Patent ID: 6891962

Claim:
A fingerprint sensor, comprising: a first optical component including a first surface on which a finger is placed and a second surface which forms a certain angle with respect to said first surface; a light source provided at a first side of said first optical component and emits light directly against said first optical component to irradiate the finger placed on said first surface with the light; an image sensor for receiving the light reflected from the finger and converting fingerprint information for the finger into an electric signal; and a second prism array of multiple second triangular prisms arranged side by side, said second prism array being provided at a second side opposite said first side with respect to said first optical component, each of said multiple second triangular prisms including a fourth surface, a fifth surface, and a sixth surface, said fifth surface being greater than said sixth surface such that an angle between said fourth surface and said fifth surface is smaller than an angle between said fourth surface and said sixth surface, the light emitted from said first optical component entering said second triangular prisms from said fourth surface and being emitted from said fifth surface, in light paths between said first optical component and said image sensor, said second prism array performing a first refraction of said light reflected from said finger placed on said first surface as said light enters said second prism array and performing a second refraction of said light as said light exits said second prism array towards said image sensor such that a difference between a first length of a light path from a first portion of said first surface to a first corresponding portion of said image sensor and a second length of a light path from a second portion of said first surface to a second corresponding portion of said image sensor is smaller than a difference between the first length and the second length without said second prism array and such that said light contacts the image sensor in a substantial normal direction to said irradiated finger.