Inkjet recording device, control method, and program

Abstract

To miniaturize a recording head by narrowing a width of an electric wiring board.SOLUTION: An ink jet recording device includes: a recording head which has a plurality of nozzles for discharging ink and a piezoelectric element corresponding to each of the plurality of nozzles; control means which controls recording of the recording head; signal generation means which generates driving signals for driving the piezoelectric element; selection means which selects one kind of driving signal from the plurality of kinds of driving signals generated by the signal generation means for each nozzle; and each of a plurality of wirings which has a different wiring width to transmit the plurality of kinds of the driving signals supplied to the selection means from the signal generation means. The control means controls the signal generation means using use frequency information indicating each kind of use frequency of the plurality of kinds of driving signals. The control means controls the selection means using the use frequency information.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present disclosure relates to the technology of recording apparatuses such as copiers and printers, and particularly to a technology effective for an inkjet recording apparatus using a piezoelectric element.

Background Art

[0002] Patent Document 1 discloses an inkjet recording apparatus having a drive signal selection unit for selecting a drive signal in the vicinity of a piezoelectric element that discharges ink. One drive signal is selected from a plurality of drive signals by the drive signal selection unit, and the piezoelectric element is driven based on the selected one drive signal.

[0003] The recording apparatus of Patent Document 1 has signal supply wirings corresponding to each of the plurality of drive signals in order to supply the plurality of drive signals to the drive signal selection unit, and the thicknesses of these wirings are made approximately the same. The reason for this is that, regardless of which wiring is used, it is necessary to prepare a wiring width corresponding to the assumed maximum current so that the maximum number of drive elements that can be driven simultaneously can be driven.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, as a result of making the wiring width of all the wirings for signal supply the wiring width corresponding to the maximum current, there is a problem that the width of the electric wiring board is widened and the width of the recording head is increased.

[0006] Therefore, an object of the present disclosure is to narrow the width of the electric wiring board and miniaturize the recording head.

Means for Solving the Problems

[0007] One embodiment of the present invention includes a recording head having a plurality of nozzles for ejecting ink and a piezoelectric element corresponding to each of the plurality of nozzles; control means for controlling recording by the recording head; signal generation means for generating drive signals for driving the piezoelectric elements; selection means for selecting one type of drive signal from a plurality of types of drive signals generated by the signal generation means for each nozzle; and means for transmitting the plurality of types of drive signals supplied from the signal generation means to the selection means. multiple An inkjet recording device having a number of wires, The plurality of wirings include a first wiring having different wiring widths and capable of carrying the drive current for the maximum simultaneous operation of the piezoelectric elements, and a second wiring having a narrower wiring width than the first wiring and capable of carrying a drive current corresponding to a smaller number of simultaneous operations than the maximum simultaneous operation. The inkjet recording apparatus is characterized in that the control means controls the signal generation means using frequency information representing the frequency of use of each of the multiple types of drive signals, and the control means controls the selection means using the frequency information. [Effects of the Invention]

[0008] According to this disclosure, it is possible to narrow the width of the electrical wiring board and miniaturize the recording head. [Brief explanation of the drawing]

[0009] [Figure 1] Schematic diagram showing the overall configuration of an inkjet recording device. [Figure 2] Schematic diagram showing the chip unit that makes up the inkjet recording head. [Figure 3] Perspective view of an inkjet recording head [Figure 4] Schematic diagram showing the wiring of an inkjet recording head. [Figure 5] Schematic diagram showing the wiring of an inkjet recording head. [Figure 6] Diagram showing the driving method and driving signal of a piezoelectric element. [Figure 7] Block diagram showing the configuration of an inkjet recording device. [Figure 8] Block diagram showing the configuration of the image processing unit. [Figure 9] Figure showing the configuration and operation of the drive signal selection unit [Figure 10] Figure showing the first serial communication [Figure 11] Timing chart of the drive signal selection unit [Figure 12] Figure showing the residual vibration voltage [Figure 13] Figure showing the residual vibration detection circuit [Figure 14] Figure showing the drive signal generation circuit for ink ejection [Figure 15] Figure explaining the recording control unit [Figure 16] Flowchart of the usage frequency information generation process [Figure 17] Figure explaining a specific example of the usage frequency information generation process [Figure 18] Figure explaining the drive signal control table used by the drive signal generation unit [Figure 19] Figure showing the waveform of the drive signal [Figure 20] Figure explaining the drive signal selection information [Figure 21] Figure explaining the usage frequency information [Figure 22] Figure explaining the replacement process of the drive signal selection information [Figure 23] Figure explaining the drive signal transmitted through the wiring [Figure 24] Schematic diagram of the flexible printed wiring board [Figure 25] Schematic diagram of the flexible printed wiring board

Embodiments for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Unless otherwise specified, the same reference numerals indicate the same or corresponding parts throughout the drawings. Note that the features described below do not unnecessarily limit the invention according to the claims, and not all combinations of these features are essential as the solution means of the present disclosure.

[0011] <Overall Configuration of the Inkjet Recording Apparatus> Figure 1 is a side cross-sectional view showing the configuration of a recording device that uses a full-line inkjet recording head to record onto a roll-shaped recording medium such as roll paper, as an example of an inkjet recording device.

[0012] A full-line inkjet recording head (hereinafter simply referred to as "recording head") is a recording head that has a recording width greater than or equal to the length of the roll paper in the width direction.

[0013] The recording device generally consists of a housing 106, a head unit 100, first to fourth recording heads 101 corresponding to four colors such as cyan (C), magenta (M), yellow (Y), and black (K), a scanner unit 102, a line scanner 103, and transport rollers 104.

[0014] The roll paper 105 used as a recording medium is nipped by a pair of transport rollers 104 and transported in the direction of the arrow, and recorded sequentially directly below each of the first to fourth recording heads 101.

[0015] <Recording head configuration> One means of ejecting ink from the nozzle of the recording head 101 is a piezoelectric element that functions as an ejection energy generating element. A known method involves using a piezoelectric element to generate pressure in a pressure chamber, and using that pressure to eject the liquid in the pressure chamber from a nozzle formed at one end of the pressure chamber. In such a recording head 101, each piezoelectric element is equipped with an electrical contact and connected to an integrated circuit that generates a drive signal, and ejection is performed by driving the piezoelectric element with the drive signal.

[0016] Figure 2 is a schematic diagram of a chip unit 209, which combines a piezoelectric element substrate 200, a drive signal selection unit 201, and a flexible electrical wiring board 202. The piezoelectric element substrate 200 has a first terminal 200a and a second terminal 200b, which are electrically connected to terminals (not shown) provided on the drive signal selection unit 201, which is mounted on the flexible electrical wiring board 202. The flexible electrical wiring board 202 has a selection unit side terminal 203, which is electrically connected to a wiring board side terminal (not shown) provided on the drive signal selection unit 201.

[0017] The flexible electrical wiring board 202 includes a capacitor mounting section 205 for mounting a power supply bypass capacitor for the drive signal selection section 201, and a head board connection section 204 for connecting to a head board (not shown).

[0018] Figure 3 is a schematic diagram of the recording head 101. One head consists of four chip units 209. Electrical connection between each chip unit 209 and the head board 206 is made by a head board connection section 204. The head board 206 includes a signal connection section 207 and a drive signal connection section 208 that are connected to the recording device body.

[0019] Figure 4 shows the wiring of the first layer of the flexible electrical wiring board 210 (corresponding to the flexible electrical wiring board 202 in Figure 3). The first drive signal wiring 211, the third drive signal wiring 213, the fifth drive signal wiring 215, and the seventh drive signal wiring 217 have approximately the same wiring width. The drive signal feedback current wiring 219-1 is located on the opposite side of the third drive signal wiring 213 when the first drive signal wiring 211 is used as the reference. Similarly, the drive signal feedback current wiring 219-1 is located on the opposite side of the fifth drive signal wiring 215 when the seventh drive signal wiring 217 is used as the reference.

[0020] Figure 5 shows the wiring of the second layer of the flexible electrical wiring board 210. The second drive signal wiring 212, the fourth drive signal wiring 214, the sixth drive signal wiring 216, and the eighth drive signal wiring 218 have approximately the same wiring width. The drive signal feedback current wiring 219-2 is located on the opposite side of the fourth drive signal wiring 214 when the second drive signal wiring 212 is used as the reference. Similarly, the drive signal feedback current wiring 219-2 is located on the opposite side of the sixth drive signal wiring 216 when the eighth drive signal wiring 218 is used as the reference.

[0021] <Method for driving piezoelectric elements and driving signals for piezoelectric elements> The method for driving the piezoelectric element 301 and the driving signal applied to the piezoelectric element 301 will be explained using Figure 6. Driving the piezoelectric element 301 requires the following four steps, from step (1) to step (4), which will be explained in order.

[0022] Step (1): In the initial state, the pressure chamber 304 is filled with ink 305, and a high voltage is applied from the voltage source 303 between the upper electrode 300 and the lower electrode 302 of the piezoelectric element 301, causing the pressure chamber 304 to contract.

[0023] Step (2): The voltage of the voltage source 303 is reduced to expand the pressure chamber 304, drawing the ink 305 into the expanded pressure chamber 304. At this time, a sinusoidal pressure wave is generated in the pressure chamber 304 by the piezoelectric element 301.

[0024] Step (3): By increasing the voltage of the voltage source 303 in synchronization with the pressure wave generated in step (2), the pressure chamber 304 is contracted and the ink 305 is ejected.

[0025] Step (4): After step (3), mechanical vibration continues in the piezoelectric element 301. To cancel out this mechanical vibration and bring the piezoelectric element 301 to a standstill, the voltage of the voltage source 303 is increased again.

[0026] The series of operations described above, from step (1) to step (4), constitutes one discharge operation. Furthermore, the series of voltage changes in the voltage source 303 from step (1) to step (4) represent the waveform of the drive signal to be applied to the piezoelectric element 301.

[0027] <Configuration of an inkjet recording device> The configuration of the inkjet recording device will now be described. Figure 7 is a block diagram showing the configuration of the inkjet recording device. The Host PC 401 sends a print command and a print job containing print image data and print setting information to the control controller 400. The control controller 400 that controls the inkjet recording device has a receiving I / F 402, ROM 403, RAM 404, motor / sensor control unit 405, image processing unit 406, recording control unit 407, and CPU 410.

[0028] The receiving interface 402 transmits and receives data with the Host PC 401. The ROM 403 stores the program that operates the CPU 410. The RAM 404 is used for program execution and also temporarily stores various data. The motor / sensor control unit 405 controls the motors and sensors in the inkjet recording device. The image processing unit 406 performs image processing on the image data included in the print job sent from the Host PC 401 through the receiving interface 402. Specifically, for example, the image processing unit 406 generates bitmap-format raster image data based on the image data expressed in a page description language included in the print job received from the Host PC 401. Furthermore, the image processing unit 406 converts the generated image data into image data for each ink color, such as CMYK, that can be processed by the recording control unit 407 and outputs it. The recording control unit 407 performs recording control on the recording head 413 (corresponding to the recording head 101 in Figure 1) based on the image data output by the image processing performed by the image processing unit 406.

[0029] The recording control unit 407 includes a drive signal control unit 408 and a drive signal selection information transmission unit 409. The drive signal control unit 408 transmits a control signal for generating a drive signal to the drive signal generation unit 411. The drive signal selection information transmission unit 409 transmits drive signal selection information to the drive signal selection unit 412 (corresponding to the drive signal selection unit 201 in Figure 2) via serial communication (referred to as first serial communication) using a predetermined transmission line. Serial communication refers to a communication method that uses one or two transmission lines to send and receive data, and transmits and receives data one bit at a time continuously.

[0030] The drive signal generation unit 411 outputs multiple drive signals to the drive signal selection unit 412 based on the control signal transmitted from the drive signal control unit 408. In this embodiment, the multiple drive signals are described as including three types of drive signals (large ink droplet size, small ink droplet size, and no ink droplet ejection), which will be described later (see Figure 11, etc.).

[0031] The drive signal selection unit 412 selects a drive signal from among multiple drive signals transmitted by the drive signal generation unit 411 based on the drive signal selection information transmitted by the drive signal selection information transmission unit 409. The drive signal selected by the drive signal selection unit 412 is input to the piezoelectric element 301 corresponding to the nozzle in the recording head unit. When the voltage of the drive signal waveform is applied to the electrodes of the piezoelectric element 301, the piezoelectric element 301 between the electrodes is displaced, and ink is ejected from the nozzle using the energy generated as a result.

[0032] The aforementioned first serial communication connects the drive signal selection information transmission unit 409 and the drive signal selection unit 412, and the clk signal, data signal, and latch signal are transmitted. Specifically, information is transmitted on the data signal in synchronization with the clk signal, and information is transmitted in units of the latch signal.

[0033] The drive signal selection information transmission unit 409 and the drive signal selection unit 412 are connected by a second serial communication using a different transmission path than that used in the first serial communication. The second serial communication is used to perform settings within the drive signal selection unit 412. In this example, a communication protocol such as SPI (Serial Peripheral Interface), which is generally widely known, is used for the second serial communication, but the communication method is not limited to this.

[0034] The recording head 413 consists of nozzles (also called ejection holes) with an ink ejection mechanism, and piezoelectric elements 301 corresponding to the nozzles. Ink is ejected by inputting a drive signal to the piezoelectric elements 301 corresponding to the nozzles. In the following explanation, unless otherwise specified, the recording head 413 will be described using an example consisting of 128 nozzles and piezoelectric elements 301 corresponding to each nozzle, but the number of nozzles can be any integer of 2 or more.

[0035] Figure 8 is a block diagram showing the detailed structure of the image processing unit 406 in Figure 7. Instructions from the CPU 410 to the image processing unit 406 are given by writing appropriate values ​​to registers (not shown).

[0036] The image processing input unit 421, based on instructions from the CPU 410, takes image data included in the print job from the RAM 404 and outputs it to the image generation unit 422. The image generation unit 422 converts the received image data into CMYK 4-channel image data with a resolution that the recording head 413 can record, and outputs it to the output gradation correction processing unit 423. The output gradation correction processing unit 423 performs correction processing corresponding to the output characteristics of the ink. The quantization processing unit 424 converts 8-bit to 16-bit gradation data into gradation data that can be represented by the nozzles of the recording head. Generally, this is done by N-sampling using error diffusion or dithering, and converting the gradation into 1-bit to 4-bit image data. The impact position misalignment correction processing unit 425 shifts the data on a pixel-by-pixel basis to correct the impact position misalignment for each nozzle on an image resolution basis. The image processing output unit 426 outputs the image data that has undergone the above image processing to the RAM 404, and this image data is stored in the RAM 404.

[0037] <Drive signal selection section> The drive signal selection unit 412 shown in Figure 7 will be explained using Figure 9. Data transmitted from the drive signal selection information transmission unit 409 via the first serial communication is received by the serial-to-parallel conversion unit 506 and held in the data latch 507 starting from the input timing of the latch signal. The held drive signal selection information is input to the decoder 509.

[0038] The drive signal generation unit 411 is composed of a plurality of digital-to-analog conversion units 512 and a plurality of drive signal generation circuits 513. The digital-to-analog conversion units 512 receive control signals from the drive signal control unit 408. The drive signal generation circuits 513, having received the analog signals output by the digital-to-analog conversion units, generate drive signals.

[0039] The generated drive signal is input to the switch group 510 in the drive signal selection unit 412. The switch group 510 consists of multiple switches SWx-y (where x corresponds to a nozzle number that identifies a nozzle, and y corresponds to a drive signal number that identifies a drive signal). Based on the decoding information from the decoder 509, the switch group 510 selects a drive signal from among the multiple drive signals and drives the piezoelectric element 301 corresponding to the nozzle. In this example, the recording head 413 consists of a nozzle group 503 containing 128 nozzles and a piezoelectric element 301 corresponding to each nozzle, and there are the same number of decoders 509 and switch groups 510 as there are nozzles.

[0040] <First Serial Communication> Figure 10 shows the contents of the signals transmitted from the drive signal selection information transmission unit 409 via the first serial communication. As shown in the figure, the data signal is transmitted in synchronization with the clk signal. The latch signal indicates the end of one transmission.

[0041] The data signal does not need to be just one; the number of data signals may be increased, taking into account the balance with the clk signal frequency, to enable the ejection of ink at the predetermined ejection frequency. Note that "ink ejection frequency" refers to the number of times the recording head ejects ink droplets per second.

[0042] In this disclosure, data equivalent to one column, specifically the number of nozzles × the drive signal selection information (i.e., the number of drive signal types), is transmitted between one latch signal and the next. For example, in the case where there are four types of drive signals and 128 nozzles, 128 × 2 bits of data (representing selection from the four types of signals) are transmitted between the latch signals. On the other hand, in the case where there are switches for residual vibration detection (details will be described later) in addition to the four types of drive signals, the sum of the number of drive signal types and the number of switches for residual detection is 5 (=4+1). Therefore, 128 × 3 bits of data (because selection is made from five states) needs to be transmitted between the latch signals.

[0043] <Timing chart for drive signal selection section> The timing chart of the drive signal selection unit will be explained using Figure 11. Figure 11 shows the relationship between the data transmitted via the first serial communication and the drive signal. Between one latch signal and the next latch signal, one column of drive signal selection information is transferred, and the received data is held in the data latch 507 (see Figure 9) starting from the reception of the latch signal. Then, based on the data held in the data latch 507, one type of drive signal is selected from among several types for each nozzle and transmitted to the piezoelectric element 301 corresponding to each nozzle. For example, in the case of Figure 11, three types of drive signals are assumed. Therefore, in this case, there are three drive signal generation circuits (513-0, 513-1, 513-2) in Figure 9. Drive signals that can realize desired ink droplet states, such as large ink droplet size, small ink droplet size, no ink droplet ejection, etc., are assigned to these three drive signal generation circuits 513 and used. As shown in Figure 11, the drive signal for achieving a large ink droplet size is defined as "drive signal 0," the drive signal for achieving a small ink droplet size is defined as "drive signal 1," and the drive signal for achieving a state where no ink droplets are ejected is defined as "drive signal 2."

[0044] <Residual vibration detection circuit> Among the switches included in the switch group 510 shown in Figure 9, switches SWx-0 to SWx-n (in this example, x and n are each integers in the range of 0 to 127) are switches for applying a drive signal to the piezoelectric element 301 corresponding to nozzle x.

[0045] On the other hand, the switches SWx-z (in this example, x is a single integer in the range of 0 to 127) are switches that supply the residual vibration voltage generated in the piezoelectric element 301 due to residual vibration after the piezoelectric element 301 has been driven to the residual vibration detection circuit 511.

[0046] As shown in Figure 12, first, in section st1, a drive signal is applied to the piezoelectric element 301 to drive it. Then, the switch is turned off to stop the application of the drive signal to the piezoelectric element 301. As shown in Figure 12, in section st2, a voltage Amp-in appears on the piezoelectric element 301. This voltage is the result of residual mechanical vibrations in the piezoelectric element 301 being converted into a voltage by the piezoelectric effect, and is called the "residual vibration voltage". By detecting and analyzing the residual vibration voltage, abnormalities in each nozzle can be detected.

[0047] The detection of residual vibrations performed by the residual vibration detection circuit 511 in Figure 9 will be explained using Figure 13.

[0048] The residual oscillating voltage Amp-in is supplied to the non-inverting input terminal V+ of the operational amplifier OPAz via the switch SWx-z and capacitor Ca. The non-inverting input terminal V+ of the operational amplifier OPAz is connected to the bias voltage Vbias via resistor Rm. On the other hand, the inverting input terminal V- of the operational amplifier OPAz is connected to the bias voltage Vbias via resistor Rb. The inverting input terminal V- of the operational amplifier OPAz is connected to the output terminal of the operational amplifier OPAz via resistor Ra.

[0049] In the above circuit, the residual vibration voltage Amp-in is amplified to become the residual vibration detection voltage Vz. The residual vibration detection voltage Vz is expressed by equation (1).

[0050]

number

[0051] The residual vibration detection voltage Vz is sent outside the residual vibration detection circuit 511. Subsequently, the residual vibration detection voltage Vz is converted into a digital signal by an analog-to-digital converter (not shown) and analyzed by a logic operation element (not shown).

[0052] <Drive signal generation circuit> The drive signal generation circuit 513 shown in Figure 9 will be explained using Figure 14. Figure 14 is a circuit diagram of the drive signal generation circuit 513. The drive signal generation circuit 513 is a so-called amplifier circuit that amplifies the voltage and current of the analog signal 608 supplied to the non-inverting input terminal V+ of the operational amplifier 607.

[0053] As shown in Figure 14, the drive signal generation circuit 513 consists of transistors 601 and 602 connected in Darlington on the high side, transistors 603 and 604 connected in Darlington on the low side, and an operational amplifier 607. Transistors 601 and 602 are NPN transistors, and transistors 603 and 604 are PNP transistors.

[0054] The base terminals of transistor 602 and transistor 604 are each connected to the output terminals of operational amplifier 607 via diodes. The emitter terminals of transistor 601 and transistor 603 are each connected to piezoelectric element 301 via switches SWx-n (not shown).

[0055] In the above configuration, when the analog signal 608 is input to the drive signal generation circuit 513, the voltage of the analog signal 608 is amplified in the operational amplifier 607. Next, the current is amplified by transistors 601 and 602, and transistors 603 and 604.

[0056] Ultimately, the piezoelectric element 301 is driven by the amplified voltage and current drive signal 610, causing the ink to be ejected.

[0057] [First Embodiment] The first embodiment will be described below with reference to Figures 15 to 25.

[0058] Figure 15 is a block diagram showing the configuration of the recording control unit 407 (see Figure 7) in this embodiment.

[0059] Instructions from the CPU 410 to the recording control unit 407 are made by writing an appropriate value to the register unit 434.

[0060] The drive signal selection information generation unit 431 reads image data from the RAM 404 and outputs drive signal selection information indicating which drive waveform to select for each pixel in the image to the drive signal selection information transmission unit 409 and the usage frequency determination unit 432. In this embodiment, the value of each pixel in the image data is used directly as the value of the drive signal selection information, but different values ​​may be used for each nozzle according to the ejection characteristics of each nozzle instructed by the CPU 410 as the value of the drive signal selection information. In this embodiment, the data for each pixel in the drive signal selection information takes one of three values: "0" indicating the selection of a non-ejecting drive signal, "1" indicating the selection of a drive signal for a large ink droplet size, or "2" indicating the selection of a drive signal for a small ink droplet size.

[0061] The usage frequency determination unit 432 performs usage frequency information generation processing on the data input from the drive signal selection information generation unit 431, determining the usage frequency of the drive signal selection information for each column of data. A "column" refers to a drive unit that is processed together in one process. In this example, one column is defined as one line of nozzles arranged in the sub-scanning direction on the recording head. The usage frequency information generation processing will be described later with reference to Figure 16.

[0062] The usage frequency information PriTab is a table data that shows the order of usage frequency for each value of the drive signal selection information. In this example, where three values ​​are used as the drive signal selection information, it is represented as {a, b, c}. a is the usage frequency rank corresponding to "0", b is the usage frequency rank corresponding to "1", and c is the usage frequency rank corresponding to "2". In this embodiment, the usage frequency rank values ​​are represented from 0 to 2.

[0063] For example, consider a case where, in the drive signal selection information corresponding to a certain column, "0" is used most frequently, "1" is used less frequently, and "2" is used even less frequently (the least frequently used of the three values). In this case, the usage frequency information PriTab will be {0,1,2}.

[0064] For example, consider the case where, in the drive signal selection information corresponding to another column, "2" is used most frequently, "0" is used less frequently, and "1" is used even less frequently (the least frequently used of the three values). In this case, the usage frequency information PriTab will be {1,2,0}.

[0065] The drive signal selection information transmission unit 409 performs a replacement process on each value of the drive signal selection information output from the drive signal selection information generation unit 431, based on the usage frequency information output from the usage frequency determination unit 432. This replacement process converts the drive signal selection information (values) to predetermined values ​​in order of decreasing usage frequency. As an example of the replacement process in this embodiment, equation (2) is shown below when the drive signal selection information of a certain pixel is InDat[i] and the drive signal selection information of the same pixel after the replacement process is OutDat[i]. OutDat[i]=PriTab[InDat[i]](i:0~127)...Equation (2) Here, we assume that there are 128 nozzles per column (1 line), and that i can take any value between 0 and 127.

[0066] For example, if the usage frequency information PriTab = {1, 2, 0} and the value of a certain pixel in the drive signal selection information is "2", the drive signal selection information after the replacement process using equation (2) becomes "0". Similarly, if the value of a certain pixel in the drive signal selection information is "0", the drive signal selection information after the replacement process becomes "1", and if the value of a certain pixel is "1", the drive signal selection information after the replacement process becomes "2". In this way, the values ​​of the drive signal selection information are converted into values ​​of usage frequency ranking by the replacement in this embodiment. The drive signal selection information transmission unit 409 transmits the replaced drive signal selection information to the drive signal selection unit 412 via the first serial communication.

[0067] The usage frequency buffer 433 temporarily buffers the usage frequency information and outputs it to the drive signal control unit 408. In this embodiment, the timing at which the drive signal control unit 408 uses the usage frequency information is after the drive signal selection unit 412 has latched the drive signal selection information once. Therefore, the usage frequency buffer 433 buffers the usage frequency information so as to be delayed by one latch signal.

[0068] The drive signal control unit 408 selects, based on the usage frequency information output from the usage frequency determination unit 432, which drive signal generation unit 411 should generate for which wiring on the flexible electrical wiring board 202 and which waveform of drive signal to produce. The drive signal control unit 408 then transmits a control signal based on this selection to the drive signal generation unit 411. The multiple drive waveforms generated by the drive signal generation unit 411 based on the control of the drive signal control unit 408 are input to the drive signal selection unit 412 via the multiple drive signal wirings of the flexible electrical wiring board 202, as explained with reference to Figure 9. Here, the multiple drive signal wirings in the flexible electrical wiring board 202 of this embodiment each have different wiring widths. First, there is a drive signal wiring with a wiring width that can handle the drive current when all piezoelectric elements are driven simultaneously (100% drive) (in other words, it is possible to flow such a current). In this specification, as mentioned above, the case where all piezoelectric elements are driven simultaneously is referred to as "100% driven," and the case where a predetermined percentage n% of piezoelectric elements are driven simultaneously is referred to as "n% driven."

[0069] In this embodiment, drive signal wiring capable of handling drive currents up to 75% drive, drive signal wiring capable of handling drive currents up to 50% drive, drive signal wiring capable of handling drive currents up to 33% drive, etc., are also provided, and the wiring width of each wire is narrowed in proportion to the drive current. The operation of the drive signal control unit 408 will be described later with reference to Figures 18 and 19.

[0070] <Frequency of Use Information Generation Process> The usage frequency information generation process in this embodiment will be described below with reference to Figure 16. Figure 16 is a flowchart of the process performed by the usage frequency determination unit 432 based on instructions from the CPU 410.

[0071] In step S1601, the usage frequency determination unit 432 acquires drive signal selection information for one unprocessed column of data to be processed. Here, "one column" is explained as "one nozzle line in the recording head." Also, for simplicity, "step S~" will be abbreviated as "S~" from here on.

[0072] In S1602, the usage frequency determination unit 432 analyzes the data of each pixel included in the drive signal selection information acquired in S1601 and performs a counting process to count how often each of the possible values ​​for the drive signal selection information is used. In this embodiment, as described above, the value can be one of three values: "0" which indicates the selection of a non-ejecting drive signal, "1" which indicates the selection of a drive signal for a large ink droplet size, and "2" which indicates the selection of a drive signal for a small ink droplet size. Therefore, the count values ​​for "0", "1", and "2" (i.e., the number of times each value is used per line) are determined.

[0073] In S1603, the usage frequency determination unit 432 uses the count values ​​for each possible value of the drive signal selection information derived in S1602 to determine the usage frequency order (rank), with the highest count value indicating the highest usage frequency.

[0074] In S1604, the usage frequency determination unit 432 outputs the usage frequency order information (referred to as usage frequency information) determined in S1603. The usage frequency information output by the usage frequency determination unit 432 is received by the drive signal selection information transmission unit 409 and the usage frequency buffer 433. Once reception is confirmed, the process proceeds to step S1605.

[0075] In S1605, the usage frequency determination unit 432 determines whether the output of the usage frequency information in S1604 has been completed for all data to be processed. For example, if the output of the information in S1604 has been completed for one page of image data, the result of this step may be set to true. If the result of this step is true, the series of processes is completed; however, if the result is false, the process returns to S1601.

[0076] <<Another specific example of the usage frequency information generation process>> Below, as an example of the usage frequency information generation process, a specific example different from the one described above will be explained using Figure 17.

[0077] Table 1701 stores nozzle data for each line. Here, we assume that there are 512 nozzles per line, and we adopt eight possible values ​​for the drive signal selection information: "0", "1", "2", "3", "4", "5", "6", and "7". The following explanation will use the Nth line (let's call it line N) as an example.

[0078] In S1601, the usage frequency determination unit 432 acquires the drive signal selection information for line N as drive signal selection information for one column that has not been processed.

[0079] In step S1602, the usage frequency determination unit 432 analyzes the data of each pixel included in the drive signal selection information of line N and performs a counting process to count how often each value from "0" to "7" is used. In the example in Figure 17, the value "4" is used most often with a count value of 130, followed by the value "0" (count value: 90). On the other hand, the value "2" (count value: 0) is not used even once.

[0080] In S1603, the usage frequency determination unit 432 uses the count value derived in S1602 to determine the usage frequency order (rank), with the highest count value indicating the highest usage frequency. In the example in Figure 17, the usage frequency order is "4", "0", "7", "6", "3", "1", "2", and in table 1703, the field on line N with the value "4" holds 0, which represents the highest rank in usage frequency. In this example, the highest rank is represented as 0 and the lowest rank as 7.

[0081] In S1604, the usage frequency determination unit 432 outputs the usage frequency information for line N determined in S1603.

[0082] The processes described above, S1601 to S1604, are performed for all lines.

[0083] <Operation of the drive signal control unit> The operation of the drive signal control unit 408 will be explained below with reference to Figures 18 and 19.

[0084] Figure 18 illustrates an example of the drive signal control table drive_tab used by the drive signal control unit 408 in this embodiment. The drive signal control unit 408 can use the drive signal control table drive_tab by setting the CPU 410 to write an appropriate value to the register unit 434. The drive signal control table drive_tab holds a value instructed by the CPU 410 on how much of a drive signal value should be used to drive the piezoelectric element at predetermined intervals. In this embodiment, an 8-bit digital value, specifically any single value within the range of 0 to 255, is used as the value set and held in drive_tab. i indicates a multiple of how many times the predetermined time is multiplied, and i=n means predetermined time × n. The initial value of i is 0. That is, i=0 indicates the start of the drive signal.

[0085] Furthermore, the drive signal control table drive_tab holds sets of values ​​corresponding to each type in order to generate waveforms for multiple types of drive signals, such as non-ejection, large ink droplet size, and small ink droplet size. Figure 18 shows three types of drive signal control tables drive_tab, namely drive_tab[0], drive_tab[1], and drive_tab[2]. drive_tab[0] is an example of a drive signal control table used to drive nozzles that do not eject ink. Similarly, drive_tab[1] is an example of a drive signal control table used to drive nozzles that produce large ink droplets, and drive_tab[2] is an example of a drive signal control table used to drive nozzles that produce small ink droplets.

[0086] Figure 19 shows graphs based on the three types of drive signal control tables drive_tab shown in Figure 18, with the horizontal axis representing i and the vertical axis representing the value in each graph. Specifically, Figure 19(a) shows the drive signal control table drive_tab[0] used to drive nozzles that do not eject ink. Figure 19(b) shows the drive signal control table drive_tab[1] used to drive nozzles that produce large ink droplets. Figure 19(c) shows the drive signal control table drive_tab[2] used to drive nozzles that produce small ink droplets.

[0087] The drive signal generated by the drive signal generation unit 411 based on the table shown in Figure 19(c) has a smaller amplitude than the drive signal generated by the drive signal generation unit 411 based on the table shown in Figure 19(b). As a result, the degree to which the pressure chamber 304 expands and contracts is reduced, resulting in a difference in the amount of ink ejected. Generally, the larger the amplitude, the larger the ink droplets ejected.

[0088] The drive signal control unit 408 controls the waveforms of multiple drive signals output by the drive signal generation unit 411 by changing the value transmitted to the drive signal generation unit 411 at predetermined intervals using the drive signal control table drive_tab. In this embodiment, the drive signal control unit 408 uses the usage frequency information PriTab to rearrange the drive signal control table drive_tab so that each column is ordered by the most frequently used type. This rearrangement process will be described later.

[0089] <Replacing control signals for the drive waveform, and replacing drive signal selection information> The following describes, using Figures 20 to 23, the swapping of drive waveform control signals and the swapping of drive signal selection information, which are performed by the recording control unit 407 in this embodiment.

[0090] On the left side of Figure 20, an example of image data representing drive signal selection information processed by the usage frequency determination unit 432 is shown. The dashed areas (a-1), (b-1), (c-1), and (d-1) in this image each refer to a part of the drive signal selection information (image). Figure 20 also shows enlarged views (a-1), (b-1), (c-1), and (d-1) of these dashed areas.

[0091] The histogram (a-2) shows how much of each of the three values ​​(i.e., 0, 1, and 2) of the drive signal selection information is used in one column, line (a-0) in this example, corresponding to region (a-1).

[0092] Furthermore, histogram (b-2) shows how often each of the three values ​​of the drive signal selection information is used in line (b-0) corresponding to region (b-1). Histograms (c-2) and (d-2) are similar. These histograms are examples of the results of the counting process performed by the usage frequency determination unit 432.

[0093] Figure 21(a) shows the usage frequency information PriTab derived by the usage frequency determination unit 432, which represents the usage frequency information corresponding to the histogram (a-2) in Figure 20. Similarly, Figure 21(b) corresponds to the histogram (b-2), Figure 21(c) corresponds to the histogram (c-2), and Figure 21(d) corresponds to the histogram (d-2).

[0094] The image of the drive signal selection information depends on the image to be printed, which is input by the user using a recording device, and the waveform of the drive signal used by each nozzle differs in each region. For example, in region (a-1), looking at the distribution of the frequency of use of the values ​​(drive signal selection information) in line (a-0), it can be seen that "1", which indicates a large ink droplet size, is used frequently. In contrast, in region (b-1) or region (c-1), various types of drive signal waveforms will be used.

[0095] Figure 22 shows image data representing the drive signal selection information after the drive signal selection information shown in Figure 20 has been replaced, as an example of the replacement process performed by the drive signal selection information transmission unit 409. In Figure 22, the symbols (a), (b), (c), and (d) represent enlarged views of the corresponding areas of the drive signal selection information after the replacement process.

[0096] In the Column (1 line) corresponding to region (a) shown in Figure 22, as shown in Figure 21(a), the value "1" was the most frequently used value for the drive signal selection information, followed by "0" and then "2," resulting in a usage frequency order of {1, 0, 2}.

[0097] As mentioned above, the drive signal selection information transmission unit 409 replaces the values ​​of the drive signal selection information based on the frequency of use, replacing the value "0" in the drive signal selection information in region (a-1) of Figure 20 with the value "1". In addition, it replaces the value "1" in the drive signal selection information in region (a-1) of Figure 20 with the value "0", and replaces the value "2" with the value "2".

[0098] In regions (b), (c), and (d) of Figure 22, substitutions based on frequency of use are performed, similar to region (a). In this way, in each column, the values ​​of the drive signal selection information are replaced in order of the most frequently used drive waveform types.

[0099] Figure 23 shows the waveforms of the drive signals generated by the drive signal generation unit 411 and corresponding to each drive signal wiring in the columns corresponding to regions (a) to (d) in Figure 22, as a result of control signal transmission by the drive signal control unit 408 of this embodiment.

[0100] In the Column (1 line) corresponding to region (a) shown in Figure 22, as shown in Figure 21(a), the value "1" was the most frequently used value for the drive signal selection information, followed by "0" and then "2," resulting in a usage frequency order of {1, 0, 2}.

[0101] Therefore, the drive signal control unit 408 associates the drive signal control table drive_tab[1] with drive signal 0 based on this frequency of use, thereby performing control based on the drive signal control table drive_tab[1].

[0102] Furthermore, the drive signal control unit 408 associates drive signal 1 with drive signal control table drive_tab[0] based on this frequency of use, thereby enabling control based on drive signal control table drive_tab[1]. In addition, the drive signal control unit 408 associates drive signal control table drive_tab[2] with drive signal 2 based on this frequency of use, thereby enabling control based on drive signal control table drive_tab[2].

[0103] In regions (b), (c), and (d) of Figure 22, similar to region (a), the drive signal control table drive_tab is swapped based on usage frequency to control the waveform of the drive signal. In this way, control signals are transmitted so that in each column, drive signal wiring capable of handling drive currents that can drive many piezoelectric elements (in other words, wider drive signal wiring) is assigned in order from the most frequently used drive signals.

[0104] <Effects of this embodiment> As explained above, by swapping the control signals of the drive waveform and the drive signal selection information so that drive signals are assigned to each column in order of frequency of use, it is possible to use wiring according to the number of elements to be driven. As a result, for example, as shown in Figures 24 and 25, it becomes possible to narrow the width of the flexible electrical wiring board and miniaturize the recording head.

[0105] Figure 24 shows the wiring of the first layer of the flexible electrical wiring board 220 in this embodiment. Figure 25 shows the wiring of the second layer of the flexible electrical wiring board 220 in this embodiment, as viewed through from the first layer side. The first and second layers form the laminated structure of the flexible electrical wiring board 220.

[0106] As shown in Figure 24, the first layer has a first drive signal wire 221 that can handle the drive current when all (100%) of the piezoelectric elements are driven simultaneously (in other words, it is possible to supply such a current). The first layer also has a second drive signal wire 223 that can handle the current required to drive 75% of the piezoelectric elements simultaneously. Similarly, the first layer has a third drive signal wire 225 that can handle the current required to drive 50% of the piezoelectric elements simultaneously, and a fourth drive signal wire 227 that can handle the current required to drive 33% of the piezoelectric elements simultaneously.

[0107] The drive signal feedback current wiring 229-1 is the return path for the drive signal and can handle the feedback current of the drive signal when the device is driven at 100%. Other components include, as shown in Figure 24, a mounting section 236 for mounting a drive signal selection unit that selectively switches the drive signal applied to the piezoelectric element. It also has a first control signal line 231, a second control signal line 232, and a third control signal line 233 for transmitting control signals to drive the drive signal selection unit, as well as a synchronization signal line 230. In addition, there is a power line for supplying power to the drive signal selection unit, a power bypass capacitor, a connection section 235 for connecting to the head board connected to the recording device body, a residual vibration signal line 234 for transmitting residual vibrations of the piezoelectric element to the main body, and a reference voltage line fixed at a constant potential.

[0108] As shown in Figure 25, the second layer has a first drive signal wiring 222 that can handle the drive current when all (100%) of the piezoelectric elements are driven simultaneously (in other words, it is possible to flow such a current). The second layer also has a second drive signal wiring 224 that can handle the current to drive 75% of the piezoelectric elements simultaneously. Similarly, the third drive signal wiring 226 is wired that can handle the current to drive 50% of the piezoelectric elements simultaneously, and the fourth drive signal wiring 228 is wired that can handle the current to drive 33% of the piezoelectric elements simultaneously. Furthermore, the second layer has a drive signal feedback current wiring 229-2 that can handle the feedback current of the drive signal when 100% is driven, and a reference voltage line fixed at a constant potential, etc.

[0109] [Other embodiments] This disclosure can also be implemented by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions. [Explanation of Symbols]

[0110] 407 Recording Control Unit 411 Drive signal generation unit 412 Drive signal selection section

Claims

1. A recording head having a plurality of nozzles for ejecting ink, and a piezoelectric element corresponding to each of the plurality of nozzles, Control means for controlling recording with the recording head, A signal generation means for generating a drive signal for driving the piezoelectric element, For each nozzle, a selection means for selecting one type of drive signal from among the multiple types of drive signals generated by the signal generation means, A plurality of wires for transmitting the plurality of drive signals supplied from the signal generation means to the selection means, An inkjet recording device having, The plurality of wirings include a first wiring having different wiring widths and capable of carrying the drive current for the maximum simultaneous operation of the piezoelectric elements, and a second wiring having a narrower wiring width than the first wiring and capable of carrying a drive current corresponding to a smaller number of simultaneous operations than the maximum simultaneous operation. The control means controls the signal generation means using frequency information representing the frequency of use of each of the multiple types of drive signals. The control means controls the selection means using the usage frequency information. An inkjet recording apparatus characterized by the following features.

2. The control means controls the signal generation means so that the most frequently used type of drive signal is supplied via the first wiring based on the usage frequency information. The inkjet recording apparatus according to claim 1, characterized in that

3. The control means is Information generation means for generating first selection information for each of the plurality of nozzles, which selects one type of drive signal from the plurality of types of drive signals, A determination means that determines the usage frequency of each of the multiple types of drive signals using the first selection information, It further possesses, The aforementioned determination means generates the usage frequency information. The inkjet recording apparatus according to feature 2.

4. The determination means performs a counting process to count how many times each of the possible values ​​for the first selection information is used. The inkjet recording apparatus according to claim 3, characterized in that

5. The determination means executes the counting process for each predetermined drive unit. The inkjet recording apparatus according to claim 4, characterized in that

6. The predetermined drive unit is a nozzle line arranged in the sub-scanning direction in the recording head. The inkjet recording apparatus according to claim 5, characterized in that

7. The first wiring is capable of carrying current to simultaneously drive the piezoelectric elements corresponding to all of the nozzles included in the nozzle line 1. The inkjet recording apparatus according to claim 6, characterized in that

8. The control means further includes an information transmission means that transmits to the selection means a second selection information generated by substituting the value of the first selection information using the frequency of use information. The selection means selects the one type of drive signal using the second selection information. The inkjet recording apparatus according to any one of claims 5 to 7, characterized by the features described herein.

9. The information transmission means generates the second selection information by replacing the value of the first selection information with a value indicating the ranking of the usage frequency, in accordance with the order of usage frequency of the values ​​of the first selection information in the predetermined drive unit. The inkjet recording apparatus according to feature 8.

10. The control means further includes a signal transmitting means that transmits a control signal to the signal generating means based on the selection of which type of drive signal the signal generating means will generate for which of the plurality of wirings, using the usage frequency information. The inkjet recording apparatus according to any one of claims 5 to 7, characterized by the features described herein.

11. The signal transmission means generates the control signal using the usage frequency information. The inkjet recording apparatus according to feature 10.

12. For each of the aforementioned multiple types of drive signals, a drive signal control table is associated with which the signal waveform is represented by multiple signal values ​​consisting of signal values ​​at predetermined time intervals. The signal transmission means switches the drive signal control table to be used using the frequency of use information. The inkjet recording apparatus according to claim 10 or 11.

13. Regarding the aforementioned multiple types of drive signals, the signal waveform differs for each type. The aforementioned multiple types of drive signals include a first drive signal with a large ink droplet size, a second drive signal with a small ink droplet size, and a third drive signal that does not eject ink. An inkjet recording apparatus according to any one of claims 1 to 12, characterized in that

14. A recording head having a plurality of nozzles for ejecting ink, and a piezoelectric element corresponding to each of the plurality of nozzles, Control means for controlling recording with the recording head, A signal generation means for generating a drive signal for driving the piezoelectric element, For each nozzle, a selection means for selecting one type of drive signal from among the multiple types of drive signals generated by the signal generation means, A plurality of wires for transmitting the plurality of drive signals supplied from the signal generation means to the selection means, A control method for an inkjet recording apparatus having, The plurality of wirings include a first wiring having different wiring widths and capable of carrying the drive current for the maximum simultaneous operation of the piezoelectric elements, and a second wiring having a narrower wiring width than the first wiring and capable of carrying a drive current corresponding to a smaller number of simultaneous operations than the maximum simultaneous operation. The control means controls the signal generation means using frequency information representing the frequency of use of each of the multiple types of drive signals, The control means controls the selection means using the usage frequency information, possess, Features and control methods.

15. A program for causing a computer to perform the method described in claim 14.

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