JPH02272595A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a color mixture from being generated in a toner carried by a developing sleeve by providing a cleaning member having a press- contacting/release function against an image forming body, and a plate-like leveling member which moves and abuts by interlocking with press-contacting and release of the cleaning member. CONSTITUTION:This device is provided with a cleaning member 4 having a press-contacting/release function against an image forming body 30, and a plate- like leveling member 43 which moves and abuts by interlocking with press- contacting and release of the cleaning member. Accordingly, a toner lump which is generated at the time of drawback of a cleaning blade 41 and remains behind in the rear end part of an image area is lowered as to its height, and also, leveled flatly by the leveling plate 43 and compressed to thickness contained enough in an interval of a developing area of the case by a developing system of non-contact, that is, a gap between the image forming body 30 and a developing sleeve. In such a way, it can be prevented that a color mixture is generated in a toner carried by the developing sleeve.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus that forms a color toner image by superimposing a plurality of toner images of different colors on an image forming member.

[Background of the invention]

An electrophotographic image forming apparatus that forms a color image such as a full color image or a functional color image includes a charger that charges a photoreceptor drum that is an image forming member, an image exposure unit that exposes an image to the photoreceptor drum, and a photoreceptor drum. A developing device that develops the electrostatic image on the photosensitive drum with toner, a transfer device that transfers the toner image on the photosensitive drum onto recording paper, and the like are arranged around the photosensitive drum.

Among these, the developing units in full-color electrophotographic image forming apparatuses are comprised of three or four developing units each containing yellow (Y), magenta (M), cyan (C) toner, and sometimes black (BK) toner. It consists of a developing device, and while the photosensitive drum rotates three or four times,
Yellow (Y), magenta (M), cyan (C), and black (BK) toner images are formed on the photosensitive drum, and these toner images are transferred to recording paper to obtain a full-color image. There is.

Japanese Patent Laid-Open No. 61-55661 discloses a color image forming apparatus using such an image forming method, and in such an apparatus, toner images of different colors are formed by superimposing on the already formed toner image. Therefore, a non-contact developing method called jumping development is used.

In this developing method, the developing sleeve on the developing device side is placed in a position that maintains a small gap between the image forming body and the image forming body, and alternating current and direct current biases are applied to the developing sleeve, and the toner is flown toward the grounded image forming body. We are taking measures to make that latent image visible.

[Problem that the invention seeks to solve]

The gap between the developing sleeve and the image forming body is at most 0.5
Since the toner particles are extremely small (about a + m), if toner lumps remain on the image forming body during cleaning after image transfer, color mixing will occur in the first toner image of a newly formed color image, making it difficult to obtain a color image with accurate tone. The problem arises that it cannot be obtained.

The present invention solves and improves this point, and as a result, the toner mass remaining on the image forming member is flattened before the start of new image formation, that is, within the non-image area of the surface of the image forming member, and is removed from the developing sleeve. The object of the present invention is to provide an image forming apparatus in which color mixing does not occur in toner carried thereon.

[Means for Solving the Problems] The above object is to provide an image forming body, a cleaning member having a function of pressing and releasing the image forming body, and a cleaning member that moves and contacts in conjunction with the pressing and releasing of the cleaning member. This is achieved by an image forming apparatus characterized by having a plate-like leveling member.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 to 6.

FIG. 1 shows a printer to which the present invention is applied.

The printer has a clamshell structure divided into an upper casing 1 and an apparatus main body 2, and the upper casing 1 is held at a predetermined open angle using a hinge LA connected to the apparatus main body 2 as a fulcrum. This is possible, and in the closed state, it is integrated with the main body 2 of the device by means of a locking fitting (not shown).

An image forming body 30 constituting an image forming section of the printer, developing devices 36, 37, 38, and 39 containing yellow, magenta, cyan, and black developers, and a cleaning device 40.
In addition, the charger 35, pre-transfer charger 9, and toner collection box 70 are housed in the integrated process cartridge 3 to form a unit, and a guide member 4 is provided on the bottom surface.
Particularly in this embodiment, each of the above-mentioned developing units 36.
The housings 37, 38, and 39 are integrally constructed and arranged in order downward from the image forming body 30 and facing upward from the upstream direction of the rotation so as to face the circumferential surface of the image forming body 30.

That is, the process cartridge 3 is inserted and mounted in the depth direction of the apparatus main #2 by holding the handle provided on the front side and holding the guide member 4, and when pulled out toward the front, the holding of the guide member 4 is released and the process cartridge 3 is installed. Although it is removed from the front of the main body 2, each developing device is kept in a position with its opening facing upward, so the developer may leak out and fall or get mixed into other developing devices. Nothing like that happens.

The printer has a laser writing system unit B in a space on the side of the process cartridge 3, and a transfer material conveying surface in a part above the process cartridge 3 that spans both the upper housing 1 and the main body 2 of the apparatus. We have set up
The image forming member 30 is subjected to laser scanning by the laser writing system unit B from diagonally downward, and a color toner image formed by superimposing the laser scanning surface is transferred onto the lower surface of the recording paper.

In this way, the transfer material is conveyed horizontally over the top of the process cartridge 3, and the transfer surface is also facing downward, so even if toner spills or scatters from the cleaning device 40 or the like, the image surface will be contaminated. I never get to the point where I do it.

In addition, this device has the following advantages: (1) The paper feeding system is located below, and the center of gravity is set further below, which has great advantages in terms of the structure of the machine.

(2) The transport system can be easily opened in the event of a jam.

Benefits include:

The process of color image copying by the printer is performed as follows.

First, the formation of a multicolor image according to this embodiment is performed according to the image forming system shown in FIG. That is, the color image data input section (Fig. 4 (a)) where the image sensor scans the original image.
) is processed by an image data processing unit equipped with a computer (Fig. 4 (b)) to create image data, which is then stored in the image memory (Fig. 4 (c)). Stored. Then, the image memory is taken out during recording and stored in the recording section (
For example, the image data is input to the color image forming apparatus shown in the embodiment shown in FIG.

That is, when a color signal output from an image reading device separate from the printer is input to the laser writing system unit B, the laser writing system unit B outputs a laser beam generated by a semiconductor laser (not shown). is rotated and scanned by a polygon mirror 32 rotated by a drive motor 31, and passes through an fθ lens 33 to three mirrors 34A,
An image forming body 30 whose optical path is bent by 34B and 34G and to which a charge is applied in advance by a charger 35 serving as a charging means.
is projected onto the circumferential surface to form a bright line.

On the other hand, when scanning is started, the beam is detected by the index sensor, modulation of the beam by the first color signal is started, and the modulated beam scans the circumferential surface of the image forming body 30. Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the image forming body 30 by the main scanning by the laser beam and the sub scanning by the rotation of the image forming body 30. This latent image is developed by a developing device 36 loaded with yellow (Y) toner (developing medium) of the developing means, and a toner image is formed on the drum surface. The obtained toner image passes under a cleaning device 40, which is a cleaning means, which is separated from the peripheral surface of the image forming body 30 while being held on the drum surface, and enters the next copy cycle.

That is, the image forming body 30 is charged again by the charger 35, and then the second color signal output from the signal processing section is input to the writing system unit I-B, and the above-mentioned first color signal is Writing is performed on the drum surface in the same manner as in the case of the drum surface, and a latent image is formed.

The latent image is developed by a developer 37 loaded with magenta (M') toner as a second color.

This magenta (M) toner image is formed in the presence of the previously formed yellow (Y) toner image.

A developing device 38 has cyan (C) toner, and forms a cyan (C) toner image on the drum surface based on a control signal generated by a signal processing section.

Furthermore, 39 is a developing device having black toner, and a black toner image is superimposed and formed on the drum surface by the same process. Direct current or even alternating current bias is applied to each sleeve of these developing units 36, 37, 388, and 39, and jumping development is performed using a two-component developer serving as a developing means to form an image with a grounded substrate. body 30
Development is now possible without contact.

The color image thus formed on the circumferential surface of the image forming body 30 is transferred to the lower surface of the transfer material fed from the paper feed cassette C via the paper feed roller and the paper feed guide in the transfer section.

That is, after this multicolor toner image is charged by the pre-transfer charger 9 to be easily transferred, the transfer belt 50 used as a transfer means, which has been rotated since the start of transfer, is brought into contact with the image forming body 30 and fed. Paper feed roller 1 from paper cassette C
2 and the timing roller 13, the image is transferred onto the supplied recording paper in synchronization with the image formation.

The transfer belt 50 is stretched between rollers 59 and 60,
The roller 60 is rotated in synchronization with the circumferential speed of the image forming body 30, and as the roller 58 moves up and down, it is moved away from or in contact with the image forming body 30.

The roller 58 is attached to a lever 57 that can swing around the axis of the roller 60 as a fulcrum, and is held in the upper position shown by the solid line by an elastic member that biases the lever 57. The transfer belt 50 is moved downward by the power of a solenoid or the like operated at the timing indicated by a dashed line, that is, to a position where the transfer belt 50 is brought into pressure contact with the circumferential surface of the image forming body 30.

As the transfer belt 50, a rubber belt containing a conductive cloth is used as a base, and a high resistance layer or an insulating layer having an elastic body with a thickness of 0.5 mm is provided on the outer periphery of the belt.

The transfer belt 50 is charged by a transfer device 51, and a transfer charge having a polarity opposite to that of the toner is applied to perform the transfer. Note that the toner adhering to the transfer belt 50 is removed and cleaned by a transfer belt cleaning device 50A.

The transfer material to which the multicolor toner image has been transferred in this way is an image forming body 3.
It is separated from the circumferential surface of the fixing roller 8 and transported to the fixing device.
After the toner is melted and fixed by 0, the toner is discharged to the outside of the machine via the paper discharge roller 90.

On the other hand, the image forming body 30 from which the transfer material has been separated is cleaned by removing residual toner by the cleaning device 40 according to the present invention.

FIG. 2 shows the details of each member constituting the cleaning device 40, and each member described below is housed in a housing and is rotated clockwise relative to the circumferential surface of the image forming body 30. As shown in the figure, it is installed diagonally in the upper right position.

In FIG. 2, a blade 41 is a cleaning member that comes into pressure contact with the surface of the image forming body 30 to remove residual toner, and is held by a blade holder 41a and freely rotates about a shaft 40A installed between the front and rear side walls. It is supported so that it can move.

42 is a rotary plate supported on the shaft 40A near the rear side wall so as to freely rotate like the blade holder 41a, and a worm gear portion 42a and an arc-shaped protrusion 42b are formed on a part of its outer periphery. Drive bin 42 protruding toward the front
It is equipped with c.

A tension spring 44 is stretched between the rotary plate 42 and the blade holder 41a, and the blade holder 41a is brought into contact with a stop pin 42d on the rotary plate 42 to be integrated.

Reference numeral 43 denotes a leveling plate provided to flatten the toner lumps accumulated on the circumferential surface of the image forming body 30 after cleaning by the blade 41, and is held by the leveling plate holder 43a and connected to the shaft 40A, which is installed between the front and rear side walls. They are supported so as to be freely rotatable about parallel shafts 40B as fulcrums.

The leveling plate holder 43a is integrally formed with an arm portion 43b that overlaps the rotary plate 42, and a cam 143c provided on the arm portion 43b engages with the drive pin 42c of the rotary plate 42, and the arm portion 43b It is constantly biased clockwise by a tension spring 45 stretched between and the side wall. The cam groove 43c is composed of a circular arc portion centered on the shaft 40A and a widened bent portion.

The blade 41 is a plate-shaped member made of a well-known hard urethane rubber or the like, and its tip is pressed against the circumferential surface of the image forming body 30 with some force, whereas the leveling plate 43 is made of hard urethane rubber or the like. This member is made of, for example, mylar material and has a small but sufficient elasticity, and is pressed against the circumferential surface of the image forming body 30 with a rather large contact area.

Further, M is a motor, and W is a worm attached to the rotating shaft of the motor M. The worm W meshes with the worm gear portion 42a of the rotating plate 42, and by switching the rotational direction of the motor M, the rotating plate 42 is rotated clockwise or clockwise. It is possible to select and drive rotation counterclockwise.

SWl, SW2. SW3 is a switch that is activated by pressing the protrusion 42b of the rotary plate 42, and the rotation phase of the rotary plate 420 is detected by a signal from the switch group, and the control system that receives the signal starts the motor. The rotational operation of M and its direction are controlled.

FIG. 2 shows the state of the cleaning device 40 when an image is being formed on the circumferential surface of the image forming body 30. In this case, the switch SW2 is turned on by the pressure of the protrusion 42b and the motor is turned on. The rotation of M stops and the rotating plate 4
2 is stationary in the rotational phase shown.

As a result, the blade 41 is held in a position retracted from the surface of the image forming body 30 by the contact of the blade holder 41a with the stop pin 42d, while the leveling plate 43 is also held in the position of the drive bin 42c relative to the leveling plate holder 43b. Due to regulations, it is retracted to a position spaced apart from the surface of the image forming body 30.

The cleaning device 40 operates synchronously around the leading edge of the image after the transfer of the image forming body 30, but in this case, cleaning the peripheral surface of the image forming body 30 is performed using a lamp 46 installed at the top of the housing. The residual toner is previously de-charged by the device comprising the light guide section 47 and is brought into a state where it can be easily peeled off.

From the state shown in FIG. 2, the motor M starts to rotate in the opposite direction in synchronization with the arrival of the leading edge of the image, and the rotation plate 42 is driven and rotated counterclockwise due to the engagement between the worm W and the worm gear part 42a. Turn off the switch SW2 using the protrusion 42b, and then turn on the switch SWI.
The rotation of motor M is stopped as follows.

The rotary plate 42 rotates following the blade holder 41a by the action of the tension spring 44, but in the process, the tip of the blade 41 is brought into contact with the circumferential surface of the image forming body 30 as shown in FIG. 3(a). It should be noted that after further rotation while being brought into strong pressure contact by the biasing force of the tension spring 44, the motor M stops rotating and comes to rest at the position shown in the figure.

Therefore, the cleaning device 40 is placed in a state where the residual toner on the circumferential surface of the image forming body 30 is removed by the blade 41, while the leveling plate holder 43a is in a state where the drive bin 42C of the rotary plate 42 is removed from the cam. Since the arc portion of the groove 43c is only moved, the leveling plate 43 is not rotated and is maintained at the angle shown in FIG.
Continuously hold it in a position away from the circumferential surface of the

After a predetermined period of time has elapsed after the blade 41 finishes removing the residual toner from the image area, the motor M starts to rotate forward and rotates the rotary plate 42 clockwise, thereby removing the protrusion 42b.
passes through the switch SW2 which is placed in the neutral state, turns on the switch SW3, and the rotation of the motor M is stopped by that signal.

The rotary plate 42 therefore rotates clockwise, and in the process, the blade holder 41a follows as a unit, and further rotates to retract the blade 41 far beyond the circumferential surface of the image forming body 30, as shown in FIG. 3(b). After that, motor M
The rotation ends when the motor stops.

On the other hand, the leveling plate holder 43a is rotated slightly clockwise as the driving pin 42c of the rotary plate 42 moves to the widened bent portion of the cam groove 43c, and is further freed, so that the tension spring The leveling plate 43 is brought into pressure contact with the circumferential surface of the image forming body 30 by the biasing force 45 .

This state lasts from when the rear end of the image area reaches the pressing position of the leveling plate 43 until just before the leading edge of the next image area arrives, that is, the leveling plate 43 presses only the non-image area between the images. The operating time is controlled so that the motor M rotates in the reverse direction again, returning to the state shown in FIG.

As a result, the toner mass remaining at the rear end of the image area generated when the blade 41 is retracted is made flat and low in height by the leveling plate 41. It is compressed to a thickness that is sufficient to fit into the gap between the image forming body and the developing sleeve.

FIG. 5 shows each developing device, each charging and transfer electrode, and the blade 41 in the cleaning device 40.
．． This is an example of settings showing the respective positional relationships of the leveling plate 43 with respect to the image forming body 30, and in this example, the image forming process by the printer is performed as shown in the time chart of FIG. By the end of the rotation, the blade 4
One cycle of image copying is completed by removing the residual toner by pressure contact in step 1 and flattening the toner mass by the leveling plate 43, which operates after a short period of time.

〔Effect of the invention〕

The present invention minimizes the accumulation of residual toner on the image forming body, which tends to occur in blade-type cleaning devices, within the non-image area of the image forming body so as not to interfere with the development process or the image itself. As a result, a superimposed color image forming method using a non-contact development method was realized, making it compact, easy to handle, and capable of producing excellent color images. A color image forming apparatus is now provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an image forming apparatus of the present invention, FIG. 2 is a sectional view of a cleaning device of the apparatus, FIG. 3 is a diagram of its main parts, and FIG. FIG. 5 is an explanatory diagram showing an arrangement example of each equipment in the image forming apparatus, and FIG. 6 is a time chart of image formation according to the arrangement example. 30... Image forming body 40... Cleaning device 41... Blade 42... Rotating plate 42b... Protrusion 43... Leveling plate 43b... Arm portion 44.45... Tension spring W...Warm swl, SW2, SW3...Switch

Claims (1)

[Claims] An image characterized by having an image forming body, a cleaning member having a function of pressing and releasing the image forming body, and a plate-shaped leveling member that moves and comes into contact with the pressing and releasing of the cleaning member. Forming device.