JP5822104B2 - Droplet discharge apparatus, image forming apparatus, and landing position adjustment method - Google Patents

Description

  The present invention relates to a droplet discharge device, an image forming apparatus, and a landing position adjusting method.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, a plotter, and a complex machine of these, for example, an ink jet is used as an image forming apparatus of a droplet discharge recording system using a droplet discharge head (liquid discharge head) that discharges ink droplets. Recording devices and the like are known.

  The attachment position of the droplet discharge head to the apparatus has a great influence on the discharge position accuracy, and thus the droplet discharge head needs to be positioned with respect to the apparatus.

  In Patent Document 1, a direction perpendicular to an image forming surface of a recording material (hereinafter referred to as a Z-axis direction), a sub-scanning direction (hereinafter referred to as a Y-axis direction) that is a recording material conveyance direction, and a width direction of the recording material An ink jet recording apparatus that positions a droplet discharge head in a main scanning direction (hereinafter referred to as an X-axis direction) is described. The ink jet recording apparatus described in Patent Document 1 includes a box-type head holder that holds a droplet discharge head, and an X for positioning the droplet discharge head in the X-axis direction in the head holder. An axis reference surface, a Y-axis reference surface for positioning the droplet discharge head in the Y-axis direction, and a Z-axis reference surface for positioning the droplet discharge head in the Z-axis direction are provided. The droplet discharge head has an X-axis positioning projection that contacts the X-axis reference surface, a Y-axis positioning projection that contacts the Y-axis reference surface, and a Z-axis positioning surface that contacts the Z-axis reference surface. doing. A first urging means is provided on a surface of the head holder facing the X-axis reference surface, and a second urging means is provided on a surface of the head holder facing the Y-axis reference surface. It has been. The lid that opens and closes the inside of the head holder and faces the Z-axis reference surface of the head holder has third urging means. The droplet discharge head inserted into the head holder is urged toward the X-axis reference surface by the first urging means, so that the X-axis positioning projection comes into contact with the X-axis reference surface, and the liquid Positioning and fixing of the droplet discharge head in the X-axis direction is performed. Further, by urging the droplet discharge head toward the Y-axis positioning reference surface by the second urging means, the Y-axis positioning protrusion comes into contact with the Y-axis reference surface, and the Y-axis direction of the droplet discharge head The positioning is fixed. Further, by urging the droplet discharge head toward the Z-axis positioning reference surface by the third urging means, the Z-axis positioning surface comes into contact with the Z-axis reference surface, and the Z-axis direction of the droplet discharge head The positioning is fixed.

  However, according to Patent Document 1, as described above, the first and second urging means press the positioning protrusions provided on the droplet discharge head against the positioning reference surface of the head holder. ing. Therefore, it is necessary to insert the droplet discharge head so as to be pushed between the first and second urging means and each positioning surface. For this reason, when replacing the droplet discharge head, the nozzle surface of the droplet discharge head may be caught by the first urging means or the second urging means, and the nozzle surface may be damaged. Therefore, in order to insert the nozzle surface without damaging it, it is necessary for a skilled person to perform the work carefully. Therefore, there is a problem that the replacement operation of the droplet discharge head cannot be performed easily and quickly.

  In view of the above problems, the present applicant has proposed the following positioning mechanism in Japanese Patent Application No. 2009-16331 (hereinafter referred to as the prior application). In other words, the positioning mechanism of the prior application has three positioning members that protrude from the surface of the support plate for supporting the droplet discharge head, which faces the droplet discharge head, and whose tip is spherical. In addition, there are three positioned parts on the surface of the positioning plate that is provided in the droplet discharge head and that faces the support plate. The first positioned portion provided on the positioning plate is a conical recess, the second positioned portion is a V-shaped groove extending in parallel with the Y-axis direction, and the third positioned portion Is a flat portion parallel to the surface facing the support plate. The first positioned portion is provided at one end in the Y-axis direction, and the second positioned portion is provided at the other end in the Y-axis direction. The line connecting the top of the first positioned portion of the conical recess and the top of the second positioned portion that is a V-shaped groove is parallel to the nozzle row extending in the Y-axis direction. ing. Further, the third positioned portion is such that a line segment connecting the center of the third positioned portion, the center of the second positioned portion, and the first positioned portion is an isosceles triangle. In the position.

  In the positioning mechanism of the prior application, when the droplet discharge head is supported by the support plate via the positioning plate, one of the positioning members having a spherical tip is connected to the first positioned portion of the conical recess. Engage. Further, another positioning member engages with the second positioned portion of the V-shaped groove, and yet another positioning member contacts the third positioned portion of the flat portion. Thereby, the droplet discharge head is positioned in the Y-axis direction (sub-scanning direction), the X-axis direction (main scanning direction), and the Z-axis direction (perpendicular to the image forming surface of the recording material). More specifically, one of the positioning members engages with the first positioned portion of the conical recess, thereby positioning the droplet discharge head in the Y-axis direction. Further, when one of the positioning members is engaged with the first positioned portion of the conical recess, and the other positioning member is engaged with the second positioned portion of the V-shaped groove portion, Directional positioning is made. In addition to these, another positioning member comes into contact with the third positioned portion of the flat portion, so that the droplet discharge head is supported by the support plate at three points, and positioning in the Z-axis direction is performed. It is.

  Thus, in the prior application, positioning of the droplet discharge head in the X-axis direction and positioning in the Y-axis direction can be performed without using the first biasing means and the second biasing means. Therefore, by attaching the droplet discharge head from the Z-axis direction, the droplet discharge head can be attached without the urging means being caught on the nozzle surface. As a result, the operation of replacing the droplet discharge head can be performed easily and quickly.

  However, in the prior application, if the accuracy of the protruding amount of the positioning member provided on the support plate from the support plate is poor, the droplet discharge head is positioned and fixed while being tilted around the X axis, or Y The positioning is fixed while tilting around the axis. As a result, the landing accuracy is deteriorated. For this reason, it is necessary to manufacture the protrusion amount from the support plate with high accuracy, and there is a problem that the cost is increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a droplet capable of easily and quickly exchanging the droplet discharge head and reducing the cost of the apparatus. To provide an ejection device, an image forming apparatus, and a landing position adjustment method.

In order to achieve the above object, a first aspect of the present invention provides a droplet discharge apparatus including a droplet discharge head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged in a predetermined direction. And a positioning plate provided on the droplet discharge head and having a facing surface facing the support plate, and the droplet discharge head is positioned on the support plate via the positioning plate. The support plate includes a first positioning member, a second positioning member, and a third positioning member that protrude from the support plate, and the positioning plate includes a conical recess on the opposing surface, A first positioned portion that engages with the first positioning member and a groove portion that extends toward the first positioned portion, and that engages with the second positioning member. A positioning portion, and a third positioning portion that is in contact with the third positioning member, and includes a first positioning member, a second positioning member, and a third positioning member that is in contact with the third positioning member. Of the third positioning member, a protrusion amount adjusting means for adjusting a protrusion amount of at least two positioning members from the support plate is provided, and the protrusion amount adjusting means is attached to the support plate and positioned on the support plate. The projection amount adjusting means can be accessed from the surface opposite to the surface supporting the plate.
According to a second aspect of the present invention, in the droplet discharge device according to the first aspect, at least the contact between the first positioning member and the first positioned member and the second positioning member and the second positioned portion. A droplet discharge device characterized in that tip shapes of the first positioning member and the second positioning member are formed so that the contact is a line contact or a point contact.
According to a third aspect of the present invention, in the droplet discharge device of the first or second aspect, each positioning member is held in a recess formed in the support plate, and the protrusion amount adjusting means is positioned on the support plate. An adjustment member is provided on the support plate so as to be movable in a direction perpendicular to the surface supporting the plate, and adjusts the protruding amount of the positioning member by protruding from the concave surface of the concave portion.
According to a fourth aspect of the present invention, in the droplet discharge device according to the third aspect, each positioning member is a sphere, and the support plate is formed with three recesses for inserting the different spheres. The protrusion amount adjusting means is attached to the support plate so as to be opposed to the recess, has a hole portion for protruding a part of the sphere, and holds the sphere in the recess. The adjustment member is an adjustment screw that pushes the sphere into the plate spring member side.
According to a fifth aspect of the present invention, in the droplet discharge device according to the fourth aspect, the adjustment screw of the protrusion amount adjusting means can be accessed from the nozzle surface side where the nozzle row of the droplet discharge head is formed. It is characterized by comprising.
According to a sixth aspect of the invention, in the droplet discharge device of the fourth or fifth aspect, a differential screw is used as the adjustment screw of the protrusion amount adjusting means.
The invention of claim 7 is provided with a droplet discharge means for discharging droplets by discharging droplets by a droplet discharge means record medium, an image forming apparatus that forms an image on a recording medium, The droplet discharge device according to any one of claims 1 to 6 is used as the droplet discharge means.
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the image forming apparatus includes an image reading unit that reads an image formed on the recording medium, forms a test image on the recording medium, and is formed on the recording medium. The test image is read by the image reading means, the deviation of the landing position of the droplet on the recording medium is detected, and each adjusting means can be adjusted based on the detection result. To do.
According to a ninth aspect of the invention, there is provided a droplet discharge head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged in a predetermined direction, a support plate for supporting the droplet discharge head, and the droplet discharge head. A positioning plate having a facing surface facing the support plate, and the droplet discharge head is positioned on the support plate via the positioning plate, and the support plate protrudes from the support plate A first positioning member having a first positioning member, a second positioning member, and a third positioning member, wherein the positioning plate is formed of a conical recess on the facing surface and engages with the first positioning member. And a second positioning portion that engages with the second positioning member, and a surface of the support plate that faces each other. In the method for adjusting a landing position in a droplet discharge device that includes a parallel planar portion and has a third positioned portion that contacts the third positioning member, the droplet discharge device includes the first positioning member and the second positioning member. Of the positioning member and the third positioning member, a protrusion amount adjusting means for adjusting a protrusion amount of at least two positioning members from the support plate is provided, the protrusion amount adjusting means being attached to the support plate, and supporting surfaces of the positioning plate in the plate and from the surface opposite is configured to be accessible to the projection amount adjusting means, forming a test image on a record medium, the test image formed on the recording medium Based on the step of reading by the image reading means and the image read by the image reading means, a process for grasping the attachment / detachment position deviation of the droplets on the recording medium. If, on the basis of the landing position shift, which is grasped, and is characterized in that a step of adjusting the projection amount from the support plate of the positioning member with the projection amount adjusting means.

According to the present invention, even if the droplet discharge head is positioned and fixed while being tilted around the X axis or positioned and fixed while being tilted around the Y axis, the protrusion amount adjusting means supports each positioning member. The inclination can be adjusted by adjusting the amount of protrusion from the plate. As a result, the landing accuracy of the droplet discharge head can be obtained without increasing the accuracy of the protrusion amount of the positioning member provided on the support plate from the support plate as in the prior application, compared to the previous application. The apparatus can be made inexpensive.
Further, similarly to the previous application, the droplet ejection head can be positioned in the X-axis direction and the Y-axis direction without using the first urging unit and the second urging unit. Therefore, by attaching the droplet discharge head from the Z-axis direction, the droplet discharge head can be attached without the urging means being caught on the nozzle surface. As a result, the operation of replacing the droplet discharge head can be performed easily and quickly.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is a plan view showing an image forming unit of the copier from information. FIG. 2 is a perspective view illustrating a configuration of a droplet discharge device of the copier. The perspective view which shows the structure of the droplet discharge head of the droplet discharge apparatus. The perspective view which shows the structure of the positioning plate of the droplet discharge apparatus. (A) is a perspective view which shows a positioning plate and a droplet discharge head, (b) is the top view. The perspective view which shows the structure of the support plate of the droplet discharge apparatus. (A) is a perspective view which shows the structure of a thin plate, (b) is AA sectional drawing of FIG. The schematic block diagram of a differential screw. The schematic diagram which shows a mode that the droplet discharge head was fixed to the support plate. The figure explaining positioning of a droplet discharge head. Flow chart for landing position adjustment. FIG. 4 is a diagram illustrating an example of a test image on which recording paper is formed. FIG. 3 is a schematic configuration diagram illustrating another image forming apparatus. The block diagram which shows the structure of a positioning plate joining apparatus. The figure which shows the coordinate of an ideal position, and the center coordinate of a nozzle alignment mark. The perspective view which shows the mode of imaging of the nozzle alignment mark by the CCD camera of a positioning plate joining apparatus. The perspective view which shows the structure of a reference | standard chart. 1 is a schematic configuration diagram of a line type image forming apparatus. The perspective view which shows the structure of the support plate of the droplet discharge apparatus mounted in the same line type image forming apparatus. FIG. 3 is a perspective view showing a configuration of a droplet discharge device mounted on the line type image forming apparatus. FIG. 6 is a plan view showing another configuration of a droplet discharge device mounted on the line type image forming apparatus.

Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described with reference to the accompanying drawings.
As an image forming apparatus of a printer, a facsimile machine, a copying machine, or a composite machine of these, for example, a liquid ejection apparatus including a recording head composed of a liquid ejection head that ejects liquid droplets of a recording liquid is used. Although it is also referred to as “paper”, the material is not limited, and a recording medium (hereinafter referred to as “ink”) is conveyed while conveying a recording medium, a recording medium, a transfer material, recording paper, and the like. Is also attached to a sheet to form an image (recording, printing, printing, and printing are also used synonymously).

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The term “not only” means to give an image having a meaning such as a character or a figure to the medium but also to give an image having no meaning such as a pattern to the medium. Further, the liquid is not limited to the recording liquid and ink, and is not particularly limited as long as it is a liquid capable of forming an image. The droplet discharge device means a device that discharges droplets from a droplet discharge head.

Hereinafter, an ink jet copying machine will be described as an embodiment of an image forming apparatus to which the present invention is applied.
FIG. 1 is a schematic configuration diagram showing a copying machine according to the present embodiment. In FIG. 1, the copying machine 1 has an image reading unit (scanner unit) 11 serving as an image reading unit for reading an image of a document at the upper part of the casing. The image reading unit 11 reads an image of a document placed on the contact glass 12 while moving an optical system 15 including an illumination light source 13 and a mirror 14 and an optical system 18 including mirrors 16 and 17. For light scanning. The original reflected light obtained by this optical scanning is read as an image signal by the image reading element 20 disposed behind the lens 19, and the read image signal is digitized and then subjected to image processing. Then, image formation is performed on the recording paper 5 based on the image information of the image processing.

  The copying machine forms an image based on the original image read by the image reading unit 11, as well as an information processing device such as an external personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera. An image can be formed based on the image information sent from.

  A paper feed unit 4 is provided near the bottom of the housing, and the recording paper 5 is taken out one by one from the paper bundle contained in the paper feed cassette 41 and sent out toward the paper feed path. The paper feed cassette 41 can be inserted and removed from the front side of the housing. A paper feed roller 42 and a friction pad 43 for separating and feeding out the uppermost recording paper 5 in the internal paper bundle are provided. Further, the receiving roller 48 for receiving the recording paper 5 fed into the housing from the duplex unit 10 that is optionally mounted on the lower side of the housing, and the recording paper 5 is conveyed toward the image forming unit 2 described later. A conveyance roller pair 49 is also provided. A member that conveys the recording paper 5 toward the image forming unit 2 to be described later, such as a paper feed roller 42, is rotationally driven by a paper feed motor (drive means) 45 including an HB stepping motor via a paper feed clutch (not shown). The

  The recording paper 5 fed into the paper feed path eventually enters a scanning conveyance position formed between the sub-scanning conveyance unit 3 and the image forming unit 2. At this scanning conveyance position, the image forming unit 2 forms (records) a required image by ejecting droplets toward the recording paper 5.

  As shown in FIG. 2, the image forming unit 2 holds the carriage 23 by a guide rod 21 and a guide stay (not shown) so as to be movable in the main scanning direction. The carriage 23 is connected to a stretched portion of a timing belt 29 spanned between a driving pulley 28A that is rotationally driven by a main scanning motor 27 and a driven pulley 28B, and main scanning is performed as the belt moves. It can be moved in the direction.

  On the carriage 23, droplet discharge heads 241y, 241m, 241c, and 241k for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K) are integrated. The droplet discharge device 24, an electric circuit board (not shown) that supplies a drive signal to the head, and a sub tank 25 that stores ink to be supplied to the head. The droplet discharge device 24 is arranged with a nozzle row composed of a plurality of nozzles arranged in the sub-scanning direction orthogonal to the main scanning direction and the ink droplet discharge direction facing downward. Further, the droplet discharge device 24 is configured by attaching four color droplet discharge heads 241y to 241k each having two nozzle rows to one support plate.

  A maintenance / recovery device 121 for keeping the state of the nozzles of the droplet discharge head 241 constant is disposed in a non-printing area on one side of the carriage 23 in the scanning direction. The maintenance / recovery device 121 includes four moisturizing caps 122k, 122c, 122m, and 122y for individually capping the nozzle surfaces of the four droplet discharge heads (241y to 241k). Further, a wiper blade 124 for wiping the nozzle surface, an empty discharge receiving member 125 for discharging liquid droplets that do not contribute to recording (image formation) (empty discharge), and the like are also provided.

  In the non-printing area on the other side in the scanning direction of the carriage 23, the idle ejection receiving member 126 for ejecting droplets that do not contribute to image formation (empty ejection) from the four droplet ejection heads (241y to 241k). Is arranged. The empty discharge receiving member 126 is provided with openings 127y, 127m, 127c, and 127k that individually correspond to the droplet discharge heads 241y, 241m, 241c, and 241k, respectively.

  As shown in FIG. 1, the corresponding color ink is supplied from the sub tank 25 mounted on the carriage 23 to the droplet discharge heads (241 y to 241 k) of each color. The sub tank 25 can store the inks y, m, c, and k in an independent state. Therefore, in this printer, the carriage 23 on which the sub tank 25 serving as the first storage tank is mounted by the guide rod 21, the guide stay (not shown), the driving pulley 28A, the driven pulley 28B, the timing belt 29, and the like shown in FIG. Main scanning moving means for moving in the scanning direction is configured.

  In FIG. 1 described above, ink cartridges 26y, 26m, 26c, and 26k that store y, m, c, and k inks are detachably mounted above the paper feed cassette 41. The y, m, c, and k inks stored in these ink cartridges as the second storage tank are replenished into the sub tank 25 on the carriage 23 as necessary.

  The sub-scanning conveyance unit 3 that forms a scanning conveyance position with the image forming unit 2 stretches an endless belt-like conveyance belt 31 by a driven roller 33 and a rotationally driven drive roller 32 in the drawing. Move endlessly counterclockwise. A charging roller 34 to which an AC voltage output from a high voltage power source (not shown) is applied is in contact with the front surface of the conveyance belt 31, and the front surface is charged by the discharge from the charging roller 34. By this charging, the recording paper 5 that has entered the scanning conveyance position from within the paper feed path is attracted to the front surface of the conveyance belt 31.

  The recording paper 5 fed from the end of the paper feed path toward the scanning conveyance position enters a receiving nip formed by the conveyance belt 31 and a pressing roller 36 that contacts the front surface of the recording belt 5. Then, after being electrostatically attracted to the front surface of the conveyance belt 31 charged by the charging roller 34, the conveyance belt 31 is conveyed in the sub-scanning direction along with the endless movement of the conveyance belt 31.

  At the scanning conveyance position, the plate-shaped scanning guide member 35 is in contact with the upper stretched portion of the conveyance belt 31 from the back side. Thereby, the undulation of the conveyance belt 31 at the scanning conveyance position is suppressed.

  The transport belt 31 includes a surface layer that becomes a sheet adsorbing surface formed of a pure resin material that does not contain a resistance control agent, for example, ETFE pure material, and a back layer (medium resistance) that is made of the same material as the surface layer and is subjected to resistance control by carbon. However, the present invention is not limited to this, and a one-layer structure or a structure having three or more layers may be used.

  The recording paper 5 that has passed through the scanning conveyance position with the endless movement of the conveyance belt 31 is separated from the belt front surface by the separation claw 37. The recording paper 5 separated from the conveyance belt 31 is transferred to the post-recording conveyance unit 7. The post-recording conveyance unit 7 forms a post-recording conveyance path 70 between an upper guide member 74 facing the image recording surface of the recording paper 5 and a lower guide member 73 facing the back surface of the recording paper 5. . The upper guide member 74 holds a plurality of spurs 72 arranged in a lattice pattern in the conveyance direction of the recording paper 5 and in a direction perpendicular thereto. Further, the lower guide member 73 rotatably holds a plurality of conveyance rollers 71 arranged in a lattice pattern in the conveyance direction of the recording paper 5 and the direction orthogonal thereto.

  The plurality of transport rollers 71 are driven to rotate by drive transmission from a driving means (not shown). Further, the plurality of spurs 72 have a plurality of sharp protrusions arranged along the rotation trajectory, and these protrusions are brought into contact with the conveyance roller 71 corresponding to itself among the plurality of conveyance rollers 71. .

  The recording paper 5 delivered from the sub-scanning conveying unit 3 to the post-recording conveying unit 7 is sandwiched between the spur 72 and the conveying roller 71 in the post-recording conveying path 70, while the conveying roller 71 rotates. Are transported horizontally. At this time, a spur 72 having its own protrusion point-contacted with the image recording surface of the recording paper 5 presses the recording paper 5 toward the lower guide member 73. As a result, ink smear and image disturbance due to contact between the ink which is not dry on the image recording surface of the recording paper 5 and the upper guide member 74 are avoided.

  A first switching claw 60 that can swing around a swing shaft is disposed on the side of the post-recording transport unit 7. The first switching claw 60 moves the subsequent transport direction of the recording paper 5 sent out from the post-recording transport unit 7 to the direction toward the reverse paper discharge unit 76 and the optional duplex unit 10 by the swing position. Switching is made between the heading direction and the straight paper discharge path.

  When the first switching claw 60 sets the transport direction to the duplex unit 10, the recording paper 5 sent out from the post-recording transport path 7 is fed into the descending and reversing unit 90 of the duplex unit 10. Then, the sheet is conveyed while being inverted up and down by a plurality of conveyance roller pairs 91 provided in the descending and reversing conveyance path 90 c of the descending and reversing unit 90, and enters the horizontal conveyance path 90 a of the duplex unit 10. The horizontal conveyance path 90 a extends in the horizontal direction, and conveys the received recording paper 5 in the horizontal direction while being sandwiched between the rollers of the conveyance roller pair 93.

  The duplex unit 10 has a switchback conveyance path 90b immediately below the horizontal conveyance path 90a. The recording paper 5 sent out from the horizontal conveyance path 90a enters the switchback conveyance path 90b while coming into contact with the second switching claw 96 that can be driven to swing and being turned upside down again. And it is conveyed in the reverse direction to the horizontal conveyance path 90a, being pinched | interposed between the rollers of the several conveyance roller pair 95 provided in the switchback conveyance path 90b.

  When the trailing edge of the recording paper 5 enters the switchback conveyance path 90b, the duplex unit 10 starts to reverse the rotation driving direction of the conveyance roller pair 95 in the switchback conveyance path 90b. Further, the second switching claw 96 is rotated by a predetermined angle at substantially the same timing. Then, the recording paper 5 switches back in the switchback conveyance path 90b with the rear end side so far leading, and enters the duplex discharge path. Then, after being transferred from the double-sided conveyance path to the paper feeding unit 4 of the copying machine main body, it is supplied again to the scanning conveyance position between the image forming unit 2 and the sub-scanning conveyance unit 3 while being further inverted upside down. .

  The recording paper 5 re-supplied to the scanning conveyance position has the back surface opposite to the previous image forming surface facing the image forming unit 2. As the image is conveyed in the sub-scanning direction at the scanning conveyance position, an image is also recorded on the back surface of the image and then transferred to the post-recording conveyance unit 7 again.

  When the conveyance direction is set to the direction toward the reverse paper discharge unit 76 by the first switching claw 60 disposed on the side of the post-recording conveyance unit 7, the recording paper fed out from the post-recording conveyance path 70 5 is sent to the reverse paper discharge unit 76. Then, in the reverse discharge path 81 of the reverse discharge section 76, the paper is sandwiched between the rollers of the reverse roller pair 77 and between the rollers of the paper discharge roller pair 78, and discharged toward the outside while being turned upside down. The The discharged recording paper 5 is stacked on a stack unit 89 provided on the upper surface of the casing of the print unit including the image forming unit 2 and the like.

  In the case where the conveyance direction is set to the straight discharge path by the first switching claw 60, the recording paper 5 sent out from the conveyance path 7 after recording is conveyed straight as it is, and in the figure of the housing. Paper is discharged toward the left side. Then, they are stacked on a paper discharge tray 88 provided on the side surface of the housing.

FIG. 3 is a perspective view showing the configuration of the droplet discharge device 24.
As shown in the figure, the droplet discharge device 24 includes a support plate 242 that supports the droplet discharge heads 241Y to 241K, and a positioning plate that is attached to each droplet discharge head 241 and positions the droplet discharge head 241. 243Y, 243M, 243C, 243K. The plurality of droplet discharge heads 241Y to 241K are arranged in the main scanning direction (hereinafter referred to as the X-axis direction) that is the carriage movement direction indicated by the arrow in the drawing, and each positioning plate 243Y to 243K has two steps. Each droplet discharge head 241 </ b> Y to 241 </ b> K is fixed to the support plate 242 by being fixed to the support plate 242 by the screws 244. Each of the droplet discharge heads 241Y to 241K is configured to be detachable with respect to the support plate 242, and when replacing the droplet discharge head due to the life or failure of the droplet discharge head, only two stages in which only the failed droplet discharge head is fixed. By removing the attached screw 244, it can be replaced with a new droplet discharge head.

FIG. 4 is a perspective view showing the configuration of the K-color droplet discharge head 241K.
As shown in the figure, the droplet discharge head 241K includes a head portion 258K and a frame portion 255K. On the nozzle surface 254K of the head portion 258K, a nozzle row 251K having a plurality of nozzles 251aK formed at equal intervals in the sub-scanning direction (hereinafter referred to as the Y-axis direction) which is the recording paper 5 conveyance direction is arranged in the X-axis direction. Two rows are arranged. In addition, nozzle alignment marks 252K and 253K for use in nozzle position adjustment, which will be described later, are provided at both ends in the Y-axis direction of the nozzle surface 254K of the droplet discharge head 241K in which the nozzle row 251K is formed. The number of nozzle rows 251K in the droplet discharge head 241K may be appropriately determined according to the model of the ink jet recording apparatus to be mounted, that is, the performance. Further, both ends of the frame portion 255K in the Y-axis direction have portions protruding in the Y-axis direction, and a projection portion 256K that engages with an engaging portion (not shown) of a positioning plate, which will be described later, and the sub tank 25 are attached. A mounting hole 257K is formed. The other droplet discharge heads 241Y, 241M, and 241C have the same configuration.

FIG. 5 is a perspective view showing the configuration of the K-color positioning plate 243K. FIG. 6A is a perspective view showing the positioning plate 243K and the droplet discharge head 241K, and FIG. 6B is a plan view.
As shown in FIGS. 5 and 6, the positioning plate 243K has a shape in which the center is hollowed so that the droplet discharge head 241K is fitted in the center, and is positioned accurately by nozzle position adjustment described later. Thus, it is joined to the droplet discharge head 241K by an adhesive or the like. Further, conical recesses 243aK serving as a first positioned portion are provided at four corners of the facing surface 243dK of the positioning plate 243K facing the support plate 242. Further, a V-shaped groove portion 243bK having a V-shaped cross section extending in parallel with the Y-axis direction as a second positioned portion is provided at the end of the facing surface 243dK opposite to the side where the conical recess 243aK is provided. Yes. In addition, a flat portion 243cK as a third positioned portion is provided in the center in the Y-axis direction at the end on the side where the conical recess 243aK and the V-shaped groove 243bK are provided and the end opposite to the X-axis. ing.

  As indicated by the dotted line in FIG. 6B, the apex of the conical recess 243aK is arranged on the extended line of the ridgeline of the V-shaped groove 243bK. In addition, the extended line connecting the center of the dotted V-shaped groove 243bK and the center of the conical recess in the drawing is arranged so as to be parallel to the nozzle row 251K of the droplet discharge head 241K. The positioning plates 243Y, 243M, and 243C have the same configuration.

FIG. 7 is a perspective view showing the configuration of the support plate 242.
As shown in the figure, the support plate 242 has four insertion holes 261Y, 261M, 261C, and 261K into which the droplet discharge heads 241Y to 241K are inserted. In addition, three conical recesses 265aK, 265bK, and 265cK are provided around the insertion hole 261K. The first recess 265aK is provided at a position facing the conical recess 243aK of the positioning plate 243K, and the second recess 265bK is provided at a position facing the V-shaped V-shaped groove 243bK of the positioning plate 243K. ing. The third recess 265ck is provided at a position facing the flat surface portion 243cK of the positioning plate 243K. Similarly, three conical recesses 265aC to 265cC are provided around the C-color insertion hole 261C, and three conical recesses 265aM to 265cM are provided around the m-color insertion hole 261M. . Although not shown, three conical recesses 265aY to 265cY are provided around the Y insertion hole 261Y.

FIG. 8A is a perspective view showing the configuration of the thin plate 266, and FIG. 8B is a cross-sectional view taken along line AA in FIG.
As shown in the drawing, the sphere 264 is held in the recess 265aY by a thin plate 266 having a hole 266a through which a part of the sphere 264 protrudes in the center. The diameter of the hole 266a of the thin plate 266 is slightly smaller than the diameter of the sphere 264, and its edge is subjected to burring. The thin plate 266 is made of spring steel and acts as a leaf spring. The depth of the recess 265aY is slightly longer than the radius of the sphere 264. The sphere 264 is inserted into the recess 265aY, and the thin plate 266 is fixed to the support plate 242 with a screw 267 from above, so that the sphere 264 is held in the recess 265aY with a part protruding from the support plate 242. . In addition, the sphere 264 is held in a state of being biased by the thin plate 266 acting as a leaf spring on the concave portion 265aY side. Further, as shown in FIG. 8, a screw hole 242a is formed at the center of the recess 265aY, and the screw hole 242a serves as an adjustment screw for adjusting the amount of protrusion of the sphere 264 from the support plate 242. A differential screw 268 is screwed. The other recesses 265bY to 265ck have the same configuration.

FIG. 9 is a schematic configuration diagram of the differential screw 268.
As shown in the figure, the differential screw 268 includes a cylindrical outer screw 268a, a cylindrical inner screw 268b having a slightly smaller pitch than the outer screw 268a, a drive shaft 268c, and the like. The outer screw 268 a has a male screw formed on the outer periphery, a female screw formed on the inner periphery, and is screwed into the screw hole 242 a of the support plate 242. A male screw having a slightly smaller pitch than the male screw formed on the outer periphery of the outer screw 268a is formed on the outer periphery of the inner screw 268b, and is screwed to the outer screw 268a. The drive shaft 268c passes through the inner screw 268b, and the tip of the inner screw 268b (the side opposite to the operation side) is fastened to the drive shaft 268c by a clamp 268d. The inner screw 268b is non-rotatable by a rotation stopper 268e.

  When the outer screw 268a is rotated by operating the operation portion 268a-1 of the outer screw 268a from the side of the support plate 242 facing the recording paper 5 (the side on which the droplet discharge head discharges droplets), the inner screw 268a is rotated. The screw 268b moves in the direction perpendicular to the image forming surface of the recording paper 5 (hereinafter referred to as the Z-axis direction) together with the drive shaft 268c. For example, when the pitch of the male screw formed on the outer periphery of the outer screw 268a is 0.5 [mm] and the pitch of the male screw formed on the outer peripheral surface of the inner screw 268b is 0.45 [mm], the outer screw 268a , The inner screw 268b moves along with the drive shaft 268c in the 0.05 [mm] Z-axis direction. Thus, fine adjustment is possible by using a differential screw as the adjusting screw.

FIG. 10 is a schematic diagram showing a state in which the droplet discharge head 241 is fixed to the support plate 242, and FIG. 11 is a diagram for explaining the positioning of the droplet discharge head 241. In addition, since each color structure is the same, in the following description, a color code | symbol is abbreviate | omitted and demonstrated.
When attaching the droplet discharge head 241 to the support plate 242, first, the droplet discharge head 241 is moved in the Z-axis direction, and a part of the droplet discharge head 241 is inserted into the insertion hole 261 of the support plate 242. . Next, as shown in FIG. 11, the sphere 264 held in the first recess 265a of the support plate 242 is engaged with the conical recess 243a of the positioning plate 243, and the sphere 264 held in the second recess 265b is The positioning plate 243 is engaged with the V-shaped groove 243b. Further, the spherical body 264 held in the third recess 265c is brought into contact with the flat surface portion 243c of the positioning plate 243. Accordingly, the droplet discharge head 241 is positioned on the support plate 242 via the positioning plate 243 in the X axis direction, the Y axis direction, and the Z axis direction. More specifically, the sphere 264 held in the first recess 265a comes into line contact with the inclined surface of the conical recess, whereby the droplet discharge head 241 is positioned in the Y-axis direction. In addition, the sphere 264 held in the second recess 265b makes point contact with the two inclined surfaces of the V-shaped groove, whereby the droplet discharge head 241 is positioned in the X-axis direction. Further, in addition to these, the sphere 264 held in the third recess 265c comes into contact with the flat portion 243c, so that the droplet discharge head 241 is supported at three points with respect to the support plate, and in the Z-axis direction. Positioned.

  In the present embodiment, the positioning portion to be positioned with the spherical body 264 as the positioning member of the support plate 242 is a conical recess, a V-shaped groove portion, and a flat portion, so that the positioning portion is all conical recesses. In comparison, the tolerance of the distance between the centers of the three spheres can be relaxed. More specifically, even if the position of the sphere held in the second recess 265b slightly deviates from the target position in the Y-axis direction, the sphere held in the second recess 265b is engaged with the V-shaped groove. Can be combined. Further, even when the position of the sphere held in the third recess 265c is slightly shifted in the X-axis direction and the Y-axis direction with respect to the target position, the sphere can be brought into contact with the flat portion. Therefore, the tolerance of the distance between the centers of the three spheres can be relaxed as compared with the case where all the positioned parts are conical recesses.

  Further, in this embodiment, a spherical body 264 is used as the positioning member, the tip shape of the portion protruding from the support plate 242 is spherical, and the positioning member is in line contact or point contact with the inclined surface of the conical recess or the inclined surface of the V-shaped groove. The shape to be. Accordingly, the positioning member can be brought into contact with the inclined surface of the conical concave portion and the inclined surface of the V-shaped groove portion with rough accuracy as compared with the shape in which the positioning member is in surface contact with the inclined surface of the conical concave portion and the inclined surface of the V-shaped groove portion. That is, when the positioning member has a shape that makes surface contact with the inclined surface of the conical concave portion, the shape of the portion that protrudes from the support plate of the positioning member is a conical convex portion. However, if the shape of this portion is slightly smaller than the conical recess, the positioning member will rattle in the conical recess. Similarly, when the surface of the positioning member is brought into surface contact with the slope of the V-shaped groove, it is necessary to form a slope having an opening angle similar to that of the V-shaped groove. However, if this opening angle is slightly smaller than the opening angle of the V-shaped groove part, the positioning member will rattle in the V-shaped groove part. On the other hand, by positioning the positioning member in line contact or point contact with the inclined surface of the conical recess or the inclined surface of the V-shaped groove portion, even with rough accuracy, the positioning member makes line contact or point contact with the inclined surface of the conical recess or the inclined surface of the V-shaped groove portion. The positioning member does not rattle on the inclined surface of the conical recess or the V-shaped groove. Thereby, compared with the case where it makes surface contact, since it can manufacture easily, an apparatus can be made cheap.

  In the present embodiment, the spherical body 264 is used as the positioning member. However, it may have any shape that makes line contact or point contact with at least the conical recess 243a and the V-shaped groove 243b of the positioning plate 243. For example, the surface in contact with the inclined surface of the conical recess 243a or the surface in contact with the V-shaped groove 243b may be a rotational quadratic surface such as a paraboloid, hyperboloid, or ellipsoid. Further, the positioning member that engages with the V-shaped groove 243b or the conical recess 243a may have a columnar shape such as a quadrangular column or a cylinder. Also in this case, it is possible to make line contact or point contact with the V-shaped groove 243b or the conical recess 243a.

  Moreover, in this embodiment, although the 1st to-be-positioned part is made into the conical recessed part, what is necessary is just a cone shape, such as a triangular pyramid and a quadrangular pyramid. In the case of a triangular pyramid or a quadrangular pyramid shape, a point contact is made with the sphere 264 as a positioning member. Further, the V-shaped groove portion 243b of the positioning plate 243 may not have a V-shaped cross-section. When viewed from the Y-axis direction, the V-shaped groove portion 243b faces the reference line that extends across the sphere 264 and extends parallel to the Z-axis direction. On the other hand, it is only necessary to have at least two flat portions having the same opening angle in opposite directions. For example, the bottom surface may be flat and the inclined surfaces may be formed on both sides. However, in this case, the interval between the inclined surfaces needs to be adjusted so that the sphere 264 does not contact the bottom surface. Further, the material of the support plate 242 may be a metal in consideration of a rigid surface, but a resin having mechanical strength such as PPS is preferable in view of weight reduction. The material of the sphere 264, which is a positioning member provided on the support plate 242, is preferably stainless steel or ceramics as a material that does not rust.

  When the droplet discharge head 241 is positioned on the support plate 242 via the positioning plate 243 as described above, the stepped screw 244 is placed at the center in the Y-axis direction of the positioning plate as shown in FIG. The stepped screw 244 is screwed to the support plate 242 by being inserted into the through holes provided at both ends in the X-axis direction via the coil spring 245. As a result, the coil spring 245 is compressed between the head of the stepped screw 244 and the upper surface of the positioning plate 243, and the positioning plate 243 is supported in a state where the coil spring 245 is biased toward the support plate by the coil spring 245. Attached to the plate 242.

  Thus, according to this embodiment, the droplet discharge head 241 is positioned and fixed in the X-axis direction by the spherical body 264 engaging with the conical recess 243a of the positioning plate 243. Further, the spherical body 264 engages with the conical recess 243a and the spherical body 264 engages with the V-shaped groove 243b, whereby the droplet discharge head 241 is positioned and fixed on the Y axis. Finally, the sphere 264 is engaged with the conical recess 243a and the V-shaped groove 243b, the sphere is brought into contact with the flat surface 243c, and the droplet discharge head is positioned in the Z-axis direction. The liquid droplet ejection head 241 is positioned and fixed in the Z-axis direction by being biased toward the support plate 242 by the coil spring 245. As a result, the position of the droplet discharge head 241 can be determined.

  If the amount of protrusion of the sphere 264 from the support plate 242 differs due to differences in the depths of the recesses 265a to 265c formed in the support plate 242 due to manufacturing errors or the like, the droplet discharge head 241 may rotate around the Y axis. There is a possibility that it is fixed to the support plate 242 by being inclined, or is attached to be inclined around the X axis. As described above, when the droplet discharge head 241 is mounted with an inclination, the droplets even discharged from the droplet discharge head 241 do not land at the target landing position, thereby degrading the image quality. For this reason, it is necessary to manufacture accurately so that the protrusion amount from the support plate 242 of the spherical body 264 as a positioning member becomes the same. Further, the height to the top of the conical recess, the slope, and the V-shape so that the contact position in the Z-axis direction of the sphere 264 and each positioned portion (conical recess 243a, V-shaped groove 243b, flat surface 243c) are the same. It is necessary to accurately manufacture the opening angle of the slope of the groove. As a result, there arises a problem that the cost of the apparatus increases.

  However, in the present embodiment, the amount of protrusion of the sphere 264 from the support plate 242 can be adjusted using the differential screw 268. As a result, even if the droplet discharge head 241 is tilted about the Y axis or tilted about the X axis, the amount of protrusion of the spherical body 264 from the support plate 242 is adjusted by the differential screw 268, so that the liquid The nozzle surface 254 of the droplet discharge head 241 can be made parallel to the image forming surface of the recording paper 5, and the droplet can be landed at a target landing position.

  For example, when the flat surface portion 243c side of the droplet discharge head 241 is inclined to the liquid discharge side, the differential screw 268 provided in the third recess 265c is operated to lift the sphere 264 to the positioning plate side. The leaf spring-like thin plate 266 is deformed, and the sphere 264 moves toward the positioning plate, and the amount of protrusion from the support plate increases. Then, the flat portion 243c side of the positioning plate 243 is lifted against the urging force of the coil spring 245, and the inclination of the droplet discharge head 241 about the Y axis is adjusted. The amount of movement of the sphere 264 in the Z-axis direction is approximately several tens of μm to several hundreds of μm.

Here, a procedure for replacing the droplet discharge head 241 will be described.
First, the stepped screw 244 to which the failed droplet discharge head 241 is fixed is removed, the failed droplet discharge head 241 is moved away from the droplet landing surface, and the failed droplet discharge head 241 is moved. Is removed from the support plate 242. Next, a new droplet discharge head 241 to which the positioning plate 243 is bonded is attached to the support plate 242. In this case, as described above, the positions of the three positioned portions (the conical concave portion 243a, the V-shaped groove portion 243b, and the flat surface portion 243c) of the positioning plate 243 and the sphere 264 as the three positioning members on the support plate 242 are used. The droplet discharge head 241 is attached in a state in which it is biased toward the support plate side by tightening the stepped screw 244 in accordance with each of the positions. The nozzle position of the droplet discharge head 241 after the replacement can complete the positioning in the X, Y, and Z triaxial directions only by this operation. As will be described later, the positioning plate 243 and the droplet discharge head 241 are joined to a member having the same configuration as that of the support plate 242 in a state where the positioning plate 243 is positioned and held in the same manner as described above. ing. That is, the positioning plate 243 and the droplet discharge head 241 are joined in the same state as that assembled in the image forming apparatus. Therefore, the nozzle row of the droplet discharge head 241 can be attached to the target position simply by positioning and fixing the positioning plate 243 to the support plate 242. Next, an ink supply tube for supplying ink to the droplet discharge head 241 is attached. While printing in this state, and confirming the landing position of the printed droplet, the mounting angle of the droplet discharge head 241 is adjusted by operating the differential screw 268 provided in the recesses 265a to 265c of the support plate 242. Adjust the position. Thus, the replacement operation of the droplet discharge head 241 is completed.

Next, a specific landing position adjustment method will be described.
FIG. 12 is a flowchart of landing position adjustment.
First, as described above, after the droplet discharge head 241 is replaced, the carriage 23 provided with the droplet discharge device 24 is moved to a position facing the recording paper 5 and stopped (S1 to S3). When the carriage 23 stops at a position facing the recording paper 5, the recording paper 5 is conveyed and a test image as shown in FIG. 13 is formed on the recording paper 5. A test image as shown in FIG. 13 is formed by discharging droplets from all the nozzles once with the carriage 23 stopped. In FIG. 13, the C color droplet discharge head 241C is replaced. When the replaced droplet discharge head 241C is tilted around the Y axis, the droplet discharged from the C color is M color. The ink is discharged toward the side or near the K color. As a result, the interval between adjacent colors is shorter or longer than the above-described a1 than the ideal interval (interval a1 between Y color and M color). Further, when the replaced droplet discharge head 241c is tilted around the X axis, the droplets land at positions shifted by b1 in the Y axis direction (sub-scanning direction) with respect to other colors.

  Next, the image forming apparatus displays on the operation display unit or the like that the recording paper 5 on which the test image is formed is set in the image reading unit 11. The service person sets a test image on the image reading unit 11 and operates a start button (not shown). When the start button is pressed, the image forming apparatus reads the test image and grasps the landing position deviation. For example, the interval between the color (C color in FIG. 12) and the adjacent color (M color or K color in FIG. 12) discharged from the replaced droplet discharge head 241c is measured from the read test image. The difference between this interval and the target interval a1 is calculated to grasp the landing position deviation in the X-axis direction (main scanning direction). Further, from the test image, the distances Cy, Cm, and Ck from the landing position at one end in the Y-axis direction (sub-scanning direction) of the color other than the color discharged by the replaced droplet discharge head 241c to the end of the recording paper are measured. The average value is calculated. Next, the distance Cc from the landing position of one end in the Y-axis direction (sub-scanning direction) of the color discharged by the replaced droplet discharge head 241c to the end of the recording paper is measured, and the difference from the above average value is calculated. Then, the landing position deviation in the Y-axis direction (sub-scanning direction) is grasped. The target distance C1 is stored in advance, and the distance Cc from the landing position at one end in the Y-axis direction (sub-scanning direction) of the color discharged by the replaced droplet discharge head 241c to the end of the recording paper 5 is stored. The landing position deviation in the Y-axis direction (sub-scanning direction) may be grasped by comparing with the target distance C1.

Next, the control unit of the image forming apparatus calculates the adjustment amount of the differential screw 268 based on the grasped landing position deviation and displays it on a display unit (not shown). For example, when adjusting the inclination of the droplet discharge head 241 around the Y axis, when the distance between the spheres in the X axis direction is 50 mm and the distance from the nozzle surface 254 to the recording paper is 1 mm, the adjustment amount is the landing position. 50 times the amount of deviation. Specifically, for example, if the landing position is shifted by 5 μm in the X axis direction, the rotation angle θ around the Y axis of the droplet discharge head 241 required to move the landing position by 5 μm in the X axis direction is Since tan ⁻¹ θ = 5 / (1 × 1000), θ = 0.29 °. The adjustment amount for rotating the droplet discharge head 241 about 0.29 ° Y-axis is tan (0.29) × 50 × 1000 = 253 μm when the interval between the spheres in the X-axis direction is 50 mm. Since the differential screw 268 moves in the 50 μm Z-axis direction when the outer screw 268a is rotated once, in this case, a display indicating that the differential screw 268 is instructed to rotate five times is displayed on a display unit (not shown). Then, the service person adjusts the landing position by adjusting the differential screw 268 based on the content displayed on the display unit (not shown). When the adjustment is completed, a predetermined operation is performed on the image forming apparatus to notify the image forming apparatus that the adjustment has been completed.

  In the above description, the image forming apparatus includes the image reading unit 11. However, in the apparatus that does not include the image reading unit as illustrated in FIG. 14, the test image is read by an image reading apparatus outside the image forming apparatus. In this way, the read image data may be transmitted to the image forming apparatus. Further, in the image forming apparatus as shown in FIG. 14, an image reading unit such as a CCD camera is arranged downstream of the carriage 233 in the recording paper conveyance direction, and the formed test image is picked up by this CCD camera. For example, test image data may be obtained. In this case, a reference line is drawn in advance on the lens of the CCD camera, etc., and the reference line is imaged together with the test image on the recording paper, the amount of deviation of the landing position from the reference line is calculated, and the deviation of the landing position is calculated. You may make it grasp.

  In the above description, the amount of protrusion of each sphere 264 from the support plate 242 can be adjusted. Of the three spheres 264, the amount of protrusion of the two spheres 264 from the support plate can be adjusted. That's fine. In this case, the amount of protrusion of the other sphere 264 is adjusted with reference to the amount of protrusion of the sphere held in the recess where the differential screw 268 is not provided, so that the droplet discharge head 241 The inclination around the X axis and the inclination around the Y axis can be adjusted.

Next, a positioning plate joining apparatus for joining the positioning plate 243 and the droplet discharge head 241 will be described.
FIG. 15 is a block diagram illustrating a configuration of the positioning plate joining apparatus 300. A positioning plate joining apparatus 300 shown in the figure is an apparatus that joins the positioning plate 243 by aligning the position of the nozzle row of the droplet discharge head 241. The positioning plate joining apparatus 300 mainly includes a holding unit 334 for holding the positioning plate 243, a stage unit 333, a stage control unit 340, and an image processing unit 350.

  The holding portion 334 for holding the positioning plate 243 has the same configuration as the support plate 242, and the positioning plate 243 is formed on three spheres provided at predetermined positions on the base of the holding portion 334. The conical concave portion 243a, V-shaped groove portion 243b and flat surface portion 243c on the bottom surface thereof are placed in alignment, and are pressed from above by an upper biasing means (not shown) and fixed to the holding portion 344.

  The stage unit 333 includes an arm unit 335 that holds the droplet discharge head 241 and a stage moving unit 337 that moves the arm unit 335. The stage moving unit 337 includes a Y-axis stage 331 that can move the arm unit 335 in the nozzle row direction (Y-axis direction), an X-axis stage 332 that moves in a direction orthogonal to the nozzle row (X-axis direction), and an XY plane. The rotation stage 336 is rotated by the rotation stage 336. Accordingly, the nozzle position of the droplet discharge head 241 can be moved in accordance with predetermined positions in the Y-axis direction, the X-axis direction, and the θ rotation direction.

  The stage control unit 340 includes a stage position detection unit 341, a target position calculation unit 342, a stage drive unit 343, a stage drive control unit 344, an adhesive application unit 345, and an ideal position measurement unit 346. The stage position detector 341 detects the position of the stage. The stage drive control unit 344 controls the stage drive unit 343. The adhesive application unit 345 fills an adhesive between the frame unit 255 (see FIG. 4) of the droplet discharge head 241 and the positioning plate 243. The target position calculation unit 342 includes the coordinates (xa, ya) of the ideal position a and the center coordinates (XA, YA) of the nozzle alignment mark 253 shown in FIG. 16 registered in the ideal position registration unit 358 of the image processing unit 350 and the ideal. The difference between the coordinates (xb, yb) of the position b and the center coordinates (XB, YB) of the nozzle alignment mark 252 is calculated, and the distances from the nozzle alignment marks 252 and 253 to the ideal positions a and b are calculated. In addition, the stage position detection unit 341, the target position calculation unit 342, the stage drive unit 343, the stage drive control unit 344, the adhesive application unit 345, and the ideal position measurement unit 346 of the stage control unit 340 can be operated by the operation unit 347. ing.

  The image processing unit 350 includes CCD cameras 351 and 352, coaxial incident illumination units 353 and 354, a monitor 355, an operation unit 356, a nozzle alignment mark measurement unit 357, and an ideal position registration unit 358. As shown in FIG. 17, the CCD cameras 351 and 352 image the vicinity of the nozzle alignment marks 252 and 253 provided on the droplet discharge head 241, and the coaxial incident illumination units 353 and 354 are connected to the nozzle alignment marks 252 and 253. Illuminate the vicinity. The CCD cameras 351 and 352 of the present embodiment acquire images by photographing the vicinity of the nozzle alignment marks 252 and 253 from a direction perpendicular to the head surface on which the nozzle alignment marks 252 and 253 are formed. For this reason, CCD cameras 351 and 352 having a measurement field of view of horizontal 1.2 mm × vertical 0.9 mm and subject depth of ± 110 microns are used.

  The monitor 355 displays nozzle alignment marks 252, 253 and the like imaged by the CCD cameras 351, 352. The nozzle alignment mark measurement unit 357 performs a series of image processing based on image data in the vicinity of the nozzle alignment marks 252 and 253 photographed by the CCD cameras 351 and 352 and detects the positions of the nozzle alignment marks 252 and 253. Specifically, the optimal illumination dimming is performed by calculating the average density of the image, the optimal binarization is determined, and the nozzle alignment to be used as a position reference based on conditions such as area value, width, height, and circularity The marks 252 and 253 are specified.

  In the present embodiment, as shown in FIG. 16, the center coordinates (XA, YA) of the nozzle alignment mark 253 and the center coordinates (XB, YB) of the nozzle alignment mark 252 are measured, and the data is sent to the nozzle alignment mark measurement unit 357. Output. These series of processes are configured by an image processing system that is activated by incorporating a part of dedicated hardware and software into a general-purpose information device. In this embodiment, an optical image unit with a pixel resolution of 1.6 microns / pixel is provided, and the measurement accuracy is 0.5 microns by gray processing, which is a general software processing.

  The ideal position registration unit 358 acquires and registers the ideal position by being measured by the ideal position measurement unit 346 based on the reference chart 400 in which the ideal position shown in FIG. 18 is recorded. The reference chart 400 is configured by attaching a glass plate 401 on which ideal positions a and b are recorded as shown in FIG. The reference chart 400 is accurately made with micron accuracy at the ideal dimensions of the positions of the nozzle alignment marks 252 and 253 of the droplet discharge head 241, and the ideal position a and the ideal position b are accurately there with micron accuracy. The glass plate 401 recorded in (1) is bonded to the base material 402.

  For obtaining the ideal position, first, the reference chart 400 is attached to the positioning plate joining apparatus 300 in FIG. 15 instead of the droplet discharge head 241, and the CCD camera 351 is based on the signal from the target position calculation unit 345 of the stage control unit 340. , 352, the ideal positions a and b are imaged. Next, the ideal positions a and b are measured by the ideal position measurement unit 346. Then, the ideal position measurement unit 346 transfers this measurement result to the ideal position registration unit 358 and registers this measurement result. In order to attach the reference chart 400 of FIG. 18 instead of the positioning plate 243, the base material 402 constituting the reference chart 400 is provided with a conical recess, a V-shaped groove portion, and a positioning portion on the bottom surface in the same manner as the positioning plate 243. A plane portion is formed. In the present embodiment, the ideal positions a and b are acquired from the reference chart 400 by the ideal position measurement unit 346. In this way, when adjusting the position of the plurality of droplet discharge heads 241, each liquid is not affected by the mechanical error when the positioning plate bonding apparatus 300 is moved to the adjustment start position. The droplet discharge head 241 can be reliably moved to the ideal position.

A process of bonding the droplet discharge head 241 of the positioning plate bonding apparatus 300 to the positioning plate 243 will be described.
The bonding of the droplet discharge head 241 to the positioning plate 243 is performed by the image processing unit 350 executing a program stored in a storage unit (not shown) provided in the image processing unit 350. First, when the power of the positioning plate joining apparatus 300 is turned on, the origin is returned and the origin of the positioning plate joining apparatus 300 is determined. Next, the registered ideal positions a and b are acquired.

  Next, the positioning plate 243 is fixed to the base of the holding part 334. As described above, the holding portion 334 has the same configuration as the support plate, and the positioning plate 243 is placed on the bottom surface of three spheres provided at predetermined positions on the base of the holding portion 334. The conical concave portion 243a, the V-shaped groove portion 243b, and the flat surface portion 243c are placed in alignment, and are pressed from above by an upper urging means (not shown) and fixed to the holding portion 334. At this time, the base of the holding unit 334 in the positioning plate joining apparatus 300 has three spheres arranged at the same size and the same position as the support plate 242 used in the actual image forming apparatus. That is, the state of the positioning plate 243 held by the holding unit 334 is reproduced on the image forming apparatus as it is.

  Next, a UV adhesive is applied in advance on an engaging portion (not shown) provided on the positioning plate 243 using an adhesive application unit 345. Then, the frame portion 255 of the droplet discharge head 241 is gripped by the arm portion 335, and the arm portion 335 is moved in the vertical direction (Z-axis direction) with respect to the base of the holding portion 334 to move the nozzle hole 251a downward. And temporarily fixed to the positioning plate 243. Specifically, the protrusion 256 (see FIG. 4) provided on the Y-axis direction protruding portion of the frame portion 255 of the droplet discharge head 241 is engaged with an engaging portion (not shown) provided on the upper surface of the positioning plate 243. Combine. Next, the droplet discharge head 241 is positioned and fixed in the vertical direction (Z-axis direction) by urging the droplet discharge head 241 toward the positioning plate 243 using an urging means (not shown) that is pressed from above. . Further, the droplet discharge head 241 is temporarily fixed to the positioning plate in the left-right front-rear direction (X-axis direction and Y-axis direction) due to the frictional force.

  Next, position adjustment by the arm portion 335 holding the temporarily fixed droplet discharge head 241 is started. As described above, the position of the droplet discharge head 241 is adjusted by moving in the front-rear and left-right rotation directions (X-axis direction and Y-axis direction) while being pressed against the positioning plate 243 by an urging means (not shown). Done. Next, as shown in FIG. 17, the vicinity of the nozzle alignment marks 252 and 253 is simultaneously imaged by the CCD cameras 351 and 352.

  Next, the nozzle alignment mark measurement unit 357 detects the positions of the nozzle alignment marks 252 and 253. At this time, the optimal illumination of the coaxial epi-illumination units 353 and 354 is adjusted from the calculation of the average density of the image, and the optimal binarization is determined. From conditions such as area value, width, height, and circularity The nozzle alignment marks 252 and 253 used as the position reference are specified. Since the nozzle alignment marks 252 and 253 are made of a material that reflects light, the nozzle alignment marks 252 and 253 can be easily identified. Next, based on the difference between the detected position data of the coordinates of the nozzle alignment marks 252 and 253 and the position data of the coordinates of the ideal positions a and b acquired in advance before the droplet discharge head 241 is assembled. Thus, the movement distances of the nozzle alignment marks 252 and 253 to the ideal positions a and b are calculated. Next, the stage drive controller 344 in FIG. 14 moves the droplet discharge head 241 in the X-axis direction and the Y-axis direction so that the ideal positions a and b coincide with the detected nozzle alignment marks 252 and 253. Or by rotating in the θ rotation direction. Thus, by adjusting the position so that the two ideal positions a and b and the nozzle alignment marks 252 and 253 coincide with each other,

  With reference to the nozzle alignment marks 252 and 253 provided at both ends of the droplet discharge head 241 in the Y-axis direction, the nozzle row of the droplet discharge head includes the apex of the conical concave portion of the positioning plate and the ridge line of the V-shaped groove portion. The droplet discharge head 241 can be positioned on the positioning plate 243 with high accuracy so as to be parallel to the line connecting the two (see FIG. 6). When the position adjustment is completed, the frame portion 255 of the droplet discharge head 241 and the positioning plate 243 are bonded with a UV adhesive by irradiating UV from a UV irradiator (not shown). The UV irradiator irradiates the UV adhesive between the frame part 255 and the positioning plate 243 with UV light.

  The example in which the present invention is applied to the serial type image forming apparatus has been described above, but the present invention can also be applied to a line type image forming apparatus as shown in FIG.

  The image forming unit in this line-type image forming apparatus discharges four line-type liquid droplets that discharge, for example, yellow (Y), magenta (M), cyan (C), and black (K) liquid droplets. The liquid droplet ejection devices 411y, 411m, 411c, and 411k are configured by integrating a head and a sub tank that supplies ink to the liquid droplet ejection head, and each droplet ejection device 411 has a nozzle that ejects droplets. The head holder 413 is mounted with the nozzle surface facing downward.

  As shown in FIG. 20, each droplet discharge device 411 used in this line type image forming apparatus has a droplet discharge head 241 on a support plate 242 that is long in the direction orthogonal to the paper feed direction (X-axis direction). Two insertion hole rows in which a plurality of insertion holes 261 to be inserted are arranged at equal intervals in the X-axis direction (direction orthogonal to the paper feed direction) are provided in the Y-axis direction (paper feed direction). Further, the insertion holes 261 of the support plate 242 are arranged in a staggered manner in the paper transport direction. In the vicinity of each insertion hole 261, the droplet discharge head 241 is supported by engaging or abutting with a conical recess 243 a, V-shaped groove 243 b, and flat surface portion 243 c of the positioning plate 243 joined to each droplet discharge head 241. A spherical body 264 as a positioning member for positioning on the plate 242 is held in the same manner as the configuration shown in FIG. Then, a part of the droplet discharge head 241 to which the positioning plate 243 is bonded is inserted into each insertion hole 261 of the support plate 242. At this time, as shown in FIG. 11, the conical recess 243a, the V-shaped groove 243b, and the flat surface 243c of the positioning plate 243 are engaged with or abutted with the sphere 264, and the droplet discharge head 241 is supported. Positioning and fixing to the plate 242 in the X-axis direction, the Y-axis direction, and the Z-axis direction, a liquid discharge device 411 as shown in FIG. 21 is obtained. Further, the droplet discharge heads 241 inserted into the respective insertion holes 261 are attached so that the nozzle rows are parallel to the X-axis direction (direction orthogonal to the paper feed direction).

  After the droplet discharge head 241 is attached to the support plate 242, a test image is formed on the recording paper 5, the image is read by an image reading device incorporated in the outside or the device, and the amount of deviation of the landing position from the ideal position And the adjustment amount by the differential screw 268 is calculated and displayed. Based on the displayed adjustment amount, the differential screw 268 is operated to adjust the landing position to the target landing position.

  In the above description, the four-color droplet discharge device 411 of y, m, c, and k is provided. However, as shown in FIG. 21, a single droplet discharge device discharges four-color droplets. You may comprise. As shown in FIG. 22, this droplet discharge device 411 includes three droplet discharge heads 241 arranged in a line in the X-axis direction indicated by a dotted line in the figure, and three droplet discharge heads 241 arranged alternately in the front line. Is a set for forming an image of one color. Four such sets are arranged in the Y-axis direction (recording conveyance direction). Also in this droplet discharge device 411, as in the configuration shown in FIG. 11, three spheres are held in the vicinity of each insertion hole of the support plate 242, and the positioning plate 243 joined to the droplet discharge head 241. The conical concave portion 243a, the V-shaped groove portion 243b, and the flat surface portion 243c respectively engage with or come into contact with the sphere, and the droplet discharge head is positioned and fixed to the support plate in the X-axis direction, the Y-axis direction, and the Z-axis direction. . Then, after the droplet discharge head 241 is attached to the support plate 242, a test image is formed on the recording paper 5, and the image is read by an image reading device incorporated in the outside or in the device, and the ideal landing position is obtained. The deviation amount is grasped, and the adjustment amount by the differential screw 268 is calculated and displayed. Based on the displayed adjustment amount, the differential screw 268 is operated to adjust the landing position to the target landing position.

  According to the line-type image forming apparatus including the droplet discharge device 411 as shown in FIGS. 21 and 22, the recording liquid of each color is applied to each pixel in each row on the recording paper conveyed in the conveying direction. As a result, an image is formed.

  In the above description, a plurality of droplet discharge heads are arranged at equal intervals in the X-axis direction. However, a single full-line droplet discharge head that is long in the X-axis direction may be used.

  In addition, a maintenance / recovery mechanism 412y, 412m, 412c, 412k (referred to as "maintenance / recovery mechanism 412" when colors are not distinguished) is provided for maintaining and recovering the head performance corresponding to each droplet discharge device 411. During the performance maintenance operation of the head such as processing and wiping processing, each droplet discharge device 411 and the maintenance / recovery mechanism 412 are relatively moved to configure the maintenance / recovery mechanism 412 on the nozzle surface of each droplet discharge device 411. A capping member or the like is opposed.

  As described above, according to the droplet discharge device 24 of the present embodiment, the droplet discharge head 241 having the nozzle row 251 in which a plurality of nozzles 251 a for discharging droplets are arranged in a predetermined direction and the droplet discharge head 241 are supported. And a support plate 242. In addition, the droplet discharge head 241 has a facing surface that faces the support plate 242, and the facing surface is engaged with a first positioning member that is provided on the support plate 242 and protrudes from the support plate 242. A conical recess 243a as one positioned portion, a V-shaped groove portion 243b as a second positioned portion that engages with a second positioning member that is provided on the support plate 242 and protrudes from the support plate, and the support plate 242 A positioning plate 243 having a flat portion 243c as a third positioned portion that comes in contact with a third positioning member that is provided and protrudes from the support plate is provided. By providing such a configuration, as described above, the droplet discharge head 241 can pass through the positioning plate 243 in the X-axis direction (main scanning direction), the Y-axis direction (sub-scanning direction), and the Z-axis direction (recording paper 5). The image can be positioned in a direction perpendicular to the image forming surface. Accordingly, the droplet discharge head 241 can be positioned in the X-axis direction and the Y-axis direction without urging the droplet discharge head 241 in the X-axis direction and the Y-axis direction. When attaching from the Z-axis direction, the urging means does not come into contact with the nozzle surface 254 of the droplet discharge head 241, and the nozzle surface 254 can be prevented from being damaged.

  Further, according to the droplet discharge device 24 of the present embodiment, the protrusion amount adjustment for adjusting the protrusion amount of the at least two positioning members among the first positioning member, the second positioning member, and the third positioning member from the support plate 242. Means. Thereby, even if the droplet discharge head 241 is tilted in the X-axis direction or tilted in the Y-axis direction, by adjusting the protrusion amount of the positioning member from the support plate 242 by the protrusion amount adjusting means, The tilt can be corrected. Thereby, the droplet can be landed on the target position, and a high-quality image can be obtained. Further, since the droplets can be landed on the target position without accurately forming the discharge amount of each positioning member from the support plate 242, the manufacturing cost can be suppressed and the apparatus can be made inexpensive. it can.

  In addition, the first positioning member and the second positioning member so that the contact between the first positioning member and the conical recess 243a and the contact between the second positioning member and the V-shaped groove portion 243b are line contact or point contact. The tip of the. Thereby, the positioning member can be brought into contact with the inclined surface of the conical concave portion and the inclined surface of the V-shaped groove portion with rough accuracy as compared with the shape in which the positioning member is in surface contact with the inclined surface of the conical concave portion and the inclined surface of the V-shaped groove portion. .

  Each positioning member is a sphere 264, and the support plate 242 is formed with three recesses 265a to 265c into which the different spheres 264 are inserted. A thin plate 266 that is attached to the support plate 242 so as to be opposed to each other, has a hole 266a for projecting a part of the sphere 264, and holds the sphere 264 in the recess 265, and the above-mentioned An adjustment screw for pushing the sphere 264 toward the thin plate 266 is provided. By setting it as such a structure, the protrusion amount of a positioning member can be adjusted, without using an electrical component. Thereby, power saving of the liquid ejection device can be achieved.

  In addition, since the inclination of the droplet discharge head 241 is adjusted by adjusting the amount of protrusion of the positioning member from the support plate 242, the positioning member is different from a member that uses another member to adjust the inclination. Thus, the liquid discharge device can be made compact. In addition, the number of parts can be reduced, and the cost of the apparatus can be reduced.

  In this embodiment, since the adjustment screw of each adjustment means is configured to be accessible from the nozzle surface side where the nozzle row of the droplet discharge head is formed, the adjustment screw can be accessed with a simple configuration. can do.

  Further, by using a differential screw as the adjustment screw, it is possible to finely adjust the protruding amount of the sphere 264, and it is possible to adjust the landing position with high accuracy.

  Further, the image forming apparatus according to the present embodiment uses the above-described droplet discharge device as the droplet discharge unit, so that the droplet can be landed at the target position even after the droplet discharge head is replaced. A quality image can be obtained over time.

  Further, the image forming apparatus according to the present embodiment includes the image reading unit 11 that is an image reading unit that reads an image formed on the recording paper 5 that is a recording medium. Then, a test image is formed on the recording paper 5, the test image formed on the recording paper 5 is read by the image reading unit 11, and the deviation of the landing position of the droplet on the recording paper 5 is detected. Based on the above, each adjusting means is adjusted. Thereby, the shift | offset | difference of a landing position can be adjusted with high precision.

  In addition to a general image forming apparatus, the liquid droplet ejection apparatus of the present invention is a color filter manufacturing apparatus such as a liquid crystal display, an electrode manufacturing apparatus used for electrode formation such as an organic EL display, FED (surface emitting display), or the like. It can also be used for bio-organic matter injection used for biochip manufacturing. The present invention can also be applied to a liquid droplet ejection apparatus that ejects a liquid other than ink, such as a DNA sample, a resist, or a pattern material, or an image forming apparatus that includes these.

1: Copier 2: Image forming unit 5: Recording paper 11: Image reading unit 23, 233: Carriage 24, 411: Droplet discharge device 25: Sub tank 241: Droplet discharge head 242: Support plate 243: Positioning plate 243a: Conical concave portion 243b: V-shaped groove portion 243c: Flat surface portion 243d: Opposing surface 244: Stepped screw 245: Coil spring 251a: Nozzle 251: Nozzle row 252 and 253 Nozzle alignment mark 254: Nozzle surface 256: Protruding portion 258: Head portion 261 : Insertion hole 264: Spheres 265a, 265b, 265c: Conical recess 266: Thin plate 268: Differential screw 268a: Outer screw 268b: Inner screw 268c: Drive shaft 268d: Clamp 300: Plate joining device

JP 2006-231802 A

Claims (9)

In a droplet discharge apparatus including a droplet discharge head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged in a predetermined direction,
A support plate for supporting the droplet discharge head;
A positioning plate provided on the droplet discharge head and having a facing surface facing the support plate, and the droplet discharge head is positioned on the support plate via the positioning plate;
The support plate has a first positioning member, a second positioning member, and a third positioning member protruding from the support plate,
The positioning plate includes a conical recess on the opposing surface, a first positioned portion that engages with the first positioning member, and a groove that extends toward the first positioned portion, and the second A second positioned portion that engages with the positioning member, and a third positioned portion that consists of a plane portion parallel to the opposing surface of the support plate, and abuts against the third positioning member,
A protrusion amount adjusting means for adjusting a protrusion amount of at least two positioning members from the support plate among the first positioning member, the second positioning member, and the third positioning member;
The protrusion amount adjusting means is attached to the support plate and configured to be accessible to the protrusion amount adjusting means from a surface of the support plate opposite to the surface supporting the positioning plate. . The droplet discharge device according to claim 1.
At least the first positioning member and the first positioning member so that the contact between the first positioning member and the first positioned member and the contact between the second positioning member and the second positioned portion are line contact or point contact. A droplet discharge device characterized by forming a tip shape of a second positioning member. The droplet discharge device according to claim 1 or 2,
Each positioning member is held in a recess formed in the support plate,
The protrusion amount adjusting means is provided on the support plate so as to be movable in a direction perpendicular to the surface of the support plate that supports the positioning plate, and adjusts the protrusion amount of the positioning member protruding from the concave surface of the recess. A droplet discharge device comprising a member. The droplet discharge device according to claim 3.
Each positioning member is a sphere,
The support plate has three recesses into which the different spheres are inserted,
The protrusion amount adjusting means is attached to the support plate so as to be opposed to the recess, has a hole for protruding a part of the sphere, and a leaf spring for holding the sphere in the recess A droplet discharge device comprising: a member, wherein the adjustment member is an adjustment screw for pushing the sphere toward the leaf spring member. The droplet discharge device according to claim 4.
A droplet discharge apparatus characterized in that the adjustment screw of the protrusion amount adjusting means can be accessed from the nozzle surface side where the nozzle row of the droplet discharge head is formed. The droplet discharge device according to claim 4 or 5,
A droplet discharge device using a differential screw as an adjustment screw of the protrusion amount adjusting means. Comprising a droplet discharge means for discharging droplets ;
By discharging droplets by a droplet discharge means record medium, an image forming apparatus that forms an image on the recording medium,
An image forming apparatus using the droplet discharge device according to claim 1 as a droplet discharge unit. The image forming apparatus according to claim 7.
Comprising image reading means for reading an image formed on the recording medium,
A test image is formed on the recording medium, the test image formed on the recording medium is read by the image reading unit, and a deviation of the landing position of the droplet on the recording medium is detected. Based on the detection result, An image forming apparatus characterized in that each adjusting means can be adjusted. A droplet discharge head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged in a predetermined direction; a support plate for supporting the droplet discharge head;
A positioning plate provided on the droplet discharge head and having a facing surface facing the support plate, and the droplet discharge head is positioned on the support plate via the positioning plate;
The support plate has a first positioning member, a second positioning member, and a third positioning member protruding from the support plate,
The positioning plate includes a conical recess on the opposing surface, a first positioned portion that engages with the first positioning member, and a groove that extends toward the first positioned portion, and the second Landing in a droplet discharge device having a second positioned portion that engages with a positioning member and a third positioned portion that is in contact with the third positioning member, and includes a plane portion parallel to the opposing surface of the support plate. In the position adjustment method,
The droplet discharge device includes a protrusion amount adjusting unit that adjusts a protrusion amount of at least two positioning members from the support plate among the first positioning member, the second positioning member, and the third positioning member, The protrusion amount adjusting means is attached to the support plate, and is configured to be accessible to the protrusion amount adjusting means from a surface opposite to the surface supporting the positioning plate in the support plate .
Forming a test image on a record medium,
A step of reading a test image formed on the recording medium by an image reading means;
Based on the image read by the image reading means, the step of grasping the attachment / detachment position deviation of the droplet to the recording medium;
And a step of adjusting the amount of protrusion of the positioning member from the support plate using the protrusion amount adjusting means based on the grasped landing position deviation.

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