JP2524651Y2 - 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 is transferred onto 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 according to the number of color separations of a document image on a photosensitive drum as an image carrier,
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 one image on the peripheral surface in addition to the photosensitive drum, 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 Japanese Patent Application Laid-Open Nos. 60-75850 and 60-76766 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 is separated by using a portion of the curvature using a small-diameter rotating roller, thereby preventing poor transfer material separation and the like. it can.

[Purpose 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, a plurality of developing units and a cleaning unit is provided mainly below the outer peripheral surface of the photoreceptor belt. The image forming means are installed facing the peripheral surface, and these image forming means including the photosensitive belt are housed in an independent form as a unitized process cartridge so as to be freely detachable from the apparatus main body.

However, when many such image forming means are integrated, the cartridge becomes large and heavy, making it difficult to attach and detach the cartridge to and from the apparatus main body. In addition, each image forming means may have a different service life and a different frequency of maintenance. There are many points that are inconvenient in terms of maintenance management.

As a result of solving this problem and improving the present invention, a process cartridge including a transfer means, particularly a transfer belt and a photoreceptor belt, can be attached to and detached from the apparatus main body in accordance with maintenance and inspection, and a small area can be used for removal. It is an object of the present invention to provide a color image forming apparatus in which a photoreceptor belt of a certain transfer section is efficiently protected in a small space.

[Structure of device]

The object is to integrally form a belt-shaped image forming member that is stretched and moved between a plurality of rotating rollers and a transfer unit that transfers a toner image formed on the belt-shaped image forming member onto a transfer material. In the color image forming apparatus in which the process cartridge is detachable from the apparatus main body, in a state where the process cartridge is detached from the apparatus main body, the transfer unit moves from the transfer unit at the time of transfer of the belt-shaped image forming body. This is achieved by a color image forming apparatus characterized in that it is configured to come into contact with a wide area to cover and protect a transfer area.

〔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 serving as a belt-shaped image forming member. The photoreceptor belt 1 is provided between rotating rollers 2 and 3 and is driven clockwise by driving the rotating roller 2. 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 the action of a tension roller 5 so that the inner peripheral surface thereof becomes the guide member. 4 rub. The guide member 4 is provided with a concave portion in an area unnecessary for image formation,
The resistance due to rubbing is reduced. Of course, this recess need not be provided if the sliding resistance is low. Photoreceptor belt 1
Alternatively, a low friction member such as Teflon (registered trademark) processing is provided on either the surface of the photoreceptor belt 1 or the guide member 4 for the purpose of reducing the sliding friction between the guide members 4, or is constituted by the above low friction member. Is preferred.

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.

By providing the developing device and the cleaning device below the photoreceptor belt, it is possible to prevent the developer from scattering and spilling.

6 is a scorotron charger as charging means, 7 is a laser writing system unit as image exposure means, and 8 to 11 are developing devices as a plurality of developing means each containing a developer of a specific color. Is disposed at a position of the photoreceptor belt 1 facing the guide member 4. Then, in order to maintain the gap without hindering the movement of the photoreceptor belt 1, the guide member 4 is brought into contact with the guide member 4 outside the photoreceptor belt 1 with a gap holding means.

As the laser writing system unit 7, in addition to the optical system shown in the figure, an optical system 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 device, and reference numeral 13 denotes a cleaning device. The blade 13A and the toner conveying roller 13B of the cleaning device 13 are kept at a position separated from the surface of the photosensitive belt 1 during image formation, and are shown only during cleaning after image transfer. As described above, the photosensitive belt 1 is pressed against the surface of the photosensitive belt 1.

When a color signal output from an image reading device separate from the printer is input to the laser writing unit 7, the laser beam generated by the semiconductor laser (not shown) in the laser writing unit 7 is Drive motor 7A
Is rotated and scanned by a polygon mirror 7B rotated by a mirror, and the optical path is bent by mirrors 7D and 7E via an fθ lens 7C. Projected to form bright lines.

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 reversibly developed in a non-contact state by a developing unit 8 loaded with yellow (Y) toner (visual image medium) of the developing means, and a toner image is formed on the belt surface. The obtained toner image passes under the cleaning device 13 as a cleaning means separated from the peripheral surface of the photoreceptor belt 1 while being held on the belt 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 reversely developed in a non-contact state by a developing device 9 loaded with magenta (M) toner as a 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 drum surface by the same processing. A DC or AC 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 one-component or two-component developer as a visualization means, and the base is grounded. The photoreceptor belt 1 is developed in a non-contact manner.

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 supply cassette 14 is carried out by the rotation of the paper supply roller 16, and the transfer device 12 is synchronized with the image formation on the photosensitive belt 1 via the timing roller 17 in timing. Supplied to.

The transfer material that has undergone image transfer and static elimination is surely separated from the photoreceptor belt 1 that suddenly changes its direction along the rotating roller 2 without being affected by image quality such as toner scattering due to the static elimination effect. After the image is fused by the fixing roller 18, the image is discharged onto the tray 20 via the discharge roller 19.

On the other hand, the photoreceptor belt 1 after the transfer to the transfer material is further conveyed, and the toner remaining in the cleaning device 13 in which the blade 13A facing the rotation roller 3 and the rotating toner conveyance roller 13B are pressed against each other is pressed. After the removal, the blade 13A is separated again after the completion, and a little after that, the blade 13A is separated from the toner conveying roller 13B to start a new image forming process.

The photoreceptor belt 1, the guide member 4, the scorotron charger 6, the transfer device 12, and the cleaning device 13
As shown in FIG. 2, each of the image forming means is incorporated in a process cartridge 30 composed of bases 30A and 30B on the front and back sides, and is united and detached from the apparatus body.

In the cartridge 30, the front and rear bases 30A and 30B are integrated with the guide member 4 via the two stays 31, and between the bases 30A and 30B, each of the image forming means is held and inserted horizontally from the front of the apparatus body. Stored.

On the other hand, each of the developing devices is assembled in a state of being partitioned into an integral and flexible developing container 41 as shown in FIG. 3, and then mounted on a support 42 to form a developing unit 40 in the apparatus main body. Detachable.

The developing container 41 sandwiches a plurality of compression springs 43 arranged in the front-rear direction between the bottom surface corresponding to the developing devices 8 and 11 and the support table 42, and the peripheral surfaces of the developing sleeves are in contact with each other. In a state of being substantially horizontal from the front of the apparatus main body in a state of being locked by the claw portions 42A, the curvature of the curved surface formed by the guide member 4 is smaller than the curvature of the image forming surface of the photosensitive belt 1 formed by the guide member 4. Inserted and stored.

The cartridge 30 and the developing unit 40 are inserted into the apparatus main body by opening the front cover 100 of the apparatus main body shown in FIG.

FIGS. 5 and 6 are sectional views taken along the line AA of the cartridge 30 shown in FIG. 2 and the developing unit 40 shown in FIG. 3, respectively.
FIG. 4 shows a BB cross-sectional view.

The cartridge 30 has a pair of engaging holes H penetrating the front and rear substrates 30A and 30B at positions facing each other. On the other hand, on the apparatus main body side, the front cover 100 and the inner surface of the rear side plate 110B of the main body. Each of a pair of engagement pins P1 and P2 that fits into the engagement hole H is attached thereto.

In mounting the cartridge 30, first, the substrate 30B
Side engaging hole H is fitted to the engaging pin P2 of the rear side plate 110B, and a part of the substrate 30A is supported by the bent portion of the front side plate 110A, and then the front cover 100 is closed. The engagement pin P1 fits into the engagement hole H on the substrate 30A side, and the cartridge 30 is set at a predetermined storage position in the apparatus main body.

On the other hand, the developing unit 40 has an engaging pin P3 at a bent portion 42B at the center of the front surface of the support table 42, and an engaging pin P4 at each of a pair of bent portions 42C on the rear surface. Is provided with a biasing device for pressing the engaging pins P3 and P4 to move the developing unit 40 to the cartridge 30.

6, reference numeral 101 denotes a stop plate which regulates the upper limit position of the engaging pin P3 of the developing unit 40 attached to the inner surface of the cover 100, and 102 has an inclined surface 102A and guides to slide upward by the action of the tension spring 103. When the developing unit 40 is not inserted, the pressing plate 10
2 is maintained at a position slightly above the illustrated position.

On the other hand, reference numeral 111 denotes a long hole of the rear side plate 110B provided to fit the engaging pin P4, 112 denotes a pressing plate having an inclined surface 112A and guided to slide upward by the action of a tension spring 113, and a developing unit 40. If no crimping plate is inserted
Reference numeral 112 is maintained at a position slightly higher than the illustrated position.

In mounting the developing unit 40, first, the engaging pin P4 on the rear surface is inserted into the elongated hole 111 of the rear side plate 110B, and the bent portion 42A at the front center is placed on the upper edge of the front side plate 110A. When the engagement pin P4 is inserted into the elongated hole 111, the inclined surface 1
The crimping plate 112 is slid downward by pressing 12A. After the engagement, the crimping plate 112 is pressed against the upper end of the elongated hole 111 by the pressing force of the crimping plate 112.

Therefore, the developing unit 40 is in the inclined position with the front side lowered, and the developing sleeves 8A to 11A of the respective developing units are maintained at positions separated from the photosensitive belt 1 incorporated in the cartridge 30. The cartridge 30
Can be attached to and detached from the apparatus main body without interfering with the developing unit 40 at all.

The developing unit 40 is automatically set to a predetermined storage position by closing the front cover 100 similarly to the cartridge 30, whereby the developing sleeves are moved to positions where a predetermined developing interval is formed with the photosensitive belt 1. Is set.

That is, the front cover 100 pushes up the engaging pin P3 of the developing unit 40 in which the pressing plate 102 is supported by the front side plate 110A by the inclined surface 102A in the process of opening the lid, and at the end of closing the lid as shown in the drawing. P3 crimping plate
A state of being sandwiched and supported between 102 and the stop plate 101 is assumed.

As a result, the developing unit 40 is kept horizontal and is pressed against the cartridge 30, so that the abutting rollers of the respective developing devices described later are pressed against the guide member 4 and the developing sleeves and the photosensitive belt 1 are in contact with each other. Is set. When the developing unit 40 is pressed, the abutting rollers of the developing sleeves are uniformly arranged on the curved surface of the guide member 4 due to the flexibility of the developing container 41 itself and the elasticity of the compression spring 43 acting on the developing container 41. It is pressed properly with an appropriate load.

7 (A) to 7 (C) show the detailed structure of the transfer device 12. FIG.

In the drawing, 120A is a rotating shaft erected between the substrates 30A and 30B of the cartridge 30, and 120 is a pair of swing levers fixed to both shaft ends of the rotating shaft 120A, which is located on the substrate 30B side. A semicircular protrusion 120B is provided at the base of the swing lever 120. The projection 120B is turned on by operating any of the switches SA, SB, and SC designated according to an image forming sequence, and the rotation of the swing lever 120 is stopped and held at a predetermined position. .

121 is a drive roller bearing supported on the upper end of the swing lever 120, 122 is a rotatable driven roller directly mounted between the substrates 30A and 30B, and the drive roller 121 is a coaxial extension. It is driven and rotated counterclockwise by an attached motor (not shown).

Reference numeral 123 denotes a belt-shaped member, that is, a transfer belt, which is a transfer unit included in the transfer device 12, and is provided on a tension lever 125 which is wound around the drive roller 121 and the driven roller 122 and is urged counterclockwise by a tension spring 124. A predetermined tension is applied by the action of the tension roller 126. The transfer belt 123 is in contact with the photoreceptor belt 1 to form a transfer unit, and is circulated and conveyed counterclockwise by the rotation of the drive roller 121.

FIG. 7 (A) shows a position where the image forming sequence is at the transfer timing and the power of the apparatus main body connected to the rotating shaft 120A is switched to ON by the projection 120B in response thereto. This shows a state in which the transfer belt 123 is stopped and thereby the transfer belt 123 contacts the peripheral surface of the photoreceptor belt 1 to form a transfer unit.

That is, in this state, the image transfer to the transfer material is performed, and the residual toner adhering to the transfer belt 123 after the transfer material is sent out is removed by the cleaning blade 127 sandwiched by the front and rear swing levers 120 and is transferred via the transport screw 128. To the toner collection container.

FIG. 7 (B) shows that the image forming sequence is at the timing of superimposing toner images,
The power of the apparatus main body connected to 120A is stopped at the position where the switch SC is turned ON by the projection 120B by the projection 120B, whereby the transfer belt 123 is separated from the peripheral surface of the photosensitive belt 1 and the photosensitive belt is separated. 1 shows a state where one transfer area is opened.

As a result, the toner images of each color formed on the peripheral surface of the photoreceptor belt 1 are superimposed without contacting the transfer belt 123, and a complete color toner image can be synthesized.

Further, in the present invention, the transfer belt 123 has a function that can be used as a protection member for the transfer area of the photosensitive belt 1.

FIG. 7C shows the state of the transfer device 12 when the front cover 100 is opened in order to remove the cartridge 30 from the apparatus main body. In response to the operation, the image forming motor is released, and the switch SA is turned off. Is activated, and the rotation of the swing lever 120 is stopped at the position where the lever is turned ON. As a result, the swing lever 120 largely rotates clockwise, and the transfer belt 123 comes into contact with the photosensitive belt 1 over a wide area to cover and protect the transfer area.

As a result, the photoreceptor belt 1 whose upper and lower peripheral surfaces are covered by the bent surfaces of the substrates 30A and 30B is further provided with the transfer belt.
The transfer region is also covered by 123, and almost the entire peripheral surface is protected.

This mode is automatically released by the operation of mounting the cartridge 30 on the apparatus main body and closing the front cover 100, and the apparatus returns to the image forming mode again.

In the present embodiment, the color image forming apparatus for forming a color image by superimposing images by multiple rotations of the photoreceptor belt has been described. However, the present invention provides a color image forming apparatus in which a plurality of images are superimposed by one rotation of the photoreceptor belt. It can be applied to an image forming apparatus,
In that case, the operation of retracting the transfer belt from the peripheral surface of the photosensitive belt can be omitted.

[Effect of the invention]

The present invention makes it possible to automatically cover and protect the photoconductor in the transfer area with a small space, and to remove the photoconductor from the apparatus. As a result, the photoconductor is efficiently prevented from dust, scratches, or light deterioration. Thus, a color image forming apparatus capable of stably obtaining high-quality images for a long period of time has been provided.

The process cartridge may be an integrated process cartridge including a developing device group.

Further, the above embodiment is an embodiment in which a toner image is superimposed on an image forming body and then transferred onto a transfer material.However, the present invention is not limited to this. A structure in which a color image is formed by transferring the image to a transfer body each time may be used, and the same effect can be obtained.

[Brief description of the drawings]

1 is a sectional view of the color image forming apparatus of the present invention, FIGS. 2 and 3 are front views of a process cartridge and a developing unit housed in the apparatus, and FIG. 4 is a front cover of the apparatus. FIG. 5 is a perspective view, FIGS. 5 and 6 are cross-sectional views of the cartridge and the unit, and FIGS. 7A to 7C are main-portion cross-sectional views of the cartridge. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor belt, 2, 3 ... Rotating roller 4 ... Guide member, 6 ... Charging device 7 ... Laser writing system unit 8, 9, 10, 11 ... Developing device 12 ... Transfer device, 13 ... Cleaning device 14 ... Supply Paper cassette 17 Timing roller 18 Fixing roller 19 Discharge roller 30 Process cartridge 30A, 30B Substrate 40 Developing unit 120 Oscillating lever 120A Rotating shaft 120B Projection 121 Drive roller 122 … Driven roller, 123… transfer belt 126… tension roller 127… cleaning blade SA, SB, SC… switch

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-200160 (JP, A) JP-A-63-163864 (JP, A) Jikai Sho-56-88243 (JP, U)

Claims (3)

(57) [Scope of request for utility model registration] A belt-shaped image forming member that is stretched and moved between a plurality of rotating rollers, and a transfer unit that transfers a toner image formed on the belt-shaped image forming member onto a transfer material. In a color image forming apparatus in which an integrated process cartridge is detachable from an apparatus main body, in a state in which the process cartridge is detached from the apparatus main body, the transfer unit transfers the belt-shaped image forming body during transfer. A color image forming apparatus, wherein the color image forming apparatus is configured to come into contact with a wider area to cover and protect a transfer area. 2. A color image forming apparatus according to claim 1, wherein said transfer means is a belt-shaped member. 3. A color image forming apparatus according to claim 1, further comprising switching means for switching the position of said transfer means for covering and protecting said transfer area.