Palm scanner using a programmable nutating mirror for increased resolution

• US 6,928,195 B2
• Filed: 12/18/2001
• Issued: 08/09/2005
• Est. Priority Date: 12/18/2000
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Cross Match Technologies Incorporated (Assa Abloy AB)
• Inventors: Van Dusen, John, Scott, Walter G., Irving, Richard D.
• Primary Examiner(s): PATEL, KANJIBHAI B
• Application Number:
  US10/020,498
• Publication Number:
  US 20020090147A1
• Time in Patent Office: 1,330 Days
• Field of Search: 382/124, 382/127, 382/274, 382/296, 382/299, 382/313, 396/261, 396/315, 359/17, 359/19, 359/226, 359/212, 358/1.2
• US Class Current: 382/299
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

A system and method for increasing image resolution in a palm print scanner. The method of the invention requires the synchronization of a nutating mirror with a camera frame sync. A first image is scanned at a first nutation position. The mirror is nutated by a fraction of a pixel amount in one direction. Another image is scanned at a second nutation position. The process of nutating the mirror to a different nutation position and scanning an image is repeated until all sub-pixels needed to increase an image resolution are obtained. All of the sub-pixels obtained are then interlaced to obtain a higher resolution image.

Claims

1. A method for increasing image resolution in a palm print scanner, comprising the steps of:

(1) synchronizing a nutating mirror with a camera frame sync;

(2) scanning a frame of an image at a first nutation position;

(3) positioning the nutating mirror by a fraction of a pixel amount in one direction to obtain a next nutation position;

(4) scanning the frame of another image at the next nutation position;

(5) repeating steps (3) and (4) until an image is obtained for each nutation position needed; and

(6) mapping sub-pixels from each of the images obtained in steps (2), (4), and (5) to an image of pixels having a higher resolution than the respective images of sub-pixels.

2. The method of claim 1, wherein step (6) comprises the steps of:

(a) gathering each image of sub-pixels from memory;

(b) allocating memory for the higher resolution image;

(c) mapping sub-pixels from the first nutation position image onto the higher resolution image; and

(d) interlacing sub-pixels from each of the images obtained in steps (2), (4) and (5) onto the higher resolution image.

3. A palm print imaging system, comprising:

a light emitting diode (LED);

an illuminator mirror;

a condenser lens;

a conformable prism, wherein said LED, said illuminator mirror, and said condenser lens provide color illumination to said conformable prism to obtain an image reflected from said conformable prism;

plurality of mirrors;

a nutating mirror, wherein said plurality of mirrors direct said image to said nutating mirror;

a driver for controlling said nutating mirror; and

a camera for capturing said image,

wherein said camera provides signals to said driver to synchronize said nutating mirror with camera frame syncs.

4. The system of claim 3, wherein said conformable prism is spring loaded.

5. The system of claim 3, wherein said conformable prism is used as a palm platen.

6. The system of claim 3, wherein said nutating mirror is repositioned to obtain a plurality of images, wherein said plurality of images are used in an interlacing recombining scheme to obtain a higher resolution image.

7. The system of claim 3, wherein said nutating mirror is two-dimensional and programmable to allow movement in two different axial directions.

8. The system of claim 3, wherein said conformable prism is comprised of a silicone pad.