Siemens Corporation

Hartwig Ruell

Ming-Yee Chiu

Wolfgang H Feix

Edward J Devinney, Jr

The fingerprint sensor derives an electric output signal in accordance with the topographic relief of the finger under investigation. The sensor incorporates a contact body which is formed at least in part by a light-transparent elastic material. The contact body, preferably a flat sensor plate made of said elastic material and attached to a flat supporting plate, has a light receiving surface and a contact surface for receiving a contact pressure by the finger. Before an investigation process is started, the contact surface is smooth. By pressing the finger against the contact surface, the contact surface will attain a shape conforming to the fingerprint pattern of the finger. The sensor also incorporates a light source, a photodetector and an optical system. The light source obliquely passes light to the contact surface which reflects a light beam modulated in accordance with the fingerprint. The optical system passes the reflected light beam to the light sensitive area of the photodetector. In the optical path between finger and photodetector is included a light stop for blocking reflected light which does not contain fingerprint information.

Fingerprint sensing device for deriving an electric signal

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.

Fingerprint sensor

An automobile identification system and a method for producing it are disclosed. The system utilizes a conventional license plate with alpha-numeric characters conveying identifying information perceptible by the unaided eye in combination with a hologram embodying encoded identifying information which cannot be decoded by the unaided eye.

Automobile identification system

The fingerprint transducer contains a sensing member having a sensing surface for receiving a fingerprint. The sensing member is made of a material which has a transition or softening temperature that is higher than ambient temperature and close to the temperature of the finger. Particularly, the softening temperature is chosen such that the material of the sensing member will start to melt on the surface when the finger is pressed against the sensing surface. The sensing surface has a surface relief of random roughness. In other words, the sensing surface has variations in elevation which do not show a specific pattern. The method for analyzing fingerprints comprises the steps of generating a surface relief of random space on a sensing surface of a sensing member, generating the fingerprint on the sensing surface by pressing a finger thereto, and optically reading the fingerprint from the sensing surface.

Transducer for fingerprints and apparatus for analyzing fingerprints

There is disclosed an input sensor unit for a fingerprint verification system. A sensor plate facing a fingerbed is composed of a transparent polymer which is elastic so as to form a latent topographic relief of a finger pattern. A sensing light beam is coupled into the sensor plate through one edge surface. An output light beam emitted through a planar surface of the sensor plate at the opposite side of the fingerbed is directed onto the light sensitive area of an electro-optical sensing array. In the optical path of the output light beam there is arranged an optical lens for focusing the output light beam onto the light sensitive area and an optical filter for masking out the direct light of the output light beam.

Input sensor unit for a fingerprint identification system

The fingerprint transducer contains a sensing member having a sensing surface for receiving a fingerprint, a device for generating an electrostatic charge on the sensing surface and a heating device for heating the sensing surface up to a temperature which is approximately the softening temperature of the sensing member. The method for enhancing fingerprints comprises the steps of generating the fingerprint on the sensing surface, electrostatically charging the sensing surface, heating the sensing surface up to the softening temperature, and thereafter cooling down the sensing member.

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Mt. Laurel, NJ, United States of America

Hartwig Ruell