Patient support apparatus with body slide position digitally coordinated with hinge angle

Abstract

An articulated patient support apparatus includes upper and lower body support frames hinged together to form a patient support assembly which is hinged to head and foot end supports. One end of the assembly includes a length compensator to enable hinged angulation between the body support frames. Hinge motors are connected between the frames to cause hinged articulation therebetween. One or both of the body support frames has a body slide assembly mounted thereon to enable part of a patient's body to move linearly along the particular body support frame by operation of a slide motor to compensate for hinged articulation of the frames. The hinge motors and slide motor have encoders interfaced to a controller to digitally coordinate sliding movement with hinging articulation.

Claims

1. A patient support apparatus comprising: (a) a base including a head end support and a foot end support positioned in spaced relation to said head end support; (b) an upper body support frame hingedly connected at an outer end to said head end support; (c) a lower body support frame hingedly connected at an outer end to said foot end support and hingedly connected to said upper body support frame to enable an angular orientation between said support frames at an inward hingedly connected articulation; (d) a body slide assembly including a body slide support pad, wherein the body slide assembly slidingly moves the body slide support pad along the lower body support frame, the body slide assembly having a body slide motor engaged between the body slide support pad and the lower body support frame; and (e) a controller interfaced with said body slide motor and a motor to angulate said hingedly connected support frames to operatively coordinate positioning of said body slide support pad with said angular orientation at the inward hingedly connected articulation.

2. An apparatus as set forth in claim 1 wherein: (a) said body slide motor is engaged with said body slide support pad by way of an endless belt mounted on said associated body support frame and secured to said body slide assembly.

3. A patient support apparatus as set forth in claim 1 wherein: (a) at least one of said end supports includes an end lift motor, said end lift motor being activated to selectively lift and lower said outer end of said body support frame.

4. A patient support apparatus as set forth in claim 1 further comprising: (a) a length compensator engaged between the outer end of one of said frames and its respective end support to thereby enable said angular orientation between said support frames and with said end supports.

5. A patient support apparatus as set forth in claim 1 further comprising: (a) a hinge articulation encoder engaged with said controller in such a manner as to generate a hinge articulation signal indicating said angular orientation between said support frames; (b) the controller having said hinge articulation encoder interfaced with and operable to coordinate positioning of said body slide support pad by said body slide motor along said lower body support frame.

6. A patient support apparatus as set forth in claim 1 further comprising: (a) a body slide position encoder engaged between said body slide assembly and the lower body support frame in such a manner as to generate a slide position signal indicating a position of said body slide support pad along said lower body support frame; and (b) the controller having the body slide position encoder interfaced thereto and operative to coordinate positioning of said body slide support pad by said body slide motor along said lower body support frame with variations of said angular orientation between said support frames by said controller, the position of the body slide support pad being indicated by said slide position signal, and the variations of said angular orientation being indicated by said hinge articulation signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of an embodiment of a patient support structure with a body slide position digitally coordinated with a hinge angle according to the present invention.

(2) FIG. 2 is a side elevational view of the patient support structure with body support frames thereof in 180° or hinge-neutral alignment.

(3) FIG. 3 is a perspective view of the body support frames of the patient support structure at a reduced scale.

(4) FIG. 4 is a top plan view of the body support frames.

(5) FIG. 5 is a longitudinal sectional view of components of the body support frames taken along line 5-5 of FIG. 4 and illustrate hinge articulation and length compensation details thereof.

(6) FIG. 6 is a greatly enlarged fragmentary cross sectional view similar to FIG. 5 and illustrates details of a hinge motor and a worm drive mechanism for articulating a hinge of the body support frames.

(7) FIGS. 7 and 8 are greatly enlarged fragmentary perspective views of a worm gear of the worm drive mechanism of the body support frames.

(8) FIG. 9 is an enlarged perspective view of an upper body slide mechanism of the patent support structure, shown removed from the patient support apparatus and with a portion broken away to show details thereof.

(9) FIG. 10 is an end perspective view of the upper body slide mechanism.

(10) FIG. 11 is a side elevational view of the patient support structure with the body support frames in a hinge-up relationship, with the upper body slide moved toward the hinge and with a foot end of a lower body support frame in a lowered position.

(11) FIG. 12 is a side elevational view of the patient support structure with the body support frames in a hinge-down relationship, with the upper body slide moved away from the hinge.

(12) FIG. 13 is an enlarged fragmentary perspective view of a foot end of the patient support structure with a portion of a lower body support frame member removed to illustrate a length compensation rod thereof.

(13) FIG. 14 is an enlarged fragmentary perspective view of a foot end support of the patient support structure with portions broken away to illustrate details of a secondary lift mechanism thereof.

(14) FIG. 15 is an enlarged fragmentary perspective view of a head end support of the patient support structure with portions broken away to illustrate details of a roll motor thereof.

(15) FIG. 16 is a side elevational view of a modified embodiment of the patient support structure having a lower body slide mechanism digitally coordinated with an angle of the hinge.

(16) FIG. 17 is an enlarged fragmentary side elevational view of the modified patient support structure with body support frames in a hinge-neutral relationship.

(17) FIG. 18 is a greatly enlarged fragmentary perspective view of components of the body support frames and illustrate details of the lower body slide mechanism.

(18) FIG. 19 is a greatly enlarged fragmentary perspective view of the modified patient support structure with the body support frames in a slightly hinge-down relationship.

(19) FIG. 20 is a perspective view of the modified patient support structure with the body support frames in a hinge-up relationship and with the lower body slide mechanism moved toward the hinge.

(20) FIG. 21 is a fragmentary perspective view of the modified patient support structure with the body support frames shown in a hinge-down relationship and with the lower body slide mechanism moved away from the hinge.

(21) FIG. 22 is an enlarged fragmentary perspective view similar to FIG. 21 and shows the body support frames in a hinge-down relationship.

(22) FIG. 23 is a block diagram showing control components of the patient support structure for digitally coordinating the positioning of body slide mechanisms with the angle of the hinge connecting the body support frames.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

(23) As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

(24) Referring to the drawings in more detail, the reference number 301 generally designates a patient support structure with a body slide position digitally coordinated with a hinge angle, according to the present invention. The patient support structure 301 generally includes an upper body frame 303 and a lower body frame 305 which are hingedly connected at a support hinge 307 to enable hinged articulation therebetween. A body slide assembly 309 is engaged with one of the body frames 303 or 305, such as the upper body frame 303, to avoid stretching or compressing the body of a patient on the support structure during articulation of the upper and lower body support frames 303 and 305 about hinge 307. Linear movement of the body slide assembly 309 is digitally coordinated with the angle of articulation of the frames 303 and 305 about the hinge 307.

(25) The body support frames 303 and 305 form a patient support assembly 311, with the upper body support frame 303 being hingedly connected to a head end support assembly 316 and the lower body support frame 305 hingedly connected to a foot end support assembly 318. The illustrated end support assemblies 316 and 318 are connected in fixed relation by an elongated center beam 320. One end of the patient support assembly 311 includes a length compensator mechanism 322, such as at a foot end of the lower body support frame 305, to enable the patient support assembly 311 to lengthen when the body support frames 303 and 305 are hingedly articulated.

(26) Referring to FIGS. 3-5, the illustrated patient support assembly 311 includes the upper and lower body support frames 303 and 305 which are pivotally connected at the hinge, or as illustrated hinges, 307 having aligned hinge axes 325. The illustrated upper body support frame 303 includes a pair of spaced apart elongated upper body support members 328 which are interconnected in parallel relation at a head end by a head crossbar assembly 330. Referring to FIG. 15, the illustrated head crossbar assembly includes a head crossbar 332 and a head crossbar plate 334. The head crossbar plate 334 interconnects a pair of transversely spaced head end caps 336 and is reinforced by the head crossbar 332. Head ends of the upper body support members 328 are receive in and secured to the head end caps 336. The head crossbar assembly 330 includes a pair of spaced apart head end hinge brackets 338 which are secured to the head crossbar 332 and the head crossbar plate 334. The head end hinge brackets 338 hingedly connect with structure on the head end support assembly, as will be described further below.

(27) The illustrated lower body frame 305 includes a pair of elongated lower body support members 342 connected in spaced apart parallel relation by a foot crossbar assembly 344. Referring to FIG. 13, foot ends of the lower body support members 342 are closed by foot end caps 346 to which the members 342 are secured. The end caps 346 have bushing members 348 secured thereto. The illustrated foot crossbar assembly 344 includes an inverted U-shaped foot crossbar member 350 having transverse strut 352 and a pair of rod support legs 354 depending in an outward angular orientation therefrom. The transverse strut 352 may have an upwardly arched center section or arch 356 to provide clearance of the center beam 320 when a foot end of the patient support assembly 311 is lowered to its lower extreme. The crossbar member 350 has a pair of transversely spaced hinge lugs 358 extending upwardly from outer ends thereof. Each of the rod support legs 354 has an elongated translator rod 360 extending therefrom. The rods 360 are slidably received in the bushings 348 and form the length compensators 322 therewith. The illustrated lower body frame 305 may be provided with hip pads 362 secured in transverse spaced relation to the lower body support members 342 to support hip and thigh areas of a patient positioned on the patient support assembly 311.

(28) On the illustrated patient support apparatus 301, hinged articulation of the patient support assembly 311 is actuated by a pair of hinge motor assemblies 365 which are engaged between the upper and lower body support frames 303 and 305. Referring to FIGS. 6-8, each of the illustrated hinge or angle motor assemblies 365 includes a worm drive unit 367 mounted on one of the body support frames and a worm gear unit 369 on the opposite body support frame. As illustrated in FIG. 5 and in other figures, the worm drive unit 367 is mounted on the lower body support frame 305, and the worm gear unit 369 is mounted on the upper body support frame 303.

(29) Returning to FIG. 6, each illustrated worm drive unit 367 is mounted in a hinge motor housing 371 having a motor housing stub 373 which is received in and secured within a hinge end of an associated one of the lower body support members 342. The worm gear unit 369 has a worm gear mounting stub 375 which is received in and secured within a hinge end of an associated upper body support member 328. The motor housings 371 are hingedly connected to the worm gear units 369 at the hinge axis 325 by hinge pins 377 to thereby hingedly connect the upper and lower body support frames 303 and 305. In an embodiment of the patient support assembly 301, the hip pads 362 are secured to the motor housings 371 rather than directly on the lower body support members 342.

(30) The illustrated worm drive unit 367 includes a rotary electric hinge motor 379 engaged through hinge motor gearing 381 with a substantially cylindrical “worm” 383 having one or more helical threads 385 or advancement structures formed on an external surface thereof. The gearing 381 includes internal gears (not shown) which reduce the rotary speed of the motor 379 to an appropriate rate for the worm 383. A housing of the motor 379 is joined to a housing of the gearing 381. The drive unit 367 includes a worm bracket 387 having bearing sets in which the worm 383 is rotatably mounted. The illustrated worm drive unit 367 has a hinge encoder 389 engaged therewith which outputs a hinge angle signal having a value which is proportional to the angle of articulation between the upper and lower body support frames 303 and 305 about the hinge axis 325. Rotary and angle encoders which are appropriate for use as the hinge encoder 389 are well known by those skilled in mechanical and electrical control arts.

(31) Referring to FIGS. 7 and 8, the illustrated worm gear unit 369 is formed by worm gear sector 391 having an outer cylindrical surface 393 with gear teeth 395 formed therein. The teeth 395 are helical segments formed into the cylindrical surface 393 and are shaped to mesh with the worm thread 385. The worm gear mounting stubs 375 extend from the worm gear sector 391. When the hinge motor housings 371 are hingedly connected to the worm gear units 369 by the hinge pins 377, the worm threads 385 are positively engaged with the worm gear teeth 395 whereby rotation of the worms 383 by the motors 379 cause hinged articulation of the upper and lower body support frames 303 and 305 about the hinge axis 325.

(32) Although a specific embodiment of the hinge motor assemblies 365 is described and illustrated, other configurations of hinge motor assemblies 365 are contemplated. It is also foreseen that the patient support assembly 311 can be hingedly articulated by motors (not shown) located at the head and/or foot ends thereof. It is foreseen that the body support frames 303 and 305 could be hingedly connected to the head and foot end support assemblies 316 and 318 respectively but not hingedly connected to one another, as disclosed in U.S. Published Application 2011/0107516, which is incorporated herein by reference.

(33) The head and foot end support assemblies 316 and 318 are somewhat similar in structure and function. The end support assemblies 316 and 318 are sometimes referred to as support piers or support columns. The head end support assembly 316 includes a transversely extending head end base 400 having a head end lift column 402 upstanding from a central region thereof and terminating in a head end articulation mechanism 404. Similarly, the foot end support assembly 318 includes a transversely extending foot end base 406 with a foot end lift column 408 upstanding from a central region thereof and terminating an a foot end articulation mechanism 410. The illustrated end support bases 400 and 406 have casters 412 to render the patient support apparatus 301 mobile. Preferably, the casters 412 are capable of swiveling about vertical axes and being releasably locked in position when needed. Similarly, the casters 412 preferably have brake mechanisms (not shown) to selectively brake wheels thereof when needed. As illustrated, the head and foot end bases 400 and 406 are interconnected by the center beam 320.

(34) Referring to FIGS. 2 and 15, the illustrated head end lift column 402 includes three column sections which are telescoped. A head end lift mechanism (not shown) within the column 402 is activated to extend or retract the column sections. The lift mechanism may be a pneumatic or hydraulic cylinder or cylinders or some other type of lift mechanism, such as one or two jack screws (not shown) rotated by associated electric motors (not shown). Telescoping lift column arrangements are well known in patient support systems to those skilled in these arts.

(35) The head end lift column 402 terminates at an upper end in the head end articulation mechanism 404. The illustrated articulation mechanism 404 includes a mounting plate 416 which has a roll motor 418 (FIG. 15) mounted thereon. The roll motor 418 is activated to rotate the patient support assembly 311 about a substantially horizontal head end roll axis 420 which passes through a roll motor shaft 422 (FIG. 2). The illustrated roll motor 418 preferably incorporates a harmonic drive mechanism. Harmonic drives are well known in mechanical arts and have the benefits of low backlash or play, light weight and compactness, and very high gear ratios. Alternatively, other types of roll motors and drive mechanisms can be employed in the patient support apparatus 1.

(36) The illustrated head end articulation mechanism 404 includes a head end ladder bracket assembly 424 secured to the roll motor shaft 422. The assembly 424 includes a ladder bracket base plate 426 which is secured to the shaft 422 and a hinge or coupler plate 428 which is releasably connected to the base plate 426 by quick release pins or connectors 430. The hinge plate 428 has a pair of transversely spaced hinge lugs 432 depending therefrom. The lugs 432 have the hinge brackets 338 of the head crossbar assembly 330 pivotally connected thereto. Pivotal engagement of the hinge brackets 338 with the hinge lugs 432 enables the upper body support frame 303 to pivot relative to the head end support assembly 316.

(37) Referring particularly to FIGS. 2, 13, and 14, the foot end support assembly 318 includes the foot end base 406 which has a foot end lift column 408 upstanding from a middle region thereof. The foot end base 406 has the casters 412 which are similar in function to the casters 412 on the head end base 400. The foot end lift column 408 forms a primary lift mechanism 436 for the foot end of the patient support assembly 311. The illustrated lift column 408 is a telescoping mechanism and is substantially similar to the front end lift column 402.

(38) In the illustrated patient support apparatus 1, the foot end of the patient support assembly 311 is provided with a greater degree of vertical movement than the head end. An upper section of the lift column 408 supports a secondary lift framework 438 forming a support for a secondary lift mechanism 439 of the foot end support assembly 318. The framework 438 includes a horizontal mounting plate 440 secured to a top end of the lift column 408, an elongated vertical back plate 442 secured to the mounting plate 440, vertical side plates 444 secured to the mounting plate 440 and the back plate 442, and a horizontal top plate 446 secured to the back plate 442 and the side plates 444. The components 440-446 may be secured to one another by welding or by other means.

(39) A pair of vertically extending, transversely spaced, and parallel secondary lift screws 448 are mounted in bearings in the top plate 446 and a bottom plate (not shown) extending from a lower end of the back plate 442. The lift screws 448 are threadedly engaged with outer ends of a secondary lift carriage 450 whereby simultaneous rotation of the lift screws 448 lifts or lowers the carriage 450. In the illustrated secondary lift mechanism 439, upper ends of the lift screws 448 have driven sprockets 452 mounted thereon. A reversible secondary lift motor 454 is mounted on the top plate 446 and has a drive sprocket (not shown) mounted on a motor shaft (not shown) of the motor 454. A sprocket chain (not shown) is engaged with the drive sprocket and the driven sprockets 452 whereby activation of the motor 454 causes rotation of the lift screws 448. The lift carriage 450 has a ladder pivot 456 rotatably mounted therein. The lift screws 448, lift carriage 450, and the sprockets 452 are covered by a secondary lift housing 458 and a top cover 460. The housing 458 is provided with a central slot 462 to provide clearance for the ladder pivot 456.

(40) The ladder pivot 456 has a foot ladder plate 464 secured thereto which has a foot end coupler or hinge plate 466 releasably connected thereto by quick-release connectors 468. The hinge plate 466 has a pair of transversely spaced hinge lugs 470 depending therefrom. The plates 464 and 466, the connectors 468, and the hinge lugs 470 form a foot end ladder bracket assembly 472. The hinge lugs 470 is hingedly connected to the hinge lugs 358 of the foot crossbar assembly 344 to enable hinged movement of lower body support frame 305 relative to the foot end support assembly 318. Connection of the ladder plate 464 to the ladder pivot 456 provides a passive pivot at the foot end of the patient support assembly 311 when the assembly is subjected to roll movement by activation of the roll motor 418 within the head end support assembly 316. It should be noted that the patient support assembly 311 can only be rolled when the ladder pivot 456 is aligned with the roll motor shaft 422. Otherwise, the foot end of the lower body frame 311 would be swung in an arc radially spaced from the ladder pivot 456.

(41) When a patient is supported on the patient support assembly 311 and the upper and lower body support frames 303 and 305 are pivoted about the hinge axis 325, a bending axis of the patient's body is spaced radially from the hinge axis 325. Because of this, the patient's body tends to be stretched when the patient support assembly 311 is hinged upwardly and compressed when the assembly 311 is hinged downwardly. In order to relieve such stretching or compressing stress on the patient's body, the patient must be repositioned or the upper or lower portion, or both portions, of the patient's body must be able to move linearly along the appropriate body support frame 303 or 305. The body slide assembly 309 is provided on either the upper or lower body support frame 303 or 305. It is also foreseen that a body slide assembly 309 could be provided on both of the body support frames 303 and 305.

(42) Referring to FIGS. 9 and 10, the illustrated body slide assembly 309 is implemented as an upper body slide mechanism 475 of the patient support apparatus 301, including an upper body trolley structure 477 having a sternum pad 479 secured thereto. The illustrated mechanism 475 includes a pair of elongated upper body slide guide members 481 which are sized and shaped to be removably received on the upper body support members 328 of the upper body support frame 303. The configuration of the guide members 481 enable the entire upper body slide mechanism 475 to be removed from the upper body support frame 303 when necessary. The guide members 481 are interconnected by cross members 483 which extend therebetween to form a rigid framework. Cross sections of the left and right hand guide members 481 are mirror images, and the guide members 481 have guide grooves 484, formed on the illustrated guide members 481 by an upper flange 485 and a lower ledge 486 on inner sides of each guide member 481. The grooves 484 slidably receive elongated trolley guide bars 487 which are secured to the trolley 477, as by fasteners 489.

(43) It is foreseen that the upper body slide mechanism 475 could be adapted for passive sliding to relieve stretching or compressing stresses on the patient's body when the patient support assembly 311 hinges up or down. However, a surgeon would likely prefer for the patient to be supported a stable and stationary platform during surgical procedures. Therefore, such a passively sliding upper body slide mechanism would require a brake (not shown) to fix the position thereof.

(44) In an embodiment of the patient support apparatus 301, the upper body slide mechanism 475 is provided with a upper body slide motor 492 engaged with the upper body trolley 477 to positively translate it along the upper body slide guides 481. The illustrated slide motor 492 is engaged with a gearbox 494 which is connected by motor mount brackets 496 to one of the upper body slide guides 481. A transversely extending slide motor shaft 498 extends through the gearbox 494 and has drive sprockets or pulleys 500 secured on the opposite ends thereof. The sprockets 500 are rotatably mounted on the inner sides of the slide guides 481. Freewheeling or driven sprockets or pulleys 502 are rotatably mounted on the inner sides of the slide guides 481 at opposite ends thereof. An upper slide timing belt 504 is reeved about the pairs of drive and driven sprockets 500 and 502 and secured to the trolley guide bars 487. The timing belts 504 are preferably toothed on their inner surface, as are the sprockets 500 and 502, to prevent slippage between the belt 504 and the sprockets 500 and 502.

(45) The upper body slide mechanism 475 includes an upper body slide (UBS) encoder 506 (FIG. 23) to accurately measure movement of the trolley 477 relative to the guides 481 and, thus, to the upper body support frame 303 and to provide a digital slide signal indicating the position of the trolley 477 relative to the body support frame 303. The encoder 506 may be incorporated into the motor 492, the gearbox 494, the belt 504, the guide bars 487, or the like, as would occur to one skilled in appropriate arts. The encoder 506 enables control of movement of the trolley 477, and thus the upper body of the patient, with hinging movement of the body support frames 303 and 305, as will be described below, so that the trolley 477 moves toward the hinge axis 325 (as shown in FIG. 11) when the patient support assembly 311 is hinged upwardly and away from the hinge axis 325 (as shown in FIG. 12) when the assembly 311 is hinged downwardly.

(46) In some circumstances it might be considered desirable to provide sliding adjustment of the lower body of a patient in response to upward or downward hinging articulation of the patient support assembly 311. Referring particularly to FIG. 18, an embodiment of the body slide assembly 309 is implemented as a lower body slide mechanism 510. In an embodiment of the lower body slide mechanism 510, such a mechanism is provided on each of the hinge motor housings 371, with the mechanisms on the right and left hinge motor housings 371 being substantially mirror images of one another.

(47) Each illustrated lower body slide mechanism 510 includes a hip pad support platform 512 in sliding engagement with a linear guide member 514 secured to a top surface of the associated hinge motor housing 371. The platform 512 is connected by a hip pad bracket 516 to a hip pad actuator rod 518. An elongated hip pad actuator support base or plate 520 is secured to the lower side the lower body support member 342 associated with the particular hinge motor housing 371 and may also be secured to the housing 371. A hip pad actuator screw 522 is rotatably supported in spaced apart screw bearings 524 depending from the support base 520. A hip pad actuator nut 526 is meshed with the screw 522 so that rotation of the screw 522 causes linear reciprocation of the nut 526 along the support base 520. A lower body slide actuator motor 528 is mounted on the support base and is engaged with the actuator screw 522 to rotate it.

(48) The motor 528 has a lower body slide encoder 530 engaged therewith and provides a digital lower body slide signal which indicates the linear position of the hip pad 512 relative to the lower body support frame 305. The lower body slide encoder 530 enables coordination of the movement of the lower body slide mechanism 510 so that the hip pad 512 is moved toward the hinge axis 325 (as shown in FIG. 20) when the patient support assembly 311 is hinged upwardly and away from the hinge axis 325 (as shown in FIG. 21) when the patient support assembly 311 is hinged downwardly. The hip pad actuator rod 518 is connected to the hip pad actuator nut 526 so that linear movement of the nut 526 along the screw 522 causes the hip pad platform 512 to move linearly along the guide 514. The hip pad platform 512 has one of the hip pads 362 secured thereto.

(49) Referring to FIG. 23, the patient support apparatus 301 includes a patient support control system 535 to enable medical personnel to control the configuration and orientation of components of the apparatus 301. The control system 535 includes a patient support controller or computer 537 having a plurality of patient support input controls 539 and a plurality of patient support actuators 541 interfaced thereto. The controller 537 includes a user interface 543, which may include a keyboard and display (not shown), to enable medical personnel to enter data into the controller 537 and to display alphanumeric and/or graphic information regarding states and of components of the apparatus 301.

(50) The inputs 539 include a hinge control 545 to enable personnel to cause the patient support assembly 311 to hinge upwardly or downwardly by directional activation of the hinge motors 379. As hinging articulation of the patient support assembly 311 occurs, the hinge encoders 389 provide hinge angle signals to the controller 537 to track the angle of the upper and lower body support frames 303 and 305 about the hinge axis 325 (FIG. 4). In response to the hinge angle tracking, the controller 537 activates the upper body slide motor 492 and/or the lower body slide motors 528 to move the respective upper body slide mechanism 475 and/or the lower body slide mechanism 510 in such a direction from the hinge axis 325 and to such a linear extent to provide translation compensation to prevent stretching or compressing a portion of the body of a patient supported on the patient support assembly 311 as the patient support assembly is hingedly articulated.

(51) The control system 535 preferably includes a manual body slide control 547 to enable initial positioning of the body slide assembly 309. The control 547 may be provided for controlling the upper body slide motor 492, the lower body slide motors 528, or both should both an upper body slide 475 and a lower body slide mechanism 510 be provided on the patient support apparatus 301. When the body slide assembly 309 is initially positioned, that position is detected by the upper body slide encoder 506 or lower body slide encoder 530 and conveyed to the controller 537 as the reference position of the body slide assembly 309. Thereafter, the upper body slide motor 492 is, or lower body slide motors 528 are, activated in such a manner as to coordinate the position of the associated body slide assembly 309 with the hinge angle as detected by the hinge encoders 389.

(52) Generally upper body slide trolley 477 or hip pad support platform 512 is moved toward the hinge axis 325 when the patient support assembly 311 is hinged upwardly and away from the hinge axis when the patient support assembly is hinged downwardly. The amount of linear movement of the trolley 477 or platform 512 is proportioned to the hinge angle between the body support frames 303 and 305 to avoid stretching or compression stresses in the patient's body as the patient support assembly 311 is hingedly articulated. The linear to angular movement relationship can vary depending on dimensional factors of the patient, such as the height, weight, girth, proportion of the upper body length to lower body length of the patient, and other factors. Such factors can be entered into the patient support controller 537 to control the proportion of linear movement of the trolley 477 or platform 512 to the hinge angle of the body support frames 303 and 305 in relation to the dimensional factors of the patient.

(53) In addition to the hinge motors 379 and the body slide motors 492 and 528, the patient support apparatus 301 includes the roll motor 418 (FIGS. 15 and 23), a head end lift motor or head motor 549 (FIG. 23), a foot end primary lift motor 551, and the foot end secondary lift motor 553 (FIGS. 14 and 23). Each of the motors 549, 551, 454, and 418 includes a corresponding control for its operation.

(54) A roll control 555 is interfaced to the controller 537 for reversibly activating the roll motor 418. A roll encoder 557 is engaged with the roll motor 418 and interfaced with the controller 537 to track the roll angle of the patient support assembly 311. A head motor control 559 is interfaced to the controller 537 for activating the head lift motor 549 to raise or lower the head end of the patient support assembly 311. A head motor encoder 561 is engaged with the head motor 549 and interfaced with the controller 537 to track the vertical position of the head end of the patient support assembly 311. Foot primary and secondary (PRI/SEC) controls 563 are interfaced to the controller 537 for activation respectively the foot primary motor 551 and the foot secondary motor 454 to lift and lower the foot end of the patient support assembly 311. Foot primary and secondary motor encoders 565 are engaged with the foot primary and secondary motors 551 and 454 and interfaced with the controller 537 to track the vertical position of the foot end of the patient support assembly 311.

(55) Embodiments of the patient support apparatus 301 have been described and illustrated in which the body slide position is digitally coordinated with the hinge angle of the body support frames 303 and 305. Such embodiments disclose a hinge connection between the body support frames 303 and 305. However, it is foreseen that the present invention could also be advantageously applied to types of patient support apparatus to enable digital coordination of the linear position of a body slide assembly 309 provided on one of a set of body support frames (not shown) which are not hingedly connected but which are capable of being positioned in a range of angular relations. The present invention is also intended to encompass such types of patient support apparatus.

(56) It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.