JP2012076261A - Inkjet printing apparatus - Google Patents

Abstract

A nozzle cleaning process is executed promptly and efficiently.
An ink jet head that discharges ink from a nozzle to a print medium, a head cap 143a that is detachably attached to the ink jet head and covers the nozzle in a sealed state from the outside air when attached, and a head cap The ultrasonic wave generation element 155 that generates ultrasonic waves and the head cap 143a are attached to the inkjet head, and ink is stored in the head cap 143a so as to immerse the nozzle. A control unit 70 that generates ultrasonic waves is provided.
[Selection] Figure 3

Description

  The present invention relates to an inkjet printing apparatus that performs printing on printing paper by ejecting ink with an inkjet head.

  In general, an inkjet printing apparatus to which an inkjet method is applied prints images, characters, and the like by ejecting ink from a nozzle of an inkjet head toward printing paper based on print data such as image information and character information. In addition, since print data can be printed in color on printing paper using multi-color ink, it is widely used for home use and business use.

  In such an ink jet printing apparatus, a process of forcibly discharging or sucking ink from the ink jet head by driving a pump is performed for the purpose of removing or removing unnecessary substances such as dry ink on the surface of the ink jet head to prevent or eliminate nozzle clogging. (Hereinafter referred to as a purge operation) is periodically performed (see, for example, Patent Document 1).

  Patent Document 2 also discloses that a maintenance mechanism includes at least one startable ultrasonic transducer disposed at a distance from a nozzle, and an ultrasonic transducer for transmitting ultrasonic energy via a fluid medium. Inkjet printing apparatus comprising a thin layer of viscous fluid formed between orifice plates in contact with them and means for performing a cleaning process to activate the ultrasonic transducer and cause the ultrasonic transducer to generate ultrasonic waves Has been proposed.

JP 2004-106304 A JP 2000-94702 A

  However, in the ink jet printing apparatus described in Patent Document 1, the purge operation is executed for the purpose of removing unnecessary objects, but there are cases where the unnecessary objects cannot be sufficiently removed only by the purge operation.

  Further, in the ink jet printing apparatus described in Patent Document 2, it is necessary to cause the ultrasonic transducer to generate ultrasonic waves after moving the carriage provided with the ink jet head to the maintenance mechanism. There was a problem that time was required and this delayed the start of printing.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet printing apparatus that performs nozzle cleaning processing quickly and efficiently.

  In order to achieve the above object, a first feature of an ink jet printing apparatus according to the present invention is an ink jet head that discharges ink from a nozzle to a print medium, and a state in which the ink jet head is detachably provided and attached. A head cap that covers the nozzle in a sealed state from outside air, an ultrasonic wave generating means that is provided on the head cap and generates ultrasonic waves, and the head cap is attached to the inkjet head so as to immerse the nozzle. And a control means for causing the ultrasonic wave generating means to generate ultrasonic waves after storing ink in the head cap.

  A second feature of the ink jet printing apparatus according to the present invention is that, when the elapsed time from the time when ink is finally discharged from the nozzle exceeds a preset standby movement setting time, the control means A head cap is attached to the inkjet head.

  A third feature of the ink jet printing apparatus according to the present invention is that the control means causes the ultrasonic wave generating means to generate an ultrasonic wave while causing the ink jet head to discharge ink from a nozzle.

  A fourth feature of the ink jet printing apparatus according to the present invention is that a waste ink tank for storing the ink, the waste ink tank and the head cap are connected, and the ink stored in the head cap is used for the waste ink tank. And an ink discharge path for discharging the ink.

  According to the first feature of the ink jet printing apparatus according to the present invention, the ink jet head for discharging ink from the nozzle to the print medium, and the ink jet head are detachably provided, and the nozzle is sealed from the outside air in the mounted state. A head cap that covers the head cap, an ultrasonic wave generating means that generates ultrasonic waves, and a head cap that is attached to the inkjet head, and after storing ink in the head cap so as to immerse the nozzle Since the ultrasonic generating means is provided with a control means for generating an ultrasonic wave, when the ink is not discharged for a long time, it is possible to stand by with the head cap mounted on the inkjet head. Thereby, when executing the cleaning process, it is possible to generate an ultrasonic wave from the standby state, so that the cleaning process can be executed promptly and efficiently.

  According to the second feature of the ink jet printing apparatus according to the present invention, the head cap is attached to the ink jet head when the elapsed time from the time when the ink is finally discharged from the nozzle exceeds the preset standby movement set time. Therefore, the cleaning process can be executed quickly and efficiently.

  According to the third feature of the ink jet printing apparatus according to the present invention, since the ultrasonic wave is generated by the ultrasonic wave generating means while discharging the ink from the nozzle to the ink jet head, the cleaning process can be executed more efficiently. .

  According to the fourth aspect of the ink jet printing apparatus of the present invention, the waste ink tank for storing ink, the waste ink tank and the head cap are connected, and the ink stored in the head cap is discharged to the waste ink tank. The ink discharge path is further provided, so that the ultrasonic wave generated by the ultrasonic wave generation means propagates and the ink discharge path is also ultrasonically cleaned.

It is a block diagram which shows the structure of the inkjet printing apparatus which is one Embodiment of this invention. It is the figure which showed typically the maintenance unit with which the inkjet printing apparatus which is one Embodiment of this invention is provided. It is a perspective view of the head cap of the maintenance unit with which the inkjet printing apparatus which is one Embodiment of this invention is provided. It is the figure which showed the function structure of the inkjet printing apparatus which is Example 1 of this invention. It is the flowchart which showed the process sequence in the inkjet printing apparatus which is one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In one embodiment of the present invention, line-type image formation is provided in which a plurality of inkjet heads each having a large number of nozzles are provided, and black or color ink is ejected from each inkjet head and printing is performed on a printing sheet line by line. The apparatus will be described as an example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Overall configuration of inkjet printing apparatus>
The structure of the inkjet printing apparatus 1 which is one Embodiment of this invention is demonstrated in detail.

  FIG. 1 is a configuration diagram illustrating a configuration of an inkjet printing apparatus 1 according to an embodiment of the present invention.

  As shown in FIG. 1, the inkjet printing apparatus 1 includes a side paper feed unit 10, an internal paper feed unit 20, a printing unit 30, a paper discharge unit 40, and a reversing unit 50.

  The side paper feeding unit 10 includes a paper feeding table 11 on which the printing paper W is stacked, and a primary paper feeding unit 12 that conveys only the uppermost printing paper W from the paper feeding table 11 onto the paper feeding conveyance path FR. And a secondary paper feeding unit 14 for carrying the printing paper W conveyed by the primary paper feeding unit 12 onto the circulation conveyance path CR.

  The internal paper feed unit 20 includes a paper feed tray 21a on which the print papers W are stacked, and a primary paper feed unit 22a that transports only the uppermost print paper W from the paper feed tray 21a onto the paper feed transport path FR. The printing paper W is laminated, the primary paper supply unit 22b that conveys only the uppermost printing paper W from the paper feeding base 21b onto the paper feeding conveyance path FR, and the printing paper W. Sheet feeding table 21c, a primary sheet feeding unit 22c that conveys only the uppermost printing sheet W from the sheet feeding table 21c onto the sheet feeding conveyance path FR, and a sheet feeding table 21d on which the printing sheets W are stacked. And a primary paper feed section 22d for transporting only the uppermost printing paper W from the paper feed tray 21d onto the paper feed transport path FR.

  In this way, the printing paper W is conveyed from the side paper feeding unit 10 and the internal paper feeding unit 20 to the secondary paper feeding unit 14, and further, the printing paper W is also conveyed from the reversing unit 50 described later.

  Therefore, in front of the secondary paper feeding unit 14 in the transport direction, the transport path of the fed printing paper W and the path through which the paper on which one side is printed are circulated and merged are joined A point exists. Based on this merging point, the path on the paper feed mechanism side is referred to as a paper feed conveyance path FR, and the other path is referred to as a circulation conveyance path CR.

  The printing unit 30 is provided on a paper transport unit 133 that transports the print paper W on the circulation transport path CR, and an upper portion of the paper transport unit 133. C (cyan), M (magenta), Y (yellow), K An inkjet head unit 31 in which a plurality of inkjet heads are arranged in a staggered pattern for each (black) ink color, and a maintenance unit 135 that performs a cleaning process of the inkjet head unit 31 are provided.

  The paper transport unit 133 includes an annular platen belt 132, and the printing paper W fed by the secondary paper feed unit 14 is placed on the platen belt 132 by a suction fan 131 (described later) installed in the platen belt 132. The ink is sucked by the ink and is printed on a line basis by the ink ejected from the inkjet head unit 31 while being conveyed on the conveyance path at a predetermined conveyance speed.

  The printing paper W printed by the printing unit 30 is conveyed on the circulation conveyance path CR in the housing by a conveyance roller or the like disposed on the circulation conveyance path CR. A switching mechanism 43 is provided on the circulation conveyance path CR to switch between guiding the printing paper W conveyed on the circulation conveyance path CR to the paper discharge unit 40 or recirculating it on the circulation conveyance path CR. Yes.

  The switching mechanism 43 switches the printing paper W in order to guide it to one of a paper discharge unit 40 and a reversing unit 50 described later.

  When a predetermined time has elapsed after printing of the printing paper W, it is necessary to remove unnecessary materials such as dry ink on the surface of the inkjet head. Therefore, a maintenance unit 135 for performing the cleaning process of the ink jet head unit 31 is disposed below the paper transport unit 133 for the purpose of removing unnecessary materials. During the cleaning process, the paper transport unit 133 moves in the X1 direction and the maintenance unit 135 moves in the Y1 direction, so that the maintenance unit 135 is attached to the inkjet head unit 31 and the cleaning process is executed.

  The paper discharge unit 40 includes a tray-shaped paper discharge table 41 protruding from the casing of the inkjet printing apparatus 1 and a pair of paper discharge rollers 42 that guide the print paper W to the paper discharge table 41. Then, the printing paper W guided to the paper discharge unit 40 by the switching mechanism 43 is conveyed to the paper discharge table 41 by the paper discharge roller 42, and is stacked on the paper discharge table 41 with the printing surface facing down.

  The reversing unit 50 reverses the printing paper W, and the reversing unit 51 conveys the printing paper W from the circulation conveyance path CR to the reversing table 51 or conveys the printing paper W from the reversing table 51 onto the circulation conveyance path CR. And a roller 52.

  The printing paper W guided to the reversing unit 50 by the switching mechanism 43 is transported from the circulation transport path CR to the reversing table 51 by the reversing roller 52, and is transported from the reversing table 51 to the circulation transport path CR after a predetermined time. Thus, the front and back are reversed with respect to the circulation conveyance path CR. The printing paper W whose front and back are reversed is conveyed toward the printing unit 30 on the circulation conveyance path CR by a plurality of rollers such as a conveyance roller 53 provided on the circulation conveyance path CR.

  FIG. 2 is a diagram schematically showing a maintenance unit 135 provided in the inkjet printing apparatus 1 according to an embodiment of the present invention.

  As shown in FIG. 2, the maintenance unit 135 includes a pan 141 serving as a tray for the leaked ink, a base 142 provided in the pan 141, and head caps 143 a to 143 d provided on the base 142. A waste liquid line 145 that discharges ink from the head caps 143a to 143d to the waste liquid tank, and waste liquid valves 144a to 144d that are provided corresponding to the head caps 143a to 143d and discharge the ink to the waste liquid line 145 are provided. The head caps are provided corresponding to the ink jet heads, respectively, but only the head caps 143a to 143d, which are a part of the head caps, are shown in FIG.

  Then, when the entire maintenance unit 135 is moved in the Y1 direction by a unit driving unit (not shown), the head caps 143a to 143d are respectively attached to the inkjet heads.

  FIG. 3 is a perspective view of the head cap 143a of the maintenance unit 135 provided in the inkjet printing apparatus 1 according to the embodiment of the present invention. Since the head caps 143b to 143d have the same configuration as the head cap 143a, the description thereof is omitted.

  As shown in FIG. 3, the head cap 143a is provided with a nozzle cap portion 152 on a frame 151 so as to be movable up and down. Since the head cap 143a is fixed to the maintenance unit 135, when the maintenance unit 135 is raised in the Y1 direction shown in FIG. 1, the head cap 143a is also raised in the Y1 direction.

  A packing 154 formed of an elastic body such as rubber is provided on the upper portion of the nozzle cap portion 152. When the head cap 143a is raised in the Y1 direction, the packing 154 and the inkjet head of the inkjet head unit 31 are moved. Contact. Thereby, the head cap 143a is attached to the inkjet head.

  A spring 153 is provided on the frame 151 so as to support the nozzle cap portion 152. Then, due to the restoring force of the spring 153, the packing 154 and the inkjet head of the inkjet head unit 31 are in close contact with each other, so that the nozzle is covered with the head cap 143a in a state of being sealed from the outside air.

  Further, a purge pump 136 that supplies air into the inkjet head is provided to pressurize the interior of the inkjet head and discharge ink from the nozzles. The discharge of ink from the inkjet head by the pressure of the purge pump 136 is called a purge operation.

  When the ink is discharged from the inkjet head by this purge operation, the ink is stored inside the head cap 143a, and the nozzle is immersed in the stored ink.

  In addition, an ultrasonic wave generating element 155 that generates ultrasonic waves is provided inside the nozzle cap unit 152, and the ultrasonic wave generating element 155 emits ultrasonic waves while ink is stored in the nozzle cap unit 152. As a result, the inkjet head is ultrasonically cleaned.

  A waste liquid line 145 for discharging ink from the nozzle cap part 152 is connected to the lower part of the nozzle cap part 152, and the waste liquid valve 144a is "opened" to be stored in the nozzle cap part 152. Ink is discharged to the waste liquid tank via the waste liquid line 145.

<Functional Configuration of Inkjet Printing Apparatus 1>
Next, the functional configuration of the inkjet printing apparatus 1 that is Embodiment 1 of the present invention will be described.

  FIG. 4 is a diagram illustrating a functional configuration of the inkjet printing apparatus 1 that is Embodiment 1 of the present invention.

  As shown in FIG. 4, the inkjet printing apparatus 1 includes an external interface unit 71, a unit driving unit 139, a paper transport unit 133, a maintenance unit 135, a printing unit 30, an operation unit 60, and a control unit 70. It has. Among these configurations, the paper transport unit 133, the maintenance unit 135, and the printing unit 30 have been described above, and a description thereof will be omitted.

  The unit driving unit 139 drives the paper transport unit 133 and the maintenance unit 135 based on an instruction from the control unit 70.

  The external interface unit 71 is an interface device for connecting to the terminal 100 via the network 9 and supplies, for example, print data transmitted from the terminal 100 to the control unit 70.

  The operation unit 60 includes a display / input panel (not shown), a start key for starting reading and printing, a stop key for stopping reading and printing, and a numeric keypad for inputting the number of prints (whichever And an operation signal based on a user operation is supplied to the control unit 70.

  The display / input panel of the operation unit 60 includes a pressure-sensitive or electrostatic transparent touch panel disposed on the front surface and a liquid crystal display panel disposed on the back surface of the touch panel for displaying various display screens (none of which are shown). ). The user touches the surface of the touch panel directly with his / her finger while looking at the display screen of the liquid crystal display panel, and sets a standby time for automatically starting the cleaning process and a button for executing the cleaning process. In order to prevent the ink jet head from drying, the paper transport unit 133 is automatically moved to the standby position, and the maintenance position 135 is set to move to the maintenance position. Various buttons such as a setting button for setting time can be pressed.

  The control unit 70 performs central control of the inkjet printing apparatus 1 and controls the side paper feed unit 10, the internal paper feed unit 20, the printing unit 30, the paper discharge unit 40, and the reversing unit 50. Moreover, the control part 70 is provided with the drive control part 70a and the washing | cleaning control part 70b on the function.

  When executing the cleaning process, the drive control unit 70a moves the paper transport unit 133 to the standby position and moves the maintenance unit 135 to the maintenance position when the maintenance preparation is not completed. When the cleaning process is completed, the drive control unit 70a moves the maintenance unit 135 to the standby position and moves the paper transport unit 133 to the printing position.

  Further, when the elapsed time from the time when the ink is finally discharged from the inkjet head exceeds the standby position movement setting time, the drive control unit 70a moves the paper transport unit 133 to the standby position and moves the maintenance unit 135. Move to the maintenance position. Here, the discharge of ink includes discharge by applying a predetermined voltage to a piezoelectric element provided in the inkjet head, and discharge of ink by a purge operation of the purge pump 136.

  The cleaning control unit 70 b causes the ultrasonic wave generation element 155 to generate ultrasonic waves while discharging ink from the nozzles to the inkjet head by a purge operation by the purge pump 136.

<Operation of Inkjet Printing Apparatus 1>
Next, the operation of the inkjet printing apparatus 1 according to one embodiment of the present invention will be described.

  FIG. 5 is a flowchart showing the processing procedure of the cleaning process in the inkjet printing apparatus 1 according to the embodiment of the present invention.

  As shown in FIG. 5, the control unit 70 determines whether or not a cleaning process has been requested (step S101). Specifically, it is determined whether or not an operation signal for requesting execution of the cleaning process is supplied from the operation unit 60.

  When it is determined in step S101 that the cleaning process is not requested (NO), the control unit 70 determines whether or not a predetermined time has elapsed since the last ink discharge (step S103). Specifically, the control unit 70 determines whether or not the elapsed time from the time when the ink is finally discharged from the inkjet head has exceeded the standby setting time set in advance from the operation unit 60 by the user.

  Here, an appropriate value such as “2h” is set in advance as the standby setting time so that the ink does not dry and solidify when the nozzles of the inkjet head come into contact with the outside air.

  If it is determined in step S101 that a cleaning process has been requested (in the case of YES), or if it is determined in step S103 that a predetermined time has elapsed since the last ink discharge (in the case of YES), the control unit The drive control unit 70a of 70 determines whether or not the maintenance preparation is completed (step S104). Specifically, the drive control unit 70a determines whether or not the paper transport unit 133 is in the standby position and the maintenance unit 135 is in the maintenance position.

  If it is determined in step S104 that the maintenance preparation has not been completed (NO), the drive control unit 70a of the control unit 70 moves the paper transport unit 133 to the standby position (step S105). Specifically, the drive control unit 70a controls the unit drive unit 139 so as to move the paper transport unit 133 in the X1 direction shown in FIG.

  Next, the drive control unit 70a of the control unit 70 moves the maintenance unit 135 to the maintenance position (step S107). Specifically, the drive control unit 70a controls the unit drive unit 139 so as to move the maintenance unit 135 in the Y1 direction shown in FIG. As a result, the head cap 143 a is attached to the inkjet head of the inkjet head unit 31.

  Then, the cleaning control unit 70b of the control unit 70 performs a purge operation (step S109). Specifically, the cleaning control unit 70b activates the purge pump 136 to supply air into the inkjet head. Thereby, the inside of the inkjet head is pressurized, and ink is discharged from the nozzles of the inkjet head. When the ink is discharged from the inkjet head by this purge operation, the ink is stored inside the head cap 143a, and the nozzle is immersed in the stored ink.

  Next, the cleaning control unit 70b causes the ultrasonic wave generating element 155 to generate ultrasonic waves (step S111). Specifically, the cleaning control unit 70b applies a predetermined voltage to the ultrasonic wave generating element 155 from a power supply system (not shown), thereby causing the ultrasonic wave generating element 155 to generate ultrasonic waves. As a result, the nozzles of the inkjet head are ultrasonically cleaned, and the ultrasonic waves propagate through the waste liquid line 145 from the head cap 143a to the waste liquid valve 144a, thereby cleaning the waste liquid line 145.

  Then, the cleaning control unit 70b determines whether or not the cleaning set time has been reached (step S113). Here, the cleaning setting time is a time that is set as a time sufficient for cleaning the nozzles of the inkjet head, and may be set as a fixed value such as 10 (seconds), or may be set last from the inkjet head. It may be set according to the elapsed time from the time when ink is discharged.

  When it is determined in step S113 that the cleaning set time has been reached (in the case of YES), the cleaning control unit 70b stops the generation of ultrasonic waves by the ultrasonic generating element 155 (step S115) and stops the purge operation. (Step S117).

  Next, the drive control unit 70a of the control unit 70 opens the waste liquid valve 144a to discharge the ink stored in the nozzle cap unit 152 to the waste liquid tank (step S119).

  Next, the drive control unit 70a of the control unit 70 moves the maintenance unit 135 to the standby position (step S121). Specifically, the drive control unit 70a controls the unit drive unit 139 to move the maintenance unit 135 in the Y2 direction shown in FIG.

  Then, the drive control unit 70a of the control unit 70 moves the paper transport unit 133 to the printing position (step S123). Specifically, the drive control unit 70a controls the unit drive unit 139 to move the paper transport unit 133 in the X2 direction shown in FIG.

  As described above, according to the inkjet printing apparatus 1 according to an embodiment of the present invention, the nozzles of the inkjet head unit 31 are covered with the nozzles of the inkjet head sealed from the outside air, and the ink is stored so as to immerse the nozzles. Since the cap 143a and the ultrasonic wave generating element 155 provided on the head cap 143a for generating ultrasonic waves are provided, when the ink is not discharged for a long time, the head cap 143a is put on standby with the ink jet head mounted. it can. Thereby, when performing the cleaning process, it is not necessary to move the maintenance unit 135, so that the cleaning process can be performed promptly and efficiently.

  Further, for example, in the ink jet printing apparatus described in Patent Document 2, a thin layer of viscous fluid is formed between the ultrasonic transducer and the orifice plate so as to be in contact therewith, and the ultrasonic transducer generates ultrasonic waves. The cleaning process could not be executed in parallel with the process. On the other hand, according to the inkjet printing apparatus 1 according to an embodiment of the present invention, the head cap 143a covers the nozzles of the inkjet head in a sealed state from the outside air, and stores the ink so as to immerse the nozzles. Ultrasonic waves can be generated in the ultrasonic wave generating element 155 while discharging ink from the nozzles. As a result, the nozzle cleaning process can be executed more efficiently.

  In the embodiment of the present invention, the ultrasonic wave is generated by the ultrasonic wave generating element 155 while performing the purge operation. However, the present invention is not limited to this, and only ultrasonic cleaning by the ultrasonic wave generating element 155 is performed. Alternatively, the purge operation and the ultrasonic cleaning by the ultrasonic wave generating element 155 are performed in parallel while performing the flushing operation of ejecting ink from the nozzle by applying a voltage to the piezoelectric element provided in the inkjet head. You may make it perform.

  Further, in the embodiment of the present invention, the ultrasonic generating element 155 that generates ultrasonic waves is provided inside the nozzle cap portion 152. However, the present invention is not limited thereto, and ultrasonic waves are generated outside the nozzle cap portion 152. The element 155 may be provided. That is, the ultrasonic wave generating element 155 may be provided at a location where the ultrasonic wave propagates to the ink stored in the nozzle cap portion 152.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printing apparatus 10 ... Side paper feed part 20 ... Internal paper feed part 30 ... Printing part 31 ... Inkjet head unit 40 ... Paper discharge part 50 ... Inversion part 60 ... Operation part 70 ... Control part 70a ... Drive control part 70b ... Cleaning control unit 133 ... Paper transport unit 135 ... Maintenance unit 136 ... Purge pump 139 ... Unit driving unit 143a to 143d ... Head caps 144a to 144d ... Waste liquid valve 145 ... Waste liquid line (ink discharge path)

Claims (4)

An inkjet head that ejects ink from a nozzle to a print medium;
A head cap that is detachably provided on the inkjet head and covers the nozzle in a sealed state from the outside air when attached;
An ultrasonic wave generating means provided on the head cap for generating ultrasonic waves;
Control means for attaching the head cap to the inkjet head and storing the ink in the head cap so as to immerse the nozzle;
An ink jet printing apparatus comprising: The control means includes
The head cap is attached to the ink jet head when an elapsed time from the time when ink is finally discharged from the nozzle exceeds a preset standby movement setting time. Inkjet printing device. The control means includes
The inkjet printing apparatus according to claim 1, wherein the ultrasonic wave is generated by the ultrasonic wave generation unit while discharging the ink from the nozzle to the inkjet head. A waste ink tank for storing the ink;
An ink discharge path for connecting the waste ink tank and the head cap, and discharging the ink stored in the head cap to the waste ink tank;
The inkjet printing apparatus according to claim 1, further comprising:

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