Device and method for identifying bank note

• US 6,050,387 A
• Filed: 03/03/1998
• Issued: 04/18/2000
• Est. Priority Date: 09/10/1997
• Status: Expired due to Term

• Current Assignee: Nippon Conlux Co., Ltd. (Crane Company)
• Original Assignee: Yokohama Denshi Kogyo Kabushiki Kaisha
• Inventors: Iwaki, Kunihide
• Primary Examiner(s): Olszewski, Robert P.
• Assistant Examiner(s): JAKETIC, BRYAN J
• Application Number:
  US09/033,967
• Time in Patent Office: 777 Days
• Field of Search: 194/207, 382/135, 250/205, 250/556, 356/71
• US Class Current: 194/207
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 3/46 Measurement of colour; Colour measuring devices, e.g. colorimeters measuring colour temperature G01J5/60
• CPC Class Codes: G01J 3/501 Colorimeters using spectrally-selective light sources, e.g. LEDs
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/59 Transmissivity G01N21/25 takes precedence
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths

Abstract

A device and method for identifying a bank note with simple construction offering easy adjustment and a reliable performance independent of the environment under which it works. The device enables identification of a bank note printed in color with a genuine one by the method of adjusting the intensity of light emission so as to equalize sensitivity of a photoelectric transducer to a light source A and a light source B, emitting lights in different wavelengths when there is no object to be identified, detecting the difference in sensitivity of detected signals of light transmitted through or reflected by the object to be identified as output of a high-pass filter, and sampling, in a sampling circuit, a signal based on the sensitivity difference and proportional to the difference between detected value for light source A and sensitivity of light source B to conduct identification based on the sampling value.

Claims

1. A device for identifying a bank note comprising:

first light emitting means for emitting light of a first wavelength;

second light emitting means for emitting light of a second wavelength different from the first wavelength;

first drive means for driving said first light emitting means to emit light;

second drive means for driving said second light emitting means to emit light;

light emission control means for activating said first and second drive means by alternately switching them;

light receiving means for receiving light emitted by said first and second light emitting means and outputting electrical signals corresponding with intensities of received light;

adjustment means for adjusting intensity of light by controlling at least one of said first and second drive means so that a difference in level between electrical signals corresponding with the light of the first and second wavelength and output by said light receiving means falls within a specified range;

means for fixing the intensity of light to be emitted by said first and second light emitting means adjusted by said adjusting means when an object to be identified reaches a position between said first and second light emitting means and said light receiving means;

extracting means for extracting an alternating current component of the electrical signals output from said light receiving means when said object to be identified is transported between said first and second light emitting means and said light receiving means; and

sampling means for sampling the alternating current component extracted by said extracting means and emitted by one of said first and second light emitting means, whereby identification of the object is conducted based on a sampling value obtained by said sampling means.

2. A device for identifying a bank note as set forth in claim 1, wherein said identification of a bank note is conducted by checking similarity between the sampling value obtained from said sampling means and a value of a genuine object to be identified which is stored in advance.

3. A device for identifying a bank note as set forth in claim 1, wherein said first and second light emitting means are constructed with first and second LEDs, respectively, and said first and second LEDs and said light receiving means are arranged to face each other opposedly, said object to be identified being transported between said first and second LEDs and said light receiving means, while an optical filter is disposed between said first and second LEDs and said light receiving means.

4. A device for identifying a bank note as set forth in claim 3, wherein said first and second LEDs are constructed with a red LED and a green LED.

5. A device for identifying a bank note as set forth in claim 1, wherein said first and second light emitting means are constructed with first and second LEDs, respectively, and said light receiving means is disposed between said first and said second LEDs so as to be able to receive light emitted from both of said first and second LEDs after the light is reflected from a reference reflector, while said object to be identified is transported between said first LED, said second LED, said light receiving means and said reference reflector.

6. A device for identifying a bank note as set forth in claim 5, wherein said first and second light emitting diodes are constructed with a red LED and a green LED.

7. A device for identifying a bank note as set forth in claim 3, wherein said first and second light emitting diodes are integrated into a 2-colored LED.

8. A device for identifying a bank note as set forth in claim 5, wherein said first and second light emitting diodes are integrated into a 2-colored LED.

9. A method for identifying a bank note with a device including 2 kinds of light emitting means emitting light in different wavelengths, and light receiving means for outputting electrical signals corresponding with detected light intensity by receiving light emitted from said 2 kinds of light emitting means, said method comprising the steps of;

controlling the intensity of light emission from said 2 kinds of light emitting means so as to equalize approximately the electrical signals from said 2 kinds of light receiving means by sequentially switching said 2 kinds of light emitting means, when said object to be identified is not being identified, to eliminate variations in performance of both of said 2 kinds of light emitting means and said light receiving means;

emitting light from said 2 kinds of light emitting means at an intensity of light emission controlled before identification, when said object to be identified is being identified;

extracting an alternating current component in an output of said light receiving means to determine variations of quantity of received light from said 2 kinds of said light emitting means when said object to be identified is transported between both of said 2 kinds of light emitting means and said light receiving means;

detecting variations in the output of said light receiving means as derived from received light from one of said 2 kinds of light emitting means; and

identifying a bank note as a genuine one by determining that the detected variations are similar to a pattern stored in advance.