JPH10133452A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a positional deviation in each color and to form an image of high quality by making the position where the rotational fluctuation of an image carrier occurs because of the contact, separation or the like of an intermediate transfer body the same, at the time of attaining development with each different color. SOLUTION: The intermediate transfer belt of the intermediate transfer body 3 is rotated in the direction of an arrow B. The intermediate transfer belt of the intermediate transfer body 3 rockingly driven in the direction of an arrow C comes into contact with the photoreceptor drum of the image carrier 1, by the driving of a contact/uncontact driving means 4. After that, a toner image of the first color on the photoreceptor drum of the image carrier 1 is transferred to the intermediate transfer belt of the transfer body 3. Then, the intermediate transfer belt of the transfer body 3 rockingly driven in the direction opposite to the direction of the arrow C is separated from the photoreceptor drum of the image carrier 1, by the contact/uncontact driving means 4. After that, the intermediate transfer belt of the transfer body 3 is first reversely rotated by the rotation in the direction of the arrow B, to align the second color with a transferring position. Such an operation is repeated four times, to transfer the toner image onto the intermediate transfer belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an electrostatic latent image formed on an image carrier in a copying machine, a printer, a facsimile machine or a multifunction machine using an electrophotographic system. The present invention relates to an image forming apparatus in which toner images of different colors, which are developed by a plurality of developing devices, are sequentially superimposed on an intermediate transfer body, intermediately transferred, and then transferred to a transfer material to form an image.

[0002]

2. Description of the Related Art A conventional electrophotographic image forming apparatus such as an electrophotographic copying machine forms an electrostatic latent image on an image carrier and develops the electrostatic latent image with a plurality of developing devices. In general, toner images of different colors are obtained by performing the above operations, and the toner images of the respective colors are successively superimposed on an intermediate transfer body, and then intermediately transferred, and then transferred to a transfer material to form an image. In a conventional image forming apparatus, as means for reducing the impact of an intermediate transfer member or the like to suppress breakage, Japanese Patent Application Laid-Open No. 5-323
As disclosed in Japanese Patent Application Laid-Open No. 797/797, there is an apparatus in which the transfer roller is gradually pressed against the image carrier via the intermediate transfer body when the intermediate transfer body is replaced.

[0003]

However, in the conventional image forming apparatus, an intermediate transfer belt, which is an intermediate transfer member, is brought into contact with or separated from the image carrier after a predetermined time from the image writing start timing, so that the image bearing member is placed on the image bearing member. Is transferred to the intermediate transfer member, and when the intermediate transfer belt comes into contact with or separates from the image bearing member, and the rotation of the image bearing member fluctuates, the rotation fluctuation causes the development blur. And the problem that image quality is deteriorated occurs. That is,
When a developing device for developing a plurality of colors of toner is provided around the image carrier, such as a color copier, the electrostatic latent image formed on the image carrier is developed by the developing device. After the toner image is formed, the toner image is transferred to the intermediate transfer member. However, the timing at which the intermediate transfer member is brought into contact with or separated from the image carrier is set to a certain time from the image writing start timing. Rotational fluctuation of the image carrier occurs after a certain period of time as a reference, and the timing at which the rotational fluctuations occur differs depending on the arrangement position of the developing units based on the developing process of the toner developing units of each color, causing a development blur. was there. SUMMARY OF THE INVENTION The present invention has been made to solve the problem of the development blur caused by the rotation fluctuation of the image carrier as described above. It is an object of the present invention to provide an image forming apparatus in which a high-quality image is formed by eliminating the positional deviation of each color by setting the same position where the rotation fluctuation of the body occurs.

[0004]

In order to achieve this object, the present invention according to the first aspect of the present invention is directed to an image forming apparatus, comprising: an electrostatic latent image formed on an image carrier; In an image forming apparatus in which a toner image is sequentially superimposed on an intermediate transfer body and then intermediately transferred, and then transferred to a transfer material to form an image, an electrostatic latent image of a different color is formed rotatably supported. An image carrier and a different color toner image for developing an electrostatic latent image of a different color formed at a predetermined interval (L) on the image carrier rotating at a predetermined linear velocity (V) are arranged. A developing unit composed of a plurality of developing devices, an intermediate transfer body that is superimposed on toner images of different colors developed by the developing unit and sequentially intermediately transferred, and an intermediate transfer body is brought into contact with the image carrier to perform intermediate transfer. The timing of different colors sequentially formed on the image carrier. Characterized in that an image forming apparatus comprising a separation driving means for driving to lag the respective position of the toner image by a predetermined time (t). According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the contact / separation driving unit determines a timing at which the intermediate transfer member is separated from the image carrier after the intermediate transfer of the toner image. The image forming apparatus is characterized in that the image forming apparatus is driven so as to be separated by a predetermined time (t) from each position of a different color toner image sequentially formed on the body. According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the contact / separation driving unit sequentially forms timings of contacting or separating the intermediate transfer member on the image carrier on the image carrier. The predetermined time (t) is determined by each position of the different color toner images
(L) / (V) drive, where L is an interval between toner images of different colors formed on the image carrier,
V is a linear velocity (V) on the image carrier, and is an image forming apparatus. According to a fourth aspect of the present invention, in the image forming apparatus of the first, second or third aspect, the intermediate transfer member rotates in both the forward direction and the return direction when transferring a toner image of two or more colors. When a one-color toner image is transferred, it is rotated in one direction.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an image forming apparatus according to the present invention. This color copying machine includes a color scanner unit 20, a color printer unit 30, a paper feed unit 40, an image processing unit (not shown), and the like. The color scanner unit 20 includes an illumination lamp 20b, a mirror group 20
c and a lens 20d, and irradiates a document (not shown) on the contact glass 20a with light, and reflects the reflected light through a mirror group 20c and a lens 20d.
The image is read on each of the color separation lights, for example, blue, green, and red, and is converted into an electric signal. After reading the original image in this manner, a color change process is performed by an image processing unit (not shown) based on the blue, green, and red color separation image signal intensity levels obtained by the color scanner unit 20 to obtain black and cyan. , Magenta and yellow color image data. The color image data is converted into an optical signal by the color printer unit 30, and optical writing corresponding to the original image is performed by the laser beam via the polygon mirror 20f, the f / θ lens 20g, and the reflection mirror 20h, and An electrostatic latent image is formed on the timepiece 1.

A predetermined linear velocity (V) in the direction of arrow A
Black, cyan, magenta, and yellow developing units 2a, 2b, which are arranged around the photosensitive drum of the image carrier 1 rotating at a distance (L) on the surface of the drum.
The electrostatic latent image on the image carrier 1 is developed by the developing unit 2 composed of 2c and 2d, and the developed toner images of each color are transferred to the intermediate transfer belt of the intermediate transfer body 3 by driving the contact / separation drive unit 4. Is done. Note that the contact / separation driving unit 4 delays the intermediate transfer member 3 and the image carrier by a predetermined time (t) with respect to the position of the toner image of each color sequentially formed at a predetermined interval (L) on the image carrier 1. 1 is controlled so as to come into contact with
The separation between the intermediate transfer member 3 and the image carrier 1 is also delayed by a predetermined time (t) with respect to each position of the toner images of different colors sequentially formed at a predetermined interval (L) on the image carrier 1. By performing the control and superimposing the images four times to sequentially perform the intermediate transfer, a four-color superimposed color toner image is formed on the intermediate transfer belt of the intermediate transfer body 3. The predetermined time (t)
Can be represented by (t) = (L) / (V), where L
Is an interval between toner images of different colors formed on the image carrier 1, and V is a linear velocity (V) of the image carrier 1 on the photosensitive drum.

The four-color superimposed color toner image formed on the intermediate transfer belt of the intermediate transfer body 3 is
0 on the transfer paper (P) which is fed and fed by the registration roller 30a in synchronization with the transfer roller 30.
The transfer is performed by b.

The transfer paper (P) on which the four-color superimposed color toner image is further transferred is transferred to a fixing unit 30 by a transport unit 30c.
After the toner image is fused and fixed to the sheet, the sheet is discharged and stored by a sheet discharging roller 30e. 4 formed on the intermediate transfer belt of the intermediate transfer body 3
The intermediate transfer belt of the intermediate transfer body 3 rotates in the illustrated arrow B direction (forward direction) in order to prevent the transfer position of the toner image of each color of black, cyan, magenta, and yellow from being superposed. After the intermediate transfer belt of the intermediate transfer body 3 oscillatingly driven in the direction of arrow C shown in the drawing is brought into contact with the photosensitive drum of the image carrier 1 by the drive of the contact / separation drive means 4, the photosensitive body of the image carrier 1 The first color toner image on the drum is transferred to the intermediate transfer belt of the intermediate transfer body 3. next,
The intermediate transfer belt of the intermediate transfer body 3 driven to swing in the direction opposite to the arrow C shown in the figure by the contact / separation driving unit 4 is moved to the image carrier 1.
After being separated from the photosensitive drum, the intermediate transfer belt of the intermediate transfer body 3 rotates in the reverse direction by the amount previously rotated in the forward direction, and the second color is adjusted to the transfer position.
By repeating such an operation four times, a four-color superimposed toner image is intermediately transferred onto the intermediate transfer belt of the intermediate transfer body 3.

FIG. 2 is an explanatory view for explaining a main part of an image forming apparatus showing an embodiment of the present invention, and FIG. 3 is a perspective view of a main part of the image forming apparatus. 2 and 3, the opposing roller 4a, the tension roller 4b, the driving roller 4c, and the roller 4d of the contact / separation driving unit 4 stretch the intermediate transfer belt of the intermediate transfer body 3, and are driven by the driving roller 4c to indicate the arrow B shown in FIG.
It is supported in such a manner that it can be rotationally driven in the forward direction and the return direction opposite to the arrow B shown in the figure.
Opposing roller 4a opposing the photosensitive drum of image carrier 1
Is supported by a rotation support portion on the swing end side of a support member 4f that is swingably supported on a support shaft 4e, and the tension roller 4b is supported swingably on a support shaft 4g. The support member 4h is supported by a rotation support portion on the swing end side. The support member 4f and the support member 4h are brought into pressure contact with the cam member 4i by means of a biasing member (not shown) by surfaces facing each other.
The cam member 4i is an eccentric cam, and the cam member 4i
Is rotated half a distance, so that the support member 4f and the support member 4h maintain the same distance and can move in the same direction with respect to the photosensitive drum of the image bearing member 1, in other words, in the same direction. I have. A half-rotation step clutch 4k is attached to the rotation shaft 4j of the cam member 4i.
By the rotation of the drive motor 41, the cam member 4i is driven in a half-turn step.

FIG. 4 is a perspective view for explaining another main part of the image forming apparatus according to the present invention, in which an image of two or more colors is formed by driving a driving roller 4c by a stepping motor 4m. The intermediate transfer belt of the intermediate transfer member 3 is rotated in the direction of arrow B (forward direction) and in the direction opposite to the direction of arrow B (return direction). ).

FIG. 5 is an enlarged explanatory view for explaining another main part of the image forming apparatus according to the present invention. As shown in FIG. , A plurality of developing devices (black) 2a, a developing device (cyan) 2b, and a developing device (magenta)
2c and a developing device (yellow) 2d are provided. The distance between the developing roller 2e1, the developing roller 2e2, the developing roller 2e3, and the developing roller 2e4 is the same, and the length of the image carrier 1 on the photosensitive drum is a predetermined distance (L).
Installed away.

An image forming process of the image forming apparatus having the above-described configuration will be described. First, at the writing position indicated by the arrow C, the electrostatic latent image formed on the image carrier 1 reaches the first-color black developing device 2a by rotating the image carrier 1 in the direction of the arrow A. Visualize the electrostatic latent image. This visualized black toner image is the image carrier 1
Is further rotated in the direction of arrow A, moves in the direction of the intermediate transfer member 3, and comes into contact with the photosensitive drum of the image bearing member 1 after a predetermined time from the start of writing the black electrostatic latent image at the writing position C. Intermediate transfer is performed on the intermediate transfer belt of the body 3. Further, after a lapse of a predetermined time after the transfer to the intermediate transfer member 3, the intermediate transfer member 3 is separated,
The intermediate transfer member 3 and the image carrier 1 are separated from each other. Thereafter, after a lapse of a predetermined time (T) from the start of writing the black electrostatic latent image, a cyan electrostatic latent image is formed on the photosensitive drum of the image bearing member 1 at the writing position indicated by the arrow C, and the developing device 2b
However, the timing at which the cyan electrostatic latent image is visualized is based on the writing start time at the writing position C, and the electrostatic latent image reaches the black developing device 2a. Is performed later by an amount proportional to the distance (L) from the arrival at the black developing device 2a to the arrival at the cyan developing device 2b as compared with the time t. That is, assuming that the predetermined linear velocity of the image bearing member 1 on the photosensitive drum is (V), development is started later by (L) / (V).

Therefore, the timing at which the image bearing member 1 of the intermediate transfer belt of the intermediate transfer member 3 comes into contact with the photosensitive drum is delayed by a predetermined time (t) = (L) / (V). The effect of the rotation fluctuation caused by the contact of the intermediate transfer member 3 with the image carrier 1 on the development process occurs at the same timing as in the case of black development and the case of cyan development. Similarly, the timing at which the magenta electrostatic latent image is visualized is based on the write start time,
Compared with the time required for the electrostatic latent image to reach the cyan developing device 2b, the electrostatic latent image is performed later by an amount proportional to the distance (L) from the cyan developing device 2b to the magenta developing device 2c. As a reference, the writing is performed later than the time from the writing start time until the electrostatic latent image reaches the black developing device 2a by an amount proportional to the distance (2L). That is, assuming that the predetermined linear velocity of the image bearing member 1 on the photosensitive drum is (V), development is started later by (2L) / (V).

Therefore, as shown in FIG. 6, when the write start at the write position C is performed every T time, the contact signal of the intermediate transfer member 3 is (t) = (T) + (L).
/ (V), and the separation signal of the intermediate transfer member 3 is also generated every (t) = (T) + (L) / (V), so that cyan, magenta and yellow images can be visualized. In this case, the developing device contacts the photosensitive drum of the image carrier 1 at the same position of the electrostatic latent image as when a black image is developed despite the relative position of the developing device to the photosensitive drum. Then, when the intermediate transfer belt of the intermediate transfer member 3 comes into contact with the photosensitive drum of the image carrier 1, the visualized portion overlaps on the intermediate transfer belt of the intermediate transfer member 3. Similarly, at the timing when the intermediate transfer belt of the intermediate transfer member 3 is separated from the photosensitive drum of the image carrier 1, the visualized portion overlaps on the intermediate transfer belt of the intermediate transfer member 3. Since the rotation fluctuation of the photosensitive drum of the image carrier 1 at the time of contact of the intermediate transfer belt of the intermediate transfer member 3 and at the time of separation of the intermediate transfer belt 3 are the same, each of the rotation fluctuations is 4
The colors will match.

[0015]

According to the present invention, the image bearing member is formed at a predetermined interval (L) on the image carrier rotating at a predetermined linear velocity (V). Intermediate transfer in which different color toner images developed by a developing unit composed of a plurality of developing units arranged corresponding to different color toner images for developing different colors of electrostatic latent images are superimposed sequentially and sequentially. The timing at which the body is brought into contact with the image carrier and intermediately transferred is determined by driving the contact / separation driving unit.
The contact is made with a delay of a predetermined time (t) at each position of the images of different colors sequentially formed on the image carrier.
The position where the rotation of the image bearing member occurs due to the contact of the intermediate transfer member during development becomes the same, and it is possible to provide an image forming apparatus capable of performing high quality image formation without displacement of each color. Was. According to the second aspect of the present invention, electrostatic latent images of different colors formed at a predetermined interval (L) on an image carrier rotating at a predetermined linear velocity (V) correspond to toner images of different colors for developing. The timing at which the intermediate transfer body, which is intermediately transferred by superimposing toner images of different colors developed by the developing unit composed of a plurality of developing devices arranged in sequence and in contact with and separated from the image carrier, is By driving the contact / separation driving means, the contact and the separation of the images of different colors sequentially formed on the image carrier are delayed by a predetermined time (t) by a predetermined time (t). Alternatively, it is possible to provide an image forming apparatus capable of performing high-quality image formation in which the positions at which the rotation fluctuation of the image bearing member occurs due to separation or the like become the same and the positional shift of each color is eliminated. According to the third aspect of the present invention, electrostatic latent images of different colors formed at a predetermined interval (L) on an image carrier rotating at a predetermined linear velocity (V) correspond to toner images of different colors for developing. The timing at which the intermediate transfer body, which is intermediately transferred by superimposing toner images of different colors developed by the developing unit composed of a plurality of developing devices arranged in sequence and in contact with and separated from the image carrier, is By the driving of the contact / separation driving means, the contact and the separation are made with a delay of time (t) = (L) / (V) by each position of the images of different colors sequentially formed on the image carrier. Accordingly, it is possible to provide an image forming apparatus in which the rotation of the image carrier due to the contact of the intermediate transfer member during development is the same, and high-quality image formation is performed without displacement of each color. Was. According to the fourth aspect of the present invention, the electrostatic latent images of different colors formed at the predetermined interval (L) on the image carrier rotating at the predetermined linear velocity (V) correspond to the toner images of different colors for developing. The timing at which the intermediate transfer body, which is superimposed and sequentially intermediate-transferred toner images of different colors developed by the developing unit including a plurality of arranged developing devices, comes into contact with the image carrier and is intermediately transferred is separated. When the driving means is driven, the positions of the images of different colors sequentially formed on the image carrier are contacted with a delay of a predetermined time (t), and the intermediate transfer body is used to transfer toner images of two or more colors. Rotates in both the forward direction and the return direction, and rotates in one direction of the forward direction or the return direction when transferring a single color toner image. Fluctuations in body rotation Kill position has become possible to provide a compact image forming apparatus identical to become high-quality image formation without the transfer positional displacement of each color is performed.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a perspective view illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is an enlarged explanatory diagram illustrating another main part of the image forming apparatus according to the exemplary embodiment of the present invention.

FIG. 6 is a timing chart illustrating an operation of another main part of the image forming apparatus according to the exemplary embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Developing unit, 2a ...
Developing device (black), 2b Developing device (cyan), 2
c: developing device (magenta), 2d: developing device (yellow), 2e1 to 4: developing roller, 3: intermediate transfer member, 4: contact / separation driving means, 4a ... Facing roller,
4b: tension roller, 4c: drive roller,
4d: roller, 4e: support shaft, 4f: support member, 4g: support shaft, 4h: support member, 4i ...
・ Cam member, 4j: rotating shaft, 4k: clutch,
4l: drive motor, 4m: stepping motor, 20: color scanner unit, 20a ...
・ Contact glass, 20b ・ ・ ・ Illumination lamp, 20c
... Mirror group, 20d ... Lens, 20e ... Color sensor, 20f ... Polygon mirror, 20g
..F / θ lens, 20h ... reflection mirror, 30 ...
-Color printer unit, 30a-Registration roller, 30b-Transfer roller, 30c-Transport unit, 30d-Fixing device, 30e-Discharge roller,
40 ... paper feed unit.

Claims (4)

[Claims] 1. An image forming apparatus comprising: an electrostatic latent image formed on an image carrier; and a toner image of a different color developed by a plurality of developing units. In an image forming apparatus for forming an image by transferring an image, an image carrier that is rotatably supported to form electrostatic latent images of different colors, and a predetermined image is formed on the image carrier that rotates at a predetermined linear velocity (V) A developing unit composed of a plurality of developing units arranged corresponding to toner images of different colors for developing electrostatic latent images of different colors formed at intervals is overlapped with the toner images of different colors developed by the developing unit. The timing at which the intermediate transfer member that is intermediate-transferred together and the intermediate transfer member is brought into contact with the image carrier and the intermediate transfer is performed is set for each of the toner images of different colors that are sequentially formed on the image carrier. It will contact with a delay by a predetermined time depending on the position An image forming apparatus comprising a separation driving means for driving, in that it consists of a. 2. The image forming apparatus according to claim 1, wherein
The contact / separation driving unit controls the timing at which the intermediate transfer member separates from the image carrier after the toner image is intermediately transferred by each position of a different color toner image sequentially formed on the image carrier. An image forming apparatus which is driven so as to be separated by a predetermined time. 3. The image forming apparatus according to claim 1, wherein the contact / separation driving unit sequentially forms a timing of contacting or separating the intermediate transfer member on the image carrier on the image carrier. Driven by a predetermined time (t) = (L) / (V) by each position of the different color toner images
Here, L is an interval between toner images of different colors formed on the image carrier 1, and V is a linear velocity (V) on the image carrier 1. apparatus. 4. The image forming apparatus according to claim 1, wherein the intermediate transfer member rotates in both a forward direction and a return direction when a toner image of two or more colors is transferred, and forms one color. An image forming apparatus which rotates in one direction when transferring the toner image of the image forming apparatus.