Compact fingerprint recognizing apparatus illuminated with electroluminescent device

• US 5,781,651 A
• Filed: 04/15/1996
• Issued: 07/14/1998
• Est. Priority Date: 04/15/1996
• Status: Expired due to Fees

• Current Assignee: Aetex Biometric Corporation
• Original Assignee: Aetex Biometric Corporation
• Inventors: Shew, Paul-Waie, Hsiao, Pei-Yung
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Werner, Brian P.
• Application Number:
  US08/632,608
• Time in Patent Office: 820 Days
• Field of Search: 382/127, 382/126, 382/125, 382/124, 382/116, 356/71, 396/15, 427/1, 209/585, 359/439, 359/831, 70/277, 257/81, 340/825.34
• US Class Current: 382/127
• CPC Class Codes: G06V 40/13 Sensors therefor
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

A fingerprint recognizing apparatus includes: a prism, an electroluminescent device secured or adhered on an incident surface of the prism for emitting a uniform light towards a finger-laying surface of the prism with the light beam reflected at the valleys of the fingerprint, a photosensor selected from a charge-coupled-device (CCD) sensing camera for picking up the image as reflected from the prism for converting the image signal to be a voltage signal, and an image processing and recognizing circuit for processing the voltage signal for fingerprint identification, wherein the energizing of the ELD is synchronized with the image processing and recognizing for a reliable fingerprint recognization.

Claims

1. A fingerprint recognizing apparatus comprising:

a polygonal prism (1) having a light-reflective side for laying a finger to be detected thereon, a light-incoming side disposed at a first side of said light-reflective side for enterring an incident light through said light-incoming side, and a light-outgoing side disposed at a second side of said light-reflective side for projecting light as reflected from said light-reflective side outwardly through said light-outgoing side;

an electroluminescent device (ELD,2) formed as a strip and secured on said light-incoming side of said prism (1) for emitting light enterring into said prism (1) through said light-incoming side of said prism (1) and projecting the light towards a finger surface of said finger laid on said light-reflective side of said prism (1) for reflecting a fingerprint image from said finger;

an energizing circuit (3) electrically connected to said ELD (2) and operatively powering and driving said electroluminescent device (2) for illumination thereof for emitting light projecting into said prism (1) and said finger to be detected;

an image sensor (4) facing said light-outgoing side of said prism (1) for picking up an image signal of said fingerprint image as reflected from said light-reflective side of said prism (1) and converting the image signal to a voltage signal; and

an image processing and recognizing circuit (5) electrically connected to said image sensor (4) for receiving said voltage signal from said image sensor (4) and operatively processing and recognizing said voltage signal for an identification of the fingerprint as sensed from the finger to be detected;

said ELD (2) including at least an electroluminescent emission layer (21) sandwiched in between a transparent conductive layer (22) and a substrate conductive layer (23) having an insulative bottom layer coated on a bottom of said substrate conductive layer, said transparent conductive layer (22) adhered on said light-incoming side of said prism (1), and said two conductive layers (22,23) electrically connected to said energizing circuit (3) for driving said electroluminescent device (2) for illumination thereof;

said energizing circuit (3) connected with a brightness adjusting circuit (7), said brightness adjusting circuit (7) operatively adjusting a voltage and frequency value of said energizing circuit (3) for adjusting a brightness of said ELD (2) as deteriorated with the lapse of time, said ELD (2) having two conductive layers electrically connected with the brightness adjusting circuit (7);

said energizing circuit (3) including a transistor (Q1) having a base electrically connected to a micro-controller (51) of an image processing and recognizing circuit (5) for receiving an input signal from the micro-controller (51), a collector of the transistor (Q1) electrically connected to a primary winding of a transformer (T1) operatively self-exciting an input voltage (Vin) to increase an output energizing voltage to drive the ELD (2), and an emitter of the transistor (Q1) grounded; and

the transformer (T1) having a secondary winding coupled to the primary winding of the transformer (T1) and having two opposite ends of the secondary winding of the transformer (T1) electrically connected to two conductive layers (22,

     23) of the ELD (2) for outputing the energizing voltage to the ELD (2); and

said micro-controller operatively adjusting a frequency of a sguarewave input to said transistor (Q1) for adjusting a frequency of an output current from said transformer (T1) for adjusting a brightness of said ELD (2); and

said brightness adjusting circuit (7) including a variable resistor having variable resistance (Ra) and a fixed-resistance resistor (Rc) connected in series across two ends of the secondary winding of the transformer (T1) of the energizing circuit (3), said two resistors (Ra, Rc) parallelly connected to two said conductive layers (22,

     23) disposed on two sides of said electroluminescent emission layer (21) of said ELD (2), whereby upon varying of said variable resistor (Ra) to change an output voltage of said energizing circuit (3), a brightness of said ELD (2) as driven by said energizing circuit (3) is adjusted.