JP6232862B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a recording head for discharging droplets.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, a plotter, and a complex machine of these, for example, a liquid discharge recording type image forming apparatus using a recording head composed of a liquid discharge head (droplet discharge head) for discharging droplets An ink jet recording apparatus or the like is known.

  By the way, when a droplet is ejected from the recording head, a mist much smaller than the main droplet is generated in addition to the main droplet that forms an image. If the generated mist adheres to the recording medium, the image quality will be degraded, if it adheres to the periphery of the nozzle, it may cause nozzle non-ejection, or if it adheres to a member in the device, it will become contaminated. Not only will it cause malfunctions.

  Therefore, a suction means for sucking mist is provided. Here, for example, a suction port is provided between the recording heads, and suction is performed by a fan connected to the suction port (Patent Document 1).

  Also, the rotation speed of the suction means is changed according to the movement speed of the carriage (Patent Document 2), and the rotation speed of the suction means is controlled so that the movement speed of air including mist is faster than the conveyance speed of the paper. (Patent Document 3) and the like.

Japanese Patent No. 2801231 JP 2007-136847 A JP 2010-201873 A

  By the way, the mist generated along with the droplet discharge moves not only on the downstream side in the medium conveying direction but also on the upstream side. At this time, the moving direction and amount of the mist change depending on the conveyance speed of the recording medium.

  For this reason, in the configuration in which suction is performed from all suction ports using a common suction means as disclosed in Patent Document 1, there is a problem that mist cannot be efficiently collected.

  This invention is made | formed in view of said subject, and it aims at enabling it to collect | recover mist efficiently.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged;
A conveying means for conveying a recording medium,
The recording head is arranged in a direction in which the nozzle row intersects the medium conveyance direction,
An upstream suction port and a downstream suction port that open toward the liquid droplet ejection direction are arranged on the upstream side and the downstream side of the recording head in the medium conveyance direction, respectively.
Control means for controlling the suction amount from the upstream suction port and the downstream suction port so that the suction amount from the downstream suction port is larger than the suction amount from the upstream suction port;
The control means includes
According to the increase in the conveyance speed of the recording medium,
Increase the amount of suction from the downstream suction port,
Control is performed to reduce the amount of suction from the upstream suction port.

  According to the present invention, mist can be collected efficiently.

1 is an explanatory diagram illustrating an overall configuration of an example of an image forming apparatus according to the present invention. FIG. 4 is an explanatory diagram viewed from the conveying belt side illustrating an example of a recording head unit of the apparatus. FIG. 3 is a cross-sectional explanatory view taken along line AA in FIG. 2. FIG. 3 is a cross-sectional explanatory view taken along line BB in FIG. 2. It is block explanatory drawing with which the outline | summary of the control part of the apparatus is provided. It is principal part expansion explanatory drawing at the time of the image quality priority mode with which it uses for description of the suction control in 1st Embodiment of this invention. It is a principal part expansion explanatory drawing at the same time in speed priority mode. It is a flowchart with which it uses for description of the suction control by the control part in 1st Embodiment. FIG. 6 is an explanatory diagram around one recording head for explaining a second embodiment of the present invention. It is explanatory drawing around one recording head with which it uses for description of 3rd Embodiment of this invention. It is explanatory drawing which looked at the recording head unit with which it uses for description of 4th Embodiment of this invention from the conveyance belt side. It is a side explanatory view similarly.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram illustrating the overall configuration of the image forming apparatus.

  This image forming apparatus is a line type image forming apparatus. A sheet 100 as a recording medium loaded on the sheet feeding tray 101 is conveyed by a sheet feeding roller 102 along a conveyance path shown by a broken line. The paper 100 transported to the transport path is transported to the belt transport unit 104 via a timing alignment / skew correction roller (so-called registration roller) pair 103.

  When the paper 100 is conveyed, the paper thickness is set by the paper thickness sensor 300 provided in the paper feed tray 101 or the user's paper type, the recording head unit 200 is moved up and down, and the recording head unit 200 and the paper A gap of 100 is set.

  The belt conveyance unit 104 includes a conveyance roller 105 driven at a predetermined timing, a tension roller 106, and an endless conveyance belt 107 wound around these rollers 105 and 106.

  In order to hold the paper 100 with the conveyance belt 107 of the belt conveyance unit 104, means by electrostatic adsorption, adsorption by air suction, or other known means can be used.

  The sheet 100 is conveyed by the belt conveyance unit 104 so as to face the recording head unit 200, and the recording head unit 200 is driven according to the image data to eject droplets, thereby forming an image.

  The recording head unit 200 is provided with a temperature sensor 400. The energy for ejecting ink droplets of the recording head unit 200 is controlled according to the environmental temperature detected by the temperature sensor 400.

  On the paper 100 on which the image is formed by the recording head unit 200, undried ink constituting the image is attached. In order to dry the undried ink, a drying mechanism such as a heater or hot air may be provided between the decurler unit 109 and the like, although not shown.

  The paper 100 on which an image is formed by the recording head unit 200 is conveyed to the decurler unit 109 and decurled (curl correction).

  When the paper 100 that has passed through the decurler unit 109 is discharged as it is, it is conveyed by the separation claw 110 via the conveyance path 111 to the paper discharge roller 112 and discharged.

  In the case of reverse paper discharge or reverse side printing (double-sided printing), the separation claw 110 is switched counterclockwise from the position shown in the drawing, passes through the conveyance path 113, passes through the guide member 114, and is sent to the hitting roller 115. . The paper 100 sent to the hitting roller 115 is conveyed in the reverse direction by the hitting roller 115 whose rotation direction has been switched.

  In the case of reverse paper discharge as it is, it passes through the second separation claw 116, passes through the conveyance path 117, is sent to the paper discharge roller 112, and is discharged.

  In the case of printing on the back side, the sheet 100 conveyed in the reverse direction by the tapping roller 115 passes between the second separation claw 116 and the double-side reversing roller 118 that are switched counterclockwise from the illustrated position, and then the conveyance path 119. And is sent to the registration roller pair 103.

  The recording medium (paper 100) is not limited to cut paper but may be film or roll paper.

  In addition, a maintenance / recovery unit 108 is provided to maintain and recover the performance of the recording head unit 200. The maintenance / recovery unit 108 wipes ink remaining on the head when the ink is sucked into the cap 120, a cap 120 for capping the nozzle surface of each head of the recording head unit 200, a suction pump (not shown) connected to the cap 120. A wiper 121 is provided.

  Here, when performing the maintenance / recovery operation, the recording head unit 200 moves up, and the maintenance / recovery unit 108 moves to below the recording heads of the recording head unit 200 to perform the maintenance / recovery operation. Further, the cap 120 of the maintenance / recovery unit 108 also serves as a moisture retention cap that maintains the humidity of each recording head of the recording head unit 200 during standby, and the recording head unit 200 rises during non-printing, and the maintenance / recovery unit 108. Moves below the recording head unit 200 to perform moisture retention capping.

  Next, an example of the recording head unit 200 will be described with reference to FIG. FIG. 2 is an explanatory view of the recording head unit as viewed from the conveying belt side.

  The recording head unit 200 ejects yellow (Y), magenta (M), cyan (C), and black (K) ink droplets onto the base member 210 (head units 211Y, 211M, 211C, and 211K (when not distinguished). "Head unit 211").

  The head unit 211 is a line type liquid discharge head unit in which a plurality of liquid discharge heads (recording heads) 202 having a plurality of nozzles 212 for discharging droplets are arranged in a length corresponding to the paper width.

  Here, the plurality of recording heads 202 are arranged in a staggered manner in odd and even rows to form a head having a length corresponding to the paper width. In addition, an odd nozzle row 201O and an even nozzle row 201E in which a plurality of nozzles 212 are arranged (also referred to as “nozzle row 201” when not distinguished) are also arranged in a staggered manner. The recording head 202 is disposed on the base member 210 in a direction in which the nozzle row 201 intersects the medium conveyance direction (not only orthogonal but also oblique).

  Next, the configuration of the mist suction means in the recording head unit 200 will be described with reference to FIGS. 3 is a cross-sectional explanatory view taken along line AA in FIG. 2, and FIG. 4 is a cross-sectional explanatory view taken along line BB in FIG.

  The base member 210 is provided with an upstream suction port 203 and a downstream suction port 204 that open toward the droplet discharge direction on the upstream and downstream sides of the recording head 202 in the medium conveyance direction, respectively.

  The upstream suction port 203 communicates with the upstream mist collection common space 205 formed in the base member 210 via the path 203a. The upstream mist collection common space 205 is provided with an upstream suction fan 206 serving as suction means via a filter 207.

  By rotating and driving the upstream suction fan 206, an airflow sucked into the upstream suction port 203 is generated, and mist generated when droplets are ejected from the recording head 202 is collected from the upstream suction port 203. It is taken into the common space 205 and collected by the filter 207.

  Similarly, the downstream suction port 204 communicates with the downstream mist collection common space 208 formed in the base member 210 via the path 204a. The downstream mist collection common space 208 is provided with a downstream suction fan 209 serving as suction means via a filter 207.

  By rotating and driving the downstream suction fan 209, an air flow sucked into the downstream suction port 204 is generated, and mist generated along with droplet ejection from the recording head 202 is collected from the downstream suction port 204 to the downstream mist. It is taken into the common space 208 and collected by the filter 207.

  In addition, although the upstream suction fan 206 and the downstream suction fan 209 separate the upstream suction and the downstream suction, they can be switched by one fan and a valve. In this way, in order to vary the suction amount while using a common fan, a means for changing the flow path resistance may be disposed in the middle of the paths 203a and 204b.

  Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. FIG. 5 is a block diagram of the control unit.

  The control unit 500 includes a CPU 501 that also functions as a control unit according to the present invention that controls the entire apparatus, a ROM 502 that stores fixed data such as a program executed by the CPU 501, and a RAM 503 that temporarily stores image data and the like. ing. The control unit 500 also includes a rewritable nonvolatile memory 504 for holding data while the apparatus is powered off, image processing for performing various signal processing and rearrangement on image data, and other entire apparatus. And an ASIC 505 for processing input / output signals for controlling.

  The control unit 500 also includes a print control unit 508 including a data transfer unit for driving and controlling each recording head 202 of the recording head unit 200 and a driving signal generating unit, and a head driver (for driving each recording head 202). Driver IC) 509 and a motor driving unit 510 for driving a paper feed motor 530 for rotating the conveyor belt 107 and the like.

  The control unit 500 is connected to an operation panel 514 for inputting and displaying information necessary for the apparatus.

  The control unit 500 has an I / F 506 for transmitting and receiving data and signals to and from the host side. From the host 600 side such as an information processing apparatus such as a personal computer, the I / F 506 is connected via a cable or a network. Receive at.

  Then, the CPU 501 of the control unit 500 reads and analyzes the print data in the reception buffer included in the I / F 506, and performs necessary image processing, data rearrangement processing, and the like in the ASIC 505. This image data is transferred from the print control unit 508 to the head driver 509.

  The print control unit 508 transfers the above-described image data, and performs D / A conversion, voltage amplification, and current amplification on the drive pulse pattern data stored in the ROM to form one drive pulse or a plurality of drive pulses. The drive signal to be output is output to the head driver 509.

  The I / O unit 513 acquires information from various sensor groups 515 mounted on the apparatus, extracts information necessary for controlling the apparatus, and is used for controlling the print control unit 508, the motor drive unit 510, and the like. To do. The sensor group 515 includes an optical sensor for detecting the position of the paper in addition to the temperature sensor 400 described above, and the I / O unit 513 can process various sensor information.

  Next, suction control in the first embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an enlarged explanatory view of a main part for explanation in the image quality priority mode, and FIG. 7 is an enlarged explanatory view of a main part for explanation in the speed priority mode.

  The image forming apparatus according to the present embodiment has, as print modes, a speed priority mode that prioritizes productivity over image quality and an image quality priority mode that prioritizes image quality over productivity. The conveyance speed V1 of the paper 100 in the speed priority mode is set to be faster (V1> V2) than the conveyance speed V2 of the paper 100 in the image quality priority mode.

  Here, normally, when droplet discharge is performed with the conveying belt 107 stopped, a downdraft is generated by the main droplet 700, and the downdraft collides with the paper 100 to generate an updraft. Scatters in the air current. On the other hand, when the paper 100 is transported by moving the transport belt 107, an airflow generated by the transport is added, and the manner in which the mist 701 is scattered changes.

  First, when the print mode is the image quality priority mode, that is, when the paper transport speed is a relatively low transport speed V2, as shown in FIG. 6, the upstream suction fan 206 is driven to the upstream suction port. The suction is performed from 203 with the suction amount Q2, and the downstream suction fan 209 is driven to perform the suction with the suction amount P2 from the downstream suction port 204.

  That is, when the conveyance speed of the paper is low, the airflow generated by the conveyance is weak, and thus the influence of the rising airflow generated by the main droplet 700 becomes strong. Therefore, the amount of the mist 701 that rides on the airflow generated by the conveyance is reduced, and the mist 701 scatters on the rising airflow generated by the main droplet 700.

  In particular, the mist generated when the main droplet 700 from the upstream nozzle row 201O is ejected tends to ride on the ascending air current 701, and the nozzle surface is soiled to cause ejection failure.

  Here, even if suction is performed only with the downstream suction port 204, the mist 701 generated on the upstream side can hardly be recovered. Therefore, the mist 701 riding on the ascending air current can be recovered by performing suction from the upstream suction port 203.

  At this time, since the mist 701 generated on the upstream side rises, the mist 701 generated on the upstream side tends to go to the upstream suction port 203, and the mist 701 generated on the downstream side easily rides on the airflow generated by the paper 100 and easily moves away from the downstream suction port 204. .

  Therefore, it is possible to collect more mist when the suction amount P2 of the downstream suction port 204 is larger than the suction amount Q2 of the upstream suction port 203.

  Next, when the print mode is the speed priority mode, that is, when the paper transport speed is a relatively high transport speed V1, the upstream suction fan 206 is driven to perform upstream suction as shown in FIG. The suction is performed from the port 203 at the suction amount Q1 (Q1 <Q2), the downstream suction fan 209 is driven, and the suction is performed from the downstream suction port 204 at the suction amount P1 (P1> P2). Note that P1> Q1 is also satisfied.

  In other words, when the paper transport speed is high, the air flow generated by the transport is more dominant than the air flow generated by the main droplet 700. Therefore, most of the mist 701 generated by droplet discharge from the upstream nozzle row 201O and the downstream nozzle row 201E is directed to the downstream side.

Therefore, suction is performed by increasing the suction amount from the downstream suction port 204 from the suction amount P2 to the suction amount P1 as compared with the case where the sheet conveyance speed is low.

  On the other hand, since the mist 701 floating in the direction of adhering to the nozzle surface by droplet discharge is also generated from the upstream nozzle row 201O, suction is also performed from the upstream suction port 203. At this time, the amount of suction from the upstream side suction port 203 can be reduced as compared with the case where the sheet conveyance speed is low.

  The suction control by the control unit 500 in the first embodiment will be described with reference to the flowchart of FIG.

  When printing is started, the print mode is determined to determine whether the speed priority mode or the image quality priority mode.

  In the image quality priority mode, as described above, the upstream suction fan 206 is driven to perform suction with the suction amount Q2 from the upstream suction port 203, and the downstream suction fan 209 is driven to downstream the suction port 204. The suction is performed with the suction amount P2.

  On the other hand, in the speed priority mode, as described above, the upstream suction fan 206 is driven to perform suction with the suction amount Q1 from the upstream suction port 203, and the downstream suction fan 209 is driven to perform downstream suction. Suction is performed from the port 204 at a suction amount P1.

  Then, suction is stopped when printing is completed.

Thus, in accordance with an increase in the transport speed of the recording medium, to increase the amount of suction from the downstream side suction opening, by the control for reducing the amount of suction from the upper stream side suction opening, effectively mist Recovery can be performed.

  Further, in the case where the common suction means and the means for distributing the suction force by the suction means to the upstream suction port and the downstream suction port are provided, the suction force is limited by distributing the suction force in the direction with much mist. Mist can be collected efficiently with suction force.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory view around one recording head for explaining the embodiment.

  In the present embodiment, the opening position of the downstream suction port 204 is projected to the nozzle surface position of the recording head 202. That is, the suction port portion 241 forming the downstream suction port 204 is extended to the nozzle surface position (or the vicinity thereof).

  Mist 701 that flows downstream from the recording head 202 in the medium conveying direction is scattered more toward the paper 100 than from the recording head 202 side. Therefore, by projecting the opening position of the downstream suction port 204 toward the paper 100 side, the suction flow velocity in the vicinity of the paper 100 side by the downstream suction port 204 is increased, and a large amount of mist can be sucked.

  On the other hand, since the mist 701 easily flows to the upstream suction port 203 on the upstream side, it is not necessary to project the opening position of the upstream suction port 203 toward the paper 100 side, and the formation of the paper 100 and the suction port 203 by the floating of the paper 100 Contact with a part can be reduced.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is an explanatory view around one recording head for explaining the embodiment.

  In the present embodiment, an upstream guide portion 230 that projects in the droplet discharge direction and guides the airflow generated by suction is formed on the upstream side of the upstream suction port 203 in the medium conveyance direction. At least the surface on the recording head 202 side of the upstream guide unit 230 is formed on an inclined surface 230a that extends downstream in the suction direction. That is, the inclined surface 230a of the upstream guide unit 230 has a shape that approaches the recording head 202 side as it approaches the paper 100 side in the medium conveyance direction.

  Thus, the mist generated and soared on the upstream side can easily flow to the upstream suction port 203, and the mist generated on the upstream side can be efficiently sucked and collected.

  Further, a downstream guide portion 240 that projects in the droplet discharge direction and guides the airflow generated by suction is formed on the downstream side of the downstream suction port 204 in the medium conveyance direction. At least the surface on the recording head 202 side of the downstream guide portion 240 is formed as an inclined surface 240a that extends downstream in the suction direction. That is, the inclined surface 240a of the downstream guide unit 240 has a shape that approaches the recording head 202 side as it approaches the paper 100 side in the medium conveyance direction.

  Accordingly, the mist generated and swept up on the downstream side can easily flow to the downstream suction port 204, and the mist generated on the downstream side can be efficiently sucked and collected.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a view of the recording head unit used for description of the embodiment as viewed from the conveying belt side, and FIG. 12 is a side view of the same.

  In the present embodiment, side suction ports 251 and 251 are provided on both sides of the recording head unit 200 in the direction intersecting the medium conveyance direction. A part 251a of the side suction port 251 is formed to extend in a direction crossing the medium transport direction.

  As a result, the mist that cannot be completely sucked by the upstream suction port 203 and the downstream suction port 204 but has scattered in the direction intersecting the medium transport direction is collected by the side suction ports 251 and 251 and the mist is scattered. Can be prevented more.

  Here, the side suction port 251 is connected to the upstream mist collection common space 205 through a path (not shown) so as to be sucked by the upstream suction fan 206. In this case, the suction amount of the upstream suction port 203 is reduced by the side suction port 251, but the suction amount of the upstream suction port 203 may be lower than the suction amount of the downstream suction port 204. Does not occur.

  In this case, a valve may be attached to the side suction port 251 in accordance with conditions where mist is likely to occur, and suction switching may be performed using the valve.

  In this embodiment, a side guide portion 252 is provided on the side opposite to the recording head 202 side along the side suction port 251 in the medium transport direction. Thereby, mist is guided to the side suction port 251 and efficient suction can be performed.

  Also in this case, the side guide portion 252 forms an inclination toward the recording head 202 side toward the conveyance belt 107 side, and is configured such that mist easily enters the side suction port 251.

  Further, the side guide portion 252 is disposed outside the width of the transport belt 107 in a direction crossing the transport direction, and is formed so as to protrude below the transport surface of the transport belt 107 (downstream in the droplet discharge direction). Yes.

  As a result, there is no gap between the surface of the conveyor belt 107 and the side guide portion 252 and the mist easily flows through the side suction port 251.

  In each of the above embodiments, it is preferable to adjust the suction amount according to the gap length between the recording head and the paper.

  That is, when the gap length between the recording head and the paper can be adjusted, when the gap is relatively narrow, mist tends to adhere to the paper and the amount of mist is reduced. Therefore, the suction amount is adjusted according to the gap length between the recording head and the paper. For example, when the gap is narrow, the suction amount is decreased. Thereby, it is possible to reduce the influence of the suction on the paper floating, the power consumption of the suction device, the noise, and the landing of the main droplet.

  Moreover, the amount of mist changes with environmental temperature and humidity. For example, mist is more likely to occur at a lower temperature than at a higher temperature. Therefore, by adjusting the suction amount according to the environmental temperature and humidity, it is possible to reduce the influence of suction on the floating of the paper, the power consumption of the suction device, the noise, and the landing of the main droplet.

  In the present application, the “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, etc., and means a material to which ink droplets or other liquids can be attached. , Recording media, recording paper, recording paper, and the like. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics or the like. In addition, “image formation” not only applies an image having a meaning such as a character or a figure to a medium but also applies an image having no meaning such as a pattern to the medium (simply applying a droplet to the medium). It also means to land on.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

100 sheets (recording medium)
200 recording head unit 202 recording head 203 upstream suction port 204 downstream suction port 206 upstream suction fan 207 downstream suction fan 210 base member

Claims (9)

A recording head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged;
A conveying means for conveying a recording medium,
The recording head is arranged in a direction in which the nozzle row intersects the medium conveyance direction,
An upstream suction port and a downstream suction port that open toward the liquid droplet ejection direction are arranged on the upstream side and the downstream side of the recording head in the medium conveyance direction, respectively.
Control means for controlling the suction amount from the upstream suction port and the downstream suction port so that the suction amount from the downstream suction port is larger than the suction amount from the upstream suction port;
The control means includes
According to the increase in the conveyance speed of the recording medium,
Increase the amount of suction from the downstream suction port,
An image forming apparatus that controls to reduce the amount of suction from the upstream suction port.   The image forming apparatus according to claim 1, wherein the opening of the downstream suction port is located closer to the conveying unit than the opening of the upstream suction port.   The image forming apparatus according to claim 1, wherein a guide unit that guides an airflow generated by suction is disposed upstream of the upstream suction port in the medium conveyance direction.   4. The image forming apparatus according to claim 1, wherein a guide portion that guides an airflow generated by suction is disposed downstream of the downstream suction port in the medium conveyance direction. 5.   The image forming apparatus according to claim 3, wherein the guide portion has an inclined surface that spreads downstream in the suction direction.   6. The image according to claim 1, wherein side suction ports that open toward a droplet discharge direction are arranged on both sides of the recording head in a direction intersecting a medium conveyance direction. Forming equipment.   A side guide portion is provided outside the side suction port and projecting to the opposite side of the recording head from the recording surface of the recording medium and guiding the air flow generated by suction to the side suction port. The image forming apparatus according to claim 6, wherein the image forming apparatus is provided.   The image forming apparatus according to claim 1, wherein the suction amount is changed according to a gap between a nozzle surface of the recording head and the recording medium.   The image forming apparatus according to claim 1, wherein the suction amount is changed according to an environmental temperature.

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