Patent Description:
The present disclosure relates to a golf club head.

There has been known a golf club head including a crown. The crown is usually formed of a convex curved surface that is smooth and continuous as a whole. On the other hand, <CIT> discloses a golf club head having a step on its crown. This step contributes to lowering the position of a back part of the head and lowering the position of the center of gravity of the head.

Documents <CIT> and <CIT> disclose a golf club head having a crown atypically-shaped portion and a crown rib.

A problem solved by the invention is to provide a golf club head that has an improved sound at impact.

The problem is solved by a golf club head having the features defined in claim <NUM>.

The shape of a crown can influence the characteristics of a head. The inventor of the present disclosure considered providing a projection or a recess on a crown that is otherwise usually smooth and continuous. This projection or recess can also influence the aerodynamic characteristic of a head, for example. This projection or recess also can influence the position of the center of gravity of a head, for example. The presence of a projection or a recess on a crown can increase the degree of freedom in design of a head.

The inventor, however, has found that such a projection or recess also affects the sound of a golf club head produced when striking a golf ball (hereinafter, this sound is also simply referred to as sound at impact). The inventor has also found that a projection or a recess provided on a crown lowers the pitch of sound at impact and reduces the degree of freedom in design of sound at impact.

One of the objects of the present disclosure is to provide a golf club head that has a projection or a recess on its crown and is capable of improving and adjusting sound at impact.

In one aspect, a golf club head of the present disclosure is hollow. The golf club head includes a face portion that forms a striking face, a crown portion that forms a crown outer surface and a crown inner surface, a sole portion that forms a sole outer surface and a sole inner surface, and a hosel portion. The crown portion includes a crown atypically-shaped portion and a crown rib that is disposed on the crown inner surface. The crown atypically-shaped portion is a crown projection that forms a projection on the crown outer surface while forming a recess on the crown inner surface, or a crown recess that forms a recess on the crown outer surface while forming a projection on the crown inner surface. The crown rib is positioned on a crown center side relative to a center of the crown atypically-shaped portion. The crown rib is disposed on the crown center side relative to an entirety of the crown atypically-shaped portion. The crown rib is located apart from the crown atypically-shaped portion.

Hereinafter, the present disclosure will be described in detail according to the preferred embodiments with appropriate references to the accompanying drawings.

In the present disclosure, a reference state, a reference perpendicular plane, a toe-heel direction, a face-back direction, an up-down direction, and a face center are defined as follows.

The reference state is a state where a head is placed at a predetermined lie angle on a ground plane HP. As shown in <FIG>, in the reference state, a shaft axis line Z lies on (is contained in) a plane VP that is perpendicular to the ground plane HP. The shaft axis line Z is the center line of a shaft. The shaft axis line Z usually coincides with the center line of a hosel hole (shaft hole). The plane VP is defined as the reference perpendicular plane. The predetermined lie angle is shown in a product catalog, for example.

In the reference state, a face angle is <NUM>°. That is, in a planar view of a head as viewed from above, a line normal to its striking face at the face center is set to be perpendicular to the toe-heel direction. The definitions of the face center and the toe-heel direction are as explained below.

In the present disclosure, the toe-heel direction is the direction of an intersection line NL between the reference perpendicular plane VP and the ground plane HP (see <FIG>).

In the present disclosure, the face-back direction is a direction that is perpendicular to the toe-heel direction and is parallel to the ground plane HP. A face side in the face-back direction is also simply referred to as "face side". A back side in the face-back direction is also simply referred to as "back side".

In the present disclosure, the up-down direction is a direction that is perpendicular to the toe-heel direction and is perpendicular to the face-back direction. In other words, the up-down direction in the present disclosure is a direction perpendicular to the ground plane HP.

In the present disclosure, the face center is determined in the following manner. First, a point Pr is selected roughly at the center of a striking face in the up-down direction and the toe-heel direction. Next, a plane that passes through the point Pr, extends in the direction of a line normal to the striking face at the point Pr, and is parallel to the toe-heel direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Px of this intersection line is determined. Next, a plane that passes through the midpoint Px, extends in the direction of a line normal to the striking face at the midpoint Px, and is parallel to the up-down direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Py of this intersection line is determined. Next, a plane that passes through the midpoint Py, extends in the direction of a line normal to the striking face at the midpoint Py, and is parallel to the toe-heel direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Px of this intersection line is newly determined. Next, a plane that passes through this newly-determined midpoint Px, extends in the direction of a line normal to the striking face at this midpoint Px, and is parallel to the up-down direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Py of this intersection line is newly determined. By repeating the above-described steps, points Px and Py are sequentially determined. In the course of repeating these steps, when the distance between a newly-determined midpoint Py and a midpoint Py determined in the immediately preceding step first becomes less than or equal to <NUM>, the newly-determined midpoint Py (the midpoint Py determined last) is defined as the face center.

<FIG> is an overall view of a golf club <NUM> that includes a head <NUM> according to a first embodiment of the present disclosure. <FIG> is a front view of the head <NUM>. <FIG> shows the head <NUM> which is in the reference state as viewed from the face side. <FIG> is a plan view of the head <NUM> as viewed from a crown side. <FIG> is a perspective view of the head <NUM> as viewed from a heel-back side.

As shown in <FIG>, the golf club <NUM> includes the golf club head <NUM>, a shaft <NUM>, and a grip <NUM>. The shaft <NUM> includes a tip end Tp and a butt end Bt. The head <NUM> is attached to a tip end portion of the shaft <NUM>. The grip <NUM> is attached to a butt end portion of the shaft <NUM>.

The golf club <NUM> is a driver (No.<NUM> wood). The head <NUM> is a driver head. Typically, the club as a driver has a length of greater than or equal to <NUM> centimeters (<NUM> inches). Preferably, the golf club <NUM> is a wood type golf club.

The shaft <NUM> is in a tubular form. The shaft <NUM> is hollow. The material of the shaft <NUM> is a carbon fiber reinforced resin. From the viewpoint of weight reduction, a carbon fiber reinforced resin is preferable as a material for the shaft <NUM>. The shaft <NUM> is a so-called carbon shaft. Preferably, the shaft <NUM> is formed with a cured prepreg sheet. In the prepreg sheet, fibers are substantially oriented in one direction. Such a prepreg in which fibers are substantially oriented in one direction is also referred to as UD prepreg. "UD" is an abbreviation of "unidirectional". A prepreg other than the UD prepreg may be used. For example, fibers contained in the prepreg sheet may be woven. The shaft <NUM> may include a metal wire. The material of the shaft <NUM> is not limited, and may be a metal, for example.

The grip <NUM> is a part that a golfer grips during a swing. Examples of the material of the grip <NUM> include rubber compositions and resin compositions. The rubber composition for the grip <NUM> may contain air bubbles.

The head <NUM> has a hollow structure. In the present embodiment, the head <NUM> is a wood type head. The head <NUM> may be a hybrid type head. The head <NUM> may be an iron type head. The head <NUM> may be a putter type head. Examples of a preferable material for the head <NUM> include metals and fiber reinforced plastics. Examples of the metals include titanium alloys, pure titanium, stainless steel, maraging steel, and soft iron. Examples of the fiber reinforced plastics include carbon fiber reinforced plastics. The head <NUM> may be a composite head including a portion made of a metal and a portion made of a fiber reinforced plastic.

As shown in <FIG>, the head <NUM> includes a face portion <NUM>, a crown portion <NUM>, a sole portion <NUM> and a hosel portion <NUM>. The face portion <NUM> forms a striking face 10a and a face inner surface (not shown in the drawings). The striking face 10a is the outer surface of the face portion <NUM>. The striking face 10a is also simply referred to as a face or a face surface. The crown portion <NUM> forms a crown outer surface 12a and a crown inner surface 12b. The sole portion <NUM> forms a sole outer surface 14a and a sole inner surface 14b. The head <NUM> is hollow. That is, the head <NUM> includes a hollow portion k1. The face inner surface, the crown inner surface 12b, and the sole inner surface 14b face the hollow portion k1 of the head <NUM>. The crown inner surface 12b, the sole inner surface 14b and the hollow portion k1 are shown in cross-sectional views (<FIG> and <FIG>) of the head <NUM>, which are detailed below.

The striking face 10a has a face center Fc as defined above.

The crown portion <NUM> includes a crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is a portion that forms a hollow projection or a hollow recess. In the present embodiment, the crown atypically-shaped portion <NUM> is a crown projection <NUM> that forms a projection on the crown outer surface 12a and forms a recess on the crown inner surface 12b. The crown atypically-shaped portion <NUM> forms a projection on the crown portion <NUM> when viewed from outside the head <NUM>, and thus is also referred to as the crown projection <NUM>.

In the front view (<FIG>) of the head <NUM> as viewed from the face side, the crown atypically-shaped portion <NUM> is not viewable. In the front view (<FIG>) of the head <NUM> as viewed from the face side, the crown atypically-shaped portion <NUM> does not constitute any part of an outer contour line CL1 of the head <NUM>. The crown atypically-shaped portion <NUM> is the crown projection <NUM>, and thus can raise the position of the center of gravity of the head <NUM>. The crown projection <NUM> is preferably formed at a low position from the viewpoint of not raising the position of the center of gravity of the head while providing the crown projection <NUM> for obtaining aerodynamic characteristics. In such a case, the crown projection <NUM> can be provided at a position that is not viewable in the front view of the head <NUM>.

The entirety of the crown atypically-shaped portion <NUM> is provided in the crown portion <NUM>. As shown in <FIG>, the head <NUM> has an outer contour line CL2 in the planar view. The outer contour line CL2 includes a contour line CL4 of the crown portion <NUM> in the planar view. Excepting contour lines of the face portion <NUM> and the hosel portion <NUM>, the outer contour line CL2 coincides with the contour line CL4. As shown in <FIG>, the crown atypically-shaped portion <NUM> does not reach the contour line CL4. The crown atypically-shaped portion <NUM> does not extend to other portions than the crown portion <NUM>.

The contour line CL4 of the crown portion <NUM> includes a contour line CL5 positioned on the face side. In a longitudinal cross section (longitudinal cross section means a cross section taken along the face-back direction) of the outer surface of the head <NUM>, the radius of curvature of the contour line of the head outer surface in the longitudinal cross section (hereinafter, the contour line in the longitudinal cross section is also referred to as a longitudinal cross-sectional contour line) is sequentially observed from the center of the crown outer surface 12a toward the face portion <NUM>, and a portion where the radius of curvature becomes less than or equal to <NUM> for the first time is specified. In this portion, a point located at the centermost position of the crown outer surface 12a can be a point constituting the contour line CL5. This point can be specified at each position in the toe-heel direction.

The plan view of the head <NUM> is a projected figure obtained by projecting the head which is in the reference state onto a plane parallel to the ground plane HP. In the present disclosure, the plan view (<FIG>) of the head <NUM> is also referred to as a planar view.

In the planar view, the crown atypically-shaped portion <NUM> may reach the contour line CL4 of the crown portion <NUM>. The crown atypically-shaped portion <NUM> may form a part of the contour line CL4. The crown atypically-shaped portion <NUM> may extend into other portion(s) other than the crown outer surface 12a. For example, the crown atypically-shaped portion <NUM> may extend from the crown portion <NUM> into the sole portion <NUM>. When the head <NUM> includes a side portion (skirt portion), the crown atypically-shaped portion <NUM> may extend from the crown portion <NUM> into the side portion.

The crown outer surface 12a includes a base surface b1. Of the crown outer surface 12a, a portion in which the crown atypically-shaped portion <NUM> is not present is formed by the base surface b1. The base surface b1 is a convex curved surface that is smooth and continuous. The convex curved surface is a curved surface that is convex toward the outside of the head <NUM>. As shown in <FIG>, the base surface b1 belonging to the crown outer surface 12a includes a geometric center EC of the head <NUM> in the plan view. The geometric center EC is the geometric center of a figure indicated by the outer contour line CL2.

The crown portion <NUM> includes a crown center RC. The crown center RC can be determined based on the geometric center EC. As shown in <FIG>, a frontmost point (face-most point) T1 of the head <NUM> and an uppermost point T2 of the face surface 10a are determined in the cross-sectional contour line (longitudinal cross-sectional contour line) of the outer surface of the head <NUM> in a longitudinal cross section V1 that passes through the geometric center EC. The radius of curvature of the longitudinal cross-sectional contour line is sequentially observed from the center of the face surface 10a toward the crown portion <NUM>, and a portion where the radius of curvature becomes less than or equal to <NUM> for the first time is specified. In this portion, a point located on the centermost position of the face surface 10a can be the uppermost point T2. A distance between the frontmost point T1 and the uppermost point T2 in the face-back direction is denoted by Da. In the plan view of the head <NUM>, a point obtained by moving the geometric center EC toward the back side by half of Da is defined as the crown center RC. Hereinafter, a direction toward the crown center RC and a position closer to the crown center RC is referred to as a crown center side.

<FIG> shows a cross-sectional contour line of the outer surface of the head <NUM> in a cross-sectional view taken along line A-A in <FIG>. <FIG> shows a cross-sectional contour line of the outer surface of the head <NUM> in a cross-sectional view taken along line B-B in <FIG>. <FIG> shows a cross-sectional contour line of the outer surface of the head <NUM> in a cross-sectional view taken along line C-C in <FIG>. <FIG> shows a cross-sectional contour line of the outer surface of the head <NUM> in a cross-sectional view taken along line D-D in <FIG>. <FIG> each include the cross-sectional contour line of the crown outer surface 12a.

The crown atypically-shaped portion <NUM> includes a contour line CL20, an upper surface <NUM>, and a sidewall surface <NUM> (see <FIG>). The contour line CL20 is the contour line of the crown atypically-shaped portion <NUM> on the crown outer surface 12a. The contour line CL20 is a boundary line between the base surface b1 and the crown atypically-shaped portion <NUM>. In the planar view, the contour line CL20 of the crown atypically-shaped portion <NUM> has a substantially quadrilateral shape (substantially trapezoidal shape) having four sides. In the present disclosure, the word "substantially" means that a shape in question may have a curved side(s) (not straight side(s)) and/or a rounded corner(s). As described above, in the planar view, the side(s) of the crown atypically-shaped portion <NUM> may be bent. In the planar view, the radius of curvature (allowable radius of curvature) of the curved side(s) is preferably greater than or equal to <NUM>, more preferably greater than or equal to <NUM>, and still more preferably greater than or equal to <NUM>. Of course, each side may be a straight line in the planar view. When a side is a curved line, a point at which the radius of curvature becomes smaller than the allowable radius of curvature for the first time can be the end of the side. In the planar view, the radius of curvature of each rounded corner(s) is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>. A substantially quadrilateral shape is formed by the contour line CL20.

It should be noted that there may be a side that cannot be seen in the planar view, such as a third side <NUM> (see <FIG>) in a head <NUM> described below. Even in such a case, the side can be recognized in the planar view by using a hidden line (see-through line) of the side.

The boundary between the upper surface <NUM> and the sidewall surface <NUM> can be defined by a ridgeline. The ridgeline can be specified as a point having a radius of curvature of less than or equal to <NUM> or as a vertex of an angular corner in a cross-sectional contour line of the outer surface of the crown atypically-shaped portion <NUM>. Although the radius of curvature of the cross-sectional contour line can vary depending on the direction of the cross section, a cross section that has the smallest radius of curvature is selected for determining the radius of curvature to specify the ridgeline.

As described below, the crown atypically-shaped portion <NUM> preferably has at least one side. That is, the contour line CL20 preferably has at least one side in the crown outer surface 12a. As in the present embodiment, the crown atypically-shaped portion <NUM> (contour line CL20) may have a substantially polygonal shape. When this substantially polygonal shape is defined as a substantially N-sided polygonal shape, N can be an integer of greater than or equal to <NUM>. N may be an integer that is greater than or equal to <NUM> and less than or equal to <NUM>.

As shown in <FIG>, the crown atypically-shaped portion <NUM> (contour line CL20) has a first side CL21, a second side CL22, a third side CL23 and a fourth side CL24. The first side CL21 constitutes a side on the toe-face side of the crown atypically-shaped portion <NUM>. The first side CL21 extends in such a manner that it goes toward the back side as it goes to the toe side. The first side CL21 connects the second side CL22 and the fourth side CL24.

The second side CL22 constitutes a side on the heel-face side of the crown atypically-shaped portion <NUM>. The second side CL22 extends in such a manner that it goes toward the back side as it goes to the heel side. The second side CL22 connects the first side CL21 and the third side CL23.

The third side CL23 constitutes a side on the heel-back side of the crown atypically-shaped portion <NUM>. The third side CL23 extends in such a manner that it goes toward the back side as it goes to the toe side. The third side CL23 connects the second side CL22 and the fourth side CL24. The third side CL23 constitutes a curved line that projects toward the outside of the head <NUM>.

The fourth side CL24 constitutes a side on the toe-back side of the crown atypically-shaped portion <NUM>. The fourth side CL24 extends in such a manner that it goes toward the back side as it goes to the heel side. The fourth side CL24 connects the third side CL23 and the first side CL21.

The second side CL22, the third side CL23, and the fourth side CL24 constitute a starting line of the sidewall surface <NUM>. That is, the second side CL22, the third side CL23, and the fourth side CL24 constitute the boundary line between the sidewall surface <NUM> and the base surface b1.

On the other hand, the first side CL21 does not constitute a starting line of the sidewall surface <NUM>. The first side CL21 constitutes the boundary line between the base surface b1 and the upper surface <NUM>.

In the present disclosure, a cross-sectional contour line in a cross section taken along the toe-heel direction is also simply referred to as a transverse cross-sectional contour line. <FIG> shows an example of the transverse cross-sectional contour line. A transverse cross-sectional contour line of the outer surface of the head <NUM> is also simply referred to as a transverse cross-sectional contour line. In the present disclosure, a cross-sectional contour line in a cross section taken along the face-back direction is also simply referred to as longitudinal cross-sectional contour line. <FIG> shows an example of the longitudinal cross-sectional contour line. A longitudinal cross-sectional contour line of the outer surface of the head <NUM> is also simply referred to as a longitudinal cross-sectional contour line.

An inflection point in the transverse cross-sectional contour line can be a point that forms the contour line CL20. In other words, this inflection point can be a starting point of the crown atypically-shaped portion <NUM>. The transverse cross-sectional contour line of the base surface b1 is a curved line that projects toward the outside of the head <NUM>. The inflection point is a point at which the curved line that projects toward the outside of the head <NUM> changes into a curved line that projects toward the inside of the head <NUM>.

A vertex of an angular corner in the transverse cross-sectional contour line can be a point that forms the contour line CL20. In other words, this vertex can be a starting point of the crown atypically-shaped portion <NUM>. The transverse cross-sectional contour line of the base surface b1 is a curved line that projects toward the outside of the head <NUM>. A line that is connected to this curved line, makes an angle, and extends toward the outside of the head <NUM> forms a vertex. This vertex points toward the inside of the head <NUM>. This vertex can be the starting point of the crown atypically-shaped portion <NUM>.

An inflection point of in the longitudinal cross-sectional contour line can be a point that forms the contour line CL20. In other words, this inflection point can be a starting point of the crown atypically-shaped portion <NUM>. The longitudinal cross-sectional contour line of the base surface b1 is a curved line that projects toward the outside of the head <NUM>. The inflection point is a point at which the curved line that projects toward the outside of the head <NUM> changes into a curved line that projects toward the inside of the head <NUM>.

A vertex of an angular corner of in the longitudinal cross-sectional contour line can be a point that forms the contour line CL20. In other words, this vertex can be a starting point of the crown atypically-shaped portion <NUM>. The longitudinal cross-sectional contour line of the base surface b1 is a curved line that projects toward the outside of the head <NUM>. A line that is connected to this curved line, makes an angle, and extends toward the outside of the head <NUM> forms a vertex. This vertex points toward the inside of the head <NUM>. This vertex can be the starting point of the crown atypically-shaped portion <NUM>.

Typically, the contour line CL20 can be determined by the inflection points or the vertices. For determining the contour line CL20, the transverse cross-sectional contour line may be selected in preference to the longitudinal cross-sectional contour line. In this case, the transverse cross-sectional contour line is used for specifying the inflection point or the vertex. When it is difficult to specify the inflection point or the vertex by using the transverse cross-sectional contour line, the longitudinal cross-sectional contour line can be used. When the contour line of the crown atypically-shaped portion <NUM> can be visually and clearly recognized, the contour line can be determined as the contour line CL20.

The crown atypically-shaped portion <NUM> is a portion that protrudes from the base surface b1. A virtually extended surface b2 that is obtained by extending the base surface b1 can be specified on the lower side of the crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is a portion that protrudes relative to the virtually extended surface b2. The virtually extended surface b2 can be considered, if no crown atypically-shaped portion <NUM> is present, as a part of the base surface b1 formed in a region in which the crown atypically-shaped portion <NUM> would be installed. The virtually extended surface b2 is formed so as to be continuous with the base surface b1. The virtually extended surface b2 is a curved surface that is convex toward the outside of the head <NUM>. The virtually extended surface b2 is smoothly continuous with the base surface b1.

<FIG> is an enlarged view of a portion that is surrounded by a tetragon Q1 in <FIG>. <FIG> is an enlarged view of a portion that is surrounded by a tetragon Q2 in <FIG>.

<FIG> shows the transverse cross-sectional contour line with a virtually extended line b3 that can form the virtually extended surface b2. The virtually extended line b3 is a curved line that projects toward the outside of the head <NUM>. The virtually extended line b3 is smoothly continuous with the transverse cross-sectional contour line of the base surface b1. The virtually extended surface b2 can be formed by a set of virtually extended lines b3.

The virtually extended line b3 smoothly connects the transverse cross-sectional contour line of the base surface b1 on one side of the crown atypically-shaped portion <NUM> and the transverse cross-sectional contour line of the base surface b1 on the other side of the crown atypically-shaped portion <NUM>. The virtually extended line b3 can be drawn as a Bezier curve. A quadratic Bezier curve and a cubic Bezier curve are known as the Bezier curve. In the quadratic Bezier curve, the number of control points is one (excluding a starting point and an end point). In the cubic Bezier curve, the number of control points is two (excluding a starting point and an end point). The cubic Bezier curve is preferably used. Bezier curves drawn in <FIG> and <FIG> are cubic Bezier curves.

As shown in <FIG>, the transverse cross-sectional contour line has a first starting point P1 and a second starting point P2. The first starting point P1 and the second starting point P2 are located on the contour line CL20.

Points P11 and P12 that are located on the opposite side of the first starting point P1 from the crown atypically-shaped portion <NUM> are plotted in order to define an effective tangent line to the transverse cross-sectional contour line at the first starting point P1. The point P11 is a point located <NUM> apart from the first starting point P1. The point P12 is a point located <NUM> apart from the point P11. These distances of "<NUM>" for these points are route lengths measured along the transverse cross-sectional contour line. The points P11 and P12 are located on the transverse cross-sectional contour line. A tangent line L1 at the point P1 to a circle that passes through these three points P1, P11 and P12 is determined. When the points P1, P11 and P12 are positioned on a single straight line, this straight line can be determined as the tangent line L1.

Similarly, points P21 and P22 that are located on the opposite side of the second starting point P2 from the crown atypically-shaped portion <NUM> are plotted in order to define an effective tangent line to the transverse cross-sectional contour line at the second starting point P2. The point P21 is a point located <NUM> apart from the second starting point P2. The point P22 is a point located <NUM> apart from the point P21. These distances of "<NUM>" for these points are route lengths measured along the transverse cross-sectional contour line. The points P21 and P22 are located on the transverse cross-sectional contour line. A tangent line L2 at the point P2 to a circle that passes through these three points P2, P21 and P22 is determined. When the points P2, P21 and P22 are positioned on a single straight line, this straight line can be determined as the tangent line L2.

When the tangent line L1 and the tangent line L2 are determined, then an intersection point Px between the tangent line L1 and the tangent line L2 is specified. Furthermore, a middle point M1 between the point P1 and the point Px is specified, and a middle point M2 between the point P2 and the point Px is specified.

A Bezier curve can be drawn by using the point P1 as the starting point, the middle point M1 as the first control point, the middle point M2 as the second control point, and the point P2 as the end point. In <FIG>, a Bezier curve drawn in this manner is the virtually extended line b3. Because of having two control points, this Bezier curve is a cubic Bezier curve.

The virtually extended line b3 can be defined at any position in the face-back direction. The virtually extended surface b2 can be defined as the set of these virtually extended lines b3.

A similar Bezier curve can be defined in the longitudinal cross-sectional contour line. As shown in <FIG>, the longitudinal cross-sectional contour line has a first starting point P1 and a second starting point P2. The first starting point P1 and the second starting point P2 are located on the contour line CL20.

Points P11 and P12 that are located on the opposite side of the first starting point P1 from the crown atypically-shaped portion <NUM> are plotted in order to define an effective tangent line to the longitudinal cross-sectional contour line at the first starting point P1. The point P11 is a point located <NUM> apart from the first starting point P1. The point P12 is a point located <NUM> apart from the point P11. These distances of "<NUM>" for these points are route lengths measured along the longitudinal cross-sectional contour line. The points P11 and P12 are located on the longitudinal cross-sectional contour line. A tangent line L1 at the point P1 to a circle that passes through these three points P1, P11 and P12 is determined. When the points P1, P11 and P12 are positioned on a single straight line, this straight line can be determined as the tangent line L1.

Similarly, points P21 and P22 that are located on the opposite side of the second starting point P2 from the crown atypically-shaped portion <NUM> are plotted in order to define an effective tangent line to the longitudinal cross-sectional contour line at the second starting point P2. The point P21 is a point located <NUM> apart from the second starting point P2. The point P22 is a point located <NUM> apart from the point P21. These distances of "<NUM>" for these points are route lengths measured along the longitudinal cross-sectional contour line. The points P21 and P22 are located on the longitudinal cross-sectional contour line. A tangent line L2 at the point P2 to a circle that passes through these three points P2, P21 and P22 is determined. When the points P2, P21 and P22 are positioned on a single straight line, this straight line can be determined as the tangent line L2.

A Bezier curve can be drawn by using the point P1 as the starting point, the middle point M1 as the first control point, the middle point M2 as the second control point, and the point P2 as the end point. In <FIG>, a Bezier curve drawn in this manner is a virtually extended line b4.

The virtually extended line b4 can be defined at any position in the toe-heel direction. The virtually extended surface b2 can be defined as the set of these virtually extended lines b4.

In some cases, the crown atypically-shaped portion may reach an outer peripheral edge (contour line CL4) of the crown portion. In such a case, the number of the starting point(s) of the crown atypically-shaped portion which is/are formed on the boundary between the crown atypically-shaped portion and the base surface b1 can be only one in the transverse cross-sectional contour line and/or the longitudinal cross-sectional contour line. When only one starting point is present as in this case, a circular arc that is drawn so as to path through the starting point and have a radius of curvature at the starting point can be the virtually extended line b3. That is, in this case, the virtually extended line b3 can be a circle that passes through the following three points: a first point that is the starting point; a second point located <NUM> apart from the first point; and a third point located <NUM> apart from the second point.

For determining the virtually extended surface b2, the transverse cross-sectional contour line may be used in preference to the longitudinal cross-sectional contour line. The virtually extended surface b2 can be determined as a set of the virtually extended lines b3 obtained from the transverse cross-sectional contour lines. When the virtually extended surface b2 is not clearly determined by the set of the virtually extended lines b3, the virtually extended surface b2 may be determined as a set of the virtually extended lines b4 obtained from the longitudinal cross-sectional contour lines.

A height Ht of the crown atypically-shaped portion <NUM> can be defined as a height from the virtually extended surface b2. As shown in <FIG>, a normal line LN that is normal to the virtually extended surface b2 at a certain point f1 has an intersection point f2 at which the normal line LN intersects the outer surface of the crown atypically-shaped portion <NUM>. A distance between the point f1 and the intersection point f2 can be defined as the height Ht of the crown atypically-shaped portion <NUM> at the intersection point f2. When the crown atypically-shaped portion does not intersect the normal line LN of the virtually extended surface b2 and has a point at which the crown atypically-shaped portion intersects a normal line that is normal to the base surface b1, the height Ht of the crown atypically-shaped portion at the point is defined as a height from the base surface b1. Also in this case, the length of the normal line is the height Ht. When the crown atypically-shaped portion <NUM> forms a recess on the crown outer surface 12a, the height Ht of the crown atypically-shaped portion <NUM> is defined as the height from the virtually extended surface b2. In this case, the intersection point f2 is an intersection point between the normal line and the inner surface of the crown atypically-shaped portion. The maximum value of the height Ht is the maximum height of the crown atypically-shaped portion <NUM>.

As explained above, when the crown atypically-shaped portion <NUM> is the crown projection <NUM> that forms a projection on the crown outer surface 12a, the virtually extended surface b2 and the contour line CL20 can be determined. Similarly, when the crown atypically-shaped portion <NUM> is a crown recess that forms a recess on the crown outer surface 12a, the virtually extended surface b2 and the contour line CL20 can be determined. Also when the crown atypically-shaped portion <NUM> is the crown recess, the contour line CL20 of the crown atypically-shaped portion <NUM> can be determined on the crown outer surface 12a. In this case, however, points that constitute the contour line CL20 including the points P1 and P2 are not inflection points on the cross-sectional contour line of the crown outer surface 12a. This is because, when a recess is formed on the crown outer surface 12a, a round corner in which the starting point of the recess is present is a curved line that projects toward the outside of the head <NUM> as with the base surface b1. From this viewpoint, when the crown atypically-shaped portion <NUM> is the crown recess, points that constitute the contour line CL20 can be considered as portions (points) having the smallest radius of curvature or as vertices of angular corners in cross-sectional contour lines. In the case where the portion having the smallest radius of curvature is a circular arc, the midpoint of the circular arc can be the point constituting the contour line CL20. Excepting this matter, the methods for determining the contour line CL20 and the virtually extended surface b2 of the crown recess are the same as those of the crown projection.

<FIG> is the plan view of the head <NUM> as with <FIG>. <FIG> additionally shows a crown rib <NUM> and a sole rib <NUM> provided on the inner surface of the head <NUM> with dashed lines. The crown rib <NUM> and the sole rib <NUM> in <FIG> are schematically illustrated by indicating only rib center lines L30 and L40 of the respective ribs. <FIG> is a cross-sectional view taken along line A-A in <FIG>. <FIG> is an enlarged view of a portion shown within the circle of <FIG>. <FIG> is a cross-sectional view taken along line B-B in <FIG>. <FIG> is a cross-sectional view taken along line C-C in <FIG>. <FIG> is a perspective view of a head body 4a of the head <NUM>. In the head <NUM>, a face member (not shown) and the head body 4a are joined (welded) to each other. In <FIG>, the inside of the head <NUM> is viewable.

As shown in <FIG> and <FIG>, the crown atypically-shaped portion <NUM> forms the projection 20a on the crown outer surface 12a while forming the recess 20b on the crown inner surface 12b. The recess 20b is also referred to as an inner surface recess. The projection 20a is also referred to as an outer surface projection. The inner surface recess 20b is recessed to correspond to the outer surface projection 20a. As shown in <FIG>, the inner surface recess 20b has a portion located on the outer side (outer side of the head <NUM>) relative to the virtually extended surface b2.

In the crown portion <NUM>, a bent portion <NUM> is formed along the contour line CL20 of the crown atypically-shaped portion <NUM>. The bent portion <NUM> is formed by bending a wall forming the crown portion <NUM>. The bent portion <NUM> may be angled or may be curved. In the crown outer surface 12a, the contour line CL20 is a starting point of bending of the bent portion <NUM>. The wall thickness of the crown atypically-shaped portion <NUM> is substantially the same as the wall thickness of the crown portion <NUM> in the vicinity of the crown atypically-shaped portion <NUM>. Since the inner surface recess 20b is formed on the reverse side of the outer surface projection 20a, the bent portion <NUM> is formed. In the embodiment of <FIG>, the bent portion <NUM> forms a rounded corner on the crown outer surface 12a and forms an angular corner on the crown inner surface 12b. The bent portion <NUM> may form a rounded corner both on the crown outer surface 12a and the crown inner surface 12b. The bent portion <NUM> may form an angular corner both on the crown outer surface 12a and the crown inner surface 12b. The bent portion <NUM> may form an angular corner on the crown outer surface 12a, and may form a rounded corner on the crown inner surface 12b.

As shown with a dashed line in <FIG>, the crown portion <NUM> includes the rib <NUM>. The rib <NUM> is provided on the crown inner surface 12b. The rib <NUM> is also referred to as a crown rib. The crown portion <NUM> including the crown rib <NUM> is integrally formed as a single piece member.

The crown rib <NUM> is provided at a position different from the position of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> does not intersect the crown atypically-shaped portion <NUM>. The crown rib <NUM> may intersect the crown atypically-shaped portion <NUM>.

In the present embodiment, the number of the crown rib <NUM> is one. A plurality of crown ribs <NUM> may be provided.

As shown with dashed lines in <FIG>, the rib <NUM> is provided in the sole portion <NUM>. As shown in <FIG>, the rib <NUM> is provided on the sole inner surface 14b. The rib <NUM> is also referred to as a sole rib. The sole rib <NUM> includes a first sole rib <NUM> and a second sole rib <NUM>. The first sole rib <NUM> and the second sole rib <NUM> intersect each other. The number of the sole ribs <NUM> may be one or may be plural as in the present embodiment.

As shown in <FIG>, the crown rib <NUM> is positioned on the crown center side relative to a center C1 of the crown atypically-shaped portion <NUM>. That is, in the planar view, a line segment S1 that extends from the center C1 to the crown center RC intersects the crown rib <NUM>. The center C1 of the crown atypically-shaped portion <NUM> means the geometric center (center of figure) of the contour line CL20 in the planar view.

The crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. That is, in the planar view, the crown rib <NUM> is disposed between the contour line CL20 of the crown atypically-shaped portion <NUM> and the crown center RC. In the planar view, the crown rib <NUM> intersects the line segment S1 extending from the center C1 to the crown center RC, and does not intersect the crown atypically-shaped portion <NUM>.

The contour line CL20 of the crown atypically-shaped portion <NUM> has at least one side. As described above, in the present embodiment, the contour line CL20 has four sides CL21 to CL24. These sides CL21 to CL24 include a specific side CL24 that is positioned on the crown center side relative to the center C1 of the crown atypically-shaped portion <NUM>. In the planar view, a side that intersects the line segment S1 is defined as the specific side.

<FIG> is a cross-sectional view taken along line B-B in <FIG>. The line B-B extends in a width direction of the crown rib <NUM>. The crown rib <NUM> has a first starting point 30a and a second starting point 30b. A line segment S2 that extends from the first starting point 30a to the second starting point 30b is determined. The length of the line segment S2 is defined as a rib base width W1. The width direction is a direction in which the rib base width W1 is at the minimum value. In each cross section taken along the width direction, a middle point Pm of the line segment S2 is determined. The set of the middle points Pm is the rib center line L30.

A double-pointed arrow Hr in <FIG> shows the height of the crown rib <NUM>. The height Hr is measured in a cross section taken along the width direction. The height Hr is measured in a direction that is perpendicular to the line segment S2. The height Hr is the height measured from the line segment S2.

The crown rib <NUM> extends substantially parallel to the specific side CL24. That is, in the planar view, an angle formed between the rib center line L30 of the crown rib <NUM> and the specific side CL24 is <NUM>° ±<NUM>°. In other words, this angle is greater than or equal to -<NUM>° and less than or equal to +<NUM>°. For determining this angle, when the rib center line L30 is a curved line, a tangent line at each point on the curved line is taken into consideration. Similarly, for determining the angle, when the specific side CL24 is a curved line, a tangent line at each point on the curved line is taken into consideration. When the above angle is <NUM>° ±<NUM>° in every tangent line, the crown rib <NUM> and the specific side CL24 are substantially parallel to each other. More preferably, in the planar view, the angle formed between the rib center line L30 and the specific side CL24 is <NUM>° ±<NUM>° (greater than or equal to -<NUM>° and less than or equal to <NUM>°). More preferably, in the planar view, the angle formed between the rib center line L30 and the specific side CL24 is <NUM>° ±<NUM>° (greater than or equal to -<NUM>° and less than or equal to <NUM>°).

At least one end of the crown rib <NUM> is located in an outer edge portion 12e of the crown portion <NUM>. In the planar view, a region that extends from the contour line CL4 of the crown portion <NUM> to a position <NUM> apart (in shortest distance) from the contour line CL4 is the outer edge portion 12e. The outer edge portion 12e includes an outer edge portion 12f that extends from the contour line CL5 on the face side of the crown portion <NUM> to a position <NUM> apart (in shortest distance) from the contour line CL5. As shown in <FIG>, the crown rib <NUM> has a back-side end <NUM> and a face-side end 30f. In the present embodiment, only one of the two ends of the crown rib <NUM> is located in the outer edge portion 12e. In the present embodiment, the back-side end <NUM> is located in the outer edge portion 12e. On the other hand, the face-side end 30f is not located in the outer edge portion 12e. The face-side end 30f is located on the back side relative to the outer edge portion 12f.

In the head <NUM>, the entirety of the crown atypically-shaped portion <NUM> is disposed in a region that extends from the contour line CL4 of the crown portion <NUM> to a position <NUM> apart from the contour line CL4. That is, in the planar view, all points on the contour line CL20 of the crown atypically-shaped portion <NUM> have a distance (shortest distance) from the contour line CL4 of less than or equal to <NUM>.

<FIG> is a plan view of a head <NUM> according to a second embodiment. <FIG> is a cross-sectional view taken along line A-A in <FIG>. <FIG> is a cross-sectional view taken along line B-B in <FIG>. <FIG> is a perspective view of a head body 50a of the head <NUM>. In the head <NUM>, a face member (not shown in the drawings) and the head body 50a are joined (welded) to each other. In <FIG>, the face member is absent, and thus the inside of the head <NUM> is viewable.

The head <NUM> includes a face portion <NUM>, a crown portion <NUM>, a sole portion <NUM>, and a hosel portion <NUM>. The face portion <NUM> includes a striking face 10a. The striking face 10a is the outer surface of the face portion <NUM>. The crown portion <NUM> forms a crown outer surface 12a and a crown inner surface 12b. The crown outer surface 12a includes a crown base surface b1 that is a convex curved surface and extends continuously with no step. The sole portion <NUM> forms a sole outer surface 14a and a sole inner surface 14b. The hosel portion <NUM> has a shaft hole 16a.

The crown portion <NUM> includes a crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is hollow. The crown atypically-shaped portion <NUM> forms an outer surface projection 60a on the crown outer surface 12a while forming an inner surface recess 60b on the crown inner surface 12b. The inner surface recess 60b is recessed to correspond to the outer surface projection 60a. The crown atypically-shaped portion <NUM> forms a projection on the crown portion <NUM> when viewed from outside the head <NUM>. The crown atypically-shaped portion <NUM> is a crown projection <NUM>. The entirety of the crown atypically-shaped portion <NUM> is located on the heel side relative to the face center.

The crown atypically-shaped portion <NUM> has a contour line CL60. The contour line CL60 is a boundary line between the crown base surface b1 and the crown atypically-shaped portion <NUM>. In the plan view (planar view) of the head <NUM>, the crown atypically-shaped portion <NUM> has a substantially pentagonal shape. The substantially pentagonal shape is formed by the contour line CL60.

The contour line CL60 of the crown atypically-shaped portion <NUM> has a first side CL61, a second side CL62, a third side CL63, a fourth side CL64, and a fifth side CL65.

As shown in <FIG> and <FIG>, in the crown portion <NUM>, a bent portion <NUM> is formed along the contour line CL60 of the crown atypically-shaped portion <NUM>. The wall thickness of the crown atypically-shaped portion <NUM> is substantially the same as the wall thickness of the crown portion <NUM> in the vicinity of the crown atypically-shaped portion <NUM>. Since the inner surface recess 60b is formed on the reverse side of the outer surface projection 60a, the bent portion <NUM> is formed.

As shown with a dashed line in <FIG>, the crown portion <NUM> includes a rib (crown rib) <NUM>. The crown rib <NUM> is schematically illustrated by indicating only its rib center line L70. The crown rib <NUM> is provided on the crown inner surface 12b. The crown portion <NUM> including the crown rib <NUM> is integrally formed as a single piece member.

The crown rib <NUM> is provided at a position different from the position of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> does not intersect the crown atypically-shaped portion <NUM>.

As shown with dashed lines in <FIG>, the sole portion <NUM> of the head <NUM> includes a rib <NUM>. The rib <NUM> is provided on the sole inner surface 14b. The rib <NUM> is also referred to as a sole rib. The sole rib <NUM> is schematically illustrated by indicating only its rib center line L80. The sole rib <NUM> includes a first sole rib <NUM> and a second sole rib <NUM>. The first sole rib <NUM> and the second sole rib <NUM> intersect each other.

As shown in <FIG>, the crown rib <NUM> is positioned on the crown center side relative to the center C1 of the crown atypically-shaped portion <NUM>. Further, the crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. The contour line CL60 of the crown atypically-shaped portion <NUM> includes a specific side CL65 that is positioned on the crown center side relative to the center C1 of the crown atypically-shaped portion <NUM>. The crown rib <NUM> extends substantially parallel to the specific side CL65. A first end (back-side end) 70b of the crown rib <NUM> is located in the outer edge portion 12e of the crown portion <NUM>. A second end (face-side end) 70f of the crown rib <NUM> is not located in the outer edge portion 12e. The face-side end 70f is located on the back side relative to the outer edge portion 12f. In the head <NUM>, the entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4.

<FIG> is a plan view of a head <NUM> according to a third embodiment. <FIG> is a cross-sectional view taken along line A-A in <FIG>.

The crown inner surface 12b and the sole inner surface 14b face a hollow portion k1.

The crown portion <NUM> includes a crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is hollow. Unlike the crown atypically-shaped portion <NUM> or the crown atypically-shaped portion <NUM>, the crown atypically-shaped portion <NUM> is a crown recess <NUM>. The crown atypically-shaped portion <NUM> forms a recess (outer surface recess) 100a on the crown outer surface 12a while forming a projection (inner surface projection) 100b on the crown inner surface 12b. The inner surface projection 100b protrudes to correspond to the outer surface recess 100a. The crown atypically-shaped portion <NUM> forms a recess on the crown portion <NUM> when viewed from outside the head <NUM>. The entirety of the crown atypically-shaped portion <NUM> is located on the heel side relative to the face center. The head <NUM> is the same as the head <NUM> except for the shape of the crown atypically-shaped portion.

The outer surface recess 100a has a portion located on the inner side (inner side of the head <NUM>) relative to the virtually extended surface b2.

The crown recess <NUM> can be used as a receiving portion to which an additional member such as a badge is attached. The additional member such as badge can be attached to the outer surface recess 100a. The fixability of the additional member is enhanced by physical engagement with the outer surface recess 100a. By forming a flat surface portion on the bottom surface of the outer surface recess 100a, attachability (adhesivity) of the additional member can be improved. Further, the presence of the outer surface recess 100a can suppress the height of the additional member from the crown outer surface 12a. The material of the additional member such as badge can be a resin, a metal, a ceramic, or any combination thereof.

The crown atypically-shaped portion <NUM> has a contour line CL100. In the planar view, the crown atypically-shaped portion <NUM> has a substantially rectangular shape. The substantially rectangular shape is formed by the contour line CL100.

The crown atypically-shaped portion <NUM> (contour line CL100) has a first side CL101, a second side CL102, a third side CL103, and a fourth side CL104.

As shown in <FIG>, in the crown portion <NUM>, a bent portion <NUM> is formed along the contour line CL100 of the crown atypically-shaped portion <NUM>. The wall thickness of the crown atypically-shaped portion <NUM> is substantially the same as the wall thickness of the crown portion <NUM> in the vicinity of the crown atypically-shaped portion <NUM>. Since the inner surface projection 100b is formed on the reverse side of the outer surface recess 100a, the bent portion <NUM> is formed.

As shown with a dushed line in <FIG>, the crown portion <NUM> includes a rib (crown rib) <NUM>. The crown rib <NUM> is schematically illustrated by indicating only its rib center line L110. The crown rib <NUM> is provided on the crown inner surface 12b. The crown portion <NUM> including the crown rib <NUM> is integrally formed as a single piece member.

The crown rib <NUM> is provided at a position different from the position of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> does not intersect the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located between the crown atypically-shaped portion <NUM> and the crown center RC.

As shown with dushed lines in <FIG>, the sole portion <NUM> of the head <NUM> includes a rib (sole rib) <NUM>. The sole rib <NUM> is schematically illustrated by indicating only its rib center line L120. The rib (sole rib) <NUM> is provided on the sole inner surface 14b. The sole rib <NUM> includes a first sole rib <NUM> and a second sole rib <NUM>. The first sole rib <NUM> and the second sole rib <NUM> intersect each other. As shown in <FIG>, the sole rib <NUM> has a height higher than that of the crown rib <NUM>.

As shown in <FIG>, the crown rib <NUM> is positioned on the crown center side relative to the center C1 of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. The contour line CL100 of the crown atypically-shaped portion <NUM> includes a specific side CL104 positioned on the crown center side relative to the center C1 of the crown atypically-shaped portion <NUM>. The crown rib <NUM> extends substantially parallel to the specific side CL104. A first end (back-side end) 110b of the crown rib <NUM> is located in the outer edge portion 12e of the crown portion <NUM>. A second end (face-side end) 110f of the crown rib <NUM> is not located in the outer edge portion 12e. The face-side end 110f is located on the back side relative to the outer edge portion 12f. In the head <NUM>, the entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4.

<FIG> is a plan view of a head <NUM> according to a fourth embodiment. The head <NUM> is the same as the above-described head <NUM> except that the crown atypically-shaped portion and the crown rib is replaced. The head <NUM> includes a face portion <NUM>, a crown portion <NUM>, a sole portion (not shown in the drawing), and a hosel portion <NUM>.

The crown portion <NUM> includes a crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is a crown projection <NUM>. The crown atypically-shaped portion <NUM> has a contour line CL140. The contour line CL140 includes a plurality of (four) sides. The contour line CL140 has a first side CL141, a second side CL142, a third side CL143, and a fourth side CL144. The contour line CL140 includes a specific side CL144 positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>.

The crown portion <NUM> includes a crown rib <NUM>. The crown rib <NUM> is provided on the inner surface of the crown portion <NUM>. The crown rib <NUM> is schematically illustrated by indicating only its rib center line L150 with dushed line. The crown rib <NUM> is provided at a position different from the position of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> does not intersect the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located between the crown atypically-shaped portion <NUM> and the crown center RC.

The crown rib <NUM> is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. The crown rib <NUM> extends substantially parallel to the specific side CL144. A first end 150b of the crown rib <NUM> is located in the outer edge portion 12e of the crown portion <NUM>. A second end 150f of the crown rib <NUM> is not located in the outer edge portion 12e. In the head <NUM>, the entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4.

<FIG> is a plan view of a head <NUM> according to a fifth embodiment. The head <NUM> is the same as the above-described head <NUM> except that the crown atypically-shaped portion and the crown rib is replaced. The head <NUM> includes a face portion <NUM>, a crown portion <NUM>, a sole portion (not shown in the drawing), and a hosel portion <NUM>.

The crown portion <NUM> includes a crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is a crown projection <NUM>. The crown atypically-shaped portion <NUM> has a contour line CL170. The contour line CL170 includes a plurality of (four) sides. The contour line CL170 includes a specific side CL171 positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>.

The crown portion <NUM> includes a crown rib <NUM>. The crown rib <NUM> is provided on the inner surface of the crown portion <NUM>. The crown rib <NUM> is schematically illustrated by indicating only its rib center line L180 with dushed line. The crown rib <NUM> includes a portion located on the inner surface of the crown atypically-shaped portion <NUM>. That is, the crown rib <NUM> intersects the crown atypically-shaped portion <NUM>. The crown rib <NUM> intersects the specific side CL171. The crown rib <NUM> is located between the center of the crown atypically-shaped portion <NUM> and the crown center RC.

The crown rib <NUM> is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>. However, the crown rib <NUM> is not positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is not substantially parallel to the specific side CL171. A first end 180b of the crown rib <NUM> is located in the outer edge portion 12e of the crown portion <NUM>. A second end 180f of the crown rib <NUM> is not located in the outer edge portion 12e. In the head <NUM>, the entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4.

<FIG> is a plan view of a head <NUM> according to a sixth embodiment. The head <NUM> is the same as the above-described head <NUM> except that the crown atypically-shaped portion and the crown rib is replaced. The head <NUM> includes a face portion <NUM>, a crown portion <NUM>, a sole portion (not shown in the drawing), and a hosel portion <NUM>.

The crown portion <NUM> includes a crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is a crown projection <NUM>. The crown atypically-shaped portion <NUM> has a contour line CL200. The contour line CL200 has a specific side CL201.

The crown portion <NUM> includes a crown rib <NUM>. The crown rib <NUM> is provided on the inner surface of the crown portion <NUM>. The crown rib <NUM> is schematically illustrated by indicating only its rib center line L210 with dushed line. The crown rib <NUM> is provided at a position different from the position of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> does not intersect the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located between the crown atypically-shaped portion <NUM> and the crown center RC.

The crown rib <NUM> is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. A first end 210b of the crown rib <NUM> is not located in the outer edge portion 12e of the crown portion <NUM>. A second end 210f of the crown rib <NUM> is not located in the outer edge portion 12e, either. In the head <NUM>, the entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4.

<FIG> is a plan view of a head <NUM> according to a seventh embodiment. The head <NUM> is the same as the above-described head <NUM> except that the crown atypically-shaped portion and the crown rib is replaced. The head <NUM> includes a face portion <NUM>, a crown portion <NUM>, a sole portion (not shown in the drawing), and a hosel portion <NUM>.

The crown portion <NUM> includes a plurality of (two) crown atypically-shaped portions. The crown portion <NUM> includes a first crown atypically-shaped portion <NUM> and a second crown atypically-shaped portion <NUM>. The crown atypically-shaped portion <NUM> is a crown projection <NUM>. The crown atypically-shaped portion <NUM> is a crown projection <NUM>. The crown atypically-shaped portion <NUM> is located on the face side of the crown atypically-shaped portion <NUM>.

The contour line of the crown atypically-shaped portion <NUM> has a specific side CL231 that is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>. The contour line of the crown atypically-shaped portion <NUM> has a specific side CL241 that is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>.

The crown portion <NUM> includes a crown rib <NUM>. The crown rib <NUM> is provided on the inner surface of the crown portion <NUM>. The crown rib <NUM> is schematically illustrated by indicating only its rib center line L250 with dushed line. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located between the crown atypically-shaped portion <NUM> and the crown center RC. The crown rib <NUM> is located apart from the crown atypically-shaped portion <NUM>. The crown rib <NUM> is located between the crown atypically-shaped portion <NUM> and the crown center RC.

The crown rib <NUM> is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is positioned on the crown center side relative to the center of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>. The crown rib <NUM> is positioned on the crown center side relative to the entirety of the crown atypically-shaped portion <NUM>.

The crown rib <NUM> extends substantially parallel to the specific side CL231. The crown rib <NUM> extends substantially parallel to the specific side CL241. A first end 250b of the crown rib <NUM> is located in the outer edge portion 12e of the crown portion <NUM>. A second end 250f of the crown rib <NUM> is also located in the outer edge portion 12e. The entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4. The entirety of the crown atypically-shaped portion <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4. The entirety of all of the plurality of crown atypically-shaped portions <NUM> and <NUM> is disposed in the region extending from the contour line CL4 of the crown portion <NUM> to the position <NUM> apart from the contour line CL4.

<FIG> is a plan view of a head 4y according to an eighth embodiment as viewed from the crown side. The head 4y includes a crown rib <NUM> and a sole rib <NUM>. The head 4y is the same as the head <NUM> of the first embodiment except that the second sole rib <NUM> is removed from the head <NUM> of the first embodiment. In the head 4y, the number of the sole rib is one. In the planar view, the sole rib <NUM> intersects the crown rib <NUM>. In the head 4y, a portion having the maximum amplitude in the primary vibration mode is located in the crown portion <NUM>.

<FIG> is a plan view of a head 4z according to a ninth embodiment as viewed from the crown side. <FIG> is a cross-sectional view taken along line A-A in <FIG>. The head 4z includes a crown rib <NUM> and a sole rib <NUM>. The head 4z is the same as the head <NUM> of the first embodiment except that the first sole rib <NUM> is removed from the head <NUM> of the first embodiment. In the head 4z, the number of the sole rib is one. In the planar view, the sole rib <NUM> intersects the crown rib <NUM>. In the head 4z, a portion having the maximum amplitude in the primary vibration mode is located in the crown portion <NUM>. As shown in <FIG>, the sole rib <NUM> has a height higher than that of the crown rib <NUM>.

<FIG> is a simulation image showing a vibration mode of a head 4x in which the crown rib <NUM> is removed from the head <NUM> of the first embodiment. <FIG> shows a primary vibration mode. In this image, the relative magnitude of amplitude of vibration with respect to the maximum amplitude of vibration is indicated by contour lines. In this image, the lower (darker) the brightness is, the larger the amplitude of vibration is.

<FIG> is a simulation image showing a vibration mode of a head 50x in which the crown rib <NUM> is removed from the head <NUM> of the second embodiment. <FIG> shows a primary vibration mode. In this image, the relative magnitude of amplitude of vibration with respect to the maximum amplitude of vibration is indicated by contour lines. In this image, the lower (darker) the brightness is, the larger the amplitude of vibration is.

The vibration mode means the shape of vibration obtained by an eigenvalue analysis (modal analysis) of the head. The vibration mode is also referred to as a characteristic mode shape. The vibration mode is determined for each natural frequency. A vibration mode when the natural frequency is at the smallest value is the primary vibration mode. The vibration modes such as the primary vibration mode, the secondary vibration mode, and the tertiary vibration mode are determined in ascending order of the natural frequency. The eigenvalue analysis of a head is performed by simulation.

In this simulation, the finite element method is used. In this finite element method, three-dimensional data (calculation model) of a head is mesh-divided. This mesh division can be made by a commercially available preprocessor (such as HyperMesh). In addition, a longitudinal elastic modulus, a density, and a Poisson's ratio are used as the physical property values of the head material.

In the eigenvalue analysis, natural frequencies of the head and vibration modes for respective natural frequencies are obtained. As a software for the eigenvalue analysis, "Nastran" produced by MSC software Corporation can be used. The constraint condition is set to a free support condition. By this eigenvalue analysis, a plurality of natural frequencies and vibration modes for respective natural frequencies are obtained.

As shown in <FIG> and <FIG>, the inventor of the present disclosure found that vibration having a large amplitude occurs on and near the crown atypically-shaped portion. The inventor has also found that the amplitude of vibration is particularly large on the crown center side of the crown atypically-shaped portion. It has been found that the crown portion <NUM> tends to vibrate at a low frequency because of the presence of the crown atypically-shaped portion. Accordingly, it is found that the presence of the crown atypically-shaped portion lowers the pitch of sound at impact. It is considered that the bending of the bent portion causes the low-frequency vibration. It is considered that the vibration is generated in a state where the first starting point of the vibration is positioned at the bent portion and the second starting point of the vibration is positioned on the crown center side of the bent portion.

As shown in <FIG> and <FIG>, it has been found that a portion having a large amplitude of vibration is located on and near the crown atypically-shaped portion and on the crown center side of the crown atypically-shaped portion. Further, it has been found that the vibration extends to the vicinity of the crown center RC. In the outer edge portion 12e, the rigidity of the crown portion <NUM> is high. Accordingly, it is considered that vibration is hardly generated in a region that is located on the outer edge portion 12e side relative to the crown atypically-shaped portion. On the other hand, a region that is located on the crown center RC side relative to the crown atypically-shaped portion has a lower rigidity than the rigidity of the outer edge portion 12e. For this reason, it is considered that vibration having a large amplitude is generated on the crown center side of the crown atypically-shaped portion.

The crown rib <NUM> of the head <NUM> suppresses the occurrence of the low-frequency vibration which is otherwise caused by the crown atypically-shaped portion <NUM>. The crown rib <NUM> is disposed in a portion having a large amplitude of vibration in the head 4x. In this case, the above-mentioned vibration suppression effect is large. The crown rib <NUM> increases the primary natural frequency and makes the frequency of sound at impact higher. The primary natural frequency of the head 4x was <NUM>. On the other hand, the primary natural frequency of the head <NUM> provided with the crown rib <NUM> was <NUM>.

The same applies to the head <NUM>. The crown rib <NUM> of the head <NUM> suppresses the occurrence of the low-frequency vibration that is otherwise caused by the crown atypically-shaped portion <NUM>. The crown rib <NUM> is disposed in a portion having a large amplitude of vibration in the head 50x. In this case, the above-mentioned vibration suppression effect is large. The crown rib <NUM> increases the primary natural frequency and makes the frequency of sound at impact higher. The primary natural frequency of the head 50x was <NUM>. On the other hand, the primary natural frequency of the head <NUM> provided with the crown rib <NUM> was <NUM>.

A portion located on the crown center side in the crown portion <NUM> has a lower rigidity as compared with the outer edge portion 12e. Accordingly, the antinode of the vibration is located on the crown center side of the crown atypically-shaped portion. The presence of the crown rib on the crown center side of the crown atypically-shaped portion can effectively suppress the occurrence of the low-frequency vibration, whereby an excessively low-pitched sound at impact can be improved.

The crown rib is located apart from the crown atypically-shaped portion. Since a portion located on the crown center side of the crown atypically-shaped portion easily vibrates, when the crown rib is located apart from the crown atypically-shaped portion toward the crown center side, the occurrence of the low-frequency vibration is effectively suppressed and the effect of improving sound at impact is enhanced.

The specific side is a side located on the crown center side having a low rigidity, and thus is likely to be the starting point of vibration. As shown in <FIG> and <FIG>, a portion having a large amplitude of vibration is distributed substantially along the specific side of the crown atypically-shaped portion. When the crown rib is disposed substantially parallel to the specific side, the occurrence of the low-frequency vibration can be effectively suppressed, and sound at impact can be improved.

Although the amplitude of vibration is large on and near the contour line of the crown atypically-shaped portion, the vibration extends to the vicinity of the crown center RC. The amplitude of vibration becomes smaller with increasing proximity to the crown center RC. By changing the position of the crown rib in the area between the center C1 of the crown atypically-shaped portion and the crown center RC, the natural frequency can be effectively adjusted. As a result, the pitch of sound at impact can be adjusted by the position of the crown rib. For example, as in the head <NUM> (<FIG>), when the crown rib <NUM> is disposed apart from the crown atypically-shaped portion <NUM> and is located closer to the crown center RC, an increase in the natural frequency can be suppressed. This can make it possible to obtain a lower-pitched sound at impact than when the crown rib is disposed at a position having the maximum amplitude of vibration, although the obtained sound at impact is higher-pitched than when there is no crown rib. The presence of the crown rib can enable to effectively adjust the sound at impact while an excessively low-pitched sound at impact can be improved.

By positioning at least one of the ends of the crown rib in the outer edge portion 12e having a high rigidity, the above-mentioned vibration suppression effect brought by the crown rib is enhanced, and the sound at impact can be effectively higher pitched. As in the head <NUM> (<FIG>), when both ends of the crown rib <NUM> are not disposed in the outer edge portion 12e, the above-mentioned vibration suppression effect decreases. This configuration is effective when one desires to adjust sound at impact to be a little lower pitched.

When the face-side end of the crown rib is disposed in the outer edge portion 12e, this crown rib can suppress the deformation of the face portion <NUM>, and can reduce the coefficient of restitution of the head. From this viewpoint, the face-side end of the crown rib is preferably positioned on the back side relative to the outer edge portion 12f.

As shown in <FIG>, in the head 4x, a portion having the maximum amplitude in the primary vibration mode is located in the crown portion <NUM>. This holds true for the head <NUM> having the crown rib <NUM>. On the other hand, when the sole rib <NUM> is removed from the head <NUM> (<FIG>), such a portion having the maximum amplitude in the primary vibration mode is located in the sole portion <NUM>, and the vibration mode shown in <FIG> is the tertiary vibration mode. The sole portion <NUM> of the head <NUM> includes the sole rib <NUM> that shifts the portion having the maximum amplitude in the primary vibration mode from the sole portion <NUM> to the crown portion <NUM>. Because of the presence of the sole rib <NUM>, a region that has the maximum vibration in the primary vibration mode is positioned in the crown portion <NUM>. Accordingly, the primary natural frequency can be changed by the crown rib <NUM>. The primary natural frequency has a greater effect on the pitch of sound at impact felt by golfers, as compared with the secondary and subsequent natural frequencies. Accordingly, sound at impact can be effectively adjusted by the crown rib <NUM>.

As shown in <FIG>, in the head 50x, a portion having the maximum amplitude in the primary vibration mode is positioned in the crown portion <NUM>. This holds true for the head <NUM> having the crown rib <NUM>. On the other hand, when the sole rib <NUM> is removed from the head <NUM> (<FIG>), such a portion having the maximum amplitude in the primary vibration mode is located in the sole portion <NUM>, and the vibration mode shown in <FIG> is the secondary vibration mode. The sole portion <NUM> of the head <NUM> includes the sole rib <NUM> that shifts the portion having the maximum amplitude in the primary vibration mode from the sole portion <NUM> to the crown portion <NUM>. Because of the presence of the sole rib <NUM>, a region that has the maximum vibration in the primary vibration mode is positioned in the crown portion <NUM>. Accordingly, the primary natural frequency can be changed by the crown rib <NUM>. Accordingly, sound at impact can be effectively adjusted by the crown rib <NUM>.

A double-pointed arrow E1 in <FIG> shows the length of the crown rib. The length E1 is measured in the planar view. The length E1 is the length (route length) of the rib center line in the planar view.

From the viewpoint of suppressing the occurrence of the low frequency vibration which can be caused by the crown atypically-shaped portion and obtaining a higher-pitched sound at impact, the length E1 of the crown rib is preferably greater than or equal to <NUM>, more preferably greater than or equal to <NUM>, and still more preferably greater than or equal to <NUM>. Dimensions of the crown portion <NUM> is limited due to the restriction on the head volume imposed by the rules of golf. From this viewpoint, the length E1 of the crown rib is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>.

When the contour line of the crown atypically-shaped portion has the specific side, the length of the specific side is not limited. When the specific side is long, the vibration of the crown portion <NUM> caused by the specific side increases. Accordingly, when the specific side is long, the effect of the crown rib is large. From this viewpoint, the length of the specific side is preferably greater than or equal to <NUM>, more preferably greater than or equal to <NUM>, and still more preferably greater than or equal to <NUM>. An excessively long specific side is likely to result in an excessively lower-pitched sound at impact. From this viewpoint, the length of the specific side is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, still more preferably less than or equal to <NUM>, still more preferably less than or equal to <NUM>, and yet still more preferably less than or equal to <NUM>. The length of the specific side is measured in the planar view. The length of the specific side is the length (route length) in the plan view.

The crown atypically-shaped portion <NUM> of the first embodiment includes the side wall surface <NUM> (<FIG>). As described above, the specific side CL24 is the starting line of the side wall surface <NUM>. That is, the specific side CL24 is the lower edge of the side wall surface <NUM>. In this case, the angle of the corner of the bent portion <NUM> of the crown atypically-shaped portion <NUM> becomes large, and the crown portion <NUM> easily vibrates. Accordingly, this configuration enhances the sound-at-impact improving effect and the sound-at-impact adjusting effect brought by the crown rib <NUM>.

The position of the crown atypically-shaped portion in the crown portion <NUM> is not limited. In each of the above embodiments, the crown atypically-shaped portion is disposed on the heel side relative to the crown center RC. The crown atypically-shaped portion may be disposed on the toe side relative to the crown center RC, for example. The crown atypically-shaped portion may be disposed on the back side relative to the crown center RC, for example. The crown atypically-shaped portion is preferably disposed at a position apart from the crown center RC.

The base surface b1 of the crown outer surface 12a is a convex curved surface as a whole, but has a portion that is relatively flat in the vicinity of the hosel portion <NUM>. A portion that is connected to the outer surface of the hosel portion <NUM> from the crown outer surface 12a is a concave curved surface. Accordingly, a transition portion in which the convex curved surface changes into the concave curved surface is formed on the crown outer surface 12a, and the transition portion is relatively flat. The transition portion is located at a position close to the hosel portion <NUM> and is positioned on the heel side in the crown portion <NUM>. The transition portion has a lower rigidity than that of the convex curved surface. When the transition portion is located close to the crown atypically-shaped portion, portions that easily vibrate are adjacent to each other, which tends to cause a low frequency vibration. Accordingly, in this case, the advantageous effect of the presence of the crown rib is high. From this viewpoint, it is preferable that the entirety of the crown atypically-shaped portion is located on the heel side relative to the crown center RC. The entirety of the crown atypically-shaped portion is preferably located on the heel side relative to the face center Fc.

A double-pointed arrow D1 in <FIG> shows a distance between each point on the contour line CL20 and the contour line CL4 of the crown portion <NUM>. The distance D1 is defined as a distance (shortest distance) in the transverse cross-sectional contour line. By reducing the minimum value of the distance D1, the crown atypically-shaped portion <NUM> is located closer to the outer edge portion 12e. In this case, the vibration of the crown portion <NUM> is effectively suppressed on the outer edge portion 12e side of the crown atypically-shaped portion <NUM>. Accordingly, the sound-at-impact improving effect and the sound-at-impact adjusting effect can be obtained only by the crown rib <NUM> located on the crown center side of the crown atypically-shaped portion <NUM>. From this viewpoint, the minimum value of the distance D1 is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>. The minimum value of the distance D1 may be <NUM>.

A double-pointed arrow D2 in <FIG> shows the shortest distance between the rib center line of the crown rib and the specific side. The antinode of vibration of the crown portion <NUM> caused by the crown atypically-shaped portion is positioned close to the specific side. From the viewpoint of obtaining a higher-pitched sound at impact, the distance D2 is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>. As described above, the distance D2 may be <NUM>. When a lower-pitched sound at impact is desired, the distance D2 can be increased. By changing the distance D2, the sound at impact can be effectively adjusted. The distance D2 is measured in the planar view.

From the viewpoint of enhancing the rigidity of the crown portion by the crown rib, the height Hr (<FIG>) of the crown rib is preferably greater than or equal to <NUM>, more preferably greater than or equal to <NUM>, and still more preferably greater than or equal to <NUM>. From the viewpoint of suppressing the weight of the crown rib, the height Hr of the crown rib is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>.

From the viewpoint of enhancing the advantageous effect brought by the sole rib, the height of the sole rib is preferably greater than or equal to <NUM>, more preferably greater than or equal to <NUM>, still more preferably greater than or equal to <NUM>, and yet more preferably greater than or equal to <NUM>. From the viewpoint of enhancing the advantageous effect brought by the sole rib, the sole rib may have a height higher than the height Hr of the crown rib. From the viewpoint of suppressing the weight of the sole rib, the height of the sole rib is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>. The height of the sole rib is measured in the same manner as the height Hr of the crown rib.

From the viewpoint of the degree of freedom in design of the head, the maximum height of the crown atypically-shaped portion may be greater than or equal to <NUM>, further may be greater than or equal to <NUM>, and still further may be greater than or equal to <NUM>. From the viewpoint of easy production, the maximum height of the crown atypically-shaped portion may be less than or equal to <NUM>, further may be less than or equal to <NUM>, and still further may be less than or equal to <NUM>. The maximum height of the crown atypically-shaped portion means the maximum value of the height Ht (see <FIG>).

A double-pointed arrow W2 in <FIG> shows the longest traverse length of the contour line CL20 in the planar view. The longest traverse length W2 is the maximum value of the length of a line segment S3 that extends from a first end located at a first point on the contour line CL20 to a second end located at a second point on the contour line CL20. From the viewpoint of increasing the degree of freedom in design of the head, the longest traverse length W2 is preferably greater than or equal to <NUM>, more preferably greater than or equal to <NUM>, and still more preferably greater than or equal to <NUM>. From the viewpoint of sound at impact, the longest traverse length W2 is preferably less than or equal to <NUM>, more preferably less than or equal to <NUM>, and still more preferably less than or equal to <NUM>.

From the viewpoint of increasing the degree of freedom in design of the head, the total area of the crown atypically-shaped portion in the planar view is preferably greater than or equal to <NUM><NUM>, more preferably greater than or equal to <NUM><NUM>, and still more preferably greater than or equal to <NUM><NUM>. From the viewpoint of sound at impact, the total area of the crown atypically-shaped portion in the planar view is preferably less than or equal to <NUM><NUM>, more preferably less than or equal to <NUM><NUM>, and still more preferably less than or equal to <NUM><NUM>. This total area is the area of a figure indicated by the contour line CL20. When a plurality of crown atypically-shaped portions are present, the total area is the sum total of the areas of the crown atypically-shaped portions.

A large head volume tends to cause a loud sound at impact. In addition, when dimensions of the crown portion <NUM> is larger, the crown atypically-shaped portion has a larger effect on the sound at impact. Accordingly, the crown rib of the present disclosure exhibits a higher advantageous effect when the head has a large volume. From this viewpoint, the head volume is preferably greater than or equal to <NUM> cm3, more preferably greater than or equal <NUM><NUM>, more preferably greater than or equal <NUM> cm3, more preferably greater than or equal <NUM> cm3, and still more preferably greater than or equal <NUM><NUM>. From the viewpoint of the rules of golf, the head volume is preferably less than or equal to <NUM> cm3, more preferably less than or equal to <NUM> cm3, and still more preferably less than or equal to <NUM><NUM>.

The above descriptions are merely illustrative and various modifications can be made without departing from the principles of the present disclosure.

Claim 1:
A hollow golf club head (<NUM>) comprising:
a face portion (<NUM>) that forms a striking face (10a);
a crown portion (<NUM>) that forms a crown outer surface (12a) and a crown inner surface (12b);
a sole portion (<NUM>) that forms a sole outer surface (14a) and a sole inner surface (14b); and
a hosel portion (<NUM>), wherein
the crown portion (<NUM>) includes a crown atypically-shaped portion (<NUM>) and a crown rib (<NUM>) that is disposed on the crown inner surface (12b),
the crown atypically-shaped portion (<NUM>) is a crown projection (<NUM>) that forms a projection on the crown outer surface (12a) while forming a recess on the crown inner surface (12b), or a crown recess that forms a recess on the crown outer surface (12a) while forming a projection on the crown inner surface (12b),
the crown rib (<NUM>) is disposed on a crown center side relative to a center (C1) of the crown atypically-shaped portion (<NUM>), the crown rib (<NUM>) is disposed on the crown center side relative to an entirety of the crown atypically-shaped portion (<NUM>), and
the crown rib (<NUM>) is located apart from the crown atypically-shaped portion (<NUM>).