JP2010125705A - Liquid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejecting apparatus capable of suppressing a characteristic difference between and among nozzles. <P>SOLUTION: The liquid ejecting apparatus has first and second switchable modes. In the first mode, liquid is ejected from a nozzle in such a manner that an electric field is applied to a piezoelectric element 6 in a polarization direction of a piezoelectric material layer 15 so as to drive the piezoelectric element. In the second mode, liquid is ejected from the nozzle in such a manner that the electric field is applied to the piezoelectric element in a direction opposite to the polarization direction of the piezoelectric material layer so as to drive the piezoelectric element. The control of the ejection is performed by the first mode with respect to a nozzle of which the amount of ink to be ejected is comparatively large or by the second mode with respect to a nozzle of which the amount of ink to be ejected is comparatively small. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus including a piezoelectric element used as a drive source for a liquid ejection head such as an ink jet recording head, and more particularly to a liquid ejection apparatus capable of suppressing a difference in ejection characteristics between nozzles. .

  For example, a liquid ejection apparatus is an apparatus that includes a liquid ejection head capable of ejecting liquid and ejects various liquids from the liquid ejection head. As a typical example of this liquid ejection apparatus, for example, an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejection head is provided, and liquid ink is recorded on recording paper or the like from nozzles of this recording head. An image recording apparatus such as an ink jet printer (hereinafter referred to as a printer) that records an image or the like by ejecting and landing on a medium (landing target) to form dots can be given. In recent years, liquid ejecting apparatuses have been applied not only to this image recording apparatus but also to various manufacturing apparatuses such as a manufacturing apparatus for a color filter such as a liquid crystal display.

  Some recording heads, which are a type of the liquid ejection head, include a piezoelectric element as a drive source for ejecting ink. This piezoelectric element is configured by laminating a piezoelectric material and an electrode material, and is stretched or deformed by applying a voltage between the drive electrode and the common electrode. The piezoelectric element can be deformed by being provided on a diaphragm that divides a part of a pressure generation chamber communicating with the nozzle and applying a drive signal for deformation driving. Due to the deformation of the vibration plate, the volume of the pressure generating chamber changes to cause a pressure fluctuation in the ink in the pressure generating chamber. By controlling this pressure fluctuation, liquid ink can be ejected (ejected) from the nozzle.

  However, in a printer equipped with the recording head, the amount (weight) of ink ejected from the nozzle differs from head to head even when the same voltage is applied to the piezoelectric element due to individual differences between the heads. For this reason, in a liquid discharge apparatus including a plurality of print heads (head units), ranks are made according to discharge characteristics such as the amount of ink discharged from nozzles, and print heads are combined based on this rank. A drive voltage is set in accordance with (see, for example, Patent Document 1).

JP 2006-082046 A

By the way, in the recording head described above, due to parts accuracy, assembly accuracy, or structural problems, some nozzles in a nozzle row (nozzle group) in which a plurality of nozzles are arranged are ejected more than other nozzles. The amount of ink may be significantly reduced. In this case, there is a problem that the image quality is deteriorated due to the decrease in the amount of ejected ink. In such a recording head in which a difference in ejection characteristics locally occurs, it cannot be solved even by a combination of recording heads based on the rank.
Even in the case of combining the print heads based on the ranks, if the number of ranks is increased, it is necessary to wait until the print heads of the same rank are prepared at the time of manufacture, and the manufacturing efficiency is lowered. On the other hand, if the number of ranks is reduced in order to improve the production efficiency, there is a problem in that the variation in ejection characteristics between nozzles of different recording heads in the same liquid ejection apparatus increases, leading to a reduction in image quality.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejection apparatus capable of suppressing a difference in ejection characteristics between nozzles.

The present invention has been proposed in order to achieve the above object, and has a plurality of nozzles for discharging a liquid, and supplies a drive signal to the piezoelectric element to drive the piezoelectric element so as to drive the ink in the pressure generating chamber. A liquid ejection device including a liquid ejection head that causes pressure fluctuations and ejects liquid from the nozzles by the pressure fluctuations,
A first mode in which an electric field is applied to the piezoelectric element in the polarization direction of the piezoelectric body to drive the piezoelectric element to discharge liquid from the nozzle, and a direction opposite to the polarization direction of the piezoelectric body with respect to the piezoelectric element A mode switching control unit capable of switching between a second mode in which the piezoelectric element is driven by applying an electric field to discharge the liquid from the nozzle;
The plurality of nozzles includes a first nozzle and a second nozzle that discharges less liquid than the first nozzle when the same drive signal as the first nozzle is supplied to the piezoelectric element,
The mode switching control unit performs discharge control in the first mode for the first nozzle and in the second mode for the second nozzle, respectively.
Regarding the direction of the electric field with respect to the polarization direction, in the first mode, the electric field does not always have to be in the same direction as the polarization direction during the driving period of the piezoelectric element, and there is a period in which the electric field is opposite to the polarization direction. Also good. In short, it is only necessary that the electric field is in the same direction as the polarization direction in most of the period of one driving of the piezoelectric element. Similarly, in the second mode, the electric field does not always have to be opposite to the polarization direction during the driving period of the piezoelectric element, and there may be a period in which the electric field is forward with respect to the polarization direction. In short, it is sufficient that the electric field is in the direction opposite to the polarization direction in most of the period of one driving of the piezoelectric element.

  According to the above configuration, an electric field in a direction opposite to the polarization direction of the piezoelectric body is applied as compared with the first mode in which a forward electric field is applied to the polarization direction of the piezoelectric body to drive the piezoelectric element. In the second mode in which the piezoelectric element is driven, the displacement amount of the piezoelectric element becomes larger. Therefore, by performing ejection control in the second mode for a nozzle with a relatively small amount of ejected liquid. The amount of liquid discharged from the nozzle can be increased. Thereby, the difference in the ejection characteristics between the nozzles can be suppressed, and the influence on the image quality such as the image of the landing target such as the recording paper can be reduced.

In addition, the present invention has a plurality of nozzle groups configured by arranging a plurality of nozzles for discharging the previous liquid, and supplies the drive signal to the piezoelectric element to drive the piezoelectric element, thereby causing ink in the pressure generating chamber to A liquid ejection device including a liquid ejection head that causes pressure fluctuations and ejects liquid from the nozzles by the pressure fluctuations,
A first mode in which an electric field is applied to the piezoelectric element in the polarization direction of the piezoelectric body to drive the piezoelectric element to discharge liquid from the nozzle, and a direction opposite to the polarization direction of the piezoelectric body with respect to the piezoelectric element A mode switching control unit capable of switching between a second mode in which the piezoelectric element is driven by applying an electric field to discharge the liquid from the nozzle;
The plurality of nozzle groups includes a first nozzle group, a second nozzle group that discharges less liquid than the first nozzle group when the same drive signal as the first nozzle group is supplied to the piezoelectric element, and With
The mode switching control unit performs discharge control in the first mode for the first nozzle group and in the second mode for the second nozzle group, respectively. To do.

  According to this configuration, the ejection control between the nozzle groups is performed by performing the ejection control in the second mode for the nozzle group in which the amount of liquid ejected in the liquid ejection head having the plurality of nozzle groups is relatively small. Differences in characteristics can be suppressed.

In the above configuration, the piezoelectric element is configured by laminating a first electrode, a piezoelectric layer, and a second electrode in this order, and the polarization direction of the piezoelectric layer is from the first electrode side. A direction toward the second electrode,
A drive voltage supply source for generating a drive voltage, a bias voltage supply source for generating a constant bias voltage, and a path from the drive voltage supply source and the bias voltage supply source to the first electrode and the second electrode And a path switching means arranged in
In the first mode, the path switching unit supplies a driving voltage from the driving voltage supply source to the first electrode and supplies a bias voltage from the bias voltage supply source to the second electrode. In the second mode, the driving voltage from the driving voltage supply source is supplied to the second electrode and the bias voltage from the bias voltage supply source is supplied to the first electrode. A configuration for switching can be employed.

  In each of the above configurations, the bias voltage supply source may employ a configuration in which the bias voltage is changed according to the amount of liquid to be ejected.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following description, an ink jet recording head (hereinafter simply referred to as a recording head) mounted on an ink jet printer (a kind of the liquid ejecting apparatus of the present invention) is taken as an example of the liquid ejecting head of the present invention. .

  FIG. 1 is an exploded perspective view showing the configuration of the recording head 1 of the present embodiment. 2A is a plan view of the recording head 1, FIG. 2B is a cross-sectional view taken along the line AA 'in FIG. 2A, and FIG. 2C is the width direction of the pressure generating chamber 9 (short piezoelectric element). It is principal part sectional drawing of (direction). The recording head 1 in this embodiment is configured by laminating a flow path forming substrate 2, a nozzle plate 3, an elastic film 4, an insulator film 5, a piezoelectric element 6, a protective substrate 7, and the like.

  In this embodiment, the flow path forming substrate 2 is composed of a silicon single crystal substrate having a plane orientation (110), and a plurality of pressure generating chambers 9 are arranged in parallel in the width direction of the flow path forming substrate 2. In addition, a communication portion 10 is formed in a region in the longitudinal direction outside the pressure generation chamber 9 of the flow path forming substrate 2, and the communication portion 10 and each pressure generation chamber 9 are provided for each pressure generation chamber 9. Communication is made via a path 11. The communication unit 10 communicates with a reservoir unit 20 of the protective substrate 7 to be described later and constitutes a part of a reservoir 21 serving as a common ink chamber for the pressure generation chambers 9. The ink supply path 11 is formed with a narrower width than the pressure generation chamber 9, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 9 from the communication portion 10.

  On the opening surface side of the flow path forming substrate 2, a nozzle plate 3 having a nozzle 12 communicating with an end portion of each pressure generating chamber 9 on the side opposite to the ink supply path 11 is provided with an adhesive, a heat welding film, or the like. It is fixed through. As shown in FIG. 3, the nozzle plate 3 includes a plurality of nozzles 12 for ejecting ink to form a nozzle row 13 (a kind of nozzle group), and the nozzle row 13 is orthogonal to the nozzle row setting direction. A plurality of (in this embodiment, two rows) are formed in the direction in which they are to be performed. One nozzle row 13 is composed of, for example, 360 nozzles opened at a pitch of 360 dpi. In this embodiment, as shown in FIG. 3, one nozzle row 13 is divided into three blocks A to C.

On the other hand, an elastic film 4 made of, for example, silicon dioxide (SiO ₂ ) is formed on the side opposite to the opening surface of the flow path forming substrate 2, and an insulating film made of zirconium oxide (ZrO ₂ ) is formed on the elastic film 4. A body film 5 is formed. Further, on this insulator film 5, a lower electrode film 14 (a kind of second electrode in the present invention), a piezoelectric layer 15, and an upper electrode film 16 (a kind of first electrode in the present invention) Are formed, and these constitute a piezoelectric element 6 (thin film piezoelectric element) in a laminated state. Here, the piezoelectric element 6 refers to a portion including the lower electrode film 14, the piezoelectric layer 15, and the upper electrode film 16. In general, one electrode of the piezoelectric element 6 is used as a common electrode (ground electrode), and the other electrode (positive electrode or individual electrode) and the piezoelectric layer 15 are patterned for each pressure generating chamber 9. A portion that is composed of any one of the patterned electrodes and the piezoelectric layer 15 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the piezoelectric layer 15 is polarized so that the polarization direction is from the upper electrode film 16 toward the lower electrode film 14 (polarization direction Pd in FIG. 6). In addition, the lower electrode film 14 is a common electrode of the piezoelectric element 6 and the upper electrode film 16 is an individual electrode of the piezoelectric element 6. However, these may be reversed as a whole depending on the convenience of the drive circuit and wiring. it can. In either case, a piezoelectric active part is formed for each pressure generating chamber 9. In addition, a lead electrode 17 made of, for example, gold (Au) or the like is connected to the upper electrode film 16 of each piezoelectric element 6.

  On the surface of the flow path forming substrate 2 on the piezoelectric element 6 side, a protective substrate 7 having a piezoelectric element holding portion 19 that is a space that does not hinder the displacement is bonded to a region facing the piezoelectric element 6. ing. Since the piezoelectric element 6 is accommodated in the piezoelectric element holding part 19, it is protected in a state hardly affected by the external environment. Further, the protective substrate 7 is provided with a reservoir portion 20 in a region corresponding to the communication portion 10 of the flow path forming substrate 2. The reservoir portion 20 is provided along the direction in which the pressure generation chambers 9 are arranged so as to penetrate the protective substrate 7 in the thickness direction, and is communicated with the communication portion 10 of the flow path forming substrate 2 as described above. A reservoir 21 serving as an ink chamber common to the pressure generation chambers 9 is configured.

  A through hole 22 that penetrates the protective substrate 7 in the thickness direction is provided in a region between the piezoelectric element holding portion 19 and the reservoir portion 20 of the protective substrate 7, and the lower electrode film 14 is provided in the through hole 22. And the tip of the lead electrode 17 are exposed. A bias voltage from a bias voltage supply source 29 on the printer body side is applied to the lead electrode 17, and a drive voltage from a drive voltage supply source 30 on the printer body side is applied to the lower electrode film 14. (Both will be described later with reference to FIG. 5). A compliance substrate 25 including a sealing film 23 and a fixing plate 24 is bonded on the protective substrate 7. The sealing film 23 is made of a material having low rigidity and flexibility (for example, polyphenylene sulfide film), and one surface of the reservoir portion 20 is sealed by the sealing film 23. The fixing plate 24 is made of a hard material such as metal (for example, stainless steel). Since the area of the fixing plate 24 facing the reservoir 21 is an opening 26 that is completely removed in the thickness direction, one surface of the reservoir 21 is sealed only with a flexible sealing film 23. Has been.

  In the recording head 1 configured as described above, after the ink is taken in from the ink supply means and filled from the reservoir 21 to the nozzle 12 with the ink, the pressure generating chamber 9 is supplied by supplying the drive voltage and the bias voltage from the printer body side. A discharge pulse P (see FIG. 5) is applied between the lower electrode film 14 and the upper electrode film 16 corresponding to each of the elastic film 4, the insulator film 5, the lower electrode film 14, and the piezoelectric layer 15. By deforming, the pressure in the pressure generating chamber 9 is increased, and by controlling the pressure fluctuation, ink is ejected (ejected) from the nozzle 12.

  FIG. 4 is a block diagram illustrating the electrical configuration of the printer. The printer controller 36 includes a CPU 39 that controls each unit in accordance with a control program stored in the ROM 37, a ROM 37 that stores a control program for various data processing, a RAM 38 that stores various data, and the piezoelectric of the recording head 1. A drive signal generation circuit 40 that generates a drive signal for driving the element 6, a nonvolatile storage element 41 that stores nozzle characteristic information described later, and an interface (I / F) unit 42 that outputs data to the recording head 1. And are connected to each other.

  The drive signal generation circuit 40 includes a bias voltage supply source 29 and a drive voltage supply source 30 (see FIG. 6). The drive voltage supply source 30 generates, for example, the drive voltage VP illustrated in FIG. The drive voltage VP is a pulse voltage that changes up and down with respect to the intermediate potential (reference potential) Vb. On the other hand, the bias voltage supply source (DC voltage supply source) 29 generates a constant bias voltage (DC voltage) VC. This bias voltage is set lower than at least the intermediate potential Vb of the drive voltage generated by the drive voltage supply source 30. The drive voltage VP generated by the drive voltage supply source 30 is applied to the upper electrode film 16, and the bias voltage VC generated by the bias voltage supply source 29 is applied to the lower electrode film 14. The ejection pulse P shown in FIG. 5 is applied. The discharge pulse P holds the potential lowering element p1 for lowering the potential with a relatively gentle gradient from the reference potential Vm corresponding to the reference volume of the pressure generating chamber 9 to the lowest potential VL, and the lowest potential VL for a predetermined time. A first potential hold element p2, a potential increase element p3 that raises the potential steeply from the lowest potential VL to the highest potential VH, a second potential hold element p4 that holds the highest potential VH for a predetermined time, and a reference from the highest potential VH And a return element p5 that lowers the potential to the potential Vm.

  When the potential lowering element p1 is supplied to the piezoelectric element 6, the piezoelectric element 6 bends in the opposite direction to the pressure generating chamber 9 and deforms the elastic film 4, whereby the pressure generating chamber 9 expands relatively slowly and generates pressure. Chamber 9 is depressurized. Subsequently, the expanded state of the pressure generating chamber 9 is maintained by supplying the first hold element p2. Thereafter, the potential increasing element p3 is supplied, the piezoelectric element 6 is bent toward the pressure generating chamber 9, and the pressure generating chamber 9 contracts in a very short time, whereby the ink in the pressure generating chamber 9 is rapidly pressurized. Ink is ejected from the nozzles 12. Thereafter, the return element p5 is supplied after the second hold element p4, the pressure generating chamber 9 is gently expanded, and the meniscus vibration in the nozzle 12 after the ink is discharged is converged.

  By the way, the printer according to the present invention drives the piezoelectric element 6 by applying an electric field to the piezoelectric element 6 in the same direction as the polarization direction Pd of the piezoelectric layer 15 according to the ejection characteristics of each nozzle 12. The first mode and the second mode for driving the piezoelectric element 6 by applying an electric field to the piezoelectric element 6 in the direction opposite to the polarization direction Pd of the piezoelectric layer 15 are switched. Hereinafter, this point will be described.

  6A and 6B are simplified circuit diagrams showing a signal supply path from the drive signal generation circuit 40 to the piezoelectric element 6. FIG. 6A shows a switching state in the first mode, and FIG. 6B shows a switching state in the second mode. Each is shown. As shown in the figure, the printer according to this embodiment includes a switch as a path switching unit that switches a path from the drive voltage supply source 30 and the bias voltage supply source 29 to the upper electrode film 16 and the lower electrode film 14 of the piezoelectric element 6. A circuit 31 is provided. In the present embodiment, these paths and the switch circuit 31 are provided independently for each block (A to C) of each nozzle row 13 described above. The switching of the switch circuit 31 is controlled by a CPU 39 functioning as a mode switching control unit.

  The non-volatile storage element 41 of the printer according to the present embodiment stores the average ejection ink amount for each of the blocks A to C of each nozzle row 13. This average discharge ink amount is, for example, for each nozzle row with respect to the ink weight (weight per drop of discharged ink or the total weight when discharged a predetermined number of times) when ink is discharged from the nozzle 12 in the inspection process at the time of manufacture. The average is calculated for each of 13 blocks A to C. The CPU 39 functions as a mode switching control unit in the present invention, and compares the average ejection ink amount for each of the blocks A to C of each nozzle row 13. For the comparison of the amount of ejected ink, a threshold value may be determined in advance and compared with this threshold value. Then, the CPU 39 sets the mode to the first mode in the block in which the average amount of ejected ink is relatively large (or larger than the threshold), and as shown in FIG. From which the drive voltage VP is supplied to the upper electrode film 16 as an individual electrode (positive electrode) and the bias voltage VC from the bias voltage supply source 29 is supplied to the lower electrode film 14 as a common electrode (ground electrode) The switch circuit 31 is switched so that In the ejection control in the first mode, as described above with reference to FIG. 5, the drive voltage VP from the drive voltage supply source 30 is applied to the upper electrode film 16 and the bias voltage from the bias voltage supply source 29 is applied. By applying VC to the lower electrode film 14, the ejection pulse P shown in FIG. 5 is applied to the piezoelectric element 6. The ejection pulse P becomes a positive voltage as a whole. Therefore, in this first mode, an electric field is applied to the piezoelectric element 6 in the polarization direction Pd of the piezoelectric film 15.

  On the other hand, in a block where the average amount of ejected ink is relatively small (or smaller than the threshold value), the CPU 39 as the mode switching control unit sets the mode to the second mode, as shown in FIG. The switch circuit 31 is arranged so that the drive voltage VP from the drive voltage supply source 30 is supplied to the lower electrode film 14 and the bias voltage VC from the bias voltage supply source 29 is supplied to the upper electrode film 16. Switch. In this second mode, the ejection pulse P applied to the piezoelectric element 6 is inverted in polarity and becomes a negative voltage as a whole. In other words, in the second mode, an electric field is applied to the piezoelectric element 6 in a direction opposite to the polarization direction of the piezoelectric film 15.

  Here, FIG. 7 is a graph showing the characteristics of the displacement amount (deflection amount) with respect to the applied voltage of the piezoelectric element 6. As shown in the figure, when the applied voltage is changed, the amount of displacement of the piezoelectric element 6 changes in accordance with this to draw a locus indicated by an arrow in the figure. And when the voltage of the same absolute value is applied, compared with the 1st mode which applies the electric field of the forward direction with respect to the polarization direction of the piezoelectric material film 15, in which the applied voltage is changed on the plus side. In the configuration in which the applied voltage is changed on the minus side, that is, in the second mode in which the electric field in the direction opposite to the polarization direction of the piezoelectric film 15 is applied, the displacement amount of the piezoelectric element 6 becomes larger. Specifically, in the second mode, the displacement amount of the piezoelectric element 6 is increased by about several tens to several tens of% compared to the case of the first mode.

  For this reason, in the first mode, for the nozzle 12 having a relatively large amount of ejected ink (corresponding to the first nozzle in the present invention), the nozzle 12 having a relatively small amount of ejected ink (this (Corresponding to the second nozzle in the invention), by controlling the discharge in the second mode, the difference in the discharge characteristics between the nozzles can be suppressed. For example, as shown in FIG. 8, in a certain nozzle row 13, the amount (average value) of ink ejected from the nozzles 12 belonging to the block B among the blocks A to C belongs to the other blocks A and C. When the amount of ink ejected from the nozzles 12 (average value) is relatively lower (or lower than a predetermined threshold), the nozzles 12 belonging to the blocks A and C are set to the first mode. Discharge control is performed, and the nozzles 12 belonging to the block B are set to the second mode to perform discharge control. In the second mode, as described above, by applying an electric field in a direction opposite to the polarization direction of the piezoelectric film 15 to drive the piezoelectric element 6, the displacement amount of the piezoelectric element 6 compared to the first mode is achieved. Can be improved. Thereby, as shown by a broken line in FIG. 8, the amount of ink ejected from the nozzles 12 belonging to the block B can be increased as a whole. For this reason, the difference in the ejection characteristics between the nozzles can be suppressed as much as possible, and as a result, the influence on the image quality such as the image of the landing target such as the recording paper can be reduced.

Here, in addition to the mode switching control, by changing the bias voltage VC generated by the bias voltage supply source 29, the ejection characteristics between the nozzles can be made closer.
FIG. 9 is a graph showing the amount of displacement of the piezoelectric element 6 when the bias voltage VC is changed. As shown in the figure, it is understood that the displacement amount of the piezoelectric element 6 is changed by changing the bias voltage VC. In this example, the maximum amount of displacement is obtained by setting the bias voltage VC to −2V to −1V, and the amount of displacement tends to decrease by changing the bias voltage VC to the plus side or the minus side. By utilizing this characteristic and setting the bias voltage VC according to the amount of ejected ink, the difference in the ejected ink amount of each nozzle 12 can be further reduced.

  Similarly, by changing the drive voltage (potential difference from the highest potential to the lowest potential) of the drive voltage VP generated by the drive voltage supply source 30, the displacement amount of the piezoelectric element 6 is adjusted, and the ejection characteristics between the nozzles. Can be made closer. In this case, as the drive voltage of the drive voltage VP is increased, the amount of displacement of the piezoelectric element 6 is increased. Therefore, the amount of ink ejected from the nozzle 12 is increased, and conversely, the drive voltage of the drive voltage VP is increased. The lower the value is, the smaller the displacement amount of the piezoelectric element 6 is, and accordingly, the amount of ink ejected from the nozzle 12 is also reduced.

  By the way, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the description of the scope of claims.

For example, the shape of the drive voltage VP is not limited to that illustrated in the above embodiment, and an arbitrary waveform can be adopted.
Moreover, in the said embodiment, although the piezoelectric element 6 which is a thin film piezoelectric element was illustrated, it is not restricted to this, It can apply also to the piezoelectric element of another structure.

  In the above embodiment, the configuration in which one nozzle row 13 is divided into a plurality of blocks and the mode is set for each block is exemplified, but the present invention is not limited to this. For example, it is possible to employ a configuration in which a drive signal supply path and a switch circuit 31 are provided independently for each nozzle, and a mode is set for each nozzle. According to this configuration, since the discharge amount can be adjusted in units of nozzles, it is possible to more reliably align the discharge characteristics between the nozzles.

  Further, in the configuration in which the recording head 1 includes a plurality of nozzle rows 13 (nozzle groups), a configuration in which a mode is set for each nozzle row can be employed. That is, in this configuration, the CPU 39 as the mode switching control unit performs the first mode for the nozzle row 13 (corresponding to the first nozzle group) with a relatively large amount (average value) of ejected ink. For the nozzle row 13 (corresponding to the second nozzle group) with a relatively small amount (average value) of ejected ink, ejection control is performed in the second mode. According to this configuration, when there is a difference in ejection characteristics between the nozzle rows, it is possible to suppress the difference in ejection characteristics between the nozzle rows by appropriately setting the mode.

  The present invention is not limited to the exemplified printer, but various ink jet recording apparatuses such as plotters, facsimile apparatuses, and copiers, and liquid ejection apparatuses other than the recording apparatus, such as display manufacturing apparatuses, electrode manufacturing apparatuses, and chip manufactures. It can also be applied to devices and the like.

FIG. 3 is an exploded perspective view of a recording head. 2A and 2B are a plan view and a sectional view of a recording head. It is a top view of a nozzle plate. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. It is a wave form diagram, such as a drive voltage applied to a piezoelectric element. It is a simple circuit diagram which shows the signal supply path | route from a drive signal generation circuit to a piezoelectric element. It is a graph which shows the characteristic of the displacement amount (deflection amount) with respect to the applied voltage of a piezoelectric element. It is a graph which shows the discharge ink amount of all the nozzles. It is a graph which shows the displacement amount of a piezoelectric element when a bias voltage is changed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Recording head, 6 ... Piezoelectric element, 12 ... Nozzle, 13 ... Nozzle row, 14 ... Lower electrode film, 15 ... Piezoelectric film, 29 ... Bias voltage supply source, 30 ... Drive voltage supply source, 31 ... Switch circuit, 39 ... CPU, 40 ... drive signal generation circuit

Claims (4)

A liquid that has a plurality of nozzles that discharge liquid, supplies a drive signal to the piezoelectric element, and drives the piezoelectric element to cause pressure fluctuation in the ink in the pressure generating chamber, and the liquid that discharges liquid from the nozzle by the pressure fluctuation A liquid discharge apparatus including a discharge head,
A first mode in which an electric field is applied to the piezoelectric element in the polarization direction of the piezoelectric body to drive the piezoelectric element to discharge liquid from the nozzle, and a direction opposite to the polarization direction of the piezoelectric body with respect to the piezoelectric element A mode switching control unit capable of switching between a second mode in which the piezoelectric element is driven by applying an electric field to discharge the liquid from the nozzle;
The plurality of nozzles includes a first nozzle and a second nozzle that discharges less liquid than the first nozzle when the same drive signal as the first nozzle is supplied to the piezoelectric element,
The mode switching control unit performs discharge control in the first mode for the first nozzle and in the second mode for the second nozzle, respectively. Discharge device. A plurality of nozzle groups configured by arranging a plurality of nozzles for discharging liquid, supplying a driving signal to the piezoelectric element to drive the piezoelectric element, thereby causing pressure fluctuation in the ink in the pressure generating chamber; A liquid discharge apparatus including a liquid discharge head for discharging liquid from a nozzle by this pressure fluctuation,
A first mode in which an electric field is applied to the piezoelectric element in the polarization direction of the piezoelectric body to drive the piezoelectric element to discharge liquid from the nozzle, and a direction opposite to the polarization direction of the piezoelectric body with respect to the piezoelectric element A mode switching control unit capable of switching between a second mode in which the piezoelectric element is driven by applying an electric field to discharge the liquid from the nozzle;
The plurality of nozzle groups includes a first nozzle group, a second nozzle group that discharges less liquid than the first nozzle group when the same drive signal as the first nozzle group is supplied to the piezoelectric element, and With
The mode switching control unit performs discharge control in the first mode for the first nozzle group and in the second mode for the second nozzle group, respectively. Liquid ejecting device. The piezoelectric element is configured by laminating a first electrode, a piezoelectric layer, and a second electrode in this order, and the polarization direction of the piezoelectric layer is changed from the first electrode side to the second electrode side. The direction towards
A drive voltage supply source for generating a drive voltage, a bias voltage supply source for generating a constant bias voltage, and a path from the drive voltage supply source and the bias voltage supply source to the first electrode and the second electrode And a path switching means arranged in
In the first mode, the path switching unit supplies a driving voltage from the driving voltage supply source to the first electrode and supplies a bias voltage from the bias voltage supply source to the second electrode. In the second mode, the driving voltage from the driving voltage supply source is supplied to the second electrode and the bias voltage from the bias voltage supply source is supplied to the first electrode. The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is switched. The liquid discharge apparatus according to claim 3, wherein the bias voltage supply source changes the bias voltage according to an amount of liquid to be discharged.

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