JP3146385B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system, in which a belt-shaped image forming body is exposed from the back side, and the belt-shaped image forming body is formed together with a developing unit to form a color toner image on the belt-shaped image forming body. And a color image forming apparatus which transfers the toner image onto transfer paper to obtain an image.

[0002]

2. Description of the Related Art Conventionally, for example, when a multicolor image is formed by an image forming apparatus using an electrophotographic system, charging, exposure, development, and transfer are repeated for each color, and each color toner image is transferred onto a recording paper in a superimposed manner. I am trying to do it. For example, an electrostatic latent image is formed for each color on a photoreceptor by using separation light of blue, green, red, etc. obtained through a color separation filter, and is formed into a yellow, magenta, cyan and, if necessary, a black toner. And developing a toner image of each color, and transferring the toner image of each color onto recording paper to form a multicolor image.

[0003] For example, Japanese Patent Application Laid-Open No. Sho 56-144452, Japanese Patent Application No. 58-184381, and Japanese Patent Application No.
No. 3152, Japanese Patent Application No. 58-187000, the specification discloses that a plurality of toner images are superimposed and developed on the same photoconductor so that only one transfer process is required, and the development of the first toner image is performed. Other than the above, there has been proposed an image forming apparatus which performs non-contact development.

In order to reduce the size of the entire apparatus, a belt-shaped image forming member (hereinafter referred to as a belt photoreceptor) is stretched between two shafts, and a plurality of toners of different colors are accommodated along the lower side thereof. A plurality of developing units, and during the rotation of the belt photoconductor a plurality of times, forming a latent image on the belt photoconductor in accordance with the number of color separations of the original image, and forming a developing device group by the developing device group. A color copy is obtained by transferring the image onto a transfer sheet fed from a sheet feed cassette in a cassette storage chamber provided on the lower side.

[0005] Unlike the photoconductor drum, the belt photoconductor of such a color image forming apparatus can make a U-turn with a small curvature, so that it can run flat and can effectively use space. In addition, the separation of the transfer paper is improved by providing a separation pole for the transfer paper after the transfer at the small-diameter curvature portion that makes a U-turn.

However, the belt photoreceptor is suspended between a driving roller and a driven roller in the main body of the image forming apparatus, and when the belt photoreceptor is replaced, one or both of the driving roller and the driven roller are removed from the shaft and replaced. Has been done. At that time, since the developing device is also provided in the main body, a method of removing the belt photoreceptor and replacing it after pulling out the developing device (four in the case of color) from the main body has been performed. Further, as a method of exposing the belt photoreceptor, laser exposure is mainly performed from the outside of the belt photoreceptor.

[0007]

Since it is necessary to repeat the transfer cycle for each color as described above, the entire apparatus becomes large, the image forming process becomes complicated, the operation time is lost, and the operation is repeated. Each color toner image is displaced, and it is difficult to guarantee the accuracy of image formation. Further, when the second and subsequent image exposures of the color toner are performed, since the previously developed toner image always exists, the light of the image exposure applied to the area of the toner image where the toner is adhered. Cannot be sufficiently transmitted through the photoconductor. Further, in an image forming apparatus using a belt-shaped image forming body configured to improve the size, even if the miniaturization is solved, the image forming apparatus for the second and subsequent colors of the color toner is exposed in the photoconductor. The means for transmitting light sufficiently has not been solved yet, and has been a major bottleneck in forming a color image. Further, as described above, the belt photoreceptor is attached to the main body via the drive roller and the driven roller, and the belt photoreceptor cannot be removed from the main body unless the roller is removed from the shaft. It took a great deal of time to exchange. When a color developing device is provided at the same time, it is necessary to pull out the four developing devices from the main body and remove them. In this case, the developer comes into contact with the belt photoreceptor, and the developer falls or scatters in the machine. This caused the inside of the device to become dirty. Further, a band electrode for applying a charge to the belt photoreceptor is also fixed in the apparatus, and is disposed close to the belt photoreceptor. In this case, particularly when a new belt photoconductor is mounted on the driving roller and the driven roller and set in the apparatus, there is a risk that the band electrode comes into contact with the photoconductor surface of the belt photoconductor, so that the band electrode also needs to be removed. As described above, the replacement of the belt photoreceptor also required much labor. Further, since the exposing means is provided outside the belt photoreceptor, there is a disadvantage that the whole apparatus is enlarged.

Further, since a detecting means and the like provided for detecting the passage of the transfer paper are also provided on the outer peripheral portion of the belt photoreceptor, there is a possibility that the sensitivity may be lowered due to the adhesion of toner and dust, and the space may be reduced. For this reason, there is a problem that the detection accuracy cannot be increased because it is impossible to arrange the transfer paper close to the transfer surface.

The present invention has solved and improved this point,
Protects the transfer material detection means from adhesion of toner and dust,
Further, it is an object of the present invention to provide an image forming apparatus which can be disposed close to a transfer material, thereby improving detection accuracy.

[0010]

An object of the present invention is to provide an image forming apparatus having a photosensitive layer formed on a rotatable closed-loop transparent substrate, and an image exposing means disposed inside the image forming body. In the image forming apparatus, a transfer material detecting unit is provided upstream or downstream of the image transfer area of the image forming body, or inside and outside of the image transfer area, and jam detection or type determination of the transfer material is performed based on a detection signal from the detection unit. This is achieved by an image forming apparatus characterized in that:

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a flexible belt photoreceptor serving as a belt-shaped image forming member. The belt photoreceptor is suspended between a driving roller 2 and a driven roller 3, and is conveyed clockwise. The belt photoreceptor 1 uses a transparent base 1a, and a photosensitive layer 1b is provided on the transparent base 1a via a conductive layer 1c.
Is applied. Incidentally, a polyester material is used as the transparent base 1a of the conductive substrate, and the photosensitive layer 1b is formed of a photosensitive layer mainly composed of a carrier generating layer and a carrier transporting layer.

Reference numerals 4, 4a, 4b, and 4c denote guide members fixed to the main body of the apparatus so as to be in contact with the lower side of the belt photoreceptor 1. Reference numeral 5 denotes a tension member that is in contact with the belt photoreceptor 1 to bring the belt photoreceptor 1 into a tensioned state. It is. Guide members 4, 4a, 4
b, 4c and the tension member 5 make it possible to form a stable image forming surface on the belt photoreceptor 1.

Reference numeral 6 denotes a scorotron charger as a charging means.
A is a cleaner for cleaning the wire of the charger 6. Reference numeral 7 denotes a laser writing system unit serving as an image exposure unit. In addition to the optical system shown in the figure, the laser writing system unit 7 can use an optical system or the like in which a light emitting unit and a converging light transmitter are integrated.

Reference numerals 8, 9, 10 and 11 denote developing units as a plurality of developing means which respectively store developers of different colors, for example, yellow, magenta, cyan and black developers. The guide members 4, 4a, 4b, and 4c are disposed to face the photosensitive layer 1b of the belt photoreceptor 1 inscribed therein. These developing units 8 to 11 have developing sleeves 8A, 9A, 10 which maintain a predetermined gap from the photosensitive layer 1b of the belt photosensitive member 1.
A, 11A, and has a function of visualizing the latent image on the photosensitive layer 1b by a non-contact development method. Unlike the contact development, the non-contact development has an advantage that the movement of the belt photoconductor 1 is not hindered.

Reference numeral 12 denotes a transfer unit, 12A denotes a charge removing bar, and 13 denotes a cleaning device. Blade 13A of cleaning device 13
And the toner transport roller 13B is in contact with the photosensitive layer 1b during image formation.
The surface of the photosensitive layer 1b is pressed against the surface of the photosensitive layer 1b only at the time of cleaning after image transfer as shown in FIG.

The color image forming apparatus comprises: a belt photoreceptor 1 suspended from the driving roller 2 and the driven roller 3;
A laser writing system unit 7 of exposure means, a developing device 8,
As shown in FIG. 1, the image forming unit 14 is mounted on guide members 16, 17, 18 provided on an image forming apparatus main body 15. Fix with screws. The laser writing system unit 7 includes guide members 19 and 20 provided in the image forming unit 14.
Placed on and fixed. A protection cover 21 is attached to the outside of the image forming unit 14 so as to be openable and closable. When the image forming unit 14 is detached, the protection cover 21 is rotated in a closing direction about a rotating shaft 21A by a spring member or the like (not shown). To protect the belt photoreceptor 1 exposed to the transfer unit 12. A cover 22 for preventing dust from entering is also attached to the exposure slit 7a of the laser writing unit 7 so as to be openable and closable at the time of removal. And it is provided with the structure closed by the spring which is not illustrated.

FIG. 2 is a cross-sectional view of the image forming apparatus main body 15. A coupling 23 is provided on the shaft 2 A of the drive roller 2 provided in the laser writing unit 7, and is provided inside the image forming apparatus main body 15. Drive member 23 'driven by drive motor M
The coupling 23 is detachably connected to the coupling.

The guide members 16 and 17 are fixedly mounted on two stays 24 and 25 provided on the main body 15 of the image forming apparatus.
As a driving method of the developing units 8, 9, 10, and 11, a coupling C is provided to protrude from each of the developing units, and a clutch (not shown) is provided by a driving source provided separately by the driving motor M.
The operation is switched and driven by. 26 is the main body of the image forming apparatus
It is an opening / closing lid provided in front of 15.

First, the formation of a multicolor image according to the embodiment of FIG. 1 is performed according to the following system. The image forming apparatus main body
When a color signal output from an image reading device separate from 15 is input to the laser writing unit 7, a laser beam generated by a semiconductor laser (not shown) in the laser writing unit 7 is driven by a drive motor. The lens is rotated and scanned by a polygon mirror 27B rotated by an
The light path is bent by the mirror 27D via C, and is projected via the transparent base 1a on the peripheral surface of the photosensitive layer 1b of the belt photosensitive member 1 to which electric charge has been previously applied by the charger 6 as a charging means, thereby forming a bright line. .

On the other hand, when the scanning is started, the beam is detected by the index sensor, the modulation of the beam by the first color signal is started, and the modulated beam travels on the peripheral surface of the photosensitive layer 1b of the belt photosensitive member 1. Scan. Accordingly, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive layer 1b by the main scanning by the laser beam and the sub-scanning by the conveyance of the belt photosensitive member 1. This latent image is developed by the developing device 8 loaded with yellow (Y) toner (visual medium) in the developing means, and a toner image is formed on the surface of the photosensitive layer 1b. The obtained toner image passes under the blade 13A of the cleaning device 13 separated from the peripheral surface of the photosensitive layer 1b while being held on the surface of the photosensitive layer 1b, and enters the next print cycle.

The photosensitive layer 1b is charged again by the charger 6, and then the second color signal output from the signal processing section is input to the writing system unit 7, and the same as in the case of the first color signal described above. Then, 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,
Similarly, a cyan (C) toner image is formed by the developing device 10 having cyan (C) toner, and a black toner image is formed on the belt surface by the developing device 11 having black toner. .

A DC or AC bias is applied to each of the developing sleeves 8A, 9A, 10A, and 11A of each of the developing devices 8, 9, 10, and 11, so that jumping development using a two-component developer as a visualizing means is performed. The development is performed in a non-contact manner on the photosensitive layer 1b whose base is grounded. Incidentally, non-contact development using a one-component developer can also be used as the development.

As described above, the photosensitive layer 1b of the belt photosensitive member 1
Is formed on the transfer paper P. The transfer paper P is fed from a paper feed cassette 29 in a cassette storage chamber 28 below the developing devices 8 to 11 to the paper feed path 31 one by one from the uppermost layer by friction of the paper feed roller 30, and a timing roller 32. Is supplied to the transfer device 12 at the same time as the image formation on the photosensitive layer 1b of the belt photoreceptor 1. A separating roller 33 is used for separating the transfer paper P.

As described above, the transfer paper P supplied to the transfer unit 12 and subjected to image transfer and charge elimination is more reliably transferred from the photosensitive layer 1b which sharply (small-diameter curvature) changes direction along the drive roller 2. After being separated and facing upward, the image is welded by the fixing roller 34, the sheet is discharged onto a sheet discharge tray 36 via a sheet discharge roller 35, and is stacked.

On the other hand, the photosensitive layer 1 after the transfer to the transfer paper P is completed.
In step (b), 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. After the cleaning is completed, the blade 13A is separated again, so that the toner conveying roller 13B after a short time after the toner accumulated on the tip of the blade 13A is separated, the toner conveying roller 13B is separated, and a new image forming process is started.

Each of the tray conveying pipes 151 of the corresponding toner hopper 38 is automatically connected to each of the developing devices 8, 9, 10, 11 so that toner is supplied.

Further, the apparatus is a paper feeding means for feeding the transfer paper to the paper feeding path 31, and a first paper feeding means by manual paper feeding from a releasable manual feeding guide plate 37 at a side of the apparatus body. A second paper feeding means for automatically feeding paper from the paper feeding cassette 29;

FIG. 3 is an exploded perspective view in which the image forming unit 14 and the laser writing unit 7 described with reference to FIGS. 1 and 2 are removed from the image forming apparatus main body 15, respectively. Unit positioning holes 39 and 40 are provided in the unit 7, and the unit 7 is provided with positioning pins 41 and 42 inserted and positioned in the unit positioning holes 39 and 40 at a portion facing the wall 15A.

In order to insert and position the laser writing system unit 7 in the image forming unit 14, positioning holes 43 and 44 for the laser writing unit 7 are provided in a part of the inner wall in the image forming unit 14. Positioning pins 45 and 46 inserted and positioned in the holes 43 and 44 are provided in the laser writing unit 7, and an insertion hole 47 into which the laser writing unit 7 can be inserted is opened in the front wall of the image forming unit 14. The laser writing unit 7 is inserted in the direction indicated by the arrow in FIG. 3, and the positioning pins 45 and 46 are inserted into positioning holes 43 and 44 in the image forming unit 14 for positioning. When the laser writing system unit 7 is inserted, it is placed and guided on the guide members 19 and 20, and is accurately positioned. Further, a plurality of positioning pins 50 provided in the insertion direction are provided on a front plate member 49 provided with handles 47, 48 provided in front of the laser writing system unit 7 in the insertion direction.
The positioning pin 50 is inserted into the hole 51 provided opposite to 14, and the laser writing system unit 7 is accurately set at a predetermined position in the image forming unit 14. Note that the mounting / removing direction of the image forming unit 14 is not particularly limited, and the image forming unit 14 may be configured to be mounted / removed from the front-back direction or the side direction.

FIG. 4 shows a state in which the laser writing system unit 7 is fixed to the inner wall 15A of the image forming apparatus main body 15 with a plurality of screws 52.
On the other hand, only the image forming unit 14 is separately attached to the image forming apparatus main body 15, and as shown in FIG. 4, a notch 47a is provided on the back side in the insertion direction of the image forming unit 14, and the image forming unit 14 is , 14C, and is inserted into the image forming apparatus main body 15 in the direction indicated by the arrow. At that time, the laser writing system unit 7 is inserted into the image forming unit 14 through the notch hole 47a. Positioning holes provided on the inner wall 15A with positioning pins 41 and 42 provided on the image forming unit 14.
Insert into 39 and 40 and fix with screws as appropriate. Thus, image formation is performed with the configuration of FIG. Image forming unit 14
When the image forming unit 14 is removed outside, the protective cover is closed to cover the exposed portion of the belt photoreceptor 1, and when the image forming unit 14 is attached to the image forming apparatus main body 15, the protective cover is opened as shown in FIG.
insert.

FIG. 5 shows a main part of the image forming unit 14.
A photocoupler PC1 composed of a light emitting element PC1A and a light receiving element PC1B is provided upstream of a portion facing the transfer unit 12, that is, an image transfer area, and a light emitting element PC2A and a light receiving element PC2B are provided downstream.
Is provided.

The light receiving element PC1B of the photocoupler PC1 is located inside the belt photoreceptor 1, and transmits the infrared light projected from the light emitting element PC1A located outside the paper feeding path 31 to the paper feeding path 31. The opening 31H and the opening 14 of the image forming unit 14
After passing through H, the light is further received through the belt photoreceptor 1.

The photocoupler PC1 is positioned so as to face out of the image range of the transfer paper P and can always detect a constant light amount regardless of the image density. It is possible to determine the type of the transfer paper P transported along the paper path 31.

Therefore, it is very easy to detect a transfer material close to a transparent material such as a transparency used in an overhead projector (OHP) or the like, and the detection signal is input to the CPU as shown in FIG. By controlling the fixing temperature or the transfer speed of the transfer material in this way, it is possible to form an image with rich gloss and good contrast.

On the other hand, the light-emitting element PC2A and the light-receiving element PC2B constituting the photocoupler PC2 are both arranged in parallel in the width direction inside the belt photoreceptor 1, and a member that is in close contact with the peripheral surface through the belt photoreceptor 1 is red. The detection is performed based on the reflectance of external light.

Since the photocoupler PC2 is also disposed in the non-image area of the belt photoreceptor 1 similarly to the photocoupler PC1, the presence of the transfer paper P closely contacting the belt peripheral surface can be easily detected by a change in the amount of received light. I can do it.

Therefore, when the transfer paper P to which the image has been transferred is conveyed while being separated from the peripheral surface of the belt photoreceptor 1 and closely contacted, the abnormal condition of the conveyance is detected by detecting the transfer paper P by the photocoupler PC2. By inputting this signal to the CPU, it is possible to take measures to stop the operation of the drive system relating to the conveyance of the cover sheet for the jam warning and the transfer sheet P.

[0039]

According to the present invention, each detecting means used for detecting a transfer material can be compactly narrowed to a position close to the transfer material and further protected from toner adhesion. An image forming apparatus has been provided which can prevent a large transport trouble due to a jam due to the ability to accurately detect a material.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of an image forming apparatus of the present invention and a cross-sectional view of a part of a belt photoconductor enlarged.

FIG. 2 is a cross-sectional view of the image forming apparatus.

FIG. 3 is an exploded perspective view of an image forming unit and a laser writing unit.

FIG. 4 is a perspective view showing a state where a laser writing unit is fixed to an image forming apparatus main body and the image forming unit is removed.

FIG. 5 is a main part view of the image forming apparatus.

FIG. 6 is a block circuit diagram of a control system of the device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Belt photoreceptor 1a Transparent base 1b Photosensitive layer 6,611,61A, 61B, 61C, 61D Charger 7,7A, 7B, 7C Laser writing system unit 8,9,10,11 Developing device 12 Transfer device 13 Cleaning device 14 Image forming unit 15 Image forming apparatus main body 29 Paper cassette 34 Fixing roller PC1, PC2 Photocoupler PC1A, PC2A Light emitting element PC1B, PC2B Light receiving element P Transfer paper

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-107573 (JP, A) JP-A-62-15566 (JP, A) JP-A-1-279281 (JP, A) JP-A-2- 141773 (JP, A) JP-A-64-82049 (JP, A) JP-A-56-60943 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 550 G03G 15/00 510-534 G03G 15/04-15/043 G03G 15/05 G03G 21/00 350 G03G 21/00 370-500 G03G 21/16-21/18

Claims (6)

(57) [Claims] 1. An image forming apparatus comprising: an image forming body having a photosensitive layer formed on a rotatable closed-loop translucent substrate; and an image exposing unit disposed inside the image forming body. An image forming apparatus comprising: a transfer material detecting means provided upstream or downstream of an image transfer area of a body or inside or outside of a body, and performing jam control or type determination of the transfer material based on a detection signal from the detection means. . 2. The image forming apparatus according to claim 1, wherein said image forming body is a belt-shaped photoreceptor. 3. The image forming apparatus according to claim 1, wherein the image forming body is incorporated in an image forming unit that is detachable from the apparatus main body. 4. An image forming apparatus according to claim 1, wherein said image exposing means is detachably attached to said apparatus body integrally with said image forming unit. 5. The image forming apparatus according to claim 1, wherein said image exposing means is detachable from said image forming unit. 6. An image forming apparatus according to claim 1, wherein said image exposure means is fixed to an apparatus main body.