Games using tangible projectile – Player held and powered – nonmechanical projector – per se,... – Racket or paddle; accessory therefor
Reexamination Certificate
1999-04-09
2002-07-16
Chiu, Raleigh W. (Department: 3711)
Games using tangible projectile
Player held and powered, nonmechanical projector, per se,...
Racket or paddle; accessory therefor
C473S560000, C081S177100, C081S489000, C016S110100, C440S101000
Reexamination Certificate
active
06419601
ABSTRACT:
BACKGROUND
1. Field of Invention
This invention relates to rotatable handle grips that improve the performance of a broad range of items including tennis racquets, hockey sticks, kayak oars, and rotary hand tools.
2. Description of Prior Art
Although this invention can be applied to many items, only two types of items, tennis racquets and screwdrivers, will be discussed in detail since they represent a broad range of possible applications.
In the game of tennis a racquet is usually rotated to different positions relative to a players hand when preparing for backhand, forehand or volley shots. Most players utilize more than one grip position for each of those shots. For example, when hitting a backhand shot the player can impart either slice (underspin) or topspin (overspin) to the ball, but each shot can be performed more efficaciously using different grip positions.
Different grip positions determine the degree of angular racquet head displacement relative to a player's hand This determines the angle of the racquet face relative to the ground at the moment of impact with a tennis ball during a tennis stroke. A topspin shot would require a slightly acute angle, while a slice shot would require a somewhat obtuse angle. This rotational displacement can be controlled by a rotatable handle grip that can provide a player with increased accuracy, control, power, consistency, hand comfort and decreased response time. However, rotatable handle grips that can be locked in only a limited number of predetermined positions, or that cannot be adjusted easily and instantaneously during play, are inefficacious because they limit not only the types of shots a player can make but the quality of play in general.
Rotatable handle grips also improve the performance of many hand tools that require rotation, such as screwdrivers. Such rotatable handle grips usually operate with a ratcheting mechanism, allowing the handle grip to rotate freely about the shaft of a tool in only one direction at a time. When the user rotates the handle grip in the opposite direction, the tool rotates with the handle grip. If a user wishes to rotate the tool in the opposite direction, he must slide or twist a setting switch prior to use, a time consuming and bothersome procedure. Manufacture and assembly of the numerous moving parts is relatively complex, resulting in production costs far above that of conventional stationary handle grip screwdrivers.
Previous rotatable handle grips suffered from the above-mentioned problems as well as these discussed below.
U.S. Pat. No. 2,019,512 to Marsh (1936) discloses a golf club handle which had to be “set” in position. This involved a cumbersome and time-consuming process; a user was required to loosen a nut at the base of the handle, disengage a toothed mechanism, estimate where the desired setting might be, reengage the teeth, and finally retightening the base nut Consequently, this handle grip mechanism could not provide any benefit if applied to a tennis racquet since the user would be unable to rotate the handle grip to different positions during play.
Marsh's handle could not provide a ratcheting effect, or selectively transfer torque, thereby making it equally non-beneficial for screwdrivers.
U.S. Pat. No. 4,693,475 to Keilhau (1987) shows a tennis racquet similar to Marsh's. In Keilhau's, however, the clutch comprises an acutely angled conical component on the handle shaft, and a corresponding funnel shape on the handle grip. Keilhau's handle grip was an improvement over Marsh's handle grip in that it could be set in an infinite number of positions because it possessed no teeth; nonetheless, it provided no means for rotating the handle grip to different positions during play.
German patent DE 35 10598 A1 to Pankonin (1986) shows a handle grip similar to Keilhau's, but Pankonin's provides a powerful tension spring rather than a locking nut, and less acutely angled clutch surfaces. Unfortunately, the spring tension required to prevent axial rotation of the racquet during off-center shots was enormous; this made quick handle grip position changes during play nearly impossible.
In U.S. Pat. No. 3,534,960 to Hanks (1970), a rotatable tennis racquet handle grip was proposed which could be locked in only three predetermined positions. Hanks' handle grip was also complicated to operate. The user was required to perform three precisely timed sequential operations in order to change from one grip setting to another. First a spring loaded dog-pin mechanism had to be “unlocked” by depressing a thumb tab. Next the user rotated the grip about the handle. The user then had to release the thumb tab at precisely the correct spot to situate the dog-pin into one of three hole settings. Since the handle grip was normally in a locked position, if the user applied rotational force to the handle grip prior to depressing the thumb tab, the mechanism could jam; even worse, the dog-pin or opposing parts could shear or bend. Likewise, if the user did not release the thumb tab at, or immediately prior to the desired hole setting while rotating the handle grip, it could lock in the wrong position, or not even lock at all.
The preferred Hanks' embodiment, containing only three settings, created an inflexible system. The rotational displacement between each setting was overly large; very small changes in angular displacement are needed. Without such control the racquet-face will not be at the correct angle relative to the ground at the moment of impact with a ball during a tennis stroke. Adding more holes would have confused the user; there was no way to quickly and easily distinguish among even the few settings which were provided. Too many holes would have also greatly increased the chance of part failure due to shear; the greater the number of holes, the smaller each hole would need to be to remain separated, and the thinner the dog-pin would need to be.
Finally, Hanks' mechanism did not address the extremely important factor of user compatibility. The user was forced to delicately place his thumb on a tab longitudinally along the handle grip. The thumb had to remain there for much of the time during play in order to be prepared for quick changes of grip positions. When gripping the handle in such an awkward and unnatural manner, it is extremely difficult to maintain a firm grip and control of the racquet when hitting a tennis ball. Furthermore, a player could inadvertently unlock the handle grip from its setting; there is a natural tendency to squeeze the handle grip of a tennis racquet more firmly at the moment the racquet impacts the ball. If the mechanism for changing grip positions is cumbersome, time consuming, unreliable, and distracting to use, it is not appropriate for use in a game which requires intense concentration and nearly instantaneous grip changes.
Hanks' tennis racquet handle grip mechanism was also inappropriate for performing a ratcheting effect on screwdrivers.
In U.S. Pat. No. 4,101,125 to Heath (1988) a rotatable tennis racquet handle grip was proposed. It employed a spring loaded grip-sleeve with a peg and grove locking mechanism. The handle grip had only two settings—forehand and backhand As mentioned earlier, a handle grip that provides only a limited number of predetermined positions is inefficacious.
Adding many positions would not be possible; the mechanism necessitates a large rotational displacement between positions in order to prevent part failure due to shear. Furthermore, the user would be unable to easily and quickly distinguish between positions, and accurately reengage the locking peg in a desired slot.
The mechanism increased response time during play and was also susceptible to jamming. The user was required to “unlock” the handle grip by moving it longitudinally up the racquet shaft prior to rotating the handle grip to a new position. This extra motion increased the amount of time needed to change from one grip position to another. In many circumstances during play, the grip change could not be p
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