JP2008134104A - Position detection device and position detection program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection device and a position detection program capable of detecting an accurate position without forming a pattern for absolute position detection on the surface of a detection object, or even when a moving range of the detection object is wide. <P>SOLUTION: A reading part reads a piece of paper, to acquire a read image (150). Data in a comparison domain whose one side agrees with an origin position are extracted from registered image data as comparison data (152, 154), to thereby perform comparison processing (156). Then, it is determined whether collation by comparison is established or not by whether a normalized score is higher than a threshold or not on condition that the maximum value of a correlation value is higher than a threshold (158). In the case of negation, a comparison domain is updated (160, 154, 156), and in the case of affirmation, a position from which the comparison data are extracted is specified as a position on the piece of paper read by the reading part (162), and the specified position of the reading part is displayed on a display (164). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position detection device and a position detection program.

  Conventionally, an absolute encoder that detects an absolute position such as an optical type or a magnetic type is known. These absolute encoders detect the absolute position by reading a position detection pattern formed on the rotating plate or scale with a sensor. For example, in the case of an optical type, the pattern for detecting the absolute position is formed by transferring an original plate on which a pattern is formed onto glass or the like. However, the formation of the pattern for detecting the absolute position in this way becomes more difficult as the moving range of the rotating plate or scale as the position detection object becomes wider and the position detection accuracy becomes higher.

In contrast, a plurality of detection scales on which absolute position detection patterns are drawn and a detection head provided with the same number of pickups as the detection scales are moved relative to each other, and two adjacent detection scales are Detection is achieved by ensuring a range where overlap can be detected by the pickup (overlap detection range), switching pickup data used for detection output in this overlap detection range, and performing correction to ensure the continuity of the detection output. A technique for extending the length at which an absolute position can be measured without being affected by an error associated with scale connection is known (see Patent Document 1).
JP 2005-337757 A

  The present invention has been made in the background art described above, and does not form an absolute position detection pattern on the surface of the detection target object, and even when the movement range of the detection target object is wide, an accurate position is provided. It is an object of the present invention to obtain a position detection device and a position detection program that can detect an error.

  In order to achieve the above object, the invention according to claim 1 reads an object in which unique features having randomness are distributed on a surface, and a unique feature distributed in the reading region using a part of the surface as a reading region. A reading means, and at least one of the object and the reading means is arranged to move relative to the other of the object and the reading means, and on the surface of the object Storage means for storing the position on the surface of the object corresponding to the feature data and the feature data indicating the characteristic features to be distributed and a predetermined reference position as a reference, and the read by the reading means Based on the comparison result between the reading data indicating the unique characteristics of the reading area and the characteristic data stored in the storage unit, at least one of the object and the reading unit is the Detecting means for detecting the position of the reading area on the surface of the object relative to the reference position when the object is moved relative to the other of the object and the reading means. .

  The configuration of the position detection device is a configuration in which the reading unit moves relative to the object, a configuration in which the object moves relative to the reading unit, and a configuration in which both the object and the reading unit move relative to each other. Either may be used.

  The object can be composed of a paper piece of a predetermined shape, a paper piece of a predetermined shape whose surface is protected by a transparent protective film, or a polished glass of a predetermined shape. In this case, the predetermined shape is a long shape or a disk shape. It can be.

  The reading unit can read the reading region by receiving transmitted light or reflected light of the light irradiated on the surface of the object.

  The detection means is distributed over a part of the area on the surface of the object extracted from the read data indicating the unique characteristics of the reading area read by the reading means and the characteristic data stored in the storage means Based on the determination means for determining whether or not the correlation value with the comparison data representing the characteristic to be determined is greater than or equal to a predetermined value, and the comparison data determined by the determination means that the correlation value is greater than or equal to the predetermined value, The reading unit may be configured to include a specifying unit that specifies a position of the reading area on the surface of the object with reference to a reference position.

  The determination unit is configured to move the partial area from a predetermined position in a forward direction and a backward direction corresponding to the relative movement direction by a predetermined pixel pitch until a correlation value between the read data and the comparison data becomes equal to or greater than a predetermined value. The specifying means moves from at least one direction, based on a product of the number of pixels and the length of one pixel from a predetermined position to the position where the correlation value between the read data and the comparison data is equal to or greater than a predetermined value. The position of the reading area with reference to the reference position can be specified.

  The predetermined pixel pitch is equal to or smaller than the pixel corresponding to the width in the moving direction of the partial area, and is preferably one pixel from the viewpoint of resolution.

  Further, the predetermined pixel pitch is a half width of the moving direction of the partial area until the correlation value approaches a predetermined value to reduce the number of movements of the partial area. The width may be narrowed as it approaches a predetermined value.

  The invention according to claim 8 is based on feature data indicating a unique characteristic having randomness distributed on the surface of the object and a predetermined reference position, and on the surface of the object corresponding to the feature data. Based on the result of comparison between the storage step for storing the position in advance, the read data indicating the unique feature of the reading area read by the reading means, and the feature data stored in advance, the object and The reference position when at least one of the reading means for reading a unique feature distributed in the reading area using a part of the surface of the object as a reading area moves relative to the other of the object and the reading means. And a detection step for detecting a position of the reading area on the surface of the object with reference to the position.

  As described above, according to the present invention, since an object in which a unique characteristic having randomness is distributed is used, a pattern for detecting an absolute position is not formed on the surface, and the object to be detected is also detected. Even when the movement range is wide, it is possible to detect the accurate position of the detection target with the reference position as a reference.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 shows an overview of an embodiment of the system 12. A reading unit 20 is supported on the horizontally arranged table 14 so as to be movable in the arrow “+” direction and the arrow “−” direction. The reading unit 20 is moved by a nut fixed to the reading unit 20, a ball screw screwed to the nut, a drive unit 16 including a servo motor that rotates the ball screw, and a CNC (numerical control device) 18. The reading unit 20 has a function of reading an object with a predetermined resolution (for example, 400 dpi).

  An operation panel 22 is connected to the CNC 18. The operation panel 22 includes a display, a keyboard, a power switch, and the like (not shown).

  In parallel with the table 14, an object mounting table 24 on which an object to be read is fixed is provided, and a partial area of the object is read by the reading unit 20.

  Further, the system 12 includes an analog / digital (A / D) converter 26 connected to a reading unit 20 that converts an analog signal into a digital signal, a CPU, a RAM, a ROM, a nonvolatile memory, an input / output interface, and the like. The signal processing unit 28 is composed of a computer. The signal processing unit 28 is connected to the reading unit 20 and controls reading processing of the reading unit 20. In addition, the signal processing unit 28 has a function of representing the read object with a predetermined gradation (for example, 8-bit gray scale).

  In the system 12, the signal output from the reading unit 20 by reading the object is processed by the A / D converter 26 and the signal processing unit 28, and the absolute position of the reading unit 20 based on the origin position which is the reference position. Is to be detected. The absolute position of the reading unit 20 is used for feedback control of the CNC 18 and the like.

  As shown in FIG. 2, a paper piece 30 covered with a transparent protective film as an object is fixed to the object mounting table 24. The piece of paper 30 has a size including at least the entire range of the area that can be read by the reading unit 20 by movement.

  The reading method of the reading unit 20 is a reflected light reading type, and the reading unit 20 receives a light emitting element 20A that irradiates light on the paper piece 30 and light emitted from the light emitting element 20A and reflected by the paper piece 30; The image pickup device 20B is composed of a CCD or the like in which a large number of light receiving elements that output signals according to the amount of received light are arranged.

  The feature having randomness distributed over the entire surface of the paper piece 30 is read in advance by a flatbed scanner 32 as shown in FIG. 3 and stored in a nonvolatile memory provided in the signal processing unit 18. Has been. That is, the scanner 32 has the same resolution and signal as the above-described reading unit 20 in terms of the characteristics of the paper piece 30 placed on the document table (not shown), for example, 32 dots (about 2 mm) × the total length of the table 14. A function of reading with the same gradation (for example, 8-bit gray scale) as the processing unit 18 is provided. Registered image data in which feature data representing a unique characteristic having randomness distributed on the surface of the paper piece 30 obtained by reading and data indicating the position of the feature are associated with each other is provided in the signal processing unit 18. Stored in non-volatile memory. The origin position is determined at the end of the pixel corresponding to this feature data.

  Next, the position detection routine of the reading unit 20 will be described with reference to the flowchart of FIG. This position detection routine is executed when the position of the reading unit 20 immediately before the position detection routine is unknown, such as immediately after the system 12 is turned on. A program of this position detection routine is stored in the ROM of the signal processing unit 18.

  In step 150, the reading unit 20 is moved, and the reading unit 20 reads the surface of the paper piece 30 and has a size of 64 × 64 dots (about 4 mm × about 4 mm) as shown in FIG. Import image data.

  In step 152, one side of the comparison area is matched with the origin O position of the registered image data.

  In step 154, data in the comparison area in which one side as shown in FIG. 5 is made coincident with the origin O position is extracted from the registered image data as comparison data.

  FIG. 6A shows an image obtained by visualizing the comparison data (correcting the contrast so that visual confirmation is easy).

  Since it is impossible to control the entanglement of the fibrous material forming the paper piece 30 at the time of manufacturing, the entanglement of the fibrous material forming the paper piece 30 can be regarded as random, and each paper piece has a unique characteristic. is there. The entanglement of the fibrous material forming the paper piece 30 can be observed using a transmission light microscope. In the “comparison image” shown in FIG. 6 (A), although the entanglement of the fibrous material cannot be confirmed, it is caused by the randomness of the entanglement of the fibrous material (the surface of the paper caused by various conditions when the paper is rolled). (There is a possibility that the unevenness is also affected.) Since a random light and dark pattern reflecting a random change in the transparency of the paper is generated, the comparison data corresponding to the “comparison image” is stored in the comparison area on the paper piece 30. It can be confirmed that the information represents a characteristic unique to the above, that is, information representing a random change in the transparency in the comparison region on the paper piece 30.

  FIG. 6B shows an image obtained by visualizing the read data of the reading area read by the reading unit 20 used for position detection. This read data represents a random change in the transparency of the paper piece 30 within the read area.

  In step 156, a comparison process is performed. Hereinafter, the comparison process will be described with reference to the flowchart of FIG.

  In the comparison process according to the first embodiment, data corresponding to an area (calculation target area) having the same size as the comparison area is extracted from the data of the read image of the reading area (illustrated in FIG. 6B as an example) The calculation of the correlation value between the data and the comparison data of the comparison image (shown in FIG. 6A as an example) is repeated while moving the position of the calculation target region. Therefore, in the next step 170, the data extraction position (the position of the calculation target area) in the reading area is initialized.

  In step 172, data of the same size as the comparison area located at the set data extraction position (calculation target data) is extracted from the data of the reading area. In step 174, the correlation value between the comparison data and the calculation target data extracted in step 172 is calculated by the normalized correlation method according to the following equation (1), and the correlation value obtained by the calculation is stored in a RAM or the like. .

Where F is a comparison image (a set of comparison data), fi is a brightness value of each pixel of the comparison image, N is the total number of pixels of the comparison image (and a partial region of the read image), and G is a partial region of the read image ( ), Gi is the brightness value of each pixel in the partial area of the read image, f _AVE is the average value of the brightness values of the individual pixels in the comparison image, and g _AVE is the brightness value of each pixel in the partial area of the read image Is the average value.

  In the next step 176, it is determined whether or not the calculation target area has scanned the entire reading area. If the determination is negative, the process proceeds to step 178, the data extraction position is moved vertically or horizontally by one dot, and then the process returns to step 172. Thereby, steps 172 to 178 are repeated until the determination in step 176 is affirmed. In the first embodiment, since the comparison area is 32 × 32 dots and the reading area is 64 × 64 dots, the correlation value is calculated as (64−32 + 1) × (64−32 + 1) = 1089 times. Correlation values are obtained.

When the calculation of the correlation value is completed, the determination in step 176 is affirmed and the process proceeds to step 180, and the maximum value is extracted from the large number of correlation values obtained by the above calculation. In the next step 182, after calculating the standard deviation and average value of a large number of correlation values, the calculated standard deviation / average value and the maximum value of the correlation value obtained in step 180 are expressed by the following equation (2). By substituting each, the normalized score of the maximum correlation value is calculated.
Normalized score = (maximum correlation value-average correlation value) / standard deviation of correlation value (2)
In general, as the size of the comparison region (specifically, the region for which the correlation value is calculated) increases, the accuracy of the match determination improves. In the first embodiment, the size of the comparison area at a reading resolution of 400 dpi is 32 × 32 dots (about 2 mm × about 2 mm). It has been found from experimental results that if the comparison area is made smaller than the size, the accuracy of judgment of coincidence decreases. Even if the comparison area is made larger than the size, the degree of accuracy improvement is small. Therefore, it is not necessary to use an expensive and troublesome microscope for reading, and it is practical to use a reading device (such as a commercially available inexpensive scanner) capable of reading at a resolution of about 400 dpi.

  Also, when the comparison area is read, if the output signal of the light receiver becomes saturated due to excessive light incident on the light receiver, etc., the change in transparency in the comparison area represented by the comparison data obtained by the reading will occur. Since comparison data that accurately represents a change in transparency in the comparison area cannot be obtained, such as when the comparison area is partially whitened, it is desirable to appropriately suppress exposure when reading the comparison area.

  Next, in step 158, which is a determination means, whether or not collation by comparison is established depending on whether or not the maximum correlation value obtained in step 180 is equal to or greater than a threshold value and whether the normalized score calculated in step 182 is equal to or greater than a threshold value. Determine whether or not. If the result is negative, the process proceeds to step 160, and the comparison area is updated. As shown in FIG. 8A, the comparison area is an area that is moved by a predetermined movement width in a direction away from the origin O. The predetermined movement width is desirably one dot width.

  The predetermined moving width is, for example, half the width of the comparison area (16 dots (about 1 mm) until the maximum correlation value is equal to or larger than the predetermined value and the normalized score is equal to or larger than the predetermined value. ), The width may be narrowed as the maximum correlation value and the normalized score increase.

  Next, the process proceeds to step 154, and for example, data in the comparison area whose one side is matched with the position of “1” indicated by the shaded area in FIG. 8A is extracted from the registered image data as comparison data.

  In step 156, comparison with the updated comparison data is performed.

  The processing in steps 160, 154, and 156 is performed until the determination in step 158 is affirmed. For example, when the comparison area is moved 12 dots away from the origin O, it is shown as a shaded area in FIG.

  On the other hand, if the determination in step 158 is affirmative, the process proceeds to steps 162 and 164. In step 162 as identification means, the position of the paper piece 30 read by the reading unit 20 is specified based on the position of the comparison area, and in step 164, the position of the specified reading unit 20 is displayed on the display.

  The position of the reading unit 20 may be obtained by calculating the product of the number of movements of the comparison region in the direction away from the origin O and the predetermined movement width until the correlation value becomes equal to or greater than a predetermined value.

  Next, a position detection routine during movement of the reading unit 20 according to the first embodiment will be described with reference to the flowchart of FIG. A program of this position detection routine is stored in the ROM of the signal processing unit 18.

  In Step 200, the reading unit 20 is moved, and reading region data having a size of, for example, 64 × 64 dots (about 4 mm × about 4 mm) obtained by reading the surface of the paper piece 30 is captured by the reading unit 20.

  In step 202, the comparison area (+) and the comparison area (-) are made to coincide with the comparison area in which collation was established at the time of the previous position detection.

  In steps 204, 206 and 208, the comparison area (+) is moved by a predetermined movement width in the direction of the arrow “+”, and comparison data corresponding to the comparison area (+) after the movement is extracted from the registered image data. Comparison processing is performed.

  In step 210, it is determined whether or not collation by comparison has been established, and if negative, the process proceeds to steps 212, 214, and 216. In steps 212, 214, and 216, the comparison area (−) is moved by a predetermined movement width in the direction of the arrow “−”, and comparison data corresponding to the comparison area (−) after the movement is extracted from the registered image data. Comparison processing is performed.

  The predetermined movement width is desirably a one-dot width, but the predetermined movement width is such that the maximum correlation value is equal to or greater than a predetermined value and the normalized score is equal to or greater than a predetermined value. Until it becomes, for example, the width of the comparison area may be reduced as the maximum value of the correlation value and the normalized score are increased as a half width (16 dots (about 1 mm)).

  In step 218, it is determined whether or not collation by comparison is established, and the processing of step 204 to step 216 is performed until affirmative. If the determination in step 210 or 218 is affirmative, the process proceeds to step 220 or 222. In step 220, the position of the comparison area (+) or comparison area (−) where the collation is established is specified as the position of the paper piece 30 read by the reading unit 20, and in step 222, the position of the specified reading unit 20 is displayed. To display.

  As described above, in the first embodiment, it is determined whether or not the correlation value between the read data indicating the unique characteristics of the reading area read by the reading unit 20 and the comparison data is greater than or equal to a predetermined value. Thus, the position of the reading unit 20 is specified, so that the paper piece 30 does not have an absolute position detection pattern, and even when the range of relative movement between the reading unit 20 and the paper piece 30 is wide, the object mounting table 24 is provided. It is possible to specify an accurate parallel movement position of the reading area in which the paper piece 30 fixed to is read.

Further, since the paper piece 30 is optically readable, the first embodiment can be easily implemented.
(Second Embodiment)
In the second embodiment, a case where the moving direction and moving speed of the reading unit 20 can be detected will be described.

  The configuration of the system 12 in this case is the same as that of the system 12 (see FIGS. 1 and 2) shown in the first embodiment, and a description thereof is omitted here.

  In the system 12 according to the second embodiment, the position detection executed when the position of the reading unit 20 immediately before the position detection routine is unknown is performed in the same manner as in the first embodiment. Omitted.

  A position detection routine when the reading unit 20 moves according to the second embodiment will be described with reference to the flowchart of FIG. A program of this position detection routine is stored in the ROM of the signal processing unit 18.

  In step 300, the reading unit 20 is moved, and reading region data having a size of, for example, 64 × 64 dots (about 4 mm × about 4 mm) obtained by reading the surface of the paper piece 30 by the reading unit 20 is captured.

  In step 302, the comparison area is matched with the comparison area in which the collation was established at the time of the previous position detection.

  In step 304, the moving direction and moving amount of the comparison area are determined based on the detected moving direction and moving speed of the reading unit 20.

  If the movement direction is the arrow “+” direction, the process proceeds to step 306, the comparison area is moved in the arrow “+” direction according to the movement speed, and the process proceeds to step 310. If the movement direction is the direction of the arrow '-', the process proceeds to step 308, the comparison area is moved in the direction of the arrow '-' according to the movement speed, and the process proceeds to step 310. If there is no movement, the process proceeds to step 310 without changing the comparison area.

  In step 310, data in the comparison area is extracted from the registered image data as comparison data, and in step 312, the above-described comparison process is performed.

  In step 314, it is determined whether or not collation by comparison has been established. If affirmative, the process proceeds to steps 316 and 318. In step 316, the position of the comparison area is specified as the position of the paper piece 30 read by the reading unit 20, and in step 318, the specified position of the reading unit 20 is displayed on the display.

If the determination in step 314 is negative, the process proceeds to step 320 to perform position detection (see the flowchart of FIG. 4) that is performed when the position of the reading unit 20 immediately before the position detection routine is unknown. The determination in step 314 is negative when a detection error of the moving direction and moving speed of the reading unit 20 occurs, or when the paper piece 30 is contaminated.
(Third embodiment)
Next, an embodiment in which a position detection routine executed in the signal processing unit 18 of the first embodiment and the second embodiment is executed by a personal computer (PC) will be described.

  As shown in FIG. 11, the PC 55 includes a display 58 that displays various types of information and a PC main body 59. A storage device 54 for mounting the storage medium 52 is provided on the surface side of the PC main body 59.

  Here, the position detection function of the reading unit 20 can be realized by a program 50 that can be executed in the PC 55.

  As the program 50 that can be executed by the PC 55, the position detection routine program used in the signal processing unit 18 may be converted into a code that can be executed by the PC 55.

  The program 50 and data used by the program 50 can be stored in a storage medium 52 that can be read by the PC 55 in advance, and an HDD (Hard Disk Drive) 62 and a ROM (Read Only Memory) 62 described later in the PC 55. 61 may be stored in advance.

  The storage medium 52 causes a change state of energy such as magnetism, light, electricity and the like to the reading device 54 provided in the hardware resource of the PC 55 according to the description content of the program, and a signal corresponding thereto. The contents of the program description can be transmitted to the reading device 54 in a format.

  Examples of such a storage medium 52 include a magneto-optical disk 52A, an optical disk 52B, a magnetic disk 52C, and a memory 52D that can be attached to the PC main body 59. An example of the memory 52D includes an IC card and a memory card. These storage media 52 may be either portable or non-portable.

  The reader 54 includes a magneto-optical disk device 54A for reading various data stored on the magneto-optical disk 52A, an optical disk device 54B for reading various data stored on the optical disk 52B, and a magnetic disk 52C. There is a magnetic disk device 54C for reading various data stored in the disk.

  As shown in FIG. 12, the PC 55 includes a CPU (Central Processing Unit) 60, a ROM 61, and a RAM (Random Access Memory) 63. The CPU 60, ROM 61, and RAM 63 are connected to each other through a host bus 71 composed of a CPU bus or the like so as to exchange signals. The configuration including the CPU 60, the ROM 61, and the RAM 63 has the same function as that of the signal processing unit 18 described above.

  The CPU 60 has the same function as the CPU of the signal processing unit 18 described above, and executes processing according to the program 50. The ROM 61 stores programs used by the CPU 60, calculation parameters, a program 50, and the like. The RAM 63 stores programs used in the execution of the CPU 60, parameters that change as appropriate during the execution, and the like. The ROM 61 and RAM 63 function as the ROM and RAM of the signal processing unit 18 described above.

  The host bus 71 is connected to an external bus 66 such as a peripheral component interconnect / interface (PCI) bus via a bridge 64 so as to exchange data and signals.

  The PC 55 is provided with a keyboard 60, a pointing device 65 such as a mouse, a display 58, an HDD 62, a reading device 54, a connection port 67, a communication unit 70, a reading unit 20, and a data output unit 56.

  These keyboard 60, pointing device 65 such as a mouse, display 58, HDD 62 for storing various data, reading device 54, connection port 67, communication unit 70, reading unit 20, and data output unit 56 are an interface 68, The external bus 66, the bridge 64, and the host bus 71 are connected to the CPU 62 so as to be able to exchange signals.

  The keyboard 60 and the pointing device 65 are input devices operated by an operator. The display 58 includes a liquid crystal display device or a CRT (Cathode Ray Tube), and is a device that displays various types of information as text or image information. These have functions equivalent to the operation panel 22 of the system 12.

  The reading unit 20 may be configured as a physically different device and may be connected to be able to exchange signals with each other by a cable or the like.

  The storage medium 52 is attached to the reading device 54, whereby various data such as the stored program 50 is read by the reading device 54. Under the control of the CPU 60, the reading device 54 reads the program 50 and various data stored in the attached storage medium 52. The position detection routine program and data read by the reading device 54 are stored in the RAM 63 via the interface 68, the external bus 66, the bridge 64, and the host bus 71 under the control of the CPU 60.

  The connection port 67 is a port for connecting an external connection device 69 such as a scanner connected to the PC 55, and has a connection unit such as USB or IEEE1394. The communication unit 70 is a device for exchanging data and signals with an external device via a wired communication network or a wireless communication network (not shown).

  The data output unit 56 is an output device for outputting various data, and can be a printer, for example.

  In such a PC 55, when the storage medium 52 is attached to the reading device 54, the CPU 60 reads the program 50 stored in the storage medium 52 and stores it in the RAM 63. If the program 50 is stored in the HDD 62 or the ROM 61, the CPU 60 reads out the program 50 stored in the HDD 62 or the ROM 61 and stores it in the RAM 63.

  The CPU 60 executes a position detection routine program of the program 50 stored in the RAM 63. When the program 50 is executed by the CPU 60, the processing routines shown in FIGS. 4, 9, and 10 are executed by the CPU 60, and position detection is executed in the PC 55 in the same manner as the signal processing unit 18. .

  In each of the above embodiments, the reading unit 20 is a reflected light reading type, but may be a transmitted light reading type. In this case, both the object mounting table 24 and the paper piece 30 are made of a transmissive member, and the object mounting table 24 and the paper piece 30 are arranged.

  Further, the object placed on the object mounting table 24 may not be the paper piece 30 as long as the characteristics having randomness such as polished glass are distributed on the surface, and the paper piece 30 is covered with a transparent protective film. It does not have to be broken.

  Also, instead of reading using the scanner 32, the reading unit 20 moves along with the movement of the reading unit 20 over the entire movable direction, thereby reading a feature having randomness distributed over the entire surface of the paper piece 30. Registered image data in which feature feature data and feature position data are associated with each other may be stored in the signal processing unit 18.

  Moreover, although the example which moves the reading part 20 was demonstrated above, you may move the paper piece 30. FIG.

  In the above description, the comparison area and the reading area have been described as having a rectangular shape (specifically, a square shape). However, the present invention is not limited to this, and the rectangular area, trapezoidal shape, triangular shape, circular shape, elliptical shape, linear shape (for example, Any shape such as a very flat rectangular shape having a width of 1 to several dots can be employed. However, even if the shape of the region is complicated, it does not contribute to improving the accuracy of the authenticity determination. Therefore, unless there are special circumstances, it is desirable that the shapes of the comparison region and the reading region are simple rectangles or circles.

  When the comparison area and the reading area are circular, if the center of the reading area can be overlapped with the center of the comparison area by some method, the same processing as in the case of the rectangular shape can be performed by converting to the polar coordinate format. However, in general, a reading device such as a scanner has a structure in which a line sensor and a document are relatively moved in a sub-scanning direction (a direction orthogonal to the sensor arrangement of the line sensor) to perform two-dimensional reading, and data is output from the reading device. Since the order is also an order suitable for taking in the data of the rectangular area, there is little merit of making the comparison area and the reading area both circular, and the process of superimposing the centers of both areas is not a simple process. Practically, it is appropriate that the comparison area and the reading area are rectangular.

  In addition, when a random feature of an object (paper piece 30 in each embodiment) arranged on the object mounting table 24 is a characteristic accompanied by a color change, a plurality of characteristics are read when the feature is optically read. It is effective to separate and read the color components, but as a characteristic characteristic of the paper piece 30 as an object, random changes in the transparency of the paper due to the randomness of the entanglement of the fibrous material forming the paper piece 30 When used, color information is not necessary, and it is sufficient to read with a single color gray scale as in each embodiment. Further, the resolution of gradation in reading may be 256 gradations (8 bits) if the object is a paper piece 30. Even if the gradation resolution in reading is further increased, the accuracy of position detection is hardly improved.

  Even a commercially available inexpensive reading device can usually read with a gradation resolution of at least 8 bits. However, if for some reason compression of the number of bits of the gradation value is required, for example, the gradation value between shadow and highlight Instead of allocating bits evenly (linearly) to changes in color, more in the lightness range (lightness range close to highlights) where gradation value changes corresponding to random changes in paper transparency are distributed If the number of bits of the gradation value is assigned, even if the number of bits of the gradation value is 6 bits or 4 bits, the number of bits of the gradation value is 8 bits and the bits are assigned evenly with respect to the change of the gradation value. The same detection accuracy can be obtained. In addition, lossy compression such as JPEG may be applied to data obtained by reading.

  Moreover, although the example which memorize | stores registration image data in the signal processing part 18 was demonstrated above, it is not limited to this, You may memorize | store registration image data in the database connected via the network.

  Furthermore, although the example in which the size of the reading area is larger than the size of the comparison area has been described above, the present invention is not limited to this, and the size of the comparison area is made larger than the size of the reading area, The calculation of the correlation value between the partial area having the same size as the reading area and the reading area may be repeatedly performed while shifting the position of the partial area in the comparison area. However, in this case, there is a disadvantage that the capacity of the comparison data is increased, and it is preferable to make the size of the reading area larger than the size of the comparison area because the storage capacity for storing the comparison data can be saved.

  Further, each embodiment may be applied to an apparatus for detecting a position or an angle on a circular arc in the rotation direction of a rotating disk-shaped object mounting table 24 ′ as shown in FIG. 13.

FIG. 1 shows an outline of a configuration of a first embodiment of a system to which an object reading unit is applied. FIG. 2 shows an outline of the configuration of the object reading unit. FIG. 3 is a schematic configuration diagram of a scanner that reads a piece of paper. FIG. 4 shows a position detection routine of the reading unit when the position of the reading unit immediately before the position detection routine is unknown. FIG. 5 is an image for extracting a comparison region in which one side coincides with the origin position. 6A is a comparative image, and FIG. 6B is an image of a read image read by the reading unit. FIG. 7 shows a comparison routine in position detection. FIG. 8A is an image in which a comparison image is extracted by moving the comparison area from the origin in the direction of the 1-dot arrow “+”. FIG. 8B is a comparison in the direction of the 12-dot arrow “+” from the origin. It is an image in which a comparison image is extracted by moving an area. FIG. 9 shows a position detection routine for detecting the position of the moving reading unit in the first embodiment. FIG. 10 shows a position detection routine for detecting the position of the moving reading unit according to the second embodiment. FIG. 11 is a schematic diagram showing a case where position detection is executed by a personal computer. FIG. 12 is a schematic block diagram showing a configuration in the personal computer that performs position detection. FIG. 13 shows a schematic configuration of a modification of the object.

Explanation of symbols

12 System 14 Table 16 Drive unit 18 Signal processing unit 20 Reading unit 20A Light emitting device 20B Image sensor 22 Operation panel 24 Object placement table 26 Converter 30 Paper piece 32 Scanner 50 Program 52 Storage medium 54 Reading device 55 Personal computer 58 Display 67 Connection Port 69 Externally connected device 71 Host bus

Claims (8)

An object in which unique features having randomness are distributed on the surface, and a reading unit that reads the unique features distributed in the reading region using a part of the surface as a reading region, the object and the reading unit An object / reading means arranged so that at least one of the object and the other of the reading means moves relative to each other;
Storage means for storing the position on the surface of the object corresponding to the feature data, which is based on the feature data indicating the unique features distributed on the surface of the object and a predetermined reference position;
At least one of the object and the reading means is based on a comparison result between the reading data indicating the unique characteristics of the reading area read by the reading means and the characteristic data stored in the storage means. Detecting means for detecting a position on the surface of the object in the reading area based on the reference position when the object and the other of the reading means are moved relative to each other;
A position detecting device including:   The position detection device according to claim 1, wherein the object is configured by a piece of paper having a predetermined shape, a piece of paper having a predetermined shape whose surface is protected by a transparent protective film, or polished glass having a predetermined shape.   The position detection device according to claim 2, wherein the predetermined shape is a long shape or a disk shape.   The position detection apparatus according to claim 1, wherein the reading unit reads the reading region by receiving transmitted light or reflected light of light irradiated on a surface of the object.   The detection means is a partial area on the surface of the object extracted from the read data indicating the unique characteristics of the reading area read by the reading means and the characteristic data stored in the storage means Based on the determination means for determining whether or not the correlation value with the comparison data representing the characteristics distributed in the distribution is greater than or equal to a predetermined value, and the comparison data for which the correlation value is determined to be greater than or equal to the predetermined value 5. The position detection device according to claim 1, further comprising a specifying unit that specifies a position of the reading area on the surface of the object with reference to the reference position. The determination means includes a forward direction corresponding to the relative movement direction by a predetermined pixel pitch from the predetermined position until the correlation value between the read data and the comparison data is equal to or greater than a predetermined value. Move it in at least one direction of the return direction,
The specifying means determines the reference position from the product of the number of pixels and the length of one pixel from the predetermined position to the position where the correlation value between the read data and the comparison data is equal to or greater than a predetermined value. The position detection apparatus according to claim 5, wherein the position of the reading area is specified with reference to the position.   The position detection device according to claim 6, wherein the predetermined pixel pitch is equal to or smaller than a pixel corresponding to a width in the moving direction of the partial area. A storage step for preliminarily storing a position on the surface of the object corresponding to the feature data and the characteristic data indicating a unique characteristic having randomness distributed on the surface of the object and a predetermined reference position as a reference When,
Based on the comparison result between the read data indicating the unique characteristics of the reading area read by the reading means and the characteristic data stored in advance, the object and a part of the surface of the object are obtained. When at least one of the reading means for reading the unique features distributed in the reading area as a reading area moves relative to the object and the other of the reading means, the reading area of the reading area with reference to the reference position A detection step for detecting a position on the surface of the object;
The position detection program which makes a computer perform the process which has.