EP0042490A2
Expired / Lapsed
EP
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Signature verification apparatus measuring acceleration capacitively
Assignee: International Business Machines Corp
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Filing: 1981-05-15
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Granted: —
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Expires: 2001-05-15
Abstract
Abstract An apparatus for determining pen acceleration for use in a signature verification system has, mounted in a pen (2), capacitive transducer means (Tx Ty) having floating active elements (6) which change capacitance by an amount which is proportional to pen acceleration. A Blumlein bridge circuit (in 32) is utilized to measure changes in the capacitance of the transducer means, and the output of the bridge is amplified and demodulated to result in a signal which is proportional to acceleration.
Inventors
- 👤 Brian John Elliott
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 23:44
CPC Classifications
G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/125; G06; G06V; G06V10/00; G06V10/10; G06V10/12; G06V40/00; G06V40/30; G07; G07C; G07C9/00; G07C9/30; G07C9/32; G07C9/35
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
132 words
Signature verification apparatus including a pen (2) equipped with an acceleration measuring capacitive transducer (T y or T x but not the conventional T ) connected by cables (34) to verification logic (36) external to the pen, characterized in that (a) the capacitive transducer (T y or T x ) is relatively rigidly mounted in the pen and incorporates a movable member (12) resiliently mounted relative to the rest of the transducer (8), but otherwise isolated from the pen, to have a degree of freedom of capacity changing movement normal to the axis of the pen; (b) the cables couple the transducer into one arm (CB) of a Blumlien bridge circuit (Fig. 3); and (c) the output (B) of the bridge circuit, amplified and demodulated, provides the input to the verification logic.
Claim 2
Dependent Claim
132 words
Signature verification apparatus including a pen (2) equipped with an acceleration measuring capacitive transducer (T y or T x but not the conventional T ) connected by cables (34) to verification logic (36) external to the pen, characterized in that (a) the capacitive transducer (T y or T x ) is relatively rigidly mounted in the pen and incorporates a movable member (12) resiliently mounted relative to the rest of the transducer (8), but otherwise isolated from the pen, to have a degree of freedom of capacity changing movement normal to the axis of the pen; (b) the cables couple the transducer into one arm (CB) of a Blumlien bridge circuit (Fig. 3); and (c) the output (B) of the bridge circuit, amplified and demodulated, provides the input to the verification logic.
Claim 3
Dependent Claim
54 words
Apparatus as claimed in claim 1 including a second such transducer (T x or T y ) having its degree of freedom of movement normal to that of the first recited transducer (T y or T x ) and, optionally, a conventional third transducer (T z ) connected in common to the verification logic.
Claim 4
Dependent Claim
101 words
Apparatus as claimed in claim 1 or claim 2 wherein the first (and, if present, the second) transducer comprises a pair of spaced-apart parallel plates, (8, 6) each of which has a charge storing surface, a first of said plates (8) being fixed to said pen, and the second of said plates (6) being supported by or being part of a compliant arm having a mass (16) thereon, the mounting being such that the second plate is displaced upon pen acceleration by a distance which is proportional to the component of such acceleration in the direction perpendicular to said plate surfaces.
References Cited (Backward Citations)
No citation records indexed.
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