PERSON SUPPORT APPARATUS WITH SHEAR-REDUCING PIVOT ASSEMBLY

Abstract

A person support apparatus includes a support surface for supporting a person thereon. The support surface includes at least a seat and a backrest coupled together by a pivot assembly. In some embodiments, the pivot assembly includes a backrest slide bar mounted to the backrest and a seat slide bar mounted to the seat. The backrest and seat slide along their respective slide bars when the backrest pivots. A seat link is coupled to the seat and backrest slide bar, and a backrest link is coupled to the backrest and seat slide bar. The slide bars are coupled at their ends to each other. The pivot assembly creates a virtual pivot axis that, as the backrest pivots from an upright position to a reclined position, moves backward and upwardly. Elongate openings may be defined in the slide bars to support the slide bars on the seat and backrest, respectively.

Claims

1. A person support apparatus comprising: a frame; a seat supported on the frame; a backrest pivotally coupled to the seat such that the backrest is able to pivot with respect to the seat; a backrest slide bar mounted to the backrest and adapted to slide along the backrest; a seat slide bar mounted to the seat and adapted to slide along the seat; a backrest link pivotally coupled to the backrest and the seat slide bar; and a seat link pivotally coupled to the seat and the backrest slide bar.

2. The person support apparatus of claim 1 wherein the backrest defines a backrest plane and the seat defines a seat plane, and wherein the backrest slide bar slides along the backrest parallel to the backrest plane and the seat slide bar slides along the seat parallel to the seat plane.

3. The person support apparatus of claim 2 further comprising: a first support fixedly coupled to the backrest; a second support fixedly coupled to the backrest; and a first elongate opening defined in the backrest slide bar, the first and second supports being positioned in the first elongate opening and adapted to support the backrest slide bar as the backrest slide bar slides along the backrest.

4. The person support apparatus of claim 3 further comprising: a third support fixedly coupled to the seat; a fourth support fixedly coupled to the seat; and a second elongate opening defined in the seat slide bar, the third and fourth supports being positioned in the second elongate opening of the seat slide bar and adapted to support the seat slide bar as the seat slide bar slides along the seat.

5. The person support apparatus of claim 2 further comprising a pivot joint coupling a first end of the backrest slide bar to a second end of the seat slide bar, the pivot joint enabling the backrest slide bar to pivot with respect to the seat slide bar.

6. The person support apparatus of claim 2 wherein the backrest is adapted to pivot with respect to the seat about a virtual pivot axis that moves as the backrest pivots with respect to the seat, and wherein the virtual pivot axis moves toward a foot end the person support apparatus as the backrest pivots toward an upright position, and the virtual pivot axis moves toward a head end of the person support apparatus as the backrest pivots toward a downward position.

7. The person support apparatus of claim 2 wherein the backrest is adapted to pivot with respect to the seat about a virtual pivot axis that moves as the backrest pivots with respect to the seat and wherein the backrest is adapted to pivot to a flat position in which the backrest plane is substantially parallel to the seat plane.

8. The person support apparatus of claim 2 further comprising: a second backrest slide bar mounted to the backrest and adapted to slide along the backrest parallel to the backrest plane; a second seat slide bar mounted to the seat and adapted to slide along the seat parallel to the seat plane; a second backrest link pivotally coupled to the backrest and the second seat slide bar; a second seat link pivotally coupled to the seat and the second backrest slide bar; a cross-bar coupled between at least one of the following: (1) the first and second backrest slide bars, and (2) the first and second seat slide bars; and an electric actuator having a first end coupled to the cross-bar and a second end coupled to at least one of the seat and the backrest.

9. The person support apparatus of claim 3 wherein the first elongate opening is a straight opening.

10. A person support apparatus comprising: a frame; a seat supported on the frame; a backrest pivotally coupled to the seat such that the backrest is able to pivot with respect to the seat; a first backrest slide bar mounted to a first side of the backrest and adapted to slide along the backrest; a second backrest slide bar mounted to a second side of the backrest and adapted to slide along the backrest; a first seat slide bar mounted to a first side of the seat and adapted to slide along the seat; a second seat slide bar mounted to a second side of the seat and adapted to slide along the seat; a first pivot joint coupling the first backrest slide bar to the first seat slide bar; a second pivot joint coupling the second backrest slide bar to the second seat slide bar; and an actuator adapted to exert a force against the first and second pivot joints such that the backrest pivots with respect to the seat.

11. The person support apparatus of claim 10 further comprising: a first backrest link pivotally coupled to the backrest and the first seat slide bar; a second backrest link pivotally coupled to the backrest and the second seat slide bar; a first seat link pivotally coupled to the seat and the first backrest slide bar; and a second seat link pivotally coupled to the seat and the second backrest slide bar.

12. The person support apparatus of claim 11 further comprising: a first support fixedly coupled to the first side of the backrest; a second support fixedly coupled to the first side of the backrest; a third support fixedly coupled to the second side of the backrest; a fourth support fixedly coupled to the second side of the backrest; a first elongate opening defined in the first backrest slide bar, the first and second supports being positioned in the first elongate opening and adapted to support the first backrest slide bar as the first backrest slide bar slides along the backrest; and a second elongate opening defined in the second backrest slide bar, the third and fourth supports being positioned in the second elongate opening and adapted to support the second backrest slide bar as the second backrest slide bar slides along the backrest.

13. The person support apparatus of claim 12 further comprising: a fifth support fixedly coupled to the first side of the seat; a sixth support fixedly coupled to the first side of the seat; a seventh support fixedly coupled to the second side of the seat; an eighth support fixedly coupled to the second side of the seat; a third elongate opening defined in the first seat slide bar, the fifth and sixth supports being positioned in the third elongate opening of the first seat slide bar and adapted to support the first seat slide bar as the first seat slide bar slides along the seat; and a fourth elongate opening defined in the second seat slide bar, the seventh and eighth supports being positioned in the fourth elongate opening of the second seat slide bar and adapted to support the second seat slide bar as the second seat slide bar slides along the seat.

14. The person support apparatus of claim 10 wherein the backrest is adapted to pivot with respect to the seat about a virtual pivot axis that moves as the backrest pivots with respect to the seat, and wherein the virtual pivot axis moves toward a foot end of the person support apparatus as the backrest pivots toward an upright position, and the virtual pivot axis moves toward a head end of the person support apparatus as the backrest pivots toward a downward position.

15. The person support apparatus of claim 11 further comprising a cross-bar extending between the first and second pivot joints, the actuator including a first end coupled to the cross-bar and a second end coupled to one of the seat and backrest.

16. The person support apparatus of claim 11 wherein the seat defines a seat plane, the backrest defines a backrest plane, the first and second seat slide bars move parallel to the seat plane when the backrest pivots with respect to the seat, and the first and second backrest slide bars move parallel to the backrest plane when the backrest pivots.

17. A person support apparatus comprising: a frame; a seat supported on the frame; a backrest pivotally coupled to the seat; a backrest slide bar slidingly mounted to the backrest and including a first straight opening defined therein; a seat slide bar slidingly mounted to the seat and including a second straight opening defined therein; and wherein the backrest slide bar and seat slide bar are adapted to cause the backrest to pivot with respect to the seat about a virtual pivot axis that moves along a curved path as the backrest pivots.

18. The person support apparatus of claim 17 further comprising: a pivot joint coupling a first end of the backrest slide bar to a second end of the seat slide bar, the pivot joint enabling the backrest slide bar to pivot with respect to the seat slide bar; wherein the backrest defines a backrest plane and the seat defines a seat plane; and wherein the backrest slide bar slides along the backrest parallel to the backrest plane and the seat slide bar slides along the seat parallel to the seat plane.

19. The person support apparatus of claim 18 further comprising: a first support fixedly coupled to the backrest and positioned in the first straight opening; a second support fixedly coupled to the backrest and positioned in the first straight opening, wherein the first and second supports are adapted to support the backrest slide bar as the backrest slide bar slides along the backrest; a third support fixedly coupled to the seat and positioned in the second straight opening; and a fourth support fixedly coupled to the seat and positioned in the second straight opening, wherein the third and fourth supports are adapted to support the seat slide bar as the seat slide bar slides along the seat.

20. The person support apparatus of claim 17 wherein the virtual pivot axis moves along the curved path toward a foot end the person support apparatus as the backrest pivots toward an upright position, and the virtual pivot axis moves along the curved path toward a head end of the person support apparatus as the backrest pivots toward a downward position; and wherein the backrest is adapted to pivot to a flat position in which the backrest plane is substantially parallel to the seat plane.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a perspective view of a person support apparatus according to a first embodiment of the present disclosure;

[0023] FIG. 2 is a side elevation view of a person support apparatus according to a second embodiment of the present disclosure;

[0024] FIG. 3 is a side elevation view of the person support apparatus of FIG. 2 shown with a backrest reclined and a leg rest extended;

[0025] FIG. 4 is a perspective view of a pair of pivot assemblies of the person support apparatuses of FIGS. 1 and 2 showing a seat and backrest in a flat orientation;

[0026] FIG. 5 is a perspective view of the pivot assemblies of FIG. 4 showing the backrest in a first reclined position relative to the seat;

[0027] FIG. 6 is a perspective view of the pivot assemblies of FIG. 4 showing the backrest in a second reclined position relative to the seat;

[0028] FIG. 7 is a perspective view of the pivot assemblies of FIG. 4 showing the backrest in an upright position relative to the seat;

[0029] FIG. 8 is a diagram of the seat and backrest showing the backrest and seat in a flat orientation; and

[0030] FIG. 9 is a diagram showing the backrest in a raised position relative to the seat.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] A first illustrative person support apparatus 20 according to a first embodiment of the present disclosure is shown in FIG. 1, and a second illustrative person support apparatus 20 according to a second embodiment of the present disclosure is shown in FIGS. 2-3. Although the particular form of person support apparatuses 20 and 20 are illustrated as a bed in FIG. 1 and as a recliner in FIGS. 2-3, it will be understood that person support apparatuses 20 and 20 could, in different embodiments, be cots, stretchers, wheelchairs, operating tables, dental chairs, or any other structure having a support surface with at least one portion (e.g. a backrest) that is pivotal with respect to another portion of the support surface (e.g. a seat portion).

[0032] Person support apparatus 20 of FIG. 1 includes a base 22 having a plurality of wheels 24, a pair of lifts 26 supported on the base 22, a litter frame 28 supported on the lifts 26, and a support deck 30 supported on the litter frame 28. Person support apparatus 20 further includes a footboard 32 (which may be removable) and a plurality of siderails 34. Siderails 34 are all shown in a raised position in FIG. 1 but are each individually movable to a lower position in which ingress into, and egress out of, person support apparatus 20 is not obstructed by the lowered siderails 34.

[0033] Lifts 26 are adapted to raise and lower litter frame 28 with respect to base 22. Lifts 26 may be hydraulic actuators, pneumatic actuators, electric actuators, or any other suitable device for raising and lowering litter frame 28 with respect to base 22. In the illustrated embodiment, lifts 26 are operable independently so that the tilting of litter frame 28 with respect to base 22 can also be adjusted. That is, litter frame 28 includes a head end 36 and a foot end 38, each of whose height can be independently adjusted by the nearest lift 26. Person support apparatus 20 is designed so that when a person lies thereon, his or her head will be positioned adjacent head end 36 and his or her feet will be positioned adjacent foot end 38.

[0034] Litter frame 28 provides a structure for supporting support deck 30, footboard 32, and siderails 34. Support deck 30 is made of a plurality of sections, some of which are pivotal about generally horizontal pivot axes. In the embodiment shown in FIG. 1, support deck 30 includes a backrest 42, a seat 44, a thigh section 46, and a foot section 48. Backrest 42, which is also sometimes referred to as a Fowler section, is pivotal about a generally horizontal pivot axis between a generally horizontal position (not shown in FIG. 1) and a plurality of raised positions (one of which is shown in FIG. 1). As will be discussed in greater detail below, the pivoting of backrest 42 with respect to seat 44 is accomplished by way of a pair of pivot assemblies 40 (FIGS. 4-7) that cause backrest 42 to pivot in a motion having a moving virtual pivot axis. Thigh section 46 and foot section 48 may also be pivotal about one or more similar pivot assemblies.

[0035] Support deck 30 provides a support surface for a mattress (not shown), such as, but not limited to, an air, fluid, or gel mattress. Alternatively, another type of soft cushion may be supported on support deck 30 so that a person may comfortably lie and/or sit thereon. In some embodiments, the mattress or soft cushion is a segmented cushion or mattress that includes individual sections that correspond to the individual sections of support deck 30, such as backrest 42 and seat 44.

[0036] Person support apparatus 20 further includes a plurality of user interfaces 50 that enable a user of person support apparatus 20, such as a patient and/or an associated caregiver, to control one or more aspects of person support apparatus 20. In the embodiment shown in FIG. 1, person support apparatus 20 includes a footboard user interface 50a, a pair of outer siderail user interfaces 50b (only one of which is visible), and a pair of inner siderail user interfaces 50c (only one of which is visible). Footboard user interface 50a and outer siderail user interfaces 50b are intended to be used by caregivers, or other authorized personnel, while inner siderail user interfaces 50c are intended to be used by the patient associated with person support apparatus 20. Each of the user interfaces 50 includes a plurality of controls 51, although each user interface 50 does not necessarily include the same controls 51 and/or functionality.

[0037] Among other functions, the controls 51 of user interfaces 50 allow a user to control one or more of the following: change a height of support deck 30, pivot backrest 42 between a lowered position and one or more raised positions, activate and deactivate a brake for wheels 24, arm and disarm an exit detection system, and other functions. As will be discussed in greater detail below, when using user interface 50 to control the pivoting of backrest 42 with respect to seat 44, a controller on board person support apparatus 20 activates a powered actuator that drives the backrest upwardly or downwardly, as selected by the user.

[0038] Footboard user interface 50a is implemented in the embodiment shown in FIG. 1 as a control panel having a lid (flipped down in FIG. 1) underneath which is positioned a plurality of controls. As with all of the controls 51 of the various user interfaces 50, the controls of user interface 50a may be implemented as buttons, dials, switches, or other devices. Any of user interfaces 50a-c may also include a display for displaying information regarding person support apparatus 20. The display is a touchscreen in some embodiments.

[0039] Except for the pair of pivot assemblies 40 between backrest 42 and seat 44 (FIGS. 4-7), person support apparatus 20 may be mechanically constructed in a variety of different way and implement a wide variety of additional functionality beyond that explicitly described herein. Some suitable examples of such mechanical constructions and/or additional functionality are found in the following references, all of which are incorporated herein by reference in their entirety: the Stryker Maintenance Manual for the MedSurg Bed, Model 3002 S3, published in 2010 by Stryker Corporation of Kalamazoo, Mich., U.S. Pat. No. 8,689,376 issued Apr. 8, 2014 by inventors David Becker et al. and entitled PATIENT HANDLING DEVICE INCLUDING LOCAL STATUS INDICATION, ONE-TOUCH FOWLER ANGLE DJUSTMENT, AND POWER-ON ALARM CONFIGURATION; U.S. patent application Ser. No. 13/775,285 filed Feb. 25, 2013 by inventors Guy Lemire et al. and entitled HOSPITAL BED; and U.S. patent application Ser. No. 14/212,009 filed Mar. 14, 2014 by inventors Christopher Hough et al., and entitled MEDICAL SUPPORT APPARATUS. The mechanical construction of those components outside of pivot assemblies 40 of person support apparatus 20 may also take on forms different from what is disclosed in the aforementioned references, and person support apparatus 20 may include still other functionality.

[0040] As noted, FIGS. 2-3 show a second embodiment of a person support apparatus 20 implemented as a recliner. Person support apparatus 20 includes a backrest 42, a seat 44, a leg rest 52, a base 22, a pair of armrests 56, a user interface 50, and a plurality of wheels 24 that can be selectively braked and unbraked to allow person support apparatus 20 to be wheeled to different locations. Person support apparatus 20 is constructed such that the height and tilt of seat 44 are adjustable. Further, person support apparatus 20 is constructed such that backrest 42 is pivotal between a generally upright position (which may or may not be completely vertical), such as shown in FIG. 2, and a plurality of rearwardly reclined positions, one of which is shown in FIG. 3 (and which may or may not include a completely horizontal positions).

[0041] Leg rest 52 is constructed such that it is able to be moved between a retracted position (FIG. 2) and an extended position (FIG. 3) in which leg rest 52 is oriented generally horizontally to support the person's legs. In one embodiment, leg rest 52 is constructed in any of the manners shown in commonly assigned U.S. patent application Ser. No. 14/212,417 filed Mar. 14, 2014, by inventors Christopher Hough et al. and entitled MEDICAL SUPPORT APPARATUS, the complete disclosure of which is incorporated herein by reference. Other constructions of leg rest 52 are also possible.

[0042] Armrests 56 are constructed such that they are pivotable about a substantially horizontal pivot axis between a use position (FIGS. 2 and 3) and a stowed position (not shown). In some embodiments, armrests 56 are constructed in any of the manners disclosed in commonly assigned U.S. patent application Ser. No. 15/267,493 filed Sep. 16, 2016, by inventors Anish Paul et al. and entitled PATIENT SUPPORT APPARATUS, the complete disclosure of which is incorporated herein by reference. Other constructions of armrests 56 are also possible.

[0043] In some embodiments, person support apparatus 20 is constructed to be able to move backrest 42 and seat 44 between a seated configuration (FIG. 2) and a standing configuration (not shown). The standing configuration is adapted to more easily allow a patient to either exit from person support apparatus 20 or to enter person support apparatus 20. One example of such a standing position is shown in FIG. 2 of commonly assigned U.S. patent application Ser. No. 15/602,558 filed May 23, 2017, by inventor Anish Paul and entitled MEDICAL SUPPORT APPARATUS WITH STAND ASSISTANCE, the complete disclosure of which is incorporated herein by reference. Person support apparatus 20 may be configured to move to such a standing configuration, or other types of standing configurations.

[0044] Although FIGS. 2 and 3 illustrate person support apparatus 20 having specific orientations for backrest 42, it will be understood that backrest 42 is capable of being moved to a plurality of different orientations beyond what is shown in the accompanying drawings. Such movement occurs, in at least one embodiment, by a user activating a control on user interface 50. In some embodiments, person support apparatus 20 is constructed such that backrest 42, seat 44, and leg rest 52 (in some instances) move together via separate actuators that are coordinated by a controller, such as, but not limited to, a microcontroller. One example of a controller adapted to coordinate motion of backrest 42, seat 44, and leg rest 52 and suitable for inclusion in person support apparatus 20 is disclosed in commonly assigned U.S. patent application Ser. No. 14/801,167 filed Jul. 16, 2015, by inventors Anish Paul et al. and entitled MEDICAL SUPPORT APPARATUS, the complete disclosure of which is incorporated herein by reference.

[0045] For both person support apparatuses 20 and 20, backrest 42 is pivotally coupled to seat 44 by way of a pair of pivot assemblies 40a, 40b (FIGS. 4-7). A first one of the pivot assemblies 40a is positioned on a first side of backrest 42 and seat 44 and a second of the pivot assemblies 40b is positioned on a second and opposite side of backrest 42 and seat 44. Each pivot assembly 40a,b is a mirror image of each other and operates in the same manner. Accordingly, the following description will focus on a single one of the pivot assemblies (referred to herein as pivot assembly 40) with the understanding that the description applies equally to both pivot assemblies 40a and 40b.

[0046] As can be seen in FIGS. 4-7, pivot assembly 40 includes a backrest slide bar 58 mounted to a backrest body 60, a seat slide bar 62 mounted to a seat body 64, a backrest link 66, a seat link 68, a plurality of supports 70, and a pivot joint 72. Backrest body 60 is a rigid structure that either defines a backrest surface 76, or provides support for an attached backrest surface 76 (FIGS. 4-9). Seat body 64 is a rigid structure that either defines a seat surface 78, or provides support for an attached seat surface 78. Backrest body 60 is shaped to generally define a backrest plane 80, and seat body 64 is shaped to generally define a seat plane 82 (FIGS. 8-9), although it will be understood that neither body necessarily needs to be absolutely planar. It will also be understood, however, that notwithstanding the planes 80 and 82 defined by backrest body 60 and seat body 64, respectively, neither backrest surface 76 nor seat surface 78 need to be planar. Either or both of backrest surface 76 and seat surface 78 may be contoured, defined by molded foam, or otherwise have non-planar aspects to them. Indeed, in some embodiments, a mattress or other cushion is placed on top of backrest 42 and/or seat 44, and the mattress or cushion includes a patient-contacting surface that may be either planar or non-planar.

[0047] As backrest 42 pivots with respect to seat 44, backrest slide bar 58 slides along backrest body 60 in a generally linear fashion that is parallel (if not co-planar) to backrest plane 80. This sliding movement can be seen more easily by reviewing the different positions of backrest slide bar 58 in each of FIGS. 4-7 in comparison to backrest body 60. Similarly, as backrest 42 pivots with respect to seat 55, seat slide bar 62 slides along seat body 64 in a generally linear fashion that is parallel (if not co-planar) to seat plane 82. This sliding movement can also be seen more easily by comparing the different positions of seat slide bar 62 in each of FIGS. 4-7 with respect to seat body 64. Pivot joint 72 pivotally couples backrest slide bar 58 to seat slide bar 62.

[0048] Backrest slide bar 58 is slidingly supported on backrest body 60 by way of a pair of backrest supports 70a and 70b. Seat slide bar 62 is slidingly supported on seat body 64 by way of a pair of seat supports 70c and 70d. Each support 70a-d may include a low-friction surface, a roller bearing, or other conventional structure adapted to allow slide bars 58 and 62 to easily slide along bodies 60 and 64, respectively. Each of supports 70a and 70b are positioned inside of an elongate opening 84 defined in backrest slide bar 58, and each of supports 70c and 70d are positioned inside of an elongate opening 86 defined in seat slide bar 62. In the illustrated embodiment, elongate openings 84 and 86 are both straight and parallel to their respective backrest and seat planes 80 and 82. Either or both of elongate openings 84 and 86 could be modified to be non-parallel to their respective planes 80 and 82, or to include curvature so as to alter the pivoting motion of backrest 42 with respect to seat 44. The length of elongate openings 84 and 86 may also be shortened or expanded in order to change the range of pivoting of backrest 42 with respect to seat 44.

[0049] Backrest link 66 includes a first end 88 pivotally coupled to backrest 42 and a second end 90 pivotally coupled to seat slide bar 62. As seat slide bar 62 slides relative to seat body 64, the coupling of second end 90 to seat slide bar 62 ensures the second end of backrest link 66 slides with seat slide bar 62. Seat link 68 includes a first end 92 pivotally coupled to seat 44 and a second end 94 pivotally coupled to backrest slide bar 58. As backrest slide bar 58 slides relative to backrest body 60, the coupling of second end 94 to backrest slide bar 58 ensures the second end of seat link 68 slides with backrest slide bar 58.

[0050] Seat slide bar 62 of first pivot assembly 40a is coupled via a cross-bar 74 to seat slide bar 62 of second pivot assembly 40b (FIG. 7). In order to pivot backrest 42 with respect to seat 44, a powered actuator 96 is included within person support apparatuses 20 and 20 that is coupled to cross-bar 74. More particularly, actuator 96 includes a first end 98 pivotally coupled to the underside of seat 44 and a second end 100 pivotally coupled to cross-bar 74. When actuator 96 is activated, it either increases the distance between its first and second ends 98 and 100, or it decreases the distance between its first and second ends 98 and 100, depending upon whether the patient wishes to raise or lower backrest 42. Increasing the distance between ends 98 and 100 raises backrest 42 while decreasing the distance between ends 98 and 100 lowers backrest 42. In the illustrated embodiment, only a single actuator 96 is used to control the motion of backrest 42 relative to seat 44. In other embodiments, however, one or more additional actuators 96 can be used to pivot backrest 42 with respect to seat 44, if desired.

[0051] In some embodiments, actuator 96 is an electrical actuator having a motor inside of it, or otherwise driving it. It will be understood, however, that other types of powered actuators may alternatively be used, such as, but not limited to, pneumatic actuators and/or hydraulic actuators. Although not shown in the drawings, actuator 96 is in electrical communication with one or more user interfaces 50 having one or more controls for controlling the movement of actuator 96. In some embodiments, any one or more of the user interfaces 50 may be configured in any of the manners disclosed in commonly assigned U.S. patent application Ser. No. 15/170,979 filed Jun. 2, 2016, by inventors Aaron Douglas et al. and entitled PATIENT SUPPORT APPARATUSES WITH DYNAMIC CONTROL PANELS, the complete disclosure of which is incorporated herein by reference.

[0052] In some embodiments, the controller that controls actuator 96 is also configured to control other actuators of person support apparatus 20 and/or 20 (not shown), such as an actuator for controlling lifts 26 of person support apparatus 20, an actuator for controlling leg rest 52 of person support apparatus 20, and/or an actuator for controlling the tilting and/or height of seat 44 of person support apparatus 20. The control of the motor inside of, or associated with, actuator 96 and/or any of the other actuators (if included) can be carried out in any of the manners disclosed in more detail in commonly assigned U.S. patent application Ser. No. 14/838,693 filed Aug. 28, 2015, by inventors Daniel Brosnan et al. and entitled PATIENT SUPPORT APPARATUS WITH ACTUATOR BRAKE CONTROL, the complete disclosure of which is incorporated herein by reference. Other manners of controlling the motor(s) can also, of course, be used.

[0053] FIGS. 8 and 9 illustrate the manner in which pivot assemblies 40 cause backrest 42 to pivot with respect to seat 44. FIG. 8 shows backrest 42 and seat 44 in a flat orientation while FIG. 9 shows backrest 42 pivoted to a raised orientation relative to seat 44. As can be seen through a comparison of FIG. 8 to FIG. 9, backrest 42 and seat 44 are positioned close together at the same relative height when they are both in the flat orientation (FIG. 8), and backrest 42 shifts rearwardly away and up from seat 44 when it is pivoted upwardly to a raised orientation (FIG. 9). More specifically, when backrest 42 and seat 44 are both flat, backrest 42 is spaced rearwardly from seat 44 by a first distance D1, and both backrest 42 and seat 44 are positioned at substantially the same height (FIG. 8). As backrest 42 pivots upwardly, it moves rearwardly and upwardly such that, when it reaches the orientation illustrated in FIG. 9, backrest 42 is spaced rearwardly from seat 44 a second distance D2 that is greater than D1, and is positioned upwardly from seat 44 a distance D3. Depending upon the particular dimensions of the backrest 42 and seat 44 and the desired feel for a particular person support apparatus, the difference between D2 and D1 may be approximately in the range of one to two inches, while the value of D3 may be approximately in the range of several inches. Other specific values may be used. In the illustrated embodiment, the difference between D2 and D1 is greater than D3. That is, backrest 42 changes its horizontal separation from seat 44 more than it changes its height relative to seat 44 as it pivots.

[0054] FIGS. 8 and 9 also illustrate the location of a virtual pivot axis 102 created by the pivoting movement of backrest 42 relative to seat 44. Virtual pivot axis 102 may alternatively be referred to as an instantaneous center of rotation. It is the point that, were it affixed to backrest 42, would experience zero velocity at a particular instant in time as backrest 42 pivots. As can be seen in FIGS. 8 and 9, virtual pivot axis 102 starts at a first location above backrest 42 and rearwardly of seat 44 when both backrest 42 and seat 44 are generally flat. As backrest 42 is pivoted upwardly, virtual pivot axis 102 moves forwardly (toward seat 44) and also lowers its height relative to seat 44. Virtual pivot axis 102 undergoes continuous movement during the pivoting of backrest 42. Such movement follows a curved path between the position of virtual pivot axis 102 shown in FIG. 8 and the position of virtual pivot axis 102 shown in FIG. 9. The precise shape of the curved path can be changed by changing the relative dimensions, positions, and/or angular orientations of the slide bars 58, 62 and links 66, 68 with respect to each other.

[0055] Although other pivot constructions may be implemented to provide a continuously moving virtual pivot axis during pivoting of a backrest, pivot assemblies 40 are constructed in a compact manner that reduces the amount of space that might otherwise be necessary to implement the pivoting motion of backrest 42. In the illustrated embodiment, backrest and seat links 66 and 68 do not extend away from backrest surfaces 76 and seat surface 78, respectively, beyond slide bars 58 and 62. Further, by being oriented parallel to planes 80 and 82, slide bars 58 and 62 do not include any protrusions or other structures that extend away from backrest 42 and seat 44, respectively, and whose space-occupying needs would otherwise need to be accommodated in the overall design of person support apparatus 20, 20.

[0056] In the illustrated embodiments, both backrest link 66 and seat link 68 are solid one-piece components made from suitably strong material, such as, but not limited to metal. Similarly, slide bars 58 and 62, and cross-bar 74 are rigid, one-piece components made from suitably strong material, such as, but not limited to, metal. In alternative embodiments, backrest link 66, seat link 68, and slide bars 58 and 62 could be constructed from multiple rigid components or in other manners.

[0057] It will be understood that pivot assemblies 40 and person support apparatuses 20 and 20 may be varied from the embodiments shown in the attached drawings and described herein. For example, any of the person support apparatuses 20, 20 may be modified to include only a single pivot assembly 40 (rather than the two shown in FIGS. 4-7) or more than two pivot assemblies 40 for pivoting backrest 42 with respect to seat 44. Pivot assemblies 40 may also be incorporated into other pivoting components of a support surface other than backrest 42, such as, but not limited to, a thigh or leg section of a patient support surface (e.g. thigh section 46 or foot section 48 of support deck 30).

[0058] Various additional alterations and changes beyond those already mentioned herein can be made to the above-described embodiments. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described embodiments may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Any reference to claim elements in the singular, for example, using the articles a, an, the or said, is not to be construed as limiting the element to the singular.