Global Patent Index - EP 1000362 A1

EP 1000362 A1 2000-05-17 - METHOD FOR DETERMINING VERY LOW CAPACITIES AND SENSOR DESIGNED THEREFOR

Title (en)

METHOD FOR DETERMINING VERY LOW CAPACITIES AND SENSOR DESIGNED THEREFOR

Title (de)

VERFAHREN ZUR BESTIMMUNG SEHR KLEINER KAPAZITÄTEN UND DAMIT KONZIPIERTER SENSOR

Title (fr)

PROCEDE POUR DETERMINER DE TRES FAIBLES CAPACITES ET DETECTEUR CON U A CET EFFET

Publication

EP 1000362 A1 (DE)

Application

EP 98945041 A

Priority

  • DE 9802078 W
  • DE 19733865 A

Abstract (en)

[origin: WO9908121A1] A low capacity capacitor is charged and discharged several times onto a measuring capacitor with a substantially higher capacity and the voltage or charge thereof is measured directly, thereby enabling a low capacity or variation in capacity to be determined with a high degree of precision as the result of measurement by a sensor. A fingerprint sensor with an array of metal surfaces (4) underneath a contact area for a finger tip can be made without any moveable parts, whereby transistors are provided as switches (S), in addition to measuring capacitors (1) and comparators (2). A given electric potential is applied to the metal surfaces. When a finger tip is placed on the metal surfaces they become charged to varying degrees according to structure of the surface of the skin. The charges are carried to the measuring capacitors assigned thereto. The charge states of the measuring capacitors are determined separately according to the way in which the matrix memory is read.

IPC 1-7 (main, further and additional classification)

G01R 27/26; G06K 9/00

IPC 8 full level (invention and additional information)

G01L 9/12 (2006.01); G01B 7/28 (2006.01); G01R 27/26 (2006.01); G06K 9/00 (2006.01)

CPC (invention and additional information)

G01R 27/2605 (2013.01); G06K 9/0002 (2013.01)

Citation (search report)

See references of WO 9908121A1

Designated contracting state (EPC)

AT CH DE ES FR GB IT LI

EPO simple patent family

WO 9908121 A1 19990218; BR 9811837 A 20000815; CN 1266494 A 20000913; EP 1000362 A1 20000517; JP 2001512836 A 20010828; MX PA00001276 A 20020327

INPADOC legal status


2002-08-14 [18D] DEEMED TO BE WITHDRAWN

- Effective date: 20020201

2000-05-17 [17P] REQUEST FOR EXAMINATION FILED

- Effective date: 20000121

2000-05-17 [AK] DESIGNATED CONTRACTING STATES:

- Kind Code of Ref Document: A1

- Designated State(s): AT CH DE ES FR GB IT LI