EP 1000362 A1 20000517 - 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
Application
Priority
- DE 9802078 W 19980723
- DE 19733865 A 19970805
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
IPC 8 full level
G01B 7/28 (2006.01); G01L 9/12 (2006.01); G01R 27/26 (2006.01); G06K 9/00 (2006.01)
CPC (source: EP)
G01R 27/2605 (2013.01); G06V 40/1306 (2022.01)
Citation (search report)
See references of WO 9908121A1
Designated contracting state (EPC)
AT CH DE ES FR GB IT LI
DOCDB simple family (publication)
WO 9908121 A1 19990218; BR 9811837 A 20000815; CN 1266494 A 20000913; EP 1000362 A1 20000517; JP 2001512836 A 20010828; KR 20010022575 A 20010326; MX PA00001276 A 20020327
DOCDB simple family (application)
DE 9802078 W 19980723; BR 9811837 A 19980723; CN 98808036 A 19980723; EP 98945041 A 19980723; JP 2000506535 A 19980723; KR 20007001166 A 20000203; MX PA00001276 A 19980723