JP2003122084A - Image forming device - Google Patents

Abstract

(57) [Problem] To improve the accuracy of color matching correction in a multicolor image forming apparatus. When a primary transfer image of a position detection mark detected by a density detection sensor becomes a predetermined state, a control device controls a photoreceptor unit to form a position correction mark on an intermediate transfer belt for each color. The correction marks are transferred as primary transfer images 71 to 74 at the same time. When the position correction mark primary transfer image is sequentially detected by the mark detection sensor,
The control device obtains the average position of the correction marks according to the positions of the plurality of marks for each primary transfer image, and from the average position of the reference correction mark primary transfer image as a reference to the upstream side of the reference correction mark primary transfer image. Finding the detection time to the average position of the correction mark primary transfer image located as the detection timing,
The latent image formation timing of the photoconductor unit is controlled according to the detection timing.

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 using an electrophotographic process, and more particularly to a multicolor (color) image forming apparatus for forming an image using an intermediate transfer member.

[0002]

2. Description of the Related Art Generally, an electrophotographic image forming apparatus (image forming apparatus) which uses a so-called intermediate transfer body (intermediate transfer belt) when forming a color image by using an electrophotographic process.
It has been known. This image forming apparatus uses cyan (C),
Magenta (M), Yellow (Y), and Black (B
Each of the colors K) has a photoconductor unit including a photoconductor drum. That is, this image forming apparatus has a cyan photoconductor unit, a magenta photoconductor unit, a yellow photoconductor unit, and a black photoconductor unit, respectively, and each photoconductor unit along the intermediate transfer body. Are arranged. Then, the electrostatic latent images formed on the four photoconductor drums are developed using cyan toner, magenta toner, yellow toner, and black toner, respectively, to obtain toner images of respective colors. After the primary transfer of each color toner image to the intermediate transfer body in sequence, the transfer image transferred to the intermediate transfer body is secondarily transferred and fixed on the recording medium (paper),
I'm getting a color image.

Each photoconductor unit is provided with a photoconductor drum, and around the photoconductor drum, a charging unit, an exposure unit, a developing unit, a transfer unit (primary transfer unit), a cleaning unit, and a charge eliminating unit ( Eraser) is arranged. Then, after uniformly charging the surface of the photosensitive drum by the charger, an electrostatic latent image is formed on the surface of the photosensitive drum by the exposure unit. After that, the electrostatic latent image is developed by a developing device to form a toner image on the photosensitive drum, and the transfer device transfers the toner image on the photosensitive drum to the intermediate transfer member. Then, the residual toner remaining on the photosensitive drum is removed by the cleaning unit, and the surface of the photosensitive drum is further neutralized by the neutralizing unit.

As described above, after transferring the toner image as a primary transfer image onto the intermediate transfer member by each photoconductor unit, the primary transfer image is transferred onto the recording medium by using, for example, a secondary transfer device. A secondary transfer image is obtained. Thereafter, the secondary transfer image on the recording medium is fixed on the recording medium by the fixing unit to obtain a color image.

By the way, in the above-mentioned image forming apparatus, when the toner images of the respective colors are transferred to the intermediate transfer member, in order to prevent so-called color shift, alignment correction (image alignment correction) is performed between the respective photoconductor units. There is. Conventionally, when performing such alignment correction, one alignment correction mark image (position detection mark image) is provided for each photoconductor unit.
Is transferred to an intermediate transfer member, and the electrostatic latent image forming timing of each color photoconductor unit is corrected according to the position detection mark image. That is, the position detection mark image for detecting the positional deviation of each toner image is transferred from each photoconductor unit to the intermediate transfer member, and the position detection mark image of each color is detected by the mark detection sensor. In the controller,
In accordance with the detection signal from the mark detection sensor, the electrostatic latent image forming timing of each color photoconductor unit is corrected to prevent color misregistration. Then, such correction of the latent image formation timing is performed each time the toner images of the respective colors are transferred to the intermediate transfer member.

[0006]

However, in the conventional image forming apparatus, since one position detection mark image is transferred to the intermediate transfer member in each photoconductor unit, when performing the alignment correction, The accuracy of correction depends on the position detection mark image itself. For example, the accuracy of the correction is affected by the size of the position detection mark image, such as the width,
If the size of the position detection mark image is reduced, the alignment correction accuracy is improved, but in view of the detection accuracy of the mark detection sensor, the size of the position detection mark image is necessarily limited (position The detection mark image has a minimum image forming unit related to the accuracy of the mark detection sensor). In other words, the alignment correction accuracy depends on the minimum image forming unit of the position detection mark image, and there is a problem that the alignment accuracy cannot be improved beyond the minimum image forming unit.

On the other hand, in order to improve the alignment accuracy, a sensor with high detection sensitivity may be used, but if a sensor with high detection sensitivity is used, the above-mentioned minimum unit of image formation can be further reduced. Such a sensor is extremely expensive, and as a result, there is a problem that the cost of the image forming apparatus itself increases.

Further, in the conventional image forming apparatus, the latent image forming timing is corrected every time when the toner images of respective colors are transferred to the intermediate transfer member. Then, the calculation regarding the latent image formation timing must be performed, that is, the control device must confirm that there is no color shift.

An object of the present invention is to provide an image forming apparatus capable of improving the alignment correction accuracy without depending on the minimum image forming unit of the position detection mark image.

Another object of the present invention is to provide an image forming apparatus which can improve the alignment correction accuracy at low cost and with high accuracy.

[0011]

According to the present invention, an electrostatic latent image for image formed on an image carrier, which is arranged along a conveyance path and is provided corresponding to each color, and for position detection. A plurality of photoconductor units that develop the mark latent image to form an image toner image and an alignment toner image, and the image toner images that have been conveyed along a predetermined conveyance path are sequentially superimposed as an image primary transfer image. And an intermediate transfer body to which the position detection toner image is transferred at a predetermined position as a position detection mark primary transfer image, and the photoconductor unit is provided in accordance with the position detection mark primary transfer image. In the image forming apparatus configured to generate an image from the image primary transfer image by controlling the latent image formation timing of the position detection mark primary transfer image disposed on the downstream side of the photoconductor unit. A mark detection sensor which outputs a mark detection signal and a position detection mark primary transfer image based on the mark detection signal is in a predetermined state, and controls the photoconductor unit to color the intermediate transfer member. Control means for simultaneously transferring the position correction mark as a correction mark primary transfer image for each position, and when the position correction marks are sequentially detected by the mark detection sensor, the control means controls the correction mark primary transfer image. An image forming apparatus is obtained in which the detection timing of a transfer image is obtained and the latent image formation timing of the photoconductor unit is controlled according to the detection timing.

As described above, since the latent image forming timing is controlled based on the detection timing of the position correction mark primary transfer image for each color, each color is irrespective of the minimum image forming unit of the position detection mark image. The latent image formation timing can be corrected, and as a result, the accuracy of position adjustment correction (that is, color adjustment correction) can be improved.

For example, the control means may detect the position detection mark when the position detection mark primary transfer image has a width equal to or larger than a predetermined width or when the position detection mark primary transfer images are plural. The mark detection sensor may detect that the primary transfer image is in the predetermined state, and detect the density of the image primary transfer image.

Further, the control means is located, for example, on the upstream side of the reference correction mark primary transfer image after one of the correction mark primary transfer images is detected as a reference correction mark primary transfer image. The time until the correction mark primary transfer image is detected is the detection timing, the correction mark primary transfer image has a plurality of marks, and the control means averages the positions according to the positions of the plurality of marks. The position is determined, and the detection time from the average position of the reference correction mark primary transfer image to the average position of the correction mark primary transfer image located upstream of the reference correction mark primary transfer image is set as the detection timing. You may do it.

With this configuration, it is not necessary to provide a sensor for color matching correction, and moreover, an average position is obtained by using a plurality of lines as position correction marks, and the detection timing is obtained. Therefore, it is not necessary for the sensor to have high sensitivity, and as a result, it is possible to perform the alignment correction inexpensively and accurately.

Further, the control means does not change the latent image forming timing control based on the detection timing unless a preset number of marks are detected in the correction mark primary transfer image. A storage unit is provided for storing a detection timing as the latent image formation timing, and the control unit is based on the detection timing stored in the storage unit unless a preset number of marks are detected in the correction mark primary transfer image. It is preferable to control the latent image formation timing. Also,
It is preferable that the control unit controls the latent image formation timing based on the detection timing stored in the storage unit until the position detection mark primary transfer image reaches the predetermined state.

Since the detection timing is stored as the latent image formation timing in the storage means in this way, even if the correction mark primary transfer image is not normally detected, it is based on the detection timing stored in the storage means. Therefore, the latent image formation timing can be controlled.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. Incidentally, the dimensions of the components in the illustrated example,
Unless otherwise specified, the material, the shape, the relative arrangement, etc., are not intended to limit the scope of the present invention thereto, but are merely illustrative examples.

First, referring to FIG. 1, here, an LED using a color electrophotographic process is used as an image forming apparatus.
A printer will be described as an example. The illustrated LED printer includes an endless belt-shaped intermediate transfer body 11 as an intermediate transfer body (hereinafter, this intermediate transfer body is referred to as an intermediate transfer belt). A plurality of photoconductor units (toner image forming portions) are arranged along the rotation direction of the intermediate transfer belt 11 (conveying direction: indicated by solid arrows in the figure).

In the illustrated example, four photoconductor units 21 are provided.
To 24 are arranged along the intermediate transfer belt 11, and, for example, from the left side in the drawing, a black (BK) photoconductor unit 21, a cyan (C) photoconductor unit 22, and a magenta (M) photoconductor unit. 23 and a yellow (Y) photoconductor unit 24 are arranged in this order. B
The photoconductor unit 21 for K is the LED head 21 for BK.
a, BK photosensitive drum (image carrier) 21b, and BK
It is equipped with a developing device 21c (in FIG. 1,
For convenience of explanation, other components are omitted), LED
An electrostatic latent image is formed on the photosensitive drum 21b by the head 21a, and the electrostatic latent image is developed by the developing device 21c to form a toner image (BK toner image) on the photosensitive drum.

Similarly, the C photoconductor unit 22 is
The C LED head 22a, the C photoconductor drum 22b, and the C developing device 22c are provided, and the M photoconductor unit 23 and the Y photoconductor unit 24 are M LEDs.
The head 23a and the Y LED head 24a, the M photoconductor drum 23b and the Y photoconductor drum 24b, the M developing device 23c, and the Y developing device 24c are provided. Then, similar to the photoconductor unit 21, the C toner image, the M toner image, and the M toner image on the photoconductor drums 22b, 23b, and 24b, respectively.
A toner image and a Y toner image are formed.

Primary transfer rollers 31 to 34 are arranged facing the photoconductor drums 21b to 24b, and the photoconductor drums 21b to 24b and the primary transfer rollers 31 to 34 are arranged.
The intermediate transfer belt 11 is sandwiched between and. And
A density detection sensor 41 described later is arranged on the downstream side of the photoconductor unit 24.

As described above, the intermediate transfer belt 11 is conveyed in the direction of the solid line arrow in the figure, and the secondary transfer roller 51 is arranged on the downstream side in the rotational direction of the intermediate transfer belt 11. The recording paper 53 is supplied from the paper supply device (paper supply unit) 52 via the paper supply roller 52 a between the secondary transfer roller 51 and the intermediate transfer belt 11.

At the time of image formation, as described above,
Toner images are formed on the photoconductor drums 21b to 24b. The toner image on the photosensitive drum 21b is transferred to the intermediate transfer belt 11 by the primary transfer roller 31. Also in the photoconductor drums 22b to 24b, the photoconductor drum 2
A toner image is formed in the same manner as 1a, and the photosensitive drum 2
The toner images formed on 2b to 24b are sequentially transferred onto the intermediate transfer belt 11 by the primary transfer rollers 32 to 34. That is, in each of the photoconductor units 21 to 24, the toner image is transferred to the intermediate transfer belt 11 as a primary transfer image. Thus, for example, BK, C, M,
The Y-color toner images are transferred to the intermediate transfer belt 11 while being sequentially superposed.

As described above, the toner image (primary transfer image) transferred to the intermediate transfer belt 11 is sent toward the secondary transfer roller 51 as the intermediate transfer belt 11 is conveyed. Then, the toner image (primary transfer image) on the intermediate transfer belt 11 is transferred to the recording paper 53 by the secondary transfer roller 51 (secondary transfer). A fixing unit (fixing unit) 54 is disposed downstream of the recording sheet 53 in the conveying direction.
The secondary transfer image transferred onto the recording paper 53 is the fixing unit 5.
4, the recording paper 53 is pressed and heated and fixed. After that, the recording paper 53 is discharged to the discharge tray 5 of the discharge unit 55.
It is discharged to 5a.

Here, also referring to FIG. 2, during the image formation (printing process), the image data (print data) is an image processing controller (hereinafter simply referred to as a controller) 61.
Controller 61, the controller 61 decomposes the image data into color components (BK, C, M, and Y), and BK, C, M, and
And signals indicating Y (BK signal, C signal, M signal, and Y
Signal). BK signal, C signal, M signal, and Y
Before sending the signal, the controller 61 sends a mark print signal for printing the position detection mark to the LED heads 21a to 24a.

As a result, the LED heads 21a to 21
4a forms a mark latent image on the photosensitive drums 21b to 24b. After that, the controller 61 sets the LED head 21
The BK signal, the C signal, the M signal, and the Y signal are given to a to 24a, whereby the photosensitive drums 21b to 24a
A BK latent image, a C latent image, an M latent image, and a Y latent image are formed on b. These position detection mark latent image, BK latent image,
The C latent image, the M latent image, and the Y latent image are developed as described above to become the position detection mark toner image, the BK toner image, the C toner image, the M toner image, and the Y toner image, and the intermediate transfer belt. 11 is transferred.

The mark toner image transferred to the intermediate transfer belt 11 by the photoconductor units 21 to 24 is transferred to a position on the intermediate transfer belt 11 which is recognized as the same image position, and the primary transfer image ( The mark primary transfer image is a 1-dot line drawn in a direction orthogonal to the conveyance direction of the intermediate transfer belt 11.

As described above, the mark primary transfer image transferred onto the intermediate transfer belt 11 is the intermediate transfer belt 11
When the positional deviation (that is, color misregistration) occurs, the mark primary transfer image (1 dot line) is widened or the mark primary transfer image is transferred because it is transferred to the above-identified image position. Will be transcribed.

The density detection sensor 41 is a sensor for detecting the image density, and when the toner image density on the intermediate transfer belt becomes lower than a predetermined density, the toner density is adjusted by the controller 61, for example. In the example shown in FIG. 2, the density detection sensor 41 is connected to an arithmetic unit (CPU) 62, and the CPU 62 receives a detection signal of a mark primary transfer image from the density sensor 41 (hereinafter, this detection signal is referred to as a mark detection signal). Call). In the CPU 62, when the width of the mark primary transfer image indicated by the mark detection signal becomes equal to or larger than a predetermined width or a plurality of mark primary transfer images are transferred, the CPU 62 sends a color matching correction processing signal to the controller 61. Is sent.

When the color matching correction processing signal is received, the controller 61 executes the color matching correction processing. In the color matching correction process, the controller 61 sends a color matching correction mark print signal (hereinafter referred to as a correction mark print signal) to the LED heads 21a to 24a. This correction mark print signal is a signal for transferring a plurality of dot lines on the intermediate transfer belt 11 at equal intervals,
The LED heads 21a to 24a form latent mark images for correction on the photoconductor drums 21b to 24b in response to the correction mark print signal. This correction mark latent image is developed to form a correction mark toner image on the photoconductor drums 21b to 24b, and the correction mark toner image is transferred from the photoconductor drums 21b to 24b to the intermediate transfer belt 11 at the same time. .

Here, also referring to FIG. 3, here, the correction mark toner images transferred from the photosensitive drums 21b, 22b, 23b, and 24b to the intermediate transfer belt 11 are BK correction mark primary transfer images, respectively. , C correction mark primary transfer image, M correction mark primary transfer image, Y correction mark primary transfer image, and reference numerals 71 to 74. As shown in FIG. 3, each of the correction mark primary transfer images 71 to 74 has a plurality of dot lines that are drawn at equal intervals in a direction orthogonal to the transport direction of the intermediate transfer belt 11 (indicated by a solid arrow in FIG. 3). (Three dot lines are drawn at equal intervals in the example shown in FIG. 3), and these correction mark primary transfer images 71 to 74 are
The image is transferred in a range that can be distinguished from the images of the colors BK, C, M, and Y.

These correction marks primary transfer images 71 to 7
4 is sequentially detected by the density detection sensor 41 with respect to the conveyance of the intermediate transfer belt 11. In FIG. 3, first, the correction mark primary transfer image (Y color) 74 is the density detection sensor 41.
Is detected by the CPU 6 as a Y-color correction mark detection signal.
Given to 2. The CPU 62 obtains the position of each dot line of the correction mark primary transfer image 74 based on the Y-color correction mark detection signal, and obtains the average position (center position) of the correction mark primary transfer image 74 from a plurality of positions. (This average position is called the Y color correction mark average position).

Next, the correction mark primary transfer image (M color) 7
3 is detected by the density detection sensor 41 and given to the CPU 62 as an M color correction mark detection signal. The CPU 62 obtains the position of each dot line of the correction mark primary transfer image 73 based on the M color correction mark detection signal, and obtains the average position (center position) of the correction mark primary transfer image 73 from a plurality of positions. (This average position is called the M color correction mark average position). Then, the CPU 62 obtains the time from the Y color correction mark average position to the M color correction mark average position based on the transport speed, and detects the detection timing T.
It is stored in the non-volatile memory 63 as a (in this case, the average position of the Y color correction marks becomes the reference position. That is, the Y color correction mark primary transfer image becomes the reference mark primary transfer image).

Similarly, the correction mark primary transfer image (C
The color) 72 is detected by the density detection sensor 41 and is given to the CPU 62 as a C color correction mark detection signal. CPU
At 62, the correction mark primary transfer image 72 is obtained at the position of each dot line based on the C color correction mark detection signal,
The average position (center position) of the correction mark primary transfer image 72 is obtained from a plurality of positions (this average position is called the C color correction mark average position). Then, the CPU 62 obtains the time from the M color correction mark average position to reach the C color correction mark average position based on the transport speed, and stores it in the nonvolatile memory 63 as the detection timing Tb (in this case, The average position of the M color correction marks is the reference position.
That is, the M color correction mark primary transfer image becomes the reference mark primary transfer image).

Further, the correction mark primary transfer image (BK
(Color) 71 is detected by the density detection sensor 41 and is given to the CPU 62 as a BK color correction mark detection signal. CP
At U62, the position of each dot line of the correction mark primary transfer image 71 is obtained based on the BK color correction mark detection signal, and the average position (center position) of the correction mark primary transfer image 71 is obtained from a plurality of positions. (This average position is called the BK color correction mark average position). Then, in the CPU 62,
The time from the C color correction mark average position to the BK color correction mark average position is calculated based on the transport speed and stored in the nonvolatile memory 63 as the detection timing Tc (in this case, the C color correction mark is used). The average position becomes the reference position, that is, the C color correction mark primary transfer image becomes the reference mark primary transfer image).

After that, in the printing process, as described above, the BK toner image, the C toner image, the M toner image, and the Y toner image are transferred from the photosensitive drums 21b to 24b to the intermediate transfer belt 11 together with the toner images. At this time, the CPU 62 causes the detection timing Ta described above.
To Tc are given to the controller 61. Controller 6
In 1, the color matching timing is controlled according to these detection timings Ta to Tc. That is, the controller 6
1, the BK signal is sent to the LED head 21a to form a latent image on the photosensitive drum 21b, and then the detection timing Tc is reached.
When is passed, the C signal is sent to the LED head 22a. Furthermore, when the detection timing Tb elapses, the controller 61 sends an M signal to the LED head 23a, and when the detection timing Ta elapses thereafter, the controller 61 sets Y.
The signal is sent to the LED head 24a.

As a result, when the detection timing Tc elapses after the BK toner image is transferred to the intermediate transfer belt 11 by the photoconductor unit 21, the C toner image is transferred to the intermediate transfer belt 11 by the photoconductor unit 22 and further. After the detection timing Tb elapses, the M toner image is transferred to the intermediate transfer belt 11 by the photoconductor unit 23. Then, when the detection timing Ta further elapses, the Y toner image is transferred to the intermediate transfer belt 11 by the photoconductor unit 24.

By thus performing color registration correction, the latent image formation timing of each color can be corrected regardless of the minimum image formation unit of the position detection mark image. The accuracy of (that is, color matching correction) can be improved. In addition, it is not necessary to provide a sensor for color matching correction, and moreover, since the average position is obtained by using a plurality of lines as position correction marks and the detection timing is obtained, the sensor has high sensitivity. As a result, alignment correction can be performed inexpensively and accurately.

By the way, when obtaining the detection timings Ta to Tc as described above, BK, C, M and Y described above are used.
If a predetermined number of lines (here, three lines each) is not detected in the range (predetermined range) that can be distinguished from the image of each color, the CP
U62 recognizes that the detection operation is abnormal and invalidates the detection related to the position correction. Then, the CPU 62 outputs the default or sets the latent image forming timing of each color according to the detection timings Ta to Tc stored in the nonvolatile memory 62 in the previous detection.

As described above, when forming an image,
A position detection mark is printed, and this position detection mark,
That is, when the width of the position detection mark primary transfer image is equal to or larger than the predetermined width, or when a plurality of position detection mark primary transfer images are transferred, the color matching correction process is performed again. . Further, the CPU 62 does not have to be provided separately, and the controller 61 may also have the function of the CPU 62.

[0042]

As described above, according to the present invention, when the position detection mark primary transfer image is detected and the position detection mark primary transfer image reaches a predetermined state, the control means (CPU and controller). Controls the photoconductor unit to simultaneously transfer the position correction marks for each color to the intermediate transfer body as the correction mark primary transfer images, and when the correction mark primary transfer images are sequentially detected by the mark detection sensor, the control means Determines the detection timing of the correction mark primary transfer image and controls the latent image formation timing according to this detection timing, so that the latent image formation of each color is performed regardless of the minimum image formation unit of the position detection mark image. It is possible to correct the timing, and as a result, it is possible to improve the accuracy of the position adjustment correction (that is, the color adjustment correction).

Further, according to the present invention, after one of the correction mark primary transfer images is detected as the reference correction mark primary transfer image, the correction mark primary image positioned upstream of the reference correction mark primary transfer image is detected. Since the time until the transfer image is detected is set as the detection timing and the latent image formation timing is controlled based on this detection timing, the accuracy of the latent image formation timing can be improved.

Further, the correction mark primary transfer image has a plurality of marks, the control means obtains an average position thereof in accordance with the positions of the plurality of marks, and the reference position is calculated from the average position of the reference correction mark primary transfer images. If the detection time to the average position of the correction mark primary transfer image located on the upstream side of the correction mark primary transfer image is used as the detection timing, the accuracy of alignment correction can be further improved.

In addition, since the detection timing is stored as the latent image forming timing in the storage means (nonvolatile memory), even if the correction mark primary transfer image is not normally detected, it is stored in the storage means. The latent image formation timing can be controlled based on the detection timing.

Further, according to the present invention, it is not necessary to provide a sensor for color matching correction, and moreover, a plurality of lines are used as the position correction marks to obtain the average position thereof to obtain the detection timing. Therefore, it is not necessary for the sensor to have high sensitivity, and as a result, it is possible to perform the alignment correction inexpensively and accurately.

As described above, in the present invention, the latent image forming timing of each color can be corrected regardless of the minimum image forming unit of the position detection mark image, and the position adjustment correction (that is, color adjustment correction) can be performed. There is an effect that the accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a control mechanism for performing color matching timing control in the image forming apparatus shown in FIG.

3 is a diagram for explaining latent image formation timing control in the image forming apparatus shown in FIG.

[Explanation of symbols]

11 Intermediate transfer belt 21 to 24 photoconductor unit 31 to 34 Primary transfer roller 41 Concentration detection sensor 51 Secondary transfer roller 52 Paper feeder (paper feeder) 54 Fixing unit (fixing section) 61 Image processing controller 62 Arithmetic unit (CPU) 63 Non-volatile memory 71 to 74 correction mark primary transfer image

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA09 DE02 DE07 DE09 EA04                       EB06 EC03 EC06 ED04 ED06                       ED08 EE01 EE07 EE08 ZA07                 2H030 AA01 AB02 AD16 BB02 BB36                       BB42 BB56 BB63                 2H200 FA04 GA12 GA23 GA33 GA47                       GA49 GB22 GB25 HA02 HB12                       JA01 JC03 JC20 PB15 PB16                       PB20 PB39 PB40

Claims (9)

[Claims] 1. A toner for an image by developing an electrostatic latent image for image and a latent image for position detection, which are arranged along a conveying path and provided corresponding to each color and formed on an image carrier. A plurality of photoconductor units that form an image and a toner image for alignment, and the toner images for images that are transported along a predetermined transport path are sequentially superimposed and transferred as an image primary transfer image, and at the predetermined position. An intermediate transfer member onto which a position detection toner image is transferred as a position detection mark primary transfer image, and the latent image forming timing of the photoconductor unit is controlled according to the position detection mark primary transfer image to control the latent image formation timing. In an image forming apparatus configured to generate an image from an image primary transfer image, the position detection mark primary transfer image disposed on the downstream side of the photoconductor unit is detected and a mark detection signal is transmitted. When the position detection mark primary transfer image is in a predetermined state based on the mark detection sensor and the mark detection signal, the photosensitive member unit is controlled to correct the position correction mark for each color on the intermediate transfer member. And a control unit for simultaneously transferring as a work mark primary transfer image, and when the position correction marks are sequentially detected by the mark detection sensor, the control unit obtains the detection timing of the correction mark primary transfer image, An image forming apparatus, wherein the latent image forming timing of the photoconductor unit is controlled according to the detection timing. 2. The position detecting mark when the position detection mark primary transfer image has a width equal to or more than a predetermined width, or when the position detection mark primary transfer image has a plurality of positions. The primary transfer image is recognized as being in the predetermined state.
The image forming apparatus according to item 1. 3. The image forming apparatus according to claim 1, wherein the mark detection sensor also detects the density of the image primary transfer image. 4. The correction means is located on the upstream side of the reference correction mark primary transfer image after one of the correction mark primary transfer images is detected as a reference correction mark primary transfer image. The image forming apparatus according to claim 1, wherein the detection timing is set to a time until the mark primary transfer image is detected. 5. The correction mark primary transfer image has a plurality of marks, and the control means obtains an average position of the plurality of marks according to the positions of the plurality of marks, and the reference correction mark primary transfer image. 5. The detection time from the average position of the reference correction mark primary transfer image to the average position of the correction mark primary transfer image located upstream of the reference correction mark primary transfer image is set as the detection timing. Image forming device. 6. The control means does not change the latent image formation timing control based on the detection timing unless a preset number of marks are detected in the correction mark primary transfer image. The image forming apparatus according to claim 5. 7. The image forming apparatus according to claim 1, further comprising a storage unit that stores the detection timing as the latent image formation timing. 8. The control means controls the latent image formation timing based on the detection timing stored in the storage means while the position detection mark primary transfer image is in the predetermined state. The image forming apparatus according to claim 7, wherein the image forming apparatus is configured as described above. 9. A storage means for storing the detection timing as the latent image formation timing, wherein the control means stores in the storage means unless a preset number of marks are detected in the correction mark primary transfer image. The image forming apparatus according to claim 5, wherein the latent image forming timing is controlled based on the detected detection timing.