JP2021154667A - Liquid discharge device - Google Patents

Abstract

To shorten a time required for discharging a liquid to a medium to be discharged as much as possible while sufficiently supplying the liquid to a liquid discharge head.SOLUTION: Limit processing for reducing an ink discharge quantity per unit time in a recording pass is executed when a duty D, which is indicated by image data corresponding to the recording pass is higher than a threshold D1. In such a printer, when an instruction signal for instructing performance of suction purge is inputted by a user, discharge determination processing is executed (S201) before performance of the suction purge. It is estimated that under-refilling due to poor supply of an ink to an ink jet head occurs on the basis of the result of the discharge determination processing when a prescribed number of nozzles, which are continuously arranged and include a farthest nozzle from an ink supply port of a nozzle array, are non-discharge nozzles (S202: YES, S203: YES), and the threshold D1 is decreased (S206).SELECTED DRAWING: Figure 8

Description

The present invention relates to a liquid discharge device that discharges a liquid from a nozzle.

As an example of a liquid ejection device that ejects liquid from a nozzle, Patent Document 1 describes an inkjet printer that ejects ink from a nozzle to perform recording. In the inkjet printer described in Patent Document 1, the ejection head is recorded when the conditions such as the print duty ratio being equal to or higher than the threshold value are satisfied during the recording operation of ejecting ink while reciprocating the ejection head to form an image. Executes the duty limit function that pauses outside the area to generate a waiting time. As a result, it is possible to prevent so-called underrefill, which is a shortage of ink supply to the ejection head, from occurring.

Japanese Patent No. 4793462

Here, in the inkjet printer of Patent Document 1, if the threshold value is uniformly determined so that underrefill does not occur in any usage environment, the threshold value becomes small. On the other hand, the smaller the threshold value, the higher the frequency of executing the duty limiting function, which leads to a decrease in recording speed.

The inkjet printer of Patent Document 1 is provided with a so-called serial head in which ink is ejected from a nozzle while the print head reciprocates, but the total length of the recording paper is in a direction orthogonal to the transport direction of the recording paper. Even in a printer provided with a so-called line head extending over the same direction, if a uniform threshold value is determined and the duty is limited depending on whether or not the duty exceeds the threshold value as described above, the above problem occurs.

An object of the present invention is to provide a liquid discharge device capable of supplying a sufficient amount of liquid to a liquid discharge head and shortening the time required for discharging the liquid to a medium to be discharged as much as possible.

In the liquid discharge device of the present invention, the liquid discharge head, the tank for storing the liquid, the connection flow path connecting the liquid discharge head and the tank, and the liquid discharge head and the discharge medium are the first. The liquid discharge head includes a nozzle, and a plurality of individual flow paths arranged in a second direction intersecting the first direction, and the liquid discharge head, comprising a relative moving means for relatively moving in a direction and a control device. The control device has a common flow path connected to a plurality of individual flow paths and a supply port for supplying a liquid to the common flow path, and the control device is provided with the liquid discharge head and a cover to the relative moving means. The liquid is discharged to the discharge medium by causing the liquid discharge head to discharge the liquid from the nozzles constituting the plurality of individual flow paths while moving the discharge medium relative to the first direction. When the duty, which is the ratio of the actual liquid discharge amount to the maximum liquid discharge amount per unit time in the liquid discharge head, satisfies a predetermined condition corresponding to being higher than the threshold value, the liquid discharge head The amount of liquid discharged per unit time in the above is reduced so that the limiting process for setting the duty to be equal to or less than the threshold value is executed, and further, the liquid is not discharged from the nozzles constituting the plurality of individual flow paths. It receives discharge information regarding whether or not it is a discharge nozzle, and based on the discharge information, is continuous in the second direction including the individual flow path farthest from the supply port among the plurality of individual flow paths. It is determined whether or not the nozzles constituting the predetermined individual flow paths arranged side by side are the non-discharge nozzles, and it is determined that the nozzles constituting the predetermined individual flow paths are the non-discharge nozzles. When this is done, the threshold value is reduced, and thereafter, it is determined whether or not to execute the restriction process based on the predetermined condition according to the threshold value after the reduction.

It is known that when the supply of liquid to the liquid discharge head is insufficient, the nozzles constituting the continuous individual flow paths including the individual flow paths farthest from the supply port become non-discharge nozzles. Therefore, in the present invention, when it is determined that the nozzles constituting the continuous predetermined individual flow paths including the individual flow paths farthest from the supply port are non-discharge nozzles based on the discharge information, the limiting process is performed. Decrease the threshold that is the basis for deciding whether or not to execute. As a result, the threshold value can be set to a large value, and when the supply of liquid to the liquid discharge head is actually insufficient, the threshold value can be reduced, and finally, the threshold value can be set. The value can be set to an appropriate value for the liquid discharge head.

It is a schematic block diagram of the printer which concerns on embodiment of this invention. It is a figure for demonstrating the detection electrode arranged in the cap, and the connection relationship between the detection electrode, a high voltage power supply circuit, and a determination circuit. (A) is a diagram showing a change in the voltage value of the detection electrode when ink is ejected from the nozzle, and (b) is a diagram showing a change in the voltage value of the detection electrode when ink is not ejected from the nozzle. It is a figure which shows. It is a top view of the inkjet head of FIG. (A) is an enlarged view of the VA portion of FIG. 4, and (b) is a sectional view taken along line VB-VB of (a). It is a block diagram which shows the electrical structure of a printer. It is a flowchart which shows the flow of processing at the time of recording. It is a flowchart which shows the flow of processing when a purge instruction signal is input by a user. It is a flowchart which shows the flow of the process for changing the duty threshold value which is performed at the time of standby which is not recording. It is a flowchart corresponding to FIG. 7 of the modification 1. It is a flowchart corresponding to FIG. 7 of the modification 1. It is a flowchart corresponding to FIG. 9 of the modification 1.

Hereinafter, preferred embodiments of the present invention will be described.

<Overall configuration of printer>
As shown in FIG. 1, the printer 1 (“liquid ejection device” of the present invention) according to the present embodiment includes a carriage 2 (“relative moving means” of the present invention), a sub tank 3, and an inkjet head 4 (“relative moving means” of the present invention). It is equipped with a liquid discharge head ”), a platen 5, transfer rollers 6 and 7, a maintenance unit 8, and the like.

The carriage 2 is supported by two guide rails 11 and 12 extending in the scanning direction. The carriage 2 is connected to a carriage motor 86 (see FIG. 6) via a belt or the like (not shown), and when the carriage motor 86 is driven, the carriage 2 moves in the scanning direction along the guide rails 11 and 12. In the following, as shown in FIG. 1, the right side and the left side in the scanning direction will be defined and described.

The sub tank 3 is mounted on the carriage 2. Here, the printer 1 includes a cartridge holder 13, and four ink cartridges 14 (“tanks” of the present invention) are detachably attached to the cartridge holder 13. The four ink cartridges 14 store black, yellow, cyan, and magenta inks (the "liquid" of the present invention) from those arranged in the scanning direction and arranged on the right side in the scanning direction. The sub tank 3 is connected to four ink cartridges 14 mounted on the cartridge holder 13 via four tubes 15. As a result, the four color inks are supplied from the four ink cartridges 14 to the sub tank 3.

The inkjet head 4 is mounted on the carriage 2 and is connected to the lower end of the sub tank 3. The ink jet head 4 is supplied with the above four colors of ink from the sub tank 3. In the present embodiment, the tube 15 connecting the ink cartridge 14 and the inkjet head 4 and the ink flow path in the sub tank 3 are combined to correspond to the "connection flow path" of the present invention.

Further, the inkjet head 4 ejects ink from a plurality of nozzles 10 formed on the nozzle surface 4a which is the lower surface thereof. More specifically, the plurality of nozzles 10 form a nozzle row 9 by arranging them in a transport direction orthogonal to the scanning direction, and the inkjet head 4 has four rows of nozzle rows 9 arranged in the scanning direction. Has. Black, yellow, cyan, and magenta inks are ejected from the plurality of nozzles 10 from those forming the nozzle row 9 on the right side in the scanning direction.

The platen 5 is arranged below the inkjet head 4 and faces the plurality of nozzles 10. The platen 5 extends in the scanning direction over the entire length of the recording paper P (“the medium to be ejected” of the present invention) and supports the recording paper P from below. The transfer roller 6 is arranged on the upstream side in the transfer direction with respect to the inkjet head 4 and the platen 5. The transport roller 7 is arranged on the downstream side in the transport direction with respect to the inkjet head 4 and the platen 5. The transfer rollers 6 and 7 are connected to the transfer motor 87 (see FIG. 6) via a gear (not shown) or the like. When the transfer motor 87 is driven, the transfer rollers 6 and 7 rotate, and the recording paper P is conveyed in the transfer direction.

The maintenance unit 8 includes a cap 71, a suction pump 72, and a waste liquid tank 73. The cap 71 is arranged on the right side in the scanning direction with respect to the platen 5. Then, when the carriage 2 is positioned at the maintenance position on the right side of the platen 5 in the scanning direction, the plurality of nozzles 10 face the cap 71.

Further, the cap 71 can be raised and lowered by the cap raising and lowering mechanism 88 (see FIG. 6). Then, when the cap 71 is raised by the cap elevating mechanism 88 in a state where the plurality of nozzles 10 and the cap 71 are opposed to each other by positioning the carriage 2 at the maintenance position, the upper end portion of the cap 71 is brought to the nozzle surface 4a. The plurality of nozzles 10 are in close contact with each other and are covered with the cap 71. The cap 71 is not limited to covering the plurality of nozzles 10 by being in close contact with the nozzle surface 4a. The cap 71 may cover a plurality of nozzles 10 by, for example, being brought into close contact with a frame (not shown) arranged around the nozzle surface 4a of the inkjet head 4.

The suction pump 72 is a tube pump or the like, and is connected to the cap 71 and the waste liquid tank 73. Then, in the maintenance unit 8, when the suction pump 72 is driven with the plurality of nozzles 10 covered by the cap 71 as described above, the ink in the inkjet head 4 is discharged from the plurality of nozzles 10, so-called suction purge. (The "purge" of the present invention) can be performed. The ink discharged by the suction purge is stored in the waste liquid tank 73.

Further, in the present embodiment, as the suction purge, either a weak purge (“first purge” of the present invention) or a strong purge (“second purge” of the present invention) in which the amount of ink discharged is larger than that of the weak purge. Can be selectively performed. Here, in the strong purge, for example, the drive time of the suction pump 72 is longer than that of the weak purge, or the rotation speed of the suction pump 72 is faster than that of the weak purge, so that the amount of ink discharged is larger than that of the weak purge. ing.

Here, for convenience, the cap 71 covers all the nozzles 10 together, and in the suction purge, the ink in the inkjet head 4 is discharged from all the nozzles 10, but this is limited to this. No. For example, the cap 71 covers a plurality of nozzles 10 constituting the rightmost nozzle row 9 for ejecting black ink, and the left three rows of nozzle rows 9 for ejecting color ink (yellow, cyan, magenta ink). Even if a portion that covers a plurality of nozzles 10 constituting the ink jet head 4 is separately provided, and either black ink or color ink in the inkjet head 4 can be selectively discharged in suction purging. good. Alternatively, for example, the cap 71 may be individually provided for each nozzle row 9 so that ink can be discharged from the nozzle 10 individually for each nozzle row 9 in the suction purge.

Further, as shown in FIG. 2, a detection electrode 76 having a rectangular planar shape is arranged in the cap 71. The detection electrode 76 is connected to the high voltage power supply circuit 77 via a resistor 79. Then, a predetermined positive potential (for example, about 300 V) is applied to the detection electrode 76 by the high voltage power supply circuit 77. On the other hand, the inkjet head 4 is held at the ground potential. As a result, a predetermined potential difference is generated between the inkjet head 4 and the detection electrode 76. A determination circuit 78 is connected to the detection electrode 76. The determination circuit 78 compares the voltage value of the voltage signal output from the detection electrode 76 with the threshold value Vt, and outputs a signal according to the result.

More specifically, since a potential difference is generated between the inkjet head 4 and the detection electrode 76, the ink ejected from the nozzle 10 is charged. When the ink is ejected from the nozzle 10 toward the detection electrode 76 with the carriage 2 positioned at the maintenance position, the charged ink approaches the detection electrode 76 as shown in FIG. 3A. Until the ink lands on the detection electrode 76, the voltage value of the detection electrode 76 rises from the voltage value V1 when the inkjet head 4 is not driven, and reaches a voltage value V2 higher than the voltage value V1. Then, after the charged ink lands on the detection electrode 76, the voltage value of the detection electrode 76 gradually decreases and returns to the voltage value V1. That is, the voltage value of the detection electrode 76 changes during the drive period Td of the inkjet head 4.

On the other hand, when ink is not ejected from the nozzle 10, the voltage value of the detection electrode 76 almost changes from the voltage value V1 during the drive period Td of the inkjet head 4, as shown in FIG. 3 (b). do not. Therefore, in the determination circuit 78, a threshold value Vt (V1 <Vt <V2) is set in order to distinguish them. Then, the determination circuit 78 compares the maximum voltage value of the voltage signal output from the detection electrode 66 with the threshold value Vt during the drive period Td of the inkjet head 4, and outputs a determination signal according to the determination result. do. In the present embodiment, the combination of the detection electrode 66, the high voltage power supply circuit 67, the resistor 79, and the determination circuit 78 corresponds to the “signal output unit” of the present invention. Then, the signal output unit outputs a signal according to whether or not the nozzle 10 is a non-ejection nozzle in which ink is not ejected.

Further, here, the high-voltage power supply circuit 77 applies a positive potential to the detection electrode 76, but the high-voltage power supply circuit 77 applies a negative potential (for example, about −300 V) to the detection electrode 76. It may have been done. In this case, contrary to the above, when the carriage 2 is positioned at the maintenance position and the ink is ejected from the nozzle 10 toward the detection electrode 76, the charged ink is discharged from the detection electrode 76. The voltage value of the detection electrode 66 drops from the voltage value V1 until the ink lands on the detection electrode 76, and after the ink lands on the detection electrode 76, the voltage value of the detection electrode 66 gradually increases. It rises and returns to the voltage value V1.

<Inkjet head>
Next, the structure of the inkjet head 4 will be described in detail. As shown in FIGS. 4, 5 (a) and 5 (b), the inkjet head 4 has a flow path unit 21 and a piezoelectric actuator 22.

The flow path unit 21 is formed by stacking plates 31 to 35 in this order from the bottom in the vertical direction. The flow path unit 21 includes a plurality of individual flow paths 41 including nozzles 10, and four common flow paths 42.

Corresponding to the case where the plurality of nozzles 10 form the four rows of nozzle rows 9 as described above, the plurality of individual flow paths 41 form the individual flow path rows 29 by being arranged in the transport direction. The flow path unit 21 has four rows of individual flow path rows 29 arranged in the scanning direction.

Each individual flow path 41 has a nozzle 10, a pressure chamber 51, a descender 52, and a throttle flow path 53. The nozzle 10 and the left end of the pressure chamber 51 in the scanning direction are connected via a descender 52, and the throttle flow path 53 is connected to the right end of the pressure chamber 51 in the scanning direction. Further, in the present embodiment, the structures of the plurality of individual flow paths 41 are all the same. Therefore, the flow path resistances of the plurality of individual flow paths 41 are all the same. Since the structures and positional relationships of the nozzle 10, the pressure chamber 51, the descender 52, and the throttle flow path 53 are the same as those in the prior art, further detailed description thereof will be omitted here.

The four common flow paths 42 correspond to the four rows of individual flow paths 29, and extend in the transport direction to form the corresponding individual flow paths 29 on the right side in the scanning direction of the plurality of individual flow paths 41. It overlaps the part vertically. The common flow path 42 is connected to a connection port 53a provided at the right end of the throttle flow path 53 constituting these individual flow paths 41 in the scanning direction. Ink is supplied to each common flow path 42 from a supply port 42a provided at an end on the upstream side in the transport direction.

The piezoelectric actuator 22 has a diaphragm 61, a piezoelectric layer 62, a common electrode 63, and a plurality of individual electrodes 64. The diaphragm 61 is made of a piezoelectric material containing lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, as a main component, and is arranged on the upper surface of the flow path unit 21 (upper surface of the plate 35). It covers the pressure chamber 51. The piezoelectric layer 62 is made of the above-mentioned piezoelectric material, is arranged on the upper surface of the diaphragm 61, and extends continuously over a plurality of pressure chambers 51. In the first embodiment, the diaphragm 61 and the piezoelectric layer 62 are made of a piezoelectric material, but the diaphragm 61 may be made of an insulating material other than the piezoelectric material, such as a synthetic resin material.

The common electrode 63 is arranged between the diaphragm 61 and the piezoelectric layer 62, and extends over the entire area thereof. The common electrode 63 is connected to a power source (not shown) via a wiring (not shown) and held at the ground potential. The plurality of individual electrodes 64 are arranged on the upper surface of the piezoelectric layer 62. The plurality of individual electrodes 64 are individual to the plurality of pressure chambers 51, and vertically overlap the central portion of the corresponding pressure chambers 51. Each of the plurality of individual electrodes 64 is connected to the driver IC 89 (see FIG. 6) via wiring (not shown). Then, either the ground potential or the driving potential (for example, about 20V) is selectively applied to each individual electrode 64 from the driver IC 89. Further, corresponding to the arrangement of the common electrode 63 and the plurality of individual electrodes 64 in this manner, the portions sandwiched between the common electrode 63 and the individual electrodes 64 of the piezoelectric layer 62 are respectively. It is polarized in the thickness direction.

Then, in the piezoelectric actuator 22, a potential is applied to the individual electrodes 64 by the driver IC 89 to change the potential difference between the individual electrodes 64 and the common electrode 63, so that the piezoelectric layer 62 and the diaphragm 61 are in the vertical direction with the pressure chamber 51. Deform the part that overlaps with. As a result, the pressure of the ink in the pressure chamber 51 fluctuates, and the ink can be ejected from the nozzle 10 communicating with the pressure chamber 51. Further, in the present embodiment, in the piezoelectric actuator 22, any of large balls, medium balls, and small balls, which are ink droplets having different volumes from the nozzle 10, is obtained by making the drive waveform for applying the electric potential to the individual electrodes 64 different. Can be selectively discharged. Here, the medium ball has a larger volume than the small ball, and the large ball has a larger volume than the medium ball.

<Electrical configuration of printer>
Next, the electrical configuration of the printer 1 will be described. As shown in FIG. 6, the printer 1 includes a control device 80, and the operation of the printer 1 is controlled by the control device 80. The control device 80 includes a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a flash memory 84, an ASIC (Application Specific Integrated Circuit) 85, and the like. The control device 80 controls the operation of the carriage motor 86, the driver IC 89, the conveyor motor 87, the cap elevating mechanism 88, the suction pump 72, the high voltage power supply circuit 77, and the like. In the present embodiment, the control device 80 controls the inkjet head 4 by controlling the driver CI 89.

Further, a signal corresponding to whether or not the nozzle is a non-ejection nozzle is input from the determination circuit 78 to the control device 80. In addition to the above configuration, the printer 1 includes a display unit 69 and an operation unit 70 (the "signal input unit" of the present invention). The display unit 69 is a liquid crystal display or the like, and the control device 80 controls the display unit 69 to display information, messages, and the like related to the operation of the printer 1. The operation unit 70 is a button provided on the printer 1, a touch panel provided on the display unit 69, or the like. When the user operates the operation unit 70, a signal corresponding to the operation is input to the control device 80.

In the control device 80, only the CPU 81 may perform various processes, only the ASIC 85 may perform various processes, or the CPU 81 and the ASIC 85 cooperate with each other to perform various processes. It may be a thing. Further, the control device 80 may be one in which one CPU 81 performs processing independently, or one in which a plurality of CPUs 81 share the processing. Further, in the control device 80, one ASIC 85 may perform the processing independently, or a plurality of ASIC 85s may share the processing.

<Control during recording>
Next, the process of recording on the recording paper P in the printer 1 will be described. In the printer 1, as will be described in detail later, by moving the carriage 2 in the scanning direction, the inkjet head 4 and the recording paper P are relatively moved in the scanning direction, and the inkjet head 4 is moved from a plurality of nozzles 10. By repeating the recording path of ejecting ink toward the recording paper P to record an image portion that is a part of the image and the transport operation of transporting the recording paper P by a predetermined distance in the transport direction, the recording paper P is fed. Record the image.

Then, in the printer 1, when a recording command instructing to perform recording is input, the control device 80 performs processing according to the flow of FIG. 7. More specifically, when the recording command is input, the control device 80 first executes the paper feed process (S101). In the paper feeding process of S101, the control device 80 controls the transport motor 87 and the paper feed device (not shown) to transfer the recording paper P to the transport rollers 6 and 7 and the paper feed device (not shown) for the first time. The area where the image portion is recorded in the recording path is supplied to a position facing the plurality of nozzles 10 of the inkjet head 4.

Subsequently, the control device 80 waits until the image data (image data for one pass) of the image portion corresponding to one recording pass is input (S102: NO). Here, in the present embodiment, following the recording command, the image data of the image portion corresponding to each recording path is sequentially input to the printer 1. Further, the image data is data that indicates the type of ink droplet (large ball, medium ball, small ball) that forms each dot of the image portion. In the present embodiment, the image data of the image portion corresponding to each recording path corresponds to the "discharge data" of the present invention.

Then, when the image data for one pass is input (S102: YES), the control device 80 has a duty D when the recording pass is performed for each nozzle row 9 based on the input image data. It is determined whether or not it is higher than the threshold value D1 (S103).

Here, in the present embodiment, the duty D is an actual plurality of nozzles in the recording path with respect to the amount of ink ejected when large balls are continuously ejected from all the nozzles 10 constituting the nozzle row 9 in the recording path. It is the ratio of the actual ink ejection amount to the maximum ink ejection amount per unit time, which is determined by the ratio of the ink ejection amount from 10.

Further, the value of the threshold value D1 for each nozzle row 9 is stored in the flash memory 84. Then, in S103, the control device 80 calculates the value of the duty D for each nozzle row 9 based on the input image data, and the calculated duty D is higher than the threshold value D1 stored in the flash memory 84. Judge whether or not.

When the duty D is equal to or less than the threshold value D1 in all the nozzle rows 9 (S103: NO), the control device 80 executes the recording path process (S104) and proceeds to S108. In the recording path of S104, the control device 80 controls the carriage motor 86 to move the carriage 2 in the scanning direction, controls the driver IC 89, and inks from the plurality of nozzles 10 of the inkjet head 4 based on the image data. Is ejected to cause the recording paper P to perform a recording pass in which an image portion corresponding to the image data is recorded. As a result, when the duty D is equal to or less than the threshold value D1 in all the nozzle rows 9, the image portion corresponding to the image data for one pass is recorded by one recording pass.

When the duty D is higher than the threshold value D1 in any of the nozzle rows 9 (S103: NO), the control device 80 executes the data division process (S105). In the data division process of S105, the control device 80 divides the input image data for one pass into a plurality of divided data. As a result, the duty D when the recording path is performed based on each divided data becomes the threshold value D1 or less. Since the division of the image data for one pass is the same as in the conventional case, further detailed description thereof will be omitted here.

Subsequently, the control device 80 executes the recording path processing (S106). In the recording path of S106, the control device 80 controls the carriage motor 86 to move the carriage 2 in the scanning direction, and controls the driver IC 89 based on the divided data to eject ink from the plurality of nozzles 10 of the inkjet head 4. By ejecting the data, the recording paper P is made to perform a recording path in which the image portion corresponding to the divided data is recorded.

Subsequently, when the recording of the image portion corresponding to all the divided data is not completed (S107: NO), the process returns to S106 and the recording path processing is executed based on the next divided data. Then, when the recording of the image portion corresponding to all the divided data is completed (S107: YES), the process proceeds to S108. As a result, when the duty D is higher than the threshold value D1 in any of the nozzle rows 9, the image portion corresponding to the image data for one pass has a duty of the threshold value D1 or less, and a plurality of consecutive recording passes. Recorded by. In the present embodiment, the treatments of S105 to S107 correspond to the "restriction treatment" of the present invention.

In S108, it is determined whether or not the recording of the image on the recording paper P is completed. If the recording of the image on the recording paper P is not completed (S108: NO), the control device 80 executes the transfer process (S109) and returns to S102. In the transfer process of S109, the control device 80 controls the transfer motor 87 to perform the transfer operation.

Then, when the recording of the image on the recording paper P is completed (S108: YES), the control device 80 executes the paper ejection process (S110) and then ends the process. In the paper ejection process of S110, the control device 80 controls the transfer motor 87 to cause the transfer rollers 6 and 7 to discharge the recording paper P.

<Processing when a purge instruction signal is input>
Next, in the printer 1, the processing flow of the control device 80 when the user operates the operation unit 70 to input a purge instruction signal instructing the suction purge to be performed will be described. When the purge instruction signal is input, the control device 80 performs processing according to the flow of FIG.

Explaining the flow of FIG. 8 in more detail, the control device 80 first executes the discharge determination process (S201). In the ejection determination process of S201, the control device 80 drives the carriage motor 86 to move the carriage 2 to the maintenance position, and then ejects ink from the nozzles 10 of each of the plurality of nozzles 10 of the inkjet head 4. The driver IC 89 (inkjet head 4) is driven as described above, and it is determined whether or not the nozzle 10 is a non-ejection nozzle based on the signal output from the determination circuit 78 as described above. Information on whether or not each nozzle 10 is a non-ejection nozzle is stored in, for example, a flash memory 84 or the like.

Subsequently, the control device 80 determines whether or not there is a non-ejection nozzle among the plurality of nozzles 10 of the inkjet head 4 based on the result of the ejection determination process (S202). If there is no non-ejection nozzle (S202: NO), the process ends as it is.

When there is a non-ejection nozzle (S202: YES), the control device 80 subsequently sets the nozzle 10 on the most downstream side in the transport direction among the plurality of nozzles 10 constituting the nozzle row 9 in all the nozzle rows 9. It is determined whether or not all the predetermined number (for example, 10) nozzles 10 which are arranged consecutively including 10 are non-ejection nozzles (S203).

Here, among the plurality of individual flow paths 41 constituting the nozzle row 29, the individual flow path 41 on the most downstream side in the transport direction is the individual flow path 41 among the plurality of individual flow paths 41 constituting the nozzle row 29. The linear distance between the connection port 53a of the throttle flow path 53 and the supply port 42a of the common flow path 42 is longer than that of the individual flow paths 41 other than the above. As a result, among the plurality of individual flow paths 41 constituting the nozzle row 29, the individual flow path 41 on the most downstream side in the transport direction is the supply port 42a among the plurality of individual flow paths 41 constituting the nozzle row 29. The flow path length from is the longest. Among the plurality of nozzles 10 constituting the nozzle row 9, the nozzle 10 on the most downstream side in the transport direction is the nozzle 10 forming the individual flow path 41 having the longest flow path length from the supply port 42a.

In all the nozzle rows 9, when at least a part of the predetermined nozzles 10 among the plurality of nozzles 10 constituting the nozzle row 9 is not a non-ejection nozzle (S203: NO), the control device 80 is described above. The weak purge process for performing the weak purge is executed (S204), and the process is terminated.

In any of the nozzle rows 9, when all of the predetermined nozzles 10 among the plurality of nozzles 10 constituting the nozzle row 9 are non-ejection nozzles (S203: YES), the control device 80 is described above. A strong purge process for performing a strong purge is executed (S205). Subsequently, the control device 80 sets the threshold value D1 stored in the flash memory 84 for the nozzle row 9 in which all the predetermined nozzles 10 are non-ejection nozzles at the time of recording on the recording sheet P last time. The value is changed to the maximum duty value among the plurality of duties lower than the current threshold value D1 (S206), and the process is terminated.

As described above, the cap 71 covers a plurality of nozzles 10 constituting the nozzle row 9 for ejecting black ink and a portion covering the plurality of nozzles 10 constituting the nozzle row 9 for ejecting color ink. When the caps 71 are provided separately for each nozzle row 9, the strong purge and the weak purge may be performed as follows. That is, a strong purge may be performed as a suction purge for ejecting ink from a plurality of nozzles 10 constituting a nozzle row 9 in which the predetermined number of nozzles 10 are all non-ejection nozzles. Further, if there is a non-ejection nozzle and at least a part of the predetermined number of nozzles 10 is not a non-ejection nozzle, a weak purge is performed as a suction purge for ejecting ink from a plurality of nozzles 10 constituting a nozzle row 9. good.

<Processing of threshold change during standby>
Further, in the printer 1, the control device 80 performs processing according to the flow of FIG. 9 during standby when recording on the recording paper P is not performed while the power is being supplied.

To explain the flow of FIG. 9 in more detail, the control device 80 stands by in all the nozzle rows 9 while D1 is changed within a predetermined period (S301: NO). In any of the nozzle rows 9, when D1 has not been changed for a predetermined period or longer (S301: YES), the control device 80 controls the carriage motor 86 to move the carriage 2 to the maintenance position, and then the driver. The nozzle of the inkjet head 4 is driven so that the duty in the nozzle row 9 becomes equal to the duty (D1 + ΔD) (D1 + ΔD) which is a predetermined value ΔD larger than the current threshold value D1 (“test duty” of the present invention). Ink is ejected from a plurality of nozzles 10 forming the row 9 (S302). In the present embodiment, the ejection of ink from the plurality of nozzles 10 in S302 corresponds to the "test ejection" of the present invention.

Subsequently, the control device 80 executes the same discharge determination process as in S201 described above for the plurality of nozzles 10 constituting the nozzle row 9 (S303). Then, based on the result of the ejection determination process of S303, when all of the predetermined nozzles 10 among the plurality of nozzles 10 constituting the nozzle row 9 are non-ejection nozzles (S304: YES), S205. After executing the same strong purge process (S305), the process returns to S301. When at least a part of the predetermined nozzles 10 in the nozzle row 9 is not a non-ejection nozzle (S304: NO), the threshold value D1 for the nozzle row 9 stored in the flash memory 84 is set to (D1 + ΔD). Change (S306) and return to S301.

<Effect>
In the present embodiment, when the duty D indicated by the image data corresponding to the recording path is higher than the threshold value D1, the divided data obtained by dividing the image data is generated. Then, in the recording pass, ink is ejected from a plurality of nozzles 10 based on the divided data to reduce the amount of ink ejected in the recording pass, and the number of recording passes in which the ink is ejected toward the same area of the recording paper P. To increase. As a result, it is possible to prevent the so-called underrefill, in which the amount of ink ejected per unit time during recording becomes equal to or less than the threshold value D1 and the ink supply to the inkjet head 4 becomes insufficient.

Further, in the present embodiment, since the structures of the plurality of individual flow paths 41 are all the same, the flow path resistances of the plurality of individual flow paths 41 are all the same. Then, the flow path resistance of the flow path from the supply port 42a to the nozzle 10 is different among the plurality of individual flow paths 41. In the inkjet head 4 having such a structure, when underrefill occurs, a plurality of continuously arranged nozzles 10 including the individual flow path 41 having the longest flow path length from the supply port 42a are all non-ejection nozzles. It is known to be. Therefore, in the present embodiment, it is determined whether or not each of the plurality of nozzles 10 is a non-ejection nozzle by the discharge determination process. Then, in any of the nozzle rows 9, when the predetermined number of nozzles 10 arranged continuously on the downstream side in the transport direction are all non-ejection nozzles, the threshold value D1 for the nozzle row 9 is reduced. As a result, the threshold value D1 is set to a large value so that the frequency of performing the limiting process for reducing the ink ejection amount per unit time as described above is made as low as possible, and the underrefill actually occurs. Sometimes, the threshold value D1 can be reduced, and finally, the threshold value D1 can be set to an appropriate value according to the usage environment and the like.

Further, in the present embodiment, the plurality of individual flow paths 29 are arranged in the transport direction, whereas the common flow path 42 extends in the transport direction. Therefore, among the plurality of individual flow paths 41 constituting the nozzle row 29, the individual flow path 41 having the longest linear distance from the supply port 42a of the connection port 53a is the individual flow path having the longest flow path length from the supply port 42a. As the road 41, it can be determined whether or not the under refill has occurred as described above.

Further, in the present embodiment, when under refill occurs, the non-ejection of ink from the nozzle 10 can be eliminated by performing suction purging. Here, when the under refill is occurring, the amount of air entering the inkjet head 4 is large. Therefore, in the present embodiment, the nozzles are non-ejection nozzles, and at least a part of the predetermined nozzles 10 is not non-ejection nozzles in all the nozzle rows 9, that is, the case where underfilling does not occur. To perform a weak purge. On the other hand, in any of the nozzle rows 9, when all of the predetermined nozzles 10 are non-ejection nozzles, that is, when underrefill occurs, the strong purge has a larger ink discharge amount than the weak purge. To do. From these facts, it is possible to surely recover the non-ejection nozzle and prevent the ink from being ejected more than necessary by the suction purge.

The purge instruction signal instructing the user to perform suction purging is input, for example, when the image quality of the recorded image is significantly deteriorated. In such a case, the inkjet head 4 There is a high possibility that underfilling has occurred in. Therefore, in the present embodiment, when the purge instruction signal is input by the operation of the operation unit 70 of the user, the discharge determination process is executed, and based on the result, the predetermined number of nozzles 10 are non-discharge nozzles. After determining whether or not, suction purging is performed. Then, when it is determined that the predetermined number of nozzles 10 are non-ejection nozzles, the threshold value D1 is reduced.

Further, when it is determined that all the predetermined nozzles 10 are non-ejection nozzles after recording on the recording paper P, the ink is ejected with a high duty at the time of recording on the recording paper P immediately before. There is a high possibility that underfilling has occurred. Therefore, in the present embodiment, in such a case, the threshold value D1 is set to the maximum duty value among the plurality of duties lower than the current threshold value D1 at the time of recording on the immediately preceding recording paper P. Thereby, the threshold value D1 can be reduced by an appropriate amount.

Further, when the threshold value D1 has not been changed for a long period of time, the threshold value D1 is set to a value smaller than necessary, and the frequency of performing the limitation processing for reducing the ink ejection amount per unit time as described above is high. It may be higher than necessary. Therefore, in the present embodiment, when the threshold value D1 is not changed for a predetermined period or longer, the ink is ink from the plurality of nozzles 10 of the inkjet head 4 so that the duty value becomes equal to higher than the current threshold value D1 (D1 + ΔD). After performing a test discharge, the discharge determination process is executed. Then, the threshold value D1 for the nozzle row 9 determined that at least a part of the predetermined nozzles 10 is not a non-ejection nozzle is changed to (D1 + ΔD). As a result, the limiting process is not executed more than necessary, and the time required for recording on the recording paper P can be shortened.

Further, in the present embodiment, when the inkjet head 4 is driven so as to eject ink from the nozzle 10 with the nozzle 10 and the detection electrode 76 facing each other, the signal output from the determination circuit 78 is obtained. Based on this, it can be determined whether or not the nozzle 10 is a non-ejection nozzle.

<Modification example>
Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made as long as it is described in the claims.

In the above-described embodiment, when the duty D in the recording pass is higher than the threshold value D1, the amount of ink ejected in one recording pass is reduced, and the image portion is formed by a plurality of recording passes in the same area of the recording paper P. The duty is set to be equal to or less than the threshold value D1 by recording, but the duty is not limited to this.

In the first modification, in the printer 1, when recording on the recording paper P, the control device 80 performs processing according to the flow of FIG. More specifically, the control device 80 executes the processes of S401 to S403 similar to those of S101 to S103 of the above-described embodiment.

Then, when the duty D is determined to be equal to or less than the threshold value D1 in all the nozzle rows 9 in S403 (S403: NO), the control device 80 sets the standby time Tw between the recording paths to Tw1 (S404). On the other hand, when it is determined in S403 that the duty D is higher than the threshold value D1 in any of the nozzle rows 9 (S403: YES), the control device 80 sets the standby time Tw to Tw2, which is longer than Tw1 (S403: YES). S405).

After setting the standby time Tw in S404 or S405, the control device 80 executes the same recording path processing as in S104 of the above-described embodiment (S406). Subsequently, when the recording is not completed (S407: NO), the same transport process as in S109 of the above-described embodiment is executed (S408), and the waiting time Tw elapses (S409: NO). When the waiting time Tw has elapsed (S409: YES), the process returns to S402. When the recording is completed (S407: YES), the control device 80 executes the same paper ejection process as S110 of the above-described embodiment (S410), and ends the process.

In the first modification, when the duty D in any nozzle row 9 in the recording path is higher than the threshold value D1, the waiting time Tw between the recording path and the next recording path is increased to increase the waiting time Tw per unit time. The amount of ink ejected from the ink can be reduced so that the duty is set to the threshold value D1 or less. In the first modification, the process of setting the standby time Tw to Tw2, which is longer than Tw1 in S405, and lengthening the time standby Tw in S409 corresponds to the "restriction process" of the present invention.

In the second modification, in the printer 1, when recording on the recording paper P, the control device 80 performs processing according to the flow of FIG. More specifically, the control device 80 executes the processes of S501 to S503 similar to those of S101 to S103 of the above-described embodiment.

Then, when it is determined in S503 that the duty D in all the nozzle rows 9 is equal to or less than the threshold value D1 (S503: NO), the control device 80 sets the moving speed U of the carriage 2 in the recording path to U1. The drive frequency F of the inkjet head 4 in the recording path is set to F1 (S504). On the other hand, when it is determined in S503 that the duty D is higher than the threshold value D1 in any of the nozzle rows 9 (S503: YES), the control device 80 sets the moving speed U of the carriage 2 in the recording path to be higher than U1. The slow U2 is set, and the drive frequency F of the inkjet head 4 in the recording path is set to F2 lower than F1 in accordance with this (S505).

After setting the mobile phase U of the carriage 2 and the drive frequency F of the inkjet head 4 in the recording path in S504 or S505, the control device 80 executes the same recording path processing as in S104 of the above-described embodiment (S506). ). However, in the recording path processing of S506, the control device 80 controls the carriage motor 87 to move the carriage 2 at the moving speed U set in S504 or S505. Further, in the recording path processing of S506, the control device 80 controls the driver IC 89 to drive the inkjet head 4 at the drive frequency F set in S504 or S505, and ejects ink from a plurality of nozzles 10.

As a result, ink is ejected from the plurality of nozzles 10 at the ejection cycle of (1 / F). Therefore, the discharge cycle (1 / F2) when the drive frequency is set to F2 is longer than the discharge cycle (1 / F1) when the drive frequency is set to F1.

Subsequently, when the recording is not completed (S507: NO), the same transport process as in S109 of the above-described embodiment is executed (S508), and the process returns to S502. When the recording is completed (S507: YES), the control device 80 executes the same paper ejection process as S110 of the above-described embodiment (S509), and ends the process.

In the second modification, when the duty D is higher than the threshold value D1 in any of the nozzle rows 9, the moving speed U (relative moving speed between the inkjet head 4 and the recording paper P) of the carriage 2 in the recording path is slowed down. By lowering the drive frequency F of the inkjet head 4 (longer ejection cycle (1 / F)) in accordance with this, the amount of ink ejected per unit time can be reduced and the duty can be set to the threshold value D1 or less. .. In the second modification, the moving speed U is set to U2 in S505, the driving frequency F is set to F2, and the inkjet head 4 is moved to F2 while moving the carriage 2 at the moving speed of U2 in the recording path of S506. Discharge cycle of driving at the drive frequency of (1 / F2) The process of ejecting ink from a plurality of nozzles 10 corresponds to the "restriction process" of the present invention.

Further, the amount of ink ejected from the plurality of nozzles 10 of the inkjet head 4 per unit time may be reduced by a method different from the above-described embodiments and modifications 1 and 2.

Further, in the above-described embodiment, the inkjet head 4 is driven so that the duty becomes equal to higher than the current threshold value D1 (D1 + ΔD) when the threshold value D1 is not changed for a predetermined period or more during the standby mode of the printer 1. In any of the nozzle rows 9, the threshold value D1 was changed to (D1 + ΔD) when at least a part of the predetermined nozzles 10 was not a non-ejection nozzle, but the present invention is not limited to this.

In the third modification, the control device 80 performs processing according to the flow of FIG. 12 in the printer 1 during standby when recording on the recording paper P is not performed while the power is being supplied.

To explain the flow of FIG. 12 in more detail, the control device 80 stands by in all the nozzle rows 9 while D1 is changed within a predetermined period (S601: NO). Then, in any of the nozzle rows 9, when D1 has not been changed for a predetermined period or longer (S601: YES), the control device 80 controls the carriage motor 86 to move the carriage 2 to the maintenance position. , The driver IC 89 is driven to eject ink from a plurality of nozzles 10 constituting the nozzle row 9 of the inkjet head 4 so that the duty becomes equal to the current threshold value D1 (S602). In the third modification, the ejection of ink from the plurality of nozzles 10 in S602 corresponds to the "test ejection" of the present invention.

Subsequently, the control device 80 executes the same discharge determination process as in S303 described above (S603). Then, based on the result of the ejection determination process of S603, when all of the predetermined nozzles 10 among the plurality of nozzles 10 constituting the nozzle row 9 are non-ejection nozzles (S604: YES), the same as in S305. After executing the strong purge process of (S605), the process returns to S601. When at least a part of the predetermined nozzles 10 in the nozzle row 9 is not a non-ejection nozzle (S604: NO), the threshold value D1 stored in the flash memory 84 is increased by a predetermined amount (S606) to S601. return.

In the third modification, when the threshold value D1 is not changed for a predetermined period or longer, a test ejection is performed to eject ink from a plurality of nozzles 10 of the inkjet head 4 so that the duty becomes equal to the current threshold value D1, and the ejection determination is made. Execute the process. Then, when it is determined that the predetermined number of nozzles 10 are not non-ejection nozzles, the threshold value D1 is increased. As a result, the limiting process is not executed more than necessary, and the time required for recording on the recording paper P can be shortened.

Further, when the threshold value D1 has not been changed for a predetermined time or more, a process for increasing the threshold value D1 may be performed, which is different from the above-described embodiment and modification 3. Alternatively, when the threshold value D1 has not been changed for a predetermined time or longer, it is not necessary to perform the process for increasing the threshold value D1 as in the above-described embodiment and modification 3.

Further, in the above-described embodiment, the purge instruction signal is input based on the operation of the operation unit 70 of the printer 1 by the user, but the present invention is not limited to this. For example, the printer may be connected to a PC, and the printer may be purged and an instruction signal may be input based on the operation of the PC by the user. In this case, the interface unit (not shown) for connecting the printer to the PC corresponds to the "signal input unit" of the present invention.

Further, in the above-described embodiment, when the purge instruction signal is input according to the user's instruction, the ejection determination process is executed, and the predetermined number of nozzles 10 constituting any of the nozzle rows 9 are non-ejection nozzles. In some cases, the threshold D1 was changed to the highest duty value among the plurality of duty lower than the current threshold D1 at the time of the previous recording, but the present invention is not limited to this.

For example, in such a case, the threshold value D1 is determined based on the maximum duty value, not the maximum duty value itself among the plurality of duty values lower than the threshold value D1 at the time of the previous recording. It may be changed to the value of.

Alternatively, for example, when the predetermined number of nozzles 10 are non-ejection nozzles in any of the nozzle rows 9, the threshold value D1 for the nozzle row 9 is changed from the current value to a value that is a certain amount smaller. May be good.

Further, the discharge determination process as described above may be executed at a timing different from that when the purge instruction signal is input, and the threshold value D1 may be changed based on the result. For example, when a recording command is input, a discharge determination process is executed, a process of changing the threshold value D1 based on the result is performed, and then a process as shown in the flows of FIGS. 7, 10, and 11 is performed. You may do it.

Further, in the above-described embodiment, there are non-ejection nozzles, and in all the nozzle rows 9, at least a part of the predetermined number of nozzles 10 is not a non-ejection nozzle, that is, underfilling does not occur. In that case, a weak purge is performed. On the other hand, when there are non-ejection nozzles and all of the predetermined nozzles 10 among the plurality of nozzles 10 constituting any of the nozzle rows 9 are non-ejection nozzles, that is, underrefill occurs. In some cases, a strong purge is performed. However, it is not limited to this. When there is a non-ejection nozzle, the same type of suction purge may be performed regardless of whether or not underrefill has occurred.

Further, in the above-described embodiment, suction purging is performed as purging, but the present invention is not limited to this. For example, a pressure pump may be provided in the middle of the tube 15 that connects the sub tank 3 and the ink cartridge 15. Alternatively, the printer may be provided with a pressurizing pump connected to the ink cartridge. Then, in a state where the plurality of nozzles 10 are covered with the caps 71, the pressure pump is driven to pressurize the ink in the inkjet head 4 and discharge the ink in the inkjet head 4 from the nozzles 10, so-called. Pressurized purging may be performed. In this case, the combination of the cap 71 and the pressurizing pump corresponds to the "purge means" of the present invention.

Further, in purging, both suction by the suction pump 72 and pressurization by the pressurizing pump may be performed. In this case, the combination of the maintenance unit 8 and the pressurizing pump corresponds to the "purge means" of the present invention.

Further, in the above-described embodiment, when it is determined that the underrefill has occurred, the purge is immediately performed, but the present invention is not limited to this. After it is determined that the underrefill has occurred, another operation may be performed before purging.

Further, in the above-described embodiment, the common flow path 42 extends in the transport direction, and the linear distance between the connection port 53a and the supply port 42a among the plurality of individual flow paths 41 constituting the individual flow path rows 29 is set. The longest individual flow path 41 is the individual flow path 41 having the longest flow path length from the supply port 42a, but is not limited to this. For example, the common flow path 42 meanders and extends, and among the plurality of individual flow paths 41 constituting the individual flow path rows 29, the individual flow path 41 having the longest linear distance between the connection port 53a and the supply port 42a. The individual flow path 41 other than the above may be the individual flow path 41 having the longest flow path length from the supply port 42a.

Further, in the above-described embodiment, whether or not the nozzle is a non-ejection nozzle is determined from the determination circuit 78 according to the voltage value of the detection electrode 76 when ink is ejected from the nozzle 10 toward the detection electrode 76. The corresponding signal was output, but it is not limited to this.

For example, when a detection electrode extending in the vertical direction is arranged and ink is ejected from the nozzle 10 so as to pass through a region facing the detection electrode, the determination circuit can be used according to the voltage value of the detection electrode. A signal may be output depending on whether or not the nozzle is a non-ejection nozzle. Alternatively, an optical sensor (“signal output unit” of the present invention) for detecting the ink ejected from the nozzle 10 may be provided, and a signal depending on whether or not the nozzle is non-ejection may be output from the optical sensor.

Alternatively, for example, a voltage detection circuit (the present invention) for detecting a change in voltage when ink is ejected from a plate on which an inkjet head nozzle is formed, as described in Japanese Patent No. 492969. The "signal output unit" of the present invention) may be connected to output a signal from the voltage detection circuit to the control device 80 depending on whether or not the nozzle is a non-ejection nozzle.

Alternatively, for example, the substrate of the inkjet head may be provided with a temperature detection element (“signal output unit” of the present invention) as described in Japanese Patent No. 6231759. Then, after applying the first applied voltage to drive the heater for ink ejection, the second applied voltage is applied to drive the heater so that the ink is not ejected, and then the second applied voltage is applied. After that, a signal depending on whether or not the nozzle 10 is a non-ejection nozzle may be output based on the change in temperature detected by the temperature detecting element until a predetermined time elapses. ..

Furthermore, the printer is not limited to having a signal output unit that outputs a signal according to whether or not the printer is a non-ejection nozzle. For example, a predetermined test pattern may be recorded in the printer, and a signal (“discharge information” of the present invention) according to whether or not the nozzle is a non-ejection nozzle may be input based on the recording result of the test pattern. In this case, for example, by having the user operate the operation unit 70 based on the recording result of the test pattern, a signal (“discharge information” of the present invention) corresponding to whether or not the nozzle is a non-discharge nozzle may be input. good. Alternatively, when the printer is a so-called multifunction device equipped with a scanner, the scanner is made to read the test pattern, and a signal according to whether or not the printer is a non-ejection nozzle based on the reading result of the test pattern (the “) of the present invention). Discharge information ") may be input.

Further, in the above example, the duty D in the recording path and the threshold value D1 are directly compared, and when the duty D is higher than the threshold value D1, the amount of ink ejected from the plurality of nozzles 10 per unit time is reduced. However, it is not limited to this. For example, when another predetermined condition corresponding to the duty D being higher than the threshold value D1 is satisfied, the amount of ink ejected from the plurality of nozzles 10 per unit time may be reduced.

Further, in the above example, the supply port 42a is provided at the upstream end of the common flow path 42 in the transport direction, but the present invention is not limited to this. The supply port may be provided in another part of the common flow path 42. Then, in this case, among the plurality of individual flow paths 41 connected to the common flow path 42, the nozzles constituting a predetermined number of individual flow paths 41 that are continuously arranged, including the individual flow path farthest from the supply 42a. It may be determined whether or not underrefill is occurring based on whether or not all 10 are non-ejection nozzles.

Further, in the above, an example in which the present invention is applied to a printer provided with a so-called serial type inkjet head 4 that ejects ink from a plurality of nozzles 10 while moving in the scanning direction together with the carriage 2 has been described. Not limited.

For example, it is also possible to apply the present invention to a printer provided with a so-called line head in which a plurality of nozzles 10 are arranged in the scanning direction over the entire length of the recording paper P. In a printer equipped with a line head, the line head and the recording paper P are relatively moved in the transport direction by transporting the recording paper in the transport direction, and ink is ejected from a plurality of nozzles of the line head to discharge the recording paper. Images can be recorded on paper. Then, for example, when the duty of each portion of the recording paper P in the transport direction of the recorded image is higher than the threshold value, the transport speed of the recording paper (relative moving speed between the line head and the recording paper) is slowed down. In line with this, the drive frequency of the line head is lowered (the ink ejection cycle is lengthened) to reduce the amount of ink ejected per unit time.

Further, in this case, among the plurality of individual flow paths connected to the common flow path of the line head, a predetermined number of individual flow paths including the individual flow path farthest from the ink supply port to the common flow path are continuously arranged. When all the nozzles constituting the flow path are non-ejection nozzles, it is determined that underrefill has occurred.

In this case, the transport roller that transports the recording paper in the transport direction corresponds to the "relative moving means" of the present invention, and the transport speed of the recording paper corresponds to the "relative moving speed" of the present invention. Further, the transport direction corresponds to the "first direction" of the present invention, and the scanning direction corresponds to the "second direction" of the present invention.

Further, in the above example, the ink stored in the removable ink cartridge is supplied to the inkjet head, but the present invention is not limited to this. For example, the ink that is fixed to the printer 1 so as not to be removed and stored in the tank having the replenishment port for replenishing the ink may be supplied to the inkjet head.

Further, in the above, an example in which the present invention is applied to a printer that ejects ink from a nozzle and records on the recording paper P has been described, but the present invention is not limited to this. It can also be applied to a printer that records an image on a recording medium other than recording paper, such as a T-shirt, a sheet for outdoor advertising, a case of a mobile terminal such as a smartphone, a corrugated cardboard, and a resin member. It can also be applied to a liquid ejection device that ejects a liquid other than ink, for example, a liquefied resin or metal.

1 Printer 2 Carriage 3 Sub tank 10 Nozzle 14 Ink cartridge 15 Tube 41 Individual flow path 42 Common flow path 42a Supply port 70 Operation unit 76 Detection electrode 77 High voltage power supply circuit 78 Judgment circuit 79 Resistance 80 Control device

Claims (12)

Liquid discharge head and
A tank for storing liquid and
A connection flow path connecting the liquid discharge head and the tank,
A relative moving means for relatively moving the liquid discharge head and the discharged medium in the first direction,
Equipped with a control device,
The liquid discharge head
A plurality of individual flow paths including nozzles and arranged in a second direction intersecting the first direction,
A common flow path connected to the plurality of individual flow paths,
It has a supply port for supplying a liquid to the common flow path, and has.
The control device is
By causing the relative moving means to move the liquid discharge head and the discharged medium relative to the first direction, and causing the liquid discharge head to discharge the liquid from the nozzles constituting the plurality of individual flow paths. , Discharge the liquid to the ejected medium,
When the duty corresponding to the ratio of the actual liquid discharge amount to the maximum liquid discharge amount per unit time in the liquid discharge head is higher than the threshold value, the predetermined condition is satisfied.
The amount of liquid discharged per unit time in the liquid discharge head is reduced to execute a limiting process for setting the duty to be equal to or less than the threshold value.
Moreover,
Upon receiving the discharge information regarding whether or not the nozzles constituting the plurality of individual flow paths are non-discharge nozzles in which the liquid is not discharged, the nozzles are received.
Based on the discharge information, among the plurality of individual flow paths, a predetermined number of the individual flow paths continuously arranged in the second direction including the farthest individual flow path having the longest flow path length from the supply port. It is determined whether or not the nozzle constituting the flow path is the non-ejection nozzle, and the nozzle is determined.
When it is determined that the nozzles constituting the predetermined individual flow paths are the non-ejection nozzles, the threshold value is reduced, and thereafter, the limitation is based on the predetermined condition according to the threshold value after the reduction. A liquid discharge device characterized in deciding whether or not to perform a process. A purging means for purging the liquid in the liquid discharging head from the plurality of nozzles is provided.
The control device is
When it is determined that the nozzles constituting the predetermined individual flow paths are the non-discharge nozzles based on the discharge information,
The liquid discharge device according to claim 1, wherein the purging means is made to perform the purging. The control device is
The purging means is allowed to selectively perform one of the first purging and the second purging in which the amount of liquid discharged is larger than that of the first purging.
Based on the discharge information, the non-discharge nozzle is included in the nozzles constituting the plurality of individual flow paths, and the nozzle forming at least a part of the predetermined individual flow paths is the nozzle. When it is determined that the nozzle is not a non-ejection nozzle, the purging means is made to perform the first purging.
The claim is characterized in that, when it is determined that the nozzles constituting the predetermined individual flow paths are the non-discharge nozzles based on the discharge information, the purging means is made to perform the second purge. 2. The liquid discharge device according to 2. A signal input unit for inputting an instruction signal instructing the user to perform the purge is provided.
The control device is
When the instruction signal is input to the signal input unit,
Before letting the purging means perform the purging
The discharge information is received, and based on the discharge information, it is determined whether or not the nozzles constituting the predetermined individual flow paths are the non-discharge nozzles.
When it is determined that the nozzles constituting the predetermined individual flow paths are the non-discharge nozzles based on the discharge information, the threshold value is reduced, and thereafter, the threshold value after the reduction is set. The liquid discharge device according to claim 2 or 3, wherein it is determined whether or not to execute the restriction process based on the above. The control device is
When it is determined that the nozzles constituting the predetermined individual flow paths are the non-discharge nozzles based on the discharge information,
Claims 1 to 4 are characterized in that the threshold value is reduced based on the maximum duty among a plurality of duty lower than the current threshold value at the time of discharging the liquid to the discharge medium immediately before. The liquid discharge device according to any one of. The control device is
When the threshold has not been changed for a predetermined period or longer
The liquid discharge head receives the discharge information after causing the liquid discharge head to perform a test discharge of discharging the liquid from the nozzles of the plurality of individual flow paths with a test duty higher than the threshold value.
When it is determined that at least a part of the nozzles constituting the predetermined individual flow paths is not the non-discharge nozzle based on the discharge information, the threshold value is changed to the value of the test duty. The liquid discharge device according to any one of claims 1 to 5. The control device is
When the threshold has not been changed for a predetermined period or longer
The liquid discharge head is subjected to a test discharge to discharge the liquid from the nozzles of the plurality of individual flow paths so that the duty value becomes equal to the current threshold value, and then the discharge information is received.
Claims 1 to 5 are characterized in that when it is determined that at least a part of the nozzles constituting the predetermined individual flow paths is not the non-discharge nozzle based on the discharge information, the threshold value is increased. The liquid discharge device according to any one of. A transport unit for transporting the ejected medium in the second direction is provided.
The relative moving means includes a carriage that mounts the liquid discharge head and moves in the first direction.
The control device is
While moving the carriage in the first direction, the liquid discharge head is made to discharge the liquid from the nozzles of the plurality of individual flow paths, and the transfer portion is made to convey the discharged medium in the second direction. By repeating the transport operation, the liquid is discharged to the discharge medium.
In the limiting process, the amount of liquid discharged in each recording pass is reduced, and the number of recording passes for discharging the liquid toward the same region of the ejected medium is increased, so that the liquid discharge head per unit time. The liquid discharge device according to any one of claims 1 to 7, wherein the liquid discharge amount of the liquid is reduced. A transport unit for transporting the ejected medium in the second direction is provided.
The relative moving means includes a carriage that mounts the liquid discharge head and moves in the first direction.
The control device is
While moving the carriage in the first direction, the liquid discharge head is made to discharge the liquid from the nozzles of the plurality of individual flow paths, and the transfer portion is made to convey the discharged medium in the second direction. By repeating the transport operation, the liquid is discharged to the discharge medium.
The claim is characterized in that, in the limiting process, the amount of liquid discharged per unit time in the liquid discharge head is reduced by increasing the waiting time between the recording path and the next recording path. The liquid discharge device according to any one of 1 to 7. The control device is
In the limiting process, the relative moving speed of the liquid discharge head and the discharged medium is slowed down by the relative moving means, and the plurality of individual flows are sent to the liquid discharge head according to the slowed relative moving speed. The invention according to any one of claims 1 to 7, wherein the discharge amount of the liquid per unit time in the liquid discharge head is reduced by lengthening the discharge cycle for discharging the liquid from the nozzles constituting the path. Liquid discharge device. A signal output unit that outputs a signal as the discharge information according to whether or not the nozzle is the non-discharge nozzle to the control device is provided.
The control device is
The liquid discharge head is driven so as to discharge the liquid from each of the nozzles for at least a part of the plurality of individual flow paths.
The liquid discharge device according to any one of claims 1 to 10, wherein it is determined whether or not the nozzle is the non-discharge nozzle based on the signal from the signal output unit. The common flow path extends in the second direction,
Each of the plurality of individual flow paths includes a connection port connected to the common flow path, and includes a connection port.
The connection port of the individual flow path having the longest flow path length from the supply port is the supply port as compared with the connection port of the individual flow path other than the individual flow path in the plurality of individual flow paths. The liquid discharge device according to any one of claims 1 to 11, wherein the linear distance from the liquid is long.

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