JP2010064466A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that information showing a state in a line type head or as an exchangeable head module unit, a positional relationship of individual heads, etc., cannot be obtained. <P>SOLUTION: A head module 51 in which a plurality of heads 101 for delivering liquid droplets are arrayed is attached so as to be exchangeabe. The head module 51 is equipped with a relay substrate 108 which relays a signal from a main control part 500 of an apparatus body. The relay substrate 108 includes a head position information storing means 521 which stores position information to a reference position of the head module 51 of each head 101. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 machine, a copying apparatus, a plotter, and a complex machine of these, for example, an ink jet recording apparatus is known as an image forming apparatus of a liquid discharge recording method using a recording head for discharging ink droplets. . This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid ejection method is an apparatus that forms an image by ejecting liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only that an image having a meaning such as a character or a figure is imparted to the medium but also an image having no meaning such as a pattern is imparted to the medium (simply liquid. It also means that a droplet hits the medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials and the like are also included.

  By the way, in a line type image forming apparatus including a line type head in which nozzle rows corresponding to the full width of the conveyed paper are arranged, the line type recording head has, for example, a nozzle row in which nozzles for discharging droplets are arranged. A head array in which a plurality of short heads are arranged along the nozzle arrangement direction (referred to as a “head module”, also referred to as a multi-array head, a multi-head unit, etc.) is used. .

  When a plurality of head modules with such a configuration are used as a recording head, the mounting position accuracy of each head module, that is, the nozzle position accuracy between the plurality of heads constituting the line, is the ink droplet landing position accuracy. When the mounting position accuracy is poor, an abnormal image is generated.

  Therefore, in the same nozzle row direction as the paper width direction, the heads are arranged in advance so that the nozzle rows of the heads of adjacent head modules slightly overlap, and the image data is distributed to both head modules for the portion where the nozzle rows overlap. It is known that the positional deviation between the two becomes difficult to understand by performing a correction process such as the above.

  In addition, in order to cope with misalignment due to the configuration of the head and the head module unit (staggered arrangement, multiple lines, etc.) in the paper transport direction, an ejection timing adjustment means for adjusting the ejection timing of the head is provided for each head. In preparation for the above, it is known to make fine adjustments using the discharge timing adjusting means even with respect to a slight misalignment due to the head mounting position accuracy.

  Further, since a plurality of heads are used, if an abnormality such as non-ejection occurs in the head, it is necessary to replace the head in which the ejection failure has occurred or the head module including the head. It is known that a storage unit that stores unique information set for each head, such as a waveform, is provided, and the image forming apparatus is set based on the stored unique information when the head or the head module is replaced. .

JP 2006-27154 A JP 2007-90690 A

  However, in the conventional configuration in which a recording medium is provided in the head and the unique information of the head is held, the unique information of each head can be held, but the information indicating the state configured as a line type head cannot be held. In particular, information indicating the state of being configured as a line-type head, misalignment of each head, etc. can only be obtained after being configured as a line-type head or a replaceable head module. It is not preferable to store the information in the head. In other words, when the head module is replaced, it is unclear what the information is based on.

  As described above, conventionally, there is a problem that information indicating a state in a line type head or as a replaceable head module unit, a positional relationship between individual heads, and the like cannot be obtained.

  The present invention has been made in view of the above problems, and an object of the present invention is to eliminate the need for position adjustment of each head when replacement is performed in units of head modules.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A head module in which a plurality of heads for discharging droplets are arranged side by side is mounted so as to be replaceable,
The head module is provided with a relay board for relaying a signal from the control unit of the apparatus body,
The relay substrate includes a head position information storage unit that stores position information of each head with respect to a reference position of the head module.

  Here, the head position information storage means may be configured to store one or a plurality of position information obtained by averaging position information for each head or position information for each head.

  In addition, it may be configured to include a paper front end detection unit that detects the front end of the paper and a module position information storage unit that stores position information of the head module relative to a detection position by the paper front end detection unit.

  According to the image forming apparatus of the present invention, since the relay module of the head module has means for storing the position information of each head with respect to the reference position of the head module, position adjustment associated with head replacement is unnecessary. Thus, replacement in units of head modules becomes possible.

  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 FIGS. 1 is a schematic configuration diagram for explaining the overall configuration of the image forming apparatus, and FIG. 2 is a schematic plan explanatory diagram of the apparatus.

  This image forming apparatus is a line type image forming apparatus, and includes an apparatus main body 1, a paper feed tray 2 on which paper P is stacked and fed, a paper discharge tray 3 on which printed paper P is discharged and stacked, and paper P An image forming unit 5 including a transport unit 4 that transports the paper from the paper feed tray 2 to the paper discharge tray 3, a head module 51 that discharges and prints droplets on the paper P transported by the transport unit 4, and Ink is supplied to the cleaning device 6 that is a maintenance and recovery mechanism that performs maintenance and recovery of each recording head of the image forming unit 5 at a required timing, the conveyance guide portion 7 that opens and closes the cleaning device 6, and the head module 51 of the image forming unit 5. An ink tank unit 8 for supplying ink and a main tank unit 9 for supplying ink to the ink tank unit 8 are provided.

  The apparatus main body 1 includes front and rear side plates and stays (not shown), and the sheets P stacked on the sheet feed tray 2 are fed one by one to the transport unit 4 by the separation roller 21 and the sheet feed roller 22. Is done.

  The transport unit 4 includes a transport drive roller 41a, a transport driven roller 41b, and an endless transport belt 43 wound around these rollers 41a and 41b. A plurality of holes (not shown) are formed on the surface of the transport belt 43, and a suction fan 44 that sucks the paper P is disposed below the transport belt 43. Further, conveyance guide rollers 42a and 42b are respectively held on guides (not shown) on the conveyance driving roller 41a and conveyance driven roller 41b and are in contact with the conveyance belt 43 by their own weight.

  The conveyance belt 43 rotates around when the conveyance driving roller 41 a is rotated by a motor (not shown), and the paper P is sucked onto the conveyance belt 43 by the suction fan 44 and is conveyed by the rotation movement of the conveyance belt 43. The transport driven roller 41 b and the transport guide rollers 42 a and 42 b rotate following the transport belt 43.

  An image forming unit 5 composed of a plurality of head modules 51 for discharging droplets to be printed on the paper P is disposed above the transport unit 4 so as to be movable in the arrow A direction (and the reverse direction). The image forming unit 5 is moved to above the cleaning device 6 during the maintenance and recovery operation (during cleaning), and is returned to the position shown in FIG. 1 during image formation.

  In the image forming unit 5, head modules 51a, 51b, 51c, 51d in which a plurality of heads having two nozzle rows in which a plurality of nozzles for discharging liquid droplets are arranged in a row are arranged in a line along the paper transport direction. The base member 52 is mounted so as to be replaceable. Here, one of the two nozzle rows of the head modules 51a and 51b ejects yellow (Y) droplets and the other of the magenta (M) droplets, and the two nozzle rows of the head modules 51c and 51d. On the other hand, cyan (C) droplets are discharged, and on the other hand, black (K) droplets are discharged.

  That is, in the image forming unit 5, two head modules 51 that discharge droplets of the same color are arranged side by side in the paper transport direction, and the two head modules 51 form a nozzle row corresponding to the paper width. It has a configuration.

  On the upstream side of the image forming unit 5, an ink tank 81 of the ink tank unit 8 (only one ink tank is provided with a reference for convenience of illustration) is arranged, and each head module unit is connected via a supply tube 82. 51, and a negative pressure with respect to each head of the head module 51 is formed by a water head difference between the ink tank 81 and the head module 51. The ink tank unit 8 is arranged so as to be movable in the direction of arrow A together with the image forming unit 5. The supply tube 82 from the ink tank 81 to the head module 51 is shown connected from above the head module 51 for easy understanding. However, as will be described later, the longitudinal direction of the head module 51 (paper conveyance direction) To the end of the direction orthogonal to the direction.

  Further, the main tank unit 9 is disposed on the upstream side of the ink tank 81, and ink is supplied from the main tank 91 through the supply tube 92 to the ink tank 81.

  On the downstream side of the transport unit 4, a transport guide portion 7 that discharges the paper P to the paper discharge tray 3 is provided. The paper P guided and conveyed by the conveyance guide unit 7 is discharged to the paper discharge tray 3. The paper discharge tray 3 includes a pair of side fences 31 that regulate the width direction of the paper P and an end fence 32 that regulates the front end of the paper P.

  The maintenance / recovery mechanism (cleaning device) 6 includes four rows of cleaning means 61 a to 61 d corresponding to each head module 51 of the image forming unit 5, and one cleaning means 61 is provided for each head of the head module 51. The corresponding cap member 62 and a wiper member (not shown) are configured. The cap member 62 of each cleaning means 61 can be moved up and down independently for each row. Further, below the cleaning unit 61, suction pumps 63a to 63d for sucking ink from the nozzles with the cap member 62 capping the nozzle surface of the head module 51 are arranged.

  Further, in this image forming apparatus, after the printing is finished, when the nozzle surface of each head of the head module 51 that discharges droplets is capped by the cleaning unit 61, or ink is sucked from the nozzle, or the head module 51 When the ink adhering to the nozzle surface of each head is cleaned with a wiping member, as shown in FIG. 1, after the printing is stopped, the entire transport unit 4 rotates in the arrow B direction with the transport driven roller 41b as a fulcrum, A space for moving the image forming unit 5 is ensured by making the space between the image forming unit 5 larger than that at the time of image formation. At this time, the conveyance guide portion 7 disposed on the upper portion of the cleaning device 6 is also rotated upward in the direction of the arrow C at the fulcrum 71, and the upper portion of the cleaning device 6 is opened.

  Then, after the transport unit 4 and the transport guide portion 7 are released (released), the image forming unit 5 moves in the paper passing direction (in the direction of arrow A), stops above the cleaning device 6, and the cleaning unit 61. Rises and shifts to a cleaning operation (maintenance recovery operation) of each head module 51.

  Next, details of the head module will be described with reference to FIGS. 3 is a perspective explanatory view of the head module, FIG. 4 is a schematic side view of the head module, and FIG. 5 is a bottom explanatory view of one head of the head module.

  One head module 51 arranges a plurality of heads 101 (in this example, five examples) for ejecting droplets in a row on a base member 102 and arranges the heads on the plurality of heads 101. A branch member (common flow channel member) 104 that is an ink supply member that forms a common flow path that distributes and supplies ink to the plurality of heads 101 along the direction is disposed, and between the branch member 104 and the base member 102. The head 101 is urged toward the branching member 104 side by the leaf spring member 103, and is integrated. The branch member 104 is provided with an ink supply port 105A and an air vent hole 105B.

  As shown in FIG. 5, for example, the head 101 has a nozzle surface 204 having nozzle rows 201A and 201B in which a plurality of nozzles 201 for discharging droplets are arranged. The head 101 is not limited to this, and a head having three or more nozzle rows can also be used.

  In addition, the relay board 108 is held above the branch member 104 by support members 106 and 106 attached to both ends of the branch member 104. The relay substrate 108 and each head 101 are electrically connected via a connector 110 and a cable 111. As will be described later, a head position information storage unit 521 that stores information (head position information) related to the head position with respect to the reference position of the head module 51 is mounted on the relay substrate 108.

Next, a control system of this image forming apparatus will be described with reference to a block diagram shown in FIG.
A main control unit 500 is disposed on the apparatus body 1 side, and the main control unit 50 and the relay board 108 of the head module 51 are connected via a flexible cable 501.

  The main control unit 500 includes a head controller 511 that controls the heads 101 of the head modules 51a to 51d of the image forming unit 5, an image data storage unit 512 that stores image data provided from an external information processing apparatus, and the like. Head drive signal generation means 513a to 513d for each head module that generates a head drive signal for driving each head 101 of each head module 51a to 51d, and a head necessary for drive control of the head 101 other than the head drive signal And head control signal generation means 522 for generating a control signal (for example, a clock signal, a latch signal, a droplet control signal, etc.). Each head drive signal generation means 513 is composed of head drive signal generation means 514a to 514e for each head 101a to 101e. Similarly, the head control signal generation unit 522 includes head control signal generation units 523a to 523e that generate head control signals for the heads 101a to 101e.

  Each relay board 108 of the head modules 51 a to 51 d includes a head position information storage unit 521 that stores position information of each head 101 of the head module 51 with respect to the reference position of the head module 51.

  Here, as shown in FIG. 7, for example, the position of the first nozzle row (nozzle row upstream of the paper conveyance direction) 201A of the head 101 with the end of the module base 102 of the head module 51 in the paper conveyance direction as a reference position ( The distance L) is stored in the head position information storage unit 521 as head position information.

Next, adjustment of the droplet discharge timing by the main control unit 500 will be described with reference to FIGS. 8 is an explanatory diagram showing an outline of the configuration of the portion related to the adjustment of the droplet discharge timing, and FIG. 9 is a functional block explanatory diagram of the portion related to the adjustment of the droplet discharge timing.
First, as shown in FIG. 8, the plurality of head modules 51a to 51d are arranged side by side in the paper feeding direction. The drive roller 41 a that drives the transport belt 43 is provided with a rotary encoder 46 that detects the amount of movement of the paper P. In addition, a paper leading edge detection sensor 47 that detects the leading edge of the paper P is disposed upstream of the plurality of head modules 51a to 51d.

  As shown in FIG. 9, the main control unit 500 includes a droplet discharge control unit 601 that controls the droplet discharge from each head 101 of the head modules 51a to 51d, and a head module position information storage that stores head module position information. And a droplet discharge timing adjusting unit 603 for adjusting (setting) the droplet discharge timing based on the head module position information of the head module position information storage unit 602 and the head position information of the head position information storage unit 521. ing.

  The module position information storage unit 602 uses the leading edge detection position by the sheet leading edge detection sensor 47 as a reference position, and the position of each of the head modules 51a to 51d with respect to this reference position (the distance to the upstream end in the sheet conveyance direction described in FIG. 7). ) Ya1, yb1, yc1, and yd1 (see FIG. 8) are stored as module position information.

  The droplet discharge control unit 601 starts the droplet discharge operation when the droplet discharge timing of each head module 51 adjusted by the droplet discharge timing adjustment unit 603 is reached from the time when the sheet leading edge detection unit 47 detects the leading edge of the sheet P. . Thereby, the landing positions of the droplets discharged from the head 101 of each head module 51 are matched on the paper P.

  The position information includes distance information with respect to the reference position, time information calculated from the distance information with respect to the reference position and the paper conveyance speed, or time information calculated from the distance information with respect to the reference position and the paper conveyance speed, and the frequency of the internal clock. Any of the count information calculated from

  Further, since the head 101 is positioned and attached to the module base member 102 with high accuracy, and the module base member 102 is attached to the line base member 52 with reference to the attachment reference hole 102a, from the sheet leading edge detection position to the reference hole 102a. Can be processed as module position information, and the distance from the reference hole 102a to the nozzle row 201A can be processed as head position information.

Next, another example of adjusting the droplet discharge timing by the main controller 500 will be described with reference to FIG. FIG. 10 is a functional block explanatory diagram of a portion related to adjustment of droplet discharge timing.
Here, there is provided a head position information averaging means 604 for averaging the position information of each head 101 in one head module 51 based on the head position information from the head position information storage means 521, and a droplet discharge timing adjusting means. Reference numeral 603 denotes an adjustment of ejection timing based on individual head position information from the head position information storage unit 521 or a head in the head module 51 from the head position information averaging unit 604 according to the ejection timing adjustment method selection signal. The ejection timing is adjusted based on the average value of the position information.

  In this case, the head position information averaging means 604 can be mounted on the relay board 108 of the head module 51 together with the head position information storage means 521 as shown in FIG. 11, for example. Head position information storage means storing averaged position information obtained by averaging the position information of each head may be mounted on the relay substrate. Further, the discharge timing adjusting means described above can also be mounted on the relay substrate 108.

  The position information includes distance information with respect to the reference position, time information calculated from the distance information with respect to the reference position and the paper conveyance speed, or time information calculated from the distance information with respect to the reference position and the paper conveyance speed, and the frequency of the internal clock. Any of the count information calculated from

  Further, since the head 101 is positioned and attached to the module base member 102 with high accuracy, and the module base member 102 is attached to the line base member 52 with reference to the attachment reference hole 102a, from the sheet leading edge detection position to the reference hole 102a. Can be processed as module position information, and the distance from the reference hole 102a to the nozzle row 201A can be processed as head position information.

1 is a schematic side view illustrating an overall configuration of an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. It is a perspective explanatory view of a head module. It is side surface explanatory drawing of the head module. It is bottom surface explanatory drawing of one head of the head module. FIG. 2 is an explanatory block diagram for explaining a control system of the image forming apparatus. It is explanatory drawing with which it uses for description of head position information in a head module. It is explanatory drawing with which it uses for description of the part concerning adjustment of droplet discharge timing. It is a functional block explanatory drawing of the part similarly related to adjustment of droplet discharge timing. It is a functional block explanatory view of another example of the portion related to the adjustment of the droplet discharge timing. It is side surface explanatory drawing which shows the other example of the head module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 4 ... Conveyance unit (conveyance part)
5. Image forming unit 6. Cleaning device (maintenance and recovery mechanism)
DESCRIPTION OF SYMBOLS 7 ... Conveyance guide part 8 ... Ink tank unit 9 ... Main tank unit 51 ... Head module 52 ... Line head base member 61 ... Cleaning means 101 ... Head 108 ... Relay board 521 ... Head position information storage means 604 ... Averaging means

Claims (3)

A head module in which a plurality of heads for discharging droplets are arranged side by side is mounted so as to be replaceable,
The head module is provided with a relay board for relaying a signal from the control unit of the apparatus body,
An image forming apparatus comprising: a head position information storage unit that stores position information of each head relative to a reference position of the head module on the relay substrate.   The image forming apparatus according to claim 1, wherein the head position information storage unit stores position information for each head or one or a plurality of position information obtained by averaging the position information of each head.   An image forming apparatus comprising: a sheet leading edge detecting unit that detects a sheet leading edge; and a module position information storing unit that stores position information of the head module with respect to a detection position by the sheet leading edge detecting unit.

Images