Patent Publication Number:
US 6416426 B1Title:
Thermoplastic polyurethane elastomers
January 20, 2000Priority Date:
March 3, 1999Inventor(s):
Atsushi Nakamura, Hisashi Yamagishi, Takashi Maruko
Original Assignee / Applicant(s):
Bridgestone Sports Co., Ltd.
Link to Patent: US6416426B1
The present invention claims a dimpled golf ball having excellent controllability and improved flight performance, wherein the cover is formed of thermoplastic polyurethane elastomer. According to the disclosure in this publication, when a golf ball is manufactured such that the ratio of effective contact area to apparent contact area ranges from 0.40 to 0.60 and the dimple surface coverage (the percent of the ball's surface covered by the dimples formed thereon) is at least 71%, not only spin and control characteristics are improved, but also flight performance is enhanced. The publication further discloses a method for ascertaining the effective contact area and apparent contact area of the golf ball of this invention. The said method involves affixing a pressure-sensitive paper, such as Fujifilm Prescale®, to a titanium plate having a weight of 220 g which is shaped as a disk having a diameter of 9 cm and a thickness of 0.8 cm; and shooting the golf ball with an air cannon against the titanium plate at an initial velocity of 50 m/s. An image of the area of contact by the ball is impressed on the surface of the paper. The image formed on the pressure-sensitive paper is then scanned and uploaded to a computer. Because the normally round dimples are recessed, areas where the surface of ball does not actually contact the plate face (the white areas) are scattered over the image. The image is then peripherally bounded or “trimmed” to give an approximately circular image. The interior of this trimmed image is then completely blacked in, giving the image used to measure the apparent contact area. The effective contact area and the apparent contact area can then be computed using relevant computer software. The effective contact area is calculated by substracting the area of the dimpled recesses which do not experience pressure (the white areas) from the apparent contact area. Similarly, dimple surface coverage can also be calculated.