WO2008069372A1

WO2008069372A1 - Inside structure of dimple for golf ball

Info

Publication number: WO2008069372A1
Application number: PCT/KR2007/002164
Authority: WO
Inventors: Yong-Hae Lee
Original assignee: Yong-Hae Lee
Priority date: 2006-12-06
Filing date: 2007-05-02
Publication date: 2008-06-12

Abstract

Disclosed is an inside structure of a dimple for a golf ball having formed in an outer surface thereof a plurality of dimples of a concave shape, wherein projections having a predetermined shape are projectedly formed on bottom surfaces of all or some of the dimples, and a height of the projection corresponds to 15-40% of a depth of the dimple. The height and area of a projection formed in the dimple are limited to predetermined dimensions, so that excellent performance and a long flight distance can be secured when hitting the golf ball with various golf club heads, the contact area of an impact surface when hitting the golf ball with a golf club head can be increased and the elasticity of the golf ball can be improved, and the distortion of the shape of the golf ball when coming into contact with the head of a golf club is reduced.

Description

Description INSIDE STRUCTURE OF DIMPLE FOR GOLF BALL

Technical Field

[1] The present invention relates to the inside structure of a dimple for a golf ball, and more particularly, to the inside structure of a dimple for a golf ball wherein the height and the area of a projection formed in the dimple of a golf ball are limited to predetermined dimensions so that excellent performance and a long flight distance can be secured when hitting the golf ball with various golf club heads, the contact area of an impact surface when hitting the golf ball with a golf club head can be increased, the elasticity of the golf ball can be improved, and the distortion of the shape of the golf ball when it comes into contact with the head of a golf club is reduced. Background Art

[2] The dimple of a golf ball has changed in shape with the history of golf, and has developed into the current dimple structure. The projection structures of dimples, which are recently developed, includes a structure in which a projection has a height corresponding to one half of the depth of the dimple, a structure in which projections are formed in 6-10 dimples among 20 dimples, which is the number assumed to be effectively brought into contact with a golf club head upon impact, and a structure in which such a projection is formed to occupy 30-50% of the sectional area of the dimple.

[3] In the dimple structure which is integrally formed in the golf ball, assuming that about 20 dimples are brought into contact with the golf club head upon impact, a projection having a height corresponding to one half of the depth of the dimple means that the height of the projection is measured based not on the 6-10 dimples which are formed with projections but on the depth of the 10-14 dimples which are not formed with projections.

[4] The structure, in which projections are formed in 6-10 dimples among 20 dimples, which are assumed to be effectively brought into contact with a golf club head upon impact, of course, means that the projections are formed to have a size no greater than 30-50% of the sectional area of the dimple.

[5] Also, it has been explained that it is effective for the projections to be formed to occupy a space corresponding to no greater than 30-50% of the sectional area of the respective dimples and that no projections be formed in a space corresponding to no less than 50-70% of the sectional area of the respective dimples.

[6] However, these days, golf balls are regulated in the size and weight thereof, and therefore, golf ball manufacturers manufacture and sell golf balls to conform to the regulations. Various shapes and arrangements of dimples are employed.

[7] Golf balls have their respective characteristics. The reason why golf balls having projections integrally formed in the dimples thereof have not gained popularity resides in that the size of the projections in the dimple, the distribution rate of the projections over all of the dimples, and the areas of the projections are not effectively applied to golf balls. Therefore, the golf balls do not gain popularity so far and are used only by some golfers under particular conditions. Consequently, the effects of the golf balls formed with the projections have not been appropriately conveyed to golf consumers.

[8] In a golf ball, the effect of the dimples is called a Reynolds effect. As in a baseball, which is devised to have a texture to thereby increase the flight distance, the golf ball is formed with dimples which have the shape not of a circle but of a crater, and thus far this structure prevails.

[9] The effects obtained by manufacturing a golf ball such that projections are formed in some of the dimples, which are defined on the surface of the golf ball and which have the shape of a crater on the moon, do not exert an adverse influence on the Reynolds effects, rather, they efficiently improve the Reynolds effects. These facts have been disclosed in patent documents published in various nations.

[10] The golf ball must be manufactured to have a size and weight which conform to the regulations. The number and the depth of dimples are determined depending upon the proportions of the outer part and the inner core of the golf ball.

[11] In the dimple structure of a golf ball according to the regulations, as the number of dimples increases, the depth of the dimples decreases, and as the number of dimples decreases, the depth or the area of the dimples increases.

[12] FIG. 96 is a graph representing the flight distance of a golf ball having a large number of dimples, and FIG. 97 is a graph representing the flight distance of a golf ball having a small number of dimples.

[13] Referring to FIG. 96, as the number of dimples increases, the golf ball, which is hit with a golf club head, receives a large rotation force, whereby the golf ball flies high. Referring to FIG. 97, it is to be readily understood that, as the number of dimples decreases, the golf ball, which is hit with a golf club head, flies lower than the golf ball having the increased number of dimples.

[14] Based on these facts, even assuming that the area of dimples is the same with respect to the overall area of one golf ball, as the number of dimples increases, a large rotation force is applied to the golf ball so that the golf ball flies high and a high trajectory is obtained.

[15] In the overall surface area of the golf ball, as the number of dimples increases, the golf ball encounters an increased amount of air resistance and reaches a critical Reynolds value within a short time. [16] However, when observing the effects of a golf ball that has projections formed in dimples thereof, while the flight distance of the golf ball can be increased by increasing the surface area of the golf ball, the effects are changed with respect to how a golf club hits the golf ball.

[17] Also, in general, in a golf ball having a large number of dimples, due to the regulations regarding the surface of the golf ball, the sectional area of each dimple must be decreased, and it is recognized that the golf ball, which is decreased in the sectional area of each dimple, flies while drawing a parabola having a high trajectory.

[18] The reason for this resides in that the golf club used for hitting the golf ball has a specified angle. Therefore, since the golf club having the specified angle is inserted under and hits the lower surface part of the golf ball while being swung and making a circular motion, the golf ball is hit to rotate rightward when viewed in a moving direction.

[19] At this time, the lower surface of the golf ball pushes air in the moving direction due to the presence of the dimples, and the upper surface of the golf ball pushes air in the direction opposite the moving direction due to the presence of the dimples. Therefore, due to the difference in air flow between the upper and lower surfaces of the golf ball, a lift force is generated, to thus extend the flight time of the golf ball.

[20] In a golf ball having a dimple having a small sectional area, that is, having an increased number of dimples, the air flow on the upper and lower surfaces of the golf ball is enabled as the increased number of dimples acts at an increased number of places that are influenced by the air flow.

[21] Conversely, in the golf ball having a small number of dimples, because the surface area depends upon the regulated diameter of the golf ball, the sectional area of the dimple cannot but be increased.

[22] If the golf ball has a large sectional area in this way, the golf ball can execute stable flight in a low trajectory. This was demonstrated through experiments.

[23] This can be understood as described below. In a golf ball in which lift force is generated by different air flow around the upper and lower parts of the golf ball, which flies while rotating, a large lift force can be generated when a number of dimples each having a small sectional area is used, rather than when dimples each having a large sectional area are used, to thus slow down air flow around the lower part of the golf ball and speed up air flow around the upper part of the golf ball.

[24] Then, in order to produce a golf ball having the most ideal trajectory, it is necessary to cause the sectional area of the dimple to have the two above-described effects.

[25] If the sectional area of the dimple is small and the flight of the golf ball is high, problems are encountered in that a loss of flight distance is caused, and it is difficult to send the golf ball to a target place under the influence of air flowing around the golf ball. If the sectional area of the dimple is large and the flight of the golf ball is low, problems are encountered in that the loss of flight distance is caused, and, since the golf ball rolls a lot, it is difficult to stop the golf ball at a target position.

[26] In order to cope with these problems, a golf ball having a dimple structure, in which a projection is integrally formed on the center portion of the sectional area of the dimple, has been disclosed in the art.

[27] FIG. 91 is a cross-sectional view illustrating one example of the inside structure of a dimple for a golf ball according to the conventional art, FIG. 92 is a plan view illustrating one example of the inside structure of a dimple for a golf ball according to the conventional art, FIG. 93 is a plan view illustrating another example of the inside structure of a dimple for a golf ball according to the conventional art, FIG. 94 is a diagrammatic view illustrating the pattern by which a golf ball hits a golf club, and FIG. 95 is an enlarged cross-sectional view illustrating still another example of the inside structure of a dimple for a golf ball according to the conventional art.

[28] Referring to FIGs. 91 through 93, each of projection-shaped partition walls 210 and

211 is formed on the bottom surface of a dimple 200 so that an initial front breaking effect attributable to the rotation of a golf ball can be improved and lift force can be easily generated in air flowing around the dimples formed on the upper and lower parts of the golf ball.

[29] Also, if the lift force is too large, since the flight distance decreases due to the flight angle, the partition wall is formed to decrease the lift force. In this regard, a problem is caused in that, if the partition wall is large, the effect of the partition wall is deteriorated.

[30] Referring to FIG. 94, an impacted golf ball 300 naturally rotates in a direction opposite a moving direction depending upon the angle of a golf club 400.

[31] Also, as shown in FIG. 95, a groove 42 is defined in the bottom surface of the dimple.

[32] The above-described inside structure of the dimple was devised in an attempt to ensure smooth air flow in the dimple, however, air flow is blocked by the vertical surface of the partition wall, and an air flow breaking effect by the groove defined in the dimple is poor. Disclosure of Invention Technical Problem

[33] Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide an inside structure of a dimple for a golf ball wherein the height and the area of a projection formed in the dimple of a golf ball are limited to predetermined dimensions, so that excellent performance and a long flight distance can be secured when hitting the golf ball using various golf club heads, the contact area of the impact surface when hitting the golf ball using a golf club head can be increased, the elasticity of the golf ball can be improved, and distortion of the shape of the golf ball when it comes into contact with the head of a golf club is reduced. Technical Solution

[34] In order to achieve the above object, according to one aspect of the present invention, there is provided an inside structure of a dimple for a golf ball having formed on an outer surface thereof a plurality of dimples of a concave shape, wherein projections having a predetermined shape are projectedly formed on bottom surfaces of all or some of the dimples, and a height (h) of the projection corresponds to 15-40% of the depth (D) of the dimple.

[35] In order to achieve the above object, according to another aspect of the present invention, there is provided an inside structure of a dimple for a golf ball having formed on an outer surface thereof a plurality of dimples of a concave shape, wherein, when dividing the sectional area (S ) of the dimple into three portions by drawing lines

A from the vertex of a projection to the outer periphery of the dimple, the height (h) of the projection is determined in a manner such that the sum (S + S ) of the left

B C sectional area (S ) and the right sectional area (S ), which are defined on both sides of

B C the projection, is less than an upper sectional area (S ), which is defined over the projection, thus satisfying the inequality (S + S ) < S . [36] More preferably, the sectional area (S ) of the projection corresponds to 6-25% of the sectional area (S ) of the dimple. [37] More preferably, the width (W) of the lower end of the projection is no less than two times of the height (h) of the projection. [38] More preferably, a step-shaped projecting wall is projectedly formed on a side surface of the dimple, which surrounds the projection. [39] More preferably, a groove-shaped air path is defined through the projecting wall to extend from the projection to the outer periphery of the dimple. [40] More preferably, the air path is also defined through the projection.

[41] More preferably, an air path having a concave shape is defined in the projection.

[42] More preferably, the projection is composed of a first projection and a second projection, which overlaps the first projection, and a plurality of air paths having a concave shape is defined in the second projection, thus extending upward from the bottom surface of the projection. [43] More preferably, at least the widths of lower ends or heights of the first projection and the second projection are different from each other. [44] More preferably, the air path around the projection comprises one or more paths or ridges which are formed at the same acute angular interval. [45] More preferably, the air path around the projection has a structure which has a predefined inclined surface, and the width or the interval of the air path is different on the lower end and the upper end of the projection. [46] In order to achieve the above object, according to still another aspect of the present invention, there is provided an inside structure of a dimple for a golf ball having formed on the outer surface thereof a plurality of dimples having a concave shape, wherein a sidewall structure having a predetermined shape is projectedly formed in all or some of the dimples. [47] More preferably, the sidewall structure has a plurality of projections which are projectedly formed at the same angular interval, and the sum (El + E2 + E3) of widths of the projections is less than the sum (el + e2 + e3) of widths of side surface portions of the dimple positioned between the projections. [48] More preferably, the projection has a step-shaped, a divided type or an inclined type configuration. [49] More preferably, the shape of the projection is defined in a manner such that the width (P ) of the upper end of the projection and the width (P ) of the lower end of the projection are different from each other. [50] More preferably, the sidewall structure is formed as a step-shaped sidewall structure, which is formed with at least one step. [51] More preferably, the sidewall structure has one or more air paths which are defined at the same angular interval. [52] More preferably, the width of the upper end of the air path and the width of the lower end of the air path are different from each other. [53] More preferably, the air path has both sidewalls which are formed as vertical or inclined surfaces and a bottom surface which is formed as an inclined surface, or in the corrugated sectional shape of '-'. [54] More preferably, the air path is defined at an upper end or a lower end of a side surface of the dimple. [55] More preferably, in the sidewall structure, at least one of an outer circumference and an inner circumference of a sidewall of the dimple is formed to have the corrugated sectional shape of '-'. [56] More preferably, the sidewall structure is formed to have the shape of a step, and the upper surface of the step is corrugated in the sectional shape of '-'. [57] More preferably, the sidewall structure is formed to have the shape of a step, and the side surface of the step is formed to have a curved shape or the corrugated sectional shape of '-'. [58] More preferably, the sidewall structure is formed to have the shape of a step, and the width of the upper surface of the step is gradually changed.

Advantageous Effects

[59] As is apparent from the above features, the present invention provides advantages in that the height and the area of a projection formed in the dimple of a golf ball are limited to predetermined dimensions, so that excellent performance and a long flight distance can be secured when hitting the golf ball using various golf club heads. [60] Also, the present invention provides advantages in that the contact area of an impact surface when hitting the golf ball using a golf club head can be increased, the elasticity of the golf ball can be improved, and distortion of the shape of the golf ball when it comes into contact with the head of a golf club is reduced. [61] Further, the present invention provides advantages in that the height and the width of the projection in the dimple are changed so that the flight distance and the lift of the golf ball can be increased. [62] Moreover, the present invention provides advantages in that an air path is formed in the projection of the dimple or in the side configuration of an inner wall to guide air flow in the dimple, so that the lift of the golf ball is increased. [63] Furthermore, the present invention provides advantages in that the projection of the side configuration is formed to have an inclined or curved shape to meet the tastes of a large number of golfers.

Brief Description of the Drawings [64] FIG. 1 is a perspective view illustrating the inside structure of a dimple for a golf ball in accordance with a first embodiment of the present invention; [65] FIG. 2 is a cross-sectional view illustrating the inside structure of a dimple for a golf ball in accordance with the first embodiment of the present invention; [66] FIG. 3 is a relational view illustrating the relationship between the golf ball according to the first embodiment of the present invention and a driver club; [67] FIG. 4 is a relational view illustrating the relationship between the golf ball according to the first embodiment of the present invention and an iron club; [68] FIG. 5 is an enlarged cross-sectional view illustrating the height of a projection in the inside structure of a dimple for a golf ball in accordance with the first embodiment of the present invention; [69] FIG. 6 is an enlarged cross-sectional view illustrating the area of the projection in the inside structure of a dimple for a golf ball in accordance with the first embodiment of the present invention; [70] FIG. 7 is an enlarged cross-sectional view illustrating one exemplary sectional area of a dimple in the inside structure of a dimple for a golf ball in accordance with a second embodiment of the present invention; [71] FIG. 8 is an enlarged cross-sectional view illustrating another exemplary sectional area of a dimple in the inside structure of a dimple for a golf ball in accordance with the second embodiment of the present invention; [72] FIG. 9 is an enlarged cross-sectional view illustrating the height of a projection and the sectional area of a dimple in the inside structure of a dimple for a golf ball in accordance with the second embodiment of the present invention; [73] FIG. 10 is an enlarged cross-sectional view illustrating one exemplary projection in the inside structure of a dimple for a golf ball in accordance with a third embodiment of the present invention; [74] FIG. 11 is an enlarged cross-sectional view illustrating another exemplary projection in the inside structure of a dimple for a golf ball in accordance with the third embodiment of the present invention; [75] FIG. 12 is a diagrammatic view illustrating the path of the golf ball in accordance with the third embodiment of the present invention; [76] FIG. 13 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a fourth embodiment of the present invention; [77] FIG. 14 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the fourth embodiment of the present invention; [78] FIG. 15 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the fourth embodiment of the present invention; [79] FIG. 16 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the fourth embodiment of the present invention; [80] FIG. 17 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a fifth embodiment of the present invention; [81] FIG. 18 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the fifth embodiment of the present invention; [82] FIG. 19 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the fifth embodiment of the present invention; [83] FIG. 20 is a cross-sectional view illustrating the other example of the inside st ructure of a dimple for a golf ball in accordance with the fifth embodiment of the present invention; [84] FIG. 21 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a sixth embodiment of the present invention; [85] FIG. 22 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [86] FIG. 23 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [87] FIG. 24 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [88] FIG. 25 is a plan view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [89] FIG. 26 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [90] FIG. 27 is a plan view illustrating one example of the air path defined in the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [91] FIG. 28 is a cross-sectional view illustrating the example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [92] FIG. 29 is a plan view illustrating another example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [93] FIG. 30 is a perspective view illustrating the other example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [94] FIG. 31 is a plan view illustrating a third example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [95] FIG. 32 is a cross-sectional view illustrating the third example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention; [96] FIG. 33 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a seventh embodiment of the present invention; [97] FIG. 34 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention; [98] FIG. 35 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention; [99] FIG. 36 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention; [100] FIG. 37 is a plan view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention; [101] FIG. 38 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention; [102] FIG. 39 is a diagrammatic view illustrating the path of the golf ball in accordance with the seventh embodiment of the present invention; [103] FIG. 40 is a cross-sectional view illustrating one example of the inside structure of a dimple for a golf ball in accordance with an eighth embodiment of the present invention; [104] FIG. 41 is perspective views illustrating the projections of one example of the inside structure of a dimple for a golf ball in accordance with the eighth embodiment of the present invention; [105] FIG. 42 is a cross-sectional view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the eighth embodiment of the present invention; [106] FIG. 43 is perspective views illustrating the projections of the other example of the inside structure of a dimple for a golf ball in accordance with the eighth embodiment of the present invention; [107] FIG. 44 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a ninth embodiment of the present invention; [108] FIG. 45 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention; [109] FIG. 46 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention; [110] FIG. 47 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention; [111] FIG. 48 is a plan view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention; [112] FIG. 49 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention; [113] FIG. 50 is a diagrammatic view illustrating the path of the golf ball in accordance with the ninth embodiment of the present invention; [114] FIG. 51 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a tenth embodiment of the present invention; [115] FIG. 52 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the tenth embodiment of the present invention; [116] FIG. 53 is a plan view illustrating still another example of the inside structure of a dimple for a golf ball in accordance with the tenth embodiment of the present invention; [117] FIG. 54 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with an eleventh embodiment of the present invention; [118] FIG. 55 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the eleventh embodiment of the present invention; [119] FIG. 56 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a twelfth embodiment of the present invention; [120] FIG. 57 is a diagrammatic view illustrating the path of the golf ball in accordance with the example of the twelfth embodiment of the present invention; [121] FIG. 58 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the twelfth embodiment of the present invention; [122] FIG. 59 is a diagrammatic view illustrating the path of the golf ball in accordance with the other example of the twelfth embodiment of the present invention; [123] FIG. 60 is a perspective view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a thirteenth embodiment of the present invention; [124] FIG. 61 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [125] FIG. 62 is a perspective view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [126] FIG. 63 is a cross-sectional view illustrating the first example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [127] FIG. 64 is a perspective view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [128] FIG. 65 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [129] FIG. 66 is a plan view illustrating one example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [130] FIG. 67 is a cross-sectional view illustrating the example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [131] FIG. 68 is a plan view illustrating another example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [132] FIG. 69 is a plan view illustrating a third example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [133] FIG. 70 is a diagrammatic view illustrating the path of the golf ball in accordance with the thirteenth embodiment of the present invention; [134] FIG. 71 is a plan view illustrating one example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [135] FIG. 72 is a cross-sectional view illustrating the example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [136] FIG. 73 is perspective views illustrating various shapes of the side configuration of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [137] FIG. 74 is a cross-sectional view illustrating another example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [138] FIG. 75 is a cross-sectional view illustrating a third example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [139] FIG. 76 is a cross-sectional view illustrating a fourth example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention; [140] FIG. 77 is a cross-sectional view illustrating a fifth example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[141] FIG. 78 is a plan view illustrating one variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[142] FIG. 79 is a cross-sectional view illustrating the variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[143] FIG. 80 is a plan view illustrating another variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[144] FIG. 81 is a cross-sectional view illustrating the other variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[145] FIG. 82 is a cross-sectional view illustrating a third variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[146] FIG. 83 is a cross-sectional view illustrating a fourth variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention;

[147] FIG. 84 is a plan view illustrating one example of the side configuration of the inside structure of a dimple for a golf ball in accordance with a fourteenth embodiment of the present invention;

[148] FIG. 85 is a cross-sectional view illustrating the example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention;

[149] FIG. 86 is a plan view illustrating another example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention;

[150] FIG. 87 is a cross-sectional view illustrating the other example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention;

[151] FIG. 88 is a plan view illustrating a third example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention;

[152] FIG. 89 is a cross-sectional view illustrating the third example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention; [153] FIG. 90 is a diagrammatic view illustrating the path of the golf ball in accordance with the fourteenth embodiment of the present invention;

[154] FIG. 91 is a cross-sectional view illustrating one example of the inside structure of a dimple for a golf ball according to the conventional art;

[155] FIG. 92 is a plan view illustrating the example of the inside structure of a dimple for a golf ball according to the conventional art;

[156] FIG. 93 is a plan view illustrating another example of the inside structure of a dimple for a golf ball according to the conventional art;

[157] FIG. 94 is a diagrammatic view illustrating the pattern by which a golf ball hits a golf club;

[158] FIG. 95 is an enlarged cross-sectional view illustrating a third example of the inside structure of a dimple for a golf ball according to the conventional art;

[159] FIG. 96 is a graph representing the flight distance of a golf ball having a large number of dimples; and

[160] FIG. 97 is a graph representing the flight distance of a golf ball having a small number of dimples.

[161] <Description of Reference Numerals for Main Parts of Drawings>

[162] 10: golf ball 11: dimple

[163] 12: projection 13: protrusion

[164] 14: air path 20: driver club head

[165] 30: iron club head

Best Mode for Carrying Out the Invention

[166] Hereafter, a first preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[167] FIG. 1 is a perspective view illustrating the inside structure of a dimple for a golf ball in accordance with a first embodiment of the present invention, FIG. 2 is a cross- sectional view illustrating the inside structure of a dimple for a golf ball in accordance with the first embodiment of the present invention, FIG. 3 is a relational view illustrating the relationship between the golf ball according to the first embodiment of the present invention and a driver club, FIG. 4 is a relational view illustrating the relationship between the golf ball according to the first embodiment of the present invention and an iron club, FIG. 5 is an enlarged cross-sectional view illustrating the height of a projection in the inside structure of a dimple for a golf ball in accordance with the first embodiment of the present invention, and FIG. 6 is an enlarged cross- sectional view illustrating the area of the projection in the inside structure of a dimple for a golf ball in accordance with the first embodiment of the present invention.

[168] As shown in FIGs. 1 and 2, in the inside structure of a dimple for a golf ball in accordance with the present embodiment, a plurality of dimples 11 having a concave shape is formed in the outer surface of a golf ball 10, and a projection 12 having a predetermined shape is projectedly formed on the center portion of the bottom surface in all or some of the of the dimples 11.

[169] The golf ball 10 has an outer virtual circumference (a) which defines the outer shape, that is, the outer diameter of the golf ball 10, and an inner virtual circumference (b), which is defined as being spaced apart from the outer virtual circumference (a) by a predetermined interval and which connects the bottom surfaces of the dimples 11 with one another. The predetermined interval between the outer virtual circumference (a) and the inner virtual circumference (b) defines the depth (D) of the dimples 11.

[170] Preferably, the dimple 11 has a uniform shape selected from among various shapes, such as a circular or a polygonal shape, to ensure the balance of the golf ball 10. Also, in the same manner as the dimple 11, it is preferred that the projection 12 have a uniform shape selected from among various shapes, such as a circular or a polygonal shape, to ensure the balance of the golf ball 10.

[171] Mentioning the kinds of clubs used for striking golf balls, there are driver clubs, mainly used for tee shots, so-called "wood" clubs, typically made of metal, and iron clubs for hitting a golf ball over a long distance, and putters. When viewing the head surfaces of wood clubs and driver clubs, it can be seen that the surfaces are smooth in order to render a small amount of spin. In the case of iron clubs, in order to cause a large amount of spin, a number of grooves are defined in a horizontal direction.

[172] As can be readily understood, considering the fact that the size, the distribution and the area of the projections 12 in the dimples 11 defined in the golf ball 10 are determined in consideration of existing clubs, the inventions related therewith can be considered most effective by golfers.

[173] Therefore, when making a drive tee shot, it is advantageous for the distribution of the projections 12 in the dimples 11 of the golf ball 10 to include an increased number of projections 12, the projections 12 having an increased height, for a given total number of dimples 11.

[174] As shown in FIG. 3, in the relationship between the dimples 11 of the golf ball 10 and a driver club head 20, it is to be appreciated that the proportion of the dimples 11 occupied by the projections 12 is small, and that the impact is increased approaching the outer circumference along the depth of the respective dimples 11.

[175] In order to increase the impact area 21, while it is preferred that the number and the height of the projections 12 be increased, since adverse effects are caused when realizing a low level of spin, the number of the projections 12 must be flexibly adjusted.

[176] As shown in FIG. 4, when making an iron shot, it can be observed that an iron club head 30 has several tens of transverse fine grooves 32 and relatively wide and deep transverse head grooves 31.

[177] Due to the presence of the fine grooves 32, which almost cannot be discerned by the eyesight of a person and can be perceived only by touch, and the large head grooves 31, unlike the case of making a drive shot, in which the golf ball 10 is hit on the side thereof, the golf ball 10 is struck while being moved downward along a relatively steep slope, and similar to the case of the drive shot, the golf ball 10 has a substantial impact surface due to the presence of the iron club head 30 which is designed to have an average inclination angle of 25-45°.

[178] Usually, in the golf ball 10 which has about 600 dimples, the golf ball 10 has an impact surface which corresponds to the summed area of about twenty dimples 11. Upon impact, the head groove 31 of the iron club head 30 is fitted between the crest of the dimple 11 and the boundary surface of a groove, which defines the depth of the dimple 11.

[179] Here, the projections 12 in the dimples 11 perform their functions. The projections

12 aid in effectively realizing a desired level of spin in the head grooves 31 and actively react in order that the fine grooves 32 defined in the iron club head 30 obtain maximum rotational force.

[180] In this regard, as a result of research that has been conducted on the basis of the fact that the proportion of the summed area of the projections 12, which is determined by the height and the size of the projections 12 in the dimples 11, can play an important role in defining the dependence on the size of the fine grooves 32 of the iron club head 30, in the present invention, the height and the area of the projection 12 in the dimple 11 are limited in such a way as to create optimal conditions.

[181] As shown in FIG. 5, it is preferred that the height (h) of the projections 12 formed in the dimples 11 correspond to 15-40% of the depth (D) of the dimples 11. Also, it is further preferred that the height (h) of the projections 12 formed in the dimples 11 correspond to 15-35% of the depth (D) of the dimples 11.

[182] For example, when comparing golf balls having two respective different projections, that is, one golf ball which is formed with projections having a height corresponding to about 42% of the dimple depth (D) and the other golf ball which is formed with projections having a height corresponding to about 16% of the dimple depth (D), the golf ball having the projections of 16% height can react with both the fine grooves 32 and the head grooves 31 of the iron club head 30, as shown in FIG. 4, and the golf ball having the projections of 42% height can react only with the head grooves 31.

[183] Accordingly, since a golf ball having projections formed to be higher than 35% of the dimple depth (D) is deteriorated in reactivity and a golf ball having projections formed to be lower than 15% of the dimple depth (D) has poor reactivity, it is preferred that the projections 12 be formed to have a height corresponding to 15-35% of the dimple depth (D).

[184] Further, while the impact area increases as the area of the crest of each dimple 11 increases, the summed surface area of all of the dimples 11 of the golf ball 10 decreases. In order to increase both the area of the crest of the dimple 11 and the summed surface area of all of the dimples 11, as many small-sized dimples 11 must be formed as possible.

[185] However, in this case, the accomplishment of a desired level of spin in the golf ball

10 and a Reynolds critical surface is impeded, whereby another problem is caused. Therefore, the desired level of spin cannot be achieved even by friction with the fine grooves 32 and the head grooves 31 of the club head.

[186] Similar to this, even when the height of the projection 12 corresponds to 35% of the dimple depth (D), the effect of the spin is deteriorated in proportion to the effect of the crest of the dimple 11, and while the impact effect is increased, an adverse influence is imposed in accomplishing and maintaining the Reynolds critical surface.

[187] As the dimples 11 and the projections 12 in the dimples 11 have different effects in the golf ball 10 depending upon the number of dimples 11, the area of the projection 12 in the dimple 11 cannot but be a very important subject matter of the invention.

[188] Moreover, as shown in FIG. 6, the sectional area S of the projection 12 can be generally adjusted within the range of 6-25% of the sectional area S of the dimple in the manufacture of the golf ball 10. Therefore, it is preferred that the sectional area S of the projection 12 correspond to 6-25% of the sectional area S of the dimple.

[189] In particular, it is further preferred that the golf ball 10 formed with the projection

12 have a size which corresponds to 8-24% of the sectional area S of the dimple, since it actively reacts with the fine grooves 32 and the head grooves 31 of the iron club head 30.

[190] In detail, when compared to the area of a conventional dimple, since the configuration of the projection, which has an area corresponding to 25-50% of a conventional dimple, has a high crest in the dimple when making a drive shot, while advantages are provided in increasing the impact area, a disadvantage is faced in precisely placing the golf ball on a green when making an iron shot.

[191] Hence, a golf ball, which has a projection formed wider than 25% of the sectional area S of the dimple, is deteriorated in stroke accuracy, and a golf ball, which has a projection formed narrower than 6% of the sectional area S of the dimple, has a small effect on the stroke. Therefore, it is preferred that the projection be formed to correspond to 6-25% of the sectional area S of the dimple.

[192] Accordingly, by effectively limiting the height and the size of the projections 12 in the dimples 11 in order to enable effective management of a course by making an iron shot, completion of a drive shot having a low level of spin and maintenance of duration of flight within a Reynolds critical angle through rendering a large curved surface, improved results can be obtained.

[193] Also, it is preferred that the number of the dimples be less than 400 so as to keep the sectional area S of the dimple 11 large to some extent.

A

[194] That is to say, after generating a low trajectory flight through increasing the sectional area S of the dimple 11, a dimple having a projection is formed such that the

A projection has small sectional areas S and S defined on left and right sides, spanning from the distal end of the projection 12 formed in each dimple 11 to the outer circumference of the dimple. This structure of the dimple has been devised to create air flow capable of performing multiple functions. [195] Thus, since the effect of the sectional area S of the dimple 11 and the effect of the

A small sectional areas S and S on the left and right sides are simultaneously provided, parabolic motions of middle and high trajectories can be induced.

[196] In a golf ball in which a projection 12 is formed to correspond to one half of the depth (D) of the dimple 11, in order to form the projection 12 corresponding to one half of the dimple depth (D) when viewed from the sectional area S of the dimple, first, the projection 12 must be formed such that it has a size capable of preventing the projection 12 from being damaged when the golf ball is struck by the golf club. Next, when the left sectional area S and the right sectional area S are summed, there is a

B A difference between the summed sectional area and the overall sectional area S of the

A dimple, which corresponds to an upper sectional area S . The effect is represented in association with the upper sectional area S .

[197] Hence, as the size of the upper sectional area S increases, a high flight effect and a low flight effect, which are represented by the sectional area S of the dimple, can be

A advantageously accommodated.

[198] As a consequence, the height (h) of the projection, which corresponds to about 25% of the dimple depth (D) of the golf ball, that is to say, the formation of the projection corresponding to one half, is preferably accomplished in a manner such that, even when considering the error between the dimension of a lower mold and an actually manufactured product due to shrinkage and the size tolerance accepted from a manufacturer, the height (h) of the projection is made to correspond to 15-35% by subtracting 15% from the projection size corresponding to 50%.

[199] In the sectional area S of each dimple, the left sectional area S and the right sectional area S , viewed from the top point of the projection 12 to the outer circumference of the dimple, function in a manner such that the upper sectional area S above the projection creates air flow under the influence of the sectional area S of the dimple in the motion of the golf ball in the air, which travels while rotating. The left sectional area S and the right sectional area S are influenced by the projection 12 rather than the sectional area S of the dimple to create an amount of air flow within a

A small sectional area through 360°.

[200] Therefore, in general, in the present embodiment, a dimple having a sectional area which corresponds to a dimple depth of about 0.18-0.24 mm when 430 dimples are provided on an area which is greater than a predetermined value, is considered as a dimple having a reference sectional area.

[201] Actually, the reason why golf balls having about 430 dimples are predominantly distributed is because they can follow the most appropriate trajectory.

[202] As described above, when viewed with respect to the reference sectional area having about 400 dimples, if a sectional area is larger than the reference sectional area, a golf ball flies while forming a parabola having a low trajectory, and if a sectional area is less than the reference sectional area, a golf ball files while forming a parabola having a high trajectory.

[203] Hereafter, a second preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[204] FIG. 7 is an enlarged cross-sectional view illustrating one exemplary sectional area of a dimple in the inside structure of a dimple for a golf ball in accordance with a second embodiment of the present invention, FIG. 8 is an enlarged cross-sectional view illustrating another exemplary sectional area of a dimple in the inside structure of a dimple for a golf ball in accordance with the second embodiment of the present invention, and FIG. 9 is an enlarged cross-sectional view illustrating the height of a projection and the sectional area of a dimple in the inside structure of a dimple for a golf ball in accordance with the second embodiment of the present invention.

[205] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the first embodiment, and detailed descriptions thereof will be omitted herein.

[206] Referring to FIGs. 7 and 8, in the overall sectional area S of a dimple, an upper

A sectional area S adjusts the flow of a predetermined amount of air in upper and lower parts, and motion through 360° in a left sectional area S and a right sectional area S serves to adjust upward and downward air flow in the 400 respective dimples. At this time, since the effect is substantial, the sum of the left sectional area S and the right

B sectional area S must always be less than the upper sectional area S .

[207] Accordingly, in this case, ideal flight along a parabolic trajectory can be obtained.

In other words, in the left sectional area S B , the right sectional area S C and the upper sectional area S , which constitute the sectional area S of the dimple, as long as the summed area of the left sectional area S and the rig ^σht sectional area S c is less than the upper sectional area S , flight along the most ideal trajectory can be obtained. [208] When (S + S ) < S and (S + S ) = S , while a difference can be present

B C D B C D according to the shape of the projection, substantially, various sectional configurations can be adopted depending upon the height of the projection, the depth of the dimple, and the diameter of the dimple. When the projection has a shape in which the width (W) of the bottom of the projection is at least two times greater than the height (h) of the projection, the projection can be prevented from being damaged, and the dimple area satisfying (S + S ) < S can be defined at the most ideal height of the projection

B C D corresponding to 25%.

[209] Further, as shown in FIG. 9, in this case, by forming the projection such that two times the height (h) of the projection is less than or equal to the width (W) of the projection bottom ((2 x h) < W), this can help satisfy the inequality (S + S ) < S .

B C D

Therefore, it is preferred that the width (W) of the projection bottom correspond to two times the height (h) of the projection.

[210] Hereafter, a third preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[211] FIG. 10 is an enlarged cross-sectional view illustrating one exemplary projection in the inside structure of a dimple for a golf ball in accordance with a third embodiment of the present invention, FIG. 11 is an enlarged cross-sectional view illustrating another exemplary projection in the inside structure of a dimple for a golf ball in accordance with the third embodiment of the present invention, and FIG. 12 is a diagrammatic view illustrating the path of the golf ball in accordance with the third embodiment of the present invention.

[212] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the second embodiment, and detailed descriptions thereof will be omitted herein.

[213] Referring to FIGs. 10 and 11, in a golf ball according to the present embodiment, in order to form a double air pocket by means of a projection, the inside structure of a dimple 11 is preferably configured in a manner such that a step-shaped protrusion 13 is formed around a projection 12.

[214] In the aforementioned embodiment, the inequality (S + S ) < S , which represents

B C D the relationship between sectional areas, is satisfied, or the width (W) of the projection bottom must correspond to two times of the height (h) of the projection. However, in the present embodiment, since the dimple side structure including the left sectional area S and the right sectional area S is formed to have the shape of a step, the sum of a first left sectional area S B ', a second left sectional area S B ", a first right sectional area

S C ' and a second rig °ht sectional area S C " is less than an u ^rp^rper sectional area S D .

[215] Accordingly, in the dimple inside structure of the present embodiment, the inequality (S '+ S " + S ' + S ") < S , which represents the relationship between sectional areas, is satisfied. This can be made possible without the need to establish the relationship between the area and the height of the projection.

[216] Further, as shown in FIG. 12, in the golf ball having this dimple inside structure, due to the fact that a double air pocket is formed in the upper part of the golf ball, an increased amount of air can be directed upward, and a lower double air pocket directs an increased amount of air in the opposite direction, which helps generate a greater lift force.

[217] Due to these facts, while air lift force is applied in a three-staged pattern when a side is inclined, in the present embodiment, as the step-shaped protrusion 13 is formed around the projection, air lift force can be applied in a five-staged pattern. As a consequence, since the trajectory can be further stabilized and an impact area can be increased due to the presence of the protrusion 13, force transmission rate and flight distance can be increased.

[218] Further, because the protrusion 13 is formed to aid in the relative increase of the u ^rp^rper sectional area S D , the left sectional area S B and the rig °ht sectional area S c are caused to be decreased. [219] Hereafter, a fourth preferred embodiment of the present invention will be described in detail with reference to the attached drawings. [220] FIG. 13 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a fourth embodiment of the present invention, FIG.

14 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the fourth embodiment of the present invention, FIG.

15 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the fourth embodiment of the present invention, and FIG.

16 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the fourth embodiment of the present invention.

[221] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the third embodiment, and detailed descriptions thereof will be omitted herein.

[222] Referring to FIGs. 13 through 16, in a golf ball according to the present embodiment, a protrusion 13, which is formed on the inclined side surface in a dimple, has the shape of a step. The protrusion 13 can be formed to have one step portion or two or more step portions.

[223] Also, in FIG. 12, which is the flight status view of a golf ball illustrating the trajectory of the golf ball and the air flow in the upper and lower parts of the golf ball, because an increased amount of air flows in a backward direction in the lower part of the golf ball and air flows in a forward direction in the upper part of the golf ball, a great lift force can be generated.

[224] For example, it is preferred that the protrusion 13 be formed with three or more step portions, since the amount of airflow can be increased thereby.

[225] Accordingly, due to the fact that the protrusion 13 having at least one step portion is formed on the inclined side surface in the dimple, the most ideal trajectory can be obtained compared to the flight of a conventional golf ball.

[226] Further, as shown in FIGs. 15 and 16, at least one groove-shaped air path 14, which extends from the projection 12 to the outer periphery of the dimple 11, is defined through the protrusion 13 to ensure smooth air flow in the dimple.

[227] Namely, in the case of the golf ball having the dimple which has the step-shaped sidewall structure, when lift force is too large in the traveling direction of the golf ball, in order to induce the most appropriate air flow by the lift force, by defining at least one air path 14 in such a way as to extend through the protrusion 13, it is possible to provide a golf ball which can be used in a seaside area, where the golf ball should be varied to fly at a low height, or can be used for a golfer who has a swing form biased towards a high trajectory.

[228] In the case where the width rl, r2 and r3 of the air paths 14 is too large, the air flow is likely to be disintegrated. Therefore, it is preferred that the width rl, r2 and r3 of the respective air paths 14 be less than the width Rl, R2 and R3 of the divided portions of the protrusion 13.

[229] Of course, it is to be readily understood that the sum (rl + r2 + r3) of the widths of the air paths 14 is less than the sum (Rl + R2 + R3) of the widths of the divided portions of the protrusion 13 ((rl + r2 + r3) < (Rl + R2 + R3)).

[230] Specifically, in the case where the projection formed in the dimple of the golf ball is a projection 12' which is divided into portions that correspond to the number of air paths 14, since the respective air paths 14 communicate with one another, smooth air flow in the dimple is ensured, whereby optimized air flow can be obtained while the golf ball travels.

[231] Referring to FIG. 95, in the inside structure of a dimple for a golf ball according to the conventional art, in which a groove 42 is defined at the center portion in the bottom surface of a dimple 41 instead of a projection, when viewed on the overall sectional area of a dimple that has a width of (Wl), the width (e) of the left portion of the bottom surface or the width e' of the right portion of the bottom surface can be greater than the width (g) of the groove 42 (e > g or e' > g), or the sum of the widths (e + e') can be greater than the width (g) of the groove 42 ((e + e') > g). The dimple depth (dl) is in the range of 0.18-0.24 mm which corresponds to an average dimple depth. In this case, the golf ball has a type of double dimple in which the depth (d2) of the groove 42 is less than the depth (dl) of the dimple so that a groove 42 having the shape of another dimple is defined in the dimple.

[232] However, as shown in FIG. 10, in the present embodiment, the dimple depth (D) corresponds to 0.18-0.24 mm on average. In this case, since the width D ' and D 'of

B C the bottom of the dimple is greater than the width D " and D " of the protrusion, the width D ' and D ' of the bottom can be regarded as corresponding not to a groove but to the surface of the bottom, and the width D " and D " of the protrusion can be

B C regarded as corresponding to a shoulder.

[233] Therefore, in the dimple for a golf ball according to the present embodiment, a projection is formed in a dimple, and a step-shaped protrusion is formed on the side surface of the dimple, defining a shoulder. In the dimple for a golf ball according to the conventional art, a groove having a certain depth is defined in the dimple as another dimple. As a consequence, the present invention and the conventional art are different from each other.

[234] In this way, in the present embodiment, the projection is formed at the center portion on the bottom surface of the dimple, and depending upon the difference between the width of the bottom and the height of the projection, the inequality (S B + S

C ) < SD can be satisfied between sectional areas. While the ineq ⁿuality ^J (S B + S C ) < S D can be satisfied in the case of a hemi- spherical dimple, which has a curved side surface, the inequality (S + S ) < S cannot be satisfied in the case of a dimple which has a countersunk shape. Thus, in the latter case, the bottom surface of the projection can be widened and the height of the projection can be decreased, so that the inequality (S + S ) < S is satisfied, or the protrusion can be formed on the side surface of the

B C D dimple.

[235] Hereafter, a fifth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[236] FIG. 17 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a fifth embodiment of the present invention, FIG. 18 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the fifth embodiment of the present invention, FIG. 19 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the fifth embodiment of the present invention, and FIG. 20 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the fifth embodiment of the present invention.

[237] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the fourth embodiment, and detailed descriptions thereof will be omitted herein.

[238] In a golf ball according to the present embodiment, the shape of a projection 12", which is formed on the bottom surface of the dimple 11, is different from that of the projection 12' according to the fourth embodiment. Concretely speaking, air paths 14 are defined on the projection 12" such that the air paths open and widen in an upward direction.

[239] Also, air paths 14 are partially defined on a step-shaped protrusion 13', which is formed in the dimple 11 so that the amount of air flow can be adjusted in the dimple. Accordingly, the present embodiment can be effectively applied when it is necessary to adjust the amount of air flow in a dimple depending upon the condition of a field.

[240] Hereafter, a sixth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[241] FIG. 21 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a sixth embodiment of the present invention, FIG. 22 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 23 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 24 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 25 is a plan view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 26 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 27 is a plan view illustrating one example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 28 is a cross-sectional view illustrating the example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 29 is a plan view illustrating another example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 30 is a perspective view illustrating the other example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, FIG. 31 is a plan view illustrating a third example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention, and FIG. 32 is a cross-sectional view illustrating the third example of the air path around the inside structure of a dimple for a golf ball in accordance with the sixth embodiment of the present invention.

[242] Referring to FIGs. 21 through 26, in the inside structure of a dimple for a golf ball according to the present embodiment, a projection 50 is formed at the center portion on the bottom surface 41 of a dimple 40, and air paths having a concave shape are defined around the projection 50.

[243] In particular, the projection 50 is formed on the bottom surface 41 of the dimple 40 to have a height corresponding to 15-35% of the depth of the dimple 40. Unlike other projections, in the case of the projection 50, air paths are defined on the projection 50 such that they extend in one or more directions which define an acute angle between them.

[244] The projection is formed to influence the lift force for a golf ball by causing the air flowing past the bottom surface of the dimple to rapidly move around the projection formed on the bottom surface of the dimple when the hit golf ball flies. The sectional shape of the projection can be changed in a variety of ways to increase the influence.

[245] Specifically, the projection 50 of the present embodiment is composed of a first projection 51, which is formed on the bottom surface of the dimple, and a second projection 52, which overlaps the first projection 51. The plurality of air paths is defined on the second projection 52 to extend upwards from the bottom surface of the projection 50 and to have a concave shape.

[246] Referring to FIGs. 21 and 22, the air paths are defined in the projection such that the line extending along the ridge of the air path and the line extending along the base of the air path meet each other on the upper end of the projection, and the line extending along the ridge of the air path has a greater radial dimension than the line extending along the base of the air path on the bottom of the projection.

[247] Referring to FIGs. 23 and 24, the air paths are defined in the projection such that the line extending along the ridge of the air path and the line extending along the base of the air path meet each other at the bottom of the projection, and the line extending along the ridge of the air path is spaced apart from the line extending along the base of the air path on the upper end of the projection.

[248] Referring to FIGs. 25 and 26, the air paths are defined in the projection such that the line extending along the ridge of the air path is spaced apart from the line extending along the base of the air path.

[249] Therefore, various embodiments can be contemplated such that the line extending along the ridge of the air path and the line extending along the base of the air path meet each other at the upper end of the projection, meet each other at the bottom of the projection, or do not meet each other, which is an intermediate form.

[250] Accordingly, it is preferred that the lower end widths f and f and/or the heights h and h of the first projection and the second projection be different from each other. Also, the air paths may be formed on the projection such that they extend in one or more directions, which define an acute angle between them.

[251] Referring to FIGs. 27 through 30, steps 53 are formed on the outer surface of the projection 50 in such a way as to increase or decrease lift force, so that the directionality of the golf ball can be maintained for any type of stroke.

[252] Also, it is preferred that the air paths be defined in a manner such that the widths k and k and/or the intervals c and c of the air paths on the upper and lower ends of the projection are different from each other, thus ensuring smooth air flow in the dimple.

[253] The projections shown in FIGs. 21 through 30 may be combined with one another to create various projections having different shapes.

[254] In the shapes of the projections shown in FIGs. 27 and 32, grooves and steps are formed in the respective projections such that the widths c and c of the grooves and steps at the radially outer and inner ends of the grooves and steps are different from or the same with each other. Therefore, as described above, as air flows around the projection, air can be introduced into the air paths to be increased or decreased in flow speed to thereby exert an influence on the increase or decrease of the lift force.

[255] FIGs. 31 and 32 illustrate a projection which represents an intermediate form. In this projection, air paths having a predetermined height are defined on the projection to extend from the bottom surface to the upper end of the projection. Since the outer circumference and the inner circumference of the projection have a predetermined interval, the grooves and the steps have the same height.

[256] Here, in the case where the grooves and the steps are formed by removing or adding material from or to the projection, as shown in FIG. 27, if the area or the width of the groove is greater than the area or width of the step, on the surface portion of the projection, as shown in FIG. 30, the grooves define a circumference, and the steps are viewed as shoulders on the entire projection.

[257] Accordingly, in the present invention, since the groove or the step can be explained as being different names for the same thing, which has a small area in the entire projection or on the steps or the rolling surfaces of a side part, which will be described later, the steps and the grooves can be understood as constituting the same component element.

[258] Thus, although one thing is described, if the area ratio is reversed, one thing can serve as the other thing, and thus only one of the groove or the step is described.

[259] Hereafter, a seventh preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[260] FIG. 33 is a plan view illustrating the example of the inside structure of a dimple for a golf ball in accordance with a seventh embodiment of the present invention, FIG. 34 is a cross-sectional view illustrating one example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention, FIG. 35 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention, FIG. 36 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention, FIG. 37 is a plan view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention, FIG. 38 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the seventh embodiment of the present invention, and FIG. 39 is a diagrammatic view illustrating the path of the golf ball in accordance with the seventh embodiment of the present invention.

[261] Referring to FIGs. 33 and 34, in the inside structure of a dimple for a golf ball according to the present embodiment, a sidewall structure having a predetermined shape is projectedly formed on the side surface 111 of a dimple 110. The sidewall structure has a plurality of projections 150. The inside structure of a dimple is defined in such a way as to remove air paths that occur with a conventional golf ball.

[262] As the projections 150 of the dimple are formed as projecting sidewalls, as can be readily seen from FIG. 33, the projections 150 serve as partition walls of the dimple having predetermined widths El, E2 and E3.

[263] Therefore, since it can be appreciated that the sum (El + E2 + E3) of the widths of the projections 150 is less than the sum (el + e2 + e3) of the widths of the portions of the side surface 111, which are placed between the projections 150, a relationship (El + E2 + E3) < (el + e2+ e3) can be derived.

[264] In a conventional golf ball, if the side inclined surface or the side surface is wide, the air paths can be meaningfully used. However, if the air paths become wide, the air paths define the side surface of the dimple, and, as shown in FIG. 33, the projections 150 of the dimple serve as side partition walls that divide the inside space of the dimple into parts.

[265] Referring to FIG. 39, in a golf ball which flies while rotating upon being hit with a golf club, the shape of the projections 150, which serve as partition walls formed in the dimple, can reduce the generation of lift force through minimizing the effect of vortex flow due to the presence of the dimples when the creation of vortex flow is abnormally increased under the influence of the dimples positioned on the upper and lower parts of a conventional golf ball.

[266] This embodiment, in which the generation of lift force is minimized in this way, applies when the number of dimples of a golf ball is greater than the average number of dimples, which corresponds to 360-430, or when the number of dimples of a golf ball is less than the average number of dimples and the sectional area of the dimple increases, so that it is required that the sectional area of the dimple be decreased, but that the effect obtained by the dimple having a large sectional area be accomplished.

[267] Referring to FIGs. 35 through 38, in another example of the present embodiment, projections 151 and 152 are formed on the side surface 111 of a dimple in such a way as to face each other. Preferably, the projections can be formed as step-shaped projections 151 or inclined type projections 152.

[268] Therefore, since it is possible to adjust the amount of vortex flow of air which is created in the dimple, the magnitude of lift force can be controlled in conformity with the direction or the volume of wind, whereby optimal flight of a golf ball can be maintained.

[269] Also, it is preferred that the sectional area S of the projection be less than one half of the sectional area S of the dimple.

[270] Hereafter, an eighth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[271] FIG. 40 is a cross-sectional view illustrating one example of the inside structure of a dimple for a golf ball in accordance with an eighth embodiment of the present invention, FIG. 41 is perspective views illustrating the projections of one example of the inside structure of a dimple for a golf ball in accordance with the eighth embodiment of the present invention, FIG. 42 is a cross-sectional view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the eighth embodiment of the present invention, and FIG. 43 is perspective views illustrating the projections of the other example of the inside structure of a dimple for a golf ball in accordance with the eighth embodiment of the present invention.

[272] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the seventh embodiment, and detailed descriptions thereof will be omitted herein.

[273] Referring to FIGs. 40 through 43, a dimple according to the present embodiment has a hemi- spherical shape and a countersunk shape. Preferably, the height of the side projection 150, which is formed in the dimple 110, corresponds to the depth (D) of the dimple or one half of the depth (D) of the dimple.

[274] In particular, as shown in (a) through (e) of FIG. 41 and (a) through (f) of FIG. 43, the side projection 150 has a step-shaped, a divided type, or an inclined type configuration.

[275] That is to say, in the two types of dimples, at least two projections 150 having the same angle are integrally formed by oppositely arranging the projections 150 on the side surface 111. The projection 150 can have a height which corresponds to the depth of the dimple or one half of the depth of the dimple. Therefore, the projection 150 can be formed to have various shapes.

[276] Hereafter, a ninth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[277] FIG. 44 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a ninth embodiment of the present invention, FIG. 45 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention, FIG. 46 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention, FIG. 47 is a cross-sectional view illustrating the other example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention, FIG. 48 is a plan view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention, FIG. 49 is a cross-sectional view illustrating the third example of the inside structure of a dimple for a golf ball in accordance with the ninth embodiment of the present invention, and FIG. 50 is a diagrammatic view illustrating the path of the golf ball in accordance with the ninth embodiment of the present invention.

[278] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the eighth embodiment, and detailed descriptions thereof will be omitted herein.

[279] Referring to FIGs. 44 through 49, in the inside structure of a dimple for a golf ball according to the present embodiment, a projection is formed in a manner such that the width P of the upper end of the projection and the width P of the lower end of the projection are different from each other.

[280] For example, the projection of the present embodiment includes a triangle-shaped projection 153, which has the transverse sectional shape of a triangle, an inverted triangle-shaped projection 154, which has the transverse sectional shape of an inverted triangle, and a diamond- shaped projection 155, which has the transverse sectional shape of a diamond.

[281] In the present embodiment, the air flow around a golf ball can be controlled by varying the width of the projection.

[282] In the projections 153, 154 and 155 of the dimple, as shown in FIG. 50, when viewed from the top of a flying golf ball, when leftward spin is applied to the golf ball, the backward flow T on the left side promotes the easy flow of wind in the backward direction, and the vortex flow T on the right side resists the flow of wind. Therefore, in this case, lift force continuously moves the golf ball leftward in such a way as to hook the ball.

[283] In the inside structure of a dimple, as shown in FIGs. 89 through 92, even when narrow air paths are defined in the two types of projections or in the steps, if the sidewall is larger than the air paths, the tendency to form the hook is increased.

[284] Therefore, in the case in which the sidewall is smaller than the size of the air paths, as can be readily seen from the flying pattern of the golf ball according to the present embodiment shown in FIG. 38, since the undesired movement of the golf ball can be minimized, it is possible to easily hit the golf ball to a desired place.

[285] Hereafter, a tenth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[286] FIG. 51 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a tenth embodiment of the present invention, FIG. 52 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the tenth embodiment of the present invention, and FIG. 53 is a plan view illustrating still another example of the inside structure of a dimple for a golf ball in accordance with the tenth embodiment of the present invention.

[287] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the ninth embodiment, and detailed descriptions thereof will be omitted herein.

[288] Referring to FIGs. 51 through 53, in the inside structure of a dimple for a golf ball according to the present embodiment, a plurality of projections is formed at the same angular interval as oblique line-shaped projections 156 and 157, which are formed to deviate leftward or rightward by a predetermined angle α with respect to a diametric line passing through the center of the dimple.

[289] In other words, like a paper windmill, all of the projections are deviated leftward or rightward from the diametric line passing through the center of the dimple in the shape of an oblique line. The present embodiment is obtained by modifying the aforementioned embodiment to create vortex flow in the dimple.

[290] In the present embodiment, the flight pattern of the golf ball is different from those of the above-described embodiments. Namely, in order to compensate for the irregular swing pattern of a beginner, the projections are formed in the oblique line type.

[291] A golfer who strikes a golf ball cannot always make an accurate stroke upon impact, and instead makes a stroke which causes not upward and downward rotation but leftward or rightward rotation. In this case, the golf ball, when initially hit, flies in the impact direction upon making the stroke, while rotating and repeatedly contracting and expanding due to the impact force applied upon making the stroke. During the contraction and expansion, repeated in this way, positions on the golf ball where the oval-shaped contraction and expansion occurs change through 360°.

[292] Therefore, due to air spreading upward, downward, leftward and rightward, the golf ball has substantial directionality. Also, as the air collides against the front portion of the golf ball and then breaks into fragments of air when viewed in the traveling direction of the golf ball, the golf ball forcefully flies due to Reynolds theory. If the contraction and expansion decreases, and the golf ball flies with the circular shape, a relatively large lift force is applied to the golf ball. [293] Hence, the golf ball travels in the direction in which the lift force is generated. If the golf ball is accurately hit, the golf ball can have an extended flight time and can be sent accurately to a farther place.

[294] The golf ball, which is rotated leftward or rightward, is curved from the time at which contraction and expansion in the rotating direction ends. In this case, a golf ball, which is accurately hit on the dimple of the golf ball, and another golf ball, which is not accurately hit on the dimple of the golf ball, have grooves or column walls on the side surface of the dimple.

[295] In the present embodiment, due to the fact that all of the partitioning projections, which are formed on the side surface and the bottom of the dimple, are located in the shape of an oblique line, which deviates leftward or rightward from the diametric line passing through the center of the dimple, the golf ball can be selectively used depending upon the swing pattern of a golfer.

[296] In the conventional golf ball and the golf balls according to the above-described embodiments, it is possible to take advantage of the phenomenon in which lift force starts to be generated approximately at the time that the contraction and expansion of the golf ball occurs when accurately hit with great impact force. Conversely, in the present embodiment, when a leftward or rightward force is increased, by forcibly controlling vortex flow, it is possible to ideally decrease the leftward or rightward deviation to an appropriate level.

[297] Hereafter, an eleventh preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[298] FIG. 54 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with an eleventh embodiment of the present invention, and FIG. 55 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the eleventh embodiment of the present invention.

[299] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the tenth embodiment, and detailed descriptions thereof will be omitted herein.

[300] Referring to FIGs. 54 and 55, in the present embodiment, a plurality of projections is formed at the same angular interval as oblique line-shaped wall projections 161 and 162, such that the width of the projections is greater than the width of the side wall of the dimple. Side wall portions 111 are formed between the projections in such a way as to define oblique line- shaped grooves.

[301] Similar to the tenth embodiment, the grooves defined by the side wall portions 111 deviate leftward or rightward by a predetermined angle α with respect to the diametric line passing through the center of the dimple. [302] Hereafter, a twelfth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[303] FIG. 56 is a plan view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a twelfth embodiment of the present invention, FIG. 57 is a diagrammatic view illustrating the path of the golf ball in accordance with one example of the twelfth embodiment of the present invention, FIG. 58 is a plan view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the twelfth embodiment of the present invention, and FIG. 59 is a diagrammatic view illustrating the path of the golf ball in accordance with the other example of the twelfth embodiment of the present invention.

[304] In the present embodiment, the same reference numerals will be used to refer to the same component elements as those of the tenth embodiment, and detailed descriptions thereof will be omitted herein.

[305] Referring to FIGs. 56 through 59, in the present embodiment, a plurality of projections is formed at the same angular interval as curved projections 163 and 164, which are curved leftward or rightward with respect to the diametric line passing through the center of the dimple.

[306] When viewing a flying golf ball from the top, if the golf ball flies rightward while rotating rightward, due to the fact that side surface grooves, projecting supports, or bottom projections or grooves are formed in the shape of rightward oblique lines, in comparison with the case in which the oblique lines deviate leftward, an increased amount of air can be collected in the dimple.

[307] Namely, in this case, an increased amount of air can spread away from the golf ball, and the difference in lift force between the left portion and the right portion of the golf ball increases. When this is the case, the golf ball abruptly moves rightward, and thus the golf ball cannot be accurately sent to a target place.

[308] Accordingly, as shown in FIG. 57, if the projection 163 is formed to have a curved shape, a decreased amount of air is introduced into the dimple, and a small lift force is generated, so that the degree of deviation from the target place can be decreased.

[309] As described above, due to the fact that grooves or projection walls are integrally formed on the side surface or the bottom surface of the dimple, to thus be curved rightward or leftward, it is possible to allow the golf ball to be selectively used depending upon the swing pattern of a golfer.

[310] Also, referring to FIGs. 58 and 59, the side projections in the dimple are curved rightward to thus extend inward, and are curved leftward to thus project outward. The golf ball travels while rotating rightward. In this case, the projections 164 formed in the dimple direct the wind outward, thus colliding with it most severely. Also, the wind which collides to a lesser degree than the projection 164 due to rightward rotation of the golf ball is directed outwards.

[311] That is to say, in the golf ball which moves forward while rotating rightward, as can be seen from the dimple in which lift force is generated, the projections have the shape of an oblique line which is deviated leftward to introduce air into the dimple and then discharge the air to the rear, so that the difference in lift force is not increased. If the golf ball rotates leftward, a large amount of air is introduced into the dimple by the projections 164 of the dimple, and is then forcefully discharged to the rear so that the difference in lift force is increased.

[312] According to this phenomenon, the present embodiment causes the directional change of the golf ball to occur to a lesser degree than the rotation of the golf ball due to the presence of the grooves or sidewalls or partition walls which are formed in the shape of a leftward or rightward oblique line. Therefore, the present embodiment can be very useful to a large number of golfers.

[313] Hereafter, a thirteenth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[314] FIG. 60 is a perspective view illustrating one example of the inside structure of a dimple for a golf ball in accordance with a thirteenth embodiment of the present invention, FIG. 61 is a cross-sectional view illustrating the example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 62 is a perspective view illustrating another example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 63 is a cross-sectional view illustrating the first example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 64 is a perspective view illustrating a third example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, and FIG. 65 is the third cross-sectional view illustrating still another example of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention.

[315] FIG. 66 is a plan view illustrating one example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 67 is a cross-sectional view illustrating the example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 68 is a plan view illustrating another example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 69 is a plan view illustrating a third example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, and FIG. 70 is a diagrammatic view illustrating the path of the golf ball in accordance with the thirteenth embodiment of the present invention.

[316] FIG. 71 is a plan view illustrating one example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 72 is a cross-sectional view illustrating the example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 73 is perspective views illustrating various shapes of the side configuration of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 74 is a cross-sectional view illustrating another example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 75 is a cross-sectional view illustrating a third example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 76 is a cross-sectional view illustrating a fourth example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, and FIG. 77 is a cross-sectional view illustrating a fifth example of the air path around the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention.

[317] FIG. 78 is a plan view illustrating one variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 79 is a cross-sectional view illustrating the variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 80 is a plan view illustrating another variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 81 is a cross-sectional view illustrating the other variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, FIG. 82 is a cross-sectional view illustrating a third variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention, and FIG. 83 is a cross-sectional view illustrating a fourth variation of the side configuration of the inside structure of a dimple for a golf ball in accordance with the thirteenth embodiment of the present invention.

[318] Referring to FIGs. 60 through 65, in the inside structure of a dimple for a golf ball according to the present embodiment, a sidewall structure having a predetermined shape is projectedly formed on the side surface 111 of a dimple 110. [319] Specifically, in the sidewall structure, it is preferred that a plurality of projections be projectedly formed at the same angular interval and have a step-shaped, a divided type or an inclined type configuration.

[320] The projections can be changed into various shapes such as those which are formed with inclined surfaces 141, steps 142, and vertical surfaces 143.

[321] In a golf ball which moves while rotating, the steps can be formed on the side surface of the dimple to have a shape which is different from those of the above- described embodiments. Also, as shown in FIGs. 66 through 69, the side surface 111 of the dimple can be formed to have curved shapes 144 and 145. A combination of the steps and the curved shapes can be envisaged as well.

[322] Due to this structure, in order to exert an influence on air flow on the golf ball which moves forward while rotating, the sidewall structure of the dimple is configured to form shoulders and grooves on the side surface of the dimple, which serve as prominences and depressions. Thus, when air collides against the upper and lower portions of the golf ball, the air is forcefully delivered in the moving direction on the lower portion of the golf ball to a degree which cannot be achieved by the conventional circular or countersunk dimples, so that air can flow slowly around the lower portion of the golf ball.

[323] Accordingly, as shown in FIG. 70, around the upper portion of the golf ball, compared to the conventional circular or countersunk dimples, an increased amount of air is discharged. Therefore, since great lift force is generated in the golf ball, the sidewall structure can effectively increase the flight time of the golf ball.

[324] Referring to FIGs. 71 and 72, while the steps are formed in the side surface of the dimple in the above-described sidewall structure, in the present example, the sidewall 111 of the dimple is formed as an inclined surface, as in the above-described dimples, and grooves 131 are defined in the sidewall 111. Of course, steps can be formed in the inclined sidewall of the dimple. In addition, grooves can be defined to have the various sectional shapes shown in FIG. 73.

[325] Also, in the sidewall structure, by changing the intervals of the upper grooves and shoulders on the inclined surface of the dimple or the intervals on the lower portions, the lift force generated by the air introduced into the dimple can be adjusted.

[326] Accordingly, when the overall number of dimples is large and it is necessary to decrease the amount of air introduced into the dimple, by decreasing the interval L between shoulders on the upper part and increasing the interval L between the shoulders on the lower part, the golf ball can fly along a low trajectory, and by increasing the interval L between shoulders on the upper part and decreasing the interval L between the shoulders on the lower part, the golf ball can have an extended flight time. [327] Referring to FIGs. 74 through 77, a step-shaped sidewall structure is defined, in wh ich at least one step is formed on the side surface 111 of the dimple 110, and at least one air path 132 having a predetermined width is preferably defined.

[328] As air paths 133 or 134 are defined only on the upper or lower part of the side surface of the dimple, that is, partially, it is possible to adjust the amount of air introduced into the dimple. Therefore, by adjusting the amount of air introduced into the dimple through the upper part or the lower part of the dimple, the lift force of the golf ball can be finely adjusted.

[329] Referring to FIGs. 78 through 83, in the sidewall structure, curved steps 135 and

136 are formed on the side surface 111 of the dimple 110, so that air flow into the dimple can be adjusted.

[330] While the sidewall structure is formed to have a step-shaped configuration, the edges 135b and 136b of the steps 135 and 136 are formed to have a curved sectional shape or a sectional shape of a '-'.

[331] In another sidewall structure, while the sidewall structure is formed to have a step- shaped configuration, the width (q) of the upper surfaces 135a and 136a of the steps 135 and 136 are gradually changed.

[332] Accordingly, as air flows actively in the dimple along the edges and the upper surfaces of the steps, the effects of the dimple can be further improved due to this type of air flow in the dimple.

[333] Hereafter, a fourteenth preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[334] FIG. 84 is a plan view illustrating one example of the side configuration of the inside structure of a dimple for a golf ball in accordance with a fourteenth embodiment of the present invention, FIG. 85 is a cross-sectional view illustrating the example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention, FIG. 86 is a plan view illustrating another example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention, FIG. 87 is a cross-sectional view illustrating the other example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention, FIG. 88 is a plan view illustrating a third example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention, FIG. 89 is a cross-sectional view illustrating the third example of the side configuration of the inside structure of a dimple for a golf ball in accordance with the fourteenth embodiment of the present invention, and FIG. 90 is a diagrammatic view illustrating the path of the golf ball in accordance with the fourteenth embodiment of the present invention.

[335] Referring to FIGs. 84 and 85, a sidewall projection having the shape of a protuberance, which is projectedly formed on the side surface of the dimple 110, is composed of an upper inclined surface 171 and a lower inclined surface 172.

[336] The sidewall projection corresponds to the inside structure of a dimple, which functions to guide air flow into the dimple and creates vortex flow, so that lift force is generated and flight distance is increased when the golf ball flies.

[337] Referring to FIGs. 86 and 87, a step-shaped sidewall structure 173 is formed in the side surface of the dimple 110 such that the inside sectional area of the dimple 110 is increased in order to adjust the trajectory of the golf ball.

[338] In this sidewall structure 173, the upper surface 173a thereof is formed as a flat surface and the side surface thereof 173b is formed as an inclined surface, so that smooth air flow in the dimple is ensured, and an increased amount of air can be introduced into and discharged from the dimple.

[339] Referring to FIGs. 88 and 89, in the step-shaped sidewall structure 173, which is formed in the side surface of the dimple 110, an increased amount of air is discharged in the moving direction around the lower part of the golf ball and in the opposite direction around the upper part of the golf ball, so that generation of lift force is facilitated and air colliding against the front part of the golf ball breaks, thus eliminating eddies, which cause resistance.

[340] Also, in the case that air paths 174 are defined in the sidewall structure 173 to extend from the bottom surface of the dimple to the outer periphery of the dimple, when viewed from the lower part of the dimple while the golf ball flies, air action occurs to an increased extent in the step-shaped sidewall structure, in comparison with a conventional golf ball.

[341] In order to minimize this air action phenomenon, it is preferred that air paths 174 be defined. Also, it is further preferred that the sum (rl + r2 + r3) of the widths of the air paths be less than the sum (Rl + R2 + R3) of the widths of the side surface portions ((rl + r2 + r3) < (Rl + R2 + R3)).

[342] The reason for this resides in the fact that, if the size of the side surface portion is greater than the size of the air path, an eddy current phenomenon occurs in air, and the lift force increasing effect of the golf ball is impaired.

[343] Due to the presence of the sidewall structure described above, as can be readily seen from FIG. 90, lift force is generated in the hit golf ball with the aid of the vortex flow created in the upper and lower parts of the golf ball, so that the golf ball can fly in the air for an extended period.

[344] Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[I] An inside structure of a dimple for a golf ball having formed in an outer surface thereof a plurality of dimples of a concave shape, wherein projections having a predetermined shape are projectedly formed on bottom surfaces of all or some of the dimples, and a height (h) of the projection corresponds to 15-40% of a depth (D) of the dimple.

[2] An inside structure of a dimple for a golf ball having formed in an outer surface thereof a plurality of dimples having a concave shape, wherein, when dividing a sectional area (S A ) of the dimple into three portions by drawing lines from a vertex of a projection to an outer periphery of the dimple, a height (h) of the projection is determined in a manner such that a sum (S + S ) of a left sectional

B C area (S ) and a right sectional area (S ), which are defined on both sides of the

B C projection, is less than an upper sectional area (S ), which is defined over the projection, to satisfy the inequality (S + S ) < S . [3] The inside structure according to claim 1 or 2, wherein a sectional area (S ) of the projection corresponds to 6-25% of a sectional area (S ) of the dimple. [4] The inside structure according to claim 1 or 2, wherein a width (W) of a lower end of the projection is no less than two times the height (h) of the projection. [5] The inside structure according to claim 1 or 2, wherein a step-shaped projecting wall is projectedly formed on a side surface of the dimple that surrounds the projection. [6] The inside structure according to claim 5, wherein a groove-shaped air path is defined through the projecting wall to extend from the projection to the outer periphery of the dimple. [7] The inside structure according to claim 6, wherein the air path is also defined through the projection. [8] The inside structure according to claim 1, wherein an air path having a concave shape is defined in the projection. [9] The inside structure according to claim 8, wherein the projection is composed of a first projection and a second projection, which overlaps the first projection, and a plurality of air paths having a concave shape is defined in the second projection to extend upward from a bottom surface of the projection. [10] The inside structure according to claim 9, wherein widths of lower ends of and/or heights of the first projection and the second projection are different from each other.

[I I] The inside structure according to claim 8, wherein the air path around the projection comprises one or more paths or ridges which are formed at the same acute angular interval.

[12] The inside structure according to claim 8, wherein the air path around the projection has a structure that has a predefined inclined surface, and a width or an interval of the air path is different on a lower end and an upper end of the projection.

[13] An inside structure of a dimple for a golf ball having formed in an outer surface thereof a plurality of dimples of a concave shape, wherein a sidewall structure having a predetermined shape is projectedly formed in all or some dimples.

[14] The inside structure according to claim 13, wherein the sidewall structure has a plurality of projections which is projectedly formed at the same angular interval, and the sum (El + E2 + E3) of widths of the projections is less than the sum (el + e2 + e3) of widths of side surface portions of the dimple, which are positioned between the projections.

[15] The inside structure according to claim 14, wherein the projection has a step- shaped, a divided type or an inclined type configuration.

[16] The inside structure according to claim 14, wherein the shape of the projection is defined in a manner such that a width (P ) of an upper end of the projection and a width (P ) of a lower end of the projection are different from each other.

[17] The inside structure according to claim 13, wherein the sidewall structure is formed as a step-shaped sidewall structure which has at least one step formed therein.

[18] The inside structure according to claim 13, wherein the sidewall structure has one or more air paths which are defined at the same angular interval.

[19] The inside structure according to claim 18, wherein a width of an upper end of the air path and a width of a lower end of the air path are different from each other.

[20] The inside structure according to claim 18, wherein the air path has both sidewalls which are formed as vertical or inclined surfaces and a bottom surface which is formed as an inclined surface, or in a corrugated sectional shape of a

[21] The inside structure according to claim 18, wherein the air path is defined on an upper end or a lower end of a side surface of the dimple. [22] The inside structure according to claim 13, wherein, in the sidewall structure, at least one of an outer circumference and an inner circumference of a sidewall of the dimple is formed to have a corrugated sectional shape of a '-'. [23] The inside structure according to claim 13, wherein the sidewall structure is formed to have a shape of a step, and an upper surface of the step is corrugated in a sectional shape of a '-'. [24] The inside structure according to claim 13, wherein the sidewall structure is formed to have a shape of a step, and a side surface of the step is formed to have a curved shape or a corrugated sectional shape of a '-'. [25] The inside structure according to claim 13, wherein the sidewall structure is formed to have a shape of a step, and a width of an upper surface of the step is gradually changed.