JP6409381B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  A technique for causing a scanner unit to read a document transported by a document transport unit is known. Japanese Patent Application Laid-Open No. 2004-133867 describes a technique for reading an entire original image without missing by reading the original with a maximum width that can be read by the original reading unit. Japanese Patent Application Laid-Open No. 2004-228688 describes a technique for reducing the amount of communication data by transmitting image data from which blank portions at both ends in the reading width direction of a document are deleted, in relation to a facsimile communication system.

JP 2007-194938 A Japanese Patent Application Laid-Open No. 11-069138

  An object of the present invention is to improve the accuracy of correcting the size of an image formed on a recording medium when a side of the recording medium is not detected from an image read from the conveyed recording medium.

According to one aspect of the present invention, the first mark provided at a distance determined from the first side of the recording medium, and the second mark provided at the distance from the second side facing the first side. Image forming means for forming a test image having a second mark on the recording medium, conveying means for conveying the recording medium, an original table on which the recording medium is placed, the conveyed recording medium and the original Reading means for reading an image from a recording medium placed on a table; and a first image read by the reading means from a recording medium placed on the document table and formed with the test image. A distance from one mark to the second mark, a distance from the first side of the recording medium to the first mark, a distance from the second side to the second mark, Directly on the first side and the second side The second image measured by the first method using the width of the recording medium in the direction to be read, and read by the reading means from the recording medium conveyed by the conveying means and formed with the test image In the method, the distance from the first mark to the second mark is directly measured, and the ratio of the distances measured by the first method and the second method is corrected. When the second image is read from the recording medium that is stored as a coefficient and transported by the transporting unit and formed with the test image, the first side or the second side of the recording medium Is not detected, the image shape is corrected by correcting the target size of the formed image in the image forming unit using a value obtained by multiplying the distance measured by the second method by the correction coefficient. In means, to provide an image forming apparatus and a correcting means for correcting the output size of the image formed on the new storage medium.
  In a preferred aspect, the reading unit reads images from both sides of the recording medium conveyed by the conveying unit, and the correcting unit is configured to read the first image and the second image read from the same side of the recording medium. The correction coefficient is calculated using an image.

According to the present invention , compared with the case where the size of the image formed on the recording medium is not corrected using the distance between the first mark and the second mark and the coefficient calculated from the second image. Thus, when the first side or the second side is not detected from the first image, it is possible to suppress a reduction in the accuracy of the image size correction .

Block diagram showing hardware configuration of image forming apparatus The figure which shows the test paper which is used in the correction function Block diagram showing the functional configuration of the image forming apparatus Flow chart showing correction coefficient calculation processing The figure which illustrates the 1st reading image The figure which illustrates the 2nd reading image Flow chart showing processing when correction function is executed The figure which illustrates the 1st reading image in which the edge part of a test paper is not included

  FIG. 1 is a block diagram illustrating a hardware configuration of the image forming apparatus 1. The image forming apparatus 1 is an information processing apparatus that functions as a copying machine, a printer, a scanner, and a facsimile. As shown in FIG. 1, the image forming apparatus 1 includes a control unit 101, a storage unit 102, an operation unit 103, a display unit 104, a conveyance unit 105, a document table 106, an image reading unit 107, The image forming unit 108, the communication unit 109, and the image processing unit 110 are provided. Each unit (excluding the document table 106) of the image forming apparatus 1 is connected to a bus 111, and various data is exchanged via the bus 111.

  The control unit 101 is a unit that controls the operation of each unit of the image forming apparatus 1. The control unit 101 includes an arithmetic processing device such as a CPU (Central Processing Unit) and a storage medium (main storage device) such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The CPU reads a program stored in the ROM and the storage unit 102, and executes the program using the RAM as a work area. By executing the program in this manner, the control unit 101 forms an image on a sheet (an example of a recording medium), reads an image from the sheet, generates image data, and another device via a communication line. To communicate with the network.

  The storage unit 102 is a means for storing data. The storage unit 102 includes a storage medium (auxiliary storage device) such as a hard disk or a flash memory, and stores data received by the communication unit 109, data generated by the image forming apparatus 1, and the like. In addition, the storage unit 102 may include a removable storage medium (removable medium) such as a so-called memory card or USB memory, and a unit for reading / writing data from / to the storage medium. The storage unit 102 stores a correction program described later.

  The operation unit 103 is a unit that receives a user operation. The operation unit 103 includes operation elements (buttons, keys, and the like), and supplies a control signal corresponding to the pressed operation element to the control unit 101. The operation unit 103 may include a display unit 104 and a sensor provided on the display surface of the display unit 104 so as to be configured by a touch panel that supplies a control signal corresponding to the pressed position to the control unit 101. Good.

  The display unit 104 is a means for displaying information. The display unit 104 includes, for example, a liquid crystal display as a display device. The display unit 104 displays a menu screen for operating the image forming apparatus 1 under the control of the control unit 101.

  The conveyance unit 105 is a unit that conveys a sheet to the image reading unit 107. The conveying unit 105 includes various rolls for conveying the sheets stacked on the sheet tray one by one to the area on the document table 106 where the sheets are read. The sheet conveyed by the conveying unit 105 is pressed against the document table 106. The document table 106 is a table on which a sheet on which an image is read by the image reading unit 107 is placed, for example, a platen glass.

  The image reading unit 107 is a unit that optically reads a sheet and converts it into image data. The image reading unit 107 reads a sheet conveyed by the conveyance unit 105 and pressed against the document table 106 or a sheet placed on the document table 106 and converts it into image data. The image reading unit 107 extends in the main scanning direction, and has a rod-like light source that irradiates light onto the surface of the sheet pressed on the document table 106 or the sheet placed on the document table 106, and the light irradiated on the sheet. An optical system that propagates the reflected light and forms an image, and an image sensor that photoelectrically converts the formed optical image. The image reading unit 107 supplies the image data read from the sheet to the image processing unit 110.

  The image forming unit 108 is a unit that forms an image on a sheet. The image forming unit 108 includes an image forming mechanism that forms a toner image on a sheet by electrophotography. The image forming mechanism is not limited to the electrophotographic method, and other recording methods such as an ink jet method may be used.

  The communication unit 109 is means for transmitting and receiving data. The communication unit 109 is connected to a communication line and functions as a communication interface that communicates with other devices connected to the communication line.

  The image processing unit 110 is a unit that performs image processing on image data. The image processing here is, for example, color correction or gradation correction. When the print function is executed in the image forming apparatus 1, the image processing unit 110 supplies the image data subjected to the image processing to the image forming unit 108.

  The size of the image formed on the paper by the image forming unit 108 (hereinafter referred to as “output size”) is different from the size of the image originally intended to be formed by the image forming apparatus 1 (hereinafter referred to as “target size”). There is a case. Therefore, the image forming apparatus 1 has a function of correcting the target size according to the output size (hereinafter referred to as “correction function”). When the correction function is executed, an image used for measuring the output size and correcting the target size (hereinafter referred to as “test image”) is formed on the sheet by the image forming unit 108. The user places a sheet on which a test image is formed (hereinafter referred to as “test sheet”) on a sheet tray and causes the image reading unit 107 to read the sheet. The image forming apparatus 1 measures an output size using an image read from a test sheet (hereinafter referred to as “read image”), and corrects the target size according to the measurement result. By correcting the target size, the output size of the image newly formed on the paper is corrected.

  FIG. 2 is a diagram showing a test sheet P1 used in the correction function. In FIG. 2, a QR code (registered trademark) C1 and eight test marks M (M1 to M8) are included in the test image I1. The QR code C1 indicates information used by the image forming apparatus 1 in the correction function. Specifically, in the QR code C1, information for identifying the QR code C1, information indicating the type of the test paper P1 such as the paper size and basis weight of the test paper P1, and the test image I1 are formed. Information indicating the current image forming conditions (for example, a correction value when processing for correcting the target size is performed) is included.

When the background of the read image is white, the position of the end portion of the test paper P1 tends to be difficult to be detected in the read image. The test mark M is a mark for detecting the position of the end of the test paper P1 in the read image. The test mark M1 is provided at a distance d1 from the short side L1 and the long side L4. The test mark M2 is provided at a distance d1 from the short side L1. Test mark M3 is provided at a distance d 1 from the short side L1 and the long side L2. The test mark M4 is provided at a distance d1 from the long side L2. The test mark M5 is provided at a distance d1 from the long side L2 and the short side L3. The test mark M6 is provided at a distance d1 from the short side L3. The test mark M7 is provided at a distance d1 from the short side L3 and the long side L4. The test mark M8 is provided at a distance d1 from the long side L4.

In the correction function, the image forming apparatus 1 uses the length in the width direction of the test image I1 formed on the sheet (the direction perpendicular to the direction in which the image reading unit 107 reads an image (in other words, the sub-scanning direction and the conveyance direction)). However, it correct | amends so that it may become a desired size. As the length in the width direction of the test image I1, the distance between the two test marks is used. Specifically, when the width direction of the test image I1 is the direction of the arrow A1, the distance between the test mark M4 and the test mark M8 is measured. When the width direction of the test image I1 is the direction of the arrow A2, the distance between the test mark M2 and the test mark M6 is measured as the length in the width direction of the test image I1. Hereinafter, the two test marks M used for measuring the length in the width direction of the test image I1 are expressed as “measurement target marks”. The measurement target mark is an example of a first mark and a second mark.

  In the correction function, there is a demand to accurately measure the distance between the measurement target marks in order to perform correction with high accuracy. As a method of measuring the distance between the measurement target marks, (A) a method of directly measuring the distance between the measurement target marks (hereinafter referred to as “method A”), and (B) a side adjacent to the measurement target mark. There are two methods: a method of indirectly measuring the distance between measurement target marks using the distance (hereinafter referred to as “method B”). According to the method A, there is an advantage that the distance between the measurement target marks is measured even when the edge of the test paper P1 is not detected in the read image. On the other hand, there is a drawback that the accuracy of measurement is low compared to the case of using Method B described later.

ここで、ｄＰはテスト用紙Ｐ１の幅方向の長さを示す。長さｄＰは、ＱＲコードＣ１により示される。ｄ１Ａは測定対象マークの一方とテスト用紙Ｐ１の端部（当該一方の測定対象マークに近接する辺Ｌ）との距離を、ｄ１Ｂは測定対象マークの他方とテスト用紙Ｐ１の端部（当該他方の測定対象マークに近接する辺Ｌ）との距離を示す。例えば、測定対象マークがテストマークＭ４およびテストマークＭ８である場合、距離ｄ１ＡはテストマークＭ４と長辺Ｌ２との距離を示し、距離ｄ１ＢはテストマークＭ８と長辺Ｌ４との距離を示す。別の例で、測定対象マークがテストマークＭ２およびテストマークＭ６である場合、距離ｄ１ＡはテストマークＭ２と短辺Ｌ１との距離を示し、距離ｄ１ＢはテストマークＭ６と短辺Ｌ３との距離を示す。 Next, details of the method B will be described. In the method B, the distance between the measurement target marks (length in the width direction of the test image I1) dW is calculated by the following equation (1).

Here, dP indicates the length in the width direction of the test paper P1. The length dP is indicated by the QR code C1. d1A is the distance between one of the measurement target marks and the end of the test paper P1 (side L close to the one measurement target mark), and d1B is the other of the measurement target marks and the end of the test paper P1 (the other The distance to the side L) close to the measurement target mark is shown. For example, when the measurement target marks are the test mark M4 and the test mark M8, the distance d1A indicates the distance between the test mark M4 and the long side L2, and the distance d1B indicates the distance between the test mark M8 and the long side L4. In another example, when the measurement target marks are the test mark M2 and the test mark M6, the distance d1A indicates the distance between the test mark M2 and the short side L1, and the distance d1B indicates the distance between the test mark M6 and the short side L3. Show.

  When the image forming apparatus 1 measures the distance between two points in the read image, the error may increase as the measured distance increases. This is due to the following reasons, for example. There may be an upper limit for the distance that the image forming apparatus 1 can measure at a time. In this case, when the distance between the two points exceeds the upper limit value, the image forming apparatus 1 divides the two points into a plurality of sections, measures the distance of each section, and adds the measurement results of each section. To measure the distance between the two points. Thus, when a plurality of measurements are performed in the measurement of the distance between two points, the error included in each measurement is accumulated when the measurement results are added. Therefore, in the measurement of the distance between two points in the read image, the error increases as the distance between the two points increases. As shown in FIG. 2, the distance d1A and the distance d1B are shorter than the distance dW regardless of whether the width direction of the test image I1 is the arrow A1 or the arrow A2, and the distance d1A and the distance d1B are measured. Is higher than the measurement accuracy when the distance between the measurement target marks is directly measured (method A). Therefore, according to the method B, there is an advantage that the measurement accuracy is higher than that when the method A is used. On the other hand, the method B cannot be used when the end of the test paper P1 is not detected in the read image.

  When the test paper P1 is placed on the paper tray and read by the image reading unit 107, the read image may not include the end of the test paper P1. For example, when the image reading unit 107 reads the maximum width test sheet P1 from which the image reading unit 107 can read image data, the end portion in the width direction of the test sheet P1 may not be included in the read image. is there. In this case, the distance between the measurement target marks cannot be measured by the method B described above. In the image forming apparatus 1 according to the present invention, even when the method B cannot be used (when the method A is used), the size of the image formed on the paper is compensated for the disadvantage of the method A. This prevents the accuracy of the correction from being reduced. Specifically, before the correction function is executed, the image forming apparatus 1 measures the distance dW by both the method A and the method B, and calculates a coefficient that represents the ratio of the two measured distances dW. The image forming apparatus 1 uses the calculated coefficient to correct the measurement value when the method A is used in the correction function. Hereinafter, a coefficient used for correcting the measurement value by the method A is expressed as “correction coefficient”.

  FIG. 3 is a block diagram illustrating a functional configuration of the image forming apparatus 1. The image forming apparatus 1 includes an image forming unit 11, a conveying unit 12, a reading unit 13, a detecting unit 14, a correcting unit 15, and a calculating unit 16. The image forming unit 11 forms a test image I1 on a sheet. The transport unit 12 transports the test paper P1 to the reading unit 13. The reading unit 13 reads an image from the test paper P1. The reading unit 13 reads an image from the test paper P1 conveyed by the conveyance unit 12 and the test paper P1 placed on the document table 106. The detection unit 14 detects an end portion of the test paper P <b> 1 with respect to an image read from the test paper P <b> 1 conveyed by the conveyance unit 12 (hereinafter referred to as “first read image”). The correction unit 15 corrects the size of the image formed on the paper using the first read image. The calculating means 16 calculates a correction coefficient using the first read image and an image read from the test paper P1 placed on the document table 106 (hereinafter referred to as “second read image”).

  In the image forming apparatus 1, the image forming unit 108 controlled by the control unit 101 executing a correction program for realizing a correction function is an example of the image forming unit 11. The transport unit 105 controlled by the control unit 101 executing the correction program is an example of the transport unit 12. The image reading unit 107 controlled by the control unit 101 executing the correction program is an example of the reading unit 13. The control unit 101 executing the correction program is an example of the detection unit 14 and the calculation unit 16. The image processing unit 110 controlled by the control unit 101 executing the correction program is an example of the correction unit 15.

  FIG. 4 is a flowchart showing a process (hereinafter referred to as “correction coefficient calculation process”) in which the image forming apparatus 1 calculates a correction coefficient as a stage before the correction function is executed. Note that the correction coefficient calculation process may be performed at least once before the correction function is first executed in the image forming apparatus 1. The following processing is started when the user outputs the test paper P1 from the image forming apparatus 1 in advance and places the test paper P1 on the paper tray. The output of the test paper P1 is performed, for example, when the user operates the operation unit 103 to input an instruction for forming the test image I1. The user places the output test paper P1 on the paper tray.

  In step SA1, the control unit 101 reads an image from the test paper P1 stacked on the paper tray. The reading of the test paper P1 is performed, for example, when the user operates the operation unit 103 to input an instruction for starting the reading of the test paper P1 (hereinafter referred to as “reading start instruction”). When a reading start instruction is input, the conveyance unit 105 conveys the test paper P1 toward the image reading unit 107, and the image reading unit 107 reads an image from the test paper P1. The control unit 101 stores image data indicating the first read image in the storage unit 102.

  FIG. 5 is a diagram illustrating the first read image. In this example, the first read image I21 is a read image when the test paper P1 shown in FIG. 2 is read with the direction of the arrow A1 as the width direction. In the example of FIG. 5, the first read image I21 includes the end of the test paper P1. Note that the first read image I21 shown in FIG. 5 includes the end portion of the test paper P1, but if the test mark M is included, the end portion of the test paper P1 is included in the first read image. It does not have to be.

  Refer to FIG. 4 again. In step SA2, the control unit 101 detects the orientation of the test paper P1 in the first read image. In addition to the test mark M described above, the test image I1 includes a mark (not shown) (hereinafter referred to as “direction detection”) used to detect the orientation of the test paper P1, the position of the test mark M, and the position of the QR code C1. ")"). The direction detection marks are a plurality of marks having different shapes, and are provided so as to correspond to the respective sides constituting the end portion of the test paper P1. The direction detection mark is also provided at a predetermined position with respect to the test mark M. The control unit 101 detects the direction of the test sheet in the first read image by detecting the position of the direction detection mark in the first read image. For example, in the first read image I21 shown in FIG. 5, it is detected that the short side L1 and the short side L3 are along the width direction as the direction of the test paper P1. The control unit 101 stores the detected position of the direction detection mark and the orientation of the test sheet in the RAM. In step SA2, the control unit 101 stores an identifier for identifying a direction detection mark corresponding to a side along the width direction of the test paper P1 in the RAM. The storage of the identifier is performed in order to specify the length dP in the process (step SA12) described later.

  In step SA3, the control unit 101 detects the position of the test mark M in the first read image. Specifically, the control unit 101 detects the position of the test mark M by searching for a predetermined position with respect to the position of the direction detection mark stored in the RAM. The control unit 101 stores the detected position of the test mark M in the RAM.

  In step SA4, the control unit 101 detects a measurement target mark in the first read image. Specifically, the control unit 101 divides the test mark M1 to the test mark M8 into three mark groups along the width direction of the test paper P1, and sets the other two mark groups among the three mark groups. A test mark M belonging to one sandwiched mark group is detected as a measurement target mark. In the first read image I21 shown in FIG. 5, a mark group consisting of test marks M1, M2, and M3 (hereinafter referred to as “mark group G1”) and a mark group including test marks M4 and M8 (hereinafter referred to as “ Mark group G2 ") and a mark group consisting of test marks M5, M6 and M7 (hereinafter referred to as" mark group G3 "). Then, test marks M4 and M8 belonging to the mark group G2 sandwiched between the mark group G1 and the mark group G3 are detected as measurement target marks. The control unit 101 stores the position of the measurement target mark in the RAM separately from the positions of other test marks M. The control unit 101 also stores in the RAM information indicating the relative positional relationship between the position of the direction detection mark detected in step SA2 and the position of the measurement target mark (hereinafter referred to as “relative position information”). .

  In step SA5, the control unit 101 uses the method A described above to measure the distance dW from the first read image. Specifically, the control unit 101 reads the position of the measurement target mark from the RAM and measures the distance dW. Hereinafter, the distance dW measured from the first read image is expressed as “distance dW1”. For example, in the first read image I21 shown in FIG. 5, the distance dW1 is measured by directly measuring the distance between the test mark M4 and the test mark M8. The control unit 101 stores the measured distance dW1 in the RAM.

  In step SA6, the control unit 101 reads an image from the test paper P1 placed on the document table 106. The processing in step SA6 is started when the user inputs a reading start instruction in a state where the test paper P1 on which the image has been read in step SA1 is placed on the document table 106. When the test paper P1 is placed on the document table 106, a paper (hereinafter referred to as “background paper”) serving as the background of the test image I1 is set so as to overlap the test paper P1. The control unit 101 stores image data indicating the second read image in the storage unit 102.

  FIG. 6 is a diagram illustrating a second read image. In this example, the second read image I22 is a read image read from the test paper P1 shown in FIG. In the second read image I22, the shaded area indicates an area read from the background paper. In the process (step SA12) described later, the control unit 101 uses the method B described above to measure the distance dW from the second read image. Therefore, the control unit 101 reads an image with a predetermined size (for example, the maximum size) so that the end portion of the test paper P1 is included in the second read image.

  Refer to FIG. 4 again. In step SA7, the control unit 101 detects the position of the QR code C1 in the second read image. For example, the QR code C1 is provided at a predetermined position with respect to the direction detection mark described above. The control unit 101 detects the position of the direction detection mark in the second read image, and searches for a predetermined position with respect to the detected position of the direction detection mark, whereby the QR in the second read image is detected. The position of the code C1 is detected. The control unit 101 overwrites the position of the detected direction detection mark with the position of the direction detection mark stored in the RAM in step SA2. The control unit 101 also stores the detected position of the QR code C1 in the RAM.

  In step SA8, the control unit 101 acquires information indicating the paper size of the test paper P1 (hereinafter referred to as “paper size information”). Specifically, the control unit 101 acquires paper size information by decoding the QR code C1 whose position is detected in step SA7. The paper size information indicates the short side length and the long side length of the test paper P1. The short side length and the long side length indicated by the paper size information are distinguished by an identifier for identifying the short side and the direction detection mark corresponding to the long side. The control unit 101 stores the acquired paper size information in the RAM.

  In step SA9, the control unit 101 detects the position of the test mark M in the second read image. Specifically, the control unit 101 detects the position of the test mark M by searching for a predetermined position with respect to the position of the direction detection mark stored in the RAM. The control unit 101 overwrites the position of the detected test mark M with the position of the test mark M stored in the RAM in step SA3.

  In step SA10, the control unit 101 detects the position of the edge of the test paper P1 in the second read image. Specifically, the control unit 101 detects the position of the end portion of the test paper P1 using the position of the test mark M in the second read image stored in the RAM. The control unit 101 stores the detected position of the end of the test paper P1 in the RAM.

  In step SA11, the control unit 101 detects a measurement target mark in the second read image. Specifically, the control unit 101 uses the information indicating the position of the direction detection mark in the second read image and the relative position information read from the RAM, and used as the test mark as the measurement target mark in step SA4. Are detected as measurement target marks in the second read image. The control unit 101 stores the position of the measurement target mark in the RAM separately from the positions of other test marks M.

  In step SA12, the control unit 101 uses the method B described above to measure the distance dW from the second read image. Specifically, the control unit 101 measures the distance between each of the measurement target marks detected in step SA11 and the end of the test paper P1 (side closest to each of the measurement target marks). The distance d1A and the distance d1B are measured. For example, in the second read image I22 shown in FIG. 6, the distance between the test mark M4 and the long side L2 is measured as the distance d1A, and the distance between the test mark M8 and the long side L4 is measured as the distance d1B. The control unit 101 also follows the width direction when the test paper P1 is read in step SA1 out of the short side length and the long side length of the test paper P1 indicated by the paper size information stored in the RAM. The length of the other side is read as the length dP. The length of one side along the width direction is identified by the identifier stored in the RAM in step SA2. For example, when the test paper P1 is read with the direction of the arrow A1 (see FIGS. 2 and 5) as the width direction, the length of the short side of the test paper P1 is read as the length dP. The control unit 101 measures the distance dW according to equation (1) using the measured distance d1A and distance d1B and the length dP read from the RAM. Hereinafter, the distance dW measured from the second read image is expressed as “distance dW2”. The control unit 101 stores the measured distance dW2 in the RAM.

In step SA13, the control unit 101 calculates a correction coefficient. Specifically, the control unit 101 reads the distance dW1 and the distance dW2 from the RAM, and calculates the correction coefficient α by the following equation (2). The control unit 101 stores the calculated correction coefficient α in the storage unit 102.

  FIG. 7 is a flowchart illustrating processing when the correction function is executed in the image forming apparatus 1. The following process is started in a state where the process shown in FIG. 4 is executed and the correction coefficient α is stored in the storage unit 102. Similarly to FIG. 4, the following processing is started in a state where the user outputs the test paper P1 from the image forming apparatus 1 in advance and places the test paper P1 on the paper tray. Note that the test paper P1 used in the process shown in FIG. 7 may be different from the test paper P1 used in the correction coefficient calculation process. For example, in the process shown in FIG. 7, a test paper P1 having a paper size different from the test paper P1 used in the correction coefficient calculation process may be used.

  In step SB1 and step SB2, control unit 101 performs the same processing as in step SA1 and step SA2. In Step SB3 and Step SB4, the control unit 101 performs the same processing as Step SA7 and Step SA8 on the first read image read in Step SB1. In step SB5 and step SB6, control unit 101 performs the same processing as in steps SA3 and SA4.

  In step SB7, the control unit 101 performs the same process as in step SA10 on the first read image read in step SB1. In step SB8, the control unit 101 determines whether or not two sides constituting the end of the test paper P1 in the reading width direction are detected in the first read image. Specifically, the control unit 101 determines whether or not the two sides have been detected based on whether or not the positions of the two sides that constitute the end portion in the width direction of the test paper P1 are stored in the RAM. To do. When it is determined that two sides have been detected (SB8: YES), the control unit 101 shifts the processing to step SB9. If it is determined that there is an undetected side of the two sides (SB8: NO), the control unit 101 shifts the process to step SB10.

  FIG. 8 is a diagram illustrating a first read image that does not include the edge of the test sheet. In this example, the first read image I23 is a read image when the test paper P1 is read with the direction of the arrow A3 as the width direction. In the first read image I23, the end of the first read image I23 and the side L2 of the test paper P1 overlap. In this case, the position of the side L2 is not detected in step SB7 described above, and it is determined that there is a side not detected in step SB8.

  In step SB9, the control unit 101 uses the method B to measure the distance dW1 from the first read image. Specifically, the control unit 101 measures the distance dW1 by performing the same process as in step SA12 on the first read image read in step SB1. In step SB10, the control unit 101 uses method A to measure the distance dW1 from the first read image. For example, in the first read image I23 shown in FIG. 8, the distance dW1 is measured by directly measuring the distance between the test mark M4 and the test mark M8.

距離ｄＷ１に補正係数αが乗じられることにより、方法Ａを利用して測定された距離ｄＷ１が補正される。制御部１０１は、算出された距離ｄＷｒをＲＡＭに記憶する。 In step SB11, the control unit 101 corrects the distance dW1 measured using the method A using the correction coefficient α. Specifically, the corrected distance dWr is calculated by the following equation (3).

By multiplying the distance dW1 by the correction coefficient α, the distance dW1 measured using the method A is corrected. The control unit 101 stores the calculated distance dWr in the RAM.

  In step SB12, the control unit 101 calculates a correction value for correcting the target size. The control unit 101 calculates a correction value by a predetermined process using the distance dW1 measured in step SB9 or the distance dWr calculated in step SB11. The control unit 101 corrects the target size based on the calculated correction value.

  With the above processing, even when the edge of the test paper P1 is not detected from the read image in the correction function and the distance between the measurement target marks is measured using the method A, the measurement value is corrected by the correction coefficient. It is corrected by α. Accordingly, it is possible to prevent the accuracy of the correction of the size of the image formed on the paper from being lowered due to the low accuracy of the distance measurement between the measurement target marks.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. Hereinafter, some modifications will be described. Two or more of the modifications described below may be used in combination.

  The hardware configuration of the image forming apparatus 1 is not limited to the configuration shown in FIG. For example, the image reading unit 107 may include a mechanism for reading images from both sides of the sheet conveyed by the conveying unit 105. Specifically, the image reading unit 107 may include two line sensors, one line sensor may read one side of the paper, and the other line sensor may read the other side of the paper. Further, the image forming unit 108 may form test images on both sides of the paper. When the images are read from both sides of the test sheet on which the test images are formed on both sides, the control unit 101 uses the first read image and the second read image read from the same side of the test sheet to correct the correction coefficient α. Is calculated.

  The processing executed in the correction coefficient calculation processing and the correction function is not limited to the above processing. For example, in step SA10, the control unit 101 may detect the position of the end of the test paper P1 using the change in brightness of the second read image without using the position of the test mark M. Further, the position of the QR code and the position of the test mark may be detected by a method different from the method described in the embodiment.

  The test image is not limited to the image described in the embodiment. For example, in place of the QR code C1, other code images such as PDF417, CP (Communication Platform) code, HCCB (High Capacity Color Barcode) may be used. The test marks M may have different shapes. Further, the number of test marks M included in the test image is not limited to eight.

The length that the image forming apparatus 1 acquires as the output size in the correction function is not limited to the length in the width direction of the test image I1. The image forming apparatus 1 may acquire the length of the test image I1 in the length direction (the direction in which the image reading unit 107 reads an image; in other words, the sub-scanning direction and the conveyance direction ) as the output size. Also in this case, by performing the same processing as the processing shown in FIGS. 4 and 7 for the length in the length direction of the test image I1, the measured value of the length is corrected and formed on the sheet. The accuracy of image size correction is improved.

  In the embodiment, the correction program executed by the image forming apparatus 1 includes a magnetic storage medium (magnetic tape, magnetic disk (HDD, FD (Flexible Disk)), etc.), an optical storage medium (optical disk (CD (Compact Disk), DVD)). (Digital Versatile Disk))), a magneto-optical storage medium, a semiconductor memory (flash ROM, etc.), and the like may be stored in a computer-readable storage medium. The program may be downloaded via a network such as the Internet.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 101 ... Control part, 102 ... Memory | storage part, 103 ... Operation part, 104 ... Display part, 105 ... Conveyance part, 106 ... Document stand, 107 ... Image reading part, 108 ... Image forming part, 109 ... Communication unit 110 Image processing unit 11 Image forming unit 12 Transport unit 13 Reading unit 14 Detection unit 15 Correction unit 16 Calculation unit

Claims (2)

A test image having a first mark provided at a distance determined from the first side of the recording medium, and a second mark provided at the distance from a second side opposite to the first side Image forming means for forming the image on the recording medium;
Conveying means for conveying the recording medium;
An original table on which the recording medium is placed ;
Reading means for reading an image from the conveyed recording medium and the recording medium placed on the platen;
The distance from the first mark to the second mark in the first image read by the reading means from the recording medium placed on the platen and having the test image formed thereon is defined as the recording distance. A distance from the first side of the medium to the first mark, a distance from the second side to the second mark, and a direction orthogonal to the first side and the second side. In the second image measured by the first method using the width of the recording medium, conveyed by the conveying means, and read by the reading means from the recording medium on which the test image is formed, The distance from the first mark to the second mark is measured by the second method, and the ratio of the distances measured by the first method and the second method is stored as a correction coefficient. Aside, transported by the transport means When the second image is read from the recording medium on which the test image is formed and the first side or the second side of the recording medium is not detected, the second method By correcting the target size of the formed image in the image forming unit using the value obtained by multiplying the distance measured in step 1 by the correction coefficient, the image forming unit allows the image to be newly formed on the storage medium. An image forming apparatus comprising: a correction unit that corrects an output size . The reading unit reads images from both sides of the recording medium conveyed by the conveying unit;
It said correction means, the image formation according to claim 1, characterized in that to calculate the correction factor by using the first image read from the same plane and said second image of said recording medium apparatus.

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