JP2006182538A - Paper carrying mechanism for image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow easy removal of paper jammed during carriage and improve the positioning accuracy of a register roller in the state that a belt is tensed. <P>SOLUTION: The register roller 14 and a register front roller 40 are connected to each other to be driven via the belt 48. When the register roller 14 is lifted up, a tension roller 50 is also lifted up to weaken the tension of the belt 48, thus allowing easy removal of the paper and improving the positioning accuracy of the register roller 14 in the state that the belt is tensed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a paper transport mechanism in an image forming apparatus such as a copying machine, a printer, or a fax machine.

  A conventional image forming apparatus includes a registration roller that adjusts paper feeding timing on a conveyance path through which a sheet stored in a sheet storage unit is conveyed to a print processing unit, and a conveyance roller that is disposed upstream of the registration roller. A pre-registration roller is provided, and the registration roller and the pre-registration roller are configured to rotate in conjunction with each other (see, for example, Patent Document 1). The registration roller includes a driving roller and a driven roller to which a driving force of a driving source is transmitted, and the driving roller and the pre-registration roller are generally driven and transmitted by meshing a plurality of gears. Is.

  The paper stored in the paper storage unit contributes to printing by transporting the paper of the size requested by the print request from the storage unit to the printing process. The paper transported from the storage unit includes a plurality of transport rollers, It reaches the printing section through the paper guide. In this transport path, the paper may be transported in a slightly oblique direction with respect to the transport direction and jammed. When the conveyed paper is jammed in the conveyance path, a plurality of sheets stay in the conveyance path in addition to the jammed paper, particularly in a high-speed printing apparatus.

It is necessary to reliably remove the staying paper and to remove each member disposed in the transport path without any harmful effects. Therefore, a method is used in which the registration roller driving roller is lifted in a direction (upward) perpendicular to the sheet conveyance direction with respect to the driven roller to remove the sheet.
JP 2001-316017 A

  However, in the conventional method, when the driving roller of the registration roller is lifted, a load is applied to the roller driving gear, and the registration roller and the pre-registration roller are interlocked and connected by a plurality of gears. There is no guarantee that the drive roller will return to the normal position after being released and lifted, and if the drive roller is misaligned in the hand direction with respect to the driven roller, the original function of the registration roller cannot be achieved and the print quality will be reduced. And the occurrence of a jam in the sheet conveyance after the registration roller.

  In the present invention, the driving connection of the front roller (front idle roller) to the registration roller and the register is belt-driven, so that the sheet can be easily taken out, and the positional accuracy of the registration roller is improved when the belt is tensioned. Propose mechanism.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention includes a registration roller and a pre-registration roller disposed at an upstream position of the registration roller in a paper conveyance path through which the paper stored in the paper storage unit is conveyed to the print processing unit. The roller and the pre-registration roller are configured to rotate in conjunction with each other, and the registration roller includes a driving roller and a driven roller to which a driving force of a driving source is transmitted, and the driving roller and the pre-registration roller Means that the belt tension is weakened so that when the drive roller of the registration roller is moved away from the driven roller, the connection between the registration roller and the pre-registration roller is released. is there.

  In the present invention having such a configuration, when the paper is jammed in the paper conveyance path before being conveyed to the print processing unit, if the driving roller is separated from the driven roller, the tension of the belt is reduced, and the registration roller And the pre-registration roller are disconnected. As a result, the rotation of the pre-registration roller becomes free regardless of the registration roller due to the slackness of the belt, and the driving roller of the registration roller can be slightly separated from the driven roller and stays due to a jam. The paper P can be taken out easily and smoothly.

  According to the present invention, a tension roller that applies tension to the belt is provided, and when the driving roller is separated from the driven roller, the driving source and the tension roller are weak in belt tension around a rotation fulcrum. It is to be rotated in the direction.

  Then, by returning the tension roller to its original position, tension is again applied to the belt by the tension roller, so that the drive roller side is returned to the normal position as compared with the case where a plurality of gears are engaged as in the prior art. The position accuracy of the registration roller is improved when the belt is tensioned.

  According to the present invention, it is easy to take out the jammed paper in the middle of conveyance, and the positional accuracy of the registration roller can be improved in a state where the belt tension is increased.

  Hereinafter, an image forming apparatus including a transfer device according to the best embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of the configuration of an image forming apparatus provided with the transfer device of the present invention. As shown in the figure, in the image forming apparatus 100, a supply tray 10 serving as a paper storage unit for storing paper on which an image is formed is disposed in a lower portion of the housing 100a. On the other hand, a stacking tray 15 that accommodates sheets of paper on which images have been formed and discharged to the outside of the apparatus is disposed on the top of the casing 100a.

  A sheet conveyance path R is formed between the supply tray 10 and the stacking tray 15 in the vertical direction. The supply tray 10 includes a pickup roller 16 for sending out the stored sheets one by one to the sheet conveyance path R.

  A photosensitive drum 3 is disposed in the print processing section in the middle of the paper transport path R. The photosensitive drum 3 is an image carrier for carrying an image to be transferred onto a sheet conveyed through the sheet conveyance path R. Around the photosensitive drum 3, a charging device 5, an optical scanning unit 11, a developing unit 2, a transfer device 6, a cleaning unit 4, and a static elimination lamp 12 are disposed.

  The charging device 5 uniformly charges the surface of the photosensitive drum 3. The optical scanning unit 11 scans the optical image on the uniformly charged photosensitive drum 3 and writes an electrostatic latent image. The developing unit 2 supplies a developer in the developer supply container 7 to the electrostatic latent image formed on the surface of the photosensitive drum 3 to form a developer image.

  The transfer device 6 transfers the developer image formed on the surface of the photosensitive drum 3 onto the paper that has been transported through the paper transport path R. The transfer device 6 includes a driven transfer roller 6A, a driving roller 6B, a tension roller 6C, a transfer belt 6D stretched around these rollers 6A to 6C, and the like. The outer peripheral surface of the transfer belt 6D from the driven roller 6A side to the driving roller 6B side constitutes a part of the sheet transport path R.

  The cleaning unit 4 removes the developer remaining on the surface of the photosensitive drum 3 in order to form a new image on the photosensitive drum 3. The static elimination lamp 12 removes electric charges on the surface of the photosensitive drum 3.

  A registration roller 14 is disposed on the upstream side of the photosensitive drum 3 in the paper conveyance path R. The registration roller 14 controls the timing for guiding the sheet between the photosensitive drum 3 and the transfer belt 6D.

  Further, below the image forming apparatus 100, a paper supply device (not shown) including a multi-stage paper tray prepared as a peripheral device and a large capacity paper supply device (not shown) capable of storing a large amount of paper are arranged. In the vicinity of the supply tray 10 in the image forming apparatus 100, there are a sheet receiving unit 101 that receives a sheet guided from the sheet supplying apparatus to the image forming position, and an extended sheet receiving unit that receives a sheet guided from the large capacity sheet supplying apparatus to the image forming position. 102 is formed.

  A fixing device 8 is disposed on the downstream side of the photosensitive drum 3 in the paper conveyance path R. The fixing device 8 includes a fixing roller 81 and a pressure roller 82 that are disposed on both sides of the sheet conveyance path R. The fixing device 8 fixes the unfixed developer transferred onto the image forming surface of the sheet conveyed through the sheet conveyance path R by heat and pressure from the fixing roller 81 and the pressure roller 82 on the sheet.

  A conveyance roller 25 and a switching gate 9 are disposed on the downstream side of the fixing roller 81 in the sheet conveyance direction. The conveyance roller 25 further conveys the sheet that has passed through the fixing device 8 to the downstream side of the sheet conveyance path R. The switching gate 9 selectively opens a conveyance path on which a sheet conveyed by the conveyance roller 25 should be conveyed.

  Above the optical scanning unit 11, a control unit 110 including a circuit board that controls image forming processing and an interface board that receives image data from an external device is arranged. On the other hand, below the optical scanning unit 11, a power supply device 111 that supplies electric power to the above-described units of the image forming apparatus 100 is disposed. Reference numeral 38 denotes a paper guide disposed along the paper transport path R.

  Next, the details of the conveyance portion 30 immediately before the nip area between the transfer device 6 and the photosensitive drum 3 will be described with reference to FIGS.

  A pair of left and right frames 18 and 19 are arranged on the housing 100a of the image forming apparatus 100 with a predetermined interval. One frame 18 is provided with a rotation plate 20 that is rotatable about a support shaft 25. Between the frames 18 and 19, the registration roller 14 and a pre-registration roller 40 as a conveying roller are rotatably mounted.

  Specifically, the registration roller 14 includes a driving roller 14A and a driven roller 14B. The driving roller 14 </ b> A and the driven roller 14 </ b> B include feeding parts 21 and 22 and roller shafts 23 and 24 inserted through the feeding parts 21 and 22. Both sides of the roller shaft 24 of the driven roller 14B are rotatably supported by the frames 18 and 19.

  One end of the roller shaft 23 of the drive roller 14 </ b> A is supported by the rotating plate 20, and the other end is supported by the other frame 19. By rotating the rotating plate 20 around the support shaft 25 in the direction of the arrow, the driving roller 14A can be tilted so that one end side of the feeding portion 21 is separated from the feeding portion 22 of the driven roller 14B. (See FIGS. 3 and 7). One frame 18 has a relief opening 18a that allows the drive roller 14A to be inclined.

  The pre-registration roller 40 includes a driving roller 40A and a driven roller 40B. The driving roller 40A and the driven roller 40B are composed of feed portions 41 and 42 and roller shafts 43 and 44 inserted through the feed portions 41 and 42. The roller shafts 43 and 44 rotate between the frames 18 and 19, respectively. It is supported freely.

  Pulleys 45 and 46 are respectively provided on the roller shafts 23 and 43 of the driving rollers 14A and 40A of the registration roller 14 and the pre-registration roller 40, and a belt 48 is wound between the pulleys 45 and 46. . The roller shaft 23 of the driving roller 14 </ b> A of the registration roller 14 is provided with a gear 51, which meshes with a gear 53 of a motor 52 as a driving source attached to the rotating plate 20.

  The rotation plate 20 is provided with a tension roller 50 that applies tension to the belt 48. Therefore, the registration roller 14 and the pre-registration roller 40 are rotationally driven in conjunction with each other. The tension roller 50 can adjust the tension of the belt 48. The support shaft 25 is located on the upper side opposite to the tension roller 50 with respect to the registration roller 14.

  The rotation plate 20 can maintain the paper feed position where the tension roller 50 applies tension to the belt 48 in a releasable manner. Specifically, the pressing portion 100 c provided on the opening / closing cover 100 b that constitutes a part of the housing 100 a presses the rotating plate 20. Further, the rotating plate 20 is locked and fixed at the supply position to a stopper portion 18b formed by bending a part of one of the frames 18 to be bent. The opening / closing cover 100b may be rotatable about the support shaft 28 as shown in FIG.

  In the image forming apparatus 100 having the above-described configuration, the sheet P is usually along a conveyance path of the supply tray 10 → the registration roller 14 → the nip area between the transfer device 6 and the photosensitive drum 3 → the fixing device 8 → the stacking tray 15. Be transported. When the paper is transported, the rotation plate 20 is at the paper feed position, and the belt 48 is in tension, so that the driving force of the motor 52 is transmitted to the registration roller 14 and the pre-registration roller via the belt 48. 40 is also transmitted.

  Next, a case where a jam such as paper jam occurs will be described. First, the opening / closing cover 100b is opened. By opening the opening / closing cover 100b, the pressing portion 100c of the opening / closing cover 100b is separated from the rotation plate 20, so that the position restriction of the rotation plate 20 is released. At this time, the rotating plate 20 can freely rotate, and the pressing of the tension roller 50 to the belt 48 is released (see FIG. 5). As a result, the rotation of the pre-registration roller 40 becomes a free state unrelated to the registration roller 14, and the driving roller 14A of the registration roller 14 can be slightly separated from the driven roller 14B due to the slack of the belt 48. The jammed paper P can be taken out easily and smoothly (see FIG. 6).

  After the jammed paper P is taken out, the rotation plate 20 can be set again at the paper feeding position by closing the opening / closing cover 100b. At this time, the tension roller 50 presses the belt 48, and the registration roller 14 and the pre-registration roller 40 are interlocked.

  The present invention is not limited to the embodiment described above. The support shaft 25 that supports the rotating plate 20 can also be provided at a position indicated by an imaginary line in FIG. 3 (between the registration roller 14 and the tension roller 50).

  In addition, as shown in FIG. 8, the belt 48 and the pulleys 45 and 46 can be provided on the side opposite to the motor 52 (on the other frame 19 side). In such a case, the tension roller 50 is extended through the stay 55.

  In addition, the rotation plate 20 can be provided with a fixing means so that the position (discharge position) rotated upward at which the tension of the belt 48 is weakened can be maintained releasably. Further, the driving roller 14A of the registration roller 14 may be configured to be separated in parallel to the driven roller 14B over the entire length. In addition, the present invention can be variously modified. For example, the present invention can be applied not only to a printer but also to a copying machine, a facsimile machine, and the like.

1 is a cross-sectional side view showing an embodiment of an image forming apparatus to which the present invention is applied. It is a cross-sectional rear view showing the paper transport mechanism of the present invention. It is a side view including a partial cross section showing a paper transport mechanism of the present invention. FIG. 6 is a side view of conveying a sheet by a registration roller and a tension roller. It is a side view of the state which canceled the tension of the belt. FIG. 4 is a side view of a state where a sheet is removed from a registration roller and a tension roller. It is a front view of the state which made the drive roller of a registration roller space apart from the driven roller. It is a cross-sectional rear view showing another paper transport mechanism of the present invention.

Explanation of symbols

10 Paper cassette (paper storage unit)
14 registration roller 14A driving roller 14B driven roller 25 support shaft (rotation fulcrum)
40 Roller before registration 48 Belt 50 Tension roller

Claims (2)

A registration roller and a pre-registration roller disposed at an upstream position of the registration roller are provided on a paper conveyance path through which the paper stored in the paper storage unit is conveyed to the print processing unit, and the registration roller and the pre-registration roller Is a paper transport mechanism in an image forming apparatus configured to rotate in conjunction with each other,
The registration roller includes a driving roller and a driven roller to which a driving force of a driving source is transmitted. The driving roller and the pre-registration roller are driven and transmitted by a belt, and the driving roller of the registration roller is transmitted from the driven roller. A sheet conveying mechanism in an image forming apparatus, wherein the belt tension is weakened so that the connection between the registration roller and the pre-registration roller is released when separating.   When a tension roller for applying tension to the belt is provided and the driving roller is separated from the driven roller, the driving source and the tension roller are rotated in a direction in which the belt tension is weakened around the rotation fulcrum. The paper transport mechanism in the image forming apparatus according to claim 1.

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