초록 ▼

A fingerprint reader is described. The fingerprint reader includes an illumination source that produces light and a camera. An optical window is also part of the reader. The window is positioned so that light from the illumination source passes through the optical window and then is reflected to the

A fingerprint reader is described. The fingerprint reader includes an illumination source that produces light and a camera. An optical window is also part of the reader. The window is positioned so that light from the illumination source passes through the optical window and then is reflected to the camera for imaging a person's fingerprint. A filter may be positioned on or proximate to the optical window. The filter prevents ambient light from reaching the camera. In some situations, the filter will be a dielectric mirror, a dielectric filter, a holographic mirror, a holographic filter, a dichroic mirror or a dichroic filter.

대표청구항 ▼

What is claimed is: 1. A fingerprint reader, comprising:an illumination source that produces light;a camera;an optical window;an ambient light filter in contact with the optical window;wherein the light from the illumination source enters the optical window at a total internal reflection angle, such

What is claimed is: 1. A fingerprint reader, comprising:an illumination source that produces light;a camera;an optical window;an ambient light filter in contact with the optical window;wherein the light from the illumination source enters the optical window at a total internal reflection angle, such that the light is reflected off a surface of the optical window by total internal reflection;wherein when a person's finger is placed on the optical window, the light from the illumination source is frustrated by oils on ridges of the finger and is not reflected off the optical window;wherein the filter allows the light from the illumination source to pass through the filter at the total internal reflection angle inside the optical window while reflecting ambient light coming from outside of the optical window so that the ambient light does not reach the camera;wherein the ambient light can cancel or diminish the quality of a desired fingerprint to be imaged;wherein the illumination source and the filter are designed so that the light from the illumination source contacts the filter within a desired range of angles, so that the light from the illumination source is not affected by the filter; andwherein the filter is designed so that the ambient light contacts the filter outside of the desired range of angles, so that the filter rejects the ambient light.