Device and method for obtaining a plain image of multiple fingerprints

摘要

A device for providing a plain image signal indicative of a plain image of surface characteristics of more than one finger on a hand includes an plain platen prism having a flat, rectangular shaped finger receiving surface having a platen aspect ratio greater than 1.33:1. An illumination source internally illuminates the finger receiving surface such that light internally illuminating a bare portion of the finger receiving surface is internally reflected from the finger receiving surface and light internally illuminating a contacted portion of the finger receiving surface in contact with the fingers is not internally reflected from the finger receiving surface. The internally reflected light forms a reflection image of the surface characteristics of the fingers. Optical elements direct the reflection image to a camera. The camera, which has a rectangular receiving surface with an aspect ratio of approximately 1.33:1, receives the reflection image and provides the plain image signal in response. The directing optical elements include refracting elements structured and arranged to change the aspect ratio of the reflection image to approximately equal the camera receiving surface aspect ratio.