OPTICAL DISTANCE MEASUREMENT SYSTEM AND OPERATION METHOD THEREOF

• US 20130131473A1
• Filed: 09/13/2012
• Published: 05/23/2013
• Est. Priority Date: 11/18/2011
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: GU, Ren-Hau, KAO, Ming-Tsan, HUANG, Sen-Huang, LIAO, Chi-Chieh
• Granted Patent: US 9,204,843 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6886 Monitoring or controlling distance between sensor and tissue
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

There is provided an operation method of an optical distance measurement system including a first mode and a second mode. The first mode is configured to detect a finger distance. The second mode is configured to detect a physiological characteristic, wherein the optical distance measurement system transfers from the first mode to the second mode when the finger distance is within a predetermined range. There is further provided an optical distance measurement system.

Claims

1. An optical distance measurement system configured to detect a finger distance and a physiological characteristic, the optical distance measurement system comprising:

a first light source providing light of a first wavelength to a finger;

a second light source providing light of a second wavelength to the finger;

a light control unit configured to control on-states of the first light source and the second light source;

an image sensor receiving reflected light from the finger at a sampling frequency to generate a plurality of first image frames corresponding to the on-states of the first light source and a plurality of second image frames corresponding to the on-states of the second light source; and

a processing unit configured to calculate the finger distance according to the first image frames or the second image frames and to calculate the physiological characteristic according to the first image frames and the second image frames when the finger distance is within a predetermined range.

2. The optical distance measurement system as claimed in claim 1, wherein when the finger distance is within the predetermined range, the processing unit divides each of the first image frames into at least two parts and calculates an average brightness of each part, and analyzes the average brightness of the each part of the first image frames to obtain a first intensity variation;

divides each of the second image frames into at least two parts and calculates an average brightness of each part, and analyzes the average brightness of the each part of the second image frames to obtain a second intensity variation; and

calculates the physiological characteristic according to the first intensity variation and the second intensity variation.

3. The optical distance measurement system as claimed in claim 2, wherein the processing unit further calculates a heart rate according to a comparison result of comparing at least one pulse threshold with at least one of the first intensity variation and the second intensity variation.

4. The optical distance measurement system as claimed in claim 1, wherein the physiological characteristic comprises a blood oxygenation and a heart rate.

5. The optical distance measurement system as claimed in claim 1, wherein when the finger distance is within the predetermined range, the light control unit alternatively enables the on-states of the first light source and the second light source such that the image sensor receives the reflected light associated with the first light source and the second light source alternatively;

or the light control unit simultaneously enables the on-states of the first light source and the second light source such that the image sensor receives the reflected light associated with the first light source and the second light source simultaneously, and the image sensor comprises an optical filter covering at least a part of a sensing surface thereof.

6. The optical distance measurement system as claimed in claim 1, wherein the first light source, the second light source, the light control unit, the image sensor and the processing unit are packaged as a control chip to output the finger distance and the physiological characteristic processed by at least one of an encoding process, a sequential process and a compressing process.

7. The optical distance measurement system as claimed in claim 1, wherein the processing unit further detects a finger motion when the finger distance is not within the predetermined range.

8. The optical distance measurement system as claimed in claim 1, wherein the light control unit enables the on-states of one of the first light source and the second light source when the finger distance is not within the predetermined range.

9. The optical distance measurement system as claimed in claim 1, wherein the image sensor comprises a pixel array or a plurality of sensing pixels separated apart configured to detect the reflected light from the finger.

10. The optical distance measurement system as claimed in claim 1, wherein the processing unit further compensates errors caused by temperature variations.

11. An operation method of an optical distance measurement system, comprising:

a first mode configured to detect a finger distance; and

a second mode configured to detect a physiological characteristic, wherein the optical distance measurement system transfers from the first mode to the second mode when the finger distance is within a predetermined range.

12. The operation method as claimed in claim 11, wherein the second mode further comprises:

providing light of a first wavelength and a second wavelength to a finger surface;

using an image sensor to receive reflected light of the first wavelength to generate a plurality of first image frames and to receive reflected of the second wavelength to generate a plurality of second image frames;

dividing each of the first image frames and each of the second image frames into at least two parts and calculating an average brightness of each part;

analyzing the average brightness of the each part of the first image frames to obtain a first intensity variation and analyzing the average brightness of the each part of the second image frames to obtain a second intensity variation; and

calculating the physiological characteristic according to the first intensity variation and the second intensity variation.

13. The operation method as claimed in claim 12, further comprising:

calculating a heart rate according to a comparison result of comparing at least one pulse threshold with at least one of the first intensity variation and the second intensity variation.

14. The operation method as claimed in claim 11, further comprising:

showing the physiological characteristic using a response unit; and

generating a warning state when the physiological characteristic exceeds a predetermined value.

15. The operation method as claimed in claim 11, wherein the first mode further comprises:

illuminating a finger surface;

receiving reflected light from the finger surface to generate a plurality of image frames; and

calculating the finger distance according to an intensity distribution of the image frames.

16. The operation method as claimed in claim 15, further comprising:

detecting a finger motion according to an intensity variation of the image frames.

17. The operation method as claimed in claim 11, further comprising:

performing at least one of an encoding process, a sequential process and a compressing process on the finger distance or the physiological characteristic.

18. An operation method of an optical distance measurement system, comprising:

providing light of a first wavelength or a second wavelength to a finger surface;

receiving reflected light of the first wavelength or the second wavelength to generate a plurality of image frames;

calculating a finger distance according to an intensity distribution of the image frames; and

performing following steps when the finger distance is within a predetermined range;

providing light of the first wavelength and the second wavelength to the finger surface;

using an image sensor to receive reflected light of the first wavelength to generate a plurality of first image frames and to receive reflected light of the second wavelength to generate a plurality of second image frames;

dividing each of the first image frames and each of the second image frames into at least two parts and calculating an average brightness of each part;

analyzing the average brightness of the each part of the first image frames to obtain a first intensity variation and analyzing the average brightness of the each part of the second image frames to obtain a second intensity variation; and

calculating a blood oxygenation according to the first intensity variation and the second intensity variation.

19. The operation method as claimed in claim 18, wherein when the finger distance is within the predetermined range, the operation method further comprises:

calculating a heart rate according to a comparison result of comparing at least one pulse threshold with at least one of the first intensity variation and the second intensity variation.

20. The operation method as claimed in claim 19, further comprising:

using a response unit to show at least one of the blood oxygenation and the heart rate; and

generating a warning state when the blood oxygenation or the pulse rate exceeds a predetermined value.

21. The operation method as claimed in claim 18, further comprising:

detecting a finger motion according to an intensity variation of the image frames.