JPH11242410A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably form a color image and to prevent transfer paper from being wasted. SOLUTION: When a first original is sent to an original read unit 6 and the first scanning thereof is started, it is judged by an automatic color selection means 202 whether the set original is the color image or a black-and-white image based on image information obtained by the first scanning. When the set original is the color image, a transfer mode in which the toner image of the first original started to be read is formed as many as one surface on an intermediate transfer belt 1 and the toner image of the plural surfaces of the second and the subsequent originals are formed on the belt 1 is selected by a transfer mode selection means 203. By a central control part 201, the four- color toner image of the first original is successively formed on a photoreceptor and superposed on the belt 1. Then, the formed full color image is transferred on the transfer paper and the toner images of the second and the subsequent originals are transferred on the belt 1 two surfaces by two.

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 simultaneously forming an image on a plurality of surfaces with a digital color copying machine, a printer, or the like, and more particularly to the prevention of useless printing.

[0002]

2. Description of the Related Art In order to improve the efficiency of forming a color image in an image forming apparatus for forming a multicolor image of a document read by a document reading device or image information sent from a host device, for example, Japanese Patent Application Laid-Open No. 4-175774 is disclosed. As shown in the figure, a two-screen color image having the reference image size is formed on a photosensitive belt having a reference image size, for example, twice or more the length of the A4 size. As shown in Japanese Patent Application Laid-Open Publication No. H10-209, a two-screen image is formed by transferring a toner image formed on a photoreceptor to two transfer papers adsorbed on a transfer drum having a peripheral length of twice or more a reference image size. The so-called two-chamfering for forming a color image is adopted.

Further, a color copying machine or the like has an automatic color selection function for automatically judging whether a document is color or black and white without prescanning, switching between color copy and black and white copy and improving the copy speed. This automatic color selection function determines whether the original is a color image or a black and white image in the first scan, and switches between a color image forming process and a black and white image forming process accordingly.

[0004]

In the image forming process, image forming intervals and various operations are different between a color image forming process and a black and white image forming process. For this reason, if the next operation is determined after one scan by the automatic color selection function, the switching of the operation of the second sheet may not be in time in the case of performing the two-sided printing.

[0005] Further, in the color image forming process, various settings such as color setting and image quality setting are more common than in the black and white image forming process.
Often, copying is stopped immediately. However, in the image forming process for forming a color image, a toner image of four colors is formed from when the start button is pressed until the printed transfer sheet is discharged, and the image forming process is interrupted in order to overlap the toner images. Doing so increases the load on the imaging system. For this reason, in many cases, the stop is not performed immediately after the stop button is pressed, but is stopped after the image copy operation during image formation is completed. For this reason, when the two-sided printing is performed, two transfer papers on which a color image is printed are ejected and the stop button is pressed.
An image forming process for two screens and two transfer sheets are wasted.

SUMMARY OF THE INVENTION It is an object of the present invention to improve such disadvantages and to provide an image forming apparatus capable of stably forming a color image and preventing waste of transfer paper.

[0007]

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 transfer paper 2
In the image forming apparatus that performs the next transfer, a toner image of a plurality of surfaces is formed on the intermediate transfer belt from the start of reading of the document, or a toner image of the first document on which reading of the document is started is formed on the intermediate transfer belt for one surface. The image forming apparatus further includes a transfer mode selecting unit for selecting whether to form toner images on a plurality of surfaces on the intermediate transfer belt after the second document.

The transfer mode selecting means selects the formation of toner images for a plurality of surfaces on the intermediate transfer belt from the start of reading the original when the original is a monochrome image, and starts reading when the original is a color image. It is preferable to select that the toner image of the first document is formed on the intermediate transfer belt for one surface, and that the toner images of a plurality of surfaces are formed on the intermediate transfer belt after the second document.

When forming a color image on an odd number of transfer papers, the transfer mode selecting means forms a toner image of the first document which has been read for one surface on an intermediate transfer belt, and forms two sheets of the document. It is desirable to select to form a plurality of surfaces of toner images on the intermediate transfer belt after the eye.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention comprises a document reading unit, an image forming unit, a primary transfer unit,
It has a next transfer unit, a paper feed unit, 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. The control unit includes a central control unit that processes image information of the document read by the document reading unit and manages the operation of the entire apparatus, an automatic color selection unit, and a transfer mode selection unit.

When a plurality of originals are set in the automatic original feeder, a start button is pressed, and the first one of the set originals is sent to the original reading unit to start the first scan. The means determines whether the set original is a color image or a monochrome image based on the image information obtained by the first scan. When the set document is a black and white image, the transfer mode selection means selects a two-chamfer mode in which two toner images on the intermediate transfer belt of the primary transfer unit are formed as the transfer mode. When the two-chamfer mode is selected, the central control unit transfers the toner image of the first document to the intermediate transfer belt at a predetermined timing after transferring the toner image of the first document to the intermediate transfer belt. Then, toner images for two surfaces are formed on the intermediate transfer belt. The two surfaces of the toner image are transferred to a sequentially transferred transfer sheet, fixed, and discharged.

The transfer mode selecting means selects the special two-chamfer mode when the set document is a color image. When the special two-chamfer mode is selected, the central control unit 201 sequentially forms black (BK), cyan (C), magenta (M), and yellow (Y) toner images of the first document on the photoconductor. After transferring the full-color toner image formed on the intermediate transfer belt to transfer the toner images of the second and subsequent documents to the intermediate transfer belt,
Perform in chamfer mode.

[0013]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus includes an image forming unit 100 including 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, and a document reading unit 6. It has a display unit 7 and a control unit 200. The control unit 200 includes a central control unit 201 that processes image information of a document read by the document reading unit 6 and manages the operation of the entire apparatus, an automatic color selection unit 202, and a transfer mode selection unit 203.

The image forming unit 1 includes an image forming unit 10 shown in FIG.
As shown in the configuration diagram of FIG. 0, the charging charger 12 and the image writing unit 13 disposed around the photoconductor 11 and the black (B)
K), cyan (C), magenta (M), yellow (Y)
And an electrostatic latent image formed on the photoreceptor 11 by a laser beam from the image writing unit 13. The image is visualized by the color developing unit 14 to form a toner image. The primary transfer unit 2 is an intermediate transfer belt 2
1 and primary transfer section 22 and a plurality of tension rollers 23 and 2
It has a next transfer roller 24, a reference position sensor 25, and a cleaning unit 26, and primarily transfers the toner image formed on the photoconductor 11 to the intermediate transfer belt 21. Intermediate transfer belt 21
Has a length equal to or more than twice the image size of which the circumference L is a reference, for example, A4 size, and can simultaneously transfer toner images for two surfaces.
Is provided. This intermediate transfer belt 21 is
Except during the primary transfer of the toner image on the photoconductor 1, the toner image is separated from the surface of the photoconductor 11 by a contact / separation mechanism (not shown),
It is pressed against the surface of the photoconductor 11 only at the time of the next transfer. 2
The next transfer unit 3 secondarily transfers the toner image transferred to the intermediate transfer belt 21 to the transfer paper 8. The paper feed unit 4 has a plurality of paper feed trays 41a to 41c.

The image forming unit 100 configured as described above
When the read original is one color, the intermediate transfer belt 2 of the primary transfer unit 2 is used as shown in the time chart of FIG.
The first reference mark 27 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. The secondary transfer unit 3 secondarily transfers the toner image to, for example, the transfer paper 8 fed from the paper feed tray 41a in accordance with the leading end of the toner image transferred to the intermediate transfer belt 21. Is heated and pressed to fix the transferred toner image. The toner remaining on the intermediate transfer belt 21 is collected by the cleaning unit 26.

When the 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 as shown in the time chart of FIG. , The black (B) formed on the photoconductor 11 based on the mark detection signal for each rotation.
K), cyan (C), magenta (M), yellow (Y)
Is primarily transferred onto the intermediate transfer belt 21, and the images of the respective colors are superimposed without displacement. After the primary transfer of the toner image of a predetermined color to the intermediate transfer belt 21, the secondary transfer unit 3 applies the toner image to the transfer paper 8 fed according to the leading end of the toner image transferred to the intermediate transfer belt 21. Next, the fixing unit 5 fixes the toner image transferred to the transfer paper 8 by heating and pressing.

The automatic color selection means 202 of the control unit 200
Determines whether the original is a color image or a black and white image when the original set in the automatic document feeder (not shown) is sent to the original reading unit 6 and first scanned by the original reading unit 6. The transfer mode selection unit 203 determines whether the toner images for a plurality of surfaces are formed on the intermediate transfer belt 21 of the primary transfer unit 2 from the start of reading the document, based on the determination result of the automatic color selection unit 202 and an instruction from the operation display unit 7. A selection is made as to whether the toner image of the first document whose reading has been started is formed on the intermediate transfer belt 21 for one surface and the toner images of a plurality of surfaces are formed on the intermediate transfer belt 21 for the second and subsequent documents. .

A description will be given of the operation when the toner image of the reference size, for example, an A4 size image is simultaneously transferred to the intermediate transfer belt 21 for two surfaces by the image forming apparatus having the above-described configuration.

When a plurality of documents are set in the automatic document feeder and the start button of the operation display section 7 is pressed, the first document among the documents set in the automatic document feeder is sent to the document reading unit 6. Then, the original reading unit 6 starts the first scan based on the mark detection signal of the reference mark 27 on the intermediate transfer belt 21. Control unit 20
The automatic color selecting means 202 determines whether the set original is a color image or a black and white image based on the image information obtained by the first scan.
Send to 03. When the automatic color selecting unit 202 sends a notification that the set original is a black and white image, the transfer mode selecting unit 203 transfers the toner images of two surfaces from the start of the original reading to the intermediate transfer of the primary transfer unit 2 as the transfer mode. The two-chamfering mode formed on the belt 21 is selected and sent to the central control unit 201. The central control unit 201 sets the transfer mode to 2
When the chamfer mode is selected, as shown in FIG. 5, the toner image 9a of the first document is transferred to the intermediate transfer belt 21 with the reference mark 27 as a reference, and then the second document is transferred at a predetermined timing. The toner image 97 b of the document is transferred to the intermediate transfer belt 2.
1 and the toner images 7a and 7b transferred to the intermediate transfer belt 21 are secondarily transferred to transfer paper 8 continuously fed from a paper feed tray 41a on which A4 size transfer paper 8 is set.

When the automatic color selecting unit 202 sends a notification that the set original is a color image, the transfer mode selecting unit 203 converts the toner image of the first original from which reading of the original has started as an intermediate transfer mode. Transfer belt 21
The central control unit 201 selects a special two-paneling mode in which a single original is formed and the second and subsequent pages of the original are performed in the two-paneling mode.
Send to When the special two-chamfer mode is selected as the transfer mode, the central control unit 201 causes the photoconductor 11 to set the black (B) of the first document on the photoconductor 11 as shown in the time chart of FIG.
K), and the formed toner image is transferred to the intermediate transfer belt 21. Subsequently, the cyan (C), magenta (M), and yellow (Y) toner images of the first document are transferred to the photosensitive member. 11 and superimposed on the intermediate transfer belt 21. When a full-color toner image is formed on the intermediate transfer belt 21, the toner image is transferred to the transfer paper 8, fixed, and discharged. Subsequently, in the two-chamfer mode, the toner images of two surfaces of the second document and the third document are transferred to the intermediate transfer belt 21, and
The secondary transfer is performed on the transfer paper 8 continuously fed from the paper feed tray 41a on which the transfer paper 8 of four sizes is set.

As described above, when the original is a color image, the toner image of the first original is transferred to the intermediate transfer belt 21 by one surface, so that there is a setting error such as color setting or image quality setting. When the stop button on the display unit 7 is pressed, the transfer sheet 8 on which the first image has been transferred is simply discharged, and waste of the transfer sheet 8 when there is a setting error can be prevented.

In the above embodiment, the case where the automatic color selecting means 202 determines whether the original set is a color image or a black-and-white image has been described. When the formation of a color image is selected, or when the formation of an odd number of color images with one document is selected, the transfer mode selection means 203 may select the special double chamfer mode. Even if the special two-chamfering mode is selected when forming an odd number of color images in this way, the toner image finally transferred to the intermediate transfer belt 21 is only for two surfaces, and all images are to be transferred. The forming time is almost the same as when the two-chamfer mode is selected, and a high-quality color image can be stably formed without lowering the image forming speed.

[0023]

As described above, according to the present invention, a plurality of surfaces of toner images are formed on the intermediate transfer belt from the start of reading of a document, or the toner images of the first document on which reading of a document is started are transferred to the intermediate transfer belt. One surface is formed on the belt, and a selection is made as to whether a toner image on a plurality of surfaces is formed on the intermediate transfer belt after the second document, so that the toner image is transferred to the intermediate transfer belt according to the type of the document. And the usability can be improved.

When the original is a color image, a toner image of the first original which has been read is formed for one surface on the intermediate transfer belt, and the toner images of a plurality of surfaces are transferred to the intermediate transfer belt for the second and subsequent originals. When the stop button is pressed due to a setting error such as color setting or image quality setting when forming a color image, only the transfer paper on which the first image is transferred is formed. Since the paper is discharged, it is possible to prevent transfer paper from being wasted when there is a setting error.

Further, when a color image is formed on an odd number of transfer sheets, the toner image of the first document which has been read is formed on the intermediate transfer belt for one surface, and a plurality of surfaces are formed on the second and subsequent sheets of the document. Is formed on the intermediate transfer belt, a high-quality color image can be stably formed without lowering the image forming speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a configuration diagram of an image forming unit of the embodiment.

FIG. 3 is a time chart illustrating an image forming process for a one-color original.

FIG. 4 is a time chart illustrating an image forming process of a full-color document.

FIG. 5 is a layout diagram illustrating a toner image transferred to an intermediate transfer belt by two chamfers.

FIG. 6 is a time chart showing an image forming process in a special two-chamfering mode.

[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 Original reading unit 7 Operation display unit 100 Image forming unit 200 Control unit 201 Central control unit 202 Automatic color selection unit 203 Transfer mode selection unit

Claims (3)

[Claims] An intermediate transfer belt capable of simultaneously transferring a toner image 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 transfer paper. In the image forming apparatus, the toner image of a plurality of surfaces is formed on the intermediate transfer belt from the start of reading of the document, or the toner image of the first document on which reading of the document is started is formed on the intermediate transfer belt for one surface, An image forming apparatus comprising: a transfer mode selecting unit that selects whether to form a plurality of toner images on the intermediate transfer belt on the second and subsequent sheets. 2. The image forming apparatus according to claim 1, wherein said transfer mode selecting means selects to form toner images for a plurality of surfaces on the intermediate transfer belt from the start of reading the document when the document is a monochrome image, and starts reading when the document is a color image. 2. The image forming apparatus according to claim 1, wherein the toner image of the first document is formed on the intermediate transfer belt for one surface, and the toner images of a plurality of surfaces are formed on the intermediate transfer belt after the second document. apparatus. 3. The transfer mode selecting means, when forming a color image on an odd number of sheets of transfer paper, forms a toner image of the first sheet of the read-started sheet on the intermediate transfer belt for one surface, and forms a second sheet of the document. 2. The image forming apparatus according to claim 1, wherein a plurality of toner images are formed on the intermediate transfer belt after the first sheet.