JP6082557B2 - Spectral sensor optical system adjustment method, optical system adjustment apparatus, and paper sheet identification apparatus - Google Patents

Description

  The present invention relates to a spectral sensor optical system adjustment method and optical system adjustment apparatus for adjusting the optical magnification and focus of an optical system with a spectral sensor including a lens and a prism, and a paper sheet identification apparatus using the spectral sensor. .

  Conventionally, in order to measure optical characteristics such as paper sheets, a spectrum sensor including an optical system including a lens and a prism and an image sensor such as a CCD that images a spectral spectrum obtained by the optical system has been used. ing. For example, a paper sheet to be measured is irradiated with light from a light source, and reflected light or transmitted light from the paper sheet is received by an optical system. When interference fringes are formed from the light received by the optical system using a prism or the like, the interference fringes are imaged by the image sensor. Since the captured interference fringe changes according to the optical characteristics of the paper sheet to be measured, the type and authenticity of the paper sheet can be determined based on the characteristics obtained from the interference fringe.

  For example, Patent Document 1 discloses a spectroscopic device that uses an optical system including a lens, a polarizer, a Wollaston prism, and the like. In order to perform measurement correctly using such an optical system, it is necessary to image an interference fringe with an appropriate optical magnification in a focused state on the image sensor.

Patent No. 3095167

  However, a spectrum sensor having an optical system including a prism has a problem that it is difficult to adjust the focal point and optical magnification. For example, when the optical system does not include a prism for forming an interference fringe and is configured only by a mirror or a lens, a reference chart is installed at a position where the measurement object is placed, and the imaging device passes through the optical system. The focal point and the like can be easily adjusted based on the image acquired in step (b). However, in an optical system that forms an interference fringe using a prism, such as a spectrum sensor, if a similar method is used for adjustment, a reference chart or the like is placed inside the prism. Since the reference chart or the like cannot be arranged in the prism, it is difficult to accurately specify the spatial position even if the prism is removed and the reference chart or the like is arranged at the spatial position where the interference fringes are generated.

  Unlike the case where a reference chart on which a scale or ladder pattern is drawn is picked up by an image sensor and adjustment is performed using this image, the focus and optical magnification are adjusted while checking interference fringes. It is also difficult to determine the adjustment amount.

  In the optical system that constitutes the spectrum sensor, there is a variation in the processing accuracy of the lens and the prism. Therefore, it is necessary to ensure the optical performance of the spectrum sensor by correctly adjusting the focal point and the optical magnification corresponding to the variation. For this reason, there has been a demand for a method and apparatus for easily and accurately adjusting the focal point and optical magnification with a spectrum sensor composed of a plurality of optical components.

  The present invention has been made in order to solve the above-described problems of the prior art, and is a spectrum sensor including a lens and a prism, and can easily and accurately adjust the optical magnification and focus of an optical system. It is an object of the present invention to provide an optical system adjustment method, an optical system adjustment apparatus, and a paper sheet identification apparatus using the spectrum sensor.

In order to solve the above-described problems and achieve the object, the present invention provides a spectrum sensor in which an interferometer including a polarizer and a birefringent element , a lens, and a line image sensor are sequentially arranged along an optical path from a light source. 1. An optical system adjustment method comprising: (1) a reference light incident step in which a reference light having a predetermined wavelength is incident on the interferometer by a reference light source; and (2) light collected by the lens via the interferometer. A light receiving step for receiving light by the line image sensor, (3) a spectral data generating step for generating spectral spectrum data by performing Fourier transform on the light received by the line image sensor, and (4) the steps (1) to (1) Based on the spectral data generated in (3), the distance between the line image sensor and the lens is automatically adjusted for focusing. And (5) forming an image on the line image sensor on the basis of the spectral data obtained by the steps (1) to (3) in the focused state in the step (4). A determination step of determining whether or not the optical magnification of the image is within a predetermined range; and (6) if it is determined in step (5) that the optical magnification is not within the predetermined range, on the basis of the spectral data, by automatically adjusting the distance between the line image sensor and the interferometer, the saw including a optical magnification adjustment step of adjusting the optical magnification to a predetermined magnification, the in the step (4) The steps (4) to (6) are repeatedly executed until it is determined that the optical magnification is within a predetermined range .

  Further, the present invention is the above invention, wherein, in the focus adjustment step, based on a change in peak intensity of spectral spectrum data when a distance between the line image sensor and the lens is changed, the line image sensor and the The distance between the lenses is automatically adjusted toward the distance when the peak intensity shows a maximum value.

In the optical magnification adjustment step according to the present invention, after the Fourier transform is performed on the light received by the line image sensor, the wavelength wavelength conversion is further performed to obtain the wavelength of the peak position of the spectral data. Te, based on the wavelength of the obtained wavelength and the reference light, the distance between the line image sensor and the interferometer, toward the distance when the wavelength of the peak position coincides with the wavelength of the reference light automatically It is characterized by adjusting.

  The present invention further includes an initial setting step in which the line image sensor and the lens are arranged at an initial position set apart by a predetermined distance in a direction closer to or away from the distance when focusing. In the focus adjustment step, focus adjustment is started while moving at least one of the line image sensor and the lens in a direction where the focus is achieved.

Further, the present invention is the optical system adjustment method of the spectrum sensor according to the above invention, in which an interferometer including a polarizer and a birefringent element, a lens, and a line image sensor are sequentially arranged along an optical path from a light source. (1) a reference light incident step in which a reference light having a predetermined wavelength is incident on the interferometer by a reference light source; and (2) light collected by the lens through the interferometer is received by the line image sensor. A light receiving step, (3) a spectral data generating step for generating spectral spectral data by performing Fourier transform on the light received by the line image sensor, and (4) the spectral generated by the steps (1) to (3). A focus adjustment step of automatically adjusting a distance between the line image sensor and the lens based on spectral data to adjust a focus; ) The step (the step (1 focus in a state combined with 4)) - (3 and the wavelength at the peak of the spectral data generated by), correctly said step in a state where the optical magnification is adjusted (1) A correction magnification calculation step for obtaining a correction magnification based on the wavelength of the peak position of the spectral data generated by (3), and (6) a frequency wavelength conversion table prepared in advance for adjusting the optical magnification. And a correction table creation step of creating a correction table in which each conversion coefficient is corrected at the correction magnification obtained in the step (5) .

The present invention also provides an interferometer including a polarizer and a birefringent element for forming an interference wave, a lens for condensing and focusing light emitted from the interferometer, and an image formed by the lens. A spectral sensor having a line image sensor for imaging interference fringes, an optical system adjustment device for adjusting an optical system, a reference light source capable of irradiating a reference light of a predetermined wavelength, and the reference to the interferometer Spectral spectrum data when the distance between the line image sensor and the lens is changed is generated by performing Fourier transform on the light received from the light source and receiving light by the line image sensor. Based on the change in peak intensity, the distance between the line image sensor and the lens is directed to the distance when the peak intensity shows a maximum value. The step of adjusting, in a state of focusing in about該工, after performing Fourier transform, the further frequency wavelength conversion performed on the light incident light is received by the line image sensor from the reference light source to said interferometer The wavelength of the peak position of the spectral data is obtained, and based on the wavelength and the wavelength of the reference light, it is determined whether or not the optical magnification of the image formed on the line image sensor is within a predetermined range. And when the optical magnification does not fall within a predetermined range in the step, the distance between the line image sensor and the interferometer is set to match the wavelength of the peak position with the wavelength of the reference light. And a control unit that repeatedly executes the step of automatically adjusting toward the distance until the optical magnification falls within a predetermined range .

Further, the present invention has been studied by an interferometer including a polarizer and a birefringent element for forming an interference wave, a lens for condensing and focusing light emitted from the interferometer, and the lens. A spectral sensor having a line image sensor for imaging an interference fringe, an optical system adjusting device for adjusting an optical system, a reference light source capable of irradiating a reference light of a predetermined wavelength, and the reference light source to the interferometer The spectrum image data is generated by applying Fourier transform to the light received by the line image sensor and generating spectral spectrum data, and changing the distance between the line image sensor and the lens. Based on the change in intensity, the distance between the line image sensor and the lens is directed to the distance when the peak intensity shows a maximum value. In the adjusting step, the light from the reference light source is incident on the interferometer while being focused in the step, the light received by the line image sensor is subjected to Fourier transform, and further subjected to frequency wavelength conversion. The wavelength at the peak position of the spectral spectrum data is obtained, and the ratio between the wavelength and the wavelength of the reference light is used as the correction magnification, and the data after the Fourier transform is prepared in advance to adjust the optical magnification. And a control unit that creates a correction table in which each conversion coefficient of the frequency / wavelength conversion table used for frequency / wavelength conversion is corrected with the correction magnification.

The present invention is also a paper sheet identification device for interferometer including a polarizer and a birefringent element for forming an interference wave, and for focusing the light emitted from the interferometer by focusing the light. A spectral sensor having a lens and a line image sensor that images an interference fringe imaged by the lens, and the optical system adjusting device according to the invention are provided.

  According to the present invention, using the light of a predetermined wavelength emitted from the reference light source, and performing focus adjustment based on the spectral spectrum acquired through the optical system, the degree of focus is quantified, The focus can be adjusted easily and accurately.

  Further, according to the present invention, similarly, adjustment is performed so that the optical magnification becomes a predetermined magnification based on the spectral spectrum acquired using the reference light source. Can be adjusted easily and accurately.

  Further, according to the present invention, the change in peak intensity appearing in the spectral spectrum data when the distance between the lens used for focus adjustment and the image sensor is changed is confirmed, and the distance between the lens and the image sensor is determined. Since the focus can be adjusted by setting the distance at which the peak intensity shows the maximum value, the focus can be adjusted easily and accurately.

  Further, according to the present invention, the change of the peak wavelength appearing in the spectral data when the distance between the interferometer for forming the interference fringes and the image sensor is changed is confirmed, and the interferometer and the image sensor are Since the distance between them is the distance at which the peak wavelength coincides with the wavelength of the reference light from which the spectral spectrum is acquired, the optical magnification can be adjusted easily and accurately.

  Further, according to the present invention, the lens used for focus adjustment is arranged at an initial position set away from the distance between the lens and the image sensor at the time of focusing or an initial position set close to the lens. The direction in which the lens should be moved to adjust the focus becomes clear, and it is not necessary to determine the direction in which the lens should be moved when starting the focus adjustment.

  Further, according to the present invention, the correction magnification is obtained from the ratio between the wavelength of the reference light source and the peak wavelength appearing in the spectral spectrum data acquired using the reference light source, and a correction table is created. Therefore, it is not necessary to adjust the distance between the interferometer and the image sensor in order to adjust the optical magnification.

FIG. 1 is a functional block diagram illustrating the configurations of the spectrum sensor unit and the optical system adjustment control unit according to the first embodiment. FIG. 2 is a functional block diagram illustrating a configuration example of the paper sheet identification apparatus including the spectrum sensor unit according to the first embodiment. FIG. 3 is a diagram illustrating a method of using the spectrum sensor unit according to the first embodiment. FIG. 4 is a diagram for explaining the mechanism of the optical system adjustment unit of the spectrum sensor unit according to the first embodiment. FIG. 5 is an explanatory diagram for explaining details of the mechanism of the optical system adjustment unit of the spectrum sensor unit according to the first embodiment. FIG. 6 is an explanatory diagram for explaining an optical system adjustment method of the spectrum sensor unit according to the first embodiment. FIG. 7 is an explanatory diagram for explaining a method of adjusting the focus of the optical system of the spectrum sensor unit according to the first embodiment. FIG. 8 is an explanatory diagram for explaining a method of adjusting the optical magnification of the optical system of the spectrum sensor unit according to the first embodiment. FIG. 9 is a flowchart illustrating a procedure for adjusting the focal point and optical magnification of the optical system of the spectrum sensor unit according to the first embodiment. FIG. 10 is a functional block diagram illustrating the configurations of the spectrum sensor unit and the optical system adjustment control unit according to the second embodiment. FIG. 11 is a diagram illustrating a method of correcting the optical magnification of the optical system of the spectrum sensor unit according to Example 2. FIG. 12 is a flowchart illustrating a procedure of focus adjustment and optical magnification correction of the optical system of the spectrum sensor unit according to the second embodiment. FIG. 13 is a functional block diagram illustrating a configuration example in the case where the spectrum sensor unit includes a storage unit that stores data relating to adjustment of the optical system. FIG. 14 is a schematic diagram for explaining an example of the structure of a spectrum sensor unit having an adjustment reference light source. FIG. 15 is a functional block diagram illustrating a configuration example of the adjustment device when the adjustment reference light source is provided separately from the spectrum sensor unit. FIG. 16 is a functional block diagram illustrating a configuration example when a spectrum sensor unit that does not have an adjustment reference light source is used in a paper sheet identification apparatus. FIG. 17 is a schematic diagram for explaining an arrangement example of adjustment reference light sources when a spectrum sensor unit that does not have an adjustment reference light source is used.

  Exemplary embodiments of an optical system adjusting method, an optical system adjusting apparatus, and a paper sheet identifying apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In Examples 1 and 2 shown below, a paper sheet identification device for identifying the type and authenticity of a paper sheet is used as an example of a spectrum sensor unit used for acquiring optical characteristics of the paper sheet. An optical system adjustment method, an optical system adjustment apparatus, and a paper sheet identification apparatus for a spectrum sensor according to the invention will be described.

  First, the configuration of the spectrum sensor unit and the optical system adjustment control unit according to the first embodiment will be described. FIG. 1 is a functional block diagram illustrating device configurations of the spectrum sensor unit 10 and the optical system adjustment control unit 20 according to the first embodiment. The spectrum sensor unit 10 is a unit incorporated in a paper sheet identification device to be described later. The optical system adjustment control unit 20 is a control unit for automatically adjusting the focal point and optical magnification of the optical system of the spectrum sensor unit 10. The display unit 30 is a device such as a liquid crystal display for displaying a processing result of the optical system adjustment control unit 20.

  The spectrum sensor unit 10 includes an adjustment reference light source 11, an optical system unit 12, an optical system adjustment unit 13, and an image sensor 14. The adjustment reference light source 11 has a function of irradiating reference light having a specific wavelength when adjusting the focal point and optical magnification of the optical system unit 12. The optical system unit 12 is configured by optical components such as a polarizing element, a birefringent prism, and an imaging lens, and has a function of forming an interference fringe from incident light and forming an image on the imaging element 14. The optical system adjustment unit 13 operates under the control of the optical system adjustment control unit 20 and has a function of adjusting the focal point and optical magnification of the optical system unit 12. The image sensor 14 is a line image sensor using a CCD or the like, for example, and has a function of imaging the interference fringes imaged by the optical system unit 12.

  The optical system adjustment control unit 20 includes a storage unit 21 and a control unit 22, and images the interference fringes formed by the optical system unit 12 using the reference light emitted from the adjustment reference light source 11 by the imaging device 14. Then, based on the data obtained from the interference fringes, a shift in focus and optical magnification is detected. Then, the optical system adjustment unit 13 is controlled to automatically adjust the focal point and optical magnification of the optical system unit 12. The storage unit 21 is a storage device such as a hard disk or a non-volatile memory, and includes spectral spectrum data 21a, peak data 21b by lens position, frequency / wavelength conversion table 21c, and interferometer position correction table 21d by reference light source. Remember. The spectral spectrum data 21a is data obtained by performing Fourier transform and frequency / wavelength conversion processing on the data imaged by the image sensor 14. The lens position-specific peak data 21b is data used at the time of focus adjustment of the optical system unit 12, and the position of a lens 12h described later is associated with the maximum value of the intensity of the spectral spectrum data 21a at the lens position. Is remembered. The frequency / wavelength conversion table 21c is data used in the process of converting the frequency into the wavelength when generating the spectral data 21a, and stores the frequency and the wavelength in association with each other. The interferometer position correction table 21d for each reference light source is data used when adjusting the optical magnification of the optical system unit 12, and for each reference light source, the wavelength obtained from the spectral spectrum data 21a, the interferometer 12i and the image sensor 14 described later. The relationship between the distances is stored. However, for the frequency / wavelength conversion table 21c, for example, when the relationship between the frequency and the wavelength is easily expressed by a mathematical expression, this mathematical expression may be used instead of the table.

  The control unit 22 is a control unit that controls the entire optical system adjustment control unit 20, and includes an adjustment reference light source control unit 22a, a spectral spectrum data creation unit 22b, a focus position detection unit 22c, a lens adjustment position calculation unit 22d, and an interference. It has a meter adjustment position calculation unit 22e and an optical system adjustment mechanism control unit 22f. In addition, including the following description, the functional unit that controls each unit stores programs corresponding to these functional units in a non-illustrated non-volatile memory such as a ROM, and these programs are stored in a CPU (Central Processing Unit). It implement | achieves by reading and executing to.

  The adjustment reference light source control unit 22 a controls turning on and off of the adjustment reference light source 11. The spectral spectrum data creation unit 22b stores data obtained by performing Fourier transform and frequency / wavelength conversion processing on the interference fringes imaged by the imaging device 14 as spectral spectrum data 21a, and the spectral spectrum. Information relating to the peak of the data 21a is associated with the lens position and stored as peak data 21b by lens position. The focal position detection unit 22c detects a focused lens position based on the created lens position-specific peak data 21b. Using the characteristic that the peak intensity of the spectroscopic spectrum is maximized at the in-focus lens position, the in-focus lens position is specified based on the lens position-specific peak data 21b. The lens adjustment position calculation unit 22d calculates a movement direction and a movement distance for moving the lens 12h to a lens position in focus based on the detection result by the focus position detection unit 22c. The interferometer adjustment position calculation unit 22e refers to the reference light source interferometer position correction table 21d based on the peak wavelength of the spectral spectrum data 21a, specifies the positional relationship between the interferometer 12i and the image sensor 14, and The moving direction and moving distance of the interferometer 12i for realizing a predetermined optical magnification are calculated. The optical system adjustment mechanism control unit 22f controls the optical system adjustment unit 13 of the spectrum sensor unit 10 based on the movement direction and the movement distance calculated by the lens adjustment position calculation unit 22d and the interferometer adjustment position calculation unit 22e. Thus, the positions of the lens 12h and the interferometer 12i of the optical system unit 12 are adjusted. Details of the focus adjustment and the optical magnification adjustment method will be described later.

  The spectral sensor unit 10 shown in FIG. 1 is used to measure the optical characteristics of a paper sheet, for example, with a paper sheet identification device after the focus and optical magnification are adjusted by the optical system adjustment control unit 20. Is done. FIG. 2 is a functional block diagram showing an example of a paper sheet identification device 40 including the spectrum sensor unit 10 shown in FIG. The paper sheet identification device 40 includes an identification light source 41, a spectrum sensor unit 10, an output unit 42, a storage unit 43, and a control unit 44.

  The identification light source 41 is a light source used when identifying paper sheets. The output unit 42 has a function of outputting a paper sheet identification result to the outside.

  The storage unit 43 is a storage device such as a hard disk or a non-volatile memory, and stores spectral spectrum data 43a, paper sheet determination reference data 43b, and a frequency / wavelength conversion table 43c. The spectral spectrum data 43a is data obtained by subjecting data acquired from the image sensor 14 of the spectrum sensor unit 10 to Fourier transform and frequency / wavelength conversion processing. The paper sheet determination reference data 43b is determination reference data for a paper sheet to be determined. The determination reference data is spectral spectrum data to be acquired for each paper sheet, and is prepared in advance for each type of paper sheet. The frequency / wavelength conversion table 43c is data defining the relationship between the frequency and the wavelength used in the process of converting the frequency into the wavelength when the spectral data 43a is created. However, for the frequency / wavelength conversion table 43c, when the relationship between the frequency and the wavelength is easily expressed by a mathematical expression, this mathematical expression may be used instead of the table.

  The control unit 44 is a control unit that controls the entire paper sheet identification apparatus 40, and includes a light source control unit 44a, a spectral data creation unit 44b, and a true / false determination unit 44c.

  The light source control unit 44 a controls turning on and off of the identification light source 41. When data is output from the image sensor 14 of the spectrum sensor unit 10 in a state in which light from the light source for identification 41 is irradiated on the paper sheet to be determined, the spectral data generator 44b performs Fourier transform and frequency / frequency conversion on this data. Spectral data 43 a is generated by performing wavelength conversion processing and stored in the storage unit 43. The true / false / injury determination unit 44c compares the spectral spectrum data 43a obtained by using the spectrum sensor unit 10 with the paper sheet determination reference data 43b previously stored in the storage unit 43, thereby capturing an image. In addition to specifying the type of the paper sheet that has been used, the authenticity / injury is determined. The obtained determination result is output to the outside by the output unit 42.

  The frequency / wavelength conversion table 43c used in the paper sheet identification device 40 is acquired from the optical system adjustment control unit 20 that has adjusted the optical system unit 12 of the spectrum sensor unit 10, as shown in FIG. This corresponds to the frequency / wavelength conversion table 21 c stored in the storage unit 21 of the optical system adjustment control unit 20. When acquiring the data from the optical system adjustment control unit 20, if the reference light source interferometer position correction table 21 d is also acquired, the optical system unit 12 of the spectrum sensor unit 10 is adjusted in the paper sheet identification device 40. You can also At this time, the data may be exchanged between the optical system adjustment control unit 20 and the paper sheet identification device 40 using a network or storage medium (not shown), or the spectrum sensor unit 10 may store the storage unit. It is possible to use this storage unit to exchange data. In addition, the spectrum sensor unit 10 is not limited to the aspect having the adjustment reference light source 11, and may be an aspect in which a separately provided adjustment reference light source 11 is used. These will be described later. Hereinafter, as shown in FIG. 1, a case where the focal point and optical magnification of the optical system unit 12 are adjusted while being connected to the optical system adjustment control unit 20 will be described.

  Next, the optical system unit 12 and the image sensor 14 which are components of the spectrum sensor unit 10 shown in FIG. 1 will be described. FIG. 3 is a schematic cross-sectional view for explaining the structures of the optical system unit 12 and the image sensor 14. The optical system unit 12 includes a light guide 12a, a coupling 12b, an interferometer 12i, and a lens unit 12j including a lens 12h. The interferometer 12i includes a filter 12c, a diffusion plate 12d, a first polarizing plate 12e, a birefringent prism 12f, and a second polarizing plate 12g. The image sensor 14 is a line image sensor composed of a CCD formed on the substrate 14 a and images the interference fringes formed by the optical system unit 12. For example, a Wollaston prism is used as the birefringent prism 12f.

  The light guide 12a has a plurality of light receiving portions 212a to 212p that are arranged in a line at equal intervals in the X-axis direction and have light receiving surfaces perpendicular to the Z-axis. The reflected light or transmitted light from the paper sheets received by the light receiving parts 212a to 212q is guided and emitted to the emission part 212q while being totally reflected inside the light guide 12a. The light from the emission part 212q is collected by the coupling 12b and then incident on the diffusion plate 12d after unnecessary excitation light such as infrared rays and ultraviolet rays is filtered by the filter 12c. Then, the non-polarized wave scattered and emitted by the diffusing plate 12d into uniform light is converted into a 45-degree linearly polarized wave by the first polarizing plate 12e. The linearly polarized wave emitted from the first polarizing plate 12e is orthogonal to the extraordinary light (vertical polarized wave) having the optical path difference (phase difference) and the ordinary light (horizontal polarized wave) using the birefringence by the birefringent prism 12f. Are separated into two polarization components. In the second polarizing plate 12g, the vibration surfaces of the two polarization components of the extraordinary light and the ordinary light in which the optical path difference is generated are aligned. Thereafter, two light components are imaged on the image sensor 14 by the lens 12h, and the distribution of the interference light by the two light components is imaged as interference fringes by the image sensor 14.

  The interferometer 12i is obtained by unitizing the filter 12c, the diffusion plate 12d, the first polarizing plate 12e, the birefringent prism 12f, and the second polarizing plate 12g, and moves the entire interferometer 12i in the X-axis direction. Thus, the optical magnification of the spectrum sensor unit 10 can be adjusted. The lens unit 12j is a unit including the lens 12h, and the focal point of the spectrum sensor unit 10 can be adjusted by moving the position of the lens 12h in the X-axis direction.

  Next, the mechanism of the optical system adjustment unit 13 that is a component of the spectrum sensor unit 10 shown in FIG. 1 will be described. FIG. 4 is a schematic diagram for explaining the mechanism of the optical system adjustment unit 13.

  First, the outline of the optical system adjustment unit 13 will be described with reference to FIG. The optical system unit 12 can ensure the optical performance of the spectrum sensor unit 10 by adjusting the deviation of the focal point and the optical magnification due to the accuracy error even when the accuracy error is included in the optical characteristics of the component parts. The focus is adjusted by moving the position of the lens 12h in the X-axis direction in the figure and adjusting the distance between the image sensor 14 and the lens 12h. The adjustment of the position may be, for example, a mode in which the lens unit adjustment lever 13b shown in FIG. 4A is operated as indicated by an arrow 201 and moved together with the lens unit 12j in the X-axis direction, or the lens unit 12j The focus ring 12k provided on the lens 12b may be rotated as indicated by an arrow 202 to move only the lens 12h while the position of the lens portion 12j is fixed, or both of these may be performed. It doesn't matter. The optical magnification is adjusted by moving the position of the interferometer 12i in the X-axis direction in the figure. Specifically, the interferometer adjustment lever 13a shown in FIG. 4A is operated as indicated by an arrow 203 to move the position of the interferometer 12i in the X-axis direction.

  Next, a specific example of a mechanism for adjusting the focal point and optical magnification of the optical system unit 12 by the optical system adjustment unit 13 will be described with reference to FIG. FIG. 4B is a schematic diagram illustrating a plan view and a front view of the optical system unit 12 and the optical system adjustment unit 13.

  As shown in the plan view of FIG. 4B, the base plate 13p that forms the casing of the spectrum sensor unit 10 is provided with an interferometer slide groove 13h that is long in the X-axis direction. The position of the interferometer 12i is adjusted by sliding the interferometer slide groove 13h in the X-axis direction with a convex portion provided at the bottom of the interferometer 12i being inserted. An interferometer adjustment lever 13a is used as a mechanism for sliding the interferometer 12i in the X-axis direction. The interferometer adjustment lever 13a is fixed to the base plate 13p so as to be rotatable at the lever fulcrum 13d, and the interferometer 12i is moved by the rotation of the interferometer adjustment pin 13e around the lever fulcrum 13d. ing. Although details of the mechanism will be described later, the interferometer adjustment lever 13a is rotated as indicated by an arrow 204 shown in the plan view by an interferometer position adjustment motor 13c connected using a rack and a pinion or the like. The rotation of the interferometer position adjustment motor 13 c is controlled by the optical system adjustment mechanism control unit 22 f of the optical system adjustment control unit 20.

  The front view of FIG. 4B is an example of a mechanism when the lens unit 12j is fixed to the base plate 13p and only the lens 12h is moved inside the lens unit 12j. A lens position adjusting motor 13f that controls the rotation of the focus ring 12k in the direction of the arrow 202 is connected to the focus ring 12k of the lens unit 12j. The rotation of the lens position adjustment motor 13f is controlled by the optical system adjustment mechanism control unit 22f of the optical system adjustment control unit 20. When the lens position adjusting motor 13f rotates, the focus ring 12k rotates, and the position of the lens 12h in the lens portion 12j in the X-axis direction is adjusted. As described above, the lens unit 12j may be configured to use the lens unit adjustment lever 13b having the same mechanism as that of the interferometer 12i. For example, when the adjustment range of the lens position is wide, a mode in which the position is roughly adjusted by the lens unit adjustment lever 13b and then fine adjustment is performed by the focus ring 12k may be used.

  Next, a specific example of a mechanism for finely adjusting the position of the interferometer 12i by the optical system adjustment unit 13 will be described with reference to FIG. 5A to 5C show a front view below the plan view, and FIG. 5D shows only the plan view. As shown in FIG. 5A, the base plate 13p that forms the casing of the spectrum sensor unit 10 is formed with a through hole serving as a lever fulcrum 13d and an action point moving hole 13g that is an arcuate through hole. ing. When the interferometer adjustment lever 13a is rotated, the interferometer adjustment pin 13e serving as the action point moves along the action point moving hole 13g with the lever fulcrum 13d as a fulcrum. The base plate 13p is provided with an interferometer slide groove 13h for restricting the moving direction of the interferometer 12i so that the optical axis of the interferometer 12i does not shift during position adjustment.

  As shown in FIG. 5B, the interferometer 12i is installed such that the convex portion 12q on the bottom surface slides in the interferometer slide groove 13h. The interferometer 12i is formed with an action point moving hole 13i that is a long through hole in the Y-axis direction. As shown in FIG. 5C, the interferometer adjustment lever 13a is installed on the lower surface side of the base plate 13p, and is fixed so as to be rotatable at a lever fulcrum 13d. Further, at the position where the action point moving hole 13g provided in the base plate 13p overlaps with the action point moving hole 13i provided in the interferometer 12i, the interferometer adjustment of the interferometer adjustment lever 13a is placed in these two holes. By inserting the use pin 13e, the interferometer 12i and the interferometer adjustment lever 13a are connected.

  When the interferometer adjustment lever 13a is rotated with the lever fulcrum 13d as a fulcrum, the interferometer adjustment pin 13e moves along the action point moving hole 13g of the base plate 13p. At this time, the interferometer adjustment pin 13e moves in both the X-axis direction and the Y-axis direction, but the interferometer 12i does not move in the Y-axis direction but is moved in the X-axis direction due to the restriction by the interferometer slide groove 13h. Only move.

  With the above structure, as shown in FIG. 5D, the moving distance (Lb) of the interferometer 12i is smaller than the moving distance (La) in the X-axis direction of the tip of the interferometer adjusting lever 13a. As a result, as shown in FIG. 4B, the position of the interferometer 12i can be finely adjusted while controlling the movement of the end of the interferometer adjustment lever 13a by the interferometer position adjusting motor 13c.

  Next, a method for adjusting the optical system unit 12 of the spectrum sensor unit 10 shown in FIG. 1 will be described. FIG. 6 is a diagram for explaining an optical system adjustment method of the spectrum sensor unit 10.

  When the spectrum sensor unit 10 is used in the paper sheet identification device 40, spectral spectrum data is created from the data obtained by the spectrum sensor unit 10, and the type, authenticity, Identification of damage or the like is performed. For this reason, it is required that characteristics relating to the wavelength and intensity of light incident from the paper sheet appear accurately on the spectral data obtained from the spectral sensor unit 10. In order to accurately obtain the wavelength of the incident light on the spectral data, the optical magnification of the spectrum sensor unit 10 needs to be a predetermined optical magnification (design value). Further, in order to accurately obtain the characteristics related to the wavelength and intensity of incident light on the spectral data, it is necessary to focus the spectrum sensor unit 10. That is, in order to ensure the optical performance of the spectrum sensor unit 10, it is necessary to adjust the optical system unit 12 so that a predetermined optical magnification is obtained in a focused state.

  In order to adjust the optical magnification and focus of the spectrum sensor unit 10, a reference light source that shows a peak characteristic of a specific wavelength on the spectral data is used. In this embodiment, as shown in FIG. 6A, a green LED having a peak at a wavelength position of 530 nm on the spectral data is used as the adjustment reference light source 11. Light is emitted from the adjustment reference light source 11, and the interference fringes imaged on the image sensor 14 by the optical system unit 12 are imaged. At this time, the output data output from the CCD used as the image sensor 14 is shown in FIG. 6B, and the peak portion of the output data (in the circle in the figure) is enlarged in FIG. 6C. It is. The spectral data of FIG. 6D is obtained by Fourier transforming the output data and converting the frequency into a wavelength. The wavelength and intensity of the peak shown in FIG. 6D vary depending on the optical magnification and focus of the spectrum sensor unit 10.

  Specifically, the focus adjustment is performed by adjusting L1, which is the distance between the lens 12h and the image sensor 14 in FIG. 6A. FIG. 6D shows how the focus is adjusted. The peak intensity varies. Since the peak intensity is maximized when it is in focus, in other words, focusing is equivalent to determining the distance L1 at which the peak intensity in FIG. 6D is maximized. The optical magnification is determined by L2 which is the distance between the birefringent prism 12f and the image sensor 14 in FIG. 6A, and the peak wavelength shown in FIG. fluctuate. Therefore, adjusting the optical magnification corresponds to determining L2 in FIG. 6A so that the peak wavelength is 530 nm which is the wavelength of the reference light source.

  Next, a method for adjusting the focus of the optical system unit 12 of the spectrum sensor unit 10 shown in FIG. 1 will be specifically described. FIG. 7 is a diagram for explaining a focus adjustment method.

  As shown in FIG. 7A, the position of the lens 12h in a focused state is set as “lens position: ± 0”, and the lens position shifted from this position by α in the negative direction of the X axis is expressed as “lens position”. : −α ”, and the lens position shifted by β in the positive direction of the X axis is defined as“ lens position: + β ”. When the lens positions are “lens position: −α”, “lens position: ± 0”, and “lens position: + β”, respectively, the data (hereinafter referred to as the data output from the CCD that is the image sensor 14) is irradiated with the reference light. Spectral spectrum data generated from “CCD output data” are shown in FIGS. 7B to 7D, respectively. As shown in FIGS. 7B to 7D, the peak intensity S0 of the spectral data of “lens position: ± 0” is the largest, and “lens position: −α” and “lens position: β” deviated from this position. , The peak intensities Sα and Sβ are smaller than S0.

  FIG. 7E shows the relationship between the position of the lens 12h and the peak intensity of the spectral data. As described above, the peak intensity S0 has a maximum value at “lens position: ± 0”, and the peak depends on the amount of deviation regardless of whether the lens position is shifted in the positive X-axis direction or the negative X-axis direction. Strength decreases.

  For these reasons, the focus of the optical system unit 12 of the spectrum sensor unit 10 is adjusted by measuring the peak intensity of the spectral data at each lens position, as shown in FIG. This can be done by specifying the lens position where the intensity is a maximum value. Specifically, in FIG. 7E, from the initial position on the right side or the left side of the peak position where the peak intensity reaches a maximum value, the measured peak intensity increases, that is, toward the focused peak position. The position of the lens 12h is adjusted so as to move, and it is determined that the in-focus peak position has been exceeded where the peak intensity has decreased beyond the maximum point, and the in-focus peak position is specified. The amount by which the lens 12h is moved is set in advance so that a predetermined area including a focused peak position can be specified. In FIGS. 7B to 7D, the horizontal axis is the wavelength, but this can also be processed as the frequency. Needless to say, the frequency can be processed as a wavelength or the wavelength can be processed as a frequency based on the relationship between the frequency and the wavelength, including other figures and processing.

  Next, a method for adjusting the optical magnification of the optical system unit 12 of the spectrum sensor unit 10 shown in FIG. 1 will be specifically described. FIG. 8 is a diagram for explaining a method of adjusting the optical magnification.

  As shown in FIG. 8A, the position of the interferometer 12i when the optical magnification is set to a predetermined magnification is “interferometer position: ± 0”, and the position shifted by ΔM from this position in the negative direction of the X axis is “ Interferometer position: −ΔM ”, and a position shifted by ΔN in the positive direction of the X axis is referred to as“ interferometer position: + ΔN ”. When the interferometer positions are “interferometer position: −ΔM”, “interferometer position: ± 0”, and “interferometer position: + ΔN”, the spectrum obtained by irradiating the green reference light with a wavelength of 530 nm The data are shown in FIGS. 8B to 8D, respectively.

  As shown in FIG. 8C, when the interferometer 12i is at the position of “interferometer position: ± 0”, the peak wavelength of the spectral data becomes 530 nm, which is the same as the reference light. On the other hand, as shown in FIG. 8B, when the interferometer 12i is at the position of “interferometer position: −ΔM”, the peak wavelength of the spectrum data is a value smaller than the wavelength 530 nm of the reference light. (530-β) nm. Further, as shown in FIG. 8D, when the interferometer 12i is at the position of “interferometer position: + ΔN”, the peak wavelength of the spectral data is a value larger than the reference light wavelength 530 nm (530 + α). nm.

  FIG. 8E shows the relationship between the position of the interferometer 12i and the peak wavelength obtained from the spectral data. When green reference light having a wavelength of 530 nm is used, the relationship between the position of the interferometer 12i and the peak wavelength of the spectral data is a linear relationship as shown in FIG. This linear relationship is stored in the storage unit 21 as a reference light source-specific interferometer position correction table 21d. Thus, if the peak wavelength of the spectral data is obtained using the reference light, the moving direction and moving distance of the interferometer 12i for adjusting the optical magnification to a predetermined magnification from the linear relationship shown in FIG. Can be determined. Specifically, for example, when the measured peak wavelength is (530 + α) nm, the interferometer 12i is moved in the X-axis direction by ΔM based on the linear relationship shown in FIG.

  Next, a procedure for adjusting the focus and optical magnification of the optical system unit 12 of the spectrum sensor unit 10 shown in FIGS. 7 and 8 will be described. FIG. 9 is a flowchart showing a procedure for adjusting the focus and optical magnification.

  First, the adjustment reference light source controller 22a controls the adjustment reference light source 11 of the spectrum sensor unit 10 to turn on the green LED (step S101). Next, the spectral data generator 22b generates spectral data 21a from the CCD output data by Fourier transform and frequency / wavelength conversion in a state where the reference light is irradiated (step S102). And the position where the intensity | strength of the produced spectrum data 21a shows a peak is specified, and the wavelength and intensity | strength of the specified peak position are linked | related with a lens position, and are recorded on the peak data 21b classified by lens position (step S103). Next, the focal position detection unit 22c refers to the lens position-specific peak data 21b and determines whether or not the maximum value shown in FIG. 7E is included (step S104). If the peak data for each lens position 21b includes a position where the peak intensity is maximized (step S105; Yes), the process proceeds to a lens position determination process (step S107). On the other hand, when the peak position-specific peak data 21b does not include a position where the peak intensity is maximized (step S105; No), the optical system adjustment mechanism control unit 22f controls the optical system adjustment unit 13, After the lens position is slightly moved (step S106), the process returns to the spectral data generation process (step S102) again.

  The process of moving the lens 12h slightly (step S106) includes a process of determining the moving direction. Specifically, at the first movement, the lens 12h is slightly moved in an arbitrary direction of the X axis in FIG. Then, when the peak intensity of the spectral data 21a obtained as a result of the first minute movement becomes higher than the peak intensity before the minute movement, the movement direction at the next minute movement is changed to the first time. And the same direction. On the other hand, when the peak intensity of the spectral spectrum data 21a obtained as a result of the first minute movement becomes lower than the peak intensity before the minute movement, the movement direction at the next minute movement is defined as the first movement. The reverse direction.

  The initial position of the lens 12h is on the right side (0 side in the figure) from the in-focus position in FIG. 7E (0 side in the figure) or on the left side (0 side in the figure). In this way, the lens 12h is moved in an arbitrary direction, and the moving direction is the direction of focusing (the direction toward 0 (zero) in the figure) due to the change in peak intensity before and after the movement. Whether or not.

  However, the present embodiment is not limited to this. For example, when the optical system unit 12 is assembled, the initial position of the lens 12h is set so that it is on the right side (or the left side) of the focused position in FIG. In other words, at the start of focus adjustment, the lens 12h may be moved so that the peak intensity moves to the left (or right) toward the position where the focus is achieved in FIG. By setting the initial position of the lens 12h in this way, the direction in which the lens 12h should be moved for focusing is clarified at the start of focus adjustment, and processing for determining whether the moving direction is correct is not necessary. .

  When the peak data 21b for each lens position includes a position where the intensity becomes maximum as shown in FIG. 7E (step S105 in FIG. 9; Yes), this position is the in-focus position. is there. The lens position-specific peak data 121b records each lens position and the peak intensity at each lens position, including the maximum position. Therefore, the lens adjustment position calculation unit 22d can calculate the movement direction and the movement distance from the current position of the lens 12h toward the position where the peak intensity is maximized, that is, the position where the focus is achieved. The optical system adjustment mechanism control unit 22f controls the optical system adjustment unit 13 to move the lens 12h to a focused position based on the calculated movement direction and movement distance (step S107).

  After focusing in this manner, adjustment of the optical magnification is then started. First, the spectral data generator 22b irradiates light from the reference light in a focused state, and generates spectral data 21a again from the CCD output data (step S108). A peak wavelength is detected from the created spectral data 21a (step S109), and it is determined whether or not this peak wavelength is within a predetermined range centered on the reference light wavelength of 530 nm (step S110). . When the peak wavelength is within the predetermined range (step S110; Yes), it is determined that the optical magnification of the optical system unit 12 of the spectrum sensor unit 10 is the predetermined optical magnification, and the adjustment reference light source control unit. In 22a, the adjustment reference light source 11 is turned off (step S113), and the process ends.

  On the other hand, when the spectral wavelength data 21a created after the focus adjustment does not fall within a predetermined range centered on the wavelength of 530 nm (step S110; No), the interferometer adjustment position calculation unit 22e Referring to the reference light source interferometer position correction table 21d corresponding to the data shown in FIG. 8E, the moving direction of the interferometer 12i for setting the optical magnification to a predetermined magnification based on the peak wavelength of the spectral spectrum data 21a. Then, the moving distance is calculated (step S111). Then, the optical system adjustment mechanism control unit 22f controls the optical system adjustment unit 13 to move the interferometer 12i to a position where the optical magnification becomes the predetermined magnification based on the calculated movement direction and movement distance (step) S112). When the interferometer 12i is moved, since it is necessary to confirm the focus again, the process returns to the head of the focus adjustment process (step S102).

  Thus, by performing the focus adjustment first, confirming the optical magnification from the obtained spectral spectrum and adjusting the optical magnification as necessary, when adjusting the optical magnification, by performing the focus adjustment again, The focus and optical magnification can be adjusted accurately. Further, since the focus adjustment and the optical magnification adjustment are adjustments based on numerical data obtained from the CCD output, all processes can be automated using the mechanism described with reference to FIGS. Thereby, even when there is an accuracy error in the optical component constituting the optical system unit 12, the focus and the optical magnification can be adjusted easily and accurately, and the optical performance of the spectrum sensor unit 10 can be maintained.

  In the first embodiment, the focal point and optical magnification of the optical system unit 12 of the spectrum sensor unit 10 are adjusted by moving the lens 12h and the interferometer 12i. However, the present invention is not limited to this. Specifically, the optical magnification adjustment can be realized by correcting the data in the process of creating the spectral data from the acquired data without adjusting the position of the interferometer 12i. In the second embodiment, details of the case where data correction is performed will be described.

  The configurations of the spectrum sensor unit 10 and the optical system adjustment control unit 120 according to the second embodiment will be described. FIG. 10 is a device configuration diagram of the spectrum sensor unit 10 and the optical system adjustment control unit 120 according to the second embodiment. Similar to the first embodiment, the spectrum sensor unit 10 is a unit incorporated in the paper sheet identification device 40 and the like, but a table used for frequency / wavelength conversion in the paper sheet identification device 40 is a correction table described later. This is different from the first embodiment. The optical system adjustment control unit 120 is a control unit for automatically calculating the focus adjustment of the optical system of the spectrum sensor unit 10 and the correction information of the optical magnification.

  In the second embodiment, the functional units similar to those in the first embodiment, such as the display unit 30, are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted. Further, the data 121a to 121c stored in the storage unit 121 of the second embodiment correspond to the data 21a to 21c illustrated in FIG. 1 in the first embodiment, respectively, and the functional units 122a to 122d included in the control unit of the second embodiment. And 122f respectively correspond to the functional units 22a to 22d and 22f illustrated in FIG. 1 in the first embodiment, and thus detailed description thereof is omitted.

  The optical system adjustment control unit 120 includes a storage unit 121 and a control unit 122, and images the interference fringes formed by the optical system unit 12 by imaging the reference light emitted from the adjustment reference light source 11 with the imaging device 14, Based on the interference fringe data, a focus shift or optical magnification shift is detected. Then, the optical system adjustment unit 13 is controlled to adjust the focus of the optical system unit 12 and to automatically calculate correction information of the optical magnification.

  The frequency / wavelength conversion correction table 121 d stored in the storage unit 121 is for correcting the optical magnification of the optical system unit 12. In the first embodiment, the optical magnification of the optical system unit 12 is adjusted by moving the interferometer 12i. However, in the second embodiment, the spectral spectrum data is not adjusted without adjusting the position of the interferometer 12i for adjusting the optical magnification. A frequency / wavelength conversion correction table 121d is generated by correcting the frequency / wavelength conversion table 121c used for generating 121a. By using this correction table, it is possible to obtain spectral spectrum data 121a similar to that obtained when the optical magnification is adjusted by adjusting the position of the interferometer 12i. After the focus and optical magnification of the spectrum sensor unit 10 are adjusted, the frequency / wavelength conversion correction table 121d is stored in the paper sheet identification device 40 using the spectrum sensor unit 10 as the frequency / wavelength conversion table 43c. It is stored in the unit 43 and used.

  The control unit 122 is a control unit that controls the entire optical system adjustment control unit 120, and includes an adjustment reference light source control unit 122a, a spectral spectrum data creation unit 122b, a focus position detection unit 122c, a lens adjustment position calculation unit 122d, and a frequency. / Wavelength conversion table correction processing unit 122e and optical system adjustment mechanism control unit 122f.

  The frequency / wavelength conversion table correction processing unit 122e has a function of creating a frequency / wavelength conversion correction table 121d. Specifically, as shown in FIG. 11D, the adjustment reference light source 11 was irradiated with light from the light receiving unit side of the spectrum sensor unit 10, and the obtained CCD output data was Fourier transformed. Let β be the frequency at which the data intensity is maximum. Then, when the same light source is irradiated to the spectrum sensor unit 10 whose optical magnification is correctly adjusted, the frequency at which the intensity is maximum in the data obtained from the CCD output data is set to α. Then, the correction magnification M is obtained as M = β / α. The frequency / wavelength conversion table correction processing unit 122e uses this correction magnification M to create the frequency / wavelength conversion correction table 121d from the frequency / wavelength conversion table 121c. By using this correction table, the wavelength of the spectral data is mapped to the original wavelength position, details of which will be described later.

  A method of correcting the optical magnification of the optical system by the optical system adjustment control unit 120 of the spectrum sensor unit 10 shown in FIG. 10 will be described. FIG. 11 is a diagram for explaining a method of correcting the optical magnification.

  In order to correct the optical magnification of the spectrum sensor unit 10, a reference light source having a characteristic peak at a known specific wavelength on the spectrum data is used. In this embodiment, as shown in FIG. 11A, a green LED having a peak at a wavelength of 530 nm on the spectral data is used as the adjustment reference light source 11. Light is emitted from the adjustment reference light source 11, and the interference fringes imaged on the image sensor 14 by the optical system unit 12 are imaged. FIG. 11B shows the data output from the CCD used as the image sensor 14, and FIG. 11C shows the enlarged peak portion of the output data. The CCD output data obtained by Fourier transform is the data indicated by the solid line in FIG. In order to create spectral spectrum data, frequency / wavelength conversion is performed by applying the frequency / wavelength conversion table 121c shown in FIG. 11 (E) to the data (solid line) after Fourier transform in FIG. 11 (D). I do.

  However, when using the spectrum sensor unit 10 in which the optical magnification is not adjusted, the data (solid line) in FIG. 11D is converted using the conversion table in FIG. The data position of the obtained spectral data is shifted. Specifically, although a reference light having a wavelength of 530 nm is used, as shown in FIG. 11F, a peak does not appear at a wavelength of 530 nm where a peak should originally appear, but a peak appears at a shifted position. .

  In the present embodiment, when the wavelength shift caused by such a shift in optical magnification is dealt with, the position of the interferometer 12i is not adjusted as in the first embodiment, but data correction is performed. Specifically, in order to make the waveform of the spectral spectrum data obtained by frequency / wavelength conversion into a waveform mapped to the original data position, as shown in FIG. The frequency / wavelength conversion correction table 121d (solid line in the figure) is created by correcting the broken line). Specifically, the frequency / wavelength conversion table 121d is created by multiplying the frequency / wavelength conversion table 121c by the correction magnification M (= β / α) obtained by the frequency / wavelength conversion table correction processing unit 122e. . By using the frequency / wavelength conversion correction table 121d created in this way, spectral data mapped to the original wavelength position value as shown in FIG. 11 (H) from the data (solid line) shown in FIG. 11 (D). Can be obtained.

  As described above, the correction magnification M is obtained when the frequency of the peak position of the data obtained as an actual measurement value (solid line in the figure) is β and the optical magnification is correctly adjusted as shown in FIG. When the frequency at the peak position of the data, which is an ideal value (dashed line), is α, M = β / α. When F is a frequency, W is a wavelength, and the frequency / wavelength conversion table 121c is a function of F = f (W), and the frequency / wavelength conversion correction table 121d is a function g, F = g (W) = Mf (W). That is, f (w) indicated by a broken line in FIG. 11G is converted to g (W) indicated by a solid line by the correction magnification M.

  Next, the procedure for adjusting the focus of the optical system unit 12 of the spectrum sensor unit 10 and creating an optical magnification correction table will be described. FIG. 12 is a flowchart showing a procedure for adjusting the focus of the optical system unit 12 and creating an optical magnification correction table. In FIG. 12, the processing in steps S201 to S207 performed to adjust the focus is the same as the processing in steps S101 to 107 shown in FIG.

  After focusing by the same procedure (steps S201 to S207) as in the first embodiment, processing for creating an optical magnification correction table is started. First, the spectral data generator 122b irradiates the reference light in a focused state, and again generates spectral data 121a from the CCD output data (step S208). At this time, as described above, the correction magnification M is calculated by M = β / α from the frequency β of the peak position obtained from the actually measured value of the spectral spectrum data 121a and the frequency α obtained from the ideal value (step S209). Then, the frequency / wavelength conversion correction table 121d is created by correcting the frequency / wavelength conversion table 121c with the correction magnification M (step S210).

  Next, spectral spectrum data is created from the data obtained by Fourier transforming the obtained CCD output data using the previously created frequency / wavelength conversion correction table 121d (step S211). Then, it is determined whether or not the peak wavelength at which the intensity of the spectral spectrum data is maximum falls within a predetermined range centered on the reference light source wavelength of 530 nm (step S212). If the peak wavelength is not within the predetermined range (step S212; No), the process returns to the spectral data creation process (step S208) to correct the correction magnification and frequency / wavelength conversion correction table 121d. On the other hand, when the peak wavelength is within the predetermined range (step S212; Yes), the adjustment reference light source 11 is turned off (step S213), and the process ends.

  As described above, in the second embodiment, as in the first embodiment, the spectral position data is created at each lens position while automatically moving the lens position, and the position of the in-focus lens 12h is specified. The position of the lens 12h can be automatically adjusted so that it is in focus. In addition, since the frequency / wavelength conversion correction table is automatically created based on the peak wavelength of the spectral spectrum data created from the CCD output data and the wavelength of the reference light source using the light source of the predetermined wavelength, the first embodiment Thus, without moving the position of the interferometer 12i, the measurement result when the optical magnification is set to a predetermined optical magnification can be obtained. Thus, the focal point and optical magnification of the optical system of the spectrum sensor unit 10 can be adjusted as in the first embodiment without adjusting the position of the interferometer 12i in order to adjust the optical magnification.

  In addition, in Example 1 and Example 2, although the example using green LED as a reference light source was shown, a reference light source is not limited to this. For example, red or blue LEDs may be used, or laser light may be used instead of LEDs. Moreover, it is not limited to the aspect using a single light source, You may utilize the data obtained by each light source using multiple types of light sources. Further, for example, a mode in which predetermined light is extracted from a halogen light source using a color filter (interference filter) may be used.

  Further, at the time of focus adjustment, as long as the optical distance between the lens 12h and the image sensor 14 can be changed, not only the mode in which only the lens 12h is moved, but only the image sensor 14 may be moved. Both of the image sensor 14 may be moved. Similarly, when adjusting the optical magnification, either one or both of them may be moved as long as the optical distance between the interferometer 12i and the image sensor 14 can be changed.

  In the first and second embodiments, various data relating to the optical system adjustment of the spectrum sensor unit 10 are stored in the storage unit 21 of the optical system adjustment control unit 20 and the storage unit 43 of the paper sheet identification device 40. The embodiment was shown. However, the present invention is not limited to this. For example, as shown in FIG. 13, the spectrum sensor unit 10 has a storage unit 15 inside, and data is stored in the storage unit 15. It doesn't matter. Thereby, for example, after adjusting the optical system of the spectrum sensor unit 10 using the optical system adjustment control unit 20, the frequency / wavelength conversion table 21c is stored in the storage unit 15 of the spectrum sensor unit 10, and the spectrum sensor In the paper sheet identification device 40 using the unit 10, these tables can be read out from the storage unit 15 of the spectrum sensor unit 10 and used. Similarly, when the correction table is used as in the second embodiment, the frequency / wavelength conversion correction table 121d can be stored in the storage unit 15 of the spectrum sensor unit 10 and used. Thereby, for example, even when the spectrum sensor unit 10 is replaced, data can be read from the attached unit and used.

  Since the light guide 12a guides light from the light receiving parts 212a to 212p to the emission part 212q, the reference light is directly incident on the coupling 12b with the light guide 12a removed as shown in FIGS. Then, the adjustment work of the optical system unit 12 can be performed, and as shown in the first and second embodiments, the spectrum sensor unit 10 includes the reference light source 11 for adjustment, and the light receiving unit 212a of the light guide 12a. The reference light can also be incident from ˜212p. Specifically, as shown in FIG. 14A, a light source unit 113 in which an adjustment reference light source 11 and an identification light source 41 are arranged below the case 111 and the base 112 in which the light guide 12a is housed is provided. It is attached. The light guide 12 a made up of four light guide plates having a bent shape is housed inside the case 111 with the light receiving portions 212 a to 212 p exposed from the base 112. FIGS. 14B and 14C are views of the surface of the light source unit 113 shown in FIG. For example, as shown in FIG. 14B, the adjustment reference light source 11 (11a to 11c) and the identification light source 41 (41a to 41c) are each one light receiving unit 212a to 212a of the light guide 12a. 212p (illustrated only 112a to 112c) is arranged. Further, for example, as shown in FIG. 14C, the single adjustment reference light source 11 may be arranged in the vicinity of the light receiving part 212p located closest to the emission part 212q of the light guide 12a.

  As a result, the adjustment reference light source 11 is turned on when adjusting the optical system section 12 of the spectrum sensor unit 10, and the identification light source 41 is turned on when identifying the paper sheet. Can be used. In addition, since the spectrum sensor unit 10 includes the adjustment reference light source 11, it is not necessary to separately provide the adjustment reference light source 11 when adjusting the optical system unit 12. For this reason, as shown in FIG. 2, the optical system unit 12 can be adjusted by the method described above in a state where the spectrum sensor unit 10 is incorporated in the paper sheet identification device 40. When the adjustment reference light source 11 of the spectrum sensor unit 10 is used, as shown in FIG. 14A, a white medium for reflecting the reference light below the measurement window 114 made of a transparent member. Etc. 110 are desirable. For example, in the paper sheet identification device 40 in which the spectrum sensor unit 10 is incorporated, a white medium is disposed below the unit, the conveyance path portion below the unit is white, or a reflector is embedded in the conveyance path portion. By doing so, the optical system section 12 of the spectrum sensor unit 10 can be accurately adjusted while being incorporated in the paper sheet identification device 40.

  Further, as shown in FIGS. 1 and 10 and the like, the spectrum sensor unit 10 is not limited to the aspect having the adjustment reference light source 11, but as shown in FIG. 15, the spectrum sensor unit 10 does not have a light source and is provided separately. It is also possible to use an adjustment reference light source 11 that is provided. Even in this case, if the reference light source 11 for adjustment provided independently from the spectrum sensor unit 10 is controlled and the reference light is incident on the optical system unit 12, the adjustment of the optical system unit 12 is performed in the same manner as described above. It can be performed. Specifically, for example, as shown in FIG. 17A, the adjustment reference light source 11 may be arranged in the vicinity of the light receiving part 212p closest to the emission part 212q of the light guide 12a. In addition, as shown in FIG. 17B, an adjustment reference light source 11 may be disposed near the light guide 12a by providing a dedicated incident portion 212r for making the reference light incident.

  In addition, the adjustment of the optical system unit 12 is performed using a reference fluorescent medium that does not have the adjustment reference light source 11 that emits reference light having a predetermined wavelength and emits light having a predetermined wavelength by irradiating the excitation light source. You may be the aspect which performs. Specifically, for example, in the paper sheet identification device 40, the reference fluorescent medium is disposed below the light receiving portions 212a to 212p of the light guide 12a. When light is emitted from the identification light source 41 toward the reference fluorescent medium, light having a specific wavelength is emitted from the reference fluorescent medium. As a result, the optical system unit 12 can be adjusted using the light emitted from the reference fluorescent medium as the reference light. If the apparatus has a transport mechanism, the reference fluorescent medium may be transported by the transport mechanism and irradiated with excitation light so as to emit reference light when passing under the spectrum sensor unit 10. Good. Also in this case, the optical system unit 12 can be adjusted by the same method.

  In addition, as shown in FIG. 16, the paper sheet identification apparatus 40 also adjusts the optical system unit 12 by the above-described method if the adjustment reference light source 11 is provided separately from the identification light source 41. be able to. Specifically, for example, in a state where the spectrum sensor unit 10 is incorporated in the paper sheet identification device 40, as shown in FIG. 17A, the adjustment reference is provided in the conveyance path 130 below the light receiving portion 212p of the light guide 12a. The light source 11 may be installed, and the reference light may be irradiated through the light projection window 131 made of a transparent member. Alternatively, as shown in FIG. 17B, the adjustment reference light source 11 may be arranged on the side wall of the paper sheet identification device 40 so as to correspond to the dedicated incident portion 212r formed in the light guide 12a. .

  As described above, the focus and optical magnification of the optical system unit 12 of the spectrum sensor unit 10 are adjusted in a state where the spectrum sensor unit 10 is connected to the optical system adjustment control unit 20 or in the paper sheet identification device 40. It can be performed in the incorporated state. Further, the adjustment of the optical system unit 12 can be automatically performed using output data acquired through the optical system unit 12.

  As described above, the optical system adjustment method, the optical system adjustment device, and the paper sheet identification device of the spectrum sensor according to the present invention are capable of focusing even when there is an optical error in the optical system including the birefringent prism and the lens. In addition, this technique is useful for efficiently adjusting the optical magnification to suppress the influence of this error and realizing the optical performance in design.

DESCRIPTION OF SYMBOLS 10 Spectrum sensor unit 11 Adjustment reference light source 12 Optical system part 12a Light guide 12b Coupling 12c Filter 12d Diffusing plate 12e First polarizing plate 12f Birefringent prism 12g Second polarizing plate 12h Lens 12i Interferometer 12j Lens part 12k Focus Ring 13 Optical system adjustment unit 13a Interferometer adjustment lever 13b Lens unit adjustment lever 13c Interferometer position adjustment motor 13d Lever fulcrum 13e Interferometer adjustment pin 13f Lens position adjustment motor 13g, 13i Action point moving hole 13h Interferometer slide Groove 13p Base plate 14 Image sensor 15, 21, 43, 121 Storage unit 20, 120 Optical system adjustment control unit 22, 44, 122 Control unit 22a, 122a Adjustment reference light source control unit 22b, 122b Couttle data creation unit 22c, 122c Focus position detection unit 22d, 122d Lens adjustment position calculation unit 22e Interferometer adjustment position calculation unit 22f, 122f Optical system adjustment mechanism control unit 122e Frequency / wavelength conversion table correction processing unit 30 Display unit 40 Paper sheet Classifier 41 Light source for identification 42 Output unit 111 Case 112 Base 113 Light source unit 114 Measurement window

Claims (8)

An optical system adjustment method of a spectrum sensor in which an interferometer including a polarizer and a birefringent element , a lens, and a line image sensor are sequentially arranged along an optical path from a light source,
(1) a reference light incident process in which a reference light having a predetermined wavelength is incident on the interferometer by a reference light source;
(2) a light receiving step of receiving light collected by the lens via the interferometer by the line image sensor;
(3) a spectral data generation step of generating spectral spectrum data by performing Fourier transform on the light received by the line image sensor;
(4) a focus adjustment step of automatically adjusting a distance between the line image sensor and the lens based on the spectral spectrum data generated by the steps (1) to (3), and focusing .
(5) The optical magnification of the image formed on the line image sensor is predetermined based on the spectral data obtained by the steps (1) to (3) in the focused state in the step (4). A determination step of determining whether or not it is within the range;
(6) If it is determined in step (5) that the optical magnification is not within the predetermined range, then, based on the spectral data, the distance between the line image sensor and the interferometer is calculated. automatically adjusts, it viewed including the <br/> the optical magnification adjustment step of bringing the optical magnification to a predetermined magnification,
The method for adjusting an optical system of a spectrum sensor, wherein the steps (4) to (6) are repeatedly executed until it is determined in the step (4) that the optical magnification is within a predetermined range . In the focus adjustment step, the distance between the line image sensor and the lens is determined based on a change in peak intensity of spectral spectrum data when the distance between the line image sensor and the lens is changed. 2. The method of adjusting an optical system of a spectrum sensor according to claim 1 , wherein the adjustment is automatically performed toward the distance when the value indicates a maximum value. In the optical magnification adjustment step,
After performing Fourier transform on the light received by the line image sensor, further performing frequency wavelength conversion to obtain the wavelength of the peak position of the spectral data,
Based on the wavelength of the obtained wavelength and the reference light, the distance between the interferometer and the line image sensor is automatically adjusted towards a distance when the wavelength of the peak position coincides with the wavelength of the reference light The method for adjusting an optical system of a spectrum sensor according to claim 1 or 2 . An initial setting step of disposing the line image sensor and the lens at an initial position set apart by a predetermined distance in a direction closer to or away from a distance when focusing;
In the focusing step, at least one of the line image sensor and the lens, claim 1-3, characterized in that to start the focus adjustment while moving in a direction in which a distance in focus 1 Item 4. An optical system adjustment method for a spectrum sensor according to Item. An optical system adjustment method of a spectrum sensor in which an interferometer including a polarizer and a birefringent element, a lens, and a line image sensor are sequentially arranged along an optical path from a light source,
(1) a reference light incident process in which a reference light having a predetermined wavelength is incident on the interferometer by a reference light source;
(2) a light receiving step of receiving light collected by the lens via the interferometer by the line image sensor;
(3) a spectral data generation step of generating spectral spectrum data by performing Fourier transform on the light received by the line image sensor;
(4) a focus adjustment step of automatically adjusting a distance between the line image sensor and the lens based on the spectral spectrum data generated by the steps (1) to (3), and focusing.
(5) The wavelength of the peak position of the spectral data generated by the steps (1) to (3) with the focus in the step (4) and the step (( A correction magnification calculation step for obtaining a correction magnification based on the wavelength of the peak position of the spectral data generated by 1) to (3) ;
(6) a correction table creation step of creating a correction table in which each conversion coefficient of the frequency wavelength conversion table prepared in advance for adjusting the optical magnification is corrected with the correction magnification obtained in the step (5);
The method for adjusting an optical system of a spectrum sensor according to claim 2, comprising : An interferometer including a polarizer and a birefringent element for forming an interference wave, a lens for condensing and focusing light emitted from the interferometer, and an interference fringe imaged by the lens are imaged A spectral sensor having a line image sensor, an optical system adjustment device for adjusting an optical system,
A reference light source capable of emitting reference light of a predetermined wavelength;
The light from the reference light source is incident on the interferometer and the light received by the line image sensor is subjected to Fourier transform to generate spectral spectrum data, and the distance between the line image sensor and the lens is changed. A step of adjusting a distance between the line image sensor and the lens toward a distance when the peak intensity shows a maximum value based on a change in peak intensity of spectral spectrum data at the time ; In a combined state, light from the reference light source is incident on the interferometer and subjected to Fourier transform on the light received by the line image sensor, and further subjected to frequency wavelength conversion to obtain the wavelength at the peak position of the spectral data. An optical magnification of an image formed on the line image sensor based on the wavelength and the wavelength of the reference light A step of determining whether or not the optical magnification is within a predetermined range; and if the optical magnification is not within the predetermined range in the step, then the distance between the line image sensor and the interferometer is And a control unit that repeatedly executes the step of automatically adjusting the distance toward the distance when the wavelength of the position coincides with the wavelength of the reference light until the optical magnification falls within a predetermined range. Optical system adjustment device. Interferometer including a polarizer and a birefringent element for forming an interference wave, a lens for condensing and focusing the light emitted from the interferometer, and a line for imaging the interference fringes studied by the lens An optical system adjustment device for adjusting an optical system using a spectrum sensor having an image sensor,
A reference light source capable of emitting reference light of a predetermined wavelength;
The light from the reference light source is incident on the interferometer and the light received by the line image sensor is subjected to Fourier transform to generate spectral spectrum data, and the distance between the line image sensor and the lens is changed. A step of adjusting a distance between the line image sensor and the lens toward a distance when the peak intensity shows a maximum value based on a change in peak intensity of spectral spectrum data at the time; In a combined state, light from the reference light source is incident on the interferometer and subjected to Fourier transform on the light received by the line image sensor, and further subjected to frequency wavelength conversion to obtain the wavelength at the peak position of the spectral data. the calculated, as a correction factor the ratio of the wavelength of the wavelength and the reference light, is prepared in advance in order to adjust the optical magnification Each transform coefficient in the frequency wavelength conversion table to be used for frequency wavelength conversion in the data after the Fourier transform from the frequency axis to the wavelength axis, the control unit for generating a correction table is corrected by the correction factor and that
Optical adjustment device of the spectrum sensor according to claim 6, characterized in that it comprises a. An interferometer including a polarizer and a birefringent element for forming an interference wave, a lens for condensing and focusing light emitted from the interferometer, and an interference fringe imaged by the lens are imaged A spectrum sensor having a line image sensor;
A paper sheet identification device comprising: the optical system adjustment device according to claim 6 or 7 .

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