JP3219440B2 - Switching mechanism of developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching mechanism for a developing device which switches a plurality of developing devices arranged for forming an image so as to approach a photosensitive member.

[0002]

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

In this image forming apparatus, a driving means is provided for each developing device and the structure is complicated. Therefore, as shown in FIG. 5, a driving shaft 50 is driven to rotate by a driving 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 provided with a switching mechanism is employed.

That is, the developing devices 1 and 2 are constantly urged rightward in the drawing by urging means (not shown).
In the case of performing the development, the drive shaft 50 is rotationally driven, for example, clockwise by a drive motor (not shown) or the like so that the cam 5
By rotating the developing roller 1, the developing device 1 is pushed toward the photosensitive drum 32 against the urging means. For this reason, as shown by the solid line in FIG. 5, the developing device 1 approaches the photosensitive drum 32 and moves to the developing position. On the other hand, the developing device 2 is moved to a separated position away from the photosensitive drum 32 by the urging means.

On the other hand, when the developing is performed by the developing device 2, the drive shaft 50 is rotated to rotate the cam 51 by 180 °, so that the cam 51 pushes the upper portion of the lever 52 to move the lever 52 around the shaft 53. Rotate clockwise.
For this reason, the lower portion of the lever 52 pushes the developing device 2 toward the photosensitive drum 32, and the developing device 2 approaches the photosensitive drum 32 and moves to the developing position as shown by a two-dot chain line in FIG. The developing device 1 is returned to the separated position away from the photosensitive drum 32 by the urging means.

[0006]

However, since the switching mechanism has a two-axis structure of the drive shaft 50 and the shaft 53, it is difficult to reduce the size.
Are supported by both side plates of a housing (not shown), so that these shafts 50, 5
3 had to be removed and attached, which reduced the workability.

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

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a switching mechanism of a developing device which can simplify the structure and reduce the size and can accurately set the developing device at a developing position. I do.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is to switch between a first developing device and a second developing device to switch a developing device from a separated position to a photosensitive member to a developing position where development is possible. A driving shaft, driving means for rotating and driving the driving shaft, first and second cams fixedly arranged in parallel with the driving shaft with a predetermined phase difference, and the first and second cams; And a first and a second driven member for moving the first and second developing devices from the separated position to the developing position, respectively .
The first and second developing devices are respectively located at the separated position and the current position.
The first and second driven members are slidably supported between the image position and the first and second driven members, respectively, such that the driven members slide in accordance with a moving range from the separated position of the corresponding developing device to the developing position. A guide portion slidably supported by the guide member, a lever interposed between the peripheral surface of the corresponding cam and the corresponding developing device, and moving the corresponding developing device to the developing position by rotation of the corresponding cam; And a pressing surface for pressing the developing device in contact with the developing device.

[0010]

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

[0011]

FIG. 4 is a schematic diagram showing an example of an image forming apparatus such as a copying machine provided with a switching mechanism for a developing device according to the present invention. The copying machine includes a contact glass 21 and a document holder 22 at an upper portion thereof, and includes an optical system L and an image forming unit P therein. The document presser 22 presses a document placed on the contact glass 21.

The optical system L includes a document irradiation lamp 23 such as a halogen lamp, a first moving frame 26 having a reflector 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 26 and the second moving frame 29 start moving, and at the same time, the document irradiation lamp 23 emits light and the contact glass 2 is moved.
Irradiate the original on the top of the document. The reflected light from the original is passed through the mirror 25 and mirrors 27 and 28 to the lens 3.
After being guided to 0, the photosensitive drum 3
Exposure 2

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 unnecessary charges are removed from the unnecessary area by the blank lamp 34, the original is exposed to the reflected light from the original, thereby forming an electrostatic latent image. This electrostatic latent image is stored in the developing device 1
Alternatively, the toner image is developed by the developing device 2, the toner image is transferred to transfer paper by the transfer device 35, and then separated from the photosensitive drum 32 by the separation device 36. On the other hand, the toner remaining on the photosensitive drum 32 is
7 removed.

Further, from the upstream in the feeding direction of the transfer paper,
Paper feed cassettes 38 and 39, paper feed rollers 40 and 41, transport roller pairs 42 and 43, and registration roller pairs 44 are provided. Then, the transfer paper in the paper feed cassettes 38 and 39 is taken out by the paper feed rollers 40 and 41, and is conveyed to the registration roller pair 44 by the conveyance roller pairs 42 and 43. The sheet is fed to the photosensitive drum 31 in synchronization with the scanning.

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

Next, an example of the structure of the switching mechanism of the developing devices 1 and 2 will be described with reference to FIGS. The switching mechanism 3 is disposed on the opposite side of the photosensitive drum 32 with respect to the developing devices 1 and 2, and includes a drive shaft 4, cams 5, 6, driven members 7, 8, a drive motor 9, a worm 10, and Gear 1
1a, 11b, etc. Also, the drive shaft 4, the pin 121
To 124, drive motor 9, worm 10, and gear 11
a and 11b are supported by the frame 12. Drive shaft 4
Is a drive motor 9, a worm 10, and a gear 1 shown in FIG.
It is rotationally driven by a driving means composed of 1a, 12b and the like. The cams 5 and 6 are fixed side by side in the axial direction of the drive shaft 4, and are located on the vertices 5 a and 6 a of the cams 5 and 6, that is, on the peripheral surfaces of the cams 5 and 6 and are most proximate to the axis of the drive shaft 4. The distant points are set to have a phase difference of, for example, 180 °.

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

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

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

The pushing surface 83 contacts the rear end of the developing device 2 and pushes the developing device 2 toward the photosensitive drum 32 (to the left in the figure) when the driven member 8 moves to the left. is there.
The guide hole 84 is formed in the left and right direction of the driven member 8, and guides the driven member 8 in the left and right direction by slidably fitting pins 123 and 124 fixed to the frame 12. The developing devices 1 and 2 are supported by a main body chassis (not shown) so as to be slidable in the left and right directions in the figure, and are urged toward the separated position by urging means (not shown) in consideration of fail-safe. I have.

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

Next, the operation of the switching mechanism 3 will be described with reference to FIG.
This will be described with reference to FIG. When developing the electrostatic latent image on the photosensitive drum 32 by the developing device 1, the driving shaft 4 is rotationally driven by the driving 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 and contacts 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. Then, the top 5a of the cam 5
As a result, the rotation of the drive shaft 4 is stopped in a state where the lever 71 of the driven member 7 is moved to the left most (the state of FIG. 1). At this time, the developing device 1 is at the developing position, so that 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 rightward, and the driven member 8 moves rightward. As a result, the developing device 2 is returned to the separated position away from the photosensitive drum 32.

On the other hand, the photosensitive drum 32
When developing the above electrostatic latent image, the drive shaft 4 is driven to rotate by the drive motor 9 and the like as described above. This drive shaft 4
With the rotation of, the lever 72 of the driven member 7 is pushed rightward by the cam 5, and the driven member 7 moves rightward. The apex 5a 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 a state in which the photosensitive drum 3 has been moved most to the right (the state of FIG. 2), the developing device 1
2 is a separated position. On the other hand, the rotation of the cam 6 due to 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 and abuts 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 lever 81 of the driven member 8 is moved to the left most by the apex 6a of the cam 6 (the state shown in 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.

As described above, since the switching mechanism 3 has a single-shaft structure of the drive shaft 4, space can be saved. In addition, the rotational force of the cams 5 and 6 is once
Since the reciprocating motion is converted to push the developing devices 1 and 2, unnecessary developing force is not applied to the developing devices 1 and 2 so that the developing devices 1 and 2 can be appropriately stopped at the developing position.

Further, since all parts of the switching mechanism 3 such as the drive motor 9 are disposed on the frame 12 and are unitized, a drive belt, a pulley, etc. for connecting the drive shaft 4 to a drive means outside the frame 12 are provided. There is no need to separately arrange
The size of the switching mechanism 3 can be further reduced. Further, when the switching mechanism 3 is replaced, the entire frame 12 can be replaced, and maintenance becomes easy.

Further, since the driven members 7 and 8 are formed of elastic members, for example, stoppers (not shown) for stopping the developing devices 1 and 2 at the developing position by the elastic force of the levers 71 and 81, respectively. The abutment force is adjusted. Thus, there is no need to separately provide a spring or the like, and the configuration can be simplified.

The phase difference between the cams 5 and 6 is not limited to the angle (180 °) shown in FIG. 1, and the developing device 2 returns to the separated position when the developing device 1 moves to the developing position. On the contrary, any angle may be used as long as the developing device 1 returns to the separated position when the developing device 2 moves to the developing position.

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

Further, by connecting the developing devices 1 and 2 with the driven members 7 and 8, the driven members 7 and 8 may be moved rightward by the urging means of the developing devices 1 and 2. In this case, the levers 72 and 82 become unnecessary.

Further, in the above embodiment, the developing devices 1 and 2 are urged in the direction away from the photosensitive drum 32 by the urging means. 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, downsizing can be achieved. In addition, since the rotational force of the cam is temporarily 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. And appropriate development can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating 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 illustrating an example of a driving unit of a switching mechanism.

FIG. 4 is a schematic configuration diagram illustrating 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/01 G03G 15/01-15/01 117 G03G 15/08-15/095

Claims (1)

(57) [Claims] 1. A switching mechanism for a developing device for switching a first developing device and a second developing device from a separated position to a photoreceptor to a developing position at which development is possible, comprising: a driving shaft; and driving means for driving the driving shaft to rotate. And the first and second fixedly arranged in parallel with the drive shaft with a predetermined phase difference.
And a first and second driven member provided corresponding to the first and second cams for moving the first and second developing devices from the separated position to the developing position, respectively. Wherein the first and second developing devices are respectively provided with the separated position and
Wherein is slidably supported between a developing position, said first, second driven members each said driven member is slid in response to the movement range from the spaced position of the corresponding developing device to a developing position A guide portion slidably supported as described above, a lever interposed between the peripheral surface of the corresponding cam and the corresponding developing device, and moving the corresponding developing device to the developing position by rotation of the corresponding cam; A switching mechanism for a developing device, comprising: a pressing surface that abuts on the corresponding developing device and pushes the developing device.