JP2013218282A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing the number of system downs caused by failure of a detection sensor that detects a detection pattern for color shift correction, and a control method of an image forming apparatus.SOLUTION: An image forming apparatus includes: a sheet conveying mechanism that supplies sheets; an image carrier that carries developer images; an image forming unit that forms images of detection patterns of respective colors on the image carrier; a plurality of detection sensors that read the detection patterns; and a control unit that corrects, when any one of the plurality of detection sensors normally reads the detection patterns of all colors, color shift that can be corrected on the basis of one detection sensor that normally operates.

Description

  Embodiments described herein relate generally to an image forming apparatus.

  Some image forming apparatuses such as printers and copiers perform color printing. In this model, an image is formed by an image forming unit for each color using a plurality of color developers, and one image is generated. Therefore, high-quality images cannot be formed unless the image forming positions of the respective colors are accurate.

  The image forming apparatus includes a color misregistration correction device that detects the image forming position of each color in order to match the image forming position of each color and corrects the image forming position when it is determined that a misregistration has occurred.

  The color misregistration correction apparatus includes a detection pattern forming unit that forms an image of a detection pattern on an image carrier that carries a developer image, and a detection sensor that detects the detection pattern.

  The detection pattern forming unit forms an image of the detection pattern of each color on the image carrier with a predetermined interval for each color. The detection sensors are installed at two locations on the front side and the rear side.

  The conventional image forming apparatus corrects color misregistration for all colors only when all the sensors can detect the detection pattern normally. If any of the sensors cannot detect the detection pattern, it is determined as an error. And was set to bring the system down.

  Therefore, the probability of system down increases, and the usability is bad for the user.

JP 2009-64016 A

  Accordingly, there is a need for an image forming apparatus and a method for controlling the image forming apparatus that can reduce the number of times of down due to a failure of a detection sensor that detects a detection pattern for color misregistration correction.

  In order to solve the above-described problems, an embodiment of the present invention forms a sheet transport mechanism for supplying a sheet, an image carrier that carries a developer image, and a detection pattern for each color on the image carrier. When any one of a plurality of detection sensors and a plurality of detection sensors normally read a detection pattern of all colors can be corrected based on one detection sensor that operates normally. An image forming apparatus including a control unit that corrects color misregistration is provided.

1 is a diagram illustrating a configuration of an image forming apparatus. 1 is a block diagram illustrating a configuration of an image forming apparatus. 3 is a diagram illustrating a positional relationship between a detection pattern formed on an image carrier and a detection sensor 31. FIG. It is a figure which shows the principle of the detection of main scanning magnification. It is a figure which shows the detection principle of a skew. It is a figure which shows the principle of detection of a subscanning position. It is a figure which shows the principle of detection of the main scanning position. 3 is a flowchart illustrating an operation of the image forming apparatus.

  Hereinafter, an embodiment of an image forming apparatus and a method for controlling the image forming apparatus will be described in detail with reference to the drawings.

  The image forming apparatus according to the present embodiment includes a sheet conveying mechanism that supplies a sheet, an image carrier that carries a developer image, an image forming unit that forms a detection pattern of each color on the image carrier, and a detection pattern. A plurality of detection sensors to be read, and a control unit that corrects a color shift that can be corrected based on one detection sensor that normally operates when any one of the plurality of detection sensors normally reads a detection pattern of all colors; .

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 includes an automatic document feeder 11, an image reading unit 12, an image forming unit 13, a paper feeding unit 16, a sheet conveying mechanism 18, and a control unit 19. Including.

  The automatic document feeder 11 is installed at the top of the main body of the image forming apparatus 1 so as to be openable and closable. The automatic document feeder 11 includes a document conveyance mechanism that takes out documents one by one from a paper feed tray and conveys them to a paper discharge tray.

  The automatic document feeder 11 conveys documents one by one to the document reading unit of the image reading unit 12 by the document conveying function. It is also possible to open the automatic document feeder 11 and place the document on the document table of the image reading unit 12.

  The image reading unit 12 includes an exposure lamp that exposes a document and a carriage including a first reflection mirror, a plurality of second reflection mirrors that move in accordance with the movement of the carriage, a lens block, and a CCD ( Charge Coupled Device).

  The carriage rests on the document reading unit or reciprocates under the document table to reflect the light of the exposure lamp reflected by the document to the first reflecting mirror. The plurality of second reflection mirrors reflects the reflected light of the first reflection mirror to the lens block. The lens block changes the magnification of the reflected light and outputs it to the CCD. The CCD converts incident light into an electrical signal and outputs it as an image signal to the image forming unit 13.

  The image forming unit 13 includes a registration roller 13A that corrects the orientation of the sheet so that the side in the width direction of the sheet conveyed obliquely is parallel to the sheet conveyance direction.

  The image forming apparatus 1 forms an image on the sheet whose orientation is corrected by the registration roller 13 </ b> A by the image forming unit 13.

  The image forming method of the image forming unit 13 does not matter. The image forming method of the image forming unit 13 can be selected from methods such as an electronic method and an ink jet method.

  In the case of an electronic system, the image forming unit 13 includes a laser irradiation unit 13D, a photosensitive drum 13B, a developer supply unit 13C, a transfer unit 14, and a yellow Y, a magenta M, a cyan C, and a black K. Is provided.

  The laser irradiation unit 13D irradiates the photosensitive drum 13B with laser light based on the image signal, and forms an electrostatic latent image on the photosensitive drum 13B. The developer supply unit 13C supplies the developer to the photosensitive drum 13B and forms a developer image from the electrostatic latent image.

  The paper feed unit 16 takes out the sheets one by one from the paper feed cassette and delivers them to the paper transport mechanism. The paper transport mechanism transports the sheet to the transfer unit 14.

  The transfer unit 14 includes a transfer belt 14B and a transfer roller 14A. The transfer belt 14B receives and carries the developer image on the photosensitive drum 13B. The transfer roller 14A applies a voltage to transfer the developer image on the transfer belt to the conveyed sheet.

  Here, the image carrier refers to a member that carries a developer image. In other words, in the case of a model having the transfer belt 14B, the transfer belt 14B does not have the transfer belt 14B, and in the model in which the developer image is directly transferred from the photosensitive drum 13B to the sheet, the photosensitive drum 13B has the image carrier. Is the body.

  The image forming apparatus 1 includes a fixing device 14 </ b> C downstream of the transfer unit 14 in the sheet conveyance direction. The fixing device 14C heats and pressurizes the developer image to fix it on the sheet.

  In the case of an ink jet type, the image forming unit 13 includes a head that sprays ink onto a sheet.

  The head has an ink supply chamber in which piezo elements of different polarities are attached in the longitudinal direction, and the set of the attached piezo elements are arranged in a comb tooth shape, an ink discharge hole, and covers the ink supply chamber A cover is provided. The image forming unit 13 deforms the ink supply chamber by alternately applying a voltage to the head, and repeats the suction of the ink and the discharge from the ink discharge hole. The ejected ink adheres to the sheet and image formation is performed.

  The image forming apparatus 1 includes a paper feed cassette opening / closing sensor 51 that is installed in the paper feed cassette and detects opening / closing of the paper feed cassette, and a size sensor 52 that detects the size of sheets accumulated in the paper feed cassette.

  The image forming apparatus 1 includes a detection sensor 31 that is arranged to face the image carrier and reads a developer image on the image carrier. The detection sensor 31 includes a front side detection sensor 31F provided on the front side of the body and a rear side detection sensor 31R provided on the back side of the body.

  FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus 1. As shown in FIG. 2, the image forming apparatus 1 includes a main CPU 201 that is a control unit 19 that performs overall control of the entire image forming apparatus 1, a ROM and RAM 202 that are memories, a storage device 215 such as a hard disk drive, and image processing. An image processing unit 204 that performs communication, and a communication interface (hereinafter referred to as I / F) 214 that communicates information with an external device.

  The main CPU 201 is connected to a print CPU 205 that controls each part of the image forming system, a scan CPU 209 that controls each part of the image reading system, and a drive controller 212 that controls the drive unit.

  In the case of an electronic system, the print CPU 205 controls a print engine 206 that forms an electrostatic latent image on the photosensitive drum 13B and a process unit 207 that forms a developer image.

  The print CPU 205 is connected to the detection sensor 31.

  The scan CPU 209 controls the CCD drive circuit 210 that drives the CCD 211. A signal from the CCD 211 is output to the image forming unit 13.

  The drive controller 212 is connected to the drive unit 213.

  FIG. 3 is a diagram showing the positional relationship between the detection pattern formed on the image carrier and the detection sensor 31. As shown in FIG. 3, the image forming unit 13, on the image carrier such as the transfer belt 14 </ b> B, for example, detects the developer images of the same shape for each color 32 Y, 32 M, 32 C, 32 K on the front side and rear side Form in two rows.

  The detection pattern may be wedge-shaped or straight. Hereinafter, a wedge-shaped detection pattern will be described as an example.

  The image forming apparatus 1 includes a front side detection sensor 31F at a position for reading the front side detection patterns 32Y, 32M, 32C, and 32K, and a rear side detection sensor 31R at a position for reading the rear side detection patterns 32Y, 32M, 32C, and 32K. And comprising.

  The image carrier moves in the direction indicated by the arrow. The image forming apparatus 1 reads the detection patterns 32 </ b> Y, 32 </ b> M, 32 </ b> C, and 32 </ b> K that pass by the detection sensor 31 and stores the read time in the RAM 202.

  FIG. 4 is a diagram illustrating the principle of detection of the main scanning magnification. As shown in FIG. 4, it is assumed that the cyan detection pattern 32C is greatly enlarged with respect to the reference color black detection pattern 32K and an image is formed.

  In this case, the image forming apparatus 1 calculates the time intervals K1 and C1 based on the output of the rear side detection sensor 31R, and calculates the time intervals K2 and C2 based on the output of the front side detection sensor 31F.

  If K1 and K2 are equal, C1 and C2 are equal, and K1 and C1 are different, the image forming apparatus 1 determines that correction of the cyan main scanning magnification is necessary. The image forming apparatus 1 calculates the magnification to be corrected by, for example, the ratio of the time interval between K1 and C1.

  This detection of the main scanning magnification is possible when the detection sensors 31 on both the front side and the rear side are normally detecting detection patterns for all colors.

  FIG. 5 is a diagram illustrating the principle of skew detection. As shown in FIG. 5, it is assumed that the cyan detection pattern 32C is obliquely formed with respect to the reference color black detection pattern 32K and an image is formed.

  In this case, the front side detection sensor 31F and the rear side detection sensor 31R simultaneously detect the detection pattern 32K at time T1, but for the cyan detection pattern 32C, the detection timing T2 of the front side detection sensor 31F and the rear side There is a time lag with respect to the detection timing T3 of the detection sensor 31R.

  The image forming apparatus 1 calculates the presence / absence of the skew and the correction amount based on the temporal shift.

  This skew can be detected when the detection sensors 31 on both the front side and the rear side of each color normally detect the detection pattern.

  FIG. 6 is a diagram illustrating the principle of detection of the sub-scanning position. As shown in FIG. 6, it is assumed that the cyan detection pattern 32C is image-formed with a delay in the sub-scanning direction from the position 32C 'where the image should be originally formed, with respect to the reference color black detection pattern 32K.

  In this case, the image forming apparatus 1 determines the sub-scanning direction in accordance with the ratio of the time interval between the timing T1 and the timing T2 stored in the ROM 202 in advance and the time interval between the actually calculated timing T1 and the timing T3. A correction amount is calculated.

  This sub-scanning position can be detected when at least one of the front-side and rear-side detection sensors 31 is normally detecting a detection pattern for all colors.

  FIG. 7 is a diagram showing the principle of detection of the main scanning position. As shown in FIG. 7, it is assumed that a cyan detection pattern 32C is formed in an image shifted to the rear side with respect to the reference color black detection pattern 32K.

  In this case, the image forming apparatus 1 calculates the correction amount in the main scanning direction based on the ratio between the time interval K1 calculated based on the output of the detection sensor 31 and the time interval C1.

  This sub-scanning position can be detected when at least one of the front-side and rear-side detection sensors 31 is normally detecting a detection pattern for all colors.

  FIG. 8 is a flowchart showing the operation of the image forming apparatus 1. As shown in FIG. 8, in step 801, the image forming apparatus 1 forms detection patterns 32Y, 32M, 32C, and 32K for the respective colors on the image carrier.

  In step 802, the image forming apparatus 1 detects the detection patterns 32Y, 32M, 32C, and 32K by the detection sensor 31.

  In step 803, the image forming apparatus 1 determines whether the detection patterns 32Y, 32M, 32C, and 32K are normally detected by the detection sensors 31 on both the front side and the rear side for all colors. If the image forming apparatus 1 determines that both sides are normally detected, the process proceeds to step 804. If it is determined that the both sides are not normally detected, the process proceeds to step 808.

  In step 804, the image forming apparatus 1 corrects the main scanning magnification.

  In step 805, the image forming apparatus 1 corrects the skew.

  In step 806, the image forming apparatus 1 corrects the main scanning position.

  In step 807, the image forming apparatus 1 corrects the sub-scanning position.

  In step 808, the image forming apparatus 1 determines whether or not the image forming apparatus 1 normally detects the detection patterns 32Y, 32M, 32C, and 32K for at least one of the front side and rear side detection sensors 31. . If it is determined that at least one of the image forming apparatuses 1 is normally detected, the process proceeds to step 809. If it is determined that both sides are not normally detected, the process proceeds to step 811.

  In step 809, the image forming apparatus 1 corrects the main scanning position.

  In step 810, the image forming apparatus 1 corrects the sub-scanning position.

  In step 811, the image forming apparatus 1 performs error processing.

  As described above, the image forming apparatus 1 of the present embodiment includes the sheet conveyance mechanism 18 that supplies a sheet, the image carrier that carries the developer image, and the detection patterns 32Y and 32M of the respective colors on the image carrier. The image forming unit 13 that forms images of 32C and 32K, the plurality of detection sensors 31 that read the detection patterns 32Y, 32M, 32C, and 32K, and any one of the plurality of detection sensors 31 is normally all-color detection pattern 32Y. , 32M, 32C, and 32K, a control unit that corrects a color shift that can be corrected based on one detection sensor 31 is provided.

  Therefore, there is an effect that it is possible to reduce the number of times of down due to a failure of a detection sensor that detects a detection pattern for color misregistration correction.

  Although several embodiments have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

13: Image forming unit 19: Control unit 31F: Front side detection sensor 31R: Rear side detection sensor

Claims (5)

A sheet conveying mechanism for supplying a sheet;
An image carrier for carrying a developer image;
An image forming unit that forms an image of a detection pattern of each color on the image carrier;
A plurality of detection sensors for reading the detection pattern;
When any one of the plurality of detection sensors normally reads the detection pattern of all colors, a control unit that corrects a color shift that can be corrected based on the one detection sensor that operates normally;
An image forming apparatus comprising: The plurality of sensors are:
A front detection sensor installed on the front side;
A rear detection sensor installed on the rear side;
The image forming apparatus according to claim 1, comprising: The color shift that can be corrected based on the one detection sensor is:
The image forming apparatus according to claim 2, comprising a color shift at a position in the main scanning direction. The color shift that can be corrected based on the one detection sensor is:
The image forming apparatus according to claim 2, comprising a color shift at a position in the sub-scanning direction. The controller is
The image forming apparatus according to claim 2, wherein when any one of the plurality of detection sensors normally reads the detection patterns of all colors, skew correction and main scanning magnification correction are not performed.

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