JP2009161344A - Image forming device and belt device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein it is difficult to maintain the planarity of a belt between a drive roller and a driven roller and to regulate the pressing amount of the driven roller with respect to the extent of belt skew. <P>SOLUTION: An image forming device comprises a conveyance belt 43 wound between the column-shaped (or cylinder-shaped) drive roller 42a and driven roller 42b. A belt skew preventing means 8 is arranged near the driven roller 42b. The belt skew preventing means 8 rotatably supports column-shaped (or cylinder-shaped) auxiliary rollers 81, 81 between roller support members 83a, 83b provided above a roller holding member 82 and presses the two auxiliary rollers 81, 81 against the conveyance belt 43 from the outside to cause the conveyance belt 43 to generate skewing force toward a central part from opposite end sides in a conveyance belt width direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a belt apparatus.

  As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, and a complex machine of these, for example, an ink jet recording apparatus is known as an image forming apparatus of a liquid discharge recording method using a recording head for discharging ink droplets. . This liquid ejection recording type image forming apparatus ejects a recording head or a linear drop onto a conveyed paper to form an image (recording, printing, printing, and printing are also synonymous). Serial type image forming device that forms an image by ejecting droplets while the recording head moves in the main scanning direction, and a line type that forms images by ejecting droplets without the recording head moving There is a line type image forming apparatus using a head. As the image forming apparatus, there are various apparatuses such as an apparatus for forming an image by an electrophotographic method in addition to droplet discharge.

  In the present application, the “image forming apparatus” is an apparatus that forms an image by attaching an image forming agent such as ink to a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. Or, it means the medium itself, and “image formation” not only gives an image having a meaning such as a character or a figure to the medium but also an image having no meaning such as a pattern. (For example, when ink is used, it simply means that a droplet is landed on a medium). 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. The term “paper” is not limited to paper, but includes the above-described OHP sheet, cloth, and the like, and means that ink droplets adhere to the recording medium, recording medium, recording paper, recording It is used as a general term for what includes what is called paper.

  In an ink jet recording apparatus as an image forming apparatus, for example, a sheet is transported using a belt device in which an endless conveying belt is wound between a driving roller and a driven roller. In this case, it is necessary to suppress the deviation of the conveying belt in order to ensure the droplet landing position accuracy.

Therefore, as a conventional belt device, as described in, for example, Patent Documents 1 to 3, an endless conveyance belt is wound around a driving roller and driven rollers or a plurality of driven rollers, and the belt is arranged on the inner peripheral surface side of the belt. By pressing the driven roller and using a tapered roller as one or a plurality of driven rollers, and selecting the arrangement, a biasing force is generated from the inner side to the outer side of the conveying belt in the width direction of the conveying belt. Alternatively, there is known a configuration in which a shift force is generated in the opposite direction between two driven rollers.
JP-A-5-124744 JP 2001-278430 A Japanese Patent No. 3720765

  However, in the above-described conventional belt device, the driven roller around which the conveyor belt is wound has a tapered shape so that a driving force is generated from the inner side to the outer side in the width direction of the conveyor belt. The flatness of the conveyor belt cannot be obtained between the roller and the driven roller, and when the liquid droplet is ejected between the driving roller and the driven roller to form an image, the liquid droplet landing position shifts and a normal image is generated. Can't form.

  Further, since the driven roller is pressed from the inside of the conveying belt, it is difficult to adjust the pressing amount of the driven roller with respect to the degree of belt deviation, and it is difficult to cope with changes with time.

  The present invention has been made in view of the above problems, and can maintain the flatness of the belt between the driving roller and the driven roller, and can easily adjust the deviation force according to the degree of deviation of the belt. The purpose is to do so.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head for discharging droplets;
An endless conveyance belt that conveys the paper facing the recording head, and
The conveying belt is hung at least between a columnar or cylindrical driving roller and a columnar or cylindrical driven roller,
Auxiliary rollers that rotate following the circumferential movement of the conveyor belt from the outside are pressed against the conveyor belt,
The auxiliary roller is configured to generate a shifting force toward the central portion from both ends in the width direction of the conveyor belt with respect to the conveyor belt.

  Here, the auxiliary roller may be two columnar or cylindrical rollers, and the roller shaft may be arranged to be inclined in the width direction of the transport belt.

  In this case, the two auxiliary rollers may be arranged so that at least one of a pressing amount and a pressing angle with respect to the transport belt can be adjusted.

  Further, the auxiliary roller is two tapered rollers, and can be configured such that the relatively large diameter side is located on the outer side in the width direction of the conveying belt than the small diameter side.

  The auxiliary roller may be a roller having a relatively large diameter on the outer side in the width direction of the conveyor belt and a small diameter on the center side.

The belt device according to the present invention is
An endless belt,
At least a columnar or cylindrical driving roller and a columnar or cylindrical driven roller around which the belt is wound,
An auxiliary roller that is pressed against the belt from the outside and rotates following the circumferential movement of the belt,
The auxiliary roller is configured to generate a shifting force toward the central portion from both ends in the width direction of the belt with respect to the belt.

  According to the image forming apparatus and the belt device of the present invention, since the auxiliary roller that is pressed against the belt from the outside and generates a biasing force toward the center from both ends in the width direction of the belt is provided. The flatness of the belt between the roller and the driven roller is maintained, and the auxiliary roller is pressed from the outside of the belt, so that it is possible to easily adjust the shift force according to the degree of belt shift. .

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is a schematic configuration diagram illustrating the overall configuration of the image forming apparatus, FIG. 2 is a plan explanatory diagram of the apparatus, and FIG. 3 is a schematic perspective explanatory diagram of a transport unit of the apparatus.

  This image forming apparatus is a line type image forming apparatus, and includes an apparatus main body 1, a paper feed tray 2 on which paper P is stacked and fed, a paper discharge tray 3 on which printed paper P is discharged and stacked, and paper P A transport unit 4 that transports the paper from the paper feed tray 2 to the paper discharge tray 3, a head unit 5 that discharges and prints droplets on the paper P that is transported by the transport unit 4, and a head unit after printing is completed or at a required timing. And a cleaning device 6 which is a maintenance / recovery mechanism that performs maintenance / recovery of each head 5.

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

  The transport unit 4 includes a driving roller 41a, a driven roller 41b, and an endless transport belt 43 that is wound around these rollers 41a and 41b. As shown in FIG. 3, a plurality of holes 43 a are formed in the transport belt 43, and a suction fan 44 that sucks the paper P is disposed below the transport belt 43. Further, conveyance guide rollers 42a and 42b are held by guides (not shown) on the driving roller 41a and the driven roller 41b, respectively, and abut against the belt 43 by their own weight.

  When the driving roller 41 a is rotated by a motor (not shown), the conveyance belt 43 rotates and the sheet P is sucked onto the conveyance belt 43 by the suction fan 44 and is conveyed by the rotation movement of the conveyance belt 43. The driven roller 41 b and the conveyance guide rollers 42 a and 42 b are rotated by the conveyance belt 43, and the auxiliary roller 45 is also rotated by the conveyance belt 43.

  Further, the transport unit 4 is provided with a later-described shift prevention means 8 including an auxiliary roller 81 that prevents the transport belt 43 from shifting.

  A head portion 5 composed of a recording head that discharges droplets to be printed on the paper P is disposed above the transport unit 4 so as to be movable in the direction of arrow A. The head portion 5 slides above the cleaning device 6 during the maintenance / recovery operation (during cleaning).

  The head unit 5 is configured by arranging five heads 51 for discharging droplets per row over almost the entire width of a sheet. From the upstream side in the paper transport direction, the first row (also referred to as a row) is heads 51a1, 51a2, 51a3, 51a4, 51a5, and the second row (also referred to as b row) is heads 51b1, 51b2, 51b3, 51b4, 51b5. The third column (also referred to as column c) includes heads 51c1, 51c2, 51c3, 51c4, 51c5, and the fourth column (also referred to as column d) includes heads 51d1, 51d2, 51d3, 51d4, and 51d5. . When the heads in each row are collectively referred to, for example, the head 51 in the row a is represented as “head 51a”.

  The heads 51a to 51d in the first to fourth rows are arranged in a staggered manner. Each head 51 has two nozzle rows in which a plurality of nozzles are arranged. Yellow (Y) is used in one nozzle row of each head 51 of the first row head 51a and the second row head 51b. The magenta (M) color droplets are ejected from the nozzle rows of the second row, cyan (C) in one nozzle row of the heads 51c in the second row and each head 51 in the second row head 51c, and black in the other nozzle row. An image for one line can be formed by ejecting droplets of each color of (K) and adopting a staggered arrangement.

  The configuration of the head unit is not limited to these examples, and two head units 5 are arranged so that one color ink droplet is ejected from each of the two nozzle rows of each head 51. Can be doubled as compared to the above example.

  In the head unit 5, distributors 52 a to 52 d, which are distributors for supplying ink of a desired color to each head 51, are arranged above each head 51, and the distributor 52 and the head 51 are connected by a supply tube 53. Has been. A sub tank 54 is disposed on the upstream side of the distributor 52, and ink is supplied to the head 51 due to a water head difference. Further, an ink main tank (not shown) is disposed on the upstream side of the sub tank 54, and ink is supplied to each through a supply tube.

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

  The maintenance / recovery mechanism (cleaning device) 6 corresponds to each of the heads 51 in the first to fourth rows of the head unit 5, and includes five cleaning units 61a1 to 61a5 and 61b1 to the first to fourth rows, respectively. 61b5, 61c1 to 61c5, 61d1 to 61d5 are arranged in a staggered pattern. The notation of each part of the cleaning device 6 is the same as in the case of the head part 5.

  Under each cleaning means 61, suction pumps 62 (62a, 62b, 63c, 64d) for sucking ink from the head 51 are arranged.

  Further, in this image forming apparatus, after the printing is finished, when the ink is sucked from the nozzle while the head 51 that discharges the droplet is capped by the cleaning unit 61, or the ink attached to the nozzle surface of the head 51 is cleaned. When cleaning is performed by the means 61, after the printing is stopped, the entire transport unit 4 rotates in the direction of arrow B in FIG. 1 with the driven roller 41b as a fulcrum, so that the space between the head unit 5 is larger than that during image formation. In this way, a space for moving the head unit 5 is secured. At this time, the conveyance guide portion 7 disposed on the upper portion of the cleaning device 6 is also rotated upward in the direction of the arrow C at the fulcrum 71, and the upper portion of the cleaning device 6 is opened.

  Then, after the transport unit 4 and the transport guide portion 7 are released (released), the head portion 51 moves in the paper passing direction (the direction indicated by arrow A), is stopped above the cleaning device 6, and the cleaning means 61 is moved. The head moves up and shifts to a cleaning operation (maintenance recovery operation) of each head 51.

Next, belt slip prevention means in the first embodiment of the present invention applied to this image forming apparatus will be described with reference to FIGS. 4 and 5. FIG. 4 is a side view for explaining the relationship between the rollers and the belt of the transport unit, and FIG. 5 is a front view for explaining the deviation preventing means.
First, as described above, the endless conveyance belt 43 is wound around a columnar (or cylindrical roller) drive roller 42a and a driven roller 42b. As a result, the conveyance belt 43 is flat between the driving roller 42a and the driven roller 42b that form an image by discharging droplets from the head unit 5 (the nozzle surface of the head 51 and the conveyance surface are parallel to each other). State) can be secured.

  The deviation prevention means 8 for preventing the deviation of the conveying belt 43 is disposed in the vicinity of the driven roller 42b, and is provided between the roller support members 83a and 83b provided on the roller holding member 82. The auxiliary rollers 81 and 81 are rotatably supported, and the two auxiliary rollers 81 and 81 are pressed against the conveyor belt 43 from the outside.

  Here, the support position of the roller support member 83a that supports both ends of the two auxiliary rollers 81 and 81 in the belt width direction is set higher than the support position of the roller support member 83b that supports the center side in the belt width direction. . As a result, the two auxiliary rollers 81, 81 are both pressed against the conveyor belt 43 in the direction indicated by the arrow G in a state where the belt center side is inclined with respect to both ends of the belt. A shifting force is generated from both ends in the width direction toward the center (in the direction of arrow F in FIG. 5).

  Therefore, when the conveyor belt 43 is rotated by the rotation of the driving roller 42a, a shift force from the both ends in the width direction toward the center is applied to the conveyor belt 43, so that the conveyor belt 43 is on one end side. It is reduced to stop by. At this time, since the auxiliary roller 81 is disposed in the vicinity of the driven roller 42a and is pressed against the conveyor belt 43 from the outside of the conveyor belt 43, the winding amount of the conveyor belt 43 around the driven roller 42b increases, and the torque increases. As a result, the slippage of the conveyor belt 43 and the driven roller 42b is reduced. A similar effect can be obtained when the auxiliary roller 81 is disposed in the vicinity of the drive roller 42a.

  As described above, the auxiliary roller that is pressed against the belt from the outside and generates a biasing force toward the central portion from both ends of the belt in the width direction of the belt is provided. This makes it possible to maintain the flatness of the belt using the roller, and because the auxiliary roller is pressed from the outside of the belt, it is easy to adjust the shifting force by the auxiliary roller according to the degree of belt shifting To be able to do so.

Here, a means for adjusting the offset force with respect to the belt by the auxiliary roller will be described with reference to FIG. 6A is a front explanatory view for explaining the adjustment mechanism of the auxiliary roller, FIG. 6B is a left side explanatory view thereof, and FIG. 6C is a right side explanatory view thereof.
The second roller support members 83a1 and 83b2 are attached to the first roller support members 83a1 and 83b1 attached to the roller holding member 82 so as to be movable in the height direction by the long holes 84a and 84b and screws 85a and 85b, respectively. .

  Then, the shaft 81a of the auxiliary roller 81 is attached to the mounting hole 86a with the screw 87 on the second roller support member 83a2, and the shaft 81b of the auxiliary roller 81 is fitted into the recess 86b and attached to the second roller support member 83b2. Yes.

  Since it comprised in this way, the height of the auxiliary | assistant roller 81 is adjusted by moving the up-and-down position with respect to the 1st roller support member 83a1 and 83b1 of the 2nd roller support member 83a2 and 83b2 to the arrow direction H1 and H2 direction. The amount of pressing of the auxiliary roller 81 against the conveyor belt 43 can be adjusted. Further, by changing the height of the second roller support member 83a2 relative to the first roller support member 83a1, the auxiliary roller 81 has the other shaft 81a side in the direction indicated by the arrow J with respect to the shaft 81b on the second roller support member 83b2 side. Since it rotates (the angle is shaken), the pressing angle of the auxiliary roller 81 against the conveyor belt 43 can be adjusted.

  In this way, by adjusting the height and angle of the auxiliary roller so that the pressing amount can be adjusted, the shift force in the direction toward the appropriate belt center according to the aging of the conveyor belt, the conveyance speed, etc. can be adjusted. To prevent the conveyor belt from shifting.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory front view of the slip prevention means in the same embodiment.
Here, two tapered rollers are used as the auxiliary rollers 181 and 181, and these auxiliary rollers 181 and 181 have a roller holding member 82 such that the larger diameter side is relatively outside the smaller diameter side than the small diameter side. The roller support members 83a and 83a attached to the shaft are rotatably held by a shaft 88 that is horizontally mounted. Even if comprised in this way, the effect similar to the said 1st Embodiment can be acquired.

Next, a third embodiment of the present invention will be described with reference to FIG. In addition, FIG. 8 is front explanatory drawing of the slip prevention means in the same embodiment.
Here, one auxiliary roller 281 having a drum-shaped cross section along the roller axis direction, a relatively large diameter on the outer side in the belt width direction and a small diameter on the center side is used. The roller support members 83a and 83a attached to the member 82 are disposed so as to be rotatably supported by a shaft 88 placed horizontally. Even if comprised in this way, the effect similar to the said 1st Embodiment can be acquired.

  In the above embodiment, an example in which the present invention is applied to a belt device that transports paper in an image forming apparatus that forms an image by ejecting liquid droplets has been described. The present invention can also be applied to a belt device used in the device.

1 is a schematic configuration diagram illustrating an overall configuration of an example of an image forming apparatus according to the present invention. It is a plane explanatory view of the device. It is an outline perspective explanatory view of a conveyance unit similarly. It is side surface explanatory drawing explaining the relationship of the roller and belt of a conveyance unit with which it uses for description of the belt slip prevention means in 1st Embodiment of this invention. It is front explanatory drawing of a slip prevention means similarly. It is explanatory drawing with which it uses for description of the adjustment mechanism of a shift | offset | difference prevention means similarly. It is front explanatory drawing with which it uses for description of the belt slippage prevention means in 2nd Embodiment of this invention. It is front explanatory drawing with which it uses for description of the belt slip prevention means in 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 4 ... Conveyance unit 5 ... Head part 6 ... Cleaning apparatus (maintenance recovery mechanism)
8 ... Belt slip prevention means 51a to 51d ... Head 81, 181, 281 ... Auxiliary roller

Claims (6)

A recording head for discharging droplets;
An endless conveyance belt that conveys the paper facing the recording head, and
The conveying belt is hung at least between a columnar or cylindrical driving roller and a columnar or cylindrical driven roller,
Auxiliary rollers that rotate following the circumferential movement of the conveyor belt from the outside are pressed against the conveyor belt,
The image forming apparatus according to claim 1, wherein the auxiliary roller generates a biasing force toward the central portion from both ends in the width direction of the transport belt with respect to the transport belt.   The image forming apparatus according to claim 1, wherein the auxiliary roller is two columnar or cylindrical rollers, and a roller shaft is disposed to be inclined in the width direction of the conveyance belt. apparatus.   The image forming apparatus according to claim 2, wherein the two auxiliary rollers are arranged so that at least one of a pressing amount and a pressing angle with respect to the conveyance belt can be adjusted.   The image forming apparatus according to claim 1, wherein the auxiliary rollers are two tapered rollers, and are arranged such that a relatively large diameter side is located on an outer side in a width direction of the conveying belt than a small diameter side. An image forming apparatus.   2. The image forming apparatus according to claim 1, wherein the auxiliary roller is a roller having a relatively large diameter on the outer side in the width direction of the transport belt and a small diameter on the center side. An endless belt,
At least a columnar or cylindrical driving roller and a columnar or cylindrical driven roller around which the belt is wound,
An auxiliary roller that is pressed against the belt from the outside and rotates following the circumferential movement of the belt,
The belt device according to claim 1, wherein the auxiliary roller generates a biasing force toward the central portion from both ends of the belt in the width direction with respect to the belt.

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