Bed having a reduced-shear pivot and step deck combination

Description Submit all comments and votes

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a bed, and particularly to a deck for supporting a mattress on a bed or other patient-supporting device in combination with a reduced-shear pivot assembly for connecting articulating portions of the deck to stationary portions of the deck. More particularly, the present invention relates to a deck and a pivot assembly for a hospital bed or a patient-care bed which is convertible to a chair and the usual reclining positions between the normal horizontal bed position and the chair position. The bed of the present invention is ideal for supporting patients who are likely candidates for skin problems, notably decribitis ulcers.

The deck or "step deck" as it is referred to herein has a central, longitudinally extending deck portion and raised or elevated longitudinally extending upper deck portions along the sides. The step deck is movable so that the bed is convertible between a conventional bed position having a horizontal sleeping surface and a sitting position having the head and back of the person supported in an upright position. The bed may be stopped. The mechanism for moving the deck to the sitting position includes a "reduced-shear" pivot that cooperates with the step deck to minimize the shear forces between the person and the sleeping surface when the bed moves between the bed position and the sitting position.

Beds and examination tables having articulating decks to adjust the position of the person on the support surfaces thereof are known in the art. See, for example, U.S. Pat. No. 5,077,843 to Foster L. Dale et al., U.S. Pat. No. 5,157,800 to Borders, U.S. Pat. No. 5,129,177 to Celestina et al., U.S. Pat. No. 4,862,529 to Peck, and U.S. Pat. No. 4,751,754 to Baily et al., all of which are assigned to the assignee of the present invention, and U.S. Pat. No. 3,281,141 to Smiley et al., U.S. Pat. No. 5,279,010 to Ferrand et al., U.S. Pat. No. 4,183,109 to Howell, U. S. Pat. No. 4,411,035 to Fenwick, and U.S. Pat. No. 3,220,022 to Nelson, as well as German publication No. 716981. Each of these references discloses a bed r an examination table having a top surface that articulates to adjust the position of the person on the surface. See also U.S. patent application Ser. No. 08/511,711, filed Aug. 4, 1995 and titled Chair Bed, the specification of which is herein incorporated by reference.

According to the present invention, a chair bed for a person is provided, the chair bed having a head, a foot, and sides, and including a unique combination of a step deck with a reduced-shear pivot feature. The bed includes a frame and a deck carried by the frame. The deck includes an upper deck portion and a central, longitudinal recess in the upper deck portion, the recess being defined by a lower deck portion and walls connecting the upper and lower deck portions. In addition, the bed includes a mattress having a planar, upwardly-facing support surface, side portions resting on the side deck portions, and a central projection extending downwardly into the recess. The bed also includes a first longitudinal deck section coupled to the deck to pivot about a pivot axis above the lower deck portion between a generally horizontal position and a tilted position.

In preferred embodiments, the chair bed includes a base frame, an intermediate frame coupled to the base frame, a weigh frame coupled to the intermediate frame, and an articulating deck coupled to the weigh frame. The articulating deck has longitudinally spaced head, seat, thigh, and foot sections. The head, thigh, and foot sections are movable relative to each other and are movable relative to the seat section which is fixed relative to the weigh frame. The head, thigh, and foot sections are infinitely adjustable to allow the chair bed to attain any desired position within the range of movement of the head, thigh, and foot sections, thus accommodating changes of position of a person on the chair bed. The illustrative articulating deck can provide a planar, horizontal sleeping surface, a planar sleeping surface that is tilted toward either the head end of the chair bed or the foot end of the chair bed, and a non-planar chair-shaped seating surface, in addition to the intermediate positions therebetween.

The chair bed can include a mechanism for raising and lowering the articulating deck and the sleeping surface between a low position and a raised position relative to the base of the chair bed. In addition, the chair bed can also include mechanisms for independently raising and lowering each of the head section, the thigh section, and the foot section so that the chair bed can assume many positions to suit the specific needs of individual people.

A companion mattress is carried by the deck. The mattress has a planar, upwardly-facing sleeping surface, side portions resting on the side deck portions, and a projection beneath the sleeping surface. The projection extends downwardly into the recess and can engage at least a portion of the side wall of the deck. The varied thickness of the mattress provides the mattress with "zones" including a thick zone adjacent to the projection and a thin zone in areas away from the projection. The mattress includes a head mattress portion, a seat mattress portion, a thigh mattress portion, and a foot mattress portion. Each named mattress portion is associated respectively with the head, seat, thighs, and feet of the person resting on the sleeping surface of the bed as well as with the underlying head, seat, thigh, and foot sections of the deck.

Though there are many potential variations of step deck shapes and corresponding mattress shapes and numbers and types of mattress pieces that could be devised, any step deck having an upper deck portion and a recess defined by a bottom deck portion and walls connecting the bottom and the upper deck portions would achieve the desired results. Likewise, any mattress or combination of mattress pieces that provide a bottom surface generally conforming to the shape of the step deck would achieve the desired results.

The movable head section is coupled to the weigh frame and is configured to pivot relative to the weigh frame about an effective pivot axis positioned to lie above the sleeping surface. Preferably, the effective pivot axis is located generally adjacent to a pivot axis defined by the hip of a person lying on the sleeping surface in order to minimize the shear between the sleeping surface and the back of the person in the bed as the head section moves between the down position and the back-support position. To achieve this "reduced-shear" pivot, the head section is mounted to the weigh frame for both translational movement and pivoting movement relative to the weigh frame. The pivoting and translational movements combine to produce a motion in which the head portion pivots relative to the frame about the effective pivot axis.

The head section of the articulating deck can pivot relative to the weigh frame between a down position generally parallel to the weigh frame and an upward back-support position. When a person on a sleeping surface moves from a flat position to a sitting position, the back and legs of the person engaging the sleeping surface lengthen. The reduced-shear pivot accommodates this lengthening to reduce the shear between the back and legs of the person and the sleeping surface as the head section pivots between the down position and the back-support position by expanding the deck and the sleeping surface. The reduced-shear pivot allows the upper body of the person on the sleeping surface to be tilted upwardly without moving the lower body of the person. This reduces the tendency of the person to slide relative to the sleeping surface during articulation of the head section, thereby reducing the shear between the back and legs of the person and the sleeping surface.

The head section is coupled to the walls adjacent to the seat section and above the lower deck so that the head section is movable from a generally horizontal down position to a back-support position providing a pivotable backrest. Preferably, the head section simultaneously translates toward the head end of the bed and pivots upwardly when moving from the down position to the back-support position. The translation and the pivoting motions combine to produce a motion wherein the head section pivots relative to the seat section about an effective pivot axis positioned to lie above the lower deck.

The vertical distance between the sleeping surface and the reduced-shear pivot assembly can be minimized when the chair bed includes a step deck having upper deck side portions and a corresponding thin mattress portion. Mounting the reduced-shear pivot assembly to the walls connecting the lower deck and the upper deck portion minimizes the extent that the reduced-shear pivot assembly is required to raise the effective pivot axis above the reduced-shear pivot assembly as compared to a reduced-shear pivot assembly mounted to the bottom of a deck.

The step deck can also include an upper deck end portion adjacent to the foot end of the bed. The foot section can be coupled to the upper deck end portion for pivoting movement about a pivot axis that is positioned to lie above the lower deck. The foot section can also be configured to contract and expand to vary the length of the foot section as the foot section pivots about the pivot axis so that the foot section can pivot downwardly when the chair bed is in the low position to place the feet of the person supported on the sleeping surface on the floor. In addition, the foot portion of the mattress can be configured to shorten in conjunction with the contraction of the foot section. Also, the foot portion of the mattress can automatically become thinner to maintain an appropriately sized seat area as the foot section pivots downwardly.

It is an object of the present invention to provide a bed having unique head and foot section reduced-shear pivots. The bed has a head end, a foot end, and sides. The bed comprises a frame and an articulated deck supported by the frame. The deck has a head section, a seat section, and a foot section. A mattress having a support surface is supported on the deck. At least one of the deck sections is coupled to the deck for movement between a generally horizontal position and a tilted position about a first effective pivot axis above the support surface.

A conventional bed having a head portion that pivots upwardly may pivot about a pivot axis adjacent to the bottom surface of the deck carrying the mattress of the conventional bed. However, the hip of the person carried by the top surface will be several inches above the pivot axis of the conventional bed. As a result, shear forces between the person carried on the top surface and the top surface of the conventional bed when the head portion of the conventional bed pivots upwardly causing the top surface of the conventional bed to scrub against the person. This scrubbing action will often be detrimental to the skin of patients, particularly older patients with a potential for serious decribitis ulcers.

In contrast, the chair bed in accordance with the present invention is provided with a reduced-shear pivot, including shear-reducing means connected to the frame for mounting the head portion to the frame for both translational movement and pivoting movement relative to the frame. The pivoting and translational movements of the shear-reducing means combine to produce a motion of the head section in which the head section pivots relative to the frame about an effective pivot axis positioned to lie above the sleeping surface. Preferably, the effective pivot axis is generally coincident with the pivot axis of the hip of the person carried by the sleeping surface so that the shear forces between the person and the sleeping surface are minimized, thereby minimizing the scrubbing of the sleeping surface against the person.

Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figures in which:

FIG. 1 is a perspective view of a chair bed in accordance with the present invention showing a side rail exploded away from the chair bed, head side rails and foot side rails positioned along longitudinal sides of the deck, and a swinging foot gate in a closed position;

FIG. 2 is a view similar to FIG. 1 showing the chair bed in the sitting position having a head section of an articulating deck moved upwardly to a back-support position, a thigh section of the deck inclined slightly upwardly, a foot section of the deck moved to a generally vertical downwardly extending down position, a foot portion of the mattress being deflated, and swinging gates moved to an open position with one swinging gate folded next to the chair bed;

FIG. 3 is a diagrammatic view of the chair bed of FIG. 1 showing the chair bed in a bed position including a mattress having an upwardly-facing sleeping surface held a predetermined first distance above the floor, the deck being in an initial position supporting the sleeping surface in a generally planar configuration, and the foot section being a first length;

FIG. 4 is a diagrammatic view showing the chair bed in a low position;

FIG. 5 is a diagrammatic view showing the chair bed in a Trendelenburg position;

FIG. 6 is a diagrammatic view showing the chair bed in a reverse Trendelenburg position;

FIG. 7 is a diagrammatic view showing the chair bed in an intermediate position having a head end of a head section of the deck pivoted slightly upward from the initial position of the deck, a seat section positioned to lie in the horizontal plane defined by the seat section in the initial position of the deck, and the foot section being inclined slightly so that the foot end of the foot section lies below the position of the foot section when the deck is in the initial position of the deck;

FIG. 8 is a diagrammatic view showing the chair bed in a sitting or chair position with the head end of the head section pivoted upwardly away from the seat section to a back-support position, the seat section lying generally horizontal as in the initial deck position, the thigh section being raised upwardly, the foot section extending downwardly from the thigh section and being a second shorter length, and the portion of the mattress over the foot section being deflated;

FIG. 9 is a perspective view of a first embodiment of a step deck and a mattress in accordance with the present invention;

FIG. 10 is a sectional view taken along line 10--10 of FIG. 9 showing the bottom of the step deck beneath the projection;

FIG. 11 is an exploded perspective view of the chair bed of, FIG. 1 with portions broken away;

FIG. 12 is a sectional view taken through the chair bed of FIG. 1 having the chair bed in the intermediate position similar to the position shown in FIG. 7;

FIG. 13 is a view similar to FIG. 12 showing portions of the head section of the articulating deck and the reduced-shear pivot assembly in the down position shown in FIG. 3;

FIG. 14 is a view similar to FIG. 13 showing portions of the head section and the reduced-shear pivot assembly in the back-support position shown in FIG. 8;

FIG. 15 is an exploded perspective view of a second embodiment of a step deck and the mattress of the chair bed;

FIG. 16 is a sectional view taken through the step deck and the mattress of FIG. 15 and showing a C-arm 58 (in phantom) for holding medical equipment such as fluoroscopic equipment; and

FIG. 17 is an exploded perspective view of a third embodiment of the mattress and the deck showing the foot section of the deck and the foot portion of the mattress in a minimized condition having the foot section of the deck contracted and the foot portion of the mattress contracted longitudinally and deflated so that the foot portion of the mattress is thinner and shorter than when foot portion is inflated.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE AND PREFERRED EMBODIMENTS

A chair bed 50 in accordance with the present invention having a head end 52, a foot end 54, and sides 56, 58 is illustrated in FIG. 1. As used in this description, the phrase "head end 52" will be used to denote the end of any referred-to object that is positioned to lie nearest head end 52 of chair bed 50. Likewise, the phrase "foot end 54" will be used to denote the end of any referred-to object that is positioned to lie nearest foot end 54 of chair bed 50.

Chair bed 50 includes a base module 60 having a base frame 62 connected to an intermediate frame module 300 by lift arms 320, 322, 324, 326 as shown in FIGS. 1 and 11. An articulating deck/weigh frame module 400 is coupled to intermediate frame module 300 by load beams. Side rail assemblies 800, 802, 804, 806 and an extended frame module 610 having a swinging foot gate 622 are coupled to articulating deck/weigh frame module 400. A mattress 550 is carried by articulating deck/weigh frame module 400 and provides a sleeping surface or support surface 552 configured to receive a person (not shown).

Chair bed 50 can be manipulated by a caregiver or by a person (not shown) on sleeping surface 552 using hydraulic system module 100 so that mattress 550, an intermediate frame 302 of intermediate frame module 300, and an articulating deck 402 of articulating deck/weigh frame module 400 assume a variety of positions, several of which are shown diagrammatically in FIGS. 3-7.

Articulating deck 402 includes a head section 404, a seat section 406, a thigh section 408, and a foot section 410. Mattress 550 rests on deck 402 and includes a head portion 558, a seat portion 560, a thigh portion 562, and a foot portion 564, each of which generally corresponds to the like-named portions of deck 402, and each of which is generally associated with the head, seat, thighs, and feet of the person on sleeping surface 552. Details of deck 402 and mattress 550 will be explained hereinafter.

Chair bed 50 can assume a bed position having deck 402 configured so that sleeping surface 552 is planar and horizontal, defining an initial position of deck 402 as shown in FIG. 1 and as shown diagrammatically in FIG. 3. In the bed position, sleeping surface 552 is a predetermined first distance 566 above the floor. Chair bed 50 can also be manipulated to assume a low position shown diagrammatically in FIG. 4 having deck 402 in the initial position and having sleeping surface 552 a predetermined second distance 568 above the floor, the second distance 568 being smaller than first distance 566. The foot section 410 of the articulating deck 402 has a first length 465 when the deck 402 is in the initial position.

Chair bed 50 can be moved to a Trendelenburg position shown diagrammatically in FIG. 5 having deck 402 in a planar configuration and tilted so that head end 52 of sleeping surface 552 is positioned to lie closer to the floor than foot end 54 of sleeping surface 552. Chair bed 50 can also achieve a reverse Trendelenburg position shown diagrammatically in FIG. 6 having deck 402 in a planar configuration and tilted so that foot end 54 of sleeping surface 552 is positioned to lie closer to the floor than head end 52 of sleeping surface 552.

As described above, chair bed 50 is convertible to a sitting position shown in FIG. 2 and shown diagrammatically i