JP2007283706A - Driving device of droplet discharge head and driving method of droplet discharge head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive device of a droplet discharge head and a driving method of the droplet discharge head capable of reducing the size of the driving device while suppressing reduction in a recording speed. <P>SOLUTION: A plurality of piezoelectric elements 52 are provided in a matrix state corresponding to nozzles. In each row of the matrix arrangement of the plurality of piezoelectric elements 52, one of the electrodes of each of the piezoelectric elements 52 in the same row is electrically connected to a common electrode 50. In each column of the matrix arrangement, the other electrodes of the n-units of continuous piezoelectric elements (n≥2) in the same column are electrically connected to an individual electrode 56. The common electrodes 50 corresponding to a row having an equal remainder with respect to the number of rows n from one end side in the row arrangement direction in the matrix arrangement are considered as the same electrode group so as to perform switching of power distribution for each electrode group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge head drive device and a droplet discharge head drive method, and more particularly to a droplet discharge head drive device in which a plurality of piezoelectric elements are provided in a matrix corresponding to each nozzle, and The present invention relates to a method for driving a droplet discharge head.

  Conventionally, by applying a driving voltage having a predetermined driving waveform to a piezoelectric element such as a piezo element, the piezoelectric element is deformed to generate a volume change (expansion / contraction) of a storage chamber in which the liquid is stored. 2. Related Art A droplet discharge device such as an ink jet printer provided with a droplet discharge head for discharging droplets is known.

  In recent years, with this type of droplet discharge device, there has been an increasing demand for higher recording speed and higher image quality of recorded images. The density is increased. Along with this, the number of piezoelectric elements provided in the droplet discharge head increases, and the number of switch elements for controlling the application of drive voltage to each piezoelectric element also increases, so that the droplet discharge head is driven. There was a problem that a drive device will be enlarged.

  Therefore, as a technique that can be applied to solve this problem, Patent Document 1 discloses the number of switch elements required for driving piezoelectric elements by individually driving each piezoelectric element arranged in a matrix. Techniques to reduce have been proposed.

Further, in Patent Document 2, a plurality of piezoelectric elements provided in a recording head, a first piezoelectric element group including a plurality of piezoelectric elements to which a common electrode is commonly connected, and a common electrode are commonly connected, By dividing the first piezoelectric element group and the second piezoelectric element group into a second electric element group composed of a plurality of piezoelectric elements different from the first piezoelectric element group, and driving the first piezoelectric element group and the second piezoelectric element group. Techniques for reducing the number of necessary switch elements have been proposed.
JP 63-51142 A Japanese Patent Laid-Open No. 10-250074

  However, the technique of Patent Document 1 has a problem in that the recording speed is greatly reduced although the size of the driving device can be reduced.

In other words, the drive waveform of the drive voltage applied to the piezoelectric element in order to generate a sufficient volume change in the storage chamber requires a period of several μsec to several tens of μsec. When the drive voltage is individually applied and driven, the greater the number of nozzles, the longer one period in which one dot of droplet is ejected from each nozzle of the droplet ejection head, and the recording speed is greatly reduced. That is, when driving in rows and columns is simply performed, the number of divisions becomes too large, and the printing cycle becomes longer. Further, the technique of Patent Document 2 described above is a piezoelectric element for only one line provided in the recording head. This is a technology for dividing the head, and cannot be simply applied to a droplet discharge head in which piezoelectric elements are arranged in a matrix. In addition, when a plurality of lines are used, the electrical wiring of the head becomes complicated.

  It is an object of the present invention to provide a droplet discharge head drive device and a droplet discharge head drive method that can reduce the size of the drive device while suppressing a decrease in recording speed and facilitate the electrical wiring of the head. Objective.

  To achieve the above object, the invention according to claim 1 is provided in a matrix corresponding to each nozzle, and a storage chamber in which a liquid is stored by applying a driving voltage having a predetermined driving waveform and deforming it. For each row in the matrix array of the plurality of piezoelectric elements, one electrode of each piezoelectric element in the same row is electrically connected A first electrode connected, a second electrode in which the other electrode of the continuous piezoelectric elements in the same column is electrically connected by n (n ≧ 2) for each column in the matrix arrangement, Switching means for switching presence / absence of ejection for each electrode group, with the first electrode corresponding to a row having the same remainder with respect to n of the number of rows from one end side in the row arrangement direction in the matrix arrangement as the same electrode group; It is equipped with a.

  According to the first aspect of the present invention, a plurality of piezoelectric elements are provided in a matrix corresponding to each nozzle, and a liquid is applied by applying a driving voltage having a predetermined driving waveform to each piezoelectric element and deforming each piezoelectric element. One of each piezoelectric element in the same row with respect to the first electrode is generated for each row in a matrix arrangement of a plurality of piezoelectric elements by generating a volume change in the accommodated storage chamber and discharging a droplet from a corresponding nozzle. Electrodes are electrically connected, and for each column in the matrix arrangement, the other electrode of the continuous piezoelectric elements in the same column is electrically connected to the second electrode by n (n ≧ 2). Yes.

  In the present invention, by the switching means, the first electrode corresponding to the row having the same remainder with respect to n of the number of rows from one end side in the row arrangement direction in the matrix arrangement is set as the same electrode group and whether or not ejection is performed for each electrode group. Switching is performed.

  Thus, according to the first aspect of the present invention, a plurality of piezoelectric elements are provided in a matrix corresponding to the nozzles, and one of each piezoelectric element in the same row is provided for each row in the matrix arrangement of the plurality of piezoelectric elements. The electrode is electrically connected to the first electrode, and the other electrode of the continuous piezoelectric elements in the same column is electrically connected to the second electrode by n (n ≧ 2) for each column in the matrix arrangement. Since the first electrodes corresponding to the rows having the same remainder with respect to n of the number of rows from one end side in the row arrangement direction in the matrix arrangement are made the same electrode group, one electrode is electrically connected to the same second electrode. The first electrodes electrically connected to the other electrodes of the n piezoelectric elements thus formed belong to different electrode groups. In the present invention, since the presence or absence of ejection is switched for each electrode group, when energization control is performed on the second electrode, n piezoelectric elements electrically connected to the second electrode are controlled. By switching the electrode groups that can be ejected by applying a voltage effective for ejection only to the piezoelectric elements that are electrically connected to the first electrode belonging to the electrode group that is capable of ejection, , N piezoelectric elements can be individually driven.

  In this way, by switching the electrode group, n piezoelectric elements can be individually driven by one second electrode, so the number of electrodes provided in the droplet discharge head can be reduced, and the number of electrodes can be reduced. Along with the decrease, the number of switch elements for controlling energization can be reduced, and as a result, the size of the drive device can be reduced. Further, since the number of wirings in the column direction on the head can be reduced, the electrical wiring of the head is facilitated.

  According to the first aspect of the present invention, since the piezoelectric elements can be divided and driven in units of electrode groups, each piezoelectric element is individually driven in a matrix even when the number of nozzles is increased. Compared to the case, a decrease in recording speed can be suppressed.

  Further, according to the first aspect of the present invention, since the first electrodes corresponding to the rows having the same remainder with respect to the number n of rows are grouped as the same electrode group, the first electrodes adjacent to each other in the same electrode group Is not included. Therefore, when the piezoelectric elements are divided and driven in units of electrode groups, the adjacent piezoelectric elements in the column direction are not driven, so structural strokes such as vibration and deformation from adjacent piezoelectric elements, vibration transmitted through the liquid, etc. The effect of the acoustic stroke can be prevented, and droplets can be ejected stably.

  According to the present invention, as described in claim 2, in one cycle in which droplets of one dot are ejected from each nozzle, the electrode groups that can be ejected are sequentially switched by controlling the switching unit, and The nozzle group that identifies the nozzle that ejects droplets based on image data to be recorded by the droplet ejection head, and to which the first electrode that is electrically connected to the piezoelectric element corresponding to the nozzle belongs It is preferable to further comprise control means for controlling whether or not energization can be performed on the second electrode electrically connected to the piezoelectric element at a timing at which discharge is possible.

  According to a second aspect of the present invention, the control means selects the driving voltage according to the amount of droplets ejected from a plurality of driving voltages, each having a different driving waveform, as in the third aspect, and selects the first driving voltage. You may perform the control made to apply with respect to 2 electrodes.

  On the other hand, in order to achieve the above object, the invention described in claim 4 is provided in a matrix corresponding to each nozzle, and the liquid is accommodated by applying a driving voltage of a predetermined driving waveform and deforming it. One electrode of each piezoelectric element in the same row is electrically connected to the first electrode for each row in a matrix arrangement of a plurality of piezoelectric elements that cause a volume change in the storage chamber to eject droplets from the corresponding nozzle. In addition, for each column in the matrix array, the other electrode of the continuous piezoelectric elements in the same column is electrically connected to the second electrode by n (n ≧ 2), and the row array direction in the matrix array The first electrode corresponding to a row having the same remainder with respect to n of the number of rows from one end side of the first electrode is used as the same electrode group, and the presence / absence of ejection is switched for each electrode group.

  Therefore, since the invention described in claim 4 operates in the same manner as the invention described in claim 1, similarly to the invention described in claim 1, the size of the driving device can be reduced while suppressing a decrease in recording speed. And electrical wiring of the head is facilitated.

  As described above, according to the present invention, it is possible to reduce the size of the driving device while suppressing a decrease in recording speed, and to have an excellent effect that the electric wiring of the head can be facilitated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, a case where the present invention is applied to an inkjet printer will be described.

  FIG. 1 shows the configuration of an ink jet printer (hereinafter simply referred to as “printer”) 10 according to the present embodiment.

  As shown in the figure, the printer 10 includes a controller 12 that controls the operation of the entire apparatus, a drive control circuit 14 that outputs various control signals for driving a droplet discharge head 20 described later, and a predetermined drive waveform. A drive voltage generation circuit 16 that generates a drive voltage and a droplet discharge head 20 that discharges droplets in accordance with various input control signals are provided.

  The droplet discharge head 20 includes a head unit 22 in which a plurality of nozzles 40 (see FIG. 2) for discharging droplets are provided in a matrix, and a plurality of controls for controlling the row direction in the matrix arrangement of the nozzles 40. A row control switch unit 24 provided with switch elements and a column control switch unit 26 provided with a plurality of switch elements for performing control related to the column direction in the matrix arrangement of the nozzles 40 are provided.

  The controller 12 includes a CPU, RAM, ROM, and the like (not shown). When image data is input from an external device (not shown), the image data is subjected to various image processing such as halftone processing, and predetermined printing is performed. The dot data designating the nozzle 20 for ejecting droplets from the droplet ejection head 20 at every cycle and recording the dots is sequentially output to the drive control circuit 14.

  When the input of dot data is started, the drive control circuit 14 generates a clock signal having a predetermined cycle and outputs the clock signal to the drive voltage generation circuit 16. Further, the drive control circuit 14 divides and drives the nozzles provided in the head unit 22 in n times (in this embodiment, twice) in synchronization with the generated clock signal based on the sequentially input dot data. A row control signal and a column control signal are generated to output the row control signal to the row control switch unit 24, and the column control signal is output to the column control switch unit 26.

  When the clock signal is input from the drive control circuit 14, the drive voltage generation circuit 16 generates a drive voltage having a predetermined drive waveform in synchronization with the clock signal and outputs the drive voltage to the column control switch unit 26.

  FIG. 2 shows a cross-sectional view of one nozzle portion of the plurality of nozzles 40 provided in the head unit 22 according to the present embodiment.

  As shown in the figure, the head unit 22 includes a nozzle 40, a common ink channel 42, a supply channel 44, a pressure chamber 46, and a piezoelectric element 52.

  An appropriate amount of ink liquid is supplied to the common ink flow path 42 from an ink cartridge (not shown) and is temporarily stored. The common ink flow path 42 communicates with the pressure chamber 46 via the supply path 44, and the pressure chamber 46 communicates with the outside via the nozzle 40.

  A part of the wall surface of the pressure chamber 46 is constituted by a diaphragm 48. A common electrode 50 is formed on the surface of the diaphragm 48 opposite to the pressure chamber 46. A piezoelectric element 52 is attached to the common electrode 50, and one electrode of the piezoelectric element 52 is electrically connected to the common electrode 50. Each common electrode 50 can be formed by providing an insulating film on the vibration plate 48 and forming a wiring pattern thereon by applying a conductive paste or sputtering.

  Further, a flexible printed wiring board (hereinafter referred to as “FPC”) 54 is bonded to the surface of the piezoelectric element 52 opposite to the common electrode 50. The FPC 54 has an individual electrode 56 and a pad 58 penetrating the FPC 54 and electrically energized. The individual electrode 56 and the other electrode of the piezoelectric element 52 are electrically connected via the pad 58. Yes.

  The piezoelectric element 52 is deformed by applying a driving voltage via the common electrode 50 and the individual electrode 56 to change the pressing force on the diaphragm 48 to generate a volume change in the pressure chamber 46. The ink stored in the common ink flow path 42 is ejected from the nozzle 40 through the supply path 44 and the pressure chamber 46 by the vibration wave (pressure wave) of the ink generated by the volume change inside.

  3A and 3B are plan views showing configurations of the common electrode 50 and the individual electrodes 56 of the head unit 22 according to the present embodiment.

  As shown in FIG. 3A, the common electrode 50 is formed for each row along the row direction of the piezoelectric elements 52 provided in a matrix, and each piezoelectric element 52 in the same row is electrically connected. It is connected.

  In the head unit 22 according to the present embodiment, the common electrodes 50 corresponding to the rows having the same remainder with respect to “2” that is the number of divided driving times of the number of rows from one end side in the row arrangement direction in the matrix arrangement are set as the same electrode group. For each electrode group, common electrodes 50 belonging to the same electrode group are connected in parallel by wiring, and the wiring is grounded via the switch element 60. That is, in FIG. 3A, the common electrodes 50 in the first, third, and fifth rows are grounded in parallel via the switch element 60A, and the common electrodes 50 in the second, fourth, and sixth rows are connected in parallel. It is grounded through 60B.

  On the other hand, as shown in FIG. 3B, a plurality of individual electrodes 56 are formed along the column direction for each column of piezoelectric elements 52 provided in a matrix, and n individual electrodes 56 are continuous in the same column. (In this case, two pads) 58 are electrically connected to one individual electrode 56, respectively.

  As shown in FIG. 4, in the head unit 22 according to the present embodiment, the FPC 54 is bonded so that the positions of the pads 58 correspond to the piezoelectric elements 52 provided in a matrix on the vibration plate 48. Thus, the individual electrode 56 and the piezoelectric element 52 are electrically connected, and in each column, the first and second rows of piezoelectric elements 52, the third and fourth rows of piezoelectric elements 52, and 5 are provided. The piezoelectric elements 52 in the rows and the sixth row are electrically connected to the same individual electrode 56, respectively.

  FIG. 5 shows an electrical configuration of the droplet discharge head 20 according to the present embodiment. In FIG. 5, in order to simplify the description, an example in which the piezoelectric elements 52 are provided in 6 rows and 3 columns in a matrix is described, but the number of rows of the piezoelectric elements 52 provided in the droplet discharge head 20 is described. The number of columns is not limited to this.

  As described above, in the droplet discharge head 20, one electrode of each piezoelectric element 52 provided in each row is electrically connected in parallel by the common electrode 50 (in FIG. 5, for each row). In addition, the common electrode 50 is shown as an equivalent circuit connected in parallel by wiring.) 1, 3, 5 rows in which the remainder when the number of rows is divided by “2”, which is the number of times of division driving, becomes “1” The common electrode 50 of the eye is grounded in parallel via the switch element 60A, and the common electrodes 50 in the second, fourth, and sixth rows having the remainder of “0” are grounded in parallel via the switch element 60B. .

  The switch elements 60A and 60B are controlled to be turned on / off by a row control signal A and a row control signal B respectively input from the drive control circuit 14, and when a predetermined high level signal is input. When the signal is turned on and a predetermined low level signal is input, the signal is turned off.

  In the droplet discharge head 20, the other electrode of two continuous piezoelectric elements 52 in the same column is electrically connected by one individual electrode 56 for each column. Each is connected via a switch element 62 to a wiring 64 to which a drive voltage is supplied. That is, the first and second piezoelectric elements 52 in the m-th column (m = 1 to 3 in FIG. 5) are connected to the wiring 64 through the switch element 62 mA by the individual electrode 56, and the third row in the m-th column. The piezoelectric elements 52 in the fourth row and the fourth row are connected to the wiring 64 by the individual electrode 56 via the switch element 62mB, and the piezoelectric elements 52 in the fifth and sixth rows in the m-th column connect the switch element 62mC by the individual electrode 56. And connected to the wiring 64.

  The switch elements 62 mA to 62 mC (m = 1 to 3 in FIG. 5) are controlled to be turned on / off by row control signals mA to mC input from the drive control circuit 14, respectively, and have a predetermined high level. When the signal is input, it is turned on, and when a predetermined low level signal is input, it is turned off.

  Next, the operation of the printer 10 according to the present embodiment will be described.

  When image data is input from an external device (not shown), the controller 12 performs various image processing such as halftone processing on the image data, and sequentially outputs dot data to the drive control circuit 14 at every predetermined recording cycle. To do.

  When the input of dot data is started, the drive control circuit 14 generates a clock signal and outputs the clock signal to the drive voltage generation circuit 16, and performs divided drive processing (to be described later) every time dot data is input, thereby generating dot data. Based on the above, the divided discharge head 20 is divided and driven.

  FIG. 6 shows the flow of divided drive processing executed by the drive control circuit 14.

  In step 100 of FIG. 5, all the column control signals output to each switch element 62 are set to low level, and a high level row control signal A is output to the switch element 60A, and low level row control is performed to the switch element 60B. Signal B is output. As a result, the switch element 60A is turned on, the switch element 60B is turned off, and the common electrodes 50 in the first, third, and fifth rows are grounded and can be energized.

  In the next step 102, the nozzle 40 that discharges droplets from the nozzles 40 in the first, third, and fifth rows is specified based on the input dot data, and is connected to the piezoelectric element 52 corresponding to the specified nozzle 40. A high level column control signal is output to the switch element 62 to which the individual electrode 56 is connected, and a low level column control signal is output to the other switch elements 62. As a result, only the switch element 62 to which the high level column control signal is supplied is turned on, and the drive voltage is applied from the wiring 64 to the piezoelectric element 52 via the individual electrode 56.

  The piezoelectric element 52 to which the driving voltage is applied is deformed according to the driving waveform of the applied driving voltage to generate a volume change in the pressure chamber 46 and generate a vibration wave in the pressure chamber 46 to thereby generate a nozzle. A droplet is discharged from 40.

  That is, in steps 100 to 102 described above, the liquid is discharged from the nozzles 40 in the first, third, and fifth rows (odd-numbered rows) in which the remainder when the number of rows is divided by “2” that is the number of divided driving operations is “1”. Drops are ejected.

  In the next step 104, all the column control signals output to the respective switch elements 62 are set to the low level, the low level row control signal A is output to the switch element 60A, and the high level row control signal is output to the switch element 60B. B is output. As a result, the switch element 60A is turned off, the switch element 60B is turned on, and the common electrodes 50 in the second, fourth, and sixth rows are grounded and can be energized.

  In the next step 106, the nozzle 40 that discharges the droplet is identified from the nozzles 40 in the 2nd, 4th, and 6th rows based on the input dot data, and connected to the piezoelectric element 52 corresponding to the identified nozzle 40. A high level column control signal is output to the switch element 62 to which the individual electrode 56 is connected, and a low level column control signal is output to the other switch elements 62. As a result, only the switch element 62 to which the high-level column control signal is supplied is turned on, the drive voltage is applied to the piezoelectric element 52 from the wiring 64 via the individual electrode 56, and the piezoelectric element 52 to which the drive voltage is applied is The liquid droplets are ejected from the nozzle 40 by being deformed according to the driving waveform of the driving voltage.

  That is, in steps 104 to 106 described above, the liquid is discharged from the nozzles 40 in the second, fourth, and sixth rows (even-numbered rows) in which the remainder when the number of rows is divided by “2” that is the number of divided driving operations is “0”. Drops are ejected.

  In the next step 108, all the row control signals output to each switch element 62 are set to the low level, and the low level row control signal A and the row control signal B are output to the switch element 60A and the switch element 60B. Processing ends.

  In the configuration of the droplet discharge head 20 according to the present embodiment, electrical crosstalk occurs depending on the number of nozzles to be discharged at the same time, and a drive waveform that leads to discharge can be applied to the nozzles 40 that are not desired to be discharged. There is sex. For this reason, as shown in FIG. 10, load control switches 72A and 72B are provided with one end connected to the drive voltage and the other connected to each common electrode 50 of each electrode group via a dummy load 70, respectively. The on / off state of the load control switches 72A and 72B is controlled by the control signals A and B. For example, a capacitor corresponding to a capacitance of half of the maximum load of each group is used as the dummy load 70, and a load control switch corresponding to when the number of nozzles to be discharged simultaneously is less than half of the number of nozzles belonging to the group You may make it control so that 72A, 72B may turn ON. Thus, no matter how the number of nozzles to be ejected changes, if the amplitude of the drive voltage applied to the piezoelectric element 52 of the nozzle 40 to be ejected is 1, the piezoelectric element 52 of the nozzle 40 that does not want to be ejected Only a drive voltage having an amplitude of ½ or less is applied, ejection is not performed, and a printed image is not disturbed.

  Here, FIGS. 7A and 7B are plan views showing examples of configurations of the common electrode 50 and the individual electrodes 56 used in the conventional droplet discharge head.

  In the conventional droplet discharge head, as shown in FIG. 7A, the common electrode 50 is formed on the entire surface of the diaphragm 48 ′, and the piezoelectric elements 52 ′ are attached in a matrix, and FIG. As shown in B), the FPC 54 ′ has individual electrodes 56 ′ formed in parallel in the number of piezoelectric elements 52 ′ along the column direction of the piezoelectric elements 52 ′ provided in a matrix. The electrodes 56 'are connected to the switch elements 62', respectively.

  In such a droplet discharge head using the conventional common electrode 50 ′ and individual electrodes 56 ′, the number of switch elements 62 ′ is the same as the number of piezoelectric elements 52 ′ in order to control the application of drive voltage to each piezoelectric element 52 ′. Necessary.

  On the other hand, according to the present embodiment, as shown in FIG. 4, the number of switch elements 62 is reduced to approximately 1 / n because divided driving is performed n times (here, twice). As a result, the size of the driving device can be reduced.

  Further, as shown in FIG. 7B, in the conventional droplet discharge head, the individual electrodes 56 ′ are formed in parallel by the number of piezoelectric elements in the column direction. For this reason, when the nozzles of the droplet discharge head are densified, the width in the row direction of the piezoelectric elements 52 ′ provided corresponding to the nozzles is narrowed, so the width of the individual electrodes 56 ′ needs to be narrowed. . However, when the width of the individual electrode 56 'is narrowed, it is easily affected by noise and the like.

  On the other hand, according to the present embodiment, as shown in FIG. 3B, n (here, two) pads 58 are electrically connected to one individual electrode 56. As a result, the number of individual electrodes 56 can be reduced to approximately 1 / n. As a result, even when the nozzles 40 of the droplet discharge head 20 are densified, the width of the individual electrodes 56 can be increased compared to the conventional case. As a result, it becomes difficult to be affected by noise or the like.

  As described above, according to the present embodiment, the size of the driving device can be reduced by performing the divided driving, and the number of nozzles is increased because the divided driving is performed in n times. Even in this case, a decrease in recording speed can be suppressed as compared with the case where each piezoelectric element is individually driven in a matrix.

  Further, according to the present embodiment, since the adjacent common electrode 50 is not included in the same electrode group, when the piezoelectric elements 52 are divided and driven in units of electrode groups, the adjacent piezoelectric elements 52 in the column direction. Therefore, structural crosstalk such as vibration and deformation from the adjacent piezoelectric element 52 can be prevented. Further, when the common ink channel 42 communicates with the nozzles 40 adjacent in the row direction, the influence of the vibration wave generated in the adjacent pressure chamber 46 propagated through the ink in the common ink channel 42, that is, Acoustic strokes can be prevented.

  As described above, according to the present embodiment, a plurality of piezoelectric elements are provided in a matrix corresponding to the nozzles, and a liquid is generated by applying a driving voltage having a predetermined driving waveform to each piezoelectric element and deforming it. A change in volume of the accommodated accommodation chamber (here, the pressure chamber 46) is caused to eject droplets from the corresponding nozzle, and each piezoelectric element in the same row for each row in a matrix arrangement of a plurality of piezoelectric elements. Are electrically connected by the first electrode (here, the common electrode 50), and for each column in the matrix arrangement, the other electrode of the continuous piezoelectric elements in the same column is n (n ≧ 2) are electrically connected to each other by the second electrode (in this case, the individual electrode 56), and the number of rows from one end side in the row arrangement direction in the matrix arrangement by the switching means (here, the switch element 60). Since the first electrode corresponding to the rows with the same remainder with respect to n is set to the same electrode group, the presence / absence of ejection is switched for each electrode group, so that the size of the driving device can be reduced while suppressing a decrease in recording speed. .

  Further, according to the present embodiment, in one cycle (one printing cycle) in which droplets of one dot are ejected from each nozzle, the electrode groups that can be ejected are sequentially switched by controlling the switching unit, and A nozzle that ejects droplets is specified based on image data (here, dot data) to be recorded by the droplet ejection head, and the first electrode that is electrically connected to the piezoelectric element corresponding to the nozzle belongs to the nozzle. Since there is further provided a control means (here, the drive control circuit 14) for controlling whether or not the second electrode electrically connected to the piezoelectric element can be energized at the timing when the electrode group can be ejected. Droplets can be ejected from all nozzles that eject droplets identified based on image data during one cycle.

  In the present embodiment, the case where the number of times of division driving is “2” has been described. However, the present invention is not limited to this, and for example, as shown in FIG. The common electrodes 50 in the fourth and fourth rows are grounded in parallel via the switch element 60A, and the common electrodes 50 in the second and fifth rows are grounded in parallel via the switch element 60B. 50 are grounded via the switch element 60C in parallel. As shown in FIG. 8B, the individual electrode 56 is electrically connected to one individual electrode 56 by three consecutive pads 58 in the same row. It may be configured to be connected to each other and be divided and driven in three steps, or may be configured to increase the number of times of divided driving. As a result, the number of switch elements 62 provided for each individual electrode 56 can be further reduced, so that the size of the drive device can be further reduced.

  In this embodiment, the case where the drive waveform generated by the drive voltage generation circuit 16 is one type has been described. However, the present invention is not limited to this, and the drive voltage generation circuit 16 discharges, for example. Drive voltages 1 to 3 of drive waveforms of three types (for example, large droplets, medium droplets, and small droplets) having different amounts of droplets to be generated and output to the column control switch unit 26, respectively. In the unit 26, as shown in FIG. 9, the individual electrodes 56 are connected to the drive voltages 1 to 3 via the switch elements 62, respectively, and the drive control circuit 14 sets the switch elements 62 according to the density of dots to be recorded. The amount of droplets ejected from the nozzle 40 may be changed by selectively applying a driving voltage to be applied to the piezoelectric element 52 under control.

  In this embodiment, the first electrode of the electrode group that is a common electrode is turned on / off with respect to GND, and the second electrode that is an individual electrode is turned on / off with respect to the drive waveform voltage. However, the first electrode of the electrode group that is a common electrode is turned on / off with the drive waveform voltage, and the second electrode that is an individual electrode is turned on / off with a constant voltage such as GND. It may be.

  In the present embodiment, the case has been described in which the number of rows of the piezoelectric elements 52 provided in a matrix is divisible by the number n of times of division driving, but the present invention is not limited to this, and the number of columns and rows The present invention may be applied to the droplet discharge head 20 whose number is not a multiple of n. In this case, a fractional amount of waste is generated, but substantially the same effect as in the present embodiment can be obtained.

  Further, in the present embodiment, a case has been described where the number of rows and columns of the piezoelectric elements 52 provided in a matrix is equal, but the present invention is not limited to this, for example, a trapezoidal shape. Alternatively, the present invention may be applied to the case where the piezoelectric elements 52 are provided in a region such as an extremely parallelogram and the number of the piezoelectric elements 52 in each row and each column is different. In this case as well, fractional waste is generated, but substantially the same effect as in the present embodiment can be obtained.

  In this embodiment, the landing position may be shifted in the droplets ejected by the division driving. In this case, the position of the droplet ejection head 20 is physically shifted to cope with this. Also good.

  For example, even in the case of divided driving divided into two times, it is not always necessary to set each driving timing to ½ of one printing cycle, and the driving timing is set to 1 according to the direction and amount of deviation of the landing position. It is preferable to deviate from / 2. Thereby, the landing position deviation of the droplet can be reduced, and a high-quality image can be obtained.

  The present invention may also be applied to the printer 10 that records an image on a recording sheet while the droplet discharging head 20 is reciprocated in the main scanning direction. As a long head having a width wider than the width, a large number of nozzles 40 are provided along the width direction of the recording paper, and while the recording paper is relatively moved in the sub-scanning direction, You may apply to the printer 10 which records the full width of a recording paper collectively by discharging a droplet from each nozzle 40. FIG. Also in this case, the same effects as in the present embodiment can be obtained.

  Further, in the present embodiment, the case where the individual piezoelectric element 52 is attached to the common electrode 50 and the FPC 54 is bonded thereto is described. However, the present invention is not limited to this. The individual electrodes 56 may be formed by drawing a pattern on the formed piezoelectric element 52 by sputtering or the like.

  Further, in the present embodiment, the case where the common electrode 50 is grounded and the drive voltage is applied to the individual electrode 56 has been described. However, the present invention is not limited to this, and binary recording is possible. A driving voltage may be applied to the common electrode 50 and the individual electrode 56 may be grounded.

  Further, the column direction and the row direction of the piezoelectric elements 52 provided in a matrix form are a matter of definition, and for example, the sheet conveyance direction may be either the row direction or the column direction.

  In addition, the configuration of the printer 10 described in this embodiment (see FIG. 1), the configuration of the droplet discharge head 20 (see FIG. 2), the configuration of the common electrode 50 and the individual electrodes 56 (FIGS. 3 to 5, FIG. 8 to 9) is an example, and it is needless to say that changes can be made as appropriate without departing from the gist of the present invention.

  Further, the divided drive processing (see FIG. 6) described in this embodiment is also an example, and it is needless to say that it can be changed as appropriate without departing from the gist of the present invention.

1 is a configuration diagram of a printer according to an embodiment. FIG. It is sectional drawing of the nozzle which concerns on embodiment. It is a top view which shows the structure of the common electrode on the diaphragm which concerns on embodiment, and the separate electrode formed in FPC. It is a top view which shows the structure which adhere | attached the diaphragm and FPC which concern on embodiment. It is a wiring diagram showing an electrical configuration of a droplet discharge head according to an embodiment. It is a flowchart which shows the flow of the division | segmentation drive process which concerns on embodiment. It is a top view which shows an example of a structure of the common electrode and individual electrode which are used for the conventional droplet discharge head. It is a top view which shows the other structural example of the separate electrode formed in the common electrode and FPC on a diaphragm. It is a top view which shows the other structural example of the separate electrode formed in FPC. It is a wiring diagram which shows another example of the electrical structure of the droplet discharge head which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printer 14 Drive control circuit 20 Droplet discharge head 46 Pressure chamber 50 Common electrode 52 Piezoelectric element 56 Individual electrode 60 Switch element

Claims (4)

Each of the nozzles is provided in a matrix corresponding to the nozzles, and when a drive voltage having a predetermined drive waveform is applied and deformed, a volume change of the storage chamber containing the liquid is generated, and droplets are ejected from the corresponding nozzles. A plurality of piezoelectric elements,
For each row in the matrix arrangement of the plurality of piezoelectric elements, a first electrode in which one electrode of each piezoelectric element in the same row is electrically connected;
For each column in the matrix arrangement, a second electrode in which n (n ≧ 2) other electrodes of the continuous piezoelectric elements in the same column are electrically connected,
Switching means for switching the presence / absence of ejection for each electrode group with the first electrode corresponding to a row having the same remainder for n of the number of rows from one end side in the row arrangement direction in the matrix arrangement as the same electrode group;
A droplet ejection head drive device comprising: In one cycle in which droplets of one dot are ejected from each nozzle, the switching means is controlled to sequentially switch the electrode groups that can be ejected, and based on image data to be recorded by the droplet ejection head. The nozzle that discharges the droplet is specified, and the piezoelectric element is electrically connected to the piezoelectric element at a timing when the electrode group to which the first electrode electrically connected to the piezoelectric element corresponding to the nozzle belongs can be discharged. The droplet discharge head drive device according to claim 1, further comprising: a control unit that controls whether or not energization is performed on the second electrode that is connected electrically. 3. The droplet according to claim 2, wherein the control unit performs control to select and apply the drive voltage to the second electrode according to the amount of droplets ejected from a plurality of drive voltages each having a different drive waveform. Discharge head drive device. Each of the nozzles is provided in a matrix corresponding to the nozzles, and when a drive voltage having a predetermined drive waveform is applied and deformed, a volume change of the storage chamber containing the liquid is generated, and droplets are ejected from the corresponding nozzles. For each row in the matrix array of a plurality of piezoelectric elements to be operated, one electrode of each piezoelectric element in the same row is electrically connected to the first electrode, and each column in the matrix array is continuously in the same column. Electrically connecting the other electrode of the piezoelectric element n (n ≧ 2) to the second electrode,
The first electrode corresponding to the row having the same remainder with respect to n of the number of rows from one end side in the row arrangement direction in the matrix arrangement is used as the same electrode group, and the presence or absence of ejection is switched for each electrode group. Driving method.

Images