JPH11242409A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity by realizing a limitless mode even when the toner images of the images of plural surfaces are simultaneously formed. SOLUTION: At the first scanning time of two A4-sized originals set at an original read unit 9, transfer paper is supplied to a resist roller 10 from a paper supply cassette 41a by a central control part 31. Besides, it is judged based on a signal outputted from the transfer paper detection sensor 43a of the cassette 41a whether the next transfer paper exists in the cassette 41a or not. When the transfer paper on which the next image is transferred does not exist in the cassette 41a, a transfer paper size storage part 32 is retrieved by the control part 31 so as to judge whether the A4-sized transfer paper is set in the other paper supply cassettes 41b-41a or not. When the A4-sized transfer paper is set in one out of the cassettes 41b-41a, the toner image forming action and the transfer action of the first and the second surfaces are continuously executed.

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 capable of forming images on two surfaces simultaneously with a digital color copying machine, a printer, or the like, and more particularly to an improvement in image forming efficiency.

[0002]

2. Description of the Related Art As shown in, for example, Japanese Patent Laid-Open No. 4-175774, a toner image of an original read by an original reading device and an image of image information sent from a host device are simultaneously printed.
2. Description of the Related Art An image forming apparatus has been used in which image formation efficiency is improved by forming areas. This image forming apparatus, as shown in FIG.
An image forming unit 1, a primary transfer unit 2, a secondary transfer unit 3, a paper feed unit 4 and a fixing unit 5 are provided. The image forming unit 1 includes a charging charger 12 and an image writing unit 13 disposed around a photoreceptor 11, and a rotary or fixed type including black (K), cyan (C), magenta (M), and yellow (Y). And an electrostatic latent image is formed on the photoreceptor 11 by the laser beam from the image writing unit 13, and the formed electrostatic latent image is formed by the color developing unit 14. Visualize to form a toner image. The primary transfer unit 2 includes an intermediate transfer belt 21, a primary transfer unit 22, and a plurality of tension rollers 2.
It has a third transfer roller 24, a reference position sensor 25, and a cleaning unit 26, and primary-transfers the toner image formed on the photoconductor 11 to the intermediate transfer belt 21. The intermediate transfer belt 21 has a reference image size, for example, twice as long as the A4 size, and is capable of simultaneously transferring toner images for two surfaces. As shown in FIG. Two reference marks 27a and 27b are provided at a fixed interval in the image portion. This intermediate transfer belt 21 is
Except during the primary transfer of the upper toner image, the toner image is separated from the surface of the photoconductor 11 by a contact / separation mechanism (not shown), and is pressed against the surface of the photoconductor 11 only during the primary transfer of the toner. The secondary transfer unit 3 secondarily transfers the toner image transferred to the intermediate transfer belt 21 to the transfer paper 6. The paper feed unit 4 has, for example, four paper feed trays 41a to 41d.
Reference numerals a to 41d include paper feed rollers 42a to 42d and transfer paper detection sensors 43a to 43d.

When a document read by the image forming apparatus configured as described above or image information sent from the host device is sent and an image forming cycle is started, image data for forming an image is one or more colors. Is determined by a command.
When the image to be formed is one color, since it is not necessary to detect the reference marks 27a and 27b of the intermediate transfer belt 21 of the primary transfer unit 2, the toner image formed on the photoreceptor 11 is primary-transferred to the intermediate transfer belt 21. Transcribe. Secondary transfer unit 3
The transfer paper 6 fed from the paper feed tray 41a, for example, matches the leading end of the toner image transferred to the intermediate transfer belt 21.
The fixing unit 5 fixes the toner image transferred to the transfer paper 6 by heating and pressing. The toner remaining on the intermediate transfer belt 21 is
Collect at 6.

When an image to be formed has two or more colors, the toner image formed on the photoreceptor 11 is
The reference mark 27 on the intermediate transfer belt 21 is used to superimpose each color image so that there is no color shift at the time of next transfer.
Is detected by the reference position sensor 25, and the toner image formed on the photoconductor 11 is primarily transferred to the intermediate transfer belt 21 based on the mark detection signal. This primary transfer is repeated for each color. That is, when forming a two-color image, the intermediate transfer belt 21 is rotated twice, and when a full-color image is formed, the intermediate transfer belt 21 is rotated four times. The primary transfer of the toner image formed on the photoreceptor 11 to the intermediate transfer belt 21 is performed, and the images of the respective colors are superimposed without displacement. When the toner image of a predetermined color is transferred to the intermediate transfer belt 21, the intermediate transfer belt 2
The toner image is secondarily transferred to a transfer sheet 6 fed according to the leading end of the toner image transferred to the transfer sheet 1, and the fixing unit 5 fixes the toner image transferred to the transfer sheet 6 by heating and pressing.

When a toner image of a reference size smaller than the distance between the reference marks 27a and 27b, for example, an A4 size image, is simultaneously transferred to the intermediate transfer belt 21 for two surfaces,
As shown in FIG. 4, the toner image 7a for one surface is transferred to the intermediate transfer belt 21 with reference to the reference mark 27a, and then the toner image 7b for two surfaces is transferred to the intermediate transfer belt 21 with reference to the reference mark 27b. And the toner images 7a and 7b transferred to the intermediate transfer belt 21 are secondarily transferred onto transfer paper 6 continuously fed from a paper feed tray 41a on which A4-size transfer paper 6 is set.

Further, a plurality of paper feed trays 41a-41b
Is provided, there is a function called a limitless mode, for example, a paper feed tray 41 on which A4 size transfer paper 6 is set.
If the A4 size transfer paper 6 is set in the other paper feed tray 41b even if a reaches the paper end, the A4 size transfer paper 6 is continuously fed from the paper feed tray 41b.

[0007]

[0006] Even in the case of having the limitless mode as described above, for example, the transfer paper 6 formed by continuously forming a toner image of an A4 size image for two surfaces and feeding the same is provided.
When the secondary transfer is performed, a paper feed tray 41 on which A4 size transfer paper 6 is set at the start of the image forming start
It is not known whether the remaining amount of transfer paper in a is one or two or more, and if the first one side of the transfer paper 6 is not fed, it is not known whether it is the paper end and the limitless mode is applied. I couldn't. For this reason, when the first one side of the transfer paper 6 is fed and the paper ends, the next 2
The toner image on the surface cannot be continuously transferred to the transfer paper, and the image forming efficiency is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of improving the productivity by improving the disadvantages and enabling a limitless mode even when toner images of a plurality of images are simultaneously formed. Things.

[0009]

An image forming apparatus according to the present invention has an intermediate transfer belt capable of simultaneously transferring toner images of a reference image size formed on a photosensitive member for a plurality of surfaces. Transfer the transferred toner image to the transfer material 2
In the image forming apparatus for performing the next transfer, when transferring a plurality of images to the transfer material, it is characterized in that at the first scan after the start of the transfer, it is determined whether or not there is a next transfer material to be transferred. Further, as a result of this determination, when there is a transfer material having the same size as the transfer material for transferring the image on the first surface in any of the paper feed cassettes, the transfer operation on the second and subsequent surfaces is also performed continuously.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention has an image forming unit, a primary transfer unit, a secondary transfer unit, a paper feed unit having a plurality of paper feed cassettes, and a fixing unit. The image forming unit forms an electrostatic latent image on a photoreceptor by a laser beam from an image writing unit, and visualizes the formed electrostatic latent image by a color developing unit to form a toner image. The primary transfer unit includes an intermediate transfer belt wound around a plurality of tension rollers, a primary transfer unit, a secondary transfer roller, a reference position sensor, and a cleaning unit, and transfers a toner image formed on a photoconductor to the intermediate transfer belt. First transfer. The intermediate transfer belt has a length equal to or more than twice as large as an A4 size, which is one round, and is capable of simultaneously transferring toner images for two surfaces. The image portion has two fiducial marks at regular intervals. The secondary transfer unit secondarily transfers the toner image transferred to the intermediate transfer belt to transfer paper. A control unit of the image forming apparatus, which is connected to the document reading unit and the host interface, processes image information of the read document and image information sent from the host apparatus, and manages the operation of the entire apparatus;
A transfer paper size storage unit is provided for storing the size of the transfer paper set in each paper feed cassette of the paper feed unit.

For example, an A4 size 2
At the time of the first scan after the originals are set, the central control unit feeds the transfer paper for transferring the image on the first side from the paper feed cassette to the registration roller, and outputs a signal from the transfer paper detection sensor of the paper feed cassette. To determine whether the next transfer sheet is present in the sheet cassette. When there is a transfer sheet for transferring the image on the second side in the paper feed cassette, the central control unit continuously performs the toner image formation and the transfer operation on the first and second sides. When there is no recording paper for transferring the image on the second side in the paper feed cassette which has supplied the transfer paper for transferring the image on the first side, the central control unit searches the transfer paper size storage unit and searches for another paper cassette. It is determined whether or not an A4-size transfer sheet is set in the printer. As a result of this determination, when no A4-size transfer paper is set in any of the paper feed cassettes, the central control unit causes only the first-side original to be read to form a toner image on the photoconductor, and the formed first-side Is transferred to a transfer sheet, fixed and discharged. When A4 size transfer paper is set in any of the other paper feed cassettes, the central control unit continuously performs the toner image formation and transfer operation on the first and second surfaces.

[0012]

FIG. 1 is a block diagram showing the configuration of a control unit according to an embodiment of the present invention. The image forming unit 1, the primary transfer unit 2, the secondary transfer unit 3, the paper feed unit 4 and the fixing unit 5 of the image forming apparatus of this embodiment have exactly the same configuration as that shown in FIG. The control unit 30 of the image forming apparatus is connected to the host interface 8 and the document reading unit 9 and processes the image information sent from the host device and the image information of the read document to manage the operation of the entire apparatus. 31 and a transfer paper size storage unit 32 for storing the size of the transfer paper 6 set in each of the paper feed cassettes 41 a to 41 d of the paper feed unit 4.

In the image forming apparatus configured as described above, 1
Reference mark 2 on intermediate transfer belt 21 of next transfer unit 2
A toner image of a reference size, for example, an A4 size image smaller than the interval of the intermediate transfer belt
The operation of forming an image on the transfer sheet 6 by transferring the image to the transfer sheet 1 will be described with reference to the flowchart of FIG.

When two A4 size originals are set in the original reading unit 9 and the A4 size transfer paper 6 is set at the first scan, the paper feed roller 4 of the paper feed cassette 41a is set.
2a, the A4 size transfer paper 6 is transferred to the registration roller 10
(Steps S1 and S2). When the first transfer paper 6 is fed to the registration roller 10, the central control unit 3
In step S3, the control unit 1 determines whether there is the next transfer sheet 6 in the sheet cassette 41a based on a signal output from the transfer sheet detection sensor 4 (step S3). When the recording paper 6 for transferring the image on the second side is present in the paper feed cassette 41a, the central control unit 31 forms the toner image on the first side on the photoconductor 11 of the image forming unit 1 and performs the primary transfer of the formed toner image. The primary transfer is performed on the intermediate transfer belt 21 of the unit 2 (step S4). afterwards,
The original on the second side is immediately read by the original reading unit 9 (step S5), the read second-side toner image is formed on the photoconductor 11, and the second-side original is transferred onto the intermediate transfer belt 21 on which the first-side toner image is transferred. The primary transfer of the toner image is performed (step S6). This process is called black, cyan, magenta,
When the full-color toner images on the first and second surfaces are formed on the intermediate transfer belt 21 repeatedly for yellow, the transfer paper 6 on the first surface fed to the registration roller 10 is sent to the secondary transfer unit, and at the same time, the paper cassette The transfer paper 6 on the second side is fed to the registration roller 10 from step 41a (steps S7 and S8).
Then, the toner image on the second side is transferred onto the transfer paper 6 (step S9). The transfer paper 6 on which the toner image on the first side has been transferred and the transfer paper 6 on which the toner image on the second side has been transferred are fixed by the fixing unit 5 and discharged (step S10).

When there is no recording paper 6 for transferring the image on the second side in the paper feed cassette 41a, the central controller 31 determines whether or not the remoteless mode is set (step S11). If the setting is not set, only the original on the first side is read to form a toner image on the photoconductor 11, the full-color toner image of the image on the first side is transferred to the intermediate transfer belt 21, and the formed toner on the first side is The image is transferred to the transfer paper 6 (step S12). The transfer paper 6 on which the toner image of the first side has been transferred is fixed by the fixing unit 5 and discharged (step S1).
0).

If there is no recording paper 6 for transferring the image on the second side in the paper feed cassette 41a and the remoteless mode is set (steps S3 and S11), the central control unit 31 stores the transfer paper size in the transfer paper size storage unit 32. To determine whether the A4-size transfer paper 6 is set in another paper feed cassette 41b to 41d (step S12). As a result of this determination, A is assigned to any of the sheet cassettes 41b to 41d.
When the four-size transfer paper 6 is not set, the central control unit 31 causes only the first-side original to be read, and
The toner image on the first side is transferred to the transfer paper 6, fixed and discharged (step S12,
Step S10). Also, the paper feed cassettes 41b to 41d
For example, when the A4 size transfer paper 6 is set in the paper feed cassette 41b, the central control unit 31
The toner image of the surface is formed on the photoreceptor 11 of the image forming unit 1, and the formed toner image is primarily transferred to the intermediate transfer belt 21 of the primary transfer unit 2 (Step S4). Then, the second-side original is immediately read by the original reading unit 9 (step S5), and the read second-side toner image is formed on the photoconductor 11, and the second-side toner image is transferred onto the intermediate transfer belt 21 onto which the first-side toner image has been transferred. The first transfer of the toner image on the surface is performed (step S6). This process is repeated for black, cyan, magenta, and yellow.
After the first and second full-color toner images have been formed on the first and second sides, the first-side transfer paper 6 fed to the registration rollers 10 is sent to the secondary transfer unit, and at the same time, the second-side transfer paper 6 is fed from the paper feed cassette 41b. Is fed to the registration rollers 10 (steps S7 and S8), the toner image on the first surface is transferred onto the transfer paper 6, and then the toner image on the second surface is transferred onto the transfer paper 6, fixed and discharged (step S7). S9, S1
0).

[0017]

As described above, according to the present invention, when a plurality of images are transferred to a transfer material, it is determined whether or not there is a next transfer material at the first scan after the start of transfer. In addition, the limitless mode can be executed even when a paper end occurs when a plurality of images are formed on the transfer material.

When transferring a plurality of images to a transfer material, it is determined whether there is a transfer material to be transferred next at the first scan after the start of the transfer, and the first surface is placed in one of the paper feed cassettes. When the transfer material having the same size as the transfer material for transferring the image is present, the toner image formation and the transfer operation on the second and subsequent surfaces are continuously performed, so that the workability particularly when forming a color image can be improved. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control unit according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment.

FIG. 3 is a configuration diagram of an image forming apparatus.

FIG. 4 is a layout diagram of reference marks on an intermediate transfer belt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Primary transfer unit 3 Secondary transfer unit 4 Paper feed unit 5 Fixing unit 6 Transfer paper 9 Original reading unit 30 Control unit 31 Central control unit 32 Transfer paper size storage unit 41 Paper feed cassette 43 Transfer paper detection sensor

Claims (2)

[Claims] An intermediate transfer belt capable of simultaneously transferring toner images of a reference image size formed on a photoreceptor for a plurality of surfaces is provided, and the toner image transferred to the intermediate transfer belt is secondarily transferred to a transfer material. In the image forming apparatus, when transferring a plurality of images to a transfer material, it is determined whether or not there is a transfer material to be transferred next at the first scan after the start of the transfer. 2. An intermediate transfer belt capable of simultaneously transferring toner images of a reference image size formed on a photoreceptor for a plurality of surfaces, wherein the toner image transferred to the intermediate transfer belt is secondarily transferred to a transfer material. In the image forming apparatus, when transferring a plurality of images to a transfer material, it is determined whether there is a transfer material to be transferred next at the first scan after the start of the transfer, and the first side is placed in one of the paper feed cassettes. An image forming apparatus characterized in that when there is a transfer material having the same size as the transfer material for transferring the image, the transfer operation for the second and subsequent surfaces is also performed continuously.