Optical system of fingerprint image capture apparatus

• US 20040028262A1
• Filed: 08/09/2002
• Published: 02/12/2004
• Est. Priority Date: 08/09/2002
• Status: Abandoned Application

• Current Assignee: Leadtek Research, Inc.
• Original Assignee: Leadtek Research, Inc.
• Inventors: Lin, Kuo-Liang, Chien, Chiao-Hsin
• Application Number:
  US10/064,717
• Publication Number:
  US 20040028262A1
• Time in Patent Office: Days
• US Class Current: 382/127
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

An optical system of fingerprint image capture apparatus comprises an optical platen substantially in a flat shape, a source light, and an image sensor. The optical platen includes a generally planar contact face having a dull rough surface against which a finger is placed, and a generally planar viewing face at the side of which is placed the image sensor and the light source. An incident light from the light source that strikes a region of the contact surface touched by a fingerprint ridge is scattered and passes through the viewing face to be substantially captured by the image sensor. An incident light that strikes a region of the contact face corresponding to a fingerprint valley is scattered and further passes out of the optical prism by refraction. The fingerprint ridge thereby appears as brighter regions and the fingerprint valley as darker regions.

Claims

1. An optical platen used within an optical system of a fingerprint image capture apparatus, the optical platen comprising a contact face provided with a dull rough surface against which a finger is placed to pickup a fingerprint image, and an opposite viewing face exhibiting a smooth surface through which a fingerprint image light, resulted from a scattering of an incident light striking the contact face, emerges out of the optical platen to be captured by an image sensor.

2. The optical platen of claim 1, wherein the material of the optical platen includes transparent glass or plastics.

3. The optical platen of claim 1, wherein the contact face has an adequate roughness to respectively enable light scattering at the region of the contact face touched by a fingerprint ridge, and light scattering and refraction at the region of the contact face corresponding to a fingerprint valley, thereby the fingerprint ridge appears as a brighter region and the fingerprint valleys as a darker region on a formed fingerprint image.

4. The optical platen of claim 1, wherein the contact face and the viewing face are generally planar.

5. The optical platen of claim 1, wherein the optical platen has a general shape that is substantially flat.

6. An optical system for fingerprint image capture, the optical system being installed within an electronic device that includes an image capture window, the optical system comprising:

an optical platen, including a contact face provided with a dull rough surface against which a finger is placed to pickup a fingerprint image, and an opposite viewing face exhibiting a smooth surface, wherein the optical platen is mounted to the image capture window with the contact face outwardly oriented and the viewing face inwardly oriented;

a light source, placed proximate to the viewing face, and emitting an incident light that passes into the optical platen and strikes the contact face; and

an image sensor, placed proximate to the viewing face of the optical platen to receive an emerging image light resulted from a scattering of the incident light on the contact face against which the finger is placed.

7. The optical system of claim 6, wherein the material of the optical platen is made of transparent glass or plastics.

8. The optical system of claim 6, wherein the contact face has an adequate roughness to respectively enable light scattering at the region of the contact face touched by a fingerprint ridge, and light scattering and refraction at the region of the contact face corresponding to a fingerprint valley, thereby the fingerprint ridge appears as a brighter region and the fingerprint valleys as a darker region on a fingerprint image formed via the image sensor.

9. The optical system of claim 6, wherein the contact face and the viewing face are generally planar.

10. The optical system of claim 6, wherein the optical platen has a general shape that is substantially flat.

11. The optical system of claim 6, wherein the optical platen is further movably mounted to the image capture window in a manner to be capable of covering and uncovering the image capture window, thereby the optical system is enabled to be configured to a fingerprint image capture configuration when the optical platen covers the image capture window, and to a farther environment image capture configuration as a video camera optical system when the optical platen uncovers the image capture window.

12. The optical system of claim 6, wherein the light source includes light-emitting diodes (LED).

13. The optical system of claim 6, wherein the image sensor includes a charge coupled device (CDD), a complementary metal oxide semiconductor (CMOS) device, or a contact image sensor (CIS).

14. An application of an optical system according to claim 11, wherein the optical system is installed within a mobile phone to achieve an internal image capture apparatus that is enabled to be configured to pickup either a fingerprint image or a farther environment image.