JPH1020616A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of accurately correcting color slurring caused in a multicolor toner image without causing secondary trouble. SOLUTION: This image forming device is provided with plural image carriers 1 on which the monochromic toner images of respective colors are formed and an intermediate transfer body 7 on which the respective monochromic toner images are superposed and transferred; and the multicolor toner image formed on the transfer body 7 is transferred on the transfer material P so as to form a specified outputted image. The device is provided with correction control means 17, 18 and 19 forming a pattern for control on each image carrier 1, reading the pattern for control transferred on the transfer body 7 and correcting the setting of the device based on the read image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus used as a color copying machine, a color printer, and the like.
More specifically, the present invention relates to an image forming apparatus that forms a plurality of single-color toner images, and forms the plurality of single-color toner images on a transfer material so as to overlap each other to form a multicolor toner image.

[0002]

2. Description of the Related Art Conventionally, the above image forming apparatus transports, for example, four monochromatic toner image forming sections for forming a black toner image, a yellow toner image, a magenta toner image, and a cyan toner image, respectively, and a transfer material such as paper. A transfer material transporting section, and arranging the four single-color toner image forming sections in a line, and arranging the transfer material transporting section so as to transport the transfer material along the array. It is configured such that the monochromatic toner images formed on the toner image forming unit can be sequentially transferred to the transfer material.

Each of the single-color toner image forming units includes, for example, a rotatable photosensitive drum, a uniform charging corotron for charging the photosensitive drum to a predetermined potential, and
A laser exposure device that exposes the photosensitive drum according to image information, and a developing device that develops the latent image with a toner of a predetermined color,
A transfer corotron for transferring the toner image to a transfer material. The single-color toner image forming unit forms a single-color toner image on the photosensitive drum by operating the uniformly charged corotron, the laser exposure device, and the developing device while rotating the photosensitive drum. Further, the laser exposure device includes, for example, a rotatable polygon mirror, and a light emitting element that irradiates the polygon mirror with exposure light from a predetermined direction, and the exposure light reflected by the polygon mirror is exposed to light. A latent image is formed on the photosensitive drum by causing the light emitting element to emit light at the timing of irradiating the photosensitive drum. Hereinafter, a portion between the photosensitive drum and the transfer corotron is referred to as a transfer position.

Further, the transfer material transporting section can accommodate, for example, a transfer belt rotatably disposed so as to pass through a transfer position of each of the single-color toner image forming sections, and a large number of sheets. A paper storage tray, a paper supply member for transporting paper from the paper storage tray to the transfer belt, a transfer material attracting charger for electrostatically attracting the paper to the transfer belt, and a transfer separated from the transfer belt A fixing device for fixing the multicolor toner image on the material.

In the above-described image forming apparatus, a predetermined single-color toner image is formed on each of the single-color toner image forming sections, and after the transfer material is attracted to the transfer belt, the transfer material passes through each of the transfer positions. By doing so, it is possible to form a multi-color toner image by sequentially transferring the single-color toner images formed in each single-color toner image forming unit to the transfer material.

[0006]

In the above-described image forming apparatus, each single-color toner image forming section forms a single-color toner image of each color, and transfers it at each transfer position to form a single-color toner image on a transfer material (transfer belt). To form a multicolor toner image.

Therefore, in the above-described image forming apparatus, if the settings of various apparatuses are not properly set, a hue change, a color shift, and the like occur, thereby deteriorating the image quality. Specifically, in the above-described image forming apparatus, for example, the timing at which the single-color toner image formed on each photosensitive drum is located at the transfer position and the timing at which the transfer belt conveys the transfer material to the transfer position do not match. In this case, the position where each single-color toner image is transferred is shifted, and color shift occurs in the multicolor toner image. In addition,
In this case, the color misregistration mainly occurs in a direction perpendicular to the transfer material transport direction. In the above-described image forming apparatus, for example, if the transfer direction of the transfer material by the transfer belt does not match the rotation direction of each photoconductor drum, or the position of each single-color toner image formed on each photoconductor drum is If they do not match, the position where each single color toner image is transferred is shifted, and a color shift occurs in the multicolor toner image. In this case, the color misregistration mainly occurs in the transfer material conveying direction. Next, in the above-described image forming apparatus, for example, when the rotation of the transfer belt is uneven or the roundness of the peripheral surface of the photosensitive drum is poor, density unevenness due to the density of the transferred single-color toner image itself occurs. However, color unevenness and magnification variation occur in the multicolor toner image. Further, in the above-described image forming apparatus, for example, when the rotation axes of the respective photosensitive drums are not parallel to each other, the direction of each single-color toner image is different for each color, and color shift occurs in the multicolor toner image. Would.

In the above-described image forming apparatus, the rotation unevenness of the photosensitive drum and the rotation cycle of the transfer belt also change due to changes in environmental conditions such as temperature and humidity. There is also a problem that the manner and degree of subtle changes in the short term and in the long term.

Therefore, prior to the development of the present invention, the inventors form each color misregistration correction pattern on each monochromatic toner image forming section, transfer them onto a transfer belt in a superimposed manner, and transfer them to an image. An image forming apparatus has been developed which reads the image with a sensor and changes the setting of the apparatus based on the amount of color shift occurring in the read image. However, in the image forming apparatus, since a single-color pattern is transferred onto a transfer belt to form a multi-color pattern, the rigidity, the degree of bending of the transfer belt, or the transfer conditions, etc., vary with the single-color toner image on the transfer material. Is different from the case where the image is transferred, and the color shift that occurs in the image obtained by reading the multicolor pattern is different from the color shift that will occur in the multicolor toner image formed on the transfer material. Would. In addition, the inventors have considered a method in which the above-described color misregistration correction pattern is also formed on paper, but in this method, a secondary amount of paper is consumed for correcting color misregistration. Problems arise. Therefore, an object of the present invention is to provide an image forming apparatus capable of accurately correcting a color shift occurring in a multicolor toner image without causing a secondary problem.

[0010]

That is, the present invention comprises a plurality of image carriers on which a single color toner image of each color is formed, and an intermediate transfer member on which the single color toner images are superimposedly transferred. An image forming apparatus that forms a predetermined output image by transferring a multicolor toner image formed on the intermediate transfer body onto a transfer material, forming a control pattern on each image carrier, The image forming apparatus includes a correction control unit that reads a control pattern transferred onto an intermediate transfer member and corrects settings of the apparatus based on the read image.

In the present invention, the image carrier may be any as long as it can form a single-color toner image of each color.
There is a photosensitive drum using an organic photosensitive material. In order to form a single-color toner image on the photosensitive drum, for example, the photosensitive drum is rotatably disposed, and the photosensitive drum is set at a uniform potential around the photosensitive drum. Uniform charging means for charging, exposure means for exposing the photosensitive drum in accordance with image information of each color to form an electrostatic latent image, and developing the electrostatic latent image with a developer to form a monochromatic toner image What is necessary is just to provide a developing means.

The above-mentioned intermediate transfer member is capable of transferring a single-color toner image formed on each of the image carriers in a superimposed manner and further transferring a multicolor toner image formed thereby on a transfer material. For example, there is an endless belt formed of polyimide.

In order to transfer the single-color toner images onto the intermediate transfer member in a superimposed manner, for example, the endless intermediate transfer belt is rotatably disposed, and the respective image bearing members are opposed to the belt. In a state where the members are arranged and the endless intermediate transfer belt is rotated, each single color toner formed on each image carrier may be sequentially transferred to the belt.

In order to transfer the multicolor toner image formed on the intermediate transfer member to a transfer material, for example, the endless intermediate transfer belt is rotatably provided, and the endless intermediate transfer belt is When the transfer belt is disposed in contact with the transfer belt, and the endless intermediate transfer belt is rotated, the transfer material is conveyed by the transfer belt, and the multicolor toner image is transferred onto the transfer material at the contact position. Good.

The correction control means may form a control pattern on each image carrier, read the control pattern transferred on the intermediate transfer member, and correct the setting of the apparatus based on the read image. For example, for example, image information is supplied to each of the single-color toner image forming units to form a control pattern, and the control pattern transferred onto the intermediate transfer body is disposed to face the intermediate transfer body. What is necessary is just to comprise so that it may read by a pattern reading means and correct the setting of an apparatus based on the read image.

The control pattern may be any pattern that can extract information necessary for controlling a predetermined setting by reading the control pattern.
There are a color shift correction patch and a density correction patch.
On the other hand, the setting correction target includes each exposure timing and the driving cycle of the photosensitive drum when correcting color misregistration, and the developing bias and the exposure of the developing device when correcting the density. There is light quantity. As a device for reading the pattern, a color CCD sensor or the like which reads the pattern by dividing the pattern into a large number of pixels is suitable.

In the image forming apparatus of the present invention, a single-color toner image is formed on each image carrier, and the single-color toner images are superimposed on the intermediate transfer member. A multicolor pattern can be formed under the same conditions as when forming on an intermediate transfer member.

In the above image forming apparatus, a control pattern is formed on each image carrier, the control pattern transferred on the intermediate transfer member is read, and the setting of the apparatus is corrected based on the read image. Since a control means is provided to read various multicolor patterns on the transfer material carrier and correct the setting of the apparatus, as shown in FIG. 9, the multicolor pattern on the intermediate transfer member is further transferred to the transfer material. After transferring on the carrier,
As in the case where the multi-color pattern on the transfer material transporter is read and corrected, color misregistration caused by rotation unevenness of the transfer material transporter and which should not appear in the multicolor toner image is eliminated. There is no case where color misregistration correction is performed in a state where it is included.

As shown in FIG. 10, in an image forming apparatus having one photosensitive drum 1 and an intermediate transfer member 7, the intermediate transfer member 7 is rotated a plurality of times so as to rotate on the photosensitive drum 1. In order to transfer the multicolor toner image formed on the intermediate transfer member 7 to the transfer material P, the transfer material is conveyed so as to be in contact with the intermediate transfer member 7. When the transfer member 20 is provided, it is essential that the transfer material transfer member 20 is disposed so as to be capable of coming and going in order to form an image. When the apparatus is provided with a transfer material transporting body for transferring the multicolor toner image formed on the intermediate transfer body to the transfer material, it is not necessary to dispose the transfer material transporting body so as to be able to come and go. Absent.

However, in the above-described image forming apparatus, the transfer material transporting member is disposed so as to be able to contact and separate from the intermediate transfer member. When the member is brought into contact with the intermediate transfer member and a control pattern is formed on the intermediate transfer member, the transfer material transporting member may be separated from the intermediate transfer member.

Further, the switching of the contact / separation of the transfer material conveyance body is performed by:
As long as the control pattern is located at the contact position between the transfer material conveyance body and the intermediate transfer body, at least the transfer material conveyance body and the intermediate transfer body may be separated.

Thus, in the image forming apparatus, the multicolor toner image for output can be transferred to the transfer material, and the toner constituting the control pattern does not adhere to the transfer material conveyance body. There is no need to provide a cleaning unit for removing the toner from the transfer material conveyance body.

In order to dispose the transfer material transporting member so as to be able to contact and separate, for example, as shown in FIG. 6, when the transfer material transporting member is a transfer roll 20, the entirety thereof is an intermediate transfer member. It is sufficient to dispose it so that it can move in the direction of coming and going with 7, and
As shown in FIG. 7, when the transfer material transporting body is the transfer belt 10, the entirety thereof is disposed so as to be movable in a direction in which the transfer belt is brought into contact with or separated from the intermediate transfer body 7, or as shown in FIG. ,
A baffle 16 may be provided so that the transfer belt 10 contacts and separates from the intermediate transfer body 7.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image forming apparatus of the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 FIG. 1 shows a full-color image forming apparatus according to the present embodiment. The image forming apparatus includes an image input unit (IIT) that reads an image on a document sheet, an image processing unit (IPS) that forms output image information according to the image information, and a transfer material such as a sheet. And an image output unit formed on P.

The image output section includes four single-color toner image forming means for forming a single-color toner image of each color based on black, yellow, magenta, and cyan color image information, and superimposing the plurality of single-color toner images. Multicolor toner image forming means for forming a multicolor toner image, image forming means for forming the multicolor toner image on the transfer material P to form a predetermined full-color image, and image output for appropriately operating each of these means Unit control means.

As shown in FIG. 2, the single-color toner image forming means is rotatably disposed on the photosensitive drum 1 and is disposed around the photosensitive drum 1.
Charging corotron 2 for charging the photosensitive drum 1 to a uniform potential, and the photosensitive drum 1
A laser exposure device 3 for exposing the image in accordance with the image information of each color to form an electrostatic latent image, and
A developing unit 4 for developing the electrostatic latent image with a developer to form a single-color toner image of a predetermined color; and a transfer corotron 5 disposed around the photosensitive drum 1 for transferring the single-color toner image
And a photoconductor driving stepping motor 6 for driving the photoconductor drum 1 to rotate at a predetermined cycle.

The laser exposure device 3 controls a polygon mirror 3a rotatably disposed, a laser diode 3b for irradiating the polygon mirror 3a with exposure light, and controls light emission of the laser diode 3b according to image information. And a polygon mirror stepping motor 3d for rotating and driving the polygon mirror 3a at a predetermined cycle and phase. The photosensitive drum 1 is exposed with light reflected by the polygon mirror 3a. .

The single-color toner image forming means forms a predetermined single-color toner image on the photosensitive drum 1 by performing charging, exposure and development while rotating the photosensitive drum 1 and the polygon mirror 3a. I do. In the following,
The space between the photosensitive drum 1 and the transfer corotron 5 is called a transfer position.

The multicolor toner image forming section includes an endless intermediate transfer belt 7 rotatably disposed, an intermediate transfer belt driving stepping motor 8 for driving the intermediate transfer belt 7 to rotate, and an intermediate transfer belt An intermediate transfer belt cleaner 9 for cleaning the belt 7, and the intermediate transfer belt 7 is disposed so as to sequentially pass through the transfer positions of the single-color toner image forming units, so that the respective single-color toner images are removed. Each single-color toner image formed on the forming section is transferred onto the intermediate transfer belt 7, and a multicolor toner image is formed on the intermediate transfer belt 7.

The image forming means is arranged to face the intermediate transfer belt 7, and transfers the transfer material P by sucking and transferring the transfer material P, and supplies the transfer material P to the transfer material transfer belt 10. A registration roll 11, a pair of fixing rolls 12 for overheating and pressurizing the transfer material P separated from the transfer material transport belt 10, and a stepping for the transfer material transport belt for rotating and driving the transfer material transport belt 10 at a predetermined cycle. A motor 13, a registration roller stepping motor 14 for rotatingly driving the registration roll 11, a secondary transfer corotron 15 disposed opposite the intermediate transfer belt 7 via the transfer material transport belt 10, The transfer material transport belt 10 is disposed on the upstream side in the rotation direction of the transfer material transport belt 10 from the next transfer corotron 15, and the transfer material transport belt 10 And a baffle 16 to contact and separate the transfer belt 7, the transfer material conveying belt 1 in the baffle 16
The multi-color toner image formed on the intermediate transfer belt 7 is transferred onto the transfer material P by rotating the transfer material transport belt 10 and the registration roll 11 in a state where the transfer roller P is in contact with the intermediate transfer belt 7. And then the fixing roll 1
In Step 2, a predetermined full-color image is formed on the transfer material P by overheating and pressurizing the transfer material P. The position of the baffle 16 at which the transfer material transport belt 10 and the intermediate transfer belt 7 contact each other is called a home position, and the transfer material transport belt 10
The position of the baffle 16 at which the and the intermediate transfer belt 7 are separated is referred to as a retreat position.

The image output section control means is disposed opposite to the intermediate transfer belt 7, and is provided with a registration control CCD sensor 17 for sampling a registration control pattern. Based on an image density correction CCD sensor 18 for sampling a correction pattern and the read images of these sensors 17 and 18,
An image output unit control main body 19 for controlling members of the image output units;
By controlling the rotation of 8, 13, and 14 and the operation timing of the exposure control circuit 3c, synchronous control is performed so that color misregistration does not occur, and the developing bias applied to the developing device 4 and the light emission amount of the laser diode 3b are controlled. Thus, an image can be formed with a predetermined image density.

The image output unit control main body 19
As shown in FIG. 3, first, the baffle 16 is moved to the evacuation position, and then a predetermined correction sequence is started (S
1). Further, in the correction sequence, the image output unit control main body 19 first forms a predetermined control pattern on each single-color toner image forming unit, and transfers all the patterns to the intermediate transfer belt 7 (S2). Next, the multi-color control patterns formed on the intermediate transfer belt 7 are read by predetermined CCD sensors 17 and 18 (S3). Further, the image output unit control main body 19 calculates the color shift amount or density of each color, and calculates a correction value for each member (S
4). Finally, the correction value is set for each member by the image output unit control main body 19, and the correction sequence ends (S5). Finally, the image output unit control main body 19 returns the baffle 16 to the home position (S6).

For example, when correcting a color shift occurring in the driving direction of the intermediate transfer belt 7, as shown in FIG. 4, lines of each color are arranged at predetermined intervals in the direction. Forming a color misregistration correction control pattern,
The shift ΔX of the interval in the read image obtained by sampling the multicolor pattern is obtained (in the figure, the shift amounts of the other colors are obtained based on the black pattern), and the above-described respective colors are corrected so as to correct the color shift of each color. What is necessary is just to control the rotation of the stepping motor and the operation timing of the exposure control circuit 3c.

In this embodiment, in the image forming apparatus, the sequence is executed during non-image formation to correct various settings of the apparatus. An image was formed.
As a result, in the image forming apparatus, color shift and density unevenness in the full-color image were improved, and a high-quality image could be obtained.

Second Embodiment An image forming apparatus according to the second embodiment is different from the first embodiment except that the sequence executed by the image output unit control main body 19 is different.
Is the same as

After moving the baffle 16 to the retracted position as shown in FIG.
7), DC registration correction (S8), AC registration correction (S
9) and the minute DC registration correction (S10) to return the baffle 16 to the home position (S10).
11).

The DC registration correction (S8) corrects a color misregistration of about several mm. For example, a control pattern is arranged so that each single-color patch is arranged at intervals of 30 mm in the driving direction of the intermediate transfer belt 7. Compose the pattern
By sampling at a cycle of about 00 msec, an appropriate read image can be obtained, and based on that, the rotation of each stepping motor and the operation timing of the exposure control circuit may be controlled.

The AC registration correction (S9) is for correcting a color misregistration of about several hundred μm. For example, a control pattern for arranging single-color patches at 1 mm intervals in the driving direction of the intermediate transfer belt 7 is used. And the pattern is 6
An appropriate read image can be obtained by sampling at a cycle of about msec, and the rotation of each stepping motor may be controlled based on the image.

The micro DC registration correction (S10) is for correcting a color shift of about several tens of μm. For example, the control is performed so that the single color patches are arranged at intervals of 4 mm in the driving direction of the intermediate transfer belt 7. By forming a pattern and sampling the pattern at a cycle of about 25 msec, an appropriate read image can be obtained, and based on that, the rotation of each stepping motor and the operation timing of the exposure control circuit can be controlled. Good.

The detailed sequence of each of these registration corrections is the same as the correction sequence of the first embodiment (see FIG. 3A). In addition, since each of these registration corrections is performed in the order of DC registration correction (S8), AC registration correction (S9), and minute DC registration correction (S10), reading of the registration correction sensors 17, 18 in each registration correction. The resolution in each correction can be sequentially improved by narrowing the image range, and each registration correction can be performed accurately and effectively.

In this embodiment, in the above-described image forming apparatus, after correcting various settings of the apparatus during non-image formation, the image input unit reads an image on a document sheet to form a predetermined full-color image. As a result, in the image forming apparatus, high-quality images could be obtained without causing color shift or density unevenness in the full-color images.

[0043]

As described above, in the image forming apparatus of the present invention, a plurality of image carriers on which a single-color toner image of each color is formed are rotatably disposed, and the above-described single-color toner images are transferred in a superimposed manner. And a multi-color toner image formed on the intermediate transfer body is transferred onto a transfer material so as to form a predetermined output image, and on each image carrier. A control pattern is formed, the control pattern transferred onto the intermediate transfer member is read, and correction control means for correcting the setting of the apparatus based on the read image is provided. Can form a multicolor pattern, and since the multicolor pattern can be read without including an unnecessary color shift component, the multicolor pattern is generated in the multicolor toner image without causing a secondary problem. Correct color misregistration accurately Can.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram of a single-color toner image forming unit in FIG. 1;

FIG. 3 is a sequence executed by an image output unit control main body of FIG. 1;

FIG. 4 is an example of a color misregistration correction control pattern and an example of occurrence of color misregistration.

FIG. 5 is a sequence executed by an image output unit control main body according to the second embodiment of the present invention.

FIG. 6 shows a configuration example (part 1) of the present invention.

FIG. 7 is a configuration example (2) of the present invention.

FIG. 8 is a configuration example (part 3) of the invention.

FIG. 9 is an explanatory diagram of a color shift error that occurs when a control pattern is transferred to a transfer material transporting body.

FIG. 10 is a configuration example (comparative example) of forming a multicolor toner image using one photosensitive drum and a latent image intermediate transfer member.

[Explanation of symbols]

1: photosensitive drum (image carrier), 7: intermediate transfer belt (intermediate transfer member), 17, 18, 19: correction control means, 1
0: transfer material transport belt (transfer material transport body), 20: transfer roll (transfer material transport body), 16: baffle.

Claims (8)

[Claims] 1. An image forming apparatus comprising: a plurality of image carriers on which a single-color toner image of each color is formed; and an intermediate transfer body on which the single-color toner images are superimposedly transferred. An image forming apparatus that forms a predetermined output image by transferring a multicolor toner image onto a transfer material, forms a control pattern on each image carrier, and transfers the control pattern onto an intermediate transfer body. An image forming apparatus comprising: a correction control unit that reads a pattern and corrects settings of the apparatus based on the read image. 2. The apparatus according to claim 1, wherein the control pattern is a color misregistration correction patch, and the correction control means corrects the setting of the apparatus so as to correct the color misregistration based on a read image of the patch. 2. The image forming apparatus according to 1. 3. The apparatus according to claim 1, wherein the control pattern is a density correction patch, and the correction control means corrects the setting of the apparatus so as to correct the image density based on the read image of the patch. The image forming apparatus as described in the above. 4. A plurality of image carriers on each of which a single-color toner image is formed, an intermediate transfer member on which each of the single-color toner images is transferred in a superimposed manner, and an image transfer member arranged to be able to contact and separate from the intermediate transfer member. Forming a control pattern on the transfer material conveying body for conveying the transfer material and each image carrier, reading the control pattern transferred on the intermediate transfer body, and correcting the setting of the apparatus based on the read image Correction transfer means, when the multicolor toner image for output formed on the intermediate transfer member is transferred to the transfer material, the transfer material carrier is brought into contact with the intermediate transfer member, and the intermediate transfer member An image forming apparatus, wherein a transfer material transport member is separated from an intermediate transfer member when a control pattern is formed thereon. 5. The method according to claim 1, wherein at least the transfer material transport member and the intermediate transfer member are separated from each other while the control pattern is located at the contact position between the transfer material transport member and the intermediate transfer member. The image forming apparatus according to claim 4. 6. The image forming apparatus according to claim 4, wherein the transfer material transporting body is a transfer roll, and the entirety of the transfer material transporting body is arranged so as to be movable in a direction of coming into contact with and separating from the intermediate transfer body. 7. The image forming apparatus according to claim 4, wherein the transfer material transporting member is a transfer belt, and the entire transfer material transporting member is disposed so as to be movable in a direction of coming into contact with and separating from the intermediate transfer member. 8. The image forming apparatus according to claim 4, wherein the transfer material transporting body is a transfer belt, and a baffle is provided so as to make the transfer belt contact and separate from the intermediate transfer body.