JPH11338274A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the abutment part between a photoreceptor drum and an intermediate transfer belt from being damaged by friction and to prevent the occurrence of image disturbance by controlling revolving speed so as not to cause a speed difference even in the case of driving the photoreceptor drum and intermediate transfer belt by means of separate driving sources. SOLUTION: In this image forming device A1, adverse effects such as the image disturbance is prevented by abutting the photoreceptor drum 101 on the intermediate transfer belt 103 which are away from each other after detecting that a drum motor 106 for driving the photoreceptor drum 101 and a belt motor 107 for driving the intermediate transfer belt 103 have reached a prescribed speeds.

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 a separately driven photosensitive drum and a set of toner images formed on the photosensitive drum, which are superposed and transferred. The present invention relates to an image forming apparatus for contacting or separating an intermediate transfer belt as needed.

[0002]

2. Description of the Related Art For example, in a case where a color image is transferred in an image forming apparatus such as a copying machine, a printer, and a facsimile,
The yellow, cyan, magenta, and black toner images sequentially formed on the photosensitive drum are temporarily overlapped and transferred onto an endless transfer belt (intermediate transfer belt) before being transferred onto paper. There is a type in which a toner image corresponding to the color image is formed on a belt, and then the toner image corresponding to the color image having four layers for each color is transferred to a sheet. In order to fix the four-layered toner image on the sheet, a larger amount of heat is required than in the case where the one-layered toner image is fixed on the sheet. In particular, this tendency is more remarkable for thick paper, OHP, and the like than for plain paper. However, since there is a limit to the power that can be used in the apparatus, in order to provide this amount of heat, it is necessary to reduce the conveyance speed of the sheet to be fixed and prolong the time during which heat is supplied. However, if the conveying speed of the sheet to be fixed, the moving speed of the intermediate transfer belt, and the rotating speed of the photosensitive drum are made different, friction occurs at the contact portions where they come into contact with each other, which may damage each surface. There is. Therefore, in the image forming apparatus as described above, there is a case where the photosensitive drum and the intermediate transfer belt are separated from each other, and only the speed downstream of the intermediate transfer belt is reduced. Also, apart from this reason,
For example, when all the toner images of each color are transferred from the photosensitive drum to the intermediate transfer belt in consideration of, for example, attaching and detaching the unit including the intermediate unit, the photosensitive drum and the intermediate transfer belt are always separated. There is also a device which is controlled so that the photosensitive drum and the intermediate transfer belt are brought into contact again when the transfer is separated and transfer is newly performed. In the image forming apparatus, the driving of the photosensitive drum and the driving of the intermediate transfer belt are often performed by separate driving units. This means that a smaller drive unit having sufficient output to drive each of the drive units is provided, rather than preparing one drive unit having an output sufficient to drive both the photosensitive drum and the intermediate transfer belt. This is because preparing two is cheaper. These driving means start driving the photosensitive drum and the intermediate transfer belt at the same time as or after the separated photosensitive drum and the intermediate transfer belt are brought into contact with each other. Reaches a predetermined speed, the toner image can be transferred.

[0003]

However, the starting characteristics of the separate driving means often differ from individual to individual even if they are of the same type, and each of them reaches a predetermined speed as in a conventional device. If the photosensitive drum and the intermediate transfer belt are brought into contact by then, friction occurs due to a speed difference, which may damage each other and disturb the image.
SUMMARY OF THE INVENTION In order to solve the problems in the prior art, the present invention has improved an image forming apparatus, and a photoconductor drum and a set of toner images sequentially formed on the photoconductor drum are superimposed and transferred. In an image forming apparatus in which the intermediate transfer belt is brought into contact with or separated from the intermediate transfer belt as necessary, even when the photosensitive drum and the intermediate transfer belt are driven by separate driving sources, control is performed so that no speed difference occurs. It is an object of the present invention to provide an image forming apparatus which can prevent the occurrence of friction at the contact portion between the photosensitive drum and the intermediate transfer belt, thereby preventing damage and disturbing the image.

[0004]

According to a first aspect of the present invention, a photosensitive drum and a set of toner images sequentially formed on the photosensitive drum are superimposed and transferred. Endless intermediate transfer belt, first drive means and second drive means for separately driving the photosensitive drum and the intermediate transfer belt at a predetermined speed, and the photosensitive drum and the intermediate transfer belt. In the case where an image forming apparatus including an abutment / separation unit for abutting / separating the belt from the photosensitive drum and the intermediate transfer belt, which are separated by the abutment / separation unit, The image forming apparatus is configured such that the first driving means and the second driving means are brought into contact with each other after reaching the predetermined speed.
According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the first driving unit and the second driving unit detect whether or not each of the first driving unit and the second driving unit is synchronized with the predetermined speed. The gist of the present invention is to provide a detecting means. According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, after a lapse of time sufficient for the first driving means and the second driving means to reach the predetermined speed. The point is that the photosensitive drum and the intermediate transfer belt are brought into contact with each other. Claim 1
According to the image forming apparatus described in any one of the above items (1) to (3), a photoconductor drum and an intermediate transfer belt onto which a set of toner images sequentially formed on the photoconductor drum are superimposed and transferred are required. In the image forming apparatus which is brought into contact with or separated from the photosensitive drum and the intermediate transfer belt by the first drive unit and the second drive unit, the first drive unit and the second drive unit When the driving means reaches a predetermined speed, the photosensitive drum and the intermediate transfer belt are brought into contact with each other. There is almost no damage, and it is possible to prevent the contact portions from being damaged and disturb the image.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiment is a specific example of the present invention and does not limit the technical scope of the present invention. An image forming apparatus according to an embodiment of the present invention is realized by, for example, a color digital copying machine, and FIG. As shown in FIG. 1, an image forming apparatus A1 according to one embodiment of the present invention includes:
Photoconductor drum 1 on which electrostatic latent images of a plurality of grayscale images generated by separating a color image for each color are sequentially formed
01 and a plurality of developing devices 102 (10) for developing by attaching yellow, cyan, magenta, and black toners to the electrostatic latent images sequentially formed on the photosensitive drum 101.
2Y, 102C, 102M, and 102K) and the toner images of the respective colors sequentially formed on the photosensitive drum 101 by the developing device 102 are superimposed and transferred to form a toner image corresponding to the color image. Endless intermediate transfer belt 103, transfer means 104 for transferring a toner image corresponding to the color image formed on the intermediate transfer belt 103 onto paper, and a toner image transferred by the transfer means 104 on paper. , A drum motor (first drive unit) 106 and a belt motor (second drive unit) for separately driving the photosensitive drum 101 and the intermediate transfer belt 103 at a predetermined speed, respectively. 107, and the toner images of each color are transferred from the photosensitive drum 101 to the intermediate transfer belt 103. The photosensitive drum 101 is brought into contact with the intermediate transfer belt 103 until a toner image corresponding to a color image is formed. When a toner image corresponding to the color image is formed on the intermediate transfer belt 103, This is the same as a conventional image forming apparatus in that the image forming apparatus includes a contact / separation unit (not shown) for separating the body drum 101 and the intermediate transfer belt in the direction of arrow Y. The image forming apparatus A1 is particularly different from the conventional one in that when the transfer is started, it is detected whether or not the drum motor 106 and the belt motor 107 are synchronized with the predetermined speed. When it is detected that the motors 106 and 107 are synchronized, a control signal is output to the contact / separation means, and the photosensitive drum 101 and the intermediate transfer belt 103 separated by the contact / separation means are separated from each other. Is provided with a control means 108 for controlling the contact between the two. Next, details of the image forming apparatus A1 will be described with reference to FIGS. FIG. 2 is a flowchart for explaining the control operation performed by the control means 108. Note that this description is based on the photosensitive drum 1 described above.
01 and the intermediate transfer belt 103 are driven at predetermined speeds by separate motors 106 and 107, respectively, so that the photosensitive drum 101 and the intermediate transfer belt 103 are brought into contact with each other by the contact / separation means. Start as something. When the transfer start is instructed, the image forming apparatus A1 first reads out, for example, a signal corresponding to yellow from among the signals corresponding to yellow, magenta, cyan, and black stored in a memory (not shown). The laser beam is converted into a laser beam, and is irradiated onto the surface of the photosensitive drum 101 uniformly charged at a predetermined potential. As a result, an electrostatic latent image corresponding to yellow is formed on the surface of the photosensitive drum 101 which is driven by the drum motor 106 and rotates at a predetermined speed in the direction of the arrow X. When the electrostatic latent image corresponding to the yellow color moves to the developing means 102Y by the rotation of the photosensitive drum 101, the developing means 1
02Y causes yellow toner to adhere to the electrostatic latent image to form a toner image. The photosensitive drum 101
The toner image corresponding to yellow formed on the surface of the photosensitive drum 10 is rotated by rotation of the photosensitive drum 101.
When the toner image corresponding to yellow on the surface of the photosensitive drum 101 moves at a predetermined speed in the direction of arrow Z by the action of the belt motor 107 when the toner image moves to a contact portion where the surface of the intermediate transfer belt 103 contacts the surface of the intermediate transfer belt 103. The image is transferred to the surface of the intermediate transfer belt 103. The transfer operation corresponding to yellow as described above is the same for cyan, magenta, and black. By repeating this, the toner images sequentially formed on the surface of the photosensitive drum 101 are transferred to the surface of the intermediate transfer belt 103. The toner images corresponding to the color images of four layers are formed on the surface of the intermediate transfer belt 103. When a toner image corresponding to the color image is formed on the intermediate transfer belt 103, the photosensitive drum 101 and the intermediate transfer belt 103 are separated by the contact / separation unit. This separation is performed, for example, by moving the intermediate transfer belt 103 with respect to the photosensitive drum. Due to the separation, the photosensitive drum 1
And the unit 109 including the developing means 102 is prevented from being damaged when the intermediate transfer belt 103 is attached and detached.
3, the driving speed of the transfer unit 104 and the driving speed of the fixing unit 105 can be made different from the driving speed of the photosensitive drum 101. At this time, for example, according to the quality of the paper, the intermediate transfer belt 103, the transfer unit 104, the fixing unit 1
If the driving speed of the sheet 05 is reduced, the amount of heat applied to the sheet while the sheet passes through the fixing unit 104 can be increased. Then, the toner image corresponding to the color image formed on the surface of the intermediate transfer belt 103 is transferred to the sheet P conveyed on the path shown by the broken line in FIG. Means 105
As a result, heat is applied, and the toner image is fixed on the sheet P. Since the driving speeds of the transfer unit 105 and the fixing unit 106 are set to be the same, the distance between the two is short, and even if the rear end of the sheet being fixed is gripped by the transfer unit 105, the paper sags. It doesn't happen. In this way, in the image forming apparatus A1, the sheet on which the toner image corresponding to the color image is fixed is discharged by a discharge unit (not shown). At this time, the photosensitive drum 101 and the intermediate transfer belt 103 are separated from each other.
When the photosensitive drum 101 is brought into contact with the intermediate transfer belt 103 in order to newly transfer an image to a sheet, the control unit 108 performs control according to the flowchart of FIG. The control means 1
08 is, for example, the drum motor 106 and the belt motor 1
07 is realized by a sensor for detecting the speed of 07, arithmetic means such as a CPU, and the like. When a new transfer is instructed, the drum motor 106 and the belt motor 107 are turned on. At this time, the speed of the drum motor 106 and the speed of the belt motor 107 are gradually increased according to the respective starting characteristics until the speed reaches a preset predetermined speed. next,
The control means 108 detects whether or not the drum motor 106 has reached the predetermined speed and is in synchronization (S
101). At this time, the photosensitive drum 101 and the intermediate transfer belt 103 are still separated by the contact and separation unit. If it is detected that the drum motor 106 has reached the predetermined speed and is synchronized, then the control means 108 detects whether the belt motor 107 has reached the predetermined speed and is synchronized (S10).
2). At this time, the photosensitive drum 101 and the intermediate transfer belt 103 are still separated by the contact and separation means. The control means 1 determines that the drum motor 106 has also reached the predetermined speed and is synchronized.
08, a control signal is output from the control means 108 to the contact / separation means, and the contact / separation means is operated, and the photosensitive drum and the intermediate transfer belt 1 are operated.
03 is brought into contact (S103). As a result, the transfer of the image can be started, and the above-described transfer operation is repeated for a new image. As described above, in the image forming apparatus A1 according to the present embodiment, after detecting that both the drum motor 106 and the belt motor 107 have reached the predetermined speed, the photosensitive drum 101
And the intermediate transfer belt 103 are brought into contact with each other, so that there is almost no speed difference between the contact portion of the photosensitive drum 101 and the intermediate transfer belt 103, and the speed difference causes scratches and image disturbance. Is prevented.

[0006]

In the above embodiment, the present invention is applied to a color digital copying machine. However, the present invention is not limited to this, and can be applied to other image forming apparatuses such as a printer and a facsimile. In the above-described embodiment, the photosensitive drum 101 and the intermediate transfer belt 103 are brought into contact with each other after it is detected that both the drum motor 106 and the belt motor 107 have reached the predetermined speed. However, the present invention is not limited to this. For example, the time required for both the drum motor 106 and the belt motor 107 to reach the predetermined speed (sufficiently) is measured in advance, and the timer provided in the control means 108 sets the time When the elapsed time is output, the photosensitive drum 101 and the intermediate transfer belt 103 may be brought into contact with each other. Such an image forming apparatus is also an example of the image forming apparatus of the present invention. Further, in the above-described embodiment, when a toner image corresponding to a color image is formed on the intermediate transfer belt 103, the photosensitive drum 101 and the intermediate transfer belt 103 are separated from each other, and are brought into contact when a new transfer is performed. However, the present invention is not limited to this. For example, the separation / contact may be controlled according to the paper quality. Such an image forming apparatus is also an example of the image forming apparatus of the present invention.

[0007]

As described above, according to any one of claims 1 to 3,
According to the image forming apparatus described above, the photosensitive drum and the intermediate transfer belt on which a set of toner images sequentially formed on the photosensitive drum are superimposed and transferred are contacted or separated as necessary. In the image forming apparatus, even if the photosensitive drum and the intermediate transfer belt are separately driven by the first drive unit and the second drive unit, the first drive unit and the second drive unit are driven to a predetermined speed. When the photosensitive drum and the intermediate transfer belt come into contact with each other, there is almost no speed difference between the photosensitive drum and the intermediate transfer belt. Is prevented from damaging the abutment portion and disturbing the image.

[Brief description of the drawings]

FIG. 1 is an image forming apparatus A according to an embodiment of the present invention.
1 is a diagram showing a schematic configuration of FIG.

FIG. 2 is a flowchart for explaining a control operation by a control unit provided in the image forming apparatus A1.

[Explanation of symbols]

 101 photoconductor drum 102 developing means 103 intermediate transfer belt 108 control means 109 unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasushi Saito Mita Kogyo Co., Ltd. 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Osaka

Claims (3)

[Claims] 1. A photosensitive drum, an endless intermediate transfer belt on which a set of toner images sequentially formed on the photosensitive drum are superimposed and transferred, and the photosensitive drum and the intermediate transfer belt, respectively. A first driving unit and a second driving unit for separately driving at a predetermined speed; and an abutting / separating unit for abutting or separating the photosensitive drum and the intermediate transfer belt. In the image forming apparatus, when the photosensitive drum and the intermediate transfer belt that are separated by the contact and separation unit are brought into contact with each other,
An image forming apparatus, wherein the first driving means and the second driving means are brought into contact with each other after reaching the predetermined speed. 2. The image forming apparatus according to claim 1, further comprising: a synchronization detecting unit configured to detect whether the first driving unit and the second driving unit are synchronized with the predetermined speed. 3. The method according to claim 1, wherein the photosensitive drum and the intermediate transfer belt are brought into contact with each other after a sufficient time has elapsed for the first driving means and the second driving means to reach the predetermined speed. Item 2. The image forming apparatus according to Item 1.