JPH0443896Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement in a developing device for a multi-color copying machine in which a plurality of developing devices are made to function selectively depending on desired colors.

Conventional technology In a typical copying machine using xerography, an electrostatic latent image is formed by exposing the uniformly charged surface of a latent image carrier, and this electrostatic latent image is developed. A toner image is transferred to a transfer material such as paper and then fixed to obtain a copy. The developing device is configured using a rotating developer carrier such as a magnetic brush roll, and continuously transfers a certain amount of developer carried on the developer carrier to a development position, that is, to a developer carrier. The latent image carrier is supplied to a position facing the latent image carrier.

Recently, multi-color copying machines have also become available, which use a plurality of developing devices having developers of different colors and operate these devices selectively to obtain copies of desired colors. In this type of multicolor copying machine, in order to avoid troubles such as color mixing, a mechanism is usually adopted in which the non-functional developing device is kept far away from the surface of the latent image carrier.

Problems to be Solved by the Invention However, for multicolor copying machines that employ the mechanism described above, mechanical operations are essential for moving the developing device closer to or away from the latent image carrier. For example, due to the vibration or inertia of the developing device caused by this mechanical operation, toner accumulated within the developing device, particularly in the lower housing, may spill out of the developing device. If toner spills outside the developing device, the inside of the copying machine becomes dirty, or the spilled toner enters other developing devices installed below the developing device.
This has caused problems such as color mixing.

The present invention was created in view of these problems, and it is an object of the present invention to provide a developing device for a multicolor copying machine that is free from the risk of toner spilling when changing the developing color.

Means for Solving the Problems The above-mentioned problems of the prior art can be solved in the developing device of a multicolor copying machine in which a plurality of developing devices are selectively brought close to the latent image carrier to develop a latent image. ,
The latent image carrier side of the lower housing of the developing device is formed to be expandable and retractable, and a gap regulating member is fixed at a position spaced a predetermined distance from the surface of the latent image carrier, so that the end of the lower housing on the latent image carrier side is always aligned with the gap regulating member. This problem can be solved by inserting a biasing member between the end of the lower housing on the developing device main body side and the latent image carrier side in order to bring the member into contact with the member.

In the developing device of the present invention, the lower housing of the developing device is configured to be expandable and retractable, and the gap regulating member is fixed such that its end on the side of the latent image carrier is always spaced a predetermined distance from the latent image carrier. Since the biasing member is provided so as to come into contact with the toner, there is no fear that toner will spill from the developing device when the developing device is not functioning and is kept far away from the latent image carrier. As a result, the interior of the copying machine is prevented from becoming dirty due to spilled toner, and color mixing with other developing devices is prevented.

Embodiments Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

Referring to FIG. 1, there is shown a cross-sectional configuration of a developing portion of a copying machine to which the present invention is applied, and this state shows a state in which the developing device is functioning. Reference numeral 1 denotes a photosensitive drum on which an electrostatic latent image is formed by an exposure means (not shown), and functions as a latent image carrier. The developing device 2 mainly includes a developing device housing 3, a developing roll 4 and a developer transport system 5 housed inside the developing device housing 3. 6
A trimmer bar is fixed inside the housing 3 in the vicinity of the developing roll 4, and regulates the amount of developer carried on the developing roll 4, which rotates in the direction of the arrow in the figure. If this developing device is a two-component system,
The developing roll 4 consists of a fixed magnetic roll having a magnetic pole at a developing position, etc., and a conductive sleeve rotatably supported around the fixed magnetic roll. The developer consisting of toner and carrier supplied from the conveyance system 5 is carried on the developing roll 4, and after the amount carried per unit area is regulated by the trimmer bar 6, it is supplied to the developing position and electrostatically latent. The image is developed.

Photosensitive drum 1 of developing device lower housing 31
A buttful 32 is attached to the side via a biasing member 7, and the lower housing 31 is configured to be substantially telescopic. Reference numeral 8 denotes a gap regulating member fixed to, for example, both side bearings 9 of the photoreceptor drum 1, and protrudes from both side edges of the photoreceptor drum 1 at a predetermined distance. The buttful 32 attached to the lower housing 31 is always pressed against the gap regulating member 8 by the repulsive force of the urging member 7. 1
0 is a thin film-like member pasted on the upper surface of the buttful 32, and is made of, for example, a Mylar sheet. The thin film member 10 is not fixed to the lower housing 31, but is slidable relative to the lower housing 31 as the developing device 2 moves from side to side in the figure. Therefore, the developer contained in the developing device 2 does not leak to the outside from between the lower housing 31 and the buffer 32.

When the developing device 2 is not functioning, that is, when another developing device (not shown) is functioning, the developing device 2 is slid to the right in the figure with respect to the copying machine main body 11 by a driving means (not shown). The state shown in FIG. 2 is reached. At this time, Batsuful 32
Since the baffle 32 receives a force in the direction of the photoreceptor drum 1 by the biasing member 7, it does not separate from the gap regulating member 8, and the gap width between the baffle 32 and the photoreceptor drum 1 is always kept constant. For this reason, the developing device 2
There is no possibility that the toner accumulated on the tip of the lower housing 31, particularly on the baffle 32, leaks out of the developing device 2 from between the buffle 32 and the photoreceptor drum 1 due to vibrations caused by horizontal movement of the lower housing 31. .

In addition to the above-mentioned embodiments, the expansion/contraction mechanism of the lower housing 31 may include, for example, a bellows-shaped rubber member having a coil spring inside the lower housing 31.
It may also be configured such that it is attached to the tip of the.

Effects of the Invention As explained above, according to the present invention, the lower housing of the developing device is configured to be expandable and retractable, and the end portion thereof on the side of the latent image carrier is always fixed at a predetermined distance from the latent image carrier. Since it comes into contact with the gap regulating member, there is no risk of toner spilling from the developing device when the developing device is not functioning and is kept far away from the latent image carrier, and spilled toner will not stain the inside of the copying machine. This has the effect that color mixing with other developing devices can be prevented.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing a state in which the developing device of a multicolor copying machine to which the present invention is applied is functioning, and FIG. 2 is a cross-sectional configuration diagram showing the developing device in a non-functioning state. be. 1...Photosensitive drum, 2...Developing device, 4...
Developing roll, 7... Urging member, 8... Gap regulating member, 10... Thin film member, 32... Buzzful.

Claims (1)

[Scope of Claim for Utility Model Registration] In a multicolor copying machine in which latent images are developed by selectively bringing a plurality of developing devices close to a latent image carrier, A gap regulating member is formed to be extendable and retractable, and a gap regulating member is fixed at a position spaced a predetermined distance from the surface of the latent image carrier, and the lower housing is arranged such that the end of the lower housing on the latent image carrier side is always in contact with the gap regulating member. A developing device for a multicolor copying machine, characterized in that a biasing member is interposed between the developing device main body side and the latent image carrier side end.