JP2011037235A - Image forming apparatus, liquid discharging head unit, and method for assembling liquid discharging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of highly accurately positioning a head when an object to be positioned is shifted during head position adjustment. <P>SOLUTION: A liquid discharge head unit 3 having a head holder mounted with a plurality of heads 11 is detachably held on a carriage 2. The head holder includes positioning parts 23a to 23c that come into contact with positioning surfaces 41a to 41c which are provided to the carriage 2 and become positioning references in a carriage scanning direction and a sheet conveying direction, and the positioning parts 23a to 23c become positioning references of the liquid discharge heads 11 to the head holder. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, a liquid discharge head unit, and a method for assembling a liquid discharge apparatus.

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

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. The image is not limited to a flat image, but also includes an image given to a three-dimensionally formed image and a three-dimensional image formed by modeling a three-dimensional solid itself.

  In an image forming apparatus using such a liquid ejection method, the image forming speed greatly depends on the number of nozzles of the recording head, and the number of scans can be reduced by increasing the number of nozzles. Therefore, a plurality of liquid discharge heads are mounted on a head holder as a recording head and used to reduce the number of carriage scans and increase the recording speed.

  By the way, when an image is formed in an image forming apparatus using a liquid ejection method, the landing accuracy of droplets ejected from nozzles greatly affects the image quality, and if the landing accuracy of droplets is poor, the image quality is degraded. Therefore, when a plurality of liquid ejection heads are attached, it is necessary to position each head position with high accuracy.

  Therefore, for example, when positioning the liquid ejection head on the carriage, the position of the liquid ejection head is adjusted by adjusting the position of the head while the liquid ejection head is pressed by a spring (Patent Document 1).

  Also, a transparent mask with positioning reference marks is prepared, and the head alignment mark is imaged through the mask, and the assembly is performed by positioning so that the reference mark on the mask and the alignment mark of the liquid jet head are aligned. (Patent Document 2).

  Also, there is an apparatus in which alignment marks between adjacent heads are detected in the same field of view, and the alignment marks of both are aligned and assembled so as to have a predetermined positional relationship (Patent Document 3).

  On the other hand, assuming that the positions of the carriage and the liquid ejection heads are relatively positioned, two reference marks for position recognition are arranged on the carriage, and after recognizing the position of the carriage, a plurality of liquid ejection heads are positioned on the carriage. Some are assembled (Patent Document 4).

JP 2005-144933 A JP 2008-246799 A JP 2004-216816 A Japanese Patent No. 4154882

  However, when the head pressed by the spring is moved, a force for moving the carriage by the frictional force is applied, and the position of the carriage may be shifted by several tens of μm. If the carriage position is deviated during position adjustment, the relative position between the carriage and the liquid ejection head will not only be displaced, but the relative position between the already positioned liquid ejection head and the liquid ejection head to be positioned will be deviated, resulting in head positioning accuracy. There is a problem that decreases. None of the techniques disclosed in Patent Documents 1 to 3 described above considers the occurrence of carriage displacement when adjusting the position of the liquid ejection head, and cannot solve this problem.

  In addition, in some image forming apparatuses using a liquid ejection method, a recording head is detachably mounted on a carriage, and when a recording head fails, an image can be formed again by replacing it with a new recording head. . In an image forming apparatus that performs printing on wide paper at high speed, the number of liquid discharge heads to be mounted is large. Therefore, instead of replacing the liquid discharge head unit, the liquid discharge head unit is composed of a plurality of liquid discharge heads. It is supposed to be replaced.

  In such a case, it is necessary to relatively position the carriage and the liquid discharge head, but when the technique disclosed in Patent Document 4 described above is applied, a recognition means for recognizing the carriage position and the head position is provided. Therefore, the adjustment device becomes complicated and large-sized, and the head cannot be easily replaced. For example, it is difficult to replace the head in the user's usage environment.

  The present invention has been made in view of the above problems, and can perform head alignment with high accuracy even when the positioning object is displaced during head position adjustment, and can easily perform high accuracy when replacing the head. An object is to enable proper head positioning.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A head holder for mounting a plurality of liquid ejection heads;
An image forming apparatus having a carriage for detachably holding the head holder,
The head holder includes a positioning portion that is provided on the carriage and contacts a positioning reference in a carriage scanning direction and a sheet conveyance direction, and the positioning portion serves as a positioning reference for the liquid ejection head to the head holder. It was.

  Here, at least a part of the outer peripheral surface of the positioning portion of the head holder can be configured as a positioning reference for the liquid ejection head.

  Further, a mark may be provided in the positioning portion of the head holder, and the mark may be a positioning reference for the liquid ejection head.

  Further, at least three positioning parts of the head holder are arranged, and one of the positioning parts of the head holder is arranged on the paper conveying direction side of the head holder.

  Further, the positioning part of the head holder may be formed by a metal pin.

The liquid discharge head unit according to the present invention is
A liquid discharge head unit having a liquid discharge head and a head holder on which the liquid discharge head is mounted,
The head holder has a positioning portion that contacts the positioning reference of the liquid ejection apparatus main body, and the positioning portion of the head holder serves as a positioning reference for the liquid ejection head to the head holder.

An assembly method of a liquid ejection device according to the present invention includes:
Coordinates are set using a positioning unit for a liquid discharge device of a head holder on which a plurality of liquid discharge heads are mounted, the liquid discharge head is positioned at a virtual reference position on the coordinates and fixed to the head holder, The head holder is positioned on the liquid ejection apparatus main body.

Here, the step of positioning the liquid ejection head at the virtual reference position includes:
Detecting the positioning part to the liquid ejection apparatus main body;
Updating the coordinates and the virtual reference position based on the detected result;
And a step of positioning the liquid ejection head at the updated virtual reference position.

  According to the image forming apparatus of the present invention, a head holder on which a plurality of liquid discharge heads are mounted has a positioning unit that is provided on the carriage and that is in contact with a positioning reference in the carriage scanning direction and the sheet conveyance direction, and the positioning unit is a liquid Since the configuration is used as a reference for positioning the ejection head to the head holder, it is possible to perform head alignment with high accuracy even when the positioning target is displaced during head position adjustment, and it is easy to replace the head. Highly accurate head positioning is possible.

  According to the liquid discharge head unit of the present invention, the head holder on which the liquid discharge head is mounted has the positioning portion that contacts the positioning reference of the liquid discharge apparatus body, and the positioning portion of the head holder is connected to the head holder of the liquid discharge head. Since the positioning reference is used, head positioning can be performed with high precision even when the positioning target is displaced during head position adjustment, and high-precision head positioning can be performed easily even when replacing the head. Yes.

  According to the method for assembling a liquid ejection device according to the present invention, coordinates are set using a positioning unit for a liquid ejection device of a head holder on which a plurality of liquid ejection heads are mounted, and liquid ejection is performed at a virtual reference position on the coordinates. Since the head is positioned and fixed to the head holder, and the head holder is positioned on the liquid ejection apparatus main body, the head positioning can be performed with high accuracy even when the positioning target is displaced during the head position adjustment. In addition, the head positioning can be easily performed with high accuracy even when the head is replaced.

1 is a schematic plan view of a mechanism unit showing an example of an image forming apparatus according to the present invention. It is explanatory drawing seen from the nozzle surface side of the liquid discharge head unit in 1st Embodiment of this invention. It is side surface explanatory drawing of FIG. FIG. 6 is an explanatory perspective view for explaining a structure for fixing a liquid discharge head to a head holder. FIG. 5 is an explanatory plan view for explaining a configuration on a carriage side. It is explanatory drawing with which it uses for description of the assembly method of a liquid discharge head unit. It is a plane explanatory drawing similarly. It is a plane explanatory drawing similarly used for description of position shift of a head holder. It is explanatory drawing seen from the nozzle surface side of the liquid discharge head unit in 2nd Embodiment of this invention. It is explanatory drawing seen from the nozzle surface side of the liquid discharge head unit in 3rd Embodiment of this invention. It is a plane explanatory view of the carriage part in a 4th embodiment of the present invention. 1 is an external perspective view illustrating an example of an ink jet recording apparatus as an image forming apparatus including a head unit according to the present invention. FIG. 3 is an explanatory plan view of a printing mechanism unit of the recording apparatus. It is a schematic perspective view of a carriage part.

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is an explanatory plan view for explaining the mechanism of the image forming apparatus.
The image forming apparatus includes a carriage 2 movable in the main scanning direction (carriage scanning direction) inside the apparatus main body 1 and two sets (not limited to two sets) of liquid discharge head units (not limited to two sets) mounted on the carriage 2. (Hereinafter referred to as “head unit”) 3.

  The carriage 2 is slidably held in the main scanning direction by a main guide rod 4 and a sub guide rod 5 which are guide members horizontally mounted on left and right side plates (not shown). A main scanning motor 6 for moving the carriage 2 in the main scanning direction is arranged on one end side of the main guide rod 4, and a pair of driving pulleys 7 and driven pulleys arranged on both end sides of the main guide rod 4. The carriage 2 is reciprocated in the main scanning direction by transmitting the driving force of the motor 6 to the carriage 2 via the timing belt 9 spanned between the two.

  A head unit 3 having a plurality of liquid discharge heads (hereinafter simply referred to as “heads”) 11 is detachably attached to the carriage 2. Each head 11 is supplied with ink from an ink tank 14 by an ink supply means (not shown). As shown in FIG. 2, which will be described later, the head 11 is mounted on the head unit 3 so that a nozzle surface 13 on which nozzles 12 for discharging droplets are formed faces downward.

  At the time of image formation, paper 13 fed from a paper feed cassette or manual feed tray (not shown) is taken in, and the head 11 of the head unit 3 is driven according to the image signal while moving the carriage 2 in the main scanning direction. An image is formed by ejecting ink droplets 13. When the image formation for one line is completed, the sheet 13 is conveyed by a predetermined amount, and the image formation for the next line is performed. By repeating this operation, a required image is formed on the paper 11, and after the image formation is completed, the paper is discharged to a paper discharge tray (not shown).

Next, details of the head unit according to the first embodiment of the present invention will be described with reference to FIGS. 2 is an explanatory plan view of the head unit, and FIG. 3 is an explanatory side view.
The head unit 3 includes a plurality of heads 11 and a head holder 21 that holds the plurality of heads 11. The head 11 is inserted and held in a holding hole 22 provided on the lower surface of the head holder 21.

  In the head holder 21, positioning portions 23a to 23c (referred to as “positioning portion 23” when not distinguished) that are in contact with the positioning surfaces 41a to 41c, which are positioning references in the carriage scanning direction and the paper conveyance direction, provided on the carriage 2. Three metal pins 24 a to 24 c to be formed (referred to as “pin 24” when not distinguished) are inserted such that the side surface of the pin 24 partially protrudes from the side surface of the head holder 21. The protruding portion of each pin 24 serves as a positioning portion 23 when the head unit 3 is mounted on the carriage 2 or mounted on the assembly apparatus.

  Here, two positioning portions 23a and 23b are provided in the carriage scanning direction (X direction), and one positioning portion 23c is formed by pins 24 in the paper transport direction (Y direction).

  Although not shown, a positioning surface in the direction (Z direction) orthogonal to the X direction and the Y direction is provided on the lower surface of the head holder 21.

  As described above, the holding hole 22 is provided in the head holder 21 in parallel in the main scanning direction. Here, since the three heads 11 are mounted, three holding holes 22 are provided. Here, the holding holes 22 are arranged in the same row in the main scanning direction (position where the paper conveyance direction is the same), but the holding holes 22 may be arranged so as to be shifted in the paper conveyance direction.

  The head 11 is held with the nozzle surface 13 protruding from the holding hole 22 of the head holder 21.

Next, a structure for fixing the head 11 to the head holder 21 will be described with reference to FIG.
The head 11 is pressed against the head holder 21 at three locations via springs 31 to 33, and after the head 11 is adjusted in position, the head 11 is bonded and fixed to the head holder 21 at the bonding portion 16. The spring that presses the head 11 is arranged as shown in FIG. In the figure, the head 11 is illustrated with the nozzle surface 13 facing downward.

  That is, the upper leaf spring 31 is disposed on the upper portion of the head 11 and presses the head 11 so as to press it against the head holder 21. The rear leaf spring 32 is disposed so as to sandwich the head 11 and the head holder 21, and this also presses the head 11 against the head holder 21. The horizontal leaf spring 33 is disposed on the side surface of the head 11 and presses the head 11 so as to press against the protrusion provided on the side surface of the holding hole 22 of the head holder 21.

  Next, the configuration on the carriage 2 side will be described with reference to FIG. FIG. 5 is a plan view showing the carriage. Further, FIG. 2 shows an example in which two head units 3 are mounted on the left and right, and the left side of the carriage is shown with no head unit 3 mounted, and the right side is shown with the head unit 3 mounted.

  The carriage 2 has positioning surfaces 41a and 41b in the carriage scanning direction (X direction) with respect to the head holder 21, a positioning surface 41c in the paper transport direction (Y direction), and a direction (not shown) orthogonal to the X direction and the Y direction ( (Z direction) positioning surface, pressing spring 43, and opening 44.

  The opening 44 is arranged so that the head 11 enters the opening 44 in a state where the head unit 3 is positioned. The pressing spring 43 is disposed so as to press the side surface of the head holder 21 with a predetermined force, and the head unit 3 is moved away by pressing. Accordingly, the head unit 3 is positioned in the X, Y, and Z directions so that the positioning surfaces 41a to 41c of the carriage 2 and the positioning portions 23a to 23c of the head holder 21 are in contact with each other. Since the head unit 3 is positioned by pressing by the pressing spring 43, the head unit 3 can be easily replaced and positioned.

  Next, a method for assembling the head 11 to the head holder 21 will be described with reference to FIGS. FIG. 6 is an explanatory view of the main part of the head unit assembling apparatus, and FIG. 7 is an explanatory plan view of a state where the head holder is set in the assembling apparatus.

  In the assembling apparatus, a positioning unit imaging unit 51 for recognizing the position of the positioning unit 23 of the head holder 21 and an alignment mark imaging unit 52 for recognizing the positions of the alignment marks 15 and 15 formed on the head 11 are provided. As shown in FIG. 7, the head holder 21 is pressed by the same force at the same position as the carriage mounted by the pressing spring 53, and the head holder 21 is against the positioning surfaces 54 a to 54 c provided in the assembly apparatus. Positioning is performed in the X, Y, and Z directions so that the positioning unit 23 contacts.

  Here, the head holder 21 is molded from a resin using a metal mold because of its good mass productivity. The head holder 21 is deformed when pressed by a spring. The positioning position can be reproduced even when the carriage is mounted.

  When the head 11 is assembled to the head holder 21, first, the position of the positioning unit 23 is recognized by the positioning unit imaging unit 51. The position of the pin outer shape contacting the carriage positioning surfaces 41a and 41b (positioning surfaces 54a and 54b of the assembling apparatus) is calculated from the outer positions of the pins 24a and 24b to be the two positioning portions 23a and 23b in the X direction, and they are connected. The axis is set as a virtual Y-axis (virtual Y-axis), and the outer position of the pin 24c serving as the Y-direction positioning portion 23c and the position of the pin outer shape that contacts the carriage positioning surface 41c are calculated from the virtual Y-axis. Set the X axis (virtual X axis).

  Then, the target positions of the alignment marks 15 and 15 of the head 11 are calculated from the set virtual X axis and Y axis, and the alignment mark imaging unit 52 is moved by a moving unit (not shown) to an area where the target position can be imaged. And the alignment mark 15 are adjusted so as to be in the same field of view. FIG. 6 shows a state in which the alignment mark imaging means 52 is moved to a position where the leftmost head 11 is assembled.

  Next, the position of the head 11 is moved by adjusting means (not shown), the two alignment marks 15 and 15 and the two target positions are parallel, and the Y position of one of the alignment marks 15 is the same as the target Y position. Adjust so that

  At this time, by moving the head unit 3 pressed by the pressing spring 53, a force for moving the head holder 21 by a frictional force is exerted, and as shown in FIG. The position of the head holder 21 may deviate by several tens of μm from the position to the position of the head holder 21 shown by the solid line.

  However, in this embodiment, the positioning unit 23 can be recognized even during the head position adjustment, and the virtual coordinates and further the target position can be updated at any time. Therefore, even if the head holder 21 is displaced as shown in FIG. The head position can be adjusted to the correct position by recalculating the target position. After the position adjustment is completed, the head 11 and the head holder 21 are bonded and fixed at the bonding portion.

  By assembling the head unit 3 in such a manner, the head 11 can be positioned with high accuracy with respect to the positioning portion 23 (outer position of the pin 24) of the head holder 21 which becomes a butt reference when the carriage is mounted. In addition, since the state on the assembling apparatus can be reproduced on the carriage 2, positioning of the head unit 3, that is, the head 11 can be easily realized even when the head unit 3 is replaced.

  As described above, when the head unit is assembled, the holding state is the same as that when the carriage is mounted on the assembly device, and the head is positioned based on the virtual coordinate reference created from the detected head holder positioning unit, and the virtual coordinate is also adjusted when the head position is adjusted. Can be used to achieve high-precision head alignment even when the head holder is displaced during head position adjustment, as well as the positioning reference position between the head and the head holder, and the positioning reference position between the head holder and the carriage. Therefore, when the head unit is replaced, the high-precision positioning of the head can be easily reproduced by exchanging the head positioned on the head unit with high accuracy in units of head units.

  As described above, the head holder for mounting a plurality of liquid discharge heads on the liquid discharge apparatus main body has a positioning portion that is in contact with the positioning reference provided in the carriage in the carriage scanning direction and the paper transport direction, and the positioning portion is By adopting a configuration that serves as a reference for positioning the liquid ejection head to the head holder, head positioning can be performed with high precision even when the positioning target is displaced during head position adjustment. In addition, high-precision head positioning can be performed easily.

  In addition, by setting the coordinates using the positioning part of the head holder on which multiple liquid discharge heads are mounted and positioning the liquid discharge head at the virtual reference position on the coordinates, the positioning target is adjusted during head position adjustment. Even when the position of the head is shifted, the head can be aligned with high accuracy, and the head can be easily positioned with high accuracy even when the head is replaced.

Next, a head unit according to a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory plan view of the head unit.
Here, a mark (reference mark) 71 is provided at the tip of the pin 24 forming the positioning portion 23 of the head holder 21 of the head unit 3, and the position of the head holder 21 can be detected from the position of the mark 71 by image recognition. ing. For example, if the shape of the pin 24 is a cylinder and the mark 71 is formed coaxially, the outer shape of the pin 24 in contact with the positioning surface 41 and the position of the mark 71 can be accurately formed.

  In this way, since the two-dimensional coordinates of the mark can be easily detected by forming the reference mark in the positioning part of the head unit 3, the contact point with the carriage positioning surface is calculated from a plurality of positioning parts (pin outer shapes). Compared with the configuration method of the above-described embodiment in which the virtual coordinates are calculated, the virtual coordinates can be set easily.

Next, a head unit according to a third embodiment of the invention will be described with reference to FIG. FIG. 10 is an explanatory plan view of the head unit.
Here, positioning portions 23 a to 23 c are integrally formed on a part of the outer peripheral surface of the head holder 21 constituting the head unit 3, and a reference mark 71 is provided in each positioning portion 23.

  That is, as described above, when the head holder 21 is formed by resin molding, the head holder 21 is deformed when pressed by a spring for positioning the holder. If the reference mark 71 of the head holder 21 is formed at a position away from the positioning portion 23, the head holder 21 is also displaced by the deformation of the head holder 21 due to the pressing of the pressing spring 43 (the pressing spring 53 at the time of assembly). Therefore, the position of the reference mark 71 in the head holder holding state also varies due to variations in deformation of the head holder 21 caused by variations in spring force and variations in holder rigidity. On the other hand, in this embodiment, the reference mark 71 of the head holder 21 is formed on the positioning portion 23, and the position of the positioning portion 23 is constant with respect to the positioning surface 41 (positioning surface 54 during assembly) regardless of the spring pressure. Therefore, the position of the head holder 21 can be detected with high accuracy.

  Further, unlike the first embodiment described above, the reference mark is not provided, and the position of the head holder 21 can be detected by a positioning portion (pin outer shape). However, the resin-molded positioning portion 23 has a rounded edge. Therefore, the position of the reference mark 71 can be detected more accurately than the positioning portion 23.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory plan view of a carriage portion in the same embodiment.
Here, the carriage 2 is provided with a positioning surface adjustment mechanism 46 that adjusts the position of the positioning surface 41c in the paper transport direction (Y direction) in the head unit mounting portion on one side.

  That is, the carriage 2 is molded with resin using a mold because of its mass productivity, and the dimension of the resin-molded part may vary depending on molding conditions. For example, in the carriage 2 shown in FIG. The positioning surface 41c in the paper transport direction (Y direction) may be displaced between the left and right head unit mounting portions. If the head 11 has a deviation in the carriage scanning direction, the ink landing position can be adjusted by controlling the timing of ink ejection during image formation. However, if the head 11 has a deviation in the paper conveyance direction, Since the landing position cannot be shifted by the discharge timing control, the deviation of the head position in the paper transport direction directly leads to a decrease in landing accuracy.

  When a plurality of head units 3 are mounted on the carriage 2, the head 11 is positioned with high accuracy in the head unit 3, so that the positions of the head units 3 and 3 in the paper transport direction are in a correct positional relationship. It is necessary to keep.

  Therefore, as in this embodiment, by providing the positioning surface adjustment mechanism 46 so that the position of the head unit 3 can be adjusted in the Y direction, the landing position can be achieved even when the molding dimensional accuracy of the carriage 2 is poor. Misalignment can be prevented. Moreover, since the positioning part 23 of the head holder 21 is one place with respect to the Y direction, the position can be easily adjusted as compared with the adjustment at a plurality of places.

  Here, of the positioning surfaces 41c and 41c for determining the Y-direction positions of the two head units 3 and 3, the adjustment mechanism 46 is provided for one of the Y-direction positioning surfaces 41c, but both the Y-direction positioning surfaces 41c are provided. , 41c can also be provided with an adjusting mechanism 46. Further, in the case of a carriage on which three or more head units are mounted, a position adjusting mechanism may be provided according to the number of head units that need to be adjusted.

In the above description, the head holder and carriage of the head unit are described as being resin-molded. However, the material is not limited, and for example, the head unit and carriage may be formed of a metal member or the like. The present invention is equally applicable.

  Next, an example of an ink jet recording apparatus as an image forming apparatus including the head unit according to the present invention will be described with reference to FIGS. FIG. 12 is an external perspective view of the recording apparatus, FIG. 13 is a plan view of the printing mechanism of the recording apparatus, and FIG. 14 is a schematic perspective view of the carriage portion.

  This ink jet recording apparatus is a serial type ink jet recording apparatus. Inside the recording apparatus main body 201, guide rods 203 and guide rails 204 are spanned on both side plates (not shown). A carriage 205 is slidably held in the main scanning direction. The guide rail 204 is configured such that a sub guide roller 206 rotatably supported on the rear portion of the carriage 205 abuts.

  A main scanning mechanism that moves and scans the carriage 205 is disposed on one side in the main scanning direction, a driving pulley 212 that is rotationally driven by the driving motor 211, and on the other side in the main scanning direction. A driven pulley 213 and a timing belt (belt member) 214 wound around the drive pulley 212 and the driven pulley 213 are provided. The driven pulley 213 is tensioned outward (direction away from the drive pulley 212) by a tension spring.

  Here, the driving pulley 212 and the driven pulley 213 are arranged such that the pulley axial direction is located in a direction along the ink droplet ejection direction. A part of the belt member 214 wound between the driving pulley 212 and the driven pulley 213 is fixedly held by a belt fixing portion provided on the back side of the carriage 205, so that the main scanning direction is increased. It is arranged on one side of the carriage 205 in the orthogonal direction.

  The carriage 205 is also equipped with head units 220A, 220B, and 220C according to the present invention having nozzles that eject ink droplets of black (K), yellow (Y), magenta (M), and cyan (C). is doing. In the head unit 220A, the recording heads 220a to 220d are mounted on the head holder 221A, the recording heads 220e to 220g are mounted on the head holder 221B, and the recording heads 220h to 220j are mounted on the head holder 221C. . Each of these recording heads 220a to 220j has two nozzle rows.

  Here, the recording heads 220a and 220b and the recording heads 220c and 220d of the head unit 220A are used as heads for ejecting black ink droplets, for example, in a staggered arrangement with their positions shifted in the paper transport direction. Further, the recording heads 220e to 220g and the recording heads 220h to 220j of the head unit 220B and the head unit 220C are staggered by shifting their positions in the paper conveyance direction. For example, one nozzle row of the recording heads 220e and 220h is yellow. The other nozzle row ejects magenta ink droplets, the other nozzle row of 220g and 220j ejects magenta ink droplets, the other nozzle row ejects yellow ink droplets, and the recording heads 220f and 220i both By using the nozzle row as a head that discharges cyan ink droplets, the area in the paper feed direction for the two heads can be printed in the same main scan, and the discharge order of the color ink in the forward path and the backward path is the same. I have to.

  On the other hand, in the recording area of the main scanning area of the carriage 205, the sheet 210 is intermittently conveyed by being guided by the platen member in a direction (sub-scanning direction) perpendicular to the main scanning direction of the carriage 205 by a paper feed mechanism (not shown). Is done. The platen member is disposed to face the recording head 220 at least in the recording area along the main scanning area of the carriage 205.

  In addition, a maintenance / recovery mechanism 208 that performs maintenance / recovery of the recording head 220 is disposed in one end side region of the main scanning region. The maintenance / recovery mechanism 208 includes a cap 230 that seals (capping) each nozzle surface of the recording heads 220a to 220j, a wiper member that wipes the nozzle surface (not shown), and the like.

  Further, as shown in FIG. 12, an ink cartridge (main tank) 300 containing ink of each color supplied to the recording head 220 is detachably mounted outside one main scanning area.

  In this ink jet recording apparatus, the carriage 205 is moved in the main scanning direction, and the recording head 220 is driven according to the image information while the paper 210 is intermittently sent in the sub-scanning direction, thereby ejecting droplets. A required image is formed on 210.

  The configurations of the head units 220A to 220C regarding the positioning of the head holders 221A, 221B, and 221C with respect to the carriage 205 and the positioning of the recording heads 220a to 220j with respect to the head holders 221A, 221B, and 221C are the same as described in the above embodiments. Yes. Here, the configuration of FIG. 1 is illustrated, and only the head unit 220A is denoted by the same reference numeral, but the configurations of the other head units 220B and 220C are also the same.

2 Carriage 3 Liquid discharge head unit 11 Liquid discharge head 21 Head holder 23 Positioning portion 24 Pin 41 Positioning surface 71 Reference mark 205 Carriage 220A, 220B, 220C Head unit 220a to 220j Recording head (liquid discharge head)
221A, 221B, 221C Head holder

Claims (8)

A head holder for mounting a plurality of liquid ejection heads;
An image forming apparatus having a carriage for detachably holding the head holder,
The head holder includes a positioning portion provided on the carriage and in contact with a positioning reference in a carriage scanning direction and a sheet conveyance direction, and the positioning portion serves as a positioning reference for the liquid ejection head to the head holder. An image forming apparatus.   The image forming apparatus according to claim 1, wherein at least a part of an outer peripheral surface of the positioning portion of the head holder serves as a positioning reference for the liquid discharge head.   The image forming apparatus according to claim 1, wherein a mark is provided in a positioning portion of the head holder, and the mark serves as a positioning reference for the liquid ejection head.   The positioning unit of the head holder is arranged at least three, and one of the positioning units of the head holder is arranged on the paper conveyance direction side of the head holder. An image forming apparatus according to claim 1.   5. The image forming apparatus according to claim 1, wherein the positioning portion of the head holder is formed of a metal pin. A liquid discharge head unit having a liquid discharge head and a head holder on which the liquid discharge head is mounted,
The head holder has a positioning part in contact with the positioning reference of the liquid discharging apparatus main body, and the positioning part of the head holder serves as a positioning reference for the liquid discharging head to the head holder. unit.   Coordinates are set using a positioning unit for a liquid discharge device of a head holder on which a plurality of liquid discharge heads are mounted, the liquid discharge head is positioned at a virtual reference position on the coordinates and fixed to the head holder, A method for assembling a liquid ejection apparatus, comprising: positioning a head holder on the liquid ejection apparatus main body. Positioning the liquid ejection head at the virtual reference position,
Detecting the positioning part to the liquid ejection apparatus main body;
Updating the coordinates and the virtual reference position based on the detected result;
The method of assembling a liquid ejection apparatus according to claim 7, further comprising: positioning the liquid ejection head at the updated virtual reference position.

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