发明名称 |
Capacitive fingerprint sensor with adjustable gain |
摘要 |
The present invention relates to a fingerprint sensing device comprising a planar array of closely-spaced capacitive sense elements. When a finger is placed in close proximity to the sensing device, the capacitive sense elements measure a capacitance between the finger and a single capacitor plate in each sense element. This is accomplished by precharging each capacitor plate, and then using a known current source to remove a fixed amount of charge from each capacitor plate. The measured capacitance varies as a function of the distance between the capacitor plate and the finger surface. Thus, a capacitance measurement allows the distance between the capacitor plate and the finger surface to be determined. 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.
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申请公布号 |
US6049620(A) |
申请公布日期 |
2000.04.11 |
申请号 |
US19970855230 |
申请日期 |
1997.05.13 |
申请人 |
VERIDICOM, INC. |
发明人 |
DICKINSON, ALEXANDER G.;MCPHERSON, ROSS;MENDIS, SUNETRA;ROSS, PAUL C. |
分类号 |
G01B7/00;A61B5/117;G01B7/004;G01B7/28;G01B7/34;G01R27/26;G06F3/033;G06F3/041;G06F3/044;G06K9/00;G06T1/00;G07C9/00;(IPC1-7):G06K9/28;G06K9/36 |
主分类号 |
G01B7/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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