JP2001051521A - Color image forming equipment - Google Patents

Abstract

(57) Abstract: Provided is a color image forming apparatus that simplifies a driving mechanism and reduces costs while maintaining image quality. A transfer holder holding a transfer roller is provided.
The cam 72 and 82 rotate the cam 72 and 82, respectively, to move the 0 contact / separation lever 70B and the contact / separation lever 80B of the cleaning holder 80 holding the cleaning blade 16A of the intermediate transfer belt. The cams 72 and 82 are driven by a solenoid 91 which is the same drive source.

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 having an intermediate transfer member, such as a color copying machine, a color printer, and a color facsimile.

[0002]

2. Description of the Related Art Conventionally, toner images of respective colors formed on a photoreceptor are sequentially superimposed and transferred to the same position on an intermediate transfer member such as an endless belt, and the transferred image is transferred to transfer paper for fixing. In the image forming apparatus of the type that obtains a full-color image by performing, a cleaning device that cleans residual toner on the intermediate transfer body and a transfer device that transfers a toner image from the intermediate transfer body to transfer paper are provided by different drive sources. The contact / separation operation is performed.

[0003] This is because, when the transfer device and the cleaning device are arranged at a distance from each other on the intermediate transfer member, if the cleaning device is brought into contact at the same time in accordance with the transfer process, the end of the image that has not yet been transferred to the paper is obtained. This is because the toner image is also removed, so that it has to be controlled by a separate drive source.

However, usually, in an image forming apparatus having an intermediate transfer member, the number of parts is larger than that of other image forming mechanisms, so that the cost is increased, and
Since there are many drive mechanisms, the machine becomes complicated, the possibility of failure increases, and problems such as complicated maintenance services arise.

[0005]

As means for solving these problems, Japanese Patent Laid-Open Publication No. Hei 5-303288 discloses that the length of an intermediate transfer member is the total length of the length of the longest sheet and the distance from the cleaning device to the transfer device. In this case, the intermediate transfer cleaning device and the transfer device for transferring the toner image from the intermediate transfer member to the paper are integrated, and both of them are turned on / off at the same time.
It can be turned off.

However, in actual use, the problem of contamination of the transfer device when cleaning the residual toner on the intermediate transfer member during the jam processing and the pressure on the intermediate transfer member of each of the transfer device and the cleaning device are caused by the characteristics. There is a problem of pressure balance caused by completely different conditions, and there are many problems that must be solved for complete integration.

The present invention has been made in view of the above-mentioned conventional problems,
It is an object of the present invention to provide a color image forming apparatus which simplifies a driving mechanism and reduces costs while maintaining image quality.

[0008]

According to a first aspect of the present invention, there is provided a color image forming apparatus which develops a monochromatic toner image on an image carrier and forms a belt-shaped intermediate image. A color image forming apparatus of a type in which toner images of respective colors are sequentially superimposed on a transfer body to form a composite toner image, and then the composite toner image is collectively transferred to a sheet. A cleaning mechanism that can be brought into contact with and separated from the intermediate transfer body so as to clean residual toner on the intermediate transfer body; .

According to a second aspect of the present invention, in order to achieve the above object, the driving source can maintain a contact state of at least only the cleaning mechanism.

According to a third aspect of the present invention, in order to achieve the above object, there is provided a control means for setting a position of the drive mechanism in a contact state only as a reference position of the drive source.

According to a fourth aspect of the present invention, in order to achieve the above object, when the image forming apparatus main body is started, when the cleaning mechanism alone is not in a contact state, the transfer mechanism collectively transfers the synthetic toner image onto paper. It is characterized by having means for applying an application bias having a polarity opposite to the application bias for transfer.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the color image forming apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a flexible belt-shaped photoreceptor serving as a belt-shaped image carrier, and the photoreceptor belt 1 is provided between rotating rollers 2 and 3 to drive the rotating rollers 2 and 3. Is conveyed clockwise. Reference numeral 4 denotes a charging charger as charging means, 5 denotes a laser writing system unit as image exposure means, 6 denotes three developing means containing yellow, magenta, and cyan color developers, that is, a rotary color developing device, and 7 denotes color developing. This is a black developing device which is provided separately from the developing device 6 and is a developing means for containing a black developer.

The laser writing unit 5 is housed in a holding housing provided with a slit-shaped exposure opening on the upper surface, and is incorporated in the lower part of the apparatus main body. A bottom plate 60 is provided above the paper feed cassette 17 and below the writing system unit 5. The writing system unit 5 is incorporated therein, and a main body side plate for supporting each unit is provided on the left and right sides in the axial direction of each roller described above. Assembled to the bottom plate 60.

The charging unit 4, the writing unit using the laser beam 5A, and the cleaning blade 15A of the photoreceptor belt 1 are located near one of the two rollers on which the photoreceptor belt 1 is mounted. It is provided.

Each of the color developing device 6 and the black developing device 7 has a developing roller which comes close to or in contact with the photosensitive belt 1 at a predetermined position, and develops a latent image on the photosensitive belt 1 by a non-contact developing method or a contact developing method. It has the function of visualizing the image. In the figure, reference numeral 10 denotes an intermediate transfer belt as an intermediate transfer member,
The intermediate transfer belt 10 is provided between the rotation rollers 11 and 12 and is inclined. The intermediate transfer belt 10 is conveyed counterclockwise by driving the rotation rollers 11 and 12. The photoreceptor belt 1 and the intermediate transfer belt 10 are in contact with each other at a portion below the inclined belt surface of the intermediate transfer belt 10, and the first visible image on the photoreceptor belt 1 is applied to the bias provided in the intermediate transfer belt 10. The image is transferred onto the intermediate transfer belt 10 by the brush 13 (1
By repeating the same process, the second visualization, the third visualization, and the fourth visualization are superimposed on the intermediate transfer belt 10 to correct the positional deviation. Transcribed so as not to occur. Intermediate transfer belt 1
A transfer roller 14 serving as a secondary transfer member is provided above the 0 rotation roller 11 so as to come into contact with and separate from the intermediate transfer belt 10.

In FIG. 1, reference numeral 15 denotes a cleaning device including a cleaning blade 15A for the photosensitive belt 1, 16 denotes a cleaning device for the intermediate transfer belt 10, and a cleaning blade 16A of the cleaning device 16 denotes a surface of the intermediate transfer belt 10 during image formation. It is kept at a more distant position and is brought into pressure contact with the surface of the intermediate transfer belt 10 as shown in the figure only during cleaning after the secondary transfer of the image.

FIG. 2 shows the internal structure of the color and black developing devices 6 and 7, and FIG. 3 is a perspective view of the color developing device 6. The rotary color developing device 6 includes a casing 21 as a rotating body.
Are provided rotatably about a rotation center O, and the casing 21 can be rotated clockwise by driving of a driving mechanism (not shown). In addition, the casing 21 has a yellow, magenta, and cyan developing unit 22 (-
Y, M, and C) are integrally held. The developing units 22 (-Y, M, C) of each color take the same form and the same operation.

A backup roller 35 is provided on the photoreceptor belt 1 bridged between the rotating rollers 2 and 3 so as to push one of two extending portions between the two rollers outward. The surface is vertical and the lower belt surface is slightly inclined.
The color developing device 6 is disposed below the color developing device.

At the developing position in the color developing device 6, the developing roller 23 rotates with the photosensitive belt 1 in the same direction as the moving direction of the photosensitive belt 1 at a predetermined linear velocity ratio.
The photoconductor belt 1 is disposed to face the photoconductor belt 1. Below the developing roller 23, a supply roller 25 made of an elastic material such as foamed polyurethane is rubbed with the developing roller 23 at the rubbing portion, and is rotated in the same direction as the developing roller 23 at a predetermined linear velocity ratio. Is provided. Also supply roller 2
A developing blade 26 made of a thin plate having a spring property such as stainless steel is provided on the downstream side in the rotation direction of 5 such that one end thereof is in contact with the developing roller 23. Further, a screw-shaped first toner conveying member 27 described later conveys the toner from the front side to the rear side in the drawing.

As shown in FIG. 3, a toner container 29 is provided in front of the developing device 6, and the first toner conveying member 27 having a screw shape is moved from the toner container 29 to the color developing device 6. Is arranged in parallel with the developing roller 23 and the supply roller 25 up to the side plate of the developing unit 22 behind, so that the toner is conveyed from the near side to the rear side in the drawing. In addition to being interlocked with the developing roller 23 and the supply roller 25, the developing roller 23 and the supply roller 25 rotate at a predetermined linear velocity ratio. The toner supplied on the supply roller 25 is supplied to the surface of the developing roller 23 by the supply roller 25, charged, and carried on the surface of the developing roller 23. The toner carried on the surface of the developing roller 23 is thinned by the developing blade 26 to develop the electrostatic latent image formed on the surface of the photoreceptor belt 1.

By the way, the toner not used in the developing step is conveyed by the first toner conveying member 27 to the rear end portion of the developing device 6 on the side opposite to the toner container 29, where the developing roller 23 and the supply roller 25 are supplied. Reaches the toner circulating portion provided outside the effective diameter portion in the axial direction, and the toner falls to the lower portion of the developing unit 22 by gravity. Developing unit 22
At the lower part, a second toner conveying member 28 also having a screw shape is disposed in parallel with the developing roller 23, the supply roller 25, and the first toner conveying member 27, and has a direction opposite to that of the first toner conveying member 27. Then, the toner that has not been used in the developing process is transported to the toner storage unit 29. By appropriately setting the toner transport amount of the first toner transport unit 27 and the second toner transport member 28, the toner supply amount on the supply roller 25 can be reduced without detecting the toner amount in the developing unit 22 or performing complicated toner supply amount control. To supply toner to the photoreceptor belt 1
Is a small color developing device 6 having a small section occupation ratio. The toner cartridge 30 shown in FIG. 3 is detachable from the toner container 29 so that the toner cartridge 30 can be replaced when toner is supplied.

The black developing device 7 is a developing device of a type in which black toner is contained in a developing container 41. The developing device is formed integrally as a so-called developing cartridge in which the life of the developing device is replaced when the toner runs out. is there. Like the developing unit 22 of the color developing device 7, the developing roller 23
The photoreceptor belt 1 is arranged to face the photoreceptor belt 1 so as to rotate in the same direction as the moving direction of the photoreceptor belt 1 at a predetermined linear velocity ratio. Behind the developing roller 23, a supply roller 25 made of an elastic material such as foamed polyurethane is rubbed with the developing roller 23 in the rubbing portion, and is rotated in the same direction as the developing roller 23 at a predetermined linear velocity ratio. Further, a developing blade 26 made of a thin plate having a spring property such as stainless steel is provided so that one end thereof is in contact with the developing roller 23. In the developing container 41, a first agitator 42 and a second agitator 43 for conveying and stirring the toner toward the supply roller 25 and the developing roller 23 are provided. The black developing device 7 can be moved toward and away from the photoreceptor belt 1, separates from the photoreceptor belt 1 during non-development, and approaches or comes into contact with the photoreceptor belt 1 during development.

The process cartridge 31 includes a photosensitive belt 1, a charging charger 4, an intermediate transfer belt 10,
The cleaning device 15 and the cleaning device 16 are integrated, and the waste toner collecting container 36 is incorporated in the process cartridge 31 so as to be exchangeable.

Here, the waste toner scraped off from the photoreceptor belt 1 by the cleaning blade 15A is conveyed from the cleaning device 15 to the waste toner collecting container 36, and is sent from the intermediate transfer belt 10 to the cleaning blade 1
The waste toner scraped off at 6A is conveyed in the sectional front side by an auger 16B provided in the cleaning device 16, and further transferred to the waste toner collecting container 36 by a conveying member (not shown) provided on the front side of the process cartridge 31. It is transported and put together. This allows
Since the waste toner can be collected without replacing the process cartridge 31, the life of the process cartridge can be extended.

An image forming process by the above-described color image forming apparatus is performed as follows. The laser beam 5A generated by the laser writing unit 5 is
Exposure is performed on the circumference of the photoreceptor belt 1 that has been uniformly charged in advance by the charging charger 4 serving as a charging unit, thereby forming an electrostatic latent image. Here, the image pattern to be exposed is a single-color image pattern when a desired full-color image is separated into yellow, magenta, cyan, and black. The formed three-color electrostatic latent images are developed by rotating the rotary type color developing device 6 with the yellow, magenta and cyan developing units successively opposed to the photoreceptor belt 1. Thus, a monochrome image is formed (at this time, the black developing device 7 is retracted to the non-developing position with respect to the photosensitive belt 1). The black electrostatic latent image is developed by the black developing device 7, developed and made monochromatic to form a monochromatic image. The monochrome image formed on the photoreceptor belt 1 is
Intermediate transfer belt 1 that rotates counterclockwise while contacting
0 are sequentially superimposed and transferred. Intermediate transfer belt 1
The images of yellow, magenta, cyan, and black superimposed on the image No. 0 are fed from the paper feed cassette 17 to the paper feed roller 18, the transport roller pair 19A, 19B, the registration roller pair 20A, 2
0B, and the transfer roller 1
4 is transferred. After the transfer is completed, the transfer paper is transferred to the fixing device 4.
9 to complete a full-color image.

FIG. 4 is a conceptual diagram showing the transfer roller and the contact / separation mechanism for cleaning according to the present embodiment. Transfer roller 1
Reference numeral 4 is rotatably held by the transfer holder 70, and rotates together with the rotating roller 11 of the intermediate transfer belt 10 when it comes into contact therewith. The transfer holder 70 has a rotation center shaft 70 </ b> A, and is urged in a direction in which the transfer holder 70 comes into contact with the rotating roller 11 by the force of a compression spring 71 incorporated in the vicinity of the holding portion of the transfer roller 14. At one end of the transfer holder 70, a contact / separation lever 70B for bringing the transfer roller 14 into and out of contact is provided, and a cam 72 acting on the contact / separation lever 70B is provided. The operation of contacting / separating the intermediate transfer belt 10 from / to the rotating roller 11 is performed.

Similarly, the cleaning device of the intermediate transfer belt 10 has a cleaning blade 16A held by a cleaning holder 80. The cleaning holder 80 has a rotation center shaft 80A.
Are biased in the direction of contact with the rotating roller 11 by the force of a compression spring 81 incorporated near the holding portion. At one end of the cleaning holder 80, there is provided a contact / separation lever 80B for bringing the cleaning blade 16A into and out of contact, and a cam 82 acting on the contact / separation lever 80B is provided. The operation of moving the 16A intermediate transfer belt 10 toward and away from the rotating roller 11 is performed.

The rotation center shafts 72A, 82 of the cams 72, 82
A is provided with gears 72B and 82B, respectively. The side of the cleaning blade contact / separation mechanism is connected via an idle gear 83 to a clutch gear 90A of a spring clutch 90 for controlling rotation. The shaft of the spring clutch 90 is rotated by a main body drive source by a gear connection (not shown), but the actuator of the solenoid 91 is engaged with a claw 90B provided on the spring clutch 90. In this state, the clutch gear 90A Is stopped without rotating.
When the solenoid 91 is momentarily operated, the actuator is disengaged from the claw 90B of the spring clutch 90, the power of the main body drive source is transmitted, and the clutch gear 90A makes one rotation and stops.
The gear ratio between the clutch gear 90A and the gears 72B and 82B is, for example, a ratio of 1: 4.
With the rotation, the gears 72B and 82B each make 1/4 turn (9
(0 degree). That is, the solenoid 9
In one operation, the cams 72 and 82 for contacting and separating the transfer roller 14 and the cleaning blade 16A are 90
Rotate degrees.

Each of the cams 72 and 82 has four levels of stop positions. However, at two successive levels, the cams 72 and 82 do not act on the respective contact / separation levers (= the contact state of the transfer roller 14 and the cleaning blade 16A). ), The contact / separation lever 70 for retracting the transfer roller 14 and the cleaning blade 16A at the other two levels.
B, 80B.

FIGS. 5A to 5D are conceptual diagrams showing the operations of the transfer roller and the cleaning contact / separation mechanism of the above-described embodiment. FIG. 5A is a diagram showing a reference position of the apparatus in which the cleaning blade 16A is in contact and the transfer roller 14 is in the retracted state. As a means for detecting the reference position, a filler 84 having a partially convex shape having the same axial center as the cam 82 is provided, and a transmission sensor 85 is provided so as to detect the convex shape when the apparatus is at the reference position. Is placed and controlled. Since the state shown in FIG. 5A is the reference position of the apparatus, the toner adhering to the intermediate transfer belt 10 can be immediately removed without soiling the transfer roller 14 when the apparatus main body rises.

From the above state, after the aging operation at the start of the apparatus main body, the first visual image described above is transferred onto the intermediate transfer belt 10 by the bias brush 13 provided in the intermediate transfer belt 10, and Before the head of the image reaches the cleaning section, the solenoid 91 operates, and the cams 72 and 82 for contacting and separating the transfer roller 14 and the cleaning blade 16A rotate 90 degrees, respectively, but the cam 82 contacts only the cleaning device section. Release lever 80
B, and retracts the cleaning blade 16A (FIG. 5B).

Then, in the above state, the second visualized image, the third visualized image, and the fourth visualized image are superimposed on the intermediate transfer belt 10 and transferred so as not to cause a positional shift. . The yellow, magenta, cyan, and black images superimposed on the intermediate transfer belt 10 are transferred by the transfer roller 14 in timing with the transfer paper conveyed to the transfer unit. This state is shown in FIG. At this time, the solenoid 91 operates in the same manner, and the cams 72, 8 for bringing the transfer roller 14 and the cleaning blade 16A into and out of contact with each other.
2 rotate by 90 degrees, however, the cam 72 does not act on the contact / separation lever 70B only in the transfer roller device portion, and the transfer roller 14 is brought into contact. Next, the solenoid 91 operates to remove the transfer residual toner on the intermediate transfer belt 10, and the cams 72 and 82 for contacting and separating the transfer roller 14 and the cleaning blade 16A rotate 90 degrees, respectively. Only the cam 82 does not act on the contact / separation lever 80B, the cleaning blade 16A comes into contact,
The removal of the residual toner on the upper part of the intermediate transfer belt 10 is started (FIG. 5D).

As a final step, the transfer roller 14 is retracted at the timing when the rear end of the transfer paper conveyed to the transfer section passes the transfer roller 14, but the operation is the same, the solenoid 91 operates, and the transfer roller 14 and the cleaning roller are cleaned. The cams 72 and 82 for contacting and separating the blade 16A are 90
However, the cam 72 acts on the contact / separation lever 70B only in the transfer roller device, and the transfer roller 14 is retracted.
The state returns to (A). The above is the operation of the normal image forming process.

After a paper jam occurs, the transfer roller 14 is not always stopped in a state where the transfer mechanism 14 is in contact with only the cleaning mechanism which is the reference position. At the time of the restart, that is, when it is detected that the apparatus is not at the reference position, the solenoid is applied to the transfer roller 14 while applying an application bias having a polarity opposite to the application bias for transfer to the transfer roller 14 so as to be at the reference position. Keep running 91. During this time, the transfer roller 14 may be in contact with the intermediate transfer belt 10 on which the untransferred image is placed. However, since the reverse bias is applied to the transfer roller 14,
Adhesion of toner to the transfer roller 14 can be prevented, and abnormal images such as stains on the back of transfer paper can be prevented.

[0035]

According to the first aspect of the present invention, there is provided a color image forming apparatus.
As described above, the transfer mechanism that can contact and separate from the intermediate transfer member that collectively transfers the synthetic toner image onto the paper and the cleaning mechanism that can contact and separate from the intermediate transfer member that cleans the residual toner on the intermediate transfer member Since the operation is performed by the same drive source, the number of electric and electronic components, which increase the cost, such as a suction solenoid generally used as a normal contact / separation mechanism and an electromagnetic clutch due to rotational operation, is reduced from two to one. Since it can be reduced, the mechanism can be simplified and the cost of the apparatus main body can be reduced.

In the color image forming apparatus according to the second aspect, as described above, at least the contact state of only the cleaning mechanism is maintained in the same driving source. After the paper jam occurs, even if untransferred toner remains on the intermediate transfer member and the toner must be cleaned by the cleaning device when the apparatus is restarted, the transfer device may not contact the intermediate transfer member. This has the effect of preventing toner from adhering to the transfer device due to contact, and preventing abnormal images such as stains on the back of the transfer paper.

According to the third aspect of the present invention, as described above, by controlling the contact state of only the cleaning mechanism so as to be at the reference position of the same drive source mechanism, the common effects can be obtained. In addition, at the time of image formation, the distance from the cleaning position of the intermediate transfer member to the primary transfer position at which the toner images of the respective colors are successively superimposed on the intermediate transfer member to form a composite toner image is immediately changed as long as the intermediate transfer member moves. It is possible to start the image forming process, which has the effect of leading to an improvement in the so-called first print speed.

According to the fourth aspect of the present invention, as described above, when the main body of the apparatus is not in contact with only the cleaning mechanism when the apparatus main body is started, the composite toner image is transferred to the transfer mechanism at once by the transfer mechanism. The application bias is applied to the transfer mechanism with a polarity opposite to that of the application bias.In addition to the above-described common effects, even if the transfer mechanism is in contact with the paper after the paper jam occurs, the transfer mechanism is applied to the transfer mechanism. This prevents the toner from adhering to the transfer paper and prevents an abnormal image such as stains on the back of the transfer paper.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a color image forming apparatus of the present invention.

FIG. 2 is a cross-sectional view illustrating an internal configuration of a color and black developing device of the color image forming apparatus of FIG.

FIG. 3 is a perspective view of a color developing device of the color image forming apparatus of FIG.

FIG. 4 is a conceptual diagram illustrating a transfer roller and a cleaning contact / separation mechanism of the color image forming apparatus of FIG. 1;

FIG. 5 is a conceptual diagram illustrating operations of a transfer roller and a cleaning contact / separation mechanism of the color image forming apparatus of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2, 3 rotating roller 4 charging charger 5 laser writing system unit 5A laser beam 6 color developing device 7 black developing device 8 front frame 8A front frame opening 8B, 8C shaft 9 main body frame 9A boss opening 10 Intermediate transfer belt 11, 12 Rotating roller 13 Bias brush 14 Transfer roller 15 Cleaning device 15A Cleaning blade 16 Intermediate transfer belt cleaning device 16A Cleaning blade 17 Paper feed cassette 18 Paper feed rollers 19A, 19B Transport roller pair 20A, 20B Registration roller Pair 21 Casing 22 Color developing unit 23 Developing roller 25 Supply roller 26 Developing blade 27 First toner transport member 28 Second toner transport member 29 Toner storage unit 30 Toner cartridge 31 Process cartridge 35 Backup roller 36 Waste toner collecting container 41 Developing container 42, 43 Agitator 49 Fixing device 60 Bottom plate 70 Transfer holder 70A Transfer rotation center axis 70B Contact / separation lever 71 Compression spring 72, 82 Cam 72B, 82B Gear 80 Cleaning holder 80A Rotating center axis of cleaning holder 80B Contact / separation lever 81 Compression spring 83 Idle gear 84 Filler 85 Transmission sensor 90 Spring clutch 90A Clutch gear 90B Claw 91 Solenoid

Claims (4)

[Claims] 1. A monochromatic toner image is developed on an image carrier, and a toner image of each color is sequentially superimposed on a belt-shaped intermediate transfer member to form a composite toner image. Then, the composite toner image is collectively transferred to a sheet. A color image forming apparatus having a transfer mechanism capable of contacting and separating from the intermediate transfer body and a cleaning mechanism capable of contacting and separating from the intermediate transfer body so as to clean residual toner on the intermediate transfer body. A color image forming apparatus wherein the transfer mechanism and the cleaning mechanism are brought into and out of contact by the same drive source. 2. The color image forming apparatus according to claim 1, wherein the driving source can maintain at least a contact state of only the cleaning mechanism. 3. A color image forming apparatus according to claim 2, further comprising control means for setting a position of said cleaning mechanism in a contact state only as a reference position of said drive source. 4. An application bias having a polarity opposite to an application bias for batch-transferring the synthetic toner image onto a sheet is applied to the transfer mechanism when the cleaning mechanism alone is not in a contact state when the main body of the image forming apparatus is started. 4. The color image forming apparatus according to claim 2, further comprising: