Patent Application
20180178511
The present invention relates to a head unit, a liquid discharge apparatus, and a manufacturing method of a head unit.
As a liquid discharge apparatus, such as an ink jet printer which prints an image or text by discharging ink, an apparatus which uses piezoelectric elements is known. The piezoelectric elements are each provided corresponding to each of a plurality of discharge sections in a head (ink jet head), each of the piezoelectric elements is driven following a driving signal, and accordingly, a predetermined amount of ink (liquid) is discharged at a predetermined timing from a nozzle of the discharge section, and dots are formed. JP-A-2013-10228 discloses an ink jet head provided with a wiring that transfers a driving signal to a piezoelectric element via a flexible print circuit board (FPC).
In recent years, in an ink jet head (head unit), the number of nozzles (the number of driving elements, such as piezoelectric elements) that are driven at the same time has increased due to an increase in density of the nozzles, and accordingly, an electric current that flows through a driving signal transfer wiring provided on a wiring board, such as an FPC, has also increased. Meanwhile, when the number of driving modules including multiple driving elements that are electrically connected to the driving signal transfer wiring of one wiring board increases, in order to avoid an increase in size of the ink jet head, it is necessary to reduce the size of each of the driving modules, and the size of the wiring board connected to the driving module becomes extremely small. Therefore, while the electric current that flows through the driving signal transfer wiring increases, a wiring impedance increases without sufficiently ensuring a wiring area of the wiring board, and as a result, there is a possibility that transfer accuracy of the driving signal deteriorates and discharge accuracy of liquid deteriorates. In addition, since the wiring impedance increases, heat generation of the wiring board becomes large, and as a result, there is a concern that the temperature of the wiring board increases and the wiring board is damaged. Furthermore, as the heat is transmitted to the driving module from the wiring board, the temperature of the liquid discharged from the nozzle becomes higher as the nozzle becomes closer to the wiring board, and deviation of the temperature of the ink is likely to be generated between the nozzles. Then, since viscosity of the ink changes according to the temperature, there is a possibility that a difference in viscosity of the ink between the nozzles increases, a difference in amount of ink discharged from each of the nozzles increases, and discharge accuracy deteriorates. Specifically, in the ink jet head provided with the driving module including 600 or more driving elements which are aligned at a density of 300 or more driving elements per one inch, the number of driving elements which are driven at the same time increases, a large electric current is likely to flow, and thus, such a problem becomes more serious.
Furthermore, when the size of the wiring board connected to the driving module decreases, there is a problem that it becomes difficult to manufacture the ink jet head. Specifically, in the ink jet head provided with the driving module including 600 or more driving elements which are aligned at a density of 300 or more driving elements per one inch, a pitch of a connection terminal of the wiring board becomes extremely small, and thus a connection failure may occur when a connection position between the wiring board and the driving module is shifted by several μm, thereby making it more difficult to manufacture the ink jet head.
An advantage of some aspects of the invention is to provide a head unit which can reduce a concern about deterioration of a driving signal on a wiring board connected to a driving module including multiple driving elements of which the density is high, and can discharge liquid with high accuracy, and a liquid discharge apparatus provided with the head unit.
Another advantage of some aspects of the invention is to provide a head unit which can reduce a heat generation amount of a wiring board connected to a driving module including multiple driving elements of which the density is high, and a liquid discharge apparatus provided with the head unit.
Still another advantage of some aspects of the invention is to provide a head unit which can avoid a difficulty of manufacturing while a wiring board connected to a driving module including multiple driving elements of which the density is high is provided, a liquid discharge apparatus provided with the head unit, and a manufacturing method of a head unit.
The invention can be realized in the following application examples.
According to this application example, there is provided a head unit including a first board; a driving module including 600 or more driving elements which are aligned at a density of 300 or more driving elements per one inch, and a second board; and a flexible wiring board which connects the first board and the second board to each other, in which the flexible wiring board includes a first wiring layer, a second wiring layer which opposes the first wiring layer, a first output terminal which is electrically connected to a first end of the driving element, a second output terminal which is electrically connected to a second end of the driving element, a first wiring which is electrically connected to the first output terminal, a second wiring which is electrically connected to the second output terminal, and a through-hole which electrically connects the first wiring layer and the second wiring layer to each other, in which the second wiring is provided on the second wiring layer, and in which the second wiring and the second output terminal are electrically connected to each other via the through-hole.
The driving element may be, for example, a piezoelectric element, or may be a heating element. In addition, the flexible wiring board may be a single layer board, or may be a multiple layer board.
The “driving module including 600 or more driving elements which are aligned at a density of 300 or more driving elements per one inch” may be a driving module including a plurality of driving element rows in which 300 or more driving elements are aligned at a density of 300 or more driving elements per one inch, or may be a driving module including only one driving element row in which 600 or more driving elements are aligned at a density of 300 or more driving elements per one inch.
The first wiring is any one of a reference voltage signal transfer wiring which transfers the reference voltage signal and a driving signal transfer wiring which transfers a driving signal, and the second wiring may be any one of the reference voltage signal transfer wiring and the driving signal transfer wiring.
The “through-hole” is a structure including an opening portion (hole) which penetrates between the first wiring layer and the second wiring layer of the flexible wiring board, and a conductor which is provided on an inner surface thereof and electrically connects the first wiring layer and the second wiring layer to each other, and is also called “via”.
In the head unit according to the application example, since the driving module includes multiple driving elements of which the density is high, the number of driving elements which are driven at the same time increases, and on the flexible wiring board connected to the driving module, an electric current that flows through a first wiring which is electrically connected to a first end of the driving element via a first output terminal, or an electric current that flows through a second wiring which is electrically connected to a second end of the driving element via a second output terminal, are likely to increase. Meanwhile, in the head unit according to the application example, the flexible wiring board includes the first wiring layer and the second wiring layer, and as the second wiring is provided on the second wiring layer and the first wiring is provided on the first wiring layer, or as the first wiring is also provided on the second wiring layer when there is a sufficiently empty region on the second wiring layer, areas of each of the first wiring and the second wiring are sufficiently ensured. Therefore, in the head unit according to the application example, the wiring impedance of the first wiring or the second wiring which transfers the driving signal that drives the driving element is reduced, and it is possible to reduce a concern that the driving signal deteriorates on the flexible wiring board, and thus, it is possible to discharge liquid with high accuracy.
Furthermore, in the head unit according to the application example, since the flexible wiring board includes a first wiring layer and the second wiring layer, the size decreases while a large wiring region is ensured, and thus, it is possible to correspond to a decrease in size of the driving module. Therefore, it is possible to realize a small size of the head unit according to the application example.
In the head unit according to the application example, the flexible wiring board may further include a first input terminal which is electrically connected to the first wiring, and a second input terminal which is electrically connected to the second wiring, the first output terminal and the second output terminal may be provided along a first side of the flexible wiring board, and the first input terminal and the second input terminal may be provided along a second side different from the first side of the flexible wiring board.
In the head unit according to the application example, on the flexible wiring board, the first input terminal and the second input terminal, and the first output terminal and the second output terminal are provided along sides different from each other, and thus, the first wiring and the second wiring are effectively disposed. Therefore, in the head unit according to the application example, the wiring impedance of each of the first wiring and the second wiring is reduced, it is possible to reduce a concern that the driving signal deteriorates on the flexible wiring board, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the flexible wiring board may further include a control signal input terminal into which a control signal that controls discharge of liquid is input, a control signal transfer wiring which is electrically connected to the control signal input terminal, and transfers the control signal, and a control signal output terminal which is electrically connected to the control signal transfer wiring, and outputs the control signal to the driving module, and the control signal transfer wiring may be provided in a region that does not oppose a region in which the second wiring is provided, on the first wiring layer of the flexible wiring board.
In the head unit according to the application example, on the flexible wiring board, the control signal transfer wiring and the second wiring do not oppose each other, and thus, it is possible to reduce influence of noise radiated from the second wiring on the control signal. Therefore, in the head unit according to the application example, on the flexible wiring board, it is possible to reduce a concern that transfer accuracy of the control signal deteriorates, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the flexible wiring board may further include a power source voltage signal input terminal into which a power source voltage signal is input, a power source voltage signal transfer wiring which is electrically connected to the power source voltage signal input terminal, and transfers the power source voltage signal, and a power source voltage signal output terminal which is electrically connected to the power source voltage signal transfer wiring, and outputs the power source voltage signal to the driving module, the power source voltage signal transfer wiring may be provided on the second wiring layer of the flexible wiring board, and the control signal transfer wiring may be provided in a region which opposes a region in which the power source voltage signal transfer wiring is provided.
In the head unit according to the application example, on the flexible wiring board, the control signal transfer wiring and the power source voltage signal transfer wiring oppose each other, and thus, the control signal is guarded by the power source voltage signal transfer wiring. Therefore, in the head unit according to the application example, on the flexible wiring board, it is possible to reduce a concern that transfer accuracy of the control signal deteriorates, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the first wiring may be provided on the first wiring layer, and the first wiring may oppose the second wiring.
In the head unit according to the application example, an electric current path in which the electric current flows in an order of the second wiring, the driving element, and the first wiring, or in an order of the first wiring, the driving element, and the second wiring, exists, but on the flexible wiring board, the first wiring and the second wiring are provided to oppose each other on the two wiring layers different from each other, and thus, the electric current path becomes short. Therefore, in the head unit according to the application example, it is possible to reduce an impedance of the electric current path for driving the driving element, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the flexible wiring board may have a plurality of second wirings, each of which is the second wiring. The first wiring may be a reference voltage signal transfer wiring which transfers a reference voltage signal, and the plurality of the second wirings may include a first driving signal transfer wiring that transfers a first driving signal, and a second driving signal transfer wiring that transfers a second driving signal.
In the head unit according to the application example, as the first driving signal transfer wiring and the second driving signal transfer wiring are provided on the second wiring layer, and the reference voltage signal transfer wiring is provided on the first wiring layer, or as the reference voltage signal transfer wiring is also provided on the second wiring layer when there is a sufficient empty region on the second wiring layer, areas of each of the first driving signal transfer wiring, the second driving signal transfer wiring, and the reference voltage signal transfer wiring is sufficiently ensured. Therefore, in the head unit according to the application example, the wiring impedance of each of the first driving signal transfer wiring and the second driving signal transfer wiring is reduced, it is possible to reduce a concern that the first driving signal and the second driving signal deteriorate on the flexible wiring board, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, an amplitude of the first driving signal may be greater than that of the second driving signal, and on the second wiring layer, the first driving signal transfer wiring may be provided closer to an end side of the flexible wiring board than the second driving signal transfer wiring.
In the head unit according to the application example, on the flexible wiring board, the first driving signal transfer wiring which transfers the first driving signal having a large amplitude is provided on the end side, and thus, the wiring which transfers various signals is provided in the region separated from the first driving signal transfer wiring. Therefore, in the head unit according to the application example, on the flexible wiring board, it is possible to reduce influence of large noise radiated from the first driving signal transfer wiring on various signals, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the width of the first driving signal transfer wiring may be different from the width of the second driving signal transfer wiring.
In the head unit according to the application example, on the flexible wiring board, the first driving signal transfer wiring having an appropriate width that corresponds to the amplitude of the first driving signal and the second driving signal transfer wiring having an appropriate width that corresponds to the amplitude of the second driving signal, and thus, it is possible to set the wiring impedance of each of the first driving signal transfer wiring and the second driving signal transfer wiring to be an appropriate value. Therefore, in the head unit according to the application example, it is possible to reduce a concern that the transfer accuracy of the first driving signal and the second driving signal deteriorates, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, an amplitude of the first driving signal may be greater than that of the second driving signal, and the width of the first driving signal transfer wiring may be greater than the width of the second driving signal transfer wiring.
In the head unit according to the application example, on the flexible wiring board, the width of the first driving signal transfer wiring that transfers the first driving signal having an amplitude greater than that of the second driving signal, is greater than the width of the second driving signal transfer wiring that transfers the second driving signal, and thus, it is possible to further reduce the wiring impedance of the first driving signal transfer wiring. Therefore, in the head unit according to the application example, it is possible to reduce a concern that the transfer accuracy of the first driving signal and the second driving signal deteriorates, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the flexible wiring board may further include a power source voltage signal transfer wiring that transfers a power source voltage signal or a ground voltage signal transfer wiring that transfers a ground voltage signal, and on the second wiring layer, the second wiring may be provided closer to an end side of the flexible wiring board than the power source voltage signal transfer wiring or the ground voltage signal transfer wiring.
In the head unit according to the application example, on the flexible wiring board, the second wiring through which a large electric current flows is provided closer to the end side than the power source voltage signal transfer wiring or the ground voltage signal transfer wiring, and thus, various signals are guarded against the noise radiated from the second wiring by the power source voltage signal transfer wiring or the ground voltage signal transfer wiring. Therefore, in the head unit according to the application example, on the flexible wiring board, it is possible to reduce influence of large noise radiated from the second wiring on the various signals, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, both of the first driving signal transfer wiring and the second driving signal transfer wiring may be provided on the second wiring layer, and the reference voltage signal transfer wiring may be provided on the first wiring layer, and may oppose both of the first driving signal transfer wiring and the second driving signal transfer wiring.
In the head unit according to the application example, the electric current path through which the electric current flows in an order of the first driving signal transfer wiring or the second driving signal transfer wiring, the driving element, and the reference voltage signal transfer wiring, or in a reverse order, exists, but on the flexible wiring board, the first driving signal transfer wiring and the second driving signal transfer wiring, and the reference voltage signal transfer wiring are provided to oppose each other on the two wiring layers different from each other, and thus, each of the electric current paths becomes short. Therefore, in the head unit according to the application example, it is possible to reduce the impedance of each of the electric current paths for driving the driving element, and thus, it is possible to discharge liquid with high accuracy.
In the head unit according to the application example, the first wiring may be provided on the first wiring layer, and the second wiring may be thicker than the first wiring.
In the head unit according to the application example, since the second wiring is thicker than the first wiring, the impedance value per unit area becomes smaller than that of the first wiring, and a heat generation amount caused by the electric current that flows through the second wiring is more efficiently reduced. Therefore, in the head unit according to the application example, it is possible to reduce the heat generation amount of the wiring board, and thus, the wiring board is unlikely to be damaged, and it is possible to discharge liquid with high accuracy.
According to this application example, there is provided a liquid discharge apparatus including a first board; a driving module including 600 or more driving elements which are aligned at a density of 300 or more driving elements per one inch, and a second board; and a flexible wiring board which connects the first board and the second board to each other, in which the flexible wiring board includes a first wiring layer, a second wiring layer which opposes the first wiring layer, a first output terminal which is electrically connected to a first end of the driving element, a second output terminal which is electrically connected to a second end of the driving element, a first wiring which is electrically connected to the first output terminal, a second wiring which is electrically connected to the second output terminal, and a through-hole which electrically connects the first wiring layer and the second wiring layer to each other, in which the second wiring is provided on the second wiring layer, and in which the second wiring and the second output terminal are electrically connected to each other via the through-hole.
In the liquid discharge apparatus according to the application example, since the driving module includes multiple driving elements of which the density is high, the number of driving elements which are driven at the same time increases, and on the flexible wiring board connected to the driving module, the electric current that flows through the first wiring which is electrically connected to the first end of the driving element via the first output terminal, or the electric current that flows through the second wiring which is electrically connected to the second end of the driving element via the second output terminal are likely to increase. Meanwhile, in the liquid discharge apparatus according to the application example, as the flexible wiring board includes the first wiring layer and the second wiring layer, the second wiring is provided on the second wiring layer, and the first wiring is provided on the first wiring layer, or as the first wiring is also provided on the second wiring layer when there is a sufficient empty region on the second wiring layer, areas of each of the first wiring and the second wiring is sufficiently ensured. Therefore, in the liquid discharge apparatus according to the application example, the wiring impedance of the first wiring or the second wiring which transfers the driving signal that drives the driving element is reduced, it is possible to reduce a concern that the driving signal deteriorates on the flexible wiring board, and thus, it is possible to discharge liquid with high accuracy.
Furthermore, in the liquid discharge apparatus according to the application example, since the flexible wiring board includes the first wiring layer and the second wiring layer, the size decreases while a large wiring region is ensured, and thus, it is possible to correspond to a decrease in size of the driving module.
According to this application example, there is provided a manufacturing method of a head unit including a first board, a driving module including 600 or more driving elements which are aligned at a density of 300 or more driving elements per one inch, and a second board, and a flexible wiring board, in which the flexible wiring board includes a first wiring layer, a second wiring layer which opposes the first wiring layer, a first output terminal which is provided on the first wiring layer, and is electrically connected to a first end of the driving element, a second output terminal which is provided on the first wiring layer, and is electrically connected to a second end of the driving element, a first wiring which is electrically connected to the first output terminal, a second wiring which is provided on the second wiring layer, and is electrically connected to the second output terminal, a first input terminal which is electrically connected to the first wiring, a second input terminal which is electrically connected to the second wiring, and a through-hole which electrically connects the first wiring layer and the second wiring layer to each other, and in which the second wiring and the second output terminal are electrically connected to each other via the through-hole, the method including: connecting the first output terminal and the second output terminal to the second board in a second region of the first wiring layer; connecting the first input terminal and the second input terminal to the first board in a first region of the first wiring layer.
In the manufacturing method of a head unit according to the application example, on the flexible wiring board, as the second wiring provided on the second wiring layer is electrically connected to the second output terminal via the through-hole, both of the first output terminal and the second output terminal can be disposed on the first wiring layer, and the first output terminal and the second output terminal can be relatively easily connected to the second board of the driving module in the second region. Furthermore, on the flexible wiring board, as both of the first input terminal and the second input terminal are provided on the first wiring layer similar to the first output terminal and the second output terminal, in a state where the first output terminal and the second output terminal are connected to the second board of the driving module, when the first input terminal and the second input terminal are connected to the first board in the first region, it is possible to relatively easily adjust the connection position. Therefore, in the manufacturing method of the head unit according to the application example, it is possible to avoid a case where the manufacturing becomes difficult while providing the wiring board connected to the driving module including multiple driving elements of which the density is high.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, appropriate embodiments of the invention will be described in detail by using the drawings. The drawings to be used are for convenience of description. In addition, the embodiments which will be described hereinafter do not unjustly limit the contents of the invention described in the range of the claims. In addition, an overall configuration which will be described hereinafter is not necessary configuration requirement of the invention.
A printing apparatus which is an example of a liquid discharge apparatus according to the embodiment is an ink jet printer which forms an ink dot group on a printing medium, such as a paper sheet, and accordingly, prints an image (including letters or figures) which corresponds to image data, by discharging ink (liquid) in accordance with the image data supplied from a host computer on the outside.
The liquid discharge apparatus 1 of the embodiment is a line head type ink jet printer which performs printing only by transporting a recording sheet S which is an ejecting medium.
The liquid discharge apparatus 1 includes a plurality of head units 32 (ink jet head), a base 3 on which the head unit 32 is loaded, a liquid storage unit 4, such as an ink tank or the like in which the ink is stored, a first transport unit 5, a second transport unit 6, and an apparatus main body 7.
In the head unit 32, as illustrated in
In addition, in
Returning to
The liquid storage unit 4 supplies the ink to the head unit 32. In the embodiment, the liquid storage unit 4 is fixed to the apparatus main body 7, and supplies the ink to the head unit 32 via a supply pipe 8, such as a tube, from the liquid storage unit 4.
The first transport unit 5 is provided on one side in the second direction Y of the head unit 32. The first transport unit 5 includes a first transport roller 42, and a first driven roller 43 driven by the first transport roller 42. The first transport roller 42 is provided on a rear surface SP2 side on a side opposite to a landing surface SP1 on which the ink lands on the recording sheet S, and is driven by a driving force of a first driving motor 41. In addition, the first driven roller 43 is provided on the landing surface SP1 side of the recording sheet S, and nips the recording sheet S between the first driven roller 43 and the first transport roller 42. The first driven roller 43 presses the recording sheet S to the first transport roller 42 side by a biasing member, such as a spring or the like which is not illustrated.
The second transport unit 6 includes a second driving motor 71, a second transport roller 72, a second driven roller 73, a transport belt 74, and a tension roller 75.
The second transport roller 72 is driven by the driving force of the second driving motor 71. The transport belt 74 is configured of an endless belt, and is hooked to an outer circumference of the second transport roller 72 and the second driven roller 73. The transport belt 74 is provided on the rear surface SP2 side of the recording sheet S. The tension roller 75 is provided between the second transport roller 72 and the second driven roller 73, abuts against an inner circumferential surface of the transport belt 74, and imparts tension to the transport belt 74 by the biasing force of the 76, such as a spring. Accordingly, in the transport belt 74, a surface which opposes the head unit 32 between the second transport roller 72 and the second driven roller 73 is flat.
In other words, in the liquid discharge apparatus 1 of the embodiment, the recording sheet S is transported in the second direction Y by the first transport unit 5 and the second transport unit 6. In addition, by ejecting the ink from the head unit 32 and by allowing the ejected ink to land on the landing surface SP1 of the recording sheet S, the printing is performed.
In addition, in the embodiment, as the liquid discharge apparatus 1, a line head type ink jet printer in which the head unit 32 is fixed to the apparatus main body 7, and which performs the printing only by transporting the recording sheet S, is illustrated as an example. However, the embodiment of the liquid discharge apparatus 1 is not limited to the line head type. For example, the liquid discharge apparatus 1 may be a serial type ink jet printer which loads the head unit 32 on a carriage that moves in the first direction X which intersects with the second direction Y that is the transport direction of the recording sheet S, and performs the printing while moving the head unit 32 in the first direction X.
The control unit 10 includes N discharge control modules 100. N discharge control modules 100 respectively include a control signal generation section 11, a control signal conversion section 12, a control signal sending section 13, a driving data generation section 14, and a constant voltage generation section 15.
The control signal generation section 11 outputs various control signals or the like for controlling each of the portions when various signals of image data or the like are supplied from the host computer.
Specifically, the control signal generation section 11 generates n (n≥1) original printing data signals sSI1 to sSIn, n original latch signals sLAT1 to sLATn, and n original change signal sCH1 to sCHn, as a plurality of types of original control signals which control the discharge of the liquid from a discharge section 600 based on various signals from the host computer, and outputs the signals to a control signal conversion section 12 in a parallel format. In addition, in the plurality of types of original control signals, a part of the signals may be included, or other signals may be included.
The control signal conversion section 12 converts (serializes) an original printing data signal sSIi (i is any number among 1 to n), the original latch signal sLATi, and the original change signal sCHi which are output from the control signal generation section 11 respectively into one serial type original serial control signal sSi, and outputs the signal to the control signal sending section 13.
The control signal sending section 13 converts n original serial control signals sS1 to sSn output from the control signal conversion section 12 respectively into differential signals dS1 to dSn configured of two signals, and sends the differential signals dS1 to dSn to the head unit 32 via the flexible flat cable 191. In addition, the control signal sending section 13 generates a differential clock signal dClk to be used in high-speed serial data transfer of the differential signals dS1 to dSn via the flexible flat cable 191, and sends the differential clock signal dClk to the head unit 32 via the flexible flat cable 191. For example, the control signal sending section 13 generates low voltage differential signaling (LVDS) transfer type differential signals dS1 to dSn and the differential clock signals dClk, and sends the signals to the head unit 32. The LVDS transfer type differential signal can realize the high-speed data transfer since an amplitude thereof is approximately 350 mV. In addition, the control signal sending section 13 may generate various high-speed transfer types (for example, low voltage positive emitter coupled logic (LVPECL) or current mode logic (CML) other than the LVDS) of differential signals dS1 to dSn and the differential clock signal dClk, and may send the signals to the head unit 32.
Based on the various signals from the host computer, the driving data generation section 14 generates 2n pieces of driving data dA1 to dAn and dB1 to dBn which are digital data that serves as an original of the driving signal that drives the n driving modules 20 (20-1 to 20-n) included in the head unit 32, and sends the signals to the head unit 32 via the flexible flat cable 190. In the embodiment, the driving data dA1 to dAn and dB1 to dBn are digital data obtained by analogue/digital-converting a waveform (driving waveform) of the driving signals. However, the driving data dA1 to dAn and dB1 to dBn may be digital data which indicates a difference with respect to recent driving data, or may be digital data which regulates correspondence of the length of each section of which inclination is constant in the driving waveform and each of the inclinations.
n driving circuits 50-a1 to 50-an respectively generate driving signals COM-A1 to COM-An which drive each of the driving modules 20-1 to 20-n provided in the head unit 32 based on the driving data dA1 to dAn output from the driving data generation section 14. Similarly, n driving circuits 50-b1 to 50-bn respectively generate driving signals COM-B1 to COM-Bn which drive each of the driving modules 20-1 to 20-n based on the driving data dB1 to dBn output from the driving data generation section 14. For example, the driving circuits 50-a1 to 50-an and 50-b1 to 50-bn may respectively generate the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn by performing D-class amplification after digital/analogue-converting the driving data dA1 to dAn and dB1 to dBn. In addition, the 2n driving circuits 50 (50-a1 to 50-an and 50-b1 to 50-bn) may have the same circuit configuration except that the input driving data and the output driving signal are different.
The constant voltage generation section 15 generates a high power source voltage signal HVDD having a constant voltage (for example, 42 V), a low power source voltage signal LVDD having a constant voltage (for example, 3.3 V), a reference voltage signal VBS having a constant voltage (for example, 6 V), and a ground voltage signal GND having a ground voltage (0 V). In addition, the control signal generation section 11, the control signal conversion section 12, the control signal sending section 13, and the driving data generation section 14 are operated as the low power source voltage signal LVDD and the ground voltage signal GND are supplied. In addition, the driving circuits 50-a1 to 50-an are operated as the high power source voltage signal HVDD, the low power source voltage signal LVDD, the reference voltage signal VBS, and the ground voltage signal GND are supplied. The high power source voltage signal HVDD, the low power source voltage signal LVDD, the reference voltage signal VBS, and the ground voltage signal GND are transferred to the head unit 32 via the flexible flat cable 190.
In addition, in addition to the above-described processing, the control unit 10 performs processing for driving the first driving motor 41 or the second driving motor 71. Accordingly, the recording sheet S is transported in the predetermined direction.
The head unit 32 includes the n driving modules 20 (20-1 to 20-n), a control signal receiving section 24, and a control signal restoring section 25. The control signal receiving section 24 and the control signal restoring section 25 are operated as the low power source voltage signal LVDD and the ground voltage signal GND are supplied.
The control signal receiving section 24 receives the LVDS transfer type differential signals dS1 to dSn sent from the control signal sending section 13, converts the received differential signals dS1 to dSn respectively into serial control signals S1 to Sn by differential amplification, and outputs the converted serial control signals S1 to Sn to the control signal restoring section 25. In addition, the control signal receiving section 24 receives the LVDS transfer type differential clock signal dClk sent from the control signal sending section 13, converts the received differential clock signal dClk into a clock signal Clk by the differential amplification, and outputs the converted clock signal Clk to the control signal restoring section 25. In addition, the control signal receiving section 24 may receive various high-speed transfer types (for example, LVPECL or CML other than LVDS) of differential signals dS1 to dSn and the differential clock signal dClk.
The control signal restoring section 25 generates a clock signal Sck, n printing data signals SI1 to SIn, n latch signals LAT1 to LATn, and n change signals CH1 to CHn, as the plurality of types of control signals which control the discharge of the liquid from the discharge section 600, based on the serial control signals S1 to Sn converted by the control signal receiving section 24. Specifically, by restoring (deserializing) the original printing data signal sSIi, the original latch signal sLATi, and the original change signal sCHi which are included in a serial control signal Si (i is any number among 1 to n) output from the control signal receiving section 24, the control signal restoring section 25 generates a printing data signal SIi, a latch signal LATi, and a change signal CHi, and outputs the signals to a driving module 20-i. In addition, the control signal restoring section 25 performs predetermined processing (for example, dividing processing at a predetermined division ratio) to the clock signal Clk output from the control signal receiving section 24, generates the clock signal Sck synchronized with the printing data signals SI1 to SIn, the latch signals LAT1 to LATn, and the change signals CH1 to CHn, and outputs n driving modules 20 (20-1 to 20-n).
The n driving modules 20 (20-1 to 20-n) have the same configuration, and respectively include a selection control sections 220, m selection sections 230, and m discharge sections 600. In the embodiment, m is an integer which is equal to or greater than 600. The selection control section 220 is operated as the low power source voltage signal LVDD and the ground voltage signal GND are supplied. In addition, the selection section 230 is operated as the high power source voltage signal HVDD and the ground voltage signal GND are supplied.
In the driving modules 20-i (i is any number among 1 to n), the selection control section 220 instructs each of the selection sections 230 that which one of driving signals COM-Ai and COM-Bi is supposed to be selected (or which one is supposed not to be selected), by the clock signal Sck, the printing data signal SIi, the latch signal LATi, and the change signal Chi which are output from the control signal restoring section 25.
Each of the selection sections 230 selects the driving signals COM-Ai to COM-Bi in accordance with the instruction of the selection control section 220, outputs the signals to the corresponding discharge section 600 as a driving signal Vout, and applies the driving signal Vout to one end of the piezoelectric element 60 included in the discharge section 600. In addition, the reference voltage signal VBS is commonly applied to the other end of all of the piezoelectric elements 60. The piezoelectric elements 60 are provided corresponding to each of the discharge sections 600, and are displaced as the driving signal Vout (driving signals COM-Ai and COM-Bi) are applied. In addition, the piezoelectric element 60 is displaced in accordance with a potential difference between the driving signal Vout (driving signals COM-Ai and COM-Bi) and the reference voltage signal VBS, and discharges the liquid (ink). In this manner, the driving module 20-i discharges the liquid as the driving signal COM-Ai and the driving signal COM-Bi are exclusively selected and applied to one end of the piezoelectric element 60, and as the reference voltage signal VBS is applied to the other end of the piezoelectric element 60 and the piezoelectric element 60 is driven. In other words, the driving signals COM-Ai and COM-Bi are signals for discharging the liquid by driving each of the discharge sections 600.
In addition, the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn are signals of high voltage (several tens of V) since the signals are signals for driving the discharge section 600, and in the n driving circuits 50 (50-a1 to 50-n and 50-b1 to 50-bn) which generate each of the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn, power consumption is likely to increase and the temperature is likely to increase. In addition, when the waveforms of the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn change in accordance with the temperature characteristics of the driving circuits 50 (50-a1 to 50-n and 50-b1 to 50-bn), influence on discharge accuracy of the liquid from the discharge section 600 is generated. Therefore, the temperature sensor is provided in the vicinity of the driving circuits 50-a1 to 50-an and 50-b1 to 50-bn, and the discharge control module 100 may generate the driving data dA1 to dAn and dB1 to dBn such that the temperature of the waveforms of the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn is adjusted based on the output signal of the temperature sensor. In addition, even when the temperature of the waveforms of the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn is corrected, the discharge characteristics change according to the temperature characteristics of the piezoelectric element 60, and as a result, there is a case where influence on discharge accuracy of the liquid is generated. Therefore, the temperature sensor is provided in the vicinity (for example, in the vicinity of a nozzle plate 121 (refer to
As a method for forming dots on the recording sheet S, in addition to a method for forming one dot by discharging an ink droplet one time, when it is possible to discharge the ink droplets two or more times during a unit period, there is a method (second method) for forming one dot by allowing one or more ink droplets discharged during the unit period to land, and by combining the one or more landed droplets to each other, and a method (third method) for forming two or more dots by combining the two or more ink droplets to each other.
In the embodiment, according to the second method, as one dot, by discharging the ink at the maximum two times, four gradations, such as “large dot”, “medium dot”, “small dot”, and “not recorded (no dot)”, are expressed. In order to express the four gradations, in the embodiment, in the driving modules 20-i (i is any number among 1 to n), two types of driving signals COM-Ai and COM-Bi are prepared, and in each of them, a front half pattern and a rear half pattern are included in one cycle. A configuration in which, in one cycle, the driving signals COM-Ai and COM-Bi at the front half and at the rear half are selected (or not selected) in accordance with the gradation to be expressed, and are supplied to the piezoelectric element 60, is employed.
In the embodiment, the trapezoidal waveforms Adp1 and Adp2 are waveforms which are substantially the same as each other, and are waveforms in which a predetermined amount, specifically, an approximately medium amount of ink is respectively discharged from the nozzle 122 corresponding to the piezoelectric element 60 when each of the waveforms is supplied to one end of the piezoelectric element 60.
The driving signal COM-Bi has a waveform in which a trapezoidal waveform Bdp1 disposed in the period T1 and a trapezoidal waveform Bdp2 disposed in the period T2 are continuous to each other. In the embodiment, the trapezoidal waveforms Bdp1 and Bdp2 are waveforms different from each other. Among these, the trapezoidal waveform Bdp1 is a waveform for preventing an increase in viscosity of the ink by finely vibrating the ink near an open hole portion of the nozzle 122. Therefore, even when the trapezoidal waveform Bdp1 is supplied to one end of the piezoelectric element 60, the ink droplet from the nozzle 122 which corresponds to the piezoelectric element 60 is not discharged. In addition, the trapezoidal waveform Bdp2 is a waveform different from the trapezoidal waveform Adp1 (Adp2). The trapezoidal waveform Bdp2 is a waveform in which the ink of which the amount is smaller than the predetermined amount is discharged from the nozzle 122 that corresponds to the piezoelectric element 60 when the trapezoidal waveform Bdp2 is supplied to one end of the piezoelectric element 60.
In addition, any of the voltage at a start timing of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2, and the voltage at the end timing is common as a voltage Vc. In other words, the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are respectively waveforms which start at the voltage Vc and ends at the voltage Vc.
As illustrated in
The driving signal Vout which corresponds to “medium dot” has a waveform in which the trapezoidal waveform Adp1 of the driving signal COM-Ai in the period T1 and the trapezoidal waveform Bdp2 of the driving signal COM-Bi in the period T2 are continuous to each other. When the driving signal Vout is supplied to one end of the piezoelectric element 60, in the cycle Ta, the approximately medium amount and approximately small amount of ink are discharged two times from the nozzle 122 which corresponds to the piezoelectric element 60. Therefore, on the recording sheet S, each drop of ink lands and is integrated with each other, and the medium dot is formed.
The driving signal Vout which corresponds to “small dot” becomes the immediately previous voltage Vc held by capacitive properties of the piezoelectric element 60 in the period T1, and has the trapezoidal waveform Bdp2 of the driving signal COM-Bi in the period T2. When the driving signal Vout is supplied to one end of the piezoelectric element 60, in the cycle Ta, only the approximately small amount of ink is discharged in the period T2 from the nozzle 122 which corresponds to the piezoelectric element 60. Therefore, on the recording sheet S, the ink lands and the small dot is formed.
The driving signal Vout which corresponds to “not recorded” has the trapezoidal waveform Bdp1 of the driving signal COM-Bi in the period T1, and the immediately previous voltage Vc held by the capacitive properties of the piezoelectric element 60 in the period T2. When the driving signal Vout is supplied to one end of the piezoelectric element 60, in the cycle Ta, as the nozzle 122 which corresponds to the piezoelectric element 60 only finely vibrates in the period T2, the ink is not discharged. Therefore, on the recording sheet S, the ink does not land, and the dot is not formed.
The printing data signal SIi is a signal, which corresponds to each of m discharge sections 600, that includes two-bit printing data (SIH and SIL) for selecting any of “large dot”, “medium dot”, “small dot”, and “not recorded”, and has 2m bits in total.
The printing data signal SIi is serially supplied from the control signal restoring section 25 in synchronization with the clock signal Sck. A configuration for the temporary holding each two-bit printing data (SIH and SIL) included in the printing data signal SIi corresponding to the nozzle, is the shift register 222.
Specifically, a configuration in which the shift registers 222 having the number of steps which corresponds to the piezoelectric elements 60 (nozzles) are connected to each other in cascade, and the printing data signals SIi which are serially supplied are consecutively transferred in a later step according to the clock signal Sck, is employed.
In addition, when the number of piezoelectric elements 60 is m (m is a plural number), in order to distinguish the shift register 222, the shift register 222 are written as the first step, the second step, . . . and the m-th step in order from the upstream side on which the printing data signal SIi is supplied.
Each of the m latch circuits 224 latches the two-bit printing data (SIH and SIL) which is held by each of the m shift registers 222 at the rise of the latch signal LATi.
Each of the m decoders 226 decodes the two-bit printing data (SIH and SIL) latched by each of the m latch circuits 224, outputs selection signals Sa and Sb in each of the periods T1 and T2 regulated by the latch signal LATi and the change signal CHi, and regulates the selection by the selection section 230.
In addition, the logic levels of the selection signals Sa and Sb are shifted to a higher amplitude logic by a level shifter (not illustrated) than the logic levels of the clock signal Sck, the printing data signal SIi, the latch signal LATi, and the change signal CHi.
As illustrated in
The selection signal Sa from the decoder 226 is logic-inverted by the inverter 232a while being supplied to a positive control end at which a round mark is not given in the transfer gate 234a, and is supplied to a negative control end at which a round mark is given in the transfer gate 234a. Similarly, the selection signal Sb is logic-inverted by the inverter 232b while being supplied to a positive control end of the transfer gate 234b, and is supplied to a negative control end of the transfer gate 234b.
The driving signal COM-Ai is supplied to an input end of the transfer gate 234a, and the driving signal COM-Bi is supplied to an input end of the transfer gate 234b. Output ends of the transfer gates 234a and 234b are commonly connected to each other, and the driving signal Vout is output to the discharge section 600 via the common connection terminal.
When the selection signal Sa is the H level, the transfer gate 234a is conductive (ON) between the input end and the output end, and when the selection signal Sa is the L level, the transfer gate 234a is non-conductive (OFF) between the input end and the output end. The transfer gate 234b is also similarly turned On and OFF between the input end and the output end in accordance with the selection signal Sb.
Next, operations of the selection control section 220 and the selection section 230 will be described with reference to
The printing data signal SIi is serially supplied in synchronization with the clock signal Sck in each of the nozzles from the control signal restoring section 25, and is consecutively transferred in the shift register 222 which corresponds to the nozzle. In addition, when the supply of the clock signal Sck from the control signal receiving section 24 is stopped, a state where the two-bit printing data (SIH and SIL) which corresponds to the nozzle is held in each of the shift registers 222. In addition, the printing data signal SIi is supplied in order that corresponds to the final m-th step, . . . , the second step, and the first step in the shift register 222.
Here, when the latch signal LATi rises, each of the latch circuits 224 simultaneously latches the two-bit printing data (SIH and SIL) held by the shift register 222. In
The decoder 226 outputs the logic levels of the selection signals Sa and Sb by the contents illustrated in
In other words, in the decoder 226, the printing data (SIH and SIL) is (1, 1), and in a case of regulating the size of the large dot, the selection signals Sa and Sb are set to be the H and L levels in the period T1, and are also set to be the H and L levels in the period T2. In addition, in the decoder 226, the printing data (SIH and SIL) is (1, 0), and in a case of regulating the size of the medium dot, the selection signals Sa and Sb are set to be the H and L levels in the period T1, and are set to be the L and H levels in the period T2. In addition, in the decoder 226, the printing data (SIH and SIL) is (0, 1), and in a case of regulating the size of the small dot, the selection signals Sa and Sb are set to be the L and L levels in the period T1, and are set to be the L and H levels in the period T2. In addition, in the decoder 226, the printing data (SIH and SIL) is (0, 0), and in a case of regulating the not-recorded state, the selection signals Sa and Sb are set to be the L and H levels in the period T1, and are set to be the L and L levels in the period T2.
When the printing data (SIH and SIL) is (1, 1), the selection section 230 selects the driving signal COM-Ai (trapezoidal waveform Adp1) since the selection signals Sa and Sb are the H and L levels in the period T1, and selects the driving signal COM-Ai (trapezoidal waveform Adp2) since the Sa and Sb are also the H and L levels in the period T2. As a result, the driving signal Vout which corresponds to “large dot” illustrated in
In addition, when the printing data (SIH and SIL) is (1, 0), the selection section 230 selects the driving signal COM-Ai (trapezoidal waveform Adp1) since the selection signals Sa and Sb are the H and L levels in the period T1, and selects the driving signal COM-Bi (trapezoidal waveform Bdp2) since the Sa and Sb are the L and H levels in the period T2. As a result, the driving signal Vout which corresponds to “medium dot” illustrated in
In addition, when the printing data (SIH and SIL) is (0, 1), the selection section 230 selects none of the driving signals COM-Ai and COM-Bi since the selection signals Sa and Sb are the L and L levels in the period T1, and selects the driving signal COM-Bi (trapezoidal waveform Bdp2) since the Sa and Sb are the L and H levels in the period T2. As a result, the driving signal Vout which corresponds to “small dot” illustrated in
In addition, when the printing data (SIH and SIL) is (0, 0), the selection section 230 selects the driving signal COM-Bi (trapezoidal waveform Bdp1) since the selection signals Sa and Sb are the L and H levels in the period T1, and selects none of the driving signals COM-Ai and COM-Bi since the Sa and Sb are the L and L levels in the period T2. As a result, the driving signal Vout which corresponds to “not recorded” illustrated in
In addition, the driving signals COM-Ai and COM-Bi which are illustrated in
As illustrated in
The head main body 310 includes the n (here, four) driving modules 20, a holder 330 which holds the plurality of driving modules 20, a relay board 340 which is fixed to the holder 330, a supply member 350, and a fixing plate 360 which fixes the plurality of driving modules 20.
In the driving module 20, the number of rows in which the nozzles 122 which eject the ink as illustrated in
In the holder 330, on a side on which the fixing plate 360 in the third direction Z is provided, an accommodation section which is not illustrated and accommodates the plurality of driving modules 20 therein is provided. The accommodation section has a recessed shape which is open on a side on which the fixing plate 360 in the third direction Z is provided, and accommodates the plurality of driving modules 20 fixed by the fixing plate 360, and further, the opening of the accommodation section is sealed by the fixing plate 360. In other words, the driving module 20 is accommodated on the inside of a space formed by the accommodation section and the fixing plate 360.
In addition, in the holder 330, a communication flow path 332 for supplying the ink supplied from the supply member 350 to the driving module 20 is provided. Two communication flow paths 332 are provided for one driving module 20. In other words, the communication flow path 332 is provided in accordance with each row of the nozzles 122 provided in one driving module 20.
Furthermore, in the holder 330, a wiring insertion hole 333 for inserting the wiring board 400 which is electrically connected to the driving module 20 provided in the accommodation section into the surface on which the accommodation section in the third direction Z is provided and a different surface on the third direction Z side, is provided. The wiring board 400 is drawn out from the space formed by the accommodation section and the fixing plate 360 as being inserted into the wiring insertion hole 333 of the holder 330.
On a side on which the wiring board 400 of the holder 330 is drawn out, the relay board 340 is held. In the relay board 340, a driving wiring connection hole 341 which penetrates in the third direction Z which is the thickness direction is provided, and the wiring board 400 is, for example, a flexible printed board, penetrates the driving wiring connection hole 341 of the relay board 340, is bent, and is electrically connected to the relay board 340.
In addition, in the relay board 340, an insertion hole 342 is provided at a position which corresponds to the communication flow path 332 of the holder 330. The insertion hole 342 inserts a protrusion portion (not illustrated) provided in the supply member 350. The protrusion portion performs the supply of the ink to the holder 330 from the supply member 350 by connecting the supply member 350 and the communication flow path 332 of the holder 330 to each other.
Furthermore, in each of both sides in the second direction Y in the relay board 340, a control signal connector 280 and a driving signal connector 290 are provided. In addition, the relay board 340 is electrically connected to the control unit 10 via the flexible flat cables 190 and 191 (refer to
The supply member 350 is fixed to the holder 330 on the third direction Z side. In addition, in the supply member 350, a supply flow path 352 for supplying the ink supplied from the flow path member 370 to the communication flow path 332 of the holder 330, is provided. The supply flow path 352 is provided to be open on both surfaces in the third direction Z of the supply member 350. In addition, the supply flow path 352 may include a flow path of the flow path member 370, and a flow path which extends in the first direction X or in the second direction Y in accordance with the positions of the insertion hole 342 of the relay board 340 and the communication flow path 332 of the holder 330.
In addition, in the supply member 350, a through-hole 353 which penetrates in the third direction Z at the positions that correspond to each of the control signal connector 280 and the driving signal connector 290, is provided. In other words, the flexible flat cables 190 and 191 (refer to
In addition, in the fixing plate 360 which blocks the opening of the accommodation section of the holder 330, an exposure opening section 361 which exposes the nozzle 122 of each of the driving modules 20, is provided. The exposure opening section 361 in the embodiment is independently provided in each of the driving modules 20, and is sealed by the fixing plate 360 between the driving modules 20 adjacent to each other. In addition, the fixing plate 360 is fixed to the driving module 20 in the circumferential edge portion of the exposure opening section 361.
The flow path member 370 is fixed to the supply member 350 side of the head main body 310 on the third direction Z side. The flow path member 370 is configured as the plurality of filter units 390 are stacked in the second direction Y. In addition, in the filter unit 390, a plurality of flow paths 395 are provided on the inside thereof, bubbles or foreign substances which are included in the ink are removed, and the ink is supplied to the supply member 350 provided in the head main body 310.
The head unit 32 in the embodiment supplies the ink supplied from the flow path member 370 to the driving module 20 via the supply flow path 352 and the communication flow path 332 which are provided in the head main body 310. In addition, by driving the piezoelectric element 60 provided in the driving module 20-i based on the above-described driving signals COM-Ai and COM-Bi, ink droplets are ejected from the nozzle 122.
Reservoirs 118 which supply the ink to each of the pressure chambers (cavities) 130 is formed on the inside of the head case 116. Two reservoirs 118 are a space in which common ink is stored in the plurality of pressure chambers 130 which are aligned, and are formed corresponding to the rows of the pressure chambers 130 which are aligned in two rows. The reservoir 118 communicates with the communication flow path 332 (refer to
The flow path unit 115 includes the communication board 124 and the nozzle plate 121. In the communication board 124, a common liquid chamber 125 which communicates with the reservoir 118 and in which the common ink is stored in each of the pressure chambers 130, and an individual communication path 126 which individually supplies the ink from the reservoir 118 to each of the pressure chambers 130 via the common liquid chamber 125, are formed. The common liquid chamber 125 is a long empty portion which is along a nozzle row direction, and two rows of common liquid chambers 125 are formed corresponding to the rows of pressure chambers 130 which are aligned in two rows. The plurality of individual communication paths 126 are formed along the aligning direction of the pressure chamber 130 corresponding to the pressure chamber 130 in a thin plate portion of the common liquid chamber 125. The individual communication path 126 communicates with the end portion on one side in the longitudinal direction of the corresponding pressure chamber 130 in a state where the communication board 124 and the pressure chamber forming board 129 are bonded to each other.
In addition, at the positions which correspond to each of the nozzles 122 of the communication board 124, a nozzle communication path 127 which penetrates in the plate thickness direction of the communication board 124 is formed. In other words, the plurality of nozzle communication paths 127 are formed along the nozzle row direction corresponding to the nozzle row. The pressure chamber 130 and the nozzle 122 communicate with each other by the nozzle communication path 127. In a state where the communication board 124 and the pressure chamber forming board 129 are bonded to each other, the nozzle communication path 127 communicates with the end portion on the other side (a side opposite to the individual communication path 126) in the longitudinal direction of the corresponding pressure chamber 130.
The nozzle plate 121 is a board bonded to a lower surface (a surface opposite to the pressure chamber forming board 129) of the communication board 124. By the nozzle plate 121, the opening on the lower surface side of the space which is the common liquid chamber 125 is sealed. In addition, in the nozzle plate 121, the plurality of nozzles 122 are installed to be open in a shape of a straight line (shape of a row), and two nozzle rows are formed corresponding to the row of the pressure chamber 130 which are formed in two rows. The plurality of nozzles 122 (nozzle rows) which are aligned are provided at an equal interval along the first direction X at a pitch (for example, 600 dpi) which corresponds to a dot forming density from the nozzle 122 on one end side to the nozzle 122 on the other end side.
The electronic device 114 is a device having a shape of a thin plate which functions as an actuator that generates pressure fluctuation in the ink in each of the pressure chambers 130. The electronic device 114 becomes a unit in which the pressure chamber forming board 129, a vibration plate 131, the piezoelectric element 60, the sealing plate 160, and the driving IC 200 are stacked. In the driving IC 200, the selection control section 220 and the m selection sections 230 (refer to
In the pressure chamber forming board 129, a plurality of spaces which are supposed to be the pressure chamber 130 are aligned along the nozzle row direction. A lower part of the space is divided by the communication board 124, an upper part of the space is divided by the vibration plate 131, and the space configures the pressure chamber 130. Two rows of pressure chambers 130 are formed corresponding to the nozzle rows formed in two rows. Each of the pressure chambers 130 is a long space in a direction orthogonal to the nozzle row direction, the individual communication path 126 communicates with the end portion on one side in the longitudinal direction, and the nozzle communication path 127 communicates with the end portion on the other side.
The vibration plate 131 is an elastic member having a shape of a thin plate, and is stacked on the upper surface (a surface opposite to the communication board 124 side) of the pressure chamber forming board 129. An upper opening of the space which is supposed to be the pressure chamber 130 is sealed by the vibration plate 131. A part which corresponds to the upper opening of the pressure chamber 130 in the vibration plate 131 functions as a displacement unit which is displaced in a direction of being separated from or being close to the nozzle 122 in accordance with flexural deformation of the piezoelectric element 60. In other words, a region which corresponds to the upper opening of the pressure chamber 130 in the vibration plate 131 becomes a driving region 135 of which the flexural deformation is allowed. Meanwhile, a region which is out of the upper opening of the pressure chamber 130 in the vibration plate 131 becomes a non-driving region 136 in which the flexural deformation is inhibited.
In the driving region 135, the piezoelectric elements 60 are respectively stacked. Each of the piezoelectric elements 60 is formed in two rows in the nozzle row direction corresponding to the pressure chambers 130 which are aligned in two rows along the nozzle row direction. In the piezoelectric element 60, for example, a lower electrode layer 137 (individual electrode), a piezoelectric body layer 138, and an upper electrode layer 139 (common electrode) are consecutively stacked on the vibration plate 131. The piezoelectric element 60 configured in this manner is flexurally deformed in the direction of being separated from or being close to the nozzle 122 when an electric field which corresponds to the potential difference of both electrodes is imparted between the lower electrode layer 137 and the upper electrode layer 139. The end portion on the other side (an outer side in the longitudinal direction of the piezoelectric element 60) of the lower electrode layer 137 exceeds the region in which the piezoelectric body layer 138 is stacked from the driving region 135, and extends to the non-driving region 136. Meanwhile, the end portion on one side (an inner side in the longitudinal direction of the piezoelectric element 60) of the upper electrode layer 139 exceeds the region in which the piezoelectric body layer 138 is stacked from the driving region 135, and extends to the non-driving region 136 between the rows of the piezoelectric element 60.
The sealing plate 160 is a board having a shape of a flat plate which is disposed with space between the vibration plate 131 (or the piezoelectric element 60) and the board. The sealing plate 160 may function as a relay board which relays various signals, and may function as a protection board which protects the vibration plate 131 (or the piezoelectric element 60). On a second surface 142 (upper surface) on a side opposite to a first surface 141 (lower surface) which is a surface on the vibration plate 131 side of the sealing plate 160, the driving IC 200 which drives the piezoelectric element 60 is disposed. In other words, the vibration plate 131 on which the piezoelectric element 60 is stacked is connected to the first surface 141 of the sealing plate 160, and the driving IC 200 is connected to the second surface 142.
On the first surface 141 of the sealing plate 160, a plurality of bump electrodes 140 which output the driving signal from the driving IC 200 to the piezoelectric element 60 are formed. The plurality of bump electrodes 140 are formed along the nozzle row direction respectively at a position which corresponds to one lower electrode layer 137 (individual electrode) which extends to the outer side of one piezoelectric element 60, at a position which corresponds to the other lower electrode layer 137 (individual electrode) which extends to the outer side of the other piezoelectric element 60, and at a position which corresponds to the upper electrode layer 139 (common electrode) common to the plurality of piezoelectric elements 60 formed between the rows of both of the piezoelectric elements 60. In addition, each of the bump electrodes 140 is respectively connected to the corresponding lower electrode layer 137 and the upper electrode layer 139.
At least a part of the bump electrode 140 is provided on the surface of an elastic resin layer 148. The resin layer 148 is formed in a projection along the nozzle row direction on the first surface 141 of the sealing plate 160. The plurality of bump electrodes 140 which communicate with the lower electrode layer 137 (individual electrode) correspond to the piezoelectric elements 60 aligned in the nozzle row direction, and are formed along the nozzle row direction. Each of the bump electrodes 140 extends to any one of the piezoelectric element 60 side or a side opposite to the piezoelectric element 60 side from the upper part of the resin layer 148, and becomes a lower surface side wiring 147. In addition, the end portion opposite to the bump electrode 140 of the lower surface side wiring 147 is connected to a penetration wiring 145.
The plurality of bump electrodes 140 which correspond to the upper electrode layer 139 are formed on a lower surface side buried wiring 151 buried on the first surface 141 of the sealing plate 160 along the nozzle row direction. In addition, the bump electrodes 140 are formed to be the lower surface side wirings 147 which protrude on both sides in the width direction of the resin layer 148 from the upper part of the resin layer 148, and to be conductive with the lower surface side buried wiring 151. The plurality of bump electrodes 140 are formed along the nozzle row direction.
The sealing plate 160 and the pressure chamber forming board 129 are bonded to each other by a photosensitive adhesive 143 in a state where the bump electrode 140 is interposed therebetween. The photosensitive adhesives 143 are formed on both sides of each of the bump electrodes 140 in the direction orthogonal to the nozzle row direction. In addition, each of the photosensitive adhesives 143 is formed in a shape of a belt along the nozzle row direction in a state of being separated from the bump electrode 140.
On the second surface 142 of the sealing plate 160, a plurality of upper surface side buried wirings 150 which extend in the nozzle row direction are formed. Various positive voltage signals (the high power source voltage signal HVDD, the low power source voltage signal LVDD, the ground voltage signal GND, and the reference voltage signal VBS) and the driving signals COM-Ai and COM-Bi are supplied from the wiring board 400 (refer to
Furthermore, in the region on both end sides on the second surface 142 of the sealing plate 160, a bump electrode 157 into which the output signal (driving signal) from the driving IC 200 is input, is formed. At least a part of the bump electrode 157 is provided on the surface of the elastic resin layer 154. The resin layer 154 is formed in the projection which is along the nozzle row direction on the second surface 142 of the sealing plate 160. In addition, the bump electrode 157 is connected to the corresponding lower surface side wiring 147 via the penetration wiring 145.
The penetration wiring 145 is a wiring which relays the signal between the first surface 141 and the second surface 142 of the sealing plate 160. By the penetration wiring 145, the bump electrode 157 and the lower surface side wiring 147 which extend from the corresponding bump electrode 140 are electrically connected to each other, and the driving signal from the driving IC 200 is transmitted to the pressure chamber forming board 129. In this manner, the sealing plate 160 functions as the relay board which relays the driving signal from the driving IC 200 to the pressure chamber forming board 129.
The driving IC 200 is an IC chip for driving the piezoelectric element 60, and is stacked on the second surface 142 of the sealing plate 160 via an adhesive 159. On the surface on the sealing plate 160 side of the driving IC 200, a plurality of input terminals (not illustrated) which are connected to each of the bump electrodes 156 are formed, and various positive voltage signals and the driving signals COM-Ai and COM-Bi are transmitted to each of the input terminals via the bump electrode 156 from the upper surface side buried wiring 150 provided on the sealing plate 160, or various control signals are transmitted from the plurality of wirings which are not illustrated. In addition, on the surface on the sealing plate 160 side of the driving IC 200, a plurality of output terminals (not illustrated) connected to each of the bump electrodes 157 are formed, and the signals (individual driving signals which drive each of the piezoelectric elements 60) from each of the output terminals are transmitted to each of the bump electrodes 157.
The driving IC 200 is a long chip which is extremely long in the nozzle row direction, and for example, the driving signals COM-Ai and COM-Bi which are transmitted to each of the input terminals are transmitted through a wiring of which the thickness or the width is small and the length is extremely long on the inside of the driving IC 200, and are supplied to each of the selection sections 230 (refer to
The bump electrodes 157 are formed in two rows on both sides of the bump electrode 156 corresponding to the row of the piezoelectric elements 60 aligned in two rows, and in the row of the bump electrode 157, an inter-center distance (that is, pitch) (pitch of the output terminals of the driving IC 200) of the bump electrodes 157 adjacent to each other is formed to be smaller than the pitch (pitch of the nozzle 122) of the bump electrode 140. In other words, the sealing plate 160 also achieves a role of absorbing a difference between the pitch of the output terminal of the driving IC 200 and the pitch of the nozzle 122, and accordingly, it is possible to reduce the size of the driving IC 200.
In addition, the driving module 20 formed as described above introduces the ink from an ink cartridge 22 to the pressure chamber 130 via an ink introduction path, the reservoir 118, the common liquid chamber 125, and the individual communication path 126. In this state, by supplying the driving signal from the driving IC 200 to the piezoelectric element 60 via each of the wirings formed in the sealing plate 160, the piezoelectric element 60 is driven and a pressure fluctuation is generated in the pressure chamber 130. By using the pressure fluctuation, the driving module 20 ejects the ink droplets from the nozzle 122 via the nozzle communication path 127.
In addition, the discharge section 600 (refer to
Next, a configuration of the wiring board 400 will be described with reference to
As illustrated in
Although not seen in
As illustrated in
In addition, as illustrated in
The high power source voltage signal transfer wiring 431a is electrically connected to the input terminal 411a, and the high power source voltage signal transfer wiring 431b is electrically connected to the input terminal 411b. The reference voltage signal transfer wiring 432a (one example of “first wiring”) is electrically connected to the input terminal 412a, and the reference voltage signal transfer wiring 432b (one example of “first wiring”) is electrically connected to the input terminal 412b. The first driving signal transfer wiring 433a is electrically connected to the input terminal 413a, and the first driving signal transfer wiring 433b is electrically connected to the input terminal 413b. The second driving signal transfer wiring 434a is electrically connected to the input terminal 414a, and the second driving signal transfer wiring 434b is electrically connected to the input terminal 414b. The ground voltage signal transfer wiring 435 is electrically connected to the input terminal 415, the control signal transfer wiring 436 is electrically connected to the input terminal 416, and the low power source voltage signal transfer wiring 437 is electrically connected to the input terminal 417.
In addition, as illustrated in
In this manner, as the input terminal group 410 and the output terminal group 420 are disposed on the same surface of the wiring board 400, in the head unit 32 on which the relay board 340 and the sealing plate 160 are stacked, since the input terminal group 410 and the relay board 340 are connected to each other, and the output terminal group 420 and the sealing plate 160 are connected to each other, a space which is necessary for the connection becomes small, and the size of the wiring board 400 becomes small. Accordingly, a decrease in size of the head unit 32 is realized.
The output terminal 421a is electrically connected to the high power source voltage signal transfer wiring 431a, and outputs the high power source voltage signal HVDD to the driving module 20. In addition, the output terminal 421b is electrically connected to the high power source voltage signal transfer wiring 431b, and outputs the high power source voltage signal HVDD to the driving module 20. The output terminal 422a is electrically connected to the reference voltage signal transfer wiring 432a, and outputs the reference voltage signal VBS to the driving module 20. In addition, the output terminal 422b is electrically connected to the reference voltage signal transfer wiring 432b, and outputs the reference voltage signal VBS to the driving module 20. The output terminal 423a is electrically connected to the first driving signal transfer wiring 433a, and outputs the driving signal COM-Ai to the driving module 20. In addition, the output terminal 423b is electrically connected to the first driving signal transfer wiring 433b, and outputs the driving signal COM-Ai to the driving module 20. The output terminal 424a is electrically connected to the second driving signal transfer wiring 434a, and outputs the driving signal COM-Bi to the driving module 20. In addition, an output terminal 424b is electrically connected to the second driving signal transfer wiring 434b, and outputs the driving signal COM-Bi to the driving module 20. The output terminal 425 is electrically connected to the ground voltage signal transfer wiring 435, and outputs the ground voltage signal GND to the driving module 20. An output terminal 426 is electrically connected to the control signal transfer wiring 436, and outputs various control signals to the driving module 20. The output terminal 427 is electrically connected to the low power source voltage signal transfer wiring 437, and outputs the low power source voltage signal LVDD to the driving module 20.
The high power source voltage signal HVDD output from the output terminal 421a, the driving signal COM-Ai output from the output terminal 423a, and the driving signal COM-Bi output from the output terminal 424a are supplied to the selection section 230 which corresponds to each of the nozzles (discharge sections 600) included in one row (first nozzle row) of the two rows of nozzles provided in the driving module 20. In addition, the high power source voltage signal HVDD output from the output terminal 421b, and the driving signal COM-Ai output from the output terminal 423b and the driving signal COM-Bi output from the output terminal 424b are supplied to the selection section 230 which corresponds to each of the nozzles (discharge sections 600) included in the other row (second nozzle row) of the two rows of nozzles provided in the driving module 20. In other words, the output terminals 423a and 424a are electrically connected to one end (one example of “second end”) of the piezoelectric element 60 included in each of the discharge sections 600 provided corresponding to the first nozzle row, and the output terminals 423b and 424b are electrically connected to one end (one example of “second end”) of the piezoelectric element 60 included in each of the discharge sections 600 provided corresponding to the second nozzle row.
The reference voltage signal VBS output from the output terminal 422a is supplied to the discharge section 600 which discharges the liquid from each of the nozzles included in the first nozzle row. In addition, the reference voltage signal VBS output from the output terminal 422b is supplied to the discharge section 600 which discharges the liquid from each of the nozzles included in the second nozzle row. In other words, the output terminal 422a is electrically connected to the other end (one example of “first end”) of the piezoelectric element 60 included in each of the discharge sections 600 provided corresponding to the first nozzle row, and the output terminal 422b is electrically connected to the other end (one example of “first end”) of the piezoelectric element 60 included in each of the discharge sections 600 provided corresponding to the second nozzle row.
All of the ground voltage signal GND output from the output terminal 425, various control signals output from the output terminal 426, and the low power source voltage signal LVDD output from the output terminal 427, are commonly supplied to the selection control section 220.
Each of the transfer wirings is, for example, a wiring (copper plate wiring) formed by copper plating, and is covered with a resist (protection film). In addition, each of the input terminals included in the input terminal group 410 and each of the input terminals included in the output terminal group 420 are not covered with a resist, and for example, a part of a transfer wiring formed by copper plating is further formed by gold plating. In this manner, since each of the transfer wirings, each of the input terminals, and each of the output terminals do not use hard metal, such as nickel, as a material, and thus, has high flexibility, and contributes to connecting the relay board 340 and the driving module 20 to each other while saving space.
As illustrated in
The first driving signal transfer wirings 433a and 433b provided on the second surface 400b are respectively connected to the first driving signal transfer wirings 433a and 433b which are provided on the first surface 400a via through-holes 443a and 443b. Therefore, the first driving signal transfer wiring 433a (one example of “second wiring” and “driving signal transfer wiring”) provided on the second surface 400b and the input terminal 413a and the output terminal 423a which are provided on the first surface 400a, are electrically connected to each other via the through-hole 443a, the first driving signal transfer wiring 433b (one example of “second wiring” and “driving signal transfer wiring”) which are provided on the second surface 400b, and the input terminal 413b and the output terminal 423b which are provided on the first surface 400a, are electrically connected to each other via the through-hole 443b. Similarly, the second driving signal transfer wirings 434a and 434b (one example of “second wiring” and “driving signal transfer wiring”) which are provided on the second surface 400b are respectively connected to the second driving signal transfer wirings 434a and 434b which are provided on the first surface 400a via through-holes 444a and 444b. Therefore, the second driving signal transfer wiring 434a provided on the second surface 400b, and the input terminal 414a and the output terminal 424a which are provided on the first surface 400a, are electrically connected to each other via the through-hole 444a, and the second driving signal transfer wiring 434b provided on the second surface 400b, and the input terminal 414b and the output terminal 424b provided on the first surface 400a are electrically connected to each other via the through-hole 444b. Similarly, the ground voltage signal transfer wiring 435 and the low power source voltage signal transfer wiring 437 which are provided on the second surface 400b are respectively connected to the ground voltage signal transfer wiring 435 and the low power source voltage signal transfer wiring 437 which are provided on the first surface 400a via the through-holes 445 and 447. Therefore, the ground voltage signal transfer wiring 435 provided on the second surface 400b and the input terminal 415 and the output terminal 425 provided on the first surface 400a are electrically connected to each other via the through-hole 445, the low power source voltage signal transfer wiring 437 provided on the second surface 400b, and the input terminal 417 and the output terminal 427 which are provided on the first surface 400a are electrically connected to each other via the through-hole 447.
As illustrated in
In addition, in the wiring board 400, a part near the regions R1 and R2 in which the input terminal group 410 and the output terminal group 420 are respectively connected to each other, is bent in a state (refer to
With reference to
Furthermore, in the embodiment, the reference voltage signal transfer wiring 432a is provided in a region which opposes the region of the second surface 400b provided in the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a on the first surface 400a. Similarly, on the first surface 400a, the reference voltage signal transfer wiring 432b is provided in the region which opposes the region of the second surface 400b provided in the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b. In other words, the reference voltage signal transfer wiring 432a opposes both of the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432b opposes both of the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b. In each of the piezoelectric elements 60 included in the driving module 20-i, the driving signal COM-Ai and the driving signal COM-Bi are applied to one end, and the reference voltage signal VBS is applied to the other end. Therefore, the electric current path in which a large electric current flows in an order of the first driving signal transfer wiring 433a or the second driving signal transfer wiring 434a (or the first driving signal transfer wiring 433b or the second driving signal transfer wiring 434b), each of the piezoelectric elements 60, and the reference voltage signal transfer wiring 432a (or the reference voltage signal transfer wiring 432b), or in a reverse order, exists. In the embodiment, the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432a, are provided to oppose each other, the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and the reference voltage signal transfer wiring 432b, are provided to oppose each other, and thus, each of the electric current paths becomes short, and the wiring impedance of each of the electric current paths is reduced. In addition, for example, in the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b, in a case where the electric current flows in a direction toward the short side P2 from a short side P1 of the wiring board 400, the electric current flows in a direction toward the short side P1 from the short side P2 of the wiring board 400 in the reference voltage signal transfer wirings 432a and 432b. In other words, the electric current that flows through the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a and the electric current that flows the reference voltage signal transfer wiring 432a have direction different from each other, and have substantially the same total amount. Therefore, a magnetic field generated by the electric current that flows through the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and a magnetic field generated by the electric current that flows through the reference voltage signal transfer wiring 432a, offset each other. Because of the same reason, a magnetic field generated by the electric current that flows through the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and a magnetic field generated by the electric current that flows through the reference voltage signal transfer wiring 432b, offset each other. Accordingly, the wiring impedance of each of the electric current paths is further reduced. Furthermore, since a relative relationship of a position or a distance between the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432a, or a relative relationship of a position or a distance between the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and the reference voltage signal transfer wiring 432b, are the same as each other, a variation of transfer accuracy of the driving signals COM-Ai and COM-Bi is reduced.
In addition, in the embodiment, a large part of the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b is provided on the second surface 400b different from the first surface 400a on which the input terminal group 410 and the output terminal group 420 are provided. When the size of the driving module 20 is reduced, in the sealing plate 160, there is a possibility that a large area of the region to which the output terminal group 420 of the wiring board 400 is connected cannot be ensured. Therefore, in the embodiment, the plurality of output terminals included in the output terminal group 420 of the wiring board 400 are arranged at a narrow pitch, and the connection with the sealing plate 160 of the driving module 20 of which the size is reduced is possible. Meanwhile, the area of the relay board 340 is greater than the area of the sealing plate 160, and a large area of the region to which the input terminal group 410 of the wiring board 400 is connected is likely to be ensured. Therefore, in the embodiment, as illustrated in
In addition, in the sealing plate 160, since a wide area of the region to which the output terminal group 420 of the wiring board 400 is connected can be ensured, the short side P2 on which the output terminal group 420 of the wiring board 400 is provided cannot be shortened. Then, when the wiring board 400 has a constant width which is the same as the length of the short side P2, it is difficult to widen the width of each of the transfer wirings. Here, in the embodiment, except for the vicinity of the output terminal group 420, the width (a distance between a long side Q1 and the long side Q2) of the wiring board 400 is greater than the length of the short side P2. Accordingly, as illustrated in
In addition, on the first surface 400a of the wiring board 400, the input terminal group 410 and the output terminal group 420 are provided, and particularly, the plurality of output terminals included in the output terminal group 420 are arranged at a narrow pitch, and thus, the interval of the terminals or the wirings becomes extremely narrow. Then, due to the limits of processing accuracy of the terminal or the wiring, the wiring cannot be thin on the first surface 400a of the wiring board 400. Meanwhile, since the terminal is not provided on the second surface 400b of the wiring board 400, a restriction of the minimum wiring interval is small, and the first surface 400a and the relatively thick wiring can be formed. Therefore, in the embodiment, as illustrated in
In addition, with reference to
In addition, with reference to
As described above, since the wiring impedance of each of the reference voltage signal transfer wirings 432a and 432b, and the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b is reduced, the heat generation amount caused by the large electric currents that flow through each of the transfer wirings is reduced, and a temperature rise of the wiring board 400 is reduced, and thus, the wiring board 400 is unlikely to be damaged. In addition, in the head unit 32, since a heat amount transmitted to the driving module 20 from the wiring board 400 is small, a temperature gradient (a temperature deviation of each of the discharge sections 600) in the driving module 20 is small, and further, a concern about deterioration of transfer accuracy of the driving signals COM-Ai and COM-Bi is also reduced, and thus, discharge accuracy of the liquid is improved.
In addition, as illustrated in
In addition, in the embodiment, on the first surface 400a, between the reference voltage signal transfer wirings 432a and 432b and the control signal transfer wiring 436, the ground voltage signal transfer wiring 435 is provided. Therefore, various control signals transferred by the control signal transfer wiring 436 are guarded by the ground voltage signal transfer wiring 435, the influence of noise from the reference voltage signal transfer wirings 432a and 432b on various control signals is reduced, and thus, a concern about deterioration of transfer accuracy of the control signal is reduced. In addition, the low power source voltage signal transfer wiring 437 is provided between the reference voltage signal transfer wirings 432a and 432b and the control signal transfer wiring 436 such that the control signal is guarded.
Furthermore, in the embodiment, on the first surface 400a, the control signal transfer wiring 436 is provided in the region which opposes the region of the second surface 400b in which the ground voltage signal transfer wiring 435 or the low power source voltage signal transfer wiring 437 is provided. Accordingly, since various control signals are guarded by the ground voltage signal transfer wiring 435 and the low power source voltage signal transfer wiring 437 which have a constant voltage, a concern about deterioration of transfer accuracy of the control signal is further reduced.
In addition, as illustrated in
In addition, as illustrated in
Accordingly, the wiring board is unlikely to be damaged, the temperature gradient in the driving module 20 is reduced, and the discharge accuracy of the liquid is improved.
In addition, as illustrated in
In addition, the number of input terminals included in the input terminal group 410 and the number of output terminals included in the output terminal group 420 may be different from each other. For example, it is required that the wiring impedance of the first driving signal transfer wirings 433a and 433b or the second driving signal transfer wirings 434a and 434b is an appropriate wiring width (wiring impedance) which corresponds to the electric current amount. Meanwhile, as described above, the pitch of the plurality of input terminals included I the input terminal group 410 is wider than the pitch of the plurality of output terminals included in the output terminal group 420. Therefore, in order to sufficiently ensure the wiring width on the output terminal side of the first driving signal transfer wirings 433a and 433b or the second driving signal transfer wirings 434a and 434b, the number of output terminals 423a and 423b may be greater than the number of input terminals 413a and 413b.
In addition, as illustrated in
In addition, by reducing the size of the wiring board 400, it is possible to connect the relay board 340 and the sealing plate 160 of the driving module 20 of which the size is reduced to each other by the wiring board 400, and the small size of the head unit 32 is realized.
In addition, with reference to
Here, in the embodiment, the input terminal group 410 is provided on the long side Q2 which does not oppose the short side P2 provided in the output terminal group 420. In other words, on the wiring board 400, the plurality of input terminals included in the input terminal group 410 are aligned in one row in an orientation different from the direction in which the plurality of output terminals included in the output terminal group 420 are aligned in one row (that is, an orientation which is not parallel), for example, in an orthogonal direction, and each of the transfer wirings in which each of the input terminals and each of the output terminals are electrically connected to each other has a bent shape. Therefore, in a state where the short side P2 of the wiring board 400 is fixed to the sealing plate 160, in a case where the connection position of the input terminal group 410 is shifted in the direction (long side direction) toward the short side P2 from the short side P1, it is possible to perform correction at an appropriate connection position by performing the fine adjustment by using the adjustment tool. Meanwhile, even when the connection position of the input terminal group 410 is shifted in the direction toward the long side Q2 from the long side Q1, since each of the input terminals included in the input terminal group 410 is shifted in the short side direction, an appropriate connection state is ensured, and it is necessary to finely adjust the connection position.
In addition, in
In the embodiment, as illustrated in
In a state where the relay board 340 and the driving module 20 are connected to each other by the wiring board 400, while the first surface 400a on which the input terminal group 410 and the output terminal group 420 are provided are unlikely to be visually confirmed, the second surface 400b on the side opposite thereto is easily seen. Therefore, in the embodiment, in order to easily perform probing, the test pads 462a, 462b, 463a, 463b, 464a, and 464b are provided on the second surface 400b of the wiring board 400.
In addition, after the relay board 340 and the sealing plate 160 of the driving module 20 are connected to each other by the wiring board 400, when the inspection signal is supplied in order to the input terminals 412a, 412b, 413a, 413b, 414a, and 414b from the relay board 340, and the inspection signal is observed in order from the test pads 462a, 462b, 463a, 463b, 464a, and 464b, it is possible to determine that the connection between the input terminals 412a, 412b, 413a, 413b, 414a, and 414b and the relay board 340 is appropriate.
In addition, after the wiring board 400 and the sealing plate 160 of the driving module 20 are connected to each other (for example, before the wiring board 400 and the relay board 340 are connected to each other), the inspection signal is supplied in order to the output terminals 422a, 422b, 423a, 423b, 424a, and 424b from the sealing plate 160, and when the inspection signal is observed in order from the test pads 462a, 462b, 463a, 463b, 464a, and 464b, it is possible to determine that the connection between the output terminals 422a, 422b, 423a, 423b, 424a, and 424b and the relay board 340 is appropriate.
In addition, the test pad for the connection inspection which electrically connects each of the wirings to each other may be provided for the ground voltage signal transfer wiring 435, the control signal transfer wiring 436, and the low power source voltage signal transfer wiring 437. The test pads may be provided on the second surface 400b of the wiring board 400. In addition, in a case where it is not possible to ensure the region for disposing the test pad on the second surface 400b of the wiring board 400, for example, the board linked to the wiring board 400 is provided, the test pad for the connection inspection is provided on the surface which is the same as the second surface 400b of the wiring board 400 of the board, and after the connection inspection is finished, the board may be torn off from the wiring board 400.
In the embodiment, as illustrated in
Next, the inspection signal is supplied to each of the output terminals of the output terminal group 420 from each of the sealing plates 160, and the connection inspection is performed by probing each of the test pads (process S20). For the wiring board 400 and the sealing plate 160 which failed in the connection inspection, the process returns to process S10, the connection is corrected, and then, the connection inspection of process S20 may be performed again.
Next, by using the plurality of sealing plates 160 which has passed the connection inspection of process S20 and to which the wiring board 400 is connected, each of the driving modules 20 is assembled (process S30).
Next, in the region R1 of the first surface 400a of each of the wiring boards 400, the input terminal group 410 and the relay board 340 are connected to each other (process S40). In the process S40, the gripping section 440 of the wiring board 400 is gripped and the connection position is finely adjusted by using the adjustment tool.
Next, the inspection signal is supplied to each of the input terminals of the input terminal group 410 from the relay board 340, and the connection inspection is performed by probing each of the test pad (process S50). In a case of failing in the connection inspection, the process returns to process S40, the connection is corrected, and then, the connection inspection of process S50 may be performed again.
Finally, by using the relay board 340 which has passed the connection inspection of process S50 and to which the plurality of driving modules 20 are connected via the plurality of wiring boards 400, the head unit 32 is assembled (process S60).
Here, for example, since three output terminals 423a illustrated in
As described above, in the liquid discharge apparatus 1 according to the embodiment, in the head unit 32, each of the driving modules 20 includes multiple piezoelectric elements 60 of which the density is high, and thus, the number of piezoelectric elements 60 which are driven at the same time increases. Therefore, in each of the wiring boards 400 connected to each of the driving modules 20, the electric current that flows through each of the reference voltage signal transfer wirings 432a and 432b, the first driving signal transfer wirings 433a and 433b, and the second driving signal transfer wirings 434a and 434b, is likely to increase. Meanwhile, in each of the wiring boards 400, as the reference voltage signal transfer wirings 432a and 432b are provided on the first surface 400a, and as the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b are provided on the second surface 400b, areas of each of the transfer wirings are sufficiently ensured. Therefore, the wiring impedance of each of the reference voltage signal transfer wirings 432a and 432b, the first driving signal transfer wirings 433a and 433b, and the second driving signal transfer wirings 434a and 434b is reduced, and the heat generation amount caused by the electric currents that flow through each of the transfer wirings is reduced. Therefore, each of the wiring boards 400 can correspond to the small size of the driving module 20. In addition, in each of the wiring boards 400, as the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b which are provided on the second surface 400b are electrically connected to the output terminals 423a, 423b, 424a, and 424b via each of the through-holes 443a, 443b, 444a, and 444b, all of the output terminals included in the output terminal group 420 can be disposed on the first surface 400a. Therefore, the output terminal group 420 can be relatively easily connected to the sealing plate 160 of the driving module 20 in the region R2. Furthermore, in each of the wiring boards 400, since all of the input terminals included in the input terminal group 410 are also provided on the first surface 400a, in a state where the output terminal group 420 is connected to the sealing plate 160 of the driving module 20, the input terminal group 410 can be relatively easily connected to the relay board 340 in the region R1. Therefore, in the liquid discharge apparatus 1 according to the embodiment, it is possible to avoid a case where the manufacturing of the head unit 32 becomes difficult while providing the wiring board 400 connected to the driving module 20 including the multiple piezoelectric elements 60 of which the density is high.
In addition, since the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432a are provided to oppose each other, and the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and the reference voltage signal transfer wiring 432b are provided to oppose each other, each of the electric current paths is shortened, a magnetic field generated by the electric current that flows through each of the transfer wirings offset each other, and thus, the wiring impedance of each of the electric current paths is reduced.
In addition, since the relative relationship of the position or the distance between the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432a, or the relative relationship of the position or the distance between the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and the reference voltage signal transfer wiring 432b, are equal to each other, a variation of transfer accuracy of the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn is reduced.
In addition, since the thickness of the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b which are provided on the second surface 400b of the wiring board 400 is greater than the thickness of the reference voltage signal transfer wirings 432a and 432b, an impedance value per unit area is smaller than that of the reference voltage signal transfer wirings 432a and 432b. Therefore, the heat generation amount caused by the electric current that flows through each of the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b is more efficiently reduced. Therefore, in the liquid discharge apparatus 1 according to the embodiment, in the head unit 32, since it is possible to reduce the heat generation amount of each of the wiring boards 400, each of the wiring boards 400 is unlikely to be damaged, the heat amount transmitted to each of the driving modules 20 is reduced, and it is possible to discharge the liquid with high accuracy.
In addition, the width of the first driving signal transfer wirings 433a and 433b is different from the width of the second driving signal transfer wirings 434a and 434b, and the wiring impedance of each of the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b is an appropriate value. Specifically, since the width (the maximum width) of the first driving signal transfer wirings 433a and 433b is greater than the width (the maximum width) of the second driving signal transfer wirings 434a and 434b, the wiring impedance of the first driving signal transfer wirings 433a and 433b through which a larger electric current flows is reduced, and the heat generation amount of each of the wiring boards 400 is reduced.
In addition, in each of the wiring boards 400, since the input terminal group 410 and the output terminal group 420 are provided along a side on which the input terminal group 410 and the output terminal group 420 do not oppose each other, each of the transfer wirings is disposed with high efficiency, and the wiring impedance of each of the transfer wirings is reduced.
In addition, in the liquid discharge apparatus 1 according to the embodiment, in each of the wiring boards 400, since the plurality of input terminals included in the input terminal group 410 are aligned in one row in the direction orthogonal to the direction in which the plurality of output terminals included in the output terminal group 420 are aligned in one row, even after the output terminal group 420 and the sealing plate 160 of the driving module 20 are connected to each other, it is relatively easy to grip the gripping section 440 by using the adjustment tool or the like, and to finely adjust the connection position of the input terminal group 410. In addition, in the liquid discharge apparatus 1 according to the embodiment, since each of the wiring boards 400 has the wiring layers on both surfaces, the size is reduced while ensuring a large wiring region, and as the plurality of output terminals of the output terminal group 420 are arranged at a narrow pitch, the connection with the sealing plate 160 of the driving module 20 of which the size is reduced is possible, and it is possible to realize a small size of the head unit 32. In addition, in each of the wiring boards 400, since the pitch of the input terminal groups 410 is greater than the pitch of the output terminal group 420, appropriate connection between the input terminal group 410 and the relay board 340 is reliably and easily ensured. Therefore, in the liquid discharge apparatus 1 according to the embodiment, since it is possible to reduce the number of manufacturing processes of the head unit 32, and to improve yield, it is possible to reduce the manufacturing costs.
In addition, in the liquid discharge apparatus 1 according to the embodiment, in the head unit 32, the inspection signal is supplied to each of the input terminals of the input terminal group 410 from the relay board 340, and based on whether or not the inspection signal from each of the test pad is observed, it is possible to perform the connection inspection between the input terminal group 410 and the relay board 340. In addition, in a state where the input terminal group 410 is connected to the relay board 340, and the output terminal group 420 is connected to the sealing plate 160 of the driving module 20, even in a state where the first surface 400a of the wiring board 400 cannot be visually confirmed, it is possible to probe the test pad provided on the second surface 400b that can be visually confirmed, and thus, it is possible to easily perform the connection inspection of the wiring board 400.
Furthermore, in the liquid discharge apparatus 1 according to the embodiment, since all of the through-holes are provided in the region which is not bent in the wiring board 400, it is possible to reduce a concern about generation of a failure, such as a discharge defect of the head unit 32, caused by generation of a conduction failure, such as disconnection or a short circuit of a conductor in each of the through-holes, can be reduced.
Above, in the liquid discharge apparatus 1 according to the embodiment, since transfer accuracy of the driving signals COM-Ai and COM-Bi in each of the wiring boards 400 is improved, and it is possible to reduce the heat generation amount of each of the wiring boards 400, each of the wiring boards 400 is unlikely to be damaged, and it is possible to discharge the liquid from each of the head units 32 with high accuracy.
In addition, in the liquid discharge apparatus 1 according to the embodiment, the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432a are provided to oppose each other, and the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and the reference voltage signal transfer wiring 432b are provided to oppose each other. Therefore, each of the electric current paths is shortened, and the magnetic field generated by the electric current that flows through each of the transfer wirings offset each other, and thus, the wiring impedance of each of the electric current paths is reduced.
In addition, since the relative relationship of the position or the distance between the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, and the reference voltage signal transfer wiring 432a, or the relative relationship of the position or the distance between the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b, and the reference voltage signal transfer wiring 432b, are equal to each other, a variation of transfer accuracy of the driving signals COM-A1 to COM-An and COM-B1 to COM-Bn is reduced. Therefore, in the liquid discharge apparatus 1 according to the embodiment, transfer accuracy of the driving signals COM-Ai and COM-Bi in each of the wiring boards 400 is improved, and it is possible to discharge the liquid from each of the head units 32 with high accuracy.
In addition, in the liquid discharge apparatus 1 according to the embodiment, on the second surface 400b of each of the wiring boards 400, the first driving signal transfer wirings 433a and 433b are provided in the region separated from the ground voltage signal transfer wiring 435 and the low power source voltage signal transfer wiring 437. Therefore, since influence of large noise radiated from the first driving signal transfer wirings 433a and 433b through which the driving signals COM-Ai having the largest amplitude is transferred on the ground voltage signal GND or the low power source voltage signal LVDD is reduced, and it is possible to discharge the liquid from each of the head units 32 with high accuracy.
In addition, in the liquid discharge apparatus 1 according to the embodiment, in each of the wiring boards 400, since the control signal transfer wiring 436 does not oppose the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b, influence of noise radiated from the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b on various control signals is reduced.
Furthermore, in the liquid discharge apparatus 1 according to the embodiment, on the first surface 400a of each of the wiring boards 400, since the ground voltage signal transfer wiring 435 or the low power source voltage signal transfer wiring 437 is provided between the reference voltage signal transfer wirings 432a and 432b through which a large electric current flows and the control signal transfer wiring 436, various control signals transferred by the control signal transfer wiring 436 are guarded by the ground voltage signal transfer wiring 435 or the low power source voltage signal transfer wiring 437. Accordingly, in each of the wiring boards 400, influence of large noise radiated from the reference voltage signal transfer wirings 432a and 432b on various control signals is reduced. Furthermore, in each of the wiring boards 400, the reference voltage signal transfer wirings 432a and 432b, and the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b, are provided on end side, the control signal transfer wiring 436, and the ground voltage signal transfer wiring 435 and the low power source voltage signal transfer wiring 437 are provided to oppose the each other, and thus, various control signals are guarded by the ground voltage signal transfer wiring 435 and the low power source voltage signal transfer wiring 437. Therefore, in the liquid discharge apparatus 1 according to the embodiment, since a concern about deterioration of transfer accuracy of the control signal in each of the wiring boards 400 is reduced, it is possible to discharge the liquid from each of the head units 32 with high accuracy.
In addition, in the liquid discharge apparatus 1 according to the embodiment, since each of the wiring boards 400 has the wiring layers on both surfaces, the size is reduced while ensuring a large wiring region, and thus, it is possible to correspond to the small size of the driving module 20, and to realize the small size of the head unit 32.
In addition, in the liquid discharge apparatus 1 according to the embodiment, in each of the wiring boards 400, since the plurality of input terminals included in the input terminal group 410 are aligned in one row in the direction orthogonal to the direction in which the plurality of output terminals included in the output terminal group 420 are aligned in one row, even after the output terminal group 420 and the sealing plate 160 of the driving module 20 are connected to each other, it is relatively easy to finely adjust the connection position of the input terminal group 410. Therefore, in the liquid discharge apparatus 1 according to the embodiment, since it is possible to reduce the number of manufacturing processes of the head unit 32, and to improve yield, it is possible to reduce the manufacturing costs.
In the above-described embodiment, the input terminals 412a and 412b into which the reference voltage signal VBS is input, and the input terminals 413a and 413b into which the driving signal COM-Ai is input and the input terminals 414a and 414b into which the driving signal COM-Bi is input are provided on the first surface 400a of the wiring board 400. Similarly, the output terminals 422a and 422b from which the reference voltage signal VBS is output, and the output terminals 423a and 423b from which the driving signal COM-Ai is output and the output terminals 424a and 424b from which the driving signal COM-Bi is output, are provided on the first surface 400a of the wiring board 400. In addition, the reference voltage signal transfer wirings 432a and 432b through which the reference voltage signal VBS is transferred is provided on the first surface 400a, and the first driving signal transfer wirings 433a and 433b through which the driving signal COM-Ai is transferred and the second driving signal transfer wirings 434a and 434b, are provided on the first surface 400a and on the second surface 400b. In addition, the first driving signal transfer wirings 433a and 433b provided on the second surface 400b are respectively connected to the first driving signal transfer wirings 433a and 433b provided on the first surface 400a via the through-holes 443a and 443b, and the second driving signal transfer wirings 434a and 434b provided on the second surface 400b are respectively connected to the second driving signal transfer wirings 434a and 434b provided on the first surface 400a via the through-holes 444a and 444b.
Meanwhile,
In the wiring board 400 of the modification example illustrated in
In addition, in the wiring board 400 of the modification example illustrated in
In addition, in the wiring board 400 of the modification example illustrated in
In addition, even in the wiring board 400 of the modification example illustrated in
In addition, in the above-described embodiment, a case where the wiring board 400 is a single layer board and the wiring layer has two layers (the first surface 400a and the second surface 400b), is described, but the wiring board 400 may be a multiple layer board on which the plurality of boards are stacked and the wiring layer has three or more layers. In a case where the wiring board 400 has three or more wiring layers, the first surface 400a and the second surface 400b may respectively be wiring layers on the surface of the wiring board 400, and may be inner wiring layers. In addition, even in a case where the wiring board 400 has three or more wiring layers, it is desirable that the reference voltage signal transfer wiring 432a opposes both of the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a. For example, as the reference voltage signal transfer wiring 432a, and the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a are provided on the wiring layers different from each other, and the reference voltage signal transfer wiring 432a is interposed between the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a, the reference voltage signal transfer wiring 432a may oppose both of the first driving signal transfer wiring 433a and the second driving signal transfer wiring 434a. Disposition of the reference voltage signal transfer wiring 432b, and the first driving signal transfer wiring 433b and the second driving signal transfer wiring 434b is also similar. In addition, in a case where the wiring board 400 has three or more wiring layers, it is desirable that at least one wiring layer which is thicker than the wiring layer on which the output terminal group 420 is provided exists, and the first driving signal transfer wirings 433a and 433b and the second driving signal transfer wirings 434a and 434b are provided on the wiring layer which is thicker than the wiring layer provided in the output terminal group 420.
In addition, in the above-described embodiment, on the wiring board 400, a pair of the first driving signal transfer wiring 433a through which the driving signal COM-Ai is transferred and the second driving signal transfer wiring 434a through which the driving signal COM-Bi is transferred is provided on the long side Q1, and a pair of the first driving signal transfer wiring 433b through which the driving signal COM-Ai is transferred and the second driving signal transfer wiring 434b through which the driving signal COM-Bi is transferred is provided on the long side Q2. In other words, on the wiring board 400, two pairs of the first driving signal transfer wiring and the second driving signal transfer wiring are provided, but not being limited thereto, only one pair of these may be provided, or three or more pairs may be provided.
In addition, in the above-described embodiment, based on the various control signals, the driving IC 200 outputs the driving signal Vout to each of the piezoelectric elements 60 by combining the trapezoidal waveforms (driving waveforms) Adp1 and Adp2 of the driving signal COM-Ai and the trapezoidal waveforms (driving waveforms) Bdp1 and Bdp2 of the driving signal COM-Bi, but the invention is not limited thereto. For example, four driving circuits respectively generate a first driving signal having a driving waveform which corresponds to “large dot”, a second driving signal having a driving waveform which corresponds to “medium dot”, a third driving signal having a driving waveform which corresponds to “small dot”, and a fourth driving signal having a driving waveform which corresponds to “not recorded”. The driving IC 200 may output the driving signal Vout to each of the piezoelectric elements 60 by selecting any one of the first driving signal, the second driving signal, the third driving signal, and the fourth driving signal, based on various control signals.
In addition, for example, the driving circuit may generate a driving signal COMi having a plurality of driving waveforms Adp, Bdp, and Cdp as illustrated in
In addition, in the above-described embodiment, the control unit 10 and each of the head units 32 are connected to each other by the two flexible flat cables 190 and 191, but may be connected to each other by one flexible flat cable, or may be connected to each other by three or more flexible flat cable. Otherwise, various signals may be wirelessly transferred to each of the head units 32 from the control unit 10.
In addition, in the above-described embodiment, an example in which the piezo-type liquid discharge apparatus in which the driving circuit drives the piezoelectric element (capacitive load) that serves as the driving element is described, but the invention can also be employed in a liquid discharge apparatus in which the driving circuit drives a driving element other than the capacitive load. An example of the liquid discharge apparatus includes a thermal type (bubble type) liquid discharge apparatus in which a driving circuit drives a heat generation element (for example, resistance) that serves as a driving element, and which discharges liquid by using bubbles generated as the heat generation element is headed.
Above, the embodiment and the modification examples are described, but the invention is not limited to the embodiment and the modification examples, and can be realized in various aspects within a range that does not depart from the spirit. For example, it is also possible to appropriately combine the above-described embodiment and each of the modification examples with each other.
The invention practically has a configuration which is the same as the configuration described in the embodiment (for example, a configuration which has the same functions, method, and results, or a configuration which has the same purpose and effects). In addition, the invention has a configuration in which a part which is not essential in the configuration described in the embodiment is replaced. In addition, the invention has a configuration which achieves an action effect or a configuration which can achieve the same purpose which are the same as those of the configuration described in the embodiment. In addition, the invention has a configuration obtained by adding a known technology to the configuration described in the embodiment.
The entire disclosure of Japanese Patent Application No. 2016-248691, filed Dec. 22, 2016, No. 2017-191774, filed Sep. 29, 2017, Application No. 2017-191775, filed Sep. 29, 2017, Application No. 2017-191776, filed Sep. 29, 2017 are expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-248691 | Dec 2016 | JP | national |
| 2017-191774 | Sep 2017 | JP | national |
| 2017-191775 | Sep 2017 | JP | national |
| 2017-191776 | Sep 2017 | JP | national |
