JP5316112B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a carriage on which a recording head for discharging droplets is mounted.

  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 recording apparatus using a recording head for discharging ink droplets is known. This ink jet recording apparatus means a sheet on which ink droplets are conveyed from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Or a recording medium, recording paper, recording paper, medium, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). A line using a serial type image forming apparatus that forms an image by ejecting droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting droplets without moving the recording head There is a type image forming apparatus.

  In the present application, “image forming apparatus” means an apparatus that forms an image by ejecting ink onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, In addition, “image formation” not only applies an image having a meaning such as a character or a figure to a medium but also applies an image having no meaning such as a pattern to the medium (simply applying a droplet to the medium). It also means to land on. The “ink” is not limited to the ink, but is used as a general term for all liquids that can perform image formation, such as a recording liquid, a fixing processing liquid, and a liquid.

  In a serial type ink jet recording apparatus, especially when the recording paper is wide, it is necessary to increase the number of nozzles of the recording head in order to perform high-speed recording, but increasing the number of nozzles per recording head is a production In addition, there is a problem in terms of controllability, controllability, etc., and the entire head must be replaced due to a failure of one nozzle, resulting in high replacement costs.

  Therefore, by arranging a plurality of recording heads in a staggered manner, the number of nozzles in the paper feed direction that can be recorded per scan is substantially increased to improve the recording speed. However, as the number of heads increases, the number of adjustment steps such as adjustment of the position of the recording head after it is mounted on the carriage increases, or the recording head print position is corrected by image processing based on complex control. Will have to be done.

For example, when a plurality of recording heads are arranged in the sub-scanning direction (paper feeding direction) to make the total length of the nozzle row relatively long, the difference in the inclination of the nozzle row for each head adversely affects the printing result. Specifically, when the print row by the rear end portion of the first nozzle row and the print row by the front end portion of the second nozzle row are overlapped, if the nozzle row is inclined, the print rows are positioned at these print rows. Deviation occurs, and a normal printing result cannot be obtained, and in particular, a defect such as a ruled line shift occurs in a black line image.

  For this reason, conventionally, there has been known one in which the work efficiency of the position adjustment work is improved by mounting a replaceable module in which a plurality of recording heads are arranged on a carriage (Patent Documents 1 and 2).

JP 2005-297554 A JP 2006-188013 A

  However, in the above-described conventional head arrangement in which a replaceable head module in which a plurality of heads are arranged is mounted on a carriage, when bidirectional printing is performed in a mixed color printing mode using a color head, for example, the carriage is unidirectional. When moving to, a black dot is formed by overprinting in the order of cyan, yellow, and magenta, but when moving in the reverse direction, it is overprinted in the order of magenta, yellow, and cyan, resulting in a bidirectional color difference. Therefore, in the mixed color printing mode, there is a problem that productivity is reduced and unidirectional printing has to be performed. In addition, when performing unidirectional printing in such a mixed-color printing mode, it is necessary to overprint the color ink, so that the head position accuracy and ink landing accuracy are required more than normal printing. There is a problem.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and reduces the head replacement cost, maintains the ruled line linearity during single color printing, and suppresses color misregistration and color difference variation during mixed color printing, thereby achieving high quality images. The purpose is to enable recording.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A plurality of head modules are detachably mounted on a carriage that is reciprocally scanned,
Each head module includes a plurality of heads having a plurality of nozzle rows for discharging droplets,
In the plurality of head modules,
A first head module in which a plurality of heads that discharge droplets of the same color are arranged side by side in the main scanning direction with their positions shifted in the sub scanning direction;
The plurality of heads includes a second head module arranged at the same position in the sub-scanning direction and arranged in the main scanning direction.

  Here, a plurality of the second head modules may be arranged in the main scanning direction while being displaced in the sub scanning direction.

  The plurality of heads of the second head module may be configured to eject color droplets.

  Further, the plurality of heads of the second head module can eject droplets of different colors, and the nozzle rows for ejecting droplets of each color can be arranged symmetrically in the main scanning direction.

  Further, the plurality of heads of the first head module include a pair of heads arranged in the main scanning direction with two heads shifted in the sub-scanning direction by one half of a dot interval that can be printed in one main scanning by one head. A plurality of components can be arranged in the main scanning direction while being shifted in the sub-scanning direction.

  According to the image forming apparatus of the present invention, a plurality of head modules are detachably mounted on a carriage that is reciprocally scanned, and each head module includes a plurality of heads having a plurality of nozzle rows that eject droplets. The head module includes a first head module in which a plurality of heads that discharge droplets of the same color are arranged in the main scanning direction and shifted in the sub scanning direction, and a plurality of heads are arranged in the sub scanning direction. Since it is configured to include the second head module arranged at the same position in the main scanning direction, while maintaining the ruled line linearity at the time of monochromatic printing, it also suppresses color deviation and color difference variation at the time of mixed color printing, High-quality image recording can be performed. Also, replacement in module units is possible, and the cost for head replacement can be reduced.

1 is an explanatory perspective view illustrating an overall configuration of an ink jet recording apparatus as an image forming apparatus according to the present invention. 2 is a schematic plan view of a mechanism unit of the recording apparatus. FIG. FIG. 2 is a schematic perspective view illustrating an example of a carriage of the recording apparatus. It is a perspective explanatory view of the first head module. It is a perspective explanatory view of the second head module. It is a perspective explanatory view of a head. It is a plane explanatory view explaining the arrangement of the head module and the head on the carriage. It is explanatory drawing explaining the nozzle row arrangement | positioning of one head. It is a plane explanatory view explaining the head arrangement of the first head module. It is a plane explanatory view explaining the head arrangement of the second head module.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an ink jet recording apparatus as an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is an explanatory perspective view illustrating the overall configuration of the recording apparatus, FIG. 2 is an explanatory schematic plan view of a mechanism unit of the recording apparatus, and FIG. 3 is an explanatory schematic perspective view illustrating an example of a carriage of the recording apparatus. is there.

  The ink jet recording apparatus is a serial type ink jet recording apparatus, and includes a recording apparatus main body 1 and a support base 2 that supports the recording apparatus main body 1.

  Inside the recording apparatus main body 1, guide rods 3 and guide rails 4 are spanned on both side plates (not shown), and a carriage 5 is placed on these guide rods 3 and guide rails 4 in the direction indicated by the arrow A in FIG. (Main scanning direction) is slidably held. The guide rail 4 is configured such that a sub guide roller 6 rotatably supported by the carriage 5 abuts on the guide rail 4.

  The main scanning mechanism that moves and scans the carriage 3 is disposed on one side in the main scanning direction, a driving pulley 12 that is rotationally driven by the driving motor 11, and on the other side in the main scanning direction. A driven pulley 13 and a timing belt (belt member) 14 wound around the drive pulley 12 and the driven pulley 13 are provided. The driven pulley 13 is tensioned outward (in a direction away from the drive pulley 12) by a tension spring.

  The carriage 5 is detachably mounted with a first head module 21 and two second head modules 22A and 22B.

  In the first head module 21, four heads 31k1, 31k2, 32k3, and 32k4 that discharge black (K) ink droplets (referred to as “head 31k” when not distinguished) are arranged. The second head module 22A includes two heads 31ym1 each having a nozzle array for discharging yellow (Y) and magenta (M) ink droplets, and a head 31c1 having each nozzle array for discharging cyan (C) ink droplets. Are arranged, and the second head module 22B has two heads 31ym2 each having nozzle arrays for discharging yellow (Y) and magenta (M) ink drops, and each nozzle array for discharging cyan (C) ink drops. The head 31c2 is arranged (when the heads 31ym1 and 31ym2 are not distinguished from each other, they are referred to as “head 31ym”, and when the heads 31c1 and 31c2 are not distinguished from each other, they are referred to as “head 31c”). When the heads 31k, 31ym, and 31c are not distinguished, they are referred to as “head 31”.

  As shown in FIG. 4, the first head module 21 is a unit in which four heads 31 k are paired and positioned on the module holder 24 and fixed by adhesion or the like. Here, the head mounted on the first head module is not limited to the one that ejects black (K) ink droplets, but the color that is printed with a single color is high, and is particularly often used for the formation of line drawings. It is preferable to mount a head for discharging the ink droplets. As shown in FIG. 2, in a configuration in which two heads are connected in the sub-scanning direction and a wide width corresponding to two heads is recorded at once, a deviation between the heads appears remarkably in an image particularly in the case of a line drawing. Therefore, it is effective for high-quality recording to provide a head that is displaced in the sub-scanning direction like the first head module 21 with high positional accuracy on one head module. The image quality does not deteriorate.

  As shown in FIG. 5, the second head module 22 is obtained by positioning the two heads 31ym and 31c on the module holder 25 and fixing them by bonding or the like. Since color ink is mainly used for image printing, a shift between colors appears more conspicuously in the deterioration of image quality than a shift between heads of the same color. For this reason, the head for ejecting yellow (Y), magenta (M), and cyan (C) ink droplets is fixed to the second head module 22 without shifting its position, so that even when the head module is replaced, the inter-color shift occurs. Therefore, a high-quality color image can always be obtained.

  Here, the head modules 22A and 22B may be configured integrally. However, since the number of heads of one module increases, the number of heads that are wasted when the head module is replaced increases, as shown in FIG. It is preferable to divide into two.

  The head 31 has two nozzle rows as will be described later, and is an integrated head section 51 and a buffer tank section (sub tank section) 52 for supplying ink to the head section 51 as shown in FIG. Yes, ink corresponding to each nozzle row is supplied from the ink cartridge 9 through the supply ports 53a and 53b.

  On the other hand, in the recording area of the main scanning area of the carriage 5, the paper 10 is moved in a direction orthogonal to the main scanning direction of the carriage 5 by a paper feed mechanism (not shown) (the arrow B direction in FIG. 1, the paper conveyance direction in FIG. 2). ) And is intermittently conveyed by the platen member 19. The platen member 19 is disposed on the carriage 5 so as to face the recording heads 31 and 32 at least in the recording area along the main scanning area.

  In addition, a maintenance / recovery mechanism 8 that performs maintenance / recovery of the heads 31 and 32 is disposed in one end side region of the main scanning region. The maintenance / recovery mechanism 8 includes, on the base member 40, a first unit 41 corresponding to each head 31 of the first head module 21 and a second unit 42 corresponding to each head 32 of the second head modules 22A and 22B. The first and second units 41 and 42 are provided with a cap member 43 for capping the nozzle surface of each head, a wiper member for wiping the nozzle surface, and the like.

  Further, a main cartridge 9 containing ink of each color supplied to each head 31 and 32 is attached to and detached from the recording apparatus main body 1 outside the carriage movement area in the main scanning direction or below the other end side of the carriage movement area. Can be installed freely.

  In this ink jet recording apparatus, by moving the carriage 5 in the main scanning direction and intermittently feeding the paper 10 in the sub scanning direction, the heads 31 and 32 are driven according to the image information to discharge the droplets. A required image is formed on the paper 10.

Next, the head arrangement in the first and second head modules will be described with reference to FIGS.
As described above, the first head module 21 and the two second head modules 22A and 22B are detachably disposed on the carriage 5, and the four heads 31 are provided on the first head module 21 and the second head module. Three heads 31 are positioned and arranged on 22A and 22B, respectively.

  As a result, head replacement can be performed in units of head modules, and the cost of head replacement is reduced.

  Here, as shown in FIG. 8, the head 31 has two nozzle rows 30a and 30b in which a plurality of nozzles 30n for discharging droplets are arranged in a staggered manner, and the nozzle rows 30a and 30b are described above. As described above, different colors of ink can be supplied from the supply ports 53a and 53b. Accordingly, the black head 31k and the cyan head 31c are supplied with the same color ink to the two nozzle rows 30a and 30b, and the yellow and magenta head 31ym are separately provided with the two nozzle rows 30a and 30b. The magenta ink is supplied.

  In the example of FIG. 8, the head 31 is formed with an interval (nozzle pitch) Np of the nozzles 30n corresponding to 150 dpi, and the nozzle rows 30a and 30b are half the nozzle pitch in the sub-scanning direction (corresponding to 300 dpi in this example). They are staggered. As a result, a single head 31 can form dots at 300 dpi.

  As shown in FIG. 9, in the first head module 21, the heads 31k1 and 31k2 are shifted in the sub-scanning direction by half the interval of dots that can be printed by one main scan with one head 31. In the example, they are arranged in the main scanning direction with a shift of 1/4 of the nozzle pitch. Similarly, the heads 31k3 and 31k4 are shifted in the sub-scanning direction by half the interval between dots that can be printed in one main scan by one head 31, that is, in this example, the nozzle pitch is shifted by 1/4. Arranged in the scanning direction. As a result, the heads 31k1 and 31k2 and the heads 31k3 and 31k4 can record at a recording density equivalent to 600 dpi.

  The pair of heads 31k1 and 31k2 and the pair of heads 31k3 and 31k4 are shifted in the sub-scanning direction and arranged in the main scanning direction. In FIG. 9, the uppermost nozzle in the heads 31k1 and 31k2 and the lowermost nozzle in the heads 31k3 and 31k4 are arranged so as to overlap each other. Alternatively, the two may be formed apart by a distance equivalent to 600 dpi, which is the same as the recording density, or conversely, a plurality of nozzles may be stacked.

  In other words, in the first head module 21, a plurality of heads 31k1 to 31k4 that discharge droplets of the same color are arranged side by side in the main scanning direction while shifting their positions in the subscanning direction. A pair of heads (31k1, 31k2, 31k3, 31k4) arranged in the main scanning direction with a shift of half the dot interval that can be printed by one main scanning in the scanning direction in the main scanning direction are shifted in the sub scanning direction. A plurality are arranged in the direction.

  Thus, monochrome printing can be performed with two nozzle row widths in one main scan, and the recording speed of monochrome printing can be increased. At the same time, the overall nozzle pitch when performing black printing is ¼ of the nozzle pitch of one head, and high-density recording can be performed (recording accuracy can be improved).

  On the other hand, the second head modules 22A and 22B are arranged with their positions shifted in the sub-scanning direction. In the second head module 22 (22A, 22B), as shown in FIG. 10, the two heads 31ym and the head 31c are arranged with their positions in the sub-scanning direction aligned. Thus, color printing can be performed with two nozzle row widths in one main scan, and the recording speed of color printing can be improved.

  Here, the two heads 31ym and 31c of the second head module 22 are assigned to the yellow nozzle rows 30y1 and 30y2 and the magenta nozzle rows 30m1 and 30m2 with respect to the head 31ym, and main scanning is performed with the cyan head 31c as the center. The color arrangement is targeted in the direction. Accordingly, when bidirectional printing is performed, for example, the nozzle rows 30y1 and 30c1 (or 30c2) are used in the order of the nozzle row 30m1 in the forward path, and the nozzle rows 30y2, 30c2 (or 30c1) and the nozzle row 30m2 are used in the order of the forward path. By using it, the color superposition order becomes the same, and the bidirectional color difference can be reduced.

  As described above, a plurality of head modules are detachably mounted on a carriage that is reciprocally scanned, and each head module includes a plurality of heads having a plurality of nozzle arrays that eject droplets. The first head module in which a plurality of heads that discharge color droplets are arranged in the main scanning direction with their positions shifted in the sub-scanning direction, and the plurality of heads are in the main scanning with the same position in the sub-scanning direction. Since the configuration includes the second head modules arranged side by side in the direction, it is possible to improve the accuracy (recording density) and productivity (recording speed) of monochromatic printing and reduce the cost when replacing the head.

DESCRIPTION OF SYMBOLS 1 Recording device main body 2 Support stand 3 Guide rod (guide member)
5 Carriage 21 First head module 22, 22A, 22B Second head module 30n Nozzle 30a, 30b Nozzle row 31, 31k1-31k4, 31ym1, 31c1, 31ym2, 31c2, 31ym, 31c Head

Claims (5)

A plurality of head modules are detachably mounted on a carriage that is reciprocally scanned,
Each head module includes a plurality of heads having a plurality of nozzle rows for discharging droplets,
In the plurality of head modules,
A first head module in which a plurality of heads that discharge droplets of the same color are arranged side by side in the main scanning direction with their positions shifted in the sub scanning direction;
An image forming apparatus comprising: a second head module, wherein the plurality of heads are arranged side by side in the main scanning direction with the same position in the sub-scanning direction.   The image forming apparatus according to claim 1, wherein a plurality of the second head modules are arranged in the main scanning direction while being shifted in the sub-scanning direction.   The image forming apparatus according to claim 1, wherein the plurality of heads of the second head module eject color droplets.   4. The plurality of heads of the second head module eject droplets of different colors, and nozzle rows that eject droplets of each color are arranged symmetrically in the main scanning direction. An image forming apparatus according to claim 1.   The plurality of heads of the first head module sub-scans a pair of heads arranged in the main scanning direction by shifting two heads in the sub scanning direction by one half of the dot interval that can be printed in one main scanning by one head. 5. The image forming apparatus according to claim 1, wherein a plurality of the image forming apparatuses are arranged in the main scanning direction while being shifted in a direction.

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