JP2015004586A - Movement amount detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a movement amount detection device capable of detecting the amount of movement of a mobile object with high accuracy.SOLUTION: The movement amount detection device according to an embodiment includes: a laser beam source; a beam splitter which reflects a laser beam emitted from the laser beam source and causes the reflected laser beam to be made incident on a planar first surface of a light transmittable member from an aslant direction relative to the normal of the first surface, the light transmittable member having this first surface and a second surface on the opposite side of the first surface, and which irradiates the mobile object transported facing the second surface, with the incident laser beam via the light transmittable member, and which transmits a reflected light of the laser beam reflected by the mobile object; an imaging unit for capturing, at prescribed time intervals, the image of the reflected light the beam splitter has transmitted; and a calculation unit, on the basis of an image correlation between two images captured at the predetermined time intervals, calculating the amount of movement of the mobile object for each time interval.

Description

  The present invention relates to a movement amount detection apparatus.

  Conventionally, in an image reading apparatus such as a scanner and an image forming apparatus such as a printer, it is important to accurately convey a moving body such as a sheet as a medium to be read or written. For this reason, inspection of conveyance of a moving body is performed at the time of factory shipment. In the inspection of the conveyance of the moving body, there is known a movement amount detection device that periodically reads speckles appearing on the surface of the sheet by irradiating the moving body with laser light to obtain the movement amount of the moving body.

  As this type of movement detection device, there is known a device that reflects a laser beam with a beam splitter and irradiates the reflected laser beam perpendicularly on the surface of a moving body (for example, see Patent Document 1).

JP 2000-121565 A

  However, in the above-described conventional technology, when there is a transmissive member such as glass that transmits light between the beam splitter and the moving body, speckles generated by the transmissive member are imaged by the camera, and the detected amount of the moving body In some cases, it was not possible to accurately detect this.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a movement amount detection apparatus that can accurately detect the movement amount of a moving body.

  A movement amount detection apparatus according to an embodiment of the present invention reflects a laser light source and laser light emitted from the laser light source, and causes the laser light to be reflected between a planar first surface and the first surface. The laser beam is incident on the first surface of the transmissive member having a second surface on the opposite side and capable of transmitting light obliquely with respect to the normal line of the first surface, A beam splitter that irradiates the movable body conveyed opposite to the second surface through the transmission member and transmits the reflected light of the laser beam reflected by the movable body, and transmits the beam splitter. A calculation that calculates the amount of movement of the moving body at each time interval based on an image correlation between the imaging unit that images the reflected light at a predetermined time interval and two images captured at the predetermined time interval. And a section.

  According to the embodiment of the present invention, there is an effect that it is possible to accurately detect the conveyance speed of the moving body.

FIG. 1 is a diagram illustrating a movement amount detection device and an automatic document feeder according to the first embodiment. FIG. 2 is a front view illustrating a part of the movement amount detection device and the automatic document feeder according to the first embodiment. FIG. 3 is a block diagram illustrating the movement amount detection apparatus according to the first embodiment. FIG. 4 is a conceptual diagram illustrating the calculation of the movement amount of the sheet based on the image correlation between the two speckle images according to the first embodiment. FIG. 5 is a graph illustrating a sheet movement amount graph for each time interval calculated by the movement amount detection apparatus according to the first embodiment. FIG. 6 is a front view illustrating a part of the movement amount detection device and the automatic document feeder according to the first comparative example. FIG. 7 is a diagram illustrating a graph of the sheet movement amount for each time interval calculated by the movement amount detection device according to the first comparative example. FIG. 8 is a diagram illustrating a table of speckle images according to the first embodiment and the first comparative example. FIG. 9 is a front view illustrating a part of the movement amount detection device and the automatic document feeder according to the second comparative example. FIG. 10 is a diagram illustrating a graph of the sheet movement amount for each time interval calculated by the movement amount detection apparatus according to the second comparative example. FIG. 11 is a block diagram illustrating a movement amount detection device according to the second embodiment. FIG. 12 is a front view illustrating a movement amount detection apparatus according to the second embodiment. FIG. 13 is a flowchart illustrating the flow of angle adjustment processing executed by the movement amount detection apparatus according to the second embodiment. FIG. 14 is a diagram illustrating a graph of the sheet movement amount for each time interval calculated during the angle adjustment processing by the movement amount detection apparatus according to the second embodiment.

  Embodiments of a movement amount detection device will be described in detail below with reference to the accompanying drawings. Note that similar components are included in the following embodiments. Therefore, in the following, common reference numerals are given to those similar components, and redundant description is omitted.

  In the following embodiments, a moving amount detection device (inspection device) that detects a moving amount of a sheet at a reading position of an automatic document feeder (ADF) will be described as an example. However, the moving body and the position for detecting the transport speed of the moving body are not particularly limited. For example, an intermediate transfer belt in an image forming apparatus that forms a color image on a sheet by a tandem method may be used as a moving body to be inspected. Also, the position for detecting the sheet conveyance speed may be other than the reading position, such as a paper feeding position or an image forming position when performing image formation.

(First embodiment)
FIG. 1 is a diagram illustrating a movement amount detection device 1 and an automatic document feeder 120 according to this embodiment. In FIG. 1, the mechanical structure of the paper feed conveyance mechanism of the automatic document conveyance device 120 is illustrated in cross section.

  As shown in FIG. 1, in an automatic document feeder 120 (conveyance mechanism) to be inspected, a plurality of sheets 100 (see FIG. 2) stacked on a paper feed tray 121 are fed by a pickup roller 122 at the start of reading. The paper is transported via the transport roller 123 and then discharged onto the paper discharge tray 127 by the paper discharge roller 126. In this conveyance process, the sheet 100 is read through the glass 125 when it reaches the reading position of the background plate 124. Therefore, in the automatic document feeder 120, it is important in terms of reading accuracy that the conveyance position of the sheet 100 at the reading position is a designed conveyance position.

  For this reason, as shown in FIG. 2, the movement amount detection device 1 reads the reflected light 3 by the laser beam 2 (irradiation light) at the reading position of the automatic document feeder 120 and picks it up. The movement amount (conveying speed) of the sheet 100 is detected.

  Specifically, the movement amount detection device 1 irradiates the sheet 100 with the laser beam 2 at the reading position of the automatic document feeder 120, and the speckles appearing on the surface 100 a (surface) of the sheet 100 by the laser beam 2. The reflected light 3 is imaged at a predetermined time interval (frame rate).

  Here, the speckle is a bright and dark spot pattern generated in the scattered light (reflected light 3) in the region irradiated with coherent light such as the laser light 2 and the uneven structure on the subject surface (surface) in the region.

  Then, the movement amount detection device 1 moves based on the image correlation of the speckle image G1 (see FIG. 4) that is an image of two speckles captured from the reflected light 3 at a predetermined time interval. The amount, that is, the conveyance speed of the sheet 100 is detected.

  FIG. 2 is a front view illustrating a part of the movement amount detection device 1 and the automatic document feeder 120 according to this embodiment. As shown in FIG. 2, in the present embodiment, the glass 125 of the automatic document feeder 120 has, for example, a flat appearance, and includes a surface 125 a (first surface) and the opposite side of the surface 125 a. Surface 125b (second surface). The surfaces 125a and 125b are formed in a planar shape. The surface 125b is disposed to face the background plate 124. The sheet 100 is conveyed along the surface 125b while facing the surface 125b. That is, the sheet 100 is conveyed between the surface 125b and the background plate 124 with the surface 100a and the surface 125b facing each other. The glass 125 is an example of a transmission member (transparent member) through which light (laser light) can pass. The transmitting member is not limited to the glass 125 but may be made of, for example, a resin.

  As illustrated in FIG. 2, the movement amount detection device 1 of the present embodiment includes a laser light source 11 (light source), a beam splitter 12, and a camera 13. The laser light source 11, the beam splitter 12, and the camera 13 are optical system devices for irradiating the surface 100 a of the sheet 100 with the laser light 2 and imaging the reflected light 3 from the sheet 100.

  The laser light source 11 is a light emitting element that emits laser light 2. The laser light 2 emitted from the laser light source 11 is reflected by the beam splitter 12 and irradiated toward the position where the sheet 100 conveyed by the automatic document conveying device 120 passes. In the present embodiment, the position through which the sheet 100 passes is on the surface 124a of the background plate 124 as an example.

  The beam splitter 12 is positioned between the camera 13 and the glass 125 and faces the surface 125a. The beam splitter 12 reflects the laser light 2 emitted from the laser light source 11, and causes the laser light 2 to enter the surface 125a of the glass 125 from an oblique direction with respect to the normal line 125c of the surface 125a. The laser beam 2 is irradiated through the glass 125 to the sheet 100 conveyed to face the surface 125 b of the glass 125. Here, the angle between the laser beam 2 and the normal 125c of the surface 125a, that is, the incident angle α1 of the laser beam 2 on the surface 125a of the glass 125 is larger than 0 degree. The beam splitter 12 transmits the reflected light 3 of the laser light 2 reflected by the sheet 100 and the background plate 124. The reflected light 3 transmitted through the beam splitter 12 enters the camera 13.

  Specifically, the beam splitter 12 has an inclined surface 12a (layer, film). The inclined surface 12a is inclined with respect to the normal 125c of the surface 125a, and reflects the laser light 2 emitted from the laser light source 11 toward the glass 125. The inclined surface 12 a transmits the reflected light 3 of the laser light 2 reflected by the sheet 100 and the background plate 124 toward the camera 13. In the present embodiment, the acute angle α2 (angle) between the normal 12b of the inclined surface 12a and the normal 125c of the surface 125a of the glass 125 is an angle different from 45 degrees. In the present embodiment, as an example, the incident angle of the laser light 2 emitted from the laser light source 11 to the inclined surface 12a is 45 degrees. Note that the angle of the inclined surface 12a of the beam splitter 12 and the incident angle of the laser beam 2 on the inclined surface 12a are not limited to the above, and the laser beam 2 is applied to the surface 125a of the glass 125 and the surface 125a method. Other angles may be used as long as they can be incident on the line 125c from an oblique direction.

  In the above configuration, the laser light 2 emitted from the laser light source 11 and reflected by the inclined surface 12a of the beam splitter 12 is irradiated obliquely onto the surface 100a of the sheet 100 being conveyed. That is, the laser beam 2 is irradiated at a predetermined angle greater than 0 degree with respect to the normal line 100b of the surface 100a of the sheet 100 being conveyed, that is, with a predetermined incident angle greater than 0 degree with respect to the surface 100a of the sheet 100. The In this embodiment, the normal line 100b of the surface 100a of the sheet 100 is perpendicular to the conveying direction (the direction of the arrow D1). Then, by irradiating the surface 100 a of the sheet 100 with the laser light 2, speckles are generated on the surface 100 a of the sheet 100 due to scattering by the concavo-convex structure. In the captured image G, the speckle image G1 where the conveyed sheet 100 exists is displaced by the amount of movement of the sheet 100 that moves at the frame rate interval. In addition, the speckle image G1 corresponding to the surface 124a of the background plate 124 without the conveyed sheet 100 is stationary.

  In the present embodiment, as an example, the optical axis 13a of the camera 13 is along the normal line 100b of the surface 100a of the sheet 100 being conveyed. As an example, the optical axis 13 a of the camera 13 is parallel to the normal line 100 b of the surface 100 a of the sheet 100. Therefore, the camera 13 can capture the reflected light 3 from a direction substantially perpendicular to the transport direction (from left to right in FIG. 2). The camera 13 images the reflected light 3 at a predetermined time interval (frame rate). In the captured image G (see FIG. 4) captured at a predetermined frame rate, a speckle image G1 that is an image of speckle generated by scattering by the concavo-convex structure when the surface 100a of the sheet 100 is irradiated with the laser light 2 is used. (See FIG. 4). The camera 13 is an example of an imaging unit that captures speckles of the laser light 2 generated in a region irradiated with the laser light 2 at a predetermined time interval. In the present embodiment, the normal line 125c of the surface 125a of the glass 125, the normal line 100b of the surface 100a of the sheet 100, and the optical axis 13a of the camera 13 are coincident with each other. Yes.

  FIG. 3 is a block diagram illustrating the movement amount detection apparatus 1 according to this embodiment. As shown in FIG. 3, the movement amount detection device 1 includes a control unit 20 (for example, a CPU (Central Processing Unit)), a ROM 21 (Read Only Memory), a RAM 22 (Random Access Memory), an SSD 23 (Solid State Drive), A light irradiation controller 24, an imaging controller 25, an output terminal 27, and the like are provided. The light irradiation controller 24 controls light emission and the like of the laser light source 11 based on a control signal from the control unit 20. The imaging controller 25 controls imaging by the camera 13 based on a control signal from the control unit 20. Further, the control unit 20 reads and executes a program (application) installed in the ROM 21 or the SSD 23 as a nonvolatile storage unit. The RAM 22 temporarily stores various data used when the control unit 20 executes programs and executes various arithmetic processes. Note that the hardware configuration shown in FIG. 3 is merely an example, and can be implemented with various modifications such as a chip or a package. Various arithmetic processes can be performed in parallel, and the control unit 20 and the like can have a hardware configuration capable of parallel processing.

  In the present embodiment, as an example, the control unit 20 functions (operates) as at least a part of the movement amount detection device 1 by cooperation of hardware and software (program). As an example, the control unit 20 functions as the calculation unit 20a and the like.

  In this embodiment, the speckle image G1 acquired by the camera 13 is sequentially stored by a storage unit such as the RAM 21 as an example. Specifically, the storage unit such as the RAM 21 sequentially stores (stacks) captured images G captured by the camera 13 at a predetermined frame rate.

  The calculation unit 20a calculates the movement amount of the sheet 100 at each predetermined time interval based on the image correlation of the speckle image G1, which is an image of two speckles captured at a predetermined time interval. The calculation unit 20a performs image correlation processing of two speckle images G1 at predetermined time intervals stored in a storage unit such as the RAM 21. Specifically, as illustrated in FIG. 4, the calculation unit 20 a performs reading of the n-th captured image G and reading of the n + 1-th captured image G that is the next frame image, and these captured images. G image correlation processing is performed. That is, the calculation unit 20a sequentially reads the captured images G (speckle images G1) sequentially stored in the storage unit such as the RAM 21, and performs image correlation processing for each pair of the correlation images G. The calculating unit 20a performs correlation calculation (for example, phase-only correlation) of the two speckle images G1 to obtain a correlation peak. At this time, the image correlation processing performed by the calculation unit 20a includes discrete Fourier transform processing for each image (data) of the nth captured image G and the (n + 1) th captured image G, composite processing after the discrete Fourier transform processing, and composite processing. Subsequent spectrum weighting processing, inverse discrete Fourier transform processing after spectrum weighting processing, subpixel estimation processing after inverse discrete Fourier transform processing, and the like can be included.

  The calculation unit 20a calculates the movement amount of the sheet 100 at each predetermined time interval based on the result of the image correlation process. Based on the image correlation between the n-th speckle image G1 and the (n + 1) -th speckle image G1, the calculation unit 20a performs the subject (sheet 100, background plate 124) for each time interval (n-th to n + 1-th time). The amount of movement (conveyance speed) is calculated. Specifically, as illustrated in FIG. 4, the calculation unit 20 a calculates the movement amount (vector amount) of the subject corresponding to the correlation peak between the two captured images obtained by the calculation unit 20 a. As an example, the calculation unit 20a performs correlation calculation of two speckle images for each image region divided by a predetermined width, and calculates the movement amount of the subject for each position (pixel) corresponding to the image region. . Here, FIG. 4 shows a graph of the movement amount calculated by the calculation unit 20a. FIG. 5 shows an example in which the incident angle α1 of the laser beam 2 on the surface 125a of the glass 125 is 5 degrees.

  In the present embodiment, the incident angle α1 of the laser beam 2 on the surface 125a of the glass 125 is larger than 0 degree, and the laser beam 2 is incident on the surface 125a of the glass 125 from an oblique direction with respect to the normal line 125c of the surface 125a. To do. On the other hand, as a first comparative example, FIG. 6 shows a movement in which the incident angle α1 of the laser beam 2 on the surface 125a of the glass 125 is 0 degree and the laser beam 2 is incident perpendicularly on the surface 125a of the glass 125. The structure of the quantity detection apparatus 1000 is shown. FIG. 7 shows an example of a graph of the movement amount of the subject in the movement amount detection apparatus 1000 of the first comparative example. In the first comparative example and the present embodiment, the conveyance conditions of the sheet 100 are the same. As can be seen from FIGS. 5 and 7, in the movement amount detection device 1 of the present embodiment, the movement amount of the sheet 100 (subject) is detected with high accuracy, whereas the movement amount detection device 1000 of the first comparative example. Then, even when the sheet 100 (subject) is being conveyed, the movement amount may be detected as “0”. As a cause of this difference, the incident angle α1 of the laser beam 2 on the surface 125a of the glass 125 can be considered. Here, FIG. 8 is a diagram showing a table of speckle images G1 and G2 according to the first embodiment and the first comparative example. As can be seen from FIG. 8, the incident angle α1 of the laser beam 2 on the surface 125a of the glass 125 is 0 degree, that is, the speckle image G2 in the case of the first comparative example, and the laser beam 2 on the surface 125a of the glass 125. The incident angle α1 is 5 degrees, that is, different from the speckle image G1 in the example of the present embodiment. This difference occurs because when the incident angle α1 of the laser beam 2 is 0 degree, the camera 13 has captured the speckle generated on the surface 125a of the glass 125, whereas the laser beam 2 This is because when the incident angle α1 is 5 degrees, the camera 13 can capture speckles generated on the sheet 100 (subject). When the incident angle α1 of the laser beam 2 is 5 degrees, the optical path between the reflected light 3 reflected by the sheet 100 and the reflected light reflected by the surface 125a of the glass 125 is shifted, so that the reflected light reflected by the surface 125a of the glass 125 is reflected. Since light is not easily incident on the camera 13, speckles generated on the sheet 100 (subject) rather than the surface 125 a of the glass 125 can be favorably imaged.

  As a second comparative example, FIG. 9 shows a movement amount detection apparatus 2000 configured such that the beam splitter 12 is not provided and the laser light 2 is directly incident obliquely on the surface 125 a of the glass 125 from the laser light source 11. In this configuration, the incident angle α <b> 1 of the laser beam 2 on the surface 125 a of the glass 125 is relatively large due to restrictions on the arrangement of the laser light source 11. Here, the incident angle of the laser beam 2 on the sheet 100 is larger in the second comparative example than in the present embodiment. An example of a graph of the movement amount of the subject in the movement amount detection apparatus 2000 of the second comparative example having such a configuration is shown in FIG. In the second comparative example and the present embodiment, the conveyance conditions for the sheet 100 are the same. In the movement amount detection apparatus 2000, the laser beam 2 is irradiated to the sheet 100 at a relatively large incident angle. Therefore, as can be seen from FIG. 10, the vertical direction (arrow D2) that is substantially perpendicular to the conveyance direction of the sheet 100. When the sheet 100 is moved in the direction (1), the irradiation position of the laser light 2 is changed, and the speckle image G1 due to the reflected light 3 is blurred. In this case, since the movement in the vertical direction (the direction of the arrow D2) is added to the speed component in the transport direction, if the speed (movement amount) in the transport direction is detected from the speckle image G1, the travel amount in the transport direction for each time. In this case, the undulation corresponding to the vertical movement occurs. As an example, this undulation is likely to occur at the leading end and the trailing end of the sheet 100. As an example, the undulation in the area A3 in FIG. 10 corresponds to the leading end of the sheet 100, and the undulation in the area A4 in FIG. 10 corresponds to the trailing end of the sheet. On the other hand, in the movement amount detection apparatus 1 of the present embodiment, the laser light 2 emitted from the laser light source 11 is reflected by the beam splitter 12 and is incident on the sheet 100. The laser beam 2 can be irradiated to the sheet 100 at a relatively small incident angle regardless of the restrictions on the arrangement of 11. For this reason, in this embodiment, the generation | occurrence | production of a wave | undulation is suppressed compared with the 2nd comparative example so that area | region A1, A2 of FIG. 5 may show. That is, in the present embodiment, in the amount of movement in the transport direction for each time, it is possible to accurately detect the speed component in the transport direction while suppressing the occurrence of undulation corresponding to the vertical movement.

  In the present embodiment, the amount of movement of the subject detected (calculated) by the calculation unit 20a is output from the output terminal 27 to a determination unit (not shown) as an example. For example, the determination unit determines whether or not the sheet 100 is conveyed based on the detected movement amount (conveyance speed). Specifically, the determination unit determines whether or not the sheet 100 is conveyed by determining whether or not the detected movement amount of the sheet 100 is a preset speed. As an example, the determination unit checks the conveyance (conveying speed) of the sheet 100 when the detected movement amount of the sheet 100 is within a predetermined range centering on the movement amount set in advance by the storage unit or the like. Is determined to be good. If the movement amount of the sheet 100 exceeds a predetermined range, it is determined that the inspection result of the conveyance (conveying speed) of the sheet 100 is defective. The determination unit outputs the determination result to the user by display display, voice output, or the like.

  As described above, the movement amount detection apparatus 1 according to the present embodiment includes the laser light source 11, the beam splitter 12, the camera 13, and the calculation unit 20a. The beam splitter 12 reflects the laser light 2 emitted from the laser light source 11, and the laser light 2 is separated into a planar surface 125a (first surface) and a surface 125b (second surface) opposite to the surface 125a. The laser beam 2 is conveyed so as to face the surface 125b by being incident on a surface 125a of the glass 125 through which light can be transmitted obliquely with respect to the normal line 125c of the surface 125a. The sheet 100 is irradiated through the glass 125 and the reflected light 3 of the laser beam 2 reflected by the sheet 100 is transmitted. The camera 13 images the reflected light 3 transmitted through the beam splitter 12 at predetermined time intervals. The calculation unit 20a calculates the amount of movement of the sheet 100 for each time interval based on the image correlation between two images captured at a predetermined time interval. Therefore, according to the present embodiment, the beam splitter 12 reflects the laser light 2 emitted from the laser light source 11, and the laser light 2 is obliquely directed to the surface 125a with respect to the normal 125c of the surface 125a. Therefore, the speckle generated in the sheet 100 can be imaged satisfactorily by the camera 13 while suppressing the influence of the speckle generated in the glass 125. Therefore, according to the present embodiment, the amount of movement of the sheet 100 can be detected with high accuracy.

  In the present embodiment, the beam splitter 12 is positioned between the camera 13 and the glass 125, and the optical axis 13a of the camera 13 is along the normal 125c of the surface 125a of the glass 125. Therefore, according to the present embodiment, speckles generated on the sheet 100 can be favorably imaged by the camera 13.

(Second Embodiment)
FIG. 11 is a block diagram illustrating a movement amount detection apparatus according to this embodiment. As shown in FIG. 11, the movement amount detection device 1 of the present embodiment includes a movement device 14 (moving unit). The moving device 14 movably holds at least one of the laser light source 11 and the beam splitter 12 such that the incident angle of the laser light 2 reflected by the beam splitter 12 on the sheet 100 is variable. That is, the moving device 14 can change the angle α1 with respect to the normal 125c of the surface 125a of the laser beam 2 reflected by the beam splitter 12 and incident on the surface 125a of the glass 125.

  In the present embodiment, the moving device 14 includes, as an example, a holding member (frame) that holds the laser light source 11 and the beam splitter 12, and an actuator that rotates the holding member. The actuator 14 rotates the laser light source 11 and the beam splitter 12 about the rotation center axis by the actuator rotating the holding member about the rotation center axis (axial core). As an example, the rotation center axis passes through the center of the beam splitter 12 and is orthogonal to the conveying direction and the optical axis 13a of the camera 13 (normal line 125c of the surface 125a of the glass 125) (perpendicular to the paper surface of FIG. 2). Direction). For example, the moving device 14 sets the incident angle of the laser beam 2 on the sheet 100 to an arbitrary angle between a specified angle larger than 0 degrees (for example, FIG. 2) and 0 degrees. Can do. Note that the moving device 14 may be able to variably set the incident angle of the laser beam 2 on the sheet 100 to only two of a specified angle (FIG. 2) larger than 0 degrees and 0 degrees. . As shown in FIG. 12, in the case where the glass 125 is not provided, the incidence of the laser beam 2 perpendicularly to the surface 100a of the sheet 100 (moving body) is affected by the vertical movement of the sheet 100. This can be suppressed, which is preferable.

  As shown in FIG. 11, the moving device 14 is connected to the control unit 20 via the movement controller 26. The movement controller 26 controls the moving device 5 based on the control signal received from the control unit 20 to control the incident angle of the laser light 2 on the sheet 100 (angle α2 with respect to the normal 125c of the surface 125a).

  In the present embodiment, as an example, the control unit 20 functions as an angle adjustment unit 20b in addition to the calculation unit 20a by the cooperation of hardware and software (program).

  The angle adjusting unit 20b controls the moving device 14 to adjust the angle α1 with respect to the normal 125c of the surface 125a of the laser beam 2 reflected by the beam splitter 12 and incident on the surface 125a of the glass 125. The angle adjustment unit 20b adjusts the angle α1 so that the movement amount calculated by the calculation unit 20a exceeds the threshold E (see FIG. 14) for a predetermined time or more.

  Next, an angle adjustment process executed by the movement amount detection apparatus 1 will be described with reference to a flowchart shown in FIG. In the present embodiment, as an example, the initial setting value of the angle α1 with respect to the normal 125c of the surface 125a of the laser light 2 is 0 degree. Thus, by setting the initial value of the angle α1 to 0 degrees, the adjusted angle α1 can be made closer to 0 degrees. Note that the initial setting value of the angle α1 may be other than 0 degrees.

  First, the angle adjustment unit 20b performs a movement amount evaluation process (step S1). In the movement amount evaluation process, it is determined whether or not the movement amount calculated by the calculation unit 20a exceeds a threshold E (see FIG. 14) for a predetermined time (first time). In the case of the example in FIG. 14, the predetermined time is a time between one scale on the horizontal axis (e.g., between the elapsed time t1 and the elapsed time t2), and the threshold is the movement amount value E. When the angle adjustment unit 20b determines that the movement amount calculated by the calculation unit 20a does not exceed the threshold E for a predetermined time or more, that is, the angle α2 is not suitable (No in step S2), the process proceeds to step S4. The angle α2 is increased by a predetermined angle. In the case of the example in FIG. 14, since the movement amount calculated by the calculation unit 20a does not continue to exceed the threshold value E for a predetermined time from the start of the evaluation process to the elapsed time t1, during this period, Steps S1, S2, and S4 are repeated.

  On the other hand, the angle adjustment unit 20b determines that the movement amount calculated by the calculation unit 20a exceeds the threshold E (see FIG. 14) for a predetermined time or more, that is, determines that the angle α is suitable (in step S2). Yes) determines the current angle α2 as the set angle α2. In the example of FIG. 14, during the period from the elapsed time t1 to the elapsed time t2, the movement amount calculated by the calculation unit 20a continues to exceed the threshold value E. Therefore, in this case, the angle adjustment unit 20b determines the angle α2 set at the elapsed time t1 as the angle to be set (step S3).

  As described above, in the present embodiment, the moving device 14 can move at least one of the laser light source 11 and the beam splitter 12 by changing the incident angle of the laser light 2 reflected by the beam splitter 12 to the sheet 100. Hold on. Therefore, according to the present embodiment, the incident angle of the laser beam 2 reflected by the beam splitter 12 on the sheet 100 can be changed.

  In the present embodiment, the angle adjusting unit 20b controls the moving device 14 to adjust the angle α2 with respect to the normal 125c of the surface 125a of the laser beam 2 reflected by the beam splitter 12 and incident on the surface 125a. Therefore, according to the present embodiment, the angle α2 with respect to the normal 125c of the surface 125a of the laser beam 2 can be adjusted by the angle adjusting unit 20b.

  In the above embodiment, the example in which the present invention is applied to the sheet conveyance movement amount detection device has been described. However, the present invention is not limited to the sheet conveyance movement amount detection device, and any movement for inspecting conveyance of a moving body is described. The present invention can be widely applied to quantity detection devices. Further, the technical matters disclosed as the above embodiments are examples of preferable applications of the present invention, and the technical scope of the present invention is not limited to the technical matters disclosed as the above embodiments. The technical scope of the present invention includes various modifications and alternative techniques that can be easily conceived within the scope of the present invention, in addition to the specific technical matters disclosed as the above embodiments.

  DESCRIPTION OF SYMBOLS 1 ... Movement amount detection apparatus, 11 ... Laser light source, 12 ... Beam splitter, 13 ... Camera (imaging part), 14 ... Movement apparatus (moving part), 20a ... Calculation part, 20b ... Angle adjustment part, 100 ... Sheet (movement) Body), 100a ... surface, 125 ... glass (transmission member), 125a ... surface (first surface), 125b ... surface (second surface), G ... captured image, G1 ... speckle image.

Claims (6)

A laser light source;
The laser light emitted from the laser light source is reflected, and the laser light has a flat first surface and a second surface opposite to the first surface, and allows light to pass therethrough. The member is incident on the first surface of the member from an oblique direction with respect to the normal line of the first surface, and the laser beam is transmitted to the moving body that is conveyed facing the second surface. A beam splitter that irradiates through a member and transmits the reflected light of the laser beam reflected by the moving body;
An imaging unit that images the reflected light transmitted through the beam splitter at a predetermined time interval;
A calculation unit that calculates a movement amount of the moving body for each time interval based on an image correlation between two images captured at the predetermined time interval;
A movement amount detection device comprising: The beam splitter is positioned between the imaging unit and the second surface;
The movement amount detection apparatus according to claim 1, wherein an optical axis of the imaging unit is along a normal line of the first surface. The beam splitter has an inclined surface,
The inclined surface is inclined with respect to the normal line, reflects laser light emitted from the laser light source toward the transmitting member, and transmits the reflected light toward the imaging unit,
The movement amount detection apparatus according to claim 1, wherein an acute angle between a normal line of the inclined surface and a normal line of the first surface is an angle different from 45 degrees.   A movement amount detection apparatus comprising a moving unit that movably holds at least one of the laser light source and the beam splitter so that an incident angle of the laser light reflected by the beam splitter to the moving body is variable.   The angle adjustment part which controls the said moving part and adjusts the angle with respect to the normal line of the said 1st surface of the said laser beam reflected by the said beam splitter and incident on a said 1st surface is provided. Movement amount detection device.   The movement amount detection device according to claim 5, wherein the angle adjustment unit adjusts the angle so that the movement amount calculated by the calculation unit exceeds a threshold for a predetermined time or more.