CLICK-EVENT DETECTION DEVICE

• US 20130100023A1
• Filed: 09/13/2012
• Published: 04/25/2013
• Est. Priority Date: 10/25/2011
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: CHEN, Hsin Chia, GU, Ren Hau, LEE, Yi Fang, KAO, Ming Tsan, HUANG, Yu Hao
• Granted Patent: US 9,389,726 B2
• Time in Patent Office: Days
• US Class Current: 345/166
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

There is provided a click-event detection device including a light source, a light control unit, an image sensor and a processing unit. The light control unit is configured to control the light source to illuminate a finger. The image sensor receives reflected light from the finger to accordingly output a plurality of bright image frames and dark image frames. The processing unit is configured to calculate a differential image characteristic between the bright image frames and the dark image frames, to determine a plurality of operating states according to the differential image characteristic, to count a residence time at each of the operating states, and to identify a click-event according to the operating states and the residence time.

Claims

1. A click-event detection device, configured to detect a click-event of a finger, the click-event detection device comprising:

a light source configured to illuminate the finger;

a light control unit configured to control the light source to illuminate with a first brightness value and a second brightness value;

an image sensor configured to receive reflected light from the finger at a sampling frequency to output bright image frames corresponding to the first brightness value and to output dark image frames corresponding to the second brightness value; and

a processing unit configured to calculate a plurality of differential image characteristics according to the bright image frames and the dark image frames, to determine a plurality of operating states according to the differential image characteristics, to count a residence time at each of the operating states, and to identify the click-event according to the operating states and the residence time.

2. The click-event detection device as claimed in claim 1, wherein the differential image characteristic is an average brightness difference, an image quality difference, a normalized average brightness difference or a normalized image quality difference between one of the bright image frames and one of the dark image frames;

the normalized average brightness difference is obtained by normalizing the average brightness difference with a sampling parameter, and the normalized image quality difference is obtained by normalizing the image quality difference with the sampling parameter.

3. The click-event detection device as claimed in claim 1, wherein the processing unit determines the operating states according to a variation of the differential image characteristics and at least one varying threshold.

4. The click-event detection device as claimed in claim 1, wherein the processing unit determines the operating states according to a value of the different image characteristics and at least one threshold.

5. The click-event detection device as claimed in claim 1, wherein the processing unit further calculates a displacement according to the bright image frames and identifies the click-event according to the operating states, the residence time and the displacement.

6. The click-event detection device as claimed in claim 1, wherein the first brightness value is larger than the second brightness value, and the second brightness value has a zero or a non-zero brightness value.

7. A click-event detection device, configured to detect a click-event of a finger, the click-event detection device comprising:

a light source configured to illuminate the finger;

a light control unit configured to control the light source to illuminate with a first brightness value and a second brightness value;

an image sensor configured to receive reflected light from the finger at a sampling frequency to output bright image frames corresponding to the first brightness value and to output dark image frames corresponding to the second brightness value; and

a processing unit configured to calculate a plurality of differential image characteristics according to the bright image frames and the dark image frames, wherein the processing unit identifies a single-click when following two conditions are satisfied sequentially;

(1) a first variation of the differential image characteristics is larger than a first varying threshold within a first time interval;

and (2) a second variation of the differential image characteristics is smaller than or equal to a second varying threshold within a second time interval.

8. The click-event detection device as claimed in claim 7, wherein the first varying threshold is equal to or different from the second varying threshold.

9. The click-event detection device as claimed in claim 7, wherein the differential image characteristic is an average brightness difference, an image quality difference, a normalized average brightness difference or a normalized image quality difference between one of the bright image frames and one of the dark image frames;

the normalized average brightness difference is obtained by normalizing the average brightness difference with a sampling parameter, and the normalized image quality difference is obtained by normalizing the image quality difference with the sampling parameter.

10. The click-event detection device as claimed in claim 9, wherein the sampling parameter is at least one of an exposure time and an image gain.

11. The click-event detection device as claimed in claim 7, wherein the processing unit further calculates a displacement according to the bright image frames within the second time interval, and ends the detection of the click-event when the displacement exceeds a predetermined range.

12. The click-event detection device as claimed in claim 7, wherein the processing unit identifies a double-click when following four conditions are satisfied sequentially:

(1) the first variation of the differential image characteristics is larger than the first varying threshold within the first time interval;

(2) the second variation of the differential image characteristics is smaller than or equal to the second varying threshold within the second time interval;

(3) a third variation of the differential image characteristics is larger than the first varying threshold within a third time interval; and

(4) a fourth variation of the differential image characteristics is smaller than or equal to the second varying threshold within a fourth time interval.

13. The click-event detection device as claimed in claim 12, wherein the processing unit further calculates a displacement according to the bright image frames within the second time interval and the fourth time interval, and ends the detection of the click-event when the displacement exceeds a predetermined range.

14. A click-event detection device, configured to detect a click-event of a finger, the click-event detection device comprising:

a light source configured to illuminate the finger;

a light control unit configured to control the light source to illuminate with a first brightness value and a second brightness value;

an image sensor configured to receive reflected light from the finger at a sampling frequency to output bright image frames corresponding to the first brightness value and to output dark image frames corresponding to the second brightness value; and

a processing unit configured to calculate a plurality of differential image characteristics according to the bright image frames and the dark image frames, wherein the processing unit identifies a single-click when following two conditions are satisfied sequentially;

(1) a first value of the differential image characteristics is larger than a first threshold within a first time interval; and

(2) a second value of the differential image characteristics is smaller than or equal to a second threshold within a second time interval.

15. The click-event detection device as claimed in claim 14 wherein the first threshold is equal to or different from the second threshold.

16. The click-event detection device as claimed in claim 14, wherein the differential image characteristic is an average brightness difference, an image quality difference, a normalized average brightness difference or a normalized image quality difference between one of the bright image frames and one of the dark image frames;

the normalized average brightness difference is obtained by normalizing the average brightness difference with a sampling parameter, and the normalized image quality difference is obtained by normalizing the image quality difference with the sampling parameter.

17. The click-event detection device as claimed in claim 16, wherein the sampling parameter is at least one of an exposure time and an image gain.

18. The click-event detection device as claimed in claim 14, wherein the processing unit further calculates a displacement according to the bright image frames within the second time interval, and ends the detection of the click-event when the displacement exceeds a predetermined range.

19. The click-event detection device as claimed in claim 14, wherein the processing unit identifies a double-click when following four conditions are satisfied sequentially:

(1) the first value of the differential image characteristics is larger than the first threshold within the first time interval;

(2) the second value of the differential image characteristics is smaller than or equal to the second threshold within the second time interval;

(3) a third value of the differential image characteristics is larger than the first threshold within a third time interval; and

(4) a fourth value of the differential image characteristics is smaller than or equal to the second threshold with a fourth time interval.

20. The click-event detection device as claimed in claim 19, wherein the processing unit further calculates a displacement according to the bright image frames within the second time interval and the fourth time interval, and ends the detection of the click-event when the displacement exceeds a predetermined range.