JP2022067468A - Ink jet recording device - Google Patents

Abstract

To provide a constitution which can execute an aging recovery operation at appropriate timing.SOLUTION: An ink jet recording device comprises: a recording head which has a plurality of nozzles, utilizes heat energy generated in a heater element and can discharge ink via the plurality of nozzles; a temperature sensor which can detect the temperature of the recording head; and a control unit which can control the drive of the heater element. The control unit can execute: an image formation operation (printing) of causing the recording head to discharge ink to a recording material by driving the heater element in the first output; and aging recovery processing of causing the recording head to discharge the ink by driving the heater element in the second output larger than the first output on the basis of the discharge frequency (discharge number) of the plurality of nozzles. When the temperature detected by the temperature sensor is higher at the termination of a printing job of performing image formation in the image formation operation by a command, the control unit makes the timing of executing the aging recovery processing earlier than a case where the temperature is low.SELECTED DRAWING: Figure 10

Description

The present invention relates to an inkjet recording device that forms an image by ejecting ink from a plurality of nozzles.

The technique of executing a discharge drive (second mode) different from the discharge drive for recording (first mode) called aging recovery processing is known in order to remove the scorching (burnt) adhering to the discharge heater (heating element). Has been done. The execution timing of this aging recovery process is determined based on the cumulative (cumulative) number of discharges for each recording head (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-030931

Here, the higher the temperature at the time of discharge, the larger the amount of kogation that adheres tends to be. However, in Patent Document 1, since the timing of the aging recovery process (second mode) is determined only by the number of times of ink ejection for each recording head, there is a possibility that the aging recovery process cannot be performed at an appropriate timing.

An object of the present invention is to provide a configuration capable of executing a second mode (aging recovery process) at an appropriate timing.

INDUSTRIAL APPLICABILITY The present invention has a plurality of nozzles, uses heat energy generated by a heat generating element, ejects ink through the plurality of nozzles, and a temperature detecting means capable of detecting the temperature of the ejected portion. In the first mode in which the drive of the heat generating element can be controlled and the heat generating element is driven by the first output to eject ink to the recording material to the ejection unit, and the number of ejections of the plurality of nozzles. Based on the above, the control means is provided with a control means capable of executing a second mode in which the heat generating element is driven by a second output larger than the first output to discharge ink to the ejection unit. Is characterized in that the timing of executing the second mode is earlier than the case where the temperature detected by the temperature detecting means is lower at the end of the image forming job that forms an image in the first mode by a command. And.

INDUSTRIAL APPLICABILITY The present invention has a plurality of nozzles, uses heat energy generated by a heat generating element, ejects ink through the plurality of nozzles, and a temperature detecting means capable of detecting the temperature of the ejected portion. And, the drive of the heat generating element can be controlled, and the first mode in which the heat generating element is driven by the first output to discharge the ink to the recording material to the ejection unit is larger than the first output. The control means is provided with a control means capable of executing a second mode in which the heat generating element is driven by the second output and the ink is ejected to the ejection unit, and the control means has the plurality of nozzles, each of the plurality of nozzles. The ejection detected by the temperature detecting means at the end of the image forming job for forming an image in the first mode by a command when the nozzles are divided into a plurality of nozzle groups composed of a number of nozzles smaller than the number of nozzles. Based on the temperature of the unit and the number of ejections for each of the plurality of nozzles in the image forming job, the number of ejections for each of the plurality of nozzles is higher than that when the temperature of the ejection portion is higher. The cumulative number of ejections was accumulated for each of the plurality of nozzle groups, and the cumulative value of the number of ejections exceeded the first value in at least one of the plurality of nozzle groups. In this case, the second mode is executed for the nozzles of the nozzle group having a second value or more in which the cumulative value of the number of ejections is smaller than the first value among the plurality of nozzle groups. It is characterized by.

INDUSTRIAL APPLICABILITY The present invention has a plurality of nozzles, uses heat energy generated by a heat generating element, ejects ink through the plurality of nozzles, and a temperature detecting means capable of detecting the temperature of the ejected portion. The first mode, in which the drive of the heat generating element can be controlled and the heat generating element is driven by the first output to eject ink to the recording material, and the first output based on the user's command. A control means capable of driving the heat generating element with a second output larger than the second mode to eject ink to the ejection portion, and an image forming job for forming an image in the first mode by a command. Each of the plurality of nozzles is provided with a storage unit for storing the number of ejections for each of the plurality of nozzles and the temperature of the ejection unit detected by the temperature detecting means at the end of the image forming job, and the control means is said to have the same. When a plurality of nozzles are divided into a plurality of nozzle groups each composed of a number of nozzles smaller than the number of the plurality of nozzles, the storage unit stores the plurality of nozzles when the second mode is executed according to a user command. Based on the temperature of the ejection portion and the number of ejections for each of the plurality of nozzles, the number of ejections for each of the plurality of nozzles is larger than that for the case where the temperature of the ejection portion is higher. The number of ejections is accumulated for each of the plurality of nozzle groups, and among the plurality of nozzle groups, the nozzles of the nozzle group whose cumulative value of the number of ejections is equal to or greater than the first predetermined value. However, the second mode is executed.

According to the present invention, the aging recovery process can be executed at an appropriate timing.

Schematic sectional view of the inkjet recording apparatus according to the first embodiment. The schematic diagram for demonstrating the operation of the apparatus main body of the inkjet recording apparatus which concerns on 1st Embodiment. The schematic diagram which shows the structure about the aging recovery process around the recording head which concerns on 1st Embodiment. The schematic diagram which shows the structure of the recording head which concerns on 1st Embodiment. Partial sectional view around the nozzle of the recording head which concerns on 1st Embodiment. (A) The figure which shows the double pulse applied to the heat generating element. (B) The figure which shows the single pulse applied to a heating element. The control block diagram of the inkjet recording apparatus which concerns on 1st Embodiment. The figure which compared continuous printing and intermittent printing. The figure which shows the cumulative number of discharges which the image defect occurs for each head temperature. The flowchart regarding the aging recovery process in 1st Embodiment. The table which shows the table A for determining the drive pulse condition used at the time of printing. A table showing table B for operations related to weighting. A table showing table C for recording weighted cumulative points. The figure which shows the cumulative point for each nozzle and the execution area of the aging recovery process. A table showing a table D showing the frequency of the drive pulse according to the number of execution regions of the aging recovery process. The table which shows the table E for determining the drive pulse condition used at the time of an aging recovery process. (A) The figure which shows the print quality image before the aging recovery process in 1st Embodiment. (B) The figure which shows the print quality image after the aging recovery process in 1st Embodiment. (A) Flow chart showing the print job in the second embodiment (b) Flow chart showing the aging recovery process in the second embodiment. The table which shows the table F for recording the cumulative number of discharges in 2nd Embodiment.

<First Embodiment>
The first embodiment will be described with reference to FIGS. 1 to 17. First, the inkjet recording apparatus 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of the inkjet recording apparatus 1 according to the present embodiment. In the present embodiment, the main body 1A of the inkjet recording device 1 is equipped with a recording head unit 30a as an ejection unit capable of ejecting ink by utilizing the thermal energy generated by the heat generating element.

In this specification, "record" (sometimes referred to as "print") is not limited to the case of forming significant information such as characters and figures, and may be significant or involuntary. Furthermore, regardless of whether or not it is manifested so that it can be visually perceived by humans, it also represents the case where an image, a pattern, a pattern, etc. is widely formed on a recording medium or the medium is processed. In addition, "recording material" (sometimes referred to as "sheet") is not limited to paper used in general storage devices, but is also widely used for cloth, plastic film, metal plates, glass, ceramics, wood, leather, etc. It shall also represent what is acceptable for ink.

Furthermore, "ink" (sometimes referred to as "liquid") should be broadly construed as in the definition of "print" above. 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 a liquid that can be used.

[Inkjet recording device]
As shown in FIG. 1, such an inkjet recording apparatus 1 includes an apparatus main body 1A and a feeding unit 10. The feeding section 10 has a housing section 10a for accommodating the roll sheet P and a pair of feeding rollers 10b. The roll sheet P built in the accommodating portion 10a is supplied to the apparatus main body 1A by rotationally driving the pair of feeding rollers 10b. Further, the apparatus main body 1A has a transport unit 20 capable of transporting the roll sheet P, an image forming unit 30, a recovery unit 40, and a control unit 50 as a control means (see FIG. 7).

The transport unit 20 transports the roll sheet P transported from the feed unit 10 to the image forming unit 30, and sequentially transports the roll sheet P after image formation to the outside of the machine via the discharge port 1E. The image forming unit 30 performs an image forming operation as a first mode on the conveyed roll sheet P. The recovery unit 40 performs a recovery operation such as an aging recovery process as a second mode, which will be described later, so that the image forming unit 30 can stably form an image. The control unit 50 controls the operation of each configuration of the inkjet recording device 1, such as the feeding unit 10, the transport unit 20, the image forming unit 30, and the recovery unit 40. Hereinafter, a specific description will be given.

First, the transport unit 20 will be described in detail with reference to FIG. The transport unit 20 includes a transport belt 20a on which a roll sheet P is placed and transported, a roller 20b on which the transport belt 20a is stretched, and a roller 20c arranged at positions facing each other with the roller 20b and the transport belt 20a interposed therebetween. And have.

The conveyor belt 20a is rotationally driven by the conveyor motor 20d. The roller 20c can be transported while sandwiching the roll sheet P to be transported between the roller 20c and the transport belt 20a. Further, the roller 20c is a region of the surface on which the roll sheet P of the transport belt 20a is placed, which is deviated from the recording region where ink is ejected from the recording head unit 30a to the upstream side and the downstream side of the roll sheet P in the transport direction X. Is located in.

In the transport portion 20, the upstream roller 20c and the transport belt 20a can form an upstream nip portion, and the downstream roller 20c and the transport belt 20a can form a downstream nip portion. The transport section 20 sandwiches the roll sheet P fed from the feed section 10 between the upstream nip section and the downstream nip section, and transports the roll sheet P in the transport direction X indicated by the arrow in the figure to form an image. Transport to section 30.

Next, the image forming unit 30 will be described in detail with reference to FIGS. 1 and 2. FIG. 2 is a schematic diagram for explaining the operation of the inkjet recording apparatus according to the present embodiment. As shown in FIG. 1, the image forming unit 30 has a recording head unit 30a and ink tanks 30dK, 30dC, 30dM, and 30dY. Further, as shown in FIG. 2, the recording head unit 30a is provided at a position facing the transport surface for transporting the roll sheet P of the transport belt 20a. The recording heads 30aK, 30aC, 30aM, and 30aY, which will be described later, each have a built-in heat generating element group, and the ink is heated by the heat energy generated by the heat generating element, so that the ink can be ejected from the nozzle. be.

Further, it is the ink tanks 30dK, 30dC, 30dM, and 30dY of the above-mentioned colors shown in FIG. 1 that supply ink to the four recording heads 30aK, 30aC, 30aM, and 30aY. The ink tanks 30dK, 30dC, 30dM, and 30dY are arranged below the transport belt 20a in the apparatus main body 1A.

Further, it is connected to the recording head 30A1 of the corresponding color by a flexible tube or the like (not shown), and is configured to be able to supply ink of each color. The recording head 30aK corresponds to an ink tank 30dK, the recording head 30aC corresponds to an ink tank 30dC, the recording head 30aM corresponds to an ink tank 30dM, and the recording head 30aY corresponds to an ink tank 30dY. The details of the four recording heads 30aK, 30aC, 30aM, and 30aY will be described later.

As shown in FIG. 2, the roll sheet P that has been transported while being placed on the transport belt 20a reaches a position facing the recording head unit 30a. Then, the recording head unit 30a moves relative to the opposite roll sheet P, and in accordance with the received print data, black ink (Bk), cyan ink (C), magenta ink (M), and yellow ink. Ink is ejected in the order of (Y). As a result, the recording head unit 30a records the image as the first mode. The roll sheet P on which the image is recorded is conveyed to the discharge side by the transport belt 20a, and is aligned and discharged by a discharge guide (not shown) provided in the discharge port 1E, and is folded. ..

[Recovery section]
Next, the recovery unit 40 will be described in detail with reference to FIGS. 1 to 3. FIG. 3 is a schematic diagram showing a configuration related to an aging recovery process described later around the recording head according to the first embodiment. As shown in FIG. 3, the recovery unit 40 includes a recovery tub member 40a as a covering member, a waste liquid tank member 40b capable of accommodating waste ink (waste liquid), and a pump (not shown). As will be described later, the plurality of nozzles are formed with ejection ports capable of ejecting ink, and the recovery tub member 40a prevents exposure of the ejection ports of the plurality of nozzles of the standby recording head unit 30a. Therefore, it is possible to closely cover the discharge ports of a plurality of nozzles.

Further, the recovery tub member 40a has a holding member 40a1 capable of holding ink as shown in FIG. In other words, the holding member 40a1 capable of holding the ink ejected from the ejection port covered with the recovery tub member 40a is provided in the recovery tub member 40a. In the inkjet recording apparatus 1 according to the present embodiment, during the aging recovery process as the second mode, the recording heads 30aK, 30aC, 30aM, and 30aY ink the holding member 40a1 of the recovery tub member 40a by the heat energy of the heat generating element. Is discharged.

In other words, when the aging recovery process is executed, the control unit 50 drives the heat generating element to cover the recording head unit 30a with the recovery tub member 40a, and then to the holding member 40a1 via the discharge port 30aK2 described later. Ink is ejected.

Further, the recording heads 30aK, 30aC, 30aM, and 30aY can remove the kogation accumulated on the heater by using the cavitation by the bubbles generated by the heater heating in the aging recovery process. At this time, the ink I accumulated in the recovery tub member 40a is sucked into the waste liquid tank member 40b by a pump at the lower position of the recovery tub member 40a so that the ink does not overflow or scatter outside the recovery tub member 40a. to be sending.

[Recording head unit]
Next, the recording head unit 30a will be described in more detail with reference to FIGS. 4 and 5. FIG. 4 is a schematic diagram showing the configuration of the recording head unit 30a according to the first embodiment. FIG. 5 is a cross-sectional view of the recording head unit 30a according to the first embodiment, in which the periphery of the nozzle is partially broken. As shown in FIG. 4, the recording head unit 30a has a configuration in which the recording head 30aK, the recording head 30aC, the recording head 30aM, and the recording head 30aY are arranged from the upstream side with respect to the transport direction X.

The recording head 30aK ejects black ink (K), the recording head 30aC ejects cyan ink (C), the recording head 30aM ejects magenta ink (M), and the recording head 30aY ejects yellow ink (Y). ) Is discharged. The four recording heads 30aK, 30aC, 30aM, and 30aY are all in contact with each other, and there is no gap between them.

Further, the recording heads 30aK, 30aC, 30aM, and 30aY each have a heating element group (heater group) 30bK, 30bC, 30bM, 30bY as a recording element. The heat generating element group (heater group) 30bK, 30bC, 30bM, and 30bY are provided in a plurality of nozzles of the recording heads 30aK, 30aC, 30aM, and 30aY, respectively.

For example, as shown in FIG. 5, a heat generating element 30bK1 of the heat generating element group 30bK is provided inside the nozzle 30aK1 of the plurality of nozzles of the recording head 30aK, and the heat generating element 30bK1 is driven to discharge the heat. Ink is ejected from the outlet 30aK2. Further, as shown in FIG. 4, temperature sensors 30cK, 30cC, 30cM, 30cY as a temperature detecting means capable of detecting the temperature in the recording head unit 30a at positions close to the heat generating element groups 30bK, 30bC, 30bM, 30bY. Is provided. The temperature sensors 30cK, 30cC, 30cM, and 30cY are, for example, diode sensors.

The heat generating element is a kind of recording element in the inkjet recording apparatus. The recording element is an actuator associated with one discharge port, and includes various types such as a heater and a piezo element. In other words, in the present embodiment, a heat generating element which is a heater is used as the recording element, and in each recording head 30aK, 30aC, 30aM, 30aY, the recording elements are arranged at intervals of, for example, 1200 dpi.

Further, a sub-heater for assisting heat generation may be provided for each heat generating element group 30bK, 30bC, 30bM, 30bY. Further, in the present embodiment, one temperature sensor is provided for the heat generating element group, but a plurality of sensors may be provided. For example, one temperature sensor may be provided for one heat generating element.

[Drive pulse applied to heat generating element]
Next, the drive pulse applied to the heat generating element will be described with reference to FIGS. 6A and 6B. FIG. 6A is a diagram showing a double pulse 501 applied to a heat generating element when ink is ejected to the recording head. FIG. 6B is a diagram showing a single pulse 502 applied to the heat generating element when the ink is ejected to the recording head. As the drive pulse applied to the heat generating element, the double pulse 501 shown in FIG. 6A or the single pulse 502 shown in FIG. 6B is adopted. In the present embodiment, a double pulse is adopted as the drive pulse during normal printing and the drive pulse during aging recovery processing.

The application times T1 and T3 of the drive pulse during normal printing are determined with reference to the discharge pulse table shown in FIG. 11, and T2 is fixed at 1860 ns. The energy of these drive pulses during normal printing is designed with a discharge coefficient of 1.2 as the first output. On the other hand, the application times T1 and T3 of the drive pulse during the aging recovery process are determined with reference to the aging pulse table shown in FIG. T2 is fixed at 1860 ns as in normal printing. The energy of the drive pulse during these aging recovery processes is designed with a discharge coefficient of 1.45 as the second output.

In other words, the control unit 50 can control the drive of the heat generating element, and the heat generating element is driven by the first output to form an image as a first mode in which the recording head unit 30a ejects ink to the roll sheet P. The operation is feasible. Further, the recording heads 30aK and 30aC are driven by a second output larger than the first output based on the number of ejections of the plurality of nozzles described later. It is possible to execute the aging recovery process as the second mode in which the ink is ejected to 30aM and 30aY. The discharge coefficient can be obtained by the following formula.

Top indicates the energy application time obtained by adding T1 and T3, and Tth indicates the minimum single pulse width at which ink droplets start to be ejected. Since the ejection coefficient K differs depending on the color and type of ink (dye, pigment) and the recording head, it is preferable to design each time.

For the recovery operation such as the aging recovery process, the nozzle is formed by ejecting ink to the recovery tub member 40a, sucking it into a pump (not shown), and sending it to the waste liquid tank member 40b, as in the aging recovery process called preliminary ejection. There is an operation to discharge the thickened ink inside. However, the preliminary ejection uses the ejection coefficient of the drive pulse of 1.2 at the time of normal printing, which is an operation different from the aging recovery processing. In addition, while the discharge energy applied in the preliminary discharge is the same as in the normal recording, in the aging recovery process, the pulse length (ON time) is made longer than in the normal printing, so that the drive used in the aging recovery process is used. I try to give the pulse more energy.

[Control unit]
Next, the control unit 50 according to the first embodiment will be described with reference to FIG. 7. FIG. 7 is a control block diagram of the inkjet recording device 1 according to the present embodiment. The control unit 50 includes a CPU 50a, an image memory 50b, a program ROM 50c, a work RAM 50d, an EEPROM 50e, an input / output port 50f, an output port 50g, a host interface 50h, a head drive circuit 50i, a recording head temperature detection unit 50j, and a point calculation unit 50k. .. The CPU 50a receives recorded data from the host computer 80 via the host interface 50h.

The recorded data is temporarily expanded and stored in the image memory 50b with a recorded image having a predetermined size. After the deployment is completed, the CPU 50a drives an actuator (not shown) such as a drive motor of each of the feeding unit 10, the transport unit 20, and the image forming unit 30 via the output port 50g, and forms an image by a command. Start the recording operation in the print job as a formation job. The CPU 50a starts reading the image memory 50b, sequentially transfers the recording data to the recording heads 30aK, 30aC, 30aM, and 30aY via the head drive circuit 50i, and causes the roll sheet P to perform color recording.

When recording, the drive conditions applied to the heat generating element are determined based on the temperature detected by the recording head temperature detecting unit 50j. These series of operations are executed by the CPU 50a based on the control program stored in the program ROM 50c. The CPU 50a uses the work RAM 50d as a work memory required for its execution. In addition to this, the control unit 50 is connected to the operation panel 70 for inputting various commands and data, the EEPROM 50e, the feeding unit 10 and the sensors 60 for detecting the transport state of the roll sheet P in the transport unit 20. ing.

Here, at the time of printing, the number of ejected dots (number of ejections) is counted for each of the recording heads 30aK, 30aC, 30aM, and 30aY, and the point calculation unit 50k stores the accumulated points in the EEPROM 50e as the storage unit. Written. note that. Such an EEPROM 50e may be configured to be provided in each recording head 30aK, 30aC, 30aM, 30aY.

[Relationship between head temperature and kogation deposit]
Next, the relationship between the head temperature and the amount of kogation deposited will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram comparing the case of continuous printing and the case of intermittent printing in order to investigate the relationship between the head temperature and the image defect. FIG. 9 is a diagram showing the results of investigating the number of ejections in which image defects occur for each head temperature.

In FIG. 8, intermittent printing indicates a case in which intermittent printing is performed one by one over time, and continuous printing indicates a case in which continuous printing is performed at one time. Both printed images (601) use the same magenta image. Comparing the head temperature (602) when the printed image (601) is repeatedly printed, it can be seen that the head temperature during printing is higher in the continuous printing. 603 in the figure shows a state when a halftone (25% Duty) image is printed after printing a total of 10,000 sheets and a printing defect (rubbing condition) is checked.

Although the cumulative number of dots is the same for both intermittent printing and continuous printing, the degree of rubbing is more noticeable in continuous printing. Therefore, printing at a higher temperature is more likely to cause printing defects, and the heat generating element is burnt. It can be seen that it is easy to deposit. In addition to the number of sheets to be continuously printed, the factors of such an increase in the head temperature include the outside air temperature and the content, that is, the density of the image to be printed. For example, if the image has a low density, the number of ejections is small, so that the head temperature does not easily rise. On the contrary, if the image has a high density, the number of ejections increases and the head temperature tends to rise.

From the above, it can be seen that kogation accumulates faster when printing at a higher temperature. Here, in the present embodiment, the timing of the aging recovery process and the driving conditions of the heat generating element are set based on the temperatures of the recording heads 30aK, 30aC, 30aM, and 30aY detected by the temperature sensors 30cK, 30cC, 30cM, and 30cY. I have decided. Specifically, weighting is performed so that the higher the detection temperature, the earlier the timing of performing the aging recovery process according to the detection temperature.

In other words, the control unit 50 advances the timing of executing the aging recovery process when the temperature detected by the temperature sensors 30cK, 30cC, 30cM, and 30cY at the end of the print job is higher than when the temperature is lower. Further, when a plurality of print jobs are executed, the control unit 50 advances the timing of executing the aging recovery process when the average value of the temperatures detected at the end of the plurality of print jobs is higher than when the average value is lower.

Specifically, the numerical value for the weighting calculation for each nozzle shown in FIG. 12 is determined based on the table in which the number of defects for each head temperature shown in FIG. 9 is investigated. Here, FIG. 9 is a table summarizing the results of investigating the number of ejections in which image defects occur by performing continuous printing with a plurality of patterns in which the head temperature is changed. In FIG. 9, ◯ indicates an image in which the density is not reduced and the quality is OK, Δ indicates an image in which the density is slightly decreased but the quality is OK, and × indicates the image in which the density is decreased and the quality is OK. An image that is NG is shown.

[Control flow of aging recovery processing according to the first embodiment]
Next, the control flow of the aging recovery process according to the first embodiment will be described with reference to FIGS. 10 to 17. FIG. 10 is a flowchart relating to the aging recovery process according to the first embodiment. FIG. 11 is a table A for determining the conditions of the drive pulse at the time of printing.

T1 and T3 in FIG. 11 indicate the pulse widths of the two pulses in the double pulse shown in FIG. 6 (a). The recording head provided in the inkjet recording apparatus 1 is divided into a plurality of ranks based on the information for correcting the variation in the resistance value of the recording head. The “Head Rank” indicates the rank, and the inkjet recording apparatus 1 can know the rank from, for example, the information of the mounted recording head.

“Temp” indicates that the temperature is within the recording heads 30aK, 30aC, 30aM, and 30aY detected by the temperature sensors 30cK, 30cC, 30cM, and 30cY, and is lower than the numerical value in each column. For example, "<15 ° C." indicates that the temperature inside the recording head is less than 15 ° C. As a way of reading the table, the drive pulse width is determined by referring to the table corresponding to the corresponding rank and temperature of each recording head.

FIG. 12 is a table B in which weighting values for performing weighting operations on the number of discharges are listed. “Detected temperature” in FIG. 12 indicates the temperature (TEMP) in the recording heads 30aK, 30aC, 30aM, 30aY detected by the temperature sensors 30cK, 30cC, 30cM, 30cY.

For example, "15 ° C. ≤ TEMP <25 ° C." indicates that the temperature in the recording heads 30aK, 30aC, 30aM, and 30aY is 15 ° C. or higher and lower than 25 ° C. When the detected temperature is in this range, the weighting value is "1.020" in the same row, and the weighting operation can be performed according to the calculation formula described at the bottom of the table. FIG. 13 is a table C for recording the numerical values after the weighting calculation in FIG. The area of FIG. 13 is divided into 324 groups of a plurality of nozzles of the recording head as a group of nozzles, and as will be described later, the cumulative points of each area are stored in the table of FIG.

FIG. 14 is a diagram showing a graph in which cumulative points for each region are plotted and an implementation region of the determined aging recovery process. The horizontal axis of the graph shown in FIG. 14 indicates the position of the region in the nozzle row, and the vertical axis indicates the cumulative number of points in each region. Further, a point cloud in which cumulative points are plotted, a default point as a first value for determining the aging recovery processing timing, and a second value for determining an aging recovery processing execution area or a default point as a predetermined number of times × A straight line indicating 1/2 and each are marked. Later, the timing of the aging recovery process and the determination of the implementation area will be described using this graph.

FIG. 15 is a table D showing the frequencies of drive pulses set according to the number of regions to be subjected to the aging recovery process. The “number of aging regions” in FIG. 15 indicates the upper limit of the number of regions for which the aging recovery process has been determined, and the lower limit can be determined from the upper limit value shown in the left column. For example, the column "~ 144" indicates that the number of implementation areas is 109 to 144 because the table on the left side of the column is described as "~ 108". The "frequency (Hz)" is the frequency of the drive pulse applied during the aging recovery process. For example, when the number of implementation regions is in the range of 109 to 144, the frequency of the applied aging pulse is 3000 Hz.

FIG. 16 is a table E for determining the conditions of the drive pulse during the aging recovery process, and is the same as FIG. 11. FIGS. 17A and 17B are diagrams showing print quality images before and after the aging recovery process according to the present embodiment for normal printing (halftone printing), and FIGS. 17A and 17B are halftone images before the aging recovery process. An image is shown, and (b) shows a halftone image after the aging recovery process.

The aging recovery process will be specifically described with reference to FIG. First, the power of the inkjet recording device 1 is turned on (S1). When the print job (image forming job) is received (S2), the aging flag information of each recording head 30aK, 30aC, 30aM, 30aY is read (S3). Check ON / OFF of the aging flag from the read information (S4). When the aging flag is not set (OFF) (S4: NO), the head temperature is acquired (S5), and the discharge pulse table A shown in FIG. 11 is referred to (S6). Based on the head temperature acquired in S5, the ejection pulse condition is determined as the printing condition (S7), and the received image data is printed (S8).

At the end of the print job, the temperature of the heat generating element (temperature detected by the temperature sensors 30cK, 30cC, 30cM, 30cY as the temperature detecting means) is acquired (S9), and the number of ejections (number of ejections) of each nozzle is acquired. Do (S10). Next, by referring to the point calculation table B shown in FIG. 12, the acquired number of ejections for each nozzle is weighted and the points are calculated (S11).

That is, the control unit 50 has a higher head temperature based on the head temperature detected by the temperature sensors 30cK, 30cM, 30cC, and 30cY at the end of the print job and the number of ejections for each of the plurality of nozzles of the print job. Weighting is performed so that the number of ejections for each of a plurality of nozzles is larger than that when the number is low. The number of discharges with this weighting is the point of each region described below.

The calculated points are recorded in the point calculation table C shown in FIG. 13 (S12). Here, the calculation in S11 is performed by dividing a plurality of nozzles into regions as a nozzle group. 16 heat generating elements are assigned to each region handled in FIG. 13. That is, the group of 5184 heat generating elements of one recording head is divided into 324 regions for calculation and recording.

In other words, the control unit 50 divides the plurality of nozzles into a plurality of regions each composed of a number of nozzles smaller than the number of the plurality of nozzles, and accumulates points for each region. This is because when the temperature, the number of discharges, and the points are dealt with one by one, the processing speed and the recording capacity are imminent. If there is a margin in the capacity of the CPU, RAM, and ROM, points may be handled for each heat generating element.

Subsequently, it is determined whether or not the accumulated points have reached the specified points as the first value (S13). In other words, it is determined whether or not there is an area where the accumulated points have reached the specified points. In the present embodiment, the specified point is set to 1,000,000, but it is preferable to set it according to the ink to be used and the recording head. When the above-mentioned specified points are exceeded (S13: YES), a region having a point of 1/2 or more (second value or more) of the specified points is detected (S14).

A state in which the implementation area of the aging recovery process is determined from the cumulative points for each nozzle will be described with reference to FIG. In FIG. 14, the cumulative points of each region recorded in S12 as described above are plotted on the graph. Further, the default point for determining the aging recovery process is shown by the straight line 1201. When the plotted points are above the straight line 1201, it is determined that the accumulated points have reached the predetermined points.

Further, a second value corresponding to 1/2 of the specified point shown by the straight line 1201, or a point as a predetermined number of times is shown by the straight line 1202. In this case, the area where the plotted cumulative points exceed the specified points shown by the straight line 1202 is determined to be the area where the aging recovery process is performed. In FIG. 14, since it is located between the vertical line L and the vertical line R, the nozzle in the area corresponding to the cumulative point in the range surrounded by the vertical line L and the vertical line R is determined as the aging recovery processing target (S15). ).

In other words, at the timing of executing the aging recovery process, the aging recovery process is executed for the area where the total number of ejections of the weighted nozzles is equal to or more than the predetermined point among the plurality of areas, and for the other areas. , Do not perform aging recovery processing.

It should be noted that the target of the aging recovery process is the heat generating element having a point of 1/2 or more of the specified point, as shown in FIG. 9, the heat generating element whose quality is OK but the concentration is lowered. This is because the aging recovery process is performed. However, the threshold value for determining the processing target does not have to be 1/2 of the default point. For example, it may be 1/3 of the default point or may be the default point.

Next, referring to the aging frequency table D shown in FIG. 15 (S16), the frequency of the aging recovery processing is determined based on the number of aging recovery processing target areas, the aging flag is set (S17), and then the print job is waited for. Return to (S18). That is, when the default point is reached in S13, the aging flag is set, so that the aging recovery process is executed at the start of the next print job, as will be described later.

In other words, when the cumulative value of the number of discharges (cumulative points) exceeds the first value (default point) in at least one of the plurality of areas, the second value (predetermined number of times) among the plurality of areas , The aging recovery process as the second mode is executed for the nozzles in the area of 1/2) or more of the default points.

Further, the drive frequencies shown in the aging frequency table D shown in FIG. 15 are numerical values increased or decreased according to the number of aging recovery processing regions. This is because the temperature inside the head changes according to the number of aging recovery processing areas, and the temperature inside the head changes, so that the effect of removing char from the aging recovery processing is not reduced, so the drive frequency is adjusted. Therefore, the head temperature is adjusted to a temperature suitable for the aging recovery process. The temperature inside the head changes according to the number of aging recovery processing regions because the number of heaters that generate heat increases as the aging recovery processing region increases.

Further, just as the deposit of kogation changes depending on the head temperature during printing, the effect of removing kogation also changes depending on the head temperature during the aging recovery process. Specifically, there is a temperature suitable for aging recovery treatment having a high effect of removing kogation, and when the temperature exceeds a certain level, kogation removal tends to be difficult. This is because if the head temperature becomes too high, small bubbles are connected in the head to form large bubbles that block the nozzle, and normal ejection cannot be performed. In the present embodiment, the head temperature at the time of normal recording is 40 to 50 ° C., and the optimum temperature for the aging recovery treatment is 60 ° C. During the aging recovery process, the drive conditions are set so as to reach this optimum temperature.

The discharge frequency is the number of heatings per second. The higher the discharge frequency, the higher the temperature on the heater during the aging recovery process, while the lower the discharge frequency, the lower the temperature on the heater. The head temperature is adjusted by adjusting. For example, if the aging recovery processing area increases, the number of heaters that generate heat increases even if discharge is performed at the same frequency, and the head temperature rises. Therefore, it is necessary to lower the frequency by that amount. In FIG. 15, as the aging recovery processing area increases, the discharge frequency is set to decrease by the increased amount.

In other words, the control unit 50 can reduce the drive output of the heat generating element by reducing the frequency of the voltage applied to the heat generating element. Further, when the aging recovery process is executed, the frequency of the voltage applied to the heat generating element is made smaller than that in the case where the number of the regions for which the aging recovery process is executed is large among the plurality of regions.

On the other hand, if the aging flag is set at the time of confirming the aging flag (S4) (S4: YES), the mode shifts to the aging recovery processing mode (S19). After acquiring the head temperature (S20), the aging pulse table E shown in FIG. 16 is referred to (S21), the drive pulse conditions T1 and T3 of the aging recovery process are determined (S22), and the aging recovery process is executed (S23). ). As described above, T2 is fixed at 1860 ns.

In this embodiment, as shown in FIGS. 11 and 16, the application time T1 of the pulse preheated to stabilize the foaming and the time T2 for transferring the heat to the ink are set to normal recording and aging. The same conditions are used for recovery processing. Therefore, the discharge energy is adjusted by the application time T3 of the pulse for foaming. However, as long as the foaming at T3 can be stabilized, T1 and T2 at the time of normal recording and at the time of aging recovery processing may be set differently. Further, T2 does not have to be 1860 ns as long as the heat of the pulse applied in T1 is sufficiently transferred to the ink.

Further, although not shown in the flowchart, control may be performed such that the head temperature is acquired and the drive pulse condition is updated at regular intervals during the aging recovery process. Further, the number of ejections discharged from the nozzles subject to the aging recovery treatment during the aging recovery treatment of the present invention is 1,200,000, but it is preferably optimized according to the specifications of each ink, the recording head, or the printer main body.

After the aging recovery process, the aging flag is released (S24), the point value of the area where the aging recovery process is performed is reset (S25), and then the printing operation after S5 is performed. Here, as shown in FIG. 17, when the improvement of the image defect by the aging recovery treatment according to the present embodiment is confirmed, the density blur (a) before the aging recovery treatment is improved and the density blur (a) before the aging recovery treatment is improved (b). You can see that. From the above, in the inkjet recording apparatus 1 of the present embodiment, the aging recovery process is executed at an appropriate timing by accelerating the timing of executing the aging recovery process when the temperature by the temperature sensor is high at the end of the print job as compared with the case where the temperature is low. Can be confirmed that can be executed.

<Second embodiment>
Hereinafter, the second embodiment will be described with reference to FIGS. 18A to 19. FIG. 18A is a flowchart showing control regarding a print job according to the second embodiment. FIG. 18B is a flowchart showing the control regarding the aging recovery process in the second embodiment. FIG. 19 is a table F for recording the number of discharges and the cumulative number of discharges for each head temperature in the second embodiment.

In the first embodiment, the point calculation is performed for each print job, but in the second embodiment, the point calculation is performed after the transition to the aging recovery processing mode. Further, in the first embodiment, the flag of the aging recovery process is confirmed during the print job, and if the flag is set, the aging recovery process mode is automatically shifted, but in the second embodiment, the user operates. To shift to the aging recovery processing mode. Since other configurations and operations are the same as those of the first embodiment described above, the same reference numerals are given to the same configurations, and explanations and illustrations are omitted or simplified. I will mainly explain the differences.

[Control flow of aging recovery processing according to the second embodiment]
First, the control of the print job and the aging recovery process in the second embodiment will be described with reference to the flowchart. First, the control related to the print job will be described. As shown in the flowchart of FIG. 18A, after printing (S8) is completed, the result of temperature acquisition (S9) and the result of ejection number acquisition (S10) are recorded in the dot number management table F shown in FIG. (S26).

As shown in FIG. 19, in the dot number management table F, the number of dots (number of ejections) in each region is recorded for each temperature, and the calculation result of the cumulative dot count value in each region is recorded. Next, it is determined whether the cumulative number of dots has reached 800,000, which is the specified dot count number as the second predetermined value (a value larger than the first predetermined value described later) (S27). If it has not been reached (S27: NO), the process returns to the print job waiting state (S18). If it has reached (S27: YES), a notification (notification of information that the second mode should be executed) is given to the host computer 80 as a notification means (notification of information that the second mode should be executed), and a print job is waited for. Return to the state (S18).

The user who received the notification by the host computer 80 (see FIG. 7) transmits an execution command of the aging recovery process to the control unit 50 via the host computer 80 and the operation panel 70 (see FIG. 7). Upon receiving the command, the control unit 50 executes the aging recovery processing mode described later. In other words, the control unit 50 stores the number of ejections for each of the plurality of nozzles for each print job in the EEPROM 50e as a storage unit. Further, the temperature of the heat generating element at the end of the print job (temperature detected by the temperature sensors 30cK, 30cC, 30cM, 30cY as the temperature detecting means) is also stored in the EEPROM 50e.

Further, the inkjet recording device 1 according to the present embodiment includes a host computer 80 capable of notifying the user of information. When the cumulative value of the number of discharges stored in the EEPROM 50e exceeds the predetermined dot count number as the second predetermined value, the control unit 50 notifies the host computer 80 to recommend the aging recovery process as predetermined information. To notify the user. The specified dot count number is determined based on the result of FIG.

As described above, the flowchart shown in FIG. 18B starts when the user of the inkjet recording apparatus 1 of the present embodiment orders the execution of the aging recovery process via the host computer 80, and enters the aging recovery process mode. Transition (S29). That is, the control unit 50 according to the second embodiment drives the heat generating element with a second output larger than the first output based on a user's command, and causes the recording head unit 30a to eject ink. Recovery processing can be executed.

With reference to the dot number management table F shown in FIG. 19 (S30), the acquired dot number is weighted based on the table of FIG. 12 so that the higher the temperature, the larger the numerical value. (S11, S12). After detecting a region having a point of 1/2 or more of the maximum point as the first predetermined value (S31), an aging recovery process is performed according to the flow (S22).

In other words, when the control unit 50 executes the aging recovery process according to the user's command, the control unit 50 of the recording head unit 30a is based on the temperature of the recording head unit 30a stored in the EEPROM 50e and the number of ejections for each of the plurality of nozzles. Weighting is performed so that the number of ejections for each of a plurality of nozzles is larger than that when the temperature is high, and the number of ejections is accumulated for each of a plurality of regions (nozzle group). Then, based on the cumulative value of the weighted discharge counts, the nozzles in the region where the cumulative discharge count value is ½ or more (first predetermined value or more) of the maximum point among the plurality of regions are recovered from aging. Execute the process (second mode). After that, the default dot counter value is reset (S32), and the process ends.

From the above, according to the present embodiment, it is possible to remove the deposit of koge at an appropriate timing more in line with the actual state of deposit of koge, and it is possible to effectively suppress the image defect due to the koge. Further, by collectively performing the weighting calculation at the time of the aging recovery process, it is possible to reduce the processing time in a normal print job.

If the software (program) that realizes the functions of the above-described embodiment can be executed, the control unit 50 of the inkjet recording device 1 does not need to have the software (program). For example, an inkjet recording device may be connected to an external device such as a server having software or various storage media having software via a network, and the program may be read and executed by the system itself. good. Alternatively, the program may be read and executed by a computer (or CPU, MPU, etc.) of the inkjet recording device.

Further, in the first embodiment and the second embodiment, the determination of the execution of the aging recovery process is made during the print job, but the points are calculated for each paper spacing, and when the specified value is reached, the print job is performed. May be interrupted and the aging recovery process may be performed. However, since the aging recovery process takes time and there is a possibility that the density and color of the image may change before and after the aging recovery process, rather than interrupting the print job and performing the aging recovery process, after the print job is completed. It is preferable to perform aging recovery treatment.

1 ... Inkjet recording device / 30aK, 30aC, 30aM, 30aY ... Recording head (discharge part) / 30aK1 ... Nozzle / 30aK2 ... Discharge port / 30bK1 ... Heat generation element / 30cK, 30cC, 30cM , 30cY ... Temperature sensor (temperature detecting means) / 40a ... Recovery tub member (covering member) / 40a1 ... Holding member / 50 ... Control unit (control means) / 80 ... Host computer ( Notification means)

Claims (8)

An ejection unit that has a plurality of nozzles and can eject ink through the plurality of nozzles by utilizing the thermal energy generated by the heat generating element.
A temperature detecting means capable of detecting the temperature of the discharge portion and
The drive of the heat generating element can be controlled, and the first mode in which the heat generating element is driven by the first output to eject ink to the recording material to the ejection unit and the number of ejections of the plurality of nozzles are used. A control means capable of driving the heat generating element with a second output larger than the first output and ejecting ink to the ejection unit.
The control means advances the timing of executing the second mode earlier than the case where the temperature detected by the temperature detecting means is higher at the end of the image forming job that forms an image in the first mode by a command.
An inkjet recording device characterized by this. When the plurality of image forming jobs are executed, the control means sets the timing of executing the second mode earlier than the case where the average value of the temperatures detected at the end of the plurality of image forming jobs is higher and lower. do,
The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is characterized in that. When the plurality of nozzles are divided into a plurality of nozzle groups composed of a number of nozzles smaller than the number of the plurality of nozzles, the control means has the plurality of nozzles at the execution timing of the second mode. Among the groups, the second mode is executed for the nozzle group in which the total number of ejections of the nozzles is a predetermined number or more, and the second mode is not executed for the other nozzle groups.
The inkjet recording apparatus according to claim 1 or 2, wherein the inkjet recording apparatus is characterized in that. An ejection unit that has a plurality of nozzles and can eject ink through the plurality of nozzles by utilizing the thermal energy generated by the heat generating element.
A temperature detecting means capable of detecting the temperature of the discharge portion and
The drive of the heat-generating element can be controlled, and the first mode in which the heat-generating element is driven by the first output to eject ink to the recording material to the ejection unit, and the second mode, which is larger than the first output. It is provided with a control means capable of executing a second mode in which the heat generating element is driven by the output of the above and the ink is ejected to the ejection portion.
The control means is
When the plurality of nozzles are divided into a plurality of nozzle groups composed of a number of nozzles smaller than the number of the plurality of nozzles, respectively.
Based on the temperature of the ejection unit detected by the temperature detecting means at the end of the image forming job that forms an image in the first mode by a command, and the number of ejections for each of the plurality of nozzles of the image forming job. Weighting is performed so that the number of times of ejection for each of the plurality of nozzles is larger than that of the case where the temperature of the ejection portion is high, and the number of ejections is accumulated for each of the plurality of nozzle groups. death,
When the cumulative value of the number of ejections exceeds the first value in at least one of the plurality of nozzle groups, the cumulative value of the number of ejections among the plurality of nozzle groups is higher than the first value. The second mode is executed for the nozzles of the nozzle group having a small second value or more.
An inkjet recording device characterized by this. An ejection unit that has a plurality of nozzles and can eject ink through the plurality of nozzles by utilizing the thermal energy generated by the heat generating element.
A temperature detecting means capable of detecting the temperature of the discharge portion and
The drive of the heat generating element can be controlled, and the first mode in which the heat generating element is driven by the first output to eject ink to the recording material and the first output are higher than the first output based on the user's command. A control means capable of executing a second mode in which the heat generating element is driven by a large second output and ink is ejected to the ejection portion.
The number of ejections for each of the plurality of nozzles for each image forming job that forms an image in the first mode according to a command and the temperature of the ejection portion detected by the temperature detecting means at the end of the image forming job are stored. Equipped with a storage unit
The control means is
When the plurality of nozzles are divided into a plurality of nozzle groups composed of a number of nozzles smaller than the number of the plurality of nozzles, respectively.
When the second mode is executed by a user's command, the higher the temperature of the discharge unit is, based on the temperature of the discharge unit stored in the storage unit and the number of discharges for each of the plurality of nozzles. The number of ejections is weighted so that the number of ejections is larger than the number of ejections for each of the plurality of nozzles, and the number of ejections is accumulated for each of the plurality of nozzle groups.
Among the plurality of nozzle groups, the second mode is executed for the nozzles of the nozzle group in which the cumulative value of the number of ejections is equal to or greater than the first predetermined value.
An inkjet recording device characterized by this. Equipped with a notification means that can notify the user of information
The control means should execute the second mode by the notification means when the cumulative value of the number of discharges stored in the storage unit reaches the second predetermined value larger than the first predetermined value. Notify the user of the information of
The inkjet recording apparatus according to claim 5, wherein the inkjet recording apparatus is characterized in that. The control means can reduce the drive output of the heat generating element by reducing the frequency of the voltage applied to the heat generating element, and when the second mode is executed, the nozzle group of the plurality of nozzles can be reduced. , The frequency of the voltage applied to the heat generating element is made smaller than the case where the number of nozzle groups that execute the second mode is large and small.
The inkjet recording apparatus according to any one of claims 4 to 6, wherein the inkjet recording apparatus is characterized in that. The plurality of nozzles are formed with ejection ports capable of ejecting ink.
A covering member capable of covering the discharge port and
A holding member provided on the covering member and capable of holding ink ejected from the ejection port covered with the covering member is provided.
When the second mode is executed, the control means drives the heat generating element to cause the ejection unit to eject ink to the holding member via the ejection port covered with the covering member.
The inkjet recording apparatus according to any one of claims 1 to 7, wherein the inkjet recording apparatus is characterized in that.

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