JPH0254284A - Picture forming device - Google Patents

Abstract

PURPOSE:To make the toner concentration uniform in the developing width direction and to eliminate the density difference between the interior and exterior parts of a picture in the width direction by supplying a developing agent to a developing sleeve by driving a device for carrying a developing device. CONSTITUTION:The supply of a developing agent 8 to a developing sleeve 1 of a developing device 34Y is carried out by driving a device for carrying a developing device 34 which is mounted with plural developing device. After the supplied developing agent 8 is used for development, the excessive quantity of the developing agent 8 which is not used for the development and recovered into a developing chamber is not supplied to the developing sleeve 1 for the next development, but is returned to a developing agent circulating system in the developing chamber. Therefore, sufficient triboelectricity can be given to replenished toner and, at the same time, the toner concentration can be made uniform in the developing width direction. Thus the density difference between the interior and exterior sides of a picture in the width direction can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for manufacturing photosensitive drums through a predetermined process. !
A latent image is formed on a latent image carrier, this latent image is developed with a developer to obtain a developed image, this developed image is transferred to a transfer material, and then the transferred image transferred to the transfer material is fixed. Regarding an image forming device in which a permanent image is fixed in the device, in particular, a plurality of developers of different colors are movable according to a predetermined process with respect to a latent image formed on a latent image carrier. The present invention relates to an image forming bag that can be suitably applied to a color electrophotographic copying machine, etc., which is equipped with a developing device that accommodates a developer, and performs development that can produce multicolor images.

Conventional Art 1 For example, in order to form a color image, a latent image is formed on a latent image carrier such as a photosensitive drum through a predetermined process, and this latent image is transferred to each developer in a developing device having a different color. A developed image is obtained by performing development corresponding to each color with a developing agent, and this developed image is transferred to a transfer material, and then the transferred image transferred to the transfer material is fixed as a permanent image by a fixing device. A variety of color image forming apparatuses are used.

Various proposals have already been made regarding the method of transporting and circulating the developer within the developer container of the developing device used in this type of image forming apparatus. It seems that the technology related to the transport and circulation of developer in the developing device used has reached a state of perfection. However, even in this field, efforts are being made to reduce the size, weight, and cost of developing devices.

However, in the developing device that is designed to be smaller, lighter, and lower in cost, the time required for mixing and agitating the toner and carrier after replenishing the amount of toner commensurate with consumption is short.
Sufficient triboelectricity is not applied, and not only ground force blur and reverse fog appear on the image, but also toner scattering from the developer container.

To solve this problem, an idle rotation mode is used in the sequence, and the toner mixing and agitation time is set longer. Such measures are particularly effective for general-purpose copying machines, etc., which consume a small amount of toner on the screen and require only a small amount of toner to be replenished; It is not very effective against this problem, and a new developing device different from the conventional one is required.

Therefore, a developing device has been proposed in which the supplied toner is sufficiently mixed and agitated before being used for development, but in this development device the inside of the developing container is divided into a stirring chamber and a developing chamber, and the toner is replenished in the stirring chamber. The toner is mixed and stirred and conveyed to the developing chamber through one of the openings at both ends of the developing container, and in the developing chamber, development is performed using the conveyed toner, and the developer whose toner concentration has decreased due to toner consumption is transferred to the other side. By transporting and circulating the material through the opening into the stirring chamber, the insufficiency of tribo application mentioned in @ is solved.

However, in a developing device used in an image forming apparatus such as the above-mentioned full-color electrophotographic copying machine, the replenished toner and the developer whose toner concentration has been reduced are mixed and stirred and conveyed to one end of the developing width. For example, a developer with a high toner concentration is supplied to the back side of the developing width.
Since the image is immediately conveyed to the developing sleeve, the image tends to be darker on the back side in the developing width direction and lighter on the near side.

In addition, developing units of other configurations used in conventional black-and-white electrophotographic copying machines, etc. have the same or similar problems as described above, and in order to solve them, developing devices on the developing sleeve Various methods have been devised to supply the developer and to recover the developer that contributed to the development.

However, there is a limitation that the developing device used in such electrophotographic printers is always fixed.
It is undeniable that such measures are insufficient, and that trying to improve them results in an increase in the size of the device configuration and high cost.

but The present invention has been made in view of the above problems.

The purpose of this is to make the toner density uniform along the developing width direction, and to eliminate the difference in density between the back and front sides of the image in the width direction. An object of the present invention is to provide such an image forming apparatus.

The above object is achieved by an image forming apparatus according to the present invention. That is, in summary, the present invention includes a plurality of developing devices each having a developing sleeve in a developing device conveying device in order to develop an object to be developed formed through a predetermined process with a developer of a different color. In an image forming apparatus, the developing device to be subjected to development is transported to a developing position by driving the developing device conveyance device, and the developing device to be subjected to development is developed. This image forming apparatus is characterized in that the agent is supplied by driving the developing device conveyance device.

That is, in the image forming apparatus of the present invention, the developer is supplied to the developing sleeve of the developing device by driving a developing device conveying device equipped with a plurality of developing devices, and this supplied developer contributes to the development. After that, the excess developer collected in the developing chamber without being used for development is returned to the developer circulation system in the developing chamber without being supplied to the developing sleeve for the next development. It is.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments thereof with reference to the accompanying drawings.

FIG. 4 is a schematic cross-sectional view of a color electrophotographic copying machine as an image forming apparatus to which the present invention is applied. Referring to FIG. 4, this color electrophotographic copying machine includes a photosensitive drum 31 as an image carrier that rotates in the direction indicated by the arrow in FIG. Around the photosensitive drum 31, a charger 32. An exposure optical system 33, a developer transport device 34, a transfer device 35, and a cleaning device 36 are provided, respectively. Further, this color electrophotographic copying machine is equipped with a separating means 38 for separating the transfer material and a fixing device 39 downstream of the transfer device 35, and
A cassette 37 is provided that stores a transfer material at a predetermined position and supplies the transfer material.

Here, the exposure optical system 33 has a document scanning section 33a and a color separation filter part 33b, and the developer transport device 134 has a yellow developer 3 that uses yellow toner.
4Y, magenta developer 34M that uses magenta toner
, a cyan developer 34C using cyan toner and a black developer 34BK using black toner are integrally provided. As shown in the figure, each developing device is detachably held on a support 34a of a developing device conveying device 34, and is rotated about a central axis 34b of the developing device conveying device 2i34.
It is possible to exchange each developer to be used for a development position. Further, the transfer device 35 includes the gripper 3
It has a drum 35b for 5alk* and a transfer discharger 35c inside the drum 35b.

In order to form a full-color image with the color electrophotographic copying machine having such a configuration, it has been necessary to perform a predetermined process such as charging and exposure, which is conventionally carried out, to form a hidden image on the photosensitive drum 31. An image is formed, this latent image is developed corresponding to each color in each developing device of the developing device conveying device 34 to form a visible image, this visible image is transferred onto a transfer material supplied from a cassette 37, and this latent image is transferred onto a transfer material supplied from a cassette 37. After the transfer process is completed, the transfer material is separated from the photosensitive drum 31 by the separating means 38, and the separated transfer material is then conveyed to the fixing device 39, where it is fixed and transferred onto the transfer material. After the transferred image is fixed as a permanent image, it is discharged onto a discharge tray.

Here, regarding the developing device of the color electrophotographic copying machine mentioned above,
Referring to FIG. 1, each developing device includes a photosensitive drum 3 as a latent image carrier such as a photosensitive member or a dielectric material.
1, a developing device conveying device 34 for developing a latent image formed by electrophotography, electrostatic recording, etc., and housing and holding each developing device, includes a yellow developing device 34Y,
It is equipped with a cyan developing device 34C, a magenta developing device 34M, and a black developing device 34BK, and a rotation center shaft for rotating the supporting body 34a of each developing device and the developing device conveying device W34 to convey each developing device to the developing position. 34b.

Each developing device includes not only a developing container containing toner, but also a developing sleeve l as a developer carrying member, a blade 2 as a developer layer regulating member, and the like.

Here, since each developing device has the same configuration, a description of each developing device will be omitted, and the yellow developing device 34Y will be described as a representative of each developing device.
An opening is formed in a position close to the 4Y photosensitive drum 31, a developing sleeve 1 as a developer carrier is rotatably provided in this opening, and a developer is placed above the developing sleeve 1. A blade 2 as a layer regulating member is attached with a predetermined gap.

The developing sleeve l is made of a non-magnetic material, and a magnet 11, which is a magnetic field generating means, is fixed inside the developing sleeve l.
This magnet 11 has a developing magnetic pole Sl and magnetic poles N, , Nz for conveying a developer 8, which will be described later. During a developing operation, this developing sleeve I rotates in the direction of arrow B shown in FIG. 1.

Further, the blade 2 is made of a non-magnetic material such as aluminum (AR), and is attached with a predetermined gap between it and the surface of the developing sleeve 1 as described above. Developer 8 transported to the developing section
Specifically, the thickness of the developer 8 on the developing sleeve 1 is regulated. Therefore, in this embodiment, both the non-magnetic toner and the magnetic particles pass between the tip of the blade 2 and the surface of the developing sleeve I and are sent to the developing section.

The inside of the developing device 34Y is divided into a developing chamber (first chamber) P and a stirring chamber (second chamber) by a partition 5 extending perpendicular to the plane of the paper in FIG.
A toner storage chamber PZ is formed above the stirring chamber Pz with a partition wall 6 in between, and replenishment toner (non-magnetic toner) 7 is stored in this toner storage chamber P3. In addition.

At the front and rear ends of the developing device 34Y in FIG. 1, that is, at the rear and front ends in the direction perpendicular to the paper of FIG. Openings (not shown) are formed at both ends to allow the developing chamber P and stirring chamber P to communicate with each other.

A replenishment port 6a is opened in the partition wall 6.
An amount of replenishment toner 7 commensurate with the amount of toner consumed through step a is dropped into the stirring chamber PZ and replenished. A developer 8 is accommodated in the developing chamber P+ and the stirring chamber Pz, and this developer 8 is a two-component developer consisting of non-magnetic toner and magnetic particles (carrier).

A developing sleeve 1 is installed at the bottom of the developing chamber PI of the developing device 34Y.
An eleventh transport means 9 is disposed nearby, which rotates in the direction of arrow C (counterclockwise) shown in FIG. Developing device 34
It is located at the inner bottom of the stirring chamber SZ of Y in a substantially concave-horizontal position with the first conveyance means 9, and rotates in the direction of the arrow (clockwise) shown in FIG. A second conveying means 10 for conveying from the front side to the rear side in the direction is provided.

1st and 2nd like this! Specifically, the II feeding means 9 and 10 have a screw pitch P (P
+, Pz), and can be configured with a spiral-shaped screw.

The specific behavior of the developer in the developing device according to the present invention having such a configuration will be explained with reference to FIG.

As shown in FIG. 3, the development position facing the photosensitive drum 31 as a PII image carrier is set as position 50,
From there, the positions at which the developing device conveying device 34 stops rotating by 90° in the direction of arrow E are determined at positions 51, 52, and 53, respectively.
Then, the developer 8 in the developing chamber behaves as shown in FIG. The developer 8 in the developing chamber PI, which has been sufficiently captured by the Nz pole of the developing sleeve 1, moves as shown by the arrow F in FIG. to form a developer layer of a predetermined thickness,
After being carried to the developing area and used for development, excess developer 8 that is not used for development is collected into the developing chamber.

The collected developer 8 is then transferred to N, - of the developing sleeve l.
The developer is scraped off from a position slightly past the N+ pole by the repulsive magnetic field Nz, and this scraped developer is
Due to the effect of the repelling magnetic pole, the developer is not supplied to the developing sleeve 1 again.As a result, the developer with a high toner concentration is transferred to the back side, that is, the surface of the paper in FIG. Even if the developer is supplied from the back side in the vertical direction, this developer with high toner concentration will not be reflected on the developing sleeve l.Thus, when the development is completed, the developer will be trapped near the NZ extreme, as shown in Figure 5. The agent will be in a reduced state.

Then, a toner concentration detection device (not shown) detects the toner concentration of the developer '8, and according to the detection result, replenishment toner 7 commensurate with consumption is supplied from the replenishment port 6a onto the second conveying means 10, Thereafter, in combination with the driving of the first conveyance means 9, the developer 8 is circulated.

In addition, the preferable magnetic pole arrangement of the above-mentioned developing sleeve 1, that is, the angle between the poles, is as follows. That is, s, -N,: Zoo°~140°N, -N,: 100'~150°Nz-3,: 90'~140'.

Next, by driving the developing device conveyance device 34, at positions 52 and 53 of the developing device, the developer in the developing device to be supplied for the next development is captured near Nz.

Here, the first and second conveying means 9 and l having the above-described configuration are used.
The screw pitches P, , pz of O are respectively PI
= 15 to 20 mm Pz = 20 to 25 mm, and the rotational speed ratios of the developing sleeve l and the first and second conveying means 9 and 10: No: N: Nz1 No: N1: N
Assuming that z=1:2.5 to 3 degrees and 5:2.5 to 3.5, the actual stirring distance and the amount of developer actually required in the extreme vicinity of Nz will be determined from the specific example shown below.

Specific Example First, let's try to find the amount of developer actually required near the NZ pole.

Assuming that the peripheral speed of the photosensitive drum 31 is 160 mm/sec,
The time required to develop the longitudinal direction of A3 paper is 420 /
l 80 = 2, 625 sec, and assuming that the developing sleeve diameter is 20φ, the sleeve effective developing is 300 mm, the sleeve rotation speed is 3.2 rps, and the developer coating amount is 60 mg/c. 1. For example, to obtain an A3-sized item, approximately 95 gr of developer is sufficient, and in order to capture more developer, the magnetic flux density of NZ, half-width, interpolar angle of Nz-3, and All you need to do is select the position of the blade.In this specific example, the magnetic flux density of NZ is 800G, the half width is 45°, the angle between N-S+pole is 120°, and the Nz-blade angle is 30°.
Approximately 120 gr of developer can be captured at 1.

Next, let's find the actual stirring distance.

In the case of this specific example, the developer is conveyed approximately 40 to 90 mm per one rotation of the developing sleeve, and approximately 16 mm is conveyed on the short side of A4 paper.
0mm ~ 370mm, about 320 ~ 740 for A3 long side
mm, the developer and replenishment toner are mixed and stirred, and insufficiently stirred developer is not immediately reflected on the developing sleeve 1, so that the toner concentration is uniform across the entire developing width direction, and the toner concentration is uniform across the entire developing width direction, and the toner concentration is uniform in the depth of the image. It is possible to eliminate the difference in image density between the side and the front side, that is, the direction perpendicular to the page.

Next, another embodiment of the present invention will be described with reference to FIG.

This other embodiment has almost the same configuration as the above-mentioned embodiment, and the explanation of the same parts as the above-mentioned embodiment will be omitted.
In this embodiment, the developer used does not necessarily have to be the two-component developer mentioned above; for example, a l-component developer used in a black developing device can also be used as long as it has the effect of color vision and inking. It is something that can be done. In this embodiment, since the l-component developer 61 is used, unlike the previous embodiment, In! Since no mechanism is required, a significant cost reduction can be expected, and the sleeve ghost, which has been a problem in the past, can be avoided.

It goes without saying that the method of supplying the developer to the developing sleeve is the same as in the previous embodiment.

As explained above, according to the image forming apparatus of the present invention,
It is possible to provide sufficient triboelectricity to the supplied toner, and also to make the toner density uniform along the development width direction, thereby eliminating the density difference between the back side and the front side in the width direction of the image, Furthermore, it is possible to provide an image forming apparatus having a developing device that is small, lightweight, and low cost.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged schematic diagram of a developing device used in an image forming apparatus according to the present invention. FIG. 2 is a schematic perspective view of a developer conveying means used in the developing device shown in FIG. FIG. 3 is a schematic cross-sectional view of a developing device conveying means for accommodating and holding the developing device shown in FIG. FIG. 4 is a schematic sectional view of a color electrophotographic copying machine which is an embodiment of the image forming apparatus according to the present invention. FIG. 5 is a partially enlarged schematic diagram of the developing device shown in FIG. 1, showing the state of distribution of developer after the developing device is operated. FIG. 6 is a partially enlarged schematic diagram of another developing device used in the image forming apparatus according to the present invention. 1: Developing sleeve 8: Developer 34: Developing device transport device 34Y, 34M, 34C134BK: Developing device Fig. 2 P (PI, P2) Fig. 3 Fig. 5

Claims (1)

[Claims] 1) In order to develop the object to be developed formed through a predetermined process with developers of different colors, a plurality of developing devices each having a developing sleeve are mounted on a developing device conveying device, and the developing device conveying device is equipped with a plurality of developing devices having developing sleeves. In an image forming apparatus in which a developing device to be subjected to development is conveyed to a developing position by driving the device to develop the object to be developed, the developer is supplied to the developing sleeve by the developing device. An image forming apparatus characterized in that image forming is performed by driving a conveying device.