WO2007059694A1

WO2007059694A1 - Large area fingerprint recognition device

Info

Publication number: WO2007059694A1
Application number: PCT/CN2006/003051
Authority: WO
Inventors: Quanzhong Che
Original assignee: Zksoftware Inc.
Priority date: 2005-11-24
Filing date: 2006-11-14
Publication date: 2007-05-31

Abstract

A large area fingerprint recognition device comprising a light source (5), a prism (1), a lens (2) and a photoelectric detector (3). The cross-section of the prism (1) is not an isosceles triangle and the apex angle thereof is more than 90°. The light source (5) is disposed at one side of the prism (1), and the lens (2) and the photoelectric detector (3) are disposed at the other side of the prism (1). Alternatively, a first mirror (8) is placed at the short side of the prism (1), a second mirror (9) is placed at the right bottom of the first mirror (8), the angle between these mirrors is more than 90°, and the light source (5), the lens (2) and the photoelectric detector (3) are placed at the long side of the prism (1).

Description

Large format fingerprint collector

The invention relates to a fingerprint image collecting device, in particular to a large-format fingerprint collector. Background technique

At present, the prism section of the fingerprint collector for collecting fingerprints is a right-angled isosceles triangle, with the bottom surface of the triangle as the fingerprint collection surface, the light source on one side is the incident surface, and the other side is equipped with the lens and the photoelectric surface. The detector is the exit surface. Due to the height of the right triangle and the overall thickness of the collector, the image acquisition surface is usually small, the fingerprint image for comparison recognition is small, and the full fingerprint of the large finger cannot be collected. In many cases, the fingerprint recognition is required. Not available in precision equipment. For example, in the field of identification such as public security, customs, and ID cards, it is necessary to collect large-scale fingerprint images. Therefore, the existing fingerprint collector equipped with a right-angled triangular prism is large and cumbersome, is inconvenient to be used, and has a small image area for fingerprint collection, and the application field is subject to many restrictions. Summary of the invention

The technical problem to be solved by the present invention is to provide a large-format fingerprint collector, which has a small volume, a large collection surface, a large area fingerprint, and a high recognition rate.

In order to solve the above technical problems, the present invention uses the following technical solutions: A large-format fingerprint collector, including a light source, a prism, a lens, and a photodetector, the prism section is an isosceles triangle having a vertex angle greater than 90 degrees, and a prism side The oblique waist is equipped with a light source, and the other side of the prism is equipped with a lens and a photodetector on the side of the inclined waist.

Further improvement of the above technical solution is: a light source is arranged on one side of the long waist side of the prism, and a single mirror is arranged on one side of the short waist side of the prism, and an angle between the right side of the lower end of the primary mirror and the primary mirror is greater than 90 degree secondary mirror, outer side of the light source on the long waist side of the prism The lens is equipped with a photodetector on the outside of the lens.

A further improvement of the above technical solution is: the upper end of the primary mirror is inclined toward the short waist, and the right end of the secondary mirror is inclined downward.

A further improvement of the above technical solution is that the light source is composed of a light guide plate located on one side of the inclined waist surface of the prism and a light emitting diode located at the outer end of the light guide plate.

A further improvement of the above technical solution is: the illumination surface of the light guide plate on one side of the prism is a convex light guide surface, and the light guide surface has a bump width of 0.1 to 0.2 mm and a height of 0.05 to 0.1 mm. The surface is covered with a transparent homogenous film which is a corrugated surface composed of triangular ribs.

Further improvements of the above technical solution are as follows: The height of the prism is 8 to 14 mm, the width of the bottom surface is 18 to 26 mm, and the length is 24 to 36 mm.

Further improvement of the above technical solution is as follows: the angle between the long and short waist surfaces of the prism is 112.5 degrees, the angle between the long waist surface of the prism and the bottom surface is 22.5 degrees, and the angle between the short waist surface of the prism and the bottom surface is 45 degrees.

A further improvement of the above technical solution is that the bottom surface of the prism is coated with a transparent elastic resin film. A further improvement of the above technical solution is: between the lens plane and the surface of the photodetector

An angle of 5 to 8 degrees.

After adopting the above technical solution, the present invention has the following beneficial effects: By changing a right-angled isosceles triangular prism to an isosceles triangular prism with a vertex angle greater than 90 degrees, the thickness of the prism, that is, the height of the triangle can be greatly reduced; The area of the set surface is greatly increased, that is, the length of the bottom side of the triangle is increased, thereby reducing the volume and increasing the collection area. By reducing the angle of the side of the isosceles triangle, the length of the prism and the thickness of the relatively narrow prism can be greatly increased without increasing the thickness of the prism, thereby creating conditions for increasing the fingerprint image acquisition area;

In addition, by introducing a mirror and a secondary mirror to fold the optical path back, a lens is disposed below the long waist end of the prism, and a photodetector is disposed outside the lens, the margin space on the prism tip side can be fully utilized, which is advantageous for reducing The size of the whole machine does not affect the fingerprint collection surface and Fingerprint image effect; After increasing the fingerprint collection surface, it will obviously increase the recognition rate accordingly. The utility model has the advantages of large fingerprint collecting surface, small volume, light weight, low distortion rate and small distortion.

In summary, the large-format fingerprint collector of the invention has the advantages of thin prism, small volume, light weight, large collecting surface, small distortion, low distortion rate, high recognition rate, convenient assembly and reliable performance, and is most suitable for public security. Advantages of the identification field in customs, ID cards, etc. DRAWINGS

1 is a schematic structural view of a first embodiment of a large-format fingerprint collector of the present invention; FIG. 2 is a schematic structural view of a second embodiment of the large-format fingerprint collector of the present invention; FIG. 3 is a second aspect of the large-format fingerprint collector of the present invention; Schematic diagram of a transparent homogenizing film covered by the surface of the light guide plate of the embodiment;

4 is a schematic structural view of a third embodiment of the large-format fingerprint collector of the present invention. detailed description

As shown in FIG. 1, according to a first embodiment of the present invention, the large-format fingerprint collector is composed of a light source, a prism 1, a lens 2, and a photodetector 3. The angle between the long and short waist faces of the prism 1 is 112.5 degrees, the angle between the long waist surface of the prism 1 and the bottom surface is 22.5 degrees, and the angle between the short waist surface of the prism 1 and the bottom surface is 45 degrees. The prism is optically called a half-angle. The prism, designed to make the optical path ideal, the clearest and most complete image, can reduce the thickness of the prism, ensure the large area of the reflected fingerprint image, minimize the distortion rate and optimize the image quality. The prism 1 is equipped with a light source on one side of the long waist, and the lens 2 and the photodetector 3 are provided on the short side of the prism 1. The light source is composed of a light guide plate 4 located on one side of the inclined waist surface of the prism 1 and a light emitting diode 5 located at the outer end of the light guide plate 4. The light guide plate 4 is preferably a plexiglass plate, and the light source generated by the light emitting diode is red light or green light. With such a juice, the introduction of the light guide plate can make the incident light uniform and reduce the volume of the light source, and has the advantages of large light source area, small thickness, small occupied space, simple structure, small volume, light weight and low cost. The introduction is beneficial to save energy. The light guide plate 4 is located on one side of the prism, and the surface of the light guide plate is covered with a transparent uniform light film. The thickness of the uniform light film is 0.10 mm, which is more favorable for illuminating the convexity of the fingerprint, improving the sharpness and contrast of the fingerprint image, and facilitating detection. Precision. The prism 1 has a height of 8 to 14 mm, a bottom width of 18 to 26 mm, and a length of 24 to 36 mm. This design ensures a large image acquisition surface and can capture a full fingerprint image, thereby better reducing the volume and increasing the size. The advantage of fingerprint collection area. The bottom surface of the prism 1 is coated with a transparent elastic resin film 6 made of silicone resin. The transparent elastic resin film 6 can be made of silicone resin or acrylic resin, and its light transmittance and refractive index are similar to those of the glass, and will not be affected. The imaging of the prism is designed such that the surface of the resin film of the prism becomes a fingerprint collecting surface. When the incident light is irradiated onto the ridge of the fingerprint, the convex stripe is pressed by the elastic resin film, and the resin film and the convex protrusion of the finger are raised. The weave can be infiltrated, and the incident light can be well absorbed at the ridges. Because the concave strip of the fingerprint is not in contact with the resin film, it is isolated by a layer of air, and the incident light will form a complete internal reflection here, and then enter the exit surface and then be directed to the outside of the prism, thereby improving the recognition rate of the fingerprint image. , reduce the distortion rate.

The light path is: the light source generated by the light-emitting diode 5 is incident on the light guide plate 4, the light of the light guide plate 4 is transmitted through the long waist surface of the prism 1 toward the transparent elastic resin film 6, and the reflected light obtained by the transparent elastic resin film 6 is transmitted through the prism 1. The short waist surface is directed toward the lens 2, and the light transmitted through the lens 2 is projected onto the photodetector 3, thereby completing the acquisition of the fingerprint image.

2 and 3 show a second embodiment of the present invention, and the main difference from the first embodiment is: 1), the position of the light source is interchanged with the position of the lens 2 and the photodetector 3, that is, the short waist of the prism 1 The light source is provided on one side of the surface, and the lens 2 and the photodetector 3 are disposed on the long waist side of the prism 1; 2) The light guide plate 4 of the light source is located on the side of the prism, and the illumination surface is designed as a convex light guide surface and covered The transparent uniform light film 7 shown in FIG. 3 is designed to more fully illuminate the convexity of the fingerprint, improve the sharpness and contrast of the fingerprint image, and is advantageous for improving the detection precision. The light guide plate 4 has a bump width of 0.1 to 0.2 mm and a height of 0.05 0.1 mm. This design can better illuminate the fingerprint and improve the detection accuracy. The light path is: The light generated by the light-emitting diode 5 is incident on the light guide plate 4. The radiation light of the light guide plate 4 is transmitted through the short waist surface of the prism 1 toward the transparent elastic resin film 6, and the reflected light obtained by the transparent elastic resin film 6 is transmitted through the prism. The long waist surface of 1 is directed toward the lens 2, and the light transmitted through the lens 2 is projected onto the photodetector 3, thereby completing the acquisition of the fingerprint image.

As shown in FIG. 4, it is a third embodiment of the large-format fingerprint collector of the present invention, and the main difference from the first embodiment is that: the prism 1 is equipped with a light source on the long waist side, but the prism 1 has a short waist surface. The side is equipped with a mirror 8, and the right side of the lower end of the mirror 8 is provided with a secondary mirror 9 with an angle of 100-130 degrees. The prism 1 is fitted with a lens 2 at the lower end of the long waist, and the lens 2 is provided outside. The photodetector 3 is mounted, the upper end of the primary mirror 8 is inclined to the short side, and the right end of the secondary mirror 9 is inclined downward. Preferably, the mirror surface of the primary mirror 8 is at an angle of 5 to 8 degrees from the exit surface of the prism 1. This design allows for very sharp, distorted images. The angle between the lens 2 plane and the surface of the photodetector CM053 is 5 to 8 degrees, so that the fingerprint image can be corrected.

The light path is: The light source generated by the light-emitting diode 5 is incident on the light guide plate 4. The radiation light of the light guide plate 4 is directed to the bottom surface of the prism through the long waist surface of the prism 1, and the incident light of the bottom surface of the prism 1 is incident on the transparent elastic resin film. 6. The fingerprint is pressed on the surface of the transparent elastic resin film 6, and the reflected light obtained by the reflection is then directed to the primary mirror through the short waist surface of the prism 1, and the light reflected by the primary mirror 8 is reflected to the secondary mirror 9, The light reflected by the secondary mirror 9 is then projected through the lens 2 onto the photodetector 3, thereby completing the acquisition of the fingerprint image.

Claims

Claim

1. A large-format fingerprint collector comprising a light source, a prism, a lens and a photodetector, wherein: the prism cross section is an isosceles triangle with a vertex angle greater than 90 degrees, and the prism side oblique waist surface is equipped with a light source, the prism On the other side of the inclined waist side is equipped with a lens and a photodetector.

2. The large-format fingerprint collector according to claim 1, wherein: the prism has a light source on one side of the long waist surface, and a primary mirror is disposed on one side of the short waist side of the prism, and the right side of the lower end of the primary mirror is provided A secondary mirror with an angle between the mirror and the mirror is greater than 90 degrees. The light source on the long waist side of the prism is equipped with a lens, and the outside of the lens is equipped with a photodetector.

3. The large-format fingerprint concentrator according to claim 2, wherein: the upper end of the primary mirror is inclined toward the short waist, and the right end of the secondary mirror is inclined downward.

4. The large-format fingerprint collector according to claim 1 or 2, wherein the light source is composed of a light guide plate located on one side of the inclined waist surface of the prism and a light emitting diode located at an outer end of the light guide plate.

5. The large-format fingerprint collector according to claim 4, wherein the illumination surface of the light guide plate on the side of the prism is a convex light guide surface, and the bump width of the light guide surface is 0.1~ 0.2 mm, height is 0.05 to 0.1 mm, and the light guiding surface is covered with a transparent homophobic film, which is a corrugated surface composed of triangular ribs.

The large-format fingerprint collector according to claim 1 or 2, wherein the prism has a height of 8 to 14 mm, a bottom surface width of 18 to 26 mm, and a length of 24 to 36 mm.

7. The large-format fingerprint collector according to claim 1 or 2, wherein: the angle between the long and short waist surfaces of the prism is 112.5 degrees, and the angle between the long waist surface of the prism and the bottom surface is 22.5 degrees, and the short waist surface of the prism is The angle of the bottom surface is 45 degrees.

The large-format fingerprint collector according to claim 1 or 2, wherein the prism is coated with a transparent elastic resin film on the bottom surface thereof.

9. The large-format fingerprint collector according to claim 1 or 2, wherein: the lens plane has an angle of 5 to 8 degrees from the surface of the photodetector.