JPH0683148A - Image forming device - Google Patents

Abstract

PURPOSE:To dispose a detection member utilized for detection of the state of the surface of a photosensitive belt in the vicinity of the photosensitive belt without providing any exclusive space for it. CONSTITUTION:Among the detection members for the detection of the state of the surface of the photosensitive belt body 1, a photocoupler PC1 has light emitting element PC1A disposed outside the belt and light receiving element PC1B disposed inside the felt and the toner quantity on the belt is detected by transmitted light passing through the photosensitive belt 1 and the toner replenishing is started according to the detected result, and on the other hand, concerning a photocoupler PC2 and PC3, both the light emitting element and light receiving element are disposed inside the belt and residue toner, soiling, or position of contact of a photosensitive layer 1b is detected by reflected light passing through the photosensitive belt 1 and the image forming conditions are controlled by each.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention exposes the back side of a belt-shaped image forming body by an electrophotographic method, forms the belt-shaped image forming body together with a developing device, and forms a color toner image on the belt-shaped image forming body. The present invention relates to a color image forming apparatus for forming an image and transferring the toner image onto a 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 method, charging, exposing, developing and transferring are repeated for each color, and toner images of respective colors are superposed and transferred on a recording paper. I am trying to do it. For example, an electrostatic latent image for each color is formed on the photoconductor by using separation light of blue, green, red, etc. obtained through a color separation filter, and yellow, magenta, cyan and, if necessary, black toner It is known that a toner image of each color is formed by developing the toner image and the toner image of each color is transferred onto a recording paper to form a multicolor image.

Further, for example, Japanese Patent Application Laid-Open No. 56-144452, Japanese Patent Application No. 58-184381, and Japanese Patent Application Laid-Open No. 58-18 previously filed by the present applicant.
No. 3152 and Japanese Patent Application No. 58-187000 disclose that a plurality of toner images are superposed on the same photosensitive member and developed so that a single transfer process is sufficient, and the first toner image is developed. Other than the above, an image forming apparatus has been proposed which is developed in a non-contact manner.

Further, in order to reduce the size of the entire apparatus, a belt-shaped image forming body (hereinafter referred to as a belt photosensitive member) is stretched between two axes, and a plurality of toners of different colors are accommodated along the lower side thereof. A plurality of developing devices are arranged. While the belt photoconductor is rotated a plurality of times, latent images are formed on the belt photoconductor in accordance with the number of separated colors of the original image, and A color copy is obtained by transferring onto a transfer paper fed from a paper feed cassette in a cassette storage chamber provided on the lower side.

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 be run flat and the space can be effectively used. Further, the separation of the transfer paper is made good by providing the separation pole of the transfer paper after the transfer on the small-diameter curvature portion which makes the U-turn.

However, the belt photosensitive member is suspended in the main body of the image forming apparatus between the driving roller and the driven roller, and at the time of exchanging the belt photosensitive member, one or both of the driving roller and the driven roller are removed from the shaft and replaced. Is being done. At that time, since the developing device is also provided in the main body, a method of removing and replacing the belt photosensitive member after pulling out the developing devices (four in the case of a color) from the main body is used. Further, as the exposure method for the belt photosensitive member, a laser writing means is mainly used from the outside of the belt photosensitive member.

[0007]

As described above, since it is necessary to repeat the transfer cycle for each color, the size of the entire apparatus becomes large, the image forming process becomes complicated, a loss of operation time occurs, and a repetitive operation occurs. Since the toner images of the respective colors are displaced, it is difficult to guarantee the accuracy of image formation. Further, when the color toner is subjected to the second and subsequent image exposures, since the toner image previously developed is always present, the image exposure light irradiated to the area of the toner image where the toner adheres. However, there is a problem in that it cannot be sufficiently transmitted through the photoconductor. Further, even in the image forming apparatus using the belt-shaped image forming body configured to improve the size increase, even if the size reduction is solved, the image forming apparatus may be used in the photoconductor during the image exposure of the second and subsequent colors of the color toner. Means for sufficiently transmitting light have not been solved, which has been a major obstacle to color image formation. Further, as described above, the belt photosensitive member is attached to the main body via the drive roller and the driven roller, and the belt photosensitive member cannot be removed from the main body unless the roller is removed from the shaft. There was a great deal of trouble in replacing. Further, if a color developing device is provided at the same time, it is necessary to pull out and remove four developing devices from the main body. At that time, the developer and the belt photosensitive member come into contact with each other, and the developer falls into the machine or scatters. It was a cause of soiling the inside of the device. Further, a belt electrode for giving an electric charge to the belt photosensitive member is also fixed in the apparatus and is arranged close to the belt photosensitive member. In this case, in particular, when a new belt photosensitive member is attached to the driving roller and the driven roller and set in the apparatus, there is a risk that the belt electrode contacts the photosensitive surface of the belt photosensitive member, so that the belt electrode must be removed. As described above, it takes much time and effort to replace the belt photosensitive member. Further, since the exposure means is provided outside the belt photosensitive member, there is a drawback that the entire apparatus is upsized.

Further, since each detecting means or the like provided for detecting the surface condition of the belt photosensitive member is also installed on the outer peripheral portion of the belt photosensitive member, there is a possibility that toner, dust or the like adheres to lower the sensitivity. In addition, there is a problem in that it is not possible to improve the detection accuracy because it is impossible to place it close to the photosensitive surface due to space limitations.

The present invention solves this problem and improves as a result.
Protect the photoconductor's detection means from the adhesion of toner and dust,
Further, it is an object of the present invention to provide an image forming apparatus which can be arranged close to the photoconductor and thereby can improve the detection accuracy.

[0010]

The above object is to provide an image forming body in which a photosensitive layer is formed on a rotatable transparent substrate having a closed loop shape, and an image exposing means is arranged inside the image forming body. In the image forming apparatus, a detection means for detecting the surface state of the photosensitive layer is provided inside or inside and outside the image forming body, and the image forming condition is controlled by the detection information from the detection means. Achieved by the forming device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an explanation will be given based on an embodiment shown in the accompanying drawings of the present invention.

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

Reference numerals 4, 4a, 4b and 4c are guide members fixed to the main body of the apparatus so as to be inscribed in the lower side of the belt photosensitive member 1, and 5 are tension members for inwardly contacting the belt photosensitive member 1 to bring them into a tensioned state. 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 photosensitive member 1.

6 is a scorotron charger as a charging means, 6
A is a cleaner for cleaning the wire of the charger 6. Reference numeral 7 is a laser writing system unit which is an image exposing means. In addition to the illustrated optical system, the laser writing system unit 7 may be an optical system in which a light emitting portion and a converging optical transmission body are integrated.

Numerals 8, 9, 10, and 11 are developing devices as a plurality of developing means respectively containing developing agents of different colors, for example, developing agents of yellow, magenta, cyan and black. The guide members 4, 4a, 4b, 4c are arranged to face the photosensitive layer 1b of the belt photosensitive member 1 inscribed therein. The developing devices 8 to 11 are provided with developing sleeves 8A, 9A, 10 which maintain a predetermined gap with the photosensitive layer 1b of the belt photosensitive member 1.
A and 11A are provided, and the latent image on the photosensitive layer 1b is visualized by a non-contact developing method. Unlike the contact development, the non-contact development has an advantage that the movement of the belt photosensitive member 1 is not hindered.

Reference numeral 12 is a transfer device, 12A is a charge eliminating bar, and 13 is a cleaning device. Blade 13A of cleaning device 13
The toner transport roller 13B keeps the photosensitive layer 1b during the image formation.
Is kept at a position separated from the surface of the photosensitive layer 1b and is pressed against the surface of the photosensitive layer 1b as shown in the figure only during cleaning after image transfer.

The color image forming apparatus includes a belt photosensitive member 1 suspended from the driving roller 2 and a driven roller 3.
A laser writing system unit 7 of exposure means, a developing device 8,
9, 10, 11 and the charger 6 are configured as an integrated image forming unit 14 as shown in FIG. 1, and the image forming unit 14 is mounted on the guide members 16, 17, 18 provided in the main body 15 of the image forming apparatus. Secure with screws. The laser writing system unit 7 includes guide members 19 and 20 provided in the image forming unit 14.
It is placed and fixed on. Reference numeral 21 denotes a protective cover that is openably and closably attached to the outside of the image forming unit 14. When the image forming unit 14 is detached, the protective cover 21 is rotated in the closing direction about a rotation shaft 21A by a spring member or the like (not shown). Is provided so as to protect the belt photosensitive member 1 exposed to the transfer device 12. A cover 22 is attached to the exposure slit 7a of the laser writing system unit 7 so as to be openable and closable when it is removed. Further, it is provided with a structure which is closed by a spring (not shown).

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

The guide members 16 and 17 are fixedly installed on two stays 24 and 25 provided in the main body 15 of the image forming apparatus.
As a method of driving the developing units 8, 9, 10, and 11, a coupling C is provided so as to project from each of the developing units, and a clutch (not shown) is provided by a drive source in which the drive motor M is separately provided.
The operation is switched by to drive. 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 body
When a color signal output from an image reading device separate from 15 is input to the laser writing system unit 7, a laser beam generated by a semiconductor laser (not shown) in the laser writing system unit 7 is driven by a drive motor. The fθ lens 27 is rotated and scanned by the polygon mirror 27B rotated by 27.
The optical path is bent by the mirror 27D via C and is projected through the transparent base 1a onto the peripheral surface of the photosensitive layer 1b of the belt photosensitive body 1 to which electric charges have been previously applied by the charger 6 as a charging means to form 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 is on the peripheral surface of the photosensitive layer 1b of the belt photosensitive member 1. To scan. Therefore, 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 conveyance of the belt photosensitive member 1 by the sub-scanning. This latent image is developed by the developing device 8 in which yellow (Y) toner (visual medium) is loaded in the developing means to form a toner image 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 recharged by the charger 6, and then the second color signal output from the signal processing unit 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 surface of the drum 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 further formed on the belt surface by the developing device 11 having black toner. .

A DC or AC bias is applied to the developing sleeves 8A, 9A, 10A, 11A of the developing units 8, 9, 10, 11 for jumping development with a two-component developer as a developing means. The development is performed in a non-contact manner on the photosensitive layer 1b whose base is grounded. As the development, non-contact development using a one-component developer can be used.

As described above, the photosensitive layer 1b of the belt photosensitive member 1
The color toner image formed on the peripheral surface of is transferred to the transfer paper P. The transfer paper P is sent from the paper feed cassette 29 in the 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 the friction of the paper feed roller 30, and the timing roller 32. After that, the image is formed on the photosensitive layer 1b of the belt photosensitive member 1 and supplied to the transfer device 12 at the same timing. As the separating means for the transfer paper P, a separating roller 33 is used.

As described above, the transfer sheet P supplied to the transfer unit 12 and subjected to image transfer and charge removal is more reliably transferred from the photosensitive layer 1b which rapidly changes its direction (small-diameter curvature) along the drive roller 2. After being separated and directed to the upper side, the image is fused by the fixing roller 34, and then discharged onto the discharge tray 36 via the discharge roller 35 and stacked.

On the other hand, the photosensitive layer 1 which has been transferred to the transfer paper P
In b, the residual toner is removed in the cleaning device 13 in which the blade 13A and the toner transport roller 13B are brought into pressure contact with each other by continuing the transport. After the cleaning is completed, the blade 13A is separated again, so that the toner carrying roller 13B removes the toner accumulated on the tip portion of the blade 13A a little later, and then the toner carrying roller 13B is separated to start a new image forming process.

Further, the respective tray transport pipes 151 of the corresponding toner hoppers 38 are automatically connected to the respective developing devices 8, 9, 10, 11 so that the toner is replenished.

Further, the apparatus serves as a paper feeding means for feeding the transfer paper to the paper feeding path 31, and a first paper feeding means for manually feeding paper from the openable manual feed guide plate 37 on the side of the apparatus main body. It is provided with 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 system unit 7 described in FIGS. 1 and 2 are detached from the image forming apparatus main body 15, and an inner wall 15A provided in the image forming apparatus 15 is shown. Unit positioning holes 39, 40 are provided in the unit 7, and the unit 7 is provided with positioning pins 41, 42 inserted into the unit positioning holes 39, 40 and positioned 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 of the laser writing unit 7 are provided in a part of the inner wall of the image forming unit 14 to perform positioning. Positioning pins 45 and 46, which are inserted into the holes 43 and 44 and positioned, are provided in the laser writing system unit 7, and an insertion hole 47 into which the laser writing system unit 7 can be inserted is opened in the front wall of the image forming unit 14. 3, the laser writing system unit 7 is inserted in the direction of the arrow in FIG. 3, and the positioning pins 45 and 46 are inserted into the positioning holes 43 and 44 in the image forming unit 14 for positioning. When the laser writing system unit 7 is inserted, the laser writing system unit 7 is placed and guided by the guide members 19 and 20 and positioned accurately. Further, a plurality of positioning pins 50 provided in the insertion direction are provided in a front plate member 49 provided with handles 47, 48 provided in the front of the insertion direction of the laser writing system unit 7, and an image forming unit is provided.
The positioning pin 50 is inserted into the hole 51 provided so as to oppose the laser writing system unit 14, and the laser writing system unit 7 is accurately installed at a predetermined position in the image forming unit 14. The attaching / detaching direction of the image forming unit 14 is not particularly limited, and the image forming unit 14 may be attached / detached in the front / rear direction or the lateral direction.

In FIG. 4, 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 main body 15 of the image forming apparatus. As shown in FIG. 4, a cutout hole 47a is provided on the rear side in the insertion direction of the image forming unit 14, and the image forming unit 14 is provided with a handle 14B. , 14C, and insert into the image forming apparatus main body 15 in the direction of the arrow. At this time, the laser writing system unit 7 is inserted into the image forming unit 14 through the cutout hole 47a. Positioning pins 41 and 42 provided on the image forming unit 14 are provided on the inner wall 15A.
Insert into 39 and 40, and fix with screws as appropriate. In this way, image formation is performed with the configuration of FIG. The image forming unit 14
When the image forming unit 14 is removed to the outside, the protective cover is closed to cover the exposed portion of the belt photosensitive member 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 the drawing.
insert.

FIG. 5 shows the image forming unit 14. In the image forming apparatus of the present invention, the light emitting element PC1A is provided on the portion of the belt photosensitive member 1 facing the transfer device 12, that is, on the upstream side of the image transfer area. A photocoupler PC1 including a light receiving element PC1B, and light emitting elements PC2A and P2 on the downstream side.
It includes photocouplers PC2 and PC3 respectively composed of C3A and light receiving elements PC2B and PC3B.

Light receiving element PC1 of the photocoupler PC1
B is located inside the belt photosensitive member 1 and receives infrared light projected from the light emitting element PC1A located outside the belt photosensitive member 1 through the belt photosensitive member 1.

The photocoupler PC1 is a belt photosensitive member 1.
The patch image is located in a portion facing the patch image formed on the first surface, and a constant light amount can always be detected through the belt photosensitive member 1 regardless of the configuration of the image to be formed. It is possible to detect the fluctuation of the above toner amount.

A toner amount detection signal from the photocoupler PC1 is input to the CPU of the control circuit shown in FIG. 6, and when the detected toner adhesion amount fluctuates with respect to a reference value of 1.0 mg / cm ^2, for example. Corresponds to the toner amount detected at the start of the image forming process that is performed thereafter.
The operating conditions of at least one of the image forming elements shown in FIG.

[0036]

[Table 1]

That is, the detected toner adhesion amount is 0.8 m.
In case of g / cm ² , transfer current is 0.5mA when transferring images.
To 0.55 mA, a charging voltage from -800 V to -850 V at the time of new charging, or a developing bias voltage from 2.0 KV to 2.2 KV. One or more measures are taken.

In parallel with this, when the toner amount detection signal to be sent to the photocoupler PC1 indicates that the toner is insufficient, the toner hopper 38 is moved to start the replenishment of toner to each of the developing devices 8-11. However, the replenishment is continued until the recovery of the toner amount is detected.

The toner amount is controlled by specifying a part of the image surface based on the image information obtained at the time of reading the image in addition to the detection signal obtained from the above-mentioned patch image and detecting the image surface. It is also possible to carry out by the result of comparison of the detection signal obtained from

On the other hand, the photo couplers PC2 and PC3
Are the light emitting elements PC2A and PC3A and the light receiving element PC2.
B and PC3B are arranged side by side in the width direction inside the belt photosensitive member 1, and the surface state of the photosensitive layer through the belt photosensitive member 1 is detected by the reflectance of infrared light.

The photocoupler PC2 detects the amount of residual toner on the belt photoreceptor 1 after transfer and inputs it to the CPU, and compares it with the amount of toner before transfer detected by the photocoupler PC1 to compare the image. The transfer rate of the image is kept constant by detecting the transfer rate and controlling the transfer voltage of the transfer device 12 or the bias voltage applied to each developing device.

Further, the photocoupler PC3 detects the bonding position of the photosensitive layer 1C of the belt photosensitive member 1 by detecting the bar code, and the laser as an image exposing portion is formed so that an image is formed while avoiding the bonding position. The timing at which image writing is started by the writing system unit 7 is controlled.

The above-mentioned photocouplers PC2 and PC
In addition to the use example described above, it is also possible to detect the cleaning failure by the cleaning device 13 by detecting the dirt on the belt photosensitive member 1 itself.

Further, as one of detection means for detecting the surface condition of the photosensitive layer 1b, an electrode plate E is installed on the inner wall of the cartridge outside the belt photosensitive member 1 as shown in FIG. The charge capacity of the layer 1b is sent to the measuring circuit C built in the laser writing system unit 7 inside the belt photosensitive member 1 through the lead wire L to detect the charge potential of the photosensitive layer and the signal of the charger 6 is charged by the signal. It is also possible to control the voltage.

[0045]

According to the present invention, each detecting means used for detecting the surface condition of the belt photosensitive member can be compactly placed at a position close to the belt photosensitive member and can be protected from toner adhesion. As a result, it is possible to provide an image forming apparatus capable of always forming a high-quality image by the ability of accurately detecting the surface state of the photoconductor.

[Brief description of drawings]

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

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 system unit.

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

FIG. 5 is a cross-sectional configuration diagram of an image forming unit.

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

[Explanation of symbols]

 1 Belt Photosensitive Member 1a Transparent Base 1b Photosensitive Layer 6,611, 61A, 61B, 61C, 61D Charging Device 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 feeding cassette 34 Fixing roller PC1, PC2, PC3 Photo coupler PC1A, PC2A, PC3A Light emitting element PC1B, PC2B, PC3B Light receiving element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G03G 15/08 7810-2H 21/00 111 116 H04N 1/29 C 9186-5C

Claims (5)

[Claims] 1. An image forming apparatus comprising an image forming body having a photosensitive layer formed on a light-transmitting substrate having a rotatable closed loop shape, and an image exposing unit provided inside the image forming body. An image forming apparatus characterized in that detection means for detecting the surface condition of the photosensitive layer is provided inside or inside and outside the formed body, and image forming conditions are controlled by detection information from the detection means. 2. The image forming apparatus according to claim 1, wherein the detection information relates to a toner amount of the photosensitive layer. 3. The image forming apparatus according to claim 1, wherein the detection information is related to a bonding position of the translucent substrate. 4. The image forming apparatus according to claim 1, wherein the detection information relates to a degree of stain on the photosensitive layer. 5. The image forming condition is any one of a charging condition of the photosensitive layer, an image exposing condition, a developing condition, a transferring condition and a charge eliminating condition.
Any one of the image forming apparatuses.