JP2020142424A - Liquid discharge device, and heat insulation control method of recording head - Google Patents

Abstract

To suppress image irregularity caused by dispersion of a temperature in a recording head.SOLUTION: A liquid discharge device has a heater 220 provided on a recording head 210 for discharging liquid to a recording medium, for heating each discharge port of the recording head 210, a latch signal generating part 230 for generating a latch signal for latching recording data on the recording head 210, and a heating control part 240 for starting the heater 220 based on a heater drive pulse signal for starting the heater 220, and on the latch signal.SELECTED DRAWING: Figure 12

Description

The present invention relates to a heat retention control method for a liquid discharge device and a recording head.

In a recording device equipped with a recording head, maintaining a constant temperature of the recording head during printing is an important issue for suppressing image unevenness and improving image quality. Patent Document 1 describes a control for keeping the recording head warm by supplying a drive pulse having a time width insufficient for generating bubbles in the ink to the heat generation resistance element during non-printing (short pulse heating). The method is described. Further, Patent Document 2 describes a method of controlling the temperature by switching between the heat generation resistance element and the subheater according to the temperature of the recording head or whether printing or non-printing is in progress.

Japanese Unexamined Patent Publication No. 10-16228 Japanese Unexamined Patent Publication No. 5-220965

Mounting a sub-heater for heat retention control of the recording head is a factor of cost increase. On the other hand, it is impossible to control the heat retention of the recording head by short pulse heating using the heat generation resistance element during printing. Therefore, if heat retention control that relies only on short pulse control is adopted, if there is a discharge port that is not used from the start to just before the end of printing, if the discharge port is used just before the end of printing, the temperature near the discharge port will be used. Is considered to be lower than the temperature near other discharge ports. This affects the ink ejection operation and causes image unevenness.

An object of the present invention is to provide a heat retention control method for a liquid discharge device and a recording head that solves the above problems.

The liquid discharge device of the present invention
A recording head provided with a discharge port for discharging a liquid and a heater provided corresponding to each discharge port to generate energy for discharging the liquid.
A latch signal generation unit that generates a latch signal for latching the recorded data on the recording head,
It has a heater control unit that activates the heater based on the heater drive pulse signal for activating the heater and the latch signal.

The heat retention control method of the recording head of the present invention is
A process of generating energy for discharging the liquid at each discharge port of a recording head for discharging the liquid to the recording medium.
A process of generating a latch signal for latching the recorded data on the recording head, and
A process of controlling the generation of the energy is performed based on the heater drive pulse signal for generating the energy and the latch signal.

In the present invention, image unevenness due to temperature variation in the recording head can be suppressed.

It is a perspective view which shows the appearance of the liquid discharge device of this invention. It is a block diagram which shows an example of the internal structure of a recording apparatus. It is a figure which shows one configuration example of the discharge port of a recording head. It is a timing chart for explaining the timing of data transfer which is generally used. It is a timing chart for explaining the timing of the conventional data transfer. It is a circuit diagram which shows the data latch circuit for performing the conventional data transfer. It is a figure which shows the internal structure of the shift register shown in FIG. It is a timing chart for explaining the timing of data transfer to a recording head. It is a circuit diagram which shows the data latch circuit. It is a timing chart for explaining the timing of data transfer to a recording head. It is a circuit diagram which shows the data latch circuit. It is a figure which shows the outline of the liquid discharge device of this invention. It is a flowchart for demonstrating the heat retention control method of a recording head.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the configuration disclosed in the embodiments described below is only one embodiment of the present invention, and the present invention is not limited to the illustrated configuration.

In the present specification, "record" (sometimes referred to as "print") not only indicates that significant information such as characters and figures is formed, but also does not matter whether it is significant or involuntary. Furthermore, "recording" is not limited to whether or not it is manifested so that it can be visually perceived by humans, and images, patterns, patterns, etc. are widely formed on recording media, or the media is processed. It also includes what is shown to be done. Further, in the present specification, the "recording medium" is not limited to paper used in a general recording device, and can widely accept ink such as cloth, plastic film, metal plate, glass, ceramics, wood, and leather. Also included. Furthermore, "ink" (sometimes referred to as "liquid") should be broadly interpreted, as is the definition of "print". Therefore, by being applied onto the recording medium, it is used for forming images, patterns, patterns, etc., processing the recording medium, or processing ink (for example, coagulation or insolubilization of the colorant in the ink applied to the recording medium). It shall represent the liquid that can be served. Further, unless otherwise specified, the "recording element" is collectively referred to as a discharge port, a liquid passage communicating with the discharge port, and a heater that generates energy for discharging ink. Further, although the inkjet recording device described below ejects ink, the present invention can be widely applied to a liquid ejection device that ejects a liquid other than ink.

(First Embodiment)
(Inkjet recording device)
FIG. 1 is a perspective view showing the appearance of an inkjet recording device which is a typical embodiment of the present invention. As shown in FIG. 1, the inkjet recording device (hereinafter referred to as a recording device) 1 mounts an inkjet recording head (hereinafter referred to as a recording head) 3 on a carriage 2 for ejecting ink and recording according to an inkjet method. .. Further, the inkjet recording device 1 reciprocates the carriage 2 in the direction of the arrow A to perform recording. The inkjet recording device 1 feeds a recording medium P such as a recording paper via a paper feeding mechanism 5, conveys the recording medium P to a recording position, and discharges ink from the recording head 3 to the recording medium P at the recording position for recording. To do. The carriage 2 of the recording device 1 is equipped with not only the recording head 3 but also an ink cartridge 6 for storing the ink supplied to the recording head 3. The ink cartridge 6 is detachable from the carriage 2. The recording device 1 shown in FIG. 1 is capable of color recording, and therefore, the carriage 2 contains four types of inks, magenta (M), cyan (C), yellow (Y), and black (K), respectively. It is equipped with four ink cartridges. Each of these four ink cartridges can be attached and detached independently. The recording head 3 in the first embodiment employs an inkjet method that ejects ink by using heat energy. Therefore, the recording head 3 is provided with a heater. This heater is provided corresponding to each discharge port of the recording head 3, and when a pulse voltage corresponding to the recording signal is applied, ink is discharged from the corresponding discharge port. Further, a scale 7 is provided along the moving direction of the carriage 2. The scale 7 is provided with slits at regular intervals, and an encoder (not shown) mounted on the carriage 2 reads the slits in response to the movement of the carriage 2 to generate an encoder signal. This encoder signal is a signal representing the carriage position (that is, the position of the recording head) in the moving direction of the carriage 2. The moving speed of the carriage is calculated based on the period of the encoder signal (encoder signal interval). Further, this encoder signal is used as a signal for timing control for ink ejection.

(Control configuration)
FIG. 2 is a block diagram showing an example of the internal configuration of the recording device 1 shown in FIG. As shown in FIG. 2, the recording device 1 shown in FIG. 1 has a host interface 111, a host device 900, an encoder processing unit 112, an operation panel 113, and an image processing unit 114. Further, as shown in FIG. 2, the recording device 1 shown in FIG. 1 has a print data processing unit 115, a RAM (Random Access Memory) 116, and a CPU (Central Processing Unit) 117. Further, as shown in FIG. 2, the recording device 1 shown in FIG. 1 includes a ROM (Read Only Memory) 118, a recording head control unit 121, and a recording head 3. The host interface 111 inputs image data from the host device 900. This image data is stored in the reception buffer 116A provided in the RAM 116. The image processing unit 114 converts the image data into multi-valued data of the color components of CMYK and stores the image data in the multi-valued data buffer 116B provided in the RAM 116. The print data processing unit 115 converts the multi-valued data into dot data (binary data) and stores it in the dot data buffer 116C. The recording head control unit 121 transfers the binary data stored in the dot data buffer 116C to the recording head 3. The recording head control unit 121 has a function of thinning out binary data in addition to a function of transferring data. The processing in the print data processing unit 115 is synchronized with the heat trigger signal output by the encoder processing unit 112, and the recording head control unit 121 is synchronized with the block trigger signal output by the encoder processing unit 112. The processing is performed according to the transport timing. The operation panel 113 is an operation panel operated by the user to input information to the recording device 1. The CPU 117 performs drive control of the recording element, relative transfer control between the recording element and the recording medium (for example, paper), and the like according to a control program stored in the ROM 118.

(Discharge port configuration)
FIG. 3 is a diagram showing a configuration example of a discharge port of the recording head 3 mounted on the carriage 2 shown in FIG. FIG. 3A shows four recording element rows 102 (rows A, B, C, and D) including a plurality of recording elements (heaters and ejection ports corresponding to the heaters) 103. An example of the arrangement of the discharge port of the head unit 101 provided is shown. As shown in FIG. 3 (A), a plurality of recording elements 103 are arranged along the Y direction, and to explain the portion surrounded by the broken line, the recording elements 103 in columns A to D each other in the Y direction. They are placed in the same position. For example, the dots formed on the recording medium by the ink ejected from the four recording elements at the positions of the broken lines Yn are recorded at the same line positions as each other. Further, the recording element trains 102 are arranged along the X direction (the carriage moving direction corresponding to the arrow A direction in FIG. 1). The image recording of one color component of each color component of YMCK is completed by the four recording element sequences of the head unit 101. Therefore, in order to form a color image using the color image data consisting of the four color components of YMCK, as shown in FIG. 3B, each of the four colors of ink (cyan, magenta, yellow, and black) is supported. Then, the recording head 3 composed of four head units 101 is configured. As shown in FIG. 3C, a plurality of head units 101 may be arranged in the Y direction in order to obtain a recording head having a long recording width. Further, the recording head having a long recording width may be a full-line recording head whose recording width corresponds to the entire width direction of the recording medium. In this case, the relative transport direction of the recording medium with respect to the arrangement direction (Y direction) of the recording elements is the X direction, and the recording element ejects ink from the recording element in accordance with the transport timing while the recording medium is being transported in the X direction. And record.

(Data transfer timing generation)
The commonly used data transfer timing generation will be described below. Here, a method of driving (time-division driving) the print data for one column by dividing it into 16 timings will be described. FIG. 4 is a timing chart for explaining an example of commonly used data transfer timing. From the encoder, the encoder signal (A phase) 401 and the encoder signal (B phase) 402 whose phase is shifted by a quarter cycle are input to the encoder processing unit 112. The encoder processing unit 112 generates a reference pulse 403 at the timing of the rising edge of the encoder signal 401. Subsequently, the encoder processing unit 112 generates a heat trigger signal 404 that is output at intervals of recording resolution by multiplying the generated reference pulse 403. Further, the encoder processing unit 112 generates a block trigger signal 428 by dividing the interval of the heat trigger signal 404 into 16. Data is input to the recording head at the timing of the block trigger signal 428. In this way, by transferring data within the period of the cycle of the block trigger signal 428 generated based on the encoder signal which is the position information of the carriage, recording can be performed at a desired position.

(Data transfer and heater drive)
The data transfer to the conventional recording head will be described below. FIG. 5 is a timing chart for explaining an example of the timing of data transfer to the conventional recording head. Further, FIG. 6 is a circuit diagram showing an example of a data latch circuit for transferring data to a conventional recording head. Data transfer is performed using a latch signal, a CLK (clock) signal, recorded data, and a heater drive pulse as shown in FIG. The recorded data is transferred in synchronization with the CLK signal, and the recorded data is latched by the recording head at the rising edge of the latch signal (timing of t500, t501 and t502). The discharge port is selected based on the latched recorded data, and the discharge operation is performed using the heater drive pulse. As shown in FIG. 6, the recorded data synchronized with the CLK signal is input to the 6-bit shift register 600. Further, the recorded data output from the 6-bit shift register 600 is input to the plurality of 1-bit shift registers 603. The recorded data output from the shift register 600 is latched by using the 6-bit latch register 601 at the rising edge of the latch signal. Further, the recorded data output from each of the shift registers 603 is latched by using each of the plurality of 1-bit latch registers 604. Of the output data of the 6-bit latch register 601, 4-bit data is input to the 16-time division drive decoder 602, and one block of the 16-bit division is selected. The output of AND605, which takes the logical product of the output value of the 1-bit latch register 604 and the inversion of the heater drive pulse, becomes the drive signal of the heater provided at each discharge port. The 16-division driver 606 is a circuit that takes a logical product of the recorded data that is the output of the AND 605 and the 16 outputs of the 16-time division drive decoder 602. The CLK signal shown in FIG. 5 is partially missing, but this is only for convenience of description, and the input CLK signal has no missing teeth. It goes without saying that is ideal (the same applies to the following explanation).

FIG. 7 is a diagram showing the internal configurations of the 1-bit shift register 603 and the 6-bit shift register 600 shown in FIG. As shown in FIG. 7, the 1-bit shift register 603 shown in FIG. 6 causes one flip-flop (hereinafter referred to as DF) to input a CLK signal and data, and causes the input data to rise or fall of the CLK signal. It is a circuit that punches out with and delays by 1 CLK. As shown in FIG. 7, the 6-bit shift register 600 shown in FIG. 6 connects six DFs in series, causes the DF in the first stage to input a CLK signal and data, and also CLKs in the DFs in the second and subsequent stages. Have the signal input. The 6-bit shift register 600 is a circuit that punches out the data input in the front stage at the rising or falling edge of the CLK signal and delays it by 1 CLK.

The data transfer to the recording head, which is the configuration of the present invention, will be described below. FIG. 8 is a timing chart for explaining an example of the timing of data transfer to the recording head of the recording device 1 of the present invention. Further, FIG. 9 is a circuit diagram showing an example of a data latch circuit for transferring data to the recording head of the recording device 1 of the present invention. Data transfer is performed using a latch signal, a CLK signal, recorded data, and a heater drive pulse as shown in FIG. The rising timing of the latch signal here is the timing for latching the recorded data in the recording head, but the falling timing is recorded based on an external setting or a value preset in a register or the like. The head control unit 121 is generated. The same applies to the following description. The recorded data is transferred in synchronization with the CLK signal, and the recorded data is latched by the recording head at the rising edge of the latch signal (timing of T700, T702 and T704). An ejection port (hereinafter, referred to as a first ejection port) for ejecting ink is selected based on the latched recorded data, and the ejection operation is performed using the heater drive pulse. On the other hand, for the discharge port (hereinafter referred to as the second discharge port) that was not selected as the first discharge port based on the recorded data, the section where the signal level of the latch signal is High (T700 to T701, T702). Only ~ T703) is heated according to the heater drive pulse. As shown in FIG. 9, the recorded data synchronized with the CLK signal is input to the 6-bit shift register 800. Further, the recorded data output from the 6-bit shift register 800 is input to the plurality of 1-bit shift registers 803. The recorded data output from the shift register 800 is latched by using the 6-bit latch register 801 at the rising edge of the latch signal. Further, the recorded data output from each of the shift registers 803 is latched by using each of the plurality of 1-bit latch registers 804. Of the output data of the 6-bit latch register 801, 4-bit data is input to the 16-time division drive decoder 802, and one block of the 16-bit division is selected. The output value of the OR807, which is the logical sum of the output value of the 1-bit latch register 804 and the latch signal, and the inversion of the heater drive pulse are input to the AND805, which is the logical product of the output value of the heater. It becomes a drive signal. The 16-division driver 806 is a circuit that takes a logical product of the recorded data that is the output of the AND805 and the 16 outputs of the 16-time division drive decoder 802. The internal configuration of the 1-bit shift register 803 and the 6-bit shift register 800 is the same as the internal configuration of the 1-bit shift register 603 and the 6-bit shift register 600 shown in FIG.

(Latch signal generation circuit)
FIG. 10 is a timing chart for explaining another example of the timing of data transfer to the recording head of the recording device 1 of the present invention. The latch signal generation circuit is provided in the recording head control unit 121 shown in FIG. The latch signal generation circuit generates a latch signal for a short period in which the signal level is High as shown in FIG. 10 when it is not necessary to heat the second ejection port that does not eject ink. On the other hand, the latch signal generation circuit generates a latch signal having a width overlapping the width of the heater drive pulse when heating the second discharge port. The width of the generated latch signal can be dynamically set by using the setting register in the recording head control unit 121 shown in FIG. Further, the temperature of the recording head 3 may be monitored periodically, and the latch signal generation circuit may be a circuit that dynamically generates the width of the latch signal according to the temperature of the recording head 3.

(Second Embodiment)
FIG. 11 is a circuit diagram showing an example of a data latch circuit for transferring data to a recording head according to a second embodiment of the inkjet recording apparatus of the present invention. In addition to the latch signal described in the first embodiment, a second discharge port heating permission signal as shown in FIG. 11 is provided. Then, using this second discharge port heating permission signal, the output signal of the 1-bit latch register 804 is gated 807. In this way, it is also possible to heat the discharge heating means of the second discharge port according to the signal level of the second discharge port heating permission signal and the signal level of the heater drive pulse. For example, a separate second discharge port heating permission signal is provided for each discharge port row, and the discharge heating of the second discharge port is performed according to the signal level of the second discharge port heating permission signal and the signal level of the heater drive pulse. By heating the means, it is possible to control the heating of the second discharge port for each discharge port row. Further, by providing the second discharge port heating permission signal not for each discharge port row but for each discharge port, it is possible to control the heating of the second discharge port in a finer unit. The second discharge port heating permission signal can be set from the outside of the recording device 1.

FIG. 12 is a diagram showing an outline of the internal configuration of the inkjet recording device of the present invention. As shown in FIG. 12, the inkjet recording device 200 of the present invention includes a recording head 210, a heater 220, a latch signal generation unit 230, a heater control unit 240, a thermometer 250, and a discharge port 260. The recording head 210 is for ejecting ink to a recording medium, and corresponds to the recording head 3 shown in FIG. The discharge port 260 discharges the liquid. The heater 220 is provided in the recording head 210 corresponding to each discharge port 260, and generates energy for discharging the liquid. The latch signal generation unit 230 generates a latch signal for latching the recorded data on the recording head 210. Further, the latch signal generation unit 230 may generate a binary latch signal and change the value of the latch signal according to the degree of heating required for the recording head 210. Further, the latch signal generation unit 230 may generate a latch signal based on the setting according to the operation received from the outside of the inkjet recording device 200. The latch signal generation unit 230 may generate latch signals having different timings for each discharge port 260, or may generate latch signals with different timings for each row of discharge ports 260. The heater control unit 240 activates (controls) the heater 220 based on the latch signal generated by the latch signal generation unit 230 and the heater drive pulse signal for activating the heater 220. Specifically, the heater control unit 240 has energy for the heater 220 to discharge the liquid to the recording head 210 at each discharge port 260 based on the heater drive pulse signal and the latch signal generated by the latch signal generation unit 230. Controls the timing of occurrence of. That is, the heater control unit 240 controls the timing at which the heater 220 heats the recording head based on the heater drive pulse signal and the latch signal generated by the latch signal generation unit 230. More specifically, when the signal level of the heater drive pulse is the level for activating the heater 220, the heater control unit 240 activates the heater corresponding to the discharge port for discharging the liquid for recording the recorded data. .. On the other hand, when the latch signal is a predetermined value (for example, the Low level in the example shown in FIG. 8) among the two values, the heater control unit 240 activates the heater 220 at the signal level of the heater drive pulse. The heater 220 corresponding to the discharge port that does not discharge the liquid for recording the recorded data is not activated even if the level is for. The thermometer 250 measures the temperature of the recording head 210. The heater control unit 240 activates the heater 220 based on the heater drive pulse signal, the latch signal generated by the latch signal generation unit 230, and the temperature measured by the thermometer 250. The heater 220 and the discharge port 260 are included in the recording head 3 in the configuration shown in FIG. Further, the latch signal generation unit 230 and the heater control unit 240 are included in the recording head control unit 121 in the configuration shown in FIG.

The heat retention control method of the recording head in the inkjet recording apparatus 200 shown in FIG. 12 will be described below. FIG. 13 is a flowchart for explaining an example of the heat retention control method of the recording head in the inkjet recording apparatus 200 shown in FIG. The latch signal generation unit 230 generates a latch signal for latching the recorded data on the recording head 210 (step S1). Subsequently, the heater control unit 240 controls the heater 220 based on the latch signal generated by the latch signal generation unit 230 (step S2). Specifically, the heater control unit 240 controls the timing of energy generation for the heater 220 to discharge the liquid to the recording head 210 at each discharge port 260 based on the latch signal generated by the latch signal generation unit 230. To do.

As described above, in the present invention, the heating timing of the recording head to the discharge port is controlled for each discharge port based on the latch signal indicating the timing of latching the recording data on the recording head. As a result, by performing short pulse heating on the heater of the ejection port that does not eject ink even during printing, it is possible to control the heat retention of the recording head and suppress image unevenness due to temperature variation in the recording head. It becomes possible.

200 Inkjet recording device 210 Recording head 220 Heater 230 Latch signal generator 240 Heater control unit 250 Thermometer 260 Discharge port

Claims (10)

A recording head provided with a discharge port for discharging a liquid and a heater provided corresponding to each discharge port to generate energy for discharging the liquid.
A latch signal generation unit that generates a latch signal for latching the recorded data on the recording head,
A liquid discharge device having a heater control unit for activating the heater based on a heater drive pulse signal for activating the heater and the latch signal. In the liquid discharge device according to claim 1,
The heater control unit is a liquid discharge device that controls the timing at which the heater heats the recording head based on the heater drive pulse signal and the latch signal. In the liquid discharge device according to claim 1 or 2.
The latch signal generator generates the binary latch signal,
When the signal level of the heater drive pulse is the level for activating the heater, the heater control unit activates the heater corresponding to the discharge port for discharging the liquid for recording the recorded data, and activates the latch. When the signal is a predetermined value among the two values, the discharge port that does not discharge the liquid for recording the recorded data even if the signal level of the heater drive pulse is the level for starting the heater. A liquid discharge device that does not activate the corresponding heater. In the liquid discharge device according to claim 3,
The latch signal generation unit is a liquid discharge device that changes the timing of changing the value of the latch signal according to the degree of heating required for the recording head. In the liquid discharge device according to any one of claims 1 to 4.
It has a thermometer that measures the temperature of the recording head.
The heater control unit is a liquid discharge device that activates the heater based on the heater drive pulse signal, the latch signal, and the temperature measured by the thermometer. In the liquid discharge device according to any one of claims 1 to 5.
The latch signal generation unit is a liquid discharge device that generates the latch signal based on an external setting. In the liquid discharge device according to any one of claims 1 to 6.
The latch signal generation unit is a liquid discharge device that generates different latch signals for each discharge port. In the liquid discharge device according to claim 1,
The heater control unit is based on a heater drive pulse signal for activating the heater, a latch signal, and a heating permission signal for permitting heating to a discharge port that does not discharge liquid for recording the recorded data. A liquid discharge device that activates the heater. In the liquid discharge device according to claim 8,
When the signal level of the heater drive pulse is a level for activating the heater, the heater control unit activates the heater corresponding to the discharge port for discharging the liquid for recording the recorded data, and heats the heater. When the permission signal is a predetermined value, even if the signal level of the heater drive pulse is the level for activating the heater, the heater corresponding to the discharge port that does not discharge the liquid for recording the recorded data. Liquid discharge device that does not start. A process of generating energy for discharging the liquid at each discharge port of a recording head for discharging the liquid to the recording medium.
A process of generating a latch signal for latching the recorded data on the recording head, and
A heat retention control method for a recording head that performs a process of controlling the generation of energy based on a heater drive pulse signal for generating the energy and a latch signal.

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