JP3000520B2 - Color image forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus 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.

[0002]

2. Description of the Related Art Conventionally, many methods and apparatuses have been proposed for obtaining a color image using an electrophotographic method. For example, as disclosed in Japanese Patent Application Laid-Open No. 61-100770, a latent image is formed and developed in accordance with the number of separation colors of a document image on a photosensitive drum as an image carrier, and a latent image is formed on a transfer drum each time development is performed. There is a method in which a multicolor image is formed on a transfer drum by transfer 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, Japanese Patent Application Laid-Open No. 61-149,972, a latent image is formed and developed on a photosensitive drum in accordance with the number of color separations of an original image, and a latent image is formed on a transfer material each time development is performed. To obtain a multicolored color copy. In this method, it is difficult to accurately superimpose multi-color images, and a high-quality color copy cannot be obtained.

Further, 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 the color toner image on the photosensitive drum. There is a way. The basic process of this multicolor image formation is described in Japanese Patent Application Laid-Open No. 60-75850 by the present applicant.
Nos. 60-76766, 60-95456, 60-95458, 60-158475, and the like.

[0005] In a multicolor image-formed image in which a color image is obtained by such superposition, a plurality of developing units accommodating color toners of different colors are arranged on the periphery of the photosensitive drum. Generally, the photosensitive drum is rotated a plurality of times to develop a latent image on the photosensitive drum to obtain a color image.

As for the image forming body, as described above, a photoconductive drum is coated or deposited on the peripheral surface of the drum, and a photoconductive member is coated or mounted on a flexible belt. Shaped imagers have also been proposed. Since the belt-shaped image forming body (hereinafter also referred to as a photoreceptor belt) is shaped by being stretched between rotating rollers including a driving roller, a color image forming apparatus having a compact shape by effectively utilizing space is provided. It is effective when configuring.

[0007]

In a color image forming apparatus using the photoreceptor belt proposed above, an image formed of a charger, an image exposure device, and a plurality of developing devices is provided on the periphery of the photoreceptor belt. A forming unit is provided, and the image forming unit faces the rotating photoreceptor belt with a certain gap.

Therefore, in order to obtain a high quality image, it is necessary that the surface of the image forming body of the photoreceptor belt is always conveyed while maintaining a constant position. For this reason, the photoreceptor belt is provided with a tension roller. It is configured to be rotated while maintaining a slidable contact state with a reference guide surface by the tension due to the pressure contact.

However, since the tension roller is usually installed so as to press the photosensitive belt in such a manner as to expand the photosensitive belt from the inside to the outside, a large space is required for carrying the photosensitive belt and the winding of the photosensitive belt around the drive roller. As the length became shorter, the frictional force was reduced, causing slip.

The present invention has solved and improved the above points,
It is an object of the present invention to provide a color image forming apparatus capable of transporting a belt-shaped image forming body in a narrow space and further having a sufficiently long winding length around a rotating roller so that a high quality image can be always obtained without a risk of causing a slip or the like. It was done.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a belt-shaped image forming apparatus which moves while being stretched by a plurality of rotating rollers and forms at least two surfaces by being stretched by the plurality of rotating rollers. On one surface side of the body, a plurality of sets of image forming means including a charger, an image exposing device, and a developing unit are arranged in parallel, and the belt-shaped image forming body is provided at a place where the plurality of sets of image forming means are arranged. A transfer device that transfers the toner image formed on the belt-shaped image forming body onto a transfer material is provided at a position downstream of the rotation direction and opposite to the rotating roller, and the transfer device is provided with respect to the transfer unit. It is downstream in the rotation direction of the belt-shaped image forming body, and on the other surface side of the two surfaces,
A tension roller is provided in contact with the front side of the belt-shaped image forming body, and the belt-shaped image forming body that is stretched and moved by the plurality of rotating rollers constitutes a cartridge together with the tension roller, and the cartridge forms an image. This is achieved by a color image forming apparatus, which is detachable from a forming apparatus main body.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a color image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a sectional configuration diagram of a color image forming apparatus showing one embodiment of the present invention, FIG. 2 is a block diagram showing an image forming system, and FIG. 3 is a side sectional view of the image forming unit of FIG. FIG.
4 is a sectional view of a main part of the developing device, FIG. 5 is a time chart of an image forming process, and FIG. 6 is a front view of the cartridge of FIG.

FIG. 1 shows a charger on the periphery of a belt-shaped image forming body.
A color image forming apparatus having four sets of image forming means including an image exposing device and a developing device, wherein
1 shows a color image forming apparatus of the type that completes the formation of a color image and the transfer of a transfer material in a rotation cycle.

In FIG. 1, reference numeral 1 denotes a flexible photoreceptor belt which is a belt-shaped image forming member. The photoreceptor belt 1 is provided between rotary rollers 2 and 3 and is a rotary roller 2 composed of a rubber roller. Is conveyed clockwise by the drive of.

Reference numeral 4 denotes a guide member fixed to the apparatus main body so as to be in contact with the photosensitive belt 1. The photosensitive belt 1 is tensioned by a mechanical action of the tension roller 5 downward. The inner peripheral surface is rubbed against the guide member 4.

Therefore, the photoreceptor on the outer peripheral surface of the photoreceptor belt 1 is always maintained at a fixed position with respect to the surface of the guide member 4 even during conveyance, and a stable image forming surface having a large curvature is formed with a long width. It is possible to do. Therefore, many image forming units having the same shape can be arranged in parallel.

In FIG. 1, four chargers 110, 21 are opposed to the photoreceptor belt 1 behind the guide member 4.
0, 310, 410 and four image exposure devices 120, 22
0, 320, 420 and four developing units 130, 230,
330, 430 are located. Then, four chargers, image exposure devices, and developing devices 110, 120, and 130;
0, 230; 310, 320, 330; 410, 42
Reference numerals 0 and 430 are adjacent to each other as a set of four image forming units, and face the photoreceptor belt 1 having a guide member 4 having the same radius of curvature behind. Since the respective chargers and the respective developing devices are arranged close to each other substantially in parallel in this manner, it is possible to use a common power source and drive.

Each of the chargers 110, 210, 310, and 410 is a scorotron charger having the same structure. FIG. 3A shows a state in which the charger 110 is opposed to the photoreceptor belt 1 shown in the XX section in FIG. As shown. That 110A on the back plate of the charger 110, the metal member which cross section has a U-shaped, 110B each electrode blocks attached to both ends of the back plate 110A, 110W ₁ is stretched between the electrode block 110B This is a wire for the electrode. 110W ₂ is etched grid configured in a grid wire or mesh-like and many present stretched in front of the wire 110W _1.

Each of the electrode blocks 110B is integrally formed with a projection 110C having a predetermined height as a contact member.
Outside, is urged by an elastic member 110D such as a leaf spring so as to press against the guide member 4.

[0020] Thus the electrode wire 110W ₁ and grid wires 110W ₂ is located kept always constant spacing relative to the peripheral surface of the photosensitive belt 1, it is possible to reliably charge the photosensitive member to a predetermined potential.

Image exposure devices 120, 220, 320, 42
Reference numeral 0 denotes an image exposure unit having the same structure, and receives a color signal output from an image reading apparatus separate from the color image forming apparatus shown in the example of FIG.
A bright line for image formation is formed on the peripheral surface of the photoreceptor belt 1 to which the electric charge is given by 0, 310, 410.

Image exposure devices 120, 220, 320, 42
Reference numeral 0 denotes a laser beam generated by a semiconductor laser based on the input color signal, the laser beam is rotationally scanned by a polygon mirror, and the photosensitive belt 1 is passed through an fθ lens.
A laser writing system unit (not shown) that forms a bright line by projecting on the peripheral surface of the laser beam is also input as a convergent light transmitting body 120A linearly arranged as shown in FIG. Light emitting unit 120B such as an LED that emits light based on a color signal
And an integrated image exposure optical system.

FIG. 3C shows the Z of the image exposure apparatus 120 shown in FIG.
The light emitting portion 120B is a projection 12 having a predetermined height as an abutting member at both ends of the casing.
0C is the guide member 4 outside the photoreceptor belt 1.
As in the case of the charger 110, the elastic member 120D such as a leaf spring is urged so as to be in pressure contact with the charging device 110.

Accordingly, the image exposure device 120 is also always positioned at a constant distance from the peripheral surface of the photoreceptor belt 1 and can form an image on the photoreceptor belt 1 accurately.

The developing units 130, 230, 330, and 430 have the same structure. A developing device for carrying out non-contact reversal development has a two-component developer containing yellow (Y), magenta (M), cyan (C) and black (BK) toners and a carrier, respectively. is there.

FIG. 4 shows a cross section of the developing device 130. Reference numeral 130A denotes a developing sleeve containing a fixed magnet roller and a predetermined distance between the developing roller 130 and the peripheral surface of the photoreceptor belt 1 by coaxial abutting rollers 130B. The developing interval is maintained and the driving rotation is performed in the counterclockwise direction. 131A is a rigid and magnetic thin layer forming member that is pressed against the developing sleeve 130A with a predetermined load in a state where the developer is not interposed. 131B
Reference numerals 131C and 131C denote a pair of toner conveying screws which have a screw structure and convey and circulate the developer in opposite directions. The pair of toner conveying screws has a function of sufficiently stirring and mixing the toner and the carrier and sending the resultant to the developing sleeve 130A as the developer.

The toner conveying screw 131B and the toner conveying screw 131C are members that also serve as a stirring member that rotates in directions opposite to each other, and the toner and the carrier conveyed to the back side by the thrust of the toner conveying screw 131B are the toner conveying screw. The developer is transferred to the screw 131C side, is conveyed to the near side in the drawing by the thrust, and becomes a uniform 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 130A.

This layer of developer adhered to the peripheral surface of the developing sleeve 130A and formed into a layer becomes a thin layer in the course of passing through the thin layer forming member 131A, and is conveyed clockwise in the developing area. The toner image is formed by reversal developing the latent image on the peripheral surface of No. 1 in a non-contact manner at a developing interval.

During this non-contact development, a developing bias including an AC component in addition to a DC component is applied to the developing sleeve 130A from a power source (not shown).
Only the toner in the developer is selectively transferred to and adhered to the surface of the latent image on 30A.

The developer having consumed the toner component has a high carrier ratio, is conveyed by the developing sleeve 130A, is separated and collected by the scraper 131D, and is mixed with the developer having a high toner ratio again.

FIG. 3B shows a section taken along the line YY of the developing device 130 shown in FIG. In FIG. 3B, 130A is a developing sleeve of the developing device 130, 130B is a striking roller serving as a striking member, and the striking roller 130B is rotatably supported by the rotating shaft S of the developing sleeve 130A. I have.

When the abutting roller 130B is pressed against the guide member 4, the developing sleeve 130A can form a gap corresponding to a developing interval between the peripheral surface of the developing sleeve 130A and the outer peripheral surface of the photosensitive belt 1. It has an outer diameter slightly larger than 130A.

Accordingly, the developing sleeve 130A has a constant developing interval (0.3 to 1 mm) suitable for non-contact development between the developing sleeve 130A and the outer peripheral surface of the photosensitive belt 1, and the developing device 130 always performs an appropriate developing process. You can do it. Note that the other developing device 23
The same applies to 0, 330, and 430. Each built-in abutting roller is pressed against the guide member 4 by a well-known urging mechanism, and development is performed in a stable state.

A charger having the structure and function described above,
As shown in FIG. 1, four sets of image forming means including an image exposing device and a developing device are opposed to the photoreceptor belt 1 with an interval of H from each other. That is, the chargers 110, 210, 310, 4
10 are arranged at intervals of H, and are
The same applies to 0, 330, and 430. In particular, the image exposure devices 120, 220, 320, and 420 are adjusted and arranged to have the same length H on the peripheral surface of the photosensitive belt 1 due to the superposition of color images. I have. Further fine adjustment is performed by electrically shifting the light emission timing of the light emitting units 120B, 220B, 320B, 420B more than the basic timing shift.

In the image formation by the printer, full-color image formation, functional color image formation, and single-color image formation are performed according to the mode selection. First, full-color image formation will be described. In this embodiment, the developing device 130 contains a developer containing a yellow (Y) toner, and the developing device 230 contains a developer containing a magenta (M) toner.
In the developing device 330, the developer containing the cyan (C) toner is
In the developing device 430, a developer containing black (BK) toner is loaded, and an image is formed according to a time chart shown in FIG.

First, when the start switch is turned on, the photoreceptor belt 1 starts rotating clockwise at a constant speed of V, and the chargers 110, 210, 310, 410 are simultaneously turned on at the first timing, and the photoreceptor is turned on. The top is uniformly charged. Next, a latent image corresponding to the first color (Y) output from the signal processing unit by the image exposure device 120 is formed on the peripheral surface of the photosensitive belt 1. Next, the developing units 130 and 2
30, 330, and 430 start operating simultaneously at the second timing. The first latent image is developed by the developing device 130, and a yellow (Y) toner image is formed.
The charger 21 holds the yellow (Y) toner image while being held.
It passes below 0 and is recharged.

A latent image corresponding to the second color (M) is formed by the image exposure device 220 with a delay of the time H / V from the latent image formation by the image exposure device 120. This latent image is developed by the developing device 230.

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

Further, on the photoreceptor belt 1 recharged by the charger 310, a latent image corresponding to the third color (C) is delayed by a time H / V from the latent image formation by the previous image exposure device 220. It is formed by the image exposure device 320. The latent image is developed by the developing device 330, and the cyan (C) toner image is formed in the presence of the already formed yellow (Y) and magenta (M) toner images.

Similarly, a black toner image is superimposed on the surface of the photoreceptor belt 1 by the same processing by the recharging by the charger 410 and the image exposure device 420 and the developing device 430 in the same manner. These sleeves 130A, 230A, 330A of the developing units 130, 230, 330 and 430,
A DC or further AC bias is applied to 430A, jumping development is performed by a two-component developer serving as a visualization unit, and development is performed in a non-contact manner on the photosensitive belt 1 whose base is grounded. ing. Incidentally, non-contact development using a one-component developer can also be used as the development.

The color toner image 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 is transferred via the timing roller 17.
The toner is supplied to the transfer unit 12 and the static elimination bar 12A at the same timing as the image formation.

The transfer material having undergone the image transfer and the charge removal is reliably separated from the photoreceptor belt 1, which suddenly changes direction along the rotating roller 2, and heads upward.
After the image is welded, the sheet is discharged onto a tray 20 via a sheet discharge roller 19.

On the other hand, the toner remaining on the photosensitive belt 1 after the transfer of the toner image onto the transfer material is removed by a cleaning device 13 disposed above the rotating roller 2.

After passing through the elastic plate 13B of the cleaning device 13, the toner on the photoreceptor is peeled off by the blade 13A pressed against the photoreceptor belt 1 around the rotating roller 2. The removed toner is sent to a toner collecting container from a toner collecting roller 13C in the form of a screw arranged slightly upstream.

The photoreceptor belt 1 is assembled together with the tension roller 5 and the cleaning device 13 into a cartridge 30 as shown in FIG. 6, and is attached to and detached from the apparatus main body as an independent unit.

That is, the cartridge 30 integrally supports the rotating rollers 2 and 3 around which the photosensitive belt 1 is wound between the front and rear substrates 30A and 30B via the two stays 31 and the guide member 4 for bearing support. And the photoreceptor belt 1
The tension roller 5 is pressed from above to be in a tension state, and the cleaning device 13 is sandwiched and supported above the rotating roller 2.

As shown in FIG. 1, the tension roller 5 is rotatably supported by a "U-shaped" crank lever 5A pivotally mounted between the substrates 30A and 30B, and the crank lever 5A is connected to a torsion spring 5C. By being rotated counterclockwise with the shaft 5B as a fulcrum by the action, the outer periphery of the cleaned photoreceptor belt 1 is pressed against the inside in the inward direction to be in a tension state. Therefore, the tension roller 5 can tension the photosensitive surface in a clean state without being stained by the toner.

The cartridge 30 is mounted on each substrate 30A.
And a pair of engaging holes H penetrating through the support body 30B, and are engaged with a pair of support shafts projecting from the apparatus main body to be mounted on the apparatus main body.

When the cartridge 30 is attached or detached, the pressing operation of the chargers, the image exposure devices and the developing devices on the main assembly side with respect to the guide member 4 is released, and the cartridge 30 does not interfere with them. It is safely inserted and removed from the horizontal direction.

[0051]

[0052]

[0053]

According to the first aspect of the present invention, there is provided a simple structure in which a plurality of sets of image forming means including a charger, an image exposure device, and a developing device are arranged in parallel in a narrow space in comparison with the conventional device. The tension roller pressing the belt-shaped image forming member inward from the surface of the belt-shaped image forming member also makes the winding length of the belt-shaped image forming member around the rotating roller sufficiently long, so that the belt-shaped image forming member can be rotated. The belt-shaped image forming body is reliably circulated and conveyed without causing a slip or the like in the moving roller portion, and a high-quality color toner image is formed. In particular, since the tension roller comes into contact with the surface of the belt-shaped image forming member after the transfer of the toner image, a high-quality color toner image is formed without being affected by the tension roller. Moreover, since the belt-shaped image forming body is easily attached to and detached from the apparatus main body as a cartridge, it is easy to clean and replace it despite being a small color image forming apparatus utilizing a small space,
It is possible to provide a color image forming apparatus that can maintain a high-quality color image.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating an image forming system.

FIG. 3 is a side sectional view of the image forming unit of FIG. 1;

FIG. 4 is a sectional view of a main part of the developing device.

FIG. 5 is a time chart of an image forming process.

FIG. 6 is a front view of the cartridge of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor belt 2, 3 rotating roller 4 guide member 5 tension roller 12 transfer device 13 cleaning device 18 fixing roller 30 cartridge 110, 210, 310, 410 charger 120, 220, 320, 420 image exposure device 130, 230, 330, 430 developing unit

 ────────────────────────────────────────────────── ─── Continuing from the front page Referee Susumu Sakai Referee Susumu Mizugaki Referee Ritsumasa Kobashi (56) References JP-A-1-112265 (JP, A) JP-A-63-38963 (JP, A) Japanese Unexamined Patent Publication (Kokai) No. 1-222161 (JP, A) JP-A-62-168167 (JP, A) JP-A-59-228283 (JP, A) JP-A-52-54449 (JP, A) JP, U) Japanese Utility Model Showa 64-13054 (JP, U) Japanese Utility Model Showa 62-41169 (JP, U) Japanese Utility Model Showa 58-172963 (JP, U)

Claims (1)

(57) [Claims] A first roller that moves while being stretched over a plurality of rotating rollers;
By being stretched by the plurality of rotating rollers, less
At least one surface of a belt-shaped image forming member forming two surfaces
On the side, image formation consisting of a charger, an image exposure device, and a developing device
A plurality of sets of means are arranged in parallel, and a plurality of
Downstream of the belt-shaped image forming body in the rotation direction, and
Formed on the belt-shaped image forming body at the position facing the moving roller
Transfer device for transferring the transferred toner image onto the transfer material is provided.
With respect to the transfer unit, in the rotation direction of the belt-shaped image forming body.
And the other side of the two surfaces is
The tension roller that contacts the front side of the
Provided, the belt-shaped image moving is stretched on the plurality of rotating rollers
The formed body is a cartridge together with the tension roller.
The cartridge is detachable from the image forming apparatus main body.
A color image forming apparatus.