Abstract:
A seat elevating mechanism for chair particularly designed for old men and patients having weak legs mainly includes a seat that can be elevated or lowered using a power-actuated telescopic lifter. The seat is maintained in a horizontal position while being elevated or lowered, so that a user may stably sit thereon until the seat is fully elevated or lowered to enable the user to get up or sit down effortlessly.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a seat elevating mechanism for chair designed to provide a supporting force that helps old men and patients to get up from or sit on a chair effortlessly. 
   BACKGROUND OF THE INVENTION 
   An old man or a patient with weak legs and slow movement has difficulty in sitting on a chair safely and effortlessly, and therefore frequently needs help of an attendant to sit on the chair. It is even more laborious for the old man or the patient having injured or weak legs to get up from the chair, particularly when there is not an attendant. 
   There are chairs with an elevating seat available in the market designed for the aged and some patients. The elevating seats of these conventional chairs are slightly higher than that of other normal chairs, and are therefore not comfortable for sitting. Since the conventional elevating seats are normally elevated using an air pump, the users still need to exert strength at two legs to get up from the elevated seats. Another disadvantage of the conventional elevating seats is the seats are forward and downward inclined when being elevated, preventing the users from stably sitting thereon. The conventional chairs with elevating seats are therefore not safe and inconvenient for use. 
   SUMMARY OF THE INVENTION 
   A primary object of the present invention is to provide a seat elevating mechanism for chair, in which the seat of the chair is electrically driven to elevate, so that a user may stably sit thereon while the seat is gradually elevated and horizontally moved forward, and may get up from the chair effortlessly when the elevated seat reaches at a desired height. 
   The seat elevating mechanism for chair according to the present invention includes a chair, a two-piece seat, a seat support, and a telescopic lifter. The seat support includes a mounting bracket fixedly mounted to a front side of the chair, and a seat-board supporting frame having front and rear portions for supporting front and rear seat boards, respectively, to a top thereof. The front and the rear portion of the seat-board supporting frame are pivotally connected to one another at two laterally spaced pivoting points. The telescopic lifter may be actuated to push the rear portion of the seat-board supporting frame upward, so that the seat-board supporting frame and the seat boards thereon are elevated and horizontally moved forward, allowing a user stably sit thereon to get up easily. 
   In the seat elevating mechanism for chair according to the present invention, the rear portion of the seat-board supporting frame is always in a horizontal position in the course of elevating or lowering, allowing the user to stably sit thereon. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
       FIG. 1  is a front perspective view of a chair with a seat elevating mechanism according to the present invention, wherein the seat is in a fully lowered position; 
       FIG. 2  is a partially phantom view showing the structure of the seat elevating mechanism of the present invention, wherein the seat elevating mechanism is in an elevated position; 
       FIG. 3  is a partially sectioned side view showing the seat elevating mechanism of the present invention in the elevated position; 
       FIG. 4  is a partially sectioned side view showing the seat elevating mechanism of the present invention in a fully lowered position; and 
       FIG. 5  is a front perspective view of the chair of  FIG. 1  with the seat in the elevated position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Please refer to  FIGS. 1 and 2 . The present invention relates to a seat elevating mechanism for a chair  10 . As shown, the set elevating mechanism mainly includes a two-piece seat  20  consisting of a front and a rear seat board  21 ,  22 , a seat support  30 , and a telescopic lifter  40 . 
   The seat support  30  includes a mounting bracket  31  fixedly mounted to a front side of the chair  10  at a predetermined position, a seat-board supporting frame  32  for supporting the two seat boards  21 ,  22  to a top thereof, two laterally corresponded horizontal arms  33  fixedly connected at one end to the fixed mounting bracket  31 , and two links  34 . 
   The whole seat-board supporting frame  32  is pivotally connected at a front side to the fixed mounting bracket  31 , so as to pivotally turn about two pivoting points  51  relative to the mounting bracket  31 . The seat-board supporting frame  32  includes a front and a rear portion  321 ,  322  that are pivotally connected to one another at two laterally spaced pivoting points  52 , and respectively support the front and the rear seat boards  21 ,  22  thereon. 
   Each of the two links  34  has a first end pivotally connected to a free end of one of the horizontal arms  33  to turn about a pivoting point  53 , and a second end pivotally connected to the rear portion  322  of the seat-board supporting frame  32  to turn about a pivoting point  54 , such that the pivoting points  51  for the front side of the seat-board supporting frame  32  and the fixed mounting bracket  31 , the pivoting points  52  for the front and the rear portion  321 ,  322  of the seat-board supporting frame  32 , and the pivoting points  53 ,  54  for the two ends of the links  34  together form four points of a parallelogram. 
   The telescopic lifter  40  includes a base  41  pivotally connected to the rear portion  322  of the seat-board supporting frame  32  at a predetermined point, and an extendable pipe  42  having an outer end pivotally connected to a rear bottom crossbar  11  of the chair  10  at a predetermined point. When the telescopic lifter  40  is actuated, it pushes the rear portion  322  of the seat-board supporting frame  32  upward and thereby elevates the seat  20  supported on the seat-board supporting frame  32  while moving the seat  20  forward, enabling a person sitting on the seat  20  to get up easily. 
   Please refer to  FIG. 3 . When the extendable pipe  42  of the telescopic lifter  40  is extended, the seat-board supporting frame  32  is elevated. Since the above-mentioned four pivoting points  51 ,  52 ,  53 , and  54  form four points of a parallelogram, the rear portion  322  of the frame  32  is always in parallel with the horizontal arms  33 , which are fixedly connected to the mounting bracket  31 . And, since the horizontal arms  33  are horizontally fixedly mounted on the chair  10 , the rear portion  322  of the seat-board supporting frame  32  is always in a horizontal position, allowing a user, particularly an old man to sit on the seat  20  stably. When the telescopic lifter  40  gradually pushes the seat  20  upward, the front portion  321  of the seat-board supporting frame  32  is turned about the pivoting points  51  at the front side of the seat-board supporting frame  32 , bringing the rear portion  322  to gradually move forward while being elevated, and enabling the old man to get up from the seat more easily. 
   In practical use of the chair  10 , a back cushion  12  is attached to a back of the chair  10 , and front and rear seat cushions  13 ,  14  are separately attached to the two seat boards  21 ,  22  of the seat  20 , so that the chair  10  is more comfortable for sitting. To help an old man to sit on the rear seat cushion  14 , first elevate the seat-board supporting frame  32  to a desired height, as shown in  FIG. 5 , so that the old man&#39;s hips are in contact with and slightly seated on the rear seat cushion  14 . Then, the telescopic lifter  40  is operated to retract the extendable pipe  42 , so that the seat-board supporting frame  32  and the rear seat cushion  14  are gradually lowered for the old man to sit down effortlessly. 
   The telescopic lifter  40  is a known mechanism, and the extendable pipe  42  is driven to move by an electric motor. When the extendable pipe  42  of the telescopic lifter  40  is caused to retract, a weight must be applied to the telescopic lifter  40  to lower the seat-board supporting frame  32 . This design makes the seat elevating mechanism of the present invention safer for use. This type of telescopic lifter  40  is referred to as a passively retractable telescopic lifter  40  and has been widely supplied in the market for many years. More specifically, when the extendable pipe  42  of the telescopic lifter  40  is gradually retracted, a distance by which the seat-board supporting frame  32  is elevated with the telescopic lifter  40  is gradually reduced at the same time. At this point, an overall weight of the user, the frame  32 , and the base  41  of the telescopic lifter  40  would cause the seat-board supporting frame  32  to move downward and finally reach a fully lowered horizontal position, as shown in  FIG. 4 . However, in practical design of the chair  10 , it is possible for the seat-board supporting frame  32  to lower under only the weight of the supporting frame  32  and the base  41  when the extendable pipe  42  is operated to retract. 
   It is preferable to have two laterally corresponded links  34 , so that the whole seat elevating mechanism of the present invention may be moved in a stable manner. A switch  15  is provided to a lower front of one armrest  16  of the chair  10  for conveniently controlling the operation of the telescopic lifter  40  by a user. 
   In brief, the seat elevating mechanism for a chair according to the present invention uses simple linkage for the seat to gradually elevate while maintaining in a horizontal position, so that an old man or a patient may be stably and effortlessly moved to an almost upright position. Moreover, the seat is moved forward while being elevated, allowing the old man or the patient to stand up more easily. Therefore, the present invention actually provides a power-controlled elevating chair very suitable for the aged.