JP2008299083A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an adjustment in double-sided image formation so that the image forming positions on both the sides match, and to reduce processing processes. <P>SOLUTION: The image forming apparatus includes: an image forming section 41; an image reading section 60B; and a control section 11 that exerts control such that the image of image data is formed on a first side of paper by the image forming section 41, the image formed on the first side of the paper is read by the image reading section 60B, information about the position of a target image to be read is detected from the read image, according to an amount of deviation in the information about the position of a reference image for the target image to be read, the image forming position on a second side that is the back of the first side is adjusted so as to match the image forming position on the first side, and the image of the image data is formed on the second side of the paper by the image forming section 41. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  Conventionally, an image forming apparatus such as a copying machine for forming an image has been used. In this image forming apparatus, a configuration is considered in which a predetermined image is formed on a sheet together with an image to be image formed, and the predetermined image is read to form an image while preventing image displacement.

  For example, a booklet printing apparatus that prints on a booklet such as a bankbook is considered (see, for example, Patent Document 1). In this booklet printing apparatus, bar code page information is imaged in advance on each page of the booklet. Then, at the time of image formation, page information is read for each page, an image forming position correction amount for each page is determined based on the page information, and an image is printed at a desired position. This booklet printing apparatus has prevented the page image printing position from being shifted due to the thickness of the booklet.

In addition, in image formation on both sides, a configuration for adjusting the image positions on the front and back surfaces is considered. For example, a cross-shaped cross mark or a mark called a registration mark is formed on the front and back sides of a sheet of paper, and the mark is read to form an image so that the intersections of the front and back side marks coincide.
JP 2001-219608 A

  However, in forming a double-sided image, the configuration of the conventional booklet printing apparatus needs to provide an originally unnecessary image (bar code), and the process is complicated. Further, in the configuration in which the conventional cross mark image is formed on both sides, a process of forming the cross mark image on both sides is required. In addition, since a cross mark is not necessary in the final double-sided image formed product, a step of removing the cross mark is necessary. For this reason, the number of man-hours is increased, a cutting machine is required, and the scale of the image forming apparatus is also increased. In addition, in the configuration in which the conventional cross mark image is formed on both sides, the image data for the cross mark is edited to be added to the image data. Therefore, the original image data may be deleted by editing or unexpected. There were cases where accidents such as changes were made. Thus, it is a big problem that the processing that cannot reproduce the original image data is unexpectedly performed.

  SUMMARY OF THE INVENTION An object of the present invention is to perform adjustment so that the image positions on both sides are matched in the image formation on both sides, and to reduce processing steps. In particular, the configuration of the image forming apparatus is simpler, and the cutting apparatus for removing the cross mark is not required, so that the apparatus is not enlarged or complicated, and the original image data is not damaged. An object of the present invention is to provide an image forming apparatus that faithfully reproduces an image.

In order to solve the above problems, an image forming apparatus according to claim 1 is provided.
An image forming unit that forms an image on a sheet based on image data to be formed;
An image reading unit that reads an image of the image-formed paper;
Based on the image data, the image forming unit forms an image on the first surface of the paper, and the image reading unit reads the image of the paper on which the image is formed on the first surface, and the image is read from the read image. Position information of a reading target image that is a part of an image of data is detected, and the first surface according to the amount of deviation of the detected position information from the position information of a reference image that is a reference of the reading target image A control unit that adjusts the image forming position of the second surface on the second side to match the image position of the first surface, and causes the image forming unit to form an image on the second surface of the sheet based on the image data; .

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
The control unit controls the image forming position of the image forming unit on the sheet so that the image forming position of the second surface matches the image position of the first surface.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect,
A paper transport unit that transports paper by adjusting the position of the paper,
The control unit controls the paper position of the paper transport unit to match the image forming position on the second surface with the image position on the first surface.

The invention according to claim 4 is the image forming apparatus according to claim 1, 2, or 3,
An image processing unit that performs image processing of image data,
The control unit is configured to adjust the image forming position of the second surface to the image position of the first surface according to an amount of deviation of the detected position information from the position information of the reference image. The image processing unit causes the image processing unit to perform image processing, and causes the image forming unit to form an image on the second surface of the paper based on the image processed image data.

The invention according to claim 5 is the image forming apparatus according to at least one of claims 1 to 4,
The position information of the reference image has position information from the paper edge of the reference image,
The control unit calculates position information from the sheet edge in the reading target image based on the detected position information, and corresponds to a shift amount of position information from the sheet edge in the reference image and the reading target image. The image forming position on the second surface is adjusted to match the image position on the first surface.

The invention according to claim 6 is the image forming apparatus according to at least one of claims 1 to 4,
The position information of the reference image includes centroid position information in a predetermined image area of the reference image, and shape information indicating the size and shape of the reference image,
The control unit calculates centroid position information in the predetermined image area in the reading target image based on the detected position information and the shape information, and calculates the centroid position information in the reference image and the reading target image. The image forming position on the second surface is adjusted to match the image position on the first surface according to the amount of deviation.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect,
The reference image and the reading target image are at least one of characters and symbols,
The shape information is information on at least one font and size of the characters and symbols.

The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 7,
A storage unit is provided for storing position information of the reference image.

  According to the first aspect of the present invention, adjustment can be made so that the image positions on both sides are aligned, and the processing steps can be reduced without forming an unnecessary image on the final image formed product. Essentially, it is not necessary to process the original image data for adding unnecessary data, and inadvertent data damage can be avoided. Further, it is possible to reduce cutting waste generated by cutting performed to remove the cross mark. Then, the image is formed with a paper size having a margin for providing a cross mark. However, since the cross mark is not required, the paper size can be reduced, and handling such as transportation and filling becomes easy. Furthermore, it becomes unnecessary to form a mark for the purpose of alignment only, and toner for forming the mark can be saved.

  According to the second aspect of the present invention, it is possible to adjust so that the image positions on both sides are matched by controlling the image forming position on the sheet of the image forming unit.

  According to the third aspect of the present invention, the image positions on both sides can be adjusted to be matched by the paper position control of the paper transport unit.

  According to the fourth aspect of the present invention, the image positions on both sides can be adjusted to be matched by the image position control in the image processing unit.

  According to the fifth aspect of the present invention, it is possible to accurately adjust the image positions on both sides according to the shift amount of the position information from the sheet edge in the reference image and the reading target image.

  According to the sixth and seventh aspects of the invention, it is possible to accurately adjust the image positions on both sides according to the shift amount of the gravity center position information in the reference image and the reading target image.

  According to the eighth aspect of the invention, since the position information of the reference image is stored in the storage unit, the burden of inputting the position information of the reference image every time an image is formed can be reduced.

  Hereinafter, embodiments and modifications according to the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

  First, the apparatus configuration of the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 shows an image forming apparatus 1 according to the present embodiment. FIG. 2 shows an internal configuration of the image forming apparatus 1.

  In the present embodiment, an image forming apparatus 1 that is a copying machine is used. However, another image forming apparatus such as a printer may be used as the image forming apparatus.

  As shown in FIG. 1, the image forming apparatus 1 includes an image reading unit 20, an image forming unit 40, a paper feed unit 50, and a paper transport unit 60.

  The image reading unit 20 includes an image input unit 210 and an ADF (Auto Document Feeder) 200, and is disposed in the upper part of the copying machine main body. The ADF 200 operates to automatically feed one or a plurality of documents SC in the ADF mode. Here, the ADF mode refers to an operation mode in which the document SC placed on the ADF 200 is automatically fed and the document image is automatically read.

  The ADF 200 includes a document placement unit 201, a roller 202 a, a roller 202 b, a roller 203, a conveyance roller 204, and a paper discharge tray 206. One or more originals SC are placed on the original placement unit 201. A roller 202 a and a roller 202 b are provided on the downstream side of the document placement unit 201. When the ADF mode is selected, the document SC fed from the document placement unit 201 is conveyed by the downstream roller 203 so as to rotate in a U-shape. When the ADF mode is selected, the recording surface of the document SC is placed upward by the document placement unit 201.

  Further, the image input unit 210 operates to read a color image formed on the document SC. For the image input unit 210, for example, a color slit scan type scanner is used. The image input unit 210 includes image sensors 218 arranged in an array. For example, when the document SC is reversed into a U shape by the roller 203 in the ADF mode, the surface of the document SC is read to read the image. The signal Sout is output. For the image sensor 218, for example, a 3-line color CCD (Charge Coupled Device) imaging device is used.

  The image sensor 218 includes three reading sensors for detecting red (R), green (G), and blue (B) light that are configured by arranging a plurality of light receiving element arrays in the main scanning direction. The pixels are divided at different positions in the orthogonal sub-scanning direction, and light information of R, G, and B colors is read simultaneously.

  The document SC read by the image input unit 210 is transported by the transport roller 204 and discharged to the paper discharge tray 206. In addition, the image sensor 218 outputs an RGB color image reading signal obtained by reading the document SC in the platen mode. Here, the platen mode refers to an operation of automatically reading an original image by scanning an optical drive system on the original SC placed on the platen glass 211.

  In addition to the image sensor 218, the image input unit 210 includes a platen glass 211, a contact glass 212 (ADF glass), a light source 213, mirrors 214, 215, and 216, an imaging optical unit 217, and an optical drive unit (not shown). ing. The light source 213 operates to irradiate the original SC with light. The optical drive unit operates so as to relatively move the document SC or the image sensor 218 in the sub-scanning direction. The sub-scanning direction refers to a direction orthogonal to the main scanning direction when the arrangement direction of the plurality of light receiving elements constituting the image sensor 218 is the main scanning direction. As described above, the document SC placed on the document placement unit 201 of the ADF 200 is transported by the rollers 202 a, 202 b, 203 and the transport roller 204 described above, and is applied to one or both sides of the document SC by the optical system of the image input unit 210. The image is scanned and exposed, and incident light reflecting image reading is read by the image sensor 218.

  The image sensor 218 performs photoelectric conversion according to the amount of incident light. An image processing unit 42 is connected to the image sensor 218 via the control unit 10. The analog image read signal that has been subjected to photoelectric conversion is subjected to analog processing, A / D conversion, shading correction, image compression processing, scaling processing, and the like in the image processing unit 42, and digital data of R, G, and B color components. Image data. The image processing unit 42 converts the image data into Y, M, C, and BK color image data Dy, Dm, Dc, and Dk using a three-dimensional color information conversion table, and the color-converted image data Dy, Dm, Dc, and Dk are transferred to the writing units 3Y, 3M, 3C, and 3K included in the image forming unit 40.

  The image forming apparatus 1 is called a tandem type color image forming apparatus. An image forming unit 40 is provided in the image forming main body of the image forming apparatus 1. The image forming unit 40 forms a color image based on the image data Dy, Dm, Dc, Dk obtained by reading by the image reading unit 20. The image forming unit 40 includes an image forming unit 41 and an image processing unit 42. The image forming unit 41 includes a Y color image forming unit 40Y, an M color image forming unit 40M, a C color image forming unit 40C, and a BK color image forming unit 40K each having an image forming body for each color, and an endless intermediate transfer body. 6, a secondary transfer roller 7 </ b> A for transferring the image on the intermediate transfer body 6 to the paper P, and a fixing device 17 for fixing the toner image transferred to the paper P.

  A Y-color image forming unit 40Y that forms a yellow (Y) image is a photoreceptor drum 1Y as an image forming body that forms a Y-color toner image, and a Y-color image unit disposed around the photoreceptor drum 1Y. Charging unit 2Y, writing unit 3Y, developing unit 4Y, and image forming member cleaning unit 8Y. An M color image forming unit 40M that forms a magenta (M) color image includes a photosensitive drum 1M as an image forming body that forms an M color toner image, a charging unit 2M for M color, a writing unit 3M, A developing unit 4M and an image forming member cleaning unit 8M are provided.

  A C color image forming unit 40C for forming a cyan (C) color image includes a photosensitive drum 1C as an image forming body for forming a C color toner image, a charging unit 2C for C color, a writing unit 3C, A developing unit 4C and an image forming member cleaning unit 8C are provided. A K color image forming unit 40K that forms a black (BK) image includes a photosensitive drum 1K as an image forming body that forms a BK color toner image, a charging unit 2K for BK color, a writing unit 3K, It has a developing section 4K and an image forming body cleaning section 8K.

  The charging unit 2Y and the writing unit 3Y, the charging unit 2M and the writing unit 3M, the charging unit 2C and the writing unit 3C, and the charging unit 2K and the writing unit 3K are respectively connected to the photosensitive drums 1Y, 1M, 1C, and 1K. A latent image is formed. The writing units 3Y, 3M, 3C, and 3K are solid operation type writing in which a plurality of light modulation elements are arranged on a line in the main scanning direction orthogonal to the conveyance direction (sub-scanning direction) of the paper P on which an image is to be formed. In this example, an LED array head optical system using LED elements as light modulation elements is used. Development by the developing units 4Y, 4M, 4C, and 4K is performed by reversal development in which a development bias in which an AC voltage is superimposed on a DC voltage having the same polarity (for example, negative polarity) as the toner polarity to be used is applied. The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported. The toner of Y color, M color, C color, and BK color formed on each of the photosensitive drums 1Y, 1M, 1C, and 1K. The image is transferred.

  Further, the image forming unit 41 has a configuration capable of adjusting the image forming position on the back sheet when the front and back images are aligned based on the control of the control unit 10. Based on the control of the control unit 10, the image forming unit 41, for example, from the exposure unit (LED array optical system) in the writing units 3Y, 3M, 3C, and 3K to the photosensitive drums 1Y, 1M, 1C, and 1K. The image forming position on the paper can be adjusted according to the exposure timing or the like. Note that the writing units 3Y, 3M, 3C, and 3K may have an exposure unit and a polygon mirror instead of the LED array optical system. In the case of a configuration having this polygon mirror, the image forming position on the paper can be adjusted by the exposure timing from the exposure unit to the polygon mirror, the rotation speed of the polygon mirror, and the like.

  Here, an outline of the image forming process will be described. Each color image formed by the Y color image forming unit 40Y, the M color image forming unit 40M, the C color image forming unit 40C, and the BK color image forming unit 40K has a primary polarity opposite to that of the toner to be used (for example, positive polarity). A color image (color image) that is sequentially transferred onto the rotating intermediate transfer body 6 by the primary transfer rollers 7Y, 7M, 7C, and 7K to which a transfer bias (not shown) is applied, and is synthesized by superimposing colors. : Color toner image) is formed (primary transfer).

  Further, below the image forming unit 40, a paper feeding unit 50 that houses the paper P to be transported to the image forming unit 40 is provided. The paper feed unit 50 includes paper feed trays 51, 52 and 53. Each of the paper feed trays 51, 52, and 53 can accommodate paper P having different paper types (plain paper, recycled paper, high-quality paper, back paper, etc.), size, color, presence / absence of a hole, and the like. It has become. The number of trays is not limited to that shown in FIG. The paper P may be made of a material other than paper, such as an OHP (Over Head Projector) sheet.

  The paper P stored in the paper feed tray 51 or the like is transported by the paper transport unit 60A of the paper transport unit 60. The paper transport unit 60A includes a feed belt 61, a paper feed roller 62A, transport rollers 62B, 62C, and 62D, a registration roller 63, a paper discharge roller 64, a branching unit 66, a circulating paper path 67A, a reverse transport path 67B, and a refeed. A transport unit 67C and the like are provided.

  The paper transport unit 60 </ b> A has a configuration capable of adjusting the position of the paper P to be transported based on the control of the control unit 10. The paper transport unit 60A can adjust the position of the paper P in the transport direction by controlling the transport timing (rotation timing) of the registration rollers 63, for example. Further, the paper transport unit 60A includes a steering mechanism (not shown) on the transport path of the paper P. The steering mechanism has two rollers provided in a direction perpendicular to the conveyance direction of the paper P. These two rollers are provided at positions that are symmetrical from the center of the paper P. If the rotational speeds of the two rollers are controlled to be different based on the control of the control unit 10, the position of the paper P can be adjusted to a position where the orientation of the paper P is oblique with respect to the transport direction of the paper P. . The installation position of the steering mechanism is on the conveying path from the sheet output side of the fixing device 17 to the secondary transfer roller 7A via the circulating sheet passing path 67A, the reverse conveying path 67B, and the refeed conveying section 67C. Any position where the paper position can be controlled based on the image signal from 60B may be used.

  In addition, the paper transport unit 60 includes an image reading unit 60B. The image reading unit 60B includes a CIS (Contact Image Sensor). The image reading unit 60B is provided at a position where the surface of the paper P after image formation can be read on the conveyance path immediately before the registration roller 63. However, the installation position of the image reading unit 60B is not limited to this example. From the paper output side of the fixing device 17, the circulating sheet passing path 67A, the reverse conveying path 67B, and the refeed conveying section 67C are provided. On the transport path to the secondary transfer roller 7A, it is a position where the front surface of the paper P after image formation can be read. Based on the image signal from the image reading unit 60B, image formation position control and paper position control on the back surface are performed. Any position is possible.

  The image reading unit 60B reads an image from the paper P on which the surface is formed by the image forming unit 41 and conveyed through the reverse conveying path 67B and outputs the image signal to the control unit 10. The configuration of the image reading unit 60B is not limited to the configuration using the CIS, and may be a configuration using another image reading sensor such as a CCD.

  The paper P stored in the paper feed tray 51 and the like is fed by the feed belt 61 and the paper feed roller 62A, and is conveyed to the secondary transfer roller 7A through the conveyance rollers 62B, 62C and 62D, the registration roller 63, and the like. The color image is collectively transferred from the intermediate transfer body 6 to the paper P on one surface (front surface) of the paper P (secondary transfer).

  The sheet P on which the color image has been transferred is fixed by the fixing device 17, sandwiched between the discharge rollers 64, and placed on the discharge tray 65 outside the apparatus. The transfer residual toner remaining on the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer is removed by the cleaning units 8Y, 8M, 8C, and 8K and enters the next image forming cycle.

  At the time of double-sided image formation, after the image is formed on one side (front surface), the paper P discharged from the fixing device 17 is branched from the paper discharge path by the branching unit 66. Next, the sheet P passes through the lower circulating sheet passage 67A, and is reversed from the reverse conveyance path 67B which is a refeed mechanism (ADU mechanism), passes through the refeed conveyance section 67C, and is conveyed to the conveyance roller 62D. To the transfer path described above.

  In the configuration for transporting the paper P, the image reading unit 60B reads an image on the image-formed surface of the paper P being transported before the paper P on which the front surface image has been formed passes through the registration roller 63.

  The reversely conveyed paper P is conveyed again to the secondary transfer roller 7A through the registration roller 63, and a color image (color toner image) is collectively transferred onto the other surface (back surface) of the paper P. On the other hand, after the color image is transferred to the paper P by the secondary transfer roller 7A, the residual toner is removed by the intermediate transfer belt cleaning section 8A from the intermediate transfer body 6 from which the paper P is separated by curvature.

  In the present embodiment, an example in which the color electrophotographic method is applied to the image forming unit 40 will be described. However, the present invention is not limited to this, and other printing methods such as an ink jet method and a thermal sublimation method may be applied. It may be configured to form a monochrome image.

  As shown in FIG. 2, the image forming apparatus 1 includes a control unit 10, a print controller 14, an image reading unit 20, an operation unit 30, an image forming unit 40, and a paper transport unit 60. It is prepared for.

  The control unit 10 includes a control unit 11 composed of a CPU (Central Processing Unit), a RAM (Random Access Memory) 12, and a flash memory 13. In the control unit 10, among the various programs stored in the flash memory 13, a designated program is read out and expanded in the RAM 12, and various processes are executed in cooperation with the expanded program and the control unit 11. . In cooperation with the double-sided image forming program, the control unit 11 causes the image forming unit 40 to form an image on the surface of the paper P using the image reading unit 20 or the print controller 14, and causes the image reading unit 60B to form the paper. The image on the surface of P is read to obtain an image signal, and based on the image signal, position data of the image to be read from the edge of the paper P is detected, and the position of the reference image from the edge of the paper and the image of the image to be read are detected. The control amount of the image forming position on the back surface where the front and back image positions coincide with each other is calculated according to the amount of deviation from the position, and the input image data is transferred to the image forming unit 40 according to the control amount. Image.

  The RAM 12 is a volatile memory and has a work area for storing various programs and data. For example, image position data 70B described later is stored in the RAM 12. The flash memory 13 is a memory that stores information in a readable manner. The flash memory 13 stores reference image position data 70A and a double-sided image forming program (not shown). The reference image position data 70A may be acquired from data obtained from an image read by the image reading unit 20, data obtained from the print controller 14, or may be directly input from the operation unit 32. Further, if a reference image is determined, it may be stored in advance as a default.

  When the image forming apparatus 1 is used as a network printer, the print controller 14 receives image data transmitted from an external device such as a PC (Personal Computer) connected to a LAN (Local Area Network) or the like to form an image. Input to device 1.

  The image reading unit 20 reads image data of a document in accordance with a control signal from the control unit 11 and outputs the image data to the control unit 11.

  The image forming apparatus 1 may include an image storage unit such as a hard disk drive (HDD), and the image data input from the print controller 14 and the image reading unit 20 may be stored in the image storage unit. Image data stored in the image storage unit is read out and input to the control unit 11 when an image is formed.

  The operation unit 30 includes a display unit 31 including an LCD (Liquid Crystal Display) or the like, and an operation unit 32. The display unit 31 displays various display information input from the control unit 11. In addition, it is assumed that the display unit 31 includes a touch panel integrally with an operation unit 32 described later. The operation unit 32 receives input of operation information of a user's touch operation and outputs the operation information to the control unit 11.

  The image forming unit 40 includes an image forming unit 41 and an image processing unit 42. The image processing unit 42 performs various types of image processing on the image data input from the control unit 11 and outputs the processed image data to the image forming unit 41. For example, the image processing unit 42 decompresses and outputs the input compressed image data. The image forming unit 41 forms an image on the paper P based on the image data subjected to the image forming process by the image processing unit 42.

  The paper transport unit 60 includes a paper transport unit 60A, an image reading unit 60B, and a motor drive circuit 60C. The motor drive circuit 60C includes a plurality of motors that drive the rollers of the paper transport unit 60A. The motor driving circuit 60 </ b> C drives each motor and conveys the paper P under the control of the control unit 11.

  Next, information stored in the image forming apparatus 1 will be described with reference to FIGS. FIG. 3 shows the configuration of the reference image position data 70A and the image position data 70B.

  As shown in FIG. 3, the reference image position data 70 </ b> A stored in the flash memory 13 includes an object 71 indicating characters to be read, a paper size 72 of paper, a font 73 and a size 74 of characters of the object 71. , A table having items of reference positions 75 and 76.

  FIG. 4 shows the position of the reference image 80. As shown in FIG. 4, for the reference image 80 to be compared with the read target image 90, the reference image “−1−” (the symbol “−” on the left of the character “−1−”) from the end of the paper P <b> 0 as a reference. The position data of the upper left corner point 81 and the lower left corner point 82 are preset. This reference image is an image to be created at the same position in common with the reference image and the output image. This reference image may be selected from the operation unit 32 or may be set as a default in advance. Here, the paper edge p at the lower left corner of the paper P0 is the origin of the XY plane. The position data of the point 81 on the XY plane is stored in the reference position 75. The position coordinates of the point 81 are (X1, Y1). Further, the position data of the point 82 on the XY plane is stored in the reference position 76. Assume that the position coordinates of the point 82 are (X2, Y2).

  The image position data 70B stored in the RAM 12 is a table in which items of reading positions 77 and 78 are added to the reference image position data 70A. The reading positions 77 and 78 are position data of the reading target image 90 detected by the control unit 11.

  FIG. 5 shows the position of the reading target image 90. As shown in FIG. 5, the read target image 90 to be compared with the reference image 80 includes a point 91 at the upper left corner and a point 92 at the lower left corner of the read target image “-1-” from the end of the sheet P1 that is actually formed. And have. Here, the sheet edge p1 at the lower left corner of the sheet P1 is set as the origin of the XY plane. The position data of the point 91 on the XY plane is stored in the reading position 77. The position coordinates of the point 91 are (X3, Y3). Further, the position data of the point 92 on the XY plane is stored in the reading position 78. The position coordinates of the point 92 are (X4, Y4).

  Next, the operation of the image forming apparatus 1 will be described with reference to FIG. FIG. 6 shows the flow of double-sided image formation processing.

  In the image forming apparatus 1, for example, a double-sided image forming program that is read from the flash memory 13 and appropriately expanded in the RAM 12 triggered by the input of a double-sided image forming process execution instruction from the user via the operation unit 32. Then, double-sided image forming processing is executed in cooperation with the control unit 11.

  At this time, along with an instruction to execute the double-sided image forming process, a setting input as to whether or not to enter the front / back adjustment mode is performed from the user via the operation unit 32. The front / back adjustment mode is a mode for adjusting the positions of the images formed on the front and back sides of the paper to match.

  As shown in FIG. 6, first, it is determined whether or not a setting input has been made to the front / back adjustment mode via the operation unit 32 (step S1). When the front / back adjustment mode is set (step S1; YES), a front / back adjustment mode process described later is executed (step S2), and the double-sided image forming process ends. When the front / back adjustment mode is not set (step S1; NO), a normal image formation mode process in which normal image formation is performed on both sides of the sheet is executed (step S3), and the double-sided image formation process is completed.

  Here, the front / back adjustment mode processing described in step S2 will be described. First, image data to be image-formed is input via the image reading unit 20 or the print controller 14, and the image data is acquired (step S21).

  Then, the image forming unit 40 is controlled, and surface image formation on the sheet is started based on the image data to be formed corresponding to the surface acquired in step S21. Then, the image reading unit 60B is caused to read the image on the surface of the paper on which the surface image is formed in the image forming unit 40, and the image data is acquired. Then, the image position data (position from the sheet edge) of the reading target image 90 on the acquired image data is detected and acquired (step S22). The acquired image position data of the read target image 90 is combined with the reference image position data 70A read from the flash memory 13, and stored in the RAM 12 as image position data 70B.

  Then, based on the reference positions 75 and 76 of the image position data 70B stored in the RAM 12, the position of the reference image 80 from the sheet edge (the coordinate positions of the points 81 and 82) is acquired. Similarly, based on the object 71 of the image position data 70B, the paper size 72, the font 73, the size 74, and the reading positions 77 and 78, the position of the reading target image 90 from the paper edge (the coordinate position of the points 91 and 92) is determined. To be acquired. Then, the position of the reference image 80 and the position of the reading target image 90 are compared (step S23). Then, the control amount (correction amount) of the image forming position on the back surface is calculated so that the image positions on the front surface and the back surface coincide with each other in accordance with the position shift obtained in step S23 (step S24). This control amount includes a control amount for adjusting the image forming position on the paper in the image forming unit 41 and a control amount for adjusting the paper position in the paper transport unit 60A.

  Then, using the control amount calculated in step S24, the image forming position control of the image forming unit 41 and the paper position control of the paper transport unit 60A are executed, and the image forming target corresponding to the back surface acquired in step S21. On the basis of the image data, the back side image is formed on the paper on which the front side image is formed (step S25), and the front / back side adjustment mode processing is completed.

  In the front and back image adjustment processing, the front side is imaged and the back side is imaged. However, when forming images on a plurality of sheets, the front side image is formed on at least one predetermined number of sheets, and then the sheet is formed. It is good also as a structure which repeats forming a back surface image. Moreover, it is good also as a structure which forms a double-sided image by forming a surface image after forming a back image.

  As described above, according to the present embodiment, an image is formed on the surface of the paper, the reading target image that is a part of the image on the surface of the paper is read, the position of the reading target image from the paper edge is detected, and the reference image According to the amount of deviation of the position of the image to be read from the paper edge from the paper edge, the back side image forming position is adjusted so that the front and back image positions coincide with each other to form an image on the back side of the paper. . For this reason, in double-sided image formation, the image positions on the front and back surfaces can be accurately adjusted, and the processing steps can be reduced without forming an unnecessary image on the final image formed product. Further, it is possible to reduce cutting waste generated by cutting performed to remove the cross mark. Then, the image is formed with a paper size having a margin for providing a cross mark. However, since the cross mark is not required, the paper size can be reduced, and handling such as transportation and filling becomes easy. Furthermore, it becomes unnecessary to form a mark for the purpose of alignment only, and toner for forming the mark can be saved.

  Further, the image forming position on the sheet of the image forming unit 41 and the sheet position control of the sheet conveying unit 60A can accurately adjust the image forming position on the back surface so that the image positions on the front and back surfaces coincide with each other.

  In addition, since the reference image position data 70A is stored in the flash memory 13, the burden of inputting the reference image position data for each image formation can be reduced.

(Modification)
A modification of the above embodiment will be described with reference to FIG. In this modification, instead of the configuration for comparing the position of the reference image and the reading target image from the end of the sheet in the above embodiment, the positions of the center of gravity of the reference image and the reading target image are compared. For this reason, the description similar to the said embodiment is abbreviate | omitted and a different structure is mainly demonstrated. FIG. 7 shows the sheet P <b> 2 after image formation including the image area 100.

  In this modified example, as shown in FIG. 7, the symbol “-” located to the left of the page number is set as the read target image 101. An image region 100 including the reading target image 101 is set in advance. For the reading target image 101, the horizontal direction (X direction) length from the left end of the paper P2 to the image area 100 is x pixels, and the vertical direction (Y direction) length from the lower end of the paper P2 to the image area 100 is y pixels. The length in the X direction of the image area 100 is assumed to be xa pixels. The flash memory 13 further stores values x, y, and xa of the image area 100 in addition to the reference image position data of FIG.

  In the double-sided image forming process, in step S22, the position information of the paper edge and the position information of the reading target image 101 (symbol “−”) are acquired from the image data, and the reading position of the reading target image is acquired. Then, the sheet edge position information, the reading position, and the target (symbol “−”), font, size, reference position, and reference image position data including the values x, y, and xa of the image area 100 are combined. It is stored in the RAM 12 as image position data. In step S23, based on the object (symbol “−”) of the image position data stored in the RAM 12, the font, the size, the reference position, and the values x, y, and xa of the image area 100, the reference image in the image area 100 is stored. The position of the center of gravity is calculated. Similarly, reading in the image area 100 is performed based on the font and size of the reading target image 101 of the image position data, the position information of the paper edge, the position information of the reading target image 101, and the values x, y, and xa of the image area 100. The position of the center of gravity of the target image 101 is calculated. The calculation method of the center of gravity position differs depending on the font and size of the target symbol.

  In step S <b> 23, the barycentric position of the reference image is compared with the barycentric position of the reading target image 101. In step S24, the control amount (correction amount) of the image forming position and the paper position on the back surface is calculated so that the image gravity center positions on the front surface and the back surface coincide with each other in accordance with the shift in the gravity center position in step S23. .

  Further, the center of gravity position in the image area of the reference image may be stored in the flash memory 13 in advance. In this configuration, it is not necessary to calculate the centroid position in the image area of the reference image every time the centroid positions are compared, and the centroid position in the image area of the reference image is read from the flash memory 13.

  According to this modification, an image is formed on the surface of the paper, the image to be read on the surface of the paper is read, the position of the center of gravity in the image area 100 in the image to be read is obtained, and the position of the center of gravity in the image area in the reference image Depending on the amount of deviation from the center of gravity position in the read target image, the image forming position on the back surface is adjusted so that the image positions on the front and back surfaces coincide with each other to form an image on the back surface of the sheet. For this reason, in double-sided image formation, the image positions on the front and back surfaces can be accurately adjusted, and the processing steps can be reduced without forming an unnecessary image on the final image formed product.

  The descriptions in the above-described embodiments and modifications are examples of a suitable image forming apparatus according to the present invention, and the present invention is not limited to this.

  In the above embodiment and modification, the symbol “-” including or not including the page number is used as the reading target image (reference image). However, the present invention is not limited to this. FIG. 8 shows the configuration of the paper P3. For example, characters such as the page number 110 itself and the additional image 120 of “CONFIDENTIAL” as formed on the paper P3 shown in FIG. 8 may be set as the reading target image. The additional image may be another additional image such as “Do not Copy” or “Sample”. Further, at least one of various characters and various symbols may be used as a reading target image (reference image). Further, the reading target image (reference image) may be an arbitrary image other than characters and symbols. The arbitrary image is, for example, an image such as a predetermined mark or a bitmap. The information regarding the reference image may be configured to be input or set by the user via the operation unit 32 or input to the image forming apparatus 1 from an external device via a device such as the print controller 14. .

  In the embodiment and the modification described above, when the front and back images are aligned, the image position is controlled by the image forming position control of the image forming unit 41 and the paper position control of the paper transport unit 60A when the back side image is formed. Although the configuration is such that adjustment is performed, the present invention is not limited to this. The control unit 11 calculates a control amount of the image processing unit 42 for moving, rotating, or the like on the back side image data (image portion thereof) according to the amount of deviation between the position of the reference image and the image to be read. According to the control amount, the image processing unit 42 performs image processing on the back side image data, and the image forming unit 41 forms an image on the back side of the paper to perform image alignment on the front and back sides. It is good also as composition to do. Further, the image position adjustment of the front and back surfaces may be performed by at least one of the image formation position control of the image forming unit 41, the paper position control of the paper transport unit 60A, and the image position control of the image processing unit 42. Good.

  Further, the detailed configuration and detailed operation of each part constituting the image forming apparatus 1 in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

1 is a diagram showing an image forming apparatus 1 according to an embodiment of the present invention. 2 is a block diagram showing an internal configuration of the image forming apparatus 1. FIG. It is a figure which shows the structure of the reference | standard image position data 70A and the image position data 70B. FIG. 6 is a diagram showing the position of a reference image 80. It is a figure which shows the position of the reading object image 90. FIG. It is a flowchart which shows a double-sided image formation process. FIG. 3 is a diagram illustrating a sheet P2 after image formation including an image region 100. It is a figure which shows the structure of the paper P3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Control part 12 RAM
13 Flash memory 14 Print controller 20 Image reading unit 30 Operation unit 31 Display unit 32 Operation unit 40 Image forming unit 41 Image forming units 1Y, 1M, 1C, 1K Photosensitive drums 2Y, 2M, 2C, 2K Charging units 3Y, 3M, 3C, 3K writing unit 4Y, 4M, 4C, 4K Developing unit 6 Intermediate transfer member 7Y, 7M, 7C, 7K Primary transfer roller 7A Secondary transfer roller 8Y, 8M, 8C, 8K, 8A Cleaning unit 42 Image processing unit 50 Paper Feed Units 51, 52, 53 Paper Feed Tray 60 Paper Transport Unit 60A Paper Transport Unit 60B Image Reading Unit 60C Motor Drive Circuit 61 Feed Belt 62A Paper Feed Rollers 62B, 62C, 62D Transport Roller 63 Registration Roller 64 Paper Discharge Roller 65 Discharge tray 66 Branch portion 67A Circulating paper path 67B Rolling the transport path 67C refeeding section 200 ADF
201 Document Placement Units 202a, 202b, 203 Roller 204 Conveying Roller 205 Reversing Unit 206 Paper Discharge Plate 210 Image Input Unit 218 Image Sensor 211 Platen Glass 212 Contact Glass 213 Light Source 214, 215, 216 Mirror 217 Imaging Optical Unit 218 Image Sensor P Paper SC Original

Claims (8)

An image forming unit that forms an image on a sheet based on image data to be formed;
An image reading unit that reads an image of the image-formed paper;
Based on the image data, the image forming unit forms an image on the first surface of the paper, and the image reading unit reads the image of the paper on which the image is formed on the first surface, and the image is read from the read image. Position information of a reading target image that is a part of an image of data is detected, and the first surface according to the amount of deviation of the detected position information from the position information of a reference image that is a reference of the reading target image A control unit that adjusts the image forming position of the second surface on the second side to match the image position of the first surface, and causes the image forming unit to form an image on the second surface of the sheet based on the image data; And an image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit controls an image forming position on the sheet of the image forming unit to match an image forming position on the second surface with an image position on the first surface. A paper transport unit that transports paper by adjusting the position of the paper,
3. The image forming apparatus according to claim 1, wherein the control unit controls a paper position of the paper transport unit to match an image forming position of the second surface with an image position of the first surface. An image processing unit that performs image processing of image data,
The control unit is configured to adjust the image forming position of the second surface to the image position of the first surface according to an amount of deviation of the detected position information from the position information of the reference image. 4. The image formation according to claim 1, wherein the image processing unit causes the image processing unit to perform image processing, and the image forming unit forms an image on the second surface of the sheet based on the image processed image data. apparatus. The position information of the reference image has position information from the paper edge of the reference image,
The control unit calculates position information from the sheet edge in the reading target image based on the detected position information, and corresponds to a shift amount of position information from the sheet edge in the reference image and the reading target image. The image forming apparatus according to claim 1, wherein the image forming position on the second surface is adjusted to match the image position on the first surface. The position information of the reference image includes centroid position information in a predetermined image area of the reference image, and shape information indicating the size and shape of the reference image,
The control unit calculates centroid position information in the predetermined image area in the reading target image based on the detected position information and the shape information, and calculates the centroid position information in the reference image and the reading target image. 5. The image forming apparatus according to claim 1, wherein an image forming position on the second surface is adjusted to match an image position on the first surface in accordance with a shift amount. 6. The reference image and the reading target image are at least one of characters and symbols,
The image forming apparatus according to claim 6, wherein the shape information is information on at least one font and size of the characters and symbols.   The image forming apparatus according to claim 1, further comprising a storage unit that stores position information of the reference image.

Images