Abstract:
A cable guide is provided for a movable body such as a chair having legs with casters. The cable guide guides a cable attached to the movable member away from the casters during movement of the movable member and/or horizontal rotation of a portion of the movable member.

Description:
FIELD OF THE INVENTION 
     This invention concerns a cable guide structure which protects cables such as telephone cords, tubes or cables (hereafter called simply “cables”) when they are connected to a revolving chair with casters on its legs in such a way that they trail freely on the floor. More specifically, when electricity is supplied from the exterior to a revolving office chair with casters on its legs to provide power for a built-in health appliance such as an electric massager, shoulder heater or shiatsu device, this cable guide structure protects the power supply cable from being run over by the casters or getting wound around the legs of the chair. The scope of the invention is not limited to office chairs only; it could also be applied when a person seated in a chair is being monitored for pulse rate or other physiological data, or when a cable is providing audio or video signals to a seated person. 
     BACKGROUND OF THE INVENTION 
     An example of a revolving office chair with casters provided in the prior art is shown in FIG. 1 of U.S. Pat. No. 5,247,925 (FIG. 7 herein). This revolving chair  500  moves freely about the floor with the rotation of casters  540 . Its post  520  is able to rotate 360 degrees about its center in the horizontal plane. It is customary for a person seated in such a revolving chair with casters to move about the floor while seated in the chair. At such times, if the chair has a built-in electrical appliance to which a power supply cable  550  is connected, the cable may be trapped under casters  540  (see FIG. 8) so that the casters lock up, and the cable may be damaged. Or, as is shown in FIG. 9, casters  540  may run over the cable, so that it becomes entangled among legs  530 . This will limit the mobility of the chair and may cause damage to the cable. 
     A prior art design to alleviate these problems, which was proposed in U.S. Pat. No. 5,371,920, is shown in FIG.  10 . It provides a cylindrical guard (cylindrical portion  137 ) around each caster (wheel assembly  119 ) so that the power supply cord cannot be run over. Another solution was offered in U.S. Pat. No. 4,025,099, shown in FIG. 11. A panel (flipper plate  30 ) is provided on the front of each caster to keep the cable away from the wheels so that it cannot be run over. Panel  30  is attached by hinge pin  31  so that it hangs down under its own weight. Its front end  33 , then, is normally in contact with the floor so that it can lift up the cable. 
     However, the prior art designs for office chairs do not address the problem illustrated in FIG. 8, which occurs when several of the casters are locked simultaneously by being trapped in a cable lying on the floor. When one end of the cable is attached to the seat of the chair and the other is attached to a wall outlet, the cable&#39;s freedom of movement is limited. When the casters move, then, the cable can get hung up on them, which can result in the casters becoming locked. If people in an office frequently move their chairs around, this will happen again and again. When it does happen, the plug may be pulled out of the wall outlet, or the chair which is stuck may tilt on the fulcrum provided by the casters and fall over. 
     Or, as is shown in FIG. 9, the connection site  511  where the cable is attached to seat  510  may end up, when the seat rotates on post  520 , on the side of the chair opposite socket  522  and plug  551 . When this happens, the portion of electrical cord  550  which is on the floor can easily become entangled among legs  530  so that it hinders the free movement of casters  540 . In the prior art solutions discussed above, then, cable connection site  511  lacks a stabilized directionality with respect toward socket  552  and plug  551 ; thus the danger that the cable will become entangled on casters  540  remains unaddressed. 
     SUMMARY OF THE INVENTION 
     This invention is developed in order to eliminate the problems discussed above. The object of this invention is to provide a cable guide structure which would stabilize the direction of an electrical or other cable trailing onto the floor from a revolving office chair with casters on its legs or some other revolving and movable body. 
     Another object of this invention is to provide a cable guide structure which would make it difficult for the cable and casters to interfere with each other regardless of the movement of the casters when the cable extends from a revolving, movable chair with a built-in electrical appliance in such a way that it can move freely on the floor. 
     For this purpose, the cable guide structure according to this invention has a supporting arm which holds the electrical cable virtually horizontal in the space above the legs of the chair so that it cannot be run over by the casters. This supporting arm is mounted to the post of the chair in such a way that it can revolve around the post. The arm supports the cable in the space above the legs and leads it out a given distance from the post, where it is allowed to drop from the end of the arm to the floor. This distance is somewhat beyond the radius of the rotational path of the chair legs. Thus the cable which runs out from the chair is guided along the supporting arm until it is allowed to drop to the floor a sufficient distance beyond the casters. When the chair revolves or moves, the portion of the cable which is on the floor will not be run over by the casters. In addition, this invention also provides a caster sweeper unit for each caster to sweep away the portion of the cable which is on the floor. It thus offers two separate types of cable guide structures to prevent the cable from being run over by the casters 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a cable guide structure using a supporting arm according to the first preferred embodiment of this invention. 
     FIG. 2 illustrates a cylindrical case to fix the supporting arm. 
     FIG. 3 illustrates a cable guide structure using a supporting ring according to the second preferred embodiment of this invention. 
     FIG. 4 illustrates a cable guide structure using a conical supporting skirt according to the third preferred embodiment of this invention. 
     FIGS. 5A,  5 B, and  5 C illustrate a cable guide structure using a caster sweeper according to the fourth preferred embodiment of this invention. 
     FIG. 6 illustrates a cable guide structure using a caster belt according to the fifth preferred embodiment of this invention. 
     FIG. 7 illustrates an office chair provided with a power cable according to a prior art. 
     FIG. 8 illustrates a disadvantage of an office chair with a power cable according to a prior art. 
     FIG. 9 illustrates another disadvantage of an office chair with a power cable according to a prior art. 
     FIG. 10 illustrates another prior art structure. 
     FIG. 11 illustrates another prior art structure. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In this section we shall give a detailed explanation of several preferred embodiments of this invention, with reference to the appended drawings. Insofar as the dimensions, materials, shape, or relative positions of the constituent parts described in these embodiments are not specifically indicated, the scope of the invention is not limited to the description given, which is meant merely as an illustration. 
     FIG. 1 shows a cable guide structure  1  in accordance with a first preferred embodiment of this invention. This structure includes both a supporting arm  110  and caster sweepers  200  shown in FIGS. 5A,  5 B,  5 C. Office chair  500 , which has a built-in electrical massager, consists of seat  510 , revolving post  520 , which supports the seat, and legs  530 . Seat  510  can revolve in the horizontal plane on post  520 . Legs  530  all have casters  540  on their ends so that they can move freely about the floor. 
     Cable guide structure  1  supports electrical cable  550 , which supplies power to the electrical massager in seat  510 , in the space above the legs of the chair, and leads it from seat  510  to a location beyond the path of rotation of legs  530 . In this embodiment it includes supporting arm  110  and cylindrical case  120 . Supporting arm  110  extends outward virtually horizontally from cylindrical case  120 . It is necessarily somewhat longer than legs  530 . In other words, supporting arm  110  must be long enough so that the portion of the electrical cable which falls to the floor from the end of arm  110  cannot be run over and damaged by casters  540  when the chair moves around the floor, and long enough so that the cable does not hinder the free movement of the casters. The electrical cable  550  which originates in seat  510  is a curly cable. It is led to the site where supporting arm  110  is mounted (in the drawing, the left side of the arm  110 ) and supported horizontally as it is led through the space above legs  530 . The supporting arm takes the cable beyond the range of the path of the legs, where it is allowed to drop to the floor. 
     As can be seen in FIG. 2, cylindrical case  120  consists of discrete cases  120 - 1 ,  120 - 2  and  120 - 3 . These three cases surround and are concentric with rotary post  520 . Each of the three cases can rotate freely around the post and has a specific coefficient of friction with respect to the other cases. Post  520  and the closest case, case  120 - 1 , rotate freely with respect to each other at friction coefficient α 1 . Case  120 - 1  rotates freely with the next case,  120 - 2 , at friction coefficient α 2 . Case  120 - 2  and the furthest case,  120 - 3 , rotate freely with each other at friction coefficient α 3 . Thus the rotation moment n 1  of case  120 - 1 , the closest one to post  520 , can be determined with respect to the rotation moment n 0  of the post by the following. 
     
       
           n   1 =α 1   ×n   0   
       
     
     Similarly, the rotation moment of cases  120 - 1  and  120 - 2  and that of  120 - 2  and  120 - 3  can be obtained by the following. 
     
       
           n   2 =α 2   ×n   2   
       
     
     
       
           n   3 =α 3   ×n   2   
       
     
     Thus the friction coefficient of the furthest case,  120 - 3 , with respect to the rotation moment n 0  of post  520 , is obtained by cumulating the three friction coefficients α 1 , α 2  and α 3 ; so case  120 - 3  will barely rotate with post  520 . In other words, when seat  510 , which is attached to post  520 , rotates, supporting arm  110 , which is attached to case  120 - 3 , will barely rotate. The electrical cable  550  which is guided by the supporting arm will thus continue to lie in the same direction. 
     By providing a number of discrete cases,  120 - 1 ,  120 - 2 ,  120 - 3  we create a situation in which the coefficient of friction between each two cases is raised to a power of the coefficient of the previous two cases. Thus supporting arm  110 , which is attached horizontally to the furthest case,  120 - 3 , will be independent of the rotation of post  520 , which can then rotate smoothly. The number of discrete cases needed is determined by the cumulative coefficient of friction necessary to insure that the furthest case,  120 - 3 , will not be affected by the rotation of post  520  and legs  530 . 
     In the description given, the discrete cases are placed quite close to each other to achieve the appropriate coefficients of friction; however, the invention is not limited to this example only. Rod bearings, for example, could also be used between the cases. 
     With this configuration, supporting arm  110  rotates freely about post  520 . When post  520  rotates, then, electrical cable  550 , which hangs down at the end of supporting arm  110 , will normally continue to lie on the floor in the direction collinear with arm  110 . The cable, that is, will not be pulled when seat  510  rotates. Supporting arm  110  is an appropriate height off the floor, and extends far enough from post  520 , so that electrical cable  550  will not fall to the floor between two legs  530 . In other words, the supporting arm holds electrical cable  550  in the space above legs  530  so that when the cable does go down to the floor it cannot get tangled up in casters  540 . Supporting arm  110  can be flexible so that when it is not being used it can be retracted and stored below the upper portion of the chair. 
     FIG. 3 shows a second preferred embodiment. In place of the supporting arm  110  in the first embodiment, this embodiment has a supporting ring  130 . Ring  130  is fastened horizontally to the post in the space above legs  530  by means of mounting hardware  131 . The upper surface  132  of ring  130  is fashioned of a smooth material and shaped smoothly so that the electrical cable  550  which comes out of seat  510  will move along this smooth surface when seat  510  rotates. The diameter R of ring  130  is greater than the diameter L of the floor area defined by legs  530 . As a result, when electrical cable  550  falls to the floor from the edge of ring  130 , it is further from the post than are the casters  540  on the ends of legs  530 . The portion of cable  550  which is on the floor cannot interfere with casters  540 , and consequently casters  540  cannot run over the portion of the cable on the floor. The chair illustrated in the FIG. 3 embodiment may also employ caster sweepers  200  shown in FIGS.  5 (A),  5 (B) and  5 (C). 
     FIG. 4 shows the third preferred embodiment of the invention. Here rotary post  520  and all of casters  540  are covered by skirt  140 . Just as in the first embodiment, skirt  140  is mounted to post  520  through a number of cylindrical cases  120  in such a way that it is free to rotate. The lower edge of skirt  140  almost meets the floor, and it covers the tops of casters  540  and their entire surfaces in such a way that it keeps the portion of cable lying on the floor away from the casters. The skirt could be made of a conical plastic cover or fashioned from a metal plate. 
     Because skirt  140  is conical in shape, when the electrical cable  550  which comes out of seat  510  falls by its own weight onto the upper portion of the skirt, it will run along the surface of the cone down to the floor. Since the bottom of the skirt almost touches the floor, the portion of the cable lying on the floor will be pushed away from the chair by the skirt even when the entire chair moves across the floor. This effectively prevents the cable from being run over by casters  540 . 
     And because skirt  140  encloses the space above legs  530 , it prevents cable  550  from falling to the floor between two adjacent legs  530  and getting run over by casters  540 . 
     FIGS.  5 (A), (B) and (C) show the configuration of a caster sweeper  200 , in a fourth preferred embodiment of the invention which can be used on the casters of a chair having the cable guide structure of FIGS. 1,  3  or even FIG. 4, depending on how close skirt  140  comes to the floor. The caster sweeper  200  can also be used with the casters of a chair which does not have cable guide structure. Caster sweepers  200  are devices to lift up the portion of the cable which is on the floor. As can be seen in FIG.  5 (A), the caster sweeper has a tongue-shaped front portion  201  which covers the front surface of caster  540 . As can be seen in FIG.  5 (B), caster sweepers are mounted on both the front and rear of each caster  540 , which is fixed to the bottom of a leg  530 . Front portions  201  extend almost to the floor and are bent in such a way as to scoop up the portion of cable on the floor so that it remains parallel to the floor. Front portions  201  should be fashioned from a flexible substance such as plastic so that even when casters  540  are partially sunk into a soft carpet on the floor, portions  201  can come in close contact with the top of the carpet. They might also be molded as a single piece with caster covers  541 . As can be seen in FIG.  5 (C), front portions  201  may be fork-shaped. 
     FIG. 6 shows the fifth preferred embodiment of this invention. In place of the caster sweepers of the third embodiment, this embodiment has caster belt  210 . Instead of discrete pairs of caster sweepers  200  attached to individual casters  540  as in the third embodiment, caster belt  210  is a single piece which covers all the casters  540  which are attached to the bottoms of the legs. It pushes away any cable lying on the floor so that it will not be run over by casters  540 . The top of caster belt  210  is fastened to legs  530 . The bottom of the belt should be fashioned from a flexible substance such as plastic so that even when casters  540  are partially sunk into a soft carpet on the floor, the belt can come in close contact with the top of the carpet. 
     This invention features a cable guide structure with a simple configuration which guides an electrical cord or other cable beyond the reach of the legs of an office chair. The cord cannot interfere with the rotation of the casters, so the chair can move smoothly around the floor. If a supporting arm is used which is mounted to a cylindrical case revolving independently of the post of the chair, the electrical cord will ordinarily remain in the same orientation and will not become wound around the post. 
     The supporting arm  110 , supporting ring  130  and skirt  120  according to this invention can all be made cheaply from plastic. They are simple to mount and can be attached easily to any office chair. 
     Attaching caster sweepers  200  in front of the casters or installing a caster belt  210  will insure that any cable which happens to get close to a caster will be pushed away and will enable the office chair to be moved smoothly at all times. 
     Although the invention has been described above in connection with exemplary embodiments, it is apparent that many modifications can be made without departing from the spirit or scope of the invention. Accordingly, the invention is not to be considered as limited by the foregoing description, but is only limited by the scope of the appended claims.