JPH06162312A - Authenticity discriminating device for paper money or the like - Google Patents

Abstract

PURPOSE:To provide the new authenticity discriminating device for paper money. CONSTITUTION:Spatial frequency filtering technology is applied as a basic principle to an optical system 1 to display, specially, an body image to be inspected, a spatial frequency filter image, and the holographic image of a normal paper money pattern on display means 3, 6, and 9 such as a liquid crystal display and the displays of the respective images are controlled synchronize by an image processor 2. Then, the spatial frequency filter image, holographic filter image, etc., are properly displayed and altered to enable plural kinds of matched filtering, so high-speed and high-precision authenticity discrimination is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bill authenticating device for bills such as bills and securities.

[0002]

2. Description of the Related Art As a device for identifying the authenticity of banknotes,
Conventionally, the following are known. For example, regarding the contrast reduction and the difference in the width of the white portion at the edge of the colored portion due to the color bleeding in the counterfeit banknotes, the colored portion is irradiated with light and optically detected by the light receiving sensor,
A discriminating device for discriminating between true and false by electrically processing the detected waveform (Japanese Patent Laid-Open No. 58-22489).
Alternatively, an identification device that disperses reflected or transmitted light when a counterfeit banknote is irradiated with light by a prism and discriminates authenticity based on the intensity distribution of the dispersed light according to wavelength (Japanese Patent Laid-Open No. Sho 63-63).
No. 148391).

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a new bill authenticity discrimination device based on a method different from the conventional device.

The present inventors have conducted various studies to achieve the above object, and as a result, as a basic discriminating means of the authenticity discriminating apparatus, the spatial frequency filtering technique conventionally applied to optical information processing means is used. Focusing on the possibility of doing so, further research was conducted. As a result, they have found that there are the following problems in using the spatial frequency filtering technique as a basic principle for discriminating the authenticity of bills.

First, FIG. 3 shows the configuration contents of the spatial frequency filtering technique applied to the conventional optical information processing means. That is, in the spatial frequency filtering device, as shown in the figure, a semiconductor laser 31 as a light source for irradiation, a collimator lens 32, an input image display means 33, and a surface on which the display means 33 is arranged is defined as a front focal plane. The first Fourier transform lens 34, the optical filter (photosensitive material) 35 arranged on the focal plane on the rear side of the lens 34, and the arrangement surface of the filter 35 on the front side of the focal plane. Second Fourier transform lens 3 arranged
6 and a photoelectric conversion means 37 arranged on the focal plane on the rear side of the lens 36.

The spatial frequency filtering device constructed as described above operates as follows. First, an image to be input is created by a photographic film (input image display means 33) to display the input image as a transmissive image, and coherent light from the semiconductor laser 31 is applied to the displayed image. The collimator lens 32 illuminates the parallel light processed by the parallel light. The input image on the illuminated image display means 33 is Fourier transformed by the first Fourier transform lens 34, and the Fourier transformed image is formed on the optical filter 35. Also,
As the optical filter 35, a photosensitive material recording a Fourier transform hologram image for matched filtering is mounted. As a result, the optical filter 35
The Fourier transform image corresponding to the input image and the Fourier transform hologram image of the standard pattern are superimposed on each other, and then the optical product of these two Fourier transform images is the second.
Inverse Fourier transform is performed by the Fourier transform lens 36 of
Finally, it is output on the photoelectric conversion means 37. That is, only when the pattern of the input image and the standard pattern of the Fourier transform image in the optical filter 35 are optically coincident with each other, a bright spot is generated on the back focal plane of the second lens 36, and the bright spot is generated. The photoelectric conversion means 37 converts the electric signal into an electric signal for detection.

However, in the above-mentioned structure, since the optical filter 35 is required to have a positioning accuracy on the order of the light wavelength, it is not suitable to change the optical filter frequently. for that reason,
Even if multiple types of optical filters (photosensitive materials) are exchanged to identify the authenticity of banknotes, the flexibility of optical filter exchange is lacking, so the optical filters can be used in correspondence with various input image patterns. Since it cannot be freely and instantly exchanged, it is difficult to efficiently perform the authenticity discrimination work. In addition, even when trying to accurately identify forgery of banknotes, the fact is that it is difficult to identify unless there are multiple types of input image patterns and identification patterns and true and false identification is not made. Therefore, in trying to use the conventional spatial frequency filtering device as a basic identifying means of the bill authenticity identifying device, it is a big obstacle that the optical filter or the like cannot be instantly and easily replaced. It was

Therefore, as a result of further intensive studies to overcome the above problems, the inventors of the present invention instantaneously and easily apply a plurality of types of identification filters to an input image pattern of an object to be inspected. We have found a new identification means that can be exchanged with each other and can perform more accurate true / false identification by analyzing several types of optical elements for the same input image pattern. The present invention has been completed.

[0009]

That is, the authenticity identifying apparatus for banknotes according to the present invention is an object image display means for displaying an image of a part of banknotes to be identified as a transparent image, and an image display thereof. A light source that illuminates the display image by means from one side,
A first Fourier transform lens arranged on the side opposite to the light source of the image display means so that the arrangement surface of the image display means is the front focal plane thereof, and the rear focal plane of the first Fourier transform lens. And a second Fourier transform lens arranged so that the focal plane on the rear side of the first Fourier transform lens is the focal plane on the front side thereof,
A third Fourier transform lens arranged so that the rear focal plane of the second Fourier transform lens is the front focal plane thereof, and regular banknotes arranged on the rear focal plane of the third Fourier transform lens The pattern holographic filter display means, the fourth Fourier transform lens arranged so that the arrangement surface of the holographic filter display means is the front focal plane thereof, and the rear focal plane of the fourth Fourier transform lens An optical system including the arranged light intensity detection means, an image input means for picking up an image of the inspection object displayed on the inspection object image display means, and an image input by the image input means is temporarily accumulated. Storage means for inspected object image and spatial frequency filter image for storing various spatial frequency filter images displayed in the spatial frequency filter display means Accumulating means, holographic filter image accumulating means for accumulating holographic filter images of regular banknote patterns corresponding to various spatial frequency components displayed in the holographic filter displaying means, inspected object image displaying means, spatial frequency An image display control device including a display image control means for controlling an image displayed on the filter display means and the holographic filter display means is provided, and a part of images of bills to be identified is matched according to various spatial frequency components. The feature is that true / false identification is performed by filtering.

Further, the authenticity identifying apparatus of the present invention uses a liquid crystal display element or a spatial light modulator as the object image display means, the spatial frequency filter display means and the holographic filter display means in the above technical means. Further, the image input means in the above technical means is provided with a color separation means.

In the above-mentioned technical means, with respect to the optical system, various transmissive images can be appropriately selected and displayed as the inspection object image display means, the spatial frequency filter display means and the holographic filter display means. If a liquid crystal display element or a spatial light modulator is applied, the other light sources, the respective Fourier transform lenses, the light intensity detecting means, etc. are the same as those used in the conventional spatial frequency filtering device. Things can be applied.

Further, in the above-mentioned technical means, the image display control device is provided with an image input means capable of picking up an image of an object to be inspected for a banknote to be identified, an image display means to be inspected, and a spatial frequency. Image storage means capable of storing various images to be displayed on the filter display means and the holographic filter display means, and display image control capable of appropriately selecting and controlling image contents necessary for each display means through the respective image storage means. It is not particularly limited as long as it has a means.

[0013]

EXAMPLES The present invention will be described in more detail below with reference to examples. Embodiment 1 FIG. 1 is a conceptual diagram of a bill authenticity identifying device showing an embodiment of the present invention. This authenticity identification device is roughly divided into
The optical system 1 and the image display control device 2 are provided.

As shown in the figure, the above optical system 1 includes an object image display means 3, a light source 4, a first Fourier transform lens 5, a spatial frequency filter display means 6, a second Fourier transform lens 7, and a second Fourier transform lens 7. The third Fourier transform lens 8, the holographic filter display means 9, the fourth Fourier transform lens 10, and the light intensity detection means 11 are included. In this embodiment, a liquid crystal display is used as each of the display means 3, 6, and 9, a laser generator is used as the light source 4, and a photoelectric conversion device is used as the light intensity detection means 11. Not limited to. Further, reference numeral 12 in the figure denotes a collimator lens for collimating the laser light from the light source 4. Further, each Fourier transform lens is arranged with reference to each focal plane as shown in the figure. In the figure, f indicates the focal length of each lens. That is, the first Fourier transform lens 5 is arranged such that the arrangement surface of the image display means 3 is the front focal plane thereof, and the second Fourier transform lens 7 is the rear focal point of the first Fourier transform lens 5. The third Fourier transform lens 8 is arranged such that the rear focal plane of the second Fourier transform lens 7 is the front focal plane thereof, and The Fourier transform lens 10 is arranged such that the arrangement surface of the holographic filter display means 9 is the front focal plane thereof.

The image display control device 2 includes an image input means 1
3, an inspection object image storage unit 14, a spatial frequency filter image storage unit 15, a holographic filter image storage unit 16, and a display image control unit 17. In the present embodiment, a scanner is used as the image input means 13, and each image storage means 14, 1
A read-only IC (ROM) is used for each of 5 and 16 and a central processing unit (CPU) is used as the display image control means 17, but the present invention is not limited to these.

The image data of the inspection object read by the scanner of the image input means 13 is temporarily stored in the inspection object image storage means 14. At this time, when the image input unit 13 having a color separation unit is used, the image information input by the input unit 13 is color separated by the color separation unit, and the color separated image data is accumulated. It is stored in the means 14. When the input image is not color-separated by the color separation unit, it is possible to display the input image directly on the inspection object image display unit 3 without storing it in the storage unit 14.

The spatial frequency filter image storage means 15 stores spatial frequency filter image data for extracting only specific spatial frequency components from the image of the object to be inspected. This spatial frequency filtered image is
The shape (filter pattern) was determined beforehand by computer simulation. This filter image 20 is specifically as illustrated in FIGS. 2a and 2b, and is configured such that its filter pattern portion 21 is light transmissive and the other portion 22 is non-light transmissive. ing. And such a filtered image 2
The image data of 0 is sent to the display means 6 and displayed.

Further, in the holographic filter image storage means 16, data of Fourier transform type computer generated holograms calculated in advance using each picture element on the holographic filter display means 9 as a sampling point, in other words, for each picture element. The data of the applied voltage corresponding to the transmittance of is accumulated. This is performed for a plurality of patterns of regular banknotes to be identified. In the holographic filter image, the data thus accumulated in the accumulating means 16 is used as an input signal, and the transmittance of each picture element on the holographic filter displaying means 9 is spatially modulated to obtain a Fourier transform type image. It is displayed in the form of a computer generated hologram.

On the other hand, in the display image control means 17,
Various images to be displayed by the inspection object image display means 3, the spatial frequency filter display means 6 and the holographic filter display means 9 are stored in the respective image storage means 14, 1.
A control work is performed in which the selected images are appropriately selected from 5 and 16 and the selected images are displayed in synchronization on each display unit. Therefore, the control means 17 instantly and easily exchanges the image of the object to be inspected, the spatial frequency filter image composed of a specific spatial frequency component and the holographic filter image corresponding to the spatial frequency component, and the predetermined display means Will be displayed.

Next, the operation of the authenticity discriminating apparatus according to this embodiment will be described. First, the scanner of the image input means 13 inputs an image of a banknote to be identified, and stores it in the storage means 14 as an inspection object image. Also,
The storage means 15 and 16 also store various predetermined spatial frequency filter images and holographic filter images. Then, the display image control means 17 selects a predetermined image of the object to be inspected, the spatial frequency filter image and the holographic filter image and causes the corresponding display means 3, 6 and 9 to simultaneously display them.

Thereafter, the laser light from the laser device of the light source 4 is collimated by the collimator lens 12 and the collimated light illuminates the object image displayed on the liquid crystal display of the object image image display means 3. To do. The illuminated image of the inspection object is the first Fourier transform lens 5
Fourier transform by the Fourier transform image (spatial frequency spectrum) and the spatial frequency filter display means 6
Formed on the liquid crystal display. Further, since a predetermined spatial frequency filter image is displayed on the display means 6, this filter image and the Fourier transform image are superimposed, whereby a specific spatial frequency of the Fourier transform image of the inspection object image is obtained. Only the components are filtered and extracted.

The extracted Fourier transform image component of the object image is Fourier transformed by the second Fourier transform lens 7 to form a filtered image on the focal plane on the rear side. Fourier transform is performed again by the Fourier transform lens 8 of 3, and the Fourier transform image is holographic filter display means 9
Formed on a liquid crystal display. Further, since the display means 9 displays the holographic filter image of the regular banknotes corresponding to the frequency components of the spatial frequency filter, the display means 9 performs the matched filtering on the Fourier transform image.

The result of the matched filtering is inverse Fourier transformed by the fourth Fourier transform lens 10, and the reproduced image is formed on the photoelectric conversion element 11. As a result, when there is a correlation between the inspection object and the regular banknotes, a bright spot appears in the reproduced image, so the light intensity of the bright spot is converted into an electric signal and detected, and the bright spot is detected. Is confirmed to have a light intensity above a certain level, the bills to be inspected are identified as "genuine", and on the contrary, the bright spot is not detected or is detected. Also, when the light intensity is lower than the specified level, the bills to be inspected are identified as "counterfeit."

In order to improve the accuracy of the authenticity discrimination, the display image of the object to be inspected is replaced with the image content of another portion, or the spatial frequency component of the spatial frequency filter for the same image of the object to be inspected. Alternatively, the above operation may be similarly repeated and repeated. The operation for that purpose can be performed easily and instantaneously by changing the display image on each display means by the display image control means 17.

Example 2 A true / false discrimination device having the same configuration as in Example 1 except that an optical crystal such as BSO was used as a spatial light modulator instead of a liquid crystal display as each of the display means 3, 6, and 9. .
Also with this device, it is possible to perform the genuine / counterfeit discrimination of banknotes by the same operation as the device according to the first embodiment.

[0026]

As described above, according to the apparatus of the present invention, it is possible to instantly and easily change the inspection object image, the spatial frequency filter image and the holographic filter image. Moreover, the change of each display image can be controlled at high speed by the control means.
Therefore, in particular, by changing the type of the spatial frequency filter, it is possible to extract a plurality of types of spatial frequency components with respect to the same inspected image, and at the same time, a regular banknote pattern corresponding to each spatial frequency component. A plurality of types of matched filtering can be performed by displaying the holographic filter image of (1) on the liquid crystal display or the like of the display means. Further, by performing color separation processing on the image of the object to be inspected, matched filtering can be performed for each of the color-separated images, which also improves the identification accuracy. As described above, according to the present invention, it is possible to quickly and accurately discriminate bills from each other.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a true / false identification device showing an embodiment of the present invention.

FIG. 2 is a front view showing a typical example of a spatial frequency filter.

FIG. 3 is a conceptual diagram showing a spatial frequency filtering technique applied to a conventional optical information processing means.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical system, 2 ... Image display control device, 3 ... Inspected object image display means, 4 ... Light source, 5 ... First Fourier transform lens,
6 ... Spatial frequency filter display means, 7 ... Second Fourier transform lens, 8 ... Third Fourier transform lens, 9 ... Holographic filter display means, 10 ... Light intensity detection means, 13 ... Image input means, 14 ... Cover Storage means for inspection object image, 15 ... Storage means for spatial frequency filter image, 1
6 ... Storage means for holographic filter image, 17
... Display image control means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G06F 15/64 E 9073-5L 320 C 9073-5L

Claims (3)

[Claims] 1. An object image display means for displaying a partial image of a banknote to be identified as a transparent image, a light source for irradiating the image displayed by the image display means from one side, and a light source for the image display means. A first Fourier transform lens arranged on the opposite side to the focal plane on the front side of the image display means, and a spatial frequency filter arranged on the focal plane on the rear side of the first Fourier transform lens. Display means, first
Second Fourier transform lens arranged such that the rear focal plane of the Fourier transform lens of is a front focal plane, and the rear focal plane of the second Fourier transform lens is its front focal plane. A third Fourier transform lens arranged as
A holographic filter display means of a regular banknote pattern arranged on the focal plane on the rear side of the third Fourier transform lens, and a fourth holographic filter display means on which the holographic filter display means is disposed on the front side thereof. An optical system including a Fourier transform lens and a light intensity detecting means arranged on the focal plane on the rear side of the fourth Fourier transform lens; Input means, and storage means for inspected image for temporarily storing the image input by the image input means,
Spatial frequency filter image storage means for storing various spatial frequency filter images displayed on the spatial frequency filter display means, and holographic regular banknote pattern corresponding to various spatial frequency components displayed on the holographic filter display means Image display control device comprising holographic filter image storage means for storing filter images, display object image display means, spatial frequency filter display means, and display image control means for controlling images displayed on the holographic filter display means , And a genuine / counterfeit discrimination apparatus for bills, which performs true / false discrimination by performing matched filtering on a partial image of the bills to be discriminated according to various spatial frequency components. 2. An authenticity discriminating apparatus for bills according to claim 1, wherein the inspection object image display means, the spatial frequency filter display means and the holographic filter display means are liquid crystal display elements or spatial light modulation elements. 3. The authenticity discriminating device for banknotes according to claim 1, wherein the image inputting means comprises color separation means.