JP2012179811A - Cleaning device and cleaning method of liquid ejection head, and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device and a cleaning method of a liquid ejection head for removing foreign matters adhering to the surface with a liquid discharge port of the liquid ejection head formed thereon, while reliably preventing reduction in liquid-repellent effect of the surface with the liquid discharge port formed thereon, and an image forming system including the liquid ejection head and the cleaning device.SOLUTION: The cleaning device 100 includes a cleaning roller 102 having an outer peripheral surface which is close to and faces the surface of the nozzle plate of an ink ejection head 33, and an ink feed means 104 discharging ink in the ink ejection head 33. Foreign matters adhering to the nozzle plate are removed by discharging ink out of the ink ejection head 33 into a gap between the outer peripheral surface of the cleaning roller 102 and the surface of the nozzle plate, and rotating the cleaning roller 102.

Description

  The present invention relates to a liquid ejection head cleaning device, a cleaning method, and an image forming apparatus, and more particularly, to a liquid ejection head cleaning device and a cleaning device in which a liquid ejection port for ejecting liquid is formed on one surface thereof. The present invention also relates to a method and an image forming apparatus that forms an image on a recording medium using the liquid discharge head and cleans the liquid discharge head using the cleaning device.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image by ejecting liquid (for example, ink) from a liquid ejection head onto a recording medium (for example, paper) is known.

  In this image forming apparatus, if a foreign matter such as ink, dust, dust or paper dust adheres to the surface (nozzle surface) where the liquid ejection port (nozzle port) of the liquid ejection head is formed, ink ejection failure will occur. Inconveniences such as disturbance in the ink ejection direction occur.

  Therefore, in order to prevent the occurrence of such a problem, for example, in the image forming apparatuses described in Patent Documents 1 and 2, the foreign matter adhering to the nozzle surface is removed by wiping with a wiper.

  However, in the image forming apparatuses described in Patent Documents 1 and 2, since the nozzle surface is rubbed with the wiper, the liquid repellent film formed on the nozzle surface is worn. As a result, the liquid-repellent effect on the nozzle surface is reduced, and liquid discharge failure from the liquid discharge port occurs.

  The present invention has been made under such circumstances, and a first object of the present invention is to ensure that the liquid discharge port has the liquid discharge port while reliably suppressing a reduction in the liquid repellency of the surface on which the liquid discharge port of the liquid discharge head is formed. An object of the present invention is to provide a cleaning device and a cleaning method for the liquid discharge head, which can remove foreign matter adhering to the formed surface.

  A second object of the present invention is to provide an image forming apparatus capable of reliably suppressing a reduction in image quality.

  According to a first aspect of the present invention, there is provided a liquid discharge head cleaning device in which a liquid discharge port for discharging a liquid is formed on one side of the liquid discharge port. And a liquid supply means for supplying the liquid in the liquid discharge head to a gap between the one side surface and the opposite surface facing the one side surface via the liquid discharge port. And a first moving means for relatively moving the one side surface and the facing surface in a direction parallel to the one side surface in a state where the liquid is supplied to the gap by the liquid supply means. This is a cleaning device. Here, in this specification, “parallel” includes not only strictly parallel but also substantially parallel.

  According to this, it is possible to remove the foreign matter adhering to the surface on which the liquid ejection port is formed while reliably suppressing the reduction in the liquid repellency effect on the surface on which the liquid ejection port of the liquid ejection head is formed.

  According to a second aspect of the present invention, there is provided a liquid discharge head cleaning method in which a liquid discharge port for discharging a liquid is formed on one surface thereof, and the liquid in the liquid discharge head is Supplying the gap between the one-side surface and the opposite surface facing the one-side surface via the liquid discharge port; and the one-side surface in a state where the liquid is supplied to the gap. And a relative movement of the facing surface in a direction parallel to the surface on the one side.

  From a third viewpoint, the present invention is an image forming apparatus in which a liquid discharge port for discharging a liquid forms an image on a recording medium using a liquid discharge head formed on one surface thereof. An image forming apparatus comprising the cleaning device of the invention.

1 is a side view showing an internal configuration of an image forming apparatus according to a first embodiment. 2A and 2B are side views (part 1 and part 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus. FIG. 4 is a plan view of four ink discharge heads of the image recording unit as viewed from below. 4A to 4E are views (No. 1 to No. 5) for explaining the cleaning operation of the ink discharge head. It is a flowchart which shows the flow of a process of the main controller at the time of cleaning of an ink discharge head. FIG. 3 is a block diagram illustrating a control configuration of the image forming apparatus. FIGS. 7A and 7B are side views (part 1 and part 2) schematically illustrating an image recording unit and a cleaning device included in the image forming apparatus according to the second embodiment. FIGS. 8A to 8F are views (Nos. 1 to 6) for explaining the cleaning operation of the ink discharge head according to the second embodiment. 10 is a flowchart illustrating a flow of processing of the main control device during cleaning of the ink ejection head according to the second embodiment. FIGS. 10A and 10B are side views (part 1 and part 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus according to the third embodiment. FIGS. 11A to 11E are views (No. 1 to No. 5) for explaining the cleaning operation of the ink discharge head according to the third embodiment. 12A and 12B are side views (No. 1 and No. 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the fourth embodiment. 10 is a flowchart illustrating a processing flow of a main control device during cleaning of an ink discharge head according to a fourth embodiment. FIG. 10 is a block diagram illustrating a control configuration of an image forming apparatus according to a fourth embodiment. It is the top view which looked at the four ink discharge heads and the cleaning roller of 5th Embodiment from the downward direction. FIGS. 16A to 16C are side views (No. 1 to No. 3) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the fifth embodiment. FIGS. 17A and 17B are side views (No. 1 and No. 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the first modification. 18A and 18B are side views (part 1 and part 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the second modification. FIGS. 19A to 19C are side views (No. 1 to No. 3) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the third modification. 20A and 20B are side views (part 1 and part 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the fourth modification. FIGS. 21A and 21B are side views (No. 1 and No. 2) schematically showing an image recording unit and a cleaning device included in the image forming apparatus of the fifth modified example.

  A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side view showing the internal configuration of the image forming apparatus 10 according to the first embodiment. Hereinafter, the width direction (left-right direction) of the image forming apparatus 10 will be described as the X-axis direction, the depth direction (front-rear direction) as the Y-axis direction, and the direction orthogonal to the X-axis and Y-axis directions as the Z-axis direction (vertical direction). .

  The image forming apparatus 10 is a color printer used as an output device such as a personal computer (personal computer). As shown in FIG. 1, the image forming apparatus 10 includes a main body case 12, an image recording unit 14 housed in the main body case 12, a paper transport system 15, a cleaning device 100, and a main control device 110 (see FIG. 6). )including.

  An opening (not shown) is formed on the side surface on the −Y side of the lower portion of the main body case 12, and a plurality of sheets of recording media (from the front side (−Y side in FIG. 1)) (as shown in FIG. 1) A sheet feeding cassette (or a sheet feeding tray) 16 on which sheets (P) can be stacked can be detachably (removably inserted). In addition, a manual feed tray 18 for manually feeding the paper P is provided on the upper half of the front surface of the main body case 12 so as to be able to swing up and down.

  In this image forming apparatus 10, the paper P fed from the paper feed cassette 16 or the manual feed tray 18 is taken in by the paper transport system 15 and a required image is recorded by the image recording unit 14, and then the rear surface ( Paper is discharged onto a paper discharge tray 20 mounted at a predetermined angle on the back side.

  As shown in FIG. 2A, the image recording unit 14 includes a head unit 34 including a plurality of (for example, four) ink ejection heads 33 and a plurality of inks that individually supply ink to each of the four ink ejection heads 33. And a cartridge unit 41 including (for example, four) ink cartridges 36.

  As the ink discharge head 33, a piezoelectric type that pressurizes ink through a vibration plate that forms a liquid chamber wall surface with an electromechanical conversion element such as a piezoelectric element, or a bubble type that pressurizes ink by generating bubbles with a heating resistor. Alternatively, an electrostatic type that pressurizes ink by displacing the diaphragm with an electrostatic force between the diaphragm that forms the wall surface of the ink flow path and the electrode facing the diaphragm can be used. In the image forming apparatus 10, although not shown, a piezo-type ink discharge head is employed.

  As shown in FIG. 2A, the four ink discharge heads 33 are arranged from the −Y side to the + Y side along the outer periphery of a virtual cylinder having a predetermined radius R with the X axis direction as the axial direction. The most -Y side ink ejection head 33 ejects yellow (Y) ink, the second ink ejection head 33 counts from the -Y side, and cyan (C) ink counts from the -Y side. The third ink ejection head 33 ejects magenta (M) ink, and the fourth ink ejection head 33 from the −Y side ejects black (B) ink. Therefore, hereinafter, the four ink discharge heads 33 are also referred to as ink discharge heads 33Y, 33C, 33M, and 33B in order from the −Y side. The four ink discharge heads 33Y, 33C, 33M, and 33B are individually controlled for discharge drive by the main controller 110 (see FIG. 6).

  FIG. 3 is a plan view showing the head unit 34 as viewed from below. As shown in FIG. 3, each of the four ink discharge heads 33 includes a base member 33a having the X-axis direction as a longitudinal direction, and a plurality of (for example, six) head portions 33b fixed to the base member 33a. .

  Each of the four base members 33a has a length in the longitudinal direction that is slightly longer than a width in the width direction of the paper P (for example, A3 size paper).

  As shown in FIG. 4A, each of the six head portions 33b of each ink discharge head 33 has a liquid chamber member 35 in which a liquid chamber 35a for containing ink is formed, and the liquid chamber member 35. It includes a nozzle plate 37 fitted and fixed to an opening 35b formed in the bottom wall. 4A to 4E representatively show only the head portion 33b of the ink discharge head 33Y.

  In each ink discharge head 33, the base member 33a is not supported by the base member 33a in a state where the surface of the nozzle plate 37 substantially coincides with a part of the tangential plane contacting the outer peripheral surface of the virtual cylinder (see FIG. 2A). The body case 12 supports the member. Each ink discharge head 33 performs a printing operation at the position shown in FIG.

  Each of the six nozzle plates 37 protrudes from the outer wall surface of the bottom wall of the liquid chamber member 35 to the outside of the liquid chamber 35a.

  As the nozzle plate 37, for example, a plate member made of a conductive material such as SUS alloy or nickel and having a liquid repellent film formed on the surface thereof is used.

  As shown in FIGS. 3 and 4A, each nozzle plate 37 has a longitudinal direction in the X-axis direction. Each nozzle plate 37 is formed with a plurality (a large number) of nozzle ports 37 a (liquid discharge ports) penetrating in the Z-axis direction, that is, in a direction intersecting the nozzle plate 37. As shown in FIG. 3, a large number of nozzle openings 37 a are arranged in a staggered manner in almost the entire area in the longitudinal direction (X-axis direction) of the nozzle plate 37, that is, a large number of nozzle ports 37 a arranged in almost the entire area of the nozzle plate 37 in the X-axis direction. A plurality of (for example, two) nozzle port arrays each composed of the nozzle ports 37a are arranged in the Y-axis direction so as to overlap (overlap) in the X-axis direction.

  As described above, the liquid chamber 35a is opened to the outside through the large number of nozzle openings 37a. In each ink discharge head 33, the ink in the liquid chamber 35a is brought into a positive pressure state, whereby the liquid chamber 35a. The ink contained in the ink is discharged (or discharged) downward through a number of nozzle openings 37a.

  Further, as shown in FIG. 3, the six nozzle plates 37 of each ink discharge head 33 are staggered over substantially the entire longitudinal direction (X-axis direction) of the base member 33a, that is, the X-axis direction of the base member 33a. A plurality of (for example, two) nozzle plate rows each composed of a plurality of (for example, three) nozzle plates 37 arranged side by side are arranged in the Y-axis direction so as to overlap (overlap) in the X-axis direction.

  That is, each ink discharge head 33 constitutes a so-called full-line type ink discharge head, and can discharge ink over the entire width direction of, for example, A3 size paper P.

  As shown in FIG. 2A, the four ink cartridges 36 are connected to the corresponding ink discharge heads 33Y, 33C, 33M, and 33B via pipes 39, respectively. Y, C, M, and B inks are supplied to 33Y, 33C, 33M, and 33B. A check valve (not shown) is provided at an intermediate portion of the pipe 39 to prevent the backflow of ink from each ink discharge head 33 to the corresponding ink cartridge 36.

  Each ink cartridge 36 has an air opening (not shown) communicating with the atmosphere formed in the upper part thereof, and a supply port (not shown) for supplying ink to the ink discharge head 33 is formed in the lower part thereof and filled with ink. An ink chamber (not shown) containing a porous body is formed inside. In each ink cartridge 36, the ink supplied to the ink discharge head 33 is maintained at a slight negative pressure by the capillary force of the porous body.

  Each ink cartridge 36 is provided detachably (replaceable) in the main body case 12. Hereinafter, the ink cartridges 36 corresponding to the ink discharge heads 33Y, 33C, 33M, and 33B are also referred to as ink cartridges 36Y, 36C, 36M, and 36B.

  As shown in FIG. 1, the paper transport system 15 includes a paper feed roller 46, a friction pad 48, a guide member 50, a transport roller 52, a transport roller 54, a leading end roller 56, a printing receiving member 58, a transport roller 60, a spur. 62, a discharge roller 64, a spur 66, guide members 68 and 70, and the like.

  The paper feed roller 46 and the friction pad 48 have a role of separating the paper P one by one from the paper feed cassette 16 and feeding it into the transport system. The guide member 50 guides the supplied paper P toward the transport roller 52 at the next stage. A conveying roller 54 and a leading end roller 56 are disposed above the conveying roller 52, and these rollers are pressed against the outer peripheral surface of the conveying roller 52. Therefore, when the conveying roller 52 rotates in the clockwise direction in FIG. 1, the sheet P guided by the guide member 50 is inverted and the printing receiving member provided below the head unit 34 on the downstream side thereof. Sent to 58. The printing receiving member 58 is a paper guide member that guides the paper P sent out from the transport roller 52 on the lower side of the head unit 34.

  The leading end roller 56 has a structure in which the position can be finely adjusted, and defines the feeding angle of the paper P from the transport roller 52 according to the position. The transport roller 52 is rotationally driven by a drive system including a motor, a gear and the like (not shown).

  The guide members 68 and 70 are arranged to face the downstream side in the transport direction of the printing receiving member 58, and form a paper discharge path downstream of the printing receiving member 58. A conveyance roller 60 and a spur 62 are disposed in the middle of the paper discharge path, and are rotationally driven via a sheet P fed from the conveyance roller 52 and guided through the printing receiving member 58 and the guide members 68 and 70. The paper P is sent out in the paper discharge direction.

  The paper discharge roller 64 and the spur 66 are disposed at the most downstream position of the paper discharge path formed by the guide members 68 and 70, and rotate via the paper P guided through the guide members 68 and 70. Driven, the paper P is discharged to the paper discharge tray 20.

  As shown in FIG. 2A, the cleaning device 100 includes a cleaning roller 102, a plurality (for example, four) of ink feeding means 104, a voltage applying means 107 (see FIG. 6), and the like.

  The cleaning roller 102 has a cylindrical outer shape whose axial direction is the X-axis direction and whose radius r is slightly smaller than the radius R of the virtual cylinder. The dimension of the cleaning roller 102 in the axial direction is set to be slightly longer than the dimension of each ink discharge head 33 in the longitudinal direction (see FIG. 3).

  Although not shown, the cleaning roller 102 has a roller member made of a metal columnar member, a resin dispersed with, for example, conductive carbon wound around the outer peripheral surface of the roller member, and a conductive roller 102. And a member made of rubber or the like. The outer peripheral surface of the cleaning roller 102 has lower liquid repellency, that is, higher wettability than the surface of the nozzle plate 37 on which the liquid repellent film is formed.

  The cleaning roller 102 is rotationally driven around its axis by a roller driving unit 111 (see FIG. 6) including a motor or the like, for example. The roller driving unit 111 is controlled by the main controller 110 (see FIG. 6).

  In the vicinity of the outer peripheral surface of the cleaning roller 102, a blade 106 as ink scraping means is disposed.

  Further, as will be described later in detail, the cleaning roller 102 is provided vertically below the head unit 34 together with the roller driving unit 111 and the blade 106.

  Here, as shown in FIGS. 1 and 2A, the printing receiving member 58 is located immediately below the head unit 34 and above the cleaning roller 102. The printing receiving member 58 is formed of a flat plate-like member whose one end is supported so as to be rotatable about an axis extending in the X-axis direction. For example, the printing receiving member driving unit 108 including a solenoid (not shown) (FIG. 6). Can be rotated between a printing receiving position (see FIGS. 1 and 2A) parallel to the XY plane and a retracted position (see FIG. 2B) parallel to the XZ plane, for example. It has become. The printing receiving member driving unit 108 is controlled by the main controller 110 (see FIG. 6).

  The cleaning roller 102, the roller driving unit 111, and the blade 106 are, for example, a slide mechanism including a rack and pinion (not shown), and an elevating device 112 (see FIG. 6) including, for example, a servo motor that operates the slide mechanism. When the printing receiving member 58 is located at the retracted position, a standby position below the printing receiving member 58 (see FIG. 2A) and a cleaning position (see FIG. 2) that is close to and faces the four ink discharge heads 33. 2 (see (B)).

  More specifically, the cleaning roller 102 is moved up and down between the standby position and the cleaning position in a state where the Y position of the axis g is substantially coincident with the Y position of the axis G of the virtual cylinder. The elevating device 112 is controlled by the main control device 110 (see FIG. 6).

  The cleaning position of the cleaning roller 102 is a position where the clearance between the surface of the nozzle plate 37 of each ink discharge head 33 and the outer peripheral surface of the cleaning roller 102 is an appropriate value according to the characteristics of the ink used for recording. Is set. In this embodiment, water-based ink is used as an example, and the clearance is set to an appropriate value according to the characteristics of the water-based ink, for example, about 10 μm to 500 μm. The appropriate value corresponding to the ink characteristics is a value suitable for realizing a cleaning operation of each ink discharge head 33 described later.

  As shown in FIG. 2A, the four ink feeding units 104 are provided corresponding to the four ink ejection heads 33, and are connected to the liquid chambers 35a of the corresponding ink ejection heads 33 via the pipes 114. The ink cartridges 36 are connected to the corresponding ink cartridges 36 via pipes 116. Hereinafter, the ink feeding units 104 corresponding to the four ink ejection heads 33Y, 33C, 33M, and 33B are also referred to as ink feeding units 104Y, 104C, 104M, and 104B.

  As the ink feeding means 104, for example, a tubing pump, a piston pump or the like that feeds ink in the ink cartridge 36 to the ink discharge head 33 is employed. Each ink feeding means 104 is driven and controlled by the main controller 110 (see FIG. 6).

  The voltage application unit 107 includes a power source, an electric circuit, and the like (not shown). When the cleaning roller 102 is located at the cleaning position, the surface of the nozzle plate 37 of each ink discharge head 33 is used as a cathode electrode, and the cleaning roller A voltage can be applied between these two electrodes by using the outer peripheral surface of 102 as an anode electrode. The voltage application means 107 is controlled by the main controller 110 (see FIG. 6).

  Here, when the ink in the ink cartridge 36 is fed into the ink ejection head 33 by the ink feeding means 104 when the cleaning roller 102 is positioned at the cleaning position, the inside of the liquid chamber 35 a of the ink ejection head 33 is correctly aligned. Ink is discharged from the nozzle opening 37 a to the gap between the surface of the nozzle plate 37 and the outer peripheral surface of the cleaning roller 102. Then, the discharged ink is nipped (bridged) between the nozzle plate 37 and the cleaning roller 102.

In this state, when a voltage exceeding 1.23 V, which is the theoretical decomposition voltage of water, is applied between the nozzle plate 37 and the cleaning roller 102, the following electrode reaction occurs.
Nozzle plate surface (cathode electrode): 4H ₂ O + 4e ⁻ → 2H ₂ + 4OH ⁻ (1)
Outer peripheral surface of cleaning roller (anode electrode): 2H ₂ O → 4H + O ₂ + 4e ⁻ (2)

  In addition to the above reaction formulas (1) and (2), an oxidation-reduction reaction of the electrode itself occurs simultaneously. The specific reaction depends on the electrode material, the electrode potential, and the pH of the ink, but can be easily analogized by referring to, for example, a state diagram (Pour baix diagram) showing the relationship between the potential and the pH. it can.

  According to the reaction formula (1), hydroxide ions are generated on the surface side of the nozzle plate 37 (cathode electrode), and as a result, alkalinity is exhibited. When the ink coloring material is an anionic pigment, it exhibits high dispersibility under alkaline conditions, and the ink deposit attached to the nozzle surface is easily dissolved. Further, according to the reaction formula (2), hydrogen ions are generated on the outer peripheral surface (anode electrode) side of the cleaning roller 102, and as a result, it shows acidity. When the ink coloring material is an anionic pigment, the positive charge of hydrogen ions and the negative charge of the anionic pigment cancel each other, and electrostatic repulsion is reduced, causing phenomena such as aggregation, thickening, and solidification of the outer periphery of the cleaning roller 102. It occurs near the surface, especially at the electrode interface. When the ink pigment is concentrated in the vicinity of the outer peripheral surface of the cleaning roller 102, the ink concentration interposed between the two electrodes is lowered, so that dissolution of the ink adhering matter adhering to the surface of the nozzle plate 37 is promoted. If the ink is a resistor with a small amount of electrolyte component, a potential gradient is formed, so that an electrophoretic effect of an anionic pigment can also be expected.

  In the image forming apparatus 10 of the present embodiment, ink is ejected onto the stopped paper P by individually driving the four ink ejection heads 33 constituting the head unit 34 in accordance with image signals from a personal computer or the like. To record. Upon receiving a recording end signal or a signal that the trailing edge of the paper P reaches the recording area, the recording operation (printing operation) is terminated and the paper P is discharged. In the image forming apparatus 10, such a recording operation can be continuously performed on a plurality of sheets P.

  Here, during the recording operation or standby, foreign matters such as ink deposits, dust, dust, paper dust, and the like due to ink mist adhere to the nozzle plate 37 of each ink discharge head 33. In particular, if such foreign matter adheres to the vicinity of the nozzle opening 37a of the nozzle plate 37, deviation (disturbance) in the ink ejection direction, ink ejection failure, and the like occur, which are recorded on the paper P. Image quality deteriorates.

  Therefore, main controller 110 determines that the time between the recording operations, that is, the non-printing time is equal to or longer than a predetermined time (for example, several minutes) based on the timing information from timer 113 (see FIG. 6). Then, the four ink discharge heads 33 are cleaned using the cleaning device 100. Note that the time count (timekeeping) by the timer 113 is started, for example, when the recording operation by one print job is completed.

  Hereinafter, a method for cleaning the four ink discharge heads 33 will be described based on the flowchart of FIG. 5 showing the flow of processing of the main controller 110.

  During the recording operation or standby, the printing receiving member 58 is positioned at the printing receiving position, and the cleaning roller 102 is positioned at the standby position (see FIG. 2A).

  First, the main controller 110 rotates the printing receiving member 58 from the printing receiving position to the retracted position via the printing receiving member driving unit 108 (step S2).

  Subsequent to step S2, main controller 110 moves cleaning roller 102 from the standby position to the cleaning position via lifting device 112 (step S3). At this time, the surface of the nozzle plate 37 of each ink discharge head 33 and the outer peripheral surface of the cleaning roller 102 are closely opposed to each other (see FIGS. 2B and 4A).

  Here, as shown in FIG. 4A, it is assumed that the foreign matter D as described above is attached to the surface of the nozzle plate 37 of each ink discharge head 33.

  After step S3, the main controller 110 discharges a predetermined amount of ink from each ink ejection head 33 via the four ink feeding means 104 (step S4). At this time, the ink discharged through the nozzle opening 37a becomes a film sandwiched between the nozzle plate 37 and the cleaning roller 102 (see FIG. 4B). The foreign matter D adhering to the nozzle plate 37 is taken into this film-like ink (ink film M). When the ink is discharged, air bubbles in the liquid chambers 35a and the nozzle openings 37a of each ink discharge head 33, dried and thickened ink attached to the surface defining the nozzle openings 37a, and the like are also discharged.

  Subsequent to step S4, main controller 110 applies a voltage between each nozzle plate 37 and cleaning roller 102 via voltage applying means 107 (step S5). At this time, as described above, of the foreign matter D, in particular, the ink adhering matter adhering to the nozzle plate 37 is promoted to dissolve in the ink film M, so that the ink adhering matter is more reliably contained in the ink film M. It is captured.

  Subsequent to step S5, main controller 110 drives cleaning roller 102 to rotate in the direction of arrow Q (see FIG. 2B) via roller drive unit 111 (step S6). At this time, the ink film M and the foreign matter D sandwiched between the surface of the nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 are pulled by the cleaning roller 102 having higher wettability than the surface of the nozzle plate 37, and the nozzle plate. Nozzle that moves in the direction of arrow Q along the surface of 37 (see FIG. 4C) and has higher liquid repellency than the outer peripheral surface of the cleaning roller 102 without being divided by the surface tension and viscosity of the ink film M It is peeled off from the surface of the plate 37 and transferred onto the outer peripheral surface of the cleaning roller 102 (see FIG. 4D). In this way, the foreign matter D adhering to the surface of the nozzle plate 37 is removed. When the ink film M leaves the gap between the nozzle plate 37 and the cleaning roller 102, the ink film M becomes substantially hemispherical due to surface tension and adheres to the outer peripheral surface of the cleaning roller 102 (see FIG. 4E). ). The substantially hemispherical ink is scraped off by the blade 106 as the cleaning roller 102 rotates, and is stored in, for example, a waste ink receiver (not shown) provided below the blade 106.

  Subsequent to step S6, the main controller 110 stops the rotational driving of the cleaning roller 102 via the roller driving unit 111 (step S7), and then the nozzle plate 37 and the cleaning roller 102 via the voltage applying unit 107. The voltage application between the two is stopped (step S8). Note that the order of step S7 and step S8 may be reversed.

  After step S8, main controller 110 moves cleaning roller 102 from the cleaning position to the standby position via lifting device 112 as shown in FIG. 4E (step S9). After moving the printing receiving member 58 from the retracted position to the printing receiving position via the receiving member driving unit 108 (step S10), the flow is ended.

  After step S10 is completed, the timer 113 is reset, and the time count (clocking) by the timer 113 is started from the point when the recording operation by the next print job is completed.

  As described above, in the image forming apparatus 10, when the recording operation by the next print job is not performed within a predetermined time (for example, several minutes) after the recording operation by one print job is completed, The ink discharge head 33 is cleaned.

  According to the image forming apparatus 10 described above, the surface of the nozzle plate 37 of each ink discharge head 33 and the outer peripheral surface of the cleaning roller 102 having higher wettability than the surface are brought close to each other, After the ink is discharged into a minute gap between the surface of the nozzle plate 37 and the outer peripheral surface of the cleaning roller 102, the cleaning roller 102 is driven to rotate.

  Therefore, the foreign matter D adhering to the surface of each nozzle plate 37 is taken into the ink film M sandwiched between the surface of each nozzle plate 37 and the outer peripheral surface of the cleaning roller 102, and the ink film It is removed by being transferred onto the outer peripheral surface of the cleaning roller 102 together with M.

  That is, since the cleaning device 100 mechanically cleans the surface of each nozzle plate 37 in a non-contact manner, the wear of the liquid repellent film formed on the surface of each nozzle plate 37, that is, the reduction of the liquid repellent effect is reliably suppressed. Is done. As a result, the life of the liquid-repellent film, that is, the life of each ink discharge head can be greatly extended compared to the conventional case where, for example, the nozzle plate is rubbed and scraped off with a rubber wiper or the like. As a result, the product life of the image forming apparatus can be greatly extended.

  As described above, since the wear of the liquid repellent film (reduction of the liquid repellent effect) is surely suppressed, the ink ejected from each nozzle port 37a is reliably repelled by the nozzle plate 37, and as a result, ink ejection failure occurs. Is prevented.

  Even if the surface of each nozzle plate 37 is repeatedly cleaned, the liquid repellency effect is reliably maintained, so that the surface of each nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 are held between each cleaning. The formed ink film M and the foreign matter D taken into the ink film M can be reliably (constantly) delivered to the cleaning roller 102.

  Since the recording ink is used for cleaning, the configuration can be simplified and the increase in cost can be suppressed as compared with, for example, the case of using another liquid (the liquid, a tank for storing the liquid are separately required). Can do.

  Further, when ink is discharged from each ink discharge head 33, bubbles in the liquid chambers 35a and nozzle openings 37a of each ink discharge head 33, dried and thickened ink attached to the surface defining the nozzle openings 37a, etc. Are also discharged. That is, in the present embodiment, the ink discharge head 33 can be cleaned in a part of the cleaning process of the nozzle plate 37 of each ink discharge head 33.

  Each of the four ink discharge heads 33 is arranged so that the outer peripheral surface of the nozzle plate 37 is along the outer peripheral surface of the cleaning roller 102 located at the cleaning position. Two nozzle plates 37 can be cleaned simultaneously. Therefore, the configuration can be simplified and the number of parts can be reduced, and as a result, cost increases can be suppressed.

  In addition, the cleaning device 100 applies a voltage between the surface of the nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 before performing physical cleaning of the nozzle plate 37 using recording ink. A chemical reaction is caused to promote dissolution of ink deposits. As a result, the ink adhering matter adhering to the nozzle plate 37 can be reliably taken into the ink film M and delivered to the cleaning roller 102 together with the ink film M.

  Hereinafter, another embodiment of the present invention will be described. The following embodiment is different from the first embodiment only in the configuration of the image recording unit and the cleaning device. Therefore, the image recording unit and the cleaning device will be described. In the following embodiments, members having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A second embodiment will be described with reference to FIGS. Unlike the first embodiment, the cleaning device 200 of the second embodiment has head moving devices (not shown) provided corresponding to the four ink ejection heads 33, respectively.

  The head moving device includes, for example, a slide mechanism including a rack and pinion (not shown), a stepping motor for operating the slide mechanism, and the like. It can be moved with a predetermined stroke in a direction parallel to the surface (see FIGS. 7A and 7B). The head moving device is controlled by the main control device 110.

  In the second embodiment, the pipe 114 connecting each ink discharge head 33 and the corresponding ink feeding means 104 and the pipe 116 connecting each ink discharge head 33 and the corresponding ink cartridge 36 are as follows. It consists of, for example, a flexible tube that can follow the movement of each ink discharge head 33, so that the movement of each ink discharge head 33 is not hindered.

  When the main control device (not shown) determines that the non-printing time is equal to or longer than a predetermined time (for example, several minutes) based on the timing information from the timer 113, as in the first embodiment, the four inks The discharge head 33 is cleaned.

  Below, the cleaning method of the four ink discharge heads 33 of 2nd Embodiment is demonstrated based on the flowchart of FIG. 9 which shows the flow of a process of a main controller.

  In the image forming apparatus according to the second embodiment, the printing receiving member 58 is positioned at the printing receiving position, the cleaning roller 102 is positioned at the standby position, and the respective ink discharge heads 33 are set during the recording operation or standby. The printing position where the printing operation is performed, that is, the same position as each ink discharge head 33 of the first embodiment (see FIGS. 2A and 4A).

  First, the main control device rotates the printing receiving member 58 from the printing receiving position to the retracted position via the printing receiving member driving unit 108 (step S22).

  As shown in FIG. 8A, the main control device moves the cleaning roller 102 from the standby position to the cleaning position via the elevating device 112 and continues to each ink via the head moving device following step S22. The ejection head 33 is moved a distance L from the printing position to the downstream side in the rotation direction of the cleaning roller 102 in the direction parallel to the nozzle plate 37 (step S23). This distance L is set within a range in which the surface of the nozzle plate 37 of each ink discharge head 33 can face the outer peripheral surface of the cleaning roller 102 via a predetermined clearance (for example, 10 μm to 500 μm) (FIG. 8). (See (B)).

  At this time, as shown in FIG. 8B, the clearance between the surface of each nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 is the rotational direction of the cleaning roller 102 (the direction of the arrow Q in FIG. 8D). ) It gradually increases from the upstream side to the downstream side.

  Here, the upstream end and the downstream end of the surface of each nozzle plate 37 in the rotation direction of the cleaning roller 102 (hereinafter referred to as the upstream end and the downstream end of the surface of each nozzle plate 37 for convenience of explanation), respectively. It is assumed that the foreign substances D1 and D2 are attached to each.

  Subsequent to step S23, the main controller discharges a predetermined amount of ink from each ink discharge head 33 via the ink feeding means 104 (step S24), and then each nozzle plate 37 and the cleaning roller via the voltage applying means 107. A voltage is applied to 102 (step S25).

  At this time, as can be seen from FIG. 8C, the foreign matter D1 located at the position where the clearance between the surface of each nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 is the smallest is taken into the ink film M. The foreign matter D2 located at the position where the clearance is the largest is not taken into the ink film M.

  Subsequent to step S25, the main control device rotationally drives the cleaning roller 102 via the roller drive unit 111 and cleans each ink ejection head 33 via the head moving device in a direction parallel to the nozzle plate 37. For example, the distance to the upstream side in the rotation direction of the roller 102 is moved twice or more than the distance L (step S26).

  At this time, the ink film M sandwiched between the surface of each nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 is pulled by the outer peripheral surface of the cleaning roller 102 and moves in the rotational direction of the cleaning roller 102. Passing through the position where the clearance between the downstream end of the surface of the plate 37 and the outer peripheral surface of the cleaning roller 102 is the smallest while taking in the foreign matter D2 (see FIG. 8D), the cleaning roller 102 It is delivered on the outer peripheral surface (see FIG. 8E). The ink transferred onto the outer peripheral surface of the cleaning roller 102 is scraped off by the blade 106 as the cleaning roller 102 rotates, and is stored in a waste ink receiver (not shown).

  Subsequent to step S26, the main control device stops the rotational drive of the cleaning roller 102 via the roller driving unit 111 (step S27), and then the ink discharge heads 33 and the cleaning roller 102 via the voltage applying unit 107. Is stopped (step S28). Note that the order of step S27 and step S28 may be reversed.

  Subsequent to step S28, the main control device moves each ink discharge head 33 to the printing position via the head moving device and moves the cleaning roller 102 to the standby position via the lifting device 112 (step S29). Thereafter, the printing receiving member 58 is moved from the retracted position to the printing receiving position via the printing receiving member driving unit 108 (step S30), and then the flow is terminated.

  Here, when each ink discharge head 33 is positioned at the printing position and the cleaning roller 102 is positioned at the cleaning position, the clearance between the nozzle plate 37 and the cleaning roller 102 can be seen from FIG. The central portion of the surface of the nozzle plate 37 along the rotational direction of the cleaning roller 102 is the smallest, and gradually increases from the central portion toward the upstream side in the rotational direction of the cleaning roller 102 or from the central portion toward the downstream side. In this case, as shown in FIG. 4B, the upstream end and the downstream end in the rotation direction of the cleaning roller 102 in the ink film M sandwiched between the nozzle plate 37 and the cleaning roller 102 are the nozzle plate 37. If the foreign material adheres to at least one of the upstream end and the downstream end of the nozzle plate 37, the foreign matter is taken into the ink film M even if the cleaning roller 102 is driven in this state. There is a risk of not.

  Therefore, in the cleaning device 200 according to the second embodiment, as described above, the ink film M is sandwiched between the surfaces of the nozzle plates 37 and the outer peripheral surface of the cleaning roller 102 which are close to each other, and The clearance between the upstream and downstream ends of the surface of the nozzle plate 37 and the outer peripheral surface of the cleaning roller 102 is temporarily reduced by moving the ink discharge head 33 in a direction parallel to the surface of the nozzle plate 37. Thus, the foreign matter attached to at least one of the upstream end and the downstream end of the surface of the nozzle plate 37 is also surely taken into the ink film M.

  As described above, according to the cleaning device 200 of the second embodiment, not only the foreign matter attached to the location between the upstream end and the downstream end of the surface of each nozzle plate 37 but also the upstream end and the downstream of the surface of the nozzle plate 37. Foreign matter adhering to at least one of the ends can also be removed. That is, in the cleaning device 200 of the second embodiment, the entire surface of each nozzle plate 37 can be uniformly cleaned.

  Below, 3rd Embodiment is described based on FIG.10 and FIG.11. In the third embodiment, unlike the first and second embodiments, as shown in FIG. 10A, each of the four ink discharge heads 333 has its nozzle plate 337 (FIG. 11A). The surface of (see) is located on the same plane parallel to the XY plane. In the third embodiment, as shown in FIG. 11A, each nozzle port 337a passes through the nozzle plate 337 in a direction perpendicular to the nozzle plate 337. 11A to 11E, only one head portion 333b of each ink ejection head 333 is illustrated.

  Further, in the cleaning device 300 of the third embodiment, a belt mechanism 302 including a cleaning belt 302a is used instead of the cleaning roller 102 and the roller driving unit 111 used in the first and second embodiments. Have.

  The belt mechanism 302 is moved up and down by an elevating device (not shown) having the same configuration as the elevating device 112 of the first and second embodiments.

  The belt mechanism 302 includes a plurality of (for example, three) rollers 302b, a plurality of (for example, four) guide members 304, and a blade 106 in addition to the cleaning belt 302a.

  The three rollers 302b are arranged so as to face each other so that their respective axis lines are parallel to the X axis and are located, for example, at the apex of an inverted isosceles triangle as viewed from the + X side. One of the three rollers 302b is rotationally driven around its axis by a drive unit including a motor (not shown), and each of the other two rollers 302b is freely rotatable around that axis. Yes.

  The cleaning belt 302a is made of, for example, a conductive rubber endless belt, wound around three rollers 302b, and circulates as the rollers 302b rotate. Therefore, when one roller 302b is driven to rotate in the direction of arrow I in FIG. 10A, for example, the cleaning belt 302a is driven to rotate in the direction of arrow J in FIG. The surface of the cleaning belt 302 a has higher wettability than the surface of the nozzle plate 337 of each ink discharge head 333.

  The blade 106 is substantially the same as the blade 106 of each of the first and second embodiments (ink scraping means), and can move up and down with the cleaning belt 302a in the vicinity of the outer periphery of the cleaning belt 302a. Is arranged.

  The guide member 304 is disposed in contact with the back surface of the upper portion of the cleaning belt 302a located between the two upper rollers 302b that are separated in the Y-axis direction. Thereby, the rigidity regarding the gravity direction of this upper side part is secured.

  Next, a cleaning method for the four ink discharge heads 333 according to the third embodiment will be described.

  In the image forming apparatus, during the recording operation or standby, the printing receiving member 58 is positioned at the printing receiving position, and the belt mechanism 302 is positioned at a standby position vertically below the printing receiving member 58 (FIG. 10 ( A)).

  First, as in the first and second embodiments, the main control device determines that the non-printing time is equal to or longer than a predetermined time T (for example, several minutes) via the printing receiving member driving unit 108. Then, the printing receiving member 58 is rotated from the printing receiving position to the retracted position, and the belt mechanism 302 is moved from the standby position to the surface of the cleaning belt 302a and the nozzle plate 337 of each ink discharge head 33 via the lifting device. Is moved to a cleaning position facing (closely) with a predetermined clearance (for example, 10 μm to 500 μm) (see FIGS. 10B and 11A).

  Next, the main controller discharges ink from each ink discharge head 333 via the ink feeding means 104 and then applies a voltage between each nozzle plate 37 and the cleaning belt 302a via the voltage applying means 107. (See FIG. 11B). At this time, the foreign matter D adhering to the surface of each nozzle plate 37 is reliably taken into the ink film M sandwiched between each nozzle plate 337 and the cleaning belt 302a.

  The main controller then drives the cleaning belt 302a in this state. At this time, the ink film M is pulled by the surface of the cleaning belt 302 a having higher wettability than the surface of the nozzle plate 337 and moves downstream in the circumferential direction of the cleaning belt 302 a in a direction parallel to the surface of the nozzle plate 337. (See FIG. 11C), and the ink film M is cleaned by being peeled off from the surface of the nozzle plate 337 having higher liquid repellency than the surface of the cleaning belt 302a without being divided by the surface tension and viscosity of the ink film M. It is transferred onto the surface of the belt 302a for use (see FIG. 11D). The ink transferred onto the surface of the cleaning belt 302a is scraped off by the blade 106 along with the rotation of the cleaning belt 302a and is stored in a waste ink receiver (not shown).

  Next, as shown in FIG. 11E, the main control device moves the belt mechanism 302 from the cleaning position to the standby position via the lifting device, and then prints it via the printing receiving member driving unit 108. The copying member 58 is moved from the retracted position to the stamp receiving position (see FIG. 10A).

  According to the third embodiment, each of the four ink ejection heads 333 is arranged so that the surface of the nozzle plate 337 is located on the same plane, and the surface of the cleaning belt 302a is placed on the surface of the four nozzle plates 337. It is supposed that they face each other in a parallel state. Thereby, the clearance between each nozzle plate 337 and the cleaning belt 302a can be made constant (desired value) at an arbitrary position on the surface of the nozzle plate 337, and an arbitrary position on the surface of the nozzle plate 337. The foreign matter D adhering to the ink film M can be reliably taken into the ink film M. As a result, the surfaces of the nozzle plates 337 of the four ink discharge heads 333 can be cleaned simultaneously and evenly over the entire area.

  In addition, since the entire surface of the nozzle plate 337 can be cleaned only by rotating the cleaning belt 302a, that is, without moving the ink discharge heads 333, the control is simpler than in the second embodiment. is there.

  Below, 4th Embodiment is described based on FIG. 12 (A)-FIG. As shown in FIG. 12A, in the cleaning device 400 of the fourth embodiment, unlike the first and second embodiments, the cleaning roller 402 also has a function as an intermediate transfer member. That is, in the image forming apparatus of the fourth embodiment, each ink discharge head 433 is used to form an image on the outer peripheral surface of the cleaning roller 402, and the formed image is transferred to the paper P while being cleaned. Each ink discharge head 433 is cleaned using the roller 402.

  The cleaning roller 402 is disposed at a position where the outer peripheral surface thereof is close to and opposed to the surface of each ink ejection head 433 disposed at a position where a printing operation is performed. That is, the cleaning roller 402 is disposed at a fixed position, and no lifting device that moves the cleaning roller up and down is provided (see FIG. 14).

  The clearance between the outer peripheral surface of the cleaning roller 402 and the surface of the nozzle plate (not shown) of each ink discharge head 433 is set to, for example, 10 μm to 500 μm. In each ink discharge head 433, the nozzle port 437a penetrates the nozzle plate in a direction perpendicular to the surface of the nozzle plate. In the vicinity of the outer peripheral surface of the cleaning roller 402, a blade 106 for scraping off ink adhering to the outer peripheral surface of the cleaning roller 402 is disposed.

  Further, a pressure roller 404 having an X axis direction as an axial direction is vertically below the cleaning roller 402. For example, a pressure roller lifting device 405 (see FIG. 14) including a solenoid (not shown) cleans the cleaning roller 402. Is provided so as to be movable between a contact position that contacts the cleaning roller and a separation position that is separated from the cleaning roller 402. The pressure roller 404 is rotatable around its axis, and its outer peripheral surface is formed of an elastic material such as rubber. The pressure roller lifting / lowering device 405 is controlled by the main control device 410 (see FIG. 14). Note that in the image forming apparatus of the present embodiment, the printing receiving member 58 is not provided because a configuration is employed in which an image is formed on the paper P via the intermediate transfer member.

  Here, as a material of the cleaning roller 402, silicone rubber, nitrile rubber, urethane rubber, fluororubber, and elastomer obtained by coating these rubbers with fluorine-based materials can be used. The cleaning roller 402 does not need to be entirely formed of the above material, and is configured by winding a member formed of the above material around an outer peripheral surface of a cylindrical member made of a metal such as aluminum. May be. As described above, by using a material having a receding contact angle smaller than the surface of each nozzle plate for the outer peripheral surface of the cleaning roller 402, the gap between the surface of each nozzle plate and the outer peripheral surface of the cleaning roller 402 is set. The discharged ink can be transferred to the cleaning roller 402 more efficiently.

  In the fourth embodiment, detection means 403 for detecting information of an image formed on the outer peripheral surface of the cleaning roller 402 is provided (see FIG. 14). The detection means 403 is disposed opposite to the outer peripheral surface of the cleaning roller 402, and is a one-dimensional or two-dimensional light receiving sensor (not shown) that acquires image data formed on the outer peripheral surface of the cleaning roller 402. Includes an analysis unit (not shown) for analyzing the image data acquired by. The detection unit 403 outputs the analysis result of the image data to the main controller 410 (see FIG. 14). The main controller 410 determines whether each ink discharge head 433 is in a good discharge state based on the analysis result. More specifically, when determining that the image data has reached a predetermined quality based on the analysis result, the main controller 410 determines that the discharge state of each ink discharge head 433 is good, and performs the analysis. When it is determined that the image data does not reach a predetermined quality based on the result, it is determined that the ejection state of at least one ink ejection head 433 is not good.

  In the image forming apparatus according to the fourth embodiment, for example, based on image signals from a personal computer, ink is ejected in time series from the four ink ejection heads 433 to the outer peripheral surface of the cleaning roller 402 as an intermediate transfer member. A predetermined full-color image is formed on the outer peripheral surface of the roller 402 for use.

  The paper P supplied from the paper feed tray 16 or the manual feed tray 18 by the paper transport system 15 is transported in the + Y direction while being sandwiched between the cleaning roller 402 and the pressure roller 404 as shown in FIG. As a result, the image formed on the outer peripheral surface of the cleaning roller 402 is transferred.

  Of the ink that displays an image formed on the outer peripheral surface of the cleaning roller 402, the ink that displays an image that cannot be transferred onto the paper P by the pressure roller 404 is scraped off by the blade 106, for example. It is accommodated in a waste ink receiver (not shown).

  In the fourth embodiment, when the main control unit 410 determines that the ejection state of at least one ink ejection head 433 is not good based on the detection information from the detection unit 403 during the recording operation, the four ink ejection heads. 433 is cleaned.

  Hereinafter, a cleaning method for the four ink discharge heads 433 according to the fourth embodiment will be described with reference to a flowchart of FIG. 13 showing a processing flow of the main controller 410.

  As shown in FIG. 12A, during the recording operation, the cleaning roller 402 and the pressure roller 404 positioned at the contact position come into contact (pressure contact) via the paper P, and the cleaning roller 402 is moved to an arrow. Driven in the U direction, the pressure roller 404 rotates (follows) in the arrow V direction.

  First, the main controller 410 moves the pressure roller 404 from the contact position to the separation position via the pressure roller lifting / lowering device 405 and stops the rotation drive of the cleaning roller 402 via the roller drive unit 111. (Step S42). In this case, even if the recording operation by the print job currently being performed is not completed, the recording operation is interrupted and the cleaning operation is started.

  Subsequent to step S42, the main control device 410 discharges a predetermined amount of ink from each ink discharge head 433 (step S43), and then drives the cleaning roller 402 to rotate (step S44), so that the first or second ink is output. As in the embodiment, each ink discharge head 433 is cleaned.

  Subsequent to step S44, the main control device 410 performs trial ejection of ink from each ink ejection head 433 (step S45), and based on the detection information from the detection means 403, each ink ejection head 433 is similar to step S41. The quality of the discharge state is determined (step S46).

  If the main controller 410 determines in step S46 that the discharge state of each ink discharge head 433 is good, the main controller 410 stops the rotational drive of the cleaning roller 402 via the roller drive unit 111 (step S47), and then adds After the pressure roller 404 is moved from the separated position to the contact position via the pressure roller lifting / lowering device 405 (step S48), the flow is terminated.

  On the other hand, when the main controller 410 determines in step S46 that the ejection state of at least one ink ejection head 433 is not good, the processing of step S43 to step S45, that is, cleaning and trial ejection of each ink ejection head 433 is performed again. After the determination, the determination in step S46 is performed again.

  According to the image forming apparatus of the fourth embodiment, since the cleaning roller 402 also functions as an intermediate transfer member, the cleaning roller 402 is disposed at a position (fixed position) that is close to and faces each ink ejection head 433. Can do. Thereby, the transition between the recording operation and the cleaning operation can be performed quickly. Further, there is no need for a device for raising and lowering the cleaning roller 402, and there is no need to control the cleaning roller 402 with high accuracy, so that an increase in cost can be suppressed.

  In addition, when the recording operation is shifted to the cleaning operation, the cleaning is repeated until the discharge state of each ink discharge head 433 is good. Therefore, the next recording operation is performed in a state where the discharge state of each ink discharge head 433 is good. It is possible to prevent the deterioration of the image quality.

  Below, 5th Embodiment is described based on FIGS. 15-16 (C). As shown in FIGS. 15 and 16A, in the image forming apparatus of the fifth embodiment, unlike the first to fourth embodiments, four small ink ejection heads 533 and four inks are used. The cartridge 36, the four ink feeding means 104, and the like are mounted on a carriage 503 movable in the X-axis direction, and the carriage 503 is scanned in a paper width direction (X-axis direction) with a stroke larger than the paper width. As a result, ink can be ejected over the entire width direction of the paper P.

  The carriage 503 is slidably engaged with a guide rod (not shown) supported in the X-axis direction supported by the main body case 12 so as to be slidable in the X-axis direction. For example, a pair of pulleys and one of the pair of pulleys It is driven in the X-axis direction by a driving mechanism (not shown) including a driving motor and a timing belt wound around the pair of pulleys. This drive mechanism is controlled by a main controller (not shown).

  Each ink discharge head 533 has substantially the same configuration as the head portion 33b (see FIG. 3), and is arranged on the carriage 503 so that the longitudinal direction thereof is parallel to the Y axis. Further, as shown in FIG. 16A, the positional relationship between the four ink ejection heads 533 is the positional relationship between the four ink ejection heads 33 as viewed from the + X direction (see FIG. 2). (See (A)).

  Further, in the fifth embodiment, the cleaning roller 502 is positioned outside the print area of the paper P (for example, the position on the −X side of the print area of the paper P so that the axis thereof is parallel to the Y axis. ) Between the standby position, which is the lowest position, and the cleaning position, which is the highest position, so as to be movable up and down by a lifting device (not shown) having the same configuration as the lifting device 112. In the vicinity of the outer peripheral surface of the cleaning roller 502, a blade 106 is disposed as an ink scraping unit that can move up and down together with the cleaning roller 502.

  In the fifth embodiment, as in the first to third embodiments, when the main control device determines that the non-printing time is equal to or longer than a predetermined time T (for example, several minutes), the main control device moves the carriage 503 to + X. (See FIG. 16A), each ink discharge head 533 is positioned at a position facing the cleaning roller 502 (see FIG. 16B), and then the cleaning roller 502 is moved from the standby position. Each ink discharge head 533 is cleaned at the cleaning position in the same manner as in the first and second embodiments.

  In addition, this invention is not specifically limited to what was demonstrated by said 1st-5th each embodiment, A various deformation | transformation is possible.

<< First Modification >>
In the third embodiment, the printing receiving member 58 and the cleaning belt 302a are provided side by side. Instead, for example, the printing receiving member 58 is not provided and the printing belt 302a is not provided with the printing receiving member 58. It is good also as having the function as. More specifically, as shown in FIG. 17A, the upper part of the belt 302 for cleaning the belt mechanism 302 (the portion corresponding to the base of an inverted isosceles triangle as viewed from the + X direction) is each ink ejection head 333. The nozzle plate is disposed so as to face the nozzle plate within an ink discharge range. In this state, while the paper P is conveyed by the belt mechanism 302, ink is ejected from each ink ejection head 333 to the paper P to record an image. At this time, the rigidity of the cleaning belt 302a in the direction of gravity is enhanced by the four guide members that are in contact with the back surface of the cleaning belt 302a from below, so that the cleaning belt 302a functions sufficiently as a printing receiver. When cleaning each ink discharge head 333, for example, as shown in FIG. 17B, the four guide members 304 are raised together or individually, and the cleaning belt 302a is brought close to each ink discharge head 333. Thus, each ink discharge head 333 may be cleaned as in the third embodiment. In this case, since tension is applied to the cleaning belt 302a, fluttering of the cleaning belt 302a is suppressed, deformation of the cleaning belt 302a with time is corrected, and flatness of the cleaning belt 302a is improved. Is done.

  In the first modified example, the cleaning belt 302a is also provided with a function as a printing receiver. Instead, for example, the printing receiving member includes a cleaning belt 302a and four ink discharges. A horizontal movement is provided between an insertion position inserted into the gap with the head 333 and a retraction position retracted from the insertion position, and the printing receiving member is positioned at the insertion position during recording, and during cleaning. It is good also as positioning in a retreat position.

<< Second Modification >>
In the fourth embodiment, the cleaning roller 402 is also used as the intermediate transfer member. Instead, for example, as shown in FIGS. 18A and 18B, the third roller 402 is used. The same cleaning belt 302a as in the embodiment may be used as an intermediate transfer member. In this case, at the time of recording, the pressure roller 404 is brought into contact with the lower roller 302b of the belt mechanism 302 via the cleaning belt 302a, and the paper P is narrowed by the pressure roller 404 and the lower roller 302b. The image formed on the cleaning belt 302a while being held is transferred onto the paper P (see FIG. 18A). When cleaning each ink discharge head 333, the pressure roller 404 is separated from the lower roller 302b, and each ink discharge head 333 is cleaned as in the third embodiment. (See FIG. 18B).

<< Third Modification >>
In the fifth embodiment, each ink discharge head 533 and the cleaning roller 502 are used. Instead, for example, as shown in FIG. 19A, + X when viewed from the −Y side. Using the small ink discharge heads 633 and the small belt mechanism 602 having the same configuration as the ink discharge heads 333 and the belt mechanism 302 (see FIG. 10A) of the third embodiment as viewed from the side. Also good. More specifically, when cleaning each ink discharge head, a carriage (not shown) on which each ink discharge head 633, each ink cartridge 36, and each ink feeding means 104 is mounted is driven in the + X direction (FIG. 19A). After each ink discharge head 633 is positioned at a position facing the cleaning belt 602a (see FIG. 19B), the four guide members 604 are raised to cause the cleaning belt 602a to move to each ink discharge head 633. In the same manner as in the third embodiment, the ink discharge heads 633 may be cleaned.

  In the third modification, the upper portion of the cleaning belt 602a is moved up and down with respect to the roller 602b. However, instead of or in addition to this, the entire belt mechanism 602 may be moved up and down.

<< Fourth Modification >>
In the first embodiment, four ink ejection heads 33 are arranged along the outer peripheral surface of the virtual cylinder, and the four ink ejection heads 33 are simultaneously cleaned using the cleaning roller 102. Instead of, for example, as shown in FIG. 20A, four ink discharge heads 333 are arranged side by side in the Y-axis direction as in the third embodiment, and cleaning is performed with a diameter smaller than that of the cleaning roller 102. The four ink discharge heads 333 may be sequentially cleaned by moving the roller 702 from the −Y direction to the + Y direction (in the Y-axis direction) while rotating in the arrow Q direction. Note that at least one of the moving direction and the rotating direction of the cleaning roller 702 may be reversed.

  In the fifth embodiment, four ink ejection heads 533 are arranged along the outer peripheral surface of the virtual cylinder, and the four ink ejection heads 533 are simultaneously cleaned using the cleaning roller 502. Instead, for example, as shown in FIG. 20B, four ink discharge heads 633 are arranged side by side in the X-axis direction in the same manner as in the third modified example, and the cleaning is smaller in diameter than the cleaning roller 502. The four ink discharge heads 633 may be sequentially cleaned by moving the four ink discharge heads 633 from the −X direction to the + X direction (in the X axis direction) while the roller 802 is rotated in the arrow K direction. good. Note that at least one of the rotation direction of the cleaning roller 702 and the movement direction of the four ink discharge heads 633 may be reversed.

<< Fifth Modification >>
In each of the first to fifth embodiments, the clearance between each ink ejection head and the cleaning roller (or cleaning belt), and each ink ejection head and the cleaning roller when cleaning each ink ejection head. The relative speed with respect to the outer peripheral surface (or the surface of the cleaning belt) may be adjustable in accordance with the characteristics of the ink used for recording, that is, the surface tension and viscosity of the ink. Thereby, the cleaning efficiency of each ink discharge head can be further improved regardless of the characteristics of the ink used for recording.

  Specifically, at least one of the arrangement of the four ink discharge heads and the setting of the moving distance of the cleaning roller (or cleaning belt) according to the difference in the attributes of the ink (for example, the difference between aqueous and oily properties). The clearance is adjusted to an appropriate size by changing, and the relative speed is adjusted to an appropriate size by changing the setting of the rotation speed of the cleaning roller (or the rotation speed of the cleaning belt). Just do it.

  Further, since the ink has different characteristics for each color, the clearance and the relative speed may be adjusted according to the color of the ink, that is, for each ink ejection head. Specifically, the four ink discharge heads are individually moved in a direction intersecting the surface of the nozzle plate (for example, a direction orthogonal thereto) to adjust the clearance to an appropriate size for each ink discharge head ( 21A and 21B), each ink discharge head is moved in a direction parallel to the surface of the nozzle plate, and the cleaning roller is rotated or the cleaning belt is circulated. The speed may be adjusted to an appropriate size for each ink discharge head.

  In these cases, an appropriate combination of the clearance and the relative speed may be stored in, for example, a memory of the main control device, and read out during cleaning to adjust the relative speed and the clearance.

  In the fourth embodiment, the four ink discharge heads 433 are cleaned in close proximity to the cleaning roller 402 as an intermediate transfer member. However, if a plurality of ink ejection heads that eject different color inks are simultaneously cleaned, the ink removed from the surface of the nozzle plate by the intermediate transfer member may flow backward and mix from the nozzle ports that eject different color inks. . This becomes a factor of deteriorating the color quality of an image formed immediately after cleaning. Therefore, in order to avoid this color mixture, a cleaning roller is provided separately for each ink discharge head, and each ink discharge head 433 is individually cleaned using the corresponding cleaning roller. . Accordingly, each cleaning roller can independently clean the corresponding ink discharge head, and color mixing at the time of cleaning is prevented.

  In each of the first to third embodiments, the cleaning roller (or the cleaning belt) is disposed vertically below the four ink discharge heads. However, the present invention is not limited to this. For example, the four ink discharge heads Cleaning rollers (or cleaning belts) may be arranged vertically above, around, obliquely below, and obliquely above. In this case, the cleaning roller (or cleaning belt) and each ink discharge head are moved relative to each other in at least one of the vertical direction and the horizontal direction, for example, so that the surface of each nozzle plate and the outer peripheral surface of the cleaning roller come close to each other. May be opposed. In this case, only one of the ink discharge heads and the cleaning roller (or the cleaning belt) may be moved, or both may be moved.

  In the fourth embodiment, the size of the gap between the nozzle plate and the cleaning roller 402 is the same during recording and during cleaning. However, the present invention is not limited to this. For example, the ink discharge head 433 is connected to the nozzle. The size of the gap may be changed between recording and cleaning by moving in a direction intersecting the surface of the plate.

  In the fifth embodiment, the cleaning roller 502 is moved up and down so that the surface of each nozzle plate and the outer peripheral surface of the cleaning roller 502 are close to each other. The ejection head 533 is moved up and down, or both the cleaning roller 502 and the four ink ejection heads 533 are moved up and down so that the surface of each nozzle plate and the outer peripheral surface of the cleaning roller 502 are close to each other. Also good.

  In each of the first to third and fifth embodiments, when the ink deposit due to aggregation does not adhere to the nozzle plate due to the characteristics of the ink, it is not necessary to provide the voltage applying means. It is not necessary to apply a voltage between the plate and the cleaning roller (or cleaning belt).

  In each of the first to third and fifth embodiments, after discharging ink into the gap between the surface of each nozzle plate and the outer peripheral surface of the cleaning roller (or the surface of the cleaning belt), each nozzle plate Instead of applying a voltage between the cleaning roller (or cleaning belt), each nozzle plate and the cleaning roller (or cleaning belt) are discharged before discharging the ink into the gap. A voltage may be applied between the two.

  In the fourth embodiment, at least the surface of the cleaning roller 402 is formed of a conductive material, and a voltage is applied between each ink ejection head and the cleaning belt when each ink ejection head is cleaned. It's also good.

  In each of the first to third and fifth embodiments, each ink discharge head is cleaned based on the non-printing time. However, the present invention is not limited to this. For example, the number of discharges of each ink discharge head, Each ink discharge head may be cleaned based on the humidity, temperature, etc. in the atmosphere near each ink discharge head.

  In the fourth embodiment, each ink discharge head is cleaned based on the discharge state of each ink discharge head. However, the present invention is not limited to this. For example, each of the first to third and fifth embodiments described above is performed. Similarly to the embodiment, each ink discharge head may be cleaned based on the non-printing time, or based on the number of discharges of each ink discharge head, the humidity in the atmosphere in the vicinity of each ink discharge head, the temperature, and the like.

  In each of the first to fifth embodiments, ink is discharged into the gap between each ink ejection head and the cleaning roller (or cleaning belt) by feeding ink into the ink ejection head using the ink feeding means. However, instead of this, for example, ink may be supplied to the gap by sucking ink from each ink discharge head using an ink suction means such as a vacuum pump. In this case, the sucked ink may be discharged, for example, to a waste ink reservoir (not shown) installed in the lower part of the main body case 12 and absorbed and held by an ink absorber inside the waste ink reservoir.

  In the second embodiment, each ink discharge head 33 is moved in a direction parallel to the surface of the nozzle plate 37 and the cleaning roller 102 is driven to rotate. Only the ink discharge heads 33 may be moved with a larger stroke than in the second embodiment without rotationally driving the roller 102. In this case, each ink discharge head may be moved from the downstream side in the rotation direction of the cleaning roller to the upstream side, or may be moved from the upstream side in the rotation direction of the cleaning roller to the downstream side. In this case, after the movement operation of each ink discharge head is completed, the cleaning roller may be driven to rotate, and the foreign matter attached to the outer peripheral surface of the cleaning roller may be scraped off by the blade. In the second embodiment, each ink discharge head 33 is moved from the downstream side to the upstream side in the rotation direction of the cleaning roller 102. Instead, each ink discharge head is moved to the cleaning roller. It is good also as moving at a speed different from the moving speed of the outer peripheral surface of the cleaning roller from the upstream side to the downstream side in the rotation direction. In short, the surface of each nozzle plate and the outer peripheral surface of the cleaning roller may be relatively moved in a direction parallel to the surface of the nozzle plate.

  In each of the first, third, and fifth embodiments, each ink discharge head may be moved in a direction parallel to the surface of the nozzle plate, as in the second embodiment. In this case, the cleaning roller (or cleaning belt) may be driven together with each ink discharge head or may not be driven.

  In each of the first to third and fifth embodiments, the lifting device or the head moving device adopts the rack and pinion method. However, the present invention is not limited to this. For example, a feed screw method, a linear motor Any method may be adopted as long as the method can be linearly driven. However, it is particularly preferable that the lifting device has a high-speed and highly accurate position control function.

  The configuration of the belt mechanism 302 of the third embodiment is not limited to that described above. For example, the number of rollers around which the cleaning belt is wound may be two, four or more. The cleaning belt 302a may be configured to be able to circulate around the X axis.

  In each of the first to fifth embodiments, the cleaning roller or the cleaning belt is used for cleaning the four ink ejection heads. Which of these is used depends on the inside of the image forming apparatus. It is desirable to select appropriately according to the layout, specifications, the size of the ink ejection head, and the like.

  In each of the first to fifth embodiments, a roller or a belt is used as a member that faces and faces the four ink ejection heads. However, the present invention is not limited to this, and a flat plate member, for example, may be used. In this case, for example, one flat plate member may be simultaneously opposed to and opposed to the four ink ejection heads, or the four flat plate members may be individually opposed to and opposed to the four ink ejection heads. .

  In each of the first to fifth embodiments, the main control device cleans the four ink discharge heads by operating at least one of the cleaning roller (or cleaning belt) and the ink discharge head. Not limited to this, for example, a user, a serviceman, or the like appropriately operates at least one of the cleaning roller (or cleaning belt) and the ink discharge head via, for example, an operation unit (not shown) of the image forming apparatus 10. It may be cleaned.

  In general, the degree of wettability (or liquid repellency) is based on the affinity between a liquid and a member such as a static contact angle and surface tension. Of the dynamic contact angles, the receding contact angle is measured as a value in which the influence of the viscosity of the liquid is added in addition to this affinity. It has been found that ink is well released from members having a large receding contact angle, and that ink is more adsorbed to members having a small receding contact angle. In particular, as a condition with good releasability, the receding contact angle of the surface of the nozzle plate is 60 ° or more, preferably 75 ° or more with respect to pure water, and the receding contact angle of the outer peripheral surface of the cleaning roller is 70 °. And more desirably 60 ° or less. Therefore, in each of the first to fifth embodiments, the surface of the nozzle plate is obtained by using a material having a receding contact angle smaller than the surface of the nozzle plate for the outer peripheral surface of the cleaning roller (or the surface of the cleaning belt). And the outer periphery of the cleaning roller (or the surface of the cleaning belt) can be more efficiently transferred to the cleaning roller (or cleaning belt).

  In each of the first to fifth embodiments, the image forming apparatus including the four ink discharge heads in which four colors of yellow, magenta, cyan, and black are individually incorporated has been described. The present invention is not limited to this, and the present invention is also suitably applied to an image forming apparatus including at least one ink discharge head that contains only one color, or any two colors, or any three colors, or five or more colors. it can.

  In each of the first to fifth embodiments, the printer (color printer) has been described as an example of the image forming apparatus of the present invention. However, the present invention is not limited to this. A copier, a facsimile machine, a copier and a facsimile machine, or in addition thereto. MFPs with printer functions, liquid crystal display manufacturing equipment that manufactures liquid crystal displays by discharging liquid crystal onto a substrate, DNA chip manufacturing equipment that manufactures DNA chips by discharging DNA solution onto a substrate, such as semiconductors such as amorphous silicon The present invention can be applied to an image forming apparatus such as a circuit board manufacturing apparatus that manufactures a circuit board by discharging the substrate onto the substrate.

  As described above, the liquid discharge head cleaning device of the present invention is suitable for cleaning a liquid discharge head having a liquid discharge port formed on one surface thereof. The liquid discharge head cleaning method of the present invention is suitable for cleaning the liquid discharge head. The image forming apparatus of the present invention is suitable for forming an image on a recording medium using the liquid discharge head.

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 33 ... Ink ejection head (liquid ejection head), 37a ... Nozzle port (liquid ejection port), 100 ... Cleaning device, 102 ... Cleaning roller (opposing member), 104 ... Ink feeding means (liquid supply) Means), 111... Roller drive unit (first moving means), 112... Elevating device (second moving means), 107.

JP 2009-101631 A JP-A-2005-336306

Claims (15)

The liquid discharge port for discharging the liquid is a liquid discharge head cleaning device formed on one side of the liquid discharge port,
A facing member having a facing surface facing the one side surface;
Liquid supply means for supplying the liquid in the liquid discharge head to a gap between the one side surface and the opposite surface facing the one side surface via the liquid discharge port;
First moving means for relatively moving the one side surface and the facing surface in a direction parallel to the one side surface in a state where the liquid is supplied to the gap by the liquid supply means. A cleaning device characterized by. The facing member is a roller that is rotatable about an axis parallel to the surface on the one side,
The first moving means moves the liquid discharge head in a direction parallel to the one side surface in a state where the liquid is supplied to the gap, and rotationally drives the roller around the axis. The cleaning apparatus according to claim 1, wherein at least one of the above is performed. The opposing member is a belt that can circulate around an axis parallel to the surface on the one side,
The first moving unit moves the liquid discharge head in a direction parallel to the one side surface in a state where the liquid is supplied to the gap, and drives the belt around the axis. The cleaning apparatus according to claim 1, wherein at least one of the above is performed.   The cleaning apparatus according to claim 1, wherein the first moving unit is capable of adjusting a speed of the relative movement in accordance with characteristics of the liquid. A plurality of the liquid discharge heads are provided,
The first moving means is capable of individually adjusting the speed of the relative movement by individually moving each of the plurality of liquid ejection heads in a direction parallel to the one side surface thereof. The cleaning device according to claim 4.   The cleaning apparatus according to claim 1, further comprising a second moving unit that relatively moves the one side surface and the facing surface in a direction toward or away from the surface. .   The cleaning apparatus according to claim 6, wherein the second moving unit is capable of adjusting a size of the gap according to a characteristic of the liquid. A plurality of the liquid discharge heads are provided,
The second moving means is capable of individually adjusting the gap by individually moving each of the plurality of liquid ejection heads in a direction intersecting the one side surface thereof. 8. The cleaning device according to 7. The liquid is a liquid containing water,
The one side surface and the opposite surface have conductivity,
The cleaning apparatus according to claim 1, further comprising a voltage applying unit capable of applying a voltage between the one side surface and the facing surface.   The liquid supply means supplies the liquid to the gap through the liquid discharge port by feeding the liquid into the liquid discharge head. A cleaning device according to claim 1.   The liquid supply unit supplies the liquid in the liquid discharge head to the gap by sucking the liquid through the liquid discharge hole. Cleaning device.   The opposing member functions as an intermediate transfer member that forms an image on the opposing surface when the liquid is ejected from the liquid ejection head onto the opposing surface and transfers the formed image to a recording medium. It has, The cleaning apparatus as described in any one of Claims 1-11 characterized by the above-mentioned.   The cleaning apparatus according to claim 1, wherein the facing surface has higher wettability with the liquid than the surface on the one side. The liquid discharge port for discharging the liquid is a cleaning method of the liquid discharge head formed on the one side surface thereof,
Supplying the liquid in the liquid ejection head to the gap between the one side surface and the opposite surface facing the one side surface via the liquid ejection port;
And a relative movement of the one side surface and the opposite surface in a direction parallel to the one side surface in a state where the liquid is supplied to the gap. A liquid discharge port for discharging a liquid is an image forming apparatus that forms an image on a recording medium using a liquid discharge head formed on one side of the liquid discharge port.
An image forming apparatus comprising the cleaning device according to claim 1.

Images