Opto sensor signal detector
AssigneeThomson Licensing
InventorJohn Barrett George
Life of this patent
Estimating the term…
Abstract
A projection display comprises a display device forming an image for projection onto a display screen. A photo sensor is adjacent to the display screen and generates a first signal responsive to a level of the projected image illumination incident on the photo sensor. A detector is coupled to receive the first signal and generates an output signal indicative of detecting the first signal. A source of a predetermined detection threshold value is coupled to the detector for determining a threshold at which the detection of the first signal occurs. Wherein the first signal exceeds the predetermined detection threshold value, the detector detects and generates the output signal indicative of signal detection, and generates a second signal for coupling to the source to change the predetermined detection threshold value.
Claims20
A projection display, comprising:
- a display device forming an image for projection onto a display screen;
- a photo sensor adjacent said display screen and generating a first signal responsive to a level of said projected image illumination incident on said photo sensor;
- a detector coupled to receive said first signal and generating an output signal indicative of detecting said first signal;
- and,
- a source of a predetermined detection threshold value coupled to said detector for determining a threshold at which said detection of said first signal occurs,
- wherein said first signal exceeding said predetermined detection threshold value, said detector detects and generates said output signal indicative of signal detection, and generates a second signal for coupling to said source to change said predetermined detection threshold value.
An apparatus for detecting an intensity of illumination in a projection display, comprising:
- a projection means for forming a display image;
- a photo sensor illuminated by said display image and generating a first signal responsive to an intensity of said display image illumination incident on said photo sensor;
- a detector coupled to receive said first signal and generating an output signal indicative of detecting said first signal;
- and,
- a first threshold value coupled to said detector for determining a value of said first signal at which detection occurs, said first signal being responsive to a first intensity of illumination incident on said sensor,
- wherein upon detection of said first intensity of illumination said detector generates said output signal indicative of detection, and changes said first threshold value to a second threshold value, said second threshold value determining a second intensity of illumination at which said detector terminates generation of said output signal.
A circuit for detecting a projected image having illumination of variable intensity, comprising:
- a display device with an image projected on a display screen;
- a photo sensor adjacent said screen and generating a sensor signal responsive to a level of illumination from said projected raster scanned image incident on said photo sensor;
- a detector coupled to receive said sensor signal and generating an output signal indicative of detecting said sensor signal;
- a first threshold value coupled to said detector for determining a first detection value for said sensor signal responsive to a first intensity of illumination incident on said sensor;
- and,
- a second threshold value controllably coupled to said detector for determining a second detection value of said sensor signal responsive to a second intensity of illumination incident on said sensor,
- whereupon detection of said first intensity of illumination said detector generates said output signal and controllably couples said second threshold value to said detector for determining said second intensity of illumination for terminating generation of said output signal.
Dependencies are inferred from the claim text.