Inkjet recording apparatus

Abstract

An inkjet recording apparatus of the present application is provided with a recording head, an ink container, an ink supply section, a driving mechanism, a timer, a start position sensing section, and a control section. The ink supply section includes a sub-tank, an ink flow path, and a syringe pump having a cylinder and a piston. The control section, when performing a purging operation using the syringe pump, after performing a press operation on the piston located at the start position by a preset set press amount, measures a movement time from the start of the stretching operation to the arrival at the start position by the timer, and in the case where the movement time is shorter than a threshold value, determines that an abnormality has occurred in the ink supply section.

Description

Technical Field

[0001] This invention relates to an inkjet recording device. Background Technology

[0002] Conventionally, inkjet printers and other inkjet recording devices use a recording head that includes a pressure chamber for filling ink. This pressure chamber is connected to a nozzle, and by filling the pressure chamber with ink, a liquid surface (meniscus) is formed inside the nozzle. The pressure chamber is connected to a pressure element, such as a piezoelectric element that deforms when a driving voltage is applied, and a vibrating plate that is stacked with the pressure element to form a drive unit. By flexing the vibrating plate to reduce the volume of the pressure chamber, the ink inside the pressure chamber is pressurized and ejected as ink droplets from the tip of the nozzle.

[0003] In such inkjet recording devices, a method is known to supply ink to the recording head using a syringe pump. This configuration allows not only ink purification of the recording head but also the circulation and removal of air bubbles and the replacement of ink with other liquids.

[0004] As described above, in structures using syringe pumps, due to factors such as malfunction of the pump's motor, damage or blockage of the ink supply tubing, or missing connecting parts in the ink flow path, excessive pressure is sometimes applied to the syringe and flow path when ink is extruded through the piston inside the syringe pump. As a result, excessive pressure is applied to the syringe pump, the ink flow path, and even, in some cases, the recording head. In the worst case, ink contamination inside and outside the device may occur due to syringe pump failure or ink supply tubing rupture. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] The purpose of this invention is to provide an inkjet recording device that, when using an injection pump to supply ink, can simply and cost-effectively prevent both damage caused by excessive pressure applied to the flow path and abnormal flow path detection.

[0007] (II) Technical Solution

[0008] The inkjet recording apparatus of the first structure of the present invention includes:

[0009] A recording head, which has multiple nozzles that eject ink;

[0010] An ink container that holds the ink;

[0011] An ink supply unit includes a secondary container, an ink flow path, and an injection pump. The secondary container temporarily stores the ink supplied from the ink container. The ink flow path allows the ink to circulate from the secondary container through the recording head to the secondary container. The injection pump has a cylinder and a piston. The cylinder is positioned downstream of the secondary container and upstream of the recording head relative to the ink flow direction of the ink flow path. One end of the cylinder has a discharge port connected to the recording head and a filling port connected to the secondary container, while the other end is open. The piston is inserted into the cylinder and is movable in a direction approaching one end and another direction approaching the other end.

[0012] The drive mechanism performs a pressing action that moves the piston toward one end and a stretching action that moves the piston toward the other end.

[0013] A timer that measures the time it takes for the piston to move;

[0014] A starting position sensing unit senses that the piston is in the starting position; and

[0015] The control unit controls the drive mechanism.

[0016] The drive mechanism has:

[0017] motor;

[0018] One or more gears that transmit the driving force of the motor to the piston; and

[0019] A torque limiter, mounted on either of the gears,

[0020] When the control unit performs a purification operation by forcibly extruding the ink from the nozzle of the recording head using the injection pump...

[0021] After pressing the piston at the starting position with a preset pressing amount, the timer measures the movement time from the start of the stretching action to reaching the starting position.

[0022] The system is capable of executing an anomaly detection mode, which determines that an anomaly has occurred in the ink supply unit when the movement time is shorter than a threshold.

[0023] (III) Beneficial Effects

[0024] According to the first structure of the present invention, abnormalities in the ink supply section can be detected using only the existing torque limiter, start position sensing unit, and timer without adding additional components for sensing abnormalities in the ink supply section. Furthermore, by sensing abnormalities using the time required for the piston to return to the start position, abnormalities can be detected by comparing all ink flow paths downstream of the injection pump, and excessive pressure applied to the ink flow paths can be suppressed. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view showing the schematic structure of an inkjet recording apparatus 1 according to an embodiment of the present invention.

[0026] Figure 2 This is a top view of the area surrounding the recording section 5 of the inkjet recording apparatus 1 in this embodiment.

[0027] Figure 3 This is a block diagram showing the hardware structure of the main parts of the inkjet recording apparatus 1 according to this embodiment.

[0028] Figure 4 This is an explanatory diagram showing the structure of the ink supply unit 8 of the inkjet recording apparatus 1 in this embodiment.

[0029] Figure 5 This is an explanatory diagram of the injection pump 88 and the drive mechanism 70, showing the operation when ink is discharged from the injection pump 88.

[0030] Figure 6 This is an explanatory diagram of the injection pump 88 and the drive mechanism 70, showing the operation when filling the injection pump 88 with ink.

[0031] Figure 7 This is a flowchart illustrating an example of the execution control of the abnormality determination mode of the ink supply unit 8 in the inkjet recording apparatus 1 of this embodiment. Detailed Implementation

[0032] [1. Structure of an inkjet recording device]

[0033] The embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 This is a cross-sectional view showing the schematic structure of an inkjet recording apparatus 1 according to an embodiment of the present invention. Figure 2 yes Figure 1 A top view of the area surrounding the recording section 5 of the inkjet recording device 1. Figure 3 It means Figure 1 A block diagram of the hardware structure of the main parts of the inkjet recording device 1. The inkjet recording device 1 is, for example, an inkjet recording printer, and includes: device body 2, paper supply unit 3, paper transport unit 4, recording unit 5, drying unit 6, and control unit 7.

[0034] The paper supply unit 3 is, for example, located at the lower part of the device body 2. The paper supply unit 3 contains multiple sheets of paper (recording media) S, and separates and feeds out the sheets of paper S one by one during recording.

[0035] The paper conveying unit 4 is positioned downstream of the paper supply unit 3 relative to the paper conveying direction. Figure 1 Above the paper feed unit 3, the paper S is conveyed. The paper transport unit 4 conveys the paper S to the recording unit 5 and the drying unit 6, and further discharges the recorded and dried paper S to the paper discharge unit 21. The paper transport unit 4 has, for example, a flip transport unit 4r. In the case of double-sided recording, the paper transport unit 4 distributes the paper S recorded and dried on the first side to the flip transport unit 4r, and flips it by changing the transport direction, and then conveys the paper S with the second side facing up to the recording unit 5 and the drying unit 6 again.

[0036] The paper conveying unit 4 includes a first belt conveying unit 41 and a second belt conveying unit 42. The first belt conveying unit 41 has a first conveyor belt 411 formed in a ring shape. The second belt conveying unit 42 has a second conveyor belt 421 formed in a ring shape. The first belt conveying unit 41 and the second belt conveying unit 42 hold and hold the paper S on the upper surfaces (conveyor surfaces) of the first conveyor belt 411 and the second conveyor belt 421 respectively for conveying. The first conveyor belt 411 and the second conveyor belt 421 are mounted on multiple rollers including drive rollers. The first belt conveying unit 41 is positioned below the recording unit 5 to convey the paper S. The second belt conveying unit 42 is located downstream of the first belt conveying unit 41 relative to the paper conveying direction. Figure 1 (To the left), it is arranged in the drying section 6 to transport paper S.

[0037] The recording unit 5 is disposed downstream of the paper supply unit 3 and above the first conveyor belt 41, relative to the paper conveying direction. The recording unit 5 is disposed above the first conveyor belt 411 at a predetermined interval, opposite to the paper S. That is, the recording unit 5 is opposite to the paper S conveyed by the paper conveying unit 4 and held adsorbed on the upper surface of the first conveyor belt 411.

[0038] like Figure 2 As shown, the recording unit 5 holds header units 51Y, 51M, 51C, and 51K, corresponding to the four colors: yellow, magenta, cyan, and black, respectively. Header units 51Y, 51M, 51C, and 51K are arranged side-by-side along the paper transport direction Dc, with their long sides parallel to the paper width direction Dw, which is orthogonal to the paper transport direction Dc. Furthermore, the four header units 51Y, 51M, 51C, and 51K have the same basic structure; therefore, in the following description, unless specifically defined, the identification marks “B,” “C,” “M,” and “Y” representing each color are sometimes omitted.

[0039] Each color of the head unit 51 has a row-type recording head 52. Multiple recording heads 52 are arranged alternately along the width direction Dw of the paper in each color of the head unit 51 (in this embodiment, there are three recording heads 52a, 52b, and 52c).

[0040] The recording head 52 has a plurality of ink ejection nozzles 521 on its lower surface. The plurality of ink ejection nozzles 521 are arranged along the width direction Dw of the paper and are capable of ejecting ink to the entire recording area on the paper S. The recording unit 5 ejects ink sequentially from the respective recording heads 52 of the four-color head units 51Y, 51M, 51C, and 51K toward the paper S conveyed by the first conveyor belt 411, and records a panchromatic image or a monochrome image on the paper S.

[0041] The drying section 6 is located downstream of the recording section 5 relative to the paper transport direction and is equipped with a second conveyor belt 42. During transport of the paper S, on which the ink image has been recorded by the recording section 5, held adsorbed in the drying section 6 by the second conveyor belt 421, the ink is dried.

[0042] The control unit 7 includes a CPU, a storage unit, other electronic circuits, and electronic components (not shown). Based on the control program and data stored in the storage unit, the CPU controls the operation of each structural element installed in the inkjet recording device 1 to perform processing related to the function of the inkjet recording device 1. The paper supply unit 3, paper transport unit 4, recording unit 5, and drying unit 6 each receive control signals individually from the control unit 7 and record onto the paper S in a coordinated manner. The storage unit is, for example, a combination of non-volatile storage devices such as program ROM (Read Only Memory) and data ROM and volatile storage devices such as RAM (Random Access Memory).

[0043] like Figure 3 As shown, the inkjet recording apparatus 1 includes an ink supply unit 8 and a head drive unit 53. The ink supply unit 8 includes a container pump 82, a circulation pump 84, a pressurization unit 86, a depressurization unit 87, a syringe pump 88, a first switching valve 91, a second switching valve 92, and a third switching valve 95. The ink supply unit 8 also includes an ink container 81, a first auxiliary can 83, a second auxiliary can 85, a first flow path 89, a second flow path 94, a third flow path 98, and a switching mechanism 99 (all refer to...). Figure 4 The detailed structure of the ink supply section 8 will be described later.

[0044] The head drive unit 53 includes a waveform data storage unit 531, a drive waveform generation unit 532, a buffer 533, and a selector 534. The waveform data storage unit 531 stores drive waveform data for driving the pressure element (not shown) in the recording head 52.

[0045] The drive waveform generation unit 532 generates a drive waveform (drive voltage) for driving the pressure element in the recording head 52 based on the drive waveform data stored in the waveform data storage unit 531. The buffer 533 stores drive waveform selection data for one page of image recorded on the paper S. The selector 534 performs the following operations based on the drive waveform selection data stored in the buffer 533: applies the drive voltage of the ejected drive waveform to the pressure element of the recording head 52; or does not select a drive waveform and keeps the drive voltage of the pressure element of the recording head 52 constant.

[0046] [2. Structure of the ink supply department]

[0047] Figure 4 It means Figure 1 This is an explanatory diagram illustrating the structure of the ink supply unit 8 of the inkjet recording device 1. (Usage) Figure 3 as well as Figure 4 The ink supply unit 8 of the inkjet recording apparatus 1 will be described below. The ink supply unit 8 is provided separately for the four-color head unit 51. In the following description, the identification marks for each color will be omitted. The ink supply unit 8 is connected to the head unit 51 via a detachable connector 11. A valve component (not shown) is built into the connector 11, which opens the ink flow path in the connected state and closes the ink flow path in the disconnected state.

[0048] The ink container 81 is detachably disposed relative to the device body 2. The ink container 81 contains the ink supplied to the recording head 52.

[0049] The container pump 82 is positioned downstream of the ink container 81 relative to the ink flow direction. The container pump 82 draws ink from the ink container 81 and sprays it toward the first auxiliary can 83. The operation of the container pump 82 is controlled by the control unit 7.

[0050] The first auxiliary container 83 is positioned downstream of the container pump 82 relative to the ink flow direction. The first auxiliary container 83 temporarily stores the ink supplied from the ink container 81. An ink dosage sensor (not shown) is installed in the first auxiliary container 83. The ink dosage sensor may include, for example, optical, capacitive, electrode, differential pressure, or float sensors, and detects the ink dosage within the first auxiliary container 83.

[0051] The control unit 7 receives a detection signal from the ink dosage sensor of the first sub-canister 83. If the ink dosage detected by the ink dosage sensor in the first sub-canister 83 is lower than a predetermined value, the control unit 7 controls the container pump 82 to supply ink from the ink container 81 to the first sub-canister 83. The amount of ink supplied from the ink container 81 to the first sub-canister 83 is controlled, for example, by the drive time of the container pump 82. Even if the drive time of the container pump 82 has elapsed for a certain period of time, and the ink dosage detected by the ink dosage sensor in the first sub-canister 83 is still not higher than the predetermined value, the control unit 7 determines that the ink dosage in the ink container 81 is empty.

[0052] A circulation pump 84 is positioned downstream of the first auxiliary tank 83 in the ink flow direction. The circulation pump 84 moves ink from the first auxiliary tank 83 to the second auxiliary tank 85. The circulation pump 84 can be selected from liquid pumps such as tubular pumps or diaphragm pumps. The operation of the circulation pump 84 is controlled by the control unit 7.

[0053] The second auxiliary tank 85 is located downstream of the ink flow direction of the circulating pump 84. The second auxiliary tank 85 temporarily stores the ink supplied from the first auxiliary tank 83. Similar to the first auxiliary tank 83, the second auxiliary tank 85 is equipped with an ink dosage sensor (not shown) to detect the ink dosage within the second auxiliary tank 85.

[0054] The control unit 7 receives a detection signal from the ink dosage sensor of the second sub-tank 85. If the ink dosage detected by the ink dosage sensor in the second sub-tank 85 is lower than a predetermined value, the control unit 7 controls the circulation pump 84 to move ink from the first sub-tank 83 to the second sub-tank 85. The amount of ink moving from the first sub-tank 83 to the second sub-tank 85 is controlled, for example, by the drive time of the circulation pump 84.

[0055] A pressurizing unit 86 is attached to the second auxiliary tank 85. The pressurizing unit 86 pressurizes the second auxiliary tank 85 and supplies ink from the second auxiliary tank 85 to the recording head 52. The operation of the pressurizing unit 86 is controlled by the control unit 7.

[0056] A pressure-reducing unit 87 is attached to the first auxiliary tank 83. The pressure-reducing unit 87 reduces the pressure inside the first auxiliary tank 83, causing the ink to circulate from the recording head 52 to the first auxiliary tank 83. The operation of the pressure-reducing unit 87 is controlled by the control unit 7.

[0057] The syringe pump 88 is positioned downstream of the second sub-tank 85 and upstream of the recording head 52, relative to the ink flow direction. Ink flows into the syringe pump 88 from the second sub-tank 85 and flows out toward the recording head 52.

[0058] When recording an image onto paper S, the pressure unit 86 applies recording pressure to the ink. In contrast, for example during maintenance, the control unit 7 uses the drive mechanism 70 (see reference 70) to... Figure 3 ) causes the piston 882 inside the injection pump 88 (refer to Figure 5The pump moves downwards, squeezing ink out of the injection pump 88, thereby applying a maintenance pressure to the ink that is higher than the recording pressure. That is, the injection pump 88 can apply a maintenance pressure to the ink that is higher than the recording pressure applied by the pressurization unit 86.

[0059] The first flow path 89 is a flow path in which ink is circulated from the first auxiliary tank 83 through the circulation pump 84, the second auxiliary tank 85, the injection pump 88, and the recording head 52 back to the first auxiliary tank 83. The first flow path 89 includes: a first conduit 891 extending from the second auxiliary tank 85 to the injection pump 88; a second conduit 892 extending from the injection pump 88 to the recording head 52; a third conduit 893 extending from the recording head 52 to the first auxiliary tank 83; and a fourth conduit 894 extending from the first auxiliary tank 83 to the second auxiliary tank 85. A check valve CV1 is disposed on the fourth conduit 894. The check valve CV1 prevents backflow of ink relative to the ink flow direction of the first flow path 89 from the downstream side to the upstream side.

[0060] When not recording images, the control unit 7 can execute a forced flow mode in which a maintenance pressure is applied to the ink via the injection pump 88, forcing the ink to flow downstream of the ink flow direction of the injection pump 88. As a result, when not recording images, air bubbles in the ink flow path, i.e., the first flow path 89, can be moved away from the recording head 52. That is, when recording onto the paper S, the movement of air bubbles in the first flow path 89 towards the recording head 52 can be suppressed.

[0061] In addition, the control unit 7 can execute a cleaning mode when not recording images, in which ink is forcibly ejected from the ink ejection nozzle 521 (see reference). Figure 2 The ink is extruded (purified) to clean the record head 52. In cleaning mode, ink is ejected from the ink ejection nozzle 521 of the record head 52 toward the ink ejection surface. The ejected ink, including, for example, high-viscosity ink and foreign matter from the ink ejection nozzle 521, is held at the ink ejection surface by surface tension. Then, the ink on the ink ejection surface is wiped away by a wiping member (not shown).

[0062] Furthermore, the ink supply unit 8 includes a first switching valve 91, a second switching valve 92, a second flow path 94, a third switching valve 95, a third flow path 98, and a switching mechanism 99. The first switching valve 91 is disposed on the first conduit 891 of the first flow path 89, upstream of the injection pump 88 relative to the ink flow direction. The first switching valve 91 switches the first flow path 89 between the second auxiliary tank 85 and the injection pump 88.

[0063] The second switching valve 92 is disposed on the second conduit 892 of the first flow path 89. The second switching valve 92 switches the first flow path 89 between the syringe pump 88 and the recording head 52. The third switching valve 95 is disposed on the fifth conduit 941 of the second flow path 94. The third switching valve 95 switches the second flow path 94.

[0064] A switching mechanism 99 is disposed on the third flow path 98. The switching mechanism 99 is, for example, composed of a clamping member that enables manual switching of the third flow path 98. The switching mechanism 99 switches the third flow path 98 on and off.

[0065] [3. Structure of an injection pump]

[0066] Figure 5 as well as Figure 6 This is an explanatory diagram of the syringe pump 88 and the drive mechanism 70, showing the actions of ink being discharged from the syringe pump 88 and ink being filled into the syringe pump 88, respectively. Figure 5 as well as Figure 6 Detailed structural description of the injection pump 88 and the drive mechanism 70.

[0067] like Figure 5 as well as Figure 6 As shown, the injection pump 88 includes a cylinder 881 (housing) formed in a cylindrical shape and a piston 882 (pressing part) formed in a circular plate shape. At one end of the cylinder 881 ( Figure 5 The right side of the container is provided with a filling port 883 (filling port), which is connected to the second auxiliary tank 85 (see reference 883) via the first conduit 891. Figure 4 ) connection; discharge port 884 (discharge outlet), which is connected to the recording head 52 (reference) via the second conduit 892. Figure 4 ) connection. The other end of cylinder 881 ( Figure 5 The left side of the hole is opened in a way that allows the piston 882 to be inserted.

[0068] The piston 882 is reciprocally fitted inside the cylinder 881. An O-ring 885 is installed between the outer circumferential surface of the piston 882 and the inner circumferential surface of the cylinder 881. The O-ring 885 seals the space enclosed by the piston 882 and the cylinder 881.

[0069] Next, the piston 882 will be directed towards the filling port 883 side and the discharge port 884 side of the cylinder 881 (one end side, Figure 5 The direction of movement (to the right) is used as the forward direction, and the piston 882 is moved towards the opening side (the other end side) of the cylinder 881. Figure 5 The direction of movement (to the left) is taken as the reversing direction. Furthermore, the reference position, i.e., the starting position HP, for the reciprocating movement of piston 882 is set near the opening side of cylinder 881. The starting position HP is the position where piston 882 moves to its maximum extent in the reversing direction (maximum extension position).

[0070] The drive mechanism 70 includes a motor 71, a pinion 72, a freewheeling gear 73, a drive output gear 74, a rack and pinion section 75, and a roller 76.

[0071] Motor 71 is controlled by control unit 7 (see reference) Figure 3 The driving force is generated by the control. A pinion 72 is fixed on the rotating shaft (drive output shaft) of the motor 71.

[0072] A freewheeling gear 73 is disposed between the pinion 72 and the drive output gear 74. The freewheeling gear 73 is a two-stage gear with a large-diameter portion 73a and a small-diameter portion 73b coaxially arranged. The large-diameter portion 73a of the freewheeling gear 73 meshes with the pinion 72. The small-diameter portion 73b of the freewheeling gear 73 meshes with the drive output gear 74.

[0073] A torque limiter 73c is built into the idler gear 73. Therefore, when a certain or greater load is applied between the large diameter section 73a and the small diameter section 73b, the large diameter section 73a and the small diameter section 73b will idle.

[0074] The drive output gear 74 is located below the rack portion 75. The roller 76 is located above the drive output gear 74, across the rack portion 75. That is, the drive output gear 74 and the roller 76 clamp the rack portion 75 from above and below.

[0075] The rack portion 75 has a rod shape extending in the moving direction of the piston 882. One end of the rack portion 75 (the end on the forward direction side) is fixed to the piston 882. Rack teeth 75a are provided on the lower part of the rack portion 75 along the long side direction (the moving direction of the piston 882). The rack teeth 75a mesh with the drive output gear 74. The piston 882 reciprocates as the rack portion 75 moves in both the forward and backward directions. A sensing portion 75b is formed at the other end of the rack portion 75 (the end on the backward direction side).

[0076] A starting position sensing unit 77 is provided on the rearward side of the rack section 75. The starting position sensing unit 77 is, for example, composed of a PI (light interruptor) sensor. Figure 5 As shown, when the piston 882 is in a forward direction position relative to the initial position HP, the sensing part 75b of the rack part 75 separates from the initial position sensing part 77. At this time, the sensing signal of the initial position sensing part 77 becomes HIGH.

[0077] If piston 882 from Figure 5 If the state moves backward and reaches the starting position HP, then as follows: Figure 6 As shown, the starting position sensing unit 77 is blocked from light by the sensing part 75b of the rack part 75. Consequently, the sensing signal of the starting position sensing unit 77 switches from a HIGH state to a LOW state. The control unit 7 senses that the piston 882 has reached the starting position HP based on the change in the sensing signal of the starting position sensing unit 77.

[0078] Next, the ink supply operation to the recording head 52 based on the syringe pump 88 will be described. During the purification of the recording head 52, the second switching valve 92 (see reference...) is kept open. Figure 4 With the first switch valve 91 (refer to the open state) set to the open state, Figure 4 Switch to the off state. Then, as follows: Figure 5 As shown, the motor 71 is rotated in the positive direction ( Figure 5 Driven in a clockwise direction. Thus, the driving force of the motor 71 is transmitted to the rack 75 via the pinion 72, idler gear 73, and drive output gear 74, and the rack 75 moves in the forward direction (clockwise). Figure 5 Move in the direction of arrow A1.

[0079] As the rack section 75 moves forward, the piston 882 of the injection pump 88 slides forward within the cylinder 881, pressing the ink within the cylinder 881. The first conduit 891, connected to the filling port 883 of the cylinder 881, is closed by the first switching valve 91. On the other hand, the second conduit 892, connected to the discharge port 884 of the cylinder 881, is opened by the second switching valve 92.

[0080] Therefore, the ink pressed inside cylinder 881 is supplied to the recording head 52 via discharge port 884 and second conduit 892. Figure 5 (Indicated by arrow B1). Furthermore, in the recording head 52, foreign objects, air bubbles, etc., inside the recording head 52 (nozzle) are ejected from the ink ejection nozzle 521 by the ink being pressed.

[0081] In the case of refilling the ink in the syringe pump 88, which was reduced due to the cleaning of the recording head 52, the first switch valve 91 is switched to the open state, and the second switch valve 92 is switched to the closed state. Then, as Figure 6 As shown, the motor 71 is rotated in the opposite direction ( Figure 6 Driven in a counter-clockwise direction. At this time, the driving force of the motor 71 is transmitted to the rack 75 via the pinion 72, the idler gear 73, and the drive output gear 74. The rack 75 moves in a backward direction (…). Figure 6 Move in the direction of arrow A2.

[0082] As the rack section 75 moves backward, the piston 882 of the injection pump 88 slides backward within the cylinder 881, reducing pressure within the cylinder 881. At this time, the second conduit 892, connected to the discharge port 884 of the cylinder 881, is closed by the second switching valve 92. On the other hand, the first conduit 891, connected to the filling port 883 of the cylinder 881, is opened through the first switching valve 91.

[0083] Therefore, with the depressurization inside cylinder 881, the ink in the second auxiliary can 85 is drawn into cylinder 881 via the first conduit 891 and filling port 883. Figure 6 (Indicated by arrow B2). Furthermore, as the rack section 75 moves backward, the sensing section 75b mounted on the rack section 75 blocks the light from the starting position sensing section 77, thereby switching the sensing signal. If the control section 7 detects that the piston 882 has moved to the starting position HP, it stops the reverse rotation drive of the motor 71.

[0084] [4. Anomaly detection and control in the ink supply department]

[0085] Next, the abnormality detection and control of the ink supply unit 8, a characteristic feature of the present invention, will be described. In the inkjet recording apparatus 1 of this embodiment, abnormalities in the ink supply unit 8 are detected based on the ink discharge and filling operation performed by the injection pump 88. More specifically, the abnormality is detected from the state of the piston 882 at the initial position HP (see...). Figure 6 Press piston 882 (moving forward) to expel ink from syringe 881. Then, measure the time from the start of the stretching action of piston 882 (moving backward) to the arrival at the starting position HP (filling syringe 881 with ink).

[0086] As described above, a torque limiter 73c is built into the idler gear 73 constituting the drive mechanism 70. In the event of abnormalities such as damage or blockage in the first flow path 89 constituting the ink supply section 8 (especially the second conduit 892), or in the event of blockage due to ink drying in the ink ejection nozzle 521 of the record head 52, the load applied to the idler gear 73 when the piston 882 is pressed to eject ink is greater than usual. Moreover, when the load exceeds a certain value, the torque limiter 73c activates.

[0087] When the torque limiter 73c is activated, the idling gear 73 idles, therefore, the pressing amount (the amount of movement in the forward direction) of the piston 882 is less than the set value. If the pressing amount of the piston 882 decreases, correspondingly, the travel time from the piston 882's extension action to reaching the starting position HP is also shorter than the reference time (the set value of the pressing amount / the extension speed). That is, if the travel time is significantly shorter than the reference time, an abnormality in the ink supply unit 8 can be detected.

[0088] Figure 7 This is a flowchart illustrating an example of the execution control of the abnormality determination mode of the ink supply unit 8 in the inkjet recording apparatus 1 of this embodiment. Refer to [the relevant documentation] as needed. Figures 1-6 ,according to Figure 7The steps outline the execution process of the anomaly detection mode during the purification operation. Furthermore, before executing the anomaly detection mode, piston 882 is positioned at the initial position HP.

[0089] First, the control unit 7 determines whether it is the time to execute the abnormality detection mode (step S1). As for the time to execute the abnormality detection mode, it is assumed that it is executed immediately after the replacement and maintenance of the ink supply unit 8 or the record head 52, when a purification operation is performed. This is to detect poor connection of the ink flow path, forgetting to connect, etc. when replacing components.

[0090] Additionally, it is assumed that the abnormality detection mode is executed during the first cleaning operation after the inkjet recording device 1 has been left unused for a long time. This is because, when the inkjet recording device 1 has been left unused for a long time, the ink near the ink ejection nozzle 521 of the recording head 52 dries out, which may generate a large load when supplying ink to the recording head 52.

[0091] When it is the execution time of the abnormal judgment mode (yes in step S1), the control unit 7 only opens the second switch valve 92 and closes the first switch valve 91 and the third switch valve 95 (step S2).

[0092] Next, the control unit 7 sends a control signal to the motor 71 to press the piston 882, which is located at the starting position HP, with a preset pressing amount (set pressing amount) (step S3). The set pressing amount is the same as the pressing amount during the cleaning operation. The amount of ink extruded required for cleaning the recording head 52 varies depending on factors such as the placement time from the start of the final printing operation and the usage status of the inkjet recording device 1. Therefore, the pressing amount (set pressing amount) of the piston 882 during the cleaning operation also varies depending on the timing of the cleaning operation. The set pressing amount can be adjusted by the number of drive pulses when the motor 71 is a stepper motor, and by the drive time (power-on time) when the motor 71 is a brushed motor or a brushless motor.

[0093] Next, control unit 7 opens only the first switching valve 91, and closes the second switching valve 92 and the third switching valve 95 (step S4). Then, a control signal is sent to motor 71 to start the stretching action of piston 882 (step S5). At the same time, control unit 7 starts based on timer 78 (refer to...). Figure 3 The movement time T of the ) is determined (step S6).

[0094] Next, the control unit 7 determines whether the piston 882 has reached the starting position HP (step S6). Specifically, it determines whether the sensing unit 75b of the rack unit 75 blocks the light from the starting position sensing unit 77, and the sensing signal switches from the HIGH state to the LOW state. If the piston 882 has reached the starting position HP (yes in step S7), the control unit 7 ends the measurement of the movement time T based on the timer 78 (step S8).

[0095] Next, the control unit 7 determines whether the movement time T measured in steps S6 to S8 is shorter than the threshold Ts (step S9). The threshold Ts is the minimum time required for the piston 882 to extend (move from the pressing position to HP). The threshold Ts is calculated using the following formula (1).

[0096] Ts[sec]=(Set pressing amount[mL] / Stretching speed[mL / sec])×k···(1)

[0097] As shown in equation (1), the threshold Ts is determined by calculating the ratio of the completion time of the original stretching action (set pressure / stretching speed). k is a coefficient for determining the ratio, and when the threshold is set to 50% of the completion time of the original stretching action, k = 0.5.

[0098] If the travel time T is shorter than the threshold Ts (yes in step S9), it is considered that a certain or higher load is applied to the idle gear 73, thereby the torque limiter 73c is activated, the idle gear 73 idles, and the pressing amount of the piston 882 is smaller than the set value.

[0099] At this time, the control unit 7 determines that the ink supply unit 8 has malfunctioned (step S10). Then, the control unit 7 notifies the user of the malfunction of the ink supply unit 8 (step S11). For example, in the liquid crystal display unit 79 (refer to...) Figure 3 The display shows that an abnormality has occurred in the ink supply section 8 and the location of the abnormality.

[0100] If the travel time T is greater than or equal to the threshold Ts (not in step S9), the control unit 7 determines that the ink supply unit 8 has not experienced any abnormality and ends the abnormality determination mode.

[0101] according to Figure 7 The control example shown can detect abnormalities in the ink supply unit 8 using only the existing torque limiter 73c, start position sensing unit 77, and timer 78 without adding any additional components for sensing abnormalities in the ink supply unit 8. Furthermore, by sensing abnormalities using the time required for the piston 882 to return to the start position HP, abnormalities can be detected by comparing all ink flow paths downstream of the injection pump 88, preventing excessive pressure from being applied to the recording head 52.

[0102] Furthermore, the set pressure amount of piston 882 and the threshold Ts for detecting abnormalities can be adjusted by the control unit 7, thus allowing for appropriate changes based on the usage environment and usage time of the inkjet recording device 1. As described above, the threshold Ts is determined by calculating the ratio of the completion time of the original stretching action (set pressure amount / stretching speed), therefore, even when the set pressure amount of piston 882 is different, an appropriate threshold Ts corresponding to the set pressure amount can be easily determined.

[0103] In addition, Figure 7 In the control example shown, if the travel time T is shorter than the threshold Ts, it is immediately determined that there is an abnormality in the ink supply unit 8. However, in order to prevent false detection, it is also possible not to immediately determine that there is an abnormality if the travel time T is shorter than the threshold Ts. Instead, the abnormality determination mode is executed again when the next purification operation is performed, and the abnormality in the ink supply unit 8 is determined only if the travel time T is shorter than the threshold Ts.

[0104] [5. Other]

[0105] This invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiments, a torque limiter 73c is provided on the idler gear 73 of the drive mechanism 70 constituting the piston 882, but torque limiters may also be provided on other gears constituting the drive mechanism 70 (e.g., the drive output gear 74).

[0106] In addition, in the above embodiment, the case where the paper S is attracted to the first conveyor belt 411 by negative pressure attraction for conveying is described, but it is also possible to make the first conveyor belt 411 charged so that the paper S is electrostatically attracted to the first conveyor belt 411 for conveying (electrostatic adsorption method).

[0107] Furthermore, in the above embodiment, an example of using a color printer was described as the inkjet recording device 1. This color printer uses four-color ink to record color images. However, even if a monochrome printer that only uses black ink to record monochrome images is used, the anomaly detection mode of this embodiment can still be used.

[0108] This invention can be used in inkjet printers and other inkjet recording devices.

Claims

1. An inkjet recording device comprising: A recording head, which has multiple nozzles that eject ink; An ink container that holds the ink; An ink supply unit includes a secondary container, an ink flow path, and an injection pump. The secondary container temporarily stores the ink supplied from the ink container. The ink flow path allows the ink to circulate from the secondary container through the recording head to the secondary container. The injection pump has a cylinder and a piston. The cylinder is positioned downstream of the secondary container and upstream of the recording head relative to the ink flow direction of the ink flow path. One end of the cylinder has a discharge port connected to the recording head and a filling port connected to the secondary container, while the other end is open. The piston is inserted into the cylinder and is movable in a direction approaching one end and another direction approaching the other end. The drive mechanism performs a pressing action that moves the piston toward one end and a stretching action that moves the piston toward the other end. A timer that measures the time it takes for the piston to move; A starting position sensing unit senses that the piston is in the starting position; and The control unit controls the drive mechanism. The inkjet recording device is characterized in that... The drive mechanism has: motor; One or more gears that transmit the driving force of the motor to the piston; and A torque limiter, mounted on either of the gears, When the control unit performs a purification operation by forcibly extruding the ink from the nozzle of the recording head using the injection pump... After pressing the piston at the starting position with a preset pressing amount, the timer measures the movement time from the start of the stretching action to reaching the starting position. The system is capable of executing an anomaly detection mode, which determines that an anomaly has occurred in the ink supply unit when the movement time is shorter than a threshold.

2. The inkjet recording device according to claim 1, characterized in that, The threshold is determined by a ratio to the time required for the piston, pressed with the set pressure amount, to move to the starting position by the stretching action.

3. The inkjet recording device according to claim 1, characterized in that, The control unit executes the abnormality determination mode immediately after the purification operation is performed following the replacement and maintenance of the ink supply unit or the recording head.

4. The inkjet recording device according to claim 1, characterized in that, The control unit executes the anomaly detection mode when performing the purification operation for the first time after the inkjet recording device has been left unused for an extended period.

5. The inkjet recording device according to claim 1, characterized in that, When performing the purification action, the control unit executes the anomaly detection mode, and if the movement time is shorter than the threshold... The anomaly detection mode is executed again during the next purification operation, and the ink supply unit is determined to be abnormal only if the movement time is shorter than the threshold.

6. The inkjet recording apparatus according to any one of claims 1 to 5, characterized in that, The system includes a notification unit that notifies the ink supply unit of an abnormality. If the control unit determines that an abnormality has occurred in the ink supply unit when executing the abnormality determination mode, it uses the notification unit to notify of the occurrence of the abnormality.

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