JP2010002526A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress toner consumption without wastes, when detecting and correcting misalignment or color shifting in an image. <P>SOLUTION: The image forming apparatus is provided with: photoreceptors for respective colors on which electrostatic latent images for respective colors are formed; an exposure section for respective colors for carrying out respective exposures on photoreceptors for respective colors; a developing section for respective colors for respectively developing the electrostatic latent images and making toner images for respective colors; an intermediate transfer body on which toner images for respective colors are transferred; a transfer section for respective colors for respectively transferring toner images to the intermediate transfer body; a sensor for detecting misalignment detection patternss formed on the intermediate transfer body; and a control section for carrying out control for shifting correction, by generating shifting detection patterns for the respective colors and detecting color shifting from read results by the sensor for shifting detection patterns. In this case, a normal number of shifting detection patterns are generated, when the color shifting amount detected in the execution of a previous color shifting correction is a prescribed value or larger, when the color shifting correction is executed; and when the color shifting amount which is detected, when the previous color shifting correction is executed is smaller than the prescribed value, numbers fewer than the normal number of shifting detection patterns are generated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus used for a copying machine, a printer, and the like, and more particularly, to a technique capable of appropriately controlling toner consumption when correcting image misregistration.

  An image forming apparatus that forms an image of one line in the main scanning direction according to image data, and forms an image for one page by repeating image formation for each line in the main scanning direction in the sub-scanning direction. Are known.

  As an example, in an electrophotographic image forming apparatus, exposure in the main scanning direction is performed on an image carrier (photosensitive drum or photosensitive belt) by an exposure unit in which a plurality of light emitting elements are arranged in the main scanning direction. Alternatively, the laser beam is scanned in the main scanning direction with a rotating mirror, and the image carrier is moved (rotated) in the sub-scanning direction orthogonal to the main scanning direction in parallel with the two-dimensional movement. The electrostatic image is formed. Thereafter, the toner image is formed and output on the recording medium through processes of development, transfer, and fixing.

  By the way, in the case of a general image forming apparatus, a predetermined pattern (deviation detection pattern (color resist pattern)) is formed and read to detect image positional deviation or color deviation, and the amount of deviation is calculated from the read result. Then, control for correcting the positional deviation and the color deviation is performed.

For example, it is also described in Patent Document 1 below.
JP 2007-156356 A

  By the way, in order to detect and correct such image misregistration and color misregistration as described above, a large number of misregistration detection patterns are formed and read at predetermined intervals. For this reason, the toner consumption for the shift detection pattern becomes a problem.

  In order to deal with such a problem, Japanese Patent Application Laid-Open No. H10-228867 attempts to reduce toner consumption by controlling the length and the number of readings according to the toner density. In this case, although it contributes to a slight reduction in toner consumption, the current situation is that no fundamental improvement has been made.

  The present invention has been made in order to solve the above-described problems, and can suppress consumption of toner for forming a misregistration detection pattern without waste when detecting and correcting image misregistration or color misregistration. An object is to realize a possible image forming apparatus.

  That is, the image forming apparatus of the present invention as a means for solving the problem is a photoconductor for each color on which an electrostatic latent image for each color is formed by exposure, and each color for performing exposure on each photoconductor for each color. An exposure unit, a developing unit for each color that develops an electrostatic latent image on each color photoconductor to form a toner image for each color, and an intermediate transfer member to which each toner image on the photoconductor for each color is transferred A transfer portion of each color for transferring the toner image on the photosensitive member of each color to the intermediate transfer member, a sensor for detecting a shift detection pattern formed on the intermediate transfer member, and the shift detection pattern for each color. And a control unit that detects color misregistration from the reading result of the sensor of each color misregistration detection pattern and controls misregistration correction. When deviation correction is performed If the amount of color misregistration detected in the previous step is equal to or greater than a predetermined value, a normal number of the misregistration detection patterns are generated, and if the amount of color misregistration detected at the previous execution of color misregistration correction is less than the predetermined value, the normal amount is detected. A small number of the shift detection patterns are generated.

According to the present invention, the following effects can be obtained.
(1) In the invention of the image forming apparatus, when the color misregistration correction is performed, if the amount of color misregistration detected at the previous color misregistration correction is equal to or greater than a predetermined value, a normal number of misregistration detection patterns are generated. If the amount of color misregistration detected at the time of color misregistration correction is less than a predetermined value, a smaller number of misregistration detection patterns are generated, and color misregistration is detected from the reading results of each color misregistration detection pattern by the sensor. Perform correction control.

  That is, if the previous color misregistration is smaller than a predetermined value, it is unlikely that the current color misregistration is extremely large. Therefore, misregistration correction is controlled with a smaller number of misregistration detection patterns than usual.

As a result, it is possible to suppress consumption of toner for forming a misregistration detection pattern without waste when detecting and correcting image misregistration or color misregistration.
(2) In (1), the number of shift detection patterns smaller than the normal number is generated so as to include the positions of 0 ° and 180 ° of the rotational phase of the photoconductor. This makes it possible to control deviation correction while suppressing toner consumption in a state where it is difficult to be affected by the peripheral speed fluctuation of one drum cycle.

(3) In the above (1), when the color misregistration correction is performed when the power is turned on, after the detachable component is detached, or when the impact is detected, the color misregistration amount detected last time Regardless of the number, a normal number of deviation detection patterns are generated.
As a result, when there is an operation that may cause a large change between the previous correction and the current correction, appropriate deviation correction control can be executed.

  (4) In the above (1) to (3), when the color misregistration correction is executed, the number of misregistration detection patterns in which the color misregistration amount detected when the previous color misregistration correction is executed is less than a predetermined value and less than normal. If generated, if the amount of color misregistration obtained from the reading result by the sensor of the color misregistration detection pattern for each color is equal to or greater than a predetermined value, the misregistration correction based on the obtained color misregistration amount is not executed, and a normal number of misregistrations are performed. A detection pattern is generated, and a color shift is detected from a reading result by the sensor of the normal number of shift detection patterns for each color to control shift correction.

  If the previous color misregistration is smaller than the predetermined value, it is unlikely that the current color misregistration is extremely large, so the misregistration correction is controlled by a smaller number of misregistration detection patterns than usual, but the previous color misregistration is the predetermined value. If the current color misregistration is large for some reason, although smaller, the normal number of misregistration detection patterns are generated again, and the color misregistration from the result of reading by the sensor of the normal number of misregistration detection patterns for each color is detected. Is detected and deviation correction is controlled.

  As a result, when detecting and correcting image misalignment and color misalignment, if the misalignment is small, the toner consumption is suppressed without waste, and if the misalignment is not small, the necessary toner is consumed and correction is executed. It becomes possible to do.

  (5) According to the image forming apparatus of the present invention, when the misregistration correction is executed, if the misregistration amount detected at the previous misregistration correction execution is a predetermined value or more, a normal number of misregistration detection patterns are generated. If the amount of misregistration detected at the time of misregistration correction is less than a predetermined value, a smaller number of misregistration detection patterns are generated than normal, and the misregistration is detected by detecting misregistration from the result of reading the misregistration detection pattern of each color. Perform correction control.

  That is, if the previous positional deviation is smaller than a predetermined value, it is unlikely that the current positional deviation is extremely large. Therefore, deviation correction control is performed with a smaller number of deviation detection patterns than usual.

As a result, the toner consumption for forming the misalignment detection pattern can be suppressed without waste when detecting and correcting the misalignment or misalignment of the image.
(6) In the above (1), the number of deviation detection patterns smaller than the normal number is generated so as to include the positions of 0 ° and 180 ° of the rotational phase of the photoconductor. This makes it possible to control deviation correction while suppressing toner consumption in a state where it is difficult to be affected by the peripheral speed fluctuation of one drum cycle.

(7) In (1) above, if the misalignment correction is executed when the power is turned on, after the detachable component is removed, or when the impact is detected, the previously detected misalignment amount Regardless of the number, a normal number of deviation detection patterns are generated.
As a result, when there is an operation that may cause a large change between the previous correction and the current correction, appropriate deviation correction control can be executed.

  (8) In the above (5) to (7), when the positional deviation correction is executed, the number of positional deviation detection patterns whose positional deviation amount detected at the previous execution of the positional deviation correction is less than a predetermined value is smaller than normal. If generated, if the amount of misalignment obtained from the result of reading the misregistration detection pattern of each color by the sensor is equal to or greater than a predetermined value, misalignment correction based on the obtained misregistration amount is not performed, and a normal number of misalignments A detection pattern is generated, and a positional deviation is detected from the result of reading by the sensor of the normal number of deviation detection patterns for each color, and deviation correction is controlled.

  If the previous positional deviation is smaller than the predetermined value, it is unlikely that the current positional deviation will be extremely large, so deviation correction control is performed with a smaller number of deviation detection patterns than usual, but the previous positional deviation is the predetermined value. If the current misregistration is larger for some reason although it was smaller, the normal number of misregistration detection patterns are generated again, and the misregistration detection pattern of the normal number of each color is misaligned from the result of reading by the sensor. Is detected and deviation correction is controlled.

  As a result, when detecting and correcting image misalignment or misalignment, if the misalignment is small, the toner consumption is suppressed without waste, and if the misalignment is not small, the necessary toner is consumed and correction is executed. It becomes possible to do.

The best mode (embodiment) for carrying out the present invention will be described below in detail with reference to the drawings.
[First embodiment]
Here, the configuration of the first embodiment of the image forming apparatus 100 of the present embodiment will be described in detail with reference to FIGS. Here, a color image forming apparatus that forms a color image by combining toner images of a plurality of colors will be described as a specific example.

  A control unit 101 is configured by a CPU or the like to control each unit of the image forming apparatus 100. The control unit 101 generates a misregistration detection pattern for each color, detects color misregistration from a reading result of the misregistration detection pattern of each color, and controls misregistration correction. If the amount of color misregistration detected at the time of executing color misregistration correction is equal to or greater than a predetermined value, a normal number of misregistration detection patterns are generated, and the amount of color misregistration detected at the time of previous color misregistration correction execution is less than the predetermined value. If there is, control is performed to generate a smaller number of deviation detection patterns than usual.

  Reference numeral 103 denotes an image carrier such as a photosensitive drum on which an electrostatic latent image is formed by exposure and a toner image is formed by development. For each color of YMCK, an image carrier 103Y, an image carrier 103M, an image carrier 103C, and an image carrier 103K are provided.

  Reference numeral 104 denotes an intermediate transfer member such as an endless transfer belt onto which the toner image on the image carrier 103 is transferred. The toner image of each color is combined with the intermediate transfer member 104 to form a color image.

  A storage unit 105 holds various data. The storage unit 105 stores data for generating a predetermined deviation detection pattern. Further, the deviation amount detected at the time of the previous correction is also held.

Reference numeral 107 denotes a registration sensor that detects a color shift of each color toner image, and reads a predetermined shift detection pattern of each color on the intermediate transfer member 104.
Reference numeral 108 denotes an impact sensor that detects external vibrations and impacts in the image forming apparatus. As this impact sensor 108, a general vibration sensor may be used. Although not shown, a temperature sensor, a humidity sensor, or the like may be provided.

  An image processing unit 110 executes predetermined image processing according to image data and generates image data for image formation. A recording head driving unit 120 drives the recording head to perform exposure in accordance with image data or predetermined command data.

  A recording head 150 is an exposure unit that performs exposure in the main scanning direction corresponding to a plurality of pixels on the image carrier 103. The recording head 150 may be a line-shaped print head in which a plurality of LED elements are arranged with the main scanning direction as the longitudinal direction, or an exposure unit that scans a laser beam in the main scanning direction with a rotary mirror. May be.

  Reference numeral 160 denotes a developing unit that develops an electrostatic latent image formed by exposure on the image carrier 103 and attaches toner to form a toner image. A Y developing unit 106Y, an M developing unit 106M, a C developing unit 106C, and a K developing unit 106K are provided for each color of YMCK.

  Reference numeral 170 denotes a transfer unit for transferring a toner image, which transfers the toner image from the image carrier 103 (image carrier 103Y, image carrier 103M, image carrier 103C, image carrier 103K) to the intermediate transfer member 104. A toner image is transferred from the primary transfer unit 171 (Y primary transfer unit 171Y, M primary transfer unit 171M, C primary transfer unit 171C, K primary transfer unit 171K) to the recording medium (recording paper) P from the intermediate transfer member 104. A secondary transfer unit 172 is provided. A fixing unit 180 stabilizes the toner image on the recording medium P with heat and pressure.

In FIG. 1 and FIG. 2, description of general portions that are known and are not directly related to the characteristic control of the present embodiment is omitted.
The electrophotographic image forming apparatus 100 shown here performs charging, exposure, and latent image formation and development for each color to form toner images of each color on the image carrier 103 of each color. Then, primary transfer is executed from the image carrier 103 of each color, and a toner image is formed on the intermediate transfer member 104 in the aligned state. Thereafter, the toner image is transferred onto the recording medium P by secondary transfer by the secondary transfer unit 172, and the toner image is formed and output on the recording medium P through a process of fixing by the fixing unit 180. ing.

The operation of this embodiment will be described below with reference to the explanatory diagram of FIG. 3 and the flowcharts of FIG.
The control unit 101 executes color misregistration correction of the image forming apparatus 100 according to the color misregistration correction routine of FIG.

  First, it is confirmed whether it corresponds to a correction timing (step S401 in FIG. 4). Here, the correction timing refers to the initial operation timing at which the image forming apparatus 100 is installed, the operation timing for a predetermined period of time, the timing immediately after the power is turned on every morning, the main components are replaced (the detachable components are removed) ), The timing at which it is detected that the internal environment (temperature and humidity) has changed over a certain level, and the like.

If it does not correspond to the correction timing (NO in step S401 in FIG. 4), normal correction described later is executed (step S407 in FIG. 4).
On the other hand, if it corresponds to the correction timing (YES in step S401 in FIG. 4), is the correction timing immediately after the power is turned on (step S402 in FIG. 4) or after the detachable unit is detached (in FIG. 4)? Step S403), or after the impact detection by the impact sensor 108 (Step S404 in FIG. 4), the control unit 101 confirms.

  Here, even if the correction timing is applicable (YES in step S401 in FIG. 4), the detachable unit is attached / detached immediately after the power is turned on (YES in step S402 in FIG. 4). After (YES in step S403 in FIG. 4) and after impact detection by the impact sensor 108 (YES in step S404 in FIG. 4), work that may cause a large variation is included. Therefore, the normal correction described later is executed (step S407 in FIG. 4).

  Further, here, the correction timing is applicable (YES in step S401 in FIG. 4), and the correction timing is not immediately after the power is turned on (NO in step S402 in FIG. 4). If the unit is not attached or detached (NO in step S403 in FIG. 4), but not after the impact is detected by the impact sensor 108 (NO in step S404 in FIG. 4), there is a large fluctuation between the previous correction and the current correction. Therefore, the shift amount tendency, that is, the color shift amount detected at the time of the previous color shift correction execution is obtained (step S405 in FIG. 4).

Here, the acquisition of the deviation amount tendency will be described with reference to the flowchart of FIG.
First, the control unit 101 reads out and acquires the amount of deviation at the previous correction from the storage unit 105 (step S501 in FIG. 5). Then, the deviation amount at the previous correction is compared with a predetermined value (step S502 in FIG. 5).

Here, the predetermined value may be set to a value corresponding to a deviation amount at a level at which the image forming apparatus operates stably and the operation can be continued without any deviation correction.
If the amount of deviation detected during the previous correction is smaller than this predetermined value (YES in step S502 in FIG. 5, FIG. 7A), it is determined that “deviation amount tendency = small” (step S503 in FIG. 5).

If the amount of deviation detected during the previous correction is equal to or greater than this predetermined value (NO in step S502 in FIG. 5, FIG. 7B), it is determined that “deviation amount tendency = large” (step S504 in FIG. 5). .
Then, the control unit 101 refers to the obtained deviation amount tendency (step S406 in FIG. 4). If the deviation amount tendency is large, that is, if the deviation amount at the previous correction is equal to or greater than a predetermined value, A normal number of deviation detection patterns that are not thinned out are generated on the intermediate transfer member 104 (see FIG. 3), and the deviation detection pattern is read by the registration sensor 107 to detect the current deviation amount, and necessary corrections are made. The amount is calculated (step S407 in FIG. 4).

  At this time, when the control unit 101 generates a normal number of shift detection patterns that are not thinned out, the control unit 101 forms the shift detection pattern data, the shift detection pattern data, and the shift detection pattern from the storage unit 105. The data of the phase angle of the photosensitive drum to be read is read out, the first pattern is formed with a drum phase angle of 0 ° (step S601 in FIG. 6), and the drum phase angle of the next individual pattern is set to a predetermined phase. The operation of forming with accuracy (steps S602 and S603 in FIG. 6) is repeated until a predetermined number is reached (step S604 in FIG. 6). For example, as the normal number of deviation detection patterns, a total of 12 or 13 patterns are formed at a phase angle of 0 ° to 360 ° of the photosensitive drum every phase angle of 30 ° of the photosensitive drum.

  Here, as the misalignment detection pattern, a pattern corresponding to a Katakana “F”, which is a combination of a line parallel to the main scanning direction and a line obliquely connected to the line parallel to the main scanning direction, is used. (See FIGS. 3 and 7). Further, here, as the normal number of shift detection patterns, shift detection patterns for one rotation of the photoconductor are generated so as to include the positions of 0 ° to 360 ° of the rotational phase of the photoconductor. As a result, even if there is a peripheral speed fluctuation of one drum cycle, it is possible to cope with the plurality of deviation detection patterns (FIGS. 9A and 9B).

  Here, the nth pattern of one color is compared with the nth pattern of another color, and the amount of color shift in the sub-scanning direction is controlled from the distance (detection timing) between the straight lines in the main scanning direction. Unit 101 calculates. Further, as will be described later, a deviation in the main scanning direction can also be obtained.

  In the case of pattern generation as shown in FIG. 3, when the amount of misregistration of other colors is obtained based on one color, such as black K and yellow Y, black K and magenta M, black K and cyan C, Deviation calculation and deviation correction are efficient and accuracy is improved. At this time, in the case of n patterns (here, 12 patterns) for each color, the first pattern of K and Y, the second pattern of K and Y,... As in the nth pattern, each pattern is compared.

  Further, as detection of deviation in the main scanning direction, as shown in FIGS. 3 and 10, a pattern capable of detecting a dimensional change in the main scanning direction is formed on both ends in the main scanning direction. Then, this pattern may be read by the registration sensor 107 at a fixed distance r, and the change (shift) in the main scanning direction may be calculated from the read result.

  Here, it is assumed that the main scanning direction exposure result before the dimensional change is shown in FIG. Assume that the predetermined pattern formed at this time is shown in FIG. At this time, a pattern such as Katakana “F” or an inequality symbol “>” is formed with the recording head 150 facing opposite sides at both ends in the main scanning direction.

  Here, it is assumed that the exposure result in the main scanning direction after the dimensional change is shown in FIG. Assume that the predetermined pattern formed at this time is shown in FIG. Then, such a pattern before and after the change is detected by the registration sensor 107 at a constant distance r as shown in FIG.

  In this case, when the recording start position (one end in the main scanning direction) is fixed and the other end side is affected by expansion and contraction, an enlarged view thereof is shown in FIG. In this case, the detection pattern Y1 changes due to the dimensional change ΔY in the main scanning direction, and this change in Y1 is detected as a change in Y2 by the registration sensor. In this case, the control unit 101 can calculate the dimensional change ΔY in the main scanning direction as ΔY = ΔY1 = ΔY2 / tan θ from the detection result of the registration sensor.

Then, the control unit 101 generates correction data for correcting the color misregistration amount calculated as described above, and executes correction for each unit (step S410 in FIG. 4).
On the other hand, the control unit 101 refers to the obtained deviation amount tendency (step S406 in FIG. 4). If the deviation amount tendency is small, that is, if the deviation amount at the previous correction is less than a predetermined value, A smaller number of deviation detection patterns than usual in the thinned state is generated on the intermediate transfer member 104 (see FIG. 8 corresponding to FIG. 3), and this deviation detection pattern is read by the registration sensor 107 to determine the current deviation amount. It detects and calculates a required correction amount (step S408 in FIG. 4).

  At this time, when the control unit 101 generates a smaller number of shift detection patterns than usual in the thinned state, the control unit 101 receives the shift detection pattern data, the shift detection pattern generation number data, and the shift detection pattern from the storage unit 105. The data of the phase angle of the photosensitive drum to be formed is read out, the first pattern is formed with a drum phase angle of 0 ° (step S601 in FIG. 6), and the drum pattern angle of the next individual pattern is set to a predetermined drum phase angle. The operation (steps S602 and S603 in FIG. 6) formed with the accuracy of (5) is repeated until the predetermined number is reached (step S604 in FIG. 6). For example, as a small number of shift detection patterns thinned out, a total of three patterns are formed at phase angles of 0 °, 180 °, and 360 ° of the photosensitive drum for every phase angle of the photosensitive drum of 180 °.

  Here, as the misalignment detection pattern, a pattern corresponding to a Katakana “F”, which is a combination of a line parallel to the main scanning direction and a line obliquely connected to the line parallel to the main scanning direction, is used. (See FIGS. 3 and 7). In addition, here, as a normal number of deviation detection patterns, one round of the photoconductor is included so as to include positions of multiples of 0 ° and 180 °, such as 0 °, 180 °, and 360 ° of the rotational phase of the photoconductor. Generate a minute shift detection pattern. As a result, even if there is a peripheral speed fluctuation in one drum cycle, the influence of the peripheral speed fluctuation can be minimized and handled by a plurality of deviation detection patterns (FIGS. 9C and 9D).

  Here, the nth pattern of one color is compared with the nth pattern of another color, and the amount of color shift in the sub-scanning direction is controlled from the distance (detection timing) between the straight lines in the main scanning direction. Unit 101 calculates. Further, as will be described later, a deviation in the main scanning direction can also be obtained.

  In the case of pattern generation as shown in FIG. 3, when the amount of misregistration of other colors is obtained based on one color, such as black K and yellow Y, black K and magenta M, black K and cyan C, Deviation calculation and deviation correction are efficient and accuracy is improved. At this time, in the case of n patterns (here, 12 patterns) for each color, the first pattern of K and Y, the second pattern of K and Y,... As in the nth pattern, each pattern is compared. Further, the detection of the deviation in the main scanning direction can be performed in the same manner as in FIGS.

  If the previous positional deviation is smaller than the predetermined value, it is unlikely that the current positional deviation is extremely large.Therefore, the deviation correction is controlled by a smaller number of deviation detection patterns than usual. Although it was smaller than the predetermined value, there may be a case where the current position shift is large for some reason. Therefore, the control unit 101 checks whether the current color misregistration amount is small (step S409 in FIG. 4). If the current color misregistration amount is not small (NO in step S409 in FIG. 4), the control unit 101 again A normal number of misregistration detection patterns are generated, and a misregistration control is performed by detecting a misregistration from the reading result of the normal number of misregistration detection patterns of each color by the sensor (steps S407 and 410 in FIG. 4).

  Then, the control unit 101 confirms whether the current color misregistration amount is small (step S409 in FIG. 4). If the current color misregistration amount is small (YES in step S409 in FIG. 4), the current thinning is performed. The control unit 101 generates correction data for correcting the color misregistration amount obtained by the small number of misregistration detection patterns, and executes correction for each unit (step S410 in FIG. 4).

  As a result, when detecting and correcting image misalignment and misalignment, if the misalignment tendency is small, toner consumption is suppressed without waste, and if the misalignment is not small, necessary toner is consumed and corrected. Can be executed.

  Even if the shift amount tendency is small, if the color shift amount calculated this time is not small, shift calculation and correction control are performed with a normal shift detection pattern, so the accuracy does not decrease. Also, if the current misalignment correction timing is one of immediately after the power is turned on, after the removable unit is removed, or after the impact is detected by the impact sensor 108, work that may cause a large fluctuation is entered Therefore, the normal correction described later is executed, and in this case, the accuracy is not lowered. In addition to the specific examples shown here, the normal correction may be performed in the same manner if there is a work that may cause a large variation in the accuracy of the image forming apparatus.

[Other Embodiments (1)]
In the above embodiment, the control unit 101 generates a normal number of misregistration detection patterns when the color misregistration correction is performed and the color misregistration amount detected at the previous color misregistration correction execution is equal to or greater than a predetermined value. If the amount of color misregistration detected at the time of color misregistration correction is less than a predetermined value, the number of misregistration detection patterns smaller than usual is generated.

On the other hand, two types of predetermined values serving as threshold values are prepared, and the control unit 101, when performing color misregistration correction, if the color misregistration amount detected at the previous color misregistration correction execution is equal to or greater than the first predetermined value. If a normal number (for example, 12) of misregistration detection patterns are generated and the amount of color misregistration detected at the time of the previous color misregistration correction execution is less than the first predetermined value and greater than or equal to the second predetermined value, it is normal. If a small number (4 or 5 for each photosensitive drum phase angle of 90 °) of misregistration detection patterns is generated and the color misregistration detected at the previous color misregistration correction is less than the second predetermined value, the smaller number (2 or 3 for each photosensitive drum phase angle 180 °) to generate a deviation detection pattern,
Three-stage switching control may be used.

  In this case, the predetermined value in the above-described embodiment may be set as the second predetermined value, and the first predetermined value that is stricter against color shift than that. Alternatively, in this case, the predetermined value in the above-described embodiment may be set as the first predetermined value, and the second predetermined value that is looser than the color shift may be used. Further, it is possible to set more predetermined values and finer control.

[Other embodiment (2)]
In the above description of the embodiment, the color misregistration in the color image forming apparatus has been described. On the other hand, in the monochrome image forming apparatus, misregistration correction may be executed as the misregistration detection and correction for one black color. In this case, it is only necessary to perform misregistration calculation and correction such as whether a predetermined position is obtained with one black color or a predetermined distance compared with another pattern, instead of comparison with other colors.

Further, even in a color image forming apparatus, the displacement for one black color may be executed in the monochrome mode.
Further, even in a color image forming apparatus, position shift calculation and correction may be executed for each color as the position shift of each color instead of comparison with other colors.

In any case, wasteful toner consumption can be suppressed while maintaining necessary accuracy.
[Other embodiment (3)]
In the above embodiment, the electrophotographic image forming apparatus has been described. However, the present embodiment is also applied to various image forming apparatuses and image recording apparatuses such as other systems (thermal transfer, heat sensitive, ink jet). As a result, consumption of recording materials such as toner and ink can be suppressed.

[Other embodiment (4)]
In view of the toner consumption suppressed in each of the above-described embodiments, it is possible to keep the accuracy of image formation in a good state by narrowing the gap detection interval from the conventional one.

1 is a configuration diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention. 1 is a configuration diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention. FIG. 3 is a configuration diagram illustrating a shift detection pattern of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an operation state of the image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Control part 103 Image carrier 104 Intermediate transfer body 105 Storage part 107 Registration sensor 108 Impact sensor 109 Humidity sensor 110 Image processing part 120 Recording head drive part 150 Recording head 160 Development part 170 Transfer part 180 Fixing part

Claims (8)

A photoreceptor for each color on which an electrostatic latent image for each color is formed by exposure; and
An exposure portion for each color that exposes each of the photoconductors for each color;
A developing section for each color, which develops the electrostatic latent image on the photoreceptor of each color into a toner image of each color;
An intermediate transfer member to which each toner image on the photosensitive member of each color is transferred;
A transfer portion for each color for transferring a toner image on the photoconductor for each color to the intermediate transfer body;
A sensor for detecting a shift detection pattern formed on the intermediate transfer member;
A control unit that generates the misregistration detection pattern for each color, detects color misregistration from a reading result of the misregistration detection pattern of each color, and controls misregistration;
When the color misregistration correction is executed, the control unit generates a normal number of the misregistration detection patterns if the color misregistration amount detected at the previous color misregistration correction execution is equal to or greater than a predetermined value, and executes the previous color misregistration correction. If the amount of color misregistration detected at the time is less than a predetermined value, a smaller number of the misregistration detection patterns is generated than usual.
An image forming apparatus. The control means generates the deviation detection patterns smaller than the normal number so as to include positions of 0 ° and 180 ° of the rotational phase of the photosensitive member.
The image forming apparatus according to claim 1. When the color misregistration correction is performed when the power is turned on, after the detachable component is removed, or when the impact is detected, regardless of the previously detected color misregistration amount, Generating a normal number of the deviation detection patterns,
The image forming apparatus according to claim 1. When the color misregistration correction is performed, when the color misregistration amount detected when the previous color misregistration correction is performed is less than a predetermined value and a smaller number of the misregistration detection patterns are generated, If the amount of color misregistration obtained from the reading result of each color misregistration detection pattern by the sensor is equal to or greater than the predetermined value, the misregistration correction based on the obtained color misregistration amount is not executed, and the normal number of the misregistration detection patterns is generated. Thus, the color misregistration is detected from the result of reading by the sensor of the normal number of misregistration detection patterns for each color, and misregistration correction is controlled.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A photoreceptor on which an electrostatic latent image is formed by exposure;
An exposure unit that exposes the photosensitive member;
A developing unit that develops the electrostatic latent image on the photoconductor into a toner image;
An intermediate transfer member to which a toner image on the photosensitive member is transferred;
A transfer portion for transferring the toner image on the photosensitive member to the intermediate transfer member;
A sensor for detecting a shift detection pattern formed on the intermediate transfer member;
A control unit that generates the deviation detection pattern, detects a positional deviation from a reading result of the sensor of the deviation detection pattern, and controls deviation correction;
When the positional deviation correction is executed, the control unit generates a normal number of the deviation detection patterns and executes the previous positional deviation correction if the positional deviation amount detected at the previous positional deviation correction execution is equal to or greater than a predetermined value. If the amount of misalignment detected at the time is less than a predetermined value, a smaller number of misregistration detection patterns than usual is generated.
An image forming apparatus. The control means generates the deviation detection patterns smaller than the normal number so as to include positions of 0 ° and 180 ° of the rotational phase of the photosensitive member.
The image forming apparatus according to claim 5. The control unit, when the misalignment correction is performed, corresponds to any of the case of the impact detection when the power is turned on, after the detachable component is detached, regardless of the previously detected misalignment amount, Generating a normal number of the deviation detection patterns,
The image forming apparatus according to claim 5. When the positional deviation correction is performed, when the positional deviation amount detected at the previous positional deviation correction execution is less than a predetermined value and a smaller number of the deviation detection patterns are generated, If the positional deviation amount obtained from the reading result of the deviation detection pattern by the sensor is not less than the predetermined value, the deviation correction based on the obtained positional deviation amount is not executed, and the normal number of deviation detection patterns is generated, A positional deviation is detected from the result of reading by the sensor of the normal number of deviation detection patterns, and deviation correction is controlled.
The image forming apparatus according to claim 5, wherein the image forming apparatus is an image forming apparatus.