Liquid dispensing device

Abstract

To adequately perform a recovery action for recovering an abnormal nozzle even if large temperature change occurs.SOLUTION: A liquid discharge device performs an inspection drive (S105), and stores first abnormal nozzle information and first temperature information (S107) when there is an abnormal nozzle (S106: YES). Thereafter, when receiving a recording command (S108: YES), the device performs a recovery action set on the basis of the first abnormal nozzle information (S110, S113) in the case where a temperature range including a temperature at the time of receiving the recording command is the same as a temperature range including a temperature indicated by the first temperature information (S109: NO). When the temperature range including the temperature at the time of receiving the recording command is different from the temperature range including the temperature indicated by the first temperature information (S109: YES), the device performs the inspection drive again (S111) to acquire second abnormal nozzle information, and performs a recovery action set on the basis of the acquired second abnormal nozzle information (S112, S113).SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a liquid discharge device that discharges a liquid from a nozzle.

Background Art

[0002] As an example of a liquid discharge device that discharges a liquid from a nozzle, Patent Document 1 describes an inkjet printer that discharges ink droplets from a nozzle. In the printer described in Patent Document 1, a nozzle inspection process for inspecting whether ink droplets are normally discharged from the nozzle is executed, and when an abnormal nozzle is found, the type of cleaning is determined based on the result of the nozzle inspection process.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an inkjet printer such as Patent Document 1, when the temperature changes, the viscosity of the ink in the head changes, and the state of whether it is an abnormal nozzle may change. Further, after the execution of the nozzle inspection process, if a certain period of time elapses until cleaning is performed, for example, when another process is performed, the temperature may change significantly during this period. In this case, if cleaning is performed based on the result of the nozzle inspection process before the temperature change, there is a risk that the cleaning may not be appropriate.

[0005] An object of the present invention is to provide a liquid discharge device capable of appropriately performing a recovery operation for recovering an abnormal nozzle even when there is a large temperature change.

Means for Solving the Problems

[0007] Furthermore, the liquid dispensing device of the present invention dispenses liquid multiple The device comprises a liquid discharge head having a nozzle, a determination signal output unit that outputs a determination signal corresponding to each of the plurality of nozzles when the liquid discharge head is made to perform an inspection drive to check whether the nozzle is an abnormal nozzle with an abnormality in liquid discharge, a recovery means that performs a recovery operation to discharge liquid from the nozzle, a temperature signal output unit that outputs a temperature signal indicating the temperature, a storage unit, and a control device, wherein when the liquid discharge head is made to perform the inspection drive, the control device stores first temperature information related to the temperature indicated by the temperature signal output from the temperature signal output unit, and abnormality related to the abnormal nozzle based on the determination signal output from the determination signal output unit. Nozzle information and are stored in the storage unit, and thereafter, each time the first temperature information stored in the storage unit and the second temperature information related to the temperature indicated by the temperature signal output from the temperature signal output unit no longer satisfy the predetermined conditions regarding the temperature difference, the liquid discharge head is made to perform the inspection drive, the first temperature information stored in the storage unit is updated based on the temperature signal output from the temperature signal output unit, the abnormal nozzle information stored in the storage unit is updated based on the determination signal output from the determination signal output unit, and thereafter, when the recovery means is made to perform the recovery operation, the recovery means is made to perform the recovery operation based on the abnormal nozzle information stored in the storage unit for the last time. [Effects of the Invention]

[0008] In this invention, even in the event of a large temperature change, a recovery operation to restore the abnormal nozzle can be performed appropriately. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a printer according to an embodiment of the present invention. [Figure 2] This diagram illustrates the detection electrode placed inside the cap, and the connection relationship between the detection electrode, the high-voltage power supply circuit, and the judgment circuit. [Figure 3] (a) is a diagram showing the change in the potential of the detection electrode when ink is ejected from the nozzle, and (b) is a diagram showing the change in the potential of the detection electrode when ink is not ejected from the nozzle. [Figure 4] This is a plan view of an inkjet print head. [Figure 5] (a) is an enlarged view of section VA in Figure 4, and (b) is a cross-sectional view of (a) along the line VB-VB. [Figure 6] This is a block diagram showing the electrical configuration of a printer. [Figure 7] This is a flowchart showing the processing flow by the control device. [Figure 8] (a) is a diagram illustrating a table relating temperature range and drive potential, and (b) is a diagram illustrating a table relating the number of abnormal nozzles and recovery actions. [Figure 9] This is a flowchart corresponding to Figure 7 in Modification Example 1. [Figure 10] This is a flowchart corresponding to Figure 7 in Modification Example 2. [Figure 11] This is a flowchart corresponding to Figure 7 in Modification Example 3. [Figure 12] This figure illustrates a table showing the relationship between the temperature range and drive waveform in Modification 4. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present invention will be described below.

[0011] <Overall printer configuration> As shown in Figure 1, the printer 1 (the "liquid ejection device" of the present invention) according to this embodiment includes a carriage 2, a sub-tank 3, an inkjet head 4 (the "liquid ejection head" of the present invention), a platen 5, transport rollers 6 and 7, a maintenance unit 8, and the like.

[0012] The carriage 2 is supported by two guide rails 11 and 12 that extend in the scanning direction. The carriage 2 is connected to a carriage motor 86 (see Figure 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 explanation, the right and left sides of the scanning direction will be defined as shown in Figure 1.

[0013] Sub-tank 3 is mounted on carriage 2. Printer 1 includes a cartridge holder 13, in which four ink cartridges 14 are removably mounted. The four ink cartridges 14 are arranged in the scanning direction, and from right to left in the scanning direction, they store black, yellow, cyan, and magenta inks (the "liquids" of this invention). Sub-tank 3 is connected to the four ink cartridges 14 mounted on cartridge holder 13 via four tubes 15. This allows the four inks of the above four colors to be supplied from the four ink cartridges 14 to sub-tank 3.

[0014] The inkjet head 4 is mounted on the carriage 2 and connected to the lower end of the sub-tank 3. The inkjet head 4 is supplied with the four colors of ink from the sub-tank 3. The inkjet head 4 also ejects ink from a plurality of nozzles 10 formed on its lower surface, the nozzle surface 4a. More specifically, the plurality of nozzles 10 are arranged in a transport direction perpendicular to the scanning direction to form a nozzle row 9, and four rows of nozzle rows 9 are arranged in the scanning direction on the nozzle surface 4a. From the plurality of nozzles 10, black, yellow, cyan, and magenta inks are ejected starting from the nozzle row 9 on the right side in the scanning direction.

[0015] The platen 5 is disposed below the inkjet head 4 and faces a plurality of nozzles 10. The platen 5 extends over the entire length of the recording paper P (the "discharge medium" of the present invention) in the scanning direction and supports the recording paper P from below. The conveyance roller 6 is disposed upstream of the inkjet head 4 and the platen 5 in the conveyance direction. The conveyance roller 7 is disposed downstream of the inkjet head 4 and the platen 5 in the conveyance direction. The conveyance rollers 6 and 7 are connected to a conveyance motor 87 (see FIG. 6) via gears and the like not shown. When the conveyance motor 87 is driven, the conveyance rollers 6 and 7 rotate, and the recording paper P is conveyed in the conveyance direction.

[0016] The maintenance unit 8 includes a cap 71, a suction pump 72, and a waste liquid tank 73. The cap 71 is disposed on the right side of the platen 5 in the scanning direction. 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.

[0017] Further, the cap 71 is movable up and down by a cap elevating mechanism 88 (see FIG. 6). When the carriage 2 is positioned at the maintenance position so that the plurality of nozzles 10 face the cap 71, and the cap 71 is raised by the cap elevating mechanism 88, the upper end portion of the cap 71 adheres to the nozzle surface 4a, and the plurality of nozzles 10 are covered by the cap 71. Note that the cap 71 is not limited to covering the plurality of nozzles 10 by adhering to the nozzle surface 4a. The cap 71 may cover the plurality of nozzles 10 by adhering to a frame or the like not shown disposed around the nozzle surface 4a of the inkjet head 4, for example.

[0018] The suction pump 72 is a tube pump or the like, and is connected to the cap 71 and the waste liquid tank 73. In the maintenance unit 8, when the suction pump 72 is driven with the multiple nozzles 10 covered by the cap 71 as described above, a so-called suction purge can be performed, which discharges the ink from the inkjet head 4 from the multiple nozzles 10. The ink discharged by the suction purge is stored in the waste liquid tank 73.

[0019] Furthermore, in this embodiment, one of three types of suction purging—weak purging, medium purging, and strong purging—can be selectively performed. Medium purging discharges more ink than weak purging, and strong purging discharges more ink than medium purging. The amount of ink discharged differs between weak purging, medium purging, and strong purging, for example, because at least one of the driving time of the suction pump 72 and the rotational speed of the suction pump 72 is different.

[0020] For convenience, the explanation here assumes that the cap 71 covers all nozzles 10 together, and that during suction purging, ink is discharged from all nozzles 10 within the inkjet head 4. However, this is not the only possible explanation. For example, the cap 71 may have separate parts: one covering multiple nozzles 10 that make up the rightmost nozzle row 9 that ejects black ink, and another covering multiple nozzles 10 that make up the left three nozzle rows 9 that eject color inks (yellow, cyan, and magenta inks). This allows for selective discharge of either black ink or color ink within the inkjet head 4 during suction purging. Alternatively, for example, the cap 71 may be provided individually for each nozzle row 9, allowing for individual discharge of ink from each nozzle 10 during suction purging.

[0021] Also, as shown in FIG. 2, a detection electrode 76 having a rectangular planar shape is disposed within the cap 71. The detection electrode 76 is connected to a high-voltage power supply circuit 77 via a resistor 79. And, during the determination drive described later, a predetermined positive potential (for example, about 600 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. Thereby, 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 potential of the signal output from the detection electrode 76 with a threshold value Vt and outputs a signal according to the result.

[0022] More specifically, since a potential difference exists between the inkjet head 4 and the detection electrode 76, the ink ejected from the nozzle 10 is charged. When the carriage 2 is positioned at the maintenance position and ink is ejected from the nozzle 10 toward the detection electrode 76, as shown in FIG. 3(a), the charged ink approaches the detection electrode 76, and until the ink lands on the detection electrode 76, the potential of the detection electrode 76 decreases from the potential Va when the inkjet head 4 is not driven and reaches a potential Vb lower than the potential Va. Then, after the charged ink lands on the detection electrode 76, the potential of the detection electrode 76 gradually rises and returns to the potential Va. That is, during the drive period Td of the inkjet head 4, the potential of the detection electrode 76 changes.

[0023] On the other hand, when no ink is ejected from the nozzle 10, as shown in FIG. 3(b), during the drive period Td of the inkjet head 4, the potential of the detection electrode 76 hardly changes from the potential Va. Therefore, a threshold value Vt (Vb < Vt < Va) is set in the determination circuit 78 to distinguish between these. And the determination circuit 78 compares the maximum potential of the voltage signal output from the detection electrode 76 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. In the present embodiment, the combination of the detection electrode 76, the high-voltage power supply circuit 77, the resistor 79, and the determination circuit 78 is the " For judgment This corresponds to the "signal output section". For judgment The signal output unit outputs a determination signal to determine whether or not the nozzle 10 is an abnormal nozzle that does not dispense ink.

[0024] In this case, a positive potential is applied to the detection electrode 76 by the high-voltage power supply circuit 77, but a negative potential (for example, around -600V) may also be applied to the detection electrode 76 by the high-voltage power supply circuit 77. In this case, contrary to the above, when ink is ejected from the nozzle 10 toward the detection electrode 76 with the carriage 2 in the maintenance position described above, the charged ink approaches the detection electrode 76, and the potential of the detection electrode 76 rises from potential Va until the ink lands on the detection electrode 76. After the ink lands on the detection electrode 76, the potential of the detection electrode 76 gradually decreases and returns to potential Va.

[0025] <Inkjet head> Next, the structure of the inkjet head 4 will be described in detail. As shown in Figures 4, 5(a), and 5(b), the inkjet head 4 has a flow channel unit 21 and a piezoelectric actuator 22.

[0026] The flow channel unit 21 is formed by stacking plates 31 to 35 vertically in that order from the bottom. The flow channel unit 21 comprises a plurality of individual flow channels 41, each containing a nozzle 10, and four common flow channels 42.

[0027] As described above, the multiple nozzles 10 form four rows of nozzles 9. In correspondence with this, the multiple individual channels 41 are arranged in the transport direction to form an individual channel row 29, and the channel unit 21 has four rows of individual channel rows 29 arranged in the scanning direction.

[0028] Each individual flow path 41 has a nozzle 10, a pressure chamber 51, a descender 52, and a throttling flow path 53. The nozzle 10 and the left end of the pressure chamber 51 in the scanning direction are connected via the descender 52, and the throttling flow path 53 is connected to the right end of the pressure chamber 51 in the scanning direction. The structure and positional relationship of the nozzle 10, pressure chamber 51, descender 52, and throttling flow path 53 are the same as in the conventional design, so further detailed explanation is omitted here.

[0029] The four common channels 42 correspond to four rows of individual channels 29, extending in the transport direction and overlapping vertically with the right-hand portion in the scanning direction of the multiple individual channels 41 that constitute the corresponding individual channel rows 29. The common channels 42 are connected to the right-hand end in the scanning direction of the aperture channels 53 that constitute these individual channels 41. Ink is supplied to each common channel 42 from a supply port 42a located at the upstream end in the transport direction.

[0030] The piezoelectric actuator 22 includes 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 mainly composed of lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, and is placed on the upper surface of the flow channel unit 21 (the upper surface of the plate 35) and covers a plurality of pressure chambers 51. The piezoelectric layer 62 is made of the above-mentioned piezoelectric material, is placed on the upper surface of the diaphragm 61, and extends continuously across the plurality of pressure chambers 51. In this embodiment, the diaphragm 61 and the piezoelectric layer 62 are made of piezoelectric material, but the diaphragm 61 may be made of an insulating material other than piezoelectric material, such as a synthetic resin material.

[0031] The common electrode 63 is positioned between the diaphragm 61 and the piezoelectric layer 62 and extends over its entire length. The common electrode 63 is connected to a power supply (not shown) via wiring (not shown) and is maintained at ground potential. Multiple individual electrodes 64 are positioned on the upper surface of the piezoelectric layer 62. Each of the multiple individual electrodes 64 is assigned to a separate pressure chamber 51 and overlaps vertically with the central portion of the corresponding pressure chamber 51. Each of the multiple individual electrodes 64 is connected to a driver IC 89 (see Figure 6) via wiring (not shown). The driver IC 89 selectively applies either ground potential or a drive potential (e.g., about 20-30V) to each individual electrode 64. In accordance with this arrangement of the common electrode 63 and the multiple individual electrodes 64, the portion of the piezoelectric layer 62 sandwiched between the common electrode 63 and each individual electrode 64 is polarized in the thickness direction.

[0032] In the piezoelectric actuator 22, the portion that overlaps vertically with each pressure chamber 51 serves as a driving element 22a for applying pressure to the ink in the pressure chamber 51. The driver IC 89 switches the potential of the individual electrodes 64 between ground potential and driving potential, thereby driving the driving element 22a. When the driving element 22a is driven, the potential difference between the individual electrodes 64 and the common electrode 63 changes, causing the piezoelectric layer 62 and the portion of the diaphragm 61 that overlaps vertically with the pressure chamber 51 to deform. This deformation causes the pressure of the ink in the pressure chamber 51 to fluctuate, allowing ink to be ejected from the nozzle 10 that communicates with the pressure chamber 51.

[0033] <Electrical configuration of the printer> Next, the electrical configuration of printer 1 will be described. As shown in Figure 6, printer 1 is equipped with a control device 80. The control device 80 consists of a CPU (Central Processing Unit) 81, ROM (Read Only Memory) 82, RAM (Random Access Memory) 83, flash memory 84, ASIC (Application Specific Integrated Circuit) 85, etc. The control device 80 controls the operation of the carriage motor 86, driver IC 89, transport motor 87, cap lifting mechanism 88, suction pump 72, high-voltage power supply circuit 77, etc. In this embodiment, the control device 80 controls the inkjet head 4 by controlling the driver IC 89. The control device 80 also receives a determination signal from the determination circuit 78.

[0034] In addition to the configuration described above, the printer 1 also includes a display unit 69, an operation unit 70, a temperature sensor 68 (the "temperature signal output unit" of the present invention), and a clock unit 67 (the "time signal output unit" of the present invention). The display unit 69 is, for example, a liquid crystal display provided on the housing of the printer 1. The control device 80 controls the display unit 69 to display information necessary for the operation of the printer 1. The operation unit 70 is, for example, buttons provided on the housing of the printer 1, a touch panel provided on the display unit 69, etc. The user can input signals to the control device 80 by operating the operation unit 70.

[0035] The temperature sensor 68 detects the temperature, such as the ambient temperature, and outputs a temperature signal indicating that temperature. The control device 80 receives the temperature signal from the temperature sensor 68. The clock unit 67 keeps time and outputs a time signal indicating the current time. The control device 80 receives the time signal from the clock unit 67.

[0036] Note that the control device 80 may be configured such that only the CPU 81 performs various processes, or only the ASIC 85 performs various processes, or the CPU 81 and the ASIC 85 cooperate to perform various processes. Also, the control device 80 may be configured such that one CPU 81 performs processing alone, or a plurality of CPUs 81 perform processing in a shared manner. Further, the control device 80 may be configured such that one ASIC 85 performs processing alone, or a plurality of ASICs 85 perform processing in a shared manner.

[0037] <Control of Printer by Control Device> Next, the control of the printer 1 by the control device 80 will be described. The control device 80 controls the operation of the printer 1 by performing processing in accordance with the flow of FIG. 7.

[0038] More specifically, the control device 80 is waiting while it has not received a recording command (the "discharge instruction signal" of the present invention) instructing recording on the recording paper P (S101: NO), and while the time indicated by the time signal received from the clock unit 67 is not a predetermined time (S102: NO).

[0039] When the control device 80 receives a recording command (S101: YES), it sets the drive potential applied to the individual electrodes 64 during the drive of the drive element 22a (S103). More specifically, in the flash memory 84, for example, as shown in FIG. 8(a), a table associating the temperature range of the temperature T indicated by the temperature signal received from the temperature sensor 68 with the drive potential is stored. Here, T1, T2, and T3 in FIG. 8(a) have a magnitude relationship of T1 < T2 < T3, and V1, V2, V3, and V4 have a magnitude relationship of V1 > V2 > V3 > V4. Then, in S103, the control device 80 sets the drive potential to any one of V1, V2, V3, and V4 based on the table in FIG. 8(a) and the temperature T indicated by the temperature signal received from the temperature sensor 68.

[0040] Next, the control device 80 performs the recording process (S104). During the recording process, the control device 80 controls the carriage motor 86 to move the carriage 2 in the scanning direction, and controls the driver IC 89 to repeatedly perform a recording path in which ink is ejected from multiple nozzles 10 toward the recording paper P by the inkjet head 4, and a transport operation in which the transport rollers 6 and 7 transport a predetermined amount of the recording paper P, thereby recording onto the recording paper P. When the recording path is performed, the control device 80 controls the driver IC 89 to switch the potential applied to the individual electrodes 64 between the ground potential and the drive potential set in S103.

[0041] On the other hand, when the time indicated by the time signal received from the clock unit 67 reaches a predetermined time (S102: YES), the control device 80 performs an inspection drive process (S105). In the inspection drive process, the control device 80 causes the inkjet head 4 to perform an inspection drive to check whether each nozzle 10 is an abnormal nozzle or not. The inspection drive is an operation in which the inkjet head 4 is driven to eject ink from each of the multiple nozzles 10 in order toward the detection amount electrode 76, with the carriage 2 positioned in the maintenance position described above. At this time, the control device 80 also receives a determination signal from the determination circuit 78 for each of the multiple nozzles 10.

[0042] Then, if the determination signal indicates that no abnormal nozzles exist (S106: NO), the process returns to S101. If the determination signal indicates that an abnormal nozzle exists (S106: YES), the control device 80 stores the first abnormal nozzle information and the first temperature information in the flash memory 84 (S107). The first abnormal nozzle information is information indicating which nozzle 10 is an abnormal nozzle, based on the determination signal received during the inspection drive. The first temperature information is temperature information based on the temperature signal received from the temperature sensor 68 during the inspection drive. The first temperature information may be the temperature itself indicated by the temperature signal, or it may be information indicating which temperature range the temperature indicated by the temperature information falls within, within the temperature range shown in Figure 8(a).

[0043] Subsequently, the control device 80 waits until a recording command is received (S108: NO). When a recording command is received (S108: YES), it determines whether the temperature range is different from that during inspection drive (S109). More specifically, it determines whether the temperature range including the temperature indicated by the temperature signal (the "second temperature information" of the present invention) received from the temperature sensor 68 is different from the temperature range including the temperature indicated by the first temperature information stored in the flash memory 84 in S107.

[0044] In this embodiment, the condition that the temperature range including the temperature indicated by the temperature signal received from the temperature sensor 68 is the same as the temperature range including the temperature indicated by the first temperature information corresponds to the "predetermined condition" of the present invention. Also, hereinafter, the fact that the temperature range including the temperature indicated by the temperature signal received from the temperature sensor 68 is the same as the temperature range including the temperature indicated by the first temperature information may be simply referred to as "the temperature ranges are the same". Also, hereinafter, the fact that the temperature range including the temperature indicated by the temperature signal received from the temperature sensor 68 is different from the temperature range including the temperature indicated by the first temperature information may be simply referred to as "the temperature ranges are different".

[0045] When the temperature ranges are the same (S109: NO), the control device 80 sets a recovery operation based on the first abnormal nozzle information stored in the flash memory 84 in S107 (S110).

[0046] More specifically, as shown in, for example, FIG. 8(b), the flash memory 84 stores a table associating the number N of abnormal nozzles with the recovery operation. N1, N2, and N3 in FIG. 8(b) are in the magnitude relationship of N1 < N2 < N3. Flushing in FIG. 8(b) is an operation of driving the inkjet head 4 (driving element 22a) by controlling the driver IC 89 to discharge ink from at least the abnormal nozzles among the plurality of nozzles 10 of the inkjet head 4. Flushing has a smaller ink discharge amount than weak purge.

[0047] In this embodiment, the maintenance unit 8 that performs suction purging and the inkjet head 4 that performs flushing correspond to the "recovery means" of the present invention.

[0048] Then, in S110, the recovery operation is set based on the number N of abnormal nozzles obtained from the first abnormal nozzle information and the table in Figure 8(b).

[0049] If the temperature range is different (S109: YES), the control device 80 performs the same inspection drive process as in S105 again (S111). Then, based on the second abnormal nozzle information, which indicates which nozzle 10 is an abnormal nozzle and is obtained based on the determination signal output from the determination circuit 78 during the inspection drive performed by the inspection drive process in S111, the recovery operation is set (S112). More specifically, the recovery operation is set based on the number of abnormal nozzles obtained from the second abnormal nozzle information and the table in Figure 8(b).

[0050] After setting the recovery operation in S110 or S112, the control device 80 executes the recovery process (S113). In the recovery process, the control device 80 performs the recovery operation set in S110 or S112. After the recovery process, the process proceeds to S103.

[0051] <Effects> If a significant temperature change occurs between the inspection drive and the recovery operation, the status of whether or not a nozzle is abnormal may change. Therefore, in this embodiment, the first abnormal nozzle information and the first temperature information are stored during the inspection drive. Then, when the recovery operation is performed afterward, the system switches whether or not to perform the recovery operation set based on the first abnormal nozzle information, based on whether or not the temperature range is the same as during the inspection drive (i.e., the predetermined conditions are met). This makes it possible to prevent the recovery operation set based on the first abnormal nozzle information from being performed if a significant temperature change occurs between the inspection drive and the recovery operation.

[0052] Furthermore, in this embodiment, when performing a recovery operation, if the temperature range differs from that during the inspection drive (i.e., the predetermined conditions are not met), the inspection drive is performed again to acquire second abnormal nozzle information. Then, the recovery operation set based on the acquired second abnormal nozzle information is performed. This allows for appropriate recovery operation based on the second abnormal nozzle information if a large temperature change occurs between the inspection drive and the recovery operation. On the other hand, if no large temperature change occurs between the inspection drive and the recovery operation, the recovery operation can be performed based on the results of the previously performed inspection drive. Therefore, it is not necessary to perform an inspection drive immediately before the recovery operation, and the time until the recovery operation is completed can be shortened.

[0053] Furthermore, in this embodiment, the temperature range and the drive potential are associated. In this case, the temperature range and the drive potential are usually associated according to the relationship between the temperature of the ink in the inkjet head 4 and the viscosity of the ink. In this embodiment, the temperature range associated with the drive potential is used to determine whether or not the temperature range is different from that during the test drive when performing the recovery operation. This makes it possible to switch whether or not to perform the recovery operation set based on the first abnormal nozzle information, depending on whether or not the temperature change from the test drive is large and the ink viscosity has changed so much that it is necessary to change the drive potential when performing the recovery operation.

[0054] Furthermore, in this embodiment, the test drive is performed when the time indicated by the clock signal from the clock unit 67 reaches a predetermined time. Therefore, by appropriately setting the predetermined time, the test drive can be performed, for example, when the user does not use the liquid dispensing device frequently.

[0055] Furthermore, if a test drive is performed and the judgment signal indicates the presence of an abnormal nozzle, unlike in this embodiment, immediately performing a recovery operation may cause the liquid in the liquid ejection head to become thicker if there is a long period between the test drive and the reception of the recording command. In this case, it becomes necessary to perform the recovery operation again when the recording command is received, resulting in the ink ejection during the recovery operation in the test drive being wasted.

[0056] Therefore, in this embodiment, a recovery operation is performed when a recording command is received after the test drive. As a result, the recovery operation is performed immediately before the recording process, so even if there is a long period between the test drive and the receipt of the recording command, ink will not be wasted.

[0057] Furthermore, in this embodiment, by selectively performing one of the following recovery operations—flushing, weak purging, medium purging, or strong purging—ink in the inkjet head 4 can be discharged from the nozzle 10, thereby restoring the abnormal nozzle.

[0058] <Variation> Although preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible as long as they are within the scope of the claims.

[0059] In the above-described embodiment, the system switched between performing a recovery operation based on the first abnormal nozzle information or a recovery operation based on the second abnormal nozzle information depending on whether the temperature range during the test drive differed from the temperature range when a recording command was subsequently received. However, the embodiment is not limited to this.

[0060] In the modified example 1, the control device 80 controls the printer 1 by processing according to the flow shown in Figure 9. The flow in Figure 9 is the same as the flow in Figure 7, but with S109 replaced by S201. Also, in the flow in Figure 9, at S107, the temperature information itself, indicated by the temperature signal received from the temperature sensor 68, is stored as the first temperature information.

[0061] In S201, when it is determined in S108 that a recording command has been received, it is determined whether the temperature difference |ΔT| between the temperature indicated by the temperature signal received from the temperature sensor 68 (the "second temperature information" of the present invention) and the temperature indicated by the first temperature information is greater than the threshold ΔTh. In Modification 1, the condition that the temperature difference |ΔT| is less than or equal to the threshold ΔTh corresponds to the "predetermined condition" of the present invention.

[0062] Then, if the temperature difference |ΔT| is less than or equal to the threshold ΔTh (S201:NO), proceed to S110. If the temperature difference |ΔT| is greater than the threshold ΔTh (S201:YES), proceed to S111.

[0063] If a large temperature change occurs between the inspection drive and the recovery operation, the status of whether or not it is an abnormal nozzle may change. Therefore, in Modification 1, the first abnormal nozzle information and the first temperature information are stored during the inspection drive. Then, when the recovery operation is performed afterward, the system switches whether or not to perform the recovery operation set based on the first abnormal nozzle information, based on whether or not the temperature difference |ΔT| between the temperature at the time of the inspection drive and the current temperature is below a threshold (a predetermined condition is met). This makes it possible to prevent the recovery operation set based on the first abnormal nozzle information from being performed if a large temperature change occurs between the inspection drive and the recovery operation.

[0064] Furthermore, in the above-described embodiment, when it was determined in S109 that the temperature range was different, the second abnormal nozzle information was obtained by performing the inspection drive again, and a recovery operation was set based on the obtained second abnormal nozzle information, but this is not limited to this.

[0065] In modified example 2, the control device 80 controls the printer 1 by processing according to the flow shown in Figure 10. The flow in Figure 10 is the same as the flow in Figure 7, but with S111 and S112 replaced by S301 to S303.

[0066] To explain in more detail, in the modified example 2, when it is determined in S109 that the temperature range is different (S109:YES), the control device 80 further determines whether the temperature has risen compared to when it was driven for inspection (S301). If the temperature has risen compared to when it was driven for inspection (S301:YES), the recovery operation is set to a recovery operation that discharges less ink than the recovery operation set based on the first abnormal nozzle information (S302), and the process proceeds to S113.

[0067] If the temperature is lower than during the test drive (S301:NO), the recovery operation is set to one that discharges more ink than the recovery operation set based on the first abnormal nozzle information (S303), and the process proceeds to S113.

[0068] As the temperature rises, the viscosity of the ink decreases. Therefore, in Modification 2, if the temperature rises significantly enough to change the temperature range between the test drive and the recovery operation, a recovery operation with less ink discharge is performed than when the temperature has not changed significantly. This makes it possible to perform an appropriate recovery operation in response to the temperature change between the test drive and the recovery operation.

[0069] Furthermore, ink viscosity increases as temperature decreases. Therefore, in Modification 2, if the temperature drops significantly enough to change the temperature range between the test drive and the recovery operation, a recovery operation with a larger ink discharge rate is performed than in the case where the temperature has not changed significantly. This allows for an appropriate recovery operation to be performed in response to temperature changes between the test drive and the recovery operation.

[0070] Furthermore, in Modification 2, when it is determined in S109 that the temperature range is different, a recovery operation different from the recovery operation set based on the first abnormal nozzle information is performed, regardless of whether the temperature is rising or falling, but it is not limited to this.

[0071] For example, in Modification 2, when it is determined in S109 that the temperature ranges are different, if the temperature has decreased, a recovery operation may be set in the same manner as in S303, and if the temperature has increased, a recovery operation set based on the first abnormal nozzle information may be performed. In this case, the amount of ink discharged during the recovery operation may be more than the appropriate amount, but the abnormal nozzle can be recovered. In this case, the conditions that the temperature ranges are the same, and that the temperature ranges are different and the temperature has increased, correspond to the "predetermined conditions" of the present invention.

[0072] Alternatively, in Modification 2, when it is determined in S109 that the temperature ranges are different, if the temperature is rising, a recovery operation may be set in the same manner as in S302, and if the temperature is falling, a recovery operation set based on the first abnormal nozzle information may be performed. Even in this case, for example, if the recovery operation set based on the first abnormal nozzle information is set to one that discharges a large amount of ink, the amount of ink discharged during the recovery operation may be greater than the appropriate amount, but the abnormal nozzle can still be recovered. In this case, the conditions that the temperature ranges are the same, and the conditions that the temperature ranges are different and the temperature is falling, correspond to the "predetermined conditions" of the present invention.

[0073] Furthermore, in the above-described embodiment, after storing the first abnormal nozzle information and the first temperature information in the flash memory 84, when a recording command is received, it is determined whether or not the temperature range is different. If the temperature range is different, the inspection drive is performed again to obtain the second abnormal nozzle information, and the recovery process is set based on the obtained second abnormal nozzle information. However, this is not the only example.

[0074] In the third modified example, the printer 1 is controlled by processing according to the flow shown in Figure 11. More specifically, the control device 80 performs the same processing as in the above-described embodiment, from S101 to S106. When it determines in S106 that an abnormal nozzle exists (S106: YES), the control device 80 stores the abnormal nozzle information and the first temperature information in the flash memory 84 (S401). The abnormal nozzle information is the same as the first abnormal nozzle information in the above-described embodiment.

[0075] Subsequently, the system remains in standby mode if the temperature range including the temperature indicated by the temperature signal received from the temperature sensor 68 (the "second temperature information" of the present invention) is the same as the temperature range including the temperature indicated by the first temperature information (S402: NO), and no recording command has been received (S403: NO).

[0076] When the temperature range including the temperature indicated by the temperature signal received from the temperature sensor 68 is different from the temperature range including the temperature indicated by the first temperature information (S402:YES), the control device 80 performs the same inspection drive process as in S105 (S404). Then, it updates the abnormal nozzle information and the first temperature information stored in the flash memory 84 (S405) and returns to S402. In S405, the first abnormal nozzle information stored in the flash memory 84 is updated based on the determination signal output from the determination circuit 78 when the inspection drive was performed by the inspection drive process in S404. Also in S405, the first temperature information stored in the flash memory 84 is updated based on the temperature signal output from the temperature sensor 68 when the inspection drive was performed by the inspection drive process in S404.

[0077] Furthermore, when a recording command is received (S403:YES), the control device 80 sets a recovery operation based on the first abnormal nozzle information (S406). Then, it executes the recovery process to perform the recovery operation set in S406 (S407) and proceeds to S103. In other words, in the modified example 3, the recovery operation corresponding to the abnormal nozzle information stored in the flash memory 84 is performed last.

[0078] In the modified example 3, the inspection drive is performed, and the abnormal nozzle information is stored based on the judgment signal output from the judgment circuit 78 at this time. Then, before the recovery operation is performed, the inspection drive is performed each time the temperature range changes (the predetermined conditions are no longer met), and the abnormal nozzle information is updated based on the judgment signal output from the judgment circuit 78 at this time. When the recovery operation is performed, the recovery operation set based on the last stored abnormal nozzle information is performed.

[0079] This allows for appropriate recovery operations based on the initially stored abnormal nozzle information when the temperature change after the initial test drive is not significant. Furthermore, if a large temperature change occurs after the initial test drive, appropriate recovery operations based on the abnormal nozzle information after the temperature change can be performed.

[0080] Furthermore, in Modification 3, instead of performing the inspection drive and updating the abnormal nozzle information and first temperature information each time the temperature range changes, the inspection drive may be performed and the abnormal nozzle information and first temperature information updated each time the temperature difference |ΔT| described in Modification 1 exceeds the threshold ΔTh.

[0081] Furthermore, in the above example, we used the temperature range associated with the drive potential, as shown in Figure 8(a), to determine whether the temperature range was different in S109, but this is not the only way.

[0082] In Modification 4, as shown in Figure 12, a table associating temperature ranges with drive waveforms is stored in the flash memory 84. The drive waveform is the waveform of the drive signal transmitted from the driver IC 89 to the individual electrodes 64 of the drive element 22a in order to switch the potential of the individual electrodes 64 between ground potential and drive potential. The drive waveforms W1, W2, W3, and W4 in Figure 12 are, for example, pulse waveforms, and at least one of the pulse width, number of pulses, and pulse interval is different from each other. The drive waveforms W1, W2, W3, and W4 are arranged such that the amount of ink ejected from the nozzle 10 increases in the order of W1, W2, W3, and W4. In Modification 4, the temperature range associated with the drive waveform in Figure 12 is used to determine in S109 whether or not the temperature ranges are different.

[0083] In Modification 4, the temperature range and the drive waveform are associated. In this case, the temperature range and the drive waveform are usually associated according to the relationship between the temperature of the ink in the inkjet head 4 and the viscosity of the ink. Then, in Modification 4, the temperature range associated with the drive waveform is used to determine whether the temperature range is different from that of the test drive when the recovery operation is performed. This makes it possible to switch whether or not to perform the recovery operation set based on the first abnormal nozzle information, based on whether or not the temperature change from the test drive is large and the ink viscosity has changed so much that it is necessary to change the drive waveform when the recovery operation is performed.

[0084] Furthermore, the temperature range used for the determination in S109 is not limited to a temperature range associated with the driving conditions of the driving element 22a, such as a temperature range associated with the driving potential as shown in Figure 8(a), or a temperature range associated with the driving waveform as shown in Figure 12. The determination in S109 may also be made using a temperature range set independently of the driving conditions of the driving element 22a.

[0085] Furthermore, in the above embodiment, the process proceeds to S108 when the first recording command received after the test drive is received (S107: YES), but this is not limited to this. For example, the printer 1 can selectively perform either low-resolution recording or high-resolution recording, and the process may proceed to S108 when the first recording command instructing to record in high resolution is received after the test drive. In this case, if a recording command instructing to record in low resolution is received before a recording command instructing to record in high resolution is received, the recording process may be performed as is.

[0086] Furthermore, the process is not limited to proceeding to S108 only when a recording command is received after a test drive. For example, the process may proceed to S108 when, after a test drive, the printer 1 is powered on and the control device 80 receives a signal other than a recording command, such as an ON signal indicating that the power has been turned on.

[0087] Furthermore, the procedure is not limited to performing a test drive after receiving a time signal indicating a predetermined time, and then performing a recovery operation when a signal other than the said time signal is received. For example, after performing a test drive after receiving a time signal indicating a predetermined time, another operation that takes a certain amount of time, other than the recovery operation, may be performed before the recovery operation is performed. Even in this case, it is effective to switch whether or not to perform the recovery operation set based on the first abnormal nozzle information depending on whether or not a large temperature change has occurred during the other operation.

[0088] Furthermore, in the above-described embodiment, the test drive process was executed when the time signal from the clock unit 67 reached a predetermined time, but this is not limited to this. For example, the test drive process may be executed at a different timing, such as when a predetermined time has elapsed since the last recording or the last test drive.

[0089] Furthermore, in the above examples, the recovery operation was selectively performed as one of flushing, weak purging, medium purging, or strong purging, but it is not limited to these. The recovery operation may not involve flushing, but instead selectively perform one of several types of suction purging with different ink discharge volumes. Alternatively, the recovery operation may not involve suction purging, but instead selectively perform one of several types of flushing with different ink discharge volumes.

[0090] Furthermore, although suction purging was performed as the purging method in the above example, it is not limited to this. For example, a pressure pump may be provided in the middle of the tube 15 connecting the sub-tank 3 and the ink cartridge 14. Alternatively, a pressure pump connected to the ink cartridge may be provided in the printer. Then, with multiple nozzles 10 covered by caps 71, the pressure pump may be driven to pressurize the ink in the inkjet head 4 and discharge the ink from the nozzles 10, thereby performing a so-called pressure purge.

[0091] Furthermore, during purging, both suction by the suction pump 72 and pressurization by the pressure pump may be performed.

[0092] Furthermore, in the above-described embodiment, all nozzles 10 of the inkjet head 4 were driven for inspection, but this is not limited to this. For example, inspection driving may be performed only on some nozzles 10 of the inkjet head 4, such as every other nozzle 10 in each nozzle row 9, and for the remaining nozzles 10, it may be estimated whether or not they are abnormal nozzles based on the determination signal output from the determination circuit 78 during the inspection driving.

[0093] Furthermore, in the above-described embodiment, the determination circuit 78 outputs a signal indicating whether or not it is an abnormal nozzle, depending on the potential of the detection electrode 76 when ink is ejected from the nozzle 10 toward the detection electrode 76, but it is not limited to this.

[0094] For example, a detection electrode extending vertically may be placed, and when ink is ejected from the nozzle 10 so as to pass through the region opposite the detection electrode, the determination circuit may output a signal indicating whether or not it is an abnormal nozzle, depending on the potential of the detection electrode. Alternatively, a light sensor (the "Invention") that detects the ink ejected from the nozzle 10 may be used. For judgment A signal output unit may be provided, and a signal may be output from the optical sensor depending on whether or not the nozzle is abnormal.

[0095] Alternatively, for example, as described in Japanese Patent Publication No. 4929699, a voltage detection circuit (in this invention) is provided on a plate on which the nozzles of the inkjet head are formed to detect the change in voltage when ink is ejected from the nozzles. For judgment A signal output unit may be connected to the voltage detection circuit to output a signal to the control device 80 indicating whether or not it is an abnormal nozzle.

[0096] Alternatively, for example, as described in Japanese Patent Publication No. 6231759, the substrate of the inkjet head may be made a temperature sensing element (the " For judgment The device may also be equipped with a signal output unit. After applying a first applied voltage to drive the heater for ink ejection, a second applied voltage may be applied to drive the heater to prevent ink ejection, and a signal may be output based on the temperature change detected by the temperature sensing element during the period from when the second applied voltage is applied until a predetermined time has elapsed, indicating whether the nozzle 10 is an abnormal nozzle or not.

[0097] Also, in the above examples, For judgment The signal output unit outputs a signal depending on whether or not ink has been ejected from nozzle 10. Based on this signal, information is obtained about which nozzle is the faulty nozzle. Then, based on the number N of faulty nozzles obtained from this information, a set recovery operation is performed. However, this is not the only way.

[0098] For example, it outputs a signal corresponding to the abnormal nozzle condition other than ink not being ejected. For judgmentA signal output section is provided. For judgment Information regarding the state of abnormal nozzles may be obtained based on signals from the signal output unit. The state of abnormal nozzles refers to conditions such as abnormal ink ejection direction, splashing, air bubbles, or clogging with paper dust. Based on this information regarding the state of abnormal nozzles, a pre-set recovery operation may be performed. Alternatively, information including both the number of abnormal nozzles and their states may be obtained, and a pre-set recovery operation may be performed based on this information.

[0099] Furthermore, while the above describes an example of applying the present invention to a printer equipped with a so-called serial head that ejects ink from multiple nozzles while moving in the scanning direction together with the carriage, the invention is not limited to this. For example, the present invention can also be applied to a printer equipped with a so-called line head that extends along the entire length of the recording paper P in the scanning direction.

[0100] Furthermore, while the above description has focused on an example of applying the present invention to a printer that ejects ink from a nozzle to record on recording paper P, the invention is not limited to this. It can also be applied to printers that record images on recording media other than recording paper, such as T-shirts, outdoor advertising sheets, cases for mobile devices such as smartphones, cardboard, and resin materials. It can also be applied to liquid dispensing devices that dispense liquids other than ink, such as liquid resin or metal. [Explanation of Symbols]

[0101] 1. Printer 4. Inkjet head 8. Maintenance Unit 10 nozzles 22a Driving element 51 Pressure Chamber 67 Temperature sensor 68 Clock Department 72 Suction pump 76 Detection electrodes 77 High-voltage power supply circuit 78 Judgment circuit 79 Resistors 80 Control device 89 Driver ICs 84 Flash Memory

Claims

1. A liquid dispensing head having multiple nozzles for dispensing liquid, When the liquid discharge head is driven to perform an inspection to confirm whether the nozzle is a defective nozzle with an abnormality in liquid discharge, a determination signal output unit outputs a determination signal corresponding to each of the plurality of nozzles indicating whether or not it is a defective nozzle, A recovery means that performs a recovery operation to discharge liquid from the nozzle, A temperature signal output unit that outputs a temperature signal indicating the temperature, Memory unit and, A control device is provided, The control device is When the liquid discharge head is driven for inspection, First temperature information related to the temperature indicated by the temperature signal output from the temperature signal output unit, The abnormal nozzle information related to the abnormal nozzle, based on the determination signal output from the determination signal output unit, is stored in the storage unit. Subsequently, each time the first temperature information stored in the memory unit and the second temperature information related to the temperature indicated by the temperature signal output from the temperature signal output unit no longer satisfy the predetermined conditions regarding the temperature difference, The liquid discharge head is made to perform the inspection drive, Based on the temperature signal output from the temperature signal output unit, the first temperature information stored in the storage unit is updated. Based on the determination signal output from the determination signal output unit, the abnormal nozzle information related to the abnormal nozzle stored in the storage unit is updated. Subsequently, when the recovery means is made to perform the recovery operation, Finally, a liquid dispensing device characterized by causing the recovery means to perform the recovery operation based on the abnormal nozzle information stored in the memory unit.

2. The storage unit stores information for multiple types of temperature ranges that do not overlap. The first temperature information and the second temperature information are information indicating which of the multiple types of temperature ranges the temperature falls within. The liquid dispensing device according to claim 1, characterized in that the predetermined condition is that the temperature range indicated by the first temperature information and the temperature range indicated by the second temperature information are the same temperature range.

3. It includes a time signal output unit that outputs a time signal indicating the current time, The control device is When the time signal indicating a predetermined time is received from the time signal output unit, The liquid discharge head is made to perform the inspection drive, The liquid dispensing apparatus according to claim 1 or 2, characterized in that the first temperature information related to the temperature indicated by the temperature signal output from the temperature signal output unit is stored in the storage unit.

4. The control device is After receiving the time signal indicating the predetermined time, when a signal other than the time signal is received, The liquid dispensing device according to claim 3, characterized in that the recovery means is made to perform the recovery operation.

5. The liquid dispensing device according to claim 4, characterized in that the other signal is an instruction signal that instructs the dispensing of liquid into the dispensing medium.

6. The liquid dispensing device according to claim 5, characterized in that the other signal is the instruction signal that is first received after the test drive.

7. The recovery means is It has a pump that can be connected to the liquid discharge head, The liquid dispensing device according to any one of claims 1 to 6, characterized in that the recovery operation includes purging, which involves driving the pump to discharge the liquid from the nozzle into the liquid dispensing head.

8. The recovery means is Having the aforementioned liquid dispensing head, The liquid dispensing device according to any one of claims 1 to 7, characterized in that the recovery operation includes flushing to cause liquid to be discharged from the nozzle to the liquid dispensing head.

Images