Method for controlling an intensity of an infrared source used to detect objects adjacent to an interactive display surface

• US 7,787,706 B2
• Filed: 06/14/2004
• Issued: 08/31/2010
• Est. Priority Date: 06/14/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Yee, Dawson L.
• Primary Examiner(s): CHACKO DAVIS, DABORAH
• Application Number:
  US10/867,434
• Publication Number:
  US 20050277071A1
• Time in Patent Office: 2,269 Days
• Field of Search: None
• US Class Current: 382/274
• 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

In an interactive display table that uses infrared (IR) light to detect an object on an interactive display surface, IR light sources within the table are controlled in response to the level of ambient IR light passing through the interactive display surface. Light from the IR light sources that is reflected the regions disposed inside the table and peripherally around the interactive display surface is captured in an image that also includes the ambient IR light passing through the interactive display surface. A signal corresponding to the image is processed, so that the relative levels of the IR light can be compared. The IR light sources are then controlled so that the level of IR light reflected from the regions exceeds the level of ambient IR light by at least a predefined amount.

Claims

1. A system for controlling an intensity of a light source in response to an ambient light level, comprising:

(a) a diffusing surface through which ambient light passes;

(b) a light source that produces light;

(c) a brightness controller that controls the intensity of the light produced by the light source;

(d) a region generally protected from receiving direct ambient light, said protected region reflecting light from the light source;

(e) a light sensor;

(f) a processor coupled to the light sensor and the brightness controller; and

(g) a memory coupled to the processor, the memory storing a plurality of machine instructions, which when executed by the processor, cause the system to ;

(i) use the light source and light sensor to detect a level of reflected light reflected from the protected region ;

(ii) use the light sensor to detect a level of ambient light passing through the diffusing surface;

(iii) compare the level of reflected light to the level of ambient light to determine if the intensity of the light source is appropriate based on the ambient level of light; and

(iv) regulate the intensity of the light source with the brightness controller, so that the light intensity is sufficient to reflect off of objects at or near the diffusing surface but the light intensity is not so great as to interfere with other nearby electronic devices that communicate using light signals.

2. The system of claim 1, wherein the light source produces infrared (IR) light, and the ambient light level is an ambient IR light level.

3. The system of claim 1, wherein the protected region is disposed peripherally of the diffusing surface and within an enclosure that shields the protected region from the ambient light being directly incident on the protected region.

4. The system of claim 1, further comprising a plurality of protected regions spaced apart around the diffusing surface, wherein the plurality of machine instructions further cause the processor to process the signal to determine the light level reflected from the plurality of protected regions, and to control the intensity of the light source so that the level of the light reflected from all of the plurality of regions exceeds the ambient light level by a predefined amount.

5. The system of claim 1, wherein the protected region comprises an underside of a peripheral area generally surrounding the diffusing surface.

6. The system of claim 1, further comprising a baffle disposed between the light source and the light sensor that substantially prevents light produced at the light source from directly entering the light sensor.

7. The system of claim 1, wherein comparing the level of reflected light to the level of ambient light comprises determining if the difference of subtracting the reflected light level from the ambient light level is greater than a first predefined level, the first predefined level representative of a light intensity that potentially interferes with other electronic devices that use light for communication.

8. The system of claim 1 , wherein regulating the intensity of the light source with the brightness controller comprises sending a control signal to the brightness controller to reduce the intensity of the light source to reduce potential interference with other devices.

9. The system of claim 1, wherein comparing the level of reflected light to the level of ambient light comprises if the difference of subtracting the ambient light level from the reflected light level is greater than a second predefined level, the second predefined level representative of a light intensity that potentially prevents the detection of objects at or near the diffusing surface.

10. The system of claim 1 , wherein regulating the intensity of the light source with the brightness controller comprises sending a control signal to the brightness controller to increase the intensity of the light source to increase the likelihood of light reflecting off of objects at or near the diffusing surface.