JPH04299360A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the damage and deterioration of a photosensitive face caused by the sticking of dust, paper powder, etc., and contamination by covering the exposing part of a photosensitive body except using time. CONSTITUTION:A flexible shielding member 32 capable of being moved by the winding of a motor m1, and a plate-like shielding member 36 capable of being moved by the winding of a motor m2, are installed on respective opening parts facing the transfer area and exposing area of the image of a photosensitive belt 1 housed in a color process cartridge 30, respectively, and the motor m1 is operated by feeding a transfer material to an image transfer region, while the motor m2 is operated by turning on the power source switch or copying switch of a device, so that the above-mentioned shielding members 32 and 36 are moved and retreated from respective opening parts, as a characteristic.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an electrophotographic image forming apparatus that forms images on transfer materials such as copying machines and printers, and more specifically, the present invention relates to an electrophotographic image forming apparatus that forms images on transfer materials such as copying machines and printers. The present invention relates to an image forming apparatus that can be attached and detached in the following state.

0002

2. Description of the Related Art Many methods and devices have been proposed for obtaining color images using electrophotography. For example, JP-A-6
As disclosed in Japanese Patent No. 1-100770, a latent image is formed and developed in accordance with the number of separated colors of the original image on a photosensitive drum serving as an image forming member, and is transferred onto a transfer drum each time the development is performed. There is a method in which a multicolor image is formed on a drum and then transferred onto a transfer material to obtain a color copy. In addition to the photoreceptor drum, the device using this method requires a transfer drum large enough to transfer one image onto its circumferential surface.
It is inevitable that the device will be large and have a complicated structure.

Furthermore, as disclosed in, for example, Japanese Patent Laid-Open No. 61-149972, a latent image is formed and developed on a photoreceptor drum according to the number of separated colors of an original image, and each time the development is performed, a latent image is formed on a transfer material. There is a method to obtain multicolor copies by transferring to With this method, it is difficult to overlap multicolor images with high precision, and it is impossible to obtain high-quality color copies.

[0004] Furthermore, formation of a latent image according to the number of separated colors of the original image on the photoreceptor drum and development with color toner are repeated, and the color toner images are superimposed on the photoreceptor drum and then transferred to obtain a color image. There is a way. The basic process of forming a multicolor image is disclosed in Japanese Patent Application Laid-open No. 60-7585 by the present applicant.
No. 0, No. 60-76766, No. 60-95456,
This is disclosed in Japanese Patent No. 60-95458, Japanese Patent No. 60-158475, and the like.

[0005] In a multicolor image forming apparatus that obtains a color image by superimposing color images as described above, 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 to develop the latent image on the photoreceptor drum to obtain a color image.

[0006] Such image forming apparatuses, especially in the case of color image forming apparatuses, have a plurality of developing devices and a plurality of corresponding toner replenishing devices, so the structure of the image forming section becomes complicated, and the process Inspect each material individually,
Replacement or replenishment work is extremely difficult.

Therefore, at least the photoreceptor and the cleaning member are integrated, or the photoreceptor, the developing device, the cleaning member, etc. are housed in an integrated cartridge and installed in the main body of the apparatus as a unit, and then the photoreceptor, the developing device, the cleaning member, etc. A structure is adopted in which the cartridge can be removed from the main body of the apparatus by a simple operation.

[0008]

[Problems to be Solved by the Invention] When such a cartridge is formed, the photoreceptor has a structure in which most of the photosensitive surface is shielded, but since the image exposure area and transfer area are exposed, Dust, paper powder, etc. may adhere to the photosensitive surface even when it is attached to the device, and if it is removed from the device, there is a risk that the photosensitive surface may be contaminated or damaged by touching it with hands or other objects.

[0009] As a result of solving this problem and improving the present invention,
The object of the present invention is to provide an image forming apparatus that protects the photosensitive surface by always shielding the exposure and transfer areas of the photosensitive member except when the image forming process is in operation.

0010

[Means for Solving the Problems] The above object is to provide an image forming apparatus equipped with a removable process cartridge containing at least an image bearing member and a cleaning member, in which the image forming process is limited to a predetermined period of image forming process operation of the apparatus. This is achieved by an image forming apparatus characterized in that a shielding member provided in an image transfer area of the image carrier is in an open state.

[0011]

[Embodiment] FIG. 1 shows a first embodiment of the image forming apparatus of the present invention.
5. As shown in FIG.

In FIG. 1, reference numeral 1 denotes a flexible photoreceptor belt serving as a belt-like image carrier. Transported clockwise.

Reference numeral 4 denotes a support member or guide member fixed to be inscribed in the photoreceptor belt 1, and the photoreceptor belt 1 is brought into a tensioned state by the outward biasing action of the rotary roller 3. The guide member 4 rubs the inner peripheral surface thereof.

Therefore, the photoreceptors on the outer circumferential surface of the photoreceptor belt 1 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. .

6 is a scorotron charger as a charging means; 7
8 to 1 are laser writing system units serving as image exposure means;
Reference numeral 1 denotes a plurality of developing means, that is, developing devices, each containing a developer of a specific color, and each of these image forming means is arranged opposite to the outer circumferential surface of the photoreceptor belt 1 with the guide member 4 as its back surface. will be established.

In addition to the optical system shown in the drawings, the laser writing system unit 7 may also include an optical system that integrates a light emitting section and a convergent light transmission body.

Each of the developing devices 8, 9, 10, and 11 accommodates, for example, yellow, magenta, cyan, and black developers, respectively, and includes developing sleeves that maintain a predetermined gap from the photoreceptor belt 1. It has a function of making the latent image on the photoreceptor belt 1 visible by 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 charge eliminating bar, and 13 is a cleaning section, that is, a cleaning device, which includes a blade 13A and a toner conveying roller 13.
B is maintained at a position apart from the surface of the photoreceptor belt 1 during image formation, and is pressed against the surface of the photoreceptor belt 1 as shown in the figure only during cleaning after image transfer.

The color image forming process 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 following image forming system. That is, data obtained by a color image data input section in which an image sensor scans an original image is subjected to arithmetic processing in an image data processing section to create image data, which is temporarily stored in an image memory. The image memory is then taken out during recording and input to a recording section, for example, 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 7, the color signal is generated by a semiconductor laser (not shown) in the laser writing system unit 7. The laser beam is transmitted to a polygon mirror 7 rotated by a drive motor 7A.
B, it is rotated and scanned by the mirror 7 via the fθ lens 7C.
The optical path is bent by D, 7E, and 7F, and the light is projected onto the circumferential surface of the photoreceptor belt 1, which has been charged in advance by the charger 6, which is a charging means, 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 photoreceptor belt 1. Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the photoreceptor belt 1 by main scanning by the laser beam and sub-scanning by the conveyance of the photoreceptor belt 1. This latent image is yellow (Y) in the developing means.
The toner (developing medium) is developed by the developing device 8 loaded with the toner (developing medium), and a toner image is formed 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 peripheral surface of the photoreceptor belt 1, and enters the next copy cycle.

That is, the photosensitive belt 1 is charged again by the charger 6, and then the second color signal outputted from the signal processing section is inputted to the writing system unit 7, and the above-mentioned first color signal Writing is performed on the belt surface in the same manner as in the case of , and a latent image is formed. The latent image is developed by a developer 9 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 10 has 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.

Furthermore, numeral 11 is a developing device having black toner, which forms a black toner image superimposed on the belt surface by the same process. These developing devices 8, 9, 1
Direct current or even alternating current bias is applied to each sleeve 0 and 11, and jumping development is performed using a two-component developer, which is a developing means, and non-contact development is performed on the photoreceptor belt 1 whose base is grounded. It is about to be done. Note that as the development, non-contact development using a one-component developer can also be used.

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

That is, the top layer of the transfer material stored in the paper feed cassette 14 is carried out by the rotation of the paper feed roller 16, and transferred to the photoreceptor belt 1 via the timing roller 17.
It is supplied to the transfer device 12 in synchronization with the above image formation.

The transfer material that has undergone image transfer and static electricity removal is reliably separated from the photoreceptor belt 1, which suddenly changes direction along the rotation roller 2, and is transported upward via the suction type conveyor belt 17A. After the image is fused by the fixing roller 18, the sheet is discharged via the discharge roller 19 onto a tray formed on the upper lid 20.

On the other hand, the photoreceptor belt 1, which has completed the transfer to the transfer material, continues to be conveyed, and the remaining toner is removed by the cleaning device 13 in which the blade 13A, which is a cleaning member, and the toner conveyance roller 13B are brought into pressure contact with each other. After waiting for the end of the process, the blade 13A is pulled away again, and a little later, the toner conveying roller 13B smoothes out the toner accumulated on the tip of the blade 13A.
The toner conveying roller 13B is separated and a new image forming process begins.

FIG. 6 shows a timing chart of the above process.

The photoreceptor belt 1 is shown in FIGS. 2 and 3 as a process material for image formation, together with a charger 6 and developing devices arranged opposite to each other on the lower periphery, and a cleaning device 13 arranged at the lateral end. It is incorporated into an independent color process cartridge 30 as shown, and is integrated and attached to and detached from the main body of the apparatus. The color process cartridge 30 is not necessarily limited to one that contains all of the process materials described above, and may be one in which at least the photoreceptor belt 1 and the cleaning device 13 are integrated.

The color process cartridge 30 further includes a developer replenishing section 30A on the side of the cleaning device 13.
Further, a waste toner cartridge 30B is built in integrally with the guide member 4, and the developer replenishing section 30A supplies toner to each developing device, while the waste toner cartridge 30B receives waste removed by cleaning. Each device has a function to collect toner.

The color process cartridge 30 is inserted into and removed from the main body of the apparatus in the following manner.

That is, as shown in FIG. 5 showing the AA cross section, inside the device, a pedestal 50 is provided which is slidably supported by engaging a pair of fixed guide rails 40 with legs 50A on the bottom surface. Then, the color process cartridge 30 is placed on the pedestal 50 and housed in the apparatus.

The pedestal 50 is integrally equipped with a rack plate 51 that meshes with the pinion P1 of the motor M1 on the apparatus main body side, and is mounted by tilting and sliding so as to have an inclined angle when viewed diagonally from the upper right direction by the rotation of the motor M1. be done.

In the color process cartridge 30, a set of guide members 31 each having an arcuate slit as shown in FIG. 2 is installed on the circumferential surface of the photoreceptor belt 1 facing the image transfer area.

The guide members 31 are located on both sides of the photosensitive belt 1 outside the image area, and a shielding member 32 covering the image area is housed between them along the photosensitive surface.

The shielding member 32 is a highly flexible flat thin plate made of a springy metal plate, and a pair of string members 33A and 33B (each shown with a dashed line) is attached to each end of the guide member. It is attached at a position where it can move within the slit formed by 31.

The other ends of the string members 33A and 33B are locked to respective rotating shafts 34A and 34B installed within the color process cartridge 30. The rotating shaft 34A is coaxially integrated with a gear G1 on the outer wall of the cartridge, and the gear G1 is further connected to a motor m1 having an electromagnetic clutch (not shown) interposed on the rotating shaft via an intermediate gear IG1. On the other hand, the rotation shaft 34B is supported by a torsion spring 35.
The shielding member 32 is urged and rotated clockwise by the shield member 33B, and the string member 33B is wound a plurality of times to maintain the shielding member 32 in a position that closes the image transfer area of the photoreceptor belt 1.

Furthermore, the color process cartridge 3
0 is a plate-shaped shielding member 36 on the inner surface of the exposure opening 30C.
is slidably housed.

A string member (shown with a dashed line) 37 is attached to one end of the shielding member 36 and has one end locked to a rotating shaft 38 installed in the cartridge, and the other end is attached to a string member 37 that is connected to an exposure area. Color process cartridge 3 outside
A pair of tension springs 39 are attached between the shield member 36 and the opening 30C, and the biasing force of the tension springs 39 keeps the shielding member 36 in a position where the opening 30C is closed.

The rotating shaft 38 is coaxially integrated with a gear G2 on the outer wall of the cartridge, and furthermore, the gear G2 is connected to an intermediate gear IG.
2 to a motor m2 having an electromagnetic clutch (not shown) interposed on the rotating shaft.

The motor m1 is operated only during a predetermined period of the image forming process, for example, when the photoreceptor belt 1 is in operation.

That is, when the photoreceptor belt 1 starts to convey and rotate by operating the copy switch provided in the operation section of the apparatus, the motor m1 starts operating and at the same time, the electromagnetic clutch on the rotating shaft is also turned on. The gear G1 is rotated clockwise a predetermined number of times and then automatically stopped. (Indicated by transfer section opening operation A in the timing chart of FIG. 6) As a result, the string member 33A is wound around the rotating shaft 34A against the biasing force of the torsion spring 35, and the shielding member 33A is wound up as shown in FIG. moves and retreats from the image transfer area of the photoreceptor belt 1, allowing the image to be transferred to the transfer material.

The electromagnetic clutch on the rotating shaft of the motor m1 is turned off when the conveying rotation of the photoreceptor belt 1 is stopped upon completion of a series of copying operations, thereby releasing the rotating shaft 34A.

Therefore, the shielding member 32 in the retracted position
is attached to the rotating shaft 34B by the bias of the torsion spring 35, returns to the position shown in FIG. 2, and closes off the image transfer area of the photoreceptor belt 1.

Furthermore, the motor m1 and the electromagnetic clutch on its rotating shaft can be operated only during the period of image transfer to the transfer material. (Indicated by transfer section opening operation B in the timing chart of FIG. 6) That is, when the timing roller 17 rotates and starts feeding the transfer material that is temporarily stopped, the timing roller 17 starts operating. In conjunction with this, the operation of the motor m1 is started, and at the same time, the electromagnetic clutch is turned on.

Operation of the motor m1 and O of the electromagnetic clutch
The N state is maintained for a period of time from when the timing roller 17 starts operating until the rear end of the largest transfer material used passes through the image transfer area, and then it is automatically stopped or returned to OFF, as shown in FIG. 2 again. The image transfer area of the photoreceptor belt 1 is then closed.

On the other hand, the motor m2 has its power switch turned OFF.
When switched to N, the electromagnetic clutch on the rotary shaft is also turned on, and the gear G2 is rotated counterclockwise a predetermined number of times, and then automatically stopped.

As a result, the string member 37 is wound around the rotating shaft 38 against the bias of the tension spring 39, and the shielding member 36 is used for exposure as shown in FIG. It moves and retreats from the opening 30C to enable the laser writing system unit 7 to expose the original image.

On the other hand, photosensors S1, S2, S3, etc. for detecting the passage of the transfer material are arranged at key points on the conveyance path of the transfer material, and the sensors located on the upstream side of each conveyance detect the passage of the transfer material. After the detection, if the downstream sensor cannot detect the transfer material even after a predetermined time has elapsed, a jam detection signal is output, and the occurrence of a jam in the transfer material is detected. Each of the detected signals mentioned above is input to the control section of the main body of the device,
It is output as a signal for controlling the rotation of the motor M1 and the motor M2, which will be described later.

When the jam detection signal is input, the motor M1 starts rotating in reverse, and the color process cartridge 3
0 is moved from the mounting position, that is, the first position where image formation is performed, to the second position where jam removal or toner replenishment or replacement is performed.

The reverse rotation operation of the motor M1 is stopped when the light shielding plate 52 on the top surface of the cartridge is detected by the photosensor S5.

The upper lid 20 is rotatably supported by the apparatus main body via a shaft 20A, and is opened by rotating counterclockwise to open the opening at the upper part of the apparatus main body.

That is, the upper lid 20 has a sector gear 21 integrated at its rotating base that meshes with the pinion P2 of the motor M2 on the apparatus main body side, and is rotated counterclockwise from the illustrated position by the rotation of the motor M2. held at a given angle.

In this state, the color process cartridge 3
The above-mentioned shielding members 32 and 36 provided at 0 are both placed in the shielding position, and operations such as removing jammed paper and replenishing toner are performed while protecting the photoreceptor belt 1.

The color process cartridge 30 is returned to the mounting position, that is, the first position, by operating a reset button provided on the operating section.

When the reset button is pressed, the motor M1 rotates in the forward direction to move the color process cartridge 30 from the position shown in FIG. 4 to the position shown in FIG. 1 again, and the light shielding plate 52 is detected by the photosensor S4. The machine will stop at the specified position.

[0060] In synchronization with this, the motor M2 also starts rotating in the normal direction, and the upper cover 20 is rotated clockwise to close the opening at the upper part of the main body of the apparatus.

Note that even when the color process cartridge 30 is not installed, that is, when it is removed from the apparatus, the shielding members 32 and 36 are maintained at the closed position as in the case where they are at the second position.

[0062]

[Effects of the Invention] According to the present invention, the photoreceptor is effectively prevented from adhering to dust and dirt, and its lifespan is significantly improved.
As a result, an image forming apparatus that can use a photoreceptor for a long period of time and that can always record high-quality images has been provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus of the present invention.

FIG. 2 is a cross-sectional configuration diagram of a process cartridge of the apparatus.

FIG. 3 is a cross-sectional configuration diagram of a process cartridge of the apparatus.

FIG. 4 is a cross-sectional configuration diagram of essential parts of the device.

FIG. 5 is a sectional view of essential parts of the device.

FIG. 6 is a timing chart diagram showing the operation of the present invention.

[Explanation of symbols]

1...Photoreceptor belt
2...Rotating roller 12...Transfer device
13...Cleaning device 17...Timing roller
30...Color process cartridge 30C...Opening part
31...Guide member 32, 36...Shielding member
33A, 33B,
37... String members 34A, 34B, 38... Rotation shaft
35...Torsion spring 39...Tension spring
M1, M2, m1,
m2...Motor G1, G2...Gear

Claims (3)

[Claims] 1. An image forming apparatus comprising a removable process cartridge containing at least an image bearing member and a cleaning member, wherein the image transfer area of the image bearing member is limited to a predetermined period of image forming process operation of the apparatus. An image forming apparatus characterized in that a shielding member provided in the image forming apparatus is in an open state. 2. Claim 1, wherein the predetermined period of the image forming process operation is an operation period of the image carrier.
image forming device. 3. The image forming apparatus according to claim 1, wherein the predetermined period of the image forming process operation is an image transfer period.