Liquid discharge head, liquid discharge device and control method for liquid discharge head

Abstract

To provide a liquid discharge head which can suppress occurrence of density unevenness, a liquid discharge device and a control method for a liquid discharge head.SOLUTION: A liquid discharge head includes an actuator for varying capacity of a plurality of pressure chambers, a nozzle plate formed with a plurality of nozzles, a plurality of electrodes, and a driving circuit. The driving circuit is electrically independently connected with each of the plurality of electrodes, and generates a driving waveform for driving the pressure chambers in the plurality of electrodes. The plurality of nozzles are grouped for each nozzle. The driving circuit shifts driving timing of the pressure chambers in different delay time set by the sum of main delay time and sub-delay time for each group. The sub-delay time is set in a triangular wave shape of a constant cycle with respect to nozzle numbers of the adjacent grouped nozzles, monotonously increases from a minimum value to a maximum value of the sub-delay time in the cycle and monotonously decreases from the maximum value to the minimum value, and the increase width and the decrease width are the same.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] 1. Field of the Invention The present invention relates to a liquid ejection head, a liquid ejection apparatus, and a method for controlling a liquid ejection head. [Background technology]

[0002] In a conventional method for driving a piezoelectric inkjet head, a technique is known in which multiple nozzles are divided into groups and the drive timing is shifted by a different delay time for each group. This inkjet head drive method can avoid current concentration during simultaneous drive and reduce structural or fluidic mutual interference between nozzles, i.e. crosstalk. In this technique, the delay time is set as the sum of the main delay time (delay amount) and the sub-delay time (shift time). However, since the sub-delay time is a sawtooth wave that is discontinuous in the nozzle arrangement direction, this technique is prone to density unevenness at discontinuous locations when applied to an inkjet head with a one-dimensional nozzle arrangement. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-32580 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the present invention, it is possible to provide a liquid ejection head, a liquid ejection device, and a method for controlling a liquid ejection head, which are capable of suppressing large changes in the drive timing between adjacent nozzles and suppressing the occurrence of density unevenness. [Means for solving the problem]

[0005] A liquid ejection head according to an embodiment includes a plurality of pressure chambers, an actuator, a nozzle plate, a plurality of electrodes, and a drive circuit. The actuator varies the volume of the plurality of pressure chambers. The nozzle plate has a plurality of nozzles formed therein corresponding to the plurality of pressure chambers. The plurality of electrodes are formed on the inner surfaces of the plurality of pressure chambers. The drive circuit generates a drive waveform for driving the pressure chambers to the plurality of electrodes to which the plurality of electrodes are electrically independent and connected. The plurality of nozzles are grouped into groups of some of the nozzles. The drive circuit shifts the drive timing of the pressure chambers by a different delay time set by the sum of a main delay time and a sub-delay time for each group. The sub-delay time is set in a triangular wave shape with a constant period for the nozzle numbers of the nozzles grouped adjacent to each other, and increases monotonically from the minimum value to the maximum value and decreases monotonically from the maximum value to the minimum value with respect to the minimum and maximum values ​​of the sub-delay time within the period, with the increase width and decrease width being the same. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a configuration of a liquid ejection head according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the configuration of a main part of a head body of the liquid ejection head according to the embodiment. [Diagram 3] FIG. 2 is a cross-sectional view showing the configuration of a main part of a head body of the liquid ejection head according to the embodiment. [Figure 4] FIG. 2 is a block diagram showing the configuration of a circuit board of the liquid ejection head according to the embodiment. [Diagram 5] 5A and 5B are explanatory diagrams showing examples of drive waveforms with different drive timings for nozzles in each group of the liquid ejection head according to the embodiment. [Figure 6] 5A and 5B are explanatory diagrams showing an example of a main delay time of the liquid ejection head according to the embodiment. [Figure 7] FIG. 4 is an explanatory diagram showing an example of a main delay time and a sub-delay time according to the embodiment. [Figure 8] 5A to 5C are explanatory diagrams showing examples of a main delay time, a sub-delay time, and a delay time according to the embodiment. [Figure 9] FIG. 11 is an explanatory diagram showing an example of a main delay time and a sub-delay time of a liquid ejection head according to the prior art. [Figure 10] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a liquid ejection apparatus that uses a liquid ejection head according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] A liquid ejection head 1 according to an embodiment and a liquid ejection device 2 using the liquid ejection head 1 will be described below with reference to FIGS. 1 to 10. FIG. 1 is a perspective view showing the configuration of the liquid ejection head 1 according to the embodiment, FIG. 2 is a perspective view showing the configuration of the main part of the head body 11 of the liquid ejection head 1, and FIG. 3 is a cross-sectional view showing the configuration of the main part of the head body 11. FIG. 4 is a block diagram showing the configuration of the circuit board 13 of the liquid ejection head 1, and FIG. 5 is an explanatory diagram showing an example of a drive waveform of the liquid ejection head 1 with different drive timings of the nozzles 1141 for each group. FIG. 6 is an explanatory diagram showing an example of an optimal time difference of the main delay time of the liquid ejection head 1, FIG. 7 is an explanatory diagram showing an example of the main delay time and the sub-delay time, and FIG. 8 is an explanatory diagram showing an example of the main delay time, the sub-delay time, and the delay time. FIG. 9 is an explanatory diagram showing an example of the main delay time and the sub-delay time of a liquid ejection head according to a comparative example to be compared with the embodiment as a conventional technology. 10 is an explanatory diagram that shows a schematic configuration of a liquid ejection device 2 that uses a liquid ejection head 1 according to an embodiment. Note that in each drawing, the configuration is enlarged, reduced, or omitted as appropriate for the purpose of explanation.

[0008] The liquid ejection head 1 is, for example, a share mode inkjet head that ejects ink as a liquid onto a recording medium such as a paper sheet. The liquid ejection head 1 is provided in a liquid ejection device 2 such as an inkjet recording device shown in Fig. 10. The liquid ejection head 1 is provided in a head unit 2130 that includes a supply tank 2132 as a liquid storage section provided in the liquid ejection device 2.

[0009] The liquid ejection head 1 is supplied with ink as liquid stored in a supply tank 2132. The liquid ejection head 1 may be a non-circulation type head that does not circulate ink, or may be a circulation type head that circulates ink. The liquid ejection head 1 is connected to a temperature adjustment device 2116 provided in the liquid ejection device 2, and is supplied with temperature adjustment liquid (temperature adjustment water) that controls the temperature of the ink.

[0010] 1, the liquid ejection head 1 includes a head body 11, a manifold unit 12, and a circuit board 13. For example, the liquid ejection head 1 is a side shooter type four-row integrated structure head that includes a pair of head bodies 11 each having a pair of actuators 113.

[0011] 1 to 3, the head body 11 includes a substrate 111, a frame member 112, an actuator 113 having a plurality of pressure chambers 1131 and a plurality of air chambers 1132, a nozzle plate 114, and electrodes 115 formed on the substrate 111 and the actuator 113. The head body 11 forms a common liquid chamber 116 by the substrate 111, the frame member 112, and the nozzle plate 114, and by arranging the actuator 113 in the common liquid chamber 116, the plurality of pressure chambers 1131 and the common liquid chamber 116 are fluidly connected to each other.

[0012] In this embodiment, an example will be described in which the head body 11 has a pair of actuators 113, and the common liquid chamber 116 communicates with both ends of a plurality of pressure chambers 1131 formed in each of the pair of actuators 113.

[0013] The substrate 111 is formed, for example, of a rectangular plate from a ceramic material. The substrate 111 is formed, for example, of a rectangular shape that is long in one direction. A wiring pattern that forms a part of the electrode 115 is formed on one surface of the substrate 111. As a specific example, a wiring pattern that becomes a part of a plurality of individual electrodes 118 (described later) of the electrode 115 and a wiring pattern that becomes a part of a single common electrode 119 are formed on one surface of the substrate 111. A pair of actuators 113 are provided on one surface of the substrate 111 side by side in the short direction of the substrate 111. The one surface of the substrate 111 refers to one of the main surfaces of the substrate 111. The substrate 111 has, for example, one or more supply ports 1111 and multiple discharge ports 1112. The supply port 1111 and the discharge port 1112 are through holes formed in the substrate 111 and penetrating between both main surfaces of the substrate 111.

[0014] The supply port 1111 is an inlet for supplying ink to the common liquid chamber 116. The supply port 1111 is a through hole formed in the center of the short side direction of the substrate 111. The supply port 1111 extends along the longitudinal direction of the substrate 111. In other words, the supply port 1111 is, for example, a long hole that is long in one direction along the longitudinal direction of the actuators 113 and the longitudinal direction of the common liquid chamber 116. The supply port 1111 is provided between the pair of actuators 113, and opens at a position facing the common liquid chamber 116.

[0015] The discharge port 1112 is an outlet for discharging ink from the common liquid chamber 116. A plurality of discharge ports 1112 are provided. Each discharge port 1112 is provided in the common liquid chamber 116.

[0016] The frame member 112 is fixed by an adhesive or the like to one main surface of the substrate 111. The frame member 112 surrounds a supply port 1111, a plurality of discharge ports 1112, and an actuator 113, which are provided in the substrate 111. For example, the frame member 112 has a stepped structure.

[0017] For example, the frame member 112 is formed in a rectangular frame shape, thereby forming an opening that is long in one direction along the longitudinal direction of the frame member 112. A pair of actuators 113, a supply port 1111, and four exhaust ports 1112 are arranged in the opening of the frame member 112. When the liquid ejection head 1 is of a circulation type, the exhaust port 1112 as shown in Fig. 2 is provided, but when it is of a non-circulation type, the exhaust port 1112 as shown in Fig. 2 is not provided.

[0018] The pair of actuators 113 is adhered to the mounting surface of the substrate 111. The pair of actuators 113 are arranged in two rows on the substrate 111 with a supply port 1111 in between. The actuators 113 are formed in a plate shape that is long in one direction. The actuators 113 are placed in the opening of the frame member 112 and adhered to the main surface of the substrate 111.

[0019] 1 to 3, the actuator 113 has a plurality of pressure chambers 1131 arranged at equal intervals in the longitudinal direction, and a plurality of air chambers 1132 arranged at equal intervals in the longitudinal direction and disposed between adjacent pressure chambers 1131. In other words, in the actuator 113, a plurality of pressure chambers 1131 and a plurality of air chambers 1132 are alternately arranged along the longitudinal direction.

[0020] The surface of the actuator 113 opposite to the substrate 111 is bonded to the nozzle plate 114. The actuators 113 are arranged at equal intervals in the longitudinal direction, and a plurality of grooves 1133 are formed along a direction perpendicular to the longitudinal direction. The plurality of grooves 1133 form a plurality of pressure chambers 1131 and a plurality of air chambers 1132. That is, the plurality of grooves 1133 include a plurality of pressure grooves constituting the plurality of pressure chambers 1131 and a plurality of air grooves constituting the plurality of air chambers 1132. In other words, the actuator 113 has a plurality of piezoelectric bodies 1134 that are arranged at equal intervals in the longitudinal direction and are driving elements that constitute walls that form the grooves 1133 therebetween. The plurality of piezoelectric bodies 1134 form a plurality of pressure chambers 1131 and a plurality of air chambers 1132 between adjacent piezoelectric bodies 1134, and the volume of the pressure chamber 1131 is changed by application of a driving voltage.

[0021] For example, the width of the actuator 113 in the short side direction gradually increases from the top side fixed to the nozzle plate 114 toward the substrate 111 side. The cross-sectional shape of the cross section along the direction perpendicular to the longitudinal direction of the actuator 113 (short side direction) is formed into a trapezoidal shape. In other words, the side surface of the actuator 113 in the short side direction is an inclined surface that is inclined at a predetermined angle.

[0022] As a specific example, as shown in FIG. 3, the actuator 113 is formed of a laminated piezoelectric member in which two rectangular piezoelectric materials 1135 each long in one direction are bonded to face each other so that their polarization directions are opposite to each other. Here, the piezoelectric material 1135 is, for example, PZT (lead zirconate titanate). The actuator 113 is bonded to the mounting surface of the substrate 111 by, for example, a thermosetting epoxy adhesive. The actuator 113 forms an inclined surface by, for example, cutting processing. In addition, the surfaces of the substrate 111 and the actuator 113 on which the multiple individual electrodes 118 and the common electrode 119 of the electrode 115 are patterned are polished by, for example, polishing processing to form a polished surface. For example, the polished surface is formed on the inclined surface of the actuator 113 and on the substrate 111 at the foot of the inclined surface. Furthermore, in the actuator 113, a plurality of grooves 1133 that form a plurality of pressure chambers 1131 and a plurality of air chambers 1132 are formed, for example, by cutting, and a piezoelectric body (driving element) 1134 that is a side wall that separates adjacent grooves 1133 is formed.

[0023] Further, in the actuator 113, a wiring pattern that becomes a part of the individual electrodes 118, and a wiring pattern that becomes a part of one or more common electrodes 119 are formed.

[0024] The pressure chambers 1131 deform when the liquid ejection head 1 performs an operation such as printing, thereby ejecting ink from the nozzles 1141. The pressure chambers 1131 are formed so that the openings in the short side direction of the actuator 113 each open to the common liquid chamber 116, allowing ink to flow in and out of the pressure chambers 1131.

[0025] The air chamber 1132 is separated from the common liquid chamber 116 by blocking both sides in the longitudinal direction of the air groove formed in the actuator 113 with liquid-proof walls 1136, which are resin walls formed of photosensitive resin or the like. As a specific example, the liquid-proof walls 1136 of the air chamber 1132 are formed by injecting ultraviolet-curable resin into the groove forming the air chamber 1132, and then irradiating necessary portions, for example, both ends of the groove 1133 adjacent to the common liquid chamber 116, with ultraviolet light using a mask plate or the like. Such liquid-proof walls 1136 prevent ink from entering the air chamber 1132. In addition, the liquid-proof walls 1136 are formed on the common electrode 119 formed in the air chamber 1132 of the actuator 113. In addition, the air chamber 1132 is blocked by the nozzle plate 114, and no nozzle 1141 is arranged therein. Therefore, no ink flows into the air chamber 1132.

[0026] The nozzle plate 114 is formed in a plate shape. The nozzle plate 114 is fixed to the main surface of the frame member 112 opposite to the substrate 111 with an adhesive or the like. The nozzle plate 114 has a plurality of nozzles 1141 formed at positions facing the plurality of pressure chambers 1131. In this embodiment, the nozzle plate 114 has two nozzle rows 1142 in which the plurality of nozzles 1141 are aligned in one direction. That is, the liquid ejection head 1 has a one-dimensional nozzle arrangement in which the plurality of pressure chambers 1131 and the plurality of nozzles 1141 corresponding to the plurality of pressure chambers 1131 are aligned in one direction for one actuator 113.

[0027] 2 and 3, the electrode 115 includes, for example, a plurality of individual electrodes 118 connected to the plurality of pressure chambers 1131, and one or more common electrodes 119 connected to all or some of the plurality of air chambers 1132.

[0028] The electrodes 115 are formed on the upper surface of the substrate 111 and the inclined surface of the actuator 113 , and are also formed on the bottom and side surfaces of the multiple pressure chambers 1131 and the multiple air chambers 1132 .

[0029] The individual electrodes 118 apply a driving voltage individually to the electrodes 115 formed on the inner surfaces of the pressure chambers 1131. When the driving voltage is applied, a voltage is generated between the electrodes 115 and the common electrode 119 formed on the inner surfaces of the adjacent air chambers 1132, and the piezoelectric body 1134 is deformed. That is, the individual electrodes 118 individually deform each pressure chamber 1131. As shown in FIGS. 2 and 3, the individual electrodes 118 are formed by a wiring pattern formed on the substrate 111, a wiring pattern formed on the inclined surface of the actuator 113, and a wiring pattern formed on the bottom and side surfaces as the inner surfaces of the pressure chambers 1131. The individual electrodes 118 are connected to the circuit board 13.

[0030] The common electrode 119 is electrically connected to the electrode 115 formed on the inner surface of the air chamber 1132. As shown in FIG. 2 and FIG. 3, the common electrode 119 is formed by a wiring pattern formed on the substrate 111 and a wiring pattern formed on the actuator 113. The common electrode 119 is a wiring pattern formed in a predetermined region avoiding the region on the substrate 111 where the multiple individual electrodes 118 are formed, on the inclined surface of the actuator 113 opposite to the inclined surface on which the multiple individual electrodes 118 are formed, and across the bottom and side surfaces of the multiple air chambers 1132. The common electrode 119 may also be formed on the surface of the substrate 111 opposite to the surface on which the actuator 113 is provided, and on the inner peripheral surface of the supply port 1111 of the substrate 111. The common electrode 119 is connected to the circuit board 13.

[0031] The manifold unit 12 includes a manifold, a top plate, an ink supply pipe, and an ink discharge pipe. By assembling each component integrally, the manifold unit 12 forms a flow path inside the manifold unit 12 that supplies ink from the primary side to the common liquid chamber 116 via the supply port 1111 and discharges ink from the common liquid chamber 116 to the secondary side via the discharge port 1112.

[0032] As shown in FIG. 1, circuit board 13 includes a wiring film 131 having one end connected to a connection portion of substrate 111, a driving IC 132 mounted on wiring film 131, and a printed wiring board 133 mounted on the other end of wiring film 131.

[0033] The circuit board 13 drives the actuator 113 by applying a drive voltage to the wiring pattern of the actuator 113 using a drive circuit formed in a drive IC 132 or the like, which includes a driver circuit 138 that is electrically independent and connected to each of the multiple individual electrodes (electrodes) 118, thereby increasing or decreasing the volume of the pressure chamber 1131 and ejecting droplets from the nozzle 1141.

[0034] The wiring film 131 is connected to the plurality of individual electrodes 118 and the common electrode 119. For example, the wiring film 131 is an ACF (anisotropic conductive film) fixed to the connection portion of the substrate 111 by thermocompression bonding or the like. For example, a plurality of wiring films 131 to be connected are provided for one head body 11. In this embodiment, two wiring films 131 are connected to one actuator 113. The wiring film 131 is, for example, a COF (chip on film) on which a driving IC 132 is mounted.

[0035] The driving IC 132 is connected to the plurality of individual electrodes 118 and the common electrode 119 via the wiring film 131. The driving IC 132 may be connected to the plurality of individual electrodes 118 and the common electrode 119 by other means, such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste), instead of the wiring film 131.

[0036] 4, the driving IC 132 includes, as a driving circuit, a delay time generating circuit 135 that generates a first delay time and a second delay time when driving the multiple pressure chambers 1131 when a print trigger is input, a driving waveform generating circuit 136 including multiple driving waveform generating circuits 1361 that generate driving waveforms for driving the pressure chambers 1131, a print data storage circuit 137 that stores print data, and a driver circuit 138 that drives the multiple pressure chambers 1131. Note that the delay time generating circuit 135, the drive waveform generating circuit 136, the print data storage circuit 137, and the driver circuit 138 may be configured to be provided on the circuit board 13, and may be, for example, partially formed on the driving IC 132 and the other partially formed on another component of the circuit board 13, such as the printed wiring board 133, or may be entirely formed on the component of the circuit board 13 other than the driving IC 132.

[0037] For example, when the driving IC 132 receives a print trigger signal, it generates a driving waveform and changes the voltage of the individual electrode 118 of the actuator 113, thereby deforming the piezoelectric body 1134 of the corresponding pressure chamber 1131. This changes the volume of the pressure chamber 1131, pressurizes the ink inside the pressure chamber 1131, and ejects the ink from the nozzle 1141.

[0038] Further, the nozzles 1141 (pressure chambers 1131) are divided into a predetermined number of groups, each of which has some of the nozzles 1141. The driving IC 132 outputs a driving waveform with a different driving timing for each of the nozzles 1141 divided into a predetermined group in response to a print trigger, as in the driving waveform shown in FIG. 5, to drive the pressure chambers 1131. For example, in a case where the nozzles 1141 are divided into eight groups, the driving IC 132 sets the driving timing in eight different timings and in an eight-nozzle cycle in response to the print trigger. The number of groups is not limited to eight groups, and may be an even number or an odd number as long as it is two or more. The driving timing is determined by the sum of the main delay time and the sub-delay time.

[0039] In this case, when grouping multiple nozzles 1141 into n groups, the nozzle 1141 at a predetermined position is taken as the first (reference) nozzle, the nozzle number of the first nozzle 1141 is taken as ni, the nozzle number of the second nozzle 1141 is taken as ni+1, the nozzle number of the third nozzle 1141 is taken as ni+2 and the nozzle number of the nth nozzle 1141 is taken as ni+(n-1).The nozzles 1141 whose (n-1) number is 0 or an even number are taken as even-numbered nozzles 1141 (even-numbered nozzles), and the nozzles 1141 whose (n-1) number is an odd number are taken as odd-numbered nozzles 1141 (odd-numbered nozzles) in the following explanation.

[0040] There is one type of main delay time. For example, the main delay time (first delay time) of the odd-numbered nozzle 1141 is set for the even-numbered nozzle 1141. For example, the main delay time is generated by the first delay time generation circuit 1351 of the delay time generation circuit 135 connected to the individual electrode 118 of the pressure chamber 1131 corresponding to the odd-numbered nozzle 1141. For example, the optimal value of the first delay time is the time at which the ejection speeds of the odd-numbered nozzle 1141 and the even-numbered nozzle 1141 become the same when they are driven simultaneously, and in this embodiment, as shown in FIG. 6 and FIG. 8, the optimal time difference is 2.7 μs. That is, since the grouped nozzles 1141 are arranged alternately in odd and even numbers, when the time difference (main delay time) between adjacent nozzles 1141 is 2.7 μs, the variation in the ejection speed due to structural or fluid crosstalk between the nozzles 1141 can be minimized.

[0041] As shown in Fig. 7, the sub-delay time is set in a triangular wave shape with a constant period for adjacent nozzle numbers. Triangular wave shape means that the sub-delay time increases monotonically from the minimum value to the maximum value and decreases monotonically from the maximum value to the minimum value for the minimum and maximum values ​​of the sub-delay time in the period, and the increase and decrease are the same. The sub-delay time is set at its minimum value for two adjacent nozzles 1141, and similarly, at its maximum value for two adjacent nozzles 1141. For example, the sub-delay time is generated by each second delay time generation circuit 1352 of the delay time generation circuit 135 connected to the individual electrode 118 of the pressure chamber 1131 corresponding to each nozzle 1141.

[0042] 8, when the period is 8 nozzles and the time difference of the secondary delay times is 0.1 μs, the minimum value of the delay time for each nozzle 1141 is 0 μs and the maximum value is 0.3 μs. The secondary delay time (second delay time) for nozzle number 8i is 0 μs, for nozzle number 8i+1 the secondary delay time is 0 μs, for nozzle number 8i+2 the secondary delay time is 0.1 μs, for nozzle number 8i+3 the secondary delay time is 0.2 μs, for nozzle number 8i+4 the secondary delay time is 0.3 μs, for nozzle number 8i+5 the secondary delay time is 0.3 μs, for nozzle number 8i+6 the secondary delay time is 0.2 μs, and for nozzle number 8i+7 the secondary delay time is 0.1 s. In this way, the minimum secondary delay time and the maximum secondary delay time are set for two adjacent nozzles 1141, and secondary delay times other than the minimum and maximum values ​​are set with the time difference of the set secondary delay from the minimum value to the maximum value and from the maximum value to the minimum value.

[0043] The delay time for each nozzle 1141 as the drive timing is set by the sum of the main delay time and the sub-delay time for each group, and the delay time is distributed to eight different timings of 0 μs, 0.1 μs, 0.2 μs, 0.3 μs, 2.7 μs, 2.8 μs, 2.9 μs, and 3.0 μs, as shown in Fig. 8, effectively reducing current concentration during simultaneous drive. The time difference between adjacent nozzles 1141 is in the range of 2.6 μs to 2.8 μs.

[0044] That is, when the delay time (drive timing) which is the sum of the main delay time and the secondary delay time in each nozzle 1141 is set to 0 μs for nozzle number 8i, the secondary delay time for nozzle number 8i+1 is 2.7 μs, the secondary delay time for nozzle number 8i+2 is 0.1 μs, the secondary delay time for nozzle number 8i+3 is 2.9 μs, the secondary delay time for nozzle number 8i+4 is 0.3 μs, the secondary delay time for nozzle number 8i+5 is 3.0 μs, the secondary delay time for nozzle number 8i+6 is 0.2 μs, and the secondary delay time for nozzle number 8i+7 is 2.8 s. In this way, the drive timing of adjacent nozzles 1141 is set within a range of ±0.1 μs with respect to the main delay time (2.7 μs), which is the optimal time difference for the even and odd nozzles 1141 shown in FIG. 6, so that the variation in the ejection speed due to crosstalk can be minimized. Furthermore, since there is no significant change in the time difference between adjacent nozzles 1141, the occurrence of uneven density between the adjacent nozzles 1141 can be suppressed.

[0045] In this way, when the driving IC 132 including the driving circuit receives a print trigger signal, it generates a driving waveform with different driving timings (delay times) shown in FIG. 8 for each of the nozzles 1141 divided into predetermined groups, based on the main delay time based on the optimal time difference between the even-numbered and odd-numbered nozzles 1141 shown in FIG. 6 to FIG. 8 and the triangular wave-shaped secondary delay time shown in FIG. 7 and FIG. 8. Then, as shown in FIG. 5, the driving IC 132 generates a driving waveform for the individual electrode 118 corresponding to each nozzle 1141 with different driving timings, and applies the driving waveform to the individual electrode 118 of the corresponding pressure chamber 1131. That is, the driving IC 132 changes the volume of the corresponding pressure chamber 1131 by deforming the piezoelectric body 1134 of the corresponding pressure chamber 1131 with different driving timings, thereby discharging ink. In FIG. 5, Td1 is the main delay time, Td2 is the time difference between the secondary delay times, and Tc is one cycle of the discharging operation.

[0046] The printed wiring board 133 is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted.

[0047] In the liquid ejection head 1 configured in this manner, the driving IC 132, upon receiving a print trigger signal, generates a driving waveform based on print data for each of the nozzles 1141 divided into predetermined groups, at different driving timings (delay times) shown in Fig. 8, based on a main delay time based on the optimal time difference between the even-numbered and odd-numbered nozzles 1141 shown in Figs. 6 to 8 and a triangular-wave-shaped sub-delay time shown in Figs. 7 and 8. Then, the driving IC 132 applies the driving waveform to the individual electrodes 118 corresponding to each nozzle 1141 at different driving timings, as shown in Fig. 5. In this manner, the driving circuit of the driving IC 132 drives and controls the pressure chambers 1131 of the actuator 113 at different driving timings, as a control method.

[0048] That is, the driving IC 132 changes the volume of the corresponding pressure chamber 1131 by deforming the piezoelectric body 1134 of the corresponding pressure chamber 1131 with different driving timings, thereby discharging ink. The liquid discharge head 1 can minimize the variation in discharge speed caused by structural or fluid crosstalk between the nozzles 1141 by setting the main delay time between adjacent nozzles 1141 to an optimal time difference. In addition, the liquid discharge head 1 sets the sub-delay time to a triangular wave shape with a constant period for adjacent nozzle numbers, so that the delay time (drive timing) of the adjacent nozzles 1141 is set to a drive timing within a range of ±0.1 μs with respect to the main delay time (2.7 μs), thereby minimizing the variation in discharge speed caused by crosstalk. In addition, since there is no large change in the time difference between the adjacent nozzles 1141, the occurrence of density unevenness between the adjacent nozzles 1141 can be suppressed. That is, if the secondary delay time is discontinuous (sawtooth wave-like) in the nozzle arrangement direction as in the conventional technology shown in Fig. 9, a large change occurs in the time difference between adjacent nozzles, resulting in density unevenness between adjacent nozzles. As such, the liquid ejection head 1 with a one-dimensional nozzle arrangement can suppress the occurrence of density unevenness by using the drive timing of the embodiment, compared to the configuration of the conventional technology in which the secondary delay time is discontinuous (sawtooth wave-like) in the nozzle arrangement direction as shown in Fig. 9.

[0049] According to the liquid ejection head 1 of the embodiment described above, the main delay time of the grouped nozzles 1141 is set to an optimal time difference, and the sub-delay time is set to a triangular wave shape to drive and control the pressure chambers 1131 (piezoelectric bodies 1134) with different drive timings for each group. This makes it possible for the liquid ejection head 1 to prevent large changes in the drive timing between adjacent nozzles 1141, thereby preventing uneven density.

[0050] A liquid ejection device 2 having a liquid ejection head 1 will be described below with reference to Fig. 10. The liquid ejection device 2 is an inkjet recording device that ejects ink. The liquid ejection device 2 includes a housing 2111, a medium supply unit 2112, an image forming unit 2113, a medium ejection unit 2114, a transport device 2115 that is a support device, a temperature adjustment device 2116, a maintenance device 2117, and a control unit 2118. The liquid ejection device 2 also includes a temperature adjustment device that adjusts the temperature of the ink supplied to the liquid ejection head 1.

[0051] The liquid ejection device 2 is an inkjet printer that performs an image formation process on paper P by ejecting liquid such as ink while transporting the paper P as a recording medium, which is the object of ejection, along a predetermined transport path 2001 from a medium supply section 2112 through an image forming section 2113 to a medium ejection section 2114.

[0052] The medium supply unit 2112 includes a plurality of paper feed cassettes 21121. The image forming unit 2113 includes a support unit 2120 that supports paper, and a plurality of head units 2130 that are disposed above and facing the support unit 2120. The medium discharge unit 2114 includes a paper discharge tray 21141.

[0053] The support section 2120 includes a conveyor belt 21201 provided in a loop shape in a predetermined area where image formation is performed, a support plate 21202 supporting the conveyor belt 21201 from the rear side, and a plurality of belt rollers 21203 provided on the rear side of the conveyor belt 21201.

[0054] The head unit 2130 includes liquid ejection heads 1 which are multiple inkjet heads, multiple supply tanks 2132 as liquid tanks mounted on each liquid ejection head 1, a pump 2134 which supplies ink, and a connection flow path 2135 which connects the liquid ejection heads 1 and the supply tanks 2132.

[0055] In this embodiment, the liquid ejection heads 1 are provided with four colors, cyan, magenta, yellow, and black, and four supply tanks 2132 for storing ink of each color. The supply tanks 2132 are connected to the liquid ejection heads 1 by connection flow paths 2135.

[0056] The pump 2134 is a liquid-sending pump constituted by, for example, a piezoelectric pump. The pump 2134 is connected to the control unit 2118, and is drive-controlled by the control unit 2118.

[0057] The connection flow path 2135 includes a supply flow path connected to the ink supply pipe 123 of the liquid ejection head 1. The connection flow path 2135 also includes a recovery flow path connected to the ink discharge pipe of the liquid ejection head 1. For example, if the liquid ejection head 1 is of a non-circulation type, the recovery circuit is connected to a maintenance device 2117, and if the liquid ejection head 1 is of a circulation type, the recovery flow path is connected to a supply tank 2132.

[0058] The transport device 2115 transports the paper P along a transport path 2001 that runs from a paper feed cassette 21121 of the medium supply unit 2112 through the image forming unit 2113 to a paper discharge tray 21141 of the medium discharge unit 2114. The transport device 2115 includes a plurality of guide plate pairs 21211-21218 and a plurality of transport rollers 21221-21228 that are arranged along the transport path 2001. The transport device 2115 supports the paper P so that it can move relative to the liquid ejection head 1.

[0059] The temperature adjustment device 2116 includes a temperature adjustment water tank 21161, a temperature adjustment circuit 21162 such as piping or tubes for supplying the temperature adjustment water, a pump for supplying the temperature adjustment water, and a temperature adjuster for adjusting the temperature of the temperature adjustment water. The temperature adjustment device 2116 supplies the temperature adjustment water in the temperature adjustment water tank 21161, which has been adjusted to a predetermined temperature by the temperature adjuster, to the temperature adjustment water supply pipe of the liquid ejection head 1 via the temperature adjustment circuit 21162 by the water supply of the pump. The temperature adjustment device 2116 also collects the water discharged from the temperature adjustment water discharge pipe through the manifold unit 12 into the temperature adjustment water tank 21161 via the temperature adjustment circuit 21162. The temperature adjuster is, for example, a heater or a cooler. The temperature adjustment device 2116 may also be configured to adjust the temperature of the ink supplied to the liquid ejection head 1.

[0060] The maintenance device 2117, for example, during maintenance, sucks and recovers ink remaining on the outer surface of the nozzle plate 114. Furthermore, if the liquid ejection head 1 is of a non-circulation type, the maintenance device 2117 recovers ink inside the head body 11 during maintenance. Such a maintenance device 2117 has a tray, tank, etc. for storing the recovered ink.

[0061] The control unit 2118 includes a CPU 21181 as an example of a processor, a ROM (Read Only Memory) for storing various programs, a RAM (Random Access Memory) for temporarily storing various variable data, image data, etc., and an interface unit for inputting data from the outside and outputting data to the outside.

[0062] According to the embodiment of the liquid ejection device 2 described above, the nozzles 1141 are divided into groups, and the main delay time is set to an optimal time difference, and the sub-delay time is set to a triangular wave shape, and the nozzles are driven and controlled at different drive timings for each group, thereby preventing large changes in the drive timing between adjacent nozzles 1141 and suppressing the occurrence of uneven density.

[0063] It should be noted that the embodiment of the present invention is not limited to the above-mentioned configuration. For example, in the above-mentioned example, the liquid ejection head 1 is described as having a pair of head bodies 11, but is not limited to this, and may be configured to have one head body 11. Also, in the above-mentioned liquid ejection head 1, an example in which the actuator 113 is of a share mode type is described, but is not limited to this, and the actuator may be of a stacked type.

[0064] According to at least one embodiment of the liquid ejection head described above, the nozzles are divided into groups, and the main delay time is set to an optimum time difference, and the secondary delay time is set in a triangular wave shape, and the nozzles are driven and controlled at different drive timings for each group, thereby preventing large changes in the drive timing between adjacent nozzles and suppressing the occurrence of density unevenness.

[0065] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0066] 1...liquid ejection head, 2...liquid ejection device, 11...head body, 12...manifold unit, 13...circuit board, 111...substrate, 112...frame member, 113...actuator, 114...nozzle plate, 115...electrode, 116...common liquid chamber, 118...individual electrode (electrode), 119...common electrode, 123...ink supply tube, 131...wiring film, 132...driving IC, 133...printed wiring board, 135...delay time generating circuit, 136...driving waveform generating circuit, 137...print data memory circuit, 138...driver circuit, 1111...supply port, 1112...discharge port, 1131...pressure chamber, 1132...air chamber, 1133...groove, 1134...piezoelectric body (driving element), 1135...piezoelectric material, 1136...liquid-proof wall, 1141...nozzle, 1142...nozzle row, 135 1...first delay time generating circuit, 1352...second delay time generating circuit, 1361...driving waveform generating circuit, 2001...transport path, 2111...housing, 2112...medium supply section, 2113...image forming section, 2114...medium discharge section, 2115...transport device, 2116...temperature control device, 2117...maintenance device, 2118...control section, 2120...support section, 2130...head unit, 2 132...supply tank, 2134...pump, 2135...connecting flow path, 21121...paper feed cassette, 21141...output tray, 21161...temperature control water tank, 21162...temperature control circuit, 21201...conveyor belt, 21202...support plate, 21203...belt roller, 21211 to 21218...guide plate pair, 21221 to 21228...conveyor roller, P...paper.

Claims

1. A plurality of pressure chambers; an actuator that varies the volumes of the pressure chambers; a nozzle plate in which a plurality of nozzles corresponding to the plurality of pressure chambers are formed; A plurality of electrodes respectively corresponding to the plurality of pressure chambers; a drive circuit for generating a drive waveform for driving the pressure chamber to the plurality of electrodes, the plurality of electrodes being electrically and independently connected to each other; Equipped with The plurality of nozzles are grouped into groups of some of the nozzles, the drive circuit shifts the drive timing of the pressure chambers by a different delay time that is set for each group by a sum of a main delay time and a sub-delay time, A liquid ejection head, wherein the secondary delay time is set in a triangular wave shape of a constant period for the nozzle numbers of the nozzles that are grouped together and, for the minimum and maximum values ​​of the secondary delay time within the period, monotonically increases from the minimum value to the maximum value and monotonically decreases from the maximum value to the minimum value.

2. The liquid ejection head according to claim 1 , wherein the main delay time is set between an odd-numbered nozzle and an even-numbered nozzle with respect to the nozzle numbers adjacent to each other.

3. The liquid ejection head of claim 1 , wherein the delay times for adjacent nozzles are in the range of 2.6 μs to 2.8 μs.

4. A liquid ejection apparatus comprising the liquid ejection head according to claim 1 .

5. a nozzle plate in which a plurality of nozzles corresponding to the plurality of pressure chambers are formed; a plurality of electrodes respectively corresponding to the plurality of pressure chambers; and a drive circuit that generates a drive waveform to electrically connect the plurality of electrodes to each of the plurality of electrodes independently of each other, the plurality of nozzles being grouped into groups of several of the nozzles, a drive timing of the pressure chambers is shifted by a different delay time set by a sum of a main delay time and a sub-delay time for each group, and the pressure chambers are driven to the plurality of electrodes; A control method for a liquid ejection head, wherein the secondary delay time is set in a triangular wave shape of a constant period for the nozzle numbers of the nozzles that are grouped together and, for the minimum and maximum values ​​of the secondary delay time within the period, monotonically increases from the minimum value to the maximum value and monotonically decreases from the maximum value to the minimum value.

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