Abstract:
A dental chair for supporting a patient during examination and the performance of procedures on the patient includes a patient support having a seat and a back, a base adapted to engage a floor surface, and a lift arm. The lift arm has a first end pivotally coupled to support structure at a first, terminal end of the base for rotation about a pivot axis defined by the support structure. A second end of the lift arm is coupled to the patient support.

Description:
TECHNICAL FIELD  
       [0001]    The present invention relates to apparatus for supporting persons during examination or the performance of a dental or medical procedure, and more particularly to a dental chair having an improved lift assembly. 
       BACKGROUND  
       [0002]    Conventional dental operatories generally include an articulating dental chair for supporting a patient in a variety of positions to facilitate the performance of dental procedures and operations. For example, dental chairs are generally adapted to be raised and lowered relative to a floor surface, and to be moved between a first orientation where a seat back is inclined relative to a seat base to support the patient in a seated position, and a second orientation where the seat back is reclined to support the patient in a generally supine position. 
         [0003]    The dental operatory may also include a dental delivery unit adapted to support various instruments and tools used during the performance of dental procedures. The delivery unit is typically provided with water and pressurized air for operating the instruments, and may include a tray for supporting instruments or other articles used by the practitioner. The delivery unit may be supported on a movable arm that facilitates positioning the unit and instruments adjacent the dental chair for convenient access by the practitioner during the performance of a procedure, then moved away to permit the patient to exit the dental chair when the procedure is complete. 
         [0004]    Conventional dental operatories may further include a cuspidor provided adjacent the dental chair to permit patients to expel the contents of their mouths during or at the conclusion of the dental procedure, an adjustably positionable lamphead to illuminate the treatment area, and various other devices useful for the performance of dental procedures. Such devices may be supported on cabinetry or other structure positioned adjacent the dental chair for convenient access by the patient or the dental practitioner. 
         [0005]    A dental chair should generally be movable from a lowered position with the seat back inclined, which facilitates entry and exit from the chair, and a raised position with the seat back reclined, which facilitates examination and the performance of procedures by a dental practitioner. Conventional dental chairs use a lift arm pivotally coupled to a base at a position intermediate the front and rear ends of the base to raise and lower the chair. This configuration generally results in a bulky base structure that has a rather large footprint, making it difficult for a dental practitioner to navigate around the chair during the performance of procedures. This configuration also limits the maximum length of the lift arm. In general, a longer lift arm is more desirable because it provides a greater vertical rise of the chair while minimizing for and aft movement of the chair during raising and lowering. 
         [0006]    Accordingly, there is a need for an improved dental chair which overcomes these and other drawbacks of prior art dental chairs. 
       SUMMARY  
       [0007]    The present invention overcomes the foregoing and other shortcomings and drawbacks of dental chairs heretofore known for supporting a patient during examination and the performance of procedures. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention. 
         [0008]    In one aspect, a dental chair for supporting a patient during examination and the performance of procedures on the patient includes a patient support having a seat and a back, a base adapted to engage a floor surface, and a lift arm. The lift arm has a first end pivotally coupled to support structure at a first, terminal end of the base for rotation about a pivot axis defined by the support structure. A second end of the lift arm is coupled to the patient support. 
         [0009]    In another aspect, an actuator is coupled between the base and the lift arm for moving the lift arm for rotation about the pivot axis to thereby raise and lower the patient support. The actuator is offset from a longitudinal centerline of the lift arm and in a direction toward one if the lateral sides of the lift arm. The actuator may be a hydraulic cylinder having a pump in fluid communication with the hydraulic cylinder. In another aspect, the pump is positioned behind the pivot axis and in a direction away from the first terminal end of the base. 
         [0010]    In another aspect, the examination and treatment chair further includes a load-bearing panel coupled to the lift arm and fastened at least at the first and second sides of the lift arm. The load-bearing panel helps to resist twisting of the lift arm resulting from uneven loading of the lift arm by the patient support and the offset actuator. 
         [0011]    These and other features, objects and advantages of the invention will become more readily apparent to those skilled in the art in view of the following detailed description, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES  
         [0012]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention in sufficient detail to enable one of ordinary skill in the art to which the invention pertains to make and use the invention. 
           [0013]      FIG. 1  is a perspective view of an exemplary dental chair in accordance with the principles of the present disclosure. 
           [0014]      FIG. 2A  is a side elevation view of the dental chair of  FIG. 1 , in a raised position. 
           [0015]      FIG. 2B  is a side elevation view of the dental chair of  FIG. 1 , in a lowered position. 
           [0016]      FIG. 3A  is a partial cross-sectional view of the dental chair of  FIG. 1 , in a raised position. 
           [0017]      FIG. 3B  is a partial cross-sectional view of the dental chair of  FIG. 1 , in a lowered position. 
           [0018]      FIG. 4  is a cross-sectional view of the dental chair of  FIG. 3B , taken along line  4 - 4 . 
           [0019]      FIG. 5  is a partial exploded view of the dental chair of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 1  depicts an exemplary dental chair  10  in accordance with the principles of the present disclosure. The dental chair  10  comprises a patient support  12  including a seat section  14  and a back section  16  that is movable relative to the seat section  14  from a generally inclined position that facilitates maintaining a patient in a seated position, and a generally reclined position that supports a patient in a supine position. The dental chair  10  further includes a base  18  and a lift assembly  20  coupled to the base  18  for moving the patient support  12  from a raised position, as depicted in  FIGS. 1 and 2A , to a lowered position, as depicted in  2 B. The dental chair  10  may further include a headrest  22  coupled to the back section  16  of the patient support  12  to facilitate supporting a patient&#39;s head while the patient is in the chair  10 . 
         [0021]    With continued reference to  FIG. 2A , and referring further to  FIGS. 3A ,  3 B,  4 , and  5 , the lift assembly  20  comprises a lift arm  30  having a first end  32  pivotally coupled to the base  18 , and a second end  34  pivotally coupled to a seat mount assembly  36 . The patient support  12  is operatively coupled to the seat mount assembly  36  for movement with the lift arm  30 . With particular reference to  FIG. 4 , the lift arm  30  of the embodiment shown comprises a frame having first and second side members  38 ,  40  extending longitudinally between the first and second ends  32 ,  34  of the lift arm  30 . The lift arm  30  may further include horizontal or diagonal cross members, or other structure, between the first and second side members  38 ,  40  to provide strength and rigidity to the frame. In the embodiment shown, the lift arm  30  is formed as a casting. It will be appreciated, however, that the lift arm  30  may alternatively be machined, welded, forged, or formed by various other methods or combinations of methods. 
         [0022]    At the first end  32  of the lift arm  30 , the first and second side members  38 ,  40  define respective first and second clevis arms  42 ,  44  for securing the first end  32  of the lift arm  30  to an axle  46  supported on the base  18 . First and second spaced apart flanges  48 ,  50  extend generally vertically upwardly from the first end  52  of the base  18  to form support structure for the axle  46 . The axle  46  supported by the first and second flanges  48 ,  50  defines a pivot axis  54  for the lift arm  30  about the first end  52  of the base  18 . Similarly, the first and second side members  38 ,  40  of the lift arm  30  define first and second clevis members  56 ,  58  at the second end  34  of the lift arm  30  for pivotally supporting the seat mount assembly  36 . In the embodiment shown, the first and second clevis members  56 ,  58  are coupled to trunnions  59  extending from opposite sides of the seat mount assembly  36 . As the lift arm  30  is pivoted about the axle  46  to raise and lower the patient support  12 , the seat mount assembly  36  may pivot about the second end  34  of the lift arm  30  to maintain the seat section  14  and the back section  16  in a desired orientation relative to horizontal. 
         [0023]    Because the pivot axis  54  of the lift arm  30  is located at the first end  52  of the base  18 , components of the dental chair  10  for raising and lowering the lift arm  30 , or otherwise controlling operation of the dental chair  10 , are located behind the pivot axis  54  instead of being positioned forward of the pivot axis  54  as is typical of conventional dental chairs. This configuration provides a compact construction that reduces the overall footprint of the base  18  while allowing for a generally longer lift arm  30  compared to conventional dental chairs. The longer lift arm  30  provides a greater vertical rise of the patient support  12  while minimizing fore and aft movement of the patient support  12  during raising and lowering. 
         [0024]    Referring to  FIGS. 3A ,  3 B, and  4 , the lift assembly  20  further includes an actuator  60  coupled between the base  18  and the lift arm  30  to facilitate moving the lift arm  30  about the pivot axis  54 , thereby raising and lowering the patient support  12 . In the embodiment shown, the actuator  60  comprises a hydraulic cylinder including a housing  62  and a piston rod  64  extendable from the housing  62 . The housing  62  is pivotally coupled to the base  18  and the distal end of the rod  64  is pivotally coupled to the lift arm  30  by respective pin connections  66 ,  68 , whereby the lift arm  30  is moved from a lowered position, depicted in  FIG. 3B , to a raised position, depicted in  FIG. 3A , as the piston rod  64  is actuated to extend from the housing  62 . To achieve a compact configuration of the dental chair  10 , the actuator  60  is positioned relative to the base  18  and the lift arm  30  at a location offset from a longitudinal centerline  70  of the lift arm  30  and in a direction toward the second side member  40  of the lift arm  30 , as depicted in  FIG. 4 . 
         [0025]    The dental chair  10  further includes a pump  72  operatively coupled to the actuator  60  by a hydraulic line  74  and appropriate fittings. The pump  72  is operable to provide pressurized fluid to the hydraulic cylinder so that the piston rod  64  is moved in and out of the housing  62  to raise and lower the lift arm  30 , as described above. As depicted in  FIGS. 4 and 5 , the pump  72  is positioned on the base  18  at a location between the first and second side members  38 ,  40  of the lift arm  30  and behind the axle  46 . 
         [0026]    While the actuator  60  of the lift assembly  20  has been shown and described herein as a hydraulic cylinder moved by pressurized fluid from a pump  72 , it will be appreciated that the actuator may alternatively comprise a pneumatic cylinder, an electric motor, or various other linear or rotary actuators suitable for moving the lift arm about the pivot axis. 
         [0027]    The lift assembly  20  further includes a generally elongate linkage member  80  coupled between the base  18  and the seat mount assembly  36  at the second end  34  of the lift arm  30 . In the embodiment shown, the first end  82  of the linkage member  80  is pinned to a boss  84  on the base  18  and positioned between the first and second flanges  48 ,  50 . A second end  86  of the linkage member  80  is pivotally coupled to the seat mount assembly  36  by a pin  88  spaced from the pivotal connection between the seat mount assembly  36  and the first and second clevis members  56 ,  58  at the second end  34  of the lift arm  30 . The lift arm  30  and linkage member  80  therefore define a linkage assembly, together with the seat mount assembly  36  and the base  18 , whereby the orientation of the seat mount assembly  36  is controlled as the lift arm  30  is moved from the lowered position, depicted in  FIG. 3B , to the raised positioned, depicted in  FIG. 3A . The linkage member  30  also facilitates supporting the load of the patient support  12  on the second end  36  of the lift arm  30 . The weight of the patient support  12 , including a patient supported on the patient support  12 , tends to unevenly load the second end  34  of the lift arm  30  as a result of the actuator  60  being offset from the longitudinal centerline  70  of the lift arm  30 . This uneven loading tends to deflect the first side member  38  of the lift arm  30  more than the second side member  40  of the lift arm  30 . 
         [0028]    To accommodate the uneven loading of the lift arm  30 , the lift assembly  20  further includes a load bearing panel  90 , or skin, secured to the lift arm  30 . In the embodiment shown, the panel  90  comprises  0 . 120 -inch thick steel sheet secured to the lift arm  30  by bolts  92  installed into threaded apertures  94  in the lift arm  30 . It will be recognized that panel  90  may alternatively be secured to lift arm  30  by other methods. As a non-limiting example, one or more bolts  92  may be replaced by dowel pins (not shown) extending from the lift arm  30  and adapted to engage corresponding apertures in the panel  90 . The connection of the panel  90  to the lift arm  30  provides a monocoque construction whereby the panel  90  is loaded to resist twisting of the lift arm  30  under the weight of the chair. 
         [0029]    The dental chair  10  may further include a control  100  mounted to the lift arm  30 . In the embodiment shown, the control  100  is positioned centrally between the first and second side members  38 ,  40 , although it will be appreciated that the control may alternatively be mounted at various other locations on the lift arm  30 , or at various locations on the dental chair  10 . The control  100  is operatively coupled to the pump  72  and the actuator  60  and is configured to control operation of the dental chair  10  as described herein. The lift assembly  20  may further include front and back cover panels  102 ,  104  over the lift arm  30 , and cover panels  106 ,  108  on the base  18  to conceal the components of the dental chair  10  and to provide an aesthetically pleasing appearance. 
         [0030]    While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features disclosed herein may be used alone or in any desired combination. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.