초록 ▼

A finger pressed against a platen provides a fingerprint object which is scanned by an interrogating beam of collimated light in the form of a slit and that is linearly displaced across the platen. As the slit-beam scans across the back surface of the platen, the reflected light beam is modulated. T

A finger pressed against a platen provides a fingerprint object which is scanned by an interrogating beam of collimated light in the form of a slit and that is linearly displaced across the platen. As the slit-beam scans across the back surface of the platen, the reflected light beam is modulated. The modulated beam is imaged onto a linear array of photodiodes to provide a series of output signals indicative of modulation information. The outputs of the diodes are serially interrogated at each of successive scan positions to provide a set of signals containing fingerprint information. The platen has a transparent glass base. A layer of transparent, compressible, resilient epoxy is on the back of the glass base. The epoxy layer has a flat back surface. A thin silver reflecting layer on the back surface of the epoxy provides a flat mirrored surface to reflect the light beam. A further epoxy layer on top of the silver provides mechanical filtering. A lacquer layer at the back protects the platen from wear. When a finger is applied to the back surface, the ridges of the finger distort the underlying layers sufficiently so that the reflected light at the ridge zones is scattered while the reflected light at the valley zones is collimated. This difference in scatter is transformed by an imaging lens to a difference in intensity at the diode array.

대표청구항 ▼

In an optical finger image processing apparatus, the improvement comprising: a platen having a front surface adapted to receive an interrogating light beam and a back surface adapted to receive a finger thereon, said platen having a transparent substrate, a first deformable, resilient transparent la

In an optical finger image processing apparatus, the improvement comprising: a platen having a front surface adapted to receive an interrogating light beam and a back surface adapted to receive a finger thereon, said platen having a transparent substrate, a first deformable, resilient transparent layer on the back surface of said substrate, said layer having sufficient thickness and being sufficiently deformable so that forces transmitted by the ridges of a finger pressed against the back surface on said platen will readily cause said layer to deform in the zones directly under the ridges of the applied finger, and a reflective layer on the back surface of said first deformable, resilient layer, said reflective layer being sufficiently thin so that forces transmitted by the ridges of a finger pressed against the back surface of said platen will be readily transmitted to said deformable resilient layer.