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Line fault detector

  • US 4,664,376 A
  • Filed: 06/30/1983
  • Issued: 05/12/1987
  • Est. Priority Date: 12/03/1981
  • Status: Expired due to Fees
First Claim
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1. Detection apparatus for sensing the proximity of a tennis-type ball to a tennis-type court boundary, the ball including a metallic or ferromagnetic substance, said apparatus comprising:

  • a plurality of first coils disposed each adjacent another longitudinally along and parallel to a single predetermined line of the boundary,a plurality of second coils disposed each adjacent another longitudinally along and parallel to the same single predetermined line of the boundary and substantially parallel to said first coils and spaced immediately laterally adjacent thereto by a distance no greater than about 20 cm.,a plurality of oscillators, one associated with each coil for generating an associated oscillating field in the respective coil vicinity,a plurality of detectors, one associated with each oscillator and responsive to a disturbance, if any, of the associated oscillating field by the metallic or ferromagnetic material of the ball passing through said field to issue a detection signal,identifying means for issuing a signal identifying which one, if any, of said detectors has issued a detection signal, said identifying means including means for repeatedly separately scanning said detectors associated with said first and second plurality of coils in a sequence to issue a signal indicative of the location of any detector which has issued a detection signal,whereby the proximity of the ball to the boundary may be detected.

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