Golf club shaft

• US 6,213,888 B1
• Filed: 02/18/1999
• Issued: 04/10/2001
• Est. Priority Date: 09/07/1998
• Status: Expired due to Fees

• Current Assignee: NHK Spring Company Limited
• Original Assignee: Nippon Shaft Co., Ltd. (NHK Spring Company Limited)
• Inventors: Shimohira, Katsumi, Watari, Makoto, Yagita, Atsushi, Kawaguchi, Masatake
• Primary Examiner(s): Chapman, Jeanette
• Assistant Examiner(s): BLAU, STEPHEN LUTHER
• Application Number:
  US09/252,446
• Time in Patent Office: 782 Days
• Field of Search: 473/223, 473/409, 73/650.3, 736/50, 737/63, 737/67, 738/47, 738/49
• US Class Current: 473/223
• CPC Class Codes: A63B 2209/00 Characteristics of used materials
• CPC Class Codes: A63B 2220/24 Angular displacement
• CPC Class Codes: A63B 2220/51 Force
• CPC Class Codes: A63B 2220/54 Torque
• CPC Class Codes: A63B 24/0003 Analysing the course of a movement or motion sequences during an exercise or trainings sequence, e.g. swing for golf or tennis
• CPC Class Codes: A63B 53/10 Non-metallic shafts
• CPC Class Codes: A63B 60/06 Handles
• CPC Class Codes: A63B 60/08 characterised by the material
• CPC Class Codes: A63B 60/10 with means for indicating correct holding positions A63B60/12 takes precedence
• CPC Class Codes: A63B 60/42 Devices for measuring, verifying, correcting or customising the inherent characteristics of golf clubs, bats, rackets or the like, e.g. measuring the maximum torque a batting shaft can withstand
• CPC Class Codes: A63B 69/3632 Clubs or attachments on clubs, e.g. for measuring, aligning A63B69/3614 takes precedence; clubs for swinging exercises in general A63B15/00
• CPC Class Codes: A63B 71/06 Indicating or scoring devices for games or players , or for other sports activities
• CPC Class Codes: G01N 3/20 by applying steady bending forces G01N3/26, G01N3/28 take precedence
• CPC Class Codes: G01N 33/008 Sport articles, e.g. balls, skis or rackets

Abstract

A golf club shaft includes a first strain gauge attached to a first side of the shaft facing the striking direction, a second strain gauge attached to a second side of the shaft facing the address direction at right-angles to the striking direction, and a third strain gauge which is capable of measuring the twist of the shaft. Detection signals from the strain gauges are used to classify a shaft into four types according to the swing type of a golfer in accordance with at least torque or kick point.

Claims

1. A method of classifying a golf club shaft, wherein the golf club shaft comprises:

a first strain gauge attached to a first side of said shaft facing a striking direction configured to detect a strain H in the striking direction of said shaft;

a second strain gauge attached to a second side of said shaft facing an address direction at right-angles to the striking direction configured to detect a strain V in the address direction of said shaft;

a third strain gauge configured to measure a twist of said shaft;

said shaft comprising;

detecting signals from the first strain gauge, the second strain gauge and the third strain gauge;

generating an H-V graph on rectangular coordinates with the strain H in the striking direction and the strain in the addressing direction being combined; and

classifying the shaft into four types, an I-type shaft, a P-type shaft, a D-type shaft and a J-type shaft, each having a torque, according to the H-V graph associate with a swing of a golfer;

wherein the torque of said I-type shaft is between 5.6° and

7.2°

, the torque of said P-type shaft is between 4.6° and

5.0°

, the torque of said D-type shaft is between 4.0° and

4.4°

, and the torque of said J-type shaft is between 3.4° and

3.8°

.

2. A method classifying a golf club shaft according to claim 1, wherein said kick point is increased gradually in order from said I-type shaft through said P-type shaft and said D-type shaft to said J-type shaft.

3. A method of classifying a golf club shaft according to claim 1, wherein said shaft is manufactured from carbon fiber reinforced plastics or glass fiber reinforced plastics.

4. The method of claim 1, wherein the torque of the I-type shaft is 5.8°

.

5. The method of claim 1, wherein the torque of the P-type shaft is 4.8°

.

6. The method of claim 1, wherein the torque of the D-type shaft is 4.2°

.

7. The method of claim 1, wherein the torque of the J-type shaft is 3.6°

.

8. A method of classifying a golf club shaft, wherein the golf club shaft comprises:

a first strain gauge attached to a first side of said shaft facing a striking direction configured to detect a strain H in the striking direction of said shaft;

a second strain gauge attached to a second side of said shaft facing an address direction at right-angles to the striking direction configured to detect a strain V in the address direction of said shaft;

a third strain gauge configured to measure a twist of said shaft;

said method comprising;

detecting signals from the first strain gauge, the second strain gauge and the third strain gauge;

generating an H-V graph on rectangular coordinates with the strain H in the striking direction and the strain in the addressing direction being combined; and

classifying the shaft into four types, an I-type shaft, a P-type shaft, a D-type shaft and a J-type shaft, each having a kick point, according to the H-V graph associated with a golfer;

wherein the kick point of said I-type shaft is between 38% and 42%, the kick point of said P-type shaft is between 40% and 43%, the kick point of said D-type shaft is between 42% and 45%, and the kick point of said J-type shaft is between 44% and 47%.

9. A method of classifying a golf club shaft according to claim 8, wherein said torque is reduced gradually in order from said I-type shaft through said P-type shaft and said D-type shaft to said J-type shaft.

10. The method of claim 8, wherein the kick point of the I-type shaft is 40%.

11. The method of claim 8, wherein the kick point of the P-type shaft is 41.5%.

12. The method of claim 8, wherein the kick point of the D-type shaft is 43%.

13. The method of claim 8, wherein the kick point of the J-type shaft is 44.5%.

14. A method of classifying a golf club shaft according to claim 8, wherein said shaft is manufactured from carbon fiber reinforced plastics or glass fiber reinforced plastics.

15. A method of classifying a golf club shaft, wherein the golf club shaft comprises:

a first strain gauge attached to a first side of said shaft facing a striking direction configured to detect a strain H in the striking direction of said shaft;

a second strain gauge attached to a second side of said shaft facing an address direction at right-angles to the striking direction configured to detect a strain V in the address direction of said shaft;

a third strain gauge configured to measure a twist of said shaft;

said method comprising;

detecting signals from the first strain gauge, the second strain gauge and the third strain gauge;

generating an H-V graph on rectangular coordinates with the strain H in the striking direction and the strain in the addressing direction being combined; and

classifying the shaft into four types, an I-type shaft, a P-type shaft, a D-type shaft and a J-type shaft, each having a torque and a kick point, according to the H-V graph associated with a golfer;

wherein the torque of said I-type shaft is between 5.6° and

7.2°

, the torque of said P-type shaft is between 4.6° and

5.0°

, the torque of said D-type shaft is between 4.0° and

4.4°

, and the torque of said J-type shaft is between 3.4° and

3.8°

, and

the kick point of said I-type shaft is between 38% and 42%, the kick point of said P-type shaft is between 40% and 43%, the kick point of said D-type shaft is between 42% and 45%, and a kick point of said J-type shaft is between 44% and 47%.

16. A method of classifying a golf club shaft according to claim 15, wherein said shaft is manufactured from carbon fiber reinforced plastics or glass fiber reinforced plastics.

17. The method of claim 15, wherein the torque of the I-type shaft is 5.8°

.

18. The method of claim 15, wherein the torque of the P-type shaft is 4.8°

.

19. The method of claim 15, wherein the torque of the D-type shaft is 4.2°

.

20. The method of claim 15, wherein the torque of the J-type shaft is 3.6°

.

21. The method of claim 15, wherein the kick point of the I-type shaft is 40%.

22. The method of claim 15, wherein the kick point of the P-type shaft is 41.5%.

23. The method of claim 15, wherein the kick point of the D-type shaft is 43%.

24. The method of claim 15, wherein the kick point of the J-type shaft is 44.5%.