JPH02267581A - Image forming device - Google Patents

Abstract

PURPOSE:To effectively eliminate residual toner, to heighten image quality and to facilitate an operation and a maintenance work by mounting a developer recovering member on the up-stream side of a cleaning member. CONSTITUTION:When a solenoid S1 is in an off condition, a cleaning blade 41 is in a press-contact state and a bias voltage in opposite polarity to the residual toner is impressed on a recovering roller 42. Toner powder which is peeled off by the blade 41 and sprashed due to a mobile electric field caused by the impression is absorbed on the periphery of the recovering roller 42, scraped away by a scraper 42a and dropped into a housing 40 A by the clockwise turning operation of the recovering roller. Then the lump of the residual toner generated when the blade 41 is retreated from the periphery of an image forming body 30 is dragged up by the leading part of an elastic thin plate 43 in a press-contact state and removed.

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 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 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. 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 lasers corresponding to three developing devices, and the photosensitive drum and developing device are connected to each other. The container and the cleaning means are integrated into a unit and can be taken out from the main body of the device.

Further, Japanese Patent Application No. 62-320596 discloses a system in which one exposure device is used, and the developing devices are arranged one on top of the other, and the unit is made into a unit in the same way, 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.

Furthermore, Japanese Patent Application Laid-Open No. 72159/1983 describes an example in which the area around the photosensitive drum is formed into a unit in a color image forming apparatus that uses a transfer drum to transfer each color toner image to a recording paper.

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 device group is arranged below the drum-shaped image forming body, and therefore the image transfer section is configured above the image forming body. An image forming apparatus that is configured as follows is conceivable.

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 often does not fall naturally from the surface of the image forming body and is transported while remaining attached. 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. It is intended for the purpose of providing.

[Means for solving problems]

The above object is made up of an image forming body, a cleaning member having a pressure release function for the image forming body, and a rotating member located upstream 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 5.

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 IA 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 47 are housed in the integrated process cartridge 3 to form a unit, and a guide member 4 provided on the bottom
Particularly in this embodiment, each of the above-mentioned developing units 36,
The housings 37, 38, and 39 are integrally constructed and are arranged in order downwardly of the image forming body 30 and facing upward from the rotational upstream direction 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 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 transferred to the process cartridge 3.
Since the toner is conveyed horizontally on the upper part of the toner and the transfer surface faces downward, even if the toner spills or scatters from the cleaning device 40 or the like, it will not stain the image surface.

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. 3 (a)) where the image sensor scans the original image.
) is processed by an image data processing unit equipped with a computer (third factor (b)) to create image data, which is then stored in the image memory (Figure 3 (c)). Stored. Then, the image memory is taken out during recording and stored in the recording section (
For example, as shown in the embodiment of FIG. 1, t:
The image is input to a color image forming apparatus.

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 34C and to which a charge is applied in advance by a charger 35 serving as a charging means.
It is projected onto the zero circumferential surface and forms 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 (II image medium) of the developing means, and a toner image is formed on the drum surface. The obtained toner image is held on the drum surface and passes under a cleaning device 40, which is a cleaning means, which is separated from the peripheral surface of the image forming body 30, 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 (H), and in the case of the first color signal described above. Writing is performed on the drum surface in the same manner as described above, 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 (CM) 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 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, this multicolor toner image is charged by the pre-transfer charger 9 to be easily transferred; after that, 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, The image is transferred to a recording sheet fed from a paper cassette C via a paper feed roller 12 and a timing roller 13 in synchronization with image formation.

The transfer belt 50 is stretched between rollers 59 and 60,
The a-roller 60 is rotated in synchronization with the peripheral speed I 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 as indicated by the dashed line by the power of a solenoid or the like that operates at the timing of , that is, to a position where the transfer belt 50 is brought into pressure contact with the circumferential surface of the image forming body 300 .

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 rotation of 0 and conveyed to the fixing device, and 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 3o from which the transfer material has been separated is cleaned by removing residual toner by the cleaning device 4o 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 at the upper right position with respect to the circumferential surface.

A blade 41 is a cleaning member that presses against the surface of the image forming body 30 to remove residual toner therefrom, and a toner 42 is a rotating member located upstream of the blade 41 with respect to the rotational direction of the image forming body 30. This collection roller is used 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 an elastic thin plate that removes toner lumps on the screen that are generated when the toner is moved toward and away from the image forming body 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 41 held by the blade holder old a and protruding from the blade holder old a
The torsion spring 44 that biases b is always biased counterclockwise around the support shaft 41c, that is, the tip thereof has the habit of pressing against the surface of the image forming body 30.

The arm 41b of the holder 41a is connected to the housing 40A.
It protrudes near the inner wall surface in the back direction of the solenoid st, and its long tip is engaged with the pin on the plunger of the solenoid st.

The collection roller 42 is a roller formed by a sponge or brush that can be electrically switched between the polarity of the residual toner and the polarity different from that of the residual toner by a bias power source E, and is positioned slightly away from the surface of the image forming body 30. It is driven and rotated clockwise by the power system of the device main body 2.

On the other hand, the thin elastic plate 43 is made of an elastic material such as Mylar, which has low hardness and some rigidity.
A torsion spring 45 that biases an arm 43b that is gripped by a blade and protrudes from the holder 43a always biases the arm 43b counterclockwise around the support shaft 43c, that is, the tip of the arm 43b is used as a fulcrum to rotate the arm 43b around the image forming body 30. It has been given the habit of pressing surfaces together.

Arm 43b of holder 43a in elastic thin plate 43
Similarly to the arm 41b of the blade 41, the arm 41b is provided protruding near the inner wall surface in the rear direction of the housing 40A, and a part thereof protrudes outside the housing 40A, and the elongated hole at the tip is connected to the pin on the plunger of the solenoid S2. engaged.

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 41 and the elastic thin plate 43 against the circumferential surface of the image forming body 30 and releasing the pressing is performed by turning OFF and ON the solenoids S1 and S2, respectively.

In FIG. 2(a), the solenoid Sl is turned off and the plunger is in a free state due to the start of cleaning, and the blade 4l is in a free state due to the action of the torsion spring 44.
shows a state in which the peripheral surface of the image forming member 30 is pressed against the surface of the image forming member 30 and the residual toner is peeled off.

Further, when the solenoid Sl is OFF, that is, while the blade 4l is in pressure contact, a bias voltage having a polarity different from that of the residual toner is applied to the collecting roller 42, and the toner is peeled off and scattered by the blade 4l due to the moving electric field formed thereby. The powder is sucked onto the surface of the collection roller 42, and by rotating clockwise, it is scraped off by the scraper 42a and dropped into the housing 40A.

During this cleaning operation, solenoid S2 is turned on.
In this state, the plunger is attracted and the elastic thin plate 43 is placed in a position retracted from the circumferential surface of the image forming body 30.

In the state shown in FIG. 2(a), when the removal of the residual toner in the image area is completed by the rotation of the image forming body 3o, the solenoid S1 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 is retracted from the surface of the image forming body 3o. At the same time, the recovery roller 42 is switched to a bias voltage of the same polarity or a 7 rotation state. Its rotation may also be stopped.

Also, at the same time as solenoid SL turns ON, solenoid S2 turns OFF.
When the FF is set and the plunger becomes free, the torsion spring 4
5, the elastic thin plate 43 rotates counterclockwise to bring its tip into pressure contact with the circumferential surface of the image forming body 3o.

The elastic thin plate 43 is in pressure contact with at least the image forming member 30.
After this phase passes between the pressure contact points of the blade 4l and the elastic thin plate 43 and is maintained for the end time, the solenoid S2 is turned on to return to the retracted position.

Therefore, a lump of residual toner generated when the blade 4l retreats from the circumferential surface of the image forming body 3o is scooped up and removed by the tip of the elastic thin plate 43 that is in pressure contact. If cleaning is not complete at a position on the image forming body where there is a lump of residual toner, it is preferable to avoid that position and perform the next toner image formation.

Thus, by applying a bias of the same polarity to the collection roller 42 or making it floating, and by the retracting and separating action of the blade 411 and the elastic thin plate 43, the surface of the image forming body 30 is released from the cleaning action, and a new toner image is formed by superposition. becomes possible.

Regarding the collection roller 42, if a structure is adopted in which it can be retracted to a position further away from the surface of the image forming body 3o 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. Good condition. Further, as the aforementioned bias, a bias in which an AC component is superimposed on a DC component is effective in promoting the movement of residual toner.

Alternatively, the collection roller 42 may be arranged close to the tip of the blade 41 so that the toner scraped by the blade is directly collected by the collection roller 42. By doing so, the amount of toner that accumulates at the tip of the blade 41 can be significantly reduced.

FIG. 4 shows each developing device, each charging and transfer electrode, and the blade 41 in the cleaning device 40.
．． This is one setting example showing the respective positional relationships of the collection roller 42 and the elastic thin plate 43 with respect to the image forming body 30. In this example, the image forming process by the printer is performed as shown in the time chart of FIG. By the end of five rotations, the pressing operation of the elastic thin plate 43 against the image forming body 30 is completed, and one cycle of image copying is completed. Furthermore, in order to avoid the effect on the image when the cleaning member is crimped,
It is preferable to start pressing the cleaning member after the fourth image exposure.

The residual toner removed by the cleaning device 40 is collected in a toner collection box 70 attached to the process cartridge 3 via a toner transport pipe 71 installed on the front surface of 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.

Note that the toner conveying pipe 71 is a pipe member molded from a synthetic resin material with high lubricity so as not to provide 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 extremely useful image forming apparatus for users, which has good image quality and is easy to handle and maintain, has been realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the image forming apparatus of the present invention, FIG. 2 is a sectional view of the cleaning device of the apparatus, the third factor is a block diagram of the image forming system, and FIG. 4 is a diagram of each equipment in the image forming apparatus. An explanatory diagram showing an arrangement example, and FIG. 5 is a time chart of image formation according to the arrangement example. 3... Process cartridge 9... Pre-transfer charger 30... Image forming body 35.
- Charger 36.37.38...Developer 40...Cleaning device 40A...Housing 41...Blade 42...Collection roller 4
2a... Scraper 43... Elastic thin plate 70.
...Toner collection box E...Power supply Sl, S2...Solenoid (b)

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 upstream of the cleaning member and facing the image forming body to collect 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 having 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.