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

• US 20050277071A1
• Filed: 06/14/2004
• Published: 12/15/2005
• 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.
• Granted Patent: US 7,787,706 B2
• Time in Patent Office: Days
• US Class Current: 430/396
• 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 method for controlling an intensity of a light source in response to an ambient light level, comprising the steps of:

(a) providing a region that is substantially prevented from receiving incident ambient light, but is able to receive light generally only from the light source;

(b) capturing an image of both the region and a diffusing surface through which the ambient light passes, producing a signal corresponding to the image;

(c) processing the signal to determine a level of the light reflected from the region and the ambient light level for the ambient light passing through the diffusing surface; and

(d) controlling the intensity of the light source so that the level of the light reflected from the region exceeds the ambient light level by a predefined amount.

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

3. The method of claim 2, wherein the diffusing surface comprises an interactive display surface on which an object is detected in response to IR light reflected from the object when the object is disposed adjacent to the interactive display surface, the step of controlling the intensity of the light source enabling the IR light reflected from the object to be apparent relative to the ambient IR light that passes through the interactive display surface.

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

5. The method of claim 1, further comprising the step of carrying out steps (b) and (d) after a predetermined number of images of the diffusing surface have been captured since a previous time that steps (b) and (d) were carried out, except for a first time the image is captured after the light source is energized.

6. The method of claim 1, further comprising the step of processing the signal to determine the light level reflected from a plurality of regions that are spaced apart around the diffusing surface, wherein the step of controlling comprises the step of controlling 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.

7. A memory medium having machine executable instructions for carrying out the steps of claim 1.

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

(a) a diffusing surface;

(b) a light source that produces light;

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

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

(e) a light sensor for capturing images, producing a signal corresponding to the images captured;

(f) a processor coupled to the light sensor and the 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 processor to control the light source relative to the ambient light level by carrying out a plurality of functions, including;

(i) using the light sensor for capturing an image of both the region and the diffusing surface through which the ambient light passes, producing a signal corresponding to the image;

(ii) processing the signal to determine a level of the light reflected from the region and the ambient light level of ambient light passing through the diffusing surface; and

(iii) controlling the intensity of the light source with the controller, so that the level of the light reflected from the region exceeds the ambient light level by a predefined amount.

9. The system of claim 8, wherein the light source produces infrared (IR) light, the image that is captured is an IR image, and the ambient light level is an ambient IR light level.

10. The system of claim 8, wherein the region is disposed peripherally of the diffusing surface and within an enclosure that shields the region from the ambient light being directly incident on the region.

11. The system of claim 8, wherein the machine instructions further cause the processor to sense the light reflected from the region and control the intensity of the light source in response to the ambient light level after a predetermined number of images of the diffusing surface have been captured since a previous time that the light reflected from the region and the intensity of the light source was controlled, except for a first time the image is captured after the light source is energized.

12. The system of claim 8, further comprising a plurality of regions spaced apart around the diffusing surface, wherein the machine instructions further cause the processor to process the signal to determine the light level reflected from the plurality of 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.

13. The system of claim 8, wherein the region comprises an underside of a peripheral area generally surrounding the diffusing surface.

14. The system of claim 8, further comprising a housing that substantially excludes ambient light from being incident on the sensor, except for the ambient light that passes through the diffusing surface.

15. The system of claim 8, wherein the predefined amount by which the level of the light reflected from the region exceeds the ambient light level is selected to enable light from an object adjacent to the diffusing surface to be detected in the presence of the ambient light, so that the object is detectable.

16. A method for controlling an intensity of an IR light source that emits infrared (IR) light in response to a level of ambient IR light that passes through an interactive display surface, to achieve sufficient contrast between light reflected from an object adjacent to the interactive display surface and the ambient IR light so that the object can be detected adjacent to the interactive display surface, comprising the steps of:

(a) capturing an IR image that includes any ambient IR light passing through from the interactive display surface, any IR light from the IR light source that is reflected by any object adjacent to the interactive display surface, and IR light from the IR light source that is reflected from a peripheral region adjacent to the interactive display surface;

(b) evaluating the image to determine a relative level of the IR light reflected from the peripheral region, compared to the ambient IR light passing through the interactive display surface; and

(c) controlling the intensity of the IR light source to try to keep the level of the IR light reflected from the peripheral region greater than the level of the ambient IR light passing through the interactive display surface.