Arbitration of tennis by change of colors

Abstract

Disclosed herein is apparatus to precisely determine if a tennis ball hits in or out of the tennis court area. A pressure sensitive layered material which changes colors upon the tennis ball striking it is placed outside the tennis court bounderies and gives an indication whenever the ball strikes out of bounds. The material returns to its original color a short time later.

I claim: 
     
       1. A tennis ball contact indicator in combination with a tennis court comprising: a thin rectilinear conduit having a transparent and flexible top layer and a bottom layer of one color;   said top layer including a tear and wear resistant material in the form of a rectilinear line;   a .[.high density.]. fluid having a color different from said one color and being flowable upon movement of said top layer;   said top layer and bottom layer being separated .[.by one millimeter or more.].; and   said conduit being affixed to said tennis court to define the boundary thereof and said top layer being movable towards said bottom layer to momentarily displace said fluid and expose said one color upon impact of a tennis ball with said top layer to indicate out of bounds of a tennis ball during play.