Method and apparatus for calibrating an optical computer input system

• US 5,181,015 A
• Filed: 11/09/1990
• Issued: 01/19/1993
• Est. Priority Date: 11/07/1989
• Status: Expired due to Term

• Current Assignee: Straight Signals LLC (Intellectual Ventures LLC)
• Original Assignee: Proxima Corporation (Ask ASA)
• Inventors: Hauck, Lane T., Shapiro, Leonid, Marshall, Roger N., Busch, Jeffrey W., Stevens, Eric S.
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): WU, XIAO MIN
• Application Number:
  US07/611,416
• Time in Patent Office: 802 Days
• Field of Search: 340/707, 340/709, 340/706, 340/705, 340/762, 340/782, 358/107, 358/93, 358/213.13, 434/323, 434/324, 434/325, 434/337, 356/375, 353/122, 353/28, 353/43
• US Class Current: 345/156
• CPC Class Codes: G06F 3/0386 for light pen
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

A method and apparatus facilitates the alignment and light sensitivity adjustment of an optical computer input system, which includes a user generated light directed onto a screen bearing a computer generated image, to convey information to the computer interactively by the user, even in a darkened room. The system discriminates between the user generated image, and the computer generated image. Devices facilitate the proper alignment of the system with the screen, as well as proper light sensitivity adjustments.

Claims

1. Optical input system calibration apparatus for facilitating alignment with an image reflected from a viewing surface, comprising:

a housing;

a single light sensing device for detecting the image reflecting from the viewing surface;

said light sensing device being adapted to be positioned in general alignment with a rectangularly shaped image reflecting from the viewing surface, said rectangularly shaped image being defined by four corner portions;

universal mounting means mounted to said housing for supporting said light sensing device and for permitting it to be moved to an adjusted position relative to the viewing surface so that the entire image reflecting from the viewing surface is detected;

means responsive to said light sensing device for generating electrical signals indicative which ones of the corner portions are detected from the image reflecting from the viewing surface;

alignment means responsive to said electrical signals for determining direction movements required to detect currently undetected corner portions of the reflect image, in any;

microprocessor means responsive to said alignment means for causing alignment signals to be generated, said alignment signals being indicative of movement directions for repositioning said light sensing device to a corrected position so it receives substantially the entire image reflecting from the viewing surface.

2. A calibration apparatus according to claim 1, further comprising:

signal means responsive to said light sensing device for generating a detection signal indicative of the presence of light detected by said light sensor means;

offset means for preventing said signal means from generating a detection signal in response to the presence of detected background light, when said background light does not exceeds a predetermined luminance level; and

reference level means coupled to said signal means for generating an auxiliary light information signal in response to the detection of an auxiliary light image and for generating a video signal in response to the detection of video image light reflected from the viewing surface.

3. A calibration apparatus according to claim 1, wherein said light sensing device is a charge coupled device.

4. A calibration apparatus according to claim 1, wherein said light sensing device includes an optical filter.

5. A calibration apparatus according to claim 4, wherein said optical filter is a ruby lith filter.

6. A calibration apparatus according to claim 4, wherein said optical filter is a red acetate filter.

7. A calibration apparatus according to claim 1, wherein said light sensing device is a charge couple device for sensing the presence of light over a given period of time.

8. A calibration apparatus according to claim 7, wherein said light sensing device is a raster scan device.

9. A calibration apparatus according to claim 7, wherein said given period of time is adjustable between a range of about 0.666 seconds and 0.166 seconds.

10. A calibration apparatus according to claim 8, wherein said raster scan device includes exposure means for adjusting said given period of time between a minimum period of time and a maximum period of time.

11. A calibration apparatus according to claim 10, wherein said minimum period of time corresponds to one refresh cycle of said reflected image.

12. A calibration apparatus according to claim 11, wherein said maximum period of time corresponds to four refresh cycles of said reflected image.

13. A calibration apparatus according to claim 1, wherein said alignment means includes indicating means for helping a user to properly align the viewing area of said light sensing device to be able to detect the light from the image reflecting from said viewing surface and the viewing surface adjacent to and surrounding the image reflecting from said viewing surface.

14. A calibration apparatus according to claim 13, wherein said indicating means includes a set of four light emitting devices.

15. A calibration apparatus according to claim 14, wherein said light emitting devices are light emitting diodes.

16. A calibration apparatus according to claim 15, wherein said light emitting devices are arranged in a diamond-shaped configuration.

17. A calibration apparatus according to claim 13, wherein said user interactive positioning means includes indicia means indicative of positioning directions.

18. A calibration apparatus according to claim 14, wherein said position directions includes UP, DOWN, RIGHT, LEFT.

19. A calibration apparatus according to claim 1, further comprising:

digital to analog converter means for generating an analog bias voltage to control the light energy sensitivity of said light sensing device.

20. A calibration apparatus according to claim 17, wherein said algorithm means further includes means for causing said microprocessor to generate a set of four direction signals for helping a user to interactively align the viewing area of said raster scan field in proper orientation relative to a video image reflecting from said viewing surface.

28. A calibration apparatus according to claim 7, further comprising:

band pass filter means for preventing said means responsive to light from detecting light information outside of a given wavelength range.

21. Optical input system calibration apparatus for facilitating alignment with an image reflected from a viewing surface, comprising:

a single light sensing device for detecting the presence of light produced from an image reflecting from the viewing surface;

means for mounting said single light sensing device for universal movement relative to said viewing surface;

detecting means for determining whether the entire reflected image from the viewing surface can be detected and for generating a plurality of electrical signals indicative of the direction of any miscalibration; and

indicating means responsive to said signals for providing indications of miscalibration directions when the entire reflected image on the viewing surface can not be detected to indicate the direction of movement of said sensing device so that it can be adjusted positionally until it detects substantially the entire reflected image.

22. A calibration apparatus according to claim 21, wherein said indicating means includes light emitting means for providing a visual indication of said miscalibration directions.

23. A calibration apparatus according to claim 22, wherein said light emitting means includes a set of light emitting diodes.

24. Optical input system calibration apparatus for facilitating alignment with an image reflecting from a viewing surface according to claim 21, wherein said light sensing device includes:

means responsive to light reflecting from the viewing surface for generating an image signal indicative of the luminance levels of the light reflecting from the viewing surface;

timing generator means for producing raster scan signals to control the refresh rate of said means responsive to light reflecting from the viewing surface, said raster scan signals recurring during a predetermined time period;

light sensitivity means responsive to said image signal for generating a detection signal indicative of the presence of light reflecting from the viewing surface;

microprocessor means for adjusting the responsiveness of said light sensitivity means to said image signal so that said detection signal is indicative of light having a given luminance level; and

refresh control means for causing said predetermined time period to be increased or decreased to adjust the sensitivity level of said means responsive to light reflecting from the viewing surface to different levels of luminance reflecting from the viewing surface.

25. A calibration apparatus according to claim 24, wherein said light sensitivity means is a comparator means having a pair of inputs, one of said inputs being coupled to said means responsive to light from the viewing surface and the other one of said inputs being coupled to said microprocessor means.

26. A calibration apparatus according to claim 25, further comprising:

p1 image signal amplification means for increasing or decreasing the strength of said image signal to a sufficient level to enable said comparator means to generate a detection signal in response to said image signal.

27. A calibration apparatus according to claim 25, wherein said

microprocessor means includes

algorithm means for causing said microprocessor means to generate a digital signal indicative of a reference level voltage to control the responsiveness of said light sensitivity means to said image signal.

29. A method for aligning an optical computer input system comprising:

using a light sensing device for detecting the presence of light reflecting from a viewing surface;

generating electrical signals indicative of the height and width of the image reflecting from the viewing surface;

determining whether said light sensing device is sufficiently aligned relative to the reflected image to receive substantially the entire image reflecting from the viewing surface; and

causing alignment signals to be generated, said alignment signals being indicative of movement directions for repositioning said light sensing device to a corrected position so it receives substantially the entire image reflecting from the viewing surface.

30. A method for alignment according to claim 29, further comprising:

generating a light information signal in response to said light sensing device detecting light reflecting from the viewing surface;

responding to said light information signal by generating a detection signal indicative of the presence of light detected by said light sensing device; and

preventing said detection signal from being generated in response to the presence of detected background light, when said background light is less than a predetermined luminance level; and

generating an information signal in response to the detection of information light reflecting from the viewing surface.

31. Optical input system calibration apparatus for facilitating alignment with an image reflected from a viewing surface, comprising:

light sensing means for detecting the reflected image;

means for determining the width and height of a detected image on the viewing surface;

means for storing image detection signals indicative of the width and the height of said detected image;

means for comparing the stored signals with another set of signals indicative of the width and height of a projected image on the viewing surface;

computing means for determining the peripheral boundaries of said detected image; and

means responsive to said means for comparing and to said computing means for generating left, right, up and down signals indicative of light sensing means movement directions, so that the entire peripheral boundaries of the reflected image can be detected by suitable movement to a corrected position of said light sensing means.

32. A method for aligning image detection means to receive a given image reflected from a viewing surface, comprising:

determining the width and height of a detected image on the viewing surface;

storing image detection signals indicative of X and Y distance values for the width and the height of said detected image;

comparing the stored signals with another set of signals indicative of the width and the height of a projected image on the viewing surface;

determining the peripheral boundaries of said detected image;

generating left, right, up and down signals indicative of movement directions, so that the entire peripheral boundaries of the reflected image can be detected by suitable movement to a corrected position of a light sensing device, whereby the entire width and height of the given image can be detected.