JP2802782B2 - 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 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 in accordance with the number of separation colors of a document image on a photosensitive drum, and transferred to 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, and 60-158475.

In such a multicolor image forming apparatus that obtains a color image by superimposing, a plurality of developing devices containing 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.

[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, 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.

The present invention solves this problem and as a result, as a result, it is possible to form a color image forming apparatus such as a photoreceptor belt which can be detachably attached to an apparatus main body by a very easy operation according to maintenance inspection without interfering with each other. It is intended to provide a device.

[Configuration of the invention]

The above object is achieved by disposing a process unit having a horizontally arranged belt-shaped image carrier, a developing unit having a plurality of developing units below the process unit, and a sheet feeding cassette below the developing unit. A fixing roller pair is disposed above the process unit, and the transfer paper fed in a substantially horizontal direction from the paper feed cassette is changed in the feeding direction to the belt-shaped image carrier and the fixing device. A color image forming apparatus having a transfer paper path for guiding
In conjunction with opening of the front cover of the color image forming apparatus, the developing unit is separated from the process unit in a direction substantially perpendicular to the mounting / removing direction of the process unit, and the process unit is opened from the side where the front cover is opened. This is achieved by a color image forming apparatus characterized in that the unit is detachable.

〔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 in contact with 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 is guided by the guide member 4. Rub. Note that the guide member 4 is provided with a concave portion in a region not required for image formation, thereby reducing resistance due to rubbing. Of course, this recess need not be provided if the sliding resistance is low. Further, in order to reduce the rubbing resistance between the photosensitive belt 1 and the guide member 4, a low-friction member is applied to the photosensitive belt 1 or the guide member 4 by using Teflon processing.
Is preferably provided on any one of the surfaces, or is constituted by the above-mentioned low friction member.

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 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. The photosensitive belt 1 is disposed at a position 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 unit, 12A denotes a charge removing plate, 13 denotes a cleaning device, and a blade 13A of the cleaning device 13 and the toner conveying roller 1
3B is kept at a position separated from the surface of the photoreceptor belt 1 during image formation, and is brought into pressure contact with the surface of the photoreceptor belt 1 as shown in the drawing 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. 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 rotated by a polygon mirror 7B rotated by a drive motor 7A, and the optical path is bent by mirrors 7D and 7E via an fθ lens 7C. The light is projected on the 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 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 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. In the same manner as described above, 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 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 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.

As shown in FIG. 3, the photoreceptor belt 1, the guide member 4, the scorotron charger 6, and the image forming means of the cleaning device 13 include front and rear substrates 30A and 30B.
And is attached to and detached from the apparatus main body as a unit.

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

On the other hand, each of the developing units is assembled in a state of being partitioned into an integral and flexible developing container 41 as shown in FIG. 4, and then mounted on a support table 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.

6 and 7 are sectional views taken along line AA of the cartridge 30 shown in FIG. 3 and the developing unit 40 shown in FIG. 4, 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 engaged with the engaging pin P2 of the rear side plate 110B, 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 is fitted in 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 is provided with an engaging pin P3 at a bent portion 42B at the center of the front surface of the support base 42, and an engaging pin P4 at each of a pair of bent portions 42C on the rear surface. Is provided with an urging device for pressing the engaging pins P3 and P4 to move the developing unit 40 to the cartridge 30.

In FIG. 7, reference numeral 101 denotes a stop plate that regulates the upper limit position of the engaging pin P3 of the developing unit 40 attached to the inner surface of the front cover 100, and 102 has an inclined surface 102A and slides upward by the action of a tension spring 103. If the developing unit 40 is not inserted when the pressing plate is guided, the pressing plate
Reference numeral 102 is maintained at a position slightly higher than the illustrated position.

On the other hand, reference numeral 111 denotes an elongated hole on the rear side plate 110B provided with a portion to which the engagement pin P4 is fitted, and 112 denotes a development by a pressure plate which has an inclined surface 112A and is guided to slide upward by the action of a tension spring 113. When the unit 40 is not inserted, the crimping plate 112 is kept at a position slightly higher than the position shown.

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 an 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. Result the cartridge
30 is 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.

The structure and function of each developing device will be described using the developing device 9 as an example.

FIG. 8 shows a cross section of the developing device 9. Reference numeral 9A denotes a developing sleeve containing a fixed magnet roller, and a predetermined developing distance between the peripheral surface of the photoreceptor belt 1 and a coaxial abutting roller 9B. And is driven and rotated counterclockwise. Reference numeral 90A denotes a rigid and magnetic thin layer forming member which is pressed against the developing sleeve 9A with a predetermined load in a state where the developer is not interposed. 90B and 90C have a screw structure, and are a pair of toner conveying screws that convey and circulate the developer in opposite directions to each other, and have a function of sending the toner and the carrier to the developing sleeve 9A as the upper developer sufficiently stirred and mixed. is there.

The toner transport screw 90B and the toner transport screw 90C are members that also serve as a stirring member that rotates in the direction of transporting each other, and the toner and the carrier transported to the back side by the thrust of the toner transport screw 90B are on the toner transport screw 90C side. The toner is transported to the near side of the drawing by the thrust, and is made into a homogeneous developer triboelectrically charged by the mixing action of the toner and the carrier therebetween, and adheres in a layer on the peripheral surface of the developing sleeve 9A.

This developer layer adhered on the peripheral surface of the developing sleeve 9A to form a thin layer is used to transfer the latent image on the peripheral surface of the photoreceptor belt 1 conveyed clockwise in the development area at a distance of the above-described development interval. The toner image is formed by reversal development upon contact.

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

The developer having consumed the toner component has a higher carrier ratio and is conveyed by the developing sleeve 9A to be scraped by the scraper 90D.
And the developer with a high toner ratio is mixed again.

The main assembly of the apparatus is configured to open and close one of the pair of the paper feed guide 15, the timing roller 17, the fixing roller 18, and the paper discharge roller 19 and one of the rollers and the transfer device 12 to form the left side of the main body. Supported by a possible horizontal cover 200,
When a jam of the transfer material occurs, the horizontal cover 100 is opened as shown by a dashed line in FIG. 9 so that the transfer material can be easily removed. The horizontal cover 200 may be provided with a support shaft 200A at the upper part of the main body and open from the lower side.

〔The invention's effect〕

According to the present invention, the developing unit and the cartridge containing the image forming body interfere with each other by retracting and separating the developing unit containing a plurality of developing units from the image forming body by a very simple mechanism and easy operation. A color image forming apparatus that can be freely attached to and detached from the apparatus main body without causing any trouble, and as a result, maintenance of each image forming means can be performed and a high quality image can always be obtained. It was decided to be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a color image forming apparatus of the present invention, FIG. 2 is a block diagram showing an image forming system, and FIGS. 3 and 4 are process cartridges housed in the apparatus. FIG. 5 is a perspective view of a front cover of the apparatus, FIG. 6 and FIG. 7 are cross-sectional views of the cartridge and the unit, FIG. FIG. 9 is a configuration diagram of a lateral cover of the device. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor belt, 4 ... Guide member 6 ... Charger 7 ... Laser writing system unit 8,9,10,11 ... Developing device 8A, 9A, 10A, 11A ... Developing sleeve 12 ... Transfer Container 13 Cleaning device 14 Paper cassette 17 Timing roller 18 Fixing roller 30 (Process) cartridge 30A (30B) Substrate 35 Handle 40 Developing unit 41 ...... Developing container 42 Support base 43 Compression spring 100 Front cover 101 Stop plate 102,112 Crimping plate 103,113 Tension spring 110A (110B) Side plate 111 Long hole 200: Horizontal cover, H: Engagement hole P1, P2, P3, P4: Engagement pin

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-133473 (JP, A) JP-A-62-278580 (JP, A) JP-A-62-209546 (JP, A) Jpn. 96645 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/01-15/01 117 G03G 13/01 G03G 15/00 G03G 15/00 550 G03G 21/16-21 / 18

Claims (1)

(57) [Claims] A process unit having a belt-shaped image carrier disposed horizontally, and a developing unit having a plurality of developing units disposed below the process unit, and a paper feed cassette disposed below the developing unit. And a pair of fixing rollers is disposed above the process unit, and the transfer direction of the transfer paper fed from the paper feed cassette in a substantially horizontal direction is changed upward to change the feeding direction of the belt-shaped image carrier and the fixing device. And a transfer paper path for guiding the developing unit to the process unit in a direction substantially perpendicular to a direction in which the process unit is attached to and detached from the process unit in conjunction with opening of a front cover of the color image forming apparatus. Wherein the process unit is detachable from a side where the front cover is opened.