Abstract:
A chair includes a base, a seat, a backrest pivotally connected to a rear end of a seat frame of the seat, and a transmission mechanism including a motor, a telescopic rod actuated by the motor to move in a retracting direction and an extending direction, and a transmission plate. A connecting rod is pivotally connected between a lower end of the backrest frame and the transmission plate. The telescopic rod is directed to a position below a central portion of the seat. The transmission plate is pivoted to the central portion of the seat, the second end of the connecting rod, and the telescopic rod at different portions thereof. When the telescopic rod is retracted, the top support portion of the transmission plate presses against the seat frame to make the rear end of the seat frame move upward and forward.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a chair. In particular, the present invention relates to a chair with aid in lying back and getting up.  
         [0003]     2. Description of the Related Art  
         [0004]      FIGS. 9 and 10  of the drawings illustrate a conventional chair with aid in lying back and getting up. In other words, the chair may assist the user in lying back into the chair or getting up from the chair. The chair comprises a base  10 ′, a seat  11 ′, a backrest  12 ′ pivotally connected to a rear end of the seat  11 ′, a transmission mechanism  13 ′, and a footrest  14 ′. The transmission mechanism  13 ′ comprises a motor  131 ′ pivotally mounted to a rear end of the base  10 ′ and a telescopic rod  132 ′ extending from the motor  13 ′ and having a front end pivotally connected to a front end of the seat  11 ′. The footrest  14 ′, the seat  11 ′, and the transmission mechanism  13 ′ are so connected that the backrest  12 ′ is inclined rearward and the footrest  14 ′ is extended when the telescopic rod  132 ′ is in a retracted position, assisting in lying down of the user ( FIG. 9 ) and that the footrest  14 ′ is folded and the backrest  12 ′ is moved forward when the telescopic rod  132 ′ is in an extended position, assisting in getting up of the user ( FIG. 10 ).  
         [0005]     The center of gravity of the user sitting in the chair is usually located in a longitudinal position adjacent to the rear end of the chair. However, the force applied by the telescopic rod  13 ′ acts on the front end of the chair  11 ′, resulting in unstable movement of the seat  11 ′. Further, the telescopic rod  132 ′ extending forward from the rear end of the base  10 ′ could not reach the location on which the center of gravity of the user sitting in the chair generally locates, failing to provide a reliable support for the seat  11 ′ when the seat  11 ′ is moving forward.  
         [0006]      FIGS. 11 and 12  illustrate another conventional chair with aid in getting up and lying down. The chair comprises a base  20 ′, a seat  21 ′, a backrest  22 ′ pivotally connected to the seat  21 ′, a transmission mechanism  23 ′, and a footrest  24 ′. The transmission mechanism  23 ′ comprises a motor  231 ′ and a telescopic rod  232 ′ extending rearward and having a top end fixed to the backrest  22 ′. The footrest  24 ′, the transmission mechanism  23 ′, and the seat  21 ′ are so connected that the backrest  22 ′ is inclined rearward and the footrest  24 ′ is extended when the telescopic rod  232 ′ is in a retracted position, assisting in lying down of the user ( FIG. 11 ) and that the footrest  24 ′ is folded and the backrest  22 ′ is moved forward when the telescopic rod  232 ′ is in an extended position, assisting in getting up of the user ( FIG. 12 ).  
         [0007]     The center of gravity of the user sitting in the chair is usually located in a longitudinal position adjacent to the rear end of the chair. However, the telescopic rod  232 ′ is connected to the backrest  22 ′ (i.e., at a rear of the seat  21 ′), not the location on which the center of gravity of the user sitting in the chair generally locates, failing to provide a reliable support for the seat  21 ′ when the seat  21 ′ is moving forward.  
       SUMMARY OF THE INVENTION  
       [0008]     An objective of the present invention is to provide a chair in which the seat is reliably supported and moves smoothly during forward movement of the seat for assisting in getting up of the user.  
         [0009]     Another objective of the present invention is to provide a chair with a footrest that can be extended or folded in response to movement of a transmission mechanism.  
         [0010]     A chair in accordance with the present invention comprises a base having a front end and a rear end, a seat including a seat frame that has a central portion and a rear end, a backrest having a lower end pivotally connected to the rear end of the seat frame, and a transmission mechanism.  
         [0011]     The transmission assembly includes a motor, a telescopic rod actuated by the motor to move in a retracting direction and an extending direction, and a transmission plate. The motor has an end pivotally connected to the front end of the base. The transmission plate is pivotally connected to the central portion of the seat frame. A connecting rod includes a first end pivotally connected to the lower end of the backrest frame and a second end pivotally connected to the transmission plate.  
         [0012]     The transmission plate includes a top support portion. The telescopic rod is directed to a position below a central portion of the seat. The transmission plate further includes a first pivotal portion on an upper portion of a front side thereof for pivotal connection with the central portion of the seat. The transmission plate further includes a second pivotal portion on a lower portion of the front side thereof for pivotal connection with the second end of the connecting rod. The transmission plate further includes a third pivotal portion on a lower portion of a rear side thereof for pivotal connection with the telescopic rod.  
         [0013]     When the telescopic rod is extended, the transmission plate rotates and the backrest is folded. When the telescopic rod is retracted, the top support portion of the transmission plate presses against the seat frame to make the rear end of the seat frame move upward and forward.  
         [0014]     In an embodiment of the invention, the base further comprises a supporting portion at a rear end thereof for supporting the rear end of the seat.  
         [0015]     Preferably, the base comprises a connecting plate mounted on each of two lateral sides of the front end of the base. A connecting plate is mounted to each of two sides of the rear end of the seat frame. The chair further comprises two connecting rods each having a first end pivotally connected to an associated one of the connecting plates and a second end pivotally connected to an associated one of the connecting plates.  
         [0016]     Preferably, the seat frame further includes a front end to which the footrest mechanism is pivotally connected. The footrest mechanism comprises a toggle mechanism, a footrest frame, and a connecting rod. The toggle mechanism includes two ends respectively and pivotally connected to the front end of the seat frame and the footrest frame. The connecting rod includes a first end pivotally connected to the toggle mechanism and a second end pivotally connected to the second pivotal portion of the transmission plate.  
         [0017]     In another embodiment of the invention, the chair further comprises two armrests respectively mounted on two sides of the seat frames.  
         [0018]     In a further embodiment of the invention, the seat comprises a front end pivotally connected to the front end of the base. The seat frame comprises a front frame and a rear frame that is pivotally connected to the front frame. When the telescopic rod is extended, the top abutting portion presses against the seat frame to make the rear end of the seat frame move upward and forward.  
         [0019]     Preferably, a second connecting rod has a first end pivotally connected to the front end of the seat and a second end pivotally connected to the rear frame of the seat frame. A third connecting rod has a first end pivotally connected to the backrest frame and a second end. The footrest mechanism comprises a toggle mechanism and a footrest frame. The toggle mechanism includes two ends respectively and pivotally connected to the front end of the seat and the footrest frame. The toggle mechanism is connected to the second end of the third connecting rod.  
         [0020]     Preferably, the chair includes an elastic element having a first end connected to the toggle mechanism and a second end connected to the seat.  
         [0021]     Preferably, the second end of the third connecting rod comprises an elongated slot, and the toggle mechanism is pivotally and slidably engaged in the elongated slot.  
         [0022]     Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]      FIG. 1  is a perspective view of an embodiment of a chair in accordance with the present invention.  
         [0024]      FIG. 2  is a side view of the chair in accordance with the present invention, wherein the backrest is inclined rearward and the footrest is in an extended position.  
         [0025]      FIG. 3  is a view similar to  FIG. 2 , wherein the backrest is in an upright position and the footrest is in a folded position.  
         [0026]      FIG. 4  is a side view similar to  FIG. 3 , wherein the backrest is moved forward.  
         [0027]      FIG. 5  is a side view similar to  FIG. 2 , wherein the chair includes armrests.  
         [0028]      FIG. 6  is a side view of another embodiment of the chair in accordance with the present invention, wherein the backrest is inclined rearward and the footrest is in an extended position.  
         [0029]      FIG. 7  is a side view similar to  FIG. 6 , wherein the backrest is in an upright position and the footrest is in a folded position.  
         [0030]      FIG. 8  is a side view similar to  FIG. 7 , wherein the chair is moved forward.  
         [0031]      FIG. 9  is a side view of a conventional chair.  
         [0032]      FIG. 10  is a view similar to  FIG. 9 , wherein the footrest is in a folded position and the backrest is moved forward.  
         [0033]      FIG. 11  is a side view of another conventional chair.  
         [0034]      FIG. 12  is a view similar to  FIG. 11 , wherein the footrest is in a folded position and the backrest is moved forward. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]     Referring to  FIGS. 1 and 2 , an embodiment of a chair in accordance with the present invention comprises a base  1 , a seat  2 , a backrest  3 , a transmission mechanism  4 , and a footrest mechanism  5 . The base  1  includes a pivotal portion  11  at a center of a front end thereof. The transmission mechanism  4  includes a motor  41  pivotally mounted to the pivotal portion  11 , which will be described later. The base  1  further includes a supporting portion  12  at a rear end thereof for supporting a rear end of the seat  2 .  
         [0036]     Two connecting plates  13  are respectively mounted on two lateral sides of the front end of the base  1 . Each connecting plate  13  includes a pivotal hole  13  for pivotal connection with an end of a connecting rod  14 . The other end of each connecting rod  14  is pivotally connected to the seat  2 .  
         [0037]     The seat  2  includes a seat frame  21  having a connecting portion  22  at a central portion thereof. A transmission plate  43  of the transmission mechanism  4  is pivotally connected to a pivotal section  221  of the connecting portion  22 . The rear end of the seat frame  21  includes a pivotal portion  23  for pivotal connection with the backrest  3 . A connecting plate  24  is mounted to each of two sides of the rear end of the seat frame  21  and includes a pivotal hole  241  for pivotal connection with the other end of the associated connecting rod  14 . Further, the seat frame  21  includes a pivotal portion  25  at a front end thereof for pivotal connection with the footrest mechanism  5 .  
         [0038]     The backrest  3  includes a backrest frame  31  that has a pivotal portion  32  at each of two sides of a lower end thereof for pivotal connection with the associated pivotal portion  23  at the rear end of the seat frame  21 . The backrest frame  31  further includes a horizontal bar  33  at a lower end thereof. The horizontal bar  33  includes a central pivotal portion  331  for pivotal connection with an end of a connecting rod  34 . The other end of the connecting rod  34  is pivotally connected to the transmission plate  43 .  
         [0039]     The transmission mechanism  4  includes the motor  41 , a telescopic rod  42 , and the transmission plate  43 . An end of the motor  41  is pivotally connected to the pivotal portion  11  of the base  1 . The motor  41  may be activated to extend or retract the telescopic rod  42 . A front end of the telescopic rod  42  is directed to a position below a rear, central portion of the seat  2  and pivotally connected to the transmission plate  43 . In this embodiment, the transmission plate  43  includes two sidewalls and mounted on the connecting portion  22  of the seat frame  21 . The transmission plate  43  includes a top support portion  431 . Further, the transmission plate  43  includes pivotal portions  432 ,  433 , and  434  at upper and lower portions of a front side thereof and an upper portion of a rear side thereof. The pivotal portion  432  is pivotally connected to the connecting portion  22  of the seat  2 . The pivotal portion  433  is pivotally connected to the other end of the connecting rod  34  and an end of a connecting rod  53  of the footrest mechanism  5 . The pivotal portion  434  is pivotally connected to the telescopic rod  42 .  
         [0040]     The footrest mechanism  5  includes a toggle mechanism  51 , a footrest frame  52 , and the connecting rod  53 . The toggle mechanism  51  includes two ends respectively and pivotally connected to the pivotal portion  25  of the seat frame  21  and the footrest frame  52 . The toggle mechanism  51  further includes a pivotal portion  511  for pivotal connection with the other end of the connecting rod  53 . The end of the connecting rod  53  is pivotally connected to the pivotal portion  433  of the transmission plate  43 , as mentioned above.  
         [0041]     When the motor  41  is activated to retract the telescopic rod  42 , the transmission plate  43  pivots about the pivotal portion  432  at the upper portion of the front side thereof. The rear side of the transmission plate  43  moves downward, and the lower portion of the front side of the transmission plate  43  moves forward to move the connecting rod  34  of the backrest frame  31  rearward and to move the backrest frame  31  rearward to an inclined state. Further, the connecting rod  53  of the footrest mechanism  5  moves forward to cause forward movement of the toggle mechanism  51  and the footrest frame  52  is moved to an extended position, as shown in  FIG. 2 .  
         [0042]     Referring to  FIG. 3 , when the motor  41  is activated to extend the telescopic rod  42 , the rear side of the transmission plate  43  moves upward, and the connecting rod  34  of the backrest frame  31  and the connecting rod  53  of the footrest mechanism  5  move rearward such that the backrest frame  31  moves to an upright position and the footrest  5  moves to a folded position.  
         [0043]     Referring to  FIG. 4 , when the user is intended to get up from the chair, the telescopic rod  42  is extended to make the top support portion  431  of the transmission plate  43  press against the connecting portion  22  of the seat frame  21 . Thus, the seat frame  21  extends in response to the extension of the telescopic rod  42 , resulting in upward movement of the rear side of the seat frame  21  and downward movement of the front side of the seat frame  21 , assisting in getting up of the user. During the upward movement of the seat frame  21 , the two sides of seat frame  21  are connected via the connecting plates  24  and the connecting rods  14  to the connecting plates  13  of the seat  1 , providing a stable support. Further, the force applied by the transmission mechanism  4  is directed to the location where the center of gravity of the user sitting in the chair generally locates, which further assures stable movement of the seat frame  21 .  
         [0044]     Referring to  FIG. 5 , two armrests  6  may be mounted on two sides of the seat frame  21  to provide improved sitting comfort.  
         [0045]      FIG. 6  illustrates another embodiment of the invention. In this embodiment, the chair comprises a base  71 , a seat  72 , a backrest  73 , a transmission mechanism  74 , and a footrest mechanism  75 . The base  71  includes a pivotal portion  711  at a center of a front end thereof. The transmission mechanism  74  includes a motor  741  pivotally mounted to the pivotal portion  711 , which will be described later. The base  71  further includes a supporting portion  712  at a rear end thereof for supporting the seat  72 .  
         [0046]     The base  71  further includes a pivotal portion  713  at a front end thereof for pivotal connection with a front end of the seat  72 . Also formed on the front end of the base  71  are a pivotal portion  714  for pivotal connection with the footrest mechanism  75  and a pivotal portion  715  for pivotal connection with an end of a connecting rod  716 . The other end of the connecting rod  716  is pivotally connected to the seat  72 . Armrests  717  are mounted on the base  71 .  
         [0047]     The seat  72  includes a seat frame  721  having a front frame  722  and a rear frame  723  that is pivotally connected to the front frame  722 . The rear frame  723  includes a connecting portion  724  at a central portion thereof. A transmission plate  743  of the transmission mechanism  74  is pivotally connected to a pivotal section  725  of the connecting portion  724 . A pivotal portion  726  is provided on a front end of the front frame  722  for pivotal connection with the base  71 . The rear frame  723  includes a pivotal portion  727  for pivotal connection with the backrest  73 . Further, the rear frame  723  includes another pivotal portion  728  for pivotal connection with the other end of the connecting rod  716  that has an end pivotally connected to the base  71 .  
         [0048]     The backrest  73  includes a backrest frame  731  that has a pivotal portion  732  at each of two sides of a lower end thereof for pivotal connection with the seat frame  721 . The backrest frame  731  further includes a horizontal bar  733  at a lower end thereof. The horizontal bar  733  includes a pivotal portion  734  for pivotal connection with an end of a connecting rod  736  and another pivotal connection with an end of another connecting rod  737 . The other end of the connecting rod  736  is pivotally connected to the transmission plate  743 . The other end of the connecting rod  737  includes an elongated slot  7371  for engaging with the footrest mechanism  75 .  
         [0049]     The transmission mechanism  74  includes the motor  741 , a telescopic rod  742 , and the transmission plate  743 . An end of the motor  741  is pivotally connected to the pivotal portion  711  of the base  71 . The motor  741  may be activated to extend or retract the telescopic rod  742 . A front end of the telescopic rod  742  is directed to a position below a rear, central portion of the seat  72  and pivotally connected to the transmission plate  743 . The transmission plate  743  includes a top support portion  7431 . Further, the transmission plate  743  includes pivotal portions  7432 ,  7433 , and  7434  at upper and lower portions of a front side thereof and an upper portion of a rear side thereof. The pivotal portion  7432  is pivotally connected to the seat  72 . The pivotal portion  7433  is pivotally connected to the other end of the connecting rod  736  of the backrest frame  731 . The pivotal portion  7434  is pivotally connected to the telescopic rod  742 .  
         [0050]     The footrest mechanism  75  includes a toggle mechanism  751  and a footrest frame  752 . The toggle mechanism  751  includes two ends respectively and pivotally connected to the pivotal portion  714  of the base  71  and the footrest frame  752 . The toggle mechanism  751  is pivotally and slidably engaged in the elongated slot  7371  of the connecting rod  737  of the backrest frame  73 . Further, the toggle mechanism  751  is connected to an end of an elastic element  753 . The other end of the elastic element  753  is connected to a horizontal rod (not labeled) of the base  71 .  
         [0051]     When the motor  741  is activated to retract the telescopic rod  742 , the transmission plate  743  pivots about the pivotal portion  7432  at the upper portion of the front side thereof. The rear side of the transmission plate  743  moves downward, and the lower portion of the front side of the transmission plate  743  moves forward to move the connecting rod  736  of the backrest frame  731  rearward and to move the backrest frame  731  rearward to an inclined state. Further, the connecting rod  737  below the backrest frame  731  moves forward to cause forward movement of the toggle mechanism  751  and the footrest frame  752  is moved to an extended position whereas the elastic element  753  is stretched, as shown in  FIG. 6 .  
         [0052]     Referring to  FIG. 7 , when the motor  741  is activated to extend the telescopic rod  742 , the rear side of the transmission plate  743  moves upward, the backrest frame  731  moves to an upright position, and the toggle mechanism  751  moves to a folded position. The elastic element  753  assists in folding operation of the toggle mechanism  751 .  
         [0053]     Referring to  FIG. 8 , when the user is intended to get up from the chair, the telescopic rod  742  is extended to make the top support portion  7431  of the transmission plate  743  press against the seat frame  721 . Thus, rear side of the seat frame  721  moves upward, and the front frame  722  and the rear frame  723  are in an angled position to assist in getting up of the user. During the upward movement of the seat frame  721 , the connecting rod  716  is connected to the base  71  to provide a stable support for the seat frame  121 . Further, the force applied by the transmission mechanism  74  is directed to the location where the center of gravity of the user sitting in the chair generally locates, which further assures stable movement of the seat frame  721 .  
         [0054]     Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the essence of the invention. The scope of the invention is limited by the accompanying claims.