Abstract:
A force-transmitting head for a chiropractic adjustor apparatus includes a hub which is rotatable in a cavity formed in the head and non-rotatably attached to a reciprocating shaft of the apparatus. A rotation pin extends through the body into the cavity and engages a track formed in the hub. Reciprocating movement of the shaft and hub causes a rotational movement of the body with passage of the rotation pin along the track. Also, a chiropractic adjustor apparatus incorporating the force-transmitting head.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of co-pending U.S. application Ser. No. 10/174,622 filed Jun. 19, 2002, which in turn claims the benefit of U.S. application Ser. No. 09/749,023 filed Dec. 26, 2000 and now issued as U.S. Pat. No. 6,537,236. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention generally relates to a rotation hub for a chiropractic adjustor apparatus used to apply vibratory energy or force to a patient. More particularly, the invention relates to a chiropractic adjustor apparatus that allows limited, controlled rotation of a force-transmitting head during use.  
       BACKGROUND OF THE INVENTION  
       [0003]     Chiropractic adjustments of the spinal vertebrae of a body involve the application of pressure or force in a known manner directly to the body by the hands of a chiropractor or by a chiropractic adjustor apparatus. Examples of such chiropractic adjustor apparatuses found in the prior patent art are those disclosed in U.S. Pat. No. 4,716,890 to Bichel and U.S. Pat. No. 4,841,955 to Evans et al.  
         [0004]     Another example of a prior art chiropractic adjustor apparatus is described in the Applicant&#39;s earlier patent, U.S. Pat. No. 6,537,236. This patent describes an apparatus that includes a housing, a handle on the housing, a trigger reciprocally mounted to the handle, an electronic control module provided in the handle and activated by depression and release of the trigger, and an elongated force-transmitting shaft reciprocally mounted through the housing. An electromagnetic drive mechanism is disposed in the interior cavity of the housing and connected electrically to the electronic control module. The chiropractic adjustor is operable by the actuation of the trigger and the return action of a compressible spring near the rear portion of the housing, causing the shaft to transmit vibratory energy to the human body.  
         [0005]     The electromagnetic drive mechanism includes a spool with stationary electrical windings supported in the interior cavity of the housing and a stator mounted on the shaft and disposed within a bore of the spool in an electromagnetically coupled relationship with the electrical windings about the spool. Depressing the trigger activates the electrical control module to apply predetermined pulses to the electrical windings so as to actuate the stator and thus the shaft into a repetitive reciprocal vibratory type of movement along a longitudinal axis of the shaft and relative to the housing.  
         [0006]     One operation performed by a chiropractor is manipulation of the spine. A U-shaped force-transmitting head is commonly fitted to the shaft for this operation. The U-shaped head is placed to straddle the spine such that one arm of the U is on each side of the spine.  
         [0007]     During operation, many of the prior art devices tend to rotate, or twist, out of the user&#39;s grip, as a result of the rotational components of the force exerted on the shaft by the electromagnetic drive mechanism, requiring the operator to exert significant effort to hold the device substantially perpendicular to the patient&#39;s vertebrae. The earlier patent of the Applicant, U.S. Pat. No. 6,537,236, describes a mechanism to resist such rotation so that the device can be held in the proper position along the patient&#39;s spine. The mechanism described is a pin mounted across a forward portion of the shaft that moves with the shaft. The pin moves in a slot formed in a sleeve attached to the housing of the adjustor. The pin and slot combination allows the shaft to move longitudinally but prevents rotation. The description in U.S. Pat. No. 6,537,236 is incorporated herein by reference.  
         [0008]     It has been found that it is desirable to allow some degree of rotation of the force-transmitting head during operation of the chiropractic adjustor. Therefore, it is an object of this invention to provide a device that allows a controlled amount of rotation of the head during operation. It is a further object of this invention to provide a head that depresses a controlled distance while rotating a controlled distance. It is a further object to provide a force-transmitting head that can be rotated to the right or left a desired amount.  
       SUMMARY OF THE INVENTION  
       [0009]     In one form the invention resides in a force-transmitting head for a chiropractic adjustor apparatus, the head comprising a body; a cavity formed in one end of the body; a hub rotatable in the cavity relative to the body; at least one track formed in the hub; and at least one rotation pin extending from the body into the cavity and engaging the track such that longitudinal movement of the hub relative to the body causes rotational movement of the body with passage of the rotation pin along the track. In the preferred embodiment, the track is substantially L shaped.  
         [0010]     In a further form the invention resides in a chiropractic adjustor apparatus having a housing having a central interior cavity; an electromagnetic drive mechanism mounted in the interior cavity of the housing; a shaft extending through the electromagnetic drive mechanism and extending beyond the housing; means for actuating the electromagnetic drive mechanism to cause repetitive reciprocal movement of the shaft along a longitudinal axis of the shaft and relative to the housing; and a force-transmitting head comprising a body; a cavity formed in one end of the body; a hub attached to the shaft and rotatable in the cavity relative to the body; at least one track formed in the hub; and at least one rotation pin extending from the body into the cavity and engaging the track such that repetitive reciprocal movement of the shaft and hub causes rotational movement of the body with passage of the rotation pin along the track. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a longitudinal sectional view of a prior art chiropractic adjustor apparatus;  
         [0012]      FIG. 2  is an enlarged cross sectional view of the apparatus taken along line  2 - 2  of  FIG. 1 .  
         [0013]      FIG. 3  is a perspective view of a chiropractic adjustor apparatus with one embodiment of an improved force-transmitting head according to the present invention; and  
         [0014]      FIG. 4  is an exploded perspective view of the improved force-transmitting head of  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     Referring to the drawings and particularly to  FIG. 1  and  FIG. 2 , there is illustrated a chiropractic adjustor apparatus of the prior art, generally designated  40 . The apparatus  40  basically includes a housing  42  with a handle  50 . An electromagnetic drive mechanism  46  located within the housing  42  is actuated by a trigger  102  that is electrically connected to an electronic control module  104  and hence to electromagnetic drive mechanism  46  by wires  106 . Depression of the trigger  102  actuates the drive mechanism  46  to cause repetitive reciprocal vibratory movement of the shaft  44  relative to the housing  42 .  
         [0016]     A pin  88  is mounted through the forward portion of the shaft  44  in a transverse relationship thereto. A sleeve  90  extends about and along the forward portion of the shaft  44  and has a longitudinal slot  92  receiving each end of the pin  88  such that the shaft  44  can undergo longitudinal movement through the sleeve  90  relative to the housing  42  but cannot undergo rotation about a longitudinal axis of the shaft  44 . Front plug  114  provides a stop which is abutted by each end of pin  88 . The arrangement of the pin  88 , sleeve  90 , slot  92  and front plug  114  is shown most clearly in  FIG. 2 .  
         [0017]     The force applied by the elongated shaft  44  can be adjusted by rotation of knob  108  disposed on a rear end of the shaft  44  which cooperates with first and second springs  110 ,  112  disposed on either side of rear plug  116 . By turning the knob  108  the return force imposed by the springs  110 ,  112  on the shaft  44  can be increased or decreased to thereby adjust the amount of vibratory force applied to the human body at the front end of the shaft  44 .  
         [0018]     A plurality of force transmitting heads of different configurations, such as  122 , are adapted to be fitted to a hex shaped segment  124  on the front end of the shaft  44  and placed against a part of the human body to be treated. Other polygonal shapes may be used to resist rotation, as explained in the prior art. The different configurations of the heads  122  allow for the application of force in different ways to the human body. The head shown in  FIG. 1  is a simple ball and the head shown in  FIG. 4  is a U shape. The adjustor apparatus  40  has a mode of operation similar to that of a jack hammer or the like. In the case of the apparatus  40 , vibratory impacts are transmitted at the front end of the shaft  44  by the selected one of the force transmitting heads  122  when it is placed against the desired part of the human body.  
         [0019]     Referring now to  FIG. 3  there is shown a chiropractic adjustor apparatus  40  having a shaft  44  with a hex shaped segment  124  at one end. An improved force-transmitting head  125  is shown attached to the shaft  44  via a rotation hub  126  which is held in the head  125  by rotation pin  132 .  
         [0020]     Detail of the improved force-transmitting head is shown in the exploded perspective view of  FIG. 4 . In the preferred embodiment, a U-shaped head is used. The U-shaped head  125  has first and second arms  126 A,  126 B extending from a body  128 . Each arm  126 A,  126 B terminates with a screw  129  covered by a rubber pad  130 , which contacts the patient. The body  128  has a cavity  131  which receives a hub  126 . In the preferred embodiment, the hub  126  has a hex shaped cavity  133  that fits onto the hex shaped element  124  of the shaft  44  of the chiropractic adjustor apparatus  40 . A set screw  134  locks the hub  126  to the shaft  44 . The hub  126  may be mounted on the shaft in any of the six positions defined by the mating of the hex-shaped cavity with the hex-shaped shaft, allowing the user to index the head at six different positions. Of course, the cavity  133  and element  124  may have complementary shapes other than hexagonal. For example, if a square-shaped cavity with mated square shaft are used, the user will have a choice of four head positions from which to mount the hub to the shaft.  
         [0021]     It will be appreciated that other means of locking the hub  126  to the shaft  44  will also be suitable. For instance, the hub  126  may be held directly on the shaft  44  with a pin that passes through the hub and the shaft. It will also be appreciated that heads having other than U shapes may be implemented with the improved hub.  
         [0022]     A rotation pin  132  passes through the body  128  into the cavity  131 , and hence into a track  135  formed in the hub  126 . The track  135  is shaped so that relative longitudinal movement between the hub  126  and the head  125  causes a relative rotation due to the passage of the rotation pin  132  in the track  135 . Alternatively the pin may be an integral extension from the body  128  into the track  135 . A bias means, such as a spring  136 , biases the head  125  towards an end of the track  135 . It will be appreciated that other resiliently deformable bias means, such as a rubber block, will also be appropriate.  
         [0023]     Since the hub  126  is keyed to the shaft  44  by the matching cavity  133  and element  124 , the hub  126  will remain rotationally stationary relative to the chiropractic adjustor apparatus  40  and the head  125  will rotate as it vibrates. The exact amount of relative rotation of the head  125  will depend upon the shape of the track  135  and the position of the rotation pin  132  in the track  135 . Increased pressure applied by the user will compress the bias means  136  thus moving the rotation pin  132  into a different portion of the track  135 . It is envisaged that a range of hubs  132  may be available with each head  125  and a suitable hub chosen for a certain chiropractic procedure.  
         [0024]     As shown in the preferred embodiment of  FIG. 4 , the track  135  may end in a straight section  137  generally perpendicular to the direction of vibration of the shaft  44 , thus forming a substantially L-shaped track. The straight section  137  allows the user to lock off the rotation of the head  125  by applying sufficient force to compress the biasing means  136  and twisting the head  125  so the rotation pin  132  sits in the straight section  137 . Arcuate-shaped tracks may also be implemented.  
         [0025]     The preferred embodiment has been described with reference to a single track  135  and rotation pin  132 . The track shown in the preferred embodiment of  FIG. 4  allows the head to rotate to the left and back during operation. It may be convenient to provide a second complementary track opposite the first track to enable the user to twist the head to either the right or left. In such case, a second rotation pin will extend into the cavity to engage the second track formed in the hub.  
         [0026]     Although the invention has been described by reference to the application to an electronic chiropractic adjustor, it will be appreciated by persons skilled in the art that the rotation hub is not limited by the actuation mechanism of the chiropractic adjustor. Thus the invention may also be applied to pneumatic chiropractic adjustors, such as those described in the prior art of Bichel referred to earlier.  
         [0027]     While there has been illustrated and described what is at present considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the true scope of the invention. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.