JPH01310367A - Developing device - Google Patents

Abstract

PURPOSE:To switch a developing system smoothly in a developing device having plural developing vessels by invariably bringing each developing system into contact with a drum, and moving a displacing part provided on either of them, thereby separating the developing vessels from a photosensitive drum. CONSTITUTION:The drum support 26 is provided on the both sides of a photosensitive drum 4, the support 26 setting the gap between the drum 4 and a developing role 22 of the developing vessel. The support 26 has a disc-like shape and is fixed on the same shaft with the drum 4. The developing systems 7 and 8 are invariably brought into press-contact with the support 26 via eccentric circular cams 27 and 28, respectively. The instant the eccentric circular cams 27 and 28 turn, the developing vessels 7 and 8 are separately moved in activating positions in proximity to the drum 4, with the cams 27 and 28 abutting on the support 26. Thus, they are not hit against a member on the side of the drum 4 when the developing systems 7 and 8 are moved in the activating positions; and the toner is prevented from spilling and dripping.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device used in an electrophotographic copying machine or the like capable of forming images in a plurality of colors.

[Prior Art] Conventionally, this type of developing device has been equipped with a plurality of developing devices that use toner of different colors and are arranged along the rotational direction of a photoreceptor drum. As the container, for example, one employing a magnetic brush development method is used. In the case of the above-mentioned developing device, if one developing device is in the vicinity of the photosensitive drum while another developing device is performing development, the following problem occurs. In other words, if another developing device is located upstream in the rotational direction of the photoreceptor drum than the developing device that is performing development, the magnetic brush of this developing device will rub against the electrostatic latent image on the photoreceptor drum. There have been problems in that the electrolatent image is disturbed and toner from the magnetic brush adheres to the photoreceptor drum, causing color mixing and deteriorating image quality.

On the other hand, if another developing device is located downstream in the direction of rotation of the photoreceptor drum than the developing device that is performing development, the magnetic brush of this developing device may disturb the toner image already developed on the photoreceptor drum. In addition, toner from the magnetic brush adheres to the photoreceptor drum, causing color mixing, which also causes deterioration in image quality.

Therefore, in a developing device equipped with a plurality of developing devices, each developing device is individually movable to an operating position close to the photoreceptor drum, and while one developing device is performing development, the other developing devices are Some devices are configured so that the developing device is separated from the photoreceptor drum. That is, as shown in FIG. 9, two developing units 6 are disposed vertically near the photosensitive drum 60.
1.62, and each developing device 61.62 is supported movably in a direction towards and away from the photosensitive drum 60. The developing device 61.62 has a spring 63.6.
Drive shafts 65 .
Eccentric cams 67, 68 fixed to 66 are respectively arranged. By rotating the drive shafts 65 and 66, the tips of the eccentric cams 67 and 68 press the rear surface of one of the developing units 61 and 62, and the developing unit 6
1 or 62 can be moved to an operating position close to the photoreceptor drum 60.

[Problems to be Solved by the Invention] However, such conventional technology has the following problems. That is, it is necessary to provide the eccentric cams 67, 68 and a mechanism for driving the eccentric cams 67, 68 on the back side of the developing units 61, 62, which increases the space behind the current devices 61, 62 and complicates the mechanism. It has the problem of becoming.

Furthermore, when the developing devices 61 and 62 move to a position close to the photoreceptor drum 60, they do not come into contact with any member on the photoreceptor drum 60 side before reaching the stop position. Therefore, when the developing devices 61 and 62 are pushed by the eccentric cams 67 and 68 and moved to the operating position close to the photoreceptor drum 60, the leading end of the developing devices 61 and 62 connects between the photoreceptor drum 60 and the developing roll. There is a problem in that when the developer collides with the setting member that sets the interval, the developer adhering to the developing roll or the like spills out due to the impact, mixes into other developing devices, causes color mixing, and stains the surrounding area.

A device as shown in FIG. 10 may also be considered as a solution to the above problems. That is, a lever 70 that can be manually operated from the outside of the copying machine is provided, and a gear 12 is provided on a shaft 71 that pivots this lever 70.
2 is meshed with a gear 74 provided on a drive shaft 73. Cams 76 and 77 that press a leaf spring 75 provided on the back surface of the developing device 61 are fixed to the drive shaft 73. The cam 77 is for pressing a developing device (not shown) disposed below the developing device 61. Also, the lever 70
As shown in FIG. 11, is provided with a protrusion 78, and near the lever 70 is a microswitch that is turned on when the lever 70 is operated and the developing unit 61 is moved to the operating position. 79 will be provided.

In this way, the developing device 61 can be moved manually, thereby simplifying the mechanism and reducing costs. In the figure, 80 indicates a bearing.

Further, as shown in FIG. 12, a dial 81 is provided in place of the lever, and the rotational driving force of this dial 81 is applied to the pulley 8.
It is also conceivable to move the developing unit 61 to the operating position by transmitting the power to the drive shaft 73 via the belt 84 and the belt 84.

However, even in these cases, the problem of the developer being scattered due to the impact when the developing device collides with a predetermined member during movement of the developing device cannot be solved.

[Means for Solving the 'rR Problem] Therefore, the present invention was made to solve the problems of the above-mentioned prior art, and its purpose is to save space and to solve the current problem. An object of the present invention is to provide a developing device capable of smoothly performing a switching operation of @ containers and capable of preventing scattering of developer and the like.

That is, the present invention provides a developing device that includes a plurality of developing devices and is capable of individually moving each developing device to an operating position close to an image carrier, in which a portion of each developing device is used as a developing member of the developing device. It is brought into pressure contact with a setting member that sets the distance from the image carrier,
At least one of the developing device or the setting member is provided with a displacement portion that is displaced in a direction in which the developing device and the image carrier move toward and away from each other, and by moving this displacement portion, the developing device is moved toward and away from the image carrier. It is configured to be movable in the direction.

The number of developing units used is, for example, two, but is not limited to this, and of course may be three or more.

For example, a photoreceptor drum is used as the image carrier, but it is not limited to this, and it goes without saying that a photoreceptor belt or the like may also be used.

Further, as the setting member, for example, a member that is provided on both sides of the image carrier and comes into contact with a part of the developing device is used.

Further, the portion of the developing device that comes into contact with the setting member may be, for example, a housing of the developing device, but preferably a rotating plate or the like rotatably provided on both sides of the developing device is used.

Further, as the displacement portion, for example, eccentric portions formed on a rotary plate or the like provided in a developing device at different distances from the center are used. Further, as this displacement part, a setting member is used which is formed into a rotatable disk shape, and an eccentric part is provided in the circumferential direction on this setting member, the distance from the center being different from that of the other parts.

[Operation] In the present invention, the developing device and the setting member are kept in contact with each other at all times, and a displacement portion provided on at least one of the developing device or the setting member is moved, so that the developing device is connected to the image carrier. It is designed to be able to approach and separate from the

[Example] The present invention will be explained below based on illustrated embodiments.

FIG. 7 shows an electrophotographic copying machine capable of forming images of a plurality of colors to which the developing device according to the present invention can be applied.

In the figure, reference numeral 1 denotes a document table glass on which an original (not shown) is placed. The document placed on the document table glass 1 is illuminated by a light source 2, and its reflected light image is formed by a mirror and a lens. The image is projected onto the photoreceptor drum 4 via the scanning optical system. The surface of the photosensitive drum 4 is uniformly charged in advance by a charger 5 before exposing the image of the original, and then the I/O of the original is charged. ifi is exposed to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 4 is developed by one of the developing devices of the developing device 6 according to the present invention. In the illustrated embodiment, the developing device 6 has two developing devices 7.8 containing developers of different colors. It can be moved to any position.

The image developed by one of the developing devices is sent out from the paper feed cassette 9 by a paper feed roll 10, onto a transfer paper 12 that is conveyed to the surface of the photoreceptor drum 4 by a registration roll 11 at a predetermined timing. Transfer is performed by charging the transfer corotron 13. Thereafter, the transferred toner image is fixed on the transfer paper 12 by the fixer 14, and the paper is discharged onto the tray 15. In the figure, 16 indicates a cleaner.

By the way, as shown in FIG. 6, the developing device 7.8 is
The developing devices 7.8 are vertically arranged at intervals, and each developing device 7.8 is exposed to light through a long hole 20.20 drilled in the frame 19 of the copying machine via a rod 17.18 protruding from the side surface. The body drum 4 is slidably attached in the direction of the arrow A to move toward and away from the body drum 4. Further, these developing devices 7 and 8 are provided on the back side of the developing devices 7 and 8.
．． A leaf spring 50 for bringing 8 into pressure contact with a setting member to be described later.
゜51 is arranged.

As shown in FIG. 4, each of the developing devices 7.8 includes a developing roll 22 rotatably provided inside the developing device main body 21;
It is rotatably provided on the back side of the developing roll 22, and a developer 23 made of toner and magnetic carrier is transferred to the developing roll 22.
The main parts thereof include a paddle 24 that supplies the developer 23 to the developer 2, and a mixer 25 that is rotatably provided on the back side of the paddle 24 and mixes the developer 23.

Further, as shown in FIGS. 1 and 5, on both sides of the photoreceptor drum 4, the photoreceptor drum 4 and a developing roll 22 of a developing device are provided.
Drum support 2 as a setting member that sets the distance between
The drum support 26 is formed into a disk shape and is fixed coaxially with the photosensitive drum 4 . The drum support 26 maintains a constant distance between the surface of the photosensitive drum 4 and the developing roll 22 of the developing device by coming into contact with a part of the developing device, which will be described later.

In this embodiment, at least one of the developing device or the setting member is provided with a displacement portion that is displaced in a direction in which the developing device and the image carrier come into contact with each other. That is, as shown in FIG. 1, eccentric cams 27.28 are provided on both sides of the developing device 7.8 coaxially with the developing roll 22. It is formed of portions 27a, 28a and portions 27b, 28b protruding toward the photosensitive drum 4 side. On the outer surface of the eccentric cam 27.28, pins 29.30 are protruded on the opposite side from the protrusions 27b, 28b. Elongated holes 34.35 drilled in .33 are engaged.

The link member 31 has arm portions 32 and 33 projecting at approximately 180 degrees from the central axis 36, and the central axis 36 of the link member 31 is connected to the motor as shown in FIG. It is connected via a link 40 to a crank 39 fixed to a drive shaft 38 of 37.

By rotating the motor 37 by a predetermined amount, the link member 31 is moved up and down via the crank 39 and the link 40. By doing this, the pin 29.30 engaged in the elongated hole 34.35 of the link member 31
Accordingly, the eccentric cam 27.28 provided in the developing device 7.8
The projections 27b of these eccentric cams 27, 28,
28b comes into contact with the drum support 26, so that the developing devices 7.8 can be individually moved toward and away from the photosensitive drum 4.

In the above configuration, in the developing device according to this embodiment,
The developing device is switched as follows. That is, since the developing device 7.8 is pressed toward the photoreceptor drum 4 by the leaf spring 50.51, the eccentric cam 27.28 provided on the developing device 7.8 comes into contact with the drum support 26. There is. At this time, as shown in FIG. When the protrusion 27b is in contact with the drum support 26, the other eccentric cam 28 is moved toward its arcuate portion 28.
a is in contact with the drum support 26. Therefore, the distance from the surface of the drum support 26 to the center of the eccentric cam 27.28 is larger in the developing device 8 where the protrusion 28b is in contact with the drum support 26, and the distance between the surface of the drum support 26 and the center of the eccentric cam 27, 28 is greater in the developing unit 8 where the protrusion 28b is in contact with the drum support 26, and the distance between the surface of the drum support 26 and the center of the eccentric cam 27. The developing device 7 is smaller. That is, the developing device 7 is located at an operating position close to the photoreceptor drum 4, whereas the developing device 8 is located at a non-operating position away from the photoreceptor drum 4.

Next, in order to switch the developing devices and move the developing device 8 to the working position and the developing device 7 to the non-working position, the motor 37 is moved to a predetermined position.
By rotating the crank 39 and the link 4 by
0 to move the link member 31 upward. And the elongated hole 3 bored in the arm part 32, 33 of the link member.
4.35, the eccentric cams 27, 28 are rotated counterclockwise and the protrusion 2 of the eccentric cam 27 is rotated as shown in FIG.
7b is brought into contact with the drum support 26, and the circular arc portion 28a of the eccentric cam 28 is brought into contact with the drum support 26.
so that it touches the By doing this, the developing device 7 is able to move the photosensitive drum 4 against the elastic force of the leaf spring 50 with the eccentric cam 27 always in contact with the drum support 26.
At the same time, the developing device 8 is moved to the non-operating position separated from the photosensitive drum 4 by the elastic force of the leaf spring 51, with its eccentric cam 28 always in contact with the drum support 26.
Move to operating position close to.

In this way, the developing device 7.8 is constantly pressed against the drum support 26 via the eccentric cam 27.28, and the eccentric cam 27.
．． 28, the developing devices 7.8 are individually moved to an operating position close to the photoreceptor drum 4, with the eccentric cams 27.28 of the developing devices 7.8 always in contact with the drum support 26. Therefore, when the developing device moves to the operating position, it does not collide with the member on the photosensitive drum 4 side, and it is possible to prevent the developer from spilling from the developing device due to the impact. Also, developing device 7.8
There is no need to install an eccentric cam or a mechanism to drive the eccentric cam on the back side of the developing unit, and the eccentric cam and the mechanism to drive it can be installed on the side of the developing unit, which has a relatively large amount of space.This saves space in the device. This enables miniaturization and miniaturization.

FIG. 8 shows another embodiment of the present invention, in which the same parts as in the previous embodiment are given the same reference numerals. In this embodiment, the displacement part is provided on the developing device side. It is configured to be provided on the setting member side, rather than on the setting member side.

That is, as shown in FIG. 8, a part of the drum support 26 as the setting member is provided with a protrusion 26a, and the tip of the protrusion 26a has a radius larger than the arcuate portion with radius R. It has an arc shape with R, and
Both sides of the circular arc portion 26b slope gently from the tip.
It follows. Further, a gear 43 is fixed to the rotating wheel 42 of the drum support 26, and this gear 43 is meshed with a drive gear 45 fixed to a motor 44. Further, a developing roll 22 is provided on both sides of the developing device 7.8.
Disc-shaped tracking rolls 46 and 47 are rotatably provided coaxially with the drum support 26, and these tracking rolls 46 and 47 come into contact with the drum support 26.

Then, by rotationally driving the drum support 26 by the motor 44 via the drive gear 45 and the gear 43, the tracking roll of one of the developing devices comes into contact with the protrusion 26a of the drum support 26, and this developing device is rotated. The other developer is moved to a non-operating position away from the photoreceptor drum 4, and the tracking roll of the other developer comes into contact with the arcuate portion 26b of the drum support 26, thereby moving this developer to an operating position close to the photoreceptor drum 4. It is designed to be moved. Even in this case, since the tracking roll of the developing device moves while always in contact with the drum support, it is possible to prevent the developer from spilling when the developing device is moved to the operating position. Also,
In this embodiment, all you have to do is rotate the drum support 26. jJR structure can also be further simplified,
-m Space saving and cost reduction can be achieved. Since the other configurations and operations are the same as those of the previous embodiment, their explanations will be omitted.

[Effects of the Invention] The present invention has the above-described structure and operation, and can save space, smoothly switch the developing device, and prevent developer from scattering. I can do it.

[Brief explanation of the drawing]

FIGS. 1 and 2 show the development method according to the present invention! 3 is a front view showing a mechanism for switching the developing device, FIG. 4 is a schematic diagram showing the developing device, and FIG. 5 is a photosensitive drum. and a plan view showing the developing device; FIG. 6 is a perspective view showing the supporting structure of the developing device;
FIG. 7 is a schematic diagram showing an electrophotographic copying machine to which the developing device according to the present invention can be applied, FIG. 8 is a schematic front view showing another embodiment of the present invention, and FIG. 9 is a diagram showing a conventional developing device. 10 is a perspective view of a main part showing a proposed example, FIG. 11 is a perspective view of a main part of the same proposal, and FIG. 12 is a perspective view of a main part of another proposal. [Explanation of symbols] 7.8... Current device 26... Drum support (setting member) 27.28...
- Eccentric cams 27b, 28b... Protrusions 50, 51... Leaf spring patent Applicant: Fuji Xerox Co., Ltd. Agent: Patent attorney: Tomohiro Nakamura (3 others) Fig. 2 28a Fig. 3 Fig. 5 Figure 6 Figure 9

Claims (1)

[Claims] In a developing device that includes a plurality of developing devices and is capable of individually moving each developing device to an operating position close to the image carrier, a portion of each of the developing devices is set to a distance between the developing member of the developing device and the image carrier. The developing device is brought into pressure contact with a setting member for setting, and at least one of the developing device or the setting member is provided with a displacement portion that is displaced in a direction in which the developing device and the image carrier come into contact with each other, and by moving this displacement portion, the developing device can be set. A developing device characterized in that it is movable in directions toward and away from an image carrier.