JPH0772720A - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] To provide an image forming apparatus having a developing device contacting / separating mechanism which has a relatively simple structure and does not take up space. A developing device 14 for visualizing a latent image formed on a photoconductor 1 is provided, and the developing device is configured to be movable between a developing position close to the photoconductor and a non-developing position separated from the photoconductor. In an image forming apparatus using a cam mechanism as its contact / separation mechanism, a pair of cam followers 30a, 30b connected to the cam mechanism of the contact / separation mechanism are provided, and the pair of cam followers 30
a and 30b are always in contact with the cam 26, and the relationship between the contact positions of the pair of connected cam followers 30a and 30b is about 180 ° with respect to the rotation center of the cam 26. . [Effect] When the cam mechanism is used as the contact / separation mechanism of the developing device, the problem of the idling of the cam can be prevented, the contact / separation movement of the developing device can be smoothly performed, and the impact noise due to the abrupt movement of the developing device is generated. The problem of generation and blowing of the developer is solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a laser beam printer and a facsimile.

[0002]

2. Description of the Related Art Conventionally, there has been known an image forming apparatus which forms an image of two or more colors by arranging a plurality of developing devices around one photoconductor, for example, in a two-color color copying machine. , A developing device containing a black developer and a developing device containing a developer of a color other than black such as red and blue are arranged around one photosensitive drum to perform development. There is. In the image forming apparatus having such at least two developing devices, since development is performed for each color, when one developing device approaches the photoconductor, the other developing devices separate from the photoconductor. As a contacting / separating mechanism for moving the developing device, a mechanism combining a cam, a lever (cam follower) and a link is known (for example, Japanese Patent Laid-Open No. 62-15563).
JP-A-62-75675, etc.).

[0003]

However, as in the prior art, two or more developing devices are arranged around the photosensitive drum, and each developing device has a combination of a cam, a lever (cam follower) and a link. If a separation mechanism is provided,
There is a problem that a large space is required around the photosensitive drum for its contacting / separating mechanism, and the device cannot be downsized. Further, in the structure in which the developing device is brought into contact with and separated from the developing device through the lever (cam follower) and the link by the cam, and the one end side of the lever is driven by being brought into contact with the cam, the developing device has the developing position (contact position with the photoconductor) When moving from the non-developing position to the non-developing position (the position where the photoconductor does not contact), the cam may idle due to the load from the lever side. There is also a problem in that the developer is blown out due to the occurrence of a toner or an impact.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus having a contact / separation mechanism that has a relatively simple structure and does not take up space.
Further, it is another object of the present invention to solve the problems such as the generation of impact noise due to idling of the cam and the blowing of the developer when the cam mechanism is used as the contact / separation mechanism.

[0005]

In order to achieve the above object, the invention of claim 1 has a developing device for visualizing a latent image formed on a photosensitive drum, and the developing device is exposed to light. In an image forming apparatus that is configured to be movable to a developing position that is close to the body drum and a non-developing position that is separated from the body drum, and that uses a cam mechanism for the contact / separation mechanism, a pair of cam followers connected to the cam mechanism of the contact / separation mechanism is provided. It is characterized in that the pair of cam followers are always in contact with the cam.
Further, in the image forming apparatus, the relationship between the contact positions of the pair of connected cam followers is as follows:
It is characterized by having a positional relationship of about 180 ° (claim 2).

According to the invention of claim 3, there is provided a developing device for visualizing the latent image formed on the photosensitive drum,
In an image forming apparatus in which the developing device is configured to be movable to a developing position close to the photoconductor drum and a non-developing position separated from the photosensitive drum, and a cam mechanism is used as a contact / separation mechanism of the developing device, an end surface of the cam of the contact / separation mechanism is provided. The cam follower is provided with an abutting elastic member.

[0007]

According to the image forming apparatus of the present invention, a pair of connected cam followers is provided in the contacting / separating mechanism of the developing device.
The pair of cam followers are always in contact with the cams. Therefore, if the pair of cam followers are brought into contact with the cams so as to sandwich the cams, the idling of the cams is prevented, and further the cam follower according to claim 2
As described above, by making the contact position of the pair of connected cam followers have a positional relationship of about 180 ° with respect to the center of rotation of the cam, idling of the cam is further prevented and rotation of the cam becomes smooth. .

In the image forming apparatus of the third aspect, since the elastic member that comes into contact with the end surface of the cam of the cam mechanism that constitutes the contacting / separating mechanism of the developing device is provided on the cam follower, the braking action by the elastic member is similar to the above. The cam is prevented from idling and the cam rotates smoothly.

[0009]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention, in which reference numeral 1 is a drum-shaped photosensitive member which is rotationally driven in a clockwise direction. Below the photoconductor 1, a paper conveyance path from the paper feed cassette 2 to the paper ejection receiver 3 is provided. In the paper conveyance path, a paper feed roller 5, a registration roller 6, a transfer device 7, and a fixing unit. And the container 8 are arranged. Around the photosensitive member 1, a first charger 9, a first exposure system 10, a first developing device 11, a second charger 12, and a second charger are provided.
Exposure system 13, second developing device 14, cleaning unit 1
5, a static eliminator 16 is provided. A document reading optical system is provided above the image forming unit, and the document placed on the contact glass is irradiated with light from the light source, and the reflected light image from the document is reflected by the mirror, lens, and color separation. An image is formed on the image sensor 17 via a filter or the like, and black image information 171 and image information 172 other than black are stored in the image information storage units 17a and 17b, respectively.

The first developing device 10 is loaded with toner of a specific color (for example, black), and the second developing device 14 is loaded with toner of another color (for example, red). The device provides a two color image with two color toners. That is, when forming an image of a specific color, the photoconductor 1 is uniformly charged by the first charger 9, and image exposure is performed by the first exposure system 10 based on the image information signal from the image information recording unit 17a. Then, an electrostatic latent image is formed, and the latent image is developed by the first developing device 11 and visualized. When forming an image other than black, the photoconductor 1 is uniformly charged by the second charger 12, and image exposure is performed by the second exposure system 13 based on the image information signal from the image information recording unit 17b. Then, an electrostatic latent image is formed, and the latent image is developed by the second developing device 14 and visualized.

The second developing device 14 is used only for forming a two-color image or a monochromatic red image. Therefore, in order to prevent consumption and contamination of the developing device, the second developing device 14 is movably provided between a developing position which is close to the photoconductor 1 and a non-developing position which is separated therefrom. That is, in the case of forming only a black image, the second developing device 14 is moved to the non-developing position separated from the photoconductor 1, and the development is performed only by the first developing device 11 as described above. Transferred to recording paper.
Further, when forming a two-color image, the second developing device 14 is moved to a developing position close to the photoconductor 1, and after the development by the first developing device 11, the second developing device 1 is operated as described above.
4 is developed, and the two-color image is transferred onto the recording paper.

Here, the contact / separation mechanism of the second developing device 14 is shown in FIG.
This will be described with reference to FIGS. In FIG. 2, reference numeral 21 denotes a leaf spring member that presses the developing device 14, and is provided at two positions on the front side and the back side with respect to the paper surface. The leaf spring member 21 is fixed to a drive shaft 22 which is rotated by a predetermined angle by a cam mechanism which will be described later, and is rotated clockwise about the drive shaft 22 by an angle θ to push the developing device 14 toward the photoreceptor 1. Contact the developing roller. Drive and bias are transmitted to the developing roller of the developing device 14 which is in contact with the developing device 14, and toner is attached to the electrostatic latent image on the photoconductor 1 to perform development. After completion of development, the leaf spring member 21
Rotates counterclockwise about the axis 22 by an angle θ,
The developing device 14 is pressed by the releasing leaf spring member 23 and separated from the photoconductor 1, and returns to the non-developing position.

The leaf spring member 21 is rotated by the cam mechanism shown in FIGS. The gear 24 is rotated clockwise by driving a motor of the image forming apparatus main body (not shown). The rotation of the spring 26 causes the cam 26 to rotate.
Tell. One side of the spring clutch 25 is connected to the cam 26, and the other end is connected to the sleeve 27.
Claws 27a and 27b are provided on the surface of the sleeve 27, and the protrusion 29a of the arm 29 connected to the solenoid 28 abuts the surface of the sleeve 27, so that the solenoid O
The protrusion 29a of the arm 29 is caught by the claws 27a and 27b by N and OFF. At that time, since the spring clutch 25 is loosened, the rotation from the gear 24 is cut off and the cam 26 is stopped. As shown in FIG. 4, the cam 26 has a pair of connected cam followers 30 (30a, 30a).
b) comes into contact and moves about the drive shaft 22 by an angle θ by the rotation of the cam 26. When the cam 26 is at the top dead center position, the developing device 14 is at the developing position, and when the cam 26 is at the bottom dead center position, the developing device 14 is at the non-developing position.

Next, the movement of the cam 26 and the pair of cam followers 30 (30a, 30b) will be described with reference to FIG. As shown in FIG. 4A, one end of one cam follower 30a is fixed to the drive shaft 22 and the other end of the cam follower 30a is in contact with the cam 26. When the cam 26 is at the top dead center position, the cam follower 30a does not move. A load force F ₁ by the leaf spring member 21 for contacting the developing device 14 with the photoconductor ₁ is applied via the drive shaft 22. Here, if the cam follower is only 30a, when the cam 26 moves from the top dead center to the bottom dead center as shown in FIG. 4C, the force F ₁ from the cam follower 30a causes the cam 26 to move.
Is pressed and idling occurs. That is, the cam 26 is shown in FIG.
When rotating from the bottom dead center of (b) to the top dead center of (a), the force F ₁ from the cam follower 30a acts in the direction opposite to the rotation direction of the cam 26, but FIG. When the cam 26 moves from the top dead center to the bottom dead center as described above, the force F ₁ from the cam follower 30a acts in the rotation direction of the cam 26, and at this time, the rotation direction of the cam 26 and the spring clutch connected to the cam 26. Since the loosening direction of 25 is the same direction, the force acting in the arrow F ₁ direction of the load from the cam follower 30a acts in the loosening direction of the spring clutch 25,
The cam 26 will idle. When the idling of the cam 26 occurs, the developing device rapidly moves to the non-developing position.
Impact noise and toner blowout occur.

Therefore, in the present invention, in order to prevent the idling of the cam 26, a pair of cam followers 30 connected to the cam mechanism are provided.
a, 30b are provided, and a pair of cam followers 30a, 3b
0b is always in contact with the cam 26. The cam follower 30a is connected to the cam follower 30a by a spring 32 at one end with the connecting shaft 31 as a fulcrum, and the cam follower 30a and the cam follower 30b are
The cam 26 is held by the force of the spring 32, and is always in contact with the cam 26 in a positional relationship of about 180 °. As a result, the cam follower 30b becomes the cam follower 3b.
One of the cam followers 30a moves in the opposite direction to 0a.
Force F ₁ exerted on the cam 26 from the other cam follower 30 b
Is canceled by the force F ₂ exerted on the cam 26 from. Therefore, the idling of the cam 26 is eliminated and the cam 26 rotates smoothly. This allows the developing device to move smoothly,
The problem of impact noise and toner blowout is solved.

Next, FIG. 5 is a schematic configuration diagram of a contacting / separating mechanism showing an embodiment of claim 3. The configuration of the drive mechanism of the cam 26 is the same as that of FIG. 3, but in the present embodiment, the elastic member 40 (for example, a metal plate spring) that comes into contact with the end surface of the cam 26 is provided in the cam follower 30. This elastic member 40 is
When the end surface on the side of the top dead center passes, it comes into contact with the end surface and gives a braking action to the cam 26. For this reason, the idling of the cam 26 is suppressed, and the rotation becomes smooth. As a result, the developing device can be moved smoothly, and problems such as the generation of impact noise and the blowing of toner can be solved.

[0017]

As described above, in the image forming apparatus of the first aspect, the cam mechanism constituting the contacting / separating mechanism of the developing device is provided with the pair of connected cam followers, and the pair of cam followers always contact the cam. Therefore, if the pair of cam followers makes contact with the cam so as to sandwich it, idling of the cam is prevented. Further, as described in claim 2, the contact position of the pair of connected cam followers is set to a positional relationship of about 180 ° with respect to the rotation center of the cam, whereby the idling of the cam is further prevented, and the rotation of the cam is prevented. Becomes smooth. Therefore, according to the image forming apparatus of claims 1 and 2, when the cam mechanism is used as the contact / separation mechanism of the developing device, the idling of the cam can be prevented, and the contact / separation movement of the developing device can be smoothly performed. The problems such as the generation of impact noise due to the abrupt movement of the developing device and the blowing of the developer are solved.

Further, in the image forming apparatus of the third aspect, the elastic member that comes into contact with the end face of the cam of the cam mechanism constituting the contacting / separating mechanism of the developing device is provided in the cam follower, and the elastic member brakes the brake. Similarly to the above, the idling of the cam is prevented and the cam rotates smoothly. Therefore, according to the image forming apparatus of the third aspect, when the cam mechanism is used as the contacting / separating mechanism of the developing device, the idling of the cam can be prevented, and the contacting / separating movement of the developing device can be smoothly performed. Problems such as the generation of impact noise due to the rapid movement of the container and the blowing of the developer are eliminated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention and is an explanatory diagram of a contacting / separating mechanism of a developing device.

FIG. 3 is a diagram showing an embodiment of the present invention and is an explanatory diagram of a cam mechanism used as a contact / separation mechanism of the developing device.

FIG. 4 is a diagram showing an embodiment of the present invention and is an explanatory diagram of a configuration and an operation of a cam mechanism used as a contact / separation mechanism of the developing device.

FIG. 5 is a view showing another embodiment of the present invention and is a schematic configuration diagram of a contacting / separating mechanism of the developing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photosensitive member 2 ... Paper feeding cassette 5 ... Paper feeding roller 6 ... Registration roller 7 ... Transfer device 8 ... Fixing device 9 ... First charging device 10 ... 1st exposure system 11 ... 1st developing device 12 ... 2nd charging device 13 ... 2nd exposure system 14 ... 2nd developing device 15 ... Cleaning unit 16 ... Static eliminator 17 ... ..Image sensor 21 ... Leaf spring member 22 ... Drive shaft 23 ... Release leaf spring member 24 ... Gear 25 ... Spring clutch 26 ... Cam 27 ... Sleeve 28 ... -Solenoid 29 ... Arm 30 (30a, 30b) ... Cam follower 31 ... Connection shaft 32 ... Spring 40 ... Elastic member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuhiro Shima Shima 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Hiromitsu Takagaki 1-3-6 Nakamagome, Ota-ku, Tokyo・ Ricoh Co., Ltd. (72) Inventor Kazuhiro Nishido 1-3-6 Nakamagome, Ota-ku, Tokyo ・ Ricoh Company (72) Inventor Naoki Iwata 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hidetoshi Yano 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (3)

[Claims] 1. A developing device for visualizing a latent image formed on a photosensitive drum, wherein the developing device can be moved to a developing position close to the photosensitive drum and a non-developing position separated from the developing position. In the image forming apparatus using the cam mechanism as the contact / separation mechanism, a pair of cam followers connected to the cam mechanism of the contact / separation mechanism are provided, and the pair of cam followers are always in contact with the cam. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the contact position of the pair of connected cam followers is about 180 ° with respect to the center of rotation of the cam. apparatus. 3. A developing device for visualizing a latent image formed on a photosensitive drum, wherein the developing device can be moved to a developing position close to the photosensitive drum and a non-developing position separated from it. In the image forming apparatus using the cam mechanism as the contact / separation mechanism, an elastic member that comes into contact with the end surface of the cam of the contact / separation mechanism is provided in the cam follower.