JPH08305119A - Rotary developing device - Google Patents

Abstract

PURPOSE: To carry sufficiently charged toner to a developing part and to use it for developing, even if the posture of each developing unit is rotated and a developer in a developing container for the developing units is excessively moved, in accordance with the rotational operations in the peripheral direction of plural developing units arrayed in the peripheral direction of a rotary developing device. CONSTITUTION: A small-diameter driving gear 10 is installed in a position nearer to the outside of the locus in the peripheral direction of the rotation of the developing units 61-64 of the rotary developing device 60, for instance, the position of 3/4 rotation from a developing position. This gear 10 is engaged with a gear not shown by the figure, provided in the developing sleeve 12 of the developing unit 64 located in the gear 10, to rotationally drive the developing sleeve 12. The developer which is scattered from the developing sleeve 12 in the developing container and then, returned to the vicinity of the sleeve 12, by the rotation of the posture of the developing unit excessively fetches the toner by an excessive movement, to include a large amount of toner insufficient in electrification. However, the excessive toner is discharged from the developer by the rotation of the sleeve 12 and moreover, the residual toner is stirred and charged by friction in a sufficient time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary developing device used in a multicolor image forming apparatus utilizing an electrophotographic system or the like.

[0002]

2. Description of the Related Art A multicolor image forming apparatus using an electrophotographic process, such as a multicolor copying machine or a laser beam printer, has conventionally been constructed as shown in FIG.

The multicolor image forming apparatus has a photosensitive drum 1 which rotates in the direction of arrow R1, and the photosensitive drum 1 is charged to a predetermined potential by a charging device 2. Next, the exposure device 3, that is, an image forming exposure optical system based on color separation of a color original image, or a scanning exposure optical system using a laser scanner that outputs a laser beam modulated in accordance with a time series electric digital pixel signal of image information By receiving the optical image information, the electrostatic latent image corresponding to the first color component image of the target color image, for example, the magenta component image is formed.

Then, as the photosensitive drum 1 rotates, the electrostatic latent image is developed so as to face the magenta color developing device 41 which is the first developing device of the rotary developing device 4, and is visualized as a magenta toner image. The rotary developing device 40 has a magenta color developing device 41, a cyan color developing device 42, a yellow color developing device 43 and a black color developing device 44 as the first, second, third and fourth developing devices. Developing devices 41 to 4
4 are arranged at equal intervals in the circumferential direction. Photosensitive drum 1
The magenta toner image formed above is electrostatically transferred to the recording paper 6 that is electrostatically supported on the surface of the transfer drum 5, and the toner remaining on the photosensitive drum 1 by this transfer is cleaned by the cleaning device 7. To be done.

Similarly, the latent image formation, development, and transfer processes are sequentially repeated for cyan, yellow, and black, so that the recording paper 6 on the transfer drum 5 is magenta, cyan, yellow, and black.
The color toner images are superimposed and transferred, and a composite color toner image corresponding to the target color image is formed.

The recording paper 6 on which the superposed transfer of the four color toner images has been completed is separated from the transfer drum 5 and conveyed to the fixing device 8, where a fixing roller 81 and a pressure roller 82 are heated and adjusted to a predetermined temperature. Is heated and pressurized by the process, mixed with the toner images of four colors and fixedly fixed on the recording paper 6, and finally output as a full-color image outside the image forming apparatus.

Each of the developing devices 41 to 41 of the rotary developing device 40.
For 44, a two-component developing device or a non-magnetic one-component developing device is used. The two-component developing device uses a developer in which a magnetic carrier such as iron oxide powder and a non-magnetic colored toner are mixed, and a developer container (hopper) containing the developer carries the developer on a developing sleeve to face the photosensitive drum 1. Then, the magnetic brush of the developer is formed in the developing section, and the latent image on the photosensitive drum is developed. The non-magnetic one-component developing device uses a developer consisting of only non-magnetic toner, applies the developer from a developing container to a developing sleeve, conveys it to a developing section, and develops a latent image.

The rotary developing device 40 is driven to rotate in the direction of arrow R2 to rotate and transfer the developing devices 41 to 44 arranged in the circumferential direction to form an electrostatic latent image on the photosensitive drum 1. The developing device of the color corresponding to is conveyed to the developing position facing the photosensitive drum 1 and stopped. The developing unit located at the developing position develops the electrostatic latent image on the photosensitive drum by rotating the developing sleeve while keeping the developing sleeve facing the photosensitive drum.

[0009]

By the way, in the above-described conventional rotary developing device 40, when the developing device rotates in the circumferential direction of the developing device, the attitude of the developing device changes with respect to the gravity direction. When the attitude of the developing device is rotated in the order of upward → overturn → downward → normal attitude, the developer or toner excessively moves in the developing container, and the insufficiently charged toner is supplied to the developing sleeve. For this reason, the density of the developed image may be non-uniform, fogging, or toner may be scattered into the developing device 4.

Therefore, in order to prevent this, like the ferris wheel in which the gondola is arranged in the circumferential direction, the rotation developing device 40 does not change the posture of each of the developing devices 41 to 44 with respect to the gravity direction even when rotated. In such a case, in that case, a rotation support shaft structure for supporting each developing device in the direction of gravity in a constant manner, and attaching / detaching to position and release the developing device with respect to the photosensitive drum at the developing position. Since a mechanism or the like is required, there is a disadvantage that the device configuration becomes complicated and the size becomes large.

SUMMARY OF THE INVENTION It is an object of the present invention to develop a developer even if the developer in the developer container moves excessively due to the rotation of the attitude of each of the developers in accordance with the circumferential rotation of a plurality of the developers arranged in the circumferential direction. It is an object of the present invention to provide a rotary developing device capable of carrying a sufficiently charged toner on an agent carrier, carrying the toner to a developing unit facing the image carrier, and using the developer for development.

[0012]

The above object can be achieved by the rotary developing device according to the present invention. In summary, according to the present invention, a plurality of developing devices arranged in the circumferential direction are carried and rotated in the circumferential direction, and the developing device stops the circumferential rotation at the developing position facing the image carrier and moves to the developing position. A rotary developing device for developing an electrostatic latent image formed on an image bearing member by a positioned developing device, comprising means for rotating a developer bearing member of the developing device at a position other than the developing position. Is a rotary developing device.

According to the present invention, the rotating means is provided at a position on the outer side of the circumferential orbit of the rotation of the developing device, and a gear provided on the developer carrier of the developing device and a position on the outer side. Inside of the circumferential orbit of the rotation of the developing device and all the gears provided on the developer carrying members of a plurality of developing devices, which are used as driving gears that are engaged with each other or are installed coaxially with the rotation center of the developing device rotation. It is a drive gear that is engaged and driven at a position closer to it. Further, the developing device is a two-component developing device using a two-component developing agent in which a magnetic carrier and a non-magnetic toner are mixed, or a one-component developing device using a non-magnetic one-component developing agent containing only non-magnetic toner. It

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a rotary developing device according to an embodiment of the present invention together with a photosensitive drum and the like. In Figure 1,
Although the charging device 2 and the exposure device 3 are shown around the photosensitive drum 1 in which the rotary developing device 60 is installed adjacently,
Since these are the same as those in the image forming apparatus shown in FIG. 5, description thereof will be omitted.

The rotary developing device 60 includes a magenta color developing device 61, a cyan color developing device 62, and a yellow color developing device 6 in the circumferential direction.
3 and the black color developing device 64 are arranged,
In order to switch the developing device fixed at the developing position facing the photosensitive drum 1, the developing devices 61 to 64 are rotated in the same circumferential direction by rotating in the direction of arrow R2.

According to the present invention, these developing devices 61-64
Is fixedly installed on the rotary developing device 60, and the developing sleeve 1 of each of the developing devices 61 to 64 at the developing position.
2 so that the photosensitive drum 1 and the photosensitive drum 1 face each other.
With the developing sleeve 12 facing outward from the center of
The developing devices 61 to 64 are arranged in the rotary developing device 60. Therefore, the developing device changes its posture with respect to the direction of gravity and rotates, and the developing device is turned upward at a position rotated 1/4 in the direction of arrow R2 from the developing position, and is rotated 3/4 at a position rotated 1/2. In the position, it takes a downward rotation posture.

In this way, in the structure in which the developing devices 61 to 64 move while maintaining the arrangement posture with respect to the center of the rotary developing device 60, unlike the conventional ferris wheel type rotary developing device,
Since there is no need for a rotating support shaft structure that holds each developing device uniformly in the direction of gravity, and an attachment / detachment mechanism that positions and releases the developing device with respect to the photosensitive drum at the developing position,
The device configuration is simplified, and the size can be reduced.

In this embodiment, a two-component developing device as shown in FIG. 2 is used as each of the developing devices 61 to 64 of the rotary developing device 60, and the developing container 17 has a non-magnetic metal developing device. Magnetic carrier 1 such as iron oxide powder on the sleeve 12 side
3, the non-magnetic toner 14 is stored on the back side thereof.
The magnetic carrier 13 and the non-magnetic toner 14 are mixed and used as a two-component developer.
The toner 14 is electrostatically attached to the surface of the. The developing sleeve 12 is arranged in an opening portion of the developing container 17 which is located at a position facing the photosensitive drum, and the magnet roller 11 is concentrically arranged in the developing sleeve 12. A doctor blade 15 is installed above the above with a predetermined gap therebetween. A stirring screw 16 is installed in the developing container 17.

The toner 14 in the developing container 17 is moved toward the developing sleeve 12 by the stirring screw 16 and mixed with the magnetic carrier 13 on the developing sleeve 12 side,
The developer is composed. The developer is supplied to the surface of the developing sleeve 12, the magnetic carrier 13 is attached to the surface of the developing sleeve 12 by the magnetic force of the magnet roller 11, and the toner 14 is electrostatically adsorbed on the surface of the carrier 13, so that the developer is Are carried on the developing sleeve 12.

The developer carried on the developing sleeve 12 is conveyed toward the developing portion facing the photosensitive drum by the rotation of the developing sleeve 12, and the doctor blade 15 and the magnet roller 11 magnetically regulate the toner during the conveyance. Then, it is applied as a thin developer layer on the developing sleeve 12. The developer applied in a thin layer forms a magnetic brush by the magnetic force of the magnet roller 11 in the developing section to develop the latent image on the photosensitive drum.

In such a two-component developing device, the developing container 1
The amount of magnetic carrier 13 in 7 is equal to that of magnet roller 11
Is generally larger than the amount that can be held on the developing sleeve 12 by the magnetic field. As in this configuration, the rotary developing device 6
When each developing device is fixedly installed at 0, the posture of the developing device changes and rotates as the developing device rotates in the circumferential direction, whereby the developer in the developing container 17 is scratched and insufficiently charged. Toner is excessively supplied to the developing sleeve 12. That is, when the developing device rotated 1/4 to 2/4 from the developing position is in a state in which the developing device is in an upward to inverted rotational posture, the carrier 13 is held in the developing container 17 by the carrier 13 in the developing sleeve 12.
When the carrier 13 is dissipated from the vicinity of the developing sleeve and then in the downward rotation posture of 3/4 rotation, the carrier 13
Come back near. When returning to the vicinity of the developing sleeve 12, the carrier 13 takes in the toner 14 excessively, so that the mixing ratio of the toner and the carrier (T / C
Ratio becomes high, and a large amount of toner whose frictional electrification with the carrier 13 is insufficient is included.

Therefore, when development is carried out by the developing device in the normal position returned to the developing position (returning to the normal position with no rotation at the developing position), the developer containing the insufficiently charged toner is developed. Since the image is conveyed to the developing device for development, the density of the developed image becomes uneven and fogging occurs. Further, since the adhesion to the surface of the developing sleeve 12 and the surface of the photosensitive drum 1 is weak, the toner is likely to be scattered into the apparatus when receiving electrostatic vibration due to the developing bias and wind pressure due to rotation of the photosensitive drum.

Therefore, in the present invention, a means for rotating the developing sleeve 12 of the developing device is installed at a position other than the developing position of the rotary developing device 60 facing the photosensitive drum 1 so that the developing device develops at a position other than the developing position. The sleeve 12 is kept in a rotationally driven state.

According to the present embodiment, the developing sleeve rotating means is, as shown in FIG. 1, provided with a small diameter outside the circumferential orbit of rotation of the developing device, for example, at a position rotated 3/4 rotation from the developing position. Drive gear 10. In the figure, the black developing device 64 facing the photosensitive drum 1 is next positioned at that position. The drive gear 10 engages with a gear (not shown) provided on the developing sleeve 12 of the black color developing device 64 and rotates in the arrow R3 direction, thereby rotating the developing sleeve 12 in the R4 direction which is the same direction as during development. .

Therefore, the developer containing a large amount of excessive toner and insufficiently charged toner returning to the vicinity of the developing sleeve 12 is collected in the developing container 17 by the rotation of the developing sleeve 12, and the developer is Excess toner is discharged from the toner, and the remaining toner is stirred and friction-charged for a sufficient time. For this reason, when the developing device is located at the developing position, a developer having sufficient toner 14 and a proper T / C ratio is carried on the developing sleeve 12 and conveyed to the developing section, and the developing of the photosensitive drum 1 is performed. Can be used for

As a result, it is possible to obtain a high-quality image without causing uneven density or fogging of the developed image. Further, since the toner 14 has a strong adhesive force on the surface of the developing sleeve 12 and the surface of the photosensitive drum 1, the toner may be scattered into the apparatus even if it receives electrostatic vibration due to the developing bias and wind pressure due to rotation of the photosensitive drum. Absent.

A rotary developing device according to another embodiment of the present invention is shown in FIG. The rotary developing device 80 of this embodiment comprises a magenta color developing device 81, a cyan color developing device 82, a yellow developing device 83 and a black developing device 84, which are non-magnetic one-component developing devices, arranged in the circumferential direction. As in the case of the previous embodiment, the developing devices 81 to 84 are fixedly installed with the developing sleeve 19 facing outward from the center of the rotary developing device 80.

These non-magnetic one-component developing devices 81-84 are
The developing device is configured as shown in FIG. The present developing device has a developing device 22 containing a non-magnetic toner 18 which is a non-magnetic one-component developer, and a semi-conductive member is provided in an opening portion of the developing container 22 facing the photosensitive drum. A developing roller 19 made of a flexible elastic member is installed, and an elastic roller 21 made of a conductive rubber sponge or the like is pressed against the surface of the developing roller 19 opposite to the opening. The non-magnetic toner 18 in the developing container 22 is carried on the elastic roller 21 by the rotation of the elastic roller 21 and supplied toward the developing roller 19, and is rubbed against the developing roller 19 by the elastic roller 21. By the frictional contact between the elastic roller 21 and the developing roller 19, the toner 18 is triboelectrically charged, and the toner 18 is applied and carried on the developing roller 19.

Toner 18 carried on the developing roller 19
Is conveyed by the rotation of the developing roller 19, and the elastic blade 2 that abuts on substantially the top of the developing roller 19 during the conveyance.
The toner is rubbed by 0 to impart a triboelectric charge, and the layer thickness is regulated to form a uniform toner layer on the developing roller 19. Toner 18 formed on the toner layer
Is conveyed to the developing section facing the photosensitive drum 1 as the developing roller 19 rotates, and is used for developing the latent image formed on the photosensitive drum 1.

As described above, in the non-magnetic one-component developing device, the charging mechanism for the non-magnetic toner 18 is based on the sliding friction between the elastic roller 21 and the developing roller 19 and the sliding mechanism between the elastic blade 20 and the developing roller 19. Consists of. Therefore, the attitude of the developing device changes as the rotary developing device 80 rotates,
When the toner is rotated and its posture is rotated, the toner 18
When the toner is directly supplied to the developing roller 19 without pressure contact by the elastic roller 21, the charging due to the rubbing is lost, so that the toner is insufficiently charged even if the elastic blade 20 rubs. This insufficiently charged toner is carried on the developing roller 19 and conveyed to the developing section, so that toner scattering and fogging occur.

Therefore, in this embodiment, the rotary developing device 80 is used.
A large-diameter drive gear 23 is installed coaxially with the center of rotation of the developing devices 81 to 84 in the circumferential direction, and the driving gear 23 is located at a position closer to the inner side of the circumferential orbit of rotation of the developing devices 81 to 84.
The developing roller 19 of 84 is engaged with a gear (not shown) to rotate in the direction of arrow R5. As a result, the developing roller 19 of the developing device 81 located at the developing position
Is rotated in the direction of arrow R6 to cause the developing device 81 to perform a developing operation, and the developing devices 82 to 8 located at other positions.
All the developing rollers 19 of No. 4 are rotationally driven in the R7 direction which is the same direction as the rotation during the developing operation.

Therefore, when the posture of the developing device is rotated, the developing roller 19 is not pressed by the elastic roller 21.
Even if the toner 18 is directly supplied to the developing roller 19, the toner 18 is carried on the developing roller 19 and the developing device is repeatedly rotated until it reaches the developing position, and the elastic blade 20 is pressed to charge the toner 18 in a sufficient time. As a result, the toner can be sufficiently charged. Therefore, when the developing device is located at the developing position, the developing roller 19 can convey the sufficiently charged toner 18 to the developing portion to be used for developing the photosensitive drum 1, and the density is sufficient and there is no fog. High quality development can be obtained. Further, the toner is not scattered into the apparatus.

[0033]

As described above, in the rotary developing device of the present invention, a plurality of two-component developing devices or non-magnetic one-component developing devices are circumferentially arranged and fixedly installed. In the present invention, means for rotating the developer carrier of the developing device is provided at a position other than the developing position where the developing device faces the image carrier, and the two components in the developing container are set by the time the developing device reaches the developing position. The non-magnetic toner of the developer or the one-component developer was agitated. Therefore, the posture of each developing device rotates as the developing device rotates in the circumferential direction, and the non-magnetic toner of the two-component developer or the one-component developer in the developing container moves excessively, and the developer carrier is charged. Even if insufficient toner is supplied, the charging of the toner can be stabilized before the developing device reaches the developing device. As a result, it is possible to obtain a high-quality image without causing non-uniformity in the density of the developed image or fogging, and to prevent toner scattering into the apparatus.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a rotary developing device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a two-component developing device installed in the rotary developing device of FIG.

FIG. 3 is a sectional view schematically showing a rotary developing device according to another embodiment of the present invention.

4 is a cross-sectional view showing a non-magnetic one-component developing device installed in the rotary developing device of FIG.

FIG. 5 is a schematic configuration diagram showing a multicolor image forming apparatus in which a conventional rotary developing device is installed.

[Explanation of symbols]

 1 Photosensitive Drum 10, 23 Drive Gear 12 Developing Sleeve 13 Magnetic Carrier 14, 18 Non-Magnetic Toner 15 Doctor Blade 19 Developing Roller 20 Elastic Blade 21 Elastic Roller 60, 80 Rotating Developing Device 61-64 Two-Component Developing Device 81-84 Non-Magnetic One component developer

Claims (5)

[Claims] 1. A developing device which carries a plurality of developing devices arranged in the circumferential direction and rotates in the circumferential direction, stops the circumferential rotation at a developing position where the developing device faces the image carrier, and develops the developing device in the developing position. In a rotary developing device for developing an electrostatic latent image formed on an image carrier by a developing device, there is provided a means for rotating the developer carrying member of the developing device at a position other than the developing position. Development device. 2. The rotating means is driven by engaging with a gear provided on a developer carrying member of the developing device, which is installed at a position on the outer side of a circumferential orbit of rotation of the developing device, at a position on the outer side. The rotary developing device according to claim 1, which is a drive gear. 3. The rotating means comprises all the gears provided on the developer carrying members of a plurality of developing devices, which are installed coaxially with the rotation center of the developing device rotation, and inside the circumferential orbit of the developing device rotation. 2. A drive gear that is engaged and driven at the position
Rotation developing device. 4. The rotary developing device according to claim 1, wherein the developing device is a two-component developing device that uses a two-component developing agent in which a magnetic carrier and a non-magnetic toner are mixed. 5. The rotary developing device according to claim 1, wherein the developing device is a one-component developing device using a non-magnetic one-component developer consisting of only non-magnetic toner.