Racket String Tensioning System

Abstract

The present invention is directed at string tensioning system for use in racket stringing machines. The system produces accurate and consistent string tensions, requires minimum maintenance, works with a weak current source, such as a battery, and provides quick adjustment options, all achieved in a low-cost manner. The system may comprise a crank, a control module, a force sensor, and a brake mechanism. The system may further comprise an electric tensioning mechanism. The present invention is further directed at a string tensioning method. The method may comprise: fixing the first end of a racket string to a string holder of the string tensioning system, manually tensioning the racket string using a crank, and, in some embodiments, automatic tensioning of the racket string by an electric tensioning mechanism.

Claims

1. A string tensioning system for use with racket stringing machines, the system comprising: a crank; a force sensor coupled to the control module and configured to produce a tension signal based on a tension of a racket string; a control module configured to produce a brake signal when the tension of the racket string reaches an intermediate tension; and a brake mechanism coupled to the control module and configured to stop the crank from rotating upon receiving the brake signal.

2. The string tensioning system of claim 1, further comprising an electric tensioner.

3. The string tensioning system of claim 2, wherein the electric tensioner is configured to tension the racket string from the intermediate tension to a final tension.

4. The string tensioning system of claim 3, wherein the electric tensioner tensions the racket string when the crank cannot rotate.

5. The string tensioning system of claim 3, wherein the electric tensioner automatically tensions the racket string once the tension of the racket string reaches the intermediate tension.

6. The string tensioning system of claim 1, further comprising a tension transfer bar.

7. The string tensioning system of claim 6, where the force sensor senses a force of the tension transfer bar.

8. The string tensioning system of claim 1, further comprising an input module coupled to the control module and configured to receive user inputs, the user inputs including at least the intermediate tension of the racket string and a final tension of the racket string.

9. The string tensioning system of claim 8, wherein the intermediate tension is within 10% of the to the final tension.

10. The string tensioning system of claim 2, wherein the system is operable without a connection to a strong current source.

12. The string tensioning system of claim 2, wherein the electric tensioner is one of an electric motor and an actuator.

13. The string tensioning system of claim 2, wherein the electric tensioner provides a constant pull feature.

14. A method of tensioning a racket string, the method comprising: providing a string tensioning system, the system comprising: a crank; a force sensor coupled to the control module and configured to produce a tension signal based on a tension of a racket string; a control module configured to produce a brake signal when the tension of the racket string reaches an intermediate tension; a brake mechanism coupled to the control module and configured to stop the crank from rotating upon receiving the brake signal; fixing a first end of the racket string to a string holder of the string tensioning system, a second end of the racket string fixed to a racket; manually tensioning the racket string using the crank until the tension of the racket string is equal to the intermediate tension, causing the brake mechanism to stop the crank from rotating.

15. The method of claim 14, wherein the string tensioning system further comprises an electric tensioner configured to tension the racket string from the intermediate tension to a final tension.

16. The method of claim 15, further comprising automatic tensioning of the racket string by the electric tensioner until the tension of the racket string is equal to a final tension.

17. The method of claim 16, wherein the automatic tensioning is performed at least twice.

18. The method of claim 16, wherein the string tensioning system is operable without a connection to a strong current source.

19. The method of claim 16, wherein the electric tensioner is one of an electric motor and an actuator.

20. The method of claim 15, wherein the string tensioning system further comprises an input module coupled to the control module and configured to receive user inputs, the user inputs including at least the intermediate tension of the racket string and the final tension of the racket string.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing summary, as well as the following detailed description of preferred variations of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings variations that are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements shown. In the drawings, where:

[0017] FIG. 1a is a cross-sectional view of a typical mechanical string tensioning mechanism of a racket stringing mechanism.

[0018] FIG. 1b is a cross-sectional view of the typical mechanical string tensioning mechanism of FIG. 1a, in which the brake pin has been released.

[0019] FIG. 2 is a cross-sectional view of a typical electric string tensioning mechanism on a racket stringing mechanism.

[0020] FIG. 3 shows the electrical components of a string tensioning system, according to one embodiment of the present invention.

[0021] FIG. 4 is a cross sectional view of a string tensioning system, according to one embodiment of the present invention where the electric tensioner is an electric motor.

[0022] FIG. 5 is a cross sectional view of a string tensioning system, according to one embodiment of the present invention where the electric tensioner is an actuator.

[0023] FIGS. 6a-6e show the steps of a string tensioning method, according to one embodiment of the present invention.

[0024] FIGS. 7a-7e show the steps of a string tensioning method, according to one embodiment of the present invention.

DETAILED DESCRIPTION

[0025] Where certain elements of these implementations can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present disclosure are described, and detailed descriptions of other portions of such known components are omitted so as not to obscure the disclosure.

[0026] In the present specification, an implementation showing a singular component should not be considered limiting; rather, the disclosure is intended to encompass other implementations including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Further, the present disclosure encompasses present and future known equivalents to the components referred to herein by way of illustration.

[0027] It will be recognized that while certain aspects of the technology are described in terms of a specific sequence of steps of a method, these descriptions are only illustrative of the broader methods of the disclosure and may be modified as required by the particular application. Certain steps may be rendered unnecessary or optional under certain circumstances. Additionally, certain steps or functionality may be added to the disclosed implementations, or the order of performance of two or more steps permuted. All such variations are considered to be encompassed within the disclosure disclosed and claimed herein.

[0028] Referring now to FIG. 3, the electrical components of one exemplary string tensioning system 340 are illustrated and described in detail below. The electrical components may include a control module 342, a force sensor 344, and a brake mechanism 346.

[0029] The control module 342 may include a processor 348 and memory 350. The memory may contain at least one algorithm 252 that is executable in the processor. This algorithm 352 may be configured to enable the control module 342 to produce a brake signal based on the tension signal produced by the force sensor 344. For example, the system of FIG. 3 includes an algorithm 352 that enables the control module 342 to produce a brake signal when the tension signal indicates that the tension of the racket string is equal to an intermediate tension.

[0030] Alternatively, any of the control module functions described herein can be implemented using hardware (e.g., fixed logic circuitry such as integrated circuits), software, firmware, manual processing, or a combination thereof. Thus, the blocks discussed in the above disclosure generally represent hardware (e.g., fixed logic circuitry such as integrated circuits), software, firmware, or a combination thereof. In the instance of a hardware configuration, the various blocks discussed in the above disclosure may be implemented as integrated circuits along with other functionality. Such integrated circuits may include all of the functions of a given block, system, or circuit, or a portion of the functions of the block, system, or circuit. Further, elements of the blocks, systems, or circuits may be implemented across multiple integrated circuits. Such integrated circuits may comprise various integrated circuits, including, but not necessarily limited to: a monolithic integrated circuit, a flip chip integrated circuit, a multichip module integrated circuit, and/or a mixed signal integrated circuit. In the instance of a software implementation, the various blocks discussed in the above disclosure represent executable instructions (e.g., program code) that perform specified tasks when executed on a processor. These executable instructions can be stored in one or more tangible computer readable media. In some such instances, the entire system, block, or circuit may be implemented using its software or firmware equivalent. In other instances, one part of a given system, block, or circuit may be implemented in software or firmware, while other parts are implemented in hardware

[0031] The force sensor 344 may be coupled to the control module 342. The force sensor 344 may be any force sensor that is known in the art, including, but not limited to, Savio type, tension line, single point, s-type, load cell, and miniature force sensors. The force sensor may convert a measured force into an electrical tension signal that may be processed by the control module 342. For example, the system of FIG. 3 includes a Savio type sensor 344 configured to convert a measured tension of a racket string into a tension signal.

[0032] The brake mechanism 346 may be coupled to the control module 342. The brake mechanism 346 may be any brake mechanism that is known in the art, including, but not limited to, a clamp and an actuator. The brake mechanism 346 may activate upon receiving a brake signal from the control module 342, preventing further rotation of the crank. For example, the system of FIG. 3a includes a clamp that clamps down on a brake disc upon receiving a brake signal, preventing further rotation of the crank.

[0033] The electrical components may further include an input module 354, a display module 356, a weak current source 362, and an electric tensioner 364.

[0034] The input module 354 may be coupled to the control module 342. In this embodiment, the memory 350 of the control module 342 may include an algorithm 358 configured to process user inputs received from the input module 354. In an alternative embodiment, the input module 354 is integrated into the control module 342. In yet another alternative embodiment, the input module 354 is integrated with the display module 356. The input module 354 may be configured to receive user inputs. User inputs may include an intermediate tension of the racket string and a desired tension of the racket string. The input module 354 may receive user inputs using any input method known in the art including, but not limited to, a keyboard, buttons, and a touch screen. For example, FIG. 3 depicts an input module 354, integrated into the control module, with two arrow-shaped buttons that enable a user to input a set an intermediate racket string tension and a final racket string tension.

[0035] The display module 356 may be coupled to the control module 342. In this embodiment, the memory 350 of the control module may include an algorithm 360 configured to display control parameters using the display module 356. In an alternative embodiment, the display module 356 is integrated into the control module 352. In yet another alternative embodiment, the display module 356 is integrated with the input module 354. The display module 356 may be configured to display control parameters. The control parameters may include an intermediate tension of the racket string, a final tension of the racket string, and/or a current tension of the racket string. The display module 356 may display control parameters using any display method known in the art including, but not limited to, LCD, LED, and OLED displays. For example, FIG. 3 depicts a display module 356 with an LCD display integrated into the control module 342.

[0036] The weak current source 362 may be coupled to the control module 342. The weak current source 362 may supply power directly to the control module 342, where the control module 342 diverts power to the other electrical components. In an alternative embodiment, the weak current source 362 supplies power directly to a plurality of electrical components. The weak current source 362 may be any type of portable energy storage that supplies power to the electrical components without a constant connection to a larger electrical grid, including, but not limited to, a battery or a battery pack. For example, FIG. 3 depicts a battery 362 coupled to the control module 342. In an alternative embodiment, the weak current source 362 may a portable energy generator that that supplies power to the electrical components without a constant connection to a larger electrical grid, including, but not limited to, a solar panel. If the weak power 362 source is a portable energy storage device, such as a battery, the weak power source 362 may be rechargeable. Such recharging may occur by connecting the portable energy storage device to a larger electrical grid or to a portable energy generator. Alternatively, such recharging may occur by capturing some of the energy produced during rotation of the crank.

[0037] The electric tensioner 364 may be coupled to the control module 342. The electric tensioner 364 may be any known part or combination of parts that, ultimately, converts electric power into a mechanical motion that tensions a racket string, including, but not limited to, an electric motor or an actuator. For example, FIG. 3 depicts an electric motor coupled to the control module 342. This electric motor may be used to turn a gear to pull a tension head assembly along a winding bar, tensioning a racket string.

[0038] According to an embodiment, the electric components of the system 340 are incorporated into racket stringing machines during the manufacturing process. According to another embodiment, the electric components of the system 340 system are sold as a kit. This kit may be retrofitted into existing racket stringing machines that use mechanical tensioning mechanisms. For example, a user may remove elements of the mechanical tensioning system and replace them with elements of the kit.

[0039] Referring now to FIG. 4, one exemplary string tensioning system 440 is illustrated and described in detail below. The system may be comprised of a crank 418, a string holder 404, a control module 442, a force sensor 444, a brake mechanism 446, and a weak current source 462. The system 440 may further comprise an electric tensioner 464.

[0040] The crank 418 may rotate around the axel 419. The crank may be fixed to the disc brake 426 such that the crank 418 cannot rotate while the disc brake 426 is locked. In this embodiment, the crank 418 may be fixed to the gear 420 such that rotating the crank 418 rotates the gear 420 but rotating the gear 420 does not rotate the crank 418. This may be achieved through a two directional rachet connection between the crank 418 and gear 420. In an alternative embodiment, the crank 418 is fixed to the gear such that the gear 420 only rotates with the crank 418 and vice versa. As the crank 418 is rotated clockwise, the gear 420 rotates clockwise and pulls the entire tension head assembly 400 along the winding bar 402, tensioning the racket string 422.

[0041] In this embodiment, the force sensor 444 is a Savio type sensor, the brake mechanism 446 is a clamp, the weak current source 462 is a battery, and the electrical tensioning mechanism 464 is an electric motor.

[0042] According to an embodiment, the tension head assembly 400 with all attached components, including the system 440, are incorporated into racket stringing machines during the manufacturing process. According to another embodiment, the tension head assembly 400 with all attached components, including the system 400, are provided as a unit. This unit may be retrofitted into existing racket stringing machines that use mechanical tensioning mechanisms. For example, a mechanical tensioning mechanism can be removed from the winding bar 402 and replaced with this unit.

[0043] Referring now to FIGS. 5a-5b, one exemplary string tensioning system 540 is illustrated and described in detail below. The system may be comprised of a crank 518, a string holder 504, a control module 542, a force sensor 544, a brake mechanism 546, and a weak current source 562. The system 540 may further comprise an electric tensioner 564. The electric tensioner 564 may move the top part of tension head 500 back and forth, tensioning the racket string 522 if its tension is too low or loosening the racket string 522 if its tension is too high.

[0044] The crank 518 may rotate around the axel 519. The crank may be fixed to the disc brake 526 such that the crank 518 cannot rotate while the disc brake 526 is locked. As the crank 518 is rotated clockwise, the gear 520 rotates clockwise and pulls the entire tension head assembly 500 along the winding bar 502, tensioning the racket string 522.

[0045] In this embodiment, the force sensor 544 is a Savio type sensor, the brake mechanism 546 is a clamp, the weak current source 562 is a battery, and the electrical tensioning mechanism 564 is an actuator.

[0046] According to an embodiment, the tension head assembly 500, with all attached components, is incorporated into racket stringing machines during the manufacturing process. According to another embodiment, the tension head assembly 500, with all attached components, is provided as a unit. This unit may be retrofitted into existing racket stringing machines that use mechanical tensioning mechanisms. For example, a mechanical tensioning mechanism can be removed from the winding bar 502 and replaced with the unit.

[0047] The string tensioning systems of FIG. 4 and FIG. 5 combine elements of both mechanical tensioning systems and electric tensioners, essentially operating as a hybrid tensioning system.

[0048] These hybrid tensioning systems can, unexpectedly, use much smaller electric motors (or other electric tensioning mechanisms) than their electric counterparts. Electric tensioners require large, heavy-duty motors because the motors operate nearly continuously, performing large tensioning motions throughout the entire string tensioning process. Conversely, hybrid tensioning systems can use much smaller electric motors because the motors operate sporadically, only performing tiny corrective motions at the end of the string tensioning process, tensioning a racket string from an intermediate tension to the final tension. The ability to use smaller electric motors (or other electric tensioning mechanisms) results in many benefits:

[0049] Large motors are heavy and power hungry, requiring a constant connection to a strong current source, reducing the portability of electric tensioners. Conversely, small motors are light and energy efficient, able to work using solely a weak current source, increasing the portability of hybrid tensioning systems.

[0050] Large motors are expensive to produce, increasing the cost of electric tensioners. Conversely, small motors are inexpensive to produce, decreasing the cost of hybrid tensioning systems.

[0051] Large motors operate nearly continuously, increasing power and maintenance costs for electric tensioners. Conversely, small motors operate sporadically, decreasing power and maintenance costs for hybrid tensioning systems.

[0052] Now referring to FIGS. 6a-6e, one exemplary method of tensioning a racket string is illustrated and described in detail below.

[0053] FIG. 6a depicts a racket string 622 and a string tensioning system 640 identical to the one depicted in FIG. 6. The first end of the racket string 622 is already fixed, for example, to a racket held in a mounting plate of the racket stringing machine. The second end of the racket string 622 is free.

[0054] FIG. 6b depicts a user fixing the second end of the racket string 622 into the string holder 604 of the string tensioning system 640.

[0055] FIG. 6c depicts a user manually turning the crank 618 clockwise, pulling the entire tension head assembly 600 along the winding bar 602 and tensioning the racket string 622. The crank 618 is turned until the force sensor 644 indicates that the tension of the racket string 622 is equal to an intermediate tension, at which point the control module 642 sends a brake signal to the brake mechanism 646. The intermediate tension may be slightly below or above the final tension, based on user preference. In an alternative embodiment, the intermediate tension may be within 15% of the final tension, more preferably within 10% of the final tension, more preferably within 5% of the final tension, and most preferably within 2.5% of the final tension. In an alternative embodiment, the intermediate tension may be equal to the final tension. The intermediate tension may be selected using the user input module before or during the string tensioning process.

[0056] For embodiments of the invention that do not include an electric tensioner, the intermediate tension is the same as the final tension, both equal to the tension of the racket string after tensioning with the tension crank. For example, a user sets the intermediate tension and/or final tension to 45 lbs. He or she turns the tension crank until the tension of the racket string is equal to 45 lbs, activating the brake mechanism and preventing further crank rotation.

[0057] For embodiments of the invention that include an electric tensioner, the intermediate tension is equal to the tension of the racket string after tensioning with the tension crank and the final tension is equal to the tension of the racket string after tensioning with the electric tensioner. For example, a user sets the intermediate tension to 43 lbs and the final tension to 45 lbs. He or she turns the tension crank until the tension of the racket string is equal to 43 lbs, activating the brake mechanism and preventing further crank rotation. The electric tensioner then tensions the string up to the final tension of 45 lbs. The final tension may be equal to the intermediate tension, lower than the intermediate tension, or higher than the intermediate tension, according to user preference.

[0058] FIG. 6d depicts how, after receiving the brake signal, the brake mechanism 646 activates, clamping down on the brake disc 626 and stopping further crank 618 rotation.

[0059] FIG. 6e depicts how, after the brake mechanism 646 is activated, the electric tensioner 664 automatically turns the gear 620 and pulls the entire tension head assembly 600 along the winding bar 602, tensioning the racket string 622 if its tension is lower than the final tension or loosening the racket string 622 if its tension is higher than the final tension. The electric tensioner 664 adjusts the tension of the racket string until the tension of the racket string 622 is equal to a final tension. The final tension may be based on user preference. The final tension may be selected using the user input module before or during the string tensioning process.

[0060] The steps depicted in FIG. 6e may be repeated several times to provide a constant pull feature. For example, once the racket string 622 reaches its final tension, the electric tensioner 664 may stop pulling the tension head assembly 600. Within a few seconds, the string 622 naturally stretches and its tension drops. The electric tensioner 664 then starts pulling the tension head assembly 600 again, re-stretching the string 622 to reach its final tension a second time. Depending on the characteristics of the string, this re-stretching process can be repeated several times.

[0061] Now referring to FIGS. 7a-7e, one exemplary method of tensioning a racket string is illustrated and described in detail below.

[0062] FIG. 7a depicts a racket string 722 and a string tensioning system 740 identical to the one depicted in FIG. 5. The first end of the racket string 722 is already fixed, for example, to a racket held in a mounting plate of the racket stringing machine. The second end of the racket string 722 is free.

[0063] FIG. 7b depicts a user fixing the second end of the racket string 722 into the string holder 704 of the string tensioning system 740.

[0064] FIG. 7c depicts a user manually turning the crank 718 clockwise, pulling the entire tension head assembly 700 along the winding bar 702 and tensioning the racket string 722. The crank 718 is turned until the force sensor 744 indicates that the tension of the racket string 722 is equal to an intermediate tension, at which point the control module 742 sends a brake signal to the brake mechanism 746. The intermediate tension may be slightly below or above the final tension, based on user preference. In an alternative embodiment, the intermediate tension may be equal to the final tension. The intermediate tension may be selected using the user input module before or during the string tensioning process.

[0065] FIG. 7d depicts how, after receiving the brake signal, the brake mechanism 746 activates, clamping down on the brake disc 726 and stopping further crank 718 rotation.

[0066] FIG. 7e depicts how, after the brake mechanism 746 is activated, the actuator 764 may automatically move the top end of the tension head assembly 700 relative to the bottom end of the tension head assembly 700, tensioning the racket string 722 if its tension is lower than the final tension or loosening the racket string 722 if its tension is higher than the final tension. The electric tensioner 764 adjusts the tension of the racket string until the tension of the racket string 722 is equal to a final tension. The final tension may be based on user preference. The final tension may be selected using the user input module before or during the string tensioning process.

[0067] The steps depicted in FIG. 7e may be repeated several times to provide a constant pull feature. For example, once the racket string 722 reaches its final tension, the electric tensioner 764 may stop pulling the tension head assembly 700. Within a few seconds, the string 722 naturally stretches and its tension drops. The electric tensioner 764 then starts pulling the tension head assembly 700 again, re-stretching the string 722 to reach its final tension a second time. Depending on the characteristics of the string, this re-stretching process can be repeated several times.

[0068] While the above detailed description has shown, described, and pointed out novel features of the disclosure as applied to various implementations, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the disclosure. The foregoing description is of the best mode presently contemplated of carrying out the principles of the disclosure. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the technology. The scope of the disclosure should be determined with reference to the claims.