GAME COURT BOUNDARY INDICATOR SYSTEM

• US 3,774,194 A
• Filed: 01/12/1972
• Issued: 11/20/1973
• Est. Priority Date: 01/12/1972
• Status: Expired due to Term

• Current Assignee: Peter Jokay, Stephen Grill
• Original Assignee: Peter Jokay, Stephen Grill
• Inventors: Jokay, Peter, Grill, Stephen
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/217,325
• Time in Patent Office: 678 Days
• Field of Search: 340/323,258C,285 273/31,29
• US Class Current: 473/467
• CPC Class Codes: A63B 2071/0611 Automatic tennis linesmen, i.e. in-out detectors
• CPC Class Codes: A63B 2209/08 magnetic
• CPC Class Codes: A63B 43/00 Balls with special arrangements
• CPC Class Codes: A63B 71/0605 Decision makers and devices using detection means facilitating arbitration

Abstract

A game court boundary indicator system in which critical zones adjoining the boundary lines have protected and/or concealed sensing means responsive to the proximity of a playing ball having triggering means, said sensing means being unaffected by the presence of the player'"'"''"'"'s body or the tennis racket, and connected to circuit means actuating indicating means.

Claims

1. A playing court boundary indicator system comprising:

a playing court;

a boundary line on said court;

a critical zone adjoining said boundary line;

sensing means in said critical zone;

indicating means;

circuit means associating the sensing means with said indicating means;

a playing ball;

said ball having triggering means;

said triggering means in said ball when in said critical zone affecting said sensing means;

whereby said indicating means is actuated, providing a definite indication index of the position of said ball with respect to said critical zone.

2. A system as claimed in claim 1 in which the triggering means in the ball has a plurality of conductive windings coiled about different axes.

3. A system as claimed in claim 1 having a transmitter of a predetermined frequency, in Which the triggering means in the ball is a tuned circuit corresponding to the frequency of the transmitter.

4. A system as claimed in claim 1 in which the sensing means has an antenna below the surface of the playing court in said critical zone.

5. A system as claimed in claim 1 in which the playing court includes a '"'"''"'"''"'"''"'"'single'"'"''"'"''"'"''"'"' critical zone, and a '"'"''"'"''"'"''"'"'double'"'"''"'"''"'"''"'"' critical zone, each having separate sensing means, and a switch in said circuit means to selectively connect the sensing means of both the '"'"''"'"''"'"''"'"'single'"'"''"'"''"'"''"'"' and '"'"''"'"''"'"''"'"'double'"'"''"'"''"'"''"'"' critical zones to the indicating means in one position of said switch and the sensing means of only the '"'"''"'"''"'"''"'"'double'"'"''"'"''"'"''"'"' critical zone in another position of said switch.

6. A system as claimed in claim 1 in which the triggering means in the ball includes a magnetic material.

7. A system as claimed in claim 1 in which radio frequency energy is fed into said sensing means.

8. A system as claimed in claim 1 in which the sensing means is connected to one portion of a balanced bridge circuit, and the indicating means is connected to the remaining position of the said bridge circuit.

9. A system as claimed in claim 1 in which the sensing means radiates two different radio frequencies, and the triggering means in the ball is a mixer circuit.