JP3800855B2 - Inkjet head maintenance mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an inkjet head maintenance mechanism, and more particularly to a technique for recovering an inkjet head by sucking air bubbles or defective ink in the inkjet head.
[0002]
[Prior art]
  Conventionally, a maintenance mechanism (generally referred to as a purge device) that sucks bubbles, defective ink, and the like from a large number of ink ejection channels in the head in order to maintain a state in which ink is normally ejected by an inkjet head (hereinafter referred to as a head). Is used). As shown in FIG. 6, the maintenance mechanism includes a suction cap 20 that performs a contact / non-contact operation with respect to a nozzle row provided in the head 2.'And a negative pressure generating pump 17 for generating a negative pressure to suck ink, and a suction cap 20'The suction port 45 leading to the negative pressure generating pump 17 is provided at a position facing the nozzle row. When sucking bubbles or defective ink in the head 2, the negative pressure generating pump 17 is driven with the suction cap 20 ′ in contact with the nozzle row portion of the recording head. Thus, ink is sucked from the channel 41 communicating with each nozzle 43, and bubbles, defective ink, and the like are sucked together with the ink. A manifold 42 is fixed to the side of the head 2 opposite to the side on which the suction cap 20 ′ contacts, and ink is supplied from an ink cartridge (not shown) through the manifold 42.
[0003]
[Problems to be solved by the invention]
  However, according to the conventional head maintenance mechanism as described above, since the suction port 45 of the suction cap 20 ′ is provided only at a position facing the vicinity of the center in the nozzle row direction of the head 2, When sucking, the ink in the channel 41 near the center of the head 2 tends to flow, but the ink in the channel 41 near the head end is difficult to flow. In particular, when the manifold 42 has a shape that extends from the center of the channel row to both ends, the tendency is more remarkable when the suction port 45 is also in the center. Therefore, it has been difficult to remove bubbles and defective ink in the channel 41 near the head end. In addition, today, the length of the nozzle row tends to increase, and this problem will become more prominent in the future.
  Further, when ink is initially introduced into the head, air tends to remain at the end of the manifold 42, and therefore it is necessary to take a long time to discharge the air to suck a large amount of ink. Furthermore, it is empirically recognized that bubbles are likely to stagnate in the vicinity of the end portion of the manifold 42 while ink is ejected. To discharge these bubblesManyThe amount of ink had to be sucked, wasting time and ink.
[0004]
  The present invention has been made to solve the above-described problems, and controls the flow of ink in the channels at the center and end of the head as needed to quickly introduce ink into the head. An object of the present invention is to provide a head maintenance mechanism that can efficiently remove bubbles and defective ink.
[0005]
[Means for Solving the Problems]
  In order to achieve the above object, the invention described in claim 1 is used in a recording apparatus that performs recording by ejecting ink onto a recording medium from a plurality of nozzles of an inkjet head, and contacts the inkjet head with the nozzle. In the maintenance mechanism for sucking ink from the inkjet head, a negative pressure generating means for generating a negative pressure for sucking ink and a negative pressure generating means are respectively connected to the nozzle row formed by a plurality of nozzles.The nozzle array is divided into a substantially central portion and both sides of the nozzle array, and is provided at a position facing the nozzle array.A capping unit having a plurality of suction ports, a capping unit for capping the nozzle row, a driving unit for abutting and non-contacting the capping unit with the nozzle row, and a negative pressure by a negative pressure generating unit for the plurality of suction ports Control means for selectively acting,When the ink is initially introduced, the control means first generates a negative pressure only at the suction port provided at the substantially central portion of the nozzle row, and then only the suction ports provided at both sides of the suction port provided at the substantially central portion. Negative pressure is generated at the end, and finally negative pressure is generated at the substantially central portion and suction ports provided at both sides thereof. During periodic purge, the negative pressure is applied only to the suction ports provided at both sides of the substantially central portion of the nozzle array. Was controlled to generateIs.
[0006]
  In the above configuration, since the control means can selectively apply the negative pressure generated by the negative pressure generating means to the plurality of suction ports, the channel in each part of the head can be used depending on the purpose such as initial ink introduction or bubble removal. It is possible to control the flow of ink with respect to the ink, to quickly introduce ink, and to properly remove bubbles and defective ink.In addition, since the suction port is provided at a position opposite to the nozzle row, which is divided into a substantially central portion of the nozzle row and both sides of the nozzle row, a negative pressure is selectively applied to the suction port, so that the center of the inkjet head It becomes possible to arbitrarily control the ink flow rate of the channel in the vicinity of the portion or the end portion. Furthermore, since ink is sucked sequentially using the substantially central portion of the nozzle row and suction ports on both sides at the time of initial ink introduction, all the channels in the head are quickly filled with ink, and bubbles tend to accumulate during periodic purging. It is possible to increase the ink flow velocity in the channel near the end, and to remove air bubbles and defective ink as needed.
[0007]
  ContractA second aspect of the present invention is the maintenance mechanism for an ink jet head according to the first aspect, wherein the plurality of suction ports communicate with the negative pressure generating means via a plurality of communication passages, respectively, and control means Has an opening and closing mechanism for selectively opening and closing a plurality of communication paths.
[0008]
  In the above configuration, the negative pressure of the negative pressure generating means is selectively applied to the plurality of suction ports by selectively opening and closing the plurality of communication paths by controlling the opening / closing mechanism by the control means. Therefore, it is not necessary to provide a negative pressure generating means for each suction port in order to select whether to generate a negative pressure at the suction port, and it is possible to select the suction port with a simple configuration and control. it can.
[0009]
[0010]
[0011]
[0012]
[0013]
  Claim 3The invention described in claim 1Or claim 2In the inkjet head maintenance mechanism described above, the control means includes a key member that arbitrarily applies a negative pressure generated by the negative pressure generating means to the plurality of suction ports.
[0014]
  In the above configuration, when the user looks at the recording result and finds an ejection failure of some channels, by operating the key member, a negative pressure is applied to the suction port near the channel where the failure has occurred, The suction on the channel can be enhanced.
[0015]
  Claim 4The invention described in claim 1 to claim 1Claim 3The maintenance mechanism for an inkjet head according to any one of the above, wherein the driving means and the negative pressure generating means are capable of suctioning each inkjet head with respect to a recording apparatus including a plurality of inkjet heads for color recording. Are controlled by
[0016]
  In the above configuration, since the suction operation of each inkjet head by the driving unit and the negative pressure generating unit is enabled for a recording apparatus including a plurality of inkjet heads, bubbles and defects of the plurality of inkjet heads can be obtained with a single maintenance mechanism. Ink can be removed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, an ink jet head maintenance mechanism according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a printer including an inkjet head maintenance mechanism according to an embodiment of the present invention. A color ink jet printer (hereinafter referred to as a printer) 1 includes four ink jet heads 2 that perform recording by ejecting ink of four colors (cyan, magenta, yellow, black) onto a recording medium P such as printing paper. 2, 2 and 2. Each head 2 is provided with a nozzle (shown in FIG. 4) for ejecting each of the four colors of ink, and is held on a carriage 3 that is linearly driven back and forth during recording. ing. Each head 2 is provided integrally with the head holder 4, and ink cartridges 5 a, 5 b, 5 c, 5 d for supplying four colors of ink to each head 2 are detachably mounted on the carriage 3. The front portion of the carriage 3 is supported by a carriage shaft 7 and is movable along the carriage shaft 7. The rear part of the carriage 3 is slidably supported on the guide plate 8. The reciprocating movement of the carriage 3 is driven by a carriage motor 9 via a belt 10.
[0018]
  A platen roller 11 is provided at a position facing the head 2. The platen roller 11 is driven by a driving force of a line feed motor (not shown). The recording medium P is transported to a position facing the head 2 by the platen roller 11 and recording is performed. A maintenance mechanism 15 is provided on the side of the platen roller 11. The head 2 may cause ejection failure due to bubbles generated inside the head 2 or ink droplets adhering to the nozzle opening surface, which can be eliminated and recovered to a good ejection state. There is a maintenance mechanism 15 for this purpose. The maintenance mechanism 15 is also driven when the head 2 or the ink cartridges 5a to 5d are converted, and has a function of filling the head 2 with ink. A capping device 16 for protecting the head is provided on the side of the maintenance mechanism 15.
[0019]
  The maintenance mechanism 15 is provided with a suction cap 20 for purging the head 2. FIG. 2 shows a front view of the suction cap 20 and the capping device 16 portion. A portion of the suction cap 20 is in contact with a cam provided on the pump cam gear 25 that is rotated by the line feed motor. When this cam rotates, the suction cap 20 moves in a direction in which the suction cap 20 abuts or does not abut against the head 2 along the shape of the cam. As a result, the contact / non-contact operation of the suction cap 20 with respect to the nozzle row is performed. For purging the head 2, with the suction cap 20 in contact with the nozzle portion of the head 2, a negative pressure is generated by the pump (negative pressure generating means) 17 to suck bubbles, defective ink, and the like inside the head 2. By doing. The sucked defective ink is sent to the storage unit 18. By this purge operation, the head 2 is restored to a state where normal ink ejection is possible. The pump 17 is also driven by the rotation of the pump cam gear 25. The suction cap 20 performs a suction operation on each of the four heads. When suction on one head is finished, the other head is moved to a position facing the suction cap 20, and suction on the head is performed. Followed by A wiper 21 for wiping the nozzles of the head 2 is provided on the side (recording area side) of the suction cap 20.
[0020]
  The capping device 16 is provided with four caps 16a, 16b, 16c and 16d for each nozzle in order to perform capping on each nozzle of the four heads 2. The capping device 16 is configured to contact the nozzles of the head 2 when the carriage 3 has moved to the capping position. Thereby, a nozzle part is sealed and drying of a nozzle and ink is prevented.
[0021]
  FIG. 3 shows a block diagram of the control system of the printer 1. The printer 1 is provided with control means including a G / A (gate array) circuit 28 that controls recording data processing and the like, and a CPU 29 that controls the entire printer 1 and the like. A host computer 31 is connected to the G / A circuit 28 via an interface unit 30, and an image memory 32 that stores recording data received from the host computer 31 is also connected. Further, a ROM 35 storing a program for controlling the drive mechanism of the carriage 3, the transport mechanism of the recording medium P, the maintenance mechanism 15 and the like, and a RAM 36 storing control data for each functional block are connected to the G / A circuit 28 and the CPU 29. Has been.
[0022]
  The CPU 29 has an operation panel for operating each operation of the printer 1.37Is connected. The carriage motor 9, the recording medium P conveying motor 39 and the pump 17 driving motor 39 are also controlled by the CPU 29. Further, the CPU 29 controls the opening and closing of valves (opening / closing mechanisms) 51, 52, and 53 that open and close the communication passage that communicates with the suction port provided in the suction cap 20. A head driver 54 for driving the head 2 is connected to the G / A circuit 28, and recording data, a transfer clock, a print clock, and a latch signal are transmitted from the G / A circuit 28 to the head driver 54. Is done. The CPU 29 is a sensor provided for detecting the contact / non-contact state of the suction cap 20 to the head 2, and is based on rotation of a cam provided integrally with the pump cam gear 25. A detection signal is sent from the sensor 55 that is turned on and off.
[0023]
  The suction cap 20 will be described with reference to FIG. FIG. 4 is a sectional view showing a state in which ink is sucked from the head 2 by the suction cap 20. Each head 2 has a nozzle row composed of a plurality of nozzles 43, and a plurality of channels serving as ink flow paths having actuators for selectively ejecting ink from each nozzle 43 corresponding to the nozzle rows 41 is provided. Ink supplied from the ink cartridges 5 a to 5 d (FIG. 1) is filled into the plurality of channels 41 through the manifold 42. The manifold 42 has a tapered flow path that expands from the center of the row formed by the channels 41 toward both ends. The ink in the channel 41 selectively drives the actuator based on the recording data, whereby the wall surface of the channel 41 is deformed, whereby the internal volume of the channel 41 is changed, whereby each ink corresponding to each channel 41 is changed. The ink is selectively ejected from the nozzle 43 toward the recording medium. The ejected ink lands on the recording medium, thereby recording an image. The nozzle rows formed by the nozzles 43 are arranged in the row direction in a direction orthogonal to the moving direction of the carriage 3.
[0024]
  The suction cap 20 is made of a rubber material or the like, and has a contact portion 47 for contacting the periphery of the nozzle row and surrounding the nozzle row portion to form a sealed space 48. The suction cap 20 is provided with a plurality of suction ports 45 (three in this example) that open into the sealed space 48. These suction ports 45 are provided at positions facing the nozzle rows, and at positions facing the substantially central portion of the nozzle rows and the nozzle rows on both sides thereof. Each of the three suction ports 45 communicates with the pump 17 via the communication path 46. Each communication path 46 is provided with valves 51, 52, and 53 that open and close the communication path 46. The valves 51, 52, 53 are driven by solenoids or the like, and the opening / closing operation is controlled by the control means such as the CPU 29 as described above.
[0025]
  The opening / closing operation of the valves 51, 52, 53 is controlled according to the situation in which the purge command is issued during the recording operation. For example, when the exchange of the head 2 or the ink cartridges 5a to 5d is detected by a known detection mechanism, the control means such as the CPU 29 is charged with ink from the ink cartridge to each channel 41 of the head 2, that is, purge for initial introduction. A command is issued, and the valves 51, 52, 53 are sequentially opened and closed as will be described later, and the pump cam gears of the pump 17 and the suction cap 20 are driven. A purge command for removing bubbles generated in the channel and manifold of the head 2 when a predetermined time is counted from the previous purge command by a timing operation of a timer unit configured in the control means such as the CPU 29 (periodic time described later). (Purge), and valves 51, 52, and 53 are opened and closed as will be described later to drive the pump 17 and the pump cam gear 25 of the suction cap 20. In addition, when the user looks at the recorded results and finds an injection failure in some channels,37The valve 51, 52, 53 provided in the above is selected and a key for instructing a purge operation is operated to open and close any valve 51, 52, 53 as will be described later, and the pump cam gear of the pump 17 and the suction cap 20 25 is driven.
[0026]
  When the suction cap 20 configured as described above is brought into contact with the nozzle row portion of the head 2, a sealed space 48 is formed in the nozzle row portion by the contact portion 47. When the pump 17 is driven by opening the valve of the suction port 45 in this state, the inside of the sealed space 48 becomes negative pressure through the suction port 45, and the ink in the channel 41 is sucked out from each nozzle 43 and sucked port 45. Sucked into. At the time of this suction, by opening only the valve of the suction port 45 used for suction and closing the valves of the other suction ports, the ink suction of the portion of the head 2 where air bubbles or the like are to be removed is reinforced. Can do.
[0027]
  Control of the opening / closing operation of the valves 51, 52, 53 during the purge will be described with reference to FIG. FIG. 5 shows a flow of processing for controlling the opening / closing operation of the valves 51, 52, and 53. If there is a purge command, it is determined whether or not the purge is performed at the initial introduction of ink after replacement of the head 2 or the ink cartridge (step S1). In the case of purge at the time of initial ink introduction (S1: YES), the pump 52 is first opened and the valves 51 and 53 are closed, and the pump cam gear 25 is rotated once to perform one purge (S2). Next, purge is performed with the valves 51 and 53 open and the valve 52 closed (S3), and finally purge is performed with all the valves 51, 52 and 53 opened (S4). At the time of initial ink introduction, ink must be introduced into the channel 41 from the ink cartridges 5a to 5d. Therefore, strong suction is performed by a plurality of purges, and the manifold 42 is enlarged in a taper shape. Air is likely to remain at both end portions of 42 and ink is not easily introduced into the channels 41 at both end portions, but by changing the suction port 45 used for each purge as described above and changing the portion that enhances suction, Ink is introduced uniformly into each channel 41 without leaving air.
[0028]
  If the purge is not performed at the time of initial ink introduction in step S1 (S1: NO), it is determined whether the purge command is issued by operating the key on the operation panel 38 (S5). When the purge command is a key operation, that is, when the user instructs the start of purge (S5: YES), the purge is performed with the valve selected by the user's key operation at the time of the purge command being opened (S6). . In this way, by enabling the user to select the suction port 45, it is possible to enhance ink suction (removal of bubbles or the like) for a nozzle (channel) portion where ink ejection is abnormal. If the purge command is not operated by the purge key operation in S5, it is determined that the purge is a regular purge (S5: NO), and the purge is performed with the valves 51 and 53 open and the valve 52 closed (S7). At the time of this suction, since the sealed space 48 is set to a negative pressure from the two suction ports 45 provided separately in the nozzle row direction, the difference in the negative pressure applied to each channel 41 is reduced. Therefore, the flow rate of ink sucked from the end of the nozzle row is increased (conventionally, the flow rate of ink at this portion is slow), and the ink in the manifold 42 is positioned at either the central portion or the end portion in the head 2. The channel 41 also flows at a substantially uniform flow rate. Therefore, the amount of ink sucked out from each nozzle 43 becomes almost uniform, and ink suction suitable for regular purge that requires uniform ink suction to each channel 41 can be performed.
[0029]
  As described above, according to the maintenance mechanism of the inkjet head of the present embodiment, the suction port 45 used for ink suction can be selected by controlling the opening / closing operation of the valves 51, 52, 53 by the CPU 29. Therefore, the ink suction force with respect to the channel in each part of the head can be changed as necessary. As described above, when ink is initially introduced into the head 2, air is left in the manifold 42 by switching the suction ports 45 at the center and both ends, or sequentially performing the purge operation simultaneously performed from all the suction ports 45. Therefore, it is possible to quickly fill all the channels 41 with ink. Further, during the recording operation, air bubbles are generated near both ends of the manifold 42 with the passage of time, and it is easy to stagnate. Therefore, when performing periodic purge, a negative pressure is generated only at the suction ports 45 at both ends, and the conventional flow velocity is increased. It is possible to increase the flow velocity at both ends, which is slow, and effectively suck bubbles and defective ink. In any case, since residual air and bubbles can be quickly removed, the amount of ink to be discharged can be reduced and the purge amount can be reduced.
[0030]
  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above embodiment, suction from the three suction ports 45 is performed by one pump 17, and the suction ports 45 used for ink suction are selectively used by opening / closing control of the valves 51, 52, and 53. You may make it provide a pump in the communicating path for every suction port. In this case, the suction ports 45 used for ink suction are selectively used by driving or stopping the pumps of the respective suction ports. In the above embodiment, the maintenance apparatus according to the present invention is used in a recording apparatus that supplies ink to the head 2 using an ink cartridge. However, the maintenance apparatus according to the present invention is applied to a recording apparatus that employs another ink supply system. Is also applicable. For example, the maintenance apparatus according to the present invention can be applied even to a recording apparatus that supplies ink from an ink supply source to a recording head by a tube.
[0031]
  In the above embodiment, the suction cap 20 is provided with the three suction ports 45, and the suction ports 45 are provided in the substantially central portion of the nozzle row and on both sides thereof. Any suction port may be used as long as it is configured to be capable of controlling the opening and closing of the communication path of each suction port. Further, the number and positions of the suction ports 45 are not limited to the above embodiment. For example, the suction port of the portion where the suction force is to be increased is made larger than the other suction ports (for example, the suction port near the recording head end is formed larger than the suction port near the center), or the suction force is increased. By providing more suction ports in the part you want to enlarge than other parts (for example, providing more suction ports near the end of the print head than near the center), the suction force at each part of the print head It is possible to make changes.
[0032]
【The invention's effect】
  ContractAccording to the first aspect of the present invention, since the negative pressure generated by the negative pressure generating means can be selectively applied to the plurality of suction ports, each part of the head can be used in accordance with purposes such as initial ink introduction or bubble removal. Can control the flow of ink to the channels. This enhances ink suction on some channels of the head, effectively removes residual air, bubbles, and defective ink in that part, and quickly introduces ink or restores the ejection function in a short time It becomes possible to do.In addition, since the suction port is provided at a position opposite to the nozzle row, which is divided into a substantially central portion of the nozzle row and both sides of the nozzle row, a negative pressure is selectively applied to the suction port, so that the center of the inkjet head It becomes possible to control the ink flow rate of the channel in the part or the vicinity of the end part, and it is possible to effectively remove the residual air and bubbles at the end part, and to quickly restore the ink introduction and ejection function. In addition, when ink is initially introduced, ink is sucked sequentially using the substantially central portion of the nozzle row and suction ports on both sides thereof, so that all the channels in the head can be properly filled with ink, and regular At the time of purging, ink is sucked using the suction ports provided on both sides of the substantially central portion of the nozzle row, so that the ink flow rate in the channel near the head end where air bubbles and defective ink tend to accumulate can be increased. Accordingly, it is possible to remove appropriate bubbles and defective ink according to the initial ink introduction or the periodic purge.
[0033]
  ContractAccording to the invention described in claim 2, since the suction port used for ink suction can be selected by controlling the operation of the opening and closing mechanism, a negative pressure is applied to each suction port with a simple configuration and control. Can act selectively. Thereby, the manufacturing cost of this maintenance mechanism can be suppressed to low cost.
[0034]
[0035]
[0036]
  Claim 3According to the invention described in the above, since the negative pressure can be applied to an arbitrary suction port by operating the key member, when the user looks at the recorded result and finds an ejection failure of some channels, The suction to the channel can be strengthened and the injection failure can be quickly recovered.
[0037]
  Claim 4According to the invention described in the above, it is not necessary to have a maintenance mechanism for each of the plurality of inkjet heads because the ink suction operation is possible with respect to the plurality of inkjet heads with one maintenance mechanism. It is possible to reduce the size of the apparatus and the manufacturing cost.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a schematic configuration of a printer including an inkjet head maintenance mechanism according to an embodiment of the present invention.
FIG. 2 is a front view of a suction cap and a capping device portion.
FIG. 3 is a block diagram of a control system of the printer.
4 is a cross-sectional view taken along the line AA in FIG. 2 and showing a state in which ink is sucked from the recording head by a suction cap.
FIG. 5 is a flowchart showing the flow of processing in the case of controlling the opening / closing operation of each valve.
FIG. 6 is a cross-sectional view illustrating a state in which ink is sucked from a recording head by a conventional maintenance mechanism.
[Explanation of symbols]
1 Printer
2 Inkjet head
15 Maintenance mechanism
17 Pump (negative pressure generating means)
20 Suction cap (capping means)
25 Pump cam gear (drive means)
41 channels
43 nozzles
45 Suction port
46 communication path
51, 52, 53 Valve (opening / closing mechanism)

Claims (4)

In a maintenance mechanism that is used in a recording apparatus that performs recording by ejecting ink onto a recording medium from a plurality of nozzles of an inkjet head, and abutting the inkjet head and sucking ink in the inkjet head from the nozzle,
Negative pressure generating means for generating a negative pressure for sucking ink;
The nozzles communicated with the negative pressure generating means, arranged in the direction of the nozzle row formed by the plurality of nozzles , divided into a substantially central portion of the nozzle row and both sides of the nozzle row, and provided at positions facing the nozzle row. A capping unit having a plurality of suction ports and capping the nozzle row;
Driving means for abutting / non-abutting the capping means with respect to the nozzle row;
Control means for selectively applying a negative pressure by the negative pressure generating means to the plurality of suction ports ,
When the ink is initially introduced, the control means first generates a negative pressure only at the suction port provided at the substantially central portion of the nozzle row, and then the suction provided at both sides of the suction port provided at the substantially central portion. A negative pressure is generated only at the mouth, and finally, a negative pressure is generated at the suction port provided at the substantially central portion and the both sides thereof. A maintenance mechanism for an inkjet head, wherein only a negative pressure is controlled to be generated .   The plurality of suction ports communicate with the negative pressure generating means through a plurality of communication paths, respectively, and the control means has an opening / closing mechanism for selectively opening and closing the plurality of communication paths. A maintenance mechanism for an inkjet head according to claim 1. Said control means, said plurality of ink jet head maintenance mechanism according to claim 1 or claim 2 characterized in that it has a key member to arbitrarily act negative pressure by said negative pressure generating means with respect to the suction port . 2. A recording apparatus comprising a plurality of ink jet heads for color recording, wherein the driving means and the negative pressure generating means are controlled so as to enable a suction operation of each ink jet head. Item 4. The maintenance mechanism for an inkjet head according to any one of Items 3 to 4.

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