Abstract:
A wrist exerciser includes an upper casing member and a lower casing member that are mounted to each other to enclose a rotor therebetween. The upper casing member has a top opening, which exposes a portion of the rotor. The rotor has opposite sides on which two opposite axles are mounted respectively. The axles are rotatably coupled to an outer ring. The outer ring comprises a resiliency device. The side of the rotor that faces the resiliency device is provided with a movable catching mechanism that is releasably, selectively, and operatively coupled to the resiliency device. Thus, when the rotor is initially rotated or is towed to take a linear movement by being put in contact with a fixture surface, the resiliency device builds up compression spring force, which, when the rotor is released, causes the rotor to rotate in a reversed direction and gaining auxiliary starting power and initial rotation speed. Further, the movable catching mechanism is disengageable from the resiliency device by a centrifugal force acting thereon induced by high speed rotation of the rotor so as to allow for regular operation of the wrist exerciser.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a wrist exerciser that is in the form of a hollow sphere inside which a rotor is rotatably support so that by manually rotating the hollow sphere, the rotor is rotated inside the hollow sphere to thereby effect exercising of hand and wrist related muscles, and in particular to a wrist exerciser that is configured to auto-start the rotor by generating an initial auxiliary starting force acting on the rotor to facilitate regular operation of the wrist exerciser. 
   2. The Related Arts 
   A wrist exerciser is helpful in exercising hand and wrist related muscles, and is of particular therapeutic effect for rehabilitation. Examples are disclosed in Taiwan Patent No. 135058 and U.S. Pat. No. 5,800,311. Such devices are suitable for operating with one hand to exercise the wrist muscles. The operation of the wrist exerciser is initiated by providing an effective starting force and/or torque to a rotor inside the hollow casing and thereafter, the rotor can be further rotated with forces applied by wrist muscles. Thus, the initial starting of the rotor is an important issue for operating the wrist exerciser. 
   The starting of the wrist exerciser is conventionally initiated by forcibly pulling a pull rope that is wound around a circumferential groove defined in the rotor. Examples are shown in the above mentioned Taiwan and US patents. A drawback of this type of wrist exerciser is that the pull rope may easily get deviated out of the circumferential groove of the rotor, leading to incorrect and imprecise rotation of the rotor and thus failure starting of the wrist exerciser. Even when the rotor is correctly started, the rotor can gain no large starting force and initial speed. 
   U.S. Pat. No. 6,186,914 and Taiwan Patent No. 364383 teach a rack-and-gearing based starting mechanism for starting a wrist exerciser. Sufficient initial starting force and rotational speed can be gained by forcibly pulling the rack with respect to the rotor. However, it is difficult to mate the rack with the gearing after each time the rotor is stopped for the rotor does not always stop at a fixed angular position. A user has to adjust the relative relationship between parts of the wrist exerciser in order to allow engagement of the rack and the gearing. This is certainly troublesome. Further, the rack must be forcibly driven in order to ensure sufficient torque acting upon the rotor. This is not only difficult for certain users but may also hurt the user for the rack that is forcibly pulled may easily contact the hand of the user that holds the wrist exerciser. 
   US Design D464,687 discloses an electric starter that has a friction roller, which is engageable with rotor of the wrist exerciser for applying a driving force thereto. An obvious drawback is that ready engagement between the friction roller and the rotor is not easily ensured, which makes the operation difficult for certain users. In addition, the friction roller is electrically driven and, once getting in contact with a user&#39;s hand that holds the wrist exerciser, may hurt the user&#39;s hand. Further, the rotor is not maintained in a specific orbit, and this limits the driving force applied by the friction engagement to the rotor. Thus, similarly, the electric starter cannot ensure a large starting force. 
   Further, all the conventional wrist exerciser and/or the starting mechanism thereof are operated with two hands and are not suitable for handicapped persons that have one hand available. In addition, the precise engagement required between the conventional starting mechanism and the rotor of the wrist exerciser makes it difficult for the blind to operate the conventional wrist exercisers. 
   Therefore, it is desired to provide a wrist exerciser that is provided with an auxiliary starting force for efficiently and easily starting the operation of the wrist exerciser with either both hands or a single hand so as to overcome the drawbacks of the conventional devices. 
   SUMMARY OF THE INVENTION 
   Thus, an objective of the present invention is to provide a wrist exerciser that comprises a rotor that can be initially rotated by a user&#39;s finger or by being towed with respect to a fixture surface with which the rotor is put in friction engagement so that a compression spring force is built up, and when the rotor is released, the compression spring force causes the rotor to rotate in a reversed direction with a large initial torque and speed and thus ensuring the rotor with an enhanced initial power and speed. 
   Another objective of the present invention is to provide a wrist exerciser that can initiate an auxiliary starting power and initial speed for effecting precise and correct starting of the wrist exerciser. 
   A further objective of the present invention is to provide a wrist exerciser that can be operated with one single hand and that can be operated without visual feedback so that the wrist exerciser can be used by the blind and the one-hand handicapped. 
   To realize the objectives, in accordance with the present invention, a wrist exerciser comprises an upper casing member and a lower casing member that are mounted to each other to enclose a rotor therebetween. The upper casing member has a top opening, which exposes a portion of the rotor. The rotor has opposite sides on which two opposite axles are mounted respectively. The axles are rotatably coupled to an outer ring. The outer ring comprises a resiliency device. The side of the rotor that faces the resiliency device is provided with a movable catching mechanism that is releasably, selectively, and operatively coupled to the resiliency device. Thus, when the rotor is initially rotated or is towed to take a linear movement by being put in contact with a fixture surface, the resiliency device builds up compression spring force, which, when the rotor is released, causes the rotor to rotate in a reversed direction and gaining auxiliary starting power and initial rotation speed. Further, the movable catching mechanism is disengageable from the resiliency device by a centrifugal force acting thereon induced by high speed rotation of the rotor so as to allow for regular operation of the wrist exerciser. Thus, precise, safe, and single-handed starting operation of the wrist exerciser can be effected without any visual feedback. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, wherein: 
       FIG. 1  is a perspective view of a wrist exerciser constructed in accordance with a first embodiment of the present invention; 
       FIG. 2  is an exploded view of the wrist exerciser shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of a rotor of the wrist exerciser, taken in a different angle; 
       FIG. 4  is a cross-sectional view of the wrist exerciser, illustrating the structure of a resiliency device thereof; 
       FIG. 5  is a cross-sectional view of the wrist exerciser, illustrating the structure of a movable catching mechanism thereof; 
       FIG. 6  is a cross-sectional view of the wrist exerciser, illustrating the operation of the wrist exerciser by rotating the rotor with a finger; 
       FIG. 7  is a cross-sectional view of the wrist exerciser, illustrating the condition where the movable catching mechanism is subject to a large centrifugal force and thus separated from a positioning element; 
       FIG. 8  is a perspective view of a wrist exerciser constructed in accordance with a second embodiment of the present invention; 
       FIG. 9  is an exploded view of the wrist exerciser shown in  FIG. 8 ; 
       FIG. 10  illustrates operation of the wrist exerciser of the second embodiment with a single hand; and 
       FIG. 11  is a perspective view of a wrist exerciser constructed in accordance with a third embodiment of the present invention, with a counter detached from the wrist exerciser. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the drawings and in particular to  FIGS. 1-3 , a wrist exerciser constructed in accordance with a first embodiment of the present invention, generally designated with reference numeral  100 , is shown. The wrist exerciser  100  comprises an upper casing member  10  and a lower casing member  20 , both being hollow members, preferably in the form of hemisphere. The upper and lower casing members  10 ,  20  are releasably secured to each other to form a sphere. The upper casing member  10  forms an opening  11  at an apex point thereof and also forms two slots  12 ,  13  in a lower circuit flange thereof. The lower casing member  20  forms two lugs  21 ,  22  at an upper circular flange. The slots  12 ,  13  of the upper casing member  10  are respectively and receivingly engageable with the lugs  21 ,  22  of the lower casing member  20  and are secured together by bolts  211 ,  221  extending through both of them whereby the upper casing member  10  and the lower casing member  20  are releasably mounted together to define therebetween a receiving space A. It is apparent that the upper and lower casing members  10 ,  20  can be fixed together with any known and suitable means of which the combination of slots  12 ,  13  and the lugs  21 ,  22  is just one non-limiting example. 
   A rotor  30  forms axially-aligned axles  31 ,  32  on opposite sides thereof. Two connectors  311 ,  321  are formed on the two sides of the rotor  30 , respectively. A bore  312  extends through the connectors  311 ,  321  on the two sides of the rotor  30 , see  FIGS. 2 and 3 . 
   A ring  40  is arranged along the upper circular flange of the lower casing member  20 . Two diametrically aligned holes  41 ,  42  are defined in the ring. A retention member  43  is formed on an inner circumference of the ring  40  corresponding to the hole  41 . Two slots  431  are defined in the retention member  43 . 
   Also referring to  FIG. 4 , a resiliency device  50  comprises a case  51 , a resilient element  52 , a lid  53 , a drive shaft  54 , and a bearing  55 . The case  51  has an end surface on which two ribs  511  are formed. The ribs  511  are sized and located to fit into the slots  431  defined in the retention member  43  of the ring  40  to attach the case  51  to the ring  40 . In a central location of the end surface of the case  51 , a hole  512  is defined to align with the hole  41  of the ring  40 . An opening  513  is defined in a circumferential wall of the case  51 . 
   The resilient element  52  is received in the case  51 . The resilient element  52  is not limited to any specific type and a coil compression spring is taken as an example in the illustration here of the present invention. The resilient element  52  has a first end  521 , which is in the form of a hook to engage the side opening  513  of the case  51 . The resilient element  52  also has a second end  522  is substantially located at a-center of the resilient element  52 . 
   The lid  53  is attached to the case  51  to close the case  51  and thus securing the resilient element  52  inside the case  51 . The lid  53  defines, substantially at a center thereof, a through hole  531  having a circumference in which a notch  532  is formed. 
   The drive shaft  54  is a hollow shaft having two opposite ends respectively mounted to a fixed block  541  and a driving block  542 . An end of the drive shaft  54  extends through the through holes  531  of the lid  53 , with the fixed block  541  passing through the notch  532 , into the case  51  and is put into driving engagement with the second end  522  of the resilient element  52  so that the resilient element  52  is in operative coupling with the drive shaft  54 . The bearing  55  is fit on an end of the drive shaft  54 . 
   The axle  31  of the rotor  30  extends through the bearing  55  and into the interior of the hollow drive shaft  54  and further extending through the hole  512  of the case  51  to enter the hole  41  of the ring  40 . Another axle  32  of the rotor  30  is received in the hole  42  of the ring  40 . Thus, the rotor  30  is rotatably fixed to the ring  40  and is located in the receiving space A formed between the upper casing member  10  and the lower casing member  20 , with the rotor  30  being partially exposed through the top opening  11  of the upper casing member  10 . 
   Also referring to  FIG. 5 , a movable catching mechanism  60  comprises an arm  61 , a shaft  62  and at least one positioning element  63 . The arm  61  is made of magnetically conductive metal or magnet plate. A hole  611  and the a notch  612  are respectively defined in opposite ends of the arm  61 . The hole  611  is aligned with the connector  311  of the rotor  30  and the notch  612  engages the driving block  542  of the drive shaft  54  of the resiliency device  50 . The shaft  62  forms, at an end thereof, a circumferential groove  621 . With the shaft  62  extending through the hole  611  and the bore  312 , a C-clip engages the circumferential groove  621  of the shaft  62  to rotatably fix the arm  61  to the connector  311  in restricted rotation within a predetermined angular range. 
   The positioning element  63  is arranged on the rotor  30  at a location in a rotation trace of the arm  61 . The positioning element  63  is made of a magnet or a magnetically conductive metal so that the positioning element  63  can attract and thus fix the arm  61  when the rotor  30  is stationary or in low speed rotation. Thus, the arm  61  can be maintained in a coupling with the drive shaft  54  when the rotor  30  is stationary or in low speed rotation. However, it is apparent that the coupling between the arm  61  and the positioning element  63  is not limited to the magnetic attraction discussed above and can be replaced by any suitable means. 
   The coupling between the resiliency device  50  ad the movable catching mechanism  60  is not limited to the coupling formed by the engagement between the driving block  542  of the drive shaft  54  and the notch  612  of the arm  61  and can be replaced by any other suitable means. 
   Also referring to  FIG. 6 , operation of the wrist exerciser  100  is illustrated. A user holds the wrist exerciser  100  with one hand and uses a finger of the other hand to contact and move the rotor  30  through the top opening  11  of the upper casing member  10 . By rotating the rotor  30  in a given direction, such as counterclockwise direction as shown in  FIG. 6 , the arm  61  of the movable catching mechanism  60  engages and thus causes the drive shaft  54  of the resiliency to relatively rotate in an opposite direction (namely, clockwise direction in the embodiment). Thus, the fixed block  541  of the drive shaft  54  drives the resilient element  52  and thus winding and compressing the resilient element  52  so that the resilient element  52  is in possession of compressed spring force. 
   Also referring to  FIG. 7 , when the finger releases the rotor  30 , the compressed resilient element  52  also releases the spring force, which drives the drive shaft  54  in the opposite direction, namely the clockwise direction, as indicated by arrow of  FIG. 7 . Through the engagement between the driving block  542  and the arm  61  of the movable catching mechanism  60 , the rotor  30  is driven by the drive shaft  54  to rotate, for example in the counterclockwise direction in the embodiment illustrated, and the rotor  30  is supplied with an initial starting torque and rotation speed, which facilitate the rotor  30  to gain acceleration when the sphere of the upper and lower casing members  10 ,  20  is operated by the user. In other words, the rotor  30  is accelerated by the operation of the user that holds the wrist exerciser  100  with his or her hand and the auxiliary starting force ensured by the construction discussed above helps the rotor  30  to efficiently gain high speed and high torque to continuously maintain rotation. 
   When the rotor  30  gets high rotational speed, a centrifugal force imposed on the arm  61  is getting higher than the magnetic attraction caused by the positioning element  63 , and by the centrifugal force, the arm  61  is separated from the positioning element  63  and the resiliency device  50  disengages from the movable catching mechanism  60  to allow regular rotation of the rotor  30 . In this way, the conventionally used pull rope, rack and gearing device, and electrical starter are no longer needed in starting the rotor  30 . 
   When the rotor  30  of the wrist exerciser  100  is decelerated and gets back to low speed rotation or even stationary, the centrifugal force acting on the movable catching mechanism  60  gets smaller than the magnetic attraction so that the arm  61 , when rotated to pass through the positioning element  63 , is re-attracted and re-secured by the positioning element  63 , and the coupled condition illustrated in  FIG. 5  where the resiliency device  50  is coupled to the movable catching mechanism  60  is resumed. 
   Referring to  FIGS. 8 and 9 , which show a wrist exerciser in accordance with a second embodiment of the present invention; also designated with reference numeral  100  for simplicity, in the second embodiment of the wrist exerciser  100 , the rotor  30  forms at least one circumferential slot  33  in which a ring  331  is fit. The ring  331  is not limited to any specific type and a rubber ring having sufficient surface friction is taken as an example of the ring  331 . 
     FIG. 10  illustrates the operation of the second embodiment of the wrist exerciser  100  shown in  FIGS. 8 and 9 . The wrist exerciser  100  is operated with a single hand. The sphere of the upper and lower casing members  10 ,  20  is held by the hand with the top opening  11  of the upper casing member  10  facing downward to allow a portion of the rotor  30  exposed out of the opening  11  of the upper casing member  10 . The exposed portion of the rotor  30  is positioned against a fixture surface  200 , such as a tabletop, ground surface or other flat surfaces and the wrist exerciser  100  is forced to move, in a linear motion, with respect to the fixture surface to cause rotation of the rotor  30 , as illustrated in  FIG. 10  in which the wrist exercise  100  is move leftward and the contact between the ring  331  of the rotor  30  and the fixture surface  200  ensures a friction therebetween, which in turn induces rotation of the rotor  30  in the counterclockwise direction, similar to the initial rotation driven by the user&#39;s finger demonstrated in  FIG. 6  and the previous embodiment. Thus, and similar to the previous embodiment, the resilient element  52  of the resiliency device  50  is wound and compressed and build up a compression spring force so that when the wrist exerciser  100  is lifted and the rotor  30  gets off the fixture surface  200 , the spring force of the resilient element  52  is released to cause an initial, clockwise rotation of the rotor  30 , with which the wrist exerciser  100  of the second embodiment can effect the same operation of the previous embodiment as that illustrated in  FIG. 7 . The single hand operated embodiment illustrated in  FIG. 10  is preferably suitable for the handicapped. 
     FIG. 11  shows a wrist exerciser constructed in accordance with a third embodiment of the present invention, also designated with reference numeral  100  for simplicity. In the wrist exerciser  100  of the third embodiment, the lower casing member  20  defines an opening  23  in a bottom apex thereof and a counter  70  is mounted in the opening  23  for calculating the rotational speed of the rotor  30 . The counter  70  comprises a display  71  to display the rotational speed of the rotor  30 . The counter  70  can be of any suitable device, such as a photo-electrical counter or a magnetism based counter that operates in association with for example the positioning element  63 . 
   Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.