Patent Application
20200269580
The present application is based on, and claims priority from JP Application Serial Number 2019-033859, filed Feb. 27, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates a head unit and a liquid discharge apparatus.
Ink jet printers that include a liquid discharge head for discharging ink in accordance with driving of piezoelectric elements are known. The liquid discharge head described in JP-A-2018-039174 has a drive IC that is disposed on a plate-shaped member for protecting piezoelectric elements.
The arrangement of the drive IC, which is used to select to supply or not to supply a drive signal to each piezoelectric element, disposed on the plate-shaped member allows the high-density nozzles as compared to arrangements in which a drive IC and piezoelectric elements are electrically coupled by using a Chip on Film (COF) or the like. In this arrangement, however, the drive IC and nozzles are close to each other and the heat generated by the drive IC may change the viscosity of ink, resulting in lower print quality.
According to an aspect of the present disclosure, a head unit includes piezoelectric elements configured to be driven in accordance with a drive signal to discharge liquid from nozzles, a protection plate protecting the piezoelectric elements, a head chip including a selection circuit disposed on the protection plate, the selection circuit being configured to select to supply or not to supply the drive signal to the piezoelectric elements, a heat sink, and a thermal conductor coupling the head chip and the heat sink.
Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the attached drawings. In the drawings, the dimensions and scale of components may be appropriately changed from actual ones, and may be schematically illustrated to facilitate understanding. It is to be understood that in the following description, the scope of the present disclosure is not limited to the embodiment unless such limitations are explicitly mentioned. “Parallel” as used in this specification is not limited to completely parallel, and two objects may be inclined to each other within a range of plus or minus 5 degrees.
A transport direction of a medium M on a platen 25, which will be described below, is parallel to the +y direction. A nozzle array direction along a first array L1 of nozzles N, which will be described below, is parallel to the +y direction. A “discharge direction” in which the nozzles N, which will be described below, discharge ink is parallel to the +z direction. A direction in which head chips 3 of a head unit 10, which will be described below, are arranged, that is, an “arrangement direction” of a first head chip 3a and a second head chip 3b, which will be described below, is parallel to the +x direction. An “intersecting direction” that intersects the discharge direction is parallel to the +x direction.
The liquid discharge apparatus 100 illustrated in
The liquid discharge apparatus 100 includes a control unit 1, a transport mechanism 2, and the head unit 10. The liquid discharge apparatus 100 is a line printer that performs printing with the fixed head unit 10 while transporting a medium M.
The control unit 1 includes, for example, a processing circuit such as a central processing unit (CPU) or a field-programmable gate array (FPGA), and a storage circuit such as a semiconductor memory. The control unit 1 performs overall control of components in the liquid discharge apparatus 100.
The transport mechanism 2 transports a medium M in the +y direction under the control of the control unit 1. The transport mechanism 2 includes a transport roller 21, a following roller 22, and a transporting motor 23. The transporting motor 23 is a drive source for driving the transport roller 21. By the transporting motor 23, the transport roller 21 is rotated. The following roller 22 follows the rotation of the transport roller 21 and rotates. By the rotation of the transport roller 21 and the following roller 22, a medium M is transported on the platen 25, which is disposed on the +z axis side with respect to the head unit 10.
The head unit 10 is a line head that has arrayed nozzles N. The length of the head unit 10 in the +x direction is equal to or longer than the length of a medium M in the +x direction. The head unit 10 discharges ink supplied from the nozzles N toward a medium M under the control of the control unit 1. The discharge of ink by the head unit 10 and the transport of the medium M by the transport mechanism 2 form a desired image on the medium M.
The controller 11 controls operations of the components in the liquid discharge apparatus 100. To the controller 11, print data is supplied from an external device such as a host computer (not illustrated). The print data is data of an image to be formed by the liquid discharge apparatus 100. Based on the print data, the controller 11 generates various signals for controlling operations of the components in the liquid discharge apparatus 100. The signals include, for example, a transport control signal Cr1, a waveform-designating signal dCom, and a print signal SI.
The transport control signal Cr1 is a signal for controlling the operation of the transport motor driver 13. The waveform-designating signal dCom is a digital voltage signal for designating a waveform of a drive signal Com for driving the head unit 10. The print signal SI is a digital voltage signal for designating whether or not to supply a drive signal Com. The print signal SI is a signal for determining whether or not to discharge ink from each of discharge sections 301 of the head unit 10 and for determining an amount of discharge. The controller 11 receives or generates, other than the print signal SI, various control signals such as a clock signal and a latch signal.
The head unit 10 includes drive-signal generation circuits 51 and head chips 3. The drive-signal generation circuit 51 includes a digital-to-analog (D/A) conversion circuit. The drive-signal generation circuit 51 generates an analog drive signal Com based on a waveform-designating signal dCom. The drive signal Com includes a first drive signal Com-A and a second drive signal Com-B. Each of the first drive signal Com-A and the second drive signal Com-B is an analog voltage signal for driving piezoelectric elements 34 in a head chip 3.
Each head chip 3 includes discharge sections 301 and a selection circuit 302. Each discharge section 301 includes a piezoelectric element 34, which is an example “drive element”. The piezoelectric element 34 is driven such that ink is discharged from nozzles N. The selection circuit 302 selects to supply or not to supply a drive signal Com to piezoelectric elements 34 in accordance with a print signal SI, and the like. The selection circuit 302 generates an individual drive signal Vin for driving each of the piezoelectric elements 34 based on various signals such as a drive signal Com and a print signal SI. The selection circuit 302 includes a plurality of sets each including, for example, a shift register, a latch circuit, a decoder, and transmission gates that function as a switch. One set is provided for one piezoelectric element 34. One of two transmission gates correspond to the first drive signal Com-A. The other one corresponds to the second drive signal Com-B.
2-1a. Flow Channel Unit 400
As illustrated in
To the flow channel structure 40, an ink supply member 401 such as a tube is coupled. One end of the ink supply member 401 is coupled to the liquid container 9. The flow channel structure 40 has a distribution flow channel 491 for distributing the ink supplied from the liquid container 9 to head chips 3. The distribution flow channel 491 is a part of the liquid flow channel 49. The flow channel structure 40 may have a gas flow channel through which gas such as air flows. The flow channel structure 40 may have a pressure adjustment section that changes the pressure in the distribution flow channel 491 by the air from the gas flow channel.
The supporting member 4 supports the head chips 3. The supporting member 4 includes holders 41, the fixing plates 42, and a base 43. As illustrated in
Each holder 41 supports a plurality of head chips 3 together. Each holder 41 in this embodiment supports six head chips 3 together. The holders 41 are disposed along the +x direction. The holder 41 has a recessed portion 411 that is open on the +z side. In the recessed portion 411, six head chips 3 are disposed. As illustrated in
The fixing plate 42 illustrated in
As illustrated in
The supporting member 4 functions as a “heat transmission member” that transmits heat generated in the head chips 3 to the heat sink 60, which will be described below. The supporting member 4 is made of a material that has high thermal conductivity. The supporting member 4 has higher thermal conductivity than that of air. In particular, the holders 41 and the base 43 have high thermal conductivity. The holders 41 and the base 43 may each be made of a metal material, specifically, aluminum. Aluminum has high thermal conductivity among metal materials. The holders 41 and the base 43 are each formed, for example, by die casting. The fixing plate 42 is made of, for example, a highly rigid metal such as a stainless steel.
The number of the head chips 3 that are supported by one holder 41 is not limited to six, and any number of the head chips 3 may be supported. The number of the holders 41 that are supported by the base 43 is not limited to six, and any number of the holders 41 may be supported.
2-1b. Heat Sink 60
As illustrated in
The heat sink 60 is used to dissipate or absorb heat of the heat chips 3. The heat sink 60 efficiently release heat generated in the head chips 3 to the outside of the head chips 3. The heat sink 60 is made of a material that has high thermal conductivity. The heat sink 60 may be made of a metal material, for example, aluminum. The length of the heat sink 60 along the +x direction is equal to or substantially equal to the length of the base 43 along the +x direction. The length of the heat sink 60 may be shorter or longer than the length of the base 43 along the +x direction.
2-1c. Circuit Board 50
The circuit boards 50 each having a rectangular plate shape are disposed on the −y axis side with respect to the head chips 3. In this embodiment, one circuit board 50 is provided for one holder 41. Accordingly, for six head chips 3, one circuit board 50 is provided. Each circuit board 50 is fixed to the flow channel unit 400 by screwing with a plurality of screws 502. In this embodiment, the circuit boards 50 are fixed to the flow channel structure 40. The circuit boards 50 may be fixed to the base 43.
As illustrated in
2-1d. Cover 70
As illustrated in
The cover 70 has a first inlet 701, a second inlet 702, and an outlet 703. In this embodiment, a plurality of the first inlets 701, the second inlets 702, and the outlets 703 are disposed respectively.
The first inlets 701 and the second inlets 702 are example “inlets”. The first inlets 701 and the second inlets 702 are holes for drawing air outside the cover 70 into the space S. The first inlets 701 are disposed on the +y axis side with respect to the heat sink 60. The second inlets 702 are disposed on the −y axis side with respect to the circuit board 50. The first inlets 701 and the second inlets 702 are each provided above the nozzles N. The first inlets 701 and the second inlets 702 may each be disposed below the nozzles N; however, the first inlets 701 and the second inlets 702 disposed above can prevent ink discharged from the nozzles from entering the space S.
The outlets 703 are holes for discharging air in the cover 70, that is, the space S to the outside of the cover 70. One outlet 703 is provided for one fan 80. The outlets 703 are provided above the first inlets 701 and the second inlets 702. The outlets 703 are provided above the head chips 3, the flow channel unit 400, the heat sink 60, and the circuit boards 50.
2-1e. Fan 80
As illustrated in
The head chip 3 illustrated in
2-2a. Nozzle Plate 311
The nozzle plate 311 has nozzles N for discharging ink. Each nozzle N is a through hole in the nozzle plate 311. The nozzles N are arranged at predetermined intervals. In the drawings, the nozzles N are arranged in two lines. The nozzles N are, specifically, arranged in a first line L1 along the +y direction and a second line L2 along the +y direction. The nozzle plate 311 is made of, for example, a silicon single-crystal substrate. The nozzles N are formed by processing the silicon substrate, for example, by etching.
2-2b. Flow Channel Plate 312
The flow channel plate 312 is disposed on the nozzle plate 311. The flow channel plate 312 includes two openings 3121, second flow channels 3123, and third flow channels 3124. As illustrated in
As illustrated in
2-2c. Pressure Chamber Plate 313
As illustrated in
Each of the flow channel plate 312 and the pressure chamber plate 313 is formed by processing a silicon single crystal substrate, for example, by etching. The nozzle plate 311, the flow channel plate 312, and the pressure chamber plate 313 may be made of, for example, glass, ceramics, metal, or resin.
2-2d. First Vibration Absorbing Plate 32
As illustrated in
2-2e. Diaphragm 33
As illustrated in
2-2f. Piezoelectric Element 34
As illustrated in
As previously mentioned, the head chip 3 has a plurality of discharge sections 301. Each discharge section 301 has one piezoelectric element 34, a part of the diaphragm 33 that is in contact with the piezoelectric element 34, one first flow channel 3122, one second flow channel 3123, one pressure chamber 3131, and one third flow channel 3124. In the head chip 3, in each discharge section 301, ink is discharged from the nozzle N by the driving of the piezoelectric element 34.
2-2g. Protection Plate 35
As illustrated in
As illustrated in
2-2h. Case 36
As illustrated in
The two reservoirs R are reservoirs for storing ink. The reservoirs R are space in the case 36. The reservoirs R are open on a surface on the +z axis side and a surface on the −z axis side of the case 36 respectively. One reservoir R communicates with one opening 3121. On the surface of the case 36 on the +z axis side, two inlets 363 through which the ink supplied from the liquid container 9 via the liquid flow channel 49 is supplied are provided. One inlet 363 communicates with one reservoir R.
2-2i. Second Vibration Absorbing Plate 37
The second vibration absorbing plate 37 is disposed on the case 36 to seal the opening of the case 36 on the −z axis side. The second vibration absorbing plate 37 absorbs pressure fluctuations of the ink in the reservoir R. The second vibration absorbing plate 37 has, for example, a flexible elastic film and a support plate that supports the elastic film, similarly to the first vibration absorbing plate 32.
In the head chip 3, as indicated by arrow A13 or arrow A14 in
As illustrated in
The wiring member 38 includes connection wires 381. The connection wires 381 are electrically coupled to the selection circuit 302 via the wires 304 on the protection plate 35. The connection wires 381 are also electrically coupled to the drive-signal generation circuit 51 in the circuit board 50. Accordingly, the wiring member 38 electrically couples the selection circuit 302 and the drive-signal generation circuit 51. The wiring member 38 supplies a drive signal Com from the drive-signal generation circuit 51 to the selection circuit 302.
As illustrated in
The first head chip 3a and the second head chip 3b are arrayed in the +x direction with a pitch D3, which is a “predetermined pitch”. The first head chip 3a and the second head chip 3b are aligned, specifically, in a direction a center O3 of the first head chip 3a and a center O3 of the second head chip 3b are aligned. The pitch D3 is a distance between the center O3 of the first head chip 3a and the center O3 of the second head chip 3b. The pitch D3 is, accordingly, a center distance between the first head chip 3a and the second head chip 3b. The center O3 of the first head chip 3a is a geometric center of the first head chip 3a. The same applies to the center O3 of the second head chip 3b. In this embodiment, all of the head chips 3 are aligned along the +x direction with the pitch D3.
On each head chip 3, as described above, the wiring member 38 is disposed. When the wiring member 38 that is disposed on the first head chip 3a is a first wiring member 38a and the wiring member 38 disposed on the second head chip 3b is a second wiring member 38b, the first wiring member 38a and the second wiring member 38b are arranged in the +x direction. The first wiring member 38a and the second wiring member 38b are aligned along the direction the first head chip 3a and the second head chip 3b are aligned.
The first wiring member 38a is disposed at one end 309 of the first head chip 3a in the +y direction and similarly, the second wiring member 38b is disposed at one end 309 of the second head chip 3b in the +y direction. In this embodiment, each wiring member 38 is disposed at one end 309 of a corresponding head chip 3 in the +y direction. Consequently, all the wiring members 38 are aligned along the +x direction.
On the circuit board 50, the wiring members 38 are disposed. One drive-signal generation circuit 51 is provided for one wiring member 38. One drive-signal generation circuit 51 is provided for one head chip 3 accordingly. With this structure, a drive signal Com that is generated in accordance with characteristics of each head chip 3 can be supplied to each corresponding head chip 3, and thereby the print quality can be increased. The connection wire 381 of the wiring member 38 and the drive-signal generation circuit 51 that corresponds to the connection wire 381 are coupled via a wire (not illustrated) of the circuit board 50.
The circuit areas S5 are located along the +x direction. Consequently, the drive-signal generation circuits 51 are located along the +x direction. The wiring areas S3 are located along the +x direction. Consequently, the wiring members 38 are located along the +x direction as previously mentioned. The circuit areas S5 are aligned with an equal pitch D5. In this embodiment, the pitch D5 is substantially equal to the pitch D3 of the head chip 3, but may be a pitch different from the pitch D3. The pitch D5 is a center distance between adjacent circuit regions S5. A width W5 of the circuit area S5 is narrower than the pitch D3 of the head chip 3. The width W5 is a width of the circuit area S5 in the +x direction. The width W5 is, accordingly, the length of the circuit area S5 along the alignment direction of the first head chip 3a and the second head chip 3b.
The first drive-signal generation circuit 51A is located on the −z axis side with respect to the second drive-signal generation circuit 51B. The first drive-signal generation circuit 51A is disposed at a position farther from the head chip 3 than the second drive-signal generation circuit 51B accordingly. One first drive-signal generation circuit 51A, one second drive-signal generation circuit 51B, and one wiring member 38 are aligned along the +z direction. Accordingly, high-density head chips 3 can be provided as compared to head chips 3 that are not aligned along the +z direction.
The first drive-signal generation circuit 51A and the second drive-signal generation circuit 51B each include a large scale integration (LSI) circuit 511, which serves as a modulation circuit, an amplifier circuit 512, and a low pass filter (LPF) 513.
The LSI 511 includes a digital-to-analog converter (DAC) and a gate driver. To the LSI 511, a waveform specifying signal dCom is input from the controller 11. The LSI 511 converts the waveform-designating signal dCom into an analog signal and based on the waveform-designating signal dCom, generates a modulating signal for driving a transistor in the amplifier circuit 512. The amplifier circuit 512 includes a transistor on a high side and a transistor on a low side. As example transistors, n-channel type field effect transistors (FETs) may be used. The amplifier circuit 512 amplifies a modulating signal that is input from the LSI 511 to generate an amplified signal. The LPF 513 includes a coil. The LPF 513 smooths the amplified signal input from the amplifier circuit 512 to generate a drive signal Com.
The LPF 513, the amplifier circuit 512, and the LSI 511 are aligned in this order from the head chip 3 side along the −z direction. Accordingly, the LPF 513 is closest to the head chip 3 and the LSI 511 is farthest from the head chip 3. This arrangement allows the LPF 513, the amplifier circuit 512, and the LSI 511 to be aligned in a line. Accordingly, the further reduced width W5 of the circuit area S5 can be achieved, and the high-density head chips 3 can be provided. The transistor on the high side and the transistor on the low side in the amplifier circuit 512 are mounted in one package. Accordingly, the reduced width W5 of the circuit area S5 can be achieved as compared to a transistor on a high side and a transistor on a low side that are mounted in separate packages.
As described above, the head unit 10 includes the head chips 3, the circuit boards 50, the connection wires 381, and the flow channel unit 400. The head chips 3 each include the piezoelectric elements 34, and ink is discharged from the nozzles N by the driving of the piezoelectric elements 34. The circuit board 50 has the drive-signal generation circuit 51 that generates a drive signal Com for driving the piezoelectric elements 34. The wiring member 381 electrically couples the head chip 3 and the drive-signal generation circuit 51. The flow channel unit 400 has the liquid flow channel 49 for supplying ink to the head chips 3. The head chips 3 and the circuit boards 50 are fixed to the flow channel unit 400.
The head chips 3 and the circuit boards 50 are fixed to the same flow channel unit 400, and this structure allows to reduce the distance between each head chip 3 and each circuit board 50 as compared to head chips 3 and circuit boards 50 that are not fixed to the same unit, and thus, the length of the connection wire 381 can be reduced. The head chips 3 and the circuit boards 50 are fixed to the same flow channel unit 400, and thereby the head unit 10 that has the head chips 3 and the circuit boards 50 can be implemented. With this structure, the distance between each head chip 3 and each circuit board 50 can be reduced as compared to a control unit 1 that has circuit boards 50, and thus the length of the connection wire 381 can be reduced. With this structure, noise on the connection wire 381 due to a long wiring length can be reduced, and thereby the variations in the drive waveform of a drive signal Com can be reduced, and print quality degradation due to the noise can be suppressed.
Examples of the noise include increased magnetic flux due to an increase in inductance of the connection wire 381, a change in magnetic flux due to mutual inductance of the connection wires 381, and variations in the connection wire 381. For example, the inductance of the connection wire 381 increases as the length of the connection wire 381 increases, and an overshoot may occur in a drive waveform. As a result, a discharge malfunction may occur. The head unit 10, however, has the short connection wires 381, and thus a discharge malfunction can be prevented or reduced.
Furthermore, the flow channel unit 400 to which the head chips 3 and the circuit boards 50 are fixed eliminates separate members to which the head chips 3 and the circuit boards 50 are to be fixed. Accordingly, an increase in size of the head unit 10 can be prevented.
The high-densely nozzles N need the increased number and density of the connection wires 381, and this may cause noise and print quality deterioration. However, in the head unit 10, the distance between each head chip 3 and each circuit board 50 is short as previously described, and thus such effects of noise can be effectively reduced. In particular, a head chip 3 that has 1000 or more nozzles N with a pitch of 500 dpi or more can effectively prevent the head unit 10 from printing at a low print quality level. For example, the number of nozzles N in the head unit 10 may be less than 1000 and a pitch between the nozzles N may be 500 dpi.
On the connection wires 381, the wiring member 38 is disposed as described above. In some embodiments, the wiring member 38 is a flexible printed circuit (FPC). Among flexible wiring boards, flexible printed circuits have high flexibility. Consequently, a flexible printed circuit that is used as the wiring member 38 can stably and electrically couple the head chip 3 and the circuit board 50 by the connection wires 381 when the extending surface of the head chip 3 and the extending surface of the circuit board 50 intersect each other as illustrated in
The head chip 3 and the circuit board 50 arranged such that the extending surface of the head chip 3 and the extending surface of the circuit board 50 intersect each other can increase the flexibility in the arrangement of the wiring in the circuit board 50 as compared to an arrangement in which a head chip 3 and a circuit board 50 are parallel and face each other. With this structure, the drive-signal generation circuits 51 can be disposed at a high density.
As illustrated in
The circuit board 50 is fixed to the flow channel unit 400 at some points. The circuit board 50 according to the embodiment is fixed to the flow channel unit 400 with the screws 502. The circuit board 50 fixed at some points can be stably fixed to the flow channel unit 400 as compared to, for example, a circuit board 50 that is fixed to the flow channel unit 400 at one point. Consequently, this structure can further suppress print quality degradation. The circuit board 50 may be fixed to the flow channel unit 400 at only one point.
As described above, the first drive-signal generation circuit 51A and the second drive-signal generation circuit 51B are aligned along the +z direction. With this structure, the width W5 of the circuit area S5 can be reduced as compared to an arrangement in which a first drive-signal generation circuit 51A and a second drive-signal generation circuit 51B in one drive-signal generation circuit 51 are aligned in the +x direction. Accordingly, the head chips 3 can be disposed at a high density, and thus many nozzles N can be disposed at a high density. Furthermore, even though the head chips 3 are disposed at a high density, the head unit 10 can effectively suppress print quality degradation due to noise, and thus the head unit 10 with high resolution and high printing accuracy can be implemented.
As previously mentioned, the width W5 of the circuit area S5 is narrower than the pitch D3. The drive-signal generation circuits 51 that have the width W5 narrower than the pitch D3 implement the head unit 10 with high resolution and high printing accuracy.
As described above, the first drive-signal generation circuit 51A and the second drive-signal generation circuit 51B are aligned along the +z direction, and thereby the width W5 that is narrower than the pitch D3 can be achieved. When the first drive-signal generation circuit 51A and the second drive-signal generation circuit 51B are not aligned along the +z direction, if a width W2 of the circuit area S5 is narrower than the pitch D3, the head unit 10 with high resolution and high printing accuracy can be achieved.
As illustrated in
As previously mentioned, the head chip 3 includes the selection circuit 302 that has the transmission gates. The amount of heat generated by the head chips 3 is greater than that by a structure that has no selection circuit 302. Accordingly, the heat sink 60 is disposed via the supporting member 4 to effectively suppress the print quality degradation due to the heat generated by the head chips 3 including the selection circuits 302. Furthermore, this structure suppresses shortening of the life of the selection circuit 302 and other components due to heat.
As illustrated in
When viewed from the +z direction, a part or all of the head chips 3 may overlap the circuit boards 50 or the heat sink 60. The arrangement of the wiring members 38 is not limited to the arrangement illustrated in
As previously mentioned, the head unit 10 includes the cover 70 that accommodates a part of the head chips 3 and the fans 80 that move the air between the cover 70 and the head chips 3. In this embodiment, specifically, the cover 70 allows the movement of the air in the space S between the cover 70 and the head chips 3, the heat sink 60, the circuit boards 50, and the flow channel unit 400. The fans 80 can force the air in the space S to flow. As the air flows, heat is conducted from the head chips 3, which are heating elements, to the air in the space S. The convection dissipates the heat of the head chips 3, and the temperature rise of the head chips 3 can be suppressed, suppressing the temperature rise of the ink in the head chips 3. Consequently, this structure can suppress print quality degradation due to heat. Furthermore, this structure suppresses shortening of the life of the selection circuits 302 and other components due to heat. The fans 80 reduce temperature unevenness in the space S and thus variations in temperature of the head chips 3 can be reduced.
As previously mentioned, the head chip 3 includes the selection circuit 302 that has the transmission gates. The amount of heat generated by the head chips 3 each having the selection circuit 302 is greater than that by a structure that has no selection circuit 302 as mentioned above. Accordingly, the fans 80 are disposed to effectively suppress the print quality degradation due to the heat generated by the head chips 3 each having the selection circuit 302. Furthermore, this structure suppresses shortening of the life of the selection circuits 302 and other components due to heat. The fans 80 reduce temperature unevenness in the space S and thus variations in temperature of the head chips 3 can be reduced.
The cover 70 may accommodate a part or all of the head chips 3 as long as the space S can be provided between the cover 70 and the head chips 3. Similarly, the cover 70 may accommodate a part or all of the heat sink 60 as long as the space S can be provided between the cover 70 and the heat sink 60. The same applies to the flow channel unit 400 and the circuit boards 50.
As illustrated in
Furthermore, the head chip 3 has 1000 or more nozzles N with a pitch of 500 dpi or more that are arranged at a high density and has many piezoelectric elements 34 that are arranged at a high density. The head chip 3 generates heat and the heat can decrease the viscosity of ink. The head unit 10, however, can move the air in the space S by the driving of the fans 80, and thus the heat generated by the head chips 3 can be efficiently dissipated, and print quality degradation can be increased.
The circuit board 50 has the drive-signal generation circuit 51 that generates a drive signal Com as previously mentioned. As the electric current of a drive signal Com output from the drive-signal generation circuit 51 increases, the electric current that flows through the transistors and coil in the drive-signal generation circuit 51 increases. Consequently, the amount of heat generated by the drive-signal generation circuit 51 increases. As a result, problems due to the heat generated by the drive-signal generation circuit 51 may occur or print quality degradation may occur. Accordingly, the heat sink 60 and the fans 80 are provided to effectively reduce the problems, specifically, print quality degradation.
The drive-signal generation circuit 51 is disposed at a position closer to the fan 80 than the head chip 3. With this structure, the heat generated by the drive-signal generation circuit 51 can be efficiently dissipated. The drive-signal generation circuits 51 are disposed on the −z side with respect to the center line A5 to separate the drive-signal generation circuits 51 from the head chips 3 as compared to a structure in which the drive-signal generation circuits 51 are disposed on the +z side with respect to the center line A5. With this structure, the heat sources can be disposed at different locations. Accordingly, the temperature evenness in the space S can be maintained and variations in print quality in the head chips 3 can be suppressed. The head chips 3 may be disposed at positions closer to the fans 80 than the drive-signal generation circuits 51.
The second drive signal Com-B has a larger amplitude than that of the first drive signal Com-A as previously mentioned. Consequently, the amount of heat generated by the first drive-signal generation circuit 51A tends to be larger than that by the second drive-signal generation circuit 51B. The first drive-signal generation circuit 51A is disposed at a position farther from the head chip 3 than the second drive-signal generation circuit 51B, and thus print quality degradation can be further suppressed.
The above-described liquid discharge apparatus 100 includes the head unit 10 and the control unit 1 for controlling the head unit 10. The liquid discharge apparatus 100 includes the head unit 10, and thereby print quality degradation can be effectively suppressed. The liquid discharge apparatus 100 may include at least the control unit 1 and the head unit 10, and the structure is not limited to the structure illustrated in
The above-described embodiment may be modified in various ways. Specific modifications applicable to the above-described embodiment will be described below. Two or more modifications selected from those below may be combined without a contradiction between them.
In the above-described embodiment, the head chips 3 are long and disposed along the +y direction; however, the arrangement and shape of the head chips 3 are not limited to this example. The nozzles N in the head chip 3 are arranged along the +y direction, but may be arranged along a different direction. For example, the nozzles N in the head chip 3 may be arranged along the +x direction. The “intersecting direction” is a direction that intersects the discharge direction, and not limited to the +x direction. For example, the “intersecting direction” may be the +y direction.
In the above-described embodiment, the head unit 10 is a line head; however, the “head unit” may be a serial head that reciprocates along the +x direction together with the movement of a carriage.
In the above-described embodiment, the example “liquid” is an ink that contain a pigment or a dye, but the “liquid” may be a liquid that contains no pigment or dye.
The structure of the head chip 3 includes a “drive element” and is configured to discharge “liquid” but is not limited to the structure illustrated in
In the above-described embodiment, the drive-signal generation circuit 51 includes the first drive-signal generation circuit 51A and the second drive-signal generation circuit 51B, but one of the first drive-signal generation circuit 51A and the second drive-signal generation circuit 51B may be omitted. The drive signal Com includes two signals: the first drive signal Com-A and the second drive signal Com-B. However, the drive signal Com may include one of the two signals.
In the above-described embodiment, one circuit board 50 is disposed for six head chips 3, but one circuit board 50 may be disposed for one head chip 3. Alternatively, only one circuit board 50 may be provided for all head chips 3. In the above-described embodiment, one drive-signal generation circuit 51 is provided for one head chip 3, but one drive-signal generation circuit 51 may be provided for a plurality of head chips 3. Alternatively, no drive-signal generation circuit 51 may be provided in the head unit 10 and the drive-signal generation circuit 51 may be provided in the control unit 1.
The number of the head chips 3 in the head unit 10 is not limited to 36 as illustrated in
In the above-described embodiment, the supporting member 4 has the holders 41, the fixing plates 42 and the base 43, but any one of the holders 41, the fixing plates 42, and the base 43 may be omitted. The flow channel unit 400 includes the flow channel structure 40 and the supporting member 4, but one of the flow channel structure 40 and the supporting member 4 may be omitted. In the above-described embodiment, the flow channel unit 400 includes the plurality of components, but the flow channel unit 400 may be a single component. For example, when the supporting member 4 is omitted, the head chips 3 may be fixed to the flow channel structure 40. The head unit 10 may omit the flow channel unit 400. For example, the flow channel unit 400 may be disposed outside the cover 70.
As previously described, the selection circuit 302 selects to supply or not to supply a drive signal Com to a piezoelectric element 34 in accordance with a print signal SI, and the like, and the selection circuit 302 may include a switch other than the transfer gates. The selection circuit 302 may include, for example, a transistor that functions as a switch. Furthermore, the selection circuit 302 is disposed on the protection plate 35. The selection circuit 302 may not be in contact with the protection plate 35 as long as the selection circuit 302 is disposed on the protection plate 35, and may be disposed on the protection plate 35 via another element.
In the above-described embodiment, the supporting member 4 is used as the “thermal conductor”. The “thermal conductor” may not include, for example, the function of supporting the head chips 3. The “thermal conductor” may not have the flow channel. The supporting member 4 may be omitted and a “thermal conductor” that has high thermal conductivity may be disposed between the head chips 3 and the heat sink 60.
In the above-described embodiment, the number of fans 80 is two, but may be one or three or more. The arrangement of the fans 80 is not limited to the example arrangement illustrated in
In the above-described embodiment, the first inlets 701, the second inlets 702, and the outlets 703 are disposed, but the number of the first inlets 701, the second inlets 702, and the outlets 703 may be one respectively. However, the outlets 703 disposed at several locations contribute to uniform temperature distribution in the space S. The same applies to the first inlets 701 and the second inlets 702. The first inlets 701 or the second inlets 702 may be omitted. The head unit 10 may not include the cover 70.
In the above-described embodiment, the number of heat sink 60 is one, but may be two or more. The arrangement of the heat sink 60 is not limited to the example arrangement illustrated in
While the present disclosure has been described with reference to the embodiment and modifications, it is to be understood that the present disclosure is not limited to the above-described embodiment and the modifications. The components in the structures in the disclosure may be replaced with any structure that achieves functions similar to the functions according to the above-described embodiment, or a structure may be added.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-033859 | Feb 2019 | JP | national |
