Extendable and Retractable Tennis Racquet
One embodiment of an extendable and retractable tennis racquet contains a stringed area 01, throat 02, and shank 03 as one integral member. The handle is comprised of a shank inside of a hollow handle 05. A spring or flexible means 07 connects the shank to the hollow handle. When the racquet is swung, the centrifugal force generated pulls on the head assembly. The shank slides outward telescopically, thereby increasing the length of the racquet. At the end of the racquet swing, the restoring force of the spring overcomes the diminishing centrifugal force, which pulls the shank back to its retracted position. Other embodiments are described and shown.
This invention relates to tennis racquets, and more particularly, to tennis racquets having a mechanism to change its length during gameplay.
2. Discussion of the Prior ArtMany adjustable length racquets have been proposed in the past. Despite having some of the same common goals, the applications are significantly different. One main area of focus was the interchangeability of the racquet. Many previous inventions tried to address a means to exchange a handle or a portion of the handle in order to suit the individual needs of a particular player. Another area of focus was a means to adjust the racquet length using either common, everyday tools or specific tools. Very few prior art inventions allowed for a quick adjustment that could be achieved during gameplay.
In U.S. Pat. No. 4,746,119 to Jeanrot dated May 24, 1988, a retractable racquet is shown in FIG. 4. The purpose of retraction is to provide an easier mode of transportation for the racquet. This racquet is not meant to be changed during gameplay.
Many of the past inventions were focused on providing an adjustable length racquet. Many of the noted efforts include U.S. Pat. No. 5,169,145 to Jang, U.S. Pat. No. 4,641,838 to Gabrielidis, U.S. Pat. No. 4,671,511 to Trysinksy, U.S. Pat. No. 6,030,302 to Chojnacki, U.S. Pat. No. 6,033,325 to Hong, U.S. Pat. No. 4,545,584 and 4,691,926 to Adam, and U.S. Pat. No. 3,833,219 to Dean. All of these prior art inventions have a way to adjust the racquet length by means of grooved sockets, pins, screws, or bolts. However, none of these means can be used to quickly change the length of the racquet. Tools are often required to make the necessary adjustments. Another drawback to these inventions is that with the racquet extended, many players would hit the ground with the racquet on the take-back during the serve.
A rapidly adjustable racquet is shown in U.S. Pat. No. 3,931,968 to Hedberg dated Jan. 13, 1976. This invention requires the player to use both hands in order to slide the shank to the preferred length. The racquet remains at the specified length as long as the grip is held tightly. It also requires the player to decide when and to what degree to extend the racquet. This takes away focus from the game and distracts the player. Lastly, it would be very challenging to use this invention on the serve because the player would have to make the adjustment mid-swing. If the adjustment was made at the onset of the swing, the extended racquet would hit the ground on the takeback.
In yet another known prior art, U.S. Pat. No. 5,524,879 to Lyle dated Jun. 11, 1996, a locking sleeve is used in conjunction with a spring loaded roller to easily adjust the length of a racquet. This invention also requires both hands to operate, thus making it a distraction to the player. This mechanism is also not suitable to be used during a serve because of the propensity to hit the ground.
The last prior art worth mentioning is Chinese Pat. CN 205084346 U, to Wang et al. dated Mar. 16, 2016. The invention refers to a telescopic badminton racket. With this barrel cam design, the invention is comprised of radial and longitudinal grooves, detents, and a provision. More specifically, the outer handle has multiple radial grooves and a single longitudinal groove on the inside wall. Detents are embedded at various locations in the radial grooves. The shaft also has a provision at its base to accept a detent to lock it in place. To extend, the shaft must first be rotated along a radial groove and disengaged from its detent. After this, the shaft must be pulled out telescopically along the longitudinal groove and rotated into a different radial groove until another detent is engaged. Apart from the same two drawbacks prevalent in both Hedberg and Lyle, it is questionable whether this arrangement in the badminton racket can be adopted into a tennis racquet. The latter will require a substantial stiffening of the mechanism and a major resizing. These changes are crucial because the tennis ball and the hitting forces are greatly increased from those of badminton.
Objects and AdvantagesIt is a principal object of the invention to provide a new extendable and retractable tennis racquet which overcomes the disadvantages of the prior art in a simple but effective manner. This biomechanically designed tennis racquet requires no conscious decision from the player or physical adjustment on the racquet. The extension and retraction of the racquet are both done automatically, as a byproduct of the natural swing. This eliminates the distractions that were required in all previous adjustable length racquets.
It is a major object of the invention to afford a height advantage during the serve. The inherent delayed deployment of the mechanism allows the racquet to be swung through the take-back without hitting the ground.
It is another object of the invention to provide an extendable and retractable tennis racquet which affords a longer reach on groundstrokes.
It is yet another object of the invention to provide a more compact racquet configuration at the onset of the swing, resulting in a shortened duration for the complete swing motion. The racquet will accelerate faster due to the decreased drag, similar to a shorter racquet; this translates to a time advantage for the player to move the racquet or to get it into position for the next shot.
It is a further object of the invention to provide a racquet with a varying weight distribution or balance during gameplay. At the start of a swing or a volley, the racquet is at the retracted and compact position. These handling characteristics are comparable to a head-light racquet. When the ball is struck during a serve or a groundstroke, the racquet is fully extended; thus, its handling characteristics are similar to a head-heavy racquet.
It is an additional object of the invention to provide an extendable and retractable tennis racquet which is comparable in weight to a standard racquet. No significant weight penalty is incurred due to its simplistic design.
Accordingly, several advantages of our invention are:
a) The racquet mechanism is based on biomechanics, meaning that the advantages derived from the racquet come as a result of the forces created during the natural movement of playing tennis. As a result, the player does not have to play differently in order to utilize the advantages afforded by our invention. The player can stay more focused on gameplay because the extension and retraction are done automatically.
b) The extendable racquet offers a height advantage during the serve. The contact point of a player with an additional height advantage is higher up from the ground. Thus, the player can hit the ball more downwards. The serviceable area, or maximum area the player can hit into on the serve as a result of his or her vertical reach, is also significantly increased, which allows for a larger margin of error on the serve.
c) On the serve, the inherent delayed deployment of the mechanism allows the racquet to be swung through the take-back without hitting the ground.
d) On the serve and groundstrokes, the racquet is extended at contact. It affords the player a larger moment arm and therefore, better leverage. Thus, the player can hit the ball harder with more spin. The extended racquet also gives the player a longer reach.
e) For two of the three parts of the swing, the invention will afford a time advantage for the player. The retracted racquet at the onset of the swing will accelerate faster due to the decreased drag, similar to that of a compact racquet. This also applies at the end of the swing. The invention decreases the overall duration of any typical shot, giving the player more time to prepare for the next shot.
f) The invention has a varying balance during gameplay. The retracted racquet has the advantages of a head-light racquet: increased control, maneuverability and less shock on the arm. These characteristics are most beneficial during volleys at the net. On the other hand, the extended racquet has the advantages of a head-heavy racquet: increased power and the ability to swing the racquet faster. These characteristics are most beneficial during a groundstroke or on the serve. The extendable and retractable racquet combines all of the aforementioned virtues.
g) Since the racquet mechanism is simplistic in design with few added elements, the increase in weight over a standard racquet is minimal. No specific change in terms of technique is needed to take advantage of the current invention. Therefore, it would be a smooth and easy transition for any player to adopt this new racquet.
Further objects and advantages of our invention will become apparent from a consideration of the drawings and ensuing description.
For a better understanding of the present invention, reference is made to the accompanying drawings in which
01 Stringed frame head
02 Throat 03 Shank 04 Handle05 Hollow handle
06 Retracted shank
08 Extended shank
09 Stretched spring
11 Start of serve motion
13 Trophy position
14 Back-scratch position
15 Contact point
17 Back swing
18 Forward swing
19 Locus of racquet tip
22 Forehand groundstroke
23 Forehand volley
24 Extended racquet head position
25 Standard racquet head position
26 Additional reach
27 Retracted racquet head position
28 Forward racquet motion
31 Flat serve down the middle
32 Angled flat serve
33 Serviceable area
34 Vertical reach
35 Larger serviceable area due to additional vertical reach
41 Mechanical stop feature on shank
42 Mechanical stop feature on handle
51 Torsion spring
52 Pinion gear
53 Rack gear
The present invention relates to the field of tennis, especially extendable and retractable tennis racquets. In its broadest aspect, the invention is an extendable and retractable tennis racquet that provides added advantages to players. The racquet design is biomechanical, meaning that the advantages derived from the racquet come as a result of the natural movements of playing tennis. The centrifugal force generated by the natural swing pulls on the head assembly, which extends the racquet. Towards the end of the swing, the player decelerates the racquet, resulting in a diminishing of centrifugal force. As the centrifugal force is overcome by the restoring force in the spring, the head assembly is pulled back to its retracted position. The aforementioned invention described is only one embodiment.
Description of the Preferred EmbodimentReferring now to
The racquet design of the present invention is biomechanical, meaning that the advantages derived from the racquet come as a result of the natural movements of playing tennis. The spring mechanism to extend the racquet is actuated by the centrifugal force generated during the swing. Extension of the racquet allows for longer reach, resulting in more powerful shots. After the ball is struck, the swing motion during the follow-through moderates and the deployment force diminishes. Consequently, the restoring force in the spring retracts the racquet back to its nominal length. Thus, racquet extension and retraction automatically becomes part of the swing. This synchronization does not require conscious decision or physical adjustment, resulting in minimal change for a player to adopt this new racquet. Due to the simplistic design, the weight of the extendable and retractable racquet is comparable to that of a standard tennis racquet.
There is minimum clearance between the shank 03 and hollow handle 05 so that the shank can slide longitudinally in and out of the cavity of the hollow handle without any lateral free play. This tight fit must be maintained throughout the telescopic deployment range to ensure the overall racquet stiffness necessary to hit the ball effectively. Detailed design of both the shank and hollow handle can include complex structural cross-sections to increase the cross-sectional area and moment of inertia, and a mating feature to ensure a tight fit between the parts.
Unlike multiple prior art inventions, racquet deployment does not affect the exterior surface of the hollow handle 05. As such, the removal or reapplication of the grip material is unnecessary. Thus, the grip material can remain on the exterior surface of the hollow handle throughout the racquet extension and retraction.
In the first embodiment of the present invention,
On the serve motion, a longer or extended racquet will increase the vertical reach of the player. Refer to the serve motion 21 and additional vertical reach 26 in
In reality, there is a limitation on the racquet length as can be seen in
The advantages of this invention can be seen in various shots of the game in
For volleys, the best racquet position is the retracted position where control is of prime importance. The present invention allows the player to maintain the retracted racquet position. In a typical volley shot, there are no large swing motions. Instead, the racquet is moved forward 28 slightly, shown in volley play 23 in
This invention combines the advantages of a head-light racquet and the advantages of a head-heavy racquet in one racquet. The head-light characteristics of increased control, maneuverability, and less arm shock are most beneficial during volleys. On the other hand, the head-heavy characteristics of increased power and faster racquet acceleration are most beneficial during a serve or groundstroke. The invention allows the player to achieve all virtues without having to play differently. The player will have all the advantages based on which shot he or she hits.
In addition to more vertical reach on serves, longer reach on groundstrokes, and the removal of unnecessary conscious decisions, this invention can also generate a time advantage by reducing the overall duration of a serve or groundstroke. At the start of a swing, the racquet is in the retracted position. This more compact racquet configuration will accelerate faster due to the decreased drag, which consequently shortens the duration for the starting portion of the swing motion. In the next part of the swing, the racquet is now fully extended prior to contact. The drag on the racquet is comparable to that of a longer racquet. There are no time advantages to be gained during this small part of the entire swing. In the last part of the swing, the racquet is retracting due to the diminishing centrifugal force. Once again, there will be a time advantage due to the more compact racquet configuration. The overall duration is reduced, giving the player more time to prepare for the next shot.
Since the amount of extension is related to the centrifugal force derived by the racquet on a swing, a player can select the amount of desired extension by choosing a spring with a specific stiffness. In other words, this invention can be customized to the particular preference of the player.
Description and Operation of Alternate EmbodimentsThis invention relates to an extendable and retractable tennis racquet that can be used to optimize gameplay on the court. The biomechanical design frees the player from having to make a conscious decision of whether to extend the racket. The longer reach results in a lengthened moment arm and therefore, a more powerful shot.
The spring mechanism used in the current invention can be replaced with a two-way ratchet mechanism with an enabling toggle mechanism and a return mechanism. Once the toggle mechanism is set in place, the racquet can be extended during gameplay. A different setting on the toggle mechanism will enable the return mechanism to retract the racquet to its original length. While this design is still biomechanical in nature, it does require some physical adjustments on the player's part. In addition, the higher complexity of the design will require more elements and may warrant an increase in weight.
As much as this invention was specifically described for tennis gameplay, it can be applied to a variety of racquet sports. An extendable and retractable racquet may be beneficial in squash and badminton. The more compact and retracted position on the racquet will allow for a faster swing and head-light characteristics. This invention is equally advantageous to the golf game. An extendable and retractable shaft will also allow a faster swing and a more powerful drive.
Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments. It will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
Claims
1. A tennis racquet having the means to extend and retract, comprising:
- a stringed frame head with a throat;
- a shank connected to said throat;
- a handle;
- means for joining said shank and said handle telescopically, allowing only a relative sliding motion in the longitudinal direction; and
- a spring or flexible means to connect both said shank and said handle to prevent said shank to detach from said handle longitudinally.
2. The tennis racquet of claim 1, wherein said stringed frame head, throat and shank are one integral member.
3. The tennis racquet of claim 1, wherein said shank and said handle are comprised of complex cross-sections to increase stiffness.
4. The tennis racquet of claim 1, wherein said handle has a cavity means to accept a portion of said shank.
5. The tennis racquet of claim 4, wherein said spring or flexible means connects to the inside bottom of the cavity of said handle and base of said shank.
6. A tennis racquet having the means to extend and retract, comprising:
- a stringed frame head with a throat;
- a shank connected to said throat;
- a handle;
- means for joining said shank and said handle telescopically, allowing only a relative sliding motion in the longitudinal direction;
- a spring or flexible means to connect both said shank and said handle to prevent said shank to detach from said handle longitudinally; and
- a mechanical stop means between the said shank and said handle.
7. The tennis racquet of claim 6, wherein said stringed frame head, throat and shank are one integral member.
8. The tennis racquet of claim 6, wherein said shank and said handle are comprised of complex cross-sections to increase stiffness.
9. The tennis racquet of claim 6, wherein said handle has a cavity means to accept a portion of said shank.
10. The tennis racquet of claim 9, wherein said spring or flexible means connects to the inside bottom of the cavity of said handle and base of said shank.
11. A tennis racquet having the means to extend and retract, comprising:
- a stringed frame head with a throat;
- a shank connected to said throat;
- a handle;
- means for joining said shank and said handle telescopically, allowing only a relative sliding motion in the longitudinal direction;
- a pinion gear mounted to said handle;
- a rack gear mounted to said shank; and
- a torsion spring connecting to both said pinion gear and said handle; and said pinion gear is engaged to said rack gear.
12. The tennis racquet of claim 11, wherein said stringed frame head, throat and shank are one integral member.
13. The tennis racquet of claim 11, wherein said shank and said hollow handle are comprised of complex cross-sections to increase stiffness.
14. The tennis racquet of claim 11, wherein said handle has a cavity means to accept a portion of said shank.
15. The tennis racquet of claim 11, wherein said pinion gear is mounted to the shank; said rack gear is mounted to said handle; and said torsion spring connecting to both pinion gear and said shank.
16. The tennis racquet of claim 1 further including a mechanical stop means between the said shank and the said handle.
17. The tennis racquet of claim 1, wherein the said spring or flexible means is a torsional spring; and the said torsional spring connecting to the said handle via a pinion gear and a rack gear.
Type: Application
Filed: Sep 24, 2016
Publication Date: Mar 29, 2018
Inventors: Nicholas Lo (Irvine, CA), Patrick Lo (Irvine, CA)
Application Number: 15/275,377