Patent Application
20230347641
The present application is based on, and claims priority from JP Application Serial Number 2022-074876, filed Apr. 28, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a liquid ejecting apparatus.
In a liquid ejecting apparatus that ejects liquid such as ink, for example, thickening of liquid due to evaporation of a solvent such as moisture contained in the liquid causes a problem. The thickening of the liquid causes a decrease in ejection property, that is, a decrease in one or both of ejection amount and ejection rate. Disclosed in JP-A-2013-163290 is a liquid ejecting apparatus including a nozzle that ejects liquid and an individual flow path through which liquid is supplied to the nozzle and through which liquid not ejected from the nozzle is discharged. The liquid ejecting apparatus performs a circulation operation of circulating liquid in the individual flow path and a minute vibration operation of causing minute vibration of liquid, of which thickening has been progressed, so that local thickening in the vicinity of the nozzle is eliminated.
However, in the above-described liquid ejecting apparatus in the related art, a decrease in ejection property caused by thickening occurs in some cases even when the circulation operation and the minute vibration operation are performed.
According to an aspect of the present disclosure, there is provided a liquid ejecting apparatus including a liquid ejection head including a first piezoelectric element that is driven in response to supply of a drive signal, a first nozzle that ejects liquid by means of a pressure that is applied when the first piezoelectric element is driven, and a first individual flow path that communicates with the first nozzle, through which the liquid is supplied to the first nozzle, and through which the liquid not ejected from the first nozzle is discharged, a circulation control section that controls a circulation operation of circulating the liquid in the first individual flow path, and a minute vibration control section that supplies a drive signal having a first waveform to the first piezoelectric element so as to control a minute vibration operation of causing the liquid in the first nozzle to vibrate to such a degree that the liquid is not ejected from the first nozzle. The circulation control section starts the circulation operation at a first time, and the minute vibration control section starts the minute vibration operation at a second time later than the first time.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that, the dimensions and scales of each part shown in each drawing are different from the actual dimensions and scales as appropriate. In addition, since the embodiments to be described below are suitable specific examples of the present disclosure, various technically-preferable limitations are provided to the embodiments. However, the range of the present disclosure is not limited to the embodiments unless there is no description to the effect that the present disclosure is limited hereinafter.
For the sake of convenience, the following description will be made while appropriately using an X-axis, a Y-axis, and a Z-axis that intersect with each other. In addition, a direction extending along the X-axis is an X1 direction, and a direction opposite to the X1 direction is an X2 direction. Similarly, directions that extend along the Y-axis and are opposite to each other are a Y1 direction and a Y2 direction. In addition, directions that extend along the Z-axis and are opposite to each other are a Z1 direction and a Z2 direction.
Here, typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to a downward vertical direction. However, the Z-axis does not need to be the vertical axis and may be inclined with respect to the vertical axis. In addition, although the X-axis, the Y-axis, and the Z-axis are typically orthogonal to each other, the present disclosure is not limited thereto. For example, the X-axis, the Y-axis, and the Z-axis only need to intersect each other at an angle within a range of 80 degrees or more and 100 degrees or less.
The configuration of a liquid ejecting apparatus 100 will be described with reference to
The ink according to the first embodiment has a feature that thickening of the ink is easily progressed since a solvent such as moisture contained in the ink is volatile and is easily evaporated or a feature that thickening of the ink is easily progressed when a solvent is evaporated.
As shown in
The liquid supply source 110 is a container storing ink. Specific examples of the liquid supply source 110 include a cartridge detachable from the liquid ejecting apparatus 100, a bag-shaped ink pack formed of a flexible film, and an ink tank refillable with ink. Note that, any type of ink is stored in the liquid supply source 110.
Although not shown in the drawings, the liquid supply source 110 of the first embodiment includes a first liquid container and a second liquid container. First ink is stored in the first liquid container. Second ink, which is a different type of ink from the first ink, is stored in the second liquid container. For example, the first ink and the second ink are inks of which the colors are different from each other. The first ink and the second ink may be the same type of ink.
The control module 120 controls the operation of each element in the liquid ejecting apparatus 100. The control module 120 includes, for example, one or more processing circuits such as CPUs or FPGAs, and one or more storage circuits such as semiconductor memories. “CPU” is an abbreviation for “Central Processing Unit”. “FPGA” is an abbreviation for “Field Programmable Gate Array”. Various programs and various data are stored in the storage circuit. The processing circuit realizes various types of control by executing the programs and appropriately using the data.
The transport mechanism 130 transports the medium PP in a direction DM under the control of the control module 120. The direction DM in the first embodiment is the Y2 direction. In an example shown in
Under the control of the control module 120, the liquid ejection module 140 ejects ink to the medium PP in the Z2 direction from each of the plurality of nozzles N, the ink being supplied from the liquid supply source 110 via the circulation mechanism 150. The liquid ejection module 140 is a line head including a plurality of liquid ejection heads 10 that are disposed such that the plurality of nozzles N are distributed over the entire medium PP in a direction along the X-axis. That is, a group of the plurality of liquid ejection heads 10 constitutes a long line head that extends in the direction along the X-axis. When ejection of ink from the plurality of liquid ejection heads 10 is performed in parallel with transportation of the medium PP which is performed by the transport mechanism 130, an image is formed on a surface of the medium PP by means of ink. Note that, the plurality of nozzles N that one liquid ejection head 10 includes may be disposed to be distributed over the entire medium PP in the direction along the X-axis and in this case, for example, the liquid ejection module 140 is composed of the one liquid ejection head 10.
The liquid supply source 110 is coupled to the liquid ejection module 140 via the circulation mechanism 150. The circulation mechanism 150 is a mechanism that supplies ink to the liquid ejection module 140 and that retrieves ink discharged from the liquid ejection module 140 for re-supply to the liquid ejection module 140 under the control of the control module 120. In an example shown in
The supply flow path 153 is positioned upstream of the liquid ejection module 140 in a direction in which ink flows. The retrieval flow path 155 is positioned downstream of the liquid ejection module 140 in the direction in which ink flows. In the example of
The capping mechanism 180 is a mechanism provided to seal nozzle surfaces FN provided with the nozzles N. The capping mechanism 180 includes a cap 182 and a cap mover 184. The cap 182 seals the nozzle surfaces FN provided with the nozzles N. The cap mover 184 moves the cap 182 relative to the liquid ejection module 140 along the Y-axis and the Z-axis under the control of the control module 120. The cap mover 184 is composed of, for example, a guide rail, a motor, and the like. The cap mover 184 moves the cap 182 relative to each of the plurality of liquid ejection heads 10 in the Z1 direction during a period in which ink is not ejected to the medium PP from each of the plurality of liquid ejection heads 10 so that a tip end portion of the cap 182 comes into contact with the nozzle surfaces FN of the plurality of liquid ejection heads 10 and the nozzle surfaces FN are covered by the cap 182 at least partially. The nozzle surfaces FN will be described later with reference to
Hereinafter, an operation of sealing the nozzle surfaces FN by means of the cap 182 will be described as a “cap sealing operation”, and an operation of unsealing the nozzle surfaces FN sealed by the cap 182 will be described as “cap unsealing operation”. Note that, the cap mover 184 may cause the nozzle surfaces FN to be sealed by moving the liquid ejection module 140 instead of moving the cap 182.
The liquid ejection head 10 includes one or more head main bodies 14 that eject ink. In the first embodiment, one liquid ejection head 10 includes six head main bodies 14. The head main body 14 includes M ejectors D that eject ink and a switching circuit 141. In the first embodiment, M is an integer of 2 or more. Note that M may also be 1.
Hereinafter, for distinction between the M ejectors D that one head main body 14 includes, the ejectors D may be referred to as a first-stage ejector, a second-stage ejector, . . . , and an Mth-stage ejector in order. In addition, an mth-stage ejector D may be referred to as an “ejector D[m]”. In the following description, the variable m is an integer of 1 or more and M or less. In addition, when a component of the liquid ejecting apparatus 100, a signal, or the like corresponds to the ordinal number “m” of the ejector D[m], a suffix “[m]” that indicating that the component, the signal, or the like corresponds to the ordinal number “m” may be added to a symbol representing the component, the signal, or the like.
The switching circuit 141 switches, based on a designation signal SI, whether or not a drive signal Com output from the drive signal generation circuit 190 is to be supplied to each ejector D.
The control module 120 reads a program from the storage circuit in the control module 120 and executes the read program to function as a drive control section 121, a cap control section 125, a circulation control section 127, and a transport control section 129. However, a device that functions as the drive control section 121, a device that functions as the cap control section 125, a device that functions as the circulation control section 127, and a device that functions as the transport control section 129 may not be the same device. For example, a device that functions as the drive control section 121, a device that functions as the cap control section 125, a device that functions as the circulation control section 127, and a device that functions as the transport control section 129 may be different devices.
The drive control section 121 controls the operation of the ejectors D. More specifically, the drive control section 121 generates the designation signal SI for control of the ejectors D and a waveform designation signal dCom for control of the drive signal generation circuit 190. The waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. In addition, the drive signal Com is an analog signal used to drive the ejectors D. The drive signal generation circuit 190 includes a DA conversion circuit and generates the drive signal Com having a waveform defined by the waveform designation signal dCom. Note that, in the first embodiment, it will be assumed that the drive signal Com includes a drive signal Com-A and a drive signal Com-B.
In addition, the designation signal SI is a digital signal for designation of the type of operation of the ejectors D. Specifically, the designation signal SI designates the type of operation of the ejectors D by designating whether or not the drive signal Com is to be supplied to the ejectors D. Here, the designation of the type of operation of the ejectors D is, for example, designating whether or not the ejectors D are to be driven or designating whether or not ink is to be ejected from the ejectors D when the ejectors D are driven. When the ejectors D are to be driven to perform a printing ejection operation in which ink is ejected from the nozzles N of the ejectors D so that dots constituting an image are formed on the medium PP, the drive control section 121 functions as an ejection control section 122 that controls the ejection operation. Meanwhile, when the ejectors D are to be driven to perform a minute vibration operation in which ink in the nozzles N is caused to vibrate to such a degree that no ink is ejected from the nozzles N, the drive control section 121 functions as a minute vibration control section 123 that controls the minute vibration operation. The printing ejection operation is an example of an “ejection operation of causing liquid to be ejected from a first nozzle”.
The cap control section 125 controls the capping mechanism 180. More specifically, the cap control section 125 outputs a signal for control of the capping mechanism 180 to the capping mechanism 180 to control the cap unsealing operation.
The circulation control section 127 controls the circulation mechanism 150. More specifically, the circulation control section 127 outputs a signal for control of the circulation mechanism 150 to the circulation mechanism 150 to generate a pressure difference between a position upstream of the liquid ejection head 10 and a position downstream of the liquid ejection head 10 and to control a circulation operation of circulating ink in an individual flow path PJ which will be described later.
The transport control section 129 controls the transport mechanism 130. More specifically, the transport control section 129 outputs a signal for control of the transport mechanism 130 to the transport mechanism 130.
First, the control module 120 stores printing data Img in a storage circuit in the control module 120, the printing data Img being supplied from a host computer. Next, the control module 120 generates, based on various types of data such as the printing data Img stored in the storage circuit, the designation signal SI, the waveform designation signal dCom, a signal for control of the transport mechanism 130, a signal for control of the capping mechanism 180, a signal for control of the circulation mechanism 150, and a signal for control of the pump 170. Then, the control module 120 controls, based on the various control signals and the various types of data stored in the storage circuit, the liquid ejection module 140 such that the ejectors D are driven while controlling the transport mechanism 130 such that the position of the medium PP relative to the liquid ejection module 140 is changed. In this manner, the control module 120 adjusts whether or not ink is ejected from the ejectors D, the amount of ejection of ink, the timing of ejection of ink, and the like and controls performance of a printing process of forming an image corresponding to the printing data Img on the medium PP.
The flow path structure 11 is a structure in which a flow path used to cause ink to flow between the circulation mechanism 150 and the plurality of head main bodies 14 is provided. As shown in
Here, although not shown in the drawings, flow paths such as a first supply flow path CC1, a second supply flow path CC2, a first discharge flow path CM1, and a second discharge flow path CM2 are provided in the flow path structure 11. The first supply flow path CC1 is a flow path for supply of the first ink to the plurality of head main bodies 14, the first ink being introduced into the coupling pipe 11a. The second supply flow path CC2 is a flow path for supply of the second ink to the plurality of head main bodies 14 the, second ink being introduced into the coupling pipe lib. A filter used to capture foreign substances or the like is installed in an intermediate portion of each of the supply flow paths. The first discharge flow path CM1 is a flow path for discharge of the first ink from the plurality of head main bodies 14. The second discharge flow path CM2 is a flow path for discharge of the second ink from the plurality of head main bodies 14.
The coupling pipes 11a, 11b, 11c, and 11d are pipe bodies protruding in the Z1 direction. More specifically, the coupling pipe 11a is a pipe body that constitutes a flow path for supply of the first ink to the first supply flow path CC1. In addition, the coupling pipe 11b is a pipe body that constitutes a flow path for supply of the second ink to the second supply flow path CC2. Meanwhile, the coupling pipe 11c is a pipe body that constitutes a flow path for discharge of the first ink from the first discharge flow path CM1. In addition, the coupling pipe 11d is a pipe body that constitutes a flow path for discharge of the second ink from the second discharge flow path CM2. The hole 11e is a hole for insertion of a connector 12c which will be described later.
The wiring substrate 12 is a mounted component for electrical coupling between the plurality of head main bodies 14 and a collective substrate 16b which will be described later. The wiring substrate 12 is, for example, a rigid wiring substrate. The wiring substrate 12 is disposed between the flow path structure 11 and the holder 13, and the connector 12c is installed on a surface of the wiring substrate 12 that faces the flow path structure 11. The connector 12c is a coupling component coupled to the collective substrate 16b which will be described later. In addition, the wiring substrate 12 is provided with a plurality of holes 12a and a plurality of opening portions 12b. Each hole 12a is a hole for allowance of coupling between the flow path structure 11 and the holder 13. Each opening portion 12b is a hole through which a wiring substrate 14h that couples the head main body 14 and the wiring substrate 12 passes. The wiring substrate 14h is coupled to a surface of the wiring substrate 12 that faces the Z1 direction. The wiring substrate 14h is a member including a wire electrically coupled to a piezoelectric element PZ which will be described later, and is, for example, an FPC, a COF, an FFC, or the like. The “FPC” is an abbreviation for “Flexible Printed Circuits”. The “COF” is an abbreviation for “Chip On Film”. The “FFC” is an abbreviation for “Flexible Flat Cable”.
The holder 13 is a structure that accommodates and supports the plurality of head main bodies 14. The holder 13 is formed of, for example, a resin material, a metal material, or the like. The holder 13 has a plate-like shape that extends in directions perpendicular to the Z-axis. In addition, the holder 13 is provided with a coupling pipe 13a, a coupling pipe 13b, a plurality of coupling pipes 13c, a plurality of coupling pipes 13d, and a plurality of wiring holes 13e. In addition, although not shown in the drawing, a surface of the holder 13 that faces the Z2 direction is provided with a plurality of recess portions for accommodation of the plurality of head main bodies 14.
In the first embodiment, the holder 13 holds the six head main bodies 14_1 to 14_6. The head main bodies 14 are arranged in the X2 direction in the order of the head main bodies 14_1, 14_2, 14_3, 14_4, 14_5, and 14_6. Here, the head main bodies 14_1 to 14_3 are disposed at positions offset from the head main bodies 14_4 to 14_6 in the Y1 direction. However, the head main bodies 14_1 to 14_6 partially overlap with each other as seen in the X1 direction or the X2 direction. In addition, arrangement directions DN (which will be described later) of the plurality of nozzles N of the head main bodies 14_1 to 14_6 are parallel to each other. Furthermore, each of the head main bodies 14_1 to 14_6 is disposed such that the arrangement direction DN is inclined with respect to the direction DM which is a transport direction of the medium PP.
Here, although not shown in
In the first embodiment, regarding the head main bodies 14_1 to 14_6, the first ink is supplied to the head main bodies 14_1 to 14_3 and the second ink is supplied to the head main bodies 14_4 to 14_6.
The coupling pipes 13a, 13b, 13c, and 13d are pipe-shaped protrusions protruding in the Z1 direction. More specifically, the coupling pipe 13a is a pipe body that constitutes a flow path for supply of the first ink to the first distribution supply flow path SP1, and the coupling pipe 13a communicates with the first supply flow path CC1 of the flow path structure 11. In addition, the coupling pipe 13b is a pipe body that constitutes a flow path for supply of the second ink to the second distribution supply flow path SP2, and the coupling pipe 13b communicates with the second supply flow path CC2 of the flow path structure 11. Meanwhile, the coupling pipes 13c are pipe bodies that constitute flow paths for discharge of the first ink from the first individual discharge flow paths DS1 and the coupling pipes 13c communicate with the first discharge flow path CM1 of the flow path structure 11. In addition, the coupling pipes 13d are pipe bodies that constitute flow paths for discharge of the second ink from the second individual discharge flow paths DS2 and the coupling pipes 13d communicate with the second discharge flow path CM2 of the flow path structure 11. The wiring holes 13e are holes through which the wiring substrates 14h that couple the head main bodies 14 and the wiring substrate 12 pass.
Each head main body 14 ejects ink. Specifically, although not shown in
The fixation plate 15 is a plate member for fixation of the plurality of head main bodies 14 to the holder 13. Specifically, the fixation plate 15 is disposed in a state where the plurality of head main bodies 14 are interposed between the fixation plate 15 and the holder 13, and is fixed to the holder 13 by means of an adhesive. The fixation plate 15 is formed of, for example, a metal material. The fixation plate 15 is provided with a plurality of opening portions 15a for exposure of the nozzles N of the plurality of head main bodies 14. In an example shown in
The base 16 is a member for fixation of the flow path structure 11, the wiring substrate 12, the holder 13, the plurality of head main bodies 14, and the fixation plate 15 to the above-described supporting body 41. The base 16 includes a main body 16a, a collective substrate 16b, and a cover 16c.
The main body 16a is fixed to the holder 13 by being screwed or the like so that the flow path structure 11 and the wiring substrate 12 disposed between the base 16 and the holder 13 are held by the main body 16a. The main body 16a is formed of, for example, a resin material. The main body 16a includes a plate-shaped portion that faces a plate-shaped portion of the above-described flow path structure 11 and the plate-shaped portion is provided with a plurality of holes 16d into which the above-described coupling pipes 11a, 11b, 11c, and 11d are inserted. In addition, the main body 16a includes a portion that extends in the Z2 direction from the plate-shaped portion, and a tip end of that portion is provided with a flange 16e for fixation to the above-described supporting body 41.
The collective substrate 16b is a mounted component for electrical coupling between the control module 120 and the above-described wiring substrate 12. The collective substrate 16b is, for example, a rigid wiring substrate. The cover 16c is a plate-shaped member for protection of the collective substrate 16b and for fixation of the collective substrate 16b to the main body 16a. The cover 16c is formed of, for example, a resin material or the like, and the cover 16c is fixed to the main body 16a by being screwed or the like.
Here, the V-axis is an axis along the arrangement direction DN of the plurality of nozzles N, which will be described later, and is an axis obtained by rotating the Y-axis around the Z-axis by a predetermined angle. The W-axis is an axis obtained by rotating the X-axis around the Z-axis by the predetermined angle. Therefore, the V-axis and the W-axis are typically orthogonal to each other. However, the present disclosure is not limited thereto. For example, the V-axis and the W-axis only need to intersect each other at an angle within a range of 80 degrees or more and 100 degrees or less. In addition, the predetermined angle (that is, the angle formed between the V-axis and the Y-axis, or the angle formed between the W-axis and the X-axis) is, for example, in a range of 40 degrees or more and 60 degrees or less.
As shown in
The head main body 14 includes a surface that faces the medium PP, and as shown in
Here, a group of the plurality of nozzles N constitutes a nozzle row Ln. Further, the plurality of nozzles N are arranged at substantially equal intervals at a predetermined pitch. The predetermined pitch is a distance between the centers of the plurality of nozzles N in a direction along the V-axis.
The individual flow path PJ communicates with each of the M nozzles N. The M individual flow paths PJ extend along the W-axis and communicate with different nozzles N. The M individual flow paths PJ are arranged along the V-axis.
As shown in
Each of the pressure chamber Ca and the pressure chamber Cb in any of the M individual flow paths PJ is a space that extends along the W-axis and in which ink to be ejected from the nozzle N communicating with the individual flow path PJ is stored. In an example shown in
The nozzle flow path Nf is disposed between the pressure chamber Ca and the pressure chamber Cb in each of the M individual flow paths PJ. Here, the pressure chamber Ca communicates with the nozzle flow path Nf via the first communication flow path Na1 extending along the Z-axis. The pressure chamber Cb communicates with the nozzle flow path Nf via the second communication flow path Na2 extending along the Z-axis.
In the M individual flow paths PJ, the nozzle flow paths Nf are spaces extending along the W-axis. In addition, M nozzle flow paths Nf are arranged at intervals along the V-axis. Each of the M nozzle flow paths Nf is provided with the nozzle N. Ink is ejected from the nozzle N in each of the M nozzle flow paths Nf when there is a change in pressures in the pressure chamber Ca and the pressure chamber Cb.
Each of the first communication flow path Na1 and the second communication flow path Na2 is a space extending along the Z-axis.
Here, the first common liquid chamber R1 and the second common liquid chamber R2 communicate with the M individual flow paths PJ. The pressure chamber Ca communicates with the first common liquid chamber R1 via the narrowed portion Ap1 extending along the W-axis and the individual supply flow path Ra1 extending along the Z-axis. The pressure chamber Cb communicates with the second common liquid chamber R2 via the narrowed portion Ap2 extending along the W-axis and the individual discharge flow path Ra2 extending along the Z-axis.
The narrowed portion Ap1 is a flow path provided between the pressure chamber Ca and the individual supply flow path Ra1. The narrowed portion Ap2 is a flow path provided between the pressure chamber Cb and the individual discharge flow path Ra2. Hereinafter, each of the narrowed portion Ap1 and the narrowed portion Ap2 may be collectively referred to as a “narrowed portion Ap”. The narrowed portions Ap are flow paths formed to be narrower than other regions in the individual flow path PJ. The other regions in the individual flow path PJ are the pressure chamber Ca and the pressure chamber Cb. More specifically, the cross-sectional area of the narrowed portion Ap1 is smaller than the cross-sectional area of the pressure chamber Ca. Therefore, the narrowed portion Ap1 has a higher flow path resistance than the pressure chamber Ca. Similarly, the cross-sectional area of the narrowed portion Ap2 is smaller than the cross-sectional area of the pressure chamber Cb. Therefore, the narrowed portion Ap2 has a higher flow path resistance than the pressure chamber Cb. Furthermore, the narrowed portions Ap may be formed to be narrower than all other regions in the individual flow path PJ. The all other regions in the individual flow path PJ are the pressure chamber Ca, the pressure chamber Cb, the nozzle flow path Nf, the individual supply flow path Ra1, the individual discharge flow path Ra2, the first communication flow path Na1, and the second communication flow path Na2. Since the narrowed portions Ap are formed to be narrower than the other regions in the individual flow path PJ, the flow path resistances of the narrowed portions Ap are set to be higher than that of the other regions in the individual flow path PJ.
Each of the first common liquid chamber R1 and the second common liquid chamber R2 is a space that extends along the V-axis to overlap with the M individual flow paths PJ as seen along the W-axis. The first common liquid chamber R1 is coupled to an end, in the W2 direction, of each of the M individual flow paths PJ. In the first common liquid chamber R1, ink to be supplied to the plurality of individual flow paths PJ is stored. Meanwhile, the second common liquid chamber R2 is coupled to ends, in the W1 direction, of the individual flow paths PJ. In the second common liquid chamber R2, ink that is discharged from the plurality of individual flow paths PJ without being ejected from the nozzles N is stored.
The first common liquid chamber R1 is provided with a supply port IO1, a discharge port IO3a, and a discharge port IO3b. The supply port IO1 is a pipeline for introduction of ink into the first common liquid chamber R1 from a distribution supply flow path SP of the holder 13. The discharge port IO3a is a pipeline for discharge of ink from the first common liquid chamber R1 to the bypass flow path BP1. The discharge port IO3b is a pipeline for discharge of ink from the first common liquid chamber R1 to the bypass flow path BP2. Note that, the distribution supply flow path SP is a general term for the first distribution supply flow path SP1 or the second distribution supply flow path SP2, which will be described later.
Here, the distribution supply flow path SP is coupled to the circulation mechanism 150 via the first supply flow path CC1 or the second supply flow path CC2 of the flow path structure 11. Therefore, a flow path from the coupling pipe 11a or the coupling pipe 11b to the first common liquid chamber R1 is provided in common for the M pressure chambers Ca and the flow path constitutes a common supply flow path CF1 for supply of ink to the M individual flow paths PJ.
The second common liquid chamber R2 is provided with a discharge port IO2, an introduction port IO4a, and an introduction port IO4b. The discharge port IO2 is a pipeline for discharge of ink from the second common liquid chamber R2 to an individual discharge flow path DS of the holder 13. The introduction port IO4a is a pipeline for introduction of ink from the bypass flow path BP1 into the second common liquid chamber R2. The introduction port IO4b is a pipeline for introduction of ink from the bypass flow path BP2 into the second common liquid chamber R2. Note that, the individual discharge flow path DS is the first individual discharge flow path DS1 or the second individual discharge flow path DS2, which will be described later.
Here, the individual discharge flow path DS is coupled to the circulation mechanism 150 via the first discharge flow path CM1 or the second discharge flow path CM2 of the flow path structure 11. Therefore, a flow path from the second common liquid chamber R2 to the coupling pipe 11a or the coupling pipe 11b is provided in common for the M pressure chambers Cb and the flow path constitutes a common discharge flow path CF2 for discharge of ink from the M individual flow paths PJ.
The nozzle substrate 14a, the flow path substrate 14b, the pressure chamber substrate 14c, and the vibration plate 14d are stacked in this order in the Z1 direction. Each of these members extends along the V-axis and is manufactured, for example, by processing a silicon single crystal substrate with a semiconductor processing technology. In addition, these members are bonded to each other by means of an adhesive or the like. Note that, another layer such as an adhesive layer or a substrate may be appropriately interposed between two of these members that are adjacent to each other.
The nozzle substrate 14a is provided with the M nozzles N. Each of the M nozzles N is a through-hole that penetrates the nozzle substrate 14a and through which ink passes. The M nozzles N are arranged in the direction along the V-axis.
The flow path substrate 14b is provided with a portion of each of the first common liquid chamber R1 and the second common liquid chamber R2 and is provided with portions of the M individual flow paths PJ excluding the pressure chambers Ca, the narrowed portions Ap1, the pressure chambers Cb, and the narrowed portions Ap2. That is, the flow path substrate 14b is provided with the nozzle flow paths Nf, the first communication flow paths Na1, the second communication flow paths Na2, the individual supply flow paths Ra1, and the individual discharge flow paths Ra2.
The portion of each of the first common liquid chamber R1 and the second common liquid chamber R2 is a space penetrating the flow path substrate 14b. The vibration absorbing body 14j that closes an opening attributable to the space is installed on a surface of the flow path substrate 14b that faces the Z2 direction.
The vibration absorbing body 14j is a layer-shaped member formed of an elastic material. The vibration absorbing body 14j constitutes a portion of a wall surface of each of the first common liquid chamber R1 and the second common liquid chamber R2, and absorbs a pressure change in the first common liquid chamber R1 and the second common liquid chamber R2.
The nozzle flow paths Nf are spaces in grooves provided at a surface of the flow path substrate 14b that faces the Z2 direction. Here, the nozzle substrate 14a constitutes portions of wall surfaces of the nozzle flow paths Nf.
Each of the first communication flow paths Na1 and the second communication flow paths Na2 is a space penetrating the flow path substrate 14b.
Each of the individual supply flow paths Ra1 and the individual discharge flow paths Ra2 is a space penetrating the flow path substrate 14b. The first common liquid chamber R1 and the narrowed portions Ap1 communicate with each other through the individual supply flow paths Ra1 and ink from the first common liquid chamber R1 is supplied to the pressure chambers Ca via the narrowed portions Ap1. Here, one end of each individual supply flow path Ra1 is open at a surface of the flow path substrate 14b that faces the Z1 direction. Meanwhile, the other end of each individual supply flow path Ra1 is an upstream end of the individual flow path PJ and is open at the wall surface of the first common liquid chamber R1 in the flow path substrate 14b. With regard to this, the second common liquid chamber R2 and the narrowed portions Ap2 communicate with each other through the individual discharge flow paths Ra2 and ink from the pressure chambers Cb that is discharged via the narrowed portions Ap2 is discharged to the second common liquid chamber R2 through the individual discharge flow paths Ra2. Here, one end of each individual discharge flow path Ra2 is open at a surface of the flow path substrate 14b that faces the Z1 direction. Meanwhile, the other end of each individual discharge flow path Ra2 is a downstream end of the individual flow path PJ and is open at the wall surface of the second common liquid chamber R2 in the flow path substrate 14b.
The pressure chamber substrate 14c is provided with the pressure chamber Ca, the narrowed portion Ap1, the pressure chamber Cb, and the narrowed portion Ap2 of each of the M individual flow paths PJ. Each of the pressure chamber Ca, the narrowed portion Ap1, the pressure chamber Cb, and the narrowed portion Ap2 penetrates the pressure chamber substrate 14c and is a gap between the flow path substrate 14b and the vibration plate 14d.
The vibration plate 14d is a plate-shaped member that can elastically vibrate. The vibration plate 14d is, for example, a laminated body including a first layer formed of silicon oxide and a second layer formed of zirconium oxide. Here, another layer such as a metal oxide layer may be interposed between the first layer and the second layer. Note that, a portion of the vibration plate 14d or the entire vibration plate 14d may be integrally formed with the pressure chamber substrate 14c while being formed of the same material as the pressure chamber substrate 14c. For example, the vibration plate 14d and the pressure chamber substrate 14c can be integrally formed with each other by selectively removing portions, in a thickness direction, of regions of a plate-shaped member having a predetermined thickness, the regions corresponding to the pressure chambers C. In addition, the vibration plate 14d may be composed of a single-material layer.
On a surface of the vibration plate 14d that faces the Z1 direction, M piezoelectric elements PZa respectively corresponding to the M pressure chambers Ca and M piezoelectric elements PZb respectively corresponding to the M pressure chambers Cb are installed. In the following description, “piezoelectric element PZ” is a general term for the piezoelectric elements PZa and the piezoelectric elements PZb. In addition, the piezoelectric element PZ corresponding to the pressure chamber C means the piezoelectric element PZ that overlaps a portion of the pressure chamber C or the entire pressure chamber C in plan view along the Z-axis.
As shown in
Each of the 2×M piezoelectric elements PZ causes a change in pressure of ink in the pressure chamber C corresponding thereto so that the ink in the pressure chamber C is ejected from the nozzle N. The piezoelectric elements PZ causes the vibration plate 14d to vibrate in accordance with deformation thereof when the drive signal Com is supplied thereto. Because of the vibration, the pressure chambers C expand and contract and thus the pressure of ink in the pressure chambers C changes.
The description will be made referring again to
The protection plate 14g is a plate-shaped member installed on the surface of the vibration plate 14d that faces the Z1 direction, protects the 2×M piezoelectric elements PZ, and reinforces the mechanical strength of the vibration plate 14d. Here, a space for accommodation of the 2×M piezoelectric elements PZ is formed between the protection plate 14g and the vibration plate 14d.
The wiring substrate 14h is mounted on the surface of the vibration plate 14d that faces the Z1 direction, and is a mounted component for electrical coupling between the control module 120 and the head main body 14. A drive circuit 14i is mounted on the wiring substrate 14h. The drive circuit 14i includes the switching circuit 141 shown in
In the head main body 14 configured as described above, because of the operation of the circulation mechanism 150, ink flows through the first common liquid chamber R1, the individual supply flow paths Ra1, the narrowed portions Ap1, the pressure chambers Ca, the first communication flow paths Na1, the nozzle flow paths Nf, the second communication flow paths Na2, the pressure chambers Cb, the narrowed portions Ap2, the individual discharge flow paths Ra2, and the second common liquid chamber R2 in this order.
As shown in
An individual flow path PJ[m1] of a certain head main body 14 is an example of a “first individual flow path”, with respect to any integer m1 ranging from 1 to M. A pressure chamber Ca[m1] included in the individual flow path PJ[m1] is an example of a “first pressure chamber”, and a piezoelectric element PZa[m1] is an example of a “first piezoelectric element”. A pressure chamber Cb[m1] included in the individual flow path PJ[m1] is an example of a “second pressure chamber”, and a piezoelectric element PZb[m1] is an example of a “second piezoelectric element”. A nozzle N[m1] communicating with the individual flow path PJ[m1] is an example of a “first nozzle”. A narrowed portion Ap1[m1] included in the individual flow path PJ[m1] is an example of a “first narrowed portion”. A narrowed portion Ap2 [m1] included in the individual flow path PJ[m1] is an example of a “second narrowed portion”.
An individual flow path PJ[m2] is an example of a “second individual flow path”, with respect to an integer m2 different from the integer m1 in a range from 1 to M. A pressure chamber Ca[m2] included in the individual flow path PJ[m2] is an example of a “third pressure chamber”, and a piezoelectric element PZa[m2] is an example of a “third piezoelectric element”. A pressure chamber Cb[m2] included in the individual flow path PJ[m2] is an example of a “fourth pressure chamber”, and a piezoelectric element PZb[m2] is an example of a “fourth piezoelectric element”. A nozzle N[m2] communicating with the individual flow path PJ[m2] is an example of a “second nozzle”. A narrowed portion Ap1[m2] included in the individual flow path PJ[m2] is an example of a “third narrowed portion”. A narrowed portion Ap2[m2] included in the individual flow path PJ[m2] is an example of a “fourth narrowed portion”.
As shown in
The first distribution supply flow path SP1 is a flow path including three branch portions for supply of the first ink to three head main bodies 14, the first ink being introduced into the coupling pipe 13a. The second distribution supply flow path SP2 is a flow path including three branch portions for supply of the second ink to three head main bodies 14, the second ink being introduced into the coupling pipe 13b.
The first individual discharge flow path DS1 is provided for each of the head main bodies 14 that use the first ink, and is a flow path for discharge of the first ink from the coupling pipe 13c, the first ink being introduced from the corresponding head main body 14. The second individual discharge flow path DS2 is provided for each of the head main bodies 14 that use the second ink, and is a flow path for discharge of the second ink from the coupling pipes 13d, the second ink being introduced from the corresponding head main body 14.
The bypass flow path BP1 and the bypass flow path BP2 are provided for each of the head main bodies 14 and the bypass flow path BP1 and the bypass flow path BP2 are flow paths through which the first common liquid chamber R1 and the second common liquid chamber R2 described above communicate with each other. However, the bypass flow path BP1 and the bypass flow path BP2 are positioned on opposite sides to each other with respect to the center of the first common liquid chamber R1 or the second common liquid chamber R2 in the direction along the X-axis. In an example shown in
Each of the above-described flow paths that the holder 13 includes is provided in a laminated body composed of the layer 31 and the layer 32, and a recess portion 13f for accommodation of the head main body 14 is provided at a surface of the layer 32 that faces the Z2 direction. In an example shown in
Here, the first distribution supply flow path SP1 includes a vertical flow path SPa and a horizontal flow path SPb. The vertical flow path SPa extends in the direction along the Z-axis and is composed of a hole that penetrates the layer 32. The horizontal flow path SPb extends in a direction orthogonal to the Z-axis, and is provided between the layer 31 and the layer 32. In the example shown in
The bypass flow path BP1 includes a first portion BP1a, a second portion BP1b, and a third portion BP1c. Each of the first portion BP1a and the second portion BP1b extends in the direction along the Z-axis and is composed of a hole that penetrates the layer 32. The third portion BP1c extends in a direction orthogonal to the Z-axis, and is provided between the layer 31 and the layer 32. In the example shown in
Similarly, the bypass flow path BP2 includes a first portion BP2a, a second portion BP2b, and a third portion BP2c. Each of the first portion BP2a and the second portion BP2b extends in the direction along the Z-axis and is composed of a hole that penetrates the layer 32. The third portion BP2c extends in a direction orthogonal to the Z-axis, and is provided between the layer 31 and the layer 32. In the example shown in
The two bypass flow paths BP are formed to be wider than each of the M individual flow paths PJ. Therefore, the two bypass flow paths BP have lower flow path resistances than each of the M individual flow paths PJ. In addition, the two bypass flow paths BP are formed to be narrower than each of the first common liquid chamber R1 and the second common liquid chamber R2. In addition, as described above, the two bypass flow paths BP are formed to be bent. Therefore, the flow path resistance of the two bypass flow paths BP is greater than those of the first common liquid chamber R1 and the second common liquid chamber R2.
As shown in
The coupling state designation circuit 142 generates, based on the designation signal SI supplied from the control module 120 and at least a portion of a latch signal LAT, coupling state designation signals SL1a[1] to SL1a[M], coupling state designation signals SL2a[1] to SL2a[M], coupling state designation signals SL1b[1] to SL1b[M], and coupling state designation signals SL2b[1] to SL2b[M].
A coupling state designation signal SL1a[m] is for designation of whether a switch SW1a[m] is to be turned on or off, with respect to any m ranging from 1 to M. A coupling state designation signal SL2a[m] is for designation of whether a switch SW2a[m] is to be turned on or off, with respect to any m ranging from 1 to M. A coupling state designation signal SL1b[m] is for designation of whether a switch SW1b[m] is to be turned on or off, with respect to any m ranging from 1 to M. A coupling state designation signal SL2b[m] is for designation of whether a switch SW2b[m] is to be turned on or off, with respect to any m ranging from 1 to M.
The switch SW1a[m] switches, in accordance with the coupling state designation signal SL1a[m], between conduction and non-conduction between the internal wire LHa and individual electrodes Qda [m] of a piezoelectric element PZa[m] provided in an ejector D[m], with respect to any m ranging from 1 to M. For example, the switch SW1a[m] is turned on when the coupling state designation signal SL1a[m] is at a high level and is turned off when the coupling state designation signal SL1a[m] is at a low level.
The switch SW2a[m] switches, in accordance with the coupling state designation signal SL2a[m], between conduction and non-conduction between the internal wire LHb and the individual electrodes Qda [m] of the piezoelectric element PZa[m] provided in the ejector D[m], with respect to any m ranging from 1 to M. For example, the switch SW2a[m] is turned on when the coupling state designation signal SL2a[m] is at a high level and is turned off when the coupling state designation signal SL2a[m] is at a low level.
The switch SW1b[m] switches, in accordance with the coupling state designation signal SL1b[m], between conduction and non-conduction between the internal wire LHa and individual electrodes Qdb [m] of a piezoelectric element PZb[m] provided in the ejector D[m], with respect to any m ranging from 1 to M. For example, the switch SW1b[m] is turned on when the coupling state designation signal SL1b[m] is at a high level and is turned off when the coupling state designation signal SL1b[m] is at a low level.
The switch SW2b[m] switches, in accordance with the coupling state designation signal SL2b[m], between conduction and non-conduction between the internal wire LHb and the individual electrodes Qdb [m] of the piezoelectric element PZb[m] provided in the ejector D[m], with respect to any m ranging from 1 to M. For example, the switch SW2b[m] is turned on when the coupling state designation signal SL2b[m] is at a high level and is turned off when the coupling state designation signal SL2b[m] is at a low level.
In the first embodiment, it will be assumed that the waveforms of the drive signals Com supplied to two piezoelectric elements PZ included in one ejector D are approximately the same as each other. Here, “being approximately the same as each other” is a concept including a case where the waveforms can be considered as waveforms that are the same as each other when an error is taken into consideration, in addition to a case where the waveforms are completely the same as each other. For example, when both of the switch SW1a[m] and the switch SW1b[m] are on and both of the switch SW2a[m] and the switch SW2b[m] are off, the drive signal Com-A is supplied to two piezoelectric elements PZ included in the ejector D[m], with respect to any m ranging from 1 to M.
As described above, ink in the first embodiment has a feature of being easily thickened. Therefore, ink thickened to a certain degree may stay inside the nozzles N or near the nozzles N before the printing ejection operation. Hereinafter, thickened ink will be referred to as “thickened ink”. Before the printing ejection operation, the nozzle surfaces FN are sealed by the cap 182 through the cap sealing operation, and basically, ink in the nozzles N and air are isolated from each other. Therefore, ideally, thickening of the ink due to evaporation of a liquid component in the ink does not occur during the cap sealing operation. However, in practice, it is difficult to completely prevent contact between the ink in the nozzles N and the air even during the cap sealing operation. Therefore, in the case of the ink in the first embodiment, in a specific situation where the cap sealing operation is performed for a long time or an environmental temperature is high, thickened ink may stay inside the nozzles N or near the nozzles N even during the cap sealing operation.
It may be conceivable that it is possible to eliminate a problem that the thickened ink stays by performing the circulation operation and the minute vibration operation. However, although depending on the order in which the circulation operation and the minute vibration operation are started, the thickened ink may continue to stay. Hereinafter, an embodiment in which the minute vibration operation is started first and then the circulation operation is started will be described as a “comparative embodiment”. The comparative embodiment will be described with reference to
A pressure that is applied to ink in the individual flow path PJ per unit period because of the minute vibration operation is larger than a pressure that is applied to the ink in the individual flow path PJ per unit period because of the circulation operation. In order to make it easy to understand a difference between the magnitudes of the pressures, the stream FRb shown in
As shown in
In addition, in the comparative embodiment, the stream FRb caused by the minute vibration operation eliminates thickening at the position inside the nozzle N and at the position closer to the side to which the Z1 direction extends than the nozzle N is in
Therefore, in the case of the liquid ejecting apparatus 100 according to the first embodiment, the circulation operation is started first and then the minute vibration operation is started. A series of operations in the liquid ejecting apparatus 100 according to the first embodiment will be described with reference to
As shown in
As shown in
The minute vibration control section 123 continues, until a time Tg is reached, the minute vibration operation started at the time Tb and ends the minute vibration operation at the time Tg. The time Tg is earlier than the time Th. The time Tg is an example of a “fifth time”.
As shown in
As shown in
As shown in
Both the circulation operation and the minute vibration operation are operations of applying pressure to ink. However, as can be understood from
The circulation operation only generates an ink stream in the liquid ejection head 10 that flows from an upstream area and a downstream area in the liquid ejection head 10 and cannot generate a local stream flowing from the individual flow path PJ to the nozzle N. Meanwhile, regarding the minute vibration operation, the individual flow path PJ is in a state of being like a closed space since the narrowed portions Ap are present at both ends of the individual flow path PJ. Therefore, the ratio of a pressure transmitted to the nozzle N to a pressure applied to ink because of the minute vibration operation is larger than the ratio of a pressure transmitted to the narrowed portions Ap to the pressure applied to the ink because of the minute vibration operation. Accordingly, a large pressure is transmitted to the nozzle N in comparison with an embodiment in which no narrowed portion Ap is present. Therefore, it is conceivable that the minute vibration operation according to the first embodiment generates the stream FRb along the Z-axis that is large in comparison with the embodiment in which no narrowed portion Ap is present. In addition, in the first embodiment, the substantially same drive signals Com are supplied to the piezoelectric element PZa positioned upstream of the nozzle N and the piezoelectric element PZb positioned downstream of the nozzle N in one ejector D when the minute vibration operation is performed. Therefore, a pressure applied to ink from the piezoelectric element PZa and a pressure applied to the ink from the piezoelectric element PZb are merged with each other in the vicinity of the nozzle N which is positioned at the approximately center of the individual flow path PJ. It is conceivable that a portion of the merged pressure proceeds toward the nozzle N. Therefore, it is also conceivable that the minute vibration operation generates the stream FRb along the Z-axis.
In addition, in the case of the circulation operation, the stream FRc along the nozzle flow path Nf is generated by a pressure difference between the upstream area and the downstream area in the liquid ejection head 10. However, since a pressure at a meniscus position and the atmospheric pressure are balanced, almost no stream along the Z-axis is generated. The meniscus is a surface of ink that is formed in the nozzle N. The pressure at the meniscus position is a pressure applied to the meniscus by the ink positioned inside the meniscus. Meanwhile, in the case of the minute vibration operation, there is a difference between the pressure at the meniscus position and the atmospheric pressure. Therefore, the stream FRb along the Z-axis can be generated.
In addition, since the circulation operation generates a unidirectional stream flowing from the upstream area to the downstream area in the liquid ejection head 10, the circulation operation has an effect of replacing the ink in the individual flow path PJ. Meanwhile, since the minute vibration operation generates a bidirectional stream that alternately repeats flowing in the Z1 direction and flowing in the Z2 direction, the minute vibration operation has an effect of stirring ink inside and near the nozzle N and an effect of diffusing ink thickening.
As shown in
The designation signal SI includes, with respect to one head main body 14, individual designation signals Sd[1] to Sd[M] that designate the way in which the ejectors D[1] to D[M] are driven in each of the unit periods Tu. In addition, as shown in
Note that, the individual designation signal Sd[m] according to the first embodiment is a signal for designation of any one of the printing ejection operation and the minute vibration operation with respect to the ejector D[m] in each unit period Tu, with respect to any m ranging from 1 to M. In the first embodiment, for example, it will be assumed that the individual designation signal Sd[m] is a 1-bit digital signal as shown in
As shown in
Potentials at the start and end of the ejection waveform PX and potentials at the start and end of the minute vibration waveform PS are set to a reference potential V0. A manufacturer of the liquid ejecting apparatus 100 determines the ejection waveform PX and the minute vibration waveform PS such that a potential difference between a maximum potential VHX and a minimum potential VLX of the ejection waveform PX is greater than a potential difference between a minimum potential VLS of the minute vibration waveform PS and the reference potential V0. Furthermore, the manufacturer of the liquid ejecting apparatus 100 determines the minute vibration waveform PS such that an ink stream in the Z1 direction that is generated in the nozzle N reaches the individual flow path PJ (more specifically, the nozzle flow path Nf) when the drive signal Com-B having the minute vibration waveform PS is supplied to the piezoelectric elements PZ. Note that, the ink stream in the Z1 direction is an example of “a liquid stream toward an individual flow path”.
When the individual designation signal Sd[m] is for designation of the printing ejection operation with respect to the ejector D[m], the coupling state designation circuit 142 sets the coupling state designation signals SL1a[m] and SL1b[m] to a high level in the unit period Tu and sets the coupling state designation signals SL2a[m] and SL2b[m] to a low level in the unit period Tu, with respect to any m ranging from 1 to M. Accordingly, the ejector D[m] ejects ink in the unit period Tu so that a dot is formed on the medium PP.
In addition, when the individual designation signal Sd[m] is for designation of the minute vibration operation with respect to the ejector D[m], the coupling state designation circuit 142 sets the coupling state designation signals SL1a[m] and SL1b[m] to a low level in the unit period Tu and sets the coupling state designation signals SL2a[m] and SL2b[m] to a high level in the unit period Tu, with respect to any m ranging from 1 to M. Accordingly, in the ejector D[m], ink in the nozzle N is vibrated in the unit period Tu and no dot is formed on the medium PP.
The drive control section 121 generates, based on the printing data Img, an individual designation signal Sd for designation of any one of the printing ejection operation and the minute vibration operation with respect to each of the M ejectors D of each of the six head main bodies 14. Therefore, in the period Tde, the minute vibration operation is temporarily stopped in the ejector D for which the printing ejection operation is designated, and the printing ejection operation is temporarily stopped in the ejector D for which the minute vibration operation is designated. For example, in one unit period Tu within the period Tde, the minute vibration operation is temporarily stopped in an ejector D[m3] for which the printing ejection operation is designated and the minute vibration operation is continued in an ejector D[m4] for which the minute vibration operation is designated. Furthermore, when the minute vibration operation is designated for the ejector D[m3] in the next unit period Tu after the above-described unit period Tu, the minute vibration operation is restarted and the printing ejection operation is temporarily stopped in the ejector D[m3]. Here, m3 and m4 are integers in a range from 1 to M and are integers different from each other.
Although description about the period Tde has been made with reference to
As shown in
The description will be made referring again to
The circulation control section 127 ends the circulation operation at the time Th later than the time Tg. A period Tgh from the time Tg to the time Th is shorter than the period Tab. Note that, the period Tgh is an example of “a time interval between the fourth time and the fifth time”.
Hereinafter, the liquid ejecting apparatus 100 according to the first embodiment will be described while using any integer m1 ranging from 1 to m and m2 which is an integer different from the integer m1 in a range from 1 to M.
The liquid ejecting apparatus 100 according to the first embodiment includes the liquid ejection head 10 and the control module 120. The control module 120 functions as the circulation control section 127 and the minute vibration control section 123. The liquid ejection head 10 includes the piezoelectric element PZa[m1] that is driven in response to supply of the drive signal Com, the nozzle N[m1] that ejects ink by means of a pressure that is applied when the piezoelectric element PZa[m1] is driven, and the individual flow path PJ[m1] that communicates with the nozzle N[m1], through which ink is supplied to the nozzle N[m1], and through which ink not ejected from the nozzle N[m1] is discharged. The circulation control section 127 controls the circulation operation of circulating the ink in the individual flow path PJ[m1]. The minute vibration control section 123 supplies the drive signal Com-B having the minute vibration waveform PS to the piezoelectric element PZa[m1] so as to control the minute vibration operation of causing ink in the nozzle N[m1] to vibrate to such a degree that the ink is not ejected from the nozzle N[m1]. The circulation control section 127 starts the circulation operation at the time Ta. The minute vibration control section 123 starts the minute vibration operation at the time Tb later than the time Ta.
As shown in
In addition, the liquid ejecting apparatus 100 includes the cap 182 that seals the nozzle surface FN provided with the nozzle N[m1]. The control module 120 also functions as the cap control section 125. The cap control section 125 controls an unsealing operation of unsealing the nozzle surface FN sealed by the cap 182. The cap control section 125 starts the cap unsealing operation at the time Tc later than the time Tb.
When the nozzle surface FN is unsealed, evaporation of a solvent in ink at the nozzle N[m1] becomes remarkable and thus thickening may be rapidly progressed inside and near the nozzle N[m1]. In the first embodiment, the circulation operation and the minute vibration operation are started before the time Tc at which thickening of ink is rapidly progressed. Therefore, thickening of ink inside and near the nozzle N[m1] can be suppressed in comparison with an embodiment in which the circulation operation and the minute vibration operation are started after the time Tc.
In addition, the period Tab is shorter than that of the period Tbc. In other words, a period in which only the circulation operation is performed before the printing ejection operation is shorter than a period in which only the circulation operation and the minute vibration operation are performed before the printing ejection operation.
It is preferable that the cap sealing operation is in progress in the period Tbc and the circulation operation and the minute vibration operation are performed for a certain period so that thickening is eliminated as much as possible before the start of the cap unsealing operation. Meanwhile, the period Tab does not need to be longer than necessary because only to be performed in the period Tab is elimination of thickening in the nozzle flow path Nf. If the period Tab is set to be longer than necessary, a period from a time at which the power source is turned on to the time Te (that is, a period for which a user waits for the end of the printing process) is made long, which is not preferable. Therefore, according to the first embodiment, thickening can be eliminated as much as possible before the start of the cap unsealing operation and a time for which the user waits for the end of the printing process can be shortened in comparison with an embodiment in which the period Tab is longer than the period Tbc.
In addition, the control module 120 also functions as the ejection control section 122. The ejection control section 122 supplies the drive signal Com-A having the ejection waveform PX to the piezoelectric element PZa[m1] so as to control the printing ejection operation of causing ink to be ejected from the nozzle N[m1]. The ejection control section 122 starts the printing ejection operation after the time Tc.
At the time Tc, the circulation operation and the minute vibration operation have been already started and thickening of ink inside and near the nozzle N[m1] has been suppressed. When the printing ejection operation is started after the time Tc, the occurrence of ejection failure can be suppressed.
In addition, the circulation control section 127 ends the circulation operation at the time Th later than the end of the printing ejection operation and the minute vibration control section 123 ends the minute vibration operation at the time Tg later than the end of the printing ejection operation.
In other words, the circulation operation and the minute vibration operation are continued until the printing ejection operation is ended. Therefore, it is possible to suppress the progress of thickening during the printing ejection operation.
In addition, the time Th is later than the time Tg. In other words, the liquid ejecting apparatus 100 ends the circulation operation after the minute vibration operation is ended. As shown in
Meanwhile, in the first embodiment, the circulation operation is ended after the minute vibration operation is ended and thus meandering of the stream FRc caused by the circulation operation is eliminated in the period Tgh. When the meandering is eliminated, the occurrence of stagnation can be suppressed and thus thickened ink staying at the position downstream of the vicinity of the nozzle N can be suppressed.
In addition, the period Tgh is shorter than that of the period Tab. In other words, a period in which only the circulation operation is performed after the printing ejection operation is shorter than a period in which only the circulation operation is performed before the printing ejection operation.
Before the printing ejection operation, it is preferable to eliminate thickening as much as possible. However, after the printing ejection operation, it is sufficient to cause the ink in the individual flow path PJ to flow by means of the stream FRc caused by the circulation operation performed to a certain degree. This is because even if the circulation operation is performed for a long time after the printing ejection operation, the occurrence of slight evaporation of ink during a period between the end of the circulation operation and the next printing ejection operation cannot be suppressed. The circulation operation performed for an excessively long time only consumes power. Therefore, according to the first embodiment, thickening can be eliminated as much as possible before the printing ejection operation and power consumption of the liquid ejecting apparatus 100 can be reduced in comparison with an embodiment in which the period Tgh is longer than the period Tab.
Further, the circulation control section 127 ends the circulation operation at the time Th, the minute vibration control section 123 ends the minute vibration operation at the time Tg, and the cap control section 125 ends the cap unsealing operation at the time Tf earlier than the time Th and the time Tg. In other words, at a time when the cap unsealing operation in which thickening of ink inside and near the nozzle N is rapidly progressed is ended, the circulation operation and the minute vibration operation are in progress.
According to the first embodiment, rapid progress of thickening of ink inside and near the nozzle N can be suppressed in comparison with an embodiment in which the circulation operation and the minute vibration operation are ended before the cap unsealing operation is ended.
In addition, the ejection control section 122 ends the printing ejection operation before the time Tf.
At the time Tf, the circulation operation and the minute vibration operation are in progress so that thickening of ink inside and near the nozzle N[m1] is suppressed. When the printing ejection operation is ended before the time Tf, the occurrence of ejection failure can be suppressed throughout a period from the start of the printing ejection operation and the end of the printing ejection operation.
The circulation control section 127 is continuing the circulation operation at the time Tb.
In an embodiment in which the circulation operation is ended at the time Tb at which the minute vibration operation is started, progress of thickening of ink inside and near the nozzle N starts after the end of the circulation operation. Therefore, thickened ink may stay at the region downstream of the nozzle N in the nozzle flow path Nf as with the comparative embodiment in which the minute vibration operation is started first and then the circulation operation is started. Meanwhile, according to the first embodiment, the circulation operation is in progress at the time Tb. Therefore, thickening of ink inside and near the nozzle N can be suppressed and thickened ink staying at the region downstream of the nozzle N in the nozzle flow path Nf can be suppressed.
The minute vibration control section 123 supplies the drive signal Com-B having the minute vibration waveform PS to the piezoelectric element PZa[m1] so as to control the minute vibration operation such that the stream FRb of ink in the Z1 direction that is generated in the nozzle N[m1] reaches the individual flow path PJ[m1].
According to the first embodiment, an effect of stirring ink inside and near the nozzle N and an effect of diffusing thickening of ink can be enhanced in comparison with an embodiment in which the stream FRb does not reach the nozzle flow path Nf. However, as described with reference to
In addition, the individual flow path PJ[m1] includes the pressure chamber Ca[m1] positioned upstream of the nozzle N[m1] and the pressure chamber Cb[m1] positioned downstream of the nozzle N[m1], the piezoelectric element PZa[m1] corresponds to the pressure chamber Ca[m1], the liquid ejection head 10 further includes the piezoelectric element PZb[m1] that corresponds to the pressure chamber Cb[m1] and that is driven in response to supply of the drive signal Com, and the minute vibration control section 123 controls the minute vibration operation by driving both of the piezoelectric element PZa[m1] and the piezoelectric element PZb[m1].
As described above, a pressure applied to ink from the piezoelectric element PZa and a pressure applied to the ink from the piezoelectric element PZb are merged with each other in the vicinity of the nozzle N which is positioned at the center of the individual flow path PJ and a portion of the merged pressure proceeds in a direction toward the nozzle N. Therefore, according to the first embodiment, the stream FRb along the Z-axis can be generated.
In addition, the individual flow path PJ[m1] further includes the narrowed portion Ap1[m1] that is positioned upstream of the pressure chamber Ca[m1] and of which the flow path resistance is higher than that of the pressure chamber Ca[m1] and the narrowed portion Ap2 [m1] that is positioned downstream of the pressure chamber Cb[m1] and of which the flow path resistance is higher than that of the pressure chamber Cb[m1].
When a pressure is applied to the pressure chamber Ca[m1] because of the minute vibration operation, the pressure is transmitted to a position upstream of the pressure chamber Ca[m1] and a position downstream of the pressure chamber Ca[m1]. Here, the narrowed portion Ap1[m1] positioned upstream of the pressure chamber Ca[m1] has a higher flow path resistance than that of the pressure chamber Ca[m1]. Therefore, the ratio of a pressure transmitted to the position downstream of the pressure chamber Ca[m1] to the pressure applied to the pressure chamber Ca[m1] is larger than the ratio of a pressure transmitted to the narrowed portion Ap1 to the pressure applied to the pressure chamber Ca[m1]. Similarly, the ratio of a pressure transmitted to the position downstream of the pressure chamber Cb[m1] to the pressure applied to the pressure chamber Cb[m1] is larger than the ratio of a pressure transmitted to the narrowed portion Ap2 to the pressure applied to the pressure chamber Cb[m1]. Therefore, with the minute vibration operation according to the first embodiment, it is possible to generate the stream FRb along the Z-axis that is large in comparison with the embodiment in which no narrowed portion Ap is present. Since the larger stream FRb can be generated, with the liquid ejecting apparatus 100 according to the first embodiment, it is possible to stir the thickened ink Bu inside and near the nozzle N in a short period of time.
The liquid ejection head 10 further includes the piezoelectric element PZa[m2] that is driven in response to supply of the drive signal Com, the nozzle N[m2] that ejects ink by means of a pressure that is applied when the piezoelectric element PZa[m2] is driven, the individual flow path PJ[m2] that communicates with the nozzle N[m2], through which ink is supplied to the nozzle N[m2], and through which ink not ejected from the nozzle N[m2] is discharged, the common supply flow path CF1 that is coupled to both of the individual flow path PJ[m1] and the individual flow path PJ[m2] and through which ink is supplied to the individual flow path PJ[m1] and the individual flow path PJ[m2], the common discharge flow path CF2 that is coupled to both of the individual flow path PJ[m1] and the individual flow path PJ[m2] and through which the ink is discharged from the individual flow path PJ[m1] and the individual flow path PJ[m2], and the bypass flow path BP that is coupled to the common supply flow path CF1 and the common discharge flow path CF2 and of which the flow path resistance is lower than those of the individual flow path PJ[m1] and the individual flow path PJ[m2], the liquid ejecting apparatus 100 further includes the pump 157 that is provided upstream of the liquid ejection head 10, and the circulation control section 127 controls the circulation operation by driving the pump 157.
An ink stream in the bypass flow path BP that is caused by the circulation operation is larger than the stream FRc of ink in each of the individual flow path PJ[m1] and the individual flow path PJ[m2] that is caused by the circulation operation. Therefore, the stream FRc in the individual flow path PJ according to the first embodiment is smaller than the stream FRc in the individual flow path PJ according to an embodiment in which the bypass flow path BP is not present. When the stream FRc of ink is small, the stream FRb caused by the minute vibration operation becomes relatively large. Therefore, a degree to which the stream FRc meanders is large and it is difficult for the stream FRc to reach the region downstream of the nozzle N in the nozzle flow path Nf. Therefore, in the first embodiment, the circulation operation is started before the minute vibration operation so that a situation where the stream FRb is not present (that is, a situation where the stream FRc does not meander) can be achieved. Since the stream FRc does not meander, the thickened ink Bu staying in the region downstream of the nozzle N in the nozzle flow path Nf can be discharged.
Accordingly, in the case of the first embodiment, air bubbles of ink can be retrieved since the bypass flow path BP is provided. Furthermore, the thickened ink Bu staying in the region downstream of the nozzle N in the nozzle flow path Nf can be discharged since the circulation operation is started before the minute vibration operation.
In addition, a pressure that is applied to ink in the individual flow path PJ per unit period because of the minute vibration operation is larger than a pressure that is applied to the ink in the individual flow path PJ per unit period because of the circulation operation.
In comparison with an embodiment in which a pressure that is applied per unit period because of the minute vibration operation is smaller than a pressure that is applied per unit period because of the circulation operation, a degree to which the stream FRc caused by the circulation operation meanders because of the stream FRb caused by the minute vibration operation is large and it is difficult for the stream FRc to reach the region downstream of the nozzle N in the nozzle flow path Nf. Therefore, in the first embodiment, the circulation operation is started before the minute vibration operation so that a situation where the stream FRc does not meander can be achieved.
A second embodiment is different from the first embodiment in that a flushing operation is performed immediately before the printing ejection operation. Hereinafter, the second embodiment will be described.
Note that, in the second embodiment, in addition to the ejection waveform PX, the flushing waveform is also an example of the “second waveform”. Similarly, in addition to the printing ejection operation, the flushing operation is also an example of the “ejection operation of causing liquid to be ejected from the first nozzle”.
A series of operations in the liquid ejecting apparatus 100-A will be described with reference to
In the second embodiment, the description will be made on assumption that all of M ejectors D of one head main body 14 perform the flushing operation in a period T12 from the time Td1 to the time Td2. However, a configuration in which a portion of the M ejectors D performs the flushing operation and the remainder of the M ejectors D performs the minute vibration operation may also be adopted.
Since the printing ejection operation is not performed in the period T12, the flushing control section 124 generates the waveform designation signal dCom such that the drive signal Com-A having the flushing waveform is supplied to the head main body 14, for example. Then, the flushing control section 124 generates the individual designation signal Sd[m] for designation of the flushing operation, with respect to every m ranging from 1 to M. In the period T12, the individual designation signal Sd[m] may show any of a value (1) for designation of the flushing operation and a value (0) for designation of the minute vibration operation. When the drive signal Com-A having the flushing waveform is supplied to the head main body 14 and the individual designation signal Sd[m] shows the value (1), the flushing operation is performed. In the period T12, the minute vibration operation is temporarily stopped in the ejector D for which the flushing operation is designated.
Each of the above-described embodiments can be modified in various manners. A specific embodiment of modification will be described below. Any two or more embodiments selected from the following examples can be appropriately combined with each other as long as there is no contradiction.
In each of the above-described embodiments, the period Tgh is shorter than the period Tab. However, the disclosure is not limited thereto. For example, the period Tgh may be longer than the period Tab. In other words, a period in which only the circulation operation is performed after the printing ejection operation may be longer than a period in which only the circulation operation is performed before the printing ejection operation.
When the period before the printing ejection operation is long, a period for which a user waits for the end of the printing process is made long. Meanwhile, at a time after the printing ejection operation, an image has been already formed on the medium PP and thus the length of a period for which a user waits for the end of the printing process is not changed even if the period Tgh is made long. Therefore, according to the first modification example, a period for which the user waits for the end of the printing process can be shortened and thickening after the printing ejection operation can be eliminated more in comparison with an embodiment in which the period Tgh is shorter than the period Tab.
In the first embodiment and the first modification example based on the first embodiment, the printing ejection operation is started after the cap unsealing operation is started. However, the cap unsealing operation and the printing ejection operation may not be performed. For example, when the printing ejection operation is not performed for a long period and thus there is a possibility that thickening of ink is excessively progressed, the liquid ejecting apparatus 100 may start the circulation operation, start the minute vibration operation thereafter, end the minute vibration operation after a certain period elapses with the cap sealing operation being performed, and end the circulation operation after the end of the minute vibration operation.
In addition, in the second embodiment and the first modification example based on the second embodiment, the printing ejection operation is started after the flushing operation is performed. However, the printing ejection operation may not be performed. For example, when the printing ejection operation is not performed for a long period and thus there is a possibility that thickening of ink is excessively progressed, the liquid ejecting apparatus 100-A may start the circulation operation, start the minute vibration operation thereafter, start the cap unsealing operation after the start of the minute vibration operation, start the cap sealing operation without the printing ejection operation after performing the flushing operation after the start of the cap unsealing operation, end the minute vibration operation after the start of the cap sealing operation, and end the circulation operation after the end of the minute vibration operation.
In each of the above-described embodiments, the period Tab is shorter than the period Tbc. However, the disclosure is not limited thereto. For example, the period Tab may have the same length as the period Tbc and may be longer than the period Tbc.
In each of the above-described embodiments, the time Th is later than the time Tg. However, the disclosure it not limited thereto. For example, the time Th may be the same time as the time Tg and may be earlier than the time Tg.
In each of the above-described embodiments, one individual flow path PJ includes two pressure chambers C. However, one individual flow path PJ may include one pressure chamber C. Examples of an embodiment in which one individual flow path PJ includes one pressure chamber C include two embodiments as follows. In the first of the two embodiments, all of the M individual flow paths PJ include pressure chambers Ca without the pressure chambers Cb. In the second of the two embodiments, odd-numbered individual flow paths PJ of the M individual flow paths PJ include the pressure chambers Ca without the pressure chambers Cb and even-numbered individual flow paths PJ include the pressure chambers Cb without the pressure chambers Ca.
In each of the above-described embodiments, the liquid ejection head 10 constitutes a line head. However, the disclosure is not limited to such a configuration and a serial type configuration in which the liquid ejection head 10 reciprocates along the X-axis may also be adopted.
The liquid ejecting apparatus 100 described in each of the above-described embodiments can be adopted for various devices such as a facsimile machine and a copier in addition to a device dedicated to printing. However, the purpose of use of the liquid ejecting apparatus of the present disclosure is not limited to printing. For example, a liquid ejecting apparatus that ejects a solution of a coloring material is used as a manufacturing device forming a color filter of a liquid crystal display device. In addition, a liquid ejecting apparatus that ejects a solution of a conductive material is used as a manufacturing device forming a wire or an electrode on a wiring substrate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-074876 | Apr 2022 | JP | national |
