US4394773A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fingerprint sensor
Assignee: Siemens Corp
•
Filing: 1980-07-21
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Granted: 1983-07-19
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Expires: 2000-07-21
Abstract
Abstract The fingerprint sensor transforms the fingerprint information of a finger under investigation into an electric output signal. The sensor incorporates a contact device or sensor plate of a piezoelectric material. This sensor plate has a contact surface. The finger exercises a contact pressure thereon and changes thereby the distribution of electric charges on the contact surface. The new charge distribution is in accordance with the fingerprint pattern of the finger. The sensor further incorporates an electric device which provides the electric output signal in accordance with the distribution of charges.
Inventors
- 👤 Hartwig Ruell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:58
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/117; A61B5/1171; A61B5/1172; G; G06; G06V; G06V40/00; G06V40/10; G06V40/12; G06V40/13; G06V40/1306; Y; Y10; Y10S; Y10S310/00; Y10S310/80
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
92 words
A fingerprint sensor for transforming the fingerprint information of a finger under investigation into an electric output signal, comprising in combination: (a) a contact device containing a piezoelectric material, said contact device having surfaces including a contact surface for exercising a contact pressure thereon by means of said finger, thereby changing the density of electric charges on said surfaces according to the fingerprint pattern of said finger; and (b) electrical means for providing the electric output signal in accordance with the distribution of said charges on at least one of said surfaces.
Claim 2
Dependent Claim
92 words
A fingerprint sensor for transforming the fingerprint information of a finger under investigation into an electric output signal, comprising in combination: (a) a contact device containing a piezoelectric material, said contact device having surfaces including a contact surface for exercising a contact pressure thereon by means of said finger, thereby changing the density of electric charges on said surfaces according to the fingerprint pattern of said finger; and (b) electrical means for providing the electric output signal in accordance with the distribution of said charges on at least one of said surfaces.
Claim 3
Dependent Claim
15 words
The fingerprint sensor according to claim 1, wherein said contact device contains a piezoelectric polymer.
Claim 4
Dependent Claim
14 words
The fingerprint sensor according to claim 2, wherein said piezoelectric polymer is polyvinylidene fluoride.
Claim 5
Dependent Claim
55 words
The fingerprint sensor according to claim 2, wherein the contact device is a layer of a piezoelectric polymer having a first and a second surface, the first surface having said contact surface for exercising a contact pressure thereon and the second surface being scanned by said electrical means for determining the distribution of electric charges.
Claim 6
Dependent Claim
58 words
The fingerprint sensor according to claim 2, comprising, (a) a plate of a piezoelectric polymer having electric dipoles with their dipole axes arranged normally to the plane of said plate; (b) an array of electric sensor elements attached to said plate; and (c) means for determining the charge on said sensor elements to form said electric output signal.
Claim 7
Dependent Claim
17 words
The fingerprint sensor according to claim 5, wherein said sensor elements are arranged as a sensor matrix.
Claim 8
Dependent Claim
24 words
The fingerprint sensor according to claim 5, wherein said electric sensor elements are arranged in a structure similar to the structure of a fingerprint.
Claim 9
Dependent Claim
46 words
The fingerprint sensor according to claim 1, wherein said contact device is a plate of a piezoelectric material, said plate having a first surface for exercising said contact pressure thereon, and a second surface, whereby said first surface is structured and contains a multitude of pixels.
Claim 10
Dependent Claim
15 words
The fingerprint sensor according to claim 8, wherein said pixels are provided with small electrodes.
Claim 11
Dependent Claim
16 words
The fingerprint sensor according to claim 8, wherein an insulating material is provided between adjacent pixels.
Claim 12
Dependent Claim
17 words
The fingerprint sensor according to claim 1, further comprising a thin protective coating on said contact surface.
Claim 13
Dependent Claim
26 words
The fingerprint sensor according to claim 1, further comprising a plurality of metal electrodes on said contact surface for deriving the electric charges from said surface.
Claim 14
Dependent Claim
15 words
The fingerprint sensor according to claim 1, wherein said contact device contains a piezoelectric ceramic.
Claim 15
Dependent Claim
17 words
The fingerprint sensor according to claim 13, wherein said piezoelectric ceramic is a lead zirconate titanate ceramic.
Claim 16
Dependent Claim
13 words
The fingerprint sensor according to claim 14, wherein said ceramic contains barium titanate.
Claim 17
Dependent Claim
13 words
The fingerprint sensor according to claim 14, wherein said ceramic contains triglycine sulfate.
Claim 18
Dependent Claim
19 words
The fingerprint sensor according to claim 12, wherein said electrodes are separated from each other by an insulating material.
Claim 19
Dependent Claim
22 words
The fingerprint sensor according to claim 1, wherein said electrical means comprise a CCD scanner for determining the distribution of said charges.
Claim 20
Dependent Claim
44 words
The fingerprint sensor according to claim 1, further comprising light emitters and light receivers distributed on the rim of said contact device, said light receivers receiving light from said emitters and delivering an output signal when the finger under investigation approaches said contact surface.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-18 | 1987-01-17 | 1987-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-18 | 1991-01-17 | 1991-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-18 | 1995-01-17 | 1995-07-19 | $7700.00 | Window Closed / Lapsed |