Patent Publication Number: US-2017355544-A1

Title: Conveyance detection apparatus, conveying apparatus, and recording apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-117866, filed on Jun. 14, 2016, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a conveyance detection apparatus, a conveying apparatus, and a recording apparatus. 
     Description of the Related Art 
     There is a known recording apparatus that conveys a recording medium while controlling an amount of conveyance and that records an image on the recording medium. A recording apparatus disclosed in Patent Document 1 conveys a test chart in advance and calculates a difference between actual position information of a mark actually detected by a two-dimensional sensor when a conveyor roller makes one revolution and theoretical position information of the mark ideally detected by the two-dimensional sensor. The recording apparatus controls an amount of conveyance of the conveyor roller by calculating a corrected amount of feed of each mark from an actual amount of feed of each mark obtained by the two-dimensional sensor detecting the mark based on the calculated difference. 
     However, a process of conveying the test chart in advance is necessary in the recording apparatus of Japanese Laid-open Patent Publication No. 2011-131399, and this is cumbersome. Furthermore, vibration at the conveyance of the test chart is transmitted to a recording medium in the recording apparatus of Patent Document 1. Therefore, the two-dimensional sensor detects a position of the test chart displaced by the vibration and detects an amount of conveyance different from the amount of conveyance of the test chart actually conveyed. It is difficult to detect an amount of conveyance with an excellent accuracy. 
     Patent Document 1 
     
         
         Japanese Laid-Open Patent Publication No. 2011-131399 
       
    
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the problems, and an object of the present invention is to enable detecting highly accurate conveyance information. 
     The present invention provides a conveyance detection apparatus of a conveying apparatus, the conveying apparatus including: a conveying unit that conveys a conveyed object along a conveyance path; and an imaging unit that images the conveyed object and an object not conveyed by the conveying unit, the conveyance detection apparatus including a conveyance detection unit that acquires actual conveyance information of the conveyed object from image information of the conveyed object imaged by the imaging unit and image information of the object imaged by the imaging unit. 
     The present invention provides a conveying apparatus including: a conveying unit that conveys a conveyed object along a conveyance path; an imaging unit that images the conveyed object and an object not conveyed by the conveying unit; a conveyance detection unit that acquires actual conveyance information of the conveyed object from image information of the conveyed object imaged by the imaging unit and image information of the object imaged by the imaging unit; and a housing that houses the conveying unit, the imaging unit, and the object. 
     The present invention provides a recording apparatus including: a conveying unit that conveys a conveyed object along a conveyance path; an imaging unit that images the conveyed object and an object not conveyed by the conveying unit; a conveyance detection unit that acquires actual conveyance information of the conveyed object from image information of the conveyed object imaged by the imaging unit and image information of the object imaged by the imaging unit; and a recording unit that records an image on the conveyed object based on conveyance information detected by the conveyance detection unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a schematic configuration of a recording apparatus  100 ; 
         FIG. 2  is a view illustrating a configuration of part of a conveying unit  10  as viewed from an imaging unit  30 ; 
         FIG. 3  is a block diagram illustrating an internal configuration of the recording apparatus  100 ; 
         FIG. 4  is a flow chart illustrating a process by a control unit  50 ; 
         FIG. 5  is a flow chart illustrating a process by the control unit  50 ; 
         FIG. 6  is a view illustrating an example of first image data  60  imaged by the imaging unit  30 ; and 
         FIG. 7  is a view illustrating an example of second image data  70  imaged by the imaging unit  30 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will now be described in detail with reference to the drawings. 
     The present embodiment provides a conveyance detection apparatus and a conveying apparatus or a recording apparatus including the conveyance detection apparatus. The conveyance detection apparatus detects conveyance information of a conveyed object. The conveying apparatus conveys the conveyed object based on the conveyance information of the conveyed object detected by the conveyance detection apparatus. The recording apparatus forms an image on the conveyed object, specifically, recording paper, detected by the conveyance detection apparatus based on the conveyance information of the recording paper and records the image. 
     In the following drawings, a conveyance direction of the conveyed object will be expressed as an X direction, a direction orthogonal to the X direction and parallel to a conveyed surface will be expressed as a Y direction, and a direction orthogonal to the conveyed surface will be expressed as a Z direction, as necessary. The side of a paper feeding opening  14  described later in the conveyance direction will be called an upstream, and the side of a paper discharge opening  15  described later will be called a downstream. 
     First Embodiment 
     A recording apparatus  100  according to the present embodiment is applied to an inkjet type printer in the following description. 
       FIG. 1  is a view illustrating a schematic configuration of the recording apparatus  100 . 
     The recording apparatus  100  includes a conveying apparatus  10 , a recording unit  40 , and a control unit  50  that controls operation of the conveying apparatus  10  and the recording unit  40 . 
     The conveying apparatus  10  conveys a recording medium (hereinafter, called recording paper P) as a fed conveyed object along a conveyance path and discharges the recording medium after the recording medium passes through the recording unit  40 . The conveying apparatus  10  includes a housing  11 , a conveying unit  20 , and an imaging unit  30 . 
     The housing  11  houses and supports constituent members of the recording apparatus  100 . The housing  11  includes a conveyance support portion  12  that supports the conveying unit  20  and an imaging support portion  13  that supports the imaging unit  30 . The housing  11  also includes the paper feeding opening  14  for feeding the recording paper P and the paper discharge opening  15  for discharging the recording paper P. The housing  11  also includes an imaging reference portion described later. 
     The conveying unit  20  conveys the recording paper P. The conveying unit  20  includes a first conveyor roller unit  21  and a second conveyor roller unit  22  as rotating bodies, a conveyor motor  23 , a paper feeding roller unit  24 , a paper feeding motor  25 , and an encoder  26 . 
     The first conveyor roller unit  21  includes a pair of rollers  21   a  and  21   b  and conveys the recording paper P placed between the rollers  21   a  and  21   b . Similarly, the second conveyor roller unit  22  includes a pair of rollers  22   a  and  22   b  and conveys the recording paper P placed between the rollers  22   a  and  22   b . The first conveyor roller unit  21  and the second conveyor roller unit  22  are rotatably supported by the conveyance support portion  12  of the housing  11  at positions separated in the conveyance direction. Therefore, a conveyance path of the recording paper P is formed between the pair of rollers  21   a  and  21   b  and between the pair of rollers  22   a  and  22   b  (the recording paper P and the conveyance path overlap in  FIG. 1 ). The conveyor motor  23  rotates the first conveyor roller unit  21  and the second conveyor roller unit  22 . Therefore, the drive of the conveyor motor  23  conveys the recording paper P placed between the pair of rollers  21   a  and  21   b  and the pair of rollers  22   a  and  22   b  in the conveyance direction (arrow F illustrated in  FIG. 1 ). The paper feeding roller unit  24  includes a pair of rollers  24   a  and  24   b  and places the recording paper P between the rollers  24   a  and  24   b . The paper feeding roller unit  24  separates each of a plurality of pieces of recording paper P loaded on a tray and feeds the recording paper P from the paper feeding opening  14 . The paper feeding motor  25  rotates the paper feeding roller unit  24 . Therefore, the paper feeding motor  25  rotates to feed the recording paper P placed between the pair of rollers  24   a  and  24   b  from the paper feeding opening  14 . The encoder  26  detects a rotation state by reading a slit along a circumference of a code wheel not illustrated of the first conveyor roller unit  21  and transmits the detected information to the control unit  50 . 
     The conveying unit  20  may be configured to bring the recording paper P into close contact with a conveyor belt to convey the recording paper P instead of conveying the recording paper P by the pairs of rollers. 
     The imaging unit  30  two-dimensionally images the surface of the recording paper P being conveyed by the conveying unit  20 . More specifically, the imaging unit  30  is supported by the imaging support portion  13  of the housing  11  such that a direction orthogonal to the surface of the recording paper P is an imaging direction. The imaging unit  30  can include a lens and an image sensor including an image pickup element. The imaging unit  30  is arranged on the upstream of the recording unit  40  in the conveyance direction, and the imaging unit  30  images the surface of the recording paper P before the image is recorded by the recording unit  40 . The imaging unit  30  transmits the taken image information to the control unit  50 . 
     In addition to the recording paper P being conveyed, an imaging range of the imaging unit  30  of the present embodiment includes an object other than the recording paper P. 
       FIG. 2  is a view illustrating a configuration of part of the conveying apparatus  10  as viewed from the imaging unit  30 , and an imaging range R of the imaging unit  30  is indicated. The imaging range R includes the recording paper P conveyed along the conveyance path and the object other than the recording paper P, that is, an object not conveyed by the conveying unit  20 . The object not conveyed by the conveying unit  20  is, for example, the housing  11 , and members integrated and coupled to the housing  11  are also included. Therefore, the imaging range R is set such that the imaging unit  30  can simultaneously image the recording paper P that moves in the conveyance direction along with the conveyance of the conveying unit  20  and the housing  11  that does not move in the conveyance direction. The imaging range R can include, for example, 1024 pixels×1024 pixels. Assuming that a pitch of one pixel is, for example, 10 μm here, the imaging range R is 10.24 mm×10.24 mm. The imaging range R can be set to a size according to an amount of conveyance. 
     Meanwhile, the housing  11  includes a reference member  16  as an imaging reference portion in the imaging range R. The reference member  16  is a pin-like member or a rod-like member and is supported by the conveyance support portion  12  of the housing  11 . The reference member  16  protrudes toward the imaging unit  30  from the conveyance support portion  12 . Therefore, the imaging unit  30  images a tip of the reference member  16 . Here, a distance from the imaging unit  30  to the recording paper P conveyed in the conveyance path and a distance from the imaging unit  30  to the reference member  16  are set to substantially the same distance. The reference member  16  can be, for example, a pin with a diameter of about 20 pixels. Assuming that the pitch of one pixel is, for example, 10 μm here, the diameter of the reference member  16  is 0.2 mm. 
     The recording unit  40  records an image or the like on the surface of the conveyed recording paper P. The recording unit  40  is arranged on the downstream of the imaging unit  30  in the conveyance direction and is configured to record the image on the recording paper P after the image is taken by the imaging unit  30 . The recording unit  40  includes a carriage  41 , a recording head  42 , an ink tank  43 , and a carriage moving motor  44 . The carriage  41  is driven by the carriage moving motor  44  to move back and forth in the direction orthogonal to the conveyance direction of the recording paper P and parallel to the surface of the recording paper P, that is, in the Y direction. The recording head  42  discharges ink from a nozzle toward the surface of the recording paper P in conjunction with the backward and forward movement of the carriage  41 . The ink tank  43  supplies stored ink to the recording head  42 . The carriage moving motor  44  moves the carriage  41  back and forth through a belt  45 . 
     The recording unit  40  is not limited to the inkjet type, and an electrophotographic type, a thermal transfer type, a dot impact type or the like may also be adopted. 
     The control unit  50  controls the conveying apparatus  10  and the recording unit  40 . Specifically, the control unit  50  alternately repeats instructing the conveying apparatus  10  to convey the recording paper P with an amount of conveyance for one step and instructing the recording unit  40  to discharge the ink from the nozzle of the recording head  42  to record an image for one step. Therefore, a process by the conveying apparatus  10  conveying the recording paper P for one step and a process by the recording unit  40  recording an image for one step are repeated in the recording apparatus  100  to record a desired image on the entire surface of the recording paper P. 
       FIG. 3  is a block diagram illustrating an internal configuration of the recording apparatus  100  with a focus on the control unit  50 . 
     The control unit  50  includes a CPU  51 , a ROM  52 , and a RAM  53  and functions as a so-called computer. 
     The CPU  51  expands a program stored in the ROM  52  to the RAM  53  and executes the program to control the entire recording apparatus  100 . The program and data necessary for a process by the CPU  51  are stored in the ROM  52 . The RAM  53  is a memory that temporarily stores information when the CPU  51  executes the process. 
     The control unit  50  is connected to the imaging unit  30 , the encoder  26 , an operation unit  54 , and an information processing apparatus  110  and is configured to receive information from them. A user operates the operation unit  54  to issue an instruction to the control unit  50 . Examples of the operation unit  54  include a switch, a button, and a touch panel. Examples of the information processing apparatus  110  include a PC, a smartphone, and a tablet terminal, and the information processing apparatus  110  is connected in a wireless or wired manner through an interface unit  55 . 
     The control unit  50  is connected to the conveyor motor  23 , the paper feeding motor  25 , the carriage moving motor  44 , and the recording head  42  through motor drivers  56 ,  57 , and  58  and a head driver  59 , respectively, and is configured to transmit information to them. 
     In the recording apparatus  100  configured as described above, the imaging unit  30  images, at different timings, the recording paper P being conveyed and transmits the taken image information to the control unit  50 . Based on two pieces of image information taken at different timings, the control unit  50  uses pattern matching to detect actual conveyance information of the recording paper P, specifically, a distance conveyed in the X direction and a distance conveyed in the Y direction (distance displaced in the Y direction). Therefore, the control unit  50  functions as a conveyance detection apparatus that detects conveyance information. The control unit  50  also controls the recording head  42  to discharge the ink according to the detected actual conveyance information. Therefore, the recording unit  40  can record an image without a break and without an overlap. 
     However, the conveyor motor  23  of the conveying unit  20  is configured to rotate the first conveyor roller unit  21  and the like to convey the recording paper P in the recording apparatus  100 , and vibration of the conveyor motor  23  and vibration during the rotation of the first conveyor roller unit  21  are transmitted to the recording paper P. The vibration assumed here has a frequency of 30 Hz, a width of 40 μm, and an amplitude of 20 μm, for example. 
     Furthermore, the conveyance support portion  12  that supports the conveying unit  20  and the imaging support portion  13  that supports the imaging unit  30  are different in the recording apparatus  100 . Therefore, the vibration from the conveying unit  20  is transmitted to the imaging unit  30  in a different phase or is attenuated. More specifically, there is a phase difference between the vibration of the recording paper P and the vibration of the imaging unit  30 . Therefore, the image of the recording paper P taken by the imaging unit  30  includes an error caused by the vibration of the recording paper P, and the control unit  50  may not be able to detect highly accurate conveyance information. 
     Thus, the imaging unit  30  simultaneously images the reference member  16  in addition to the recording paper P being conveyed in the present embodiment. The image information of the recording paper P includes information in which the effect of the vibration is added to the actual conveyance information. On the other hand, the image information of the reference member  16  includes information of only the effect of the vibration, because the reference member  16  is not conveyed. Therefore, the control unit  50  can remove the effect of the vibration included in the image information of the reference member  16  from the image information of the recording paper P to detect the actual conveyance information of the recording paper P. 
     Hereinafter, a specific process by the control unit  50  will be described with reference to flow charts of  FIGS. 4 and 5 . The CPU  51  of the control unit  50  expands a program stored in the ROM  52  to the RAM  53  and executes the program to realize the flow charts of  FIGS. 4 and 5 . 
     In S 401 , the control unit  50  drives the paper feeding motor  25  to rotate the paper feeding roller unit  24  and separates each of the plurality of pieces of recording paper P loaded on the tray to feed the recording paper P from the paper feeding opening  14 . The control unit  50  further sets a desired position for the recording paper P and drives the conveyor motor  23  to convey the recording paper P to a recording start position. 
     In S 402 , the control unit  50  drives the conveyor motor  23  to convey the recording paper P for one step. Based on the image information taken by the imaging unit  30 , the control unit  50  also detects the conveyance information of the recording paper P actually conveyed at the conveyance of the recording paper P for one step, more specifically, the distance conveyed in the X direction and the distance conveyed in the Y direction. Details of the process will be described later with reference to the flow chart of  FIG. 5 . 
     In S 403 , the control unit  50  drives the carriage moving motor  44  to move the carriage  41  and discharges the ink from the nozzle of the recording head  42  to record the image for one step in which the recording paper P is conveyed. 
     In this case, the control unit  50  controls the recording head  42  to discharge the ink according to the detected actual conveyance information. Specifically, based on the actual distance conveyed in the X direction, the control unit  50  records the image throughout a region equivalent to the distance conveyed in the X direction. For example, when the distance actually conveyed is longer than the original amount of conveyance in the X direction, the image is recorded for a region including the extra length in the X direction. The control unit  50  also makes an offset equivalent to the distance conveyed in the Y direction (distance displaced in the Y direction) and records the image. Although the conveying unit  20  is not ordinarily supposed to convey the recording paper P in the Y direction, the recording paper P may be displaced in the Y direction due to slipping of the conveyor roller unit or the like. In this case, the control unit  50  records the image by shifting the timing of the start of the discharge of the ink according to the distance conveyed in the Y direction when the control unit  50  moves the recording head  42  in the Y direction. 
     In S 404 , the control unit  50  determines whether all of the recording of the image is finished. If all of the recording of the image is finished, the control unit  50  proceeds to step S 405 . If all of the recording of the image is not finished, the control unit  50  returns to S 402  to repeat the process of S 402  and S 403 . 
     In S 405 , the control unit  50  drives the conveyor motor  23  to discharge the recording paper P with the recorded image from the paper discharge opening  15 . 
     Next, the process of S 402  will be described with reference to the flow chart of  FIG. 5 . 
     In S 501 , the control unit  50  instructs the imaging unit  30  to take an image before the recording paper P is conveyed from the recording start position. The imaging unit  30  takes an image including the recording paper P and the reference member  16  in the imaging range R and transmits the taken image information, that is, image data, to the control unit  50 . The control unit  50  applies image processing, such as shading correction, to the received image data and stores the image data after the image processing. In this case, the control unit  50  stores the image data after adding identification information to the image data. For the convenience, the stored image data will be called first image data. 
       FIG. 6  is a view illustrating an example of first image data  60  obtained by the imaging unit  30  photographing the imaging range R. Each rectangle in the first image data  60  illustrated in  FIG. 6  indicates one pixel of the image pickup element of the imaging unit  30 . To facilitate the understanding, it is assumed here that the imaging range R is a range of 8 pixels×8 pixels, and the image is a gray scale image with 256 black and white gradations. 
     As illustrated in  FIG. 6 , a paper image  61  in the first image data  60  is an image obtained by photographing the recording paper P and is an example of the image information of the conveyed object. The recording paper P is not recorded yet, and the brightness value of the paper image  61  as a whole is high. However, the brightness value varies with respect to the average brightness of the entire recording paper P due to slight unevenness on the surface of the recording paper P, and the unevenness emerges as a pattern. The control unit  50  extracts an image of a predetermined region (region in an alternate long and short dash line) as a template image  62  and stores brightness information and position information. For example, the control unit  50  stores the brightness value of each pixel in the template image  62  and the center coordinates of the template image  62  in the first image data  60 . In  FIG. 6 , the center coordinates of the template image  62  are (X, Y)=(4, 7). 
     Meanwhile, a region of a housing image  63  in the first image data  60  is an image obtained by photographing the conveyance support portion  12  and the reference member  16  of the housing  11  and is an example of the image information of the imaging reference portion. Although the brightness value of the conveyance support portion  12  is substantially constant in the housing image  63 , the brightness value of the reference member  16  is lower than the conveyance support portion  12 . The control unit  50  specifies, as the reference member  16 , a pixel with a brightness value substantially the same as a brightness value stored in advance and stores the specified position information. For example, the center coordinates of the reference member  16  are (X, Y)=(5, 3) in  FIG. 6 . 
     Although the brightness value of the reference member  16  used here is higher than the brightness value of the conveyance support portion  12 , a reference member  16  with a brightness value lower than the brightness value of the conveyance support portion  12  may be used instead. 
     In S 502 , the control unit  50  instructs the conveyor motor  23  to start conveying the recording paper P by an amount of conveyance for one target step (hereinafter, called a target amount of conveyance). Therefore, the conveyor motor  23  rotates the first conveyor roller unit  21  to convey the recording paper P for the target amount of conveyance. 
     In S 503 , the control unit  50  instructs the imaging unit  30  to image the recording paper P being conveyed. The imaging unit  30  takes an image including the recording paper P being conveyed and the reference member  16  in the same imaging range R as in S 501  and transmits the taken image data to the control unit  50 . The control unit  50  applies image processing, such as shading correction, to the received image data and stores the image data after the image processing. In this case, the control unit  50  stores the image data after adding identification information to the image data. For the convenience, the stored image data will be called second image data here. 
       FIG. 7  is a view illustrating an example of second image data  70  obtained by the imaging unit  30  photographing the imaging range R. As illustrated in  FIG. 7 , a region of a paper image  71  in the second image data  70  indicates a photographed image obtained by photographing the recording paper P being conveyed. In the paper image  71 , a region equivalent to the template image  62  of the first image data  60  is moved in the conveyance direction. 
     Meanwhile, a region of a housing image  73  in the second image data  70  indicates a photographed image obtained by imaging the reference member  16 . Although the reference member  16  is supported by the conveyance support portion  12  and is not conveyed, the reference member  16  is moved due to the vibration of the first conveyor roller unit  21 . 
     Here, the timing of imaging in S 503  is set in a time period (predetermined time) in which the second image data  70  includes the region equivalent to the template image  62  of the first image data  60 . The predetermined time is stored in advance in the control unit  50  based on the imaging range R and the conveyance speed. 
     In S 504 , the control unit  50  estimates an amount of conveyance of the recording paper P between the imaging of the last time and the imaging of this time. Specifically, the control unit  50  calculates the amount of conveyance of the recording paper P (hereinafter, called an estimated amount of conveyance) from the information detected by the encoder  26 . The estimated amount of conveyance is detected based on the amount of rotation of the first conveyor roller unit  21  and is different from the actual amount of conveyance of the recording paper P when the first conveyor roller unit  21  is decentered or when there is slipping between the first conveyor roller unit  21  and the recording paper P. The control unit  50  stores the calculated estimated amount of conveyance. 
     Next, in a process from S 505  to S 507 , the control unit  50  detects the actual conveyance information of the recording paper P in which the effect of the vibration is removed, based on the image information of the recording paper P and the image information of the reference member  16 . The process is an example of the process by the conveyance detection unit. 
     In S 505 , the control unit  50  acquires conveyance information of the recording paper P on the photographed image from the image information of the recording paper P in the first image data  60  and the image information of the recording paper P in the second image data  70 . The process is an example of the process by the conveyance information acquisition unit. 
     Specifically, the control unit  50  acquires the conveyance information of the recording paper P on the photographed image by searching the position of the pattern image, which is similar to the template image  62  extracted from the paper image  61  of the first image data  60 , in the paper image  71  of the second image data  70 . 
     Here, a pattern matching method can be used as a method of searching the position of the pattern image similar to the template image  62 . As illustrated in  FIG. 7 , the control unit  50  uses, for example, SAD (Sum of Absolute Difference) to search the pattern image similar to the template image  62  from the paper image  71  of the second image data  70  based on the brightness information of each image. In this case, the control unit  50  can quickly perform the pattern matching by searching only the proximity of the estimated amount of conveyance based on the estimated amount of conveyance calculated in S 504 . The control unit  50  specifies a pattern image  72  most similar to the template image  62  in the paper image  71  and acquires the position information of the specified pattern image  72 . In  FIG. 7 , the coordinates (center coordinates) of the pattern image  72  are (X, Y)=(7, 7). 
     Next, the control unit  50  calculates the conveyance information on the photographed image by obtaining the difference in the X direction and the difference in the Y direction from the coordinates of the template image  62  of the paper image  61  of the first image data  60  and the coordinates of the specified pattern image  72 . In  FIGS. 6 and 7 , the control unit  50  can acquire the conveyance information on the taken image indicating that the recording paper P is conveyed +3 pixels in the X direction and 0 pixels in the Y direction based on the difference in the coordinates. The control unit  50  stores the acquired conveyance information on the photographed image. 
     In S 506 , the control unit  50  acquires movement information of the reference member  16  on the photographed image from the image information of the reference member  16  in the first image data  60  and the image information of the reference member  16  in the second image data  70 . The process is an example of the process by the movement information acquisition unit. The reference member  16  is not conveyed, and the movement information here indicates movement caused by the vibration of the first conveyor roller unit  21  or the like. 
     Specifically, the control unit  50  specifies, as the reference member  16 , the pixel with substantially the same brightness value as the brightness value stored in advance and acquires the specified position information. For example, the center coordinates of the reference member  16  are (X, Y)=(6, 3) in  FIG. 7 . To specify the reference member  16 , a method similar to the method of searching the pattern image similar to the template image  62  can be used. In this case, the control unit  50  can quickly perform the pattern matching by searching only a range of amplitude of vibration supposed in advance. 
     Next, the control unit  50  calculates the movement information of the reference member  16  on the photographed image by obtaining the difference in the X direction and the difference in the Y direction from the coordinates of the reference member  16  of the housing image  63  of the first image data  60  and the coordinates of the reference member  16  specified in the housing image  73  of the second image data  70 . For example, in  FIGS. 6 and 7 , the control unit  50  can acquire the movement information on the taken image indicating that the reference member  16  is moved +1 pixel in the X direction and 0 pixels in the Y direction based on the difference in the coordinates. The control unit  50  stores the acquired movement information on the photographed image. 
     In step S 507 , the control unit  50  corrects the conveyance information of the recording paper P on the photographed image based on the image information of the reference member  16  on the photographed image to detect the actual conveyance information of the recording paper P in which the effect of the vibration is removed. The process is an example of the process by the correction unit. 
     Specifically, the control unit  50  can subtract the pixel after the movement of the reference member  16  in the X direction and the Y direction on the photographed image from the pixel after the conveyance of the recording paper P in the X direction and the Y direction in the photographed image to calculate the actual conveyance information of the recording paper P. 
     In  FIGS. 6 and 7 , the conveyance information of the recording paper P on the photographed image is information indicating +3 pixels in the X direction and 0 pixels in the Y direction, and the movement information of the reference member  16  on the photographed image is information indicating +1 pixel in the X direction and 0 pixels in the Y direction. Therefore, the control unit  50  subtracts 1 pixel from 3 pixels in the X direction and subtracts 0 pixels from 0 pixels in the Y direction to obtain +2 pixels in the X direction and 0 pixels in the Y direction. Thus, the calculated conveyance information is the actual conveyance information of the recording paper P in which the effect of the vibration is removed, and the recording paper P here is actually conveyed +2 pixels in the X direction and 0 pixels in the Y direction in the imaging timing from the first image data  60  to the second image data  70 . The control unit  50  stores the acquired conveyance information of the recording paper P actually conveyed. 
     In S 508 , the control unit  50  determines whether the conveyance equivalent to one step is finished. If the conveyance equivalent to one step is not finished, the control unit  50  returns to S 503  to repeat the process from S 503  to S 507 . In this case, the control unit  50  sets, as the second image data, new image data acquired by returning to S 503  and sets, as the first image data, the image data acquired in S 503  of the last time to execute the process from S 505  to S 507 . More specifically, in S 503 , it is preferable that the control unit  50  extracts the predetermined region as the template image  62  as in S 501  and stores the brightness information and the position information, in addition to the storage of the image data after the image processing. 
     On the other hand, if the conveyance equivalent to one step is finished, the control unit  50  proceeds to S 509 . The control unit  50  proceeds to S 509  when the conveyance is temporarily halted for the recording of the image by the recording unit  40  after the end of the conveyance equivalent to one step. 
     In S 509 , the control unit  50  adds all the actual conveyance information stored in S 507  to acquire the conveyance information of the recording paper P actually conveyed in the conveyance for one step. Specifically, the control unit  50  adds the pixels in the X direction and the Y direction and multiplies the added pixels by the pixel pitch to acquire the distance conveyed in the X direction and the distance conveyed in the Y direction. 
     In this way, the control unit  50  can acquire the conveyance information of the recording paper P actually conveyed in the conveyance for one step to control the recording head  42  according to the detected actual conveyance information to discharge the ink in S 403 . Therefore, the control unit  50  records the image throughout the region equivalent to the distance conveyed in the X direction based on the actual distance conveyed in the X direction and records the image after offsetting the image according to the distance displaced in the Y direction. This can prevent a broken image and an overlapped image even when the recording unit  40  records the image step by step. 
     According to the present embodiment, the control unit  50  detects the conveyance information of the recording paper P based on the image information of the recording paper P and the image information of the object not conveyed imaged by the imaging unit  30 . Here, the image information of the recording paper P includes information in which the effect of the vibration is added to the actual conveyance information, and the image information of the object not conveyed includes information of only the effect of the vibration. Therefore, the effect of the vibration included in the image information of the object not conveyed can be removed from the image information of the recording paper P to accurately detect the actual conveyance information of the recording paper P. 
     According to the present embodiment, the control unit  50  detects the conveyance information of the recording paper P based on the image information of the recording paper P and the image information of the reference member  16  imaged by the imaging unit  30 . Here, the reference member  16  can be easily specified from the image information by using the reference member  16  as an object not conveyed, and the information of the effect of the vibration can be accurately detected from the image information of the reference member  16 . 
     According to the present embodiment, the housing  11  includes the conveyance support portion  12  that supports the conveying unit  20 , and the conveyance support portion  12  directly or indirectly supports the reference member  16 . Thus, the vibration of the first conveyor roller unit  21  or the second conveyor roller unit  22  of the conveying unit  20  is transmitted to the reference member  16  without a phase difference. Therefore, the effect of substantially the same vibration can be included in both the image information of the recording paper P and the image information of the reference member  16 , and the effect of the vibration included in the image information of the reference member  16  can be easily removed from the image information of the recording paper P. 
     According to the present embodiment, the control unit  50  detects the actual conveyance information of the recording paper P by correcting the conveyance information of the recording paper P acquired based on the image information of the recording paper P, based on the movement information of the reference member  16  acquired based on the image information of the reference member  16 . Here, the conveyance information of the recording paper P includes the information in which the effect of the vibration is added to the actual conveyance information, and the movement information of the reference member  16  includes the information of only the effect of the vibration. Therefore, the effect of the vibration can be removed from the conveyance information of the recording paper P by correcting the movement information of the reference member  16 , and the actual conveyance information of the recording paper P can be accurately detected. 
     According to the present embodiment, the control unit  50  acquires the conveyance information of the recording paper P on the photographed image based on the image information before and after the predetermined time in the recording paper P and acquires the movement information of the reference member  16  on the photographed image based on the image information before and after the predetermined time in the reference member  16 . The control unit  50  uses the movement information on the photographed image to correct the conveyance information on the photographed image to thereby detect the actual conveyance information of the recording paper P. Therefore, the actual conveyance information of the recording paper P can be accurately detected. 
     According to the present embodiment, the recording paper P and the reference member  16  are imaged in the same imaging range R, and the image information of the recording paper P and the image information of the reference member  16  are acquired from the same photographed image. Therefore, a plurality of imaging units  30  with synchronized imaging timing do not have to be provided, and the cost of the conveying apparatus  10  can be reduced. 
     According to the present embodiment, the distance from the imaging unit  30  to the conveyance path and the distance from the imaging unit  30  to the reference member  16  are substantially the same. Therefore, a focused image can be easily taken for both the image information of the recording paper P and the image information of the reference member  16  imaged by the imaging unit  30 . However, the distance from the imaging unit  30  to the conveyance path and the distance from the imaging unit  30  to the reference member  16  may not be the same if a focused image can be taken. 
     According to the present embodiment, the reference member  16  is a rod-like member protruding toward the imaging unit  30 . Therefore, the imaging reference portion can be easily set. In this case, the distance from the imaging unit  30  to the conveyance path and the distance from the imaging unit  30  to the tip of the rod-like member are substantially the same. Therefore, a focused image can be easily taken for both the image information of the recording paper P and the image information of the rod-like member imaged by the imaging unit  30 . However, the reference member  16  is not limited to the rod-like member, and the reference member  16  may be a light source such as an LED. 
     Although the present invention has been described with reference to the embodiment, the present invention is not limited to the embodiment, and changes can be made within the scope of the present invention. 
     In the case described in the embodiment, the process from S 503  to S 507  is repeated, and the conveyance information of the recording paper P actually conveyed for one step is acquired in S 509 . The recording unit  40  records the image based on the acquired conveyance information. However, the present invention is not limited to this. For example, the actual conveyance information may be acquired in S 507 , and the acquired actual conveyance information may be fed back to control the conveyor motor  23  in real time. More specifically, the control unit  50  controls the conveyor motor  23  to reduce the amount of rotation when the acquired actual conveyance information is long and controls the conveyor motor  23  to increase the amount of rotation when the acquired actual conveyance information is short. Therefore, when the conveyance for one step is finished, the same amount of conveyance as the scheduled amount of conveyance for one step can be conveyed. As a result of the control, the recording unit  40  only has to always record the image for one step, and the control unit  50  can reduce the control for the recording unit  40 . As a result of the control, the printer is not limited to the inkjet type in which the image is recorded step by step, and a printer of an electrophotographic type, a thermal transfer type, a dot impact type, or the like can also be used. As a result of the control, not only the recording apparatus  100 , but also a conveying apparatus without the configuration of the recording unit  40  can be adopted. Note that an example of the conveying apparatus  10  includes an image reading apparatus, such as a scanner, in which the configuration of the recording unit  40  is replaced with a configuration of an image reading unit. 
     Although the reference member  16  is directly supported by the conveyance support portion  12  in the case described in the embodiment, the present invention is not limited to the case, and the reference member  16  may be indirectly supported by the conveyance support portion  12  through an intermediate member. More specifically, it is only necessary that the reference member  16  is supported at a position in which the vibration of the conveying unit  20  is transmitted without a phase difference. On the other hand, the imaging unit  30  may be supported at a position with a phase difference relative to the vibration of the conveying unit  20 , and the installation position of the imaging unit  30  can be freely set. 
     Although the control unit  50  is arranged in the housing  11  in the case described in the present embodiment, the present invention is not limited to the case, and the control unit  50  may be arranged outside of the housing  11 . In this case, the control unit  50  can control the conveying apparatus  10  and the recording unit  40  in a wired or wireless manner. 
     Although the CPU  51  executes the program to realize the process in the case described in the present embodiment, the present invention is not limited to the case, and each circuit including hardware may execute the process. 
     The present invention also includes the program and a computer-readable recording medium recording the program. 
     According to the present invention, highly accurate conveyance information can be detected. 
     It should be noted that the above embodiments merely illustrate concrete examples of implementing the present invention, and the technical scope of the present invention is not to be construed in a restrictive manner by these embodiments. That is, the present invention may be implemented in various forms without departing from the technical spirit or main features thereof.