The present invention relates to a ball used in ball games such as a volley ball and a soccer ball, and more particularly to a ball having a fabric layer as a reinforcing layer obtained by sewing together a plurality of pieces of woven fabric in a specific manner.
Hitherto, in the technical field of the above kinds of balls used in ball games, there is known a structure comprising a rubber hollow tube or bladder, a fabric layer, a rubber based thin layer and a leather outer casing (for example, U.S. Pat. Nos. 2,091,455 and 2,244,503) U.S. Pat. Nos. 2,091,455 and 2,244,503 disclose a ball structure comprising a rubber hollow bladder, a fabric layer surrounding the bladder, a rubber based thin intermediate layer coated on the fabric layer and a surface layer or outer casing. The fabric layer, used as a reinforcing layer, is formed by sewing together a plurality of shell-like fabric pieces. Further, it is known to form a fabric layer by overlapping and adhering a plurality of fabric pieces to each other (for example, U.S. Pat. Nos. 2,653,818 and 4,239,568. and Japanese Examined Patent Publication No. 8519/1956). U.S. Pat. No. 653,818 discloses a nonspherical athletic ball (ellipsoidal ball) such as a football, wherein the fabric pieces of the reinforcing layer are adhered to the bladder in a previously stretched state so as to minimize circumferential enlargement of the ball in a direction parallel to the minor axis. U.S. Pat. No. 239,568 and Japanese Examined Patent Publication No. 8519/1956 disclose a ball wherein a fabric layer is formed by adhering cloth strips in two layers on a spherical body in such a manner that edges of cloth strips overlap one another. The majority of current ball products, such as volley balls, use reinforcing layers comprising windings of thread formed by winding several thousands of meters of thread, such as nylon yarn, around a tube (for example, U.S Pat. No. 4,333,648 and Japanese Examined Patent Publication No. 3,934/1983). A reinforcing layer comprising wound yarn has a drawback because it gives a poor feel when the ball collides with the human body although such a ball having this type of reinforcing layer is superior with respect to several desirable characteristics namely, sphericity and durability. In U.S. Pat. No. 4,333,648 and corresponding Japanese Examined Patent Publication No. 319,34/1983, rubber threads are mixed into nylon threads to reduce this drawback.
Recently, with respect to ladies' volley balls, boys' soccer balls and the like, it has been strongly desired that such volley balls or soccer balls produce less pain upon collision of the balls with a body and have a soft "feel".
However, it is difficult to make the current balls feel soft using reinforcing layers comprising wound threads. As a result of vigorous investigation, we inventors discovered that balls having a softer feeling could be obtained by employing a structure wherein, instead of a reinforced layer comprising wound threads, a plurality of fabric pieces of woven fabric and the like are sewed together in a particular manner to form a sphere containing a bladder therein. Various kinds of concrete constructions thereof were examined.
Since fabric layers which ar sewed together not only feel soft but also provide dimensional stability, sphericity and durability, strict limitations are required for the quality of the material, shape, sewing structure of fabric pieces abutting each other, and the like.
Therefore, as in U.S. Pat. Nos. 2,091,455 and 2,244,503, using a structure comprising a rubber bladder, a fabric layer, a rubber based thin intermediate layer and a surface casing, it is almost impossible to maintain the sphericity of a ball because the sewed together portions are not equally distributed on the ball surface; the strength of the sewed together portions is different from that of other portions, i.e. it is generally larger than that of other portions; the direction of the warp and the direction of the weft of the fabric become uniform; and further stress is unevenly distributed due to the existence of two poles generated by the design of the fabric pieces. Moreover, the ball has a drawback because a soft feeling, which can be obtained in a bias direction of fabric texture, is lost since circumferential lines on the ball are solely composed of sewed together portions. Therefore, at present, no balls are manufactured having the above structure.
Also, balls having fabric layers obtained by pasting a plurality of fabric pieces to each other as in the above U.S. Pat. No. 4,239,568 and Japanese Examined Patent Publication No. 8519/1956 are inferior in mechanical strength, particularly in the tensile strength of the joined portions of the fabric pieces, because the fabric pieces are merely overlapped over one another. These balls also have problems in sphericity and durability. Further, the balls have a drawback because of a large change in their shape over time. Still further, in balls having the structure as described hereinbefore, the joined portions of the fabric pieces are thicker than the other portions of the fabric pieces, whereby unevenness in the outer surface of the ball occurs, i.e. so-called mirror through phenomenon, on the surface of the balls. This mirror through phenomenon causes passing errors when using, for example, volley balls, because the players hands are caught in the unevenness when the ball is passed. This unevenness can also cause pain when the ball hits the player's hands. The balls are inferior in merchandise value.
In order to avoid the above drawbacks, a method is used to equalize the thickness of the fabric layers by adhering additional pieces to the concave portions of the fabric layer where there is no seam overlap. As a result, a good feeling inherent in the fabric itself, is remarkably reduced due to the thick fabric layer and the interposition of adhesive. A ball having a structure wherein the fabric layer is composed of pasted fabric pieces, improves the feeling of the ball during a collision with the ball at the sacrifice of other characteristics of the ball such as sphericity and durability. A ball of the present invention not only gives a better feeling than these balls, but satisfies the other desirable characteristics such as sphericity, and durability.
In the balls of the above type composed of pasted fabric pieces, it is possible to pile up several more fabric layers described hereinbefore and to paste then one on another to reinforce the ball, in order to improve sphericity dimensional stability and durability. However, when the structure of the ball comprises piled up fabric layers, it is difficult to obtain balls having satisfactory properties such as sphericity, dimensional stability and durability.
The present invention was made to solve the above mentioned problems. An object of the present invention is to provide a ball having superior sphericity, dimensional stability and durability as well as having a soft feeling.