JP4650005B2 - Droplet discharge device - Google Patents

Description

  The present invention relates to a droplet discharge device, and more particularly to a droplet discharge device that discharges droplets from each of a plurality of discharge means.

  Conventionally, a pressure generating chamber filled with ink is volume-changed (expanded / contracted) using an actuator such as a piezoelectric element, and the tip of a nozzle formed in communication with the pressure generating chamber by the internal pressure change 2. Description of the Related Art An ink jet recording apparatus (so-called ink jet printer) having an ink jet recording head that discharges ink droplets from an ink droplet is known.

  In recent years, inkjet recording apparatuses have a tendency to increase printing speed. For this reason, an inkjet recording head that can form an image in a wider area in a shorter time is used by elongating the inkjet recording head, increasing the number of nozzles per inkjet recording head, and arranging them in a matrix. It is getting to be.

  When the ink jet recording head is made longer than the recording paper width in this way, the number of ejectors composed of the pressure generating chambers, nozzles and the like becomes tens of thousands, which is an enormous number. If the characteristics of the ejector vary, the ejection amount and ejection speed of ink droplets vary, which affects the image quality.

  In addition, when forming an image by a single scan with an inkjet recording head that has a large number of piezoelectric elements and is longer than the recording paper width, a piezoelectric element is used to form a multi-tone image. Variations in performance, etc., will greatly affect image quality.

  On the other hand, in order to stabilize the image quality of an image formed by an inkjet recording head that has a large number of piezoelectric elements and is longer than the recording paper width, it is required to make the droplet diameter uniform for each gradation.

  In this case, it is conceivable to adjust the droplet diameter of the ink droplets by correcting the image data. However, the amount of calculation for that is enormous, and as a result, the speeding up of image formation is hindered.

  Therefore, conventionally, an apparatus for changing the driving condition of the piezoelectric element has been proposed (see Patent Documents 1 and 2). That is, in the apparatus described in Patent Document 1, in order to make the droplet diameter uniform, the applied voltage is changed by changing the applied waveform of the voltage applied to the piezoelectric element. However, in order to change the applied waveform of the voltage applied to the piezoelectric element, it is necessary to individually control the voltage for each of a plurality of power supplies. When a large number of piezoelectric elements are provided, a considerable number of power supplies are required. As a result, the apparatus becomes larger.

Moreover, in the apparatus described in Patent Document 2, the voltage application time is changed in order to change the voltage application waveform applied to the piezoelectric element. However, although the input image signal is controlled by the correction data, a considerable amount of correction data is required. As a result, an enormous number of control lines are required, and the apparatus is enlarged and the control is complicated. .
Japanese Patent Laid-Open No. 03-051138 JP 2003-291325 A

  The present invention has been made in view of the above-described facts, and an object of the present invention is to provide a droplet discharge device capable of forming a stable image without causing an increase in size of the device.

In order to achieve the above object, the droplet discharge device of the invention described in claim 1 is provided for a plurality of discharge means for discharging droplets and each block obtained by dividing the plurality of discharge means into a plurality of blocks, A plurality of drive circuits that are driven by applying a drive voltage to each of the plurality of ejection units in each block so that droplets are ejected from each ejection unit upon application of a voltage, and a voltage is applied to the plurality of drive circuits In addition, the plurality of drive circuits are configured so that variations in the discharge amount of the droplets of the plurality of ejection units in each of the plurality of blocks are reduced as a whole for the plurality of blocks. and control means for controlling said applying means, and the discharge amount of variation in the information of a droplet of the plurality of discharge means in each block obtained in advance, from the discharge means by changing the waveform of the driving voltage Storage means for storing a plurality of different control data for changing the droplet amount of the discharged droplets, and the control means includes the information stored in the storage means and the plurality of the control data. Based on the control data, control data for changing the waveform of the drive voltage applied to each of the plurality of ejection units in each block to reduce the variation in the droplet ejection amount of the plurality of ejection units in each block is provided. Based on the determined control data, each drive circuit is controlled and the voltage applied to each drive circuit is changed so that the waveform of the drive voltage applied to each of the plurality of ejection units of each block changes. The application unit is controlled so that an average variation in droplet discharge amounts of a plurality of discharge units among a plurality of blocks is reduced to a predetermined droplet discharge target amount. When That.

According to a second aspect of the present invention, in the first aspect of the present invention, the control unit obtains the control data for each of a plurality of stages of relative variations in droplet discharge amounts of the plurality of discharge units in the block. The control data for reducing the actual variation is determined based on an actual variation of the droplet ejection amount of each of the plurality of ejection units in each block and a plurality of stages of the variation. And

According to a third aspect of the present invention, in the first or second aspect of the present invention, a length in a predetermined direction of a region in which droplets are ejected by the plurality of ejection units is determined by ejecting droplets. It is more than the length of the object which forms .

  As described above, according to the present invention, it is possible to prevent an increase in the size of the droplet discharge device and to form a stable image.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a main part of an ink jet recording apparatus 10 as a droplet discharge device according to the present embodiment. Here, a configuration of an ink jet recording head peripheral portion is mainly illustrated except for a recording paper transport system. ing.

  As shown in the figure, an inkjet recording apparatus 10 according to the present embodiment includes a controller 12 as a control unit that controls the operation of the entire inkjet recording apparatus 10, and an inkjet that ejects ink droplets based on supplied print data. And a recording head 14. In addition, the inkjet recording head 14 includes a plurality of ejector groups configured by two-dimensionally arranging a plurality of ejectors 32 that eject ink droplets by deformation of piezoelectric elements (piezo elements) 30 serving as ejection units provided individually. 34 and a drive IC (Integrated Circuit) 16 as a drive circuit provided corresponding to each of the ejector groups 34.

  The ink jet recording head 14 according to the present embodiment is a long one having a width substantially equal to the width of the recording paper. That is, the inkjet recording apparatus 10 is configured as a so-called FWA (Full Width Array) type inkjet recording apparatus that performs recording while transporting only the recording paper while the inkjet recording head 14 is fixed.

  The ejector 32 according to the present embodiment includes a pressure generation chamber filled with ink, an ink discharge port that communicates with the pressure generation chamber and can discharge ink, and part of the wall surface of the pressure generation chamber. A vibration plate configured to expand or contract the pressure generating chamber by vibrating, and a piezoelectric element 30 that vibrates the vibration plate by being deformed by a voltage applied according to image data indicating an image to be recorded. And an actuator provided.

  All the driving ICs 16 provided in the ink jet recording head 14 are connected to the controller 12. The operation of the driving ICs 16 is controlled by a clock signal, print data, and a latch signal, and a waveform signal A that is a pair of signals. The waveform signal B and the waveform signal C are used by the controller 12.

  FIG. 2 is a plan view showing a schematic configuration of the ink jet recording head 14 according to the present embodiment.

  As shown in the figure, the ink jet recording head 14 according to the present embodiment includes each of ejector groups (blocks) 34A1, 34B1, 34A2, 34B2,... Configured by two-dimensionally arranging a plurality of ejectors 32. As a unit structure, a plurality of unit structures are part of an end portion of an ejector group arranged in a unit structure adjacent to a predetermined direction (longitudinal direction (long direction) of the inkjet recording head 14). Are arranged so as to overlap each other.

  In each ejector group 34A1, 34B1, 34A2, 34B2,..., Drive ICs 16A1, 16B1, 16A2, 16B2,... Are individually provided on a one-to-one basis. Are electrically connected by a connection line 18. In the following description, the ejector groups 34A1, 34B1, 34A2, 34B2,... May be abbreviated as “ejector group 34” unless a specific one is desired. In the following description, the drive ICs 16A1, 16B1, 16A2, 16B2,... May be abbreviated as “drive IC 16” unless a specific one is desired. A voltage is applied to each drive IC 16 from a variable power supply described later.

  In the ejector group 34 according to the present embodiment, the shape of the arrangement region is a trapezoidal shape in which the angles of two oblique sides connecting the upper base and the lower base are different from each other. In the ink jet recording head 14 according to the present embodiment, the pair of ejector groups 34 are arranged such that the upper bases of the ejector groups 34 face each other toward the longitudinal center line of the ink jet recording head 14. The drive ICs 16 corresponding to the respective components are also integrally arranged, so that the head unit 15 is configured as a single component. The ink jet recording head 14 is configured with a plurality of head units 15 arranged in the longitudinal direction.

  On the other hand, FIG. 3 shows the configuration of the drive IC 16 according to the present embodiment.

  As shown in the figure, the drive IC 16 according to the present embodiment includes a shift register 42, a latch circuit 44, a selector 46, a level shifter 48, and a drive waveform generation circuit 50.

  The clock signal and print data output from the controller 12 are input to the shift register 42, and the latch signal is input to the latch circuit 44.

  The print data selects one (a pair of signals) of the waveform signal A, the waveform signal B, and the waveform signal C. The waveform signal A selection signal 42A, the waveform signal B selection signal 42B, and the waveform This is serial data composed of the signal C selection signal 42C. The waveform signal A selection signal 42A, the waveform signal B selection signal 42B, and the waveform signal C selection signal 42C are signals indicating 1-bit data that is “0” or “1”, respectively. The waveform signal A selection signal 42A is “1” when the waveform signal A is selected, and is “0” when the waveform signal A is not selected. The waveform signal B selection signal 42B is “1” when the waveform signal B is selected, and is “0” when the waveform signal B is not selected. Further, the waveform signal C selection signal 42C is “1” when the waveform signal C is selected, and is “0” when the waveform signal C is not selected.

  That is, the print data is 3-bit serial data “100” when the waveform signal A is selected, “010” when the waveform signal B is selected, and “001” when the waveform signal C is selected. It becomes. Such print data is continuously equal to the number of ejectors 32 included in the corresponding ejector group 34 plus the number of ejectors 32 overlapping in the short side direction of the inkjet recording head 14 of the adjacent ejector group 34. And input to the shift register 42.

  In the following, a case where a drive waveform is supplied to one piezoelectric element 30 will be described, but the same applies to the other piezoelectric elements 30 and thus the description thereof will be omitted.

  The shift register 42 converts the input print data, which is 3-bit serial data, into 3-bit parallel data and outputs it to the latch circuit 44.

  The latch circuit 44 latches (self-holds) the parallel data output from the shift register 42 according to the input of the latch signal.

  The selector 46 receives the waveform signal A, the waveform signal B, and the waveform signal C from the controller 12 as selection target signals, and the parallel data of the print data latched by the latch circuit 44 is input to the select terminal. Accordingly, the selector 46 selects and outputs the waveform signal A, the waveform signal B, and the waveform signal C that have been selected by the print data. It should be noted that the controller 12 can input by changing the transition timing so that the waveforms of the waveform signal A, the waveform signal B, and the waveform signal C change. Although details will be described later, for example, with regard to the transition timing of the waveform signal B shown in FIG. 16C, as shown in FIG. 17, the time T1 from the first fall of the voltage HV2 to the rise of the voltage HV1, The controller 12 can control the input timing of each waveform signal B so that the time T2 during which the voltage HV1 is applied and the time T3 from the fall of the voltage HV1 to the rise of the voltage HV2 change. .

  The waveform signal output terminal of the selector 46 is connected to the level shifter 48, and the waveform signal output from the selector 46 is level-converted by the level shifter 48 and output. The level shifter 48 is supplied with power of a predetermined voltage level (a predetermined level exceeding 40 V in this embodiment) HVDD from a third power source (not shown), and the level shifter 48 has a waveform selected by print data. The signal is level-converted to a voltage level corresponding to the voltage level HVDD.

  A conventionally known level shifter 48 can be used as the level shifter 48, but in this embodiment, a P-channel MOS FET (hereinafter referred to as “PMOS”) and an N-channel MOS FET (hereinafter referred to as “PMOS”) shown in FIG. Hereinafter, a circuit configuration in which four series circuits of “NMOS” are used is applied. Note that the circuit shown in the figure corresponds to one of a pair of waveform signals input from the selector 46, and therefore, in practice, two sets of the circuits are necessary. Further, the circuit shown in FIG. 6 is also adapted to level conversion of a signal obtained by inverting one of the waveform signals, but this portion is not used in this embodiment.

  On the other hand, as shown in FIG. 3, the drive waveform generation circuit 50 according to the present embodiment includes a first signal generation circuit 52 and a second signal generation circuit 54.

  The first signal generation circuit 52 according to the present embodiment is configured as an inverter circuit configured by connecting PMOS 52A and NMOS 52B in series. Similarly, the second signal generation circuit 54 is also configured by connecting PMOS 54A and NMOS 54B in series. The inverter circuit is configured as described above.

  That is, in the first signal generation circuit 52, the drains of the PMOS 52A and the NMOS 52B are connected to each other, and the gates of the PMOS 52A and the NMOS 52B are connected. Similarly, in the second signal generation circuit 54, the drains of the PMOS 54A and the NMOS 54B are connected to each other, and the gates of the PMOS 54A and the NMOS 54B are connected.

  Here, a source of the PMOS 52A in the first signal generation circuit 52 includes a predetermined voltage level HV1 (a predetermined level within a range from 10V to 30V in the present embodiment) from a first power source which is a variable power source described later. The supplied power is supplied, and the source of the NMOS 52B is grounded to the ground level. Further, one output terminal of the level shifter 48 is connected to each gate of the PMOS 52A and the NMOS 52B, and one of the pair of waveform signals selected by the selector 46 and the waveform signal S1 whose level is converted by the level shifter 48 are input. Is done.

  Therefore, in the first signal generation circuit 52, when the signal level of the waveform signal S1 input from the level shifter 48 is high, the PMOS 52A is turned off and the NMOS 52B is turned on. Become ground level. In contrast, when the signal level of the waveform signal S1 input from the level shifter 48 is low, the PMOS 52A is on and the NMOS 52B is off, so that the voltage level of the output voltage is the voltage level HV1. As a result, the voltage output from the first signal generation circuit 52 has the same waveform as the inverted waveform of the waveform signal S1 input from the level shifter 48, and has two voltage levels: ground level and voltage level HV1. It becomes.

  On the other hand, the source of the PMOS 54A in the second signal generation circuit 54 is set to a predetermined voltage level HV2 (a predetermined level within a range from 20V to 40V in this embodiment) from a second power source which is a variable power source described later. In addition, the connection point (drain) of the PMOS 52A and the NMOS 52B in the first signal generation circuit 52 is connected to the source of the NMOS 54B. Therefore, the inverter output of the first signal generation circuit 52 is applied to the source of the NMOS 54B. Further, the other output terminal of the level shifter 48 is connected to the gates of the PMOS 54A and the NMOS 54B, and the other of the pair of waveform signals selected by the selector 46 and the waveform signal S2 whose level has been converted by the level shifter 48 are input. Is done.

  Accordingly, in the second signal generation circuit 54, when the signal level of the waveform signal S2 input from the level shifter 48 is high, the PMOS 54A is turned off and the NMOS 54B is turned on. The voltage level of the waveform is the same as the voltage output from the first signal generation circuit 52 (the waveform is the same as the inverted waveform of the waveform signal S1 input from the level shifter 48, and the voltage level is the ground level and the voltage level). Having two of HV1). In contrast, when the signal level of the waveform signal S2 input from the level shifter 48 is low, the PMOS 54A is on and the NMOS 54B is off, so that the voltage level of the output voltage (drive waveform) is the voltage level. It becomes HV2. As a result, the voltage (drive waveform) output from the second signal generation circuit 54 is output from the first signal generation circuit 52 and the second signal generation circuit 54 in accordance with the pair of waveform signals S1 and S2 input from the level shifter 48. The output voltage is a combination of three output voltages: a ground level, a voltage level HV1, and a voltage level HV2.

  FIG. 5 shows an example of the drive waveform applied to the piezoelectric element 30, the output waveform of the first signal generation circuit 52 alone and the output of the second signal generation circuit 54 required to generate the drive waveform. An example of a waveform is shown.

  As shown in the figure, when the voltage level of the drive waveform is desired to be the voltage level HV2, the voltage level of the output waveform from the second signal generation circuit 54 is set to the voltage level HV2. Therefore, in this case, the waveform signal S2 input to the second signal generation circuit 54 may be set to a low level. In this case, since the output of the first signal generation circuit 52 does not affect the output of the second signal generation circuit 54, the level of the waveform signal S1 input to the first signal generation circuit 52 is not limited.

  On the other hand, when the voltage level of the drive waveform is desired to be the voltage level HV1, the voltage level of the output waveform from the first signal generation circuit 52 is set to the voltage level HV1, and the voltage level of the output waveform from the second signal generation circuit 54 is set. Needs to be at the voltage level HV1. Therefore, in this case, it is necessary to set the waveform signal S1 input to the first signal generation circuit 52 to the low level and the waveform signal S2 input to the second signal generation circuit 54 to the high level.

  Further, when the voltage level of the drive waveform is desired to be the ground level, the voltage level of the output waveform from the first signal generation circuit 52 is set to the ground level, and the voltage level of the output waveform from the second signal generation circuit 54 is also set to the ground level. Need to be level. Therefore, in this case, it is necessary to set the waveform signal S1 input to the first signal generation circuit 52 to the high level and also set the waveform signal S2 input to the second signal generation circuit 54 to the high level.

  Table 1 shows a truth table showing the operation of the drive waveform generation circuit 50 according to the present embodiment. In the table, S1 indicates a waveform signal input to the first signal generation circuit 52, S2 indicates a waveform signal input to the second signal generation circuit 54, and OUT corresponds from the second signal generation circuit 54. The voltage level of the drive waveform supplied to the piezoelectric element 30 is shown.

  When the waveform signals S1 and S2 to be input to the first signal generation circuit 52 and the second signal generation circuit 54 are generated, a desired drive waveform is finally obtained based on the truth table shown in Table 1. A pair of waveform signal A, waveform signal B, and waveform signal C may be generated and supplied to all the drive ICs 16 so as to be obtained. FIG. 16 shows an example of the waveform signal S1 input to the first signal generation circuit 52, the waveform signal S2 input to the second signal generation circuit 54, and the drive waveforms generated by these waveform signals. ing.

  In the inkjet recording apparatus 10 according to the present embodiment, three types of “large droplets”, “medium droplets”, and “small droplets” are applied as types of ink droplets ejected by driving the piezoelectric element 30. The controller 12 generates a waveform signal A, a waveform signal B, and a waveform signal C as three sets of waveform signals that can generate drive waveforms corresponding to each of the three types of ejection amounts. , Each driving IC 16 is configured to be input. That is, FIG. 16A shows a waveform signal C. In this case, a “medium droplet” is ejected. FIG. 16B shows a waveform signal A. In this case, a “large droplet” is ejected. FIG. 16C shows a waveform signal B. In this case, “small droplets” are ejected.

  In the inkjet recording apparatus 10 according to the present embodiment, the relationship between the voltage level HVDD of power supplied from a third power supply (not shown) and the voltage level HV2 of power supplied from the second power supply (voltage level HVDD). > Voltage level HV2), and the relationship between voltage level HV2 and voltage level HV1 of power supplied from a first power supply (not shown) is (voltage level HV2> voltage level HV1).

  Further, the shift register 42 provided in the drive IC 16 according to the present embodiment is configured to hold the same number of print data as the drive target ejector 32 at a time. On the other hand, as described above, in the shift register 42, the ejector 32 in which the print data is overlapped in the short direction of the inkjet recording head 14 of the ejector group 34 arranged adjacent to the number of ejectors 32 to be driven. The number is continuously input by adding the number of. Accordingly, the drive IC 16 has a print data amount that is greater than or equal to the print data amount that can be held by the shift register 42 according to the angle of each hypotenuse of the trapezoidal shape that is the shape of the arrangement region of the ejector group 34. Print data within a range of less than twice is input.

  By the way, in the inkjet recording apparatus 10 according to the present embodiment, print data input from the controller 12 to each drive IC 16 is converted into print data for driving the ejector group 34 arranged in the corresponding unit structure. It is assumed that the input includes only print data for the ejectors 32 included in the overlapping area of the ejector groups 34 arranged in the adjacent unit structures. For this reason, the drive IC 16 needs to selectively apply only the print data for driving the ejector group 34 driven by itself from the input print data.

  In order to easily realize this, the controller 12 according to the present embodiment is provided with a clock pre-processing unit 12C.

  That is, as shown in FIG. 6, the controller 12 includes an oscillator 12A that generates a clock signal to be supplied to the driving IC 16, a non-volatile memory 12B (a flash memory as an example), a clock preprocessing unit 12C, And a CPU (Central Processing Unit) 12D that controls the operation of the controller 12 as a whole.

  The memory 12B is connected to the CPU 12D, and the CPU 12D can access the memory 12B. On the other hand, the clock preprocessing unit 12C is provided with an AND gate 12C1 having two inputs and one output. An output terminal for outputting a clock signal of the oscillator 12A is provided at one input terminal of the AND gate 12C1, and the other input terminal is provided. The CPU 12D is connected to each. The output terminal for outputting the clock signal of the oscillator 12A is also connected to the CPU 12D. The output terminal of the AND gate 12C1 supplies a clock signal to the drive IC 16.

  Here, in the memory 12B, only the signal corresponding to the input timing to the shift register 42 of the print data for driving the ejector group 34 to be driven by the drive IC 16 is valid for the clock signal input to the drive IC 16. Mask data that invalidates the signal corresponding to the input timing to the shift register 42 of the print data (i.e., print data for the ejectors 32 included in the overlapping area of the ejector groups 34 arranged in the adjacent unit structures). Stored in advance. In the mask data according to the present embodiment, “1” is applied as data corresponding to the valid timing and “0” is applied as data corresponding to the invalid timing.

  The CPU 12D reads the mask data from the memory 12B, synchronizes with the clock signal input from the oscillator 12A, as schematically shown in FIG. 7 as an example, and inputs the print data to the shift register 42 of the drive IC 16 The read mask data is serially output to the AND gate 12C1. As a result, the clock signal input from the AND gate 12C1 to the drive IC 16 is valid only for the signal corresponding to the input timing to the shift register 42 of the print data for driving the ejector group 34 to be driven by the drive IC 16. Signals corresponding to the input timing of other print data to the shift register 42 are invalidated. Accordingly, each drive IC 16 generates a drive waveform that drives only the ejector group 34 that is the target of driving, and only the ejector group 34 is driven.

  FIG. 8 schematically shows the state of the print data and the mask data, and the state of data transfer of the print data in the shift register 42 in the two drive ICs 16 corresponding to the unit structures (ejector group 34) adjacent to each other. ing. In the figure, the same print data 1, 2,... (Actually, each of the 3-bit serial data) is serially input to the two drive ICs 16 and one drive IC 16 is also input. The mask data shown in the figure is applied, and the inverted data of the mask data is applied to the other driving IC 16. Further, “-” in the figure indicates that no data transfer occurs in the shift register 42.

  As shown in the figure, in this case, the shift register 42 in one drive IC 16 transfers the data with the print data corresponding to the timing set to “0” in the mask data being thinned out, and the other drive IC 16. In the shift register 42, the print data corresponding to the timing set to “1” in the mask data is transferred in a thinned state.

  As shown in FIG. 9, each drive IC 16 is supplied with electric power (voltage is applied) from the above-described first power source 23, and each first power source 23 is controlled by the controller 12, and from each first power source 23. The voltage (HV1) applied to each corresponding drive IC 16 changes.

  Each drive IC 16 is supplied with power from the above-described second power source 20 via the switching unit 23 (a voltage is applied), and each second power source 20 is controlled by the controller 12 and from each second power source 20. The voltage (HV2) applied to each corresponding driving IC 16 changes via the switching unit 22. Note that an inspection unit 18 controlled by the controller 12 is connected to the switching unit 22.

  The plurality of first power supplies 23 and the plurality of second power supplies 20 constitute voltage applying means of the present invention.

  Since the first power source 23 and the second power source 20 have the same configuration, only the configuration of the first power source 23 will be described below with reference to FIG. 10, and the description of the configuration of the second power source 20 will be omitted. As shown in FIG. 10, the first power supply 23 receives the switching circuit 23A that receives power from the main power supply and a signal from the controller 12, and changes the voltage to the switching circuit 23A according to the frequency of the input signal. Thus, an f (frequency) -V (voltage) converter 23B that varies the output power from the switching circuit 23A is provided.

  Next, with reference to FIG. 11, the operation at the time of printing of the inkjet recording apparatus 10 according to the present embodiment will be described. FIG. 11 is a flowchart showing the flow of processing of a print processing program executed by the CPU 12D of the controller 12 when image data indicating an image to be printed is input from an external device such as a personal computer. Here, in order to avoid complications, a case where one image is printed will be described.

  In step 100 in the figure, the input image data is temporarily stored in a predetermined area of the memory 12B, and in the next step 102, print data indicating a two-dimensional image indicated by the image data is obtained based on the image data. It is created (developed) in a rectangular area in the two-dimensional memory space of the memory 12B.

  In the next step 104, the print data expanded in the two-dimensional memory space of the memory 12B is divided into print data corresponding to long rectangular images to be printed at once by the inkjet recording head 14, and the divided print data is divided. The print data is divided for each print data used in each of the ejector groups 34 provided in the ink jet recording head 14.

  Each print data obtained by this division has a trapezoidal shape similar to the shape of the arrangement region of the corresponding ejector group 34 in the two-dimensional memory space of the memory 12B, as shown in the upper diagram of FIG. Therefore, as shown in the figure, a state is assumed in which each trapezoidal shape is divided into three regions in which both ends are triangular and the middle is rectangular.

  In the example shown in the figure, as the three regions in the two-dimensional memory space of the print data corresponding to the ejector group 34A1 shown in FIG. 2, two triangular regions, region 1A1 and region 3A1, and one of region 2A1 A state of being divided into two rectangular regions is assumed. Similarly, it is assumed that the three areas corresponding to the ejector group 34B1 are divided into two triangular areas, the area 3B1 and the area 1B1, and one rectangular area, the area 2B1, and the ejector group 34A2 As the three corresponding regions, a state in which the region is divided into two triangular regions, region 1A2 and region 3A2, and one rectangular region, region 2A2, is assumed. As the three regions corresponding to ejector group 34B2, It is assumed that the area is divided into two triangular areas, area 3B2 and area 1B2, and one rectangular area, area 2B2.

  In the next step 106, as shown in the lower diagram of FIG. 12, the print data corresponding to the long rectangular image that is first printed by the ink jet recording head 14 is shown in FIG. Of the three regions in the two-dimensional memory space of the print data corresponding to the ejector groups 34 located at both ends in the longitudinal direction of the recording head 14 (the ejector group 34 located at one end is the ejector group 34A1), the longitudinal ends Dummy data (indicated as 'dummy' in the figure) is supplemented for the area located in the part. In the inkjet recording apparatus 10 according to the present embodiment, data that does not cause ink droplets to be ejected from the ejector 32 is applied as the dummy data. However, the present invention is not limited to this, and arbitrary data is applied. be able to.

  In the next step 108, as shown in FIG. 13, the print data for each ejector group 34 includes only the print data for the ejectors 32 included in the overlapping areas of the adjacent ejector groups 34. Print data is serially input to the corresponding drive IC 16.

  As a result, each ejector group 34 shares print data corresponding to the ejectors 32 that overlap with each other. In FIG. 13, an area in the two-dimensional memory space of the print data corresponding to the ejector group 34A1 (area where the areas 1A1, 2A1, and 3A1 are combined) is denoted as “A1”, and printing corresponding to the ejector group 34B1 is performed. An area in the data two-dimensional memory space (area where the areas 3B1, 2B1, and 1B1 are combined) is denoted as 'B1', and an area in the two-dimensional memory space of the print data corresponding to the ejector group 34A2 (area 1A2, 2A2, 3A2) is expressed as “A2”, and the area in the two-dimensional memory space of the print data corresponding to the ejector group 34B2 (area 3B2, 2B2, 1B2 is combined) is “B2”. It is written.

  In this case, for example, the print data DA1 input to the drive IC 16A1, the print data DB1 input to the drive IC 16B1, the print data DA2 input to the drive IC 16A2, and the print data DB2 input to the drive IC 16B2 are respectively the following ( 1) It is schematically shown as the formulas (4) to (4).

DA1 = dummy + A1 + 3B1 (1)
DB1 = 3A1 + B1 + 1A2 (2)
DA2 = 1B1 + A2 + 3B2 (3)
DB2 = 3A2 + B2 + 1A3 (4)
Here, for example, the print data DA1 and the print data DB1 are developed as shown by the following equations (5) and (6).

DA1 = dummy + 1A1 + 2A1 + (3A1 + 3B1) (5)
DB1 = (3A1 + 3B1) + 2B1 + (1B1 + 1A2) (6)
As shown in the expressions (5) and (6), the ejector group 34A1 and the ejector group 34B1 share print data including the area 3A1 and the area 3B1.

  The controller 12 inputs print data to the shift register 42 of each drive IC 16 as described above, and unnecessary print data to the shift register 42 of each drive IC 16 via the clock preprocessing unit 12C as described above. Since the clock signal in which the signal corresponding to the input timing is masked is input, each drive IC 16 ejects ink droplets only by the corresponding ejector group 34, and as a result, the inkjet recording head 14 once A long rectangular image to be printed is printed on the recording paper.

  Therefore, in the next step 110, waiting for the end of printing for one time is performed, and in the next step 112, the width of the print image in one direction in the direction perpendicular to the longitudinal direction of the ink jet recording head 14 is set. Transport only the distance corresponding to.

  In the next step 114, it is determined whether or not printing of one image has been completed. If a negative determination is made, the process returns to step 106 and the print processing program is terminated when the determination is affirmative. . Note that when the processes in steps 106 to 114 are repeatedly executed, the print data corresponding to the image area to be printed next is set as the process target print data.

  As described above in detail, according to the present embodiment, a plurality of unit structures are arranged in a predetermined direction with an ejector group in which a plurality of ejectors each ejecting ink droplets are two-dimensionally arranged as a unit structure. On the other hand, when driving the inkjet recording heads arranged so that the partial regions of the end portions of the ejector groups arranged in the adjacent unit structures overlap each other in the direction orthogonal to the one direction, the input print data And a plurality of driving circuits (here, driving ICs 16) for driving the ejector groups arranged in the corresponding unit structure are provided corresponding to each of the unit structures, and for each of the plurality of driving circuits Print data for driving the ejector group arranged in the corresponding unit structure is driven by the ejector group arranged in the corresponding unit structure. Since the print data to be input includes only the print data for driving the ejectors included in the overlapping areas of the ejector groups arranged in the unit structure adjacent to the unit structure, the joint of the ejector groups It is possible to prevent a decrease in printing speed due to the inkjet recording head due to the above.

  Next, the principle of reducing the variation in ink ejection characteristics of each ejector in the inkjet recording apparatus 10 will be described.

  The relationship between the voltage HV1 from the first power supply 23 and the voltage HV2 from the second power supply, and the amount of ink droplets ejected from the ejector 32, as shown in FIG. The relationship is stored in a memory (not shown) in the controller 12.

  Further, it has been previously understood through experiments and the like that the relationship between the time T1 for determining the waveforms of the waveform signals A to C and the amount of ink droplets ejected from the ejector 32 changes as shown in FIG. The relationship is stored in a memory (not shown) in the controller 12.

  Therefore, the variation from the ideal state of the ink ejection characteristics of the plurality of piezoelectric elements 30 in each ejector group 34 is measured, and applied to each piezoelectric element 30 so that the ink ejection characteristics of each piezoelectric element 30 are in the ideal state. It is also conceivable to change the voltages HV1 and HV2 to be changed, or to change the time T1 and the like of the waveform of the drive voltage applied to each piezoelectric element 30.

  However, if the voltages HV1 and HV2 applied to each piezoelectric element 30 are changed, a separate power source is required for each piezoelectric element 30, leading to an increase in the size of the apparatus. Further, if the controller 12 individually changes the time T1 and the like of the waveform of the driving voltage applied to each piezoelectric element 30, a control line is required for each piezoelectric element, resulting in a complicated apparatus.

  Therefore, in the present embodiment, the waveform of the drive voltage applied to each of the plurality of piezoelectric elements 30 in each ejector group 34 is changed to reduce variations in ink ejection characteristics of the plurality of piezoelectric elements 30 in each ejector group 34. As described above, each drive IC 16 is controlled and the voltage applied to each drive IC 16 is changed so that the average variation in the ink ejection characteristics of the plurality of piezoelectric elements 32 among the plurality of ejector groups 34 is reduced. The first power source 23 and the second power source 20 are controlled.

  Hereinafter, this will be described by taking the drive ICs 16A1, 16B1, 16A2, and 16B2 arranged in order from the left end of the drawing in FIG. 2 as an example. The driving ICs 16A1, 16B1, 16A2, and 16B2 are referred to as driving circuits A to D.

  As shown in FIG. 18 (a), the ink ejection characteristics of each ejector 32 that each of the drive circuits A to D is in charge, such as an appropriate amount of ink, are measured. As a result, as shown in FIG. It is assumed that the appropriate amount of ink increases monotonously with the left edge of the paper facing right, and the appropriate amount of ink for a certain ejector 32 that the drive circuit B is in charge of is the target value.

  In order to reduce the variation in the ink ejection characteristics of the ejectors 32 that each of the drive circuits A to D is responsible for and to set the ink droplet amount of each ejector 32 to the target value as shown in FIG. In principle, the following two methods are conceivable in the present embodiment (matrix control of drive waveform and applied voltage).

  First, as shown in FIG. 18B, first, the drive waveform applied to each of the plurality of piezoelectric elements 30 in each ejector group 34 is changed as described above, thereby reducing variations in each ejector group 34. Let In this case, the ink ejection characteristics (ink droplet amount) of each ejector 32 in each ejector group 34 can be made uniform, but the appropriate amount of ink among the other ejector groups 34 varies.

  Therefore, next, by changing the voltages HV1 and HV2 applied to each drive IC 16 in charge of each ejector group 34 as described above, the ink droplet amount of each ejector 32 in each ejector group 34 is finally set as a target. Can be a value.

  Second, as shown in FIG. 18C, first, the ink of each ejector 32 in each ejector group 34 is changed by changing the voltages HV1 and HV2 applied to each drive IC 16 in charge of each ejector group 34. Average drop volume reduces variation. In this case, the individual variation of the ink droplet amount of each ejector 32 in each ejector group 34 is not reduced.

  Therefore, next, the drive waveform applied to each of the plurality of piezoelectric elements 30 of each ejector group 34 is changed as described above to reduce the variation in each ejector group 34. Thereby, finally, the ink drop amount of each ejector 32 of each ejector group 34 can be set to the target value.

  By the way, when the variation in the amount of ink droplets in each ejector group 34 is reduced as described above, the time T1 for determining the waveforms of the waveform signals A to C shown in FIG. 15, the ink droplets ejected from the ejector 32, and the like. Using the relationship with the amount, the time T1 and the like are calculated from the amount of deviation between the actual value of the appropriate amount of ink and the average value (first method) or target value (second method) in each ejector group 34. Although the calculation may determine the waveforms of the waveform signals A to C, the control is complicated.

  Therefore, in the present embodiment, in view of the fact that the variation in the amount of ink droplets in each ejector group 34 is not so large, a plurality of stages of variation, specifically, for example, three stages are determined in advance and each stage is determined. The timing control data for changing the time T1 and the like is determined in advance. Then, the timing control data is determined based on the actual value of the variation of the ink droplet amount in each ejector group 34 and the above three stages, and the time T1 and the like are determined based on the determined timing control data. By changing the waveform signal, the waveform signal is changed.

  In this case, since the variation in the amount of ink droplets in each ejector group 34 is individually controlled, the control data in each of the three stages can be used in common by each ejector group 34.

  This will be described in detail below.

  For example, it is assumed that the distribution of the appropriate amount of ink for each ejector 32 in charge of the drive circuit A is obtained as shown in FIG. A first range of a predetermined range including the average value of the ink droplet amount of the ejector 32 that is in charge of the drive circuit A, a second range smaller than the lower limit value of the predetermined range, and the predetermined range for the three stages of variation The third range is determined to be larger than the upper limit value. Then, the timing control data for increasing / decreasing the time T1 at each stage is +1 (increased by a predetermined time) because the first range is 0 (that is, not corrected) and the second range is increased because the appropriate amount of ink is relatively small. ), The third range is set to -1 (decrease for a predetermined time) because the appropriate amount of ink is relatively large. By changing the waveform of each of the waveform signals A to C based on such timing control data, the ink droplet amount from the ejector 32 whose ink droplet amount is in the second range to the third range is changed to the first amount. Can range.

  The timing control data as described above can be used in the same manner in order to reduce variation in the appropriate amount of ink in each ejector 32 that the other drive circuit B is in charge of. That is, for example, it is assumed that the distribution of the appropriate amount of ink for each ejector 32 that the drive circuit B is in charge of is obtained as shown in FIG. Similar to the drive circuit A, the three stages of variation are the first range of the predetermined range including the average value of the ink droplet amount of the ejector 32 that the drive circuit B is in charge of, and the second range smaller than the lower limit value of the predetermined range. The range is determined to be a third range that is larger than the upper limit value of the predetermined range. Then, the timing control data for increasing / decreasing the time T1 at each stage is +1 (increased by a predetermined time) because the first range is 0 (that is, not corrected) and the second range is increased because the appropriate amount of ink is relatively small. ), The third range is set to -1 (decrease for a predetermined time) because the appropriate amount of ink is relatively large. By changing the waveform of each of the waveform signals A to C based on such timing control data, the ink droplet amount from the ejector 32 whose ink droplet amount is in the second range to the third range is changed to the first amount. Can range.

  However, if the average value of the ink droplet amount of the ejector 32 in charge of the drive circuit A is the target value, the ink droplet amount is the second value in each ejector 32 in charge of the drive circuit B using the timing control data. The average value of the ink droplet amount of each ejector 32 that the drive circuit B is in charge of is the same as that shown in FIG. In the example shown in FIG. 19A and FIG. 19B, the difference is larger than the target value. Therefore, in this case, by controlling the voltage applied to the drive circuit B, the average value of the ink droplet amount of each ejector 32 in charge of the drive circuit B is brought close to the target value.

  Specifically, this is performed as shown in FIG.

  In case 0 (the target drop amount rank was obtained without correction). In this case, the timing control data is 0.

Case 1 When the appropriate amount of ink for the ejector A in charge of the drive circuit A is larger than the target value, the timing control data is -1.

Case 2 When the ink droplet amount of the other ejector B in charge of the drive circuit A is smaller than the target value, the voltage condition to be applied is the same as in case 1, but the timing control data is +1.

Case 3 When the appropriate amount of ink in the ejector C, which is in charge of the drive circuit B different from the case 1 and case 2, is the target value but much smaller, the voltage applied to the drive circuit B is not the timing control data. to correct. That is, as shown in case 4, when the applied voltage is changed from HV1A → HV1B and HV2A → HV2B, the ink droplet amount of the ejector C matches the target value, and the timing control data becomes zero.

  As described above, in the present embodiment, each ejector group is provided with a drive IC, and the controller controls this drive IC. Therefore, a control line from the controller can be dispensed with for each ejector.

  Further, since the first power source and the second power source for applying a voltage to the plurality of driving ICs are provided, it is possible to eliminate the power source for each ejector.

  Thus, the control line from the controller can be made unnecessary for each ejector, and the power source can be made unnecessary for each ejector, so that the apparatus can be prevented from being enlarged.

  Then, by changing the waveform of the drive voltage applied to each of the plurality of piezoelectric elements 30 in each ejector group 34, each drive is performed so that the variation in ink ejection characteristics of the plurality of piezoelectric elements 30 in each ejector group 34 is reduced. In addition to controlling the IC 16 and changing the voltage applied to each driving IC 16, the first power supply 23 and the first power supply 23 and the first power supply 23 The second power source 20 is controlled. As described above, the variation in the appropriate amount of ink among the plurality of ejectors in each of the plurality of ejector groups can be reduced as a whole, and a stable image can be formed.

  In the above-described embodiment, each drive IC is provided with a variable power source (first power source and second power source). However, the present invention is not limited to this, and depends on the degree of variation in the appropriate amount of ink in the ejector group. As shown in FIGS. 21 and 22, variable power supplies (first power supply and second power supply) may be provided for a plurality of drive ICs. For example, in the example shown in FIG. 21, one variable power supply (first power supply and second power supply) is provided for the drive ICs 16A1 and 16B1, and one variable power supply is provided for the drive ICs 16A2 and 16B2. In the example shown in FIG. 22, one variable power supply (first power supply and second power supply) is provided for the drive ICs 16A1 and 16A2, and one variable power supply is provided for the drive ICs 16B1 and 16B2.

  In the above-described embodiment, the case where ink is used as a droplet has been described as an example. However, the present invention is not limited to this, and for example, a reaction liquid can be used instead of ink. Specifically, there is a phenomenon in which the concentration changes depending on the amount of reaction solution applied, and the present invention can be applied in the same manner as described above when controlling the concentration variation of the reaction solution. In addition, the present invention can be applied in the same manner as described above to the application of the alignment film forming material of the liquid crystal display element, the application of the flux, the application of the adhesive, and the like by the inkjet method.

1 is a schematic diagram illustrating a main configuration of an ink jet recording apparatus according to an embodiment. 1 is a plan view showing a schematic configuration of an ink jet recording head according to an embodiment. It is a block diagram (partial circuit diagram) showing a main part configuration of the drive IC according to the embodiment. It is a circuit diagram which shows the structure of the level shifter which concerns on embodiment. It is a wave form diagram which shows the example of the drive waveform which concerns on embodiment, and the example of the output waveform of the 1st signal generation circuit independent required in order to produce | generate the said drive waveform, and the output waveform of the 2nd signal generation circuit alone . It is a block diagram which shows the structure of the part regarding the production | generation of the clock signal of the controller which concerns on embodiment. It is a schematic diagram which shows the state of the output timing of the print data and mask data which concern on embodiment. FIG. 6 is a schematic diagram showing the state of print data and mask data according to the embodiment and the state of print data transfer in the shift register in two drive ICs corresponding to unit structures (ejector groups) adjacent to each other. It is the figure which showed the connection relation of the 1st power supply and the 2nd power supply. It is a block diagram of a 1st power supply. 6 is a flowchart illustrating a processing flow of a print processing program according to the embodiment. FIG. 6 is a diagram for explaining a print processing program according to an embodiment, and is a schematic diagram illustrating a state transition of print data. FIG. 6 is a diagram for explaining a print processing program according to an embodiment, and is a schematic diagram illustrating a state transition of print data. It is a graph which shows the relationship between the voltage applied to a drive IC, and an appropriate amount of ink. For example, it is a graph showing the relationship between time T1 for forming a waveform signal and an appropriate amount of ink. It is a wave form diagram which shows an example of the drive signal produced | generated by the waveform signal input into the drive waveform generation circuit of the drive IC which concerns on embodiment, and the said waveform signal. It is the figure which showed the example which changes the time which forms the waveform signal of FIG.16 (C). It is a figure explaining the method to reduce the dispersion | variation in the amount of ink droplets from an ejector. It is another figure explaining the method to reduce the dispersion | variation in the amount of ink droplets from an ejector. FIG. 10 is still another diagram illustrating a method for reducing variation in the amount of ink droplets from an ejector. It is a top view which shows schematic structure of the inkjet recording head which concerns on a modification. It is a top view which shows schematic structure of the inkjet recording head which concerns on another modification.

Explanation of symbols

10 Inkjet recording device (droplet ejection device)
12 Controller (control means)
14, 14 'inkjet recording head 16 drive IC (drive circuit)
30 Piezoelectric element (Discharging means)
32 Ejector 34 Ejector group (block)

Claims (3)

A plurality of ejection means for ejecting droplets;
It is provided for each block obtained by dividing the plurality of ejection units into a plurality of blocks. A drive voltage is applied to each of the plurality of ejection units in each block so that a droplet is ejected from each ejection unit upon application of a voltage. A plurality of drive circuits that drive and
A voltage applying means for applying a voltage to the plurality of drive circuits and capable of changing the applied voltage;
Control means for controlling the plurality of drive circuits and the application means so that variations in the ejection amount of the droplets of the plurality of ejection means in each of the plurality of blocks are reduced as a whole of the plurality of blocks;
In order to change the droplet amount of the droplets ejected from the ejection unit by changing the information on the variation in the ejection amount of the droplets of the plurality of ejection units in each block and the waveform of the driving voltage. Storage means for storing a plurality of control data different from each other,
With
The control unit changes a waveform of a drive voltage applied to each of the plurality of ejection units of each block based on the information stored in the storage unit and the plurality of control data, and a plurality of units in each block. Control data for reducing variations in the ejection amount of the droplets of the ejection unit is determined, and the waveform of the drive voltage applied to each of the plurality of ejection units in each block is changed based on the determined control data. In addition to controlling each drive circuit and changing the voltage applied to each drive circuit, the average variation in the droplet discharge amount of a plurality of ejection means between a plurality of blocks is reduced to reduce a predetermined liquid A droplet discharge apparatus, wherein the application unit is controlled to achieve a droplet discharge target amount . The control means predetermines the control data for each of a plurality of stages of relative variations in the discharge amount of the droplets of the plurality of discharge means in the block, and controls the droplets of each of the plurality of discharge means in each block. 2. The liquid droplet ejection apparatus according to claim 1, wherein the control data for reducing the actual variation is determined based on the actual variation of the ejection amount and a plurality of stages of the variation.   The length in a predetermined direction of a region where droplets are ejected by the plurality of ejection units is equal to or longer than a length of a target on which dots are formed by ejecting droplets. The droplet discharge device according to 1.

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