JP2009040538A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of reliably inserting a paper feed cassette to the normal position and preventing damages of a gear or other components. <P>SOLUTION: The image forming device couples/uncouples the drive transmission to a paper sheet stacking plate by attaching/detaching a drive gear G6 of a paper feed cassette to/from a final gear G52 of a gear train of a drive unit 34 provided on an image forming device body side through the attachable/detachable operation of the paper feed cassette having the paper sheet stacking plate which is attachable/detachable to/from the image forming device body and rockable and the drive gear G6 for rocking the paper sheet stacking plate, and a ratchet mechanism 41 is provided on the gear train of the drive unit 34. The ratchet mechanism 41 is relatively rotated only when attaching the paper feed cassette to the image forming device body, and the drive gear G6 is reliably engaged with the final gear G52 of the drive unit 34. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, when the paper feed cassette is mounted on the image forming apparatus main body, the drive gear for swinging the paper stacking plate of the paper feed cassette meshes with the final gear of the drive unit on the image forming apparatus main body side to the paper stacking plate. The present invention relates to an image forming apparatus capable of transmitting the above-mentioned drive.

  An image forming apparatus such as a copying machine, a printer, or a facsimile that forms an image on paper by an electrophotographic method is detachably mounted with a paper cassette that contains paper. A movable paper loading plate is provided.

  By the way, the sheet stacking plate is lifted up as the sheet on the sheet stacking plate is consumed by the image forming operation. This lift-up is caused by the drive gear provided in the sheet feeding cassette being driven by the drive unit on the image forming apparatus main body side. This is done by swinging the paper stacking plate by receiving the drive transmission from the.

That is, when the paper feed cassette is mounted on the image forming apparatus main body, the drive gear for swinging the paper stacking plate of the paper feed cassette meshes with the final gear of the drive unit on the image forming apparatus main body side to drive the paper stacking plate. The transmission gear is configured so that when the paper feeding cassette is pulled out from the image forming apparatus main body, the driving gear on the paper feeding cassette side is disengaged from the final gear on the image forming apparatus main body side and the driving transmission to the paper stacking plate is cut off. Has been.
JP 2003-118850 A JP 2003-246468 A JP 2005-149579 A

  However, in the image forming apparatus adopting the above configuration, when the paper feed cassette is mounted on the image forming apparatus main body, the tooth surfaces of the drive gear on the paper feed cassette side and the final gear on the image forming apparatus main body side abut against each other. The two gears may not engage with each other reliably. In such a case, the paper feed cassette may not be inserted to the proper position of the image forming apparatus main body, or the gears and other parts may be damaged. was there.

  The present invention has been made in view of the above problems, and the object of the present invention is that the paper feed cassette can always be reliably inserted into a regular position, and damage to gears and other parts can be prevented. An object is to provide an image forming apparatus.

  In order to achieve the above object, the invention according to claim 1 is a paper feed cassette which is detachably attached to the image forming apparatus main body and includes a swingable paper stacking plate and a drive gear for swinging the paper stacking plate. Is attached to and detached from the image forming apparatus main body, and the drive gear of the paper feed cassette is attached to and detached from the final gear of the gear train of the drive unit provided on the image forming apparatus main body side to drive the paper stacking plate. In the image forming apparatus in which transmission is connected / disconnected, a ratchet mechanism is provided in the gear train of the drive unit.

  According to a second aspect of the present invention, in the first aspect of the invention, the ratchet mechanism rotates relatively only when the paper feed cassette is mounted on the image forming apparatus main body, and the drive gear becomes the final gear of the drive unit. It is characterized by positively engaging.

  According to the present invention, since the ratchet mechanism is provided in the gear train of the drive unit, when the paper feed cassette is inserted into the image forming apparatus main body, the teeth of the drive gear on the paper feed cassette side and the final gear on the image forming apparatus main body side. Even when the surfaces collide with each other, the ratchet mechanism rotates relative to each other so that the drive gear is securely meshed with the final gear of the drive unit, so that the paper feed cassette can always be securely inserted into the regular position. Can prevent damage to gears and other parts.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side sectional view of a laser beam printer as an embodiment of an image forming apparatus according to the present invention. The illustrated laser beam printer 1 includes a box-shaped apparatus main body 1a, and an upper surface of the apparatus main body 1a. An inclined concave discharge tray 32 is provided at the center of the sheet. Further, an openable and closable manual feed tray 8 is provided at the upper front of the apparatus main body 1a (the right side in FIG. 1 is the front), and a paper feed cassette 7 is provided at the lower part of the apparatus main body 1a. 7 can be pulled out to the near side.

  Thus, the laser beam printer 1 according to the present embodiment is based on image data transmitted from a terminal (not shown) while transporting the paper along the transport path L provided in the apparatus main body 1a. An image is formed on a sheet, and the conveyance path L includes a horizontal portion L1 extending substantially horizontally from the front to the rear (right to left in FIG. 1) in the apparatus main body 1a, and the horizontal portion L1. The vertical portion L2 that rises substantially vertically from the end portion is configured in a substantially L shape in side view.

  Further, the laser beam printer 1 includes a paper feeding unit 2 provided at a lower portion of the apparatus main body 1a, an image forming unit 3 provided at a substantially central portion in the apparatus main body 1a above the paper feeding unit 2, The fixing unit 4 disposed behind the image forming unit 3, the concave paper discharge unit 5 provided on the upper surface of the apparatus main body 1 a above the fixing unit 4, the horizontal unit L 1 of the conveyance path L, and the supply unit A refeed conveyance unit 6 provided between the paper cassette 7 is provided.

  The paper feed unit 2 stores paper and feeds the paper toward the image forming unit 3 and includes the paper feed cassette 7 and the manual feed tray 8. Here, the paper feed cassette 7 has a rectangular box shape with an open upper surface, and has a function of feeding sheets (not shown) stacked and accommodated therein one by one, as shown in the figure. In the state where it is mounted in the apparatus main body 1a, it is located below the horizontal portion L1 of the transport path L.

  The paper feed cassette 7 includes a lift plate 9 that contacts and separates from the inner bottom surface, a paper stacking plate 10 that moves up and down in conjunction with the contact and separation of the lift plate 9, and a front end (paper) of the lift plate 9. 1 is attached in the vicinity of the downstream end of the paper feed direction) and rotates around the lift drive shaft 11 that rotates the lift plate 9 in the direction of the arrow in FIG. 1 and the rear end of the paper stacking plate 10 (upstream end in the paper feed direction). A shaft 12 is provided which is pivotally supported.

  Further, the paper feeding unit 2 feeds the paper stacked on the paper stacking plate 10 in the paper feeding cassette 7 one by one, and picks up the picked up paper to the horizontal part L1 of the transport path L. In addition to the feed roller 14 and the retard roller 15, the plurality of paper feed rollers 16, 17, and 18, the pair of registration rollers 19 that temporarily feed the fed paper and then supply it to the image forming unit 3 at a predetermined timing, as well as the manual feed tray A pick-up roller 20 is provided to take out the paper placed on the paper 8.

  The image forming unit 3 forms an image on a sheet supplied from the sheet feeding unit 2, and is an image carrier that is rotatably disposed at a substantially central portion in the front-rear direction of the horizontal portion L 1 of the transport path L. A photosensitive drum 21, a charger 22 disposed around the photosensitive drum 21, a developing device 23, a transfer roller 24 and a cleaning device 25, a laser scanner unit (LSU) 26 disposed above them, a toner hopper 27, and the like. .

  The fixing unit 4 is for fixing the toner image transferred onto the paper in the image forming unit 3 to the paper, and includes a heating roller 28 and a pressure roller 29 that rotate while being pressed against each other. Yes.

  Further, the paper discharge unit 5 is for discharging the paper on which the toner image has been fixed in the fixing unit 4 to the outside of the apparatus main body 1a, and is provided in the middle of the vertical portion L2 of the transport path L. A pair of conveying rollers 30 and a pair of paper discharge rollers 31 provided at the end of the vertical portion L2 and the paper discharge tray 32 for stacking sheets discharged to the outside of the apparatus main body 1a.

  The re-feed conveyance unit 6 is used when images are formed on both sides of a sheet, and includes another conveyance path L ′ arranged below the horizontal portion L1 of the conveyance path L and its conveyance path L ′. A plurality of conveyance roller pairs 33 provided at appropriate positions are provided.

  Next, an image forming operation of the laser beam printer 1 having the above configuration will be described.

  For example, when a print start signal is transmitted to the laser beam printer 1 from a terminal such as a personal computer (personal computer), in the image forming unit 3, the photosensitive drum 21 is driven in the direction indicated by the arrow (clockwise) in FIG. ) And the surface thereof is uniformly charged to a predetermined potential by the charger 22. When a laser beam based on the image data transmitted from the terminal is output from the laser scanner unit 26 and irradiated onto the photosensitive drum 21, an electrostatic latent image is formed on the photosensitive drum 21. Then, the electrostatic latent image formed on the photosensitive drum 21 is developed by the developing device 23 using toner as a developer to be visualized as a toner image.

  At the same time, in the paper feed unit 2, for example, the sheets stored in the paper feed cassette 7 are picked up one by one from the uppermost one by the pickup roller 13, and the feed roller 14, the retard roller 15, and the paper feed rollers 16, 17. , 18 are sent to the horizontal portion L1 of the transport path L, and after being temporarily put into a standby state by the registration roller pair 19, are supplied to the image forming portion 3 at a predetermined timing synchronized with the toner image on the photosensitive drum 21. The When an image is formed on the paper stacked on the manual feed tray 8, the paper is taken out one by one by the pickup roller 20 and sent out to the horizontal portion L 1 of the transport path L by the paper feeding rollers 16 and 18. .

  In the image forming unit 3, the sheet supplied to the transfer nip between the photosensitive drum 21 and the transfer roller 24 is conveyed while being pressed against the photosensitive drum 21 by the transfer roller 24, thereby its surface (transfer surface). ), The toner image on the photosensitive drum 21 is transferred. The sheet on which the toner image has been transferred is conveyed to the fixing unit 4, and is heated and pressed in the process of being sandwiched and conveyed by the heating roller 28 and the pressure roller 29 in the fixing unit 4. Get fixed. Note that the toner remaining on the surface of the photosensitive drum 21 (transfer residual toner) after the transfer of the toner image onto the paper is removed by the cleaning device 25.

  Thus, the sheet on which the toner image is fixed on the surface by the fixing unit 4 is conveyed upward through the vertical portion L2 of the conveying path L by the conveying roller pair 30, and the upper portion of the apparatus main body 1a by the discharge roller pair 31. The paper is discharged and stacked on a paper discharge tray 32 provided in the front.

  The above is a series of operations when an image is formed on one side of a sheet. When an image is formed on both sides of a sheet, a sheet having a toner image fixed on one side by a fixing unit 4 is transported to a pair of conveying rollers 30. Then, the sheet is fed to the vertical portion L2 of the conveyance path L, and then the sheet is switched back by reversing the conveyance roller pair 30 and fed to another conveyance path L ′. Then, the paper is transported forward (to the right in FIG. 1) along the transport path L ′ by the plurality of transport roller pairs 33 provided in the transport path L ′, and the paper is fed to the paper feed rollers 16, 17, 18. If the sheet is fed again to the horizontal portion L1 of the transport path L, the front and back of the sheet are reversed, and thereafter, the toner image on the photosensitive drum 21 is transferred to the surface of the sheet (the other side on which no image is formed) by the same operation as described above. Image is formed on both surfaces of the paper. The paper on which images are formed on both sides in this way is transported upward along the vertical portion L2 of the transport path L by the transport roller pair 30 and is discharged to the paper discharge tray 32 by the paper discharge roller pair 31 as described above. The

  Next, the gist of the present invention will be described with reference to FIGS.

  2 is a perspective view of the drive unit with the cover removed, FIGS. 3 and 4 are cross-sectional views taken along line AA of FIG. 2, FIG. 5 is a perspective view of a gear train of the drive unit, and FIG. 7 is an exploded perspective view of the ratchet mechanism, FIG. 7 is a perspective view of the paper stacking plate and the drive unit showing the meshing of the gear when the paper feeding cassette is inserted, and FIG. 8 is a perspective view of the driving unit showing the meshing of the gear when the paper feeding cassette is inserted. 9 is a perspective view showing the rotation of the drive unit side gear when the paper cassette is inserted, FIG. 10 is a perspective view of the paper stacking plate and the drive unit showing the meshing of the gear when the paper stacking plate is raised, and FIG. It is a perspective view of a drive unit which shows meshing of a gear at the time of a loading board rise.

  A drive unit 34 shown in FIG. 2 is provided on the side portion of the image forming apparatus main body 1a where the paper feed cassette 7 is inserted. The paper feed unit 34 is a unit that transmits drive to the paper stacking plate 10 and swings it up and down around the shaft 12. The paper feed unit 34 includes a motor 35 as a drive source, and a motor 35. A gear train G for transmitting the rotation to the lift drive shaft 11 (FIGS. 1 and 7) is provided.

  As shown in FIG. 5, the gear train G includes a pinion gear G1 connected to an output shaft (motor shaft) 35a extending horizontally from the motor 35, and four stage gears G2 and G3 sequentially meshing with the pinion gear G1. , G4, G5. Here, the large diameter gear G21 of the step gear G2 is engaged with the pinion barrier G1, the small diameter gear G22 of the step gear G2 is engaged with the large diameter gear G31 of the step gear G3, and the small diameter gear G32 of the step gear G3 is the step gear. It meshes with G4 large diameter gear G41. The small-diameter gear G42 of the step gear G4 meshes with the large-diameter gear G51 of the step gear G5, and the small-diameter gear G52 of the step gear G5 that is the final gear is an inner surface of the drive unit 34 as shown in FIGS. A part is exposed from the notch portion of the cover 36 that protrudes from the surface (the surface facing the side surface of the paper feed cassette 7 that is mounted).

  Incidentally, as shown in FIG. 6, the large-diameter gear G41 and the small-diameter gear G42 of the step gear G4 are separable, and the shaft 37 of the small-diameter gear G42 has a boss 38 formed at the center of the large-diameter gear G41. The gears G41 and G42 are slidably fitted in the circular hole 38a, and are relatively movable in the axial direction. A ring-shaped ratchet claw 39a is formed on the small-diameter gear G42, and a ring-shaped ratchet claw 39b is also formed inside the large-diameter gear G41.

  Thus, as shown in FIG. 3, when the shaft 37 of the small-diameter gear G41 is fitted to the boss 38 of the large-diameter gear G41 and the two gears G41 and G42 are assembled, the large-diameter gear G41 is moved by the spring 40 to the small-diameter gear. It is biased to the G42 side (left side in FIG. 3), and the ratchet claws 39a and 39b are normally engaged with each other. Here, the ratchet pawls 39a and 39b and the spring 40 constitute a ratchet mechanism 41. Therefore, the ratchet mechanism 41 is incorporated in the step gear G4.

  On the other hand, as shown in FIG. 7, a sector gear G7 is coupled to the end of the lift drive shaft 11 of the paper feed cassette 7, and the drive gear G6 is engaged with the sector gear G7. A drive gear G6 is also provided on the paper feed cassette 7 side.

  In the above, when the paper feed cassette 7 is inserted into the image forming apparatus main body 1a in the direction of arrow a in FIGS. 7 and 8, the drive gear G6 on the paper feed cassette 7 side is the final gear on the drive unit 34 side. The rotation of the output shaft 35a of the motor 35 is meshed with the small-diameter gear G52 of the gear G5, is decelerated from the pinion G1 through the step gears G2 to G5, and is transmitted to the drive gear G6 and the sector gear G7 on the sheet feeding cassette 7 side. That is, as shown in FIGS. 9 to 11, when the small-diameter gear G52 of the step gear G5, which is the final gear on the drive unit 34 side, rotates in the direction of the arrow (clockwise), the drive on the side of the paper feed cassette 7 that meshes with it. The gear G6 rotates in the direction of the arrow (counterclockwise). Then, the sector gear G7 meshing with the drive gear G6 and the lift drive shaft 11 rotate in the direction of the arrow (clockwise), and the lift drive shaft 11 causes the lift plate 9 to be centered on the lift drive shaft 11 in the same direction (clockwise). In order to rotate, the lift plate 9 causes the paper stacking plate 10 to swing upward about a shaft 12 (see FIG. 1).

The positional relationship between the small-diameter gear G52 of the step gear G5, which is the final gear on the drive unit 34 side, and the drive gear G6 on the paper feed cassette 7 side is transmitted from the small-diameter gear G52 to the drive gear G6 as shown in FIG. Horizontal force F1 of the driving force F applied
(= Fsin α: α is a pressure angle) is set so as to face the insertion direction (arrow a direction) of the paper feed cassette 7, and in this way, the paper feed cassette 7 is pulled out during driving. There is no power.

  When the paper cassette 7 is inserted into the image forming apparatus main body 1a, the tooth surfaces of the driving gear G6 on the paper feeding cassette 7 side and the small-diameter gear G52 which is the final gear on the driving unit 34 face each other. The drive gear G6 tries to rotate the small-diameter gear G52 in the direction of the arrow (clockwise) in FIG. 8, and the driving force is transmitted to the small-diameter gear G42 of the step gear GG4 via the large-diameter gear G51 of the step gear G5. The small diameter gear G42 receives the driving force in the direction of the arrow in FIG.

  Here, since the ratchet pawls 39a and 39b have a shape in which drive transmission is not performed when the small-diameter gear G42 rotates in the direction of the arrow in FIG. 4, the small-diameter gear G42 has a driving force in the direction of the arrow in FIG. In response, the ratchet mechanism 41 operates to move one ratchet pawl 39b against the biasing force of the spring 40 in the axial direction (in the direction of the arrow in FIG. 4) and retract from the other ratchet pawl 39a. Therefore, the rotation of the small-diameter gear G42 of the step gear G4 is allowed and the rotation of the small-diameter gear G52 as the final gear is also allowed, so that the small-diameter gear G52 and the drive gear G6 on the sheet feeding cassette 7 side are reliably engaged. To do. As a result, the paper feed cassette 7 is always reliably inserted into the regular position of the image forming apparatus main body 1a, and damage to the small-diameter gear G52, the drive gear G6, and other components that are meshed with each other is prevented.

  Further, when the paper feeding cassette 7 is pulled out from the image forming apparatus main body 1a, the ratchet mechanism 41 does not operate because only the small-diameter gear G52 and the driving gear G6 that have been once engaged are disengaged. In other words, the ratchet mechanism 41 ensures that the ratchet pawls 39a and 39b rotate relative to each other only when the paper feed cassette 7 is mounted on the image forming apparatus main body 1a, so that the drive gear G6 is reliably transferred to the small-diameter gear G52 that is the final gear of the drive unit 34. It functions to mesh.

  Although the present invention has been described with respect to an embodiment in which the present invention is applied particularly to a laser beam printer, the present invention is not limited to a printer, but can be applied to any other image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine thereof. Of course, the above can also be applied.

1 is a side sectional view of an image forming apparatus (laser beam printer) according to the present invention. It is a perspective view in the state where the cover of the drive unit was removed. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 (when the ratchet mechanism is not operated). FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 (when the ratchet mechanism is activated). It is a perspective view of the gear train of a drive unit. It is a disassembled perspective view of the ratchet mechanism of a drive unit. FIG. 4 is a perspective view of a paper stacking plate and a drive unit showing meshing of gears when a paper feed cassette is inserted. It is a perspective view of a drive unit showing meshing of gears when a paper feed cassette is inserted. It is a perspective view showing rotation of a drive unit side gear at the time of paper feed cassette insertion. FIG. 6 is a perspective view of a paper stacking plate and a drive unit showing meshing of gears when the paper stacking plate is raised. FIG. 4 is a perspective view of a drive unit showing the meshing of gears when the paper stacking plate is raised.

Explanation of symbols

1 Laser beam printer (image forming device)
DESCRIPTION OF SYMBOLS 1a Image forming apparatus main body 2 Paper feed part 3 Image formation part 4 Fixing part 5 Paper discharge part 6 Refeed conveyance part 7 Paper feed cassette 8 Manual feed tray 9 Lift plate 10 Paper stacking plate 11 Lift drive shaft 12 Shaft 13 Pickup roller 14 Feed roller 15 Retard roller 16-18 Paper feed roller 19 Registration roller pair 20 Pickup roller 21 Photosensitive drum 22 Charger 23 Developing device 24 Transfer roller 25 Cleaning device 26 Laser scanner unit (LSU)
27 toner hopper 28 heating roller 29 pressure roller 30 transport roller pair 31 discharge roller pair 32 drive discharge tray 33 transport roller pair 34 drive unit 35 motor 35a motor output shaft (motor shaft)
36 Drive Unit Cover 37 Gear Shaft 38 Gear Boss 39a, 39b Ratchet Claw 40 Spring 41 Ratchet Mechanism G Gear Train G1 Pinion Gear G2-G5 Stage Gear G6 Drive Gear G7 Sector Gear L, L 'Transport Path L1 Horizontal Section of Transport Path L2 Vertical part of the transport path

Claims (2)

The paper feeding cassette can be attached to and detached from the image forming apparatus main body, and the paper feeding cassette having a swingable paper stacking plate and a driving gear for swinging the paper stacking plate is attached to and detached from the image forming apparatus main body. In the image forming apparatus in which the drive gear of the cassette is attached to and detached from the final gear of the gear train of the drive unit provided on the image forming apparatus main body side, and the drive transmission to the swing stacking plate is connected and disconnected.
An image forming apparatus comprising a ratchet mechanism in a gear train of the drive unit. The image forming apparatus according to claim 1, wherein the ratchet mechanism rotates relatively only when the sheet feeding cassette is mounted on the image forming apparatus main body, and reliably meshes the drive gear with the final gear of the drive unit. apparatus.

Images