JP2813203B2 - Rotary developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method in which a hollow cylindrical developer container is rotated to move one of a plurality of developing rollers serving as a developer carrying member. The present invention relates to a rotary developing device that is selectively conveyed to a developing region that is a region facing a photoconductor that is an image carrier that carries a latent image.

[Related Art] In general, in various image forming apparatuses such as a copying machine and a printer, an electrostatic latent image corresponding to an image is formed on a photoconductor and a developing roller provided in a developing device is formed on a developing roller. A two-component or one-component developer is held, and the developer on the developing roller is carried into a developing region which is a region opposed to the photoconductor by a transport action of the developing roller. In the developing area, the toner in the developer is supplied to the electrostatic latent image to perform a developing operation, so that a toner-capable image is obtained.

As a developing device used in such an image forming apparatus, a rotary developing device has been conventionally known. The rotary developing device is provided with a developer container having a hollow cylindrical shape. A plurality of developer chambers for storing the developer are formed in the developer container, and a developer chamber is provided outside the developer container. A developing roller partly protruding toward the developer chamber is disposed in each of the developer chambers. When the developer container is rotated, one of the developing rollers is transported to a developing area, and the developing roller is selectively disposed at a predetermined position for development. According to such a rotary developing device, there is an advantage that a plurality of developing units can be accommodated in a small space, and the size of the image forming apparatus can be reduced.

[Problems to be Solved by the Invention] However, in such a rotary developing device, each developing roller must be arranged at a predetermined position in a developing area by rotating the entire device. It is difficult to position the developing roller at the same position, and it has been a problem to keep the distance between the developing roller and the photoconductor constant at all times.

In the apparatus described in JP-A-61-105565, after a designated developing unit is arranged to face the photoconductor side, the developing roller is pushed outward, that is, toward the photoconductor side. It has been practiced to set the distance between the photoconductor and the developing roller constant. However, in this device, the distance setting step must be executed each time the developing roller is switched, so that a smooth developing operation is difficult, and there is a problem that the mechanism of the device is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary developing device capable of reliably setting the distance between each developing roller and a photoconductor with a simple mechanism.

Means for Solving the Problems In order to achieve the above object, according to the invention described in claim 1, a developer chamber for accommodating a developer is formed in a hollow cylindrical developer container in a complicated manner. In each of the developer chambers, a developer carrier is arranged so that a part thereof projects outward of the developer container. A rotary developing device in which one of the developer carriers is selectively disposed at a predetermined position for development by a rotational movement of the developer container with respect to a developing region formed in the facing region. Is pressed against the back side of the development region corresponding portion of the image carrier, and is orthogonal to the transport direction of the image carrier so as to advance and retreat the development region corresponding portion of the image carrier toward the developer container. The battery is provided to be movable in The backup roller, the center of rotation of the developer container, the center of rotation of the developer carrier, and the center of rotation of the backup roller occupy substantially the same straight line, and the image carrier and the developer carrier And a roller positioning member provided in the developer container so as to receive the backup roller at a position where the distance from the roller is constant.

According to a second aspect of the present invention, in the rotary developing device according to the first aspect, the developer container has a first shaft mounting portion for mounting a rotation shaft of the developer container, and the developer carrying member. A second shaft mounting portion for mounting the body rotation shaft.

[Operation] When each developing roller is arranged to face the surface of the photoconductor to perform the development, the backup roller pressed against the rear side of the development area corresponding portion of the photoconductor is pressed toward the developer container. Is moved in a direction perpendicular to the transport direction of
As a result, the portion corresponding to the developing area of the photoconductor is also moved toward the developer container. Then, at a predetermined position, the backup roller is received by the roller positioning member, whereby the distance between the photoconductor and the developing roller is kept constant, and the same developing gap is maintained for each of the developing rollers. It has become so.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 3 shows a color copying machine to which the present invention is applied. In FIG. 1, an endless transfer belt 1 is stretched in a substantially horizontal direction over a drive roller 2 and a driven roller 3, and the transfer paper S sent in the direction of the arrow by the paper feed roller 4 is transferred to the transfer belt 1. The paper is conveyed on the belt 1.

The document table 5 is provided in parallel with the direction in which the transfer belt 1 is provided, and is configured to be reciprocally driven in directions indicated by arrows a and b. An original, not shown, is set on the original platen 5. A light image corresponding to the color image of the original is exposed through a focusing optical transmitter array 6 and a filter 7 as an image carrier. An image is formed and administered on the body belt 8, whereby an electrostatic latent image is formed on the photosensitive belt 8. Such an electrostatic latent image is formed for each color separation. Photoreceptor belt 8
Are stretched in such a way that they are scraped by the supporting rollers 8a, 8b, 8c which are installed in a stationary state.

On the other hand, the rotary developing device 9
The developing rollers 9A, 9B, and 9C for the respective colors provided as a developer carrier are switched and placed in a developing area which is a portion facing the photoreceptor belt 8, and each of the developing rollers The electrostatic latent images of the respective colors are developed by the toners of the respective colors supplied from 9A, 9B, 9C, so that toner visible images corresponding to the respective colors are obtained. In the photoreceptor belt 8, a developing area is formed between the support rollers 8a and 8b.

When the portion of the transfer paper S transfer section 11 carried by the transfer belt 1 is passed as described above, the first color toner visible image on the photosensitive belt 8 is transferred to the transfer charger.
The image is transferred to the transfer paper S by 12. At the time of this transfer, the transfer belt 1 is driven in the direction of arrow A, that is, in the direction opposite to the forward movement direction of the document table 5, and the document table 5 is returned after completing the forward movement. When the rear end of the transfer paper S passes through the transfer section 11, the transfer belt 1 is rotated in reverse, and the upper belt portion is moved in the direction of arrow B opposite to the direction of arrow A to prepare for the next transfer.

Next, by repeating the same transfer process, the toner visible image of the second color and the toner visible image of the third color are transferred so as to be superimposed on one sheet of transfer paper so as not to cause positional displacement. You.

After the transfer of the visible image of the final color toner, the transfer paper S passes through a space between the pair of static elimination chargers 13 and is received by a transfer paper fixing system 14 including a pair of heating and pressing rollers. It will be discharged outside.

Next, as shown in FIG. 1, the above-mentioned developing device 9 is provided with a developing container 92 comprising a cylindrical hollow frame member, the developer container 92, the rotary drive around a rotational center O ₁ It is installed to be. The internal space of the developing container 92, the rotational center O ₁ 3 single developer chamber by a partition wall that extends in a radial curved from 92A, 92B, is partitioned into a 92C, respective developers chamber 92A, Yellow (Y), magenta (M), and cyan (C) color developers are contained in 92B and 92C, respectively.

In each of the developer chambers 92A, 92B, and 92C, developing rollers 9A, 9B, and 9C are provided so as to partially protrude outside the developer container 92. Each of these developing rollers 9
A, 9B, respective distances connecting the rotation center O ₁ of the center of rotation and the developing container 92 9C are set so as to coincide with each other. Further, each of the developing rollers 9A, 9B, 9C is set at a position where the developing roller 9A can be in contact with the photoreceptor belt 8, and a developing region is formed at a portion where both of them come into contact. That is, each of the developing rollers 9A, 9B, 9C is arranged so as to be inscribed in a predetermined circle C1, and the predetermined circle C1 is
The surface of the photoreceptor belt 8 is set to intersect with the developing area. At this time, the outer peripheral portion of the hollow cylindrical developer container 92 is formed as a predetermined circle C2,
The predetermined circle C2 is set so as to be apart from the surface portion of the photoreceptor belt 8 by a certain amount in the developing area.

Furthermore, the toner supply rollers 94A, 94B, 94C are arranged so as to be in contact with the developing rollers 9A, 9B, 9C, and the toner of each color stored in the developing chambers 92A, 92B, 92C is used. The conveying action of the agitators 96A, 96B, 96C and the toner supply rollers 94A, 94B, 94C is supplied to and adhered to the developing rollers 9A, 9B, 9C. The toner attached to the surface portions of the developing rollers 9A, 9B, 9C is moved by the rotating and conveying action of the developing rollers 9A, 9B, 9C, and is pressed against the surface portions of the developing rollers 9A, 9B, 9C. The toner particles are formed in a uniform layer by the metering blades 95A, 95B, and 95C for regulating the toner layer. Further, the thin toner layer is carried into the developing area by the rotation and transport action of the developing rollers 9A, 9B, and 9C, where it is subjected to the above-described developing operation. The toner remaining on the developing rollers 9A, 9B, and 9C after the development is scraped off by toner layer peeling rollers 93A, 93B, and 93C that are pressed against the surface of the developing rollers 9A, 9B, and 9C. The rollers 9A, 9B, 9C will be initialized.

Each developer chamber 92A, 92B, 92C, 92B, 92
Yellow (Y), magenta (M), cyan (C) in C
Are sequentially consumed.However, when the amount of the stored developer falls below a certain value, the need for toner replenishment is indicated on the display unit by a toner end detection device (not shown). At the same time, the operation of the entire copying machine is stopped. An opening for supplying toner to the developer chambers 92A, 92B, 92C is formed in an outer frame portion of the developer container 92, and the opening for toner supply is opened or closed. Opening / closing lid 91A, 91B, 91C
Is attached to open and close freely. These opening / closing lids 91A, 91B,
The 91C is hinged to the outer frame portion of the developer container 92, and is mounted so as to be flipped up and opened radially outward.

In the developing device in such an embodiment, for example, the developing roller 9A of each of the developing rollers 9A, 9B, 9C is disposed so as to face the surface of the photoreceptor belt 8 as shown in FIG. Then, the outer surface of the developing roller 9A is pressed against the photosensitive belt 8 side, and the surface of the photosensitive belt 8 is displaced. At this time, a developing position is formed at the pressure contact portion between the developing roller 9A and the photoreceptor belt 8, and as a result, the developing position is the same for all of the developing rollers 9A, 9B, and 9C. ing. Also, as shown in FIG. 2, the developer container 92 is transported while the developing rollers 9A, 9B, and 9C are being conveyed to the developing area.
Is rotated away from the surface of the photoreceptor belt 8 by a predetermined distance, so that the rotation of the developer container 92 can be smoothly carried out.

In the embodiment shown in FIGS. 4, 5, and 6, a backup roller 81 is disposed on the back side of the portion corresponding to the developing area of the photoreceptor belt 8 so as to be in pressure contact with the belt.
The backup roller 81 is rotatably attached to a tip portion of an arm 83 that is swung about a support shaft 84, so that the backup roller 81 can reciprocate in a direction orthogonal to the conveying direction of the photosensitive belt 8. ing. Further, a drive mechanism (not shown) is attached to the backup roller 81, and the backup roller 81 is oscillated through the drive mechanism so that a portion corresponding to the developing region of the photoreceptor belt 8 is located on the developer container 92 side. It is designed to move forward and backward. In addition, the above backup roller 81
, A small-diameter guide roller 82 is coaxially attached.

On the other hand, a roller positioning member 98 that supports the backup roller 81 is formed on the side plate 97 of the developer container 92 so as to protrude outward by a predetermined amount in the radial direction. The roller positioning member 98 includes the developing rollers 9A, 9B,
9C is provided at a position corresponding to the installation portion, and a locking portion 99 formed by cutting out in a semicircular shape is provided at each radial end portion. This locking part 99
Is fitted to the guide roller 82 on the backup roller 81 side as shown in FIGS. 5 and 6. As described above, the engaging portion 99 on the developing device side and the guide roller 82 on the backup roller 81 are fitted to each other, so that the photosensitive belt 8 pressed and held by the backup roller 81 and the developing rollers 9A, 9B, The distance from 9C, that is, the developing gap is fixed.

In the apparatus in such an embodiment, first, for example, a developing roller 9A is arranged to face the surface of the photoreceptor belt 8 as shown in FIG. Next, the backup roller 81, which is located at a position separated from the back side of the portion corresponding to the developing area of the photosensitive belt 8, is driven to swing toward the developer container 92, and the backup roller 81 is moved to the photosensitive belt 8 side. Is pressed against the portion corresponding to the developing region, and the portion corresponding to the developing region of the photosensitive belt 8 is brought close to the developing roller 9A side. When the guide roller 82 on the backup roller 81 side is fitted to the locking portion 99 on the developing device side, the photosensitive belt 8
The distance between the developing roller 9A and the developing roller, that is, the developing gap, is set to a preset value. As a result, the same developing gap is maintained for all of the developing rollers 9A, 9B, and 9C.

As a modification of the present embodiment, a developing device in which the photoreceptor belt 8 and the developing rollers 9A, 9B, and 9C are in contact with each other can be configured.

[Effects of the Invention] As described above, in the present invention, the roller positioning member is positioned such that the rotation center of the developer container, the rotation center of the developer carrier, and the rotation center of the backup roller are substantially on the same straight line. Since the backup roller is received at a position occupying the roller roller, the backup roller does not apply a rotational torque to the developer container when the roller contacts the roller positioning member, and the roller positioning member is provided on the developer container, Since the backup roller is received at a position where the distance between the image carrier and the developer carrier is constant, the distance between the photoconductor and the developing roller is kept constant, and the same development is performed for each of the developing rollers. The backup roller, which maintains the gap and is pressed against the back side of the photoconductor corresponding to the development area, The material can be received at a predetermined position where the distance between the photoconductor and the developing roller is constant, and the distance between each developing roller and the photoconductor can be set with high accuracy with a simple configuration. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing a schematic configuration of a rotary developing device according to one embodiment of the present invention, and FIG. 2 is a cross-sectional explanatory view showing a moving state of the rotary developing device shown in FIG. FIG. 3 is a side view showing a color copying machine as an example of an image forming apparatus to which the present invention is applied, and FIG. 4 is a sectional view showing a schematic configuration of a rotary developing device in another embodiment of the present invention. 5, 5 and 6 are a partially enlarged sectional explanatory view and a partially enlarged external perspective view showing a positioning portion of the rotary developing device shown in FIG. 8 photoreceptor belt, 9 developing device, 9A, 9B, 9C developing roller, 92 developer container, 92A, 92B, 92C developer chamber, 81 backup roller, 98 Roller positioning member, 99 ... locking part.

Claims (2)

(57) [Claims] A plurality of developer chambers for accommodating a developer are formed inside a hollow cylindrical developer container, and each of the developer chambers has a part facing the outside of the developer container. The developer carrying members are arranged so that each of the developer containers protrudes, and each of the developing devices is rotated by the developer container with respect to a developing region formed in a region facing an image carrying member that carries an electrostatic latent image. A rotary developing device in which one of the developer carriers is selectively disposed at a predetermined position for development. A backup roller movably provided in a direction orthogonal to the conveying direction of the image carrier so as to advance and retreat a developing region corresponding portion of the body toward the developer container side; and a rotation center of the developer container, Rotation of the developer carrier The developer container so as to receive the backup roller at a position where the center and the rotation center of the backup roller occupy substantially the same straight line, and the distance between the image carrier and the developer carrier is constant. And a roller positioning member provided in the rotary developing device. 2. A rotary developing device according to claim 1, wherein said developer container has a first shaft mounting portion for mounting a rotary shaft of said developer container, and a second shaft mounting portion for mounting a rotary shaft of said developer carrier. And a shaft mounting portion.