Electronic line monitoring system for a tennis court
First Claim
1. A system for use in conjunction with a tennis court to detect shots in which a tennis ball is slightly out of bounds and provide an indication thereof comprising:
- means for establishing a pair of inner and outer substantially parallel reference light beams tracing the entire outer boundary of a tennis court with said outer beam being the out-of-bounds representation point of said boundary when in use, said beams being positioned slightly above the playing surface and spaced from one another a distance such that a tennis ball will not interrupt both beams simultaneously when it strikes the boundary during play;
said establishing means being a dual beam light projector and a plurality of light reflectors, at least a pair of said reflectors being positionable near at least three corners of a tennis court to direct said inner and outer beams along the boundary of a tennis court;
means for intercepting said beams after they have traced said boundary and providing signals representative of the interruption of either of said beams;
logic circuit means coupled to said intercepting means for generating a signal only when said outer beam is momentarily interrupted by a tennis ball during play; and
signalling means coupled to said logic circuit and responsive to said means generating said signal to provide an alarm indicating an out-of-bounds shot.
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Accused Products
Abstract
An optical tennis line sensing system employs a double beam laser for projecting only a pair of collimated beams of light along the entire outer boundary and base lines of a tennis court with one beam positioned on the line slightly above the playing surface and the remaining being positioned slightly outside the lines. A detector circuit including photo multiplier light sensors detects interruptions of the light beam in a timed sequence for generating a signal indicating when a tennis ball is out of bounds. The detector circuit discriminates between momentary interruption of one of the light beams by a tennis ball and interruption of one or both of the light beams by the player'"'"'s foot. Display means coupled to the detector circuit displays only out-of-bounds shots which are marginal and which cannot be accurately called by the line judges. A laser beam and photomultiplier and associated detection and display circuit are also employed at the service lines and along the top of the net to detect fault and let services respectively.
50 Citations
18 Claims
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1. A system for use in conjunction with a tennis court to detect shots in which a tennis ball is slightly out of bounds and provide an indication thereof comprising:
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means for establishing a pair of inner and outer substantially parallel reference light beams tracing the entire outer boundary of a tennis court with said outer beam being the out-of-bounds representation point of said boundary when in use, said beams being positioned slightly above the playing surface and spaced from one another a distance such that a tennis ball will not interrupt both beams simultaneously when it strikes the boundary during play;
said establishing means being a dual beam light projector and a plurality of light reflectors, at least a pair of said reflectors being positionable near at least three corners of a tennis court to direct said inner and outer beams along the boundary of a tennis court;means for intercepting said beams after they have traced said boundary and providing signals representative of the interruption of either of said beams; logic circuit means coupled to said intercepting means for generating a signal only when said outer beam is momentarily interrupted by a tennis ball during play; and signalling means coupled to said logic circuit and responsive to said means generating said signal to provide an alarm indicating an out-of-bounds shot. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A portable boundary line sensing system for a tennis court for detecting out-of-bounds tennis shots comprising:
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projector means positionable rear one corner of a tennis court for providing a pair of substantially parallel collimated beams of light spaced slightly above the playing surface and spaced from one another a distance such that a tennis ball will not interrupt both beams simultaneously, said pair of beams defining an inner beam and an outer beam defining the entire boundary line of a tennis court; reflector means positionable near the remaining corners of a tennis court boundary to reflect said beams from said projector means along the boundary of a tennis court with said outer beam along the out-of-bounds line and the inner beam being spaced therefrom a distance to prevent both said inner and outer beams from being interrupted simultaneously by a tennis ball; light detector means positionable near said one corner to intercept said beams of light after said beams have traced said boundary of a tennis court and for providing first and second signals when said inner and outer beams of light, respectively, are interrupted; and circuit means coupled to said light detector means and responsive to said first and second signals for discriminating between interruption of said light beams by a player'"'"'s foot and a tennis ball and for providing an alarm signal indicating an out-of-bounds shot when said outer light beam is interrupted by a tennis ball during play. - View Dependent Claims (9, 10, 11, 12)
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13. A system for use in conjunction with a tennis court to detect shots in which a tennis ball is slightly out of bounds and provide an indication thereof comprising:
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means for establishing a pair of substantially parallel reference beams of light tracing the entire outer boundary of a tennis court said beams defining inner and outer beams with the outer beam defining the out-of-bounds representation of said boundary, said beams positioned slightly above the playing surface and horizontally spaced from one another such that a tennis ball will not interrupt both beams simultaneously when it strikes said boundary during play; first and second detectors for intercepting said outer and inner beams, respectively, after they have traced said boundary and providing signals representative of the interruption of either of said beams; a first circuit coupled to said first detector for providing a pulse of a first predetermined duration at an output terminal of said first circuit is and initiated when said outer beam is interrupted. a first gate circuit having first and second input terminals and an output terminal, said second input terminal being coupled to said first detector and said first input terminal coupled to said output-terminal of said first circuit to provide a pulse from said output terminal of said first gate initiated at the end of the interruption of said outer beam and terminated at the end of said output pulse of said first predetermined duration; a second circuit coupled to said second detector for providing a pulse of a predetermined duration at an output terminal of said second circuit and initiated when said inner beam is interrupted, said second predetermined duration being greater than said first predetermined duration; a second gate circuit having first and second input terminals and an output terminal, said first input terminal being coupled to said output terminal of said first gate circuit and said second input terminal being coupled to said output terminal of said second circuit to provide a pulse at said output terminal of said second gate only when a pulse from said first gate is applied to only said first input terminal;
of said second gate andcircuit coupled to said output terminal of said second gate circuit and responsive to signals therefrom to develop an alarm indicating an out-of-bounds shot. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification