TWI220235B - Machine vision for certificating color variable thin film - Google Patents

Abstract

Techniques that could detect the color variation of color variable thin film automatically are proposed in this invention. The color variable thin film is the film which displays different colors under different observation angles. Therefore, the certification of whether a film is a standard color variable thin film or not could be done by measuring and comparing spectrum information of reflected lights coming from different reflection angles. The technologies disclosed in this invention could be adopted in the certification system which uses color variable thin film as identification, for example, the paper currency.

Description

V. Description of the invention (1) __ Field of invention ^ Invention tj: Department: a technique for measuring the color change of a color-changing film, using this color-changing film 2: identifying the authenticity of the color-changing film, the present invention can be applied to the use of Ba Tao臈 As a system for identification technology, such as banknotes. Background for the use of inventions Although plastic currency has gradually become popular in the past ten years, it has become popular in my financial institutions. 'Every type of financial institution = the use of paper money is still the most-grade, In the face of such a large amount of real currency: the average of the currency reaches one million yuan, and the rampant flow of counterfeit banknotes is not only a problem that will not cause a lot of damage to the counterfeit banknote group and the financial stability of the family. for;. Person: 2 'It is even more harmful to the national currency punishment regulations', the highest special punishment; For the financial industry, anyone who finds it is a counterfeit banknote will directly kill his or her life. . Therefore, the widespread use of the second bank must meet the characteristics of large-scale circulation of banknotes, and the technique must include technical printing that can be recognized by the naked eye, color-changing inks, security lines, hidden characters, and micro-cooperation with the needs of financial institutions to quickly detect large numbers of banknotes. There are several items of fiber yarn and magnetic ink, etc .; the face of the ever-changing fake ^ work = Rong $ -like counterfeit banknote automatic identification technology has been proven to be inadequate, many financial =

Organizations must also use human error when collecting large amounts of cash, and one of them has proven to be the most effective color-changing ink. Manual identification and screening of counterfeit banknotes to avoid damage. The artificial identification anti-counterfeiting technology is the added currency in the latest revision of almost two or two S3 anti-counterfeiting technologies. And the various ink coloring formulas also recognize this. The mechanism is automatic identification of counterfeit banknotes. Technology to develop automatic 4i recognition of the banknote detector. Summary of the invention μ ▲ The present invention proposes a technology that can automatically identify the authenticity of a color-changing film. The clear color-changing film means that the film can change different colors under different viewing angles. The principle of changing the color effect is based on the thin film optics of multilayer film interference. The reflectivity of a multilayer film is determined by the reflection coefficient and the reflected optical path of each layer, and the change of the incident angle will affect the reflected optical path. Therefore, for a certain film system From a structural point of view, the reflectivity of light at various wavelengths is a function of the angle of incidence (or reflection angle: according to optical principles, the reflection angle is equal to the angle of incidence), which means that each incident angle / reflection angle has a relative reflected light spectrum. As shown in the second figure, the reflection light spectrum of the film of the color-changing ink under the reflection angle A and the reflection angle B are 0211 and 0212, respectively. The wavelengths of the highest reaction intensity corresponding to the reflection light spectrum 0211 and 0212 are 0221 and 0 222, respectively. , So as to show the difference in outstanding luster, it is called color-changing ink.

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V. Description of the invention (3) According to the above description, the characteristics of the color-changing film are reflected light with two or more reflection angles. The purpose of the invention is to provide a banknote detector that can automatically identify the color-changing ink film on paper money. In addition, the present invention proposes to compare two or spectral information to identify the discoloration film. This technology can identify the color-changing film, which can be used to develop a new generation of anti-counterfeit automatic identification.

The color-changing film anti-counterfeiting automatic identification module provided by the present invention includes at least two or more sets of light detectors to measure the reflected light spectrum information of two or more sets of reflection angles, and compares them for identification. Take two groups as an example ^ As shown in the first figure, the light detector A (0111) and the light detector B (〇112) are placed at the reflection angle A (0121) and the reflection angle B (0122), such as the light detector The frequency and spectrum information measured by a is the light intensity of the band where the spectral response of the standard color-changing film is the strongest at the reflection angle A, while the frequency spectrum information measured by the photodetector B is the spectrum response of the standard color-changing film at the reflection angle B. As shown in the third figure, 〇3 η and 0312 are the spectral characteristics of the color-changing film under a fixed and stable white light source at the reflection angle A and reflection angle B, respectively, and 321 and 0322 are light, respectively. Spectral characteristic curves measured by Detector A and Photodetector B are the bands with the strongest spectral response of the standard color-changing film at the reflection angle. When the film under test is a standard color-changing film, The ratio of the measured signals 331 and 332 will show a special standard value due to the color change of the color-changing film with the viewing angle. If the signal ratio of the two light detectors deviates too far from the special standard value, the measured film can be judged. Not a standard discoloration film. Spectral characteristic curve of the specified photodetector measurement can be achieved by attaching a photodiode (ph〇t〇di〇de) filter, or by controlling the emission band of the light source inside the test module, as shown in the example in the second figure China 'needs a total of two sets of light sources that emit specific bands corresponding to two

Page 10 1220235 V. Description of the invention (4) Optical detectors with specified measurement spectrum band. In addition, the spectrum information measured by the 'light detector' can also be directly the color information presented by the reflected light at the reflection angle. It can be directly captured by using a charge coupled device (CCD) or a spectrometer as the light detector. Taking the color information presented by the reflected light, it can be discriminated whether the measured film is a color-changing film by comparing the variability of the colors presented at two reflection angles. Detailed description of the invention The upper reflection angle is selected based on the principle of two standards. The film of the color film determines the waveband that is the film under test when it is selected. It can be determined that the spectrum of the light source emits light at a frequency in degrees. Spectral reflected light or two or more color-changing films can use the light spectral response. At the reflection angle, the standard color-changing entire identification mode reflects the light spectrum to identify the reflection spectrum, light source, and light detector spectrum of the thin film under test. The present invention proposes to compare two or two color-changing films by using spectral information. Firstly, the light detector must be placed at the reflection angle. The selection of the reflection angle can produce the largest color change under the reflection angle. The spectrometer measures the standard change at each reflection angle state as a reference for determining the reflection angle selection. After the reflection angle is selected, the main band of the standard color-changing thin spectral response (meaning the color presented) is the main identification frequency band of the main group of the spectral response of the film at the selected reflection angle. As long as the information under the main identification frequency band is captured at each reflection angle Take it out to compare whether the film is a standard color-changing film. The spectrum information of the reflected light detected by the light detector is determined by the following parameters. The measured spectrum is measured at the reflection angle of the measured film, where the measured film is at the reflection angle. 'And other will affect the detection of light detector

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These parameters can be used to limit the acquisition of the main identification band information. These parameters can be discussed in two parts: source and light detector. False "• Two sets of reflection angles have been selected for a standard color-changing film, reflection and reflection angle B, and each group of reflection angles corresponds to a main identification frequency band. Main identification 2 & is the main frequency response of the standard color-changing film at the selected reflection angle. Band, main recognition frequency band A and main recognition frequency band B: Example 1: Using light sources as the main recognition frequency band information selection Two sets of light sources respectively only emit light signals of the main recognition frequency band, and the light source body and light signals of the main recognition frequency band A The light source B only sends out the main identification frequency band B ,, > signals. In addition, two sets of light detectors that can detect the light intensity of the main identification frequency band are selected. As shown in the fourth figure, the light source "〇411) and a light detection Device 1 (〇412; placed at a position corresponding to the reflection angle A (〇4〇1), similarly, the light source B and a light Fu 2 is placed at a position corresponding to the reflection angle B, the light source A and light detection The identification module must be isolated from the source B and the light detector 2 to prevent interference from the main identification frequency band. Therefore, the identification mechanism of the entire module is as shown in the third figure. 0311 and 0312 are standard color changes. Film under a fixed and stable white light source Spectral characteristics presented by reflection angle A and reflection angle B, 〇321 and 〇322 are the spectral characteristics of light source A and light source B respectively, focusing on the main identification frequency band A and the main identification frequency band B, respectively, and the measured film is the standard In the case of a color-changing film, the ratio of the signals 0331 and 0332 measured by the two photodetectors will appear due to the factor that the color-changing film changes color with the viewing angle-a special standard value. If the signal ratio of the two photodetectors deviates from the special standard The film is not a standard color-changing film.% ^ '

1220235 V. Description of the invention (6) In addition, the recognition rate of the module can be improved by increasing the number of light detectors. Each group of light sources is provided with a light detector at the corresponding two sets of reflection angles. As shown in the fifth figure, only The light source A (0 5 0 1) that emits the optical signal of the main identification frequency band A corresponds to two sets of light detectors respectively: the light detector K0511) is placed at the reflection angle A (〇521), and the light detector 3 (0512) is placed at the reflection Angle b (〇522), because the light source corresponds to more than one set of reflection angles, the choice of the light source must consider the larger diffusion angle, or you can use two sets of the same light source to place the reflection angles of the corresponding light detectors 'As shown in the sixth figure, the light source A1 (060 1) that only emits the optical signal of the main identification frequency band A is placed at the reflection angle A (052i), corresponding to the light detector K05U), and only emits the light source of the human optical signal of the main identification frequency band. 2 (0602) is placed at a reflection angle of 8 (0522), corresponding to the light detector 3 (0 51 2). The design of adding a group of light sources can increase the signal to noise ratio of the signal obtained by the light detector. The light source B, which only emits the light signal of the main identification frequency band B, corresponds to two sets of optical debt devices respectively: The light detector 4 is placed in the reflection a. The light detector 2 is placed at the reflection angle B. It should be noted that the spatial configuration of the two sets of light sources and their corresponding light detectors must be optically isolated to avoid interference from the main identification frequency band, so the entire module The identification mechanism is as shown in the seventh figure, with 0311 and 0312 as the standard, the spectral characteristics of the color film under a fixed and stable white light source at the reflection angle A and the reflection angle B, and 0321 and 0322 are the light source A, respectively. The spectral characteristic curves of the light source and the light source B are respectively concentrated in the main identification frequency band A and the main identification frequency band B. In the case that the ^ film is a standard color-changing film, the signals 033 1 and 0731 measured by the light detector 丨 and the light detector 3 The light intensity of the standard color-changing film at the reflection angle a and reflection at the main recognition frequency band A, respectively. The photodetectors 4 and 2 detect the numbers 0 732 and 0 332, respectively. Angle 8 under ^ Master

Page 13 V. Description of the invention (7) '一 "-: = Light intensity of band B. There is a proper safety identification procedure for the light source intensity and the placement angle. You only need to compare the values of 0331 and 0731 and 0732 and 0332. If °! 31 is greater than 0731 and 0332 is greater than 0732, the measured film is Membrane, simple comparison circuit is not only cheaper to implement, but also much faster. In addition, under the above-mentioned architecture, modifying the discrimination order can further accurately determine whether the discoloration of the color-changing film is consistent with the standard color-changing film. Dividing the ratio between 033 1 and 0731 and the ratio between 0732 and 0332 'is an index for determining the color change. Embodiment 2: Restriction of using the optical detector as the main identification band information_ Select two sets of optical detectors that can only receive the optical signals of the main identification band. This optical detector can use a photodiode plus the main Recognition f member & light sheet to achieve, the light detector A only receives the optical signal of the main identification frequency band A The light detector B only receives the light signal of the main identification frequency band B, the selection of the light source in this embodiment requires only its spectrum The response covers two main identification frequency bands, such as white light-emitting diodes (LEDs), and even the module does not need a built-in light source and uses an external light source, as long as it is calibrated before using the identification module again. Under the framework of the module's built-in light source, the identification standards are easier to control. The architecture of this embodiment is shown in the eighth figure, and one set of light sources corresponds to two sets of light detectors respectively: light detector A (0811) is placed at a reflection angle A (〇521), and light detector B (0812) is placed At the reflection angle b (〇522), since the light source (〇80) corresponds to more than one set of reflection angles, the choice of the light source must consider the larger diffusion angle 'or directly use two sets of light sources to correspond to different reflection angles. Light detector, as shown in the ninth figure, the light source 1 (0901) is placed at a reflection angle a (〇521), and the

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Light detector A (0811), light source 2 (0902) should be placed at reflection angle B (05220), yes, light detector B (0 8 1 2), adding a set of light source design can increase the light detector's known vanadium Signa L t〇noise ratio; under this structure, the identification mechanism of the positive module is shown in the third figure, 〇311 and 〇31 2 are standard color-changing films in a fixed The spectral characteristics of reflection angle A and reflection angle B under a stable white light source. 321 and 322 are the detection spectrum characteristic curves of light detection and light detection b, respectively, which are concentrated in the main identification frequency band A and the main identification. Frequency band B. In the case where the measured film is a standard color-changing film, the ratio of the signal 033 丨 and “” measured by the two photodetectors will show a special standard value due to the factor that the color-changing thickness T changes with the viewing angle. If the signal ratio of the two optical devices deviates too far from the special standard value, it can be judged that the measured film is not a standard color-changing film. Real target example two: the light source and the light detector are used as the main identification frequency band limitation

Use the light source and the light detector as the main identification band information at the same time, select f two sets of light sources to send only the light signal of the main identification frequency band, light source A only sends ^, the light signal of identification frequency band A, and light source B only sends the main identification frequency band. B's light 2 旒, another two sets of light detectors that can only detect the light intensity of the main identification band, ^ Detector A only receives light signals of the main identification band, and light detector B only receives light signals of the main 2 identification band B As shown in the tenth figure, the light source a (〇4U) and the light, and the device A (1012) are placed at positions corresponding to the reflection angle a (〇4〇i). Similarly, light and a light detector B is placed at a position corresponding to the reflection angle B, so the entire mode f = identification mechanism is as shown in the third figure, 〇311 and 〇312 are standard variations, respectively; the film is under a fixed and stable white light source at the reflection angle A and Reflection angle B

1220235 V. Description of the invention (9) '--------: Characteristics' 0321 is the special spectrum result of emission and debt measurement of light source A and optical debt device 4 and 0322 is the spectrum and emission spectrum measurement of light source b and optical detection device% " The results are focused on the main identification frequency band A and the main identification frequency stomach respectively. In the case that the measured film is a standard color-changing film, the ratio of the signals 033 1 and 0332 paid by the two photodetectors varies with the observation. When the angle changes color, the element will present a special standard value. If the signal ratio of the two light detectors deviates too far from the special standard value, it can be judged that the measured film is not a standard color-changing film. In addition, the identification rate of the module can be increased by increasing the number of optical debt devices. Each group emits only light sources in the main identification frequency band, and a light that can detect the intensity of the main identification frequency band is set at the corresponding two reflection angles. As shown in the eleventh figure, the light source A (0501) that only emits the optical signal of the main identification frequency band A corresponds to two sets of light detectors that only receive the main identification frequency band A: the light detector "(丨丨 丨 丨 彡 The reflection angle A (052 1) and the light detector A2 (1112) are placed at the reflection angle B (0522). Since the light source corresponds to more than one set of reflection angles, the choice of the light source must consider the diffusion angle. The larger one, or you can also use two sets of the same light source to place the reflection angle of the corresponding light detector, as shown in Figure 12, only the light source A1 (060 1) that emits only the main identification frequency A light signal is placed in the reflection The angle A (0521) corresponds to the light detector Al (1211) that only receives the optical signal of the main recognition frequency band A, and the light source A2 (06 02) that only emits the optical signal of the main recognition frequency band A is placed at the reflection angle B (0 522). Corresponding to the light detector A2 (1 21 2) that only receives the light signal of the main identification frequency band A, the design of adding a group of light sources can be The resulting optical signal plus noise ratio of an investigation (signal to noise ratio); Similarly, the light source emits only the main frequency identification B B segment of the optical signal received corresponding to only the main groups of identification band b

Page 16 1220235 V. Description of the invention (Light): Light device: light detector B1 is placed at reflection angle a, light detector B2 is placed at reflection angle B, so the identification mechanism of the entire module is as shown in the seventh figure Shown, 0311 and 〇31 2 are the spectral characteristics of the quasi-chromic film under a fixed and stable white light source at the reflection angle A and the reflection angle B, respectively. 321 is the light source A and light detector human hair ^ and detection spectrum. The result of multiplying the characteristics, 03 22 is the result of multiplying the emission and detection spectrum characteristics of the light source B and the light detector 8, which are respectively concentrated in the main identification frequency band A and the main identification frequency band B, and the measured film is a standard color-changing film. In this case, the signals 0331 and 0731 measured by light detector A1 and light detector A2 are the light intensities of the standard color-changing film at the reflection angle A and reflection angle B in the main identification frequency band a, respectively. The signals 0732 and 0332 measured by the light detector B2 are the light intensities of the standard color-changing film at the reflection angle A and the reflection angle B in the main recognition frequency band b, respectively. With proper arrangements for the intensity of the light source and the placement angle, the identification program only needs to compare the sizes of 0331 and 0731 and 0732 and 0332. If 0331 is larger than 0 7 3 1 and 0 3 3 2 is larger than 0 7 3 2, it will be The test film is a color-changing film. The simple comparison circuit is not only less expensive to implement, but also has a much faster identification rate. In addition, under the aforementioned architecture, modifying the identification program can further accurately determine whether the color-changing degree of the color-changing film is the same as the standard. The film is consistent, and dividing the ratio between 0331 and 0 731 and the ratio between 0732 and 0332 is an index for determining the discoloration degree. Embodiment 4: The spectrum information measured by the light detector is directly the color information presented by the reflected light at the reflection angle, such as a charge coupled device (CCD) or a spectrometer. Two sets of light detectors that can directly measure the color information of reflected light

Page 17 1220235 V. Description of the invention (11) For the angle of emission A and reflection angle B, the degree of discoloration of the measured film at each reflection angle can be directly judged by the signal captured by the light detector. The spectrum of the light source in this embodiment The response must cover the entire visible light range so that the light detector can capture the color information of the reflected light at that angle. Therefore, the light source can be any light-emitting element that can generate white light. In the identification module, the light source corresponds to more than one group of light sources. The reflection angle, so the choice of the light source must consider the larger diffusion angle, or you can use two sets of the same light source to place the reflection angle of the corresponding light detector. The above four embodiments are directed to a standard color-changing film, because different color-changing films each have their own optimal color-change observation angle and color system of change. For example, there are two sets of changes in NT $ 500 and one hundred. The yuan is the same series, one thousand yuan, two hundred yuan and two thousand yuan issued in July this year are the same color changing system. If this module is built in a system that recognizes the authenticity of banknotes, each color changing system is equipped with a set of identification modes. The group is considered to be the best design, but if considering the cost, different color changing systems can choose the same two or two sets of reflection angles, and the main identification section of each color changing system at the selected reflection angle is also compromised. A frequency band that can be shared by each color-changing system is reduced to reduce the number of components of the light detector and the light source. Of course, the premise is that the recognition rate must be maintained at a certain level of L. In addition, because this system has the ability to discern colors, these two are applied to discriminating paper currency systems that use color as the currency value segment, and can also calculate the total currency value. On the basis of this, the preferred embodiments of the present invention have been described in sufficient detail here to enable those skilled in the art to utilize the present invention. Ran should =

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Page 19 1220235 Brief description of the drawings-In order to make the above and other objects, features, and advantages of the present invention more obvious and easy to understand, the present invention will be described in detail in the following description in conjunction with the drawings. In the drawings: ^ :: standby f, which illustrates the architecture of the embodiment-'The two optical detectors are arranged at different reflection angles to measure specific spectrum information. The second picture ... The discolored thin 臈 is reflected in different observations. The third picture ... The spectral response of the present invention. Specific spectrum information. Figure 4: Identification of the frequency band of the shell device for identification purposes. ~ Using a light source as the main identification ^ ❿ Figure 1 The structure of one embodiment of the present invention illustrates the limitation of the Litian frequency band. Using a light source as the master. • The first embodiment of the present invention is described as one of the limitations of frequency slaves. Use the light source as the main identification ί: f: The identification mechanism of the present invention explains that the light detection and examination information, and special spectrum information. The eighth figure for identification purposes ... The embodiment of the present invention limits the identification frequency band. β, using a light detector as the main discriminator. Figure 9: An embodiment of the present invention sets the PP generation of a frequency band. Detector first determines the picture. Figure 10 ... Embodiment 1 of the present invention = Restriction of the main frequency band. , 0 Use of light sources and light detectors 11 Figures ... The embodiment of the present invention limits the frequency of the main identification frequency band. "Using light source and light detection on page 20 1220235 The diagram briefly illustrates the twelfth figure: one of the architectural description of the embodiment of the present invention, using the light source and the light detector as the main identification frequency band limitation. 'Drawing reference number comparison 0101: measured Film 0111: Light Detector 011 2: Light Detector

0121: Reflection angle A 0122: Reflection angle β 0211: Spectral response of light reflected by standard color changing film at reflection angle A 0212: Spectral response of light reflected by standard color change film at reflection angle B 022 1: Standard color change film at reflection angle A The color presented below is 0222: The color appearance of the standard color-changing film at the reflection angle B 0 311: The spectrum characteristic of the standard color-changing film at the reflection angle a under a fixed and stable white light source 0312: The standard color-change film is fixed and stable Spectral characteristics of white light source at reflection angle b 032 1: The result of multiplying the light source at the reflection angle A with the light detector's emission and detection spectrum characteristics 0 3 2 2: The light source at the reflection angle B and the light detection The result of multiplying the transmitter's emission and detection spectrum characteristics 0331: the signal intensity measured by the light detector at the reflection angle A 0 3 3 2: the signal intensity measured by the light detector at the reflection angle B

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040 1 ·· Reflection angle A

Light source A of the light signal for the infanter segment A 0 411 ·· Only the main identification 0412: Light Detector 1

Light source A 050 1 that recognizes the optical signal in frequency band A. Only the main 0511 is emitted: light detector 1

0512: Light Detector 3 052 1 · Reflection angle A 0522 · Reflection angle B

060 1: Light source A1 0602 that emits only the main identification frequency band a light signal A2 0731 · Light source A2 0731 that only emits the main identification frequency band a light signal 0731: Standard color-changing film reflects the light intensity of jBT in the main identification frequency band a 0732 Light intensity at the reflection angle a in the main recognition frequency band 0 8 0 1: Light source 0811: Light detector a that only receives light signals in the main recognition frequency band a 0812: Light detector that only receives light signals in the main recognition frequency band b 0 9 0 1: light source 1 090 1: light source 2

1012: Photodetector A that only receives optical signals in the main identification band A

1111 ·· Light source A1 that only emits optical signals in the main identification frequency band A 1112: Light source A2 that only emits optical signals in the main identification frequency band A 1 1 211: Light detector A1 1 21 2 which only receives optical signals in the main identification frequency band A Light Detector A2 for Identifying Optical Signals in Band A

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Claims (1)

1220235 / 、、 Scope of patent application '-------- A technology that can automatically identify the color-changing film of the invention mentioned in this case, its management is as stated previously, but no matter how the changes and modifications are, The essence and spirit of the following patent application scope. 1 · A module capable of automatically recognizing a color-changing film, comprising: two or more light detectors capable of measuring spectrum information of reflected light; the aforementioned two or more light detectors are arranged in At least two sets of reflection angles. 2 · The photodetector that can measure the spectrum information of the reflected light according to item 1 of the scope of the patent application, which can be a photodiode plus a filter of a specified band. 3. The photodetector that can measure the spectrum information of the reflected light as described in item 1 of the scope of the patent application, which can be a photosensitive coupling element (CCD). 4. According to the measurable reflected light spectrum information 1 & described in the first patent application scope, the light detector may be a spectrometer. 5 · According to item 1 of the scope of patent application, it can automatically identify the color-changing film A module, which can be used to identify paper money. 6 · — A module that can automatically identify the authenticity of the color-changing film, which includes: · one or more light sources; two or more light detectors; the aforementioned two or more light detectors The device is arranged in at least two sets of reflection and degree 7.The light source according to item 6 of the scope of patent application can be a light emitting diode (LED). Page 23 1220235 6. Scope of patent application 8. The photodetector according to item 6 of the scope of patent application may be a photodiode. 9 · The photodetector according to item 6 of the scope of the patent application can be a photosensitive coupling element (CCD). I 0 · The light detector according to item 6 of the patent application scope can be a spectrometer 〇II · The module that can automatically identify the color-changing film according to item 6 of the patent application scope can be used to identify paper money . —One I