JPS6355572A - Developing device for two-component developer - Google Patents

Abstract

PURPOSE:To surely exclude a color toner before switching, which remains on a developing roll, in a short period and miniaturize a developing device by providing a member, which triboelectrifies the toner, in a toner tank. CONSTITUTION:When copying is started, a toner supply roll and the developing roll start rotating at a prescribed timing, and the toner in a toner tank 6 is rubbed over a toner carrying roll 7 by a supply roll 8 and is carried in the direction of an arrow by the carrying roll 7 and is triboelectrified at the time of passing between a blade 9 and the toner carrying roll 7. The toner carried to a face facing a developing roll 3 is brought into contact with a developer 12 including a carrier magnetized and carried on the developing roll 3 and is transferred to the developer 12 by the bias voltage applied to the toner carrying roll 7 and is stuck to the developer 12 and is carried together with the developer. A latent image on a photosensitive body 2 is developed in a developing position near the photosensitive body 2, and the developer holding the remainder toner is carried to the developing roll 3 and is returned into the developing device.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a two-component developing device capable of switching developed colors.

Prior Art A monochrome copying machine has a single photoreceptor and develops a latent image formed on the photoreceptor in any one of different colors to produce a color copy in any one color; A full-color system in which a photoreceptor is exposed to color-separated light images, each of the resulting latent images is developed with toner of a complementary color to the color-separated light, and each toner image is superimposed and transferred onto a single transfer paper. In the copy machine,
Conventionally, a plurality of developing devices capable of developing in different colors are provided following the exposure section of the single photoreceptor described above, and are used for development each time one latent image is formed. Developing was performed by switching the developing device. Therefore, it is difficult to sequentially apply the liquid to the photoreceptor and arrange the developer.
This has the disadvantage that the developing device occupies a large space and the device becomes large.

In order to improve the above-mentioned drawbacks, a single developing roller that is provided opposite to the photoreceptor and has a group of fixed magnets inside, a toner tank that stores toner of different colors, and toner therein are introduced as described above. A two-component developing device has been proposed, which has a plurality of toner supply units each having a conveying roller that conveys the toner to the developing roller, and switches the developing color by switching any one of the above-mentioned color toners and supplying the toner to the developing roller. ing. As a result, only one developing roller is required for each color, and the space required for the developing device is also reduced.However, in this type of developing device, when switching the developing color, toner of the color before switching remains around the developing roller. Therefore, even if toner of the new color is immediately supplied to the developing roller, it will mix with the previous color and the copy will be useless. Therefore, it took a certain amount of time to carry out solid development until the previous color disappeared and remove it from around the developing roller by, for example, collecting it in a cleaning device.

Therefore, by exchanging the color separation filter, the light image of one original is continuously exposed to the photoreceptor as a plurality of color separation light images, which are developed with developer of each color, and the continuously rotating transfer drum and transfer belt. Such a developing device cannot be used for full-color copies that are superimposed and transferred onto the same transfer paper held in the same transfer paper. , each color toner replenishment unit is formed by dividing a cylinder with a wall extending in the radial direction, and a stirring blade is provided on the outer wall surface to form a paddle wheel.
The developing device casing was slightly larger than the cylinder containing the toner supply unit group.

Objective: The present invention provides a developed color developing device which eliminates the above-mentioned drawbacks of conventionally proposed two-component developing devices having a group of toner replenishing units that can switch and supply toners of different colors to a single developing roller. To provide a two-component developing device capable of quickly and surely removing toner of the color before switching remaining around a developing roller when switching, and capable of reducing the size of the developing device. The purpose is to

Structure In order to achieve the above object, the present invention includes a single developing roller that is provided facing a photoconductor and has a fixed magnet group inside, a toner tank that stores toner of a different color, and the above-mentioned developing roller. The toner supply unit has a plurality of toner supply units each having a toner conveyance roller that conveys the toner in the toner tank, and any one of the above-mentioned color toners is switched and supplied to the developing roller to switch the developing color. In the two-component developing device, the plurality of toner supply units described above can be integrally moved to a position where the toner conveyance roller of any unit is in contact with the developing roller, and each toner conveyance roller has a pressure contact member that frictionally charges the toner. are provided in pressure contact with each other, and each has a power source that applies a bias voltage to each toner transport roller and developing roller, and the bias voltage applied to each toner transport roller is based on the bias voltage applied to the developing roller. It is characterized by being adjustable so that the polarities are opposite to each other.

Embodiments of the present invention will be described in detail below based on the drawings.

The casing 1a of the developing device 1 is provided with an opening extending in the width direction at a position close to the photoreceptor drum 2, and a portion of the developing roller 3 having a fixed magnet group inside is exposed through the opening. The photoreceptor drum 2 is provided so as to be close to the photoreceptor drum 2.

A drum-shaped toner tank revolver 4 is provided on the side of the developing roller 3 opposite to the photoreceptor 2 so as to be rotatable about its axis with a slight gap in the developing device casing 1a. The toner tank revolver 4 is divided into three spaces 6 by three walls 5 extending generally radially from its axis.
It is divided into. The space 6 is a toner tank, and each toner tank 6 contains toner of a different color.
For example, in the case of a full-color copying machine, toners of mutually complementary colors such as eggplant yellow, magenta, and cyan are stored, and in the case of a single-color copying machine, toners of colors such as black, blue, and red are stored. Each toner tank 6 has an opening extending widthwise in the outer circumferential wall of each toner tank 6, and a part of the toner conveying roller 7 provided inside can approach the developing roller 6 through this opening. Examples of the material of the toner transport roller include rubber such as nitrile and silicone, resin such as Teflon, and metal.

A supply roller 8 formed as a sponge roller is provided in the toner tank 6 in contact with the toner transport roller 7 . Further, in the toner tank 6, a blade 9 is provided which presses against the conveyance roller 7 on the downstream side of the supply roller 8 in the rotational direction of the toner conveyance roller 7 shown by the arrow. Examples of the material include metals such as carbon steel, rubbers such as urethane, and elastic materials such as resins such as Teflon. Developing roller 6
, each toner transport roller 7 has a bias voltage applying i.
! a toner transport roller 7;
The voltage of the bias voltage applying power source 11 is variable so that the polarity can be reversed based on the bias voltage of the developing roller 6.

Since this device is configured as described above, when developing with a certain color, the toner of that color can be selected by button on the operation panel of the copying machine, or by program control in the case of a full-color copying machine. The toner tank revolver 4 is rotated by a motor (not shown) or the like so that the toner transport roller 7 of the stored toner tank comes into contact with the developing roller 6, and is positioned and fixed at that position.

The toner replenishing roller and the developing roller start rotating at a predetermined timing with the start of copying, and the toner in the toner cartridge is rubbed against the toner transport roller 7 by the supply roller 8, and is transported by the transport roller 7 in the direction of the arrow. When passing between the blade 9 and the toner transport roller 7, the toner is frictionally charged. The toner conveyed to the surface facing the developing roller 3 comes into contact with the developer 12 having a carrier magnetized and conveyed on the developing roller 3, and is developed by the bias voltage applied to the toner conveying roller 7. agent 12
The developer that transfers to the developer 12 and is conveyed together with the developer develops the latent image on the photoconductor 2 at a development position close to the photoconductor 2, and the developer that retains the remaining toner is transferred to the developing roller. 3 and returned to the developing device.

Now, in the next process, when a different color is selected, the bias voltage applied to the toner transport roller 7 by the power supply 11 will be reversed with respect to the bias voltage applied to the developing roller 3 at the time of switching, as shown in FIG. The toner in the developer that is magnetized and transported onto the image roller 3 is quickly and reliably transferred toward the toner transport roller 7 due to the relationship of the polarity of the bias voltage, and is transported by the toner transport roller 7. , scraped off by the blade 9 and collected into the toner tank 6. Therefore, the developer magnetized on the surface of the developing roller 3 is only the carrier. Next, the toner tank revolver 4 is rotated so that the toner conveying roller 7 of the toner tank 6 of the selected color comes to a position facing the developing roller 3, and is fixed at that position. Next, when the copy button is pressed or at a predetermined timing according to the program, the toner of the selected color is developed in the supplied color onto the carrier on the developing roller 3 by the above-described operation.

FIG. 3' is a diagram showing an embodiment in which the present invention is installed in a monochromatic copying machine capable of changing colors.

Each toner tank 6 in the toner tank resolver 4 of the developing device 1 according to the present invention contains toner of any color such as blue, sepia, red, green, etc., in addition to black toner, which is usually used most frequently. The operator selects the color using the color selection button on the operation/display section, and the toner selected as described above becomes ready to be supplied to the developing roller 3.

When the copy button is pressed, the document placed on the touch glass 2o is exposed to light on the photoreceptor drum 2 by the aperture system 21, and a latent image is formed in the same process as in a normal monochrome copying machine. The toner image is formed and developed with toner of a selected color by the developing device 1 to become a toner image.

This toner image is transferred to a transfer paper 23 by a transfer charger 22 and fixed by a fixing device 24, thereby obtaining a monochrome copy of a desired color.

An embodiment installed in a full-color copying machine using a registration transfer method is shown.

Blue, blue, etc. can be selectively inserted into the optical path of the exposure optical system 61.
Green and red color separation filters 32 are provided. Following the exposure position of the photosensitive drum 2, a developing bag according to the present invention @
1 is provided, and each toner tank in the toner tank revolver 4 stores toner of each color of yellow, magenta, and cyan, which are complementary colors of each color of the color separation filter.

The color original placed on the contact glass 30 is exposed three times in succession through each color separation filter 52, and three types of latent images are sequentially formed on the photoreceptor drum 2. Each latent image is developed by a developing device 1 using toner of a complementary color to the color-separated light. At this time, the development color of the developing device 1 is switched by program control, and the development color is reliably switched until the development of one latent image is completed and the next latent image comes to the development position. 3 formed by yellow, magenta, and cyan color toners
The seed toner images are superimposed and transferred onto a sheet of transfer paper wrapped around a transfer drum 33 that contacts the photoreceptor drum 2 at the transfer position and rotates at the same circumferential speed, and is fixed by a fixing device 35 to form a full-color image. You can get a copy.

Effects In the developing device of the present invention, when changing colors, the toner remaining in the developer around the developing roller is quickly and reliably collected into the toner tank.
It can be used with full-color copying machines that require continuous development with toner of different colors, and the size of the developing device is small because a member that frictionally charges the toner is installed in the toner tank. This makes it possible to reduce the space occupied by the developing device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device according to an embodiment of the present invention, FIG. 2 is a timing diagram of the bias voltage of the toner conveying roller and developing roller when changing colors in the developing device, and FIGS. 3 and 4 are 1 is a sectional view showing a schematic configuration of an example of a monochrome copying machine and a full-color copying machine each equipped with a developing device of the present invention. 1...Developing device 1a...Developing device casing 2...Photoreceptor 3...Developing roller 4
... Toner tank revolver 6, ... Toner tank 7 ... Toner transport roller 9 ... Blade 10.11 ... Bias power supply 12 ... Processing agent

Claims (1)

[Claims] A single developing roller that is disposed opposite to the photoreceptor and has a fixed magnet group inside, a toner tank that stores toner of a different color, and a toner conveyor that conveys the toner in the toner tank to the developing roller. a plurality of toner supply units each having a roller, and any one of the above-mentioned color toners.
In a two-component developing device in which the toner is supplied to the developing roller by switching, and the developing color is switched, the plurality of toner supply units described above are integrally displaced to a position where the toner transport roller of any unit is opposed to the developing roller. A pressure contact member for frictionally charging the toner is provided in pressure contact with each toner transport roller, and a power source is provided for applying a bias voltage to each of the toner transport rollers and the developing roller, respectively,
A two-component developing device characterized in that bias voltages applied to each toner transport roller can be adjusted to have opposite polarities based on a bias voltage applied to a developing roller.