Light pen input system having two-threshold light sensing
First Claim
1. A light pen for use with an interactive display of a computer system, said display including a screen having a multiplicity of picture elements for visually presenting information provided by said computer system, said pen comprising:
- a body adapted to be hand held;
a tip carried by said body and extending therefrom for engaging said screen;
a principal fiber optic conduit mounted within said body and said tip for collecting light from said display when said tip has engaged said screen;
screen sensor means in communication with said computer system, for determining whether said tip has engaged said screen and for supplying a signal indicative thereof to said computer system; and
detector means in communication with said principal fiber optic conduit and said computer system, said detector means being responsive to first and second predetermined amplitudes of light collected by said principal conduit such that a signal is transmitted to said computer system by said detector means at the end of a fixed time interval following sensing by said detector means of light amplitude in excess of said first predetermined amplitude provided that during said fixed time interval said detector means also senses light amplitude in excess of said second predetermined amplitude,whereby, upon receipt of said detector means signal and said sensor means signal, said computer system may determine the position coordinates of said pen tip on said display screen.
1 Assignment
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Accused Products
Abstract
A fiber optic light pen has been adapted for high resolution use with an interactive display of a computer system. The body of the light pen, which is adapted to be hand held, includes a slightly movable tip for engaging a display screen. When so engaged, a screen sensor within the body signals to the computer system that the pen is in contact with the screen. A principal fiber optic element or conduit within the pen body collects light emitted by the screen without the use of any imaging optics and a two-threshold light detector responding to two different amplitude levels of collected light permits separate and high resolution determination of the vertical and horizontal positions of the light pen with respect to the screen.
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Citations
27 Claims
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1. A light pen for use with an interactive display of a computer system, said display including a screen having a multiplicity of picture elements for visually presenting information provided by said computer system, said pen comprising:
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a body adapted to be hand held; a tip carried by said body and extending therefrom for engaging said screen; a principal fiber optic conduit mounted within said body and said tip for collecting light from said display when said tip has engaged said screen; screen sensor means in communication with said computer system, for determining whether said tip has engaged said screen and for supplying a signal indicative thereof to said computer system; and detector means in communication with said principal fiber optic conduit and said computer system, said detector means being responsive to first and second predetermined amplitudes of light collected by said principal conduit such that a signal is transmitted to said computer system by said detector means at the end of a fixed time interval following sensing by said detector means of light amplitude in excess of said first predetermined amplitude provided that during said fixed time interval said detector means also senses light amplitude in excess of said second predetermined amplitude, whereby, upon receipt of said detector means signal and said sensor means signal, said computer system may determine the position coordinates of said pen tip on said display screen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A light pen for use in an interactive display of a computer system, the display including a screen having a multiplicity of picture elements with a persistence less than the horizontal sweep time of the display for visually presenting information provided by the computer system, the pen comprising:
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a body having a generally cylindrical shape which is adapted to be hand held; a tip axially and movably mounted within an end of the body and extending therefrom for engaging the screen; a principal fiber optic conduit axially mounted within the body and the tip for collecting light from a plurality of picture elements during a single display sweep when the tip has engaged the screen; a screen sensor, in communication with the computer system, for determining if the tip has engaged the screen and for supplying a signal indicative thereof to the computer system, the sensor including a light source, a fiber optic conduit and a detector, the sensor fiber conduit including a first segment and a second segment and means for optically coupling the first and second segments; a detector in communication with the principal fiber optic conduit and the computer system, the detector including a transducer in communication with the principal fiber optic conduit for producing a signal representative of the light intensity received from the principal conduit; a first level sensor connected to the transducer for producing a signal when the transducer signal exceeds a predetermined first amplitude level; and
a second level sensor connected to the transducer for producing a signal when the transducer signal exceeds a predetermined second amplitude level; anda driver connected to the first level sensor and the second level sensor for providing a signal in response to a combination of the first and second level sensor signals, whereby, on receipt of the driver signal and the screen sensor signal, the computer system may determine the position coordinates of the pen tip on the display screen. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A light pen arrangement for use in an interactive display of a computer system comprising:
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a display having a screen phosphor, and an electron beam for scanning the phosphor; a light pen with an optical field of view larger than a single scan line; first threshold detection means for sensing when said scanning electron beam enters the field of view of said light pen; second threshold detection means for sensing when said electron beam has scanned across the center region of the field of view of said light pen; and means for determining a fixed time interval following each low threshold detection, the position of said light pen being determined by the position of said scanning electron beam at the end of said fixed time interval when a high threshold detection has also been made during said time interval. - View Dependent Claims (19, 20, 21, 22, 23)
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24. Light pen apparatus for use with an interactive display of a computer system, comprising:
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a light pen for contacting the screen of an interactive display and for collecting light from said screen, said light pen having an optical field of view when in contact with said screen which is larger than a single scan line of said display; means for sensing the amplitude of the light collected by said light pen; first threshold detection means responsive to said sensing means for detecting when the amplitude of the light collected by said light pen exceeds a first threshold level; second threshold detection means responsive to said sensing means for detecting when the amplitude of the light collected by said light pen exceeds a second threshold level; means responsive to said second threshold detection means for determining the vertical position of said light pen with respect to said display screen; and means responsive to said first threshold detection means for determining the horizontal position of said light pen with respect to said display screen. - View Dependent Claims (25, 26, 27)
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Specification