JP2010069792A - Head driving device and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent faulty recording caused by indefinite factors such as mismatching when generating waveform data, data corruption when transferring, and malfunction of a circuit. <P>SOLUTION: The head driving device includes: a waveform data output means (124) which outputs waveform data of driving voltage for operating a pressure generating element corresponding to each nozzle of an inkjet head (110) having the plurality of nozzles; an image data transmitting means (121) which transmits image data for controlling ejection of each nozzle to the inkjet head (110); and a monitoring means (160) which monitors output timing of amplitude data of the waveform data relative to transmission timing of the image data and outputs error information when the output timing is waveform timing that does not fulfill a specified condition. For example, it monitors whether or not drive voltage is bias voltage within a predetermined time with a latch signal as reference. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a head driving device and an ink jet recording apparatus, and more particularly to a head driving device suitable for driving a piezoelectric element corresponding to each nozzle in an ink jet head having a plurality of nozzles, and an ink jet recording apparatus using the head driving device.

  In Patent Document 1, in order to prevent clogging of nozzles in an ink jet recording apparatus, the number of times ink droplet ejection is continuously stopped is monitored for each nozzle based on print data, and the number of pauses is the specified number of times. A configuration is disclosed that includes a data monitoring circuit that minutely vibrates the ink meniscus by applying a minute signal to the piezoelectric vibrator corresponding to the nozzle that has reached.

Also, in Cited Document 2, the current pulse width applied to the heating element of the recording head in a thermal printer or an ink jet printer is changed according to the operating environment temperature or the characteristics of the heating element, and the electric energy applied to the heating element is changed. As for the technology of the energization pulse width control (heat PWM control) to be adjusted, a configuration is disclosed in which the pulse width of the energization pulse is measured, and this is compared with a predetermined threshold value to notify a recording abnormality.
JP 11-314360 A Japanese Patent Application Laid-Open No. 08-224876

  Generally, in an on-demand type multi-nozzle inkjet printer, image data (print data) for controlling ejection (ON) / non-ejection (OFF) of nozzles in a head and ejection pressure generating elements (piezoelectric elements) for each nozzle are provided. Printing is performed by ejecting ink by applying a driving voltage to the head.

  At the time of printing, the transfer of image data from the head drive circuit to the head and the transfer of amplitude data of the drive waveform are started at the same time, but in order to print desired image data, the amplitude of the drive waveform for ejecting ink is It must be after image data has been transferred.

  FIG. 12 shows the timing chart. (A) shows transfer of image data, (b) shows a latch signal (= DATA Latch) for setting image data in the nozzle, and (c) shows a drive voltage applied to the piezoelectric element corresponding to the nozzle. As shown in the figure, the drive waveform voltage needs to be in a stable state (= bias voltage) within the hold time from the latch signal and the setup time before the latch signal with reference to the latch signal. .

  However, if the voltage waveform cannot be kept stable for the specified setup / hold time due to uncertain causes such as inconsistencies during data generation, data destruction during transfer, or circuit malfunctions, the print quality will be significantly reduced. This is inconvenient for the system. Regarding such problems, Patent Documents 1 and 2 do not present any solution.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an ink-jet head driving apparatus and an ink-jet recording apparatus using the same that can prevent a recording defect caused by an uncertain factor.

  In order to achieve the above object, the present invention provides a waveform data output means for outputting waveform data of a driving voltage for operating a pressure generating element corresponding to each nozzle of an inkjet head having a plurality of nozzles, and discharging each nozzle. When the image data transmitting means for transmitting image data for control to the inkjet head and the output timing of the amplitude data of the waveform data with respect to the transmission timing of the image data are monitored and the waveform timing does not satisfy the prescribed condition There is provided a head driving device comprising monitoring means for outputting error information.

  According to the present invention, it is possible to check the consistency between the transfer timing of image data and the timing of waveform data, and it is possible to prevent a recording failure caused by an uncertain factor.

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

[Overall configuration of inkjet recording apparatus]
First, an example of an ink jet recording apparatus to which the present invention is applied will be described. FIG. 1 is a schematic diagram showing an overall configuration of an inkjet recording apparatus 10 according to an embodiment of the present invention. As shown in the figure, an inkjet recording apparatus 10 includes a plurality of inkjet heads (hereinafter referred to as heads) provided corresponding to black (K), cyan (C), magenta (M), and yellow (Y) inks. A printing unit 12 having 12K, 12C, 12M, and 12Y, an ink storage / loading unit 14 that stores ink to be supplied to each head 12K, 12C, 12M, and 12Y, and a recording paper 16 that is a recording medium. The paper feeding unit 18 to be supplied, the decurling unit 20 for removing the curl of the recording paper 16, and the nozzle surfaces of the heads 12K, 12C, 12M, and 12Y are arranged so as to maintain the flatness of the recording paper 16. The suction belt conveyance unit 22 that conveys the recording paper 16, the print detection unit 24 that reads the printing result of the printing unit 12, and the paper discharge that discharges the recorded recording paper (printed material) to the outside. It is provided with a 26, a.

  The ink storage / loading unit 14 has an ink supply tank that stores inks of colors corresponding to the heads 12K, 12C, 12M, and 12Y. The inks of the respective colors are supplied to the heads 12K, 12C, 12M and 12Y communicate with each other.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20.

  After the decurling process, the recording paper 16 cut to a predetermined size by the cutter 28 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least nozzle surfaces of the heads 12K, 12C, 12M, and 12Y (ink discharge surfaces on which nozzle openings are formed). ) Is configured to form a horizontal surface (flat surface).

  The belt 33 has a width that is wider than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, an adsorption chamber 34 is provided at a position facing the nozzle surfaces of the heads 12K, 12C, 12M, and 12Y inside the belt 33 spanned between the rollers 31 and 32. The recording paper 16 is sucked and held on the belt 33 by sucking the chamber 34 with the fan 35 to obtain a negative pressure. Instead of the suction (negative pressure) suction method, an electrostatic suction method may be adopted.

  The power of the motor (not shown in FIG. 1 and indicated by reference numeral 88 in FIG. 6) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, so that the belt 33 rotates clockwise in FIG. , And the recording paper 16 held on the belt 33 is conveyed from left to right in FIG.

  A belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the printing area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blowing method of spraying clean air, or a combination thereof.

  The heads 12K, 12C, 12M, and 12Y of the printing unit 12 have a length corresponding to the maximum paper width of the recording paper 16 that is the target of the inkjet recording apparatus 10, and the nozzle surface has at least a recording medium of the maximum size. This is a full-line head in which a plurality of nozzles for ejecting ink are arranged over a length exceeding one side (the entire width of the drawable range) (see FIG. 2). Each of the heads 12K, 12C, 12M, and 12Y is fixedly installed so as to extend along a direction substantially orthogonal to the conveyance direction of the recording paper 116.

  A color image can be formed on the recording paper 16 by discharging different color inks from the heads 12K, 12C, 12M, and 12Y while transporting the recording paper 16 by the suction belt transporting section 22.

  As described above, according to the configuration in which the full-line heads 12K, 12C, 12M, and 12Y having nozzle rows that cover the entire width of the paper are provided for each color, the recording paper 16 and the printing unit 12 are relatively disposed in the paper feeding direction. An image can be recorded on the entire surface of the recording paper 16 by performing the moving operation only once (that is, by one sub-scan). With such a configuration capable of single-pass printing, high-speed printing is possible and productivity can be improved as compared with a shuttle-type head in which the head reciprocates in a direction orthogonal to the paper conveyance direction.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink color and number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add an ink jet head that discharges light ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

  Each of the heads 12K, 12C, 12M, and 12Y may have a structure in which a plurality of head modules are connected in the width direction of the recording paper 16, or each head has a structure formed integrally. It may be.

  The print detection unit 24 provided at the subsequent stage of the printing unit 12 includes an image sensor (imaging device) for imaging the droplet ejection result of the printing unit 12, and nozzle clogging and the like from the droplet ejection image read by the image sensor It functions as a means for checking discharge abnormality. The print detection unit 24 reads the test patterns printed by the heads 12K, 12C, 12M, and 12Y of the respective colors, and detects ejection of the heads 12K, 12C, 12M, and 12Y. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes. Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

[Head structure]
Next, the structure of the head will be described. Since the structures of the color-specific heads 12K, 12C, 12M, and 12Y are common, the heads are represented by the reference numeral 50 in the following.

  FIG. 3A is a plan perspective view showing an example of the structure of the head 50, and FIG. 3B is an enlarged view of a part thereof. 3C is a perspective plan view showing another example of the structure of the head 50, and FIG. 4 is a diagram showing a droplet discharge element for one channel (an ink chamber unit corresponding to one nozzle 51) serving as a recording element unit. It is sectional drawing (sectional drawing in alignment with line 4-4 in Fig.3 (a)) which shows a three-dimensional structure.

  In order to increase the dot pitch printed on the recording paper 16, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 3A and 3B, the head 50 of this example includes a plurality of ink chamber units (nozzles 51, which are ink droplet ejection holes, and pressure chambers 52 corresponding to the nozzles 51). It has a structure in which the droplet discharge elements 53 are arranged in a matrix (two-dimensionally), thereby projecting so as to be aligned along the longitudinal direction of the head 50 (main scanning direction orthogonal to the paper feed direction). High density of the substantial nozzle interval (projection nozzle pitch) is achieved.

  The form in which one or more nozzle rows are configured over a length corresponding to the entire width of the recording paper 16 in the main scanning direction substantially orthogonal to the feeding direction of the recording paper 16 is not limited to this example. For example, instead of the configuration of FIG. 3A, as shown in FIG. 3C, short head units 50 ′ in which a plurality of nozzles 51 are two-dimensionally arranged are arranged in a staggered manner and connected. Thus, a line head having a nozzle row having a length corresponding to the entire width of the recording paper 16 may be configured. Although not shown, a line head may be configured by arranging short head units in a row.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and an outlet to the nozzle 51 is provided at one of the diagonal corners, and the supply ink is provided at the other. Inflow port (supply port) 54 is provided. The shape of the pressure chamber 52 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon and other polygons, a circle, and an ellipse.

  The pressure chamber 52 communicates with the common flow channel 55 through the supply port 54. The common channel 55 communicates with an ink supply tank (not shown) as an ink supply source, and the ink supplied from the ink supply tank is distributed and supplied to each pressure chamber 52 via the common channel 55.

  A piezoelectric element 58 having individual electrodes 57 is joined to a diaphragm 56 that constitutes a part of the pressure chamber 52 (the top surface in FIG. 4) and also serves as a common electrode. By applying a drive voltage between the individual electrode 157 and the common electrode, the piezoelectric element 58 is deformed to change the volume of the pressure chamber 52, and ink is ejected from the nozzle 51 due to the pressure change accompanying this.

  When ink is ejected, new ink is supplied (refilled) from the common flow channel 55 through the supply port 54 to the pressure chamber 52.

  As shown in FIG. 5, the ink chamber unit 53 having such a structure is latticed in a fixed arrangement pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape.

  That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected in the main scanning direction is d × cos θ. Thus, in the main scanning direction, the nozzles 51 can be handled substantially equivalently to those in which the nozzles 51 are linearly arranged at a constant pitch P.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the sub-scanning direction can be applied.

[Explanation of control system]
FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, a memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, and the like.

  The communication interface 70 is an interface unit (image input means) that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. The image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the memory 74.

  The memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 72 controls each part such as the communication interface 70, the memory 74, the motor driver 76, the heater driver 78, etc., performs communication control with the host computer 86, read / write control of the memory 74, etc. A control signal for controlling the system motor 88 and the heater 89 is generated.

  The ROM 75 stores programs executed by the CPU of the system controller 72 and various data necessary for control (including ejection waveform data for image formation and ejection waveform for idle driving). The ROM 75 may be a non-rewritable storage means, or may be a rewritable storage means such as an EEPROM.

  The memory 74 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 76 is a driver that drives the motor 88 in accordance with instructions from the system controller 72. In FIG. 6, the motor 88 arranged in each part in the apparatus is represented by reference numeral 88.

  The heater driver 78 is a driver that drives various heaters 89 including the heater of the post-drying unit 42 shown in FIG. 1 in accordance with instructions from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the memory 74 in accordance with the control of the system controller 72. The generated print data This is a control unit that supplies (dot data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the head 50 are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  An overview of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 70 and stored in the memory 74. At this stage, for example, RGB multi-valued image data is stored in the memory 74.

  The original image (RGB) data stored in the memory 74 is sent to the print control unit 80 via the system controller 72, and the print control unit 80 uses the halftoning process using a threshold matrix, error diffusion method, etc. It is converted into dot data (binary data or multi-value data including dot size information) for each color (K, C, M, Y).

  Thus, the dot data generated by the print control unit 80 is stored in the image buffer memory 82. The dot data for each color is converted into CMYK droplet ejection data for ejecting ink from the nozzles of the head 50, and the ink ejection data to be printed is determined.

  The head driver 84 is a drive signal for driving the piezoelectric elements 58 corresponding to the respective nozzles 51 of the head 50 based on print data (that is, dot data stored in the image buffer memory 82) given from the print control unit 80. Is output. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  The ink jet recording apparatus 10 shown in this example applies a common drive waveform signal to each piezoelectric element 58 and turns on / off the switch element connected to the individual electrode of each piezoelectric element 58 according to the ejection timing of each piezoelectric element 58. By switching, the driving method of the piezoelectric elements 58 that discharge ink from the nozzles corresponding to the piezoelectric elements 58 is applied.

  When a drive signal output from the head driver 84 is applied to the head 50, ink is ejected from the corresponding nozzle 51. An image is formed on the recording paper 16 by controlling the ink ejection from the head 50 while conveying the recording paper 16 at a predetermined speed.

  As described above, based on the ink discharge data and the drive signal waveform generated through the required signal processing in the print control unit 80, control of the discharge amount and discharge timing of the ink droplets from each nozzle via the head driver 84. Is done. Thereby, a desired dot size and dot arrangement are realized.

  As described with reference to FIG. 1, the print detection unit 24 is a block including an image sensor, reads an image printed on the recording paper 16, performs necessary signal processing, etc. And the detection result is provided to the print controller 80 and the system controller 72.

  The print control unit 80 performs various corrections on the head 50 based on information obtained from the print detection unit 24 as necessary, and performs cleaning operations (nozzle recovery operation) such as preliminary ejection, suction, and wiping as necessary. Perform the controls to be implemented.

[Configuration of head drive unit]
FIG. 7 is a block diagram showing a basic configuration of a head control system in the ink jet recording apparatus according to the present embodiment.

  In FIG. 7, reference numeral 110 denotes a head module (corresponding to an “inkjet head”) that constitutes a recording head of one ink color. A line head capable of single-pass printing with a recording width corresponding to the maximum paper width is configured by arranging and connecting a plurality of head modules 110 in the paper width direction.

  Each head module 110 is provided with a corresponding head drive circuit 120. The head drive circuit 120 includes an image memory 121 (corresponding to “image data transmitting means”), an image control circuit 122 (corresponding to “latch signal output means”), a waveform memory 124 (corresponding to “waveform data output means”), D / A converter 126 and amplifier 128 are comprised.

  The image memory 121 stores image data expanded into print image data.

  The image control circuit 122 generates a latch signal for setting image data for ink ejection to the nozzles of the head module 110. The data latch timing is set to a predetermined cycle (for example, cycle T = 40 μs), and a latch signal is given from the image control circuit 122 to the head module 110 at a constant cycle.

  The waveform memory 124 stores digital data of a drive voltage waveform for driving the piezoelectric element. When the waveform data is output from the waveform memory 124 to the D / A converter 126 in accordance with the print timing signal input from the outside, the D / A converter 126 converts the waveform data into an analog voltage waveform. . The output waveform (analog voltage waveform) of the D / A converter 126 is amplified to a predetermined current / voltage suitable for driving the piezoelectric element by the amplifier 128 and then supplied to the head module 110.

  As shown in FIG. 8, in the head module 110, image data for determining opening / closing (ejection / non-ejection) of the nozzles is received from the image memory 121 (see FIG. 7), and the above-described image data is input by inputting a latch signal pulse. A control IC 112 that controls the opening and closing of the nozzle by transferring image data to each nozzle is provided, and a transmission path 116 that transmits a drive voltage to the piezoelectric element portion (shown as 114 in FIG. 8) of the nozzle is further provided. Yes.

  A drive voltage is applied to each nozzle piezoelectric element (see reference numeral 58 in FIG. 4) with respect to the nozzles opened and closed by the input image data and latch signal, so that the piezoelectric elements 58 for the opened nozzle portion. Due to the deformation, the liquid is discharged from the nozzle.

  Although not shown in FIG. 7, the head drive circuit 120 corresponding to each head module 110 has the same configuration. The plurality of head drive circuits 120 are connected to a common control circuit 140 and operate under the control of the control circuit 140. That is, the plurality of head modules 110 are simultaneously controlled by the control circuit 140.

  The control circuit 140 is configured by a programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The control circuit 140 communicates with the host CPU 152 via a predetermined communication port to acquire printing image data and various control signals. The communication method between the host CPU 152 and the control circuit 140 is not particularly limited, and various communication interfaces such as RS232C, LVDS, and CAN can be applied.

  At the time of printing, image data transfer and drive waveform amplitude data transfer from the head drive circuit 120 to the head module 110 are started in the internal circuit of the control circuit 140. As described with reference to FIG. In order to print desired image data, it is necessary that the amplitude of the drive waveform for ejecting ink (the portion of the amplitude data indicated by reference numeral 190 in FIG. 12) is after the transfer of the image data.

  The waveform data used in the head drive circuit 120 is managed by the host CPU 152, transferred to the waveform memory 124 of the head drive circuit 120 at the time of device shipment and system maintenance (repair / maintenance), and stored therein. Is done.

  The waveform data output from the waveform memory 124 to the D / A converter 126 in response to a print timing signal input from the outside during printing is usually a setup time based on the latch signal described with reference to FIG. And satisfying the condition for a stable state (bias voltage) during the hold time period. In FIG. 12, the digital value of the bias voltage (the value input to the D / A converter 126) is “Hff” (hexadecimal notation), and the digital value of the peak value of the drive voltage waveform is “H00” (hexadecimal). Notation).

  However, it is assumed that normal waveform data is not output to the D / A converter 126 due to indeterminate factors such as inconsistency in the data creation stage, data destruction during communication, and malfunction of the control circuit 140. There are concerns about the impact.

  In addition, when the above problem occurs, a function for monitoring the consistency of waveform data is required for cause analysis.

  In order to solve such a problem, in the circuit of this embodiment, in addition to the configuration of FIG. 7, as shown in FIG. 9, a monitoring circuit 160 is provided in the control circuit 140 to monitor the output of the waveform memory 124 and the latch signal. Input to the circuit 160. In this way, the waveform data input as a digital value to the D / A converter 126 is acquired in real time by the monitoring circuit 160, thereby checking the consistency of the waveform data with the latch signal.

  That is, the control circuit 140 acquires information on the bias voltage value, information on the hold time, and information on the setup time from the host CPU 152 in advance, and stores these information in the storage units 162, 163, and 164. The monitoring circuit 160 acquires the bias voltage value information, the hold time information, and the setup time information set in the storage units 162 to 164, and acquires the latch signal and the waveform data output from the waveform memory 124. The consistency of the waveform data is determined. If the waveform timing is incorrect, error information is output to the host CPU 152.

  In FIG. 9, only one head module 110 is representatively shown. However, as described in FIG. 7, the plurality of head modules 110 and the head drive circuit 120 corresponding to each of the head modules 110 have the same configuration as in FIG. Yes.

  FIG. 10 is a flowchart of processing for monitoring the consistency of waveform data.

  After predetermined initial processing is performed and a print standby (standby) state is set (step S210), parameters are set in the monitoring circuit 160 (step S212). That is, information indicating the values of the bias voltage, setup time, and hold time necessary for monitoring and determining the waveform timing is acquired from the host CPU 152. The host CPU 152 can change the values of these parameters as needed. Parameters can be set for each head module 110.

  For example, in FIG. 12, when the period of the latch signal is 40 μs, the hold time is set to 10 μs, the setup time is set to 10 μs, and the bias voltage value “Hff” (hexadecimal notation) is set. Both the setup time and the hold time are defined by a relative time (time difference) from the latch signal based on the latch signal. The time length of the setup time and the hold time may be the same or different values.

  After step S212 in FIG. 10, the printing process is actually started, and the monitoring circuit 160 detects the latch signal (step S214). The latch signal is transferred, and monitoring is started at that timing, and the process proceeds to step S216. In step S216, it is determined whether or not the value of the drive voltage data sent from the waveform memory 124 to the D / A converter 126 within the hold time is equal to the bias voltage value.

  When the drive voltage data within the hold time is different from the bias voltage (when No is determined), it is an incorrect waveform timing. In this case, error notification processing (step S220) is performed, and an error is notified to the host CPU 152. To do. The host CPU 152 performs control to stop printing upon receiving an error notification.

  On the other hand, if it is determined in step S216 that the drive voltage data within the hold time is equal to the bias voltage, it is determined that the waveform is normal, and the process proceeds to step S218. In step S218, whether or not the value of the drive voltage data sent from the waveform memory 124 to the D / A converter 126 within the specified time (setup time) before the next latch signal is transferred is equal to the bias voltage value. Make a decision.

  If the drive voltage data within the set-up time is different from the bias voltage (when No is determined), the waveform timing is incorrect. In this case, the process proceeds to step S220, and an error is notified to the host CPU 152. As a result, printing is stopped and the process ends (step S222).

  On the other hand, if it is determined in step S218 that the drive voltage data within the setup time is equal to the bias voltage, it is determined that the waveform is normal, and the process proceeds to step S224.

  In step S224, it is determined whether or not printing has been completed. If it has not been completed (printing is in progress) (when No is determined), the process returns to step S214 and the above processing (steps S214 to S224) is repeated.

  When printing is completed and a Yes determination is made in step S224, the process ends (step S226).

  7 to 9, the head for one color has been described. However, in the ink jet recording apparatus 110 having a plurality of color heads, the same configuration is adopted for each color head.

  That is, as shown in FIG. 11, host CPUs 152_C, 152_M, 152_Y, and 152_K are provided for each color, and a higher-level host job controller 180 that integrates these is provided. In FIG. 11, suffixes “_C”, “_M”, “_Y”, and “_K” indicating the distinction of CMYK ink colors are added to elements that are the same as or similar to the configurations shown in FIGS. 7 to 9. The same reference numerals are used.

  The host CPUs 152, 152_C, 152_M, 152_Y, and 152_K described in FIGS. 7, 9, and 11 correspond to the “print control unit” in FIG. 6, and the host job controller 180 in FIG. Is equivalent to. Further, the combination of the control circuit 140 shown in FIGS. 7 and 9 and the head drive circuit 120 connected thereto corresponds to a “head drive device”.

  As described above, according to the embodiment of the present invention, the reliability of the waveform data is improved by monitoring the image data and the ink ejection waveform data sent to the print head in real time during printing.

[Modification]
In the above embodiment, an ink jet recording apparatus of a method (direct recording method) in which an ink droplet is directly formed on the recording paper 16 has been described. However, the scope of application of the present invention is not limited to this, and once, The present invention is also applied to an intermediate transfer type image forming apparatus that forms an image (primary image) on an intermediate transfer member and transfers the image onto a recording sheet in a transfer unit to form a final image. be able to.

  Further, in the above embodiment, an inkjet recording apparatus using a page-wide full-line head having a nozzle row having a length corresponding to the entire width of the recording medium (single-pass image for completing an image by one sub-scanning). However, the scope of application of the present invention is not limited to this, and an inkjet that performs image recording by scanning a plurality of heads while moving a short recording head such as a serial (shuttle scan) head. The present invention can also be applied to a recording apparatus.

  In addition, the interpretation of the term “inkjet recording device” is not limited to the use of so-called graphic printing such as photographic printing and poster printing, but is a resist printing device using an inkjet method, a wiring drawing device for an electronic circuit board, and a fine structure formation. An apparatus for industrial use that can form a pattern that can be grasped as an image, such as an apparatus, is also included.

[Appendix]
As will be understood from the description of the embodiments of the invention described in detail above, the present specification includes disclosure of various technical ideas including the invention described below.

  (Invention 1): Waveform data output means for outputting waveform data of a driving voltage for operating a pressure generating element corresponding to each nozzle of an inkjet head having a plurality of nozzles, and image data for controlling ejection of each nozzle Monitoring means for monitoring the output timing of the amplitude data of the waveform data with respect to the transmission timing of the image data, and outputting error information when the waveform timing does not satisfy a prescribed condition And a head driving device.

  As a pressure generating element, there are an aspect using a piezoelectric element that deforms a pressure chamber and an aspect using a heat generating element in a thermal jet system.

  The error information is notified to the host device or the like of the host, and control such as stopping the recording operation (print processing) is possible.

  (Invention 2): The head driving device according to Invention 1, further comprising a storage unit for storing a parameter for determining the specified condition, wherein the setting of the specified condition can be changed by changing the parameter. apparatus.

  It is desirable that the parameter that defines the “specified condition” that is a determination condition for error determination can be arbitrarily variably set as necessary. For example, the configuration is such that the parameters are variably set by the host device (host CPU) of the host.

  (Invention 3): The head drive device according to Invention 2, wherein the parameter is set with a timing for monitoring the waveform data and a drive voltage value.

  Specifically, for example, the waveform data is monitored for a predetermined time period from the latch signal, and it is determined whether or not the drive voltage value within the predetermined time is equal to the bias voltage.

  (Invention 4): The head driving device according to any one of Inventions 1 to 3, further comprising a latch signal output means for outputting a latch signal for determining a latch timing of image data corresponding to each of the nozzles; Is a condition that the drive voltage is a bias voltage within a predetermined time with reference to the latch signal.

  In this case, a value that defines a predetermined time (hold time or setup time) based on the latch signal and a bias voltage value are set in the storage means.

  (Invention 5): An ink jet recording apparatus comprising the head driving device according to any one of Inventions 1 to 4, and simultaneously controlling a plurality of the ink jet heads.

  As a configuration example of a print head (recording head) used in an ink jet recording apparatus, a full-line type head having a nozzle row in which a plurality of discharge ports (nozzles) are arranged over a length corresponding to the entire width of the recording medium is used. it can. In this case, a combination of a plurality of relatively short head modules having nozzle rows that are less than the length corresponding to the full width of the recording medium, and connecting them together, the nozzle row having a length corresponding to the full width of the recording medium as a whole. There is an aspect that constitutes.

  The plurality of head modules can be controlled simultaneously by a common monitoring circuit.

  The full-line type head is usually arranged along a direction orthogonal to the relative feeding direction (relative conveyance direction) of the recording medium. There may be a mode in which the head is disposed along an oblique direction with an angle.

  A “recording medium” is a medium (which can be called a printing medium, an image forming medium, a recording medium, an image receiving medium, a discharged medium, etc.) that receives adhesion of liquid droplets discharged from the discharge port of the head, and is continuous. Paper, cut paper, sealing paper, resin sheets such as OHP sheets, films, cloth, printed circuit boards on which wiring patterns are formed, intermediate transfer media, and other various media and shapes are included.

  The transporting means for moving the recording medium and the head relative to each other includes a mode for transporting the recording medium to the stopped (fixed) head, a mode for moving the head with respect to the stopped recording medium, or a head and recording Any aspect of moving both of the media is included. In addition, when forming a color image using an ink jet print head, a head may be arranged for each color of a plurality of inks (recording liquids), and a plurality of colors of ink can be ejected from one recording head. It is good also as a simple structure.

1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of a main part around a printing unit of the inkjet recording apparatus shown in FIG. Plane perspective view showing structural example of head Sectional view along line 4-4 in FIG. Enlarged view of the nozzle arrangement shown in FIG. 1 is a block diagram showing the configuration of a control system of the ink jet recording apparatus shown in FIG. Block diagram showing the basic configuration of the head control system Head module configuration diagram 1 is a circuit block diagram showing a configuration of a head driving device according to an embodiment of the present invention. Flowchart of processing for monitoring the consistency of waveform data with image data Explanatory drawing of a configuration having multiple color heads Image data transfer, latch signal, drive waveform timing chart

Explanation of symbols

  12K, 12C, 12M, 12Y, 50 ... head, 58 ... piezoelectric element, 72 ... system controller, 80 ... print controller, 110 ... head module, 120 ... head drive circuit, 121 ... image memory, 122 ... image control circuit, 124 ... Waveform memory, 126D / A converter, 128 ... Amplifier, 140 ... Control circuit, 152 ... Host CPU, 160 ... Monitoring circuit, 162, 163, 164 ... Storage unit

Claims (5)

Waveform data output means for outputting waveform data of a driving voltage for operating a pressure generating element corresponding to each nozzle of an inkjet head having a plurality of nozzles;
Image data transmitting means for transmitting image data for controlling ejection of each nozzle to the inkjet head;
Monitoring means for monitoring the output timing of the amplitude data of the waveform data relative to the transmission timing of the image data, and outputting error information when the waveform timing does not satisfy a prescribed condition;
A head driving device comprising: The head drive device according to claim 1,
A head driving apparatus comprising: a storage unit that stores a parameter that defines the prescribed condition; and the setting of the prescribed condition can be changed by changing the parameter. The head drive device according to claim 2,
A head driving apparatus characterized in that a timing for monitoring the waveform data and a driving voltage value are set as the parameters. In the head drive unit according to any one of claims 1 to 3,
Latch signal output means for outputting a latch signal for determining the latch timing of image data corresponding to each nozzle,
The head drive apparatus according to claim 1, wherein the specified condition is a condition that the drive voltage is a bias voltage within a predetermined time with the latch signal as a reference. A head driving device according to any one of claims 1 to 4, comprising:
An inkjet recording apparatus that controls a plurality of the inkjet heads simultaneously.

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