JPS61137171A - Multi-color developing device - Google Patents

Abstract

PURPOSE:To prevent the contact of a toner in a toner storage space with a developer and to simplify a displacement mechanism by rotating integrally each of multi-color developing units around a common revolving shaft while the units are fixed to each other. CONSTITUTION:A multi-color developing device 2 for two colors is constituted as a space isolated to two compartments by a cylindrical casing 10 of the developing device and a plane partition wall 11 running the axial center thereof. The central shaft 12 of the cylinder is used as the center of rotation. A developing roll 3 in the upper part of the developing unit provided in the left side is exposed in an opened part 10a of the casting 10 and is brought into contact with a developing position 1a of a luminous body 1. The space A between the right side of such roll 3 and the partition wall 11 is used as a developer reservoir where the two-component developer 4 is stored. The space A and the storage space B for the replenishment toner are segmented by a guide part 7 provided below the roll 3 to prevent the contact of the toner in the space B with the developer 4. The copy having good quality is thus obtd. with the simple displacement mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a developing unit in which a plurality of developing units using developer for two generations are provided around a common rotating shaft, and a developer of an arbitrary color is selectively incorporated. The present invention relates to a multicolor developing device in which a color is brought to a developing position.

Conventional technology Conventionally, in a multicolor copying machine, a plurality of developing units containing developers of different colors are arranged around a single photoreceptor, and different electrostatic latent images are obtained by multiple exposure scans. It was common practice to create multicolor copies by developing each toner image using a developing device of a different color, and then transferring the resulting toner images onto the same transfer paper in a superimposed manner. However, developing devices that use a two-component developer consisting of non-magnetic toner and magnetic carrier are equipped with a toner storage tank to replenish the toner that decreases as development is repeated, and multiple developing devices can be exposed to light. Placing them around the body was often difficult in terms of space.

In addition, recently, copying machines have been introduced which have a removable developing device and can be attached with a built-in developing device containing a developer of a desired color, thereby making it possible to make copies in any color. In this case as well, it takes some effort to replace the developing device.

In order to solve the above-mentioned drawbacks of conventional developing devices for multi-color copying machines and copying machines that can select copy colors, multiple developing units containing two-component developers of different colors are connected to a common developer. A multi-color developing device is proposed, which is mounted so as to be rotatable at the same time around a rotating shaft, so that the developing unit of any color and the developing roll can be brought to a developing position where they contact the same developing unit around the photoreceptor. has been done. However, in conventionally proposed devices, in order to prevent toner from being excessively replenished and causing background stains and toner scattering, the developing roll is kept in a certain position with the developing roll facing up, and the common rotation is continued. It is configured to rotate while revolving around an axis. As a result, the displacement mechanism becomes complicated, leading to increased costs, and the space utilization rate is, for example, 50% due to the need to secure the space necessary to maintain the position and rotate.
%, resulting in a disadvantage that the size of the copying apparatus becomes large.

Objective: The present invention has a simple structure that eliminates the above-mentioned drawbacks of a conventional multicolor developing device in which a plurality of developing units using two-component developers are rotatably provided around a common rotation axis. It is an object of the present invention to provide a small and inexpensive multicolor developing device that can prevent excess toner from being replenished into a developer.

Structure In order to achieve the above-mentioned object, the present invention provides a multicolor developing device in which each developing unit is integrally rotatably supported around a common rotating shaft while being fixed to each other. At the development position, where the magnetic roll as the developer roll contacts a certain development area of the circumference of the photoreceptor, the free surface of the toner in the replenishment toner storage space is located between this space and the development space containing the developer roll and the developer reservoir. It is characterized by being configured to be located below the opening.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail based on drawings showing embodiments thereof.

FIG. 1 shows an embodiment in which there are two developing units.

In the multicolor developing device 2 of this embodiment, two isolated spaces are formed by a cylindrical casing IO and a planar partition wall 11 passing through its axis, each of which serves as a space for each developing unit, and the center of the cylinder The shaft 12 is the center of rotation. In the state shown in FIG. 1, the developing unit on the left side of the figure is in the developing position, and the developing roll 3 provided on the upper part of the casing 10 is exposed at a section 10a and passes through a predetermined storm image gap as indicated by the arrow in the figure. The space A between the right side of the developing roll 3 and the partition wall 11, which is in contact with the developing area 1a of the photosensitive drum 1 rotating in the direction of , is a developer reservoir, and the two-component developer 4 is not stored. ing. Developing roll 3-
It has a magnet inside and is wrapped outside with a non-magnetic sleeve.
This is a known structure in which the developer adsorbed on the surface of the sleeve is conveyed to the development site by rotating one or both of the magnet and the sleeve.

The opening of the casing 10 from the top of the developer A is part 1.
A doctor part 6 is formed in the casing 10 between the doctor part 0a and the tip thereof is in contact with the developing roll 3 with a predetermined layer thickness regulating gap therebetween. A guide section 7 is provided along the downstream side from the developing section 1a of the developing roll 3 at a predetermined gap, and is connected to the developing space including the developing roll 3 and the developer reservoir A for replenishment. In FIG. 1, the developing unit ' on the right side of the partition wall 11 is constructed axially symmetrically with respect to the rotation center 12 with the developing unit on the left side. Therefore, if it is rotated by 180 degrees around the axis 12, the arrangement will be exactly the same as the developing unit currently on the left side, and the developing sleeve 3 will be in contact with the photosensitive drum 1 at the same developing area 1a with the same developing gap maintained. .

As the sleeve rotates in the direction indicated by the arrow in the figure, the developer 4 attracted to the magnetic roll 3 passes through the doctor part 6 by the developer dimension A, and the layer thickness is regulated and the developer is deposited in the developing section 1a. It comes into contact with the photosensitive drum 1, toner is attracted to the electrostatic latent image, and development is performed. After the development is completed, the developer passes through the gap between the guide portion 7 and the developing roll 3 and returns to the developer reservoir A. It's 1.
The developer that has not passed through the gap in the doctor part 6 flows back along the casing 10 and joins with the developer that has returned after development.

The guide portion 7 prevents the developer from scattering from the sleeve and prevents the toner and the toner 5 in the storage space B from unnecessarily contacting each other at the developing position.

In other words, if the developing device 2 is arranged so that the center of the multicolor developing device 2 is higher than the center of the photoreceptor drum as shown in FIG. The free surface of 5 approaches the developer roller 3 on the opposite side of the gap @ 11, and if there were no guide section 7, it would cross the developer roller 3 and be mixed with the returning developer, but the guide Because of the portion 7, the free surface of the toner 5 in the toner storage space B is located below the opening 13, preventing contact between the stored toner 8 and the developer 4, and increasing the degree of freedom in the arrangement of the developing device. The amount of developer in the developer reservoir A that falls into the toner from the opening 13 due to the attraction force of the magnetic roll 3 does not matter.

The developing unit that is not in the developing position (the right side in Figure 1, the second
In the unit on the upper right side of the figure), the toner 5 in the toner storage space B passes through the opening 13 and comes into contact with the developer 4 in the developer pool A, but the developing roll 3 is stationary. Therefore, the toner 5 is only quietly deposited on the developer 4, and the toner 5 is not taken into the developer.

When the developing unit rotates and comes to the developing position, some of the toner remains attached to the surface of the developer, and due to the movement of the developer due to the rotation of the developing roller, the toner attached to the surface of the developer is removed from the developer. The toner is taken inside and replenished in appropriate amounts.

Effects As described above, according to the present invention, in the developing state, the toner in the toner storage space does not come into contact with the developer, so excess toner is taken into the developer, causing background stains, toner scattering, etc. prevention and improve copy quality.

Further, in the configuration of the present invention, since the developing units do not need to rotate and rotate while maintaining a fixed relationship with each other, the displacement mechanism is simplified and the space required is small, contributing to cost reduction.

In the above embodiment, the case where there are two developing units is shown, but the present invention can also be applied to the case where there are three developing units.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing the same embodiment in a state where the relative position of the developing device with respect to the photosensitive drum is changed. I... Photoreceptor, 2... Multicolor developing device, 3... Magnetic roll (developing roll), 4... Two-component developer, 5... Toner, 7... Guide portion (toner and developer contact prevention means), 10...developing device casing,

Claims (1)

[Claims] A developing space containing a magnetic roll and a two-component developer carried by the magnetic roll to a photoreceptor in contact with the magnetic roll for development, and a replenishment toner storage space connected to the developing space through an opening. A plurality of sets of developing units are rotatably held together around a common rotation axis, and each developing unit has a built-in developer of a different color.
In a multi-color developing device that rotates around the rotation axis so that one developing unit is selectively brought to a developing position where the magnetic roll contacts the same developing area around the photoreceptor, each of the developing units described above is The development units are integrally rotatably supported around the rotation axis while being fixed to each other, and each development unit is in the development position such that the free surface of the toner in the replenishment toner storage space is between the space and the development space. A multicolor developing device characterized in that it is configured to be located below the opening of the device.