JP2808323B2 - Color image forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color image in which a toner image is formed on a belt-shaped image forming body by an electrophotographic method and transferred to a transfer material to obtain an image. The present invention relates to a forming apparatus.

[Background of the Invention]

Many methods and apparatuses have been proposed for obtaining a color image using electrophotography. For example, as disclosed in JP-A-61-100770, a latent image is formed and developed on a photosensitive drum as an image forming body according to the number of separation colors of a document image,
There is a method in which a multicolor image is formed on a transfer drum by transferring the image on a transfer drum each time development is performed and then transferred onto a recording paper to obtain a color copy. In the apparatus according to this method, it is necessary to provide a transfer drum having a size capable of transferring an image of another one of the photosensitive drums onto the peripheral surface thereof, and the apparatus has a large and complicated structure. Inevitable.

Further, as disclosed in, for example, JP-A-61-149972, a latent image is formed and developed on a photosensitive drum in accordance with the number of separated colors of an original image, and is transferred onto a transfer material each time development is performed. This is a method of obtaining a multi-color copy. In this method, it is difficult to accurately superimpose multi-color images, and a high-quality color copy cannot be obtained.

In addition, there is a method in which a latent image is formed on the photosensitive drum in accordance with the number of separated colors of the original image and development with color toner is repeated, and a color image is obtained by superimposing and transferring a color toner image on the photosensitive drum. The basic process of this multicolor image formation is described in JP-A-60-75850 and JP-A-60-75766 by the present applicant.
Nos. 60-95456, 60-95458, 60-158475 and the like.

In a multi-color image forming apparatus that obtains a color image by such superposition, a plurality of developing devices that store color toners of different colors are arranged on the periphery of the photosensitive drum. Rotates the photoconductor drum several times,
The color image is obtained by developing the latent image on the photosensitive drum.

As for the image forming body, a belt-shaped image forming body in which a photoconductor is applied or mounted on a flexible belt together with a photosensitive drum having a photoconductor applied or deposited on the drum peripheral surface as described above. Has also been proposed. The shape of a belt-shaped image forming body (hereinafter also referred to as a photoreceptor belt) is determined by being stretched between rotating rollers including a driving roller.
This is effective when a compact color image forming apparatus is configured by effectively utilizing the space. In addition, since the photoreceptor belt can travel along a small curvature, the transfer material can be separated by using a small-diameter rotating roller and utilizing the curvature portion, thereby preventing transfer material separation failure and the like. it can.

On the other hand, there is an image forming apparatus in which the inside is opened or a process unit is taken out of the apparatus main body in the form of a cartridge for the purpose of clearing a jam or exchanging or cleaning a member. When such devices / members are opened or removed, the exposed members may be damaged or dust may adhere thereto. It has been proposed to provide a protective cover from such a place. For example, JP-A-59-34546 proposes a protective cover for an exposed portion, and JP-A-59-61865 proposes a protective cover for protecting a photoreceptor in a transfer portion. Is a proposal for a protective cover for the developing section.

[Object of the invention]

In the color image forming apparatus using the photoreceptor belt, each of the image forming units such as a charging unit, an image exposing unit, and a plurality of developing units is arranged in parallel with a peripheral surface mainly below the outer peripheral surface of the photoreceptor belt. Are located. Therefore, for example, when the photoreceptor belt portion is formed as a cartridge and can be removed, a wide range of the photoreceptor portion facing the image forming means of the cartridge is exposed, and the photoreceptor is extremely likely to be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image forming apparatus in which a photoreceptor belt can be removed and the photoreceptor itself is protected in a detached state.

[Configuration of the invention]

The above object is achieved by disposing a belt-shaped image forming member stretched between a plurality of rotating rollers, and an image forming device including a charging device, an exposure device, and a plurality of developing devices opposed to the belt-shaped image forming device. In the color image forming apparatus, the plurality of developing devices are arranged in parallel on one side of the belt-shaped image forming body, and the belt-shaped image forming body has a cartridge configuration, and is detachably provided to the apparatus main body. The cartridge has a plurality of openable and closable covers at a position facing the developing device, and the cover is stored in a storage space provided between the developing devices in an open state. Is achieved by a color image forming apparatus.

〔Example〕

One embodiment of the color image forming apparatus of the present invention is shown in FIGS.

In FIG. 1, reference numeral 1 denotes a flexible photoreceptor belt which is a belt-shaped image forming member. The photoreceptor belt 1 is driven clockwise by a rotating roller 2 provided between the rotating rollers 2 and 3. Transported to

Reference numeral 4 denotes a guide member fixed to the apparatus main body so as to be inscribed in the photoreceptor belt 1. The photoreceptor belt 1 is tensioned by a mechanical action above the tension roller 5 so that the inner peripheral surface thereof is formed. Is brought into sliding contact with the guide member 4.

Accordingly, the photosensitive member on the outer peripheral surface of the photosensitive belt 1 is always kept at a fixed relation to the surface of the guide member 4 even during the conveyance, so that a stable image forming surface can be formed.

Reference numeral 6 denotes a scorotron charger as charging means, 7 denotes a laser writing system unit as image exposure means, and 8 to 11 denote a plurality of developing means or developing devices each containing a developing material of a specific color. The means is disposed facing the outer peripheral surface of the photoreceptor belt 1 with the guide member 4 on the back.

As the laser writing system unit 7, in addition to the optical system shown in the figure, an optical system or the like in which a light emitting unit and a converging light transmitter are integrated is used.

Each of the developing units 8, 9, 10, and 11 contains, for example, each of yellow, magenta, cyan, and black developers, and each developing sleeve that maintains a predetermined gap from the photosensitive belt 1.
8A, 9A, 10A, and 11A, and has a function of visualizing a latent image on the photosensitive belt 1 by a non-contact developing method. Unlike the contact development, the non-contact development has an advantage of not hindering the movement of the photosensitive belt.

Reference numeral 12 denotes a transfer unit, 12A denotes a static elimination bar, 13 denotes a cleaning device, and a blade 13A and a toner conveying roller 13B of the cleaning device 13 are kept at a position separated from the surface of the photoreceptor belt 1 during image formation. It is pressed against the surface of the photoreceptor belt 1 only during cleaning, as shown in the figure.

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. That is, the data obtained by the color image data input unit (FIG. 2A) in which the image sensor scans the original image is converted into an image data processing unit (2
The image data is created by performing arithmetic processing in FIG. 2B, and is temporarily stored in the image memory (FIG. 2C). Next, the image memory is taken out at the time of recording and inputted to a recording section (FIG. 2 (d)), 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 unit 7, the laser writing unit 7 generates a laser beam generated by a semiconductor laser (not shown). Is scanned by a polygon mirror 7B rotated by a drive motor 7A, the optical path of which is bent by mirrors 7D and 7E via an fθ lens 7C, and charged by a charger 6 as a charging means in advance. It is projected on the peripheral 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 is transmitted to the photosensitive belt 1.
Is scanned on the peripheral surface of. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive belt 1 by the main scanning by the laser beam and the sub-scanning by the conveyance of the photosensitive belt 1. This latent image is developed by a developing unit 8 loaded with yellow (Y) toner (a visual medium) in the developing means.
A toner image is formed on the drum surface. The toner image thus obtained passes under the cleaning device 13 as cleaning means separated from the peripheral surface of the photoreceptor belt 1 while being held on the drum surface, and enters the next copy cycle.

That is, the photoreceptor belt 1 is charged again by the charger 6, and then the second color signal output from the signal processing unit is input to the writing system unit 7. Similarly, writing is performed on the drum surface to form a latent image. The latent image is developed by the developing device 9 loaded with magenta (M) toner as the second color.

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

A developing unit 10 has a cyan (C) toner and forms a cyan (C) toner image on the drum surface based on a control signal generated by a signal processing unit.

Further, reference numeral 11 denotes a developing device having a black toner, which forms a black toner image on the belt surface by the same processing. A DC or further bias is applied to each sleeve of each of these developing devices 8, 9, 10 and 11, and a jumping development is performed by a two-component developer as a visualizing means, and a photosensitive member whose base is grounded The belt 1 is developed in a non-contact manner. As the development, non-contact development using a one-component developer can also be used.

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

That is, one of the uppermost layers of the transfer material accommodated in the paper feed cassette 14 is carried out by the rotation of the paper feed roller 16, and the transfer material is transferred to the transfer device 12 via the timing roller 17 in synchronization with the image formation on the photosensitive belt 1. Supplied to.

The transfer material that has undergone image transfer and static elimination is reliably separated from the photoreceptor belt 1, which suddenly changes direction along the rotating roller 2, and is directed upward, where the image is fused by the fixing roller 18 and then discharged. The sheet is discharged onto the tray 20 via the paper rollers 19A and 19B.

On the other hand, the photoreceptor belt 1 after the transfer to the transfer material is further conveyed and the remaining toner is removed by the cleaning device 13 in which the blade 13A and the toner conveying roller 13B are pressed against each other. The blade
13A, and slightly after that, the toner supply roller 13B
After the toner accumulates on the tip of the blade 13A, the toner supply roller 13B is separated to start a new image forming process.

The color image forming apparatus has a clamshell structure in which the upper housing can be rotated clockwise about the rotation shaft 21 and opened, and the photosensitive belt 1 and the cleaning device 13 are housed in the upper housing. Each of the developing units, the laser writing system unit 7, the fixing roller 18 and the like are
Together with the lower housing.

In the scorotron charger 6, the discharge electrode device 6A constituting the scorotron charger 6 is housed separately in the lower housing, and one of the grids 6B is housed separately in the upper housing. The charging device 6 is configured by combining the grids 6B.

The grid 6B is supported by the guide member 4 in a state where the grid 6B is attached to a protective plate 22 that covers the entire lower surface of the photoreceptor belt 1 as an image forming surface.

The protective plate 22 is provided with square holes 22A in corresponding portions of the developing sleeve and the exposure portion of each developing device, and opens only the image processing portion of the photoreceptor belt 1 to protect other portions.

Further, the guide member 4 is provided with a total of five protective covers 23 for shielding the square holes 22A and the grid 6B, respectively. When the upper housing is closed, the protective covers 23 are in the first position. As shown in the example of the developing device 11 in the figure, the protective cover 23 which is opened at a substantially right angle with the support shaft 23A as a fulcrum and shields the square hole 22A corresponding to each developing sleeve is provided in the housing of each developing device. It is designed to fit in a space.

Opening of each of the protective covers 23 accompanying the closing of the upper housing causes the charging of the photoconductor belt 1 by the charger 6,
Image exposure by the laser writing system unit 7 and development of the latent image by the developing sleeve of each developing unit become possible, and the process of forming a color image can be started.

On the other hand, when the upper housing is opened, the respective protective covers 23 rotate clockwise around the support shaft 23A as shown in FIG. Cover and protect the surface.

FIG. 4 shows a mechanism for opening and closing each of the protective covers 23 by opening and closing the upper housing.

The photoreceptor belt 1, the guide member 4, and the cleaning device 13 are incorporated in the process cartridge 30 and are integrally supported by the upper housing.
The 23 support shafts 23A are also supported by the side plates 30A at the front and rear of the process cartridge 30.

The support shaft 23A projects from the front surface of the side plate 30A,
An arm 24 having a drive pin 24A attached to the tip is fixed integrally, and the arm 24 is constantly urged clockwise by a torsion spring 25, thereby holding the protective cover 23 with each of the square holes.
22A is shielded. Such an arm 24 is the same as
It is provided for all the protective covers 23.

A drive plate 26 slidable only in the left-right direction is provided at the center of the side plate 30A.
Supported and mounted via 7.

The drive plate 26 has each claw portion 26B at a slightly distant position corresponding to the drive pin 24A of each arm 24, and a cam surface 26C at a step portion thereof.

In a state where the upper housing is open, the driving plate 26 is in a free state because the pressing pin 27 fixed to the lower housing does not press the cam surface 26C, and therefore the side plate 30
A at the rightmost position, i.e., the left end of the elongated hole 26A is urged by the tension spring 28 stretched between the guide shaft 27
In the locked position.

As a result, the drive pin 24A is released from each claw portion 26B of the drive plate 26 to release each protection cover 23 and torsion spring 25A.
The square holes 22A are shielded by the urging.

When the upper housing is rotated counterclockwise about the rotation shaft 21 as a fulcrum, the cam surface 26C of the driving plate 26 is pressed by the pressing pin 27, and the driving plate 26 resists the urging of the tension spring 28. Then, each of the claws 26B presses the corresponding drive pin 24A to rotate the arm 24 counterclockwise.

Accordingly, each of the protective covers 23 is also provided with a respective torsion spring 25.
In the state where the cover has been closed by rotating counterclockwise against the bias of (1), the cover is opened to a substantially right angle as shown in FIG.

Although the embodiment described above is an example in which the protective cover itself is opened and closed by the operation of closing and opening the upper housing, the protective cover is always opened regardless of whether the upper housing is closed or opened. The protective cover may be closed only when the process cartridge is pulled out from the front surface of the upper housing and removed.

FIG. 5 shows an example of this, in which a part of the drive plate 126 shown in FIG. 5A is bent at a right angle and extends parallel to the upper surface of the process cartridge 130, and FIG. The cam surface 126C is formed in the depth direction as shown in FIG. The cam surface 126C is pressed by a pressing pin 127 when the process cartridge 130 is attached to the upper housing.

Therefore, when the process cartridge 130 is inserted into the upper housing, the cam plate 126 is always pressed by the pressing pin 127, so that the driving plate 126 slides to the leftmost position. The cover 123 is in an open state, and this state is always maintained regardless of whether the upper housing is closed or opened.

On the other hand, when the process cartridge 130 is pulled out from the upper housing and removed, the cam surface 126C is released from the pressing of the pressing pin 127, so that the driving plate 126 is urged by the tension spring 128 as shown in FIG. As a result, it returns to the rightmost position, and as a result, the protective cover 123 automatically shields the photosensitive surface.

The present invention can be applied to all color image forming apparatuses using a photosensitive pair belt regardless of an image forming system. For example, as shown in FIG. The device is installed and the photosensitive pair belt 501
It is also possible to protect the photosensitive surface by using a color image forming apparatus having an image forming system capable of completing the formation and transfer of a color image by a rotation conveyance cycle.

Also in this case, grids 506B, 516B, 526B, 536 of each charger are provided.
B is attached to the lower housing side, and, for example,
As shown in FIG. 11, protective covers 523A and 523B are provided for each pair, which separately shield the grid 536B and the opposing square holes of the developing sleeve.

〔The invention's effect〕

According to the present invention, in an apparatus using the photosensitive surface of the photoreceptor belt or the scorotron charger, the grid surface can be safely protected from dirt and damage which are likely to occur during operation and maintenance work of the apparatus, As a result, the life of the photoreceptor belt and grid is prolonged, so that an image forming apparatus which is economical and can obtain a high quality image by the photoreceptor which is always kept in the best condition is provided. .

[Brief description of the drawings]

1, 3, and 6 are cross-sectional views of the color image forming apparatus of the present invention, FIG. 2 is a block diagram showing an image forming system, and FIGS. 4 and 5 show an opening / closing mechanism of a protective cover. FIG. 1,501 photosensitive belt 2,3 rotating roller 4,504 guide member 6,506,516,526,536 charger 6B, 506B, 516B, 526B, 536B grid 8,9,10,11,508,509,510,511 developing device 22 Protective plate, 22A… Square hole 23… Protective cover, 23A… Support shaft 24… Arm, 25… Torsion spring 26… Drive plate, 26A… Elongated hole 26B… Claw, 26C… Cam Surface 27 ... Pressing pin, 28 ... Tension spring 30,530 ... Process cartridge 507,517,527,537 ... Image exposure device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-151560 (JP, A) JP-A-61-219965 (JP, A) JP-A-63-43170 (JP, A) 49360 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/00 550 G03G 21/16-21/18 G03G 15/01

Claims (1)

(57) [Claims] A belt-shaped image forming member stretched between a plurality of rotating rollers, and an image forming device including a charger, an exposure device, and a plurality of developing devices are arranged opposite to the belt-shaped image forming device. In the color image forming apparatus, the plurality of developing devices are arranged in parallel on one side of the belt-shaped image forming body, and the belt-shaped image forming body has a cartridge configuration, and is detachably provided to an apparatus main body. The cartridge has a plurality of openable and closable covers at a position facing the developing device, and the cover is stored in a storage space provided between the developing devices in an open state. Color image forming apparatus.