U.S. patent number 3,578,379 [Application Number 04/722,504] was granted by the patent office on 1971-05-11 for adjustable chair.
This patent grant is currently assigned to Pennwalt Corporation. Invention is credited to Jim C. Cahlik, John M. Gardella, Norris O. Taylor, Wilmer P. Uhler.
United States Patent |
3,578,379 |
Taylor , et al. |
May 11, 1971 |
ADJUSTABLE CHAIR
Abstract
A dental chair is equipped with a cushion roll between the
backrest and the seat rest to provide a continuous supporting
surface extending from the backrest to as far as the bottom of the
leg rest. Single or dual controls are provided on the backrest,
preferably along the opposite side edges of the backrest. Where
dual controls are employed, a signal from a dental assistant's
control will not operate the chair except in the absence of a
signal from the dentist's control, which preferably overrides the
assistant's control. A shroud connected to the seat rest is biased
into engagement with the backrest adjacent the pivotal connection
of the backrest and seat rest. Continuous return of the backrest to
upright position may be effected by a holding device incorporated
in the control unit, with provision for deactivation when a control
switch for reclining the backrest is subsequently actuated. During
movement of the backrest to various angular inclinations the arm
rest is maintained in substantially parallel relation to the seat
rest.
Inventors: |
Taylor; Norris O. (Swarthmore,
PA), Uhler; Wilmer P. (Tottenville, Staten Island, NY),
Gardella; John M. (Staten Island, NY), Cahlik; Jim C.
(Parma, OH) |
Assignee: |
Pennwalt Corporation
(N/A)
|
Family
ID: |
45953325 |
Appl.
No.: |
04/722,504 |
Filed: |
December 28, 1967 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
475181 |
Jul 27, 1965 |
3414324 |
Dec 3, 1968 |
|
|
Current U.S.
Class: |
297/71; 297/330;
297/411.2; 297/316; 297/391 |
Current CPC
Class: |
A47C
7/38 (20130101); A47C 1/03211 (20130101); A47C
1/03 (20130101); A47C 1/037 (20130101); A61G
15/125 (20130101); A61G 15/02 (20130101); A47C
7/541 (20180801); A61G 2203/726 (20130101) |
Current International
Class: |
A47C
1/031 (20060101); A47C 1/037 (20060101); A61G
15/12 (20060101); A61G 15/00 (20060101); A61G
15/02 (20060101); A47c 001/037 (); A47c
001/04 () |
Field of
Search: |
;297/68,83,84,85,86,87,88,89,90,91,330,339,347,348,316 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McCall; James T.
Parent Case Text
This is a divisional application of application Ser. No. 475,181,
filed July 27, 1965, now U.S. Pat. No. 3,414,324, granted Dec. 3,
1968.
Claims
We claim:
1. A chair including a seat rest and a backrest, means pivotally
connecting said backrest to said seat rest, means for causing said
backrest to pivot relative to said seat rest, and a transition roll
disposed between said seat rest and said backrest so as to provide
a continuous supporting surface between said backrest and said seat
rest in all relative positions of said backrest and said seat rest,
said transition roll being constructed of resilient material so as
to be deformable during pivoting motion of said backrest relative
to said seat rest.
2. A chair including a seat rest and a backrest, means for
pivotally connecting said backrest to said seat rest, and a shroud,
means pivotally connecting said shroud to said seat rest, and
resilient means connected between said seat rest and said shroud
for biasing an upper portion of said shroud into engagement with
said backrest.
3. A chair including a backrest and a seat rest, means pivotally
connecting said seat rest to said backrest, a motor, a control for
said motor on the side edge of said backrest, a driving connection
between said motor and said backrest whereby operation of said
motor causes pivoting of said backrest relative to said seat rest,
an arm rest, means pivotally mounting said arm rest to said
backrest, and means connecting said arm rest to said seat rest for
maintaining said arm rest substantially parallel to said seat rest
in all positions of said backrest relative to said seat rest.
4. In an adjustable chair of the type including a seat rest and a
backrest pivotally mounted for movement relative to said seat rest,
and motor means for actuating the pivotal movement thereof; said
motor means comprising a reversible motor, and a set of control
means located on a side edge of said backrest for reclining said
backrest relative to said seat rest and for moving said backrest to
an upright position relative to said seat rest.
5. In an adjustable chair as defined in claim 4 wherein a second
set of control means is provided for reclining said backrest
relative to said seat rest and for moving said backrest to an
upright position relative to said seat rest, and means connecting
said set of control means to said second set of control means for
locking out said second set of control means whereby conflicting
signals cannot be transmitted to said motor means.
6. In an adjustable chair as defined in claim 5 wherein said second
set of controls is located on another side edge of said
backrest.
7. In an adjustable chair as defined in claim 4 wherein said set of
control means includes a three-position switch for moving said
backrest to a reclined position and to an upright position relative
to said seat rest; said three-position switch including first means
for providing a neutral position, second means for actuating said
motor means to recline said backrest relative to said seat rest,
and third means for actuating said motor means for moving said back
rest to an upright position relative to said seat rest.
8. In an adjustable chair as defined in claim 7 wherein said third
means includes means for holding said switch in position to
continually actuate said motor means until said backrest reaches
the extreme upright position relative to said seat rest.
9. In an adjustable chair of the type including a seat rest and a
backrest, support means fixedly secured adjacent to a lateral edge
of said seat rest and extending upwardly therefrom in a first
substantially vertical plane, said backrest including lateral
flange portions each integral with a lower portion of said backrest
and extending forwardly therefrom in a second substantially
vertical plane parallel to said first substantially vertical plane,
and pivot means connecting said flange portions to said support
means for pivotally mounting said backrest to said seat rest for
rotation about a horizontal axis of said pivot means disposed above
the plane of said seat rest.
10. In an adjustable chair as defined in claim 9 wherein means are
provided for rotating said backrest to a lowermost position with
said backrest being disposed below a horizontal plane passing
through a portion of said backrest adjacent to said seat rest.
11. In a dental chair having a seat rest and a backrest mounted for
movement relative to said seat rest, a leg rest, means pivotally
connecting said leg rest to said seat rest, a motor for actuating
the pivotal movement of said leg rest, control means located on a
side edge of said backrest for controlling said motor to effect
pivotal movement of said leg rest, and cushion means disposed over
said seat rest and leg rest and extending without interruption from
a rearward portion of said seat rest to a lower portion of said leg
rest for providing a continuous uninterrupted supporting surface
for all positions of said seat rest and said leg rest relative to
each other.
12. An adjustable chair as defined in claim 4 wherein a second set
of control means is provided for reclining said backrest relative
to said seat rest and for moving said backrest to an upright
position relative to said seat rest, said sets of control means
being respectively located on opposite side edges of said
backrest.
13. An adjustable chair of the type including a seat rest and a
backrest pivotally mounted for movement relative to said seat rest,
and motor means for actuating the pivotal movement thereof; said
motor means comprising a reversible motor, and a set of control
means located on said backrest for reclining said backrest relative
to said seat rest and for moving said backrest to an upright
position relative to said seat rest, wherein a second set of
control means is provided for reclining said backrest relative to
said seat rest and for moving said backrest to an upright position
relative to said seat rest, and wherein one of said sets of control
means is operable for reclining or moving said backrest in the
absence of a signal from the other of said sets of control
means.
14. An adjustable chair as defined in claim 6 wherein the second
set of control means is operable in the absence of a signal from
the other set of control means, and wherein a signal from the other
set of control means overrides a signal from the second set of
control means.
15. An adjustable chair as defined in claim 13 wherein said second
set of control means is inoperable upon actuation of said other set
of control means.
16. In an adjustable chair as defined in claim 4, further including
means for elevating and lowering said chair, wherein said set of
control means includes a three-position switch for raising said
chair to an elevated position and for lowering said chair to a
lower level position; said three-position switch including first
means for providing a neutral position, second means for actuating
said elevating and lowering means to raise said chair to an
elevated position, and third means for actuating said elevating and
lowering means for lowering said chair from an elevated position to
a lower position.
17. An adjustable chair of the type including a seat rest and a
backrest pivotally mounted for movement relative to said seat rest,
and motor means for actuating the pivotal movement thereof; said
motor means comprising a reversible motor, and a set of control
means located on said backrest for reclining said backrest relative
to said seat rest and for moving said backrest to an upright
position relative to said seat rest, wherein said control means
includes a switch for controlling movement of said backrest toward
an upright position by energizing said motor means, and further
including means for holding said switch in position to energize
said motor means until said backrest reaches an extreme upright
position relative to said seat rest.
18. An adjustable chair as defined in claim 17 wherein said control
means includes a second switch for controlling reclining movement
of said backrest, and resetting means for deactivating said holding
means incident to actuation of said second switch.
Description
This invention relates to new and novel adjustable chairs, and more
particularly to adjustable chairs which are ideally suited for use
in the modern practice of dentistry.
An object of the present invention is to provide a dental chair of
the type including a backrest, a seat rest, a leg rest and an arm
rest wherein synchronous motions of various elements of the chair
are designed such that a patient may be placed in the most
convenient positions for the many and varied operations and
allowing for the maximum functionability for a dentist or surgeon
and yet retaining the dignity and comfort of the patient.
Another important object of the invention is the provision of an
adjustable chair wherein a leg rest is pivotally mounted to a seat
rest so as to provide a kneebreak therebetween, and the provision
of automatic positioning of the leg rest relative to the seat rest
to provide the most comfortable position for a patient when the
backrest is in either its upright position or when in its reclined
position.
Another object of this invention is to provide single control means
for actuating the various motions of the adjustable chair.
Another object of this invention is to provide separate control
means so that various synchronous motions of the chair elements may
be actuated from the "dentist's side" or from the "assistant's
side" of the chair.
Another object of the invention is to provide an override control
means so that the dentist's controls lock out the controls of the
assistant thus maintaining control by the dentist.
Another object of this invention is to provide a new and novel
switch means which, upon actuation, causes the backrest to return
from a reclined position to a fully upright position.
A further object of this invention is to provide an adjustable
chair wherein a backrest is pivotally mounted to a seat rest at a
point above the plane of the seat rest so as to minimize rocking of
an occupant's clothes as the backrest is pivoted from an upright
position to a reclined position relative to the seat rest.
A further object of this invention is to provide an adjustable
chair wherein the backrest is pivotable from an upright position to
a fully reclined position wherein the backrest is inclined below a
horizontal position so as to aid in reviving a patient who has
fainted, by increasing blood circulation to the patient's head, or
for placing a patient in position for some particular type of
operation.
A further object of this invention is to provide a release
mechanism for the arm rest whereby the arm rest is pivotally
mounted on a portion of the backrest and is swingable away from the
seat rest to provide for easy patient admittance and departure.
A further object of this invention is to provide a chair with a
two-piece backrest portion thereby adapting the chair for use with
interchangeable headrests.
Another object of this invention is to provide a shroud or cover
plate which is pivotally mounted upon a rear portion of the seat
rest so as to shield the actuating mechanism of the chair and
prevent personal injuries.
A further object of this invention is to provide a novel transition
roll which is located between the seat rest and the backrest
thereby ensuring maximum patient comfort for all positions of the
backrest relative to the seat rest.
A still further object of this invention is to provide an
adjustable chair, of the type set forth above, wherein separate
means are provided for adjusting the leg rest relative to the seat
rest.
With the above and other objects in view that will hereinafter
appear, the nature of the invention will be more clearly understood
by reference to the following detailed description, the appended
claimed subject matter and the several views illustrated in the
accompanying drawings:
In the drawings:
FIG. 1 is a perspective view of an adjustable chair which is
illustrative of the present invention.
FIG. 2 is a diagrammatic view and illustrates the major chair
elements in an upright position and, in broken lines, in a
partially reclined position.
FIG. 3 is a diagrammatic view, similar to FIG. 2, and illustrates
the chair elements, in broken lines, in a more fully reclined
position, and in full lines, illustrates the chair elements with
the backrest thereof being in a fully reclined position so as to be
inclined below the horizontal.
FIG. 4 is a schematic diagram illustrating the various electrical
components incorporated in the adjustable chair.
FIG. 5 is a vertical sectional view, taken on line 5-5 of FIG. 1,
and illustrates the mechanism for actuating the pivotal movements
of the major chair elements.
FIG. 6 is a transverse sectional view, taken on line 6-6 of FIG. 5,
and illustrates the seat rest and leg rest with portions broken
away to show a portion of the thrust means for pivoting the leg
rest and seat rest.
FIG. 7 is a vertical sectional view, taken on line 7-7 of FIG. 5
and illustrates a pair of supporting members fixedly secured to the
seat rest and pivotally supporting the shroud member.
FIG. 8 is a vertical sectional view, taken along line 8-8 of FIG. 7
and illustrates a crosshead which is attached to the piston rod of
a conventional lift mechanism, and also illustrates the pivotal
mounting of the seat rest to the crosshead.
FIG. 9 is a vertical sectional view, taken on line 9-9 of FIG. 8,
and illustrates a guide slot which is formed on the crosshead for
cooperation with an extension of a link which is fixedly secured to
the underside of the leg rest.
FIG. 10 is a sectional view, taken on line 10-10 of FIG. 5, and
illustrates the mounting of a roller on the forward end of the
thrust bar mechanism.
FIG. 11 is a vertical transverse sectional view, taken on line
11-11 of FIG. 5, and shows the arrangement of drive sprockets and
idler sprockets for connecting the actuating motor to the operating
mechanisms.
FIG. 12 is a vertical sectional view, taken on line 12-12 of FIG.
11, and shows, in elevation, the arrangement of one of a pair of
operating screws mounted for rotation on the underside of the seat
rest.
FIG. 13 is a sectional view, taken on line 13-13 of FIG. 12, and
illustrates a guide arrangement for guiding the movement of a
channel-shaped thrust bar.
FIG. 14 is a sectional view, taken on line 14-14 of FIG. 12, and
illustrates a manner in which a nut member on the screw is
pivotally secured to a forward portion of a yoke member.
FIG. 15 is a sectional view, with parts broken away for clarity,
and illustrates the position of the seat rest and leg rest when the
backrest is in its substantially upright position.
FIG. 16 is a sectional view, similar to FIG. 15, and illustrates
the position of the seat rest and leg rest with the backrest in a
reclined position.
FIG. 17 is a partial plan view showing the arm rest being pivotally
mounted to a portion of the backrest and being pivotally mounted
therewith relative to the seat rest.
FIG. 18 is a sectional view, taken on line 18-18 of FIG. 17, and
illustrates the manner in which the arm rest is pivotally mounted
upon a forwardly extending flange portion of the backrest, and also
showing the pivotal mountings for connecting the backrest and
shroud to upstanding support members on the seat rest.
FIG. 19 is a rear elevational view, with portions broken away for
clarity, and illustrates a set of control switches being mounted at
each side of the backrest.
FIG. 20 is a vertical sectional view, taken on line 20-20 of FIG.
19 and illustrates the manner in which an adjustably positionable
headrest is mounted upon the backrest.
FIG. 21 is a fragmentary perspective view of the backrest and the
headrest, with the headrest in a partially assembled position
relative to the backrest.
FIG. 22 is a fragmentary perspective view of the switches and
mounting plate which are located on the dentist's side of the
backrest.
FIG. 23 is a partially exploded view of the switches which are
located on the dentist's side of the chair.
FIG. 24 is an elevational view of the assembled switches which are
illustrated in FIG. 23.
FIG. 25 is an enlarged sectional view, taken on line 25-25 of FIG.
24, and shows a novel spring member which is mounted between the
"recline" switch and the tiltup switch on the dentist's side of the
backrest.
FIG. 26 is a fragmentary view illustrating the "tiltup" switch in a
fully depressed and locked position, and illustrates the "recline"
switch in a released position, and also shows the novel spring
member in a bowed position which results from engagement of the
spring member by a cam located upon the "tiltup" switch.
FIG. 27 is a view similar to FIG. 25 and illustrates the cam on the
"tiltup" switch engaged with the spring member for causing
distortion thereof.
FIG. 28 is a cross-sectional view of the pushbutton portion of the
"recline" switch.
FIG. 29 is a cross-sectional view of the pushbutton portion of the
"tiltup" switch.
FIG. 30 is a fragmentary perspective view of the switches and
mounting plate located on the assistant's side of the backrest.
FIG. 31 is a sectional view of the assistant's control switch and
shows a portion of the wiring therefor.
FIG. 32 is a fragmentary perspective view of a modified form of a
backrest wherein an upper portion of the backrest is removable from
a lower portion thereof to provide for interchangeability of head
rests.
FIG. 33 is a front elevational diagrammatic view of the two-piece
backrest, with portions broken away for clarity, and illustrates
the adjusting mechanism for adjustably positioning the upper
portion of the two-piece backrest relative to the lower portion
thereof.
FIG. 34 is a vertical section, taken on line 34-34 of FIG. 33, and
illustrates a support rod fixedly secured to the top portion of the
backrest and slidably received within a guide slot in the lower
portion of the backrest.
FIG. 35 is a sectional view, taken on line 35-35 of FIG. 33, and
illustrates the control means for effecting adjustment of the
support rod within the lower portion of the backrest.
FIG. 36 is a plan view of a modified form of seat rest and leg rest
wherein an adjusting mechanism is provided for selectively
adjusting the leg rest relative to the seat rest.
FIG. 37 is a fragmentary elevational view, of FIG. 36, and
illustrates the manner in which a pair of channels can be adjusted
in length to provide for adjusting the leg rest relative to the
seat rest.
FIG. 38 is a plan view of another modification of the invention
wherein the leg rest and seat rest are provided with an adjusting
mechanism for varying the inclination of the leg rest relative to
the seat rest.
FIG. 39 is a fragmentary elevational view of FIG. 38 and
illustrates the pivotal mounting for one of a pair of plate members
on the top side of the leg rest.
FIG. 40 is a view of the underside of a leg rest and seat rest
wherein a further modification of the invention includes a separate
motor mounted on the underside of the leg rest and cooperating with
a crank for varying the inclination of the leg rest relative to the
seat rest.
FIG. 41 is a fragmentary elevational view and illustrates the
manner in which the motor and crank are connected between the seat
rest and the leg rest.
Referring to the drawings in detail, there is illustrated in FIG. 1
a new and novel adjustable chair, generally indicated by the
numeral 10, which chair is particularly adapted for use in the
practice of dentistry. The chair 10 includes a conventional
lift-mechanism 11, which may be actuated by a conventional
foot-operated switch 12 for vertically raising and lowering the
chair 10.
A forwardmost portion of the chair 10 comprises a leg rest portion
13 which depends forwardly and downwardly from a seat rest portion
14. The leg rest portion 13 and seat rest portion 14 includes a
cushion member 15 which extends, without interruption, from a
rearward portion of the seat rest portion 14 to a lower portion of
the leg rest portion 13 so as to provide a continuous uninterrupted
supporting surface.
A backrest portion 16 is pivotally mounted, at 18, to an upstanding
portion of the seat rest portion 14, and has a pair of arm rests 20
pivotally connected thereto, at 22. The backrest portion 16 has a
headrest 24 adjustably mounted thereon by a strap member 25. The
transition roll 26 is located at the juncture between the seat rest
portion 14 and the backrest portion 16 so as to provide a
continuous supporting surface between the seat rest portion 14 and
the backrest portion 16 regardless of any changes in the relative
position of the backrest portion 16 and the seat rest portion
14.
Control means 28 are located on a side of the backrest portion 16
and include a rocker switch 29 for vertically raising and lowering
the chair 10, a pushbutton 30 for moving the backrest portion 16 to
a reclined position, and a second pushbutton switch 31 for moving
the backrest portion 16 to an upright position. The rocker switch
29 actuates the lift mechanism 11 in the same manner as the
foot-operated switch 12 so that the chair 10 may be adjusted by the
switch which is most conveniently located for the dentist during
any given operation. As will be more fully described, a dual set of
control means is located on the other side of the backrest portion
16 so that the dentist's assistant is also provided with convenient
control for varying the positions of the chair 10.
FIGS. 2 and 3 are diagrammatic illustrations of the major elements
of the chair 10. The full line position of FIG. 2 illustrates a leg
rest 34 pivotally mounted to a bracket 35 which is fixedly secured
to a seat rest 36. The seat rest 36 has a pair of supporting
members 37 fixedly attached thereto along lateral edges at the
rearmost portion thereof, and a backrest 38 includes a pair of
forwardly extending flange portions which are pivotally connected
to the support members 37, at 40, above the plane of the seat rest
36.
Actuating means, generally indicated by the numeral 45, are
provided for adjustably positioning the various elements of the
chair 10. It will be apparent from a comparison of the full-line
positions and the broken-line positions of FIGS. 2 and 3, that the
actuating mechanism 45 causes the backrest 38 to be movable from
the upright position of FIG. 2 through a series of intermediate
positions to a completely reclined position wherein the backrest 38
is inclined at an angle of approximately 8.degree. below the
horizontal, as is shown in the full line position of FIG. 3.
A general understanding of the operation of the chair 10 will
become apparent by consideration of the wiring diagram illustrated
in FIG. 4. A power supply, generally indicated by the numeral 50,
is connected to a terminal board 51 to provide power for operating
the various mechanisms. The conventional lifting mechanism 11 is
actuated by a motor 52 which is controlled by the foot-operated
switch mechanisms 12 and 12', located at the base of the chair 10,
or by the control means 28 and 28' which are located along opposite
sides of the backrest portion 16. Movement of the switch 12 from
its normally opened position to the closed position will actuate
the motor 52 and thus causing the chair 10 to raise. In order to
lower the chair 10, it is necessary to actuate the switch 12' so as
to open an oil-release solenoid valve thus permitting the chair 10
to lower.
The second point at which the chair 10 can be raised or lowered is
at either of the control panels 28 or 28'. The rocker switches 29
and 29' are conventional three-position switches which are normally
open. When the upper portion of either rocker switch 29 or 29' is
pressed, the motor 52 starts and causes the chair 10 to raise.
Pressing the lower portion of either of the rocker switches 29 or
29' causes a conventional solenoid valve to open which releases the
oil pressure in the lift mechanism 11, thus permitting the chair 10
to lower. If by accident, the foot lever 12 and either of rocker
switches 29 and 29' are actuated for opposing motions, no harm will
come to the chair 10 although this is not recommended.
The reclining and tilting up operation of the chair 10 is
controlled by pushbutton switches 55 and 55', and 56 and 56',
respectively. Switches 55 and 56 are located at the control panel
28 on the dentist's side of the chair 10, while the switches 55'
and 56' are located at the control panel 28' on the assistant's
side of the chair. The chair 10 can be brought to any angle of
recline by simply pressing the correct switch for the desired
motion. Pressing the switch 55 or 55' would recline the chair 10
and, by releasing the finger pressure from the switch, the chair
motion will stop at any angle desired. Switches 55 and 56' will
tilt the chair 10, i.e. the backrest 38, up from the horizontal
position. This operation can be accomplished by either pressing the
switch 56 or 56', and holding it, or the switch 56 can be pushed in
and then pushed clockwise to a lock and hold position. The switch
will hold in this position throughout the travel of the chair and
return to its normal position when the "recline" switch 55 is
actuated. This feature of the invention will be more clearly
defined with the explanation of FIGS. 24--27.
An important feature of this invention is that means are provided
whereby the dentist's controls will override any command given by
the assistant's controls. From a consideration of FIG. 4, it will
be apparent that power is fed to the assistant's switches 55' and
56' through the wire 60 and connector 61. Tracing the wire 60
through the dentist's switches 56 and 55 will show a complete
circuit so that actuation of either of the assistant's switches 55'
or 56' will cause the respective desired motion of the chair.
However, if the dentist presses either switch 55 to cause the chair
to recline, or pushes the switch 56 to cause the chair to tilt up,
the circuit to the assistant's switches 55' and 56', through wire
60 and connector 61 is broken so that no conflicting signals can be
given to the assistant's switches.
The reclining mechanism for the chair 10 is operated by motor 62
which is preferably a single phase AC reversible motor. A limit
switch 63 is provided for shutting off motor 62 when the chair has
reached its "upright" position, and a similar limit switch 64 is
provided for shutting off motor 62 when the chair has reached its
extreme recline position.
As is shown in FIGS. 5--8 a plunger or piston rod 70 extends
upwardly from the chair base 11 and is part of a conventional
mechanism for raising and lowering the chair 10. A horizontally
disposed crosshead 71 is bolted or otherwise secured to the plunger
70 so as to be maintained in a substantially horizontal position. A
pivot rod 72, see FIG. 8, is carried by crosshead 71 and is
transversely aligned at the rearmost portion of the crosshead 71. A
pair of pivot blocks 73 are pivotally mounted upon the rod 72 at
the lateral edges of the crosshead 71. A plurality of screws 74 are
provided for fixedly securing the seat rest 36 to pivot blocks 73
(See FIGS. 7 and 8) such that the seat rest 36 is mounted on the
pivot rod 72 for pivotal motion relative to the crosshead 71 and
plunger or piston rod 70.
As is best shown in FIGS. 5, 15 and 16, a pair of upstanding
support plate members 37 are fixedly secured to the rearwardmost
lateral edge portions of the seat rest 36. The backrest 38 is
provided with a pair of lateral flange portions 39 which extend
forwardly from a lowermost portion thereof. Flange portions 39 are
each pivotally secured to a respective one of the pair of support
plate members 37 so that the backrest 38 is mounted for pivotal
motion, at 40, between an upper position to a fully reclined
position wherein, as is shown in FIG. 3, the backrest 38 is
positionable at approximately 8.degree. below the horizontal.
The chair 10 is operated between the recline and upright positions
by the motor 62. The motor 62 is provided with support bracket
means 80 (See FIG. 6) which is fixedly secured to a front underside
portion of the seat rest 36 by a plurality of bolts 82. As is
clearly shown in FIGS. 6, 11 and 12, a forward support bracket 85
is secured to and extends transversely of a front portion of the
seat rest 36, and cooperates with a rearward support bracket 86,
for supporting a pair of parallel screws 87 and 88 beneath lateral
edges of the seat rest 36. As shown in FIG. 12, a beveled washer
85' is mounted on each of the elements 87 and 88 between the
bracket 85 and the collar 89. A drive sprocket 90 is mounted upon
the forward support bracket 85 and is driven by the motor 62
through a gear reducer 91. A drive chain 92 partially encircles the
drive sprocket 90 and extends about a driven sprocket 94, which is
secured to drive screw 87, and also extends about driven sprocket
95 which is secured to drive screw 88. A pair of idler sprockets 96
and 97 are mounted for rotation on bracket 85, and it is preferable
that the idler sprocket 96 be adjustably mounted upon the bracket
85 so as to provide a means for increasing or decreasing tension in
the drive chain 92.
Each of the screws 87 and 88 is provided, respectively with a ball
nut 98 and 99 which are mounted for translation thereon. As is best
shown in FIGS. 12 and 14, the ball nut 98 is provided with a post
100 which is disposed thereabove for cooperating with limit switch
63 to stop the motor 62 when the backrest 38 reaches its fully
upright position, and also cooperates with limit switch 64 for
stopping motor 62 when the backrest 38 reaches its fully reclined
position.
A generally U-shaped yoke member 102 is provided at each of its
forwardly extending leg members with a bifurcated bracket 103 and
104 for pivotally connecting the yoke member 102 to a respective
one of the ball nuts 98 and 99, in the manner best illustrated in
FIGS. 6 and 14. As is clearly shown in FIGS. 5 and 6, a pair of
brackets 108 are fixedly secured to a central lowermost portion of
the backrest 38 and are pivotally connected to the bight portion of
the U-shaped yoke member by a pivot pin 110. Upon actuation of
either of the pushbutton switches 56 and 56', the motor 62 drives
through gear reducer 91 to rotate the screws 87 and 88 thus causing
ball nuts 98 and 99 to move forwardly beneath the seat rest 36 and
exerts a force upon brackets 108 so as to pivot the backrest 38
toward a reclined position about the pivot 40.
Each side of the yoke member 102 is provided with a depending boss
120 and 122. A pair of thrust bars 124 and 126 are pivotally
connected to the bosses 120 and 122 by pivot means 128 and 130
respectively. Thrust bars 124 and 126 extend forwardly along
lateral edges portions beneath the seat rest 36 and, as is best
shown in FIGS. 2, 6, 12 and 13, the thrust bars are guidingly
mounted upon roller members 132 and 134, which are in turn
supported by depending brackets 35. The forwardmost end portions of
the thrust bars 124 and 126 have rotatably mounted thereon a pair
of roller members 140 and 142, respectively, which are guided for
movement along the underside of the seat rest 36 by suitable
U-shaped guide members 144, as is best shown in FIGS. 5 and 10.
As is best shown in FIGS. 6 and 15, a pair of links 146 and 148 are
fixedly secured to uppermost lateral portions of the leg rest 34
and are pivotally connected on pivot pins 150 which are carried by
the brackets 35 which depend from the seat rest 36. Links 146 and
148 have rearwardly extending legs 152 and 154, respectively, and
carry roller members 156 and 158. As is clearly shown in FIGS.
5--8, a pair of guide plates 160 and 161 are fixedly secured by
suitable screws 162 to the underside of crosshead 71 to provide
guide slots 164 for receiving therein the roller members 156 and
158. Such an arrangement provides for a lost motion connection
between respective roller member 156 and 158 with the crosshead
71.
Actuation of either of the pushbutton switches 55 or 55' causes the
motor 62 to rotate the parallel screws 87 and 88 such that the ball
nuts 98 and 99 are moved forwardly thereon and causes the yoke
member 102 to rotate the back rest 38 about the pivot 40. As the
yoke member 102 moves downwardly and forwardly, the thrust bars 124
and 126 are driven forwardly to cause the leg rest 34 to move
upwardly. The roller members 156 and 158 are restrained within the
guide slots 164 and vertical movement is procluded. Consequently,
the links 146 and 148 rotate upwardly about the axis of roller
members 156 and 158 to cause upward movement of the pivot pin 150
and brackets 35. As a result, seat rest 36 is pivoted upwardly
about the axis of pivot rod 72.
As a result of the foregoing operation, the chair 10 is moved from
an upright position toward the reclined position. Continued
actuation of the switches 55 or 55' will cause the backrest 38 to
assume the fully reclined position which is best illustrated by the
full line position of FIG. 3. When the backrest 38 reaches the
fully reclined position, the ball nut 98 actuates the limit switch
63 to deactivate the motor 62, and movement of the chair 10 ceases.
Actuation of either of the switches 56 or 56' reverses the
operation of motor 62 such that the backrest 38, the leg rest 34
and the seat rest 36 are rotated from the reclined position toward
the upright position.
It is desireable that the arm rest 20 be moved in synchronism with
the seat rest 36 and backrest 38. As is clearly shown in FIGS. 2,
17 and 18, each of the arm rests 20 is pivotally mounted at 170, on
a respective one of the lateral flange portions 39 which are
integral with the backrest 38. As is best shown in FIG. 18, the
sleeve 172 is fixedly secured, such as by welds 174, to a
respective flange portion 39. The pivot shaft 176 is mounted for
rotation within the sleeve 172 and carried therewith as the
backrest 38 rotates about the pivot 40. It is desirable that the
arm rest 20 be maintained in substantially parallel relation to the
seat rest 36, as the seat rest 36 rotates about pivot rod 72.
Therefore, a crank arm 178 is mounted upon the pivot shaft 176 for
rotation therewith. An arm link 180 has one end thereof pivotally
connected to the crank arm 178, at 182, and the other end of the
arm link 180 is pivotally connected, at 184, to the support member
37 which extends upwardly from the seat rest 36. As the backrest 38
pivots relative to the seat rest 36, the pivot shaft 176 is carried
with the backrest 38 but rotates within the sleeve 172 such that
the arm rest 20 is maintained in substantially parallel relation to
the seat rest 36.
In order to provide for easy admittance and departure from the
chair 10, it is desirable that the arm rests 20 be adapted to swing
up and out of the way. As is shown in FIGS. 17 and 18, the pivot
shaft 176 is provided with a substantially radially disposed
opening 190 for receiving a locking member or pin 192 therein. A
bushing 194 is fixedly mounted within the arm rest 20 and provides
for sliding motion of the pin 192 therein. A release lever 196 is
pivotally mounted to the arm rest 20, at 198, and is connected to
the locking member or pin 192 by a link 200. The rearward portion
of the release lever 196 is disposed in an accessible position at
the rear of arm rests 20 such that upward motion of the release
lever 196 will raise the locking member or pin 192 from within the
opening 190 and thus permit arm rests 20 to freely rotate about the
pivot shaft 176.
In order to assure that pin 192 seats within the opening 190, a
spring 202 has one end attached to the release lever 196 and the
other end is connected to a stud 204 which is provided on the arm
rests 20. Thus, the release lever 196 is continually biased in a
counterclockwise direction about the pivot 198, as is shown in FIG.
17, such that the locking member or pin 192 is seated within
opening 190.
The transition roll 26 is best illustrated in FIGS. 1 and 5. The
transition roll 26 is a separate, pillowlike member which is formed
of resilient deformable material, such as foam rubber or the like.
The transition roll 26 is placed between the backrest 38 and the
seat rest 36, and is held in position by a support bracket 210, as
is shown in FIG. 5, and by frictional engagement with the seat rest
portion 14 and the backrest portion 16. As the backrest 38 pivots
to a reclined position, the transition roll 26 is squeezed between
the seat rest portion 14 and the backrest portion 16 so as to
provide a comfortable cushion-piece to support the occupant's lower
back portion. The transition roll 26 is unique in that no gap
exists between the lowermost portion of the backrest portion 16 and
the rearwardmost portion of the seat rest portion 14 at any time
during movement of the chair 10 to a reclined or upright
position.
In modern professional practice, it is becoming more conventional
for the dentist to be in a seated position during operation upon a
patient. As a result, the dentist's knees are located closely
adjacent to the lower rear portion of the chair 10. In order to
avoid interference with the yoke member 102, and to preclude
possible injury to the dentist, it is a feature of this invention
to provide a cover plate or shroud 215 to provide an absolutely
clear backrest free from all protrusions, thus eliminating any knee
interference. As is shown in FIGS. 1, 17 and 18, the shroud 215 is
provided with a pivot stud 216 and is pivotally mounted upon the
upstanding support members 37 at opposite sides of the rear of the
seat portion 36. As is shown in FIG. 16, a hook 220 is provided on
the shroud 215, and a spring 222 connects the hook 220 to a chair
frame extension such that the shroud 215 is biased upwardly toward
engagement with the backrest 38.
As is shown in FIG. 19, the control means 28 and 28' are mounted on
opposite side edges of the backrest portion 16. As was pointed out
above, in connection with FIG. 4, the dentist's controls 28
override commands initiated at the assistant's controls 28' so that
the dentist retains final control for moving the chair between the
upright and reclined positions.
FIGS. 20 and 21 illustrate the manner in which the head rest 24 is
adjustably mounted on the backrest portion 16. The strap 25 is
fixedly secured to a rear portion of the headrest 24, and is
provided with a weight 25'. The weight 25' and a portion of the
strap 25 are insertable within an opening 230 which is located in
the top portion 232 of the backrest portion 16. Headrest 24 is
preferably provided with a storage compartment 234 for storing a
roll of sanitary paper 236, and the paper 236 can be entrained over
the top of the headrest 24 and be fastened at the bottom of the
headrest 24 by a combined holding-and-cutting strap 238.
The dentist's controls 28 are illustrated in FIGS. 22--29. The
rocker switch 29, and the pushbutton switches 55 and 56 are mounted
upon a support bracket 250 which is fixedly secured to the
dentist's side of the backrest portion 16 by an exterior cover
plate 252 and a pair of suitable screws 254.
A feature of this invention is the provision of a leaf spring 260
which extends between the switches 45 and 56. A stop lug 262 is
centrally mounted upon the bracket 250 intermediate the switches 29
and 55. The spring 260 includes a pair of ears 264 mounted in a
pair of slots in the stop lug 262. The opposite end of spring 260
is provided with a pair of extension arms 266 and 268 which extend
on opposite side portions of a reduced portion 270 of the switch
56. A cam 272 is fixedly secured to the reduced portion 270 and is
disposed for engagement with the free edge of extension arm
268.
After the dentist has completed his work upon a patient, the
pushbutton switch 56 is depressed in order to raise the backrest 38
from a reclined toward a upright position. In order to avoid
holding the switch 56 depressed during the time that the mechanism
raises the chair to its full extent of travel, a lock pin 274, as
is best shown in FIG. 26, is fixed in casing 273 and cooperates
with a slot 275 which is provided in barrel member 276. Barrel
member 276 is lightly biased outwardly to the left, as is shown in
FIG. 26, by a spring, now shown. The finger-engaging portion of the
switch 56 is provided with a reduced section to provide a grip 278.
A knurled fitment 279 is provided with a bead 280 and frictionally
connects the grip portion 278 to the barrel 276 for movement
therewith. As the switch 56 is depressed, lock pin 274 rides in
slot 275 and, upon slight rotation of the grip portion 278 and
barrel member 276 in a counterclockwise direction, as viewed in
FIGS. 25 and 27, a shoulder 280 is positioned for engagement with
the lock pin 274 when the pressure on the switch 56 is released and
the switch 56 is biased outwardly by the spring, not shown. During
rotation of the grip portion 278 and barrel 276, the cam 272
engages the free edge portion of the extension arm 268 and distorts
the leaf spring 260 from the position shown in FIGS. 24 and 25 to
the position shown in FIGS. 26 and 27. The portion of the spring
260 near the ears 264 is precluded from movement by the stop lug
262 such that the spring 260 becomes pronouncely bowed and moved
toward contact with the finger-engaging portion of the switch 55.
The switch 56 remains in active position and the chair 10 moves
from a reclined position to a fully upright position whereupon ball
nut 100 on the screw 87 actuates the limit switch 64 so as to turn
off the motor 62. At the start of the next operation, after the
patient is seated, the switch 55 is depressed, so as to move the
chair 10 toward a reclined position, and the bowed portion of
spring 260 is flattened and causes the extension arm 268 to rotate
the switch 56 through engagement with the cam 272, and cause
shoulder 280 to become disengaged with the lock pin 274. As a
result, the switch 56 is forced outwardly, by its biasing spring,
to its inactive position. Switch 55 may also be provided with a
lock pin 282 and a slot 283, if so desired.
FIGS. 30 and 31 illustrate the controls 28' for the assistant's
side of the chair 10. Roder switch 29' is actuated to raise and
lower the chair 10, pushbutton switch 55' is actuated to move the
chair 10 to a reclined position, and pushbutton switch 56' is
pushed to raise the chair 10 to its upright position. As previously
pointed out, switches 55' and 56' can operate the chair 10 only in
the absence of an overriding signal from the dentist's switches 55
and 56.
FIGS. 32--35 illustrate a modified version of a chair, generally
indicated by the numeral 300, which includes a two-piece backrest
comprising a lower portion 304 and a separable top portion 306. The
top portion 306 is adapted to be equipped with the adjustably
mounted headrest 24 in the same manner as was described in
connection with the FIGS. 20 and 21.
The separable top portion 306 is provided with a support rod 308
which is fixedly secured thereto on brackets 310. A pair of channel
members 312 and 314 are fixedly secured to a back portion 316, and
cooperate with the plate member 318 to provide a guide slot 320
which is adapted to receive the support rod 308 therein. A stop
member 322 is pivotally mounted upon the channel member 314 by a
pivot pin 324 so that a portion of the stop member 322 extends into
the slot 320 and is adapted to engage support rod 308 and hold the
same in a vertically adjusted position. The stop member 322 carries
a strike plate 326 which is connected to a biasing spring 328
mounted upon a hook member 330 which is fixed to one of the bracket
member 314. Strike plate 326 is disposed for engagement by a
spring-loaded plunger 332 which is mounted on an upright side of
the lower portion 304. The upper portion 306 can be adjusted
relative to the lower portion 304 by depressing the plunger 332 and
moving the upper portion 306 to the desired vertical position, and
releasing plunger 332 so that spring 328 biases the stop member 322
into holding engagement with the support rod 308. From the
foregoing, it will be apparent that the chair 300 is adapted for
use with the upper portion 306 and headrest 24, and the chair 300
is also adaptable for use with previously known types of
traditional headrests. More important, should a future design of a
headrest be introduced into the profession, the removable top
portion 306 can be changed without changing the entire back.
Another feature of the chair 300 is that the backrest portion 306
may be removed, and the strap 25 of headrest 24 may be inserted
into the guide slot 320 so as to place the headrest 24 upon the
lower portion 304 and thus adapt the chair 300 for use with
children instead of adults.
FIGS. 36 and 37 illustrate a modification of the invention wherein
a pair of laterally disposed thrust bars 400 each include an inner
U-shaped channel member 402 which is nested within an outer
U-shaped channel member 404. Each of the channel members 404 is
provided with a rotatably mounted roller 406 for cooperation with
the leg rest 34. Channel members 402 and 404 are each provided with
adjustment holes 408 and 410, respectively. Suitable lock pins, or
spring-loaded catch members, not shown, are provided for placement
within aligned pairs of holes 408 and 410 for adjustably
positioning the channel member 404 with respect to the channel
member 402. As is apparent from a consideration of FIG. 37,
movement of the roller 406 from the full-line position to the
dotted line position, prior to actuation of the chair
reclining-mechanism, results in deactivating the thrust bars and
prevents upward motion of the leg rest 34 and seat rest 36.
Conversely, if it is desired to separately adjust the leg rest 34
and seat rest 36, relative to the backrest 38, channel members 402
and 406 may be unlocked from each other and channel member 404 may
be extended to the right, as viewed in FIG. 37, thus causing the
leg rest 34 and seat rest 36 to pivot upwardly.
Another modified form of the invention is illustrated in FIGS. 38
and 39. A pair of cover plates 420 are pivotally mounted to the leg
rest 34 by a pair of pivot pins 422 carried by mounting brackets
424 and overlie openings 426. With the cover plates 420 free to
pivot about the pivot pins 422, actuation of the chair reclining
mechanism causes the thrust bars 124 and 126 to raise the cover
plates 420 without any corresponding movement of the leg rests 34
and seat rest 36. Accordingly, only the leg rest portion of cushion
member 15 is raised and no movement of the seat rest portion of the
cushion member 15 occurs.
Another modification of the invention is illustrated in FIGS. 40
and 41. In this form of the invention, a separate motor and
gear-reducer 450 is mounted on the underside of the leg rest 34 and
includes a connector 452 fixedly connected to a drive shaft 454. A
pair of crank arms 456 are secured to the drive shaft 454 for
rotation therewith. A thrust bar 458 is pivotally secured, at 460
to a bracket 462 which is fixedly secured to the underside of the
leg rest 34. Thrust bar 458 is also pivotally connected to the
crank arms 456 by a pivot pin 464. When motor 450 is operated,
rotation of drive shaft 454 and crank arms 456 causes the leg rest
34 to pivot upwardly relative to pivot pin 464. If it is desirable
only to change the position of the leg rest 34, it is necessary to
remove plates 160 from the crosshead 71 so that the extension 152
of bracket 148 is free to pivot relative to the crosshead 71. As a
result, the motor 450 will cause the leg rest 34 to rotate about
pivot 150. If plates 160 are not removed, it should be noted that
motor 450 is capable of causing the chair 10 to be adjusted toward
a reclined or upright position. In such a case, motor 450 will
cause the leg rest 34 to pivot upwardly about the roller 156, thus
causing the seat rest 36 and backrest 38 to move toward and away
from the positions illustrated in FIGS. 15 and 16.
In each of the various embodiments of the invention, it is
desirable that the various linkages operate smoothly so as not to
cause patient apprehension. Accordingly, counterweight 480 is
preferably mounted upon the leg rest 34 beneath the leg rest
portion of cushion member 15, as is best shown in FIGS. 5 and 6.
The counterweight 480 compensates for any looseness in the
operating mechanisms and also assists the motor 62 during the time
that the chair 10 is being raised to its upright position.
While preferred forms and arrangements of parts have been shown in
illustrating the invention, it is to be clearly understood that
various changes in details and arrangements of parts may be made
without departing from the spirit and scope of the invention, as
defined in the appended claimed subject matter.
* * * * *