Note: Descriptions are shown in the official language in which they were submitted.
5~
081076-BHP - l -
TILTING SYSTEM FOR ADJU$TABLE HOSPITAL BED
Descr~tion
This invention relates to an adjustable hospital
bed haviny independently actuable head and foot acl-
justing mechanisms for elevating and lowering each endof the bed independently of the other end. More
particularly, the invention relates to an arranqement
for actuating those adjusting mechanisms to e~fect
direct tilting of the bed to a desired tilted position
from any other tilted or level position.
Adjustable hospital beds are usually vertically
movable so that the mattress supporting structure may
be established at a selected desired height, within a
range of permissible heights, ~rom the floor. The
lowermost level is most convenient when a patient is
entering or leaving the bed. On the other hand, the
uppermost height is generally preferred for examination
and treatment of the patient. To enhance the patient's
comfort, the mattxess support is divided into a series
of individually adjustable sections or panels that may
be positioned to provide a desired contour or con-
figuration. In addition, in many adjustable hospital
beds khe entire mattress supporting structure may be
tilted or canted to either a trendelenburg position
~head end down, ~oot end up~ or to a xeverse tren-
delenburg position (head end up, foot end down). The
bed i5 adjusted to a trendelen~urg position ~hen the
patient goes into shock, whereas a reverse trendelen-
~urg position is employed for drainaye.
s~
081076-BHP - 2 -
To maximize the vertical adjustment range or
travel in prior hospital beds, without sacrificing
stability, the mattress supportina struc~ure is cus-
tomarily mounted on a movable upper frame which inter-
connects, v;a head and foot adjustin~ mechanisms, to afixed lower base frame located close to the floor. The
adjusting mechanisms are actuated to either lift or
lower the upper frame, and consequently the mattress
supporting structure, as desired. For trendelenburg or
reverse trendelenburg positioning, the hospital bed
usually must first be placed at a predetermined height
(such as the extreme upper or extreme lower level
position~ and then actuated ~o the desired tilted
position. Complicated~ and someti~es confusing, steps
must therefore be taken by the opera~or and substantial
time is required to manipulate such prior hospital beds
to a tilted position. The slowness of the prior
hospital beds is particularly disadvantageous when a
patient suddenly goes into shock since time is of the
essence. It is imperative that no time is lost in
placing the patient's body in a trendelenburg position.
These shortcomings have now been overcome. By
only simple steps by the operator, the hospital bed of
the present invention may be shifted immediately and
directly to either a trendelenburg position or to a
reverse trendelenburg position, irrespective of its
position at the time. In other words, the bed may be
moved, fxom any level and from any tilted position,
directly to any othQr tilted position. It can go from
3Q a trendelenburg position directly to a reverse tren-
delen~urg position, and vice versa. Among other
advanta~es, this results in a signific~nt time saving
when adjusting the bed.
7~
081076-BHP - 3 -
The adjustable hospital bed of ~he present in-
vention comprises a stationary lower base frame and a
movable upper frame, each of the frames having head and
foot ends. A head adjusting mechanism, mounted on the
lower base frame at its head end, is provided for
raising and lowering t~e head end of the upper frame.
There is a foot adjusting mechanism, mounted on the
lower base frame at its foot end, for raising and
lowering the foot end of the upper frame. Indepen-
dently operable head and foot drive means are includedfor actuating the head and foot adjusting mechanisms,
respectively, to adjust the height of each end of the
upper frame independently of the other end. Finally,
the adjustable hospital bed comprises operator con-
trolled logic circuitry which, in response to a tren-
delenburg command, operates the head and foot drive
means to tilt the upper frame directly to a trendelen-
burg position regardless of its position at the time
the corNmand is issued. Conversely, when a reverse
txendelenburg command is received, the logic circuitry
operates the head and foot drive means to tilt the
upper frame directly to a reverse trendelenbury posi-
tion irrespective of its position when the command is
issued.
The features of the invention which are believed
to be novel are set forth with particularity in the
appended claims. The invention may best be understood,
however, by reference to the following description in
conjunction with the accompanying drawings in which
like reference numhers identify like elements, and in
which:
FIGURE 1 is a side view of an adjustable hospital
bed constructed in accordance with the invention, the
081076-BHP - 4 -
bed being illustrated with independently operable head,
foot, back and knee adjusting mechanisms placing the
bed in a normal horizontal position (the movable upper
frame and mattress support thereby being horizontal)
with the head end on the left and the foot end on the
right;
FIGURE 2 is a view of the foot end of the bed of
FIGURE l;
FIGURE 3 is a fragmentary and partially broken
away top or plan view of the bed of FIGURE 1 on an
expanded scale and illustrates drive screws for operat-
ing the adjusting mechanisms;
FIGURE 4 is a fragmentary side view of the bed
showing the side view of some of the parts illustrated
in FIGURE 3 and on the same scale as FIGURE 3;
FIGURE 5 is a fragmentary top view showing some of
the parts hidden in the FIGURE 3 view, the figure
illustrating clutches for coupling a common reversible
motor drive to the drive screws for the adjusting
mechanisms;
FIGURE 6 is a fragmentary side view, partially in
section, of some of the elements of FIGURES 3 and 5
(including one of the clutches~ on an expanded scale;
FIGURE 7 is a more detailed illustration of a
portion of the structure shown in FIGURE 6 and more
clearl~.shows the manner in ~hich the clutch may be
engaged and disengaged;
s5~
081076-BHP - 5 -
FIGURE 8 is a sectional view taken along the plane
of section line 8-8 in FIGURE 7;
FIGURE 9 is a sectional view taken along the plane
of section line 9-9 in FIGURE 7;
E`IGURE 10 is a fragmentary side view of a drive
screw and an associated drive mechanism which travels
along the drive screw, when the screw is rotated, and
actuates the associated bed adjusting mechanism;
FIGURE 11 is a fragmentary and enlarged view,
partially in section taken along the plane of section
line 11-11 in FIGURE 10, showing the drive screw and
drive mechanism of FIGURE 10;
FIGURE 12 is a sectional view taken along the
plane of section line 12-12 in FIGURE 10;
FIGURE 13 is a sectional view taken along the
plane of section line 13-13 in FIGURE 10;
FIGURE 14 illustrates the vertical movement of the
bed when the upper frame is horizontal and when both
the head and foot adjusting or lifting mechanisms are
actuated simultaneously;
FIGURE 15 depicts the manner in ~hich the bed may
be tilted to the reverse trendelenburg position (head
end up, foot end down~ when only the head adjusting
mechanism is operated;
~1~S7~L
081076-BHP - 6 -
FIGURE 16 shows the foot adjusting mechanism in
the same position as in FIGURE 15, but the head ad-
justing mechanism has been actuated so that the bed is
tilted in the other direction to the trendelenburg
position (head end down, foot end up);
FIGURE 17 illustrates the manner in which the
upper frame may be elevated or lowered while it is
tilted; and
F~C.URES 18 and 19 together schematically illus-
l~ trate logic circuitry for controlling the operation ofthe head, foot, back and knee adjusting mechanisms and
for controlling the dixection of motor rotation. Of
course, FIGURE 19 should be placed immediately to the
right of FIGURE 18 to display the complete control
circuit.
The disclosed hospital bed includes a stationary
or fixed lower base frame 10 (see particularly FIGURES
1, 2 and 4), and a movable upper frame 12 on which is
mounted an articulated mattress supporting structure
2~ 14. Frame 10 has a pair of longitudinal bars or rails
lOa with a pair of transverse or cross bars lOb at the
foot and head ends. ~lovable frame 12 is supported
on and is vertically adjustable with respect to fixed
frame 10 by means of head and foot adjusting or lifting
mechanisms 16, 18, respectively r which together provide
a parallelogram lifting system. It will be apparent,
however, that the invention may be employed with other
lifting systems, such as a trapezoidal system. Ad-
justing mechanism 18 takes t~e form of a lift yoke
3~ having a pair of channel shaped long lever or lift arms
18a rigidly afflxed to a pivot or torque tube 18b (see
FIGURE 2~ which in turn is pivotally attached, by means
~s~
081076-BHP - 7 -
of pivot studs 21, to a pair of brackets or lift
support plates 22 rigidly secured to upper frame 12.
The lift yoke also includes a pair of short lever arms
18c rigidly affixed to pivot ~ube 18b. The lower or
free end of each lever arm 18a pivotally connects to a
pair of brackets 24 rigidly affixed to the cross bar
10b at the foo~ end of base frame 10. It should be
apparent that by moving the free or upper ends of short
lever arms 18c to the right, as view~d in FIGURES 1 and
4, to effect clockwise rotation of yoke 18 around pivot
studs 21, brackets 22 and consequently th~ foot end of
upper frame 12 will be lowered. On the other hand, if
lever arms 18c are moved to the left to rotate yoke 18
in a counterclockwise direction, brackets 22 and the
foot end of ~rame 12 will be raised.
Although the drawings do not include an end view
of the head end o the bed, it will be understood that
head adjusting mechanism 16 takes the form of a lift
yoke of similar cons~ruction to yoke 18, having a pair
of long lever arms 16a rigidly secured to a pivot or
torque tube to which is also rigidly affixed a pair of
short lever arms 16c. By means of a pair of pivot
studs 25, the pivot tube is rotatably mounted to a pair
of lift support plates or brackets 26 rigidly secured
to frame 12. The lower or free ends of lever arms 16a
are pivotally coupled to the upper ends of brackets 27,
the lower ends of the brackets being pivotally attached
to fxame 10 by means of pivot studs 28~ In similar
fashion to the operation of yoke 18, when the upper
ends of lever arms 16c are moved to the right (as
viewed in FIGURE 1~ yoke 16 rotates clockwise around
pivot studs 25 causing ~rackets 76 and the head end o
~s~
081076-BHP ~ 8 -
upper frame 12 to descend. Conversely, when le~er arms
l~c are moved to the left, counterclockwise rotation
results and the head end of frame 12 moves upwardly.
The lower ends of brackets 27 are pivotally coupled to
base frame 10 by studs 28 to allow the bed to assume
the various positions shown in FIGURES 14-17.
Articulated mattress supporting structure 14 is
divided into four interconnected sections or panels,
namely a back support section 31, a center or seat
support section 32, an upper knee or thigh support
section 33J and a lower knee or foot section 34. Each
of the four support sections preferably takes the form
of a perforated metal panel, but of course other
constructions ~ould ~e employed. For example, each
mattress support section may constitute a bed spring~
Seat support section 32 is rigidly affixed to frame 12,
while one side or edge of back support section 31 is
pivotally connected, by means of a pair of pivot studs
36 (only one of which is shown in FIGURE 1), to seat
support section 32. As will be described, an adjusting
mechanism is provided for tilting back section 31
upward, with respect to fixed seat section 3~, to raise
the back and head of the patient occupying the bed to
maximize comfort. The tilting is achieved by a torque
ox pivot tube 39 (see FIGURE 12 secured to back section
31 by rigid structuxal members 41 and 42. A pair of
lever arms 43 ~only one of which is shown in FIGURE 1)
are rigidly affixed to tu~e 39 in order to facilitate
turning of the tu~e. As the free ends of lever arms 43
are moved to t~e left, as viewed in FIGURE 1, tube 39
rotates in a clockwise direction thereby tilting back
support section 31 upward.
~s~
o8lo76-sHp - 9 -
The adjacent sides of knee support sections 33 and34 are pivotally interconnected by a pair of pivot
studs 47, only one of which is shown in FIGURES 1 and
4. The left side of section 33 (as v.iewed in FIGURES 1
and 4) rigidly attaches ~o a torque or pivot tube 44
(see FIGURE 3~ which is rotata~ly mounted to seat
support section 32 ~y pivot studs 45, only one of which
is seen in FIGURES 1 and 4. A pair of lever arms 46
(see FIGURES 1, 3 and 4) are rigidly secured to torque
tube 44 so that movement of the free ends of those arms
toward the right (.as viewed in FI5URES 1 and 4~ results
in counterclockwise pivoting of tube 44 around pivot
studs 45. Upper knee support section 33 thereore
tilts upward and since that section is pivotally
connected to lower knee support section 34 by studs 47,
the left side of section 34 will be raised. Sections
33 and 34 will thus form an inverted V in order to
raise the patient's knees. An adjusting mechanism w.ill
be described for pivoting lever arms 46 to effect a
desired knee adjustme~t to maximize the patient's
comfort.
The movable members 16, 18, 31/ 33 and 34 may all
be actuated, either individually or collectively, by a
single reversible or bidirectional electric a-c motor
49 (.see FIGURES 3 and 5). supported on upper frame 12.
When energized, motor 49 drives gear 51 which in turn
rotates the four intercoupled dr.iven gears 52-550 Each
of the gears 52-55 couples, via a respective one of
our clutches 56-59, to a respective one of four screw-
threaded output drive shafts or drive scre~s 61-64,
screws 61~ 62 and 64 ~aving left-handed threads while
screw 63 has right-handed threads. Clutches 56-59,
~ ~57~
081076-BHP - 10 -
preferably made of plastic, are normally spring biased
out of engagement with their respectivo gears 52 55.
The gears and clutches have dogs or lugs which inter-
lock or mesh when engaged in order that gear rotation
will be transferred to the associated drive screw.
Attention i5 directed particularl~ to FIGURES 6-9 which
illustrate, in greater detail, the construction of
clutch 56 and the apparatus for controlling it. Of
course, since all of the clutches 56-59 are of similar
construction only one is shown in FIGURES 6-9 and the
explanation of its construction and operation applies
to all of the other clutches.
Note that clutch 56 and gear 52, as illustrated in
FIGURES 7-9, are shifted or rotated 90 from their
positions as shown in FIGURE 60 This is particularly
evident by observing the position of pin 50 which is
fixed to, and perpendicular to the axis of, drive screw
61. Pin 50 extends through the two slots 56b in clutch
56 and guides the movement of the clutch as it moves
between its engaged and disengaged positions. The
spring biasing o~ clutch 56 is accomplished by coil
sprin~ 65 which pushes t~e clutch to the left and out
of engagement with gear 52, thereby to separate the
mating surfaces. The two projecting lugs 52a on gear
52 (see particularl~ FIGURE 81 mesh with the two
projecting or raised lugs 56a on clutch 56 (see parti-
cularly FIGURE 9) when the clukch is moved to the right
and into its engaged position. Relatively light
springs may be used for the restoring springs 65. Each
spring 65 will ~e capable of disengaging or releasing
its associated clutch ~y exerting a force of only a few
ounces on the clutch. The manner in which this is
7~
081076-BHP - 11 -
accomplished will be described hereinafter.
Each of clutches 56 59 i5 actuated into engagement
with its associated gear by a respective one of four
solenoids 66-69 (see FIGURE 3) which actuate U-shaped
yokes 71-74, respectively. For reasons to be under-
stood, solenoid 66 may be called the "back solenoid",
solenoid 67 the "foot solenoid", solenoid 68 the "head
solenoid", and solenoid 69 may ~e called the "knee
solenoid". Each of yokes 71-74 is pivotally connected
to support pan 75 (mounted on frame 12~ and straddles
a respective one of drive screws 61-64 and abuts the
screw's clutch. Coil springs 76 bias the free ends of
yokes 71-74 so that minimal pressure is normally
applied to the clutches by the yokes. Actuation of
each yoke in response to energization of its associated
solenoid is achieved by means of linkages or rods 81-84
each of which connects a respective one of yokes 71-74
to a respective one of movable cores 66a-69a of
solenoids 66-69, respectively. This construction is
clearly illustrated in FIGURE 6.
When reversible motor 49 is rotating in one of its
two directions, thereby rotatins all of gears 52-55,
and a selected solenoid is energized, the yoke
associated with the solenoid ~ill be pulled to the
right, as viewed in the drawings, to actuate or move
its clutch into engagement with its associated one of
gears 52-55, thereupon causing rotation of the
associated drive screw in response to the gear ro-
t~tion. In shortt an~time motor 49 i5 energized, all
of gears 52-55 will he rotating and by energizing a
selected one or more of solenoid 66-69 a corresponding
selected one or more of drive screws 61-64 will be
7~
081076-BHP - 12 -
rotated. Of course, the rotational directions of the
drive screws will depend on the direction of motor 4~,
but ~ince that motor is revexsible it is possible to
rotate each of the screws 61-64 in either of its two
directions.
Since each clutch ;s normally held disengaged by
means of a relatively small restoring spring 65,
actuation of the clutch to engage the mating lug
surfaces may consequently be achieved by a relatively
small solenoid. The force produced by the solenoid
need only be slightly greater than the spring force in
order to overcome that spring force and shift the
clutch into its engaged position. The need for only a
small solenoid and clutch restoring spring to accom-
plish clutch actuation and de-actuation in a hospital
bed provides efficient and reliable operation, and
lowers the cost, power consumption and noise. In a
manner to be explained, such clutch operation is
achieved by unloading each clutch, that should be
disengaged or de-actuated, from any tangential forces
or torque that would otherwise tend to hold or "bind"
the mating lug surfaces locked together even after the
associated solenoid has been de-energized. To explain,
after a clutch has been engaged and the associated
adjusting mechanism is operated to obtain a desired bed
adjustment, the clutch will tend to remain in the
engaged position even after the motor stops rotating
and the assoc;ated solenoid is de-energiæed. This
occurs because the weight of all the apparatus con-
nected to the associated drive screw applies a torqueto the clutch whic~ holds or locks the mating lug
surfaces pressed together so that they cannot separate
and disengage. The ~riction ~etween the lugs on the
clutch and the lugs on the associated gear will be so
~5~
081076-BHP - 13 ~
great that, a very strong coil spring 65 would usually
be needed to move the clutch out of engagement~ In a
manner to be described, however, any torque or tan-
gential pressure on the clukch is momentarily removed
to decrease the friction ~etween the mating lug surfaces
to allow the clutch to move freely along the axis of
its associated drive screw under the ver~ small force
of its restoring spr;ng 65. Relatively little pressure
will be re~uired to push the clutch back to its dis-
engaged posi-tion. As will be seen, unloading of a
clutch from torque to eliminate the friction between
the lug surfaces, there~y to permit the clutch to slide
~ack to its released position, is accomplished by
momentarily reversing the direction of rotation of
hidirectional motor 49. This slight counterrotation
jogs the gear train sufficiently to take the forces off
of the clutch so that it can release.
The logic circuitry of FIGURES 18 and 19 may ~e
employed to control the energization of motor 49 and of
solenoids 66-~9, in accordance with the present in-
vention, to achieve actuation of drive screws 61-64 and
to position the bed as shown in FIGURES 14-17. The
logic circuitry may ~e controlled by switches that are
operated by switch actuators mounted somewhere on the
bed or in a patient hand control device that may be
held by the patient and/or removably attached to the
bed, such as to one of the ~ed's restraining sides or
side guards. Among other prior disclosures, one such
hand control unit for remotely controlling the cir-
~uitry for a bed is s~own in United States Patent3,921,Q48, issued Novem~er 18, 1975 to genneth W.
Padgitt~ Switch actuators should be conveniently
~5'7~
081076-BHP - 14 -
accessible for any operator ~be it the patient~ nurse,
doctor, attendant, ~tc.) to control the head, foot,
back and knee adjustments or functions. In other
words, the operator-controlled switches should control
the energization of solenoids 66-69, while at the same
time controlling the direction of motor rotation. As
will be appreciated when the cîrcuitry of FIGURES 18
and 19 is discussed, the patient operated controls are
included in a hand control unit that may be held by the
la patient and is cable connected to the rest of the
circuitry.
The four manually operated switch ac~uators 86-89
(see FIGURE 2), mounted at the foot end of upper frame
12, are provided for the convenience of the doctor,
nurse or attendant and control switches in FIGURE 18.
Some of these switches should not be accessible to the
patient. Most of the logic circuitry of FIGURES 18
and 19 may be mounted on a printed circuit board which
is supported on the upper frame in the general area
2~ indicated b~ the reference num~er 60 in FIGURE 3.
The rotational motion of screws 61-54 is converted
to linear motion by the ~our drive mechanisms 91-94,
respectively, the movements of ~hich cause adjustment
o~ the ~ed. Attention is directed to FIGURES 10-13
which sho~ in detail the construction of drive me-
chanism 91. Of course, the other three drive mechanisms
92-94 are o similar construction and operate in
similar manner, so only drive mechanism 91 will be
described. It includes a tw~-piece brake housing 121
surrounding drive scre~ 61. Housing piece 122 is
preferably made of an înjection molded thermopla~tic
75~
081076-BHP - 15 -
resin and is provided with shoulders 123 and 124, an
opening 125 and a lip 126. The other housing piece
128 is preferably made of metal and has shoulders 129
and 130 and an opening 131 having a radially extending~
tapered brake surface 132 thereon. A brake nut 133 is
contained in the openings 125 and 131 of the housing
pieces 122, 128, respectively. Brake nut 133 thread-
edly engages the drive screw 61 and is adapted to be
driven thereby. The brake nut contains a radially
extending~ tapered hrake surface 1340 A spring in the
form of a thrust washer 135 is retained within the lip
126 and yieldingly urges the ~rake nut 133 to the left
as seen in FIGURE 11 to force the brake surfaces 132
and 134 into engagement. A stop pin 136 is secured to
one end of the brake nut 133 and a stop surface 137 is
provided on the other end of the nut. The two pieces
122 and 128 of housing 121 are secured together by a
pair of sleeves 138 and 133 and a pair of cotter pins
141 and 142. The linkage or bracket 96 is pivotally
coupled to the brake housing 121 by the sle~ves 138 and
139 and the cotter pins 141 and 142. Stop collar 143,
containing a stop pin 144, surrounds and is fixedly
secured to drive scre~ 61 by an allen screw 145. A
second stop collar 146, containing a stop pin 147, is
similarly fixedly secured to the drive screw 148.
As drive screw 61 rotates, the brake nut 133 and
housing 121 ~ill travel linearl~ and axially along the
screw. $top collars 143 and 146 are provided on drive
screw 61 to define the limits of travel of drive
mechanism 91, the collars rotating ~ith the drive
screw. When the drive mechanism 91 travels along the
~ ~S~5~
0~1076-BHP - 16 -
drive screw 61 to a limit of travel established by one
of the collars 143, 146, the stop 136 or the stop 137
of the nut 133 will enga~e one of the pins 144, 147 of
the collars and the linear travel of the drive mechanism
will be terminated even though the drive screw 61
continues to rotate. Assume, for example, that drive
mechanism 91 has traveled to the left in FIGURES 10 and
11 until pin 144 on collar 143 engages stop surface
137. When that occurs, pin 144 will rotate the brake
nut 133 within housing 121 to overcome the frictional
engagement of the ~rake surfaces 132 and 134, the nut
thereby free-wheeling, as drive screw 61 rotates~ The
housing 121, and consequently the drive mechanism 91,
therefore remain axially stationary on the rotating
drive screw 61. Thus, continued rotation of drive
screw 61 after its drive mechanism 91 has reached a
limit of travel results in no axial movement of the
drive mechanism.
Of course, each of the other three drive screws
62-6~ has a pair of similar stop collars fixedly
secured thereto to define the limits of travel of the
associated drive mechanism. Arresting the axial travel
of each drive mechanism when a limit is reached, even
though the associated drive screw may still be ro-
tating, precludes the need for electrical switches tode-energize the motor 49 when the various bed adjust-
ments reach their extreme positions~ The eight stop
collars (like collars 143 and 146) are not shown in
FIGURES 1-6 to avoid unduly encumbering the drawings.
Bracket 96, which is pivotally coupled to drive
mechanism 91, is rigidly affixed to a tube 97 which in
081076-BHP - 17 -
turn is pivotally connected to the free ends of lever
arms 43. When drive screw 61 is rotat~d in the di-
rection which causes drive mechanism 91 to move
linearly to the left (,as viewed in the drawings), arms
43 and torque tube 39 will be rotated in a clockwise
direction and back support section 31 will ~e tilted
upward. Opposite rotation of drive screw 61 will lower
section 31 rom its tilted position. Screw 61 may thus
be referred to as the "back drive screw". In similar
fashion, drive mechanism 94 pivotally connects to
linkage or bracket lQl which is rigidly secured to one
end of a tube 102. The other end i5 pivotally coupled
to the free ends of lever arms 46 in order that ro-
tation of drive screw 54 (which may be called the "knee
drive screw"~ will rotate tube 44 to raise or lower the
knee support sections 33 and 34.
Movement of drive mechanism 92 results in actuation
of foot adjusting mechanism 18 to raise or lower the
foot end of upper frame 12, depending on the rotational
direction of drive screw 62, referred to as the "foot
drive screw". More specifically, the brake housing of
drive mechanism 92 is pivotally coupled to a bracket or
linkage 104 which rigidly connects to one end of a tube
105, the other end of which pivotally connects to lever
arms 18c. When foot drive screw 62 is rotated in the
direction to move drive mechanism 92, and consequently
tube 105, to the left in the drawings, lever arms 18c
will be rotated in a counterclockwise direction causing
the foot end of frame 12 to raise. Conversely, opposite
direction rotation of screw 62 moves the drive mechanism
to the xight and this results in clockwise rotation of
081076-BHP - 18 -
adjusting mechanism 18 and lowerin~ of the upper
frame's foot endO Motor 49, gears 51, 52 and 53,
clutch 57, drive screw 62 and drive mechanism ~2 may
therefore be considered the "foot drive means" for
actuating the foot adjusting mechanism 18 to adjust the
height of the upper frame's foot end. When the foot
end is lowered to its lowermost level, drive mechanism
~2 enyages and pushes rigid wire or rod 149 to the
right (see FIGIJRE 3~ against the force of biasing coil
spring 151 and actuates switch 152. Rod 149, spring
151 and switch 152 are supported ~y pan 75. Switch 152
is called the "foot low limit switch" and its function
will be described la~er in connection with the logic
circuitry in FIGURES 18 and l9o Briefly, switch 152 is
normally closed (as shown in FIGURE 18) wh~n the foot
end of frame 12 is at any level other than its lower-
most level. When the foot end is dropped to its
lowermost limit, drive r.~echanism 92 pushes rod 149 to
the right in FIGURE 3 and this causes switch 152 to
open. Of course, when the oot end is off of or above
its low limit and drive mechanism 92 has moved to the
left and away from engagement with rod 149, coil spring
151 will restore the rod to its noxmal position as
shown in FIGURE 3 and switch 152 will return to its
closed position.
The head adjusting mechanism 16 functions in
similar manner to effect independent raisin~ and
lowering of the head end of frame 12~ Drive mechanism
93 is pivotally coupled to linkage or bracket 107 which
rigidly attaches to one end of a tuhe 108, the other
end being pivotally coupled to the free ends of lever
~ ~57~
081076-BHP - 19 -
arms 16c. When drive screw 63 (called the "head drive
screw"~ rotates in the direction required to move dxive
mechanism 93 to the left, tube 108 will cause counter-
clockwise rotation of adjusting mechanism 16 with
resultant raising of the head end of frame 12. On the
other hand, opposite direction rotation of head drive
screw 63 causes drive mechanism 93 to travel to the
xigh.t, thereby effec~ing clockwise rotation of ad-
justing mechanism 16 and lowering of the frame's head
end. Motor 49, gears 51, 52, 53, and 54, clutch 58,
drive screw 63 and drive mechanism 93 may t~us be
called the "head drive means" for actuating the head
adjusting mechanism 16 to adjust the height of the
upper frame's head end. When the head end of -frame 12
is lowered to its lowermost level, drive mechanism 93
engages and pushes rigid wire or rod 153 to the right
(FIGURE 3) against the biasing force of coil spring 154
and actuates switch 155, the "head low limit switch".
Rod 153, spring 154 and switch 155 are supported by pan
Z0 751 ~witch. 155 is also closed ~see FIGURE 18) when the
head end is off of or above its low limit and drive
mechanism 93 is out of engagement with rod 153. When
the head end is all the way down and rod 153 is pushed
to the right, normally-closed switch 155 will open.
It will now be apparent that since each of the
adjusting mechanism~ 16 and 18 and its driving apparatus
is entirel~ independent of the oth.er adjusting me-
chanism and its driving apparatus, the head and foot
ends of upper frame 12 may each ~e positioned at any
selected level or height, as a consequence of which
7~
081076-BHP 20 -
frame 12 may be made horizontal or tilted and may be
established at any desired level. This flexibility in
operation is clearly illustrated in FIGURES 14-17.
FIGURE 14 depicts the operation of the bed when upper
frame 12 is horizontal and both of drive screws 62 and
63 are rotating simultaneously or collectively, thereby
elevating and lowering the frame in its horizontal
position. When the foot drive screw 62 i5 not rotated
but the head dri~e screw 63 is, the head end of frame
12 ma~ be raised, as shown in FIGURE 15, to establish
the bed in the reverse trendelen~urg position. FIGURE
16 shows the action when the foot end of frame 12
remains at the same heigh~ as in FIGURE 15 and the head
drive screw 63 is rotated in the opposite direction to
lower the uppex frame's head end to place the bed in
the trendelenburg position. FIGURE 17 illustrates the
operation when, starting from the tilted position of
FIGURE 16, drive screws 62 and 63 are rotated simul-
taneously, thereby elevating the entirety of frame 12
while it is tilted.
Hence, frame 12 can be tilted at any height and
the height may be changed while at any tilt angle.
Also the tilt angle may be changed by raising or lowering
either end of frame 12 thus obtaining a desired tilt
angle without chanying the height of one end. Of
course t the head and foot adjusting mechanisms are
independently operable even when the back support
section 31 and the knee support sections 33 and 34 are
tilted relative to seat section 32. As will be made
apparent, the logic circu;try of FIGURES 18 and 1~, in
75~
081076-BHP - 21 -
reponse to a command issued by the operator, controls
the operation of the head and foot drive means to tilt
the upper frame directly to either a trendelenburg
position or to a reverse trendelen~urg position,
regardless of its position at the time the command is
issued. Moreover, since all four drive screws 61-64
are independently rotatable and may be rotated in-
dividually, collectively or in any combination, several
different bed adjustments may be made simultaneously9
therehy saving considerable time. For example, ba~k
support section 31 may be raised at the same time that
knee support sections 33 and 34 are being raised. If
desired, the bed he;ght may also be changed while the
back and knee sections are being adjusted. As another
example, sections 31, 33 and 34 may all be lowered
simultaneously and made coplanar while at the same time
t~e mattress support 14 is being tilted to the tren-
delenburg position. And all of this concurrent action
is produced by a single common drive, namely reversible
motor 49.
Of course, by the proper selection of the thread
directions of drive screw 61 and 64, back support
section 31 and knee support sections 33 and 34 may be
adjusted in a desired direction at the same time that
upper frame 12 is moving in a given predetermined
direction. Yor example, it may be desirable to lower
all of sections 31, 33 and 34 to their horizontal
positions (shown in FIGURE l~ as frame 12 is simul-
taneousl~ being raised. This would expedite the
establishment of the bed in the preferred patient
examination position. In the disclosed embodiment of
081076-BHP - 22 -
the invention, however, the thread directions o the
drive screws are chosen so that all of the adjusting
mechanisms (if simultaneously operated) will go up at
the same time and down at the same time. In other
~ords, if the motor is running in one direction and all
of the adjusting mechanisms are turned on at the same
time, the ~ack and knee support sections and the head
and foot ends of the ~ed will all go up or raise at the
same time. Conversely, when the motor is rotated in
the other direction and all of the adjus~ing mechanisms
are operated, the back and knee support sections and
the head and foot ends ~ill go down or descend simul-
taneously~ Such an arrangement renders it easier for
the patient to adjust the bed. It is easier for the
patient to remember that everything goes up at the same
time, if all of the patient-controlled switches are
actuated, and everything goes down at the same time.
Since each of the two motor directions is associated
with a specific adjusting direction, for convenience
the motor directions will ~e referred to as the "up
direction" and the "down direction"~
In the event oE a power failure, thereby pre-
cluding the operation of reversible motor 49 and solenoid
66-69, linkages in the form of relatively rigid wires
or rods 111-114 are provided to allow the doctor, nurse
or attendant ko mechanically depress the cores of the
solenoids from the oot end o the bed. This i5
clearly seen in FIGURE 6~ By pulling linkage 111 to
the right in FIGURE 6, core 66a of solenoid 66 is
pushed to the right and into the solenoid winding in
~3575~
081076-BHP - 23 -
the same manner as if the solenoid had been energized
electrically. Gears 52-55 may then be driven by
inserting a hand crank (not shown) through opening 116,
at the foot end of frame 12 ~see FIGURES 2 and 3), and
then through tube 117, moun~ed on frame 12, for engage-
ment with shaft 118 w~ich is coupled to driving gear
51. By hand cranking shaft 118, gear 51 may be rotated
to in turn rotate gears 52-55 in the same fashion as if
motor 49 was rotating. Hence, by manipulating selected
ones of linkages 111-114 and by hand cranking shaft 118
all of the bed adjustments ma~ ~e made.
It should ~e appreciated that the high-low lifting
mechanisms may take diffexent forms. While a parallelo-
gram lifting system is employed in the illustrated
embodiment for the high-low adjustment, other systems,
such as a trapezoidal lifting system, could be used.
In the illustrated parallelogram lift, the head and
foot drive mechanisms travel in the same linear di-
rection when the upper frame is beir.g rais~d or lowered.
Wîth a trapezoidal lift, the two drive mechanisms would
be moving in opposite directions when the upper frame
is being elevated or lowered~
Consideration will now be given to the logic
circuitry t schematically shown in FIGURES 18 and 19,
for controlling solenvids 66-69 and motor 49 in accord-
ance with the present invention. Three-pron~ed plug
157 is adapted to plug into a conventional grounded
wall outlet, in the hospital room ~here the disclosed
adjustable hospîtal ~ed is located, to provide across
3Q line conductors Ll and L2 a source of single-phase a-c
line voltage varying in sinusoidal fashion at a fre-
quency of 60 cycles per second or hertz and having a
' .;
~7~
081076-BHP - 24 -
magnitude of approximatel~ 120 volts RMS. Line con-
ductor Ll will connect to the socalled "Hot" terminal
of the wall outlet, while line conductor L2 couples to
the "Neutral" terminal. One end of conductor 158
connects, through plug 157 and the wall outlet, to the
building ground or eart~ ground, as is also the case
with the neutral or L2 conductor. The other end of
conductor 158 is connected to the ~ed's upper frame 12,
which of course is preferably constructed of metal and
therefore conductive, in order to ground the frame to
earth ground.
T~e 120 volts a-c line voltage across conductors
Ll and L2 is isolated and reduced by a step-down trans-
foxmer 159 having a 6:1 turns ratio, rectified by a
full-wave rectifier bridge 161, filtered by filter
capacitors 162, and regulated by a voltage regulator
163 to provide regulated positive d-c voltage (labeled
V+) of a magnitude appropriate for operating all of the
logic circuits and transistors in ~he control system of
2Q FIGURES 18 and 19. Preferably, that d-c voltage will
be around + 12 volts and the ground plane of reference
potential or circuit common, to which the lower terminals
of the capacitors 162 are connected, will be zero
volts. The circuit common or ground is not connected
to the bed ~rame 12. It is an isolated ground on the
printed circuit board and cannot be engaged by the
patient or other operator when operating the bed's
adjusting apparatus~ Of coursel all of the terminals
in FIGURES 18 and 19 marked V-~ are tied or connected to
the positive output oF the d-c power supply 161-163.
The relatively high voltage level V+ (or -~ 12 volts)
constitutes logic 1 in the logic circuitry and the zero
ground voltage represents logic 0.
~5'7~
081076-BHP - 25 -
Motor 49 takes the form of a t~o-phase reversible
a-c induction motor of conventional construction
having, in delta connection, a pair of field windin~s
164 and 165 and a phase shift capacitor 166. When 12Q
volts a-c is applied directl~ across field winding 164,
that same voltage, except almost 90 phase shifted,
will appear across winding 165 and the motor will
rotate in its down direction. As will be fully under-
stood~ this means that any of the four adjusting
mechanisms (foot, head, back and knee~ t~a~ is being
driven ~y the motor will cause its adjusta~le apparatus
to descend or lo~er. In other words, when motor 49 is
running in its down direction, the head and foot ends
of ~rame 12, back support 31 and knee supports 33 and
34 ma~ all be lowered simultaneously or individually.
Convexsely, when 120 volts a-c is applied directly to
winding 165 it is phase shifted close to 90 by capa-
citor 166 and applied across winding 164, with the
result that the motor rotates in the opposite or up
2n direction to cause the driven adjusting mechanisms to
elevate or raise their associated adjustable appara~us.
~ pair of solid state switches, in the form of
triacs 168 and 169, are provided to apply the a-¢ line
voltage, across line conductors Ll and L2, directly to
either field winding 164 or field winding 165. As is
well kno~l, in the absence of any applied voltages a
triac assumes its off condition in which a very high
impedance exists between its main terminals Tl and T2
to effectivel~ constitute an open switch. When a
voltage o either polarity ;s impressed across the main
terminals, the triac remains non conductive until gate
~57S~
081076-BHP - 26 -
or triggering current of appropriate magnitude is
translated between the gate terminal G and the main
terminal Tl in either direction, whereupon the triac
turns on and permits current flow between terminals T
and T2 in response to the voltage applied thereto and
in the direction determined by the voltage's polarity.
Once the triac is rendered conductive, a very low
impedance is presented between its main terminals so
that it essentially functions as a closed switch, as a
lQ consequence of which the full a-c line voltage will be
applied directly to either winding 164 or 155 depending
on which triac is turned on. As is common wi~h triacs,
conduction between terminals Tl and T2 continue even
though the gate current may be terminated so long as
there is a potential difference across the main terminals.
When the Tl - T2 voltage is reduced to zero, the triac
therefor returns to its off state. Thereafter, when
the voltage across the main terminals is increased from
zero, conduction will not occur until the triac is
regated, namely until gate current again flows between
gate G and terminal Tl.
Since a triac automatically switches to its off
condition each time the alternating vol-tage appeariny
across its main terminals crosses its a-c axis, at
which time a zero potential difference exists between
terminals Tl and T2, gate current must be supplied to
the gate terminal at some instant following the be-
ginning of each half cycle or alternatiQn if the a-c
line voltage, across conductors Ll and L2, is to be
applied to the motor for at least a portion of each
half cycle. In other words, at the end of each half
7~
081076-BHP - 27 -
cycle of one polarity, the triac which is to be effect-
ive assumes its non-conductive state. The polarity of
the alternating voltage appearing across its main
terminals then changes at the start of the next half
cycle, thereby requiring retriggering at the gate
before the triac turns on and Tl - T2 current flow
takes place. As will be made apparent, maximum gate
current is supplied to the effective one of triacs 168
and 169 as its Tl - T2 voltage goes through zero
amplitude so that immediate regating occuxs at the very
beginning of the next half cycle.
Triacs 168 and 169 are controlled by photo couplers
171 and 172. Normally, transistors 181 and 182 are
turned off and no d-c voltage is applied to the LED's
(l;ght emitting diodes) 173 and 174 of photo couplers
171 and 172, respectively, and each of photo resistors
175 and 176 will exhibit a high resistance. Under
those conditions, insufficient gate current will flow
to the gate terminals of triacs 168 and 169 to turn
them on. With both triacs turned off, circuit junctions
177 and 178 in motor 4~ will be at the same potential~
namely 120 volts a-c with respect to line conductor Ll
Assume now t~at transistor 181 is made conductive
~y applying logic 1, or + 1~ volts d-c, to the tran-
sistor's base, thereby groundin~ the cathode of LED 173and effecting energization thereof from d-c source V~.
The illumination of LED 173 causes the resistance of
photo resistor 175 to drop to the extent necessary to
supply gate current ~rom junction 178, and via the
cross-coupling circuit including current-limiting
resistor 183, capacitor 184 and photo res;stor 175, to
the gate terminal of triac 168 to render the triac
081076-BHP - 2B -
conductive. Capacitor 166 initially introduces re~
latively little phase shift, so during the start-up
period the gating voltage at triac 168 will be roughly
in phase with the Tl - T2 voltage and the triac will
conduct during most of each half cycle. Hence, circuit
junction 177 will be intermittently connected to line
conductor Ll through triac 168 and the full 120 volts
a-c~ appearing across conductors Ll and L2, will be
applied directly across field winding 164 to effect
motor rotation in the down direction. As the motor
rotates, the shifted phase voltage across winding 165
effectively adds to the voltage across winding 164 with
the result that a voltage of about 240 volts RMS is
produced between circuit junction 178 and line con-
ductor Ll. Since there is practically no voltage dropfrom circuit junction 177 and through triac 168 to
conductors Ll while the motor rotates~ the full 240
volts appears across phase shift capacitor 166.
The gating voltage at triac 168 therefore doubles
2a in magnitude and shifts phase after motor 49 begins
rotation. Capacitor 184 provides voltage dropping
without power dissipation in order to maintain the gating
voltage only as hi~h as necessary to control the triac.
A major advantage, however, of using the phase shifted
voltage at junction 178 to gate triac 168 is that the
gatin~ voltage will be approximately 90 out-of-phase
with respect to the Tl - T~ voltage. Most of the 90
phase shift is attributable to capacitor 166 but if its
capacitance is insuffîcient then the capacitance of
capacitor 184 ma~ be adjusted so that the two capacitors
together will result in a 90 phase shift. With such a
7Si~
08107~-BHP - 29 -
a phase relationshi~, the gate current will always be
at a maximum when the voltage appearing across terminals
Tl and T2 of triac 168 completes one half cycle and
passes through zero amplitude to begin the next
opposite-polarity half cycle. Havlng high gate current
at the start of a half cycle causes the triac to be
gated on immediatel~ so that field winding 164 is
essentially continuously connected across line con-
ductors Ll and L2. In effect, it may be likened to
0 gating the triac with d-c voltage. With such con-
tinuous operation of tne triac~ the gating is noise-
free and no radio frequency interference is generated.
When logic 1 is subsequently removed from the base
of transistor 181, the energizing circuit for photo
coupler 171 is broken and triac 168 returns to its off
condition in which a very high impedance exists between
main term;nals Tl and T2, whereupon the a-c line
voltage is removed from winding 164 and motor 49 stops
its rotation.
Rotation of motor 49 in the opposite or up di-
rection is achieved in similar manner. By applying
logic 1 to the base of transistor 182, the energizing
circuit for LED 174 of photo coupler 172 is completed
and this causes the resistance of photo resistor 176 to
lower sufficiently to cause gate current to flow from
circuit junction 177, and over thP cross-coupling
circuit including current-limiting resistor 185,
capacitor 185 and photo resistor 176, to the gate
terminal of triac 169. The triac is turned on in
response to the gate current, as a consequence of which
the 120 volts a-c line voltage is supplied to winding
~s~
081076-BHP - 30 -
165 to caus~ the rnotor to rotate in the up direction.
Once the motor begins to rotate, the voltage at
junction 177 doubles in magnitude and becomes phase
displaced by about 90 relative to the Tl - T2 voltage
appearing at triac 169 so that the triac will be re-
triggered at the very beginning of each half cycle. By
then switching the base voltage of transistor 182 from
logic 1 to logic 0 the transistor turns off and the
energizing circuit for photo coupler 172 opens, there~y
turning off triac 169 to disconnect winding 165 from
the line voltage source L1 - L2.
The previously discussed switch actuators 86, 87,
88 and 89, mounted at the foot end of the bed, are
spring biased and control the normally-open switches
86a, 87a, 88a and 89a, respectively, shown on the left
in FIGURE 18. These switches are therefore of the
momentary contact type which requires the operator
(namely, the doctor, nurse or attendant in the case of
switches 86a - 89a) to maintain continuous pressure on
a selected spring-biased switch actuator in order to
close the associated switch and to hold it closed.
Switch 86a is closed when the operator wishes to raise
both the head and foot ends o~ upper frame 12, and
switch 87a i5 closed to lower the frame. Switch 88a is
closed when it is desired to establish the bed in the
reverse trendelenburg or drainage position (head end
up, foot end down~, and switch 89a is closed when the
bPd is to be adjusted to the trendelenburg or shock
position (head end down, foot end upl. As will be
appreciated, a trendelenbur~ command is issued by the
operator merely ~y closing switc~ 89a~ while a reverse
trendelenburg command is issued by closing switch 88a.
7~i~
081076-BHP - 31 ~
The three switches 187, 188 and 189 are included
in the patient hand control 190 which is cable connected
to the rest of the circuitry in FIGURES 18 and 19 and
is adapted to be hand held by the patient occupying the
bed in order to remotel~ control the various bed
adjustments merely by selectively depressing different
spring-biased switch actuators or push buttons, the
switches being of the momentary-contact type and being
normally open. Preferably, the hospital bed is provided
wi~h a holder ~for example, on a bed restraining side)
for holding control 190 when it is not being operated
hy the patient. Of course, ~hile hand control 190 is
provided primarily for the convenience of the patient,
it may be operated by some other operator, such as a
doctor, nurse, attendant, etc., to control the same bed
adjustments or functions that are controllable by the
patient. As indicated by the labels associated with
the switches in the patient hand control 190 illustxated
in FIGURE 18, switch 187 may be actuated, by a knee-up
switch actuator, to its up position to raise the knee
support sections 33 and 34, and by a knee-down switch
actuator to actuate switch 187 to its down position to
lower the knee support sections. Similarly, by de-
pressing a back-up ac-tuator switch 188 may be actuated
to its up position to elevate back support section 31,
and by depressing a back-down actuator switch 183 may
be established in its down position to drop the back
support section 31. Like~ise, the bed switch 189 is
actuabl~ by switch actuators to its up position to
simultaneously raise both the head and foot ends of
upper frame 12, and to its down position to lower the
081076-BHP - 32 -
head and foot ends at the same time.
Each of the NAND gates 191-206 produces a logic 1
output (namely, ~ 12 volts d-c) if any of its two
inputs is logic 0 or ~ero volts. W:ith at least one
logic 0 inpu-t, the output will be logic 1. On the
other hand, if both inputs are logic 1, a logic Q
output will be provided. Each of NOR gates 207-219
produces a logic 0 output if at least one of its two
inputs is logic 1. Otherwise, with logic 0 at ~oth
1~ inputs a logic 1 output is developed~ Each of the
exclusive OR gates 220l 221, and 222 produces a logic 1
output if one of its two inputs is logic 1 while its
other input i5 logic 0. In other words, when either
input is logic 1, but not both, the output will be
1~ logic lo If both inputs are logic 0 or if both inputs
are logic 1, the output will be logic 0.
Three pairs of NAND gates (namely, 193 and 194,
197 and 198, and 201 and 202) are combined in con-
ventional fashion to provide three R-S flip-flops, which
2Q serve as memory devices since each flip-flop holds the
condition or state in which it is established. When an
input pulse actuates a flip-flop to one of its two
conditions, the flip-flop will remain in that condition
after the input pulse terminates. Each of the three R-
S flip flops has a ~ingle output and two inputs, an Ror reset input and an S or set input. The single
output is usually called the Q output of an R-S flip-
flop. The Q out~ut (the 180 counterpart of the Q
outputl is not used in the circuitry o FIGURES 18 and
30 l9o The reset input of each flip-flop has greater
7~
081076-BHP - 33 -
control over the operation of the ~lip-flop than the
set input, in that the application of logic 0 to the
reset input triggers the flip-flop to its reset con-
dition to produce a logic 1 output regardless of the
signal level at the set input. Logic 0 on the reset
input overrides whatever is applied to the set input.
On the other hand, if the reset or R input is esta-
~lished at logic 1, the application of logic 0 to the
set or S input actuates the R-S flip-flop to its set
condition, thereby producing a logic 0 output. If
logic 1 is applied to ~oth of the inputs, nothing will
happen and the flip-flop will remain in the condition
to which it was previously actuated by a logic 0 on one
of the inputs. In short, logic 0 on the R input always
~enerates a logic 1 output, while logic 0 on the S
input produces a logic 0 output but only if the R input
is logic 1.
There are five monostable or one-shot multivi-
brators provided in FIGURE 19 by NOR gates 212-217,
NAND gates 204-206, inverter 223, resistors 224-228 and
capacitors 231~235. More particularly, gate 212,
inverter 223, resistor 224 and capacitor 231 form a
single one-shot multivibrator, the resistor and capa-
citor detexmining the time interval that the multi-
vibrator will remain in its abnormal or unstable
condition once it is triggered to that condition, after
which it will automatically return to its normal stable
operating condition. The one-shot multivibrator
normally provides logic Q at its output (namely, the
output of inverter 223~ but when actuated, ~y the
application to the upper input of gate 212 of a signal
excursion or transition going ~rom logic 0 to logic 1,
S7~L
081076-B~IP - 34 -
the multivibrator assumes its abnormal condition for a
predetermined interval to produce a logic 1 output~ ~t
the conclusion of the interval, the output of the
multivibrator re~urns to logic 0. Hence, when the
signal level at the upper input of gate 212 switches
from logic 0 to logic 1, the multivibrator produces a
positive-going pulse having a pulse width detexmined by
resistor 224 and capacitor 231. The pulse width is not
critical. Preferably, it is estahlished in the range
from 40 to 150 milliseconds~
Gates 204, 213 and 214 and the associated resistors
and capacitors form two one-shot multivibrators for
producing, when triggered, positive-going pulses of the
same width as the pulses produced by inverter 223.
Hence, when the upper input of gate 213 switches from
logic 0 to logic 1, the output of gate 204 developes a
positive-going pulse. Likewise, when ~he signal level
at the lower input of gate 214 changes from logic 0 to
logic 1, the output of gate 204 switches from logic 0
ko logic 1 and then back to logic 0 to produce a
positive-going pulse.
Gates 205, 215 and 216, resistors 227 and 228 and
capacitors 234 and 235 also provide dual one-shot
multivibrators that function in the same manner as
discussed above, producing positive-going pulses at the
output of gate 205 whenever eithex the upper input of
gate 215 or the lower input of gate 216 goes from logic
0 to logic 1. Suc~ positive-~oing pulses will also
have the same pulse width as those devloped by inverter
223 and by gate 204.
3 ~57~
081076-BHP - 35 -
Consideration will now be giv~n to the operation
of the lo~ic circuitry when power is initially applied.
It will be assumed that all of the switches 187-189 and
86a-89a are open as shown in FIGURE 18. It will alsD
be assumed tha~ ~he bed is at some intermediate position
and not fully down when plug 157 is inserted in the
wall outlet. The head lo~ limit switch 155 and the
foot low limit switch 152 will therefore both be closed
as shown in FIGURE 18, ~hereby applying ground or zero
volts ~namely logic 0~ to both inputs of NAND ~ate 195.
This produces logic 1 at the output of gate 195 for
application to the lower input of gate 192 and to the
base of transistor 236, the collector of which connects,
via conductor 237 and lamp 238, to the upper terminal
of the secondar~ winding of transformer 159. Tran-
sistor 236 will therefore conduct and lamp 238 will
illuminate in response to a pulsating d-c voltage
provided by half wave rectified a-c. The energization
of lamp 238, which is preferably mounted at the foot
2a end of the bed, presents a signal to the doctor, nurse,
etc., that the bed is not full down, namely not in its
lowermost position. Usually, hospital beds are lowered
at night, so a signal light is helpful for a nurse to
spot the beds that are not all the way down.
BeEore power is applied, capacitor 239 is un-
charyed, diode 241 providing a discharge path. At the
instant that d-c voltage V+ is developed, the upper or
ungrounded side of capacitor 23~ will be at zero volts,
thereby appl~ing logîc 0 to the upper input of NAND
gate 192. This produces a logic 1 at the gate's output
which is converted to logic 0 by inverter ~42. NAND
gate 191 therefore generates a logic 1 which is con-
verted to logic 0 ~y inverter 243. As a consequence,
flip-flop 193, 194 receives logic 0 on its reset or R
~s~
081076-BHP - 36 -
input which triggers the flip-flop to its reset con-
dition to produce a logic 1 output. Inverter 244
converts this output to logic 0 for application to the
base of transistor 245, thereby maintaining the tran-
sistor in its off condition. ~fter flip-flop 193, 194
has been reset or cleared in response to the initial
application of voltage V+, capacitor 239 will charge
through resistors 246 and 247 to voltage V+. Thus,
when capacitor 23g is fully charged the upper input of
gate 192 will be established and held at loyic 1.
Flip-flop 193, 194 willr however, remain in its reset
condition.
With switches 88a and 89a open, the lower inputs
of NOR gates 207, 208, 209 and 211 will all be at logic
1, as a result of which the outputs of ~he gates will
be established at logic 0 and none of transistors 248-
252 will conduct. Conductoxs 253-256, which receive
logic 1 via the LED's of photo couplers 257-260, res-
pectively, will therefore be connected to conductors
261-264, respectively, to apply logic 1 to the inputs
of ~our of the five one-shot multivibrators. This will
have no effect, howeverl since both the "down bus" and
the "up bus" will be at logic 1, exclusive OR gate 220
thereby producing a logic 0 output which is applied
over conductor 265 and converted by inverter 266 to a
logic 1 signal level for application to the lower
inputs of NOR gates 218 and 219. Logic 0 outputs will
therefore be developed by the ~ates for application to
the bas~s of transistors 181 and 182, thereby main-
taining the transîstors non~conductive. Hence, when
power is initially applied to the ~ed and none of the
operator-controlled switches are actuated, solenoids
66-69 and motor 49 will not be energized.
081076-BHP - 37 ~
In operation of the logic circuitry, assume that
the patient, or some other operator, depresses the
knee~up switch actuator to close switch 187 in the up
direction. The cathodes of diodes ~67 and 268 will
thus become grounded to place logic 0 on conductors 256
and 264 and on the up ~us. Tl~e LED of photo coupler
260 illuminates and lowers the resiskance of the
associated photo resistor sufficiently to gate the
tr;ac 275 into conduction so that the a-c line voltage
across line conductors Ll and L2 will be rectified by
full wave rec~ifier bridge 276 to provide d-c voltage
for energizing knee solenoid 63. Clutch 59 therefore
engages in order to couple motor 49 to the knee ad-
justing mechanism.
In the meantime, the logic 0 on the up bus is
applied to the upper input of exclusive OR gate 220,
the lower input of which is established at logic 1 by
the down bus. Logic 0 on the up bus is also conveyed
over conductor 269 to the lower input of exclusive OR
gate 222. Not~ that the upper input of exclusive OR
gate 221 will be established at logic 1, received via
conductor 271 from the down bus~ The logic 0 on con-
ductor 269 and applied to gate 222 could be used to
turn transistor 182 on immediately and to command motor
49 to run in the up direction. However, the motor will
first be rotated momentarily in the opposi~e or down
direction in order to ensure that the motor ~ill be
disengaged from all except the selected knee adjusting
mechanism. In this wa~, if one of the othe.r adjust.ing
3a mechanisms, say the back adjusting mechanism, had been
previously actuated ~ut it5 clutch did no release or
disenga~e at the end of the actuat;on, thereby locking
~s~
081076-BHP - 38 -
the back adju~ting mechanism to the motor, then b~
initially driving the motor momentarily in the di-
rection opposite to the selected desired direction the
clutch for the back adjust.ing mechanism will be un-
loaded, permitting it to slide back to its disengagedposition under the force of its restoring spring.
I'o explain how this momentary motor reversal
occurs, since gate 220 will receive different Logic
levels on its two inputs when the up ~us is grounded by
1~ knee switch 187, t~e output of gate 22Q will change
from logic 0 to logic 1. The positive-going signal
transition is applied to the upper input of gate 212 to
trigger the one-shot multivibrator 212, 223, 224, 231,
thereby producing a positive-going pulse which is
converted by inverter 272 to a negative-going pulse for
application to the upper input of NAND gate 206. That
input therefore switches from logic 1 to logic 0 and
then back to log;c 1, as a result of which the output
of gate 206 produces a positive-going pulse, switching
from logic 0 to logic 1 and then back to logic 0.
Hence, for a relatively short interval (40-150 milli-
seconds~. the output of gate 206, and consequently the
common input of gates 221 and 222, will be at logic 1.
During that time both inputs of gate 221 and the upper
input of gate 222 will be at logic 1, while the lower
input of gate 222 will be estabished at logic 0. As a
result, the output of gate 221 and the upper input of
NOR gate 218 become lo~ic n 7 while the output of gate
222 and the upper input of ~ate 219 become logic 1.
Mean~hile, the common input of gates 218 and 219 will
receive logic a from inverter 266. With both inputs of
gate 218 at logic 0 a logic 1 output is developed for
~5'75~
081076-BHP - 39 -
application ~o the base of transistor 1~1 to turn ~hat
transi~tor on, there~y energizing motor 4~ and running
it in the down direction. During that same short
interval, the different logic levels at the inputs of
gate 219 produce a logic 0 output for application to
the base of transistor 182, thereby maintaining the
transistor non-conductive.
Thus; while the operator has commanded that the
motor run in the up direction, it initially is driven
in the down directïon in order to release all of the
clutches except that for the knee adjusting mechanism~
At the conclusion of the positive-golng pulse from gate
206 the common input of gates 221 and 222 switches from
logic 1 to logic 0, whereupon the output of gate 221
switches from logic 0 to logic 1 and the output of gate
222 switches from logic 1 to logic 0. Gate 218 will
now receive different logic levels on its inputs,
causing the gate's output to switch from logic 1 to
logic 0, thereby turning off transistor 181. At the
same time, gate 219 now receives similar logic 0 levels
at it~ inputs to produce a logic 1 for turning tran-
sistor 182 on. Motor 49 therefore now begins to rotate
in the desired up direction and will continue to rotate
in that direction as long as the operator continues to
depress the knPe-up switch actuator.
Of course, had the operator depressed the knee-
down actuator to close switch 187 in the down direction
it will now ~e apparent that the motor would initially
and momentarïly rotat~ in the up direction, to dis-
engage all clutches except the knee clutch, before iti5 then run in t~e down direction. By the same token,
from the foregoing explanation the manner in which the
~s~
081076-BHP - 40
back switch 188 controls the operation of s,olenoid 66
and motox 49 will be understood. The back-up and back-
dawn functions work in essentially the same ~ay as the
knee function~.
Turning now to the ~ed high low controls, when the
bed~up switch actuator is depressed to close switch 182
in the up direction or when the high switch 86a is
closed, conductor 273 is grounded and the three diodes
connected to that conductor conduct in order to essentially
lQ ~round conductors 253 and 254 to energize foot solenoid
67 and head solenoid 68, and in order to place logic 0
on the up ~us for initially and momentarily running
motor 49 in the down direction and for then rotating
the motor in the up direction. The ar~uation of switch
189 or switch 86a also grounds the junction of resistors
246 and 247 to discharge capacitor 239, thereby apply-
ing logic 0 to the upper input of gate 192 to reset or
clear flip-flip 193, 194. Transi~tor 245 will thus
always be maintained in its off condition while the bed
is being elevated. The actuated switch is deactuated
when the head and foot adjustiny mechanisms have raised
frame 12 to the level desired.
~hile the effects of depressing the bed~up switch
actuator in hand control 190 are the same as depressing
the switch actuator 86 at the foot end of the bed, this
;~ not true with respect to the bed-down switch actuator
and switch actuator 87. When switch 189 is closed in
the down direction, conductor 274 is grounded to turn
on the three diodes connected to the conductor, thereby
essentially grounding conductors 253 and 254, to
energize solenoids 67 and 68, and appl~ing logic 0 to
the down bus to effect rotation of motor 49, initially
'75~
081076-BHP - 41 -
and momentarily in the up direction and then in the
down direction. When the ~ed is lowered to the extent
desired, the patient, or other operator, releases the
bed-down switch actuator to de-energize the motor and
solenoids.
Assume now that the nurse or attendant wishes to
lower the bed to its lowermost position. This may ~e
accomplished merely by momentar;ly closing the low
switch 87a. When that happens logic 0 will be applied
to the S or set input of flip-flop 193, 194 to trigger
the flipflip to its set condition, thereby providing a
logic 0 output which is converted by inverter 244 to
logi~c 1 for turning transistor 245 on~ Conduc~ors 253
and 254 will therefore be essentially grounded and the
down bus will be established at logic 0. Solenoids 67
and 68 wïll energize and motor 49 will operate to lower
the bed. By employing flip-flop 193, 194, transistor
245 will be maintained conductive, and the bed will
continue to lower, after the nurse or attendant releases
switch actuator 87 and switch 87a opens. Hence, the
logic circuitry will be latched in a down operating
mode. In fact, it is not even necessary that the nurse
or attendant remain at the hospital bed. By latching
the system in a down operating mode, the nurse may
2S leave the hospital bed, thereby saving considerable
time. For this reason, flip-flop 193, 194 is labeled
the "walkaway down flip-flop" in FIGURE 18.
The bed will continue to descend, after switch 87a
opens, until head lo~ limit switch 155 and foot low
limit switch 152 are ~oth opened, namely when both ends
081076-BHP - 42 -
of frame 12 are all the way down. When that happens,
both of the inputs-of NAND gate 195 ~ill ~e at logic 1,
as a consequence of which. logic Q will be applied to
the base of transistor 236, to exti.nguish. lamp 238, and
to the lower input of gate 192 to provlde a logic 1
output ~hich is then converted by inverter 242 to logic
0 for application to the upper input of N~ND gate 191.
Logic 1 will thus ~e developed at the output of gate
191 which is then converted ~y inverter 243 to apply
logic 0 to the R input of the walkaway down flip~flop
193, 1~4 to reset the flip-flo.p to its res-et condition,
thereby producing a logic 1 output which causes tran-
sistor 245 to turn off, whereupon solenoid 67 and 68
and motor 49 de-energize.
15It is to be not2d that exclusive OR gate 220
performs another important function in addition to that
already described. I~ two switches are simultaneously
actuated, one switch. calling for motor rotation in the
up direction while the other switch commands motor
rotation in the down direction, gate 220 will provide a
lockout so that no motor ro~ation whatsoever can occur.
When t~ere are up and down commands simultaneously
present, both the do~l bus and the up bus will be at
logic Q, thereby applying logic 0 to both inputs of
gate 220 to produce a logic 0 output which is converted
by inverter 266 to logic 1 for application to the
common input of NOR gates 218 and 219. Logic 0 will
therefore be produced at the outputs of those gates and
transistors 181 and 182 will be non-conductive.
30As~ume now that at lea~t two of the adjusting
mechanisms are operating at the same time. Assume, for
example, that the patient has simultaneously depressed
~5~
081076-BHP - 43 -
the switch actuators for closing all three switches
187, 188 and 189 in the up direction. Solenoids 66-6
will all be energized and, after an initial momentary
counterrotation, motor 49 will rotate in the up di-
rection to raise upper frame 12, back support section31 and knee suppor~ sections 33 and 34. At this time
each of the four conductors 261-264 will he esta~lished
at logic 0, there~y applying logïc 0 to the upper
inputs of NOR gates 213 and 215 and to the lower inputs
of gates 214 and 216. Assume t~at when the ~ack
support section reaches the tilted position desired by
the patient, continued elevation of the upper frame and
knee support sections is desired. The patient will
therefore release t~e back-~p switch actuator on han~
control 190 to open switch 188, while continuing to
depre~s the bed-up and knee-up switch actuators~ Back
solenoid 66 will immediately be de-energized and the
direction of motor rotation will be momentarily reversed
în order to release clutch 56 and unlock the engaging
lug surfaces on clutch 56 and gear 52. With this
arrangement, any adjusting mechanism may be decoupled
from the motor drive while other adjusting mechanism
continue to be actuated by the motor drive. Momentary
motor reversal occurs whenever one of the actuated
adjusting mechanisms is deactuated.
To explain, when the back-up switch is opened by
the patient, conductor 263 changes from logic 0 to
logic 1 (receiving logic 1 via conductor 255 and the
LED of photo coupler 259), thereby tri~gering the one-
shot multivlbrator~ comprising gates 205 and 215,
resistor 227 and capacitor 234, to produce a positive-
' :,'
081076-BHP - 44 -
going pulse (namely, going from logic 0 to :Loglc 1 and
then back to logic 0) at the output of gate 2Q5 for
application to the lower i.nput of gate 217. The pulse
is converted to a negative-going pulse in gate 217,
which. is then converted in gate 206 back to a positive-
going pulse for application to the common input of
gates 221 and 222. Such a pulse effectively momentarily
reverses the operation of gates 221 and 222. To
elucidate, pxior to the application of the positive-
going pulse, the upper input of gate 221 is at logic 1while its lo~Yer input and ~oth inputs of gate 222 are
at logic 0. This condition produces a logic 1 at the
output of gate 221 and a log;c 0 at the output of gate
222, thereby effecting conduction of transistor 182 and
non-conduction of transistor 181 in order to run the
motor in the up direction. When the positive-going
pulse is then applied to the common input of gates 221
and 222 r both inputs of gate 221 and the upper input of
gate 222 will be at logic 1 while the lower input of
2~ gate 222 will be estaklished at logic 0. With those
signal conditions, gate 221 now momentarily switches to
a logic 0 output and gate 222 momentarily switches to a
logic 1 output to turn transistor 181 on and to turn
transistor 182 off. As a consequence, the motor
rotation in the up direction ~ill be interrupted for a
short interval ~40-150 milliseconds) during which time
the motor will be rotated in the down direction~
During the motor reversal interval, clutch 56 will be
unloaded and unlocked so that restoring spring 65 will
be a~le to return the clutch to its disen~aged position.
It will now ~e understood t~at the deactivation of
an~ function, while at least one other function continues
to operate, will cause the motor to momentarily reverse
~5~5~
08107Z-BHP - 45 -
directions in order-to decouple the motor drive from
the deactivated ~unction.
Consideration will now be given to the operation
of t~e control circuitry, in accordance with the
present invention, when it i5 desired to tilt the bed
in either direction. Assume, for example, that it is
desired to tilt upper frame 12 in the head-down, foot~
up direction. Assume also that frame 12 is not in its
lowermost position at this time. To achieve the de-
slred tilting, a trendelen~urg command is issued by
closiny trendelenbuxg switch 89a. Prior to the switch
closing, capacitor 277 ~ill ~e uncharged since each
~ide is connected to voltage source V+, through re-
sistors 278 and 279. When switch 89a is closed~ the
lS lower side of capacitor 277 is grounded and the upper
side will instantaneously be established at logic 0.
The upper input of NAND gate 19~ thus becomes logic 0
to provide a logic 1 output which is then converted by
inVerter 281 to logic 0 for application to the lower
2a input of gate 1~1. Logic 1 wil1 therefore be produced
by gate 191 to achieve resetting of the walkaway down
flip-flop 193, 194/ if it isn't already in its reset
condition. The logic 0, produced at the junction of
capacitor 277 and resistor 278 in response to the
initial closing of switch 89a, will also be applled to
the reset or S input o~ flip-flop 1~7, 198 but it will
have no affect on the operation of that flip~flop since
îts reset or R input will be grounded via the closed
head low limit switch 155~ Logic Q will therefore be
applied to the R input and such a logic level will
7~i~
081076 BHP - 46 -
override whatever i5 applied to the $ input and will
establi.sh flip-flop 1~7, 198 in its res.et condition,
thereby applying lo~ic 1 to the upper input of gate 207
and to the upper input of gate 199. Meanwhile, the
loqic 0, provided by the closed switch 155, will be
converted ~y inverter 282 to logic 1 for application to
the lower input of gate 199~ W-ith. logic 1 at both of
its inputs, gate 1~9 produces a logic 0 for the upper
input of ~ate 208, whose lower input, as well as the
lower input of gate 207, will ~e esta~lished at logic 0
~y t~e closed sw-itch 89a. The dissimilar logic levels
at the inputs of gate 207 .result in a logic 0 output
applied to the base of transistor 248, thereby main-
tainins the transistor non-conductive. Both of the
inputs of gate 208 will be at logic 0, however, so a
logic 1 output will be developed for the base of trans-
sistor 249, turning that transistor on in order to
~round conductor 254 and to place logic 0 on the down
buso
2n After an initial and momentary counterrotation in
the up direction, the head end of upper frame 12 will
therefore descent and will continue to drop as long AS
the operator maintains switch 89a closed. Assuming
that switch 89a i5 kept c~osed until the head end of
frame 12 drops to its lowermost level, at that time
switch 155 will opern and the R input of flip-flop 197,
198 will change from logic a to logic 1, as will the
input of inverter 282. The cond;tion of the flip~flop
will not c~ange at t~is time, however, because the S
3~ input will ~e established at logic 1~ Thls occurs
~ecause capacitor 277 ~egins to charge throug~ resistor
081076-BHP - 47 -
278 to voltage V+ as soon as switch 89a is closed.
Hence, the junction of capacitor 277 and resistor 278
will ~e at logic 1 when the head end lowers to its full
down position and opens switch 155. ~ith both its R
and S inputs at logic 1, the flip-flop remembers or
stays ;n its present condition, namely its reset
condition~ ~lthou~h the flip-flop does not switch
conditions when switch 155 opens, transistor 249 will
be turned off to de-energize head solenoid 68 and motor
49. To explain/ since the input of inverter 282 will
now be logic 1, ïts output will be logic 0, thereby
producing logic 1 at the output of gate 199. The
inputs of gate 208 will now be dissimilar, as a conse-
quence of which logic 0 will ~e applied to the base of
transistor 249 to render it non-conductive.
Transistors 248 and 249 are therefore both turned
off, even though the operator continues to depress
switch actuator 89 to maintain switch 89a closed. If
additional head-down, foot-up tilting is desired, the
operator merely must release the switch actuator 89 and
then immediately re-depress it, thereby momentarily
opening switch 89a. As soon as the switch opens,
capacitor 277 discharges since both sides of the
capacitor will be connected to voltage source V~.
When switch 89a then re-closes, the upper side of the
capacitor, and consequently th~ S input of flip-flop
197, 198, will be instanteously at logic Q. This time,
however, since the R input i~ at loglc 1, the logic 0
on t~e ~ input wïll tr;gger t~e flip-flop from its
reset to its set condition. Logic 0 is consequently
produced at the output of flip-flip 197, 198. Both
~ ~ ~r~
081076-BHP - 48 -
inputs of gate 199 will then be logic 0 to produce
logic 1 for the upper input of gate 208, the lower
input of which receives logic Q from the re-closed
switch 89a. With the two inputs of gake 20B at
diferent logic levels, a logic 0 will result and
transistor 249 ~ill remain non-conductive. Gate 2~7,
on the other handt will no~ receive logic a at both of
its inputs, resulting in a logic 1 which turns tran-
sistor 248 on, there~y grounding conductor ~53 to
lQ energize foot solenoid 67 and apply logic 0 to the up
hus to run t~e motor in the up direction, after of
course the initial momentary rotat;on in the down
direction~ The foot end of frame 12 ~ill therefore
elevate and ~ill continue to rise as long a~ switch 89a
ls maintained closed by the operator. If the maximum
tilt is desired, the foot end of the bed will be raised
to its uppermost position.
Hence, by actuating trendelenburg switch 89a, the
head end of the upper frame 12 will first go all the
way down, if it isn't already there, and then the foot
end will be raised. Note that this action will occur
regardless of the horizontal level of frame 12 and even
though it may already be tilted in either one of its
two tilt directions. In other words, the upper frame
will be tilted directly to a trendelenburg position
regardless of its position at the time the trendelen-
burg command is issued.
It will now be apparent that ~y closing the
reveXse trendelenburg s~itch 88a, thereby issuing a
reverse trendelenburg command, frame 12 may be ~ilted
directly in the opposite or head-up, foot-down di-
rect;on. If the foot end of frame 12 is not already at
~s~
081076-BHP - 4g -
its low limit, transistor 252 will initially be turned
on (while transistor 251 will be offl ~o energize the
foot solenoid 67 and to drive thQ motor 49 in its down
direction, thereby lowering the foot end of frame 12.
When the lowermost level is reached and switch 152
opens, transistor 252 will be rendered non-conductive.
5witch actuator 88 may then ~e released and re-de-
pressed to trigger fl;p-flop 201, ~02 to its set
condition, as a result of ~hich transistor 251 will be
turned on to raise the head end of frame 12 to the
extent desired.
Hence, in accordance with the invention, merely by
actuating switches~ 88a and 89a, frame 12 may be moved
from an~ tilted or level position directly to any other
tilted or level position. It is not necessary, for
example, to first level the bed in its uppermost or
lowermost position before the bed may then be established
in the trendelen~urg or reverse trendelenburg position.
The bed can go from trendelenburg directly to reverse
trendelenburg and vice versa. Note also that when the
bed is in the trendelen~urg position, it may be leveled
by actuating the reverse trendelenburg switch 88a, and
when in the reverse trendelenburg position the bed may
be leveled by operating the trendelenburg switch 89a.
Moreover, by operating the high-low switches 86a, 87a
and 18~, the entire frame 12 may be raised or lowered
even though it may be tilted. It is also to be realized
that both ends of frame 12 may he lowered to their
lowermost level, e~en though t~e ~rame is tilted, by
closing switch 87a and actuatïng the walkaway down
1ip-flop 193l 194.
5~
081076-BHP - 50 -
The invention provides, therefore, an adjustable
hospital ~ed featuring unique operator-controlled logic
circuitr~ for causing the bed's upper frame to quickly
shift, from any level and from any ti.lted position,
directly to any other tilted position. Moreover,
relatively simple steps are required on the part of the
operator.
Whïle a particular em~odiment of the invention has
~een shown and described, modifications may he made,
and it is intended in the appended claims to cover all
such.modifications as may fall within the true spirit
and scope of the invention.
