DISPLACEMENT DETECTION APPARATUS AND METHOD

• US 20110150363A1
• Filed: 11/30/2010
• Published: 06/23/2011
• Est. Priority Date: 12/18/2009
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: CHEN, H sin Chia, CHEN, Chun Wei
• Granted Patent: US 8,515,129 B2
• Time in Patent Office: Days
• US Class Current: 382/291
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device

Abstract

A displacement detection method includes the steps of: capturing a first frame and a second frame; selecting a first block with a predetermined size in the first frame and selecting a second block with the predetermined size in the second frame; determining a displacement according to the first block and the second block; comparing the displacement with at least one threshold; and adjusting the predetermined size according to a comparison result of comparing the displacement and the threshold. The present invention further provides a displacement detection apparatus.

Claims

1. A displacement detection method, comprising the steps of:

capturing a first frame and a second frame;

selecting a first block with a predetermined size in the first frame and a second block with the predetermined size in the second frame;

determining a displacement according to the first block and the second block;

comparing the displacement with at least one threshold; and

adjusting the predetermined size according to a comparison result of comparing the displacement and the threshold.

2. The displacement detection method as claimed in claim 1, further comprising:

transmitting the displacement to an image display.

3. The displacement detection method as claimed in claim 1, wherein the displacement is a sum of the absolute value of a displacement in a first direction and the absolute value of a displacement in a second direction perpendicular to the first direction, or a sum of square of a displacement in the first direction and a displacement in the second direction.

4. The displacement detection method as claimed in claim 1, wherein the step of determining a displacement according to the first block and the second block further comprises:

searching the second block having the highest correlation with the first block in the second frame; and

calculating a position difference between a corresponding position of the first block in the second frame and a position of the second block as the displacement.

5. The displacement detection method as claimed in claim 1, wherein the displacement is the movement in a second.

6. The displacement detection method as claimed in claim 1, wherein the predetermined size comprises a first size and a second size smaller than the first size, and the displacement detection method further comprises:

selecting the second size when the displacement is larger than the threshold; and

selecting the first size when the displacement is smaller than the threshold.

7. The displacement detection method as claimed in claim 1, wherein the predetermined size comprises a first size and a second size smaller than the first size, and the threshold comprises an upper threshold and a lower threshold lower than the upper threshold, and the displacement detection method further comprises:

adjusting the predetermined size to the second size when the predetermined size is the first size and the displacement is larger than the upper threshold;

maintaining the predetermined size as the first size when the predetermined size is the first size and the displacement is smaller than the upper threshold;

adjusting the predetermined size to the first size when the predetermined size is the second size and the displacement is smaller than the lower threshold; and

maintaining the predetermined size as the second size when the predetermined size is the second size and the displacement is larger than the lower threshold.

8. The displacement detection method as claimed in claim 1, wherein a plurality of thresholds are formed as a look-up table, and the step of comparing the displacement with at least one threshold is to compare the displacement with the look-up table.

9. A displacement detection method, comprising the steps of:

capturing a first frame and a second frame;

comparing an area with a predetermined size of the first frame with an area with the predetermined size of the second frame;

determining a displacement according to a comparison result;

decreasing the predetermined size when the displacement is larger than an upper threshold; and

increasing the predetermined size when the displacement is smaller than a lower threshold.

10. The displacement detection method as claimed in claim 9, further comprising:

transmitting the displacement to an image display.

11. The displacement detection method as claimed in claim 9, wherein the displacement is a sum of the absolute value of a displacement in a first direction and the absolute value of a displacement in a second direction perpendicular to the first direction, or a sum of square of a displacement in the first direction and a displacement in the second direction.

12. The displacement detection method as claimed in claim 9, wherein the displacement is a movement in a second, and the lower threshold is smaller than the upper threshold.

13. The displacement detection method as claimed in claim 9, wherein the predetermined size is decreased or increased by two pixels each step.

14. The displacement detection method as claimed in claim 9, wherein the step of comparing an area with a predetermined size of the first frame with an area with the predetermined size of the second frame is to compare the correlation of the area with the predetermined size of the first frame and the area with the predetermined size of the second frame.

15. A displacement detection apparatus, comprising:

an image sensing unit, configured to capture a first frame and a second frame;

a storage unit, configured to store at least one threshold; and

a processing unit, configured to select a first block with a predetermined size in the first frame and select a second block with the predetermined size in the second frame, determine a displacement according to the first block and the second block, compare the displacement with at least one threshold, and adjust the predetermined size according to a comparison result of comparing the displacement and the threshold.

16. The displacement detection apparatus as claimed in claim 15, further comprising a light source to provide the light when the image sensing unit is capturing image frames.

17. The displacement detection apparatus as claimed in claim 15, further comprising a transmission interface unit to transmit the displacement obtained by the processing unit to an image display.

18. The displacement detection apparatus as claimed in claim 17, wherein the transmission interface unit is wirelessly or electrically coupled to the image display.

19. The displacement detection apparatus as claimed in claim 15, wherein the first frame and the second frame captured by the image sensing unit are stored in the storage unit.

20. The displacement detection apparatus as claimed in claim 15, wherein the displacement detection apparatus is an optical mouse.