JPS62280877A - Developing device - Google Patents

Abstract

PURPOSE:To exactly prevent a foreign matter from adhering to the surface of a developing member, by providing a shutter member for holding an outside exposed surface of the developing member, in an open position, in a developing action position, and holding said surface in a closed position, in a non-developing action position. CONSTITUTION:When a semi-rotation driving of a cam 21 is started in a state that a developing device A is held in a developing action position against a drum B, the inside surface of a rear side lug 18 receives a pressing force by a raised part of the cam, and a base plate 12, namely, the developing device A moves backward against the drum B. At the time point when the semi-rotation of the cam 21 has been ended, its retreat amount becomes maximum, and the developing device A is switched to a non-developing action position where it has been saved as prescribed against the drum B (a developing sleeve 2 has been separated as prescribed from the surface of the drum B). On the other hand, as for a shutter member 9 which has been held in an open position, a shutter member opening/closing mechanism is operated at the time point being near an end period of a retreat process by interlocking with a retreat motion of the developing device A, executes a closing turn without interfering with the surface of the drum B, and the shutter member is held in a closed position where the surface of the developing sleeve has been hidden.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention A. Object of the Invention [Field of Industrial Application] The present invention relates to a developing device for an image forming apparatus such as an electronic copying device or an electrostatic recording device.

More specifically, the rotary acid in electrophotography is a rotating photoreceptor, and the rotary acid in electrostatic recording is a rotating dielectric member, etc., which has a developing action position that is close to a predetermined distance to a member to be developed (I image bearing member) and a predetermined position. The present invention relates to a developing device which is arranged so as to be switchable between a non-developing operation position and a retracted (retracted) position.

[Conventional technology]

For example, the above-mentioned developing device configuration includes a plurality of developing devices containing developers of different colors arranged sequentially along the surface movement direction of the member to be developed, and selecting one of the developing devices. It is adopted as a means to avoid so-called mixed color development in image forming apparatuses that can form monochrome images, multicolor images, or full color images (Japanese Patent Publication No. 55-3707). ).

That is, each developing device can be switched and moved between a developing position and a non-developing position with respect to the member to be developed as described above,
While one selected developing device is switched to a developing position with respect to the member to be developed and is performing the developing action, the other developing devices are kept on standby in non-developing positions that are evacuated from the member to be developed. It is.

[Problem that the invention seeks to solve]

However, in practice, there were the following inconveniences.

(1) If the developing devices arranged sequentially along the direction of surface movement of the member to be developed use developer Lt of magnetic toner, the developing device located upstream in the direction of surface movement of the member to be developed A process in which the surface of the member to be developed passes through a developing device position which is held in a non-developing position with respect to the member to be developed, downstream of the developing device in the direction of surface movement of the member to be developed. Then, a part of the magnetic toner constituting the developed image on the surface of the developing member is attracted to the developing member side by the magnetic field of the developing member of the downstream developing device, and the surface of the developing member is attracted. It is easy to get contaminated with colored toner.

(2) If the upstream developing device uses a two-component developer of torch and magnetic particle carrier, and the downstream developing device uses a one-component developer of magnetic toner, the upstream developing device As the surface of the member to be developed passes through the developing device position on the downstream side, which is held in a standby position in a non-developing position with respect to the member to be developed, a very small amount is deposited on the surface of the member to be developed. However, the surface of the developing member of a developing device using a one-component developer, where magnetic particle carriers that have adhered and are carried out from the upstream developing device are easily transferred and attracted to the developing member side by the magnetic field of the developing member of the downstream developing device. When such foreign particles such as magnetic particle carriers are adsorbed, the developing performance of the developing device decreases.

One way to solve the above-mentioned problems (1) and (2) is to set the non-developing position of each developing device with respect to the member to be developed at a position quite far away from the member to be developed. The moving length of the developing device between the developing operating position and the non-developing operating position increases, leading to an increase in the size of the developing device moving mechanism section and, by extension, the overall size of the image forming apparatus.

It is a good measure to protect the surface of the developing member of the developing device with a shutter member.

Conventionally, for the purpose of protecting the externally exposed surface of the developing member of a developing device taken out from the image forming apparatus main body for maintenance, inspection, repair, etc., when the developing device is taken out from the image forming apparatus main body, a defective member is used. Some devices are equipped with a shutter member A that is held in a closed position that hides the externally exposed surface, and is held in an open position that leaves the developing member surface open when the developing device is in the main body of the image forming apparatus.

However, when the developing device is inside the main body of the image forming apparatus, this shaft member is held in the open position even when the developing device is in the non-developing position with respect to the member to be developed. There is no function to prevent adhesion of antiparticle carriers to the surface of the developing member a' of the developing device which is held in standby position.

The present invention has been proposed in view of the above, and uses a simple shutter member configuration that operates rationally to prevent magnetic toner/magnetic particle carriers, etc. An object of the present invention is to provide a developing device that reliably prevents the adhesion of foreign matter.

Summary: Structure of the Invention [Means for Solving the Problems] The present invention is arranged so that it can be switched between a developing position close to a member to be developed and a non-developing position retracted to a predetermined position. In the developing device, the developing device opens and closes in conjunction with the above-mentioned position switching movement of the developing device, and in a developing action position of the developing device with respect to the member to be developed, an externally exposed surface of the developing member that faces and acts on the member to be developed is opened. The gist of the blade is that it is provided with a developer member face shutter member that is held in the open position and held in the closed position where it is concealed in the non-developing position.

[For production]

With the above configuration, when the developing device is held in a standby position in a non-developing position relative to the developing member, the surface of the developing member is hidden by the closed shutter member and is protected from adhesion of foreign matter. When in the developing action position, the shutter member escapes from the surface of the developing member, and the surface of the developing member is released, allowing development of the member to be developed to be performed without any trouble.

〔Example〕

Embodiment 1 (Figs. 1 to 4) In Figs. 1 and 2, A is the overall code of a developing device, and B is a drum-type photoreceptor (hereinafter referred to as drum) for electrophotography, for example, as a member to be developed.

The drum B is rotated clockwise at a predetermined circumferential speed, and an electrostatic Wi image is formed on its circumferential surface by an appropriate known latent image forming process device (not shown), and the image passes through a developing section a facing the developing device A. do.

In the developing device A, 1 is a developer container, and 2 is a non-magnetic developing member that is placed horizontally on the front wall side of the developer container with the right half side inserted into the container and the left half side exposed outside the container. The developing sleeve is rotated counterclockwise at a predetermined circumferential speed. Reference numeral 3 denotes a fixed (non-rotating) magnet roller as a magnetic field generating means which is inserted and built into the developing sleeve, and 4 is a fixed (non-rotating) magnet roller provided coaxially and freely rotatable at both ends of the developing sleeve 2, at a predetermined position than the developing sleeve 2. A large diameter spacer roller, 5 is a doctor blade that applies a developer layer to a predetermined thickness on the two surfaces of the developing sleeve, T is a one-component developer made of magnetic toner in the developer container, or 2 is a one-component developer made of toner and a magnetic particle carrier. Component developer, 6 a rotating member for stirring and transporting the developer in the container, 7 a pair of wire antennas for detecting the amount of developer, 8
indicates the developer replenishment port.

Reference numeral 9 corresponds to the surface of the developing sleeve 2 exposed outside the container.

This is an opening/closing shutter member with an arcuate cross section. In FIG. 1, the developing device A is switched to a non-developing position where it is retracted (retracted) to a predetermined position with respect to the drum B, and the above-mentioned shutter section and material 9 are in the closed position, so that the developing sleeve 2 is exposed to the outside. FIG. 2 shows a state in which the surface is hidden by the shutter member, when the developing device A is switched to the developing operating position where it approaches (advances) a predetermined distance with respect to the tram B, and the shutter member 9 is in the open position. A state in which the externally exposed surface of the dovetail developing sleeve 2 is open is shown.

(1) Mechanism for switching and moving the position of the developing device This mechanism will be mainly explained with reference to FIG. 1@2. 10 is an immovable developing device support base plate in the main body of the image forming apparatus; 11 is a slippery resin layer provided as a lining on the upper surface of the support base plate; 12 is placed on the resin layer; This is a developing device mounting base plate that can slide freely only in the forward direction toward the drum B and in the opposite backward direction.

The developing device mounting base plate 12 is made of plywood long in the direction perpendicular to the drawing, and its front and rear sides are respectively bent upward to form rail strips 13-14 parallel to each other. On the other hand, developing device A
The lower surface is provided with mutually parallel rail strips 15 and 16 corresponding to the rail strips 13 and 14 on the base plate 12 side.

The developing device A develops the top of the base plate 12 by bringing the rear ends of the rail strips 15 and 16 on the lower surface into engagement with the front ends of the rail strips 13 and 14 on the base plate 12 side, respectively, and pushing them. It slides toward the back side while being guided by the rail strips 13-14. By pushing the developing device A sufficiently until it hits a stopper (not shown) and is received, the developing device A is placed in a proper position on the base plate 12. That is, it is installed inside the main body of the image forming apparatus. Conversely, by pulling it out from above the base plate 12 toward the front, it can be taken out of the image forming apparatus. The insertion and removal of the developing device A from the base plate 12, that is, the insertion and removal from the image forming apparatus, is performed when the base plate 12 is in a position retracted from the drum B as shown in FIG.

The developing device A mounted on the base plate 12 advances and retracts integrally with the drum B as the base plate 12 moves forward and backward with respect to the drum B.

Reference numerals 17 and 18 denote a pair of downwardly parallel cut-and-raised lugs 19 provided at two locations on the front and back sides of the developing device mounting base plate 12, one on the front end and the other on the back end, respectively. 20 is a plate spring piece attached to the inside of the front lug 17 with screws, 20 is a camshaft located between the lugs 17 and 18, and both ends are supported by bearings on a fixed member on the image forming apparatus side; 21 is a camshaft; It is a cam (eccentric disc) fixed to the camshaft.

Although not shown in the figure, the camshaft 20 is connected to a rotational drive source via a clutch. The clutch is a well-known half-rotation type consisting of a renoid spring clutch, control pawl, etc.
Each time a signal is input to the solenoid from the control circuit, the clutch is actuated and the camshaft 20 is controlled to rotate intermittently by half a rotation in the clockwise or counterclockwise direction.

As shown in FIG. 1, when the cam 21 is driven half a rotation in a state where the developing device A is in a non-developing position where it is retreated a predetermined distance from the drum B, the developing device A approaches the drum B to a predetermined value. It is then switched to the developing position shown in FIG. 2 and held at that position. That is, when the cam 21 starts to be driven half a rotation, the front lug 17 receives a pressing force from the raised portion of the rotating cam via the leaf spring piece 19, and the developing device mounting base plate 1
2, that is, the developing device 5mA is moved forward with respect to the drum B.

In conjunction with this forward movement, a shutter member opening/closing mechanism, which will be described later, is operated in the forward movement process/initial stage D, and the shutter member 9, which is in the closed position covering the developing sleeve 2 surface, opens and rotates without interfering with the drum 3 surface. The developing sleeve is held in the open position with the surface open.

A little before the cam 21 completes half a rotation, the spacer rollers 4 on both ends of the developing sleeve come into contact with the drum surfaces on both ends of the drum B and are received. The forward movement of the base plate 12, ie, the developing device A, is prevented by the reception, and this position becomes the developing action position of the developing device A with respect to the drum B. The developing sleeves 2 are opposed to each other with a predetermined gap α defined by the spacer rollers 4 in contact with the surface of the drum 3.

Then, as the cam 21 continues to rotate to the half-rotation end position, the leaf spring 19 connects the highest protrusion of the cam 21 with the front lug 1.
7, the positional error is absorbed, and the developing action position of the developing device A with respect to the drum B is elastically maintained.

Conversely, when the cam 21 starts to be driven half a rotation while the developing device A is held in the developing position with respect to the drum B as shown in FIG. receives a pressing force, and the base plate 12, that is, the developing device WA, moves backward relative to the drum B. When the cam 21 completes half a rotation, the amount of retraction reaches its maximum, and as shown in FIG. is retracted to a predetermined position with respect to drum B (developing sleeve 2
is switched to a non-developing position (a predetermined distance from the surface of the drum 3). On the other hand, the shutter member 9 held in the open position interferes with the surface of the drum 3 when a shutter member opening/closing mechanism, which will be described later, operates in conjunction with the reversing of the developing device A and near the end of the retracting process. The developing sleeve is rotated closed and held in the closed position where the surface of the developing sleeve is hidden.

(2) Shutter member opening/closing mechanism This mechanism will be explained mainly with reference to FIGS. 3 and 4.

Dowel shafts 30 are provided on the outer surfaces of the front end plate and the rear end plate of the developer container 1, respectively, substantially coaxially with the rotation center axis of the developing sleeve 2, and 31 are dowel shafts provided at both ends of the shutter member 9, respectively, facing inward. The two arm plates 31 are each supported by the dowel shaft 30 via a bearing 32 so as to be freely rotatable about the shaft. Therefore, the shutter member 9 is free to swing approximately concentrically with the developing sleeve 2 about the dowel shaft 30.

The bearing 32 of the arm plate 31 on the near side of the shutter member 9 is provided with a fan-shaped gear portion 32a on a part of its outer periphery, and is also provided with an inward protrusion 32b. The arm plate 31 is integrated with the arm plate 31, that is, the shutter member 9, by fitting into a notch hole provided in the arm plate 31, that is, the shutter member 9. The relative position of the fan-shaped gear portion 32a on the bearing 32 side and the shutter member 9 is maintained by the fitting engagement between the projection portion 32b and the hole on the arm plate 31 side.

Reference numeral 33 designates a two-stage fan-shaped gear that can freely rotate around a bottle shaft 34 that is implanted on the outer surface of the front end plate of the developer container 1. 2 sector gear part 3
3b. The first fan-shaped gear portion 33a is the bearing 3
It meshes with the fan-shaped gear portion 32a on the second side.

Reference numeral 35 designates a lever that is freely rotatable around a bottle shaft 36 that is also implanted on the outer surface of the front end plate of the developer container 1. This lever 35 is always urged to rotate clockwise by a spring 37. The tip of the arm on the left side of the bottle shaft 36 is a sector-shaped gear part 35a, which meshes with the second sector-shaped gear part 33b of the two-stage sector gear 33. The tip of the right arm is a cam follower part 35b.

In the free state, the lever 35 rotates clockwise due to the biasing force of the spring 37, and accordingly, the gear portion 35a*33bs
33a * 32a, the bearing 32, and the arm plate 31, the shutter member 9 is rotated clockwise, which is the closing direction, with respect to the developing sleeve 2 around the dowel shaft 30, and the upper side 9a is rotated as shown in the third figure. comes into contact with the outer surface of the front wall of the developer container 1, and the receiver is in a stopped state, and is held in a closed position with respect to the externally exposed surface of the developing sleeve 2.

Reference numeral 38 denotes a stationary cam fixedly attached by screws to the upper surface near the front side of the above-mentioned immovable developing device support base plate 10, and corresponds to the cam follower portion 35b of the lever 35 on the developing device A side.

When the developing device A is switched to the non-developing position with respect to the drum B as shown in FIG. It corresponds to the surface portion 38c. In this state, the lever 35 is in a free state, and therefore, the shutter member 9 is held in the closed position with respect to the developing sleeve 2, as described above.

When the developing device A is moved forward from this state to the developing position with respect to the drum B by the operation of the position switching mechanism of the developing device, the cam follower portion 35b of the lever 35 is moved toward the rear side of the cam 38 at the beginning of the forward movement process. lower surface part 3
From 8c, the lever 35 climbs up the comparative slope part 38b and corresponds to the higher surface part 38a on the front side, thereby rotating the lever 35 counterclockwise about the bottle shaft 36 against the spring 37.

This causes the shutter member 9 in the closed position to move to the gear portion 35.
ae33bs33ae32a, the bearing 32° arm plate 31 rapidly rotates the developing sleeve 2 around the dowel shaft 30 in the counterclockwise direction, which is the opening direction, and the force J of the lever 35 causes the follower part 35b to act on the cam 38. When located at the starting end of the high surface portion 38a, the developing sleeve 2 is rotated to the open position (FIG. 4) in which the externally exposed surface is fully opened.

This opening operation of the shutter member 9 is performed by the drum B of the developing device A.
Since this is completed at the beginning of the forward movement process, the shutter member 9 will not interfere with the surface of the drum B during the subsequent forward movement process of the developing device A.

The developing device A finally reaches the developing position as described above. Meanwhile, the cam follower part 35b of the lever 35 is connected to the cam 3.
By continuing to correspond to the high-level surface portion 38a of No. 8, the shutter member 9 is maintained in the open position.

Conversely, when the developing device A is moved back to the non-developing position with respect to the drum B from the state shown in FIG. The cam follower portion 35b of the cam 35 descends from the high surface portion 38a of the cam 38 down the slope portion 38b to the low surface portion 38c.
Corresponding to this, Shihachi-35 becomes free state, lever 3C% M IJ ↓ to 971 de ← 工 r 斗 - stirring d: 1 hill i Haruka h 1 Yui , ~l
11. The connector I9 is rotated closed relative to the developing sleeve 2, and is held in the closed position as shown in FIG. 3 (FIG. 1).

Since the closing operation of the shutter member 9 is started after the developing device 1A has sufficiently moved backward with respect to the drum B, the shutter member 9 that has been closed does not interfere with the surface of the drum B.

Thus, when the developing device A is in the developing position, the shutter member 9 relative to the developing sleeve 2 is opened and closed in conjunction with the switching movement between the developing position and the non-developing position of the developing device A with respect to the drum B. When the developing sleeve 2 is opened and faces the drum B in a predetermined manner, development can be carried out without any trouble, and when the developing device A is in the non-developing position, the developing sleeve 2 is kept hidden by the shutter member 9. Sufficient protection from foreign matter adhesion.

Note that when the developing device A is inserted into or removed from the image forming apparatus, as described above, the developing device A or the base plate 12 is placed in the non-developing position (the first
3), and at this time, the lever 35 is in the free state and the shutter member 9 is held in the closed position. Therefore, the surface of the developing sleeve 2 is protected by the shutter member 9 in the closed state. be done.

Embodiment 2 (FIGS. 5 and 6) This embodiment shows another embodiment of the shutter member opening/closing mechanism, and members common to those in Embodiment 1 are designated by the same reference numerals and will not be described again.

In this example, a bottle 33c is installed on the side surface of the two-stage fan-shaped gear 33, and a coil spring 40 is installed between this bottle 33c and a bottle 39 installed on the outer surface of the end plate on the front side of the developer container 1. is set up. The lever 35 is not provided with the rotation biasing spring 37 as in the first embodiment, and the cam follower portion of the lever 35 has first and second forked arm portions 35b, #35b2.
It's Toshide. The cam 38 on the plywood 10 side that acts on the bifurcated cam follower portion is a protruding cam.

FIG. 5 shows a state in which the developing device A is switched to a non-developing position relative to the drum B and is held therein. In this state, the coil spring 40 stretched between the bins 33c and 39 is in two stages. It is located on the right side of the rotation center shaft 34 of the sector-shaped sector gear 33, so that the two-stage sector gear 33 is urged to rotate counterclockwise about the shaft 34, and the rotational urging force causes the shutter member to move. 9 is stably held in the closed position.

When the developing device A is switched from this state to the developing position with respect to the drum B, the second protrusion 35b2 of the cam follower portion of the lever 35 comes into contact with the protruding cam 38, and the lever 35 is moved. It is rotated counterclockwise about the shaft 36, and in conjunction with this, the two-stage fan-shaped gear 33 is rotated clockwise about the shaft 34 while stretching the coil spring 40, and the shutter member 9 is rotated to open. is started. The coil spring 40 is connected to the shaft 34 of the two-stage fan-shaped gear 33.
When the shutter member 9 is displaced to the left, the contracting force of the coil spring 40 applies a clockwise rotation force to the two-stage gear 33 about the shaft 34, which causes the shutter member 9 to rapidly open. Stably held in the open position.

The developing device A continues to move forward into the developing position and is held there (FIG. 6).

Conversely, when the developing device A is switched from the developing position to the non-developing position, the second arm 35b2 of the cam follower portion of the hale lever 35 is moved until the developing device A moves backward to a position slightly before the non-developing position. The shutter member 9 is kept in contact with the protrusion cam 38, and <-35 is not rotated, and the shutter member 9 is maintained in the open state.

Next, the first arm portion 35b1 of the cam follower portion of the lever 35
comes into contact with the protruding cam 38 and the lever 35 is rotated clockwise about the shaft 36, and in conjunction with this, the two-stage fan-shaped gear 3
3 rotates counterclockwise around the shaft 34 while stretching the coil spring 40, and the closing rotation of the shutter member 9 is started. When the coil spring 40 is displaced to the right from the position of the shaft 34 of the two-stage fan-shaped gear 33, the contraction force of the coil spring 40 causes the two-stage gear 33 to rotate counterclockwise around the shaft 34. As a result, the shutter member 9 rapidly closes and is stably held in the closed position, resulting in the state shown in FIG.

Embodiment 3 (FIGS. 7 and 8) Components common to those in Embodiment 1 are given the same reference numerals and repeated explanations will be omitted.

This example shows the immovable fixed cam 38 on the plywood 10 in Example 1.
Instead, a notched cam 41 is fixed to the half-rotation cam shaft 20 of the position switching mechanism of the developing device, and the cam follower portion 35b of the lever 35 is related to the notched cam 41.

FIG. 7 shows a state in which the developing device A is switched to the non-developing position with respect to the drum B and is held therein. 4Lc is compatible and the cam follower part 3
It is in a non-contact state with respect to 5b. This allows lever 3
5 is in a free state, and the shutter member 9 is held in the closed position.

From this state, when the cam shaft 20 of the position switching mechanism of the developing device A is driven half a rotation (counterclockwise rotation), the eccentric cam 21 switches the developing device A to the developing position relative to the drum B. And its inscription 1h pickled shin fJ Negetsu 1
The rear end 41b of the circular arc surface portion of the circular cam 41 integrated with the grain cam 20 is the cam follower portion 35 of the lever 35.
b, and the lever 35 is rapidly rotated counterclockwise about the shaft 36 against the spring 37. As a result, the shutter member 9 rapidly opens and reaches the open position.

The developing device A continues to be moved forward relative to the drum B and reaches the developing position (FIG. 8). During this time, the cam follower portion 35b of the lever 35 is in corresponding contact with the arcuate surface portion 41a of the circular cam 41, and the shutter member 9 The opened state will continue to be maintained.

Conversely, from this state, when the camshaft 20 of the position switching mechanism of the developing device A is driven half a rotation and the eccentric cam 21 switches the developing device A to the non-developing position with respect to the drum B, the developing device Until the device A moves to a position slightly in front of the non-developing position, the cam follower portion 35b of the lever 35 continues to be in 8-contact with the arcuate surface portion 41a of the occluded cam 41, which rotates together with the camshaft 20, and the shutter is closed. The open state of the member 9 is maintained as it is.

Next, in the process of moving the developing device A to the non-developing position, the rear end 41d of the circular arc surface portion of the notched circular cam 41 is positioned corresponding to the shutter member 35b of the lever 35, and then the notched interior 4Lc
is in the corresponding position, and the edge of the occluded cam 41 relative to the cam follower portion 35b is cut. This causes the lever 35 to move freely
Then, the shutter member 9 is rapidly closed and rotated by the biasing force of the spring 37, and is held in the closed position relative to the developing sleeve 2 (FIG. 7).

In this example, a cam 41 for opening/closing the shutter member 9 is provided on the cam shaft 20 of the position switching cam 21 of the developing device A, and both are rotated about a common shaft, so that the cam 41 for switching the position of the developing device A can be moved. In order to ensure appropriate opening/closing operation timing of the shutter member, that is, to prevent the opening/closing shutter member 9 from interfering with the drum B, the developing device is switched from the non-developing position to the developing position at the initial stage of the movement process. When the opening operation of the shutter member 9 is completed, and conversely, when switching from the developing operation position to the non-development operation position, timing can be easily and reliably set to perform the closing operation of the shutter member 9 at the final stage of the movement process.

Even in the case of a configuration in which the position switching movement of the developing device A is performed by a pinion provided on a shaft capable of forward and reverse rotation and a rack provided on the side of the movable developing device mounting base plate 12, it is possible to change the position of the developing device A by using a pinion provided on the forward and reverse shaft provided with a pinion. Cam 41 for opening and closing the shutter member 9
Exactly the same effect can be obtained by integrally providing a member corresponding to the above.

Furthermore, even if the position switching movement of the developing device is not a linear movement but a swinging motion about an arbitrary point, the shutter member drive section is similarly configured integrally with the drive section that performs the swinging motion. This produces a locking effect.

C1 Effects of the Invention As described above, according to the present invention, different magnetic toners and magnetism are applied to the surface of a developing member such as a developing sleeve of a developing device which is held in a non-developing position with respect to a developing member such as a photosensitive drum. It can reliably prevent particle carriers and other foreign objects from being attached to the blade, and the intended purpose can be well achieved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIGS. 1 and 3 are a cross-sectional view and a side view of the developing device switched to the non-developing position, and FIGS. 2 and 4 are the developing device in the developing position. Cross-sectional view and side view of the developing device switched to , Figures 5 and 6
The figures are side views of other examples of the shutter member opening/closing mechanism, showing changes in state as the developing device position is changed;
The figure is the same figure as above of still another example. A is a developing device, B is a drum as a member to be developed, 2 is a developing sleeve, 9 is a shutter member for opening and closing the developing sleeve, 21 is a cam for changing the position of the developing device, and 38 and 41 are cams for opening and closing the shutter member. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 1 2120 fathom Figure 7

Claims (3)

[Claims] (1) In a developing device that is disposed so as to be able to switch between a developing position that approaches the member to be developed and a non-developing position that is retracted to a predetermined position, the developing device is moved in conjunction with the position switching movement of the developing device. When the developing device is in a developing position with respect to a member to be developed, the developing device is held in an open position in which the externally exposed surface of the developing member facing the member to be developed is open, and in a non-developing position, it is in a closed position where it is concealed. A developing device comprising: a shutter member for holding a developing member surface. (2) A cam member is fixedly arranged on a stationary member outside the developing device,
A cam follower member for the cam member is provided on the developing device side, and the opening/closing movement of the shutter member is controlled by a relative change in the action of the cam follower member and the cam member as the developing device changes its position. Developing device described in Section 1. (3) The developing device according to claim 1, wherein a driving source for opening and closing the shutter member is integrally provided with a driving source for switching and moving the position of the developing device.