Games using tangible projectile – Golf – Club or club support
Reexamination Certificate
1997-10-29
2001-11-27
Chapman, Jeanette (Department: 3711)
Games using tangible projectile
Golf
Club or club support
C473S319000
Reexamination Certificate
active
06322458
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a golf club shaft.
In the conventional golf club shaft, the flexural rigidity is gradually increased from the front end portion to the grip portion of the shaft, so that the flexural rigidity of the shaft end on the user's side becomes the maximum, that is, the flexural rigidity of the rear end of the grip portion becomes the maximum. According to the golf club shaft constructed as described above, it is impossible to provide a desired flexibility by which the user can be satisfied.
In order to improve the above disadvantages, Japanese Unexamined Patent Publication No. 7-213658 discloses a golf club shaft having a portion, the flexural rigidity of which is very low. However, in the above golf club shaft, the flexural rigidity of one portion of the shaft is simply reduced, and no consideration is given to the flexural rigidity of the entire shaft. Therefore, it is impossible to satisfy various requirements of the user such as a handling property, handling stability, directional stability and soft ball hitting feeling.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the above circumstances. It is an object of the present invention to provide a golf club shaft having a characteristic by which various user's requirements can be satisfied.
The first aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a portion, the flexural rigidity of which is the maximum, is arranged in the pipe-shaped body on the front end portion side of the grip portion.
The second aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a first inflection point is formed in the pipe-shaped body, at which the flexural rigidity of the pipe-shaped body is changed from the positive to the negative when it comes from the front end portion side to the grip portion side, a second inflection point is formed in the pipe-shaped body, at which the flexural rigidity of the pipe-shaped body is changed from the negative to the positive when it comes from the front end portion side to the grip portion side, and the flexural rigidity at the first inflection point is higher than the flexural rigidity at the second inflection point.
The third aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a portion, the flexural rigidity of which is changed sharply, is arranged in the pipe-shaped body on the front end portion side of the grip portion, and the maximum flexural rigidity at the portion, the flexural rigidity of which is changed sharply, is approximate to the flexural rigidity of the grip portion.
The fourth aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a distribution of the flexural rigidity of the pipe-shaped body includes at least three inflection points at which a ratio of change in the flexural rigidity from the front end portion side is decreased and a ratio of change in the flexural rigidity from the front end potion side is increased.
The fifth aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein the crush rigidity of the pipe-shaped body from the front end portion to the grip portion is substantially constant, and the crush rigidity of the grip portion is increased toward the grip end portion.
The sixth aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a region in which the flexural rigidity is decreased from the front end portion to the grip portion is formed in the front end portion of the pipe-shaped body, a region in which the flexural rigidity is sharply increased is formed between the front end portion and the grip portion, and the flexural rigidity in the grip portion is substantially constant.
The seventh aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a region in which the flexural rigidity is gradually increased from the front end portion to the grip portion is formed between the front end portion and the grip portion of the pipe-shaped body, and a region in which the flexural rigidity is sharply increased from the front end portion to the grip portion is formed between the front end portion and the grip portion.
The eighth aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein a ratio EI
MAX
/EI
MIN
of the maximum flexural rigidity EI
MAX
to the minimum flexural rigidity EI
MIN
of the pipe-shaped body is not lower than 4, a portion corresponding to the minimum flexural rigidity EI
MIN
is located on the front end portion side, and a portion corresponding to the maximum flexural rigidity EI
MAX
is located on the grip portion side.
The ninth aspect of the present invention is to provide a golf club shaft constructed by a pipe-shaped body in which a sheet of reinforced fiber prepreg impregnated with synthetic resin is rolled, comprising: a front end portion to which a club head is attached; and a grip portion arranged on the opposite side to the front end portion, wherein the torsional rigidity in a portion between the front end portion and the middle of the shaft is decreased from the front end portion to the middle of the shaft.
REFERENCES:
patent: 5551691 (1996-09-01), Harada
patent: 5681226 (1997-10-01), Chambers
patent: 7-213658 (1995-08-01), None
Kusumoto Harunobu
Matsuo Atsushi
Saitoh Satoshi
Blau Stephen L.
Chapman Jeanette
Daiwa Seiko Inc.
Liniak Berenato Longacre & White
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