JP2019103122A - Reader, image forming apparatus, position detection method, and program - Google Patents

Abstract

To improve the accuracy of a position detection result.SOLUTION: A reader comprises: a position reference member on which a reference pattern including a line extending in a predetermined direction is arranged, and moves relatively in a direction orthogonal to the predetermined direction; a reading device on which a plurality of pixels are arranged; a reference pattern detection unit that detects the coordinate position in the orthogonal direction of each of the pixels of the reading device on the basis of the reference pattern; a correction value calculation unit that calculates at least a first correction value in the orthogonal direction for a pixel used for position detection, on the basis of the detected coordinate positions in the orthogonal direction of at least two pixels; a position detection unit that detects the outer shape of an object to be conveyed and the position of an image pattern on the object to be conveyed from the read data; and an angular error setting unit that sets a second correction value on the basis of the difference between an image formed through correction of the shape on the basis of a result of position detection performed by using the first correction value, and an image formed without correction of the shape. The position detection unit performs position detection by using the first correction value and the second correction value.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a reading device, an image forming apparatus, a position detection method, and a program.

  Conventionally, for the purpose of correcting the transport position of the transported object and the processing position with respect to the transported object, the outer edge position of the transported object and the processing position with respect to the transported object are read by a reading device such as CIS (Contact Image Sensor) Techniques for reading are disclosed.

  In addition, the lines in the test sheet are based on the image data obtained by scanning the reference scale with a scale in the longitudinal direction by the scanner and the image data obtained by reading the test sheet (object to be transported) on which the line is printed by the scanner. There is also disclosed a technique for calculating the absolute position of the relative position in the longitudinal direction.

  However, according to the related art, an angle error between the reference scale and the transport direction of the transported object causes a position detection error due to the fact that the outer edge position of the actual transported object is detected in a distorted form. There was a problem of

  The present invention has been made in view of the above, and an object thereof is to improve the accuracy of a position detection result.

  In order to solve the problems described above and to achieve the object, in the reading device of the present invention, a reference pattern including a line extending in a predetermined direction is disposed and relatively moved in a direction orthogonal to the predetermined direction. Reference pattern detection unit for detecting the coordinate position in the orthogonal direction of each pixel of the reading device based on the position reference member, the reading device in which a plurality of pixels are arranged, and the reference pattern disposed on the position reference member And a correction value for calculating a first correction value in the orthogonal direction of at least the pixel used for position detection based on the coordinate direction of the orthogonal direction of at least two of the pixels detected by the reference pattern detection unit. A position detection unit configured to detect an outer shape of the transferred object and a position of an image pattern on the transferred object from the data read by the reading device; A second correction value based on a difference between an image formed by correcting the shape based on the result of position detection using the first correction value by the position detection unit and an image formed without correcting the shape An angular error setting unit for setting the position detection unit, and the position detection unit performs position detection using the first correction value and the second correction value.

  According to the present invention, it is possible to improve the accuracy of the position detection result.

FIG. 1 is a schematic view showing an example of the hardware configuration of the printing system according to the first embodiment. FIG. 2 is a schematic view showing a reading device, a position reference member, and an installation mode. FIG. 3 is a schematic view showing the corresponding positional relationship between the reading device and the position reference member. FIG. 4 is a figure which shows the subject at the time of applying CIS to a reading device. FIG. 5 is a schematic view showing an example of reference lines arranged in the position reference member. FIG. 6 is a diagram showing the positional relationship between the position reference member and the reading device in the depth direction. FIG. 7 is a view showing the relationship between the position reference member and the conveyance direction of the recording medium. FIG. 8 is a block diagram showing an example of the electrical connection of the printing system hardware. FIG. 9 is a functional block diagram showing a functional configuration of the printing system. FIG. 10 is a schematic view showing an example of calculation of coordinates in the sub scanning direction of each sensor chip of the reading device. FIG. 11 is a diagram for explaining a method of correcting the inclination of the reading device. FIG. 12 is a diagram showing a method of calculating the outer shape of the recording medium and the position of the image pattern on the recording medium. FIG. 13 is a view exemplarily showing an image detected by the reading device. FIG. 14 is a diagram showing a method of calculating an angular error. FIG. 15 is a diagram showing a method of correcting an angular error. FIG. 16 is a flow chart schematically showing the flow of the correction value setting process. FIG. 17 is a perspective view showing the appearance of the reader according to the second embodiment. FIG. 18 is a side view partially showing the internal structure of the reader.

  Hereinafter, embodiments of a reading device, an image forming apparatus, a position detection method, and a program will be described in detail with reference to the attached drawings. In the following description, the case where a reading apparatus and an image forming apparatus are applied to a printing system including a printing apparatus such as a commercial printing machine (production printing machine) that continuously prints a large number of sheets in a short time will be described as an example. However, it is not limited to this.

First Embodiment
[Description of the hardware configuration of the printing system]
FIG. 1 is a schematic view showing an example of the hardware configuration of the printing system 1 according to the first embodiment. As shown in FIG. 1, the printing system 1, which is an image forming apparatus, includes a printing apparatus 100, a medium position detection apparatus 200 (an example of a position detection apparatus), and a stacker 300.

  The printing apparatus 100 includes an operation panel 101, image forming units 103Y, 103M, 103C, and 103K of a tandem type electrophotographic method, a transfer belt 105, a secondary transfer roller 107, a sheet feeding unit 109, and a pair of conveying rollers. And a fixing roller 104 and a reverse path 106.

  The operation panel 101 is an operation display unit that inputs various operations to the printing apparatus 100 and the medium position detection apparatus 200 and displays various screens.

  The image forming units 103Y, 103M, 103C, and 103K have toner images formed by performing image forming processes (charging step, exposure step, developing step, transfer step, and cleaning step), respectively. Is transferred to the transfer belt 105. In the present embodiment, a yellow toner image is formed on the image forming unit 103Y, a magenta toner image is formed on the image forming unit 103M, and a cyan toner image is formed on the image forming unit 103C. On the other hand, a black toner image is to be formed, but it is not limited thereto.

  The transfer belt 105 conveys the toner images (full-color toner images) transferred overlappingly from the image forming units 103Y, 103M, 103C, and 103K to the secondary transfer position of the secondary transfer roller 107. In this embodiment, first, a yellow toner image is transferred to the transfer belt 105, and subsequently, a magenta toner image, a cyan toner image, and a black toner image are sequentially superimposed and transferred. It is not limited.

  The sheet feeding unit 109 stores a plurality of recording media as processing targets (conveyed objects) in a stacked manner, and feeds the recording media. Examples of the recording medium include, but not limited to, recording paper (transfer paper), for example, coated paper, thick paper, OHP (Overhead Projector) sheet, plastic film, prepreg, copper foil, etc. Any possible medium may be used.

  The conveyance roller pair 102 conveys the recording medium fed by the paper feed unit 109 in the arrow s direction on the conveyance path a.

  The secondary transfer roller 107 collectively transfers the full color toner image conveyed by the transfer belt 105 onto the recording medium conveyed by the conveyance roller pair 102 at a secondary transfer position.

  The fixing roller 104 fixes the full-color toner image on the recording medium by heating and pressing the recording medium to which the full-color toner image has been transferred.

  In the case of single-sided printing, the printing apparatus 100 sends a print, which is a recording medium on which a full-color toner image is fixed, to the medium position detection apparatus 200. On the other hand, in the case of double-sided printing, the printing apparatus 100 sends the recording medium on which the full-color toner image is fixed to the reverse pass 106.

  The reverse path 106 reverses the front and back surfaces of the recording medium by switching back the sent recording medium and transports the recording medium in the direction of the arrow t. The recording medium conveyed by the reverse path 106 is re-conveyed by the conveyance roller pair 102, the full-color toner image is transferred to the surface opposite to the previous one by the secondary transfer roller 107, and is fixed by the fixing roller 104. , Media position detection device 200 and stacker 300.

  The media position detection device 200 located downstream of the printing apparatus 100 includes a reading device 201 and a position reference member 202.

  The reading device 201 can be realized by, for example, a CIS (Contact Image Sensor) in which a plurality of imaging elements (CMOS image sensors) are arranged in a line. The reading device 201 receives the reflected light from the reading target and outputs an image signal. Specifically, the reading device 201 sets the conveyance position of the recording medium sent from the printing apparatus 100 and the processing position (printing position) on the recording medium as a reading target. Further, the reading device 201 sets the position reference member 202 as a reading target.

  The CIS applied to the reading device 201 is generally known in the configuration that secures a necessary main scanning effective reading length by arranging a plurality of sensor chips 210 (see FIG. 4) having a plurality of pixels in the main scanning direction. It is done.

  The position reference member 202 is a reference plate for correcting the mounting position of each sensor chip 210 of the reading device 201 configured by a plurality of sensor chips 210. By thus correcting the mounting position of each sensor chip 210 of the reading device 201 using the position reference member 202, highly accurate image position detection is performed.

  Then, the medium position detection device 200 discharges the recording medium for which reading has been completed to the stacker 300.

  The stacker 300 includes a tray 301. The stacker 300 stacks the recording medium discharged by the medium position detection device 200 on the tray 301.

  Next, the reading device 201 and the position reference member 202 in the medium position detection device 200 will be described.

  By the way, accuracy is not obtained with the method of reading the outline edge position of the transported object and the processing position for the transported object with a reading device such as CIS, and correcting the transported position of the transported object and the processing position for the transported object. There was a problem that there was a case.

  FIG. 2 is a schematic view showing an installation mode of the reading device 201, the position reference member 202, and the like. As shown in FIG. 2, the position reference member 202 is provided on a rotating member 203 that is rotationally driven by the motor 204. The position reference member 202 is moved by a rotating member 203 rotated at a constant speed by a motor 204. The position reference member 202 is disposed on the facing surface of the reading device 201 at a predetermined timing as the rotation member 203 rotates.

  The position reference member 202 is rotated in such a manner that the position reference member 202 is moved at a constant speed in the sub scanning direction in order to detect the mounting inclination of the reading device 201 in the sub scanning direction. In order to read a reference line X (see FIG. 4) which is a reference pattern including a line extending in a predetermined direction disposed in

  Although in FIG. 2 the position reference member 202 is attached to the rotating member 203 and the position reference member 202 is moved at a constant speed in the sub scanning direction, the present invention is not limited to this. For example, the position reference member 202 may be provided so as to be linearly movable.

  FIG. 3 is a schematic view showing the corresponding positional relationship between the reading device 201 and the position reference member 202. As shown in FIG. As shown in FIG. 3, the position reference member 202 sets a position corresponding to the head pixel, which is an imaging element at one end (front end) of the reading device 201 in the main scanning direction, as a reference position (supporting point).

  Further, also in the reading device 201, a position corresponding to the head pixel corresponding to the reference position of the position reference member 202 is set as a reference position (supporting point).

  Here, problems in applying the CIS to the reading device 201 will be described. FIG. 4 is a view showing a problem in applying the CIS to the reading device 201. As shown in FIG. As shown in FIG. 4, for example, when the reading device 201 is attached obliquely to the position reference member 202, the image itself read by the reading device 201 has a low position detection accuracy with respect to the position reference member 202. , Correct correction can not be made (installation variation).

  In addition, when the CIS is applied to the reading device 201, as shown in FIG. 4, the pixels in each sensor chip 210 are arranged uniformly and linearly, but the arrangement of the plurality of sensor chips 210 is sub-scanned. There is a possibility of deviation in the direction (chip position variation).

  Therefore, in order to further improve the position detection accuracy in consideration of the above-described problem, the following configuration can be considered.

  Here, FIG. 5 is a schematic view showing an example of reference lines arranged on the position reference member 202. As shown in FIG. As shown in FIG. 5, a predetermined reference line X is disposed on the position reference member 202. The reference line X disposed on the position reference member 202 is a line parallel to the main scanning direction (predetermined direction) of the reading device 201 (hereinafter referred to as “horizontal line”) and the main scanning direction of the reading device 201 It is comprised by the orthogonal line (following "vertical line") extended in the orthogonal direction.

  As shown in FIG. 5, the vertical lines are arranged at equal intervals corresponding to the sensor chips 210 on the position reference member 202 so that the sensor chips 210 on the substrate of the reading device 201 can be read respectively. There is. Moreover, the horizontal line is arrange | positioned between the said vertical lines.

  Incidentally, as shown in FIG. 5, by creating a gap between the vertical line and the horizontal line on the position reference member 202, the coordinate of the vertical line is calculated even if the horizontal line is in the reading range of the reading device 201. It can be done.

Ideally, a horizontal line is read for each sensor chip 210 of the reading device 201 to detect the coordinate position of each sensor chip 210 in the sub-scanning direction, and two points corresponding to the sensor chip 210 at the end of the reading device 201 It is preferable to read the horizontal lines to detect the inclination of the reading device 201 itself and correct the reading result by the reading device 201, but there are the following disadvantages.
Since the sub-scanning position must be detected for each and every pixel, the processing becomes complicated and the processing time increases.
Since the correction values of all the pixels are calculated, it is necessary to record the all pixel correction values, and the memory capacity is required accordingly.
The processing is complicated and time-consuming because it is necessary to pull information from a large table even when using correction values.

  Therefore, in the present embodiment, two horizontal lines corresponding to the sensor chip 210 at the end of the reading device 201 are read to detect the coordinate position in the sub scanning direction, and these two coordinate positions in the sub scanning direction The inclination determined by the above is the inclination of the reading device 201. Then, the degree of inclination of each sensor chip 210 (each pixel) of the reading device 201 is obtained from the inclination of the reading device 201, which makes it possible to reduce the detection position in the subscanning direction and the result recording.

  The position reference member 202 does not function as an absolute position reference when expansion / contraction occurs due to the heat generation of the peripheral members or the like, and the position detection accuracy is deteriorated. Therefore, the position reference member 202 is made of a material having a linear expansion coefficient lower than that of the substrate of the reading device 201 and so small in position detection that the amount of expansion and contraction due to the influence of ambient temperature can be ignored. In the present embodiment, the position reference member 202 is formed of glass in consideration of the assumed temperature change range and the linear expansion coefficient. The material of the position reference member 202 is not limited to this, and it is more preferable to use quartz glass or the like in order to realize accurate medium position detection when the temperature change range of the reading device 201 is wide. is there.

FIG. 6 is a view showing the positional relationship between the position reference member 202 and the reading device 201 in the depth direction. Usually, the reading device 201 such as CIS has a characteristic that the image characteristic changes depending on the height (depth) direction. As a representative example of such image characteristics, generally
・ MTF (depth of focus)
・ Lighting depth is mentioned. Further, some reading devices 201 have characteristics that differ in characteristics depending on the position in the main scanning direction in addition to the height (depth) direction dependency.

  Therefore, in the present embodiment, the depth (height) direction position when reading device 201 reads a recording medium, and the depth (height) when reading device 201 reads reference line X on position reference member 202. The position reference member 202 and the reading device 201 are disposed such that the directional position matches. Thereby, the accuracy of position detection can be improved by reducing the influence of the image characteristic difference of the reading device 201 depending on the depth direction as much as possible.

  Furthermore, another subject will be described.

  As described above, the inclination error of the reading device 201 can be obtained to correct the mounting error between the position reference member 202 and the reading device 201. However, the conveyance direction of the recording medium changes depending on the assembly position accuracy of the main body side plate, the assembly position accuracy of the conveyance rollers before and after, the diameter difference and the pressure deviation, and the angular error in the conveyance direction of the position reference member 202 and the recording medium It may happen.

  FIG. 7 is a view showing the relationship between the position reference member 202 and the conveyance direction of the recording medium. FIG. 7A shows the case where angular error occurs in the position reference member 202 and the recording medium, and FIG. 7B shows the case where angular error and the skew in the recording medium occur in the position reference member 202 and the recording medium .

  As shown in FIG. 7A, when there is an angle error between the position reference member 202 and the recording medium, the image read by the reading device 201 is a parallelogram in which the squareness of the four sides is distorted by the angle error. Is detected as Further, as shown in FIG. 7B, when there is an angular error in the position reference member 202 and the recording medium and skew occurs in the recording medium, the image read by the reading device 201 has squareness of four sides by the skew. Detected as a distorted parallelogram.

  Since the transport direction of the recording medium changes depending on the assembly position accuracy of the main body side plate, the assembly position accuracy of the transport rollers before and after, the diameter difference, and the pressure deviation, the correction value for each device is required.

  FIG. 8 is a block diagram showing an example of the electrical connection of the hardware of the printing system 1.

  As shown in FIG. 8, the printing system 1 has a configuration in which a controller 10, an engine unit (Engine) 60, and an engine unit (Engine) 70 are connected by a PCI bus. The controller 10 is a controller that controls the entire printing system 1, draws, communicates, and controls an input from the operation panel 101 that is an operation display unit. The engine unit 60 is an engine connectable to the PCI bus, and is, for example, a scanner engine such as the reading device 201. The engine unit 60 includes an image processing unit such as error diffusion and gamma conversion in addition to the engine unit. The engine unit 70 is an engine connectable to the PCI bus, and is, for example, a print engine such as a plotter including the image forming units 103Y, 103M, 103C, and 103K.

  The controller 10 includes a central processing unit (CPU) 11, a north bridge (NB) 13, a system memory (MEM-P) 12, a south bridge (SB) 14, a local memory (MEM-C) 17, and an ASIC. (Application Specific Integrated Circuit) 16 and a hard disk drive (HDD) 18 are provided, and the north bridge (NB) 13 and the ASIC 16 are connected by an AGP (Accelerated Graphics Port) bus 15. The MEM-P 12 further includes a ROM 12 a and a RAM 12 b.

  The CPU 11 performs overall control of the printing system 1 and includes a chipset including NB 13, MEM-P 12 and SB 14, and is connected to other devices via this chipset.

  The NB 13 is a bridge for connecting the CPU 11 to the MEM-P 12, the SB 14, and the AGP bus 15, and includes a memory controller that controls reading and writing to the MEM-P 12, a PCI master and an AGP target.

  The MEM-P 12 is a system memory used as a memory for storing programs and data, a memory for expanding programs and data, a memory for drawing a printer, and the like, and includes a ROM 12 a and a RAM 12 b. The ROM 12a is a read-only memory used as a storage memory for programs and data, and the RAM 12b is a writable and readable memory used as a development memory for programs and data, a drawing memory for a printer, and the like.

  The SB 14 is a bridge for connecting the NB 13 to PCI devices and peripheral devices. The SB 14 is connected to the NB 13 via the PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

  The ASIC 16 is an IC (Integrated Circuit) for image processing application having a hardware element for image processing, and has a role of a bridge connecting the AGP bus 15, the PCI bus, the HDD 18 and the MEM-C 17 respectively. The ASIC 16 includes a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 16, a memory controller that controls the MEM-C 17, and a plurality of DMACs (Direct Memory) that rotate image data by hardware logic. And a PCI unit for transferring data between the engine unit 60 and the engine unit 70 via the PCI bus. A USB 40 and an IEEE 1394 (the Institute of Electrical and Electronics Engineers 1394) interface (I / F) 50 are connected to the ASIC 16 via a PCI bus. The operation panel 101 is directly connected to the ASIC 16.

  The MEM-C 17 is a local memory used as a copy image buffer and a code buffer, and the HDD 18 is a storage for storing image data, programs, font data, and forms.

  The AGP bus 15 is a bus interface for a graphics accelerator card proposed to speed up graphics processing, and makes the graphics accelerator card faster by directly accessing the MEM-P 12 with high throughput. It is.

  The program executed by the printing system 1 according to the present embodiment is a file in an installable format or an executable format, and is a computer such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk). It may be configured to be recorded on a readable recording medium and provided.

  Furthermore, the program executed by the printing system 1 according to the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program executed by the printing system 1 according to the present embodiment may be provided or distributed via a network such as the Internet.

[Description of Functional Configuration of Printing System 1]
Next, a function performed by the CPU 11 of the printing system 1 executing a program stored in the HDD 18 or the ROM 12a will be described. Here, the description of the conventionally known functions will be omitted, and the characteristic functions exhibited by the printing system 1 of the present embodiment will be described in detail.

  FIG. 9 is a functional block diagram showing a functional configuration of the printing system 1.

  As shown in FIG. 9, the CPU 11 of the printing system 1 includes a read control unit 110, a motor control unit 111, a horizontal line detection unit 112 which is a reference pattern detection unit, a detection result storage unit 113, an inclination correction value calculation unit 114, and position detection. It functions as the unit 115 and the angular error setting unit 116. The CPU 11 is a recording medium in addition to the reading control unit 110, the motor control unit 111, the horizontal line detection unit 112, the detection result storage unit 113, the inclination correction value calculation unit 114, the position detection unit 115, and the angle error setting unit 116. It is needless to say that the function of the conveyance control unit or the like that controls the conveyance of the sheet may be realized.

  In the present embodiment, the CPU 11 implements the characteristic function exhibited by the printing system 1 by executing a program, but the present invention is not limited to this. For example, the functions of the respective units described above Some or all of them may be realized by dedicated hardware circuits.

  The motor control unit 111 outputs a drive signal to the motor 204 to rotationally drive the rotating member 203. The motor control unit 111 also outputs a drive stop signal to the motor 204 to stop the rotation of the rotating member 203.

  The reading control unit 110 outputs a reading start signal to the reading device 201 and causes the reading device 201 to start reading. Further, when the reading control unit 110 receives a reading signal from the reading device 201, the reading control unit 110 outputs a reading end signal to the reading device 201, and ends reading by the reading device 201.

  The horizontal line detection unit 112 moves the position reference member 202 in the sub-scanning direction via the motor control unit 111. In addition, the horizontal line detection unit 112 reads the position reference member 202 moving in the sub scanning direction via the reading control unit 110 by the reading device 201. Then, the horizontal line detection unit 112 detects the coordinate position in the sub-scanning direction of each sensor chip 210 of the reading device 201.

  Here, FIG. 10 is a schematic view showing an example of coordinate calculation in the sub-scanning direction of each sensor chip 210 of the reading device 201. As shown in FIG. As shown in FIG. 10A, the horizontal line detection unit 112 performs position reference in an area of An, An + 1,..., An + m or Bn, Bn + 1,..., Bn + m for each sensor chip 210 of the reading device 201. The horizontal line of the member 202 is read, and the coordinate position of each sensor chip 210 of the reading device 201 in the sub-scanning direction is detected.

  As described above, reading the horizontal lines of the position reference member 202 at substantially the same pixel position for each sensor chip 210 is computationally advantageous for correction. However, the present invention is not limited to this, and the pixel position at which the horizontal line of the position reference member 202 is read may be changed to an arbitrary pixel for each sensor chip 210.

  More specifically, the horizontal line detection unit 112 reads the A or B area (width m pixels) of each sensor chip 210 of the reading device 201 while rotating the position reference member 202 in the sub-scanning direction. As shown in FIG. 10B, the read values for m pixels are averaged for each line of each sensor chip 210 of the reading device 201, and the data is stored in a storage unit (such as the RAM 12b or the HDD 18). The horizontal line detection unit 112 detects the coordinate position of each sensor chip 210 of the reading device 201 from the positions of the rising edge and the falling edge from the obtained data.

  The detection result storage unit 113 stores the coordinate position of each sensor chip 210 of the reading device 201 detected by the horizontal line detection unit 112 in a storage unit (such as the RAM 12 b or the HDD 18).

  The inclination correction value calculation unit 114 calculates a correction value of the inclination of the reading device 201. Here, FIG. 11 is a view for explaining the inclination correction method of the reading device 201.

  As shown in FIG. 11, the inclination correction value calculation unit 114 calculates the inclination of the entire reading device 201 from the coordinate position in the sub-scanning direction at which the two horizontal lines corresponding to the sensor chip 210 at the end of the reading device 201 are read. Do.

An example of calculation of the inclination of the reading device 201 in a case where twelve sensor chips 210 are arranged in the reading device 201 and there are 216.5 pixels for each sensor chip 210 is shown below. The 0.5 pixel is the distance for the gap between the sensor chips 210.
Inclination of the reading device 201 = (coordinate position of the twelfth sensor chip 210 in the sub-scanning direction-first coordinate position of the sensor chip 210 in the sub-scanning direction) / (12 x 216.5)

  After the inclination of the entire reading device 201 is obtained, the inclination correction value calculation unit 114 calculates a correction value in the sub-scanning direction in the pixel used for position detection. More specifically, the inclination correction value calculation unit 114 acquires one coordinate position in the sub-scanning direction of each sensor chip 210 of the reading device 201 from the storage unit. Then, the inclination correction value calculation unit 114 calculates the first correction value of the pixel to be obtained by multiplying the inclination of the entire reading device 201 by the corresponding pixel of the sensor chip 210 based on the acquired coordinate position.

An example of calculation of the first correction value in the sub scanning direction is shown below. Here, m indicates the number of pixels in the sensor chip 210. Therefore, m is in the range of 1 to 216.
First correction value = coordinate position of n-th sensor chip 210 in the sub-scanning direction + inclination of the entire reading device 201 × m

As described above, when changing the pixel position for reading the horizontal line of the position reference member 202 to an arbitrary pixel for each sensor chip 210, the following equation is applied.
Correction value = position coordinate of the n-th sensor chip 210 in the sub-scanning direction (the p-th pixel) + slope of the entire reading device 201 × (m−p)
p pixel: the number of pixels from the start of the sensor chip

  The position detection unit 115 detects the outer shape of the recording medium and the position of the image pattern on the recording medium from the image read by the reading device 201.

  Here, FIG. 12 is a diagram showing a method of calculating the outer shape of the recording medium and the position of the image pattern on the recording medium. As shown in FIGS. 12A and 12B, L-shaped image patterns P are formed at the four corners O of the recording medium. The position detection unit 115 detects the sheet edge and the start and end coordinates of the image pattern from the image level in the main scanning direction and the sub scanning direction. Considering the case where the external shape of the recording medium is to be determined as an example, the coordinates of four places in the main scan and four places in the subscan are detected, and their intersections are calculated as the four corners O of the end of the recording medium. As shown in FIG. 12C, when the position detection unit 115 determines the intersection point, the sub-scanning coordinates (main scanning coordinates when detecting the sub-scanning coordinates) when detecting the main scanning coordinates are the recording medium The position in the sub-scanning direction is calculated as an ideal value depending on which position of. Note that the position detection unit 115 may calculate the four corners O directly when calculating the end portion of the recording medium after taking in the data of all the pixels because there is room in the memory.

  Here, FIG. 13 is a view exemplarily showing an image detected by the reading device 201, where (a) shows the case where the conveyance direction of the recording medium is perpendicular to the position reference member 202, and (b) shows the recording medium. The case where the transport direction is inclined with respect to the position reference member 202 is shown.

  As shown in FIG. 13B, when the conveyance direction of the recording medium is inclined with respect to the position reference member 202 and there is an angle error, the image detected by the reading device 201 is distorted by the inclination of the conveyance direction of the recording medium. appear. The first correction value described above is used to correct the inclination between the position reference member 202 and the reading device 201, and the inclination between the conveyance direction of the recording medium and the position reference member 202 is the first It can not be corrected only with the correction value.

  Next, the angular error setting unit 116 will be described.

  The printing system 1 reads a predetermined image or a recording medium with the reading device 201 that has performed position correction using the position reference member 202 as described above, corrects writing based on the read image, and outputs an image. Do. As an example, in the present embodiment, an L-shaped image pattern P as shown in FIG. 13 is read and writing correction is performed to correct the shape of the image and output a quadrangle (writing correction ON). However, when there is an angle error between the position reference member 202 and the recording medium, if the correction is made based on the position detection result in the position detection unit 115 without correcting the angle error, the squareness is distorted instead of being square. A parallelogram image is output. In addition, the printing system 1 outputs an image (square) which does not have any shape correction in which the writing correction itself is turned off. That is, the difference between the conveyance direction of the recording medium and the position reference member 202 according to the comparison result of ON of write correction and OFF of write correction corresponds to an angle error.

  Here, FIG. 14 is a view showing a method of calculating an angle error. FIG. 14A shows a method of calculating an angle error based on the upper side. As shown in FIG. 14A, in the case of the upper side reference, the angle error is calculated from the squareness.

  FIG. 14B shows a method of calculating the angle error when the side reference is not used and the skew correction is not performed. As shown in FIG. 14B, in the case where the side reference is not performed and the skew correction is not performed, the angular error is calculated by the sub-scanning registration deviation.

  Therefore, in the present embodiment, the difference between the output image of the correction of writing OFF and the correction ON of writing is measured using an external position measuring device, and the measured difference is measured between the conveyance direction of the recording medium and the position reference member 202. Used to calculate the angular error. However, the parameters used to calculate the angular error differ depending on the position correction algorithm. Although the difference of the output image is measured and input by the external position measuring device, the present invention is not limited to this, and a person may measure and input to the printing system 1. It may be determined by a scanner mounted on the printing system 1.

  The angular error setting unit 116 stores and sets the difference of the output image input from the outside in the storage unit as a second correction value.

  Then, the position detection unit 115 performs position correction in which the first correction value corresponding to the pixel calculated by the inclination correction value calculation unit 114 is offset by the second correction value (angular error).

  FIG. 15 is a diagram showing a method of correcting an angular error. FIG. 15 shows an angular error correction method in the case where two CISs in which the reading device 201 is divided into 12 chips are used. As shown in FIG. 15, to offset by the second correction value (angular error) means to correct in the sub-scanning direction by the angular error according to the distance from the reference position with respect to each sensor chip 210 of the reading device 201 The actual error correction is shown by adding the coefficients. At this time, the position detection unit 115 does not perform correction in the main scanning direction because an error generated is sufficiently small compared to the sub-scanning direction.

  Next, the correction value setting process performed by the printing system 1 will be described.

  Here, FIG. 16 is a flow chart schematically showing the flow of the correction value setting process. As shown in FIG. 16, when the horizontal line reading start trigger is detected, the horizontal line detection unit 112 starts reading the horizontal line of the position reference member 202 while moving the position reference member 202 in the sub scanning direction (step S1). . More specifically, the horizontal line detection unit 112 moves the position reference member 202 in the sub-scanning direction via the motor control unit 111. In addition, the horizontal line detection unit 112 reads the position reference member 202 moving in the sub scanning direction via the reading control unit 110 by the reading device 201. When the reading by the reading device 201 is completed, the reading device 201 outputs a reading end trigger to the horizontal line detection unit 112.

  When the horizontal line detection unit 112 receives the reading end trigger, the horizontal line detection unit 112 stops the movement of the position reference member 202 in the sub scanning direction, and is in a standby state. Also, when receiving the reading end trigger, the horizontal line detection unit 112 detects the coordinate position in the sub-scanning direction of each sensor chip 210 of the reading device 201 (step S2).

  Next, the detection result storage unit 113 stores the coordinate position of each sensor chip 210 of the reading device 201 detected by the horizontal line detection unit 112 in the storage unit (step S3).

  Next, the inclination correction value calculation unit 114 calculates a correction value (first correction value) of the inclination of the reading device 201 (step S4).

  Then, the position detection unit 115 refers to the first correction value corresponding to the pixel calculated by the inclination correction value calculation unit 114, adds a correction according to the first correction value to the position detection result (step S5), and writes An image of correction OFF is formed.

  Thereafter, the angular error setting unit 116 stands by until the difference between the output image of the correction of writing OFF and the correction of writing ON from the outside is input (No in step S6). When the difference between the output image of the correction of writing OFF and the correction of writing ON from the outside is input (Yes in step S6), the angular error setting unit 116 uses the difference of the output image input from the outside as the second correction value. , And stored in the storage unit (step S7). Thus, the correction value setting process ends.

  Thereafter, the position detection unit 115 performs position correction for offsetting the first correction value corresponding to the pixel calculated by the tilt correction value calculation unit 114 by the second correction value (angle error) with respect to the position detection result. Do.

  As described above, according to the present embodiment, when there is an angular error between the position reference member 202 and the conveyance direction of the transported object (recording medium), position detection is performed by feeding back the angular error to the position detection unit 115. The accuracy of the result can be improved.

  In the present embodiment, the CIS as a so-called equal-magnification optical system is applied as the reading device 201. However, the present invention is not limited to this. For example, the reading device 201 may be a reading device of a so-called reduction optical system including a light source, a plurality of reflecting members (mirrors), an imaging lens, a linear image sensor, etc. If it is a device which can detect the position of, it is possible to improve position detection accuracy.

  In the present embodiment, the inclination of the entire reading device 201 is calculated from the coordinate positions in the sub-scanning direction obtained by reading the two horizontal lines corresponding to the sensor chip 210 at the end of the reading device 201. The present invention is not limited to this, and the inclination of the entire reading device 201 may be calculated from the coordinate position in the sub-scanning direction where horizontal lines corresponding to all the sensor chips 210 have been read, and correction values for all pixels may be calculated. .

Second Embodiment
Next, a second embodiment will be described.

  The second embodiment differs from the first embodiment in that a scanner unit used for MFP (Multifunction Peripheral / Printer / Product) or the like is applied as a modification of the medium position detection device 200. Hereinafter, in the description of the second embodiment, the description of the same parts as those of the first embodiment will be omitted, and the parts different from the first embodiment will be described.

  FIG. 17 is a perspective view showing the appearance of the reading device 400 according to the second embodiment. The reading device 400 is a modified example of the medium position detection device 200, and is a scanner unit used for an MFP or the like.

  As shown in FIG. 17, the reader 400 has a contact glass 410 disposed on the top surface. The contact glass 410 is formed in a substantially rectangular shape. The reading device 400 includes a reading device 201 (see FIG. 18) which moves in the reading device 400 in the sub scanning direction X and reads in a line shape in the main scanning direction Y. The reading device 201 reads an original placed on the contact glass 410.

  The reader 400 further has a slit 411. A glass 411 a is fitted into the slit 411. The reading device 201 can read the position reference member 202 (see FIG. 18) through the slit 411. Furthermore, a bridge 412 is formed between the contact glass 410 and the slit 411.

  In such a configuration, one short side of the contact glass 410 shown in FIG. 17 and one long side of the slit 411 are adjacent to each other with the bridge 412 interposed therebetween.

  FIG. 18 is a side view partially showing the internal structure of the reader 400. As shown in FIG. FIG. 18A shows a state in which the reading device 201 is located below the slit 411. Further, FIG. 18B shows a state in which the reading device 201 is located below the contact glass 410.

  An automatic document feeder (ADF) 420 is provided above the reading device 400. The ADF 420 is opened and closed when, for example, a document is placed on the contact glass 410. FIGS. 18A and 18B show the state where the ADF 420 is closed. As shown in FIGS. 18A and 18B, the ADF 420 is provided with a position reference member 202 on the bottom surface of the ADF 420 at a position facing the slit 411 with the ADF 420 closed.

  In FIG. 18A, the reading device 201 is located below the glass 411 a fitted in the slit 411. In FIG. 18A, the reading device 201 reads the position reference member 202 through the glass 411 a of the slit 411.

  In FIG. 18A, the position reference member 202 is a bottom surface of the ADF 420 and is formed at a position facing the slit 411 when the DF 420 is closed. However, the position reference member 202 does not have to be provided in the ADF 420, and the position reference member 202 may be provided in the slit 411 instead of the glass 411a.

  In FIG. 18B, the reading device 201 is located below the contact glass 410 and reads an original P placed on the contact glass 410. At this time, the reading device 201 reads the document P while moving in the sub scanning direction X.

  In such a configuration, even when the reading device 201 is attached obliquely to the position reference member 202, the same problem as described in the first embodiment occurs. The problem can be solved by the same method of the embodiment.

  In each of the above embodiments, the reading device and the image forming apparatus of the present invention have been described as an example applied to a printing system including an electrophotographic printing device, but the present invention is not limited to this. The present invention is also applicable to a printing system including the printing device of

  In each of the above embodiments, the reading device and the image forming apparatus of the present invention have been described as an example applied to a printing system including a printing apparatus such as a commercial printing machine (production printing machine). However, the present invention is limited thereto. The present invention is applicable to any image forming apparatus such as a multifunction peripheral having at least two functions of a copying function, a printer function, a scanner function, and a facsimile function, a copier, a printer, a scanner device, and a facsimile machine. Can.

  Furthermore, in each of the above embodiments, the reading device of the present invention has been described as an example applied to position detection in the image forming field, but the present invention is not limited thereto. For example, various fields such as inspection in FA field It is applicable to the position detection application of

  Moreover, the reader of this invention is applicable also to the banknote reader which discriminate | determines whether the banknote is printed in the correct position and shape for the purpose of discrimination | determination of a banknote and forgery prevention.

Reference Signs List 1 reading device, image forming apparatus 112 reference pattern detection unit 114 inclination correction value calculation unit 115 position detection unit 116 angular error setting unit 201 reading device 202 position reference member

JP, 2010-173069, A JP, 2008-28737, A

Claims (5)

A position reference member on which a reference pattern including a line extending in a predetermined direction is disposed and which is relatively moved in a direction orthogonal to the predetermined direction;
A reading device in which a plurality of pixels are arranged;
A reference pattern detection unit that detects the coordinate position of each pixel of the reading device in the orthogonal direction based on the reference pattern disposed on the position reference member;
Correction value calculation unit that calculates the first correction value in the orthogonal direction of at least the pixel used for position detection based on the coordinate position of the orthogonal direction of at least two of the pixels detected by the reference pattern detection unit When,
A position detection unit that detects an outer shape of the transported object and a position of an image pattern on the transported object from the data read by the reading device;
Second correction based on a difference between an image formed by correcting the shape based on the result of position detection using the first correction value by the position detection unit and an image formed without correcting the shape An angular error setting unit that sets a value,
Equipped with
The position detection unit performs position detection using the first correction value and the second correction value.
A reader characterized in that. The correction value calculation unit obtains the inclination of the reading device from the coordinate position of the at least two pixels in the orthogonal direction detected by the reference pattern detection unit, and the correction value is calculated based on the inclination of the reading device. calculate,
A reader according to claim 1, characterized in that. The print engine unit,
A transport control unit configured to control transport of the transported object to the print engine unit;
A reader according to claim 1 or 2;
An image forming apparatus comprising: A plurality of pixels correspond to the pixels of the reading device arranged in a predetermined direction, and include a line disposed in a position reference member relatively moved in a direction orthogonal to the predetermined direction and extending in the predetermined direction A reference pattern detection step of detecting a coordinate position of each pixel of the reading device in the orthogonal direction based on a reference pattern;
A correction value calculation process for calculating a first correction value in the orthogonal direction at least in a pixel used for position detection based on the coordinate direction of the orthogonal direction of at least two pixels detected in the reference pattern detection process When,
A position detection step of detecting the outer shape of the transported object and the position of the image pattern on the transported object from the data read by the reading device;
Second correction based on a difference between an image formed by correcting the shape based on the result of position detection using the first correction value and the image formed without correcting the shape. Angle error setting process to set the value,
Including
The position detection process performs position detection using the first correction value and the second correction value.
A position detection method characterized by A reference pattern including a line extending in a predetermined direction is disposed, and controls a reading device including a position reference member relatively moved in a direction orthogonal to the predetermined direction, and a reading device in which a plurality of pixels are arranged Computer,
A reference pattern detection unit that detects the coordinate position of each pixel of the reading device in the orthogonal direction based on the reference pattern disposed on the position reference member;
Correction value calculation unit that calculates the first correction value in the orthogonal direction of at least the pixel used for position detection based on the coordinate position of the orthogonal direction of at least two of the pixels detected by the reference pattern detection unit When,
A position detection unit that detects an outer shape of the transported object and a position of an image pattern on the transported object from the data read by the reading device;
Second correction based on a difference between an image formed by correcting the shape based on the result of position detection using the first correction value by the position detection unit and an image formed without correcting the shape An angular error setting unit that sets a value,
To act as
The position detection unit performs position detection using the first correction value and the second correction value.
Program for

Images