GB2150443A - Ball - Google Patents

Abstract

A ball (10) has one hemisphere (12) provided with at least two differing surface levels (18, 20). When projected along the plane of a line (16) joining that one hemisphere (12) and the other hemisphere (14), the ball (10) will deviate from a normal trajectory in the direction of the one hemisphere (12). The other hemisphere (14) may have a smooth surface, or a uniformly rough texture, such as that on a tennis ball. <IMAGE>

Description

SPECIFICATION Ball This invention relates to a ball which may be used for playing ball games, such as cricket, or may be used as a practice ball for such games.

In cricket, the ball can be made to 'move' or 'swing' by a skilled bowler, the movement being to the left or to the right of a line from the bowler to the batsman. Of course, in cricket the intention is for the ball to strike the ground before it reaches the batsman, and accordingly the swing or movement takes place before the ball strikes the ground.

In cricket, the movement is believed to be accentuated by polishing one hemisphere of the ball, to one side of the circumferential seam, whilst leaving the other hemisphere unpolished, but again the theory behind the behaviour of the ball is not understood.

United Kingdom patent application no. 2091110Ato Phillips describes a simulated cricket ball which assists an inexperienced bowler in obtaining 'swing'.

This is achieved by provided a simulated seam which is higher than that of a convention ball.

In baseball, the behaviour of the ball is not dissimilar to that of a cricket ball. A pitcher will, in order to deceive a batter throw a baseball so that it describes curves which differ from the normal or expected trajectory from the mound to the plate.

Only pitchers with the appropriate level of skill can produce effective pitches of this general type, variants of which are termed 'curve', 'slider', 'sinker' and 'break'.

It is known that such trajectories can be obtained or exaggerated by tampering with the ball. This is discussed in an article entitled "Masters of mischief" which appears on pages 92 and 93 ofthe October issue of "Science 83". The theory behind the behaviour of baseballs when pitched to curve to the plate is not understood, although it appears that atmospheric conditions can affect the degree of curve.

In United States patents nos. 4,128,238 and 4,286,783 both to Newcomb and Newcomb, Jr., there are described practice baseballs which have portions of the surface removed to allow the ball to curve when it is pitched as a straight ball. As the ball is not generally spherical, it cannot properly be used for playing baseball, but may only be used as a practice ball.

It is an object of this invention to provide a ball which can be used for normal play, but which is also capable when pitched or bowled, of deviation from a normal or expected trajectory.

The invention provides a ball for projection to deviate from a normal or expected trajectory, said ball having two generally hemispherical surface areas, one of said hemispherical surface areas having at least two surface levels.

The invention also provides a ball for projection to deviate from a normal or expected trajectory, said ball having two generally hemispherical surface areas, one of said generally hemispherical areas being provided with two major surface levels, the ball, in use, deviating from the plane of a line connecting said two generally hemispherical areas in the direction of said one of said generally hemispherical areas, when it is projected along said plane.

Preferably, said other of said generally hemispherical surface areas has a uniformly non-smooth surface.

Embodiments of the invention, which may be preferred, will now be described in detail with reference to the accompanying drawings, in which Figure 1 is a side elevation of a ball in accordance with this invention; Figure 2 is a cross-section through the ball of Figure 1; Figure 3 is a side elevation of another ball in accordance with this invention; Figure 4 is a cross-section through the ball of Figure 3; Figure 5 is a side elevation of a tennis ball treated to form a further ball in accordance with this invention; Figure 6 is a cross-section through the ball of Figure 5; Figure 7 is a side elevation of a further ball in accordance with this invention; Figure 8 is a cross-section through the ball of Figure 7; Figure 9 is a diagram showing the performance of a ball of the type shown in Figures 4 and 5 when thrown as a 'shooter';; Figure 10 is a diagram showing the performance of a ball of the type shown in Figures 4 and 5 when thrown as a 'dropper'; and Figure 1 7 is a diagram showing the performance of a ball of the type shown in Figures 4 and 5 when thrown to curve left or right.

In the following description, reference to a ball is intended to be a reference to a generally spherical ball, it being considered that the difficulties in projecting a nonspherical ball, and in the relationship of the more complex shape as it moves through the air, may render the application of this invention to such a ball ineffective.

Figures 1 and 2 show a ball 10 which is hollow, and is preferably made from rubber or a similar material.

The generally spherical ball 10 comprises two hemispheres 12,14 joined by a line 16 which may be a visible seam caused by a moulding process, or may simply be an imaginary line.

Hemisphere 12 is provided with a number of depressions 18 in the datum surface 20, which surface generally defines the spherical shape of the ball. Each depression 18 is teardrop shaped, and has a sharp edge 22 nearest the apex of hemisphere 12, and a more gradually sloping edge 24 at the other end of the depression. The depressions 18 are arranged in a regular pattern on hemisphere 12.

The ball 26 of Figures 3 and 4 is substantially the same as that of Figures 1 and 2, and reference numerals 12 to 16 and 20 have the same meanings as in Figures 1 and 2.

In ball 26, depressions 28 are provided in the surface 20 of hemisphere 12, but in this embodiment they are in the nature of letters. The letters could be the name of a sporting club or organization, a trade mark, a symbol such as a map of Australia, or any other device, pattern or the like.

In balls 10 and 26, hemisphere 14 has a smooth surface 20.

The ball 30 of Figures 5 and 6 is a modified tennis ball of conventional construction. One hemisphere 12 of the ball is coated with a plastics or any other suitable material, whilst the other hemisphere 14 has the usual rough texture of tennis balls.

Depressions 32 are provided in the coated surface 34 of hemisphere 12. The depressions 32 are similar to depressions 18 of ball 10, except that they are extended, and there are fewer of them. Each depression 32 has a sharp edge 36 nearest the crown of hemisphere 12, and a shallower edge 38 at the other end thereof.

In this embodiment, the datum surface can be seen as the average surface of hemisphere 14, and the major part of hemisphere 12. Alternatively, it can be seen that on hemisphere 12, there are two major surface levels, the outer surface 34, and the surfaces 40 of each depression 32. The same 'two-level' surface arrangement can be seen in depressions 18,28 of balls 10,26.

The ball 42 of Figures 7 and 8 is similar to those of Figures 1 and 2, and 3 and 4, and reference numerals 12 to 16 and 20 have the same meanings..

Hemisphere 12 of ball 42 is provided with raised portions 44, shown as letters, although they could be of any shape or pattern. It can be seen that a 'two-layer' effect is produced on hemisphere 12, with the surfaces 46 of the raised portions and surface 20 providing the two levels, with edges 48 therebetween.

If any of the balls of Figures 1 to 8 are propelled along the plane of line 16, the ball will deviate from that plane in the direction of hemisphere 12. That is, if the ball is projected with hemisphere 12 on the left of the plane, the ball will deviate in flight to the left of the plane.

The ball is projected with some back spin, about an axis perpendicular to the plane, which back spin cannot in practice be avoided in attempting to project a ball without spin. No other spin is required or desired to be imparted to the ball.

As has been discussed earlier in this specification, the behaviour of the curving or swinging motion of conventional balls is not well understood. It is believed that the behaviour of the various balls embodying the present invention can be explained as follows.

As the ball rotates in flight, the 'two-level' surface characteristics of hemisphere 12 cause a minor air disturbance or turbulence not experienced around hemisphere 14.

The disturbed air is 'propelled' over the remaining surface 20 of the hemisphere 12 by the action of the edges of the depressions or raised portions, and escapes towards hemisphere 14. This causes a partial vacuum around hemisphere 12, and the ball is propelled into this vacuum by the pressure of the air on hemisphere 14. As this action continues, the ball describes a curved path away from the plane.

When hemisphere 14 has a 'rough' surface (such as in ball 30 of Figures 5 and 6) the curving or swinging effect is seen to be enhanced.

Figures 9 to 11 show diagrams of tests made with a ball of the same general type as that of ball 30 of Figures 5 and 6.

Figure 9 is a side elevation of a testing area.

Ground level is indicated by 50, the projection point by 52, and a horizontal bar is shown at 54. Projection point 52 was 1.07m above point 56 representing a pitchers plate, and bar 54 was 1.37m from ground level 50. The trajectory of a ball thrown not to curve is shown by a broken line, and that of a ball thrown to curve is shown by a solid line. Point 56 represents a batter's plate.

It can be seen that the 'normal' ball lands at point 58, 1 .22m past plate 56. When the ball is thrown as a 'shooter', that is, to deviate upwards from the plate 56, 5.79m beyond the 'normal' pitch. In each case, as shown, the ball was thrown as near as possible to the underside of bar 54.

Figure 10 is similar to Figure 9, and the same reference numerals and dimensions apply. In each case, the ball was projected to pass as near as possible to the top of bar 54. In the case of the 'swing' ball of this invention, it was projected as a 'dropper', that is, to deviate downwards from the expected trajectory.

The normal ball landed at point 62 3.35m past plate 54. However, the ball of this invention landed on plate 54, 3.35m shorter than the 'normal' pitch.

Figure 11 is a plan view, with a vertical bar 64, but otherwise the dimensions and conditions were the same as for Figures 9 and 10. A 'normal' pitch travelled in a straight line. A pitch to deviate left passed 0.46m to the left of plate 56, and a pitch to deviate right passed the same distance to the right of plate 56.

It has already been indicated that the effectiveness of the balls is enhanced if the hemisphere 14 is not totally smooth, but has a rough texture, preferably of an homogenous nature. It has also been found that on hemisphere 12, depressions are more effective if they are located nearer the crown of the hemisphere, for example in the one-third of the surface nearest the crown rather than near line 16. However, with a recurring pattern (as in ball 10 of Figures 1 and 2) it is preferred to locate the depressions over the entire surface of the hemisphere.

An effective 'two-level' effect can be obtained by a fine mesh or grid pattern, as well as by those mentioned earlier in this specification. Undulations, dimples or grooves may also be used, and the edges of the depressions or the like may be modified. The 'two-level' effect may be achieved by moulding into or onto a surface, by machining a surface, or by adheringmaterials thereto. The balls may be hollow or solid, or formed from a foam material, and although a ball of the weight of a tennis ball or hollow rubber ball is preferred, other weights could be used. A simulated seam could be included; as long as it coincided with line 16, it would not adversely effect the performance of the ball.

It is preferred to mould the ball with the 'two-level' hemisphere in the one operation although existing balls, rubber balls, tennis balls or the like, could be modified.

The various embodiments of this invention provide a ball which can be played with as a normal ball, either to deviate or not to deviate, and can also be used in practice particularly to enable a hitter or batsmen to practice against curving pitches or deliveries.

Claims (12)

1. A ball for projection to deviate from a normal or expected trajectory, said ball having two generally hemispherical surface areas, one of said hemispherical surface areas having at least two surface levels.

2. A ball according to claim 1, wherein said one of said hemispherical surface areas is provided with at least one depression.

3. A ball according to claim 2, wherein a regular pattern of the depressions is provided.

4. A ball according to claim 3, wherein each said depression has a tear-drop shape.

5. A ball according to claim 1, wherein said one of said hemispherical surface areas is provided with depressions in the shape of letters, numerals, devices or the like.

6. A ball according to any preceding claim, wherein said other of said hemisphereical surfaces is generally smooth.

7. A ball according to any one of claims 1 to 5, wherein said other of said hemispherical surfaces is generally rough.

8. A ball according to claim 7, wherein said other of said hemispherical surfaces has a felt-like texture.

9. A ball for projection to deviate from a normal or expected trajectory, said ball having two generally hemispherical surface areas, one of said generally hemispherical areas being provided with two major surface levels, the ball, in use, deviating from the plane of a line connecting said two generally hemispherical areas in the direction of said one of said generally hemispherical areas, when it is projected along said plane.

10. A ball according to claim 9, wherein the upper of said two major surface levels forms a greater proportional of the surface area of said one of said generally hemispherical areas.

11. A ball according to claim 9, wherein the lower of said two major surface levels forms a greater proportional of the of the surface area of said one of said generally hemispherical areas.

12. A ball substantially as described herein with reference to Figures 1 and 2; Figures 3 and 4; Figures 5 and 6 or Figures 7 and 8 of the accompanying drawings.