| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a ball for a ball game advantageous to appropriately and accurately measure a behavior of the ball for the ball game. <P>SOLUTION: A hardball baseball ball 2 includes: a core layer 20, an intermediate layer 22, and a cover layer 24. The intermediate layer 22 is formed into a spherical body 26 by winding, around the core layer 20, a thread having a radio wave transmission property that allows the transmission of radio waves. The cover layer 24 covers the intermediate layer 22 and is formed of a material having the radio wave transmission property. The hardball baseball ball 2 further includes a reflection part 28. The reflection part 28 is formed on a spherical surface with the center of the spherical body 26 as a center, and has radio wave reflectivity. The reflection part 28 is constituted using the thread that forms the intermediate layer 22. The radio wave reflectivity is imparted to at least a part of the thread forming the intermediate layer 22, and the reflection part 28 is constituted of the thread to which the radio wave reflectivity is imparted. <P>COPYRIGHT: (C)2013,JPO&INPIT |
