Abstract: This invention provides a hollow golf club head including a fixing member which includes a shaft body formed with a threaded portion at one end, and a head portion at the other end of the shaft body, a viscoelastic body having an opening through which the shaft body extends, a recess portion formed in a circumferential wall of the golf club head and in which the viscoelastic body is disposed, and a screw hole formed in a bottom portion of the recess portion and threadably engages with the threaded portion. The viscoelastic body is fixed between the head portion and the bottom portion by threadably engaging the threaded portion with the screw hole.

Abstract: According to this invention, there is provided a method of manufacturing a golf cub head having a plurality of score lines on the face. The method of this invention includes the first forming step of forming grooves for the score lines on the face, and the second forming step of forming notches uniformly along the longitudinal direction of the grooves by cutting into the edges of the grooves formed in the first forming step, the notches having first side surfaces leading to the face and second side surfaces leading to the first side surfaces and side surfaces of the grooves.

Abstract: This invention provides a wood type golf club including a shaft, a grip at one end of the shaft, and a head at the other end of the shaft, wherein a mass m (g) of the golf club and a length L (cm) from a grip side end of the golf club to a barycentric position of the golf club satisfy m×L?2.56×104 (g·cm) and m×L2?2.300×106 (g·cm2).

Abstract: According to this invention, there is provided a method of manufacturing a golf cub head having a plurality of score lines on the face. The method of this invention includes the first forming step of forming grooves for the score lines on the face, and the second forming step of forming, uniformly along the longitudinal direction of the grooves by cutting into the edges of the grooves formed in the first forming step, notches having an arcuate cross-sectional shape.

Abstract: According to this invention, there is provided a method of manufacturing a golf cub head having a plurality of score lines on the face. The method of this invention includes the first forming step of forming grooves for the score lines on the face, and the second forming step of forming flat surfaces inclined with respect to the face by cutting into the edges of the grooves formed in the first forming step.

Abstract: This invention provides a wood type golf club including a shaft, a grip at one end of the shaft, and a head at the other end of the shaft, wherein a mass m (g) of the golf club and a length L (cm) from a grip side end of the golf club to a barycentric position of the golf club satisfy m×L2>2.280×106 (g·cm2) and m×L2>140×m×L?(5.95×m?417)×103.

Abstract: A golf ball movement measuring apparatus includes: a camera for taking a plurality of images of a golf ball hit by a golf club; a dark-colored background material which is disposed so as to configure a background of the golf ball in the images; and a processing unit to which the images are transmitted from the camera, the processing unit masking a background portion excepting the dark-colored background material in the images in black through image processing, and the processing unit analyzing a movement of the golf ball hit by the golf club.

Abstract: An iron set has plural iron golf clubs, in which loft angles of heads are larger as the number is increased, each golf club including the head having a sole that includes a front sole on a front side and a rear sole adjacent to the front sole. A bounce angle ?2 of the rear sole is smaller than a bounce angle ?1 of the front sole, and a width L2 of the rear sole in a front-rear direction is greater than or equal to a width L1 of the front sole in the front-rear direction. The width L1 is from 5 to 12 mm in any of the golf clubs, the bounce angle of the front sole for the number n club is greater than or equal to the bounce angle of the front sole for the number (n-1) club and greater than the bounce angle of the front sole for the number (n-2) club.

Abstract: This invention provides a wood type golf club including a shaft, a grip at one end of the shaft, and a head at the other end of the shaft, wherein a mass m (g) of the golf club and a length L (cm) from a grip side end of the golf club to a barycentric position of the golf club satisfy m×L=2.55×104 (g·cm) and m×L2=2.322×106 (g·cm2), and a barycentric position of the shaft is at 48.3% a total length of the shaft from a head side end of the shaft.

Abstract: This invention provides a wood golf club head having a loft angle of not more than 15°. In this golf club head, a progression length FP from a leading edge of a face to an axis line of a shaft axis and a horizontal length VZG from the leading edge of the face to a center of gravity of the head in a depth direction satisfy the following expression; ?2<VZG?2×FP<2.

Abstract: This invention provides a wood type golf club including a shaft, a grip at one end of the shaft, and a head at the other end of the shaft, wherein a mass m (g) of the golf club and a length L (cm) from a grip side end of the golf club to a barycentric position of the golf club satisfy m×L?2.60×104 (g·cm) and m×L2?2.270×106 (g·cm2), and the barycentric position of the shaft is within a range of 48.5% the total length of the shaft from a head side end of the shaft.

Abstract: This invention provides a plurality of grooves formed on a face of the golf club head. Each of a pair of side surfaces of each of the grooves has a first surface leading to the face and a second surface leading to the first surface in the depth direction of the groove. A first angle between the first surfaces of each of said pair of the side surfaces is larger than a second angle between the second surfaces of each of the said pair of the side surfaces. Edges of the groove are rounded. A width W (mm) of the groove measured including the rounded edges, a width Ws (mm) between the grooves adjacent one another, a width Wr (mm) of the groove measured based on the 30 degrees measurement rule and a cross section area S (mm2) of the groove satisfy the following expressions; W/Ws×100?40 (%), S/(Ws×0.5)×100?70 (%).

Abstract: A wood club head having a loft angle of not less than 13° is provided. The hosel length is not less than 20 mm. The face progression is set to fall within a range of 12 mm to 16 mm (both exclusive). The barycenter depth is set to fall within a range of 20 mm to 25 mm (both exclusive).

Abstract: The present invention provides a golf club head comprising, a face, a plurality of score line grooves formed in the face, traces formed in the face by milling; and a pair of side surfaces of the score line groove including a first surface that is contiguous with the face and a second surface that is contiguous with the first surface in the depth direction of the score line groove. A first angle that is formed by each first surface of the pair of side surfaces is larger than a second angle that is formed by each second surface of the pair of surfaces. The face in which the traces are formed has the arithmetic mean deviation of the profile (Ra) of not less than 4.00 ?m.

Abstract: A golf club head of this invention includes a face and a plurality of striations formed on the face by milling. A pitch P in the arrangement direction of the plurality of striations satisfies 300 ?m?P?600 ?m. The surface roughness of a region in the face with the striations satisfies in the maximum height of the profile Ry, 15 ?m?Ry?0.005×P+15.7 ?m.

Abstract: A golf club head of this invention includes a face, a plurality of score line grooves formed on the face, and a plurality of striations formed on the face. The angle formed by an arrangement direction of the plurality of striations and the score line grooves is between 40 degrees and 70 degrees, inclusive, as viewed clockwise from a toe side end of the score line grooves.

Abstract: A putter head includes: a face; a first group of grooves which are mutually-parallel grooves; and a second group of grooves which differ in depth from the first group of grooves, wherein the face includes the first group of grooves and the second group of grooves.