Abstract:
A telescopic support is provided for an armrest of a chair. The telescopic support includes a lower tube, an upper tube and a helical spring. The lower tube is installed on the chair. The upper tube telescopically receives the lower tube and supports the armrest. The helical spring is axially positioned in the upper tube and compressed between the upper tube and the lower tube for automatically and smoothly lifting the upper tube from the lower tube.

Description:
BACKGROUND OF INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The present invention relates to an armrest and, more particularly, to a telescopic support for an armrest.  
         [0003]     2. Related Prior Art  
         [0004]     Disclosed in Taiwanese Patent Publication no. 451658 is a telescopic support for an armrest  4 . The telescopic support includes a first tube  1 , a second tube  2  telescopically inserted in the first tube  1  and a control device  3  provided between the first tube  1  and the second tube  2 . The first tube  1  includes two racks  111  and  121 . The control device  3  includes two toothed wheels  32  and  33  attached to the second tube  2 . The toothed wheels  32  and  33  can be engaged with two racks  111  and  121  of the first tube  1 . A detent  34  is pushed to the toothed wheels  32  and  33  by a spring  36 . The detent  34  includes two toothed portions  341  and  342  for engagement with the toothed wheels  32  and  33  so that the toothed wheels  32  and  33  can not rotate. Hence, the racks  111  and  121  can neither be lifted nor lowered, i.e., the armrest  4  can neither be lifted nor lowered. The detent  34  is connected to a switch  43  via a cable  35  so that the detent  34  can be disengaged from the toothed wheels  32  and  33  by operating the switch  43 . The toothed wheels  32  and  33  can rotate. Hence, the racks  111  and  121  can be lifted or lowered, i.e., the armrest  4  can be lifted or lowered. The lifting of the armrest  4  is however not automatically conducted.  
         [0005]     The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.  
       SUMMARY OF INVENTION  
       [0006]     According to the present invention, telescopic support is provided for an armrest of a chair. The telescopic support includes a lower tube, an upper tube and a helical spring. The lower tube is installed on the chair. The upper tube telescopically receives the lower tube and supports the armrest. The helical spring is axially positioned in the upper tube and compressed between the upper tube and the lower tube for automatically and smoothly lifting the upper tube from the lower tube.  
         [0007]     The primary advantage of the telescopic support of the present invention is the automatic and smooth lifting of the upper tube from the lower tube for the use of the helical spring.  
         [0008]     Other advantages and features of the present invention will become apparent from the following description referring to the drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]     The present invention will be described through the illustration of two embodiments referring to the drawings.  
         [0010]      FIG. 1  is a perspective view of a telescopic support for an armrest according to the first embodiment of the present invention.  
         [0011]      FIG. 2  is an exploded view of the telescopic support shown in  FIG. 1 .  
         [0012]      FIG. 3  is a cross-sectional view of the telescopic support along a line  3 - 3  in  FIG. 1 .  
         [0013]      FIG. 4  is a cross-sectional view of the telescopic support in another position than shown in  FIG. 3 .  
         [0014]      FIG. 5  is a cross-sectional view of the telescopic support in another position than shown in  FIG. 4 .  
         [0015]      FIG. 6  is a perspective view of a telescopic support for an armrest according to the second embodiment of the present invention.  
         [0016]      FIG. 7  is an exploded view of the telescopic support shown in  FIG. 6 .  
         [0017]      FIG. 8  is a cross-sectional view of the telescopic support along a line  8 - 8  in  FIG. 6 .  
         [0018]      FIG. 9  is a cross-sectional view of the telescopic support in another position than shown in  FIG. 8 .  
         [0019]      FIG. 10  is a cross-sectional view of the telescopic support in another position than shown in  FIG. 9 .  
         [0020]      FIG. 11  is a cross-sectional view of the telescopic support along a line  11 - 11   FIG. 6 .  
         [0021]      FIG. 12  is another cross-sectional view of the telescopic support in another position than shown in  FIG. 9 . 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0022]     Referring to  FIG. 1 , there is shown a telescopic support for an armrest according to a first embodiment of the present invention. The telescopic support includes a lower tube  70  and an upper tube  10 .  
         [0023]     Referring to  FIG. 2 , the upper tube  10  includes an enlarged upper portion  11 , an opening  13  near the enlarged upper portion  11  and two stems  12  on the enlarged upper portion  11 .  
         [0024]     A retainer  60  consists of two identical halves  64 . The retainer  60  includes an enlarged upper portion  62 . The retainer  60  defines a channel  66  and two series of separate recesses  61  in communication with the channel  66 .  
         [0025]     The retainer  60  is inserted in the lower tube  70  except the enlarged upper portion  62  thereof positioned on an upper end of the lower tube  70 . The retainer  60  is secured to the lower tube  70  by a screw  72  driven into a bore  63  defined in the retainer  60  through an aperture  72  defined in the lower tube  70 .  
         [0026]     A guide  20  includes a rod  29  and a platform  28  formed on the rod  23 . The platform  28  defines two apertures  21  for receiving the stems  12  of the upper tube  10  when the plat form  28  is installed on the enlarged upper portion  11  of the upper tube  10  as the guide  20  is inserted in the upper tube  10 . The platform  28  is secured to the enlarged upper portion  11  of the upper tube  10  by two threaded bolts  14 .  
         [0027]     The rod  29  defines a longitudinal groove  23  and two lateral apertures  25  in communication with the groove  23 . A stem  24  is formed on the floor of the groove  23 . A hook  27  is formed on the floor of the groove  23  near a lower end of the rod  29 . A restraint  26  is formed on each of two walls of the groove  23 . Two screws  22  are driven into the rod  29 .  
         [0028]     Positioned in the apertures  25  are two balls  50  for insertion into selected ones of the recesses  61  of the retainers  60 .  
         [0029]     A controller  30  includes a bent upper section  31 , a bent lower section  32  and a wedge  35  formed between the bent upper section  31  and the bent lower section  32 . The wedge  35  includes two inclined facets  36  for pushing the balls  50 . The controller  30  defines a slot  33  between the bent upper section  31  and the wedge  35 .  
         [0030]     The controller  30  is movable in the groove  23  while the slot  33  receives the stem  24 . A tension spring  37  includes an upper end hooked by the hook  32  and a lower end hooked by the hook  27  so as to bias the wedge  35  against the balls  50 .  
         [0031]     The bent upper section  31  of the controller  30  is exposed from the upper tube  10  through the opening  13 . A handle  80  is connected to the bent upper section  31  of the controller  30 .  
         [0032]     The rod  29  is inserted through a helical compression spring  40  that is provided between the enlarged upper portion  62  of the retainer  60  and the screws  22  secured to the rod  29 . Hence, the helical compressing spring  40  tends to lift the guide  20  and the upper tube  10  from the retainer  60  and the lower tube  70 . An upper end of the helical compression  40  contacts the platform  28  at two symmetrical points centered at the rod  29 . Therefore, the helical compression spring  40  can lift the upper tube  10  from the lower tube  70  very smoothly.  
         [0033]     Referring to  FIG. 3 , the spring  37  pulls the controller  30  to a lower position. The wedge  35  comes between and pushes the balls  50  into selected ones of the recesses  61  of the retainer  60 . Hence, the upper tube  10  cannot be moved towards and from the lower tube  70 .  
         [0034]     Referring to  FIGS. 4 and 5 , a user can lift the handle  80  so as to lift the controller  30 . The wedge  35  is moved to an upper position so that it is not between the balls  50 . The balls  50  can be moved from the recesses  61  of the retainer  60 . The balls  50  will not fall from the apertures  25  because of the restraints  26  and the wedge  35 . The upper tube  10  can be lowered and lifted relative to the lower tube  70 . Now, the helical compression spring  40  can lift the upper tube  10  from the lower tube  70 .  
         [0035]     Referring to  FIGS. 6 through 12 , there is shown a telescopic support according to a second embodiment of the present invention. The telescopic support includes a lower tube  60 B and an upper tube  10 B.  
         [0036]     The lower tube  60 B defines two opposite series of apertures  62 B in communication with one another. A cap  61 B is installed on an upper end of the lower tube  60 B.  
         [0037]     The upper tube  10 B includes two opposite apertures  13 B defined therein, a cutout  15 B defined in the edge of one of the apertures  13 B and two lips  14 B and  16 B each formed around related one of the apertures  13 B. The lip  16 B includes a groove  161 B on an internal side.  
         [0038]     A controller  80 B includes a latch  813 B, a spring  82 B, a threaded bolt  831 B, a washer  832 B and a cover  84 B.  
         [0039]     The latch  813 B includes a button  81 B formed at an end, a ridge  815 B longitudinally formed thereon and two reduced sections  814 B.  
         [0040]     The cover  84 B includes a plurality of slits  841 B defined in the edge and a ridge  842 B formed along the edge.  
         [0041]     In assembly, the spring  40  is positioned in the upper tube  10 B before the lower tube  60 B is inserted in the upper tube  10 B. The spring  40  is compressed between the platform  11 B and the cap  61 B. The spring  40  tends to lift the upper tube  10 B from the lower tube  60 B. A lower end of the spring  40  is fit on a portion of the cover  61 B so that the position of the spring  40  is retained and that the upper end of the spring  40  is always located against the center of the platform  11 B. Hence, the spring  40  can lift the upper tube  10 B from the lower tube  60 B smoothly.  
         [0042]     The spring  82 B is installed on the latch  813 B that is inserted in the apertures  13 B and the series of apertures  62 B. The ridge  815 B is positioned in the cutout  15 B so that the latch  813 B cannot be rotated. The button  81 B is biased by the spring  82 B. The threaded bolt  831 B is driven in an opposite end of the latch  813 B through the washer  832 B. The cover  84 B is positioned in the lip  16 B. The slits  841  facilitate the insertion of the cover  84 B. The ridge  842 B is fit in the groove  161 B so as to retain the cover  84 B in the lip  16 B.  
         [0043]     The upper tube  10 B can be moved between lower and upper positions on the lower tube  60 B referring to  FIGS. 8 and 10 , respectively.  
         [0044]     Referring to  FIG. 11 , the reduced sections  814 B of the latch  813 B are not located in the two series of apertures  62 B so that the latch  813 B cannot be moved in the two series of apertures  62 B. Hence, the position of the upper tube  10 B on the lower tube  60 B is retained.  
         [0045]     Referring to  FIGS. 9 and 12 , the button  81 B is pressed so that the reduced sections  814 B of the latch  813 B are located in the two series of apertures  62 B so that the latch  813 B can be moved in the two series of apertures  62 B. Therefore, the position of the upper tube  10 B on the lower tube  60 B can be changed.  
         [0046]     The present invention has been described through the illustration of the embodiments. Those skilled in the art can derive variations from the embodiments without departing from the scope of the present invention. Therefore, the embodiments shall not limit the scope of the present invention defined in the claims.