JPH03149577A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain the image of high quality even in the case of using a photosensitive belt whose end parts overlap each other by making a gap between the developer layer of a developing device and a belt-like image forming body thicker than the belt thickness of the image forming body. CONSTITUTION:The gap D between the developer layer of the developing device and the belt-like image forming body 1 is made to be thicker than the belt thickness (t) of the belt-like image forming body 1. The leading end part E1 of the belt is connected to the trailing end part E2 of the belt by performing ultrasonic welding while overlapping each other with the extent of 0.3 - 3mm, or so from the inside of a ring in the moving direction of the photosensitive belt 1, that means, in the direction shown by an arrow A. The value of the gap D is made to be equal to or exceeding twice as much as the thickness (t), if possible, therefore, toner and carrier are surely prevented from adhering on a level difference part which is formed by overlapping the leading end part E1 with the trailing end part E2 of the photosensitive belt 1. Thus, the image of high quality can be obtained even in the case of using the belt-like image forming body whose end parts are stuck together.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an image in which a toner image is formed on a belt-like image forming member by electrophotography and transferred onto a transfer material to obtain an image. The present invention relates to a forming device.

(Background of the invention) There are many methods and techniques for obtaining a single color image using electrophotography.
A device has been proposed. For example, JP-A-61-10077
As disclosed in Publication No. 0, a latent image is formed and developed in accordance with the number of separated colors of an original image on a photoreceptor drum serving as an image forming member, and is transferred onto a transfer drum each time the development is performed. There is a method of forming a multicolor image on a paper and then transferring it onto recording paper to obtain a color copy. A device using this method requires a transfer drum large enough to transfer one sheet of image onto its circumferential surface in addition to the photoreceptor drum, and the device does not have a large and complicated structure. In addition, as disclosed in JP-A-61-149972, for example, a latent image is formed and developed on a photoreceptor drum according to the number of separated colors of the original image, and each time the development is performed, a latent image is formed on the transfer material. This is a method to obtain a multicolor copy by transferring the image to a computer. With this method, it is difficult to overlap multicolor images with high precision, and it is impossible to obtain high-quality color copies.

Another method is to repeatedly form a latent image on a photoreceptor drum according to the number of separated colors of the original image and develop it with color toner, and then overlap the color toner images on the photoreceptor drum and transfer them to obtain a single color image. be. The basic process for forming a multicolor image is disclosed in Japanese Patent Application Laid-Open No. 60-75850 and No. 60-7585 by the present applicant.
No. 76766, No. 60-95456, No. 60-954
No. 58, No. 60-158475, and the like.

In a multicolor image forming apparatus that obtains a single color image by such superimposition, a plurality of developing units containing different color toners are arranged around the periphery of the photoreceptor drum. Generally, the photoreceptor drum is rotated multiple times and the latent image on the photoreceptor drum is developed by a non-contact development method to obtain a single color image.

Regarding image forming bodies, as explained above, there are photosensitive drums in which a photoconductor is coated or deposited on the drum surface, as well as belt-shaped image forming bodies in which a photoconductor is coated or mounted on a flexible belt. Proposed. Since the shape of the belt-shaped image forming body (hereinafter also referred to as a photoconductor belt) is determined by stretching it between rotating rollers including a drive roller, this color image forming apparatus is compact in size and makes effective use of space. It is effective when configuring . Also, since the photoreceptor belt can run along a small curvature,
By using a rotating roller with a small diameter and separating the transfer material using this curvature, it is also possible to prevent poor separation of the transfer material.

[Purpose of the invention]

Such a photoreceptor belt is a thin sheet-like photoreceptor with a conductive layer sandwiched between a substrate and an organic photosensitive layer, and because it is used in an endless form, the ends are overlapped and ultrasonic bonded. A ring-shaped one is used.

Therefore, it is unavoidable that a step corresponding to the thickness of the photoreceptor occurs at the adhesive part, and even with non-contact development, the toner in the developer will adhere to the step unnecessarily, so in the case of a single color image, other development is necessary. This results in color mixing inside the device, and if the carrier adheres, the photoreceptor may be damaged during cleaning.

As a result of solving this problem and improving the present invention, it is an object of the present invention to provide an image forming apparatus that can obtain high-quality images without adhering unnecessary toner or carrier even by using a photoreceptor belt whose ends are overlapped. This is the purpose.

[Structure of the invention]

The above object is to stretch a belt-like image forming body with the ends of the belt stuck together vertically between a plurality of rotating rollers, and to provide a developing device that performs non-contact development on the peripheral edge of the belt-like image forming body. This is achieved by an image forming apparatus characterized in that the gap (D) between the developer layer of the developing device and the belt-like image forming member is larger than the belt thickness (1) of the belt-like image forming member. be done.

〔Example〕

An embodiment of the color image forming apparatus of the present invention is shown in FIGS. 1 to 4.

In FIG. 1, reference numeral 1 denotes a flexible photoreceptor belt that is a belt-like image forming member, and the photoreceptor belt 1 is located between a rotating roller 2 made of a rubber roller and a rotating opening/roller 3 made of a metal roller. The paper is suspended and is conveyed clockwise by the rotation roller 2.

Reference numeral 4 denotes a guide member inscribed in the photoreceptor belt l-1, and the photoreceptor belt l is brought into a tensioned state by the action of the tensicon roller 5 which is urged outward, so that its inner circumferential surface is kept under tension. The guide member 4 is rubbed.

Therefore, the photoreceptors on the outer circumferential surface of the photoreceptor belt l are always maintained at a constant position relative to the surface of the guide member 4 even during conveyance, making it possible to form a stable image forming surface.

Reference numeral 6 denotes a sufutotron charger as a charging means, 7 a laser writing system unit as an image exposure means, and 8 to 11 a developing device as a plurality of developing means each containing a developer of a specific color. The forming means is arranged at a position facing the guide member 4 of the photoreceptor belt l. In order to maintain a gap without interfering with the movement of the photoreceptor belt 1, the guide member 4 is brought into contact with the guide member 4 on the outside of the photoreceptor belt 1 with a gap maintaining means.

In addition to the optical system shown in the drawings, the laser writing system unit may also include an optical system that integrates a light emitting section and a convergent light transmission body.

The respective developing units 8,9,10,11 are yellow, for example.

The developing sleeves 8A, 9A, IOA, and LLA each contain magenta, cyan, and black developers and maintain a predetermined gap with the photoreceptor belt l, and the latent image on the photoreceptor belt l. It has the function of visualizing images using a non-contact development method. Unlike contact development, this non-contact development has the advantage of not interfering with the movement of the photoreceptor belt.

12 is a transfer device; 12A is a static elimination bar; 13 is a cleaning device serving as a cleaning means;
The blade 13A and the toner collection roller 13B of No. 3 are kept at a position apart from the surface of the photoreceptor belt 1 during image formation, and are brought into pressure contact with the surface of the photoreceptor belt 1 as shown in the figure only during cleaning after image transfer.

The process of forming a color image by the color image forming apparatus 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. In other words, a color image data input section (Fig. 2 (a)) where an image sensor scans an original image.
) is subjected to arithmetic processing in an image data processing section (FIG. 2 (b)) to create image data, which is temporarily stored in an image memory (FIG. 2 (c)). Then, the image memory is taken out at the time of recording and sent to the recording section (FIG. 2 (d)).
For example, the image is inputted to the color image forming apparatus shown in the embodiment of 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, a laser beam generated by a semiconductor laser (not shown) is driven in the laser writing system unit. The periphery of the photoreceptor belt l is rotated and scanned by a polygon mirror 7B rotated by a motor 7A, passes through an fθ lens 7C, and is deflected along the optical path by mirrors 7D and 7E. It is projected onto the surface and forms an emission 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 photoreceptor belt l. Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the photoreceptor belt l by the main scanning by the laser beam and the sub-scanning by the conveyance of the photoreceptor belt l. The developing device 8 loaded with the (Y) toner (developing medium) performs reversal development in a non-contact state to form a toner image on the belt surface. The obtained toner image, while being held on the belt surface, passes under a cleaning device 13, which is a cleaning means, which is separated from the circumferential surface of the photoreceptor belt 1, and enters the next copy cycle.

That is, the photoreceptor belt l is charged again by the charger 6, and then the second color signal output from the signal processing section is input to the writing system unit, and is processed in the same manner as in the case of the first color signal described above. Writing is then performed on the drum surface to form a latent image. The latent image is reversely developed in a non-contact manner by a developing device 9 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.

IO is a developing device having cyan (C) toner, and forms a cyan (C) toner image on the belt surface based on a control signal generated by a signal processing section.

Further, numeral 11 denotes a developing device having black toner, which forms a black toner image superimposed on the drum surface by the same process. Direct current or even alternating current bias is applied to the sleeves of these developing devices 8°9, IO, and 11, and jumping development is performed using l-component or two-component developer, which is the developing means, and the substrate is grounded. Reversal development is performed on the photoreceptor bell l-1 in a non-contact manner.

The color toner image thus formed on the circumferential surface of the photoreceptor belt 1 is transferred to a transfer material fed through a paper feed guide 15 from a paper feed roller 14 at a transfer section.

- That is, the top layer of the transfer material stored in the paper feed force set 14 is carried out by the rotation of the paper feed roller 16, and is transferred via the timing roller 17 in synchronization with the image formation on the photoreceptor belt l. 12° is supplied to the static eliminating bar 12A.

The transfer material that has undergone image transfer and charge removal is reliably separated from the photoreceptor belt l, which suddenly changes direction along the rotating roller 2, without being affected by image quality such as toner scattering due to the charge removal effect. After the image is fused by the fixing roller 18, the sheet is discharged onto the tray 20 via the discharge roller 19.

On the other hand, the photoconductor bell (1) which has completed the transfer to the transfer material is further controlled by a blade 13A facing the rotating roller 3 and a toner collection roller 13B consisting of a rotating sponge member.
The remaining toner is removed in the cleaning device 13 which is in the pressure contact state, and after the completion of the cleaning, the blade 13A is separated again, and a little later, the toner collection roller 13B is separated and a new image forming process begins.

The photoreceptor belt l is made of PET with a thickness of 30 to 100 μI.
(Polyethylene tereftate) is used as the base IA, and OPCIIIC is coated with a thickness of 10 to 30 μm consisting of a charge generation layer and a charge transfer layer as a photoreceptor layer with a conductive layer IB sandwiched thereon, and the total thickness is 0.1 mm. The front and rear photoreceptor sheets are cut into a specific shape and their ends are pasted together to form a ring.
The Pc layer 1c is stretched in a state facing outward and is circulated and conveyed in the direction of arrow A in an endless form.

With respect to the moving direction of the photoreceptor belt l, that is, the direction of arrow A, the belt leading end sEl overlaps the belt rear end E2 within a range of about 0.3 to 3i+m from the inside of the ring, and is connected by ultrasonic bonding. .

On the other hand, each of the above-mentioned developing units has the following structure.

FIG. 3(A) shows a cross section of the developing device 9, and 9A shows the cross section of the developing device 9.
By bringing abutting rollers 9B provided on both sides of the developing sleeve containing a fixed magnet roller into contact with the guide member 4, a predetermined developing distance is maintained between the rollers 9B and the surface of the photoreceptor belt l. It is driven and rotated clockwise. 9C
The developing sleeve 9 is a thin layer forming member having rigidity and magnetism.
It is pressed against A with a predetermined load without the presence of developer. 9D and 9E have a screw structure,
These screws are a pair of toner conveying screws that convey and circulate the developer in mutually opposite directions, and function to send the toner and carrier sufficiently stirred and mixed as a developer to the developing sleeve 9A.

The toner transport screw 9D and the toner transport screw 9E are members that also serve as stirring members that rotate in opposite directions, and the toner and carrier transported to the back side by the thrust of the toner transport screw 9D are transferred to the toner transport screw 9E side. The developer is transported to the front side of the drawing by the thrust, and is triboelectrically charged by the mixing action of the toner and carrier during that time, becoming a homogeneous developer.
It adheres in a layer on the circumferential surface of the developing screw 9A.

This layer of developer adhering to the circumferential surface of the developing sleeve 9A becomes a thin layer in the process of passing through the thin layer forming member 90, and forms a thin layer around the circumferential surface of the photoreceptor belt l that is conveyed clockwise in the developing area. The latent image on the surface is reversely developed in a non-contact manner with a long development interval to form a toner image.

During this non-contact development, a developing bias containing an AC component in addition to a DC component is applied to the developing sleeve 9A from a power source (not shown).
is applied, and only the toner in the developer is selectively transferred and adhered to the surface of the latent image on the image sleeve 9A.

The developer whose toner components have been consumed has a higher carrier ratio and is transported by the developing sleeve 9A to the scraper 9F.
The toner is peeled off and collected, and a developer with a high toner ratio is mixed again.

FIG. 3(B) shows a cross section taken along arrow AA of the developing device 9 of FIG. 3(A). In FIG. 3(B), 9A is a developing sleeve of the developing device 9, and 9B is an abutting roller as an abutting member. The bearings are supported.

When the abutting roller 9B is pressed against the guide portion 4, a gap corresponding to a developing interval of 0.2 to 1.0 m is created between the circumferential surface of the developing sleeve 9A and the outer circumferential surface of the photoreceptor belt l. The developing sleeve 9A has an outer diameter slightly larger than that of the developing sleeve 9A.

As shown in FIG. 4, the developing sleeve 9A has a developer layer on the circumferential surface formed by the thin layer forming member 9C that has a thickness t of the photoreceptor belt l with respect to the image forming surface of the photoreceptor belt l.
The positions of the abutting rollers 9B are set by abutting against the guide member 4 so that they face each other with a larger gap therebetween.

Thereby, the developing sleeve 9A can transport the developer layer on the circumferential surface without contacting the stepped portion formed by overlapping the photoreceptor belts 1. That is, since the thickness of the photoreceptor belt is usually around lOOp-, the developing gap is set to have a gap of 100 mm or more.

Furthermore, it is desirable that the value of the gap be at least twice the thickness t if possible, so that toner and carrier may adhere to the stepped portion caused by the overlapping of the leading and trailing ends El and E2 of the photoreceptor belt L. is more reliably prevented.

Further, in order to perform development with a large development interval, it is preferable that the development bias has an AC component in addition to a DC component to improve the development performance.

When passing through the developing area of the stepped portion, the developing sleeve is stopped and the developing bias applied to the developing sleeve 9A is switched to only a DC component or is made floating, thereby reducing the developing ability itself. It becomes possible to more effectively prevent adhesion of toner and carrier.

Note that the edge of the rear end fiE2 of the belt is chamfered diagonally, and the conductive layer exposed at the chamfer is sealed with a high-resistance sealing material.

In this way, the developing sleeve 9A forms a constant developing interval suitable for non-contact development between the developing sleeve 9A and the outer peripheral surface of the photoreceptor belt 1, and the developing device 9 can always perform proper developing processing. The same applies to the other developing devices 8 and 10.11, and the abutting rollers built into each are pressed against the guide member 4 by a well-known biasing mechanism, so that development is performed in a stable state.

〔Effect of the invention〕

According to the present invention, a developing device can be set to maintain an appropriate development interval between the belt-shaped image forming body and the photosensitive surface without causing toner or carrier to adhere to the stepped portion created by bonding the ends of the belt-shaped image forming body. As a result, a single color image forming apparatus is provided which can obtain high quality images even when using a belt-shaped image forming body manufactured by simple manufacturing means.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus according to the present invention, FIG. 2 is a block diagram showing an image forming system, and FIGS. 3 and 4 are a cross-sectional view of a developing unit of the apparatus and views of its essential parts. l...Photoreceptor belt 4...Guide member 6...
・Charger 7...Laser writing system unit 8.9. IO, 11...Developing device aA, 9A, IOA, IIA-...Developing sleeve 9B...Abutment roller 9c...Thin layer forming member 9D, 9E...Toner conveying screw 9F... Scraper 12 -- Transfer device 13 -- Cleaning device El -- Belt tip E2 -- Belt rear end

Claims (3)

[Claims] (1) A belt-like image-forming body with belt ends stuck together vertically is stretched between a plurality of rotating rollers, and a developing device for non-contact development is provided at the peripheral edge of the belt-like image-forming body. In an image forming apparatus, the gap (D) between the developer layer of the developing device and the belt-like image forming member is determined by the belt thickness (D) of the belt-like image forming member.
t) An image forming apparatus characterized by being larger than t). (2) The image forming apparatus according to claim 1, wherein the developing device is a developing device using a two-component developer. (3) a gap (D) between the developer layer and the belt-like image forming body;
3. The image forming apparatus according to claim 1, wherein D>2t between the belt thickness (t) and the belt thickness (t).