JP2011056738A - Control method of liquid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of a liquid jetting apparatus, suppressing deterioration in jetting accuracy and useless increase of a jetting amount, even in the configuration where flow paths in a head are directly affected by pressure fluctuation by a pumping effect. <P>SOLUTION: The moving amount (unit moving amount ΔF) of ink flowing into the inkjet head 13 in accordance with the single reciprocating movement of a carriage 14 and the inkjet head 13 during a printing operation is stored in the storage part of an inkjet printer 1. When finishing the print job, the total ink moving amount F is calculated by multiplying the number of times N of reciprocating movement of the carriage 14 during the print job by the unit moving amount ΔF, and a new total ink accumulation amount ΔV during the present print job is calculated by subtracting the total ink ejection amount Q during the print job from the total ink moving amount F. The increase of the inner pressure in the head is recognized from the accumulated ink accumulation amount V obtained by accumulating the values ΔV for each of print jobs, then, the jetting amount and suction amount of the ink for the following print job or the maintenance operation are corrected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention supplies a liquid such as ink from a flexible tube to a head mounted on a reciprocating carriage, and a liquid discharge apparatus having a structure in which an increase in internal pressure of the head occurs due to the pump effect of the flexible tube. It relates to a control method.

  In a structure in which a flexible tube is connected to a liquid discharge head mounted on a reciprocating carriage and liquid such as ink is supplied to the head via this flexible tube, the structure is flexible when the carriage is accelerated or decelerated. A pumping effect occurs in which the liquid in the tube moves due to inertia. Conventionally, in an inkjet printer having such a structure, a head internal pressure adjusting mechanism such as a self-sealing valve or a pressure damper is provided in the ink supply flow path in order to prevent fluctuations in the internal pressure due to the pump effect.

  Here, in order to reduce costs, it has been proposed to eliminate the self-sealing valve and pressure damper and provide only a check valve in the ink supply flow path. Is directly affected by the pressure fluctuation of the ink supply flow path due to the pump effect, and the ink movement due to the pump effect is only in one direction toward the head side, and the pressure in the head continues to rise. If ink is ejected from the nozzles provided in the head when the pressure inside the head is excessively high, the amount of ink droplets in each dot will be larger than that ejected at normal head pressure, resulting in poor ejection accuracy. As a result, the print quality deteriorates. In addition, during a maintenance operation such as nozzle cleaning or flushing, a larger amount of ink is ejected or sucked than when the pressure in the head is normal, so that wasteful ink consumption increases. Furthermore, since the amount of ejected ink droplets is larger than the preset ink consumption per dot, the actual ink consumption is greater than the ink consumption recorded on the IC chip of the ink cartridge. Thus, there is a problem that printing is possible without ink.

  In Patent Document 1, when the head internal pressure falls outside the appropriate pressure range, this is detected by a pressure sensor, and the carriage is scanned with an acceleration / deceleration pattern corresponding to the detected internal pressure. It is described that the rise in the pressure is eliminated and the inside of the head is maintained at an appropriate pressure to prevent ink dripping from the nozzles.

JP 2009-83387 A

  In the method of adjusting the pressure in the head of Patent Document 1, since the scanning profile of the carriage is changed when the pressure is outside the proper pressure range, the throughput of the liquid ejection operation may be reduced. Further, since the pressure sensor is provided in the head, there is a problem that the configuration becomes complicated.

  In addition, when supplying a plurality of colors of ink to the head, the amount of pressure fluctuation due to the pump effect differs depending on the color of the ink due to the difference in the positional relationship between the ink pack of each color in the ink cartridge and the head. In the method of Patent Document 1, there is a problem that an adjustment operation in consideration of a difference in pressure fluctuation for each color cannot be performed.

  In view of this point, the problem of the present invention is that, even in a configuration in which the liquid discharge head is directly affected by the pressure fluctuation of the liquid supply flow path due to the pump effect, the effect of the pump is achieved without affecting the throughput of the liquid discharge operation. An object of the present invention is to propose a control method for a liquid ejection apparatus that can suppress a decrease in ejection accuracy and an increase in a useless ejection amount due to an increase in the pressure in the head.

In order to solve the above problems, the present invention provides:
A liquid having a flexible flow path for supplying a liquid to a liquid discharge head mounted on a carriage that reciprocates in a predetermined scanning direction, and flowing toward the liquid discharge head upstream of the flexible flow path A control method of a liquid ejection device provided with a backflow prevention unit that allows only the passage to pass through,
A unit liquid movement amount that flows into the liquid discharge head is set in advance based on the inertial movement of the liquid in the flexible flow path accompanying one reciprocation of the carriage,
When performing the liquid discharge operation of the liquid discharge head,
The total liquid ejected from the nozzles of the liquid ejection head in the liquid ejection operation from the total liquid movement amount calculated by multiplying the unit liquid movement amount by the number of reciprocating movements of the carriage in the liquid ejection operation at a preset timing. Subtracting the discharge amount to calculate a total liquid accumulation amount in the liquid discharge head by the liquid discharge operation;
The liquid discharge amount in the next liquid discharge operation is controlled based on the total liquid accumulation amount.

  As described above, the present invention has a pump effect in which the liquid in the flexible flow path moves due to inertia when the carriage reciprocates, and the liquid that has passed through the backflow preventing portion is transferred to the liquid discharge head by this pump effect. It is premised on a configuration in which the internal pressure of the liquid discharge head rises every time the carriage reciprocates due to inflow and accumulation.

  In such a configuration, by calculating the unit liquid movement amount that flows into the liquid discharge head with one reciprocation of the carriage in advance, this liquid is determined based on the number of reciprocations of the carriage in the liquid discharge operation. The total liquid accumulation amount on the liquid ejection head side resulting from the ejection operation can be calculated. Then, it is possible to grasp the internal pressure fluctuation (internal pressure increase) in the liquid ejection head corresponding to the total liquid accumulation amount and control the liquid ejection quantity in consideration of the influence of the internal pressure fluctuation. Therefore, even when adopting a configuration in which the internal pressure fluctuation in the liquid discharge head due to the pump effect occurs for cost reduction and simplification of the configuration, the control reduces the accuracy of the liquid discharge amount due to the internal pressure fluctuation, Unnecessary increase in discharge amount can be suppressed. Further, it is possible to suppress problems caused by the remaining amount measurement value in the liquid cartridge being measured based on the number of ejected dots of the liquid being larger than the actual remaining amount.

  At this time, at least one of the suction amount in the next nozzle cleaning in the liquid discharge head and the liquid discharge amount in the next flushing in the liquid discharge head may be controlled based on the total liquid accumulation amount. By controlling the amount of liquid sucked and discharged for maintenance operations such as nozzle cleaning and flushing based on the total amount of accumulated liquid that reflects fluctuations in internal pressure, more ink is discharged or sucked than the specified amount. Can be prevented, and wasteful ink consumption can be suppressed.

  Further, each time the liquid ejection operation of the liquid ejection head is performed, the total liquid accumulation amount by the liquid ejection operation is added to the accumulated liquid accumulation amount in the liquid ejection head before the liquid ejection operation is performed. The accumulated liquid accumulation amount is updated. Based on the updated accumulated liquid accumulation amount, the liquid ejection amount in the next liquid ejection operation, the suction amount in the next nozzle cleaning, and the liquid ejection amount in the next flushing are calculated. It can also be controlled. In this way, the accumulated liquid accumulation amount in the liquid discharge head is updated each time the liquid discharge operation is performed, and the internal pressure of the liquid discharge head can be grasped each time based on the updated value, so that the accuracy of the liquid discharge amount is maintained. Thus, it is possible to continue to suppress an increase in useless discharge amount.

  In the present invention, the cumulative liquid accumulation amount is compared with a preset threshold value, and based on the comparison determination result, the liquid discharge amount in the next liquid discharge operation, the suction amount in the next nozzle cleaning, and Whether or not to correct the liquid discharge amount in the next flushing can be determined. In this way, when the accumulated liquid accumulation amount does not affect the liquid discharge amount and suction amount in normal liquid discharge operation and maintenance operation, or the accumulated liquid accumulation amount causes only an allowable internal pressure fluctuation even if there is an influence. The liquid discharge amount and the suction amount in the liquid discharge operation and the maintenance operation can be corrected only when the accumulated liquid accumulation amount that causes an unacceptable influence is performed.

  At this time, the accumulated liquid accumulation amount, the correction value of the liquid discharge amount in the next liquid discharge operation, the correction value of the suction amount in the next nozzle cleaning, and the liquid discharge amount in the next flushing are previously determined. A correction table that associates each of the correction values is created, and each correction value to be applied in the next liquid ejection operation, the next nozzle cleaning, and the next flushing is determined based on the correction table. Good. For example, if the correction table is stored in the control unit of the liquid ejection apparatus and the accumulated amount of accumulated liquid is calculated, the correction value corresponding to the level is extracted from the correction table and applied, so that the next control content can be easily obtained. Can be adjusted.

  In the present invention, the liquid discharge head includes a plurality of head-internal flow paths for supplying a plurality of types of liquids to separate nozzles, and the flexible flow path includes the plurality of heads. In the case where a plurality of liquid flow paths connected to the internal flow path are provided and the backflow prevention unit is provided on the upstream side of each liquid flow path, the unit liquid movement amount is set in each head. When the liquid discharge operation of the liquid discharge head is performed in advance for each flow path, the total liquid accumulation amount is calculated for each liquid type based on each unit liquid movement amount, and the next liquid The correction value of the liquid discharge amount in the discharge operation may be determined for each type of liquid. In this way, since the internal pressure fluctuations of the in-head flow path through which each type of liquid flows can be grasped separately, the optimum correction value can be applied to each type of liquid. Therefore, it is possible to more accurately suppress a decrease in the accuracy of the liquid discharge amount and an increase in a useless discharge amount.

  Here, when a liquid reservoir for supplying a corresponding type of liquid is connected to each of the flow paths for each liquid, the unit liquid movement amount corresponding to the flow path in each head is set to It may be set in accordance with the height difference between each liquid reservoir connected via the liquid flow path and the liquid discharge head. The amount of movement of the liquid due to the pump effect, that is, the amount of accumulated liquid that accompanies the reciprocating movement of the carriage decreases as the height difference from the liquid reservoir increases. Therefore, the unit liquid movement amount can be accurately set by considering such a height difference.

  In the present invention, the carriage is configured to reciprocate in a scanning direction that traverses above a printing position where a print medium is conveyed, and the liquid ejection head faces the printing position while scanning the carriage. An inkjet head that performs a printing operation on the print medium by discharging ink from a nozzle, the flexible flow path is an ink supply tube that supplies ink from an ink cartridge to the inkjet head, and the backflow prevention unit is When the check valve is provided on the upstream side of the ink supply tube, the total liquid accumulation amount is printed on a predetermined number of print media by the inkjet head at the end of the print job by the inkjet head. The head of the inkjet head calculated at any timing As total ink storage amount of the flow path, based on the total ink accumulated amount, it is possible to control the ink discharge amount in the next printing operation. If the ink ejection amount in the next printing operation is corrected at such timing, it is possible to suppress a decrease in print quality without abruptly changing the print quality in the same print job or the same printed matter.

  Further, the drive amount of the ink discharge mechanism in the next printing operation, the motor rotation speed of the suction pump in the next nozzle cleaning, and the drive amount of the ink discharge mechanism in the next flushing are controlled based on the ink accumulation amount. Can do. If these control amounts are corrected based on the ink accumulation amount, the ink discharge amount and the suction amount can be adjusted.

  According to the present invention, when the carriage reciprocates, the internal pressure of the liquid discharge head increases in advance due to the pump effect in which the liquid in the flexible flow path moves due to inertia. By calculating the unit liquid movement amount that flows into the liquid discharge head in association with the reciprocal movements, the liquid accumulation amount resulting from the liquid discharge operation can be calculated based on the number of reciprocating movements of the carriage in the liquid discharge operation. . Then, it is possible to grasp the internal pressure fluctuation (internal pressure rise) in the liquid ejection head corresponding to the liquid accumulation amount and control the liquid ejection quantity in consideration of the influence of the internal pressure fluctuation. Therefore, even when adopting a configuration in which the internal pressure fluctuation in the liquid discharge head due to the pump effect occurs for cost reduction and simplification of the configuration, the control reduces the accuracy of the liquid discharge amount due to the internal pressure fluctuation, Unnecessary increase in discharge amount can be suppressed. Further, it is possible to suppress problems caused by the remaining amount measurement value in the liquid cartridge being measured based on the number of ejected dots of the liquid being larger than the actual remaining amount.

1 is an external perspective view of an ink jet printer to which the present invention is applied. It is a schematic perspective view of a printer mechanism part. It is explanatory drawing which shows schematic structure of the ink supply system of an inkjet printer. It is a perspective view of a carriage and an ink supply system. It is a rear view of a carriage and an ink supply system. It is a flowchart of the setting change process which considered the internal pressure rise by the pump effect. It is a threshold value table for comparison determination. It is a correction table for correction value determination.

  Hereinafter, an ink jet printer which is an embodiment of a liquid ejection apparatus of the present invention and a control method thereof will be described with reference to the drawings.

(Overall configuration of inkjet printer)
FIG. 1 is an external perspective view of an ink jet printer. An ink jet printer 1 (liquid ejection device) performs color printing on a long recording paper fed out from roll paper using a plurality of types of color inks, and includes a printer case 2 having a rectangular parallelepiped shape as a whole. An opening 3 for mounting a roll paper is formed at the center of the front surface of the printer case 2. The opening 3 is sealed by an opening / closing lid 5 to which a recording paper discharge guide 4 is attached at the upper end. A recording paper discharge port 6 is formed between the recording paper discharge guide 4 and the upper edge portion of the opening 3 of the printer case 2. When the lock (not shown) is released and a finger is placed on the recording paper discharge guide 4 and pulled forward, the opening / closing lid 5 can be opened from the closed position shown in the drawing to the open position that falls forward about the lower end.

  A power switch 7a, a paper feed switch 7b, a plurality of operation state display lamps 7c, and the like are arranged on the right side of the opening / closing lid 5 on the front surface of the printer case 2. A mounting port 8a of an ink cartridge mounting portion 8 having a vertically long rectangular cross section extending in the front-rear direction of the printer is opened on the left side portion of the opening / closing lid 5 on the front surface of the printer case 2. An ink cartridge 20 is provided in the ink cartridge mounting portion 8. Is installed. When a button (not shown) is operated, the lock is released and the ink cartridge 20 is pushed forward by the spring force, so that the ink cartridge 20 can be pulled out.

  FIG. 2 is a schematic perspective view showing the printer mechanism unit 10 covered with the printer case 2 in the inkjet printer 1. A roll paper storage unit is formed in the center of the printer mechanism unit 10. When the opening / closing lid 5 is opened, the roll paper storage unit opens forward, and the roll paper can be replaced. On the upper side of the roll paper storage unit, a platen 12 is bridged in the printer width direction, and on the upper side of the platen 12, a carriage 14 equipped with an inkjet head 13 (liquid ejection head) with the nozzle surface facing downward is mounted. Has been placed. The carriage 14 can be reciprocated in the printer width direction along a carriage guide shaft 14a spanned in the printer width direction. The inkjet printer 1 performs a printing operation on roll paper by ejecting ink from the inkjet head 13 toward the roll paper while scanning the carriage 14 in conjunction with the roll paper conveyance operation by the roll paper conveyance mechanism.

  A head maintenance unit 19 is disposed at a position off the right side of the platen 12. The ink-jet head 13 mounted on the carriage 14 has an ink droplet ejection operation (flushing) that is not involved in printing for maintaining and recovering the nozzles at the home position shown in FIG. 2 facing the head maintenance unit 19. Maintenance operations such as an ink suction operation (nozzle cleaning) from the ink nozzles are performed. The waste ink liquid discharged from the inkjet head 13 is collected from the head maintenance unit 19 to the ink cartridge 20 mounted on the ink cartridge mounting unit 8 via a waste ink liquid recovery path (not shown). The head maintenance unit 19 capping the nozzle surface of the inkjet head 13 during flushing and collects the discharged waste ink. During nozzle cleaning, the suction pump is driven with the nozzle surface of the inkjet head 13 capped, and ink is forcibly sucked and discharged from each nozzle by the negative pressure from the suction pump.

(Ink supply system)
FIG. 3 is an explanatory diagram showing a schematic configuration of an ink supply system of the ink jet printer 1, and FIG. 4 is a perspective view showing only a carriage and an ink supply system in the printer mechanism unit of FIG. FIG. 5 is a rear view of the carriage and the ink supply system as viewed from the rear side of the printer (X direction in FIG. 4). As shown in FIG. 4, a diaphragm pump unit 16 including subtanks 15 a to 15 d that store inks of four colors, cyan, magenta, yellow, and black, is mounted on the carriage 14. The ink supplied from the diaphragm pump unit 16 to the inkjet head 13 is temporarily stored in each of the sub tanks 15a to 15d, and then supplied to the in-head flow paths 13a to 13d of the inkjet head 13, as shown in FIG. The A check valve 21 is provided in a flow path portion connecting each sub tank 15a to 15d and the in-head flow paths 13a to 13d of the inkjet head 13, and only in one direction from each sub tank 15a to 15d toward the inkjet head 13 side. The ink is configured to flow.

  One end of flexible ink tubes 17a to 17d (flexible flow paths) is connected to each sub tank 15a to 15d via a joint flow path. As shown in FIGS. 2 and 4, the diaphragm pump unit 16 includes suction levers 16 a to 16 d that are swingably attached to the upper portions of the sub tanks 15 a to 15 d. One end of each of the suction levers 16a to 16d is provided on the home position side of the diaphragm pump unit 16, and the other end is connected to the diaphragm of each of the sub tanks 15a to 15d via a spring. When the diaphragm pump unit 16 returns to the home position shown in FIG. 2, the suction levers 16 a to 16 d are oscillated with one end pressed by the inner wall surface of the printer case 2, and accordingly the suction levers 16 a to 16 d. A diaphragm connected to the other end of 16d is operated to form a negative pressure in each of the sub tanks 15a to 15d. With this negative pressure, ink is sucked into each sub tank from the flexible ink tubes 17a to 17d side.

  On the other hand, the other ends of the flexible ink tubes 17 a to 17 d are connected to an upper end portion of the planar flow path 18 disposed at a position on the rear end side of the ink cartridge mounting portion 8. As shown in FIG. 3, the planar flow path 18 includes four ink supply paths 18a to 18d extending in the vertical direction, and flexible ink tubes 17a to 17d are provided at the upper ends of the ink supply paths 18a to 18d, respectively. Is connected. A choke valve mechanism 22 is provided in each of the ink supply paths 18a to 18d, and the ink supply paths 18a to 18d can be closed during cleaning. Further, a check valve 23 (a backflow prevention unit) is provided on the upstream side of the choke valve mechanism 22 so that ink flows only in one direction from the ink cartridge 20 toward the flexible ink tubes 17a to 17d. Yes.

  As shown in FIG. 5, the lower end portion of the planar flow path 18 extends to the ink cartridge mounting portion 8, and each ink supply path is provided at a portion facing the rear end surface of the ink cartridge 20 mounted on the ink cartridge mounting portion 8. Four ink supply needles for connecting the ink cartridges 18a to 18d and the ink cartridge 20 are arranged vertically and project. The ink cartridge 20 has a flat rectangular parallelepiped shape that is long in the front-rear direction and the up-down direction, and four types of ink packs 20a to 20d (liquid storage portions) of cyan, magenta, yellow, and black are contained therein. They are stored in order from bottom to top. The ink supply ports of the ink packs 20a to 20d are fixed coaxially to the four ink supply needle insertion holes formed at positions facing the four ink supply needles on the rear end surface of the ink cartridge 20. .

  When the ink cartridge 20 is inserted into the mounting position of the ink cartridge mounting portion 8, each ink supply needle is inserted into each ink supply needle insertion hole. Thereby, an ink supply path for supplying each color ink from the respective ink packs 20a to 20d of the ink cartridge 20 to the ink jet head 13 via each ink supply needle is formed. The inside of the ink cartridge 20 is pressurized by the supply of compressed air from a pressure mechanism (not shown), and the ink stored in each of the ink packs 20a to 20d is sent out to the ink supply paths 18a to 18d by this pressure. .

(Control method considering the effect of internal pressure fluctuation due to pump effect)
In the configuration described above, the downstream end portion of the flexible ink tubes 17a to 17d moves from the position A (home position) to the position B shown in FIG. The ink in the flexible ink tubes 17a to 17d moves inertially at this time. Here, when the ink inertially moves to the downstream side (inkjet head 13 side) of the flexible ink tubes 17a to 17d, that is, the carriage 14 accelerates while moving away from the home position, or the carriage 14 moves to the home. When decelerating while moving in the direction of returning to the position, the upstream side of the flexible ink tubes 17a to 17d becomes negative pressure due to the movement of ink, and new ink is sucked from the ink cartridge 20 and passes through the check valve 23. At this time, the ink that has passed through the check valve 23 passes through the check valve 23 even if the ink is inertially moved to the upstream side (ink cartridge 20 side) of the flexible ink tubes 17a to 17d by reverse acceleration / deceleration. Thus, it cannot return to the ink cartridge 20 side. In other words, every time the carriage 14 is reciprocated, the ink jet printer 1 accumulates the ink downstream of the check valve 23 by a predetermined amount by the pump effect. The ink that has flowed into the head flow paths 13a to 13d with this ink flow is also accumulated in the head flow paths 13a to 13d by the check valve 21, and the internal pressure of the head flow paths 13a to 13d increases. It has become.

  In the present embodiment, in consideration of such an increase in internal pressure accompanying the reciprocating movement of the carriage 14 and the inkjet head 13 during the printing operation, an amount obtained by subtracting an increase in the discharge amount due to the increase in the internal pressure in the head flow paths 13a to 13d in advance. The drive level of the ink ejection mechanism is corrected so that is the ejection amount per dot, and the setting is changed so that printing is performed at the corrected drive level in the next printing. As a result, in the next printing, the inkjet head 13 can be controlled so that the ink can be ejected in a substantially prescribed amount.

  In addition, if flushing or nozzle cleaning is performed while the internal pressure in the head internal flow paths 13a to 13d is increased, an excessive amount of ink is ejected or sucked, so that the drive level of the ink ejection mechanism during flushing is increased. The correction is performed in consideration of the increase in the discharge amount due to the nozzle, and the motor rotation speed of the suction pump during nozzle cleaning is corrected in consideration of the increase in the suction amount due to the increase in internal pressure. In the next flushing and the next nozzle cleaning, the setting is changed so that flushing and cleaning are performed at the corrected drive level and rotation speed.

  FIG. 6 is a flowchart of a setting change process for performing control during printing or maintenance in consideration of an increase in internal pressure due to the pump effect. The control unit of the inkjet printer 1 performs the processing of this flowchart at the timing when each print job is completed, determines a correction value used for control of the next printing operation and maintenance operation, and changes the setting. In the present embodiment, in order to grasp the increase in internal pressure without using a pressure sensor, a unit movement amount ΔF (unit of movement of ink flowing into the inkjet head 13 with one reciprocation of the carriage 14 is previously determined. (Liquid movement amount) is calculated by experiment or calculation and stored in the storage unit of the ink jet printer 1.

  First, in step S1, the unit movement amount ΔF stored in advance and the accumulated ink accumulation amount V (accumulated liquid accumulation amount) calculated at the end of the previous print job are read from the storage unit of the inkjet printer 1. Then, the measured value of the total ink discharge amount Q (total liquid discharge amount) by the current print job is read from an IC chip (CSIC) provided in the ink cartridge 20. Here, the accumulated ink accumulation amount V is a value obtained by calculating and accumulating the total ink accumulation amount ΔV (total liquid accumulation amount) by the print job every time the print job is executed from the installation time of the ink cartridge 20. It is. This value is updated by performing the setting update process of FIG. 6 for each print job execution. In addition, the ink discharge amount recorded in the CSIC is a measured value that counts not only the ink discharge amount for printing but also the ink discharge amount for maintenance such as flushing and nozzle cleaning performed during the execution of the print job. is there.

  Subsequently, in step S2, the total ink movement amount F (total liquid movement amount) in the current print job is calculated by multiplying the number of reciprocating movements N of the carriage 14 in the current print job by the unit movement amount ΔF. Then, the calculated total ink movement amount F is subtracted from the total ink discharge amount Q of the current print job read from the CSIC, and the total ink accumulation amount ΔV newly accumulated on the inkjet head 13 side by this print job is calculated. To do. Then, the accumulated ink accumulation amount V is updated by adding the total ink accumulation amount ΔV of the current print job to the accumulated ink accumulation amount V at the end of the previous print job. The total ink accumulation amount ΔV calculated in step S2 is a value corresponding to the increase in internal pressure of the inkjet head 13 due to this print job. Further, the accumulated ink accumulation amount V is a value corresponding to the internal pressure of the inkjet head 13 at this time.

  Next, in steps S3 to S9, a comparison determination is made between the updated accumulated ink accumulation amount V and a preset threshold value. Then, the presence / absence of correction and the correction value are determined based on the comparison determination result. FIG. 7 is a threshold table showing the setting contents of threshold values for comparison determination, and FIG. 8 is a correction table for determining correction values based on the comparison determination result. In this embodiment, threshold values in a plurality of stages are set in advance, and the level of the accumulated ink accumulation amount V is determined in a plurality of stages by comparison with these threshold values. In the correction table, as the correction values corresponding to the respective levels, a correction value for the ejection amount for one dot during printing, a correction value for the ejection amount during flushing, and a correction value for the suction amount during nozzle cleaning are included. Two correction values are set. In the correction table of FIG. 8, how much the discharge amount and the suction amount are reduced from the specified amount is specified as each correction value. Alternatively, the drive voltage and drive time of the ink ejection mechanism, the motor rotation speed of the suction pump, and the like for realizing this reduction amount may be set directly in the correction table.

  First, in step S3, a comparison with the smallest threshold (threshold A) is performed. The threshold A is set to a level at which the influence of the increase in internal pressure due to ink accumulation is within an allowable range in terms of print quality, ink consumption, etc., if the cumulative ink accumulation amount V is less than this level. In the present embodiment, as shown in FIG. 7, the threshold A is set to a value when the internal pressure of the inkjet head 13 increases by 30 mmAg from the specified internal pressure, and specifically, is set to 0.3 cc. If the accumulated ink accumulation amount V is equal to or less than the threshold value A in this determination (step S3: No), it is determined that correction is unnecessary and the process ends. On the other hand, when the accumulated ink accumulation amount V is larger than the threshold value A (step S3: Yes), the process proceeds to step S4.

  In step S4, a comparison with the second smallest threshold (threshold B) is performed. As shown in FIG. 7, the threshold value B is set to a value when the internal pressure of the inkjet head 13 increases by 70 mmAg from the specified internal pressure, specifically, 0.5 cc. If the accumulated ink accumulation amount V is less than or equal to the threshold value B in this determination (step S4: No), the process proceeds to step S5, and the level of the accumulated ink accumulation amount V (threshold value A <V≤) from the correction table of FIG. The correction value corresponding to the threshold value B) is read, and the process proceeds to step S9. The correction values corresponding to this level are a 3% reduction in the discharge amount of one dot during printing, a 1% reduction in the discharge amount during flushing, and a 2% reduction in the suction amount during nozzle cleaning. On the other hand, when the accumulated ink accumulation amount V is larger than the threshold value B (step S4: Yes), the process proceeds to step S6.

  In step S6, a comparison with the largest threshold value (threshold value C) is performed. As shown in FIG. 7, the threshold value C is set to a value when the internal pressure of the inkjet head 13 increases by 100 mmAg from the specified internal pressure. If the accumulated ink accumulation amount V is equal to or less than the threshold value C in this determination (step S6: No), the process proceeds to step S7, and the level of the accumulated ink accumulation amount V (threshold value B <V ≦ V) from the correction table of FIG. The correction value corresponding to the threshold value C) is read, and the process proceeds to step S9. The correction values corresponding to this level are a 5% reduction in the discharge amount of one dot during printing, a 3% reduction in the discharge amount during flushing, and a 5% reduction in the suction amount during nozzle cleaning.

  If the accumulated ink accumulation amount V is larger than the threshold value C in step S6 (step S6: Yes), the process proceeds to step S8, and the level of the accumulated ink accumulation amount V (threshold value C <V) from the correction table of FIG. ) Is read out. The correction values corresponding to this level are 7% reduction in the discharge amount of 1 dot during printing, 5% reduction in the discharge amount during flushing, and 7% reduction in the suction amount during nozzle cleaning. Thereafter, the process proceeds to step S9.

  In step S9, the setting of the inkjet printer 1 is changed so that each correction value read based on the comparison determination result with the threshold value is applied to the control of the next printing operation and maintenance operation, and the process is terminated. To do.

  The inkjet printer 1 performs the above setting change process separately for each of the four colors of ink every time the print job is completed. The ink jet printer 1 has four systems of ink supply channels for printing using four colors of ink, and ink packs 20a to 20d that supply ink to the ink supply channels are ink cartridges 20. Are stored at different heights. Therefore, the height difference of the ink supply flow path from each ink pack 20a to 20d to the inkjet head 13 differs depending on the color of the ink, and the ink movement amount (unit movement amount ΔF) due to the pump effect flows according to this height difference. Every road is different. Specifically, when unit movement amounts in the ink supply flow paths from the ink packs 20a to 20d arranged from the bottom to the top in the order of cyan, magenta, yellow, and black are ΔFa to ΔFd, ΔFa <ΔFb. The magnitude relationship is such that <ΔFc <ΔFd.

  Therefore, in the present embodiment, the unit movement amounts ΔFa to ΔFd for the inks of the respective colors are calculated separately and stored according to the height difference between the ink packs 20a to 20d and the inkjet head 13 in advance. The threshold value table and the correction table shown in FIGS. 7 and 8 are set separately for each ink color. As a result, it is possible to perform optimum correction for each color ink. Although the ejection amount in printing and flushing can be controlled according to the color of ink, the suction amount in nozzle cleaning cannot be controlled for each nozzle. Therefore, the suction amount in nozzle cleaning is set according to the color ink with the smallest increase in internal pressure. In this way, nozzle cleaning can be performed reliably, and wasteful ink consumption can be reduced as much as possible.

  As described above, the control method of the ink jet printer 1 according to the present embodiment is such that the flow path in the head is caused by the pump effect in which the liquid in the flexible ink tubes 17a to 17d moves by inertia when the carriage reciprocates. In consideration of the internal pressure increase of 13a to 13d, the ink discharge amount and the ink suction amount can be controlled so as to cancel the increase in the discharge amount due to the increase in the internal pressure. It is possible to suppress a decrease and a wasteful increase in discharge amount. As a result, since the ink can be ejected in a substantially prescribed amount, the ink remaining amount measurement value in the ink cartridge 20 measured based on the number of ejected dots of ink and recorded in the CSIC is the actual remaining amount. It is possible to suppress the amount from exceeding the amount, and it is possible to suppress problems such as the possibility of printing even though the ink end. Therefore, it is possible to simplify the configuration of the inkjet printer 1 and reduce the cost by eliminating the self-sealing valve and the pressure damper while suppressing the decrease in print quality and the increase in useless ink consumption.

(Other embodiments)
The above embodiment is an example in which the present invention is applied to the control method of the ink jet printer 1, but the present invention can also be applied to other liquid ejecting apparatuses that eject liquid other than ink. For example, it can also be applied to liquid ejection devices for ejecting reagent solutions and liquid samples from liquid ejection heads, and liquid ejection devices for ejecting liquid paints and liquid materials from liquid ejection heads and applying them by printing It is.

(Modification example)
(1) In the above embodiment, every time a print job is completed, a cumulative ink accumulation amount calculation process, a correction presence / absence and correction value determination process, and a setting change process for subsequent control are performed. May be performed every time a predetermined number of printed matter is printed. Alternatively, the number of times of reciprocation of the carriage may be integrated and performed every time the specified number of times is reached. Moreover, you may set so that it may carry out according to a predetermined time schedule. For example, when execution such as maintenance processing is set to be performed according to a predetermined time schedule, it may be performed corresponding to these schedules.

(2) In the above embodiment, the total ink accumulation amount ΔV is calculated for each print job, and the accumulated ink accumulation amount which is the accumulated value is stored. However, the internal pressure rise corresponding to the calculated total ink accumulation amount ΔV The amount ΔP may be calculated, accumulated, and stored. In this case, the internal pressure increase threshold may be used as the comparison determination threshold.

(3) Considering that the unit movement amount ΔF due to the pump effect changes according to the internal pressure of the in-head flow paths 13a to 13d to which the ink flows, the unit movement amount ΔF and the in-head flow paths 13a to 13d. A correspondence table with the internal pressure may be created in advance. In this case, instead of accumulating the accumulated ink amount V, the accumulated internal pressure increase amount P is accumulated, and at the step S1, the accumulated internal pressure increase amount P is first read and the corresponding unit movement amount ΔF is read out. Should be read. In this way, the ink discharge amount can be controlled more accurately.

(4) In the above embodiment, correction values applied to ink ejection related to printing, ink ejection for maintenance, and ink suction are all set every time a print job ends. This determination may be made in accordance with the maintenance timing. For example, the correction value for the suction amount for nozzle cleaning may be determined before nozzle cleaning. Further, correction may not be performed for ink discharge or ink suction for maintenance.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printer (liquid discharge apparatus), 2 ... Printer case, 3 ... Opening part, 4 ... Recording paper discharge guide, 5 ... Opening / closing lid, 6 ... Recording paper discharge port, 7a ... Power switch, 7b ... Switch, 7c ... Operation state display lamp, 8 ... ink cartridge mounting part, 8a ... mounting port, 10 ... printer mechanism part, 12 ... platen, 13 ... inkjet head (liquid ejection head), 13a-13d ... flow path in head, 14 ... carriage, 14a ... Carriage guide shaft, 15a-15d ... Sub tank, 16 ... Diaphragm pump unit, 16a-16d ... Suction lever, 17a-17d ... Flexible ink tube (flexible flow path), 18 ... Flat flow path, 18a ˜18d ... ink supply path, 19 ... head maintenance unit, 20 ... ink cartridge, 20a-20d ... Nkpak (liquid storage part), 21 ... check valve, 22 ... choke valve mechanism, 23 ... check valve (backflow prevention part), ΔF, ΔFa to ΔFd ... unit movement amount (unit liquid movement amount), F ... total ink Movement amount (total liquid movement amount), Q ... Total ink ejection amount (total liquid ejection amount), V ... Cumulative ink accumulation amount (cumulative liquid accumulation amount), ΔV ... Total ink accumulation amount (total liquid accumulation amount)

Claims (9)

A liquid having a flexible flow path for supplying a liquid to a liquid discharge head mounted on a carriage that reciprocates in a predetermined scanning direction, and flowing toward the liquid discharge head upstream of the flexible flow path In the control method of the liquid ejection device provided with the backflow prevention unit that allows only the passage through,
A unit liquid movement amount that flows into the liquid discharge head based on the inertial movement of the liquid in the flexible flow path accompanying one reciprocation of the carriage is set in advance,
When performing the liquid discharge operation of the liquid discharge head,
The total liquid discharged from the nozzles of the liquid discharge head in the liquid discharge operation from the total liquid movement amount calculated by multiplying the unit liquid movement amount by the number of reciprocating movements of the carriage in the liquid discharge operation at a preset timing. Subtracting the discharge amount to calculate a total liquid accumulation amount in the liquid discharge head by the liquid discharge operation;
A method for controlling a liquid ejection apparatus, comprising: controlling a liquid ejection amount in a next liquid ejection operation based on the total liquid accumulation amount. In claim 1,
A liquid ejection apparatus that controls at least one of a suction amount in the next nozzle cleaning in the liquid ejection head and a liquid ejection amount in the next flushing in the liquid ejection head based on the total liquid accumulation amount Control method. In claim 2,
Each time the liquid ejection operation of the liquid ejection head is performed, the total liquid accumulation amount by the liquid ejection operation is added to the accumulated liquid accumulation amount in the liquid ejection head before the liquid ejection operation is performed, and the accumulated liquid Update accumulated amount,
A liquid that controls a liquid discharge amount in the next liquid discharge operation, a suction amount in the next nozzle cleaning, and a liquid discharge amount in the next flushing based on the accumulated liquid accumulation amount after the update. Discharge device control method. In claim 3,
Perform a comparison determination between the accumulated liquid accumulation amount and a preset threshold value,
Whether to correct the liquid discharge amount in the next liquid discharge operation, the suction amount in the next nozzle cleaning, and the liquid discharge amount in the next flushing is determined based on the comparison determination result. A method for controlling the liquid ejection apparatus. In claim 3 or 4,
The accumulated liquid accumulation amount, the correction value of the liquid discharge amount in the next liquid discharge operation, the correction value of the suction amount in the next nozzle cleaning, and the correction value of the liquid discharge amount in the next flushing in advance Create a correction table that correlates
A control method for a liquid ejection apparatus, comprising: determining each correction value to be applied in the next liquid ejection operation, the next nozzle cleaning, and the next flushing based on the correction table. In any one of claims 1 to 5,
The liquid discharge head includes a plurality of head internal channels for supplying a plurality of types of liquids to separate nozzles, and the flexible channel is connected to the plurality of head internal channels. It is provided with a plurality of flow paths for each liquid to be connected, and the backflow prevention unit is provided on the upstream side of each flow path for each liquid,
The unit liquid movement amount is preset for each flow path in the head,
When performing the liquid discharge operation of the liquid discharge head,
The total liquid accumulation amount is calculated for each type of liquid based on each unit liquid movement amount, and a correction value for the liquid discharge amount in the next liquid discharge operation is determined for each type of liquid. A method for controlling the liquid ejection apparatus. In claim 6,
Each liquid flow path is connected to a liquid reservoir for supplying a corresponding type of liquid,
The unit liquid movement amount corresponding to the flow path in each head is set in accordance with the height difference between each liquid storage part connected via each flow path for each liquid and the liquid discharge head. A method for controlling a liquid ejection apparatus. In any one of claims 1 to 7,
The carriage is configured to reciprocate in a scanning direction that traverses above a printing position where a print medium is conveyed,
The liquid discharge head is an inkjet head that performs a printing operation on the print medium by discharging ink from a nozzle facing the print position while scanning the carriage.
The flexible flow path is an ink supply tube that supplies ink from an ink cartridge to the inkjet head,
The backflow prevention unit is a check valve provided on the upstream side of the ink supply tube,
The total liquid accumulation amount is calculated in the flow path in the head of the ink jet head calculated at any timing of when a print job by the ink jet head is finished or when printing on a preset number of print media by the ink jet head is finished. The total ink accumulation amount of
A control method for a liquid ejection apparatus, wherein an ink ejection amount in a next printing operation is controlled based on the total ink accumulation amount. In claim 8,
Based on the total ink accumulation amount, the drive amount of the ink discharge mechanism in the next printing operation, the motor rotation speed of the suction pump in the next nozzle cleaning, and the drive amount of the ink discharge mechanism in the next flushing are controlled. A control method for a liquid ejection apparatus.

Images