JPH0636108B2 - Color image forming apparatus - Google Patents

Description

The present invention relates to a color image forming apparatus in which a developing device for a plurality of colors is sequentially moved to develop a latent image formed at the time of carrying an image on a photoreceptor or an insulator. It is about.

[Description of conventional technology]

When the developing devices of a plurality of colors are divided and positioned on the circumference around the rotation axis, and the electrostatic latent image on the photosensitive drum is contact-developed with a required color by, for example, magnetic brush development, the rotary developing device This type of color image forming apparatus, in which a developing device is selected by revolving, is compared with a conventional developing device of each color arranged side by side on the circumference of the photoconductor, and the size of the photosensitive drum and the size of the device itself are reduced. Miniaturization and price reduction can be achieved.

As disclosed in JP-A-58-189669 as a device of this type, when the developing sleeve or the like is constantly rotated even at a position other than the developing position, the deterioration of the developer tends to be accelerated, and the developer is detached from the sleeve. This causes contamination inside the machine, which causes a shortage of developer in the developing device.

[Problems to be solved by the invention]

In the full-color image forming apparatus to which the rotary developing device using the magnetic brush developing method of this kind is applied, not only the full-color image but also the single-color copying function is required, and the following problems occur.

That is, when making a single-color copy, since the developing device having the required color is selected at the developing position by the revolution of the rotary developing device, the developing device having another color that does not contribute to the development can be used before contact with the photosensitive drum. A bristling amount that depends on a fixed magnet provided inside the developing sleeve is formed on the developing sleeve. By the revolution of the rotary developing device, it reaches the developing position and is compressed there without operating. After that, the spikes that are compressed when they are separated therefrom are gradually moved in the direction opposite to the revolving direction of the rotary developing device, and the spikes are disturbed.

When this operation is repeated multiple times, the spikes on the developing sleeve are extremely biased in one direction, and the developer that cannot be restrained by the magnetic field falls due to the revolution of the rotary developing device and scatters inside the machine. Will be done.

Referring to FIG. 4, the irregularity of the spikes during non-developing described above is regulated by the doctor blade 50 on the non-magnetic developing sleeve 48 of the developing device 171 located at the position P ₁ in the rotary developing device 17. The developer 47 forms an amount of spikes commensurate with the strength of the N ₁ pole in the fixed magnet 49. By the revolution of the rotary developing device 17 as indicated by the arrow, the developing device 171 reaches the developing position P _2, and the spikes of the developer 47 are pressed against the photoconductor 14 and then pass through without being stopped. The bristles of the compressed developer 47 are moved in the direction opposite to the revolving direction when the developer 47 is separated from the developing position P ₂ , and
It becomes a disturbed shape as shown by ₃ .

After that, when the revolution revolves from the position of P ₃ and passes through the apex of the rotary developing device, the spike 47 is disturbed and the developer 47 becomes high.
Cannot fall under the restraint of the magnet and falls under its own weight.

The present invention aims to solve the above problems.

[Means for solving problems]

According to the present invention which solves the above-mentioned problems, a container for storing a developer, a developer transporting member for transporting the developer out of the container and applying the developer to an image bearing member, and an inside of the developer transporting member are arranged. A plurality of developing devices, each having a magnet and a gear train for transmitting the driving force to rotate the developer transport member, are provided on the movable support means that is rotationally moved along a predetermined circumferential path, and selected. A developing device having a color developer is moved to one developing position common to each developing device, and the developer carrying member is rotated at the developing position via the gear train to form on the developer carrying member. In a color image forming apparatus that develops an electrostatic latent image formed on an image bearing member by bringing a magnetic brush of developer into contact with the image bearing member, the gear train of the developing unit separated from the developing position is engaged. Has a fixed sector gear to fit , With the movement of the developing device is a color image forming apparatus characterized by rotating a predetermined time a developer conveying member to drive the gear train in the sector gear.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of a color image forming apparatus to which the rotary developing device according to the present invention is applied. In the operation, the photoconductor 14 supported by the shaft 13 starts to rotate in the direction of the arrow by the copy command, and the primary charger 15 uniformly charges the surface. Next, the reflected light image obtained by irradiating the original 3 on the original table 2 with the light source lamp 4 has the movable mirror 5, the movable mirrors 6 and 7 so that the optical path length between the original 3 and the lens 8 becomes constant. After passing through the movable type exposure optical system including the lens 8 and the fixed mirror 9, color separation is performed by the color separation filter 10 and the photosensitive member 14 is exposed by the exposure unit 12 through the dust-proof glass 11.

When a blue filter is selected as the color separation filter 10, an electrostatic latent image of a yellow image is formed on the photoconductor 14, and the electrostatic latent image of the yellow image is developed by the yellow developing device 171 to be visualized as a yellow image. After developing the yellow image, the rotary developing device 17 rotates in the direction of the arrow to move the magenta developing device 172 to the developing position, and an electrostatic latent image of the magenta image is formed on the photoconductor 14 by the next green filter. By developing with the magenta developing device 172, it is visualized as a magenta image. The cyan image is also visualized by a red filter.

Further, the transfer material 31 stored in the cassette 30 is fed out by the rotation of the pick-up roller 32 in the direction of the arrow, and is conveyed to the grip position 38 of the transfer drum 18 through the conveyance guides 33, 34, 35 and the conveyance rollers 36, 37. To be done. The gripper 21 of the transfer drum 18, which rotates as indicated by the arrow, is opened by the gripper cam 22 at the grip position 38 and grips the tip of the transfer material 31. The transfer material 31 is the adsorption charger 2.
3. The pressing roller 24 makes close contact with the transfer drum 18.

By rotating the photoconductor 14 and the transfer drum 18 synchronously, the tip of the yellow image on the photoconductor 14 and the transfer drum 18
The tip of the upper transfer material 31 coincides with and abuts, and the yellow image is transferred to the transfer material 31 by the transfer corona 25. After that, the desired color image is transferred a required number of times in this manner.

After the required number of transfer is completed, the transfer material 31 becomes the gripper cam 2
6 is separated from the transfer drum 18 by the separation claw 27 by the opening of the gripper 21. At that time, separation charger 2
8 prevents the toner image from being disturbed. Conveyor belt 3
9. The toner image on the transfer material 31 that is conveyed to the fixing roller pair 41 and 42 that passes through the conveyance guide 40 and rotates as shown by the arrow is fixed to the transfer material 31 by applying pressure and heat. It becomes a permanently stored image and is discharged to the tray 43.

After the transfer is completed for each color, the residual potential after the transfer is removed by the charging device 19 from the photoconductor 14, and the residual toner is cleaned by the cleaning device 20 including an elastic blade. The charges remaining on the transfer drum 18 are discharged by the discharging corona discharger 29.

FIG. 3 shows a sectional view of the developing device. As shown in the figure, the inside of the developing device 171 is divided into two chambers by a partition plate 44, and the transport screen 4 rotates through each chamber as shown by an arrow.
5. The developer 47 is reciprocally circulated by the transport screen 46. On the other hand, by the rotation of the developing sleeve 48 as indicated by the arrow, the developer 47 pumped up by the S ₃ pole in the fixed magnet 49 contained in the developing sleeve 48 is regulated by the doctor blade 50 in the amount of conveyance and N ₁ which is the pole
The latent image on the photoconductor 14 is developed by raising the ears at the poles.

After that, the developer 47 is transported from the N ₁ pole to the S ₁ , N ₂ , and S ₂ poles, peeled off from the developing sleeve 48 by the repulsive magnetic field of the S ₂ and S ₃ poles, and falls onto the transport screen 45.

Reference numeral 51 denotes a developing bias power source, and a developing bias supply electrode (not shown) applies a developing bias suitable for the developer to the developing sleeve 48 during development. In addition, the replenishment toner 53 stored in the toner hopper 52.
However, in response to a detection signal from a developer concentration detecting means (not shown), the toner is replenished from the toner replenishing port 54 in an amount commensurate with the toner consumed in the development.

FIG. 1 is an explanatory diagram of the operation according to the present invention.

In the drawing, 55 is an external gear (fixed as a sector gear) fixedly installed in the rotary developing device of the present invention, 56
Is a drive gear for the transport screen 46, 57 is a drive gear for the transport screen 45, 58 is a drive gear for the developing sleeve 48, 59 is a relay gear between 56 and 57, and 60 is a gear 57, 5.
8 relay gears, each of which rotates as indicated by an arrow when driven.

First, the operation during development will be described.

By the revolution of the rotary developing device 17 as indicated by the arrow, the developing device 171
Reaches the developing position shown. Here, the drive gear 56 of the transport screen 46 is rotationally driven by the unillustrated first drive means as indicated by the arrow, and the drive is transmitted in the order of gear 59 → gear 57 → gear 60 → gear 58, and the developing sleeve 48 rotates. Then, the electrostatic latent image on the photoconductor 14 is developed.

After completion of the development, the developing device 171 is driven by the second driving means, which is the external gear 55 immediately after the developing device 171 is separated from the developing position.
The first driving gear 56 is driven via the revolving speed of the rotary developing device, and rotates the developing sleeve in the same manner as during development.

In this way, the developing device 171 that has passed the external gear 55 having the entire length required to rotate the developing sleeve 48 by at least a half rotation or more by the revolution of the rotary developing device has a newly-arranged spike on the developing sleeve 48. It is formed and is ready for the next development.

Next, a description will be given of the case of dry development.

After reaching the developing position, the developing device 171 comes into contact with the photosensitive drum 14, then leaves the developing position and enters the external gear 55 by the revolution of the rotary developing device. To form a new organized spike.

In the above-mentioned embodiment, the developer using the non-magnetic toner and the iron powder carrier is exemplified, but it is also effective for other color magnetic toners. Further, the developer carrying means may be a magnet roller instead of the sleeve.

〔The invention's effect〕

The following effects can be obtained by providing the second drive means formed of the external gear or the like as described above.

1) By collecting the disturbed spikes in the developing device, it is possible to prevent the deviation of the developer generated on the sleeve in advance, and to prevent the developer from falling and scattering from the sleeve.

2) It is possible to form a regular spike on the sleeve.

3) Carriers on the sleeve that have consumed toner that contributed to development can be quickly collected in the developing unit by rotating the sleeve half a turn or more.

4) The mechanism for rotating the sleeve is simple as described above.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of the present invention, FIG. 2 is a sectional view of a color image forming apparatus to which a rotary developing device according to the present invention is applied, FIG. 3 is a sectional view of a developing device, and FIG. It is explanatory drawing of disorder. In the figure, reference numeral 45 is a transport screen, 46 is a transport screen, 48 is a developing sleeve, 55 is an external gear, 56 is a drive gear of the transport screen 46, and 57 is a transport screen 4.
5 is a drive gear, 58 is a drive gear for the developing sleeve 48, 5
Reference numerals 9 and 60 are relay gears.

Claims (1)

[Claims] 1. A container for accommodating a developer, a developer carrying member for carrying the developer out of the container and applying the developer to an image carrier, and a magnet arranged inside the developer carrying member. A plurality of developing devices, each having a gear train for transmitting the driving force to rotate the developer transporting member, are provided on the movable supporting means that rotationally moves along a predetermined circumferential path, and the developer of the selected color is applied. The developing device included therein is moved to one developing position common to each developing device, and at this developing position, the developer carrying member is rotated through the gear train, whereby the magnetic force of the developer formed on the developer carrying member is increased. In a color image forming apparatus that develops an electrostatic latent image formed on an image bearing member by bringing a brush into contact with the image bearing member, the gear train of a developing device separated from the developing position is engaged and fixed. Has a sector gear and moves the developing device With a color image forming apparatus characterized by rotating a predetermined time a developer conveying member to drive the gear train in the sector gear.