Rolling fingerprint acquisition method based on thermochromic principle

A temperature-induced discoloration and fingerprint technology, which is applied in the direction of instruments, character and pattern recognition, computer components, etc., can solve the problems of stagnant fingerprint management work, blurred fingerprints, and unsatisfactory results.

Inactive Publication Date: 2015-12-16
JIANGNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the fuzzy fingerprints caused by the traditional fingerprint printing method, many cannot be entered into the computer automatic fingerprint identification system normally, resulting in the stagnation of fingerprint management.
In response to this problem, Chinese scientific and technological workers are also carrying out continuou...

Method used

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  • Rolling fingerprint acquisition method based on thermochromic principle
  • Rolling fingerprint acquisition method based on thermochromic principle
  • Rolling fingerprint acquisition method based on thermochromic principle

Examples

Experimental program
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Effect test

specific Embodiment approach

[0020] 1) Using crystal violet lactone compound as the capsule core material and urea-formaldehyde resin as the capsule wall material, a thermochromic microcapsule was prepared by in-situ polymerization (the scanning electron microscope image of the thermochromic microcapsule is shown in figure 1 , the differential scanning calorimetry diagram is shown in figure 2 , see the thermogravimetric analysis diagram image 3 ).

[0021] 2) The dispersion liquid formed by mixing the prepared thermochromic microcapsules with 0.7% aqueous solution of sodium carboxymethyl cellulose is used as a drop coating solution, and the drip coating method is used to drip and flow on the surface of a glass slide to obtain a thermochromic film ( The UV reflection diagram of the thermochromic film is shown in Figure 4 ).

[0022] 3) Use a heater to adjust the surface temperature of the film, and place the collected person's finger on the thermochromic film to roll (see the influence of film surfac...

example 1

[0027] By adjusting the surface temperature of the film to 52°C, a clear fingerprint image can be obtained by rolling a finger on the thermochromic film. The obtained fingerprint image is relatively clear, and the secondary information including the fingerprint itself can also be seen with the naked eye (see Figure 5 B). After the fingerprint image is obtained, the slide is cooled until the fingerprint disappears and the thermochromic film returns to its previous dark blue color.

example 2

[0029] By adjusting the surface temperature of the film to 54°C, the subject’s finger rolled on the thermochromic film, took it out and took a picture. Because the surface temperature of the film is too high, the temperature of the place on the thermochromic film in contact with the finger cannot be completely lowered below the discoloration point, and the discoloration reaction is not complete, resulting in an incomplete fingerprint image, and even almost no fingerprint information ( See Figure 5 A).

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Abstract

The invention relates to a rolling fingerprint acquisition method based on thermochromic principle, and belongs to the field of materials chemistry. A thermochromic microcapsule is prepared in an in-situ polymerization process by taking a crystal violet lactone compound as the capsule core material and urea-formaldehyde resin as a capsule wall material. The film surface temperature is controlled to obtain a proper rolling fingerprint acquisition condition. The method is easy, feasible, rapid and reliable, a series of problems in traditional rolling fingerprint acquisition can be solved, acquired fingerprint images are clear and reliable, and the method has great significance in establishment of a national fingerprint base.

Description

technical field [0001] The invention belongs to the field of material chemistry. Background technique [0002] Fingerprints can be used as an important means of personal identification. In addition, fingerprint identification plays an increasingly prominent role in investigating and solving crimes and combating criminals. It has become the most direct, fastest and most convenient way for investigative departments around the world to find and identify criminals. 1-4 . Fingerprint information plays an irreplaceable role in the identity identification of criminal investigations. Many countries in the world have established complete fingerprint databases. The fingerprint databases in my country are incomplete and the quality of fingerprints is not high, which has become one of the main obstacles to fingerprint crimes. . [0003] At present, fingerprint collectors mainly include living optical, capacitive and pressure sensitive. For technical indicators such as resolution and a...

Claims

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Application Information

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IPC IPC(8): G06K9/00
CPCG06V40/13
Inventor 宋启军丁佩许春华赵媛
Owner JIANGNAN UNIV
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