Imaging module for biometrics authentication, biometrics authentication apparatus and prism

Abstract

An imaging module for biometrics authentication comprises: a light source irradiating a living body with light capable of passing through the living body; a prism having an incidence surface including an incidence area for taking in light emerging from the living body, two or more reflecting surfaces for reflecting the light taken in through the incidence area, and an outlet surface for outputting the light reflected by the reflecting surfaces; and a camera module including a lens for focusing the light emerging from the outlet surface of the prism and an image pickup device for converting the light focused thereon by the lens into an electric signal and outputting the electric signal.

1 . A biometrics authentication apparatus comprising:
 a light source irradiating a living body with light capable of passing through the living body;   a prism wherein the light capable of passing through the living body to an incidence area included in an incidence surface of the prism, reflects two or more times inside the prism, output from an outlet surface of the prism and the incidence area works as a reflecting surface for the reflection of the light capable of passing through the living body;   a camera module including a lens for focusing the light emerging from the outlet surface of the prism and an image pickup device for converting the light focused thereon by the lens into an electric signal and outputting the electric signal; and   a housing which places the prism and the camera module at prescribed positions.   
     
     
         2 . The biometrics authentication apparatus according to  claim 1 , further comprising a finger guide to be used for placing a finger as the living body at a prescribed position. 
     
     
         3 . The biometrics authentication apparatus according to  claim 2 , wherein the finger guide has an irradiation window for the irradiation of the finger with the light emitted by the light source. 
     
     
         4 . The biometrics authentication apparatus according to  claim 1 , wherein a light through hole for letting through the light emerging from the outlet surface of the prism is formed through the housing. 
     
     
         5 . The biometrics authentication apparatus according to  claim 4 , wherein the diameter of the light through hole of the housing is set so that a sufficient amount of light necessary for the imaging by the camera module passes through the light through hole. 
     
     
         6 . The biometrics authentication apparatus according to  claim 1 , wherein the housing is formed of material absorbing light from near-ultraviolet light to near-infrared light. 
     
     
         7 . The biometrics authentication apparatus according to  claim 1 , wherein at least a surface of the housing facing the prism is coated with paint absorbing light from near-ultraviolet light to near-infrared light so that the light emerging from the outlet surface of the prism will not be reflected by the housing to reenter the prism as stray light. 
     
     
         8 . The biometrics authentication apparatus according to  claim 1 , further comprising:
 a recognition unit which recognizes a blood vessel pattern of the living body by analyzing the electric signal output by the image pickup device;   a storage unit which has previously stored blood vessel patterns of living bodies; and   an authentication unit which executes personal authentication by comparing the blood vessel pattern recognized by the recognition unit with the blood vessel patterns prestored in the storage unit.   
     
     
         9 . The biometrics authentication apparatus according to  claim 1 , wherein the housing has an attachment part to which the camera module is attached and fixed at a position corresponding to the outlet surface of the prism; and
 the light emerging from the outlet surface of the prism is focused on the image pickup device of the camera module attached to the housing.   
     
     
         10 . The biometrics authentication apparatus according to  claim 9 , wherein the attachment part of the housing is a concavity which engages with a lens tube part containing the lens of the camera module. 
     
     
         11 . The biometrics authentication apparatus according to  claim 1 , wherein the light source is placed so that the light is emitted from the light source in the direction of a normal to the incidence surface of the prism. 
     
     
         12 . The biometrics authentication apparatus according to  claim 11 , wherein the light source is placed alongside a surface of the prism other than the incidence surface, the reflecting surfaces or the outlet surface. 
     
     
         13 . The biometrics authentication apparatus according to  claim 11 , wherein a field angle of the light source is set at 45 degrees or less. 
     
     
         14 . The biometrics authentication apparatus according to  claim 11 , wherein the light source includes an LED (Light Emitting Diode) and a condensing lens.