JPH02271380A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain the image forming device which efficiently removes residual toner even for an image forming body which rotates reversely by providing the image forming device with a cleaning member, which has the prescribed function, and a rotating member, which recovers developer on the downstream side of the member. CONSTITUTION:The image forming device is constituted of the image forming body 30, the cleaning members 41 and 42 having the press-contact release function, and the rotating member (recovering roller 43) which is positioned on the downstream side of the members, faces the image forming body 30, and recovers developer. In this constitution, when a solenoid S1 is turned off, a blade 41 and a shielding plate 42 come into press-contact with the periphery of the image forming body 30 via torsion springs 44 and 45 to peel residual toner; the toner is recovered by the roller 43 so that it does not leak out of the housing 40A. When the solenoid S1 is turned on, the blade 41 and the shielding plate 42 retreat from the periphery of the image forming body 30. Thus, efficient removal of the residual toner and cleaning can be performed even for an image forming body whose transfer part is in the upper part of the image forming body, and which rotates reversely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus in which an image transfer section is arranged horizontally above 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 fJ 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. A developing device that develops the electrostatic image on the drum with toner, a transfer device that transfers the toner image on the photosensitive drum to recording paper, etc. are installed around the photosensitive drum. The developing device in a photographic image forming apparatus consists of three or four developing devices each containing yellow (Y), magenta CM), cyan (C) toner, and sometimes black (BK) toner. While the drum rotates 3 or 4 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. When using such an image forming method, the color image forming apparatus can be made compact by making three or four developing units thin and arranging them close to each other.

Japanese Unexamined Patent Publication No. 61-55661 proposes a color image forming apparatus using such an image forming method, in which latent images are formed by three exposure devices corresponding to three developing devices, and a photoreceptor drum and The developing device and the cleaning means are integrated into a unit and can be taken out from the main body of the apparatus.

Further, Japanese Patent Application No. 62-320596 discloses a system in which one exposure device is used, and developing devices are placed one on top of the other, and the unit is made into a unit in the same manner and can be taken out from the main body of the device.

The above-mentioned Japanese Patent Application Laid-Open No. 61-55661 and Japanese Patent Application No. 1983-
Although the color image forming apparatus described in the specification of No. 320596 contributes to improved maintainability, it is easy for developer to spill or get mixed in when the unit is inserted or removed.

I: An example of a color image forming apparatus in which a toner image of each color is transferred onto a recording paper using a transfer drum, in which the area around the photosensitive drum is formed into a unit, is described in Japanese Patent Application Laid-open No. 72159/1982.

In this way, various color image forming methods have been developed for copying color images, each with its own special color, but each method requires an image forming body, a developing device, a cleaning device, etc., as described above. By storing the paper in one cartridge and making it into a unit, it is possible to simplify its handling and maintenance work such as jam removal.

On the other hand, looking at the layout of each of the above-mentioned equipment in a unitized cartridge, the developing unit group is arranged at the bottom of the drum-shaped image forming body, and therefore the image transfer section is configured at the top of the image forming body. An image forming apparatus with the following configuration can be considered.

With this type of device, the image is transferred to the lower surface of the transfer material, so there is less risk of it being smudged by falling toner, and a high-quality image can be provided. It is also possible to open the door, which has the advantage of further improving the workability of jam removal and maintenance.

[Problem that the invention seeks to solve]

However, when looking at the function of a cleaning device that cleans the residual toner on the image forming body after image transfer, conventional cleaning devices usually perform the cleaning function on the aspect of the image forming body that rotates from the bottom to the top. In contrast, in the image forming apparatus described above, the cleaning device is installed facing the circumferential surface of the image forming body that rotates from above to below. The problem remains that it is not possible to obtain a sufficient leaning effect with this function.

Particularly when the cleaning device is installed above the rotation axis of the image forming body, the removed residual toner may not fall naturally from the circumferential surface of the image forming body and may remain attached to it and be transported. In many cases, cleaning efficiency is significantly reduced.

As a result of solving this problem and improving the present invention, the present invention provides an image forming apparatus having a cleaning device that can efficiently remove and clean residual toner even when the image forming body rotates in the opposite direction to the normal case. This item is for the purpose of providing.

[Means for solving problems]

The above purpose is to provide an image forming body, a cleaning member having a pressure release function for the image forming body, and a rotating member located downstream of the cleaning member and facing the image forming body to collect developer. This is achieved by an image forming apparatus characterized by the following.

〔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 type structure divided into an upper casing 1 and an apparatus main body 2, and the upper casing 1 can be held at a predetermined open angle using a hinge IA connected to the apparatus main body 2 as a fulcrum. In the closed state, it is integrated with the main body 2 of the device by means of a stopper (not shown).

an image forming body 30 constituting an image forming section of the printer;
Developing units 36, 37, 38, 39 containing yellow, magenta, cyan, and black developers, cleaning device 4
0 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 are connected to the main body 2 of the apparatus via a guide member 4 provided on the bottom. The developing units 36 are removably housed inside, and especially in this embodiment, each of the developing units 36 described above is
, 37, 38, and 39 are integrally constructed, and arranged sequentially in parallel upwardly from the direction upstream of rotation so as to face the circumferential surface of the image forming body 30 below the image forming body 30.

That is, the process cartridge 3 is inserted and mounted in the depth direction of the apparatus main body 2 by holding the handle provided on the front side and being engaged with the guide member 4, and when pulled out toward the front, the engagement of the guide member 4 is released and the process cartridge 3 is inserted into the apparatus main body 2. However, since each developing unit is kept with its opening facing upward, there is no possibility of the developer leaking out and falling or getting mixed into other developing units. nothing 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. We have set up
The image forming body 30 is subjected to laser scanning by the laser writing system unit B from diagonally downward, and a color toner image formed on the circumferential surface thereof is superimposed and transferred to 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 color image forming apparatus shown in FIG. 1 is inputted as shown in FIG. 4(d)).

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 developer #36 loaded with yellow (Y) toner (developing medium) in 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 outputted from the signal processing section is inputted to the writing system unit b, and the second color signal is inputted to the writing system unit b. In the same manner, writing is performed on the drum surface to form a latent image.

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 each of these developing devices 36, 37, 38 and 39, and jumping development is performed using a two-component developer serving as a developing means to form an image with the substrate grounded. body 30
Development is now possible without contact.

The color image thus formed on the circumferential surface of the image forming body 300 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
28 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 conductive cloth is used as a base, and a high resistance layer or an insulating layer having an elastic body of 0.5 + no + thickness is provided on the outer periphery.

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. 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 phase 0 and is conveyed to the fixing device and fixed to the fixing roller 8.
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 details of each member constituting the cleaning device 40, and each member described below is shown in the housing 4.
The image forming body 30 is housed at 0A and rotates clockwise.
As shown in Fig. 1, it is installed diagonally in the upper right position.

4I is a blade which is a cleaning member that comes into pressure contact with the circumferential surface of the image forming body 30 to peel off the residual toner, and 42 is a shielding plate located upstream of the blade 41 with respect to the rotational direction of the image forming body 30. This is to prevent the toner peeled off by the blade 41 from scattering to the outside of the housing 40A.

Further, 43 is located below the blade 41 and
This is a collection roller that removes toner lumps on the screen that are generated when the image forming member 30 is brought into contact with and separated from the image forming member 30.

As is well known, the blade 41 is a plate-shaped member made of hard urethane rubber or the like, and is connected to a blade holder 41a.
An arm 4 held by the blade holder 41a and protruding from the blade holder 41a.
The torsion spring 44 that biases the image forming member 1b constantly biases the support shaft 41c in a counterclockwise direction using the support shaft 41c as a fulcrum.

The arm 41b of the holder 41a is provided protruding near the inner wall surface in the rearward direction of the housing 40A, and an elongated hole at the tip is engaged with a pin on the plunger of the solenoid Sl.

The shielding plate 42 is made of an elastic material such as mylar or rubber or a brush member having low hardness and some rigidity, and is held by a holder 42a and is constantly supported around a support shaft 42b by a torsion spring 45 that biases the holder 42a. It is biased counterclockwise, that is, it has the habit of pressing against the circumferential surface of the image forming body 30 with its tip, similar to the blade 41.

The holder 41a of the blade 41 has a projection P on its upper surface that can come into contact with the lower surface of the holder 42a of the shielding plate 42, and when the plunger is attracted by the operation of the solenoid Sl and the holder 41a rotates clockwise. During this process, the shielding plate 42 is pushed up by the blade 41 and moved by the contact of the protrusion P, so that the tips of the shielding plates 42 can be retracted from the surface of the image forming body 30 almost simultaneously.

The collection roller 43 is a roller formed by a sponge or a brush that can be switched between the same polarity as the residual toner or an electrically floating state and a different polarity or an electrically floating state by the bias power supply El, and is a roller that is formed around the image forming body 30. It is located at a position slightly spaced apart from the surface and is driven and rotated clockwise by the power system of the main body 2 of the device.

When cleaning the peripheral surface of the image forming body 30, the image forming body is de-charged in advance by a device consisting of a lamp 46 and a light guide section 47 installed at the upper part of the housing 40A, so that the residual toner is in a state where it is easy to peel off. be done.

The operation of pressing the blade 4l and the shielding plate 42 against the peripheral surface of the image forming body 30 and releasing the pressing is performed by turning OFF and ON the solenoid Sl.

In FIG. 2(a), the solenoid St is turned off at the start of cleaning and the plunger is in a free state, and the blade 41 is in a free state due to the action of the torsion spring 44.
shows a state in which the remaining toner is removed by pressing the surface of the image forming member 30.

In this case, since the holder 41a of the blade 4l retracts the protrusion P downward, the shielding plate 42 becomes free and rotates counterclockwise by the action of the torsion spring 45, similarly to the blade 4l. The tip is brought into pressure contact with the circumferential surface of the image forming body 30.

The tip of the shielding plate 42 is pressed into close contact with the peripheral surface of the image forming body 30 in a slidable state, so even if the residual toner peeled off by the blade is scattered, the shielding plate 42 Blocked housing 40A
leakage to the outside is prevented.

During the cleaning operation, the collection roller 43 is applied with a bias voltage of the same polarity as the residual toner or is electrically rotated seven times, and its rotation is also stopped.

In the state shown in FIG. 2(a), when the removal of the residual toner in the image area is completed by the rotating operation of the image forming body 30, the solenoid Sl is turned on and the blade 4l is rotated clockwise by the suction of the plunger. Then, as shown in FIG. 2(b), the tip thereof is retracted from the circumferential surface of the image forming body 30.

As the blade 41 rotates clockwise, the shielding plate 42 also rotates clockwise due to the abutment of the protrusion P, causing its tip to retreat from the circumferential surface of the image forming body 30 .

On the other hand, at the same time as the solenoid Sl is turned on, the bias voltage applied to the collection roller 43 is switched to one having a polarity different from that of the residual toner, and at the same time, driving rotation in the clockwise direction is started.

As a result, a moving electric field is formed around the outer periphery of the collection roller 43, and the residual toner lumps on the peripheral surface of the image forming body 30 generated when the blade 4l approaches and leaves the collection roller 43 are attracted and conveyed to the scraper. Remove shine housing 40A by 43a
It falls inside and is collected.

Application of a bias voltage having a polarity different from that of the residual toner to the collecting roller 43 and driving rotation are performed at least on the image forming member 30.
After the peripheral surface of the blade 4l passes between the pressure contact point of the blade 4l and the opposing point of the collection roller 43, the power source El
By switching, the bias voltage of the same polarity as the residual toner or the state of electrical rotation is returned again, and at the same time, the rotation is stopped.

Thus, by applying a bias of the same polarity to the collecting roller 43 or by rotating the collecting roller 43 and by retracting and separating the blade 41 and the shielding plate 42, the peripheral surface of the image forming member 30 is released from the cleaning action and a new one is generated. A state is reached in which a toner image can be formed by overlapping.

Regarding the collection row 243, if a structure is adopted in which it can be retracted to a position further away from the circumferential surface of the image forming body 30 after cleaning is completed, the polarity switching as described above will not be necessary, and a bias of a different polarity will always be applied. It is good as it is.

On the other hand, FIG. 3 shows an example in which the collecting roller is arranged in such a way that its position can be moved relative to the circumferential surface of the image forming body 30.

The collection roller 143 is held by the holder lOO and the holder 1
A torsion spring 102 that biases an arm 101 protruding from 00
Therefore, it is always urged counterclockwise about the support shaft 103 and has a tendency to approach the circumferential surface of the image forming body 30.

The arm 101 is protruded close to the inner wall surface in the rearward direction of the housing 40A, and a part of the arm 101 protrudes outside the housing 40A, and the long end thereof is engaged with a pin on the plunger of the solenoid S2.

The collecting roller 143 is constantly applied with a bias voltage different from the residual toner by the bias power source E2, but after the formation of a toner image on the circumferential surface of the image forming body 30 is started, the above-mentioned blade old and shielding roller 143 is The solenoid S2 is kept at O until the cleaning action by the plate 42 is completed.
In the N state, the holder 100 is rotated clockwise as shown in FIG.

After the image is transferred, the cleaning action by the blade 41 and the shielding plate 42 is started, and when it is finished, the solenoid Sl is turned on, and the blade 41 and the shielding plate 42 are moved from the circumferential surface of the image forming body 30. At the same time as the retraction, the solenoid S2 is turned OFF and the plunger is released from the suction state to the free state, so the holder 100 is rotated counterclockwise by the action of the torsion spring 102 until it comes into contact with the stopper 104, and thus the retrieval is completed. The roller 43 is moved to a position close to the circumferential surface of the image forming body 30.

As a result, the toner lumps on the circumferential surface produced by the contact and separation of the blade 41 are attracted and conveyed by a collection roller 143 to which a bias of a different polarity is applied, and are scraped off and dropped by a scraper 143 supported by the holder 100.

As biases of different polarities to be applied to the collecting rollers 43 and 143, a bias in which an AC component is superimposed on a DC component is more effective in promoting the movement of the residual toner.

FIG. 51i is one example of settings showing the positional relationships of the developing devices, charging and transfer electrodes, and the blades, shielding plate 42, and recovery roller 43 in the cleaning device 40 with respect to the image forming body 30. In this example, as shown in the time chart of FIG. 6, the image forming process by the printer is such that the residual toner on the image forming body 30 is absorbed by the collecting rollers 43 and 143 until the image forming body 30 completes five rotations. After completing the operation, one cycle of image copying is completed.

The residual toner removed by the cleaning device 140 passes through a toner transport pipe 71 installed on the front surface of the process cartridge 3 and is collected in a toner collection box 70 attached to the process cartridge 3.

A flexible toner conveying screw 72 that is rotated by the power system of the apparatus main body 2 is built into the toner conveying pipe 71, and residual toner is conveyed by the propulsive force generated by the rotation of the flexible toner conveying screw 72.

The toner conveying pipe 71 is made of a vibrator made of a synthetic resin material with high lubricity so as not to cause resistance to the operation of each toner conveying screw 72.

〔Effect of the invention〕

The present invention provides a cleaning device that can effectively remove and clean residual toner on an image forming body after image transfer for an image forming apparatus in which an image transfer portion is provided above the image forming body. As a result, an image forming apparatus with good image quality, easy handling and maintenance, and extremely effective for users has been realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the image forming apparatus of the present invention, FIGS. 2 and 3 are sectional views of the cleaning device of the apparatus, FIG. 4 is a block diagram of the image forming system, and FIG. 5 is the image forming apparatus. FIG. 6 is an explanatory diagram showing an example of arrangement of each equipment in FIG. 6, and FIG. 6 is a time chart of image formation according to the arrangement example. 3... Process cartridge 9... Pre-transfer charger 30... Image forming body 35.
...Charged! ! t 36, 37.38...
Developing device 40... Cleaning device 40A... Housing 41... Blade 42... Shielding plate 43.143... Collection roller 43a, I43a-
Scraper 70...toner collection box

Claims (2)

[Claims] (1) Consisting of an image forming body, a cleaning member having a pressure release function for the image forming body, and a rotating member located downstream of the cleaning member and facing the image forming body and collecting developer. An image forming apparatus characterized by: (2) The rotating member floats the rotating member when there is a toner image on the image forming body facing the rotating member, or applies a bias with the same polarity as the toner polarity, and when recovering the toner, the rotating member has a polarity different from the toner polarity. The image forming apparatus according to claim 1, wherein a bias is applied.