JP2002174992A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality color image free from color slurring by detecting a resist pattern on a belt while preventing erroneous detection caused by the flaw or the soiling of the belt and performing exact resist correction. SOLUTION: This image forming device is provided with a resist controller consisting of photosensors 60 and 61 and a control unit 70, and the unit 70 is equipped with a CPU 801, a photodetector circuit 807, a pattern width detection part 804 and a pattern width and position storage part 805. The respective color resist patterns formed on an intermediate transfer belt are detected by the photosensor and pattern width is detected after signal processing. Then, the pattern whose width is equal to or above specified width T is stored in the storage part 805 as correction data and the resist correction is performed. Before the resist correction, the flaw is detected for the belt where the pattern is not formed yet. When the maximum width C of the detected flaw shows C>=T with respect to T, T is updated to C. When the maximum width C shows C>=A with respect to the minimum width A of the pattern in the previous correction, the pattern is formed in thicker width than C as necessary.

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 employing an electrophotographic system, an electrostatic system, or the like, and more particularly, to correcting a color shift of an image at the time of forming a multiple image using a recording material carrier or an intermediate transfer member. The present invention relates to an image forming apparatus provided with a correction device that performs the correction.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image has been formed by irradiating a photosensitive drum with a laser beam light modulated according to recorded information or light from a light emitting element such as an LED, and developing the latent image. And a plurality of image forming units that visualize the toner image as a toner image, and while the recording material such as paper is sequentially conveyed to each image forming unit by the recording material conveying belt, the toner images of each color on each photosensitive drum are multiplex-transferred onto the recording material. Or an image forming apparatus that forms a color image on a recording material by a method such as transferring the toner images of each color on each photosensitive drum onto the intermediate transfer belt in a multiplex manner, and then transferring the toner images collectively from the intermediate transfer belt to the recording material. Has been proposed.

In this type of image forming apparatus, the image forming apparatus is formed on each photosensitive drum due to a mechanical mounting error between the photosensitive drums, an optical path length error of each laser beam light, an optical path change, and a warpage due to an ambient temperature of the LED. The registration (abbreviated as “register”) of each of the color toner images thus formed may not be matched on the recording material to be finally transferred by multiple transfer.

For this reason, a resist pattern (registration correction pattern) formed by transferring from each photosensitive drum onto a recording material conveying belt or an intermediate transfer belt is read by a photo sensor, and a resist of each color corresponding to each photosensitive drum is read. The shift is detected and the image signal is electrically corrected based on the shift to temporally change the image forming start position with respect to the photosensitive drum, or by driving a folding mirror provided in the laser beam optical path, thereby changing the optical path. By correcting the length or the optical path, the image forming start position for the photosensitive drum is mechanically changed, or both of them are used to change the image forming start position.

Various types of registration patterns have been considered. For example, Japanese Patent Application Laid-Open No. 2000-988
In No. 10, a second belt symmetrically arranged at a predetermined angle with respect to the moving direction of the conveying belt or the intermediate transfer belt (hereinafter, simply referred to as a belt if there is no misunderstanding) across a virtual line in the width direction perpendicular to the moving direction. A pattern consisting of one line segment and a second line segment is proposed. Such a registration correction pattern is formed along the moving direction at both ends in the width direction of the belt for each color, and as shown in FIG. The light passes below the detection field of view of the arranged photosensors 60 and 61 and is detected by the photosensors.

Since the detection of patterns by the photosensors 60 and 61 is the same, the detection by one of the sensors 60 will be described below. The belt 31 is made of a material having a reflectance higher than that of the pattern 203 with respect to light emitted by the LED 201 of the photosensor 60, for example, infrared light. The pattern 203 can be detected by the difference in the reflectance.

FIG. 8 shows a change in the light receiving output of the photo sensor 60 which has detected the belt 31 on which the pattern 203 has been formed. FIG. 9 shows a light receiving circuit for converting the light receiving output of the photo sensor 60 into a pulse signal.

The reflected light of the light emitted from the LED 201 of the photosensor 60 to the belt 31 is reflected by the phototransistor 20.
2, the photocurrent flows through the phototransistor 202, and this output current is converted into a voltage by the resistor 407 of the light receiving circuit.
04 and an operational amplifier 401. When the light from the LED 201 detects a portion of the belt 31 where the pattern 203 is not formed, the amount of reflected light at that portion is large.
A large amount of photocurrent flows through the phototransistor 202 receiving this, and the output voltage after amplification becomes a high voltage level (belt detection level). Next, when the pattern 203 is detected, since the amount of reflected light is small, a smaller photocurrent flows through the phototransistor 202 than in the belt portion, and the output voltage after amplification is at a low voltage level (pattern detection level).
become.

Therefore, when the photo sensor 60 detects the belt in the order of the belt portion → the pattern portion → the belt portion, the output voltage 301 drops from the belt detection level to the pattern detection level as shown in FIG. A downwardly convex curve is obtained. A threshold level is set by the variable resistor 406 of the light receiving circuit at an intermediate level between the transfer belt detection level and the pattern detection level, and the detection voltage value (output voltage) is compared with the threshold level by the comparator 405. As shown in b), a pulse pattern detection output 302 can be created.

If the pattern of each color sequentially sent by the belt 31 is detected by the photosensor 60 and its detection output 302 is read, the registration deviation of each color can be detected from the pattern interval and the like, and as described above, the image forming is performed. The color shift of the image can be automatically corrected by changing the start position temporally or mechanically.

[0011]

However, if unexpected dirt or scratches occur on the conveyor belt or the intermediate transfer belt, the reflectance decreases at this portion or the reflected light does not return to the photo sensor. In some cases, the photosensor may erroneously detect the stained or scratched portion as a resist pattern. As a result, there arises a problem that detection data due to dirt and scratches that should not be used is misused as registration data, and accurate registration correction (color shift correction) cannot be performed.

Accordingly, an object of the present invention is to detect a resist pattern formed on a recording material conveying belt or an intermediate transfer belt, and to correct registration by preventing erroneous detection due to scratches or dirt on the belt. An object of the present invention is to provide an image forming apparatus capable of realizing a proper registration correction and obtaining a high-quality color image without color shift.

[0013]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
An image carrier on which an image is formed, an intermediate transfer body, first detection means for detecting a detection image transferred from the image carrier to the intermediate transfer body, and detection by the first detection means Correction means for correcting the image forming conditions based on the result, in the image forming apparatus, a second detection means for detecting the surface state of the area of the intermediate transfer body on which the detection image is not formed, An image forming apparatus comprising: a control unit configured to control a formation condition of the image for detection formed on the image carrier based on a detection result by the second detection unit.

According to the present invention, a plurality of the image carriers are provided, and the image for detection is transferred from each of the image carriers to the intermediate transfer member. The correction means corrects the position of an image formed on each of the image carriers temporally or mechanically based on a detection result detected by the first detection means. In the moving direction of the intermediate transfer body, the control unit controls the length of the image for detection based on the length of an area where the output of the second detection unit is equal to or less than a predetermined value. The length of the image for detection is longer than the length of the region where the detection output by the second detection means is equal to or less than a predetermined value.

According to the present invention, an image carrier on which an image is formed, a recording material carrier for carrying a recording material, and an image for detection transferred from the image carrier to the recording material carrier are detected. An image forming apparatus that corrects an image forming condition based on a detection result by the first detecting unit, wherein the recording material carrier on which the image for detection is not formed is provided. A second detection unit configured to detect a surface state of the area; and a control unit configured to control a condition for forming the image for detection formed on the image carrier based on a detection result obtained by the second detection unit. An image forming apparatus characterized in that:

According to the present invention, a plurality of image carriers are provided, and the image for detection is transferred from each image carrier to the recording material carrier. The correction means corrects the position of an image formed on each of the image carriers temporally or mechanically based on a detection result detected by the first detection means.
In the moving direction of the recording material carrier, the control means controls the length of the image for detection based on the length of an area where the detection output by the second detection means is equal to or less than a predetermined value. The length of the image for detection is longer than the length of the region where the detection output by the second detection means is equal to or less than a predetermined value.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a sectional view of an image forming apparatus embodying the present invention. The image forming apparatus of the present embodiment is an electrophotographic color image forming apparatus, in which a plurality of image forming units considered to be particularly effective for the present invention are arranged in parallel, and an intermediate transfer system is adopted.

The present color image forming apparatus has an image reading section 1R.
And an image output unit 1P. The image reading unit 1R optically reads a document image, converts it into an electric signal, and sends it to the image output unit 1P. The configuration is well-known, and has no particular relation to the present invention, so that detailed description is omitted. .

The image output unit 1P is roughly divided into an image forming unit 10 in which four stations a, b, c, and d are arranged side by side (the basic configuration of each of the stations a to d is the same); Intermediate transfer unit 30, fixing unit 4
0, cleaning unit 50 and control unit 70
Consists of

The individual units will be described in detail.
The stations a, b, c, and d of the image forming unit 10 include photosensitive drums 11a, 11b, 11c, and 1 as image carriers.
1c, the photosensitive drums 11a to 11d are pivotally supported at their centers and are driven to rotate in the direction of the arrow. Photosensitive drum 11
a, 11b, 11c, and 11d, the primary chargers 12a, 12b, 12c, 12
d, optical systems 13a, 13b, 13c, 13d, folding mirrors 16a, 16b, 16c, 16d, developing device 14
a, 14b, 14c and 14d are arranged.

A toner image is formed on the photosensitive drum 11 (11a to 11d) by an image forming process. First, a primary charger 12 (12a to 12a) is provided on the surface of the photosensitive drum 11.
d), a charge having a uniform charge amount is given, and a light beam such as a laser beam modulated in accordance with a recording image signal generated by the optical system 13 (13a to 13d) is returned to the turning mirror 16 (16a to 16d). Exposure is performed on the photosensitive drum 11 through the surface of the photosensitive drum 11 to form an electrostatic latent image on the surface of the photosensitive drum 11. The electrostatic latent image on the photosensitive drum 11 is developed by the developing device 14 (14a to 14d) and visualized as a toner image. Developing devices 14a, 14b, 14c, 1
Reference numeral 4d contains developers (toners) of four colors of black, magenta, cyan, and yellow.
The upper latent image is formed into a black, magenta, cyan, and yellow toner image by development.

Photosensitive drums 11a, 11b, 11c, 11
Below d, primary transfer areas Ta, Tb, Tc, and Td are formed in which the intermediate transfer belt 31 contacts and transfers the toner image on the photosensitive drum to the intermediate transfer belt 31. The back side (inner side) of the intermediate transfer belt 31 in the primary transfer area
Include primary transfer chargers 35a, 35b, 35c, 35
d is arranged. Primary transfer areas Ta, Tb, Tc,
On the downstream side in the rotation direction of the photosensitive drums 11a, 11b, 11c, 11d of Td, cleaning devices 15a, 15b,
15 c and 15 d are provided, and the transfer residual toner remaining on each photosensitive drum 11 without being transferred to the intermediate transfer belt 31 is scraped off to clean the surface of the photosensitive drum 11.

The paper feed unit 20 includes cassettes 21a and 21b containing the recording material P, a manual feed tray 27, and pickup rollers 22a and 2 that feed the recording material P one by one from the cassettes 21a and 21b or from the manual tray 27.
2b and 26, a sheet feeding roller pair 23 for conveying the recording material P sent from each pickup roller to the registration rollers 25a and 25b, a sheet feeding guide 24, and the recording material P in accordance with the image forming timing of the image forming unit. The above-described registration roller 25a to be sent to the next transfer area Te,
25b.

The intermediate transfer unit 30 sandwiches the intermediate transfer belt 31 with a plurality of rollers, that is, a driving roller 32 for transmitting drive to the belt 31, a driven roller 33 and a belt 31 driven by the rotation of the belt 31. , And is wound around a secondary transfer facing roller 34 facing the secondary transfer area Te, and a primary transfer plane A is formed between the driving roller 32 and the driven roller 33.

The drive roller 32 is provided on the surface of the metal roller.
Rubber (urethane rubber or chloroprene rubber) having a thickness of several mm is coated to prevent a slip portion from the belt 31, and the driving roller 32 is driven to rotate by a pulse motor (not shown).

A secondary transfer roller 36 is disposed opposite the secondary transfer opposing roller 34 with the intermediate transfer belt 31 interposed therebetween, and the secondary transfer roller 36 is pressed against the intermediate transfer belt 31 with an appropriate pressure. The secondary transfer area Te is formed by the contact nip portion. Downstream of the secondary transfer area Te of the intermediate transfer belt 31, a cleaning device 50 for cleaning the surface (image forming surface) of the intermediate transfer belt 31 is provided. This unit 50 includes a blade 51 that contacts the surface of the belt 31. , And a waste toner box 52 for storing the toner removed from the surface of the belt 31 by the blade 51.

The fixing unit 40 includes a fixing roller 41 having a heat source such as a halogen heater therein, a pressing roller 42 pressed against the fixing roller 41 (the pressing roller 42 may also have a heat source), A guide 43 for guiding the recording material P to a contact nip portion between the roller pairs 41 and 42;
Inner and outer discharge rollers 4 for further guiding the recording material P discharged from the pair of rollers 41 and 42 to the outside of the unit 40.
4, 45, and the like, and outside the main body of the image forming apparatus, a paper output tray 48 for stacking the recording material P coming out of the unit 40 is provided.

The control unit 70, as shown in FIG.
CPU 801 for controlling the operation of the mechanism in each unit
And a motor driver 802. The control unit 70 will be described later.

Next, an image forming operation of the present image forming apparatus will be described. When an image forming operation start signal is issued from the CPU 801 of the control unit 70, first, the cassette 21a or 2 is driven by the pickup roller 22a or 22b.
The recording material P is fed out one by one from 1b, guided between the paper feeding guides 24 by the paper feeding roller pair 23, and conveyed to the registration rollers 25 (25a, 25b). At that time, the registration roller 25 has been stopped,
The leading end of the recording material P strikes the nip portion of the registration roller 25, and thereafter, the registration roller 25 starts rotating at a predetermined timing with respect to the start of image formation in the image forming unit.
The timing of the rotation of the registration roller 25 is such that toner images of each color are formed on each photosensitive drum 11, and the toner images of each color are primary-transferred onto the intermediate transfer belt 31 in a superimposed manner. When the toner image reaches the secondary transfer area Te, the recording material P sent to the registration roller 25 is set to reach the secondary transfer area Te.

In the image forming section, when an image forming operation start signal is issued, a toner image is formed on the photosensitive drum 11d of the station d which is the most upstream in the rotation direction of the intermediate transfer belt 31 by the above-described image forming process. The toner image is transferred to the intermediate transfer belt 31 in the primary transfer area Td.
The primary transfer is performed by the operation of the primary transfer charger 35 to which the high voltage is applied. The primary-transferred toner image is transported to the primary transfer area Tc of the next station c as the transfer belt 31 moves. At the station c, the image formation is performed with a delay of the time during which the toner image is transported between the stations d and c, and the next toner image is transferred with the position (registration) on the previous toner image. .
Hereinafter, the same process is repeated in the stations b and a, so that the toner images of four colors are eventually transferred onto the intermediate transfer belt 31 in a superimposed manner.

Thereafter, when the recording material P enters the secondary transfer area Te and comes into contact with the intermediate transfer belt 31, a high voltage is applied to the secondary transfer roller 36 in synchronization with the passage of the recording material P. Then, the four-color toner images formed on the intermediate transfer belt 31 by the above-described process are collectively secondarily transferred onto the surface of the recording material P. The recording material P on which the toner image has been secondarily transferred is accurately guided to the roller nip portion of the fixing unit 40 by the conveyance guide 43, and the toner image is formed on the surface of the recording material P by heat and pressure by the fixing roller 41 and the pressure roller 42. To form a full-color four-color permanent image. Thereafter, the recording material P is conveyed out of the apparatus by the inner and outer discharge rollers 44 and 45,
8 is loaded.

The image forming apparatus includes photo sensors 60 and 61 as pattern detecting means and a control unit 70 shown in FIG.
And a resist correction device including: The photosensors 60 and 61 are disposed at positions downstream of the image forming station a for the final color, and are disposed close to and above belts at both ends in the width direction perpendicular to the moving direction of the intermediate transfer belt 31. Each color resist pattern (registration correction pattern) formed along the belt moving direction at two locations at both ends in the width direction of the intermediate transfer belt 31.
Is detected and read, and registration correction control is performed by the correction means of the control unit 70.

The photo sensors 60 and 61 are, as in the prior art,
As shown in FIG. 7, the output of detecting the pattern on the intermediate transfer belt 31 is composed of the LED 201 of the light emitting element and the phototransistor 202 of the light receiving element, and the output of FIG. The light receiving circuit 807 similar to the light receiving circuit receives signal processing to detect a pattern. The resist pattern is similarly formed on the intermediate transfer belt 31.
Is formed as an example, the first line segment and the second line segment symmetrically arranged at a predetermined angle with respect to an imaginary line perpendicular to the moving direction.

The control unit 70 includes a CPU 801 for controlling the image output unit, and an R for storing a control program and data.
OM 806 and RAM 803, motor driver section 802 for driving various motors, light receiving circuit 807 that receives outputs from photo sensors 60 and 61 and outputs a pattern output, detects pattern width and position by receiving pattern output from light receiving circuit A pattern width detection unit 804 and a pattern width & position storage unit 805. The pattern width & position storage unit 805 stores A, B,.
· It is composed of a plurality of registers such as K.

The registration correcting operation is started by an instruction from the CPU 801 of the control unit 70, and the photo sensors 60 and 6
When 1 receives and detects the reflected light from the resist pattern, the output current is converted and amplified, and the obtained output voltage is input to the pattern width detection unit 804. The CPU 801 controls the pattern width detection unit 804 for a predetermined width T.
The width detection unit 804 cuts an output having a width equal to or less than a predetermined width T as a noise component, and only uses the other outputs having a width equal to or more than the predetermined width T to use a pattern used for resist correction. The pattern width and pattern position are output as data, and stored in the pattern width & position storage unit (registers A to K) 805.

FIG. 4 shows a state where the resist pattern is detected and read by the photosensors 60 and 61, and a resist pattern output is output from the light receiving circuit 807. On the intermediate transfer belt 31, image forming stations d, c,
Patterns 501, 502, 503, and 504 of yellow, magenta, cyan, and black are formed in this order by b and a.

Based on a resist pattern output obtained by detecting and reading the yellow pattern 501 with the photo sensor 60 and the light receiving circuit 807, the pattern width detecting section 8
At step 04, the position data and width data of the pattern 501 are detected and stored in the registers D and E of the storage unit 805. Similarly, based on the resist pattern output by the patterns 502 to 504, the pattern 502 is passed through the pattern width detection unit 804.
The position data and width data of .about.504 are stored in F.about.K.

Based on the position data D to K, the registration deviation on the photosensitive drum of each color is calculated, the image signal is electrically corrected, and the image formation start position on the photosensitive drum is temporally changed. Or by driving a folding mirror provided in the laser beam optical path to correct the optical path length or optical path, thereby mechanically changing the image forming start position with respect to the photosensitive drum, or the image forming start position by both of them. Is changed, and registration correction is performed.

The registration correction operation in the present invention will be described with reference to the flowchart of FIG. CPU 801
Performs a registration correction operation at a timing such as when the power of the image forming apparatus is turned on or a predetermined time after the power is turned on.

When the registration correcting operation starts, the intermediate transfer belt 31 is driven to rotate (step S701), and the LED 201 of the photo sensor is turned on (step S70).
2). Next, a resist pattern is written, and a pattern detection operation is started (step S703), and the position and width of the resist pattern output are sequentially stored in registers D to K (step S704). Also, the smallest value (MIN value) of the pattern width values stored in the registers D to K is stored in the register A (step S7).
05). Next, the above-described registration correction operation is performed using the position data stored in the registers D to K (step S7).
06) After that, the LED 201 is turned off, the rotation of the intermediate transfer belt 31 is stopped, and the registration correction operation ends (step S707).

A feature of the present invention is that the image forming apparatus has a flaw detection mode for detecting flaws and dirt on the intermediate transfer belt 31 in addition to the correction mode for performing the above-described registration correction. In other words, erroneous detection of the resist pattern due to scratches and dirt is prevented by performing flaw detection. Hereinafter, description will be given according to the flowchart of FIG.

First, the CPU 80 in the control unit 70
Prior to performing the registration detecting operation, the numeral 1 performs a state detecting operation for detecting a flaw or dirt on the intermediate transfer belt 31, that is, a state of detecting the state of the surface of the intermediate transfer belt. The rotational drive of the intermediate transfer belt 31 is started (step S601), and the LED is turned on.
201 is turned on (step S602), and the flaw detection operation is started (step S603). If the surface of the intermediate transfer belt 31 has scratches or dirt, the reflectance of the light emitted from the photosensors 60 and 61 decreases, and the detection output of the photosensor shows the same output as that of the pattern. The length of the area where the detection output falls below a predetermined value is detected, that is, the width of the flaw (including dirt) is detected and latched in the register B (step S605). The initial value 0 is stored in the register C in advance, and this register C
And the value of the register B are discriminated. If B is larger, this is a result of detection of a scratch or dirt.
The value of B is overwritten on C (steps S606 and S60).
7). Otherwise, the value remains as it is in C, and the process proceeds to step S608.

Returning to step S604, this flaw detection is repeated until the transfer belt makes one revolution, and the width of the flaw stored in the register C is updated to the detected large value (step S608). LED20
1 is turned off, and the rotation of the intermediate transfer belt 31 is stopped (step S609).

By performing the above-described flaw detection operation, the presence or absence of flaws and dirt on the intermediate transfer belt can be detected.

In the present invention, when a flaw or dirt is detected by the flaw detection, the register C storing the maximum width of the flaw or dirt is used.
Is compared with a predetermined value T set in the pattern width detection unit 804, and if C ≧ T, the predetermined width T is replaced with C and T
To update. Therefore, the pattern width detection during the registration correction operation described with reference to FIG.
Has been implemented. Thus, even if there is a flaw or dirt on the intermediate transfer belt 31, it can be cut as noise and the resist pattern can be detected without erroneously detecting the flaw or dirt by the photo sensor.

Further, if the size of the flaw or dirt is considerably large, the maximum width exceeds the minimum width of the pattern, and the pattern may be erroneously detected as a flaw or dirt. Therefore, the minimum pattern width is stored in the previous registration correction. The value of the register A is compared with the current value of the register C. If C ≧ A, the pattern is formed to be thicker than C by a predetermined width. Writing of a resist pattern during the resist correction operation described with reference to FIG. 5 is performed so as to form a pattern thickened by the predetermined width when C ≧ A.
Thus, even if there is a flaw or dirt on the intermediate transfer belt 31 exceeding the pattern width, a pattern having a width exceeding the width can be formed, and the resist pattern can be detected without erroneously detecting the flaw or dirt. it can.

In the above embodiment, the flaw detection of the intermediate transfer belt is also performed by using the detection means provided for detecting the pattern on the intermediate transfer belt. However, the detection means for flaw detection is separately provided. May be used to perform flaw detection.

In the embodiment, the registration correction in the image forming apparatus using the intermediate transfer belt has been described.
As will be understood, the present invention can also be applied to an image forming apparatus using a recording material transport belt which is a belt-shaped recording material carrier, and performs registration correction by detecting a resist pattern formed on the transport belt. The same effect can be obtained by doing the same.

[0050]

As described above, in the image forming apparatus according to the present invention, before the registration correcting operation, a flaw detecting operation for detecting a flaw or dirt on the intermediate transfer belt or the recording material conveying belt is performed. And the width of dirt is detected, and based on the detection result, the predetermined width T of the reference value set in the pattern width detecting means is updated. Detection can be performed, and accurate registration correction can be realized. Further, even when the width of a flaw or dirt is considerably large, by making the width larger than the maximum width and forming the registration correction pattern, it is possible to reliably prevent erroneous detection and detect the pattern. Further, since the sensor for detecting the registration pattern is also used for flaw detection, registration correction can be performed with a simple configuration without erroneous detection.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an image forming apparatus embodying the present invention.

FIG. 2 is a block diagram illustrating a control unit used for registration correction in the image forming apparatus of FIG. 1;

FIG. 3 is an explanatory diagram showing contents of data stored in a register partitioned into a pattern width and position storage unit of the control unit in FIG. 2;

FIG. 4 is an explanatory diagram showing a resist pattern and its detection output at the time of resist correction in the present invention.

FIG. 5 is a flowchart showing a registration correction operation according to the present invention.

FIG. 6 is a flowchart illustrating a flaw detection operation performed prior to a registration correction operation in the present invention.

FIG. 7 is an explanatory diagram showing detection of a resist pattern on a belt by a photo sensor.

FIG. 8 is an explanatory diagram showing a change in a light receiving output of the photo sensor.

FIG. 9 is a diagram illustrating a light receiving circuit that converts a light receiving output of a photo sensor into a pulse signal.

[Explanation of symbols]

 11a to 11d Photosensitive drum 31 Intermediate transfer belt 60, 61 Photosensor 70 Control unit 801 CPU 804 Pattern width detection unit 805 Pattern width & position storage unit 807 Light receiving circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/14 H04N 1/29 G H04N 1/29 G03G 21/00 372 F-term (Reference) 2H027 DA21 DA38 DA50 EB04 EC03 EC06 EC20 ED06 ED24 EE02 EE07 EF09 2H030 AA01 AB02 AD17 BB16 BB42 BB56 2H032 AA05 BA09 CA01 5C074 AA07 AA10 AA15 BB02 BB03 BB04 BB26 CC26 DD15 DD24 EE11 EE20 FF15 GG09

Claims (10)

[Claims] An image transfer member on which an image is formed; an intermediate transfer member; first detection means for detecting a detection image transferred from the image support member to the intermediate transfer member; A correction unit that corrects an image forming condition based on a detection result of the detection unit, wherein a second surface detecting unit detects a surface state of an area of the intermediate transfer body on which the detection image is not formed. Detecting means, and control means for controlling conditions for forming the image for detection formed on the image carrier based on a detection result by the second detecting means,
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein a plurality of the image carriers are provided, and the image for detection is transferred from each of the image carriers to the intermediate transfer member. 3. The image processing apparatus according to claim 2, wherein the correction unit corrects the position of an image formed on each of the image carriers temporally or mechanically based on a detection result detected by the first detection unit. The image forming apparatus according to claim 2. 4. In the moving direction of the intermediate transfer body, the control means controls the length of the image for detection based on the length of an area where the output of the second detection means is equal to or less than a predetermined value. The image forming apparatus according to claim 3, wherein: 5. The image forming apparatus according to claim 4, wherein a length of the image for detection is longer than a length of a region where a detection output by the second detection unit is equal to or less than a predetermined value. 6. An image carrier on which an image is formed, a recording material carrier for carrying a recording material, and a first detecting means for detecting a detection image transferred from the image carrier to the recording material carrier. An image forming apparatus for correcting an image forming condition based on a detection result by the first detecting means, wherein a surface of the recording material carrier on which the image for detection is not formed Second detecting means for detecting a state;
An image forming apparatus comprising: a control unit configured to control a forming condition of the image for detection formed on the image carrier based on a detection result by the detecting unit. 7. The image forming apparatus according to claim 1, wherein a plurality of the image carriers are provided, and the detection images are transferred from the respective image carriers to the recording material carrier. 8. The method according to claim 1, wherein the correction unit corrects the position of an image formed on each of the image carriers temporally or mechanically based on a detection result detected by the first detection unit. The image forming apparatus according to claim 7. 9. In the moving direction of the recording material carrier,
9. The image forming apparatus according to claim 8, wherein the control unit controls the length of the image for detection based on a length of an area where a detection output by the second detection unit is equal to or less than a predetermined value. 10. The image forming apparatus according to claim 9, wherein a length of the image for detection is longer than a length of an area where a detection output by the second detection unit is equal to or less than a predetermined value.