JP2008074022A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is simplified in a holding structure of star wheels and a damper arm. <P>SOLUTION: The first star wheel 37, a first coil spring shaft 57 erecting and supporting the second star wheel 38, and a second coil spring shaft 58 are supported by a star wheel base 53 integrally formed with synthetic resin. The first coil spring shaft 57 is directly engaged with a first spring engagement part 59 formed in the star wheel base 53, and the second coil spring shaft 58 is directly engaged with a second spring engagement part 60 formed in the star wheel base 53. The damper arm 51 is also directly held by an arm holder 61 formed in the star wheel base 53. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus capable of printing up to the end of recording paper.

  As an example of an image forming apparatus, an ink jet printer that forms an image by ejecting ink from a print head onto a recording sheet is widely used. In general, an inkjet printer includes a first transport unit that transports recording paper held in a paper feed tray to the vicinity of a print head, and a second transport unit that transports recording paper on which an image is formed by the print head to a paper discharge tray. And the recording paper is conveyed. Since the ejected ink is not completely dried when the recording paper passes through the second conveying section, the second conveying section does not damage the formed image on the image forming surface side of the recording paper. Is provided with a star wheel which is brought into point contact with the recording paper.

  5 and 6 show a state in which the star wheels 137 and 138 arranged in two rows and the support structure thereof in the conventional ink jet printer are viewed from the discharge tray side. In the figure, the base plate 153, the first star wheel 137, and the second star wheel 138 have a configuration that is substantially symmetrical with respect to the central portion of the base plate 153, and therefore, only one half of the base plate 153 is shown in the drawing. Yes. The first star wheel 137 and the second star wheel 138 are supported by the base plate 153 via the first wheel holder 171 and the second wheel holder 172. The base plate 153 is formed by pressing a metal plate, and the first wheel holder 171 and the second wheel holder 172 are made of synthetic resin.

  The first star wheel 137 is stretched and supported rotatably by the first coil spring shaft 157 in a biased state toward the first paper discharge roller. Both ends of the first coil spring shaft 157 are engaged with spring engaging portions 173 provided on the first wheel holder 171. Similarly, the second star wheel 138 is rotatably supported by the second coil spring shaft 158 in a biased state toward the second paper discharge roller. Both ends of the second coil spring shaft 158 are engaged with spring engaging portions 174 provided on the second wheel holder 172. A plurality of first star wheels 137 and second star wheels 138 are arranged side by side in a direction orthogonal to the transport direction in the transport direction so that recording papers of various sizes can be transported smoothly. For example, since only one side of the base plate is shown in FIG. 5, considering the portions not shown, the six first star wheels 137 are arranged in a line in a direction perpendicular to the recording paper conveyance direction. Accordingly, the six first wheel holders 171 are also arranged in a line in the above direction. Similarly, four second star wheels 138 are arranged in a line in the above direction, and accordingly, four second wheel holders 172 are also arranged in a line.

  In addition, an arm holding base 181 for holding a damper arm that applies a load to the rotation of the first paper discharge roller is coupled to the end of the base plate 153. The arm holding base 181 has a damper arm holding portion 182 for holding the damper arm so as to be rotatable, and is formed by pressing a metal plate in the same manner as the base plate 153.

As a conventional technique different from such an ink jet printer, Patent Document 1 discloses an ink jet printer whose structure is simplified by molding a star wheel base integrally with a front cover of a housing. . Patent Document 2 discloses an ink jet printer that prevents buckling of the leading edge of a recording sheet by two rows of star wheels. Patent Document 3 discloses an ink jet printer configured to support a plurality of star wheels by a single elastic shaft.
Japanese Patent Laid-Open No. 2001-253612 JP 2006-15521 A JP 2000-335801 A

  However, in the conventional ink jet printer having the star wheel support structure shown in FIGS. 5 and 6, in order to support the damper arm, the first star wheel 137, and the second star wheel, the arm holding base 181, the base plate 153, the arm holding base A connecting member such as a screw (not shown) for connecting 181 and the base plate 153, six first wheel holders 171 and four second wheel holders 172 are required. Such a complicated configuration leads to an increase in the number of parts, a complicated assembly process, and a cause of an increase in manufacturing cost of the ink jet printer. Further, in any of the above-described patent documents, it is necessary to separately provide a structure corresponding to the arm holding base 181 that holds the damper arm shown in FIG. 5, and it is difficult to achieve a significant cost reduction. .

  The present invention has been made to solve the above problems, and by simplifying the holding structure of the star wheel and the damper arm, the number of parts is reduced and the assembly process is simplified to reduce the cost. An object of the present invention is to provide an image forming apparatus capable of performing the above.

In order to achieve the above object, the invention of claim 1
A paper feed tray for holding the loaded recording paper, a first transport means for transporting the recording paper held in the paper feed tray into the apparatus, and forming an image on the recording paper transported by the first transport means Image forming means, a second transport means for transporting the recording paper on which an image is formed by the image forming means, and a paper discharge tray on which the recording paper transported by the second transport means is deposited. Prepared,
The first conveying means feeds the recording paper held in the paper feed tray to the inside of the apparatus, and the paper feeding conveys the recording paper sent by the pick roller to an image forming position by the image forming means. A roller and a pressing roller that presses the recording paper against the paper feeding roller,
The image forming unit includes: an ink cartridge filled with ink; a carrier in which the ink cartridge is mounted and reciprocating in a direction orthogonal to the conveyance direction of the recording paper; and a carrier driving unit that drives the carrier. Have
The second transport means is configured to press the first paper discharge roller for transporting the recording paper on which the image is formed downstream and the first paper discharge roller and rotate integrally with the first paper discharge roller. A shaft member;
A damper arm that contacts the side surface of the shaft member and applies a load to the rotation of the shaft member, an arm urging means that urges the damper arm toward the shaft member, and presses the recording paper against the first paper discharge roller A plurality of first star wheels, a plurality of first coil spring shafts that rotatably support the first star wheels in a biased state toward the first paper discharge rollers, and the first paper discharge rollers A second discharge roller for discharging the recording paper conveyed by the printer to the outside of the housing of the printer, a plurality of second star wheels for pressing the recording paper against the second discharge roller, and the second star wheel. An image forming apparatus having a plurality of second coil spring shafts rotatably supported in a biased state on the second paper discharge roller side;
A star wheel base that is integrally formed of synthetic resin and supports the damper arm, the first coil spring shaft, and the second coil spring shaft;
The star wheel base includes an arm holding portion that rotatably holds the damper arm, a first spring engaging portion that engages both ends of the first coil spring shaft, and both ends of the second coil spring shaft. A second spring engaging portion to be engaged,
Both ends of the first coil spring shaft are directly engaged with the star wheel base at a first spring engaging portion, and both ends of the second coil spring shaft are directly connected to the star wheel base at a second spring engaging portion. Is engaged.

The invention of claim 2
An image forming unit that forms an image on the recording paper; and a second transport unit that transports the recording paper on which the image is formed by the image forming unit to the outside of the apparatus,
The second conveying means includes a paper discharge roller that conveys the recording paper on which an image is formed downstream, a plurality of star wheels that press the recording paper against the paper discharge roller, and each star wheel that is connected to the paper discharge roller. In an image forming apparatus having a plurality of elastic shafts that are rotatably supported in a biased state on the side,
A star wheel base that is integrally formed of a synthetic resin and supports the elastic shaft;
The star wheel base has a shaft engaging portion with which both ends of the elastic shaft are engaged.

The invention of claim 3 is the image forming apparatus according to claim 2,
The second conveying means includes a shaft member into which the paper discharge roller is press-fitted and rotated integrally with the paper discharge roller, and a damper arm that contacts a side surface of the shaft member and applies a load to the rotation of the shaft member. And an arm biasing means for biasing the damper arm toward the shaft member,
The star wheel base has an arm holding portion that rotatably holds the damper arm.

  According to the first aspect of the present invention, since the star wheel base that supports the first coil spring shaft and the second coil spring shaft is integrally formed of synthetic resin, the number of parts constituting the image forming apparatus is reduced. be able to. That is, since both ends of the first coil spring shaft are directly engaged with the star wheel base at the first spring engaging portion and both ends of the second coil spring shaft are respectively directly engaged with the star wheel base in FIG. The six first wheel holders 171 and the four second wheel holders 172 as shown in FIG. Further, since the star wheel is supported by a star wheel base made of inexpensive resin molding instead of the base plate 153 made of an expensive metal plate, the manufacturing cost of the ink jet printer can be reduced. Further, since the star wheel base directly holds the damper arm, the arm holding base 181 as shown in FIG. 5 is not required, and the manufacturing cost can be further reduced.

  According to the invention of claim 2, since the star wheel base that supports the plurality of elastic shafts is integrally formed of synthetic resin, it is possible to reduce the number of parts and assembly man-hours constituting the image forming apparatus, The manufacturing cost can be reduced.

  According to the invention of claim 3, since the star wheel base directly holds the damper arm, the arm holding base 181 as shown in FIG. 5 is not necessary, and the manufacturing cost can be further reduced. Become.

  An ink jet printer as an example of an image forming apparatus according to the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an ink jet printer. The ink jet printer 1 includes a paper feed tray 2 that holds a loaded recording paper P, a transport mechanism 3 that transports the recording paper P held in the paper feed tray 2, and a recording paper transported by the transport mechanism 3. An image forming unit (image forming unit) 4 that forms an image on P, a paper discharge tray 5 on which recording paper P on which an image is formed by the image forming unit 4 is stacked, a transport mechanism 3 and an image forming unit 4 are accommodated. And a control unit that controls the transport mechanism 3 and the image forming unit 4.

  FIG. 2 shows a main configuration of the transport mechanism 3 and the image forming unit 4. Hereinafter, the conveyance mechanism 3 and the image forming unit 4 of the inkjet printer 1 will be described with reference to FIGS. 1 and 2. In the transport mechanism 3, an image is formed by the first transport mechanism (first transport unit) 3 a that transports the recording paper P held on the paper feed tray 2 to an image forming position by the image forming unit 4 and the image forming unit 4. The recording paper P is constituted by a second transport mechanism (second transport means) 3b for transporting the recording paper P to the paper discharge tray 5, a feed motor 30 for driving the first transport mechanism 3a and the second transport mechanism 3b, and the like.

  The image forming unit 4 includes an ink cartridge 40 filled with ink, a carrier 41 that reciprocates in the main scanning direction orthogonal to the conveyance direction A (sub-scanning direction) of the recording paper P while supporting the ink cartridge 40, A carrier driving motor (carrier driving means) 42 for driving the carrier 41 is used. A print head 43 that ejects ink onto the recording paper P is provided on the lower surface of the ink cartridge 40. The carrier 41 is supported by a shaft 44 disposed in parallel to the main scanning direction so as to be reciprocally movable, and is driven by the carrier drive motor 42 to move. The output of the carrier drive motor 42 is transmitted to the carrier 41 via a belt or the like. An image is formed on the recording paper P by ejecting ink from the print head 43 in synchronization with the drive of the feed motor 30 and the carrier drive motor 42 under the control of the control unit.

  The first transport mechanism 3a is disposed on the upstream side of the print head 43, and the second transport mechanism 3b is disposed on the downstream side (see FIG. 1). The first transport mechanism 3 a sends out the recording paper P placed on the paper feed tray 2 to the inside of the apparatus main body, and sends out the recording paper P sent out by the pick roller 31 to the print head 43 side. A paper feed roller 32 that presses the recording paper P against the paper feed roller 32, and the like. The second transport mechanism 3b includes a first paper discharge roller 35 that transports the recording paper P on which an image is formed to the paper discharge tray 5, and the recording paper P that has been transported by the first paper discharge roller 35 outside the casing of the printer. A second paper discharge roller 36 for discharging the paper, a first star wheel 37 for pressing the recording paper P against the first paper discharge roller 35, and a second star wheel for pressing the recording paper P against the second paper discharge roller 36. 38, a shaft member 50 that rotates integrally with the first paper discharge roller 35, a damper arm 51 that applies a load to the rotation of the shaft member 50, and an arm bias that biases the damper arm 51 toward the shaft member 50. A spring (arm biasing means) 52 and a star wheel base 53 that supports the first star wheel 37 and the second star wheel 38 are provided.

  3 and 4 show the first star wheel 37, the second star wheel 38, and the support structure thereof from the sheet discharge tray 5 side. In FIG. 3, the first star wheel 37 and the second star wheel 38 have a configuration that is substantially symmetrical with respect to the central portion of the star wheel base 53. Only one half of 53 is shown. The first star wheel 37 is rotatably stretched by a first coil spring shaft 57 at a position facing the first paper discharge roller 35. On the other hand, the second star wheel 38 is rotatably stretched by the second coil spring shaft 58 at a position facing the second paper discharge roller 36. The star wheel base 53 is formed with first spring engaging portions 59 at positions corresponding to both ends of the first coil spring shaft 57. The first spring engaging portion 59 is formed in a key shape so that the end of the first coil spring shaft 57 can be engaged on the side opposite to the recording paper conveyance path (the back side in FIGS. 3 and 4). ing. A key-like second spring engaging portion 60 is formed at positions corresponding to both ends of the second coil spring shaft 58 so that the end of the second coil spring shaft 58 can be engaged.

  Both ends of the first coil spring shaft 57 are directly engaged with the first spring engaging portion 59 of the star wheel base 53, and the first star wheel 37 is moved to the first discharge roller 35 side by the first coil spring shaft 57. It is stretched around in a biased state. Similarly, both ends of the second coil spring shaft 58 are directly engaged with the second spring engaging portion 60 of the star wheel base 53, and the second star wheel 38 is connected to the second discharge roller by the second coil spring shaft 58. 36 is rotatably stretched in an urging state.

  The first paper discharge roller 35 is press-fitted into the shaft member 50 and is rotated integrally with the shaft member 50. In the vicinity of the end portion of the shaft member 50, a damper arm 51 that contacts the side surface of the shaft member 50 and applies a load to the rotation of the shaft member 50 is disposed. The damper arm 51 is provided in order to suppress fluctuations in the conveyance speed of the recording paper P when the trailing edge of the recording paper P is separated from the paper feed roller 32 and to improve the quality of borderless printing. One end portion of the damper arm 51 is rotatably held by an arm holding portion 61 formed integrally with the star wheel base 53. An arm biasing spring for biasing the central portion of the damper arm 51 in the direction of the side surface of the shaft member 50 is engaged with the other end portion of the damper arm 51.

  According to the inkjet printer 1 of the present embodiment having the above-described configuration, the star wheel base 53 that supports the first coil spring shaft 57 and the second coil spring shaft 58 is integrally formed of synthetic resin. The number of parts constituting the ink jet printer can be reduced. That is, both ends of the first coil spring shaft 57 are directly engaged with the star wheel base 53 at the first spring engaging portion 59, and both ends of the second coil spring shaft 58 are directly engaged with the star wheel base 53 at the second spring engaging portion 60. Therefore, the six first wheel holders 171 and the four second wheel holders 172 as shown in FIG. 5 are not necessary, and the process of incorporating them into the base plate 153 can be omitted, thereby reducing the manufacturing cost. Can do. Further, since the first star wheel 37 and the second star wheel 38 are supported by the star wheel base 53 made of inexpensive resin molding instead of the base plate 153 made of an expensive metal plate, the manufacturing cost of the ink jet printer is reduced. be able to. Further, since the arm holding portion 61 of the star wheel base 53 directly holds the damper arm 51, the arm holding base 181 as shown in FIG. 5 is not necessary, and the manufacturing cost can be further reduced. Become.

  The present invention is not limited to the configuration of the above-described embodiment, and at least the ends of the plurality of elastic shafts for supporting the plurality of star wheels in a stretched manner are formed by a star wheel base integrally formed of synthetic resin. What is necessary is just to be comprised so that it may support directly.

1 is a diagram illustrating a configuration of an ink jet printer that is an example of an image forming apparatus according to an embodiment of the present invention. FIG. FIG. 2 is a perspective view illustrating main components of a transport mechanism and an image forming unit in the printer. FIG. 3 is a perspective view showing a first star wheel, a second star wheel, and a support structure thereof from the downstream side of the recording paper conveyance path in the printer. The perspective view which expands and shows the principal part of FIG. The perspective view which shows the 1st star wheel in a conventional inkjet printer, the 2nd star wheel, and its support structure from the downstream of a recording paper conveyance path. The perspective view which expands and shows the principal part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Paper feed tray 3 Conveyance mechanism 3a First conveyance mechanism (first conveyance means)
3b Second transport mechanism (second transport means)
4 Image forming unit (image forming means)
5 Paper discharge tray 31 Pick roller 32 Paper feed roller 33 Press roller 35 First paper discharge roller 36 Second paper discharge roller 37 First star wheel 38 Second star wheel 40 Ink cartridge 41 Carrier 43 Print head 50 Shaft member 51 Damper arm 52 Arm biasing spring (arm biasing means)
53 Star wheel base 57 First coil spring shaft (elastic shaft)
58 Second coil spring shaft (elastic shaft)
59 First spring engaging portion 60 Second spring engaging portion 61 Arm holding portion

Claims (3)

A paper feed tray for holding the loaded recording paper, a first transport means for transporting the recording paper held in the paper feed tray into the apparatus, and forming an image on the recording paper transported by the first transport means Image forming means, a second transport means for transporting the recording paper on which an image is formed by the image forming means, and a paper discharge tray on which the recording paper transported by the second transport means is deposited. Prepared,
The first conveying means feeds the recording paper held in the paper feed tray to the inside of the apparatus, and the paper feeding conveys the recording paper sent by the pick roller to an image forming position by the image forming means. A roller and a pressing roller that presses the recording paper against the paper feeding roller,
The image forming unit includes: an ink cartridge filled with ink; a carrier in which the ink cartridge is mounted and reciprocating in a direction orthogonal to the conveyance direction of the recording paper; and a carrier driving unit that drives the carrier. Have
The second transport means is configured to press the first paper discharge roller for transporting the recording paper on which the image is formed downstream and the first paper discharge roller and rotate integrally with the first paper discharge roller. A shaft member;
A damper arm that contacts the side surface of the shaft member and applies a load to the rotation of the shaft member, an arm urging means that urges the damper arm toward the shaft member, and presses the recording paper against the first paper discharge roller A plurality of first star wheels, a plurality of first coil spring shafts that rotatably support the first star wheels in a biased state toward the first paper discharge rollers, and the first paper discharge rollers A second discharge roller for discharging the recording paper conveyed by the printer to the outside of the housing of the printer, a plurality of second star wheels for pressing the recording paper against the second discharge roller, and the second star wheel. An image forming apparatus having a plurality of second coil spring shafts rotatably supported in a biased state on the second paper discharge roller side;
A star wheel base that is integrally formed of synthetic resin and supports the damper arm, the first coil spring shaft, and the second coil spring shaft;
The star wheel base includes an arm holding portion that rotatably holds the damper arm, a first spring engaging portion that engages both ends of the first coil spring shaft, and both ends of the second coil spring shaft. A second spring engaging portion to be engaged,
Both ends of the first coil spring shaft are directly engaged with the star wheel base at a first spring engaging portion, and both ends of the second coil spring shaft are directly connected to the star wheel base at a second spring engaging portion. An image forming apparatus that is engaged. An image forming unit that forms an image on the recording paper; and a second transport unit that transports the recording paper on which the image is formed by the image forming unit to the outside of the apparatus,
The second conveying means includes a paper discharge roller that conveys the recording paper on which an image is formed downstream, a plurality of star wheels that press the recording paper against the paper discharge roller, and each star wheel that is connected to the paper discharge roller. In an image forming apparatus having a plurality of elastic shafts that are rotatably supported in a biased state on the side,
A star wheel base that is integrally formed of a synthetic resin and supports the elastic shaft;
The image forming apparatus according to claim 1, wherein the star wheel base includes a shaft engaging portion to which both ends of the elastic shaft are engaged. The second conveying means includes a shaft member into which the paper discharge roller is press-fitted and rotated integrally with the paper discharge roller, and a damper arm that contacts a side surface of the shaft member and applies a load to the rotation of the shaft member. And an arm biasing means for biasing the damper arm toward the shaft member,
The image forming apparatus according to claim 2, wherein the star wheel base includes an arm holding unit that rotatably holds the damper arm.

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