JPH05165301A - Switching mechanism for developing device - Google Patents

Abstract

PURPOSE:To provide the switching mechanism which is simplified in structure reduced in size, and precisely sets the developing device at a developing position. CONSTITUTION:The switching mechanism which switches developing devices 1 and 2 respectively and guides the developing device to the developing position where developing is possible from a position separated from a photosensitive body 32 is provided with a driving means consisting of a driving shaft 4, a driving motor which drives and rotates the driving shaft 4, etc., a guide part consisting of cams 4 and 5 fixed successively to the driving shaft 4 while having, for example, a 180 deg. specific phase difference, guide holes 74 and 84 which are provided corresponding to the cams 5 and 6 and supported slidably from the separate positions of the development positions 1 and 2 to the development position, etc., and driven members 7 and 8 consisting of levers 71 and 72, and 81 and 82 which are interposed between the peripheral surfaces of the corresponding cams 5 and 6 and development devices 1 and 2 and move the development positions 1 and 2 to the development position through the rotation of the cams 5 and 6 and pressing surfaces 73 and 83 which abut on the development devices 1 and 2 and press the development devices 1 and 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device switching mechanism in which a plurality of developing devices provided for image formation are individually switched so as to approach a photoconductor.

[0002]

2. Description of the Related Art Conventionally, a plurality of developing devices respectively accommodating developers of different colors are provided, and each developing device is independently driven by a driving means such as a driving motor, so that the developing device is transferred to a photosensitive member. There is known an image forming apparatus in which a developing device other than the developing device is guided to a separating position while being brought close to the developing position.

By the way, in this image forming apparatus, since the driving means is provided for each developing device and the structure is complicated, as shown in FIG. 5, the drive shaft 50 is rotationally driven by a drive motor (not shown) or the like. Then, one of the developing devices 1 and 2 is guided to the developing position to develop the electrostatic latent image on the photosensitive drum 32 by the developing sleeves 1a and 2a, and the other developing device is guided to the separated position. A developing device having a switching mechanism is adopted.

That is, the developing devices 1 and 2 are always biased in the right direction in the drawing by a biasing means (not shown).
In the case of developing with the cam 5, the drive shaft 50 is rotationally driven in a clockwise direction, for example, by a drive motor or the like (not shown),
By rotating 1, the developing device 1 is pushed toward the photoconductor drum 32 side against the biasing means. Therefore, as indicated by the solid line in FIG. 5, the developing device 1 approaches the photosensitive drum 32 and is moved to the developing position. On the other hand, the developing device 2 is moved to a separated position apart from the photosensitive drum 32 by the urging means.

On the other hand, when developing with the developing device 2, the drive shaft 50 is rotationally driven to rotate the cam 51 by 180 °, so that the cam 51 pushes the upper part of the lever 52 to center the lever 52 on the shaft 53. Rotate clockwise.
Therefore, the lower part of the lever 52 pushes the developing device 2 toward the photoconductor drum 32 side, and the developing device 2 approaches the photoconductor drum 32 and moves to the developing position as shown by the chain double-dashed line in FIG. The developing device 1 is returned to the separated position separated from the photosensitive drum 32 by the urging means.

[0006]

However, in the above switching mechanism, since the drive shaft 50 and the shaft 53 have a two-axis structure, it is difficult to reduce the size, and the shafts 50 and 53 are also difficult to downsize.
Since both ends of the shaft are supported by both side plates of the housing (not shown), these shafts 50, 5 are not required for maintenance.
It was necessary to remove and attach 3 respectively, which reduced workability.

Further, since the developing device 1, 2 is pushed while the cam 51 and the lever 52 rotate, a vertical force may be applied to the developing device 1, 2 to cause the developing device 1, 2 to tilt. .. As a result, the developing devices 1 and 2 may not be set at the proper developing position with respect to the photosensitive drum 32, and proper development cannot be performed.

The present invention solves the above problems, and an object thereof is to provide a developing device switching mechanism capable of simplifying the structure and downsizing and accurately setting the developing device at the developing position. To do.

[0009]

In order to achieve the above object, the present invention is directed to a switching of a developing device for switching a first developing device and a second developing device to guide a developing position from a distance from a photosensitive member to a developing position where development is possible. In the mechanism, a drive shaft, a drive means for rotationally driving the drive shaft, first and second cams having a predetermined phase difference and arranged in parallel and fixed to the drive shaft, and the first and second cams.
A guide portion that is provided corresponding to the second cam and is slidably supported from the separated position to the developing position of the developing device, and is interposed between the peripheral surface of the corresponding cam and the developing device, and by the rotation of the cam. The first and second driven members are composed of a lever for moving the developing device to the developing position and a pushing surface for abutting the developing device to push the developing device.

[0010]

According to the switching mechanism of the developing device having the above structure, the drive shaft is rotationally driven, and the first and second cams are respectively rotated. Then, when the lever of the corresponding first driven member moves due to the rotation of the first cam, the first developing device is pushed from the separated position to the developing position by the pushing surface. on the other hand,
When the lever of the corresponding second driven member moves due to the rotation of the second cam, the pressing surface pushes the second developing device from the separated position to the developing position.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 is a schematic structural view showing an example of an image forming apparatus such as a copying machine having a developing device switching mechanism according to the present invention. The copying machine is provided with a contact glass 21 and a document retainer 22 on its upper part, and an optical system L and an image forming means P inside. The original document retainer 22 retains the original document placed on the contact glass 21.

The optical system L includes a first moving frame 26 having a document irradiation lamp 23 such as a halogen lamp, a reflecting plate 24 and a mirror 25, a second moving frame 29 having mirrors 27 and 28, and a lens 30. And a mirror 31. When the copying operation is started, the first moving frame body 26 and the second moving frame body 29 start moving, and the original irradiation lamp 23 emits light to cause the contact glass 2 to move.
The upper one of the originals is illuminated. Then, the reflected light from the document is passed through the mirror 25 and the mirrors 27 and 28 to the lens 3
After being guided to 0, it passes through the mirror 31 and the following photosensitive drum 3
2 is exposed.

The image forming means P includes a photosensitive drum 32,
It comprises a charging device 33, a blank lamp 34, a plurality of developing devices 1 and 2, a transfer device 35, a separating device 36, a cleaning device 37 and the like. The surface of the photosensitive drum 32 is uniformly charged by the charging device 33,
After the charges in unnecessary areas are removed by the blank lamp 34, the blanks 34 are exposed by the reflected light from the original, thereby forming an electrostatic latent image. This electrostatic latent image is developed by the developing device 1.
Alternatively, the toner image is developed by the developing device 2, the toner image is transferred to the transfer paper by the transfer device 35, and then separated from the photosensitive drum 32 by the separating device 36. On the other hand, the toner remaining on the photosensitive drum 32 is cleaned by the cleaning device 3
Removed by 7.

In addition, from the upstream side of the transfer paper feeding direction,
Paper feed cassettes 38 and 39, paper feed rollers 40 and 41, conveyance roller pairs 42 and 43, and registration roller pair 44 are arranged. Then, the transfer paper in the paper feed cassettes 38, 39 is taken out by the paper feed rollers 40, 41, conveyed to the registration roller pair 44 by the conveyance roller pairs 42, 43, and then, the optical system L of the optical system L is conveyed by the registration roller 44 pair. The image is fed to the photosensitive drum 31 in synchronization with the scanning.

A conveyor belt 45, a fixing device 46, a discharge roller pair 47, etc. are arranged downstream of the transfer sheet after the transfer. Then, the transfer paper after the transfer is the conveyor belt 4
5 is conveyed to the fixing device 46 and is fixed by the fixing device 46.
Is discharged to.

Next, an example of the configuration of the switching mechanism of the developing devices 1 and 2 will be described with reference to FIGS. The switching mechanism 3 is arranged on the opposite side of the photoconductor drum 32 across the developing devices 1 and 2, and includes a drive shaft 4, cams 5 and 6, driven members 7 and 8, a drive motor 9, a worm 10, and a worm 10. Gear 1
1a, 11b, etc. In addition, the drive shaft 4 and the pin 121
~ 124, drive motor 9, worm 10 and gear 11
The frames a and 11b are supported by the frame 12. Drive shaft 4
Is the drive motor 9, worm 10 and gear 1 shown in FIG.
It is rotatably driven by a driving means including 1a and 12b. The cams 5 and 6 are arranged and fixed side by side in the axial direction of the drive shaft 4, and are located on the respective vertices 5a and 6a of the cams 5 and 6, that is, on the circumferential surfaces of the cams 5 and 6 and located closest to the axis of the drive shaft 4. The distant points are set to have a phase difference of 180 °, for example.

The driven member 7 is made of an elastic material such as resin and has levers 71, 72, a pushing surface 73 and a guide hole 74. The levers 71 and 72 are vertically installed so as to be parallel to each other with the cam 5 interposed therebetween.
By rotating while contacting each side wall of the
The rotational force of is converted into a reciprocating motion in the horizontal direction in the figure.

The pushing surface 73 contacts the rear end of the developing device 1 when the driven member 7 moves leftward and pushes the developing device 1 toward the photosensitive drum 32 side (leftward in the drawing). is there.
The guide hole 74 is formed in the left-right direction of the driven member 7, and the pins 121 and 122 fixed to the frame 12 are slidably fitted to guide the driven member 7 in the left-right direction. ..

The driven member 8 is made of an elastic material such as resin and has levers 81, 82, a pushing surface 83 and a guide hole 84. The levers 81 and 82 are erected so as to be parallel to each other with the cam 6 interposed therebetween.
By rotating while contacting each side wall of the cam 6
The rotational force of is converted into a reciprocating motion in the horizontal direction in the figure.

When the driven member 8 moves leftward, the pushing surface 83 comes into contact with the rear end of the developing device 2 and pushes the developing device 2 toward the photosensitive drum 32 side (leftward in the drawing). is there.
The guide hole 84 is formed in the left-right direction of the driven member 8, and the pins 123 and 124 fixed to the frame 12 are slidably fitted to guide the driven member 8 in the left-right direction. The developing devices 1 and 2 are supported by a main body chassis (not shown) so as to be slidable in the left-right direction in the figure, and are biased toward the separated position by a biasing means (not shown) in consideration of fail-safe. There is.

The receiving portions 1b and 2b are detachably loaded with a toner hopper (not shown).

Next, the operation of the switching mechanism 3 will be described with reference to FIG.
2 and FIG. 2. When the electrostatic latent image on the photosensitive drum 32 is developed by the developing device 1, the drive shaft 4 is rotationally driven by the drive motor 9 or the like to rotate the cam 5. With the rotation of the cam 5, the driven member 7 moves leftward in FIG. 1 to come into contact with the rear end of the developing device 1, and pushes the developing device 1 leftward as it is. As a result, the developing device 1 moves to the photosensitive drum 32 side. And the apex 5a of the cam 5
Thus, the rotation of the drive shaft 4 is stopped when the lever 71 of the driven member 7 is most moved leftward (state of FIG. 1). At this time, the developing device 1 is at the developing position, whereby the electrostatic latent image on the photosensitive drum 32 can be developed by the developing sleeve 1a of the developing device 1. On the other hand, the rotation of the cam 6 accompanying the rotation of the drive shaft 4 pushes the lever 82 of the driven member 8 to the right, and the driven member 8 moves to the right. As a result, the developing device 2 is returned to the separated position away from the photosensitive drum 32.

On the other hand, the photoconductor drum 32 by the developing device 2
When developing the above electrostatic latent image, the drive shaft 4 is rotationally driven by the drive motor 9 or the like as described above. This drive shaft 4
Along with the rotation, the lever 72 of the driven member 7 is pushed rightward by the cam 5, and the driven member 7 moves rightward. The apex 5 a of the cam 5 causes the lever 71 of the driven member 7 to move.
When the rotation of the drive shaft 4 is stopped in the state where the drive shaft 4 is most moved to the right (the state shown in FIG. 2), the developing device 1 moves to the photoconductor drum 3
The position is separated from 2. On the other hand, the rotation of the cam 6 accompanying the rotation of the drive shaft 4 pushes the lever 81 of the driven member 8 to the left, and the driven member 8 moves to the left to come into contact with the rear end of the developing device 2. Press 2 to the left. Therefore, the developing device 2 moves to the photosensitive drum 32 side.
Then, when the rotation of the drive shaft 4 is stopped, the apex 6a of the cam 6 brings the lever 81 of the driven member 8 to the leftmost position (the state of FIG. 2). At this time, the developing device 2 is at the developing position, whereby the electrostatic latent image on the photosensitive drum 32 can be developed by the developing sleeve 2a of the developing device 2.

In this way, since the switching mechanism 3 has the one-shaft structure of the drive shaft 4, the space can be saved. In addition, the rotational force of the cams 5 and 6 is temporarily changed by the driven members 7 and 8.
Since the developing devices 1 and 2 are converted into reciprocating motion and pushed, the developing devices 1 and 2 can be appropriately stopped at the developing position without applying an unnecessary vertical force to the developing devices 1 and 2.

Further, since all parts of the drive motor 9 and the like of the switching mechanism 3 are arranged on the frame 12 as a unit, a drive belt, a pulley and the like for connecting the drive shaft 4 to the drive means outside the frame 12 are provided. It is not necessary to separately arrange
The switching mechanism 3 can be made smaller. Further, when the switching mechanism 3 is replaced, the frame 12 can be replaced together, which facilitates maintenance.

Further, since the driven members 7 and 8 are formed of elastic members, the stoppers (not shown) for stopping the developing devices 1 and 2 at the developing position, for example, by the elastic force of the levers 71 and 81. The contact force with respect to is adjusted. As a result, it is not necessary to separately provide a spring or the like, and the structure can be simplified.

The phase difference between the cams 5 and 6 is not limited to the angle (180 °) shown in FIG. 1, but when the developing device 1 moves to the developing position, the developing device 2 returns to the separated position. Conversely, the angle may be such that the developing device 1 returns to the separated position when the developing device 2 moves to the developing position.

Although the number of developing devices is two in the above embodiment, the present invention can be applied to the case where the number of developing devices is three or more. In this case, the number of cams and driven members may be increased according to the number of developing devices, and the angles of the cams may preferably be set to be equal.

Further, by connecting the developing devices 1 and 2 to the driven members 7 and 8, the driven members 7 and 8 may be moved to the right by the biasing means of the developing devices 1 and 2. In this case, the levers 72 and 82 are unnecessary.

Further, in the above-described embodiment, the developing devices 1 and 2 are biased from the photosensitive drum 32 in the separating direction by the biasing means, but instead of the biasing means, the developing devices 1 and 1 are biased. 2 and the driven members 7 and 8 may be connected to each other, and the developing devices 1 and 2 may be pulled rightward by the driven members 7 and 8 to be separated from the photosensitive drum 32.

[0031]

According to the present invention, since the developing device is guided to the developing position by the uniaxial structure, the structure is simplified and the space can be saved. Therefore, the size can be reduced. Further, since the rotational force of the cam is once converted into reciprocating motion by the driven member to move the developing device, unnecessary force in the vertical direction is not applied to the developing device, and the developing device can be appropriately stopped at the developing position. Therefore, proper development can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a switching mechanism according to the present invention.

FIG. 2 is a schematic configuration diagram showing an operation of a switching mechanism.

FIG. 3 is a schematic configuration diagram showing an example of drive means of a switching mechanism.

FIG. 4 is a schematic configuration diagram showing an example of an image forming apparatus.

FIG. 5 is a schematic configuration diagram showing a conventional switching mechanism.

[Explanation of symbols]

 1, 2 developing device 1a, 2a developing sleeve 3 switching mechanism 4 drive shaft 5,6 cam 5a, 6a apex of cam 7,8 driven member 9 drive motor 10 worm 11a, 11b gear 12 frame 71, 72, 81, 82 lever 73,83 Pushing surface 74,84 Guide hole 121-124 pin

Claims (1)

[Claims] 1. A switching mechanism of a developing device for switching a first developing device and a second developing device to guide a developing position from a distance from a photoconductor to a developing position where development is possible. And first and second cams that are fixed in parallel with the drive shaft with a predetermined phase difference, and the first and second cams.
A guide portion that is provided corresponding to the second cam and is slidably supported from the separated position to the developing position of the developing device, and is interposed between the peripheral surface of the corresponding cam and the developing device, and by the rotation of the cam. A first and a second driven member, each of which comprises a lever for moving the developing device to the developing position, and a pushing surface for abutting the developing device to push the developing device. Development device switching mechanism.