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1. (WO1998052135) CAPACITIVE FINGERPRINT SENSOR WITH ADJUSTABLE GAIN
Latest bibliographic data on file with the International Bureau   

Pub. No.: WO/1998/052135 International Application No.: PCT/US1998/009597
Publication Date: 19.11.1998 International Filing Date: 12.05.1998
Chapter 2 Demand Filed: 10.11.1998
IPC:
G06F 3/033 (2006.01) ,G06K 9/00 (2006.01) ,G07C 9/00 (2006.01)
G PHYSICS
06
COMPUTING; CALCULATING; COUNTING
F
ELECTRIC DIGITAL DATA PROCESSING
3
Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
01
Input arrangements or combined input and output arrangements for interaction between user and computer
03
Arrangements for converting the position or the displacement of a member into a coded form
033
Pointing devices displaced or positioned by the user; Accessories therefor
G PHYSICS
06
COMPUTING; CALCULATING; COUNTING
K
RECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
9
Methods or arrangements for reading or recognising printed or written characters or for recognising patterns, e.g. fingerprints
G PHYSICS
07
CHECKING-DEVICES
C
TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS, OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
9
Individual entry or exit registers
Applicants: VERIDICOM, INC.[US/US]; 2338 Walsh Avenue Santa Clara, CA 95051, US
Inventors: DICKINSON, Alexander, G.; US
MCPHERSON, Ross; US
MENDIS, Sunetra; US
ROSS, Paul, C.; US
Agent: ELAINE, H., Lo.; Skjerven, Morrill, MacPherson, Franklin & Friel, L LP Suite 700 25 Metro Drive San Jose, CA 95110, US
Priority Data:
08/855,23013.05.1997US
Title (EN) CAPACITIVE FINGERPRINT SENSOR WITH ADJUSTABLE GAIN
(FR) CAPTEUR DACTYLOSCOPIQUE CAPACITIF A GAIN REGLABLE
Abstract:
(EN) The present invention relates to a fingerprint sensing device comprising a planar array of closely-spaced capacitive sense elements (120, Fig. 1). When a finger (510) is placed in close proximity to the sensing device, the capacitive sense elements measure a capacitance (508) between the finger (510) and a single capacitor plate (500) in each sense element. This is accomplished by precharging each capacitor plate, and then using a known current source (522) to remove a fixed amount of charge from each capacitor plate (500). The measured capacitance varies as a function of the distance between the capacitor plate and the finger surface (200, Fig. 2). Thus, a capacitance measurement allows the distance between the capacitor plate and the finger surface to be determined (Fig. 3). Distance measurements across the array of sense elements are combined to produce a representation of the pattern of ridges on the finger surface which comprise a fingerprint. After a fingerprint is acquired, the quality of the fingerprint is evaluated, and if necessary, a gain parameter for the sense elements is iteratively adjusted until a satisfactory fingerprint is acquired.
(FR) La présente invention concerne un dispositif de capteur dactyloscopique comprenant un réseau plan d'éléments capteurs capacitifs proches les uns des autres. Lorsqu'on place un doigt à proximité du dispositif de capteur, les éléments capteurs capacitifs mesurent la capacité entre le doigt et une seule plaque de capaciteur dans chaque élément capteur. On effectue ce processus en préchargeant chaque plaque de capaciteur et en utilisant ensuite une source de courant connue pour enlever une quantité fixe de charge de chaque plaque de capaciteur. La capacité mesurée varie en fonction de la distance entre la plaque de capaciteur et la surface du doigt. En mesurant la capacité, il est possible de déterminer la distance entre la plaque de capaciteur et la surface du doigt. On combine les mesures de distance sur tout le réseau d'éléments capteurs afin d'obtenir une représentation du motif des lignes de la surface du doigt qui comprennent une empreinte digitale. Après qu'on a acquis une empreinte digitale, on évalue la qualité de l'empreinte digitale et, si nécessaire, on règle à plusieurs reprises le paramètre de gain des éléments capteurs jusqu'à ce qu'une empreinte digitale satisfaisante ait été obtenue.
Designated States: AU, CN, JP, SG
European Patent Office (EPO) (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE)
Publication Language: English (EN)
Filing Language: English (EN)