Passive touch system and method of detecting user input

• US 8,055,022 B2
• Filed: 02/24/2009
• Issued: 11/08/2011
• Est. Priority Date: 07/05/2000
• Status: Expired due to Term

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Singh, Manvinder, Morrison, Gerald
• Primary Examiner(s): COUSO, YON JUNG
• Application Number:
  US12/391,759
• Publication Number:
  US 20090153523A1
• Time in Patent Office: 987 Days
• Field of Search: 382/103, 382/106, 382/107, 382/154, 382/192, 382/193, 382/194, 382/286, 382/291, 382/292, 348/42, 348/47, 348/48, 348/143, 348/153, 348/159, 345/157, 345/168, 345/173, 345/863
• US Class Current: 382/103
• CPC Class Codes: G06F 3/042 by opto-electronic means
• 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
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

A method of tracking an object of interest preferably includes (i) acquiring a first image and a second image representing different viewpoints of the object of interest; (ii) processing the first image into a first image data set and the second image into a second image data set; (iii) processing the first image data set and the second image data set to generate a background data set associated with a background; (iv) generating a first difference map by determining differences between the first image data set and the background data set and a second difference map by determining differences between the second image data set and the background data set; (v) detecting a first relative position of the object of interest in the first difference map and a second relative position of the object of interest in the second difference map; and (vi) producing an absolute position of the object of interest from the first and second relative positions of the object of interest.

Claims

1. A method of determining the absolute position of an object relative to a rectangular frame surrounding a region of interest in the front of a display surface from images captured by at least two digital camera devices, each digital camera device being mounted adjacent a different corner of the frame, said method comprising:

capturing images with the digital camera devices, each digital camera device having a field of view that (i) images at least a portion of the display surface, (ii) images at least a portion of the frame, and (iii) extends at least beyond an adjacent peripheral edge of said frame, said digital camera devices being oriented to capture overlapping images of said region of interest, at least one of the digital camera devices having a sensor comprising a plurality of pixels extending in at least one direction; and

processing pixel data of images received from each digital camera device using at least one processor to compensate for an angle between the field of view of each digital camera device and at least a portion of the peripheral edge of the frame and to determine the absolute position of the object relative to the frame.

2. The method of claim 1, wherein said image capturing comprises capturing images with digital camera devices that each comprise a CMOS image sensor.

3. The method of claim 1, wherein each digital camera device comprises a selectable pixel array, and wherein during said processing, pixel data from a subset of pixels of the selectable pixel array of each digital camera device is processed.

4. The method of claim 3, wherein during said processing, pixel data from a subset of contiguous rows of pixels of the selectable pixel array of each digital camera device is processed.

5. The method of claim 3, wherein during said processing, pixel data from a subset of contiguous rows of pixels, that is aligned so that the subset of pixels looks generally along a plane substantially coplanar to said display surface, of the selectable pixel array of each digital camera device is processed.

6. The method of claim 5, wherein during said processing, the row of pixels in the subset of pixels of the selectable pixel array of each digital camera device, that acquires pixel data corresponding to a tip of said pointer within said region of interest, is determined to detect pointer contact and pointer hover over said display surface.

7. A method of determining the absolute position of an object relative to a rectangular frame surrounding a region of interest in the front of a display surface from images captured by at least two imaging assemblies, each imaging assembly being mounted adjacent a different corner of the frame, said method comprising:

capturing images with the imaging assemblies, each imaging assembly being oriented so that the fields of view of the imaging assemblies overlap across the front of the display surface and so that the field of view of each imaging assembly extends at least beyond an adjacent peripheral edge of said frame, at least one of the imaging assemblies having a sensor comprising a plurality of pixels extending in at least one direction; and

processing pixel data of images received from each imaging assembly using at least one processor to compensate for an angle between the field of view of each imaging assembly and at least a portion of the peripheral edge of the frame and to determine the absolute position of the object relative to the frame.

8. The method of claim 7, wherein said image capturing comprises capturing images with imaging assemblies that each comprise a CMOS image sensor.

9. The method of claim 7, wherein during said processing, a subset of pixel data of images captured by each imaging assembly is processed.

10. The method of claim 7, wherein during said processing, a subset of contiguous rows of pixel data of images captured by each imaging assembly is processed.

11. The method of claim 7, wherein during said processing, a subset of contiguous rows of pixel data that is aligned so that the subset looks generally along a plane substantially coplanar to said display surface, of images captured by each imaging assembly is processed.

12. The method of claim 11, wherein during said processing, the row that acquires pixel data corresponding to a tip of said pointer within said region of interest, is determined to detect pointer contact and pointer hover over said display surface.