Note: Descriptions are shown in the official language in which they were submitted.
~15 7~8
1.
Adjustable support for an optical or other ins~rument.
Technical Field.
The pre.sent invention is concerned with an adjustable
S support for an optical or other instrument. More
particularly, the invention is concerned ~ith an adjustable
support which readily permits adjustment in the position of
the instrument in a predetermined spatial envelope and/or
adjustment of the orientation of the instrument at any
given position within that envelope, the support having
associated with it clamping means for maintaining the
instrument in the desired position and/or orientation~ the
clamping means being readily operated by a person using
the instrument. One ~ield of application o~ a support
in accordance with the present inv~ntion is in the
supporting of an optical ins~rument such as a binocular
microscope9 camera, television camera or the like during
delicate surgical operations, e.g. neuro-surgical
operations. During such operations a binocular
microscope may often be used in conjunction with a
television camera for continuous monitoring of the
operation by a surgeon, and a cine or still camera may
also be used for recording certain stages of the
operation for use in training medical staff.
Background Art.
With a view to meeting the requirements of surgeons, a
number of supports, some floor mounted some ~eiling
; mounted, have bePn proposed. Whilst the use of
microscopes and related optical instruments has enabled
surgeons to achieve impressive results, existing supports
still have some drawbacks. It will be understood that
the very restricted field of view when using a microscope
at high magnification necessitates its frequent movement
as an operation progresses. In some cases~ using
existing equipment, these movements are relatively
.~
~S ~f.18
2.
difficult to achieve and the time in making the necessary
adjustments may account for as much as 40 per cent of the
operating time. This is not only tiring for the surgeon
but greatly increases the chance of complications for the
patient. Therefore a need exists for a support whereby
manipulating the microscope (or other optical instrument)
requires very little effort on the part of the surgeon,
but which is capable of sustaining the instrument in the
required position without the surgeon having to remove
his hands from the operating area to effect unclamping~
adjustment, and reclamping of the apparatus~
While a number of known supports employ a combination
o~ pivotal movements and linear (e~g. sliding) movements
of component parts to provide for the desired spatial
envelope of displacements of an optical instrument, it
has been observed that, for the smoothest operation, a
system employing only pivotal movements of component parts
of the support is preferred. One such support is
disclosed in UK Patent Specification No. 1357261. In the
support disclosed in that specification a carrier for an
optical observation device such as a binocular microscope
is fixed onto an end member of a linkage rotatably
mounted on a socket by means of a column, the said end
member being spatially freely movable as a result of the
combination of rotary movements possible about at least
three axes. Furthermore, in the support disclosed in
said specification, the orientation of the optical axis
of the observation device may be adjusted by means of a
triple axis fully universal linkage which enables freely
combinable rotation thereof in three mutually perpendicular
and intersecting directions by a handgrip, this linkage
being effective to fix the carrier on the end member of
the linkage referred to in the previous sentence. In
the support disclosed in said specification a number of
blocking devices are provided for clamping the carrier
for the optical observation device in its desired spatial
position and/or orientation, there being three of these
blocking devices associated with bearings of the triple
48
3.
axis rully universal linkage and three more associated
with bearings of the linkage rotatably mounted on said
socket. The blocking devices are of the electromagnetic
type, being rendered operative by the passage of electric
current through coils of the blocking devices. When the
surgeon wishes to adjust the position and/or orientation
of the optical instrument supported on the support
disclosed in said speci~ication he actuates a switch
mounted on a handgrip associated with the carrier for
the instrument to effect either a complete de-energisation
of the electromagnetic coils of the blocking devices or
an intermittent de-energisation thereof. Counterbalancing
means, comprising a weight adjustably mounted on an
extension of one of the links of the linkage rotatably
mounted on said socket, is provided to counterbalance
gravity-produced turning moments of the entire stand in
respect of the rotation axis of a parallelogram linkage
to a column which is rotatable about said socket.
Furthermore, by adjustment of the optical instrument on
its carrier, compensation of gravity-produced turning
moments of the triple axis fully universal linkage and of
the optical instrument about the common intersection
point of the three rotation axes is possible. These
counterbalancing facilities seek to avoid unwanted
movements of the optical instrument when the blocking
devices are released.
While a support as disclosed in said specification
goes some way to meeting the requirements of surgeons
employing optical instruments such as a binocular
microscope to assist them during delicate operations we
have found it possible to effect further improvements in
a number of respects.
~ he triple axis fully iniversal linkage of the
support disclosed in said specification is a complex
arrangement reyuiring many parts and a total of three
blocking devices associated one with each of the pivots
providiny fox rotation about said three axes. It occupies
a considerable amount or space in the vicinity of the
~ :1 5 7 L~
4.
observation point and counterbalancing adjustments
necessitate adjustment of the position of the optical
instrument itself on its carrier. Furthermore, in the
event of failure of the electrical supply, the blocking
5- devices are unclamped permitting undesired free movement
of the optical instrument.
Various objects of the invention are to overcome, or
minimise, these disadvantages and provide an improved
support which is compact, relatively inexpensive to
10 manufacture, easy to adjust, and incorporates a high
degree of safety in use.
Disclosure of i_ en_ion.
The invention provides an adjustable support for an
optical or other instrument, which support permits
adjustment of the position of the instrument in a
predetermined spatial envelope and/or adjustment of
the orientation of the instrument at any given position
within that envelope, said support comprising an
instrument carrier which is mounted on a linkage system
20 rotatably su~ported about a column and constructed and
arranged to provide for adjustment of the position of
an instrument carried by the instrument carrier in said
spatial envelope, characterised in that the instrument
carrier comprises an elongated rod-like member extending
through and secured to a ball of a ball joint arrangement
a ball supporting member of ~hich is mounted on said
linkage system, in that counterbalancing means is
adjustably mounted on the rod-like member at an end
portion thereof remote from that at which the instrument
is supported, and in that the ball joint arrangement has
associated therewith clamping means which normally
clamps the ball against rotation relatively to said ball
supporting member but ~hich may be caused to unclamp the
ball on actuation of a switch (or like) device.
Preferably, in an adjustable stand as set out in the
last preceding paragraph, said counterbalancing means
comprises a weight and means for adjusting the position
of the weight along three mutually perpendicular axes
~ ~ 5 ~ L~ 8
5.
relatively to said rod~ e member, one of said axes
being parallel to the lengthwise direction of that member.
Such an a~rangement -Facilitates adjustment of the weight
into a position in which the centre of gravity of the
particular instrument(s) carried by the instrument carrier,
the supporting parts and the counterbal.ancing means,
coincides with the centre of the ball of the ball joint
arrangement so as to avoid uncontrolled movement of the
parts about the ball centre when the clamping means is
unclamped. The cotmterbalancing means thus enables
adjustments of the position of the centre of gravity of the
components just above referred to to be made (for e~ample,
when one instrument is exchanged for anothex of dif~erent
mass and configuration) or when an additional instrument
is added to the instrument carrier) without the necessity
for adjusting the position of the instrument(s) relatively
to the carrier.
In an adjustable support as set out in the last
preceding paragraph but one, the ball of said ball joint
arrangement is preferably supported on an annular face of
a ball-supporting member~ and the clamping means comprises
a brake ring which overlies the ball supporting member and
has an inclined face which surrounds an upper portion of
the ball and is urged into clamping engagement therewith
under the action of spring means, a fluid pressure
operated piston arrangement being arranged to act on an
under side of the brake ring to overcome the action of
the spring means on actuation of said switch device. The
piston arrangement conveniently comprises an annular
rubber U-ring type piston which is housed within an annular
channel formed in an upper surface of the ball supporting
member to which channe.l air under pressure may be admitted
under the control of a valve arrangement actuated by said
switch-device.
One field in which an adjustable support in accordance
wlth the invention is li}~ely to be particularly useful is
that of neurosurgery especially when delicate operations
are to be performed on the brain. Sometimes such
~ 1~7'~8
6.
operations are performed with the patient lying on an
operating table, in others the patient may be supported
in a sltting position, particularly if the surgeon is tall.
With a view to permitting observation of any part of the
brain under these conditions it is desirable that -the
optical instrument is capable of spatial movement in an
envelope in the form of a hemisphere ahout the head of
a patient, and that this hemispherical envelope is capable
of being described at a considerable range of vertical
levels to take account, for example, of a wide range of
heights of surgeons and other observers.
With a view to providing, as nearly as practicable~
for the desired range of displacements of an optical
instrument carried by an adjustable support as set out
in the last preceding paragraph but three, preferably the
linkage system on which the ball joint arrangement is
mounted comprises a first carrier arm an outer end portion
of which carries the ball supporting member and an inner
end portion of which is pivotally supported for rotation
about a first axis provided by a first joint arrangement
which is supported by an outer end portion of a second
supporting arm, an inner end portion of the second
supporting arm being pivotally mounted, about a second
axis arranged trans~ersely to the first axis, by a second
joint arrangement on a turret rotatably mounted about said
column by means of a third joint arrangement providing a
third axis parallel to the first axis. It will be
appreciated that, with an arrangement as just described,
heightwise movements of an instrument carried by the
adjustab].e stand are effected as a consequence of pivotal
movement of the second supporting arm about said second
axis, while movements in a horizontal plane are effected
as a consequence of pivotal movements of one or both of
the first and second supportiny arms about the first and
third axes respectively.
With a view to avoiding undesired angular movements
of an instrument carri.ed bv an adjustable support as set
~1S ~ 8
7.
out in the last preceding paragraph but four and organised
as set out in the last preceding paragraph, the second
supporting arm pre~erably forms part of a parallel linkage
arrangement which is arranged, during pivotal movement of
the second supporting arm about said second axis, to
maintain said first axis in an at least substantially
vertical ~isposition.
While an adjustable support as set out in the last
preceding Paragraph but five and organised as set out in
10 the last preceding paragraph but one may have said column
suppoted by the floor or from the ceiling, preferably
the column forms part of a trolley by which the support
may be moved from one location to another9 for which
puxpose conveniently the trolley is mounted on castoxs
~5 and is provided with supporting pads coupled with a trolley
handle for moving the trolley in such manner thatg when
the handle is moved to one position, the supporting pads
are lowered to engage the floor and take the weight of
the support, while, when the handle is moved to a second
position, the pads are raised to permit movement of the
trolley on the castors by pulling or pushing the handle.
In view of the fact that, as mentioned in the opening
paragraph of this specification, it is often desirable tG
utilise a plurality of optical instruments simultaneously
. 25 for various observations during a delicate surgical
; operation, an adjustable support as set out in the last
preceding paragraph but six and organised as set out in
the last preced.ing paragraph but two is preferably provided
with second adjustable counterbalancing means for counter-
balancing turning moments of the second supporting arm
and parts supported thereby about said second axis, and,
with a view to avoiding the need oE having relatively
heavy weights supported on an extension o~ said second
supporting arm (with consequent danger of collision of
such weights with other objects or persons i.nvolved in
the operation when the position of the instrument(s) is
moved, particularly about said second or third axes)
~ ;~ 5 ~ ~ L~l ~
preferably the second counterbalancing means comprises a
tension spring housed within the column and connected at
one end portion, by connecting means, for example a cable,
to a mem~er adjustable lengthwise of an extension of the
second supporting arm which extends be~ond the second axis,
and, at the other end portion, to tension adjusting means
by which the spring is anchored in the column. The use
of such a spring arrangement also reduces quite materially
(as compared with the use of counterba:Lancing weights) the
inertia to be overcome in making adjustments to the
position of the instrument(s) which involve pivotal
movements about the said second and ~hird axes.
With a view to maintaining an instrument carried by
the instrument carrier in a desired position between
successive adjustments, an adjustable support as set out
in the last preceding paragraph but seven and organ:ised as
set out in the last preceding paragraph but three is
preferably provided with clamping means associated with
each of said first9 second and third joint arrangements ~or
restraining pivotal movement of a first joint member
relatively to a second joint member, each of said clamping
means being arranged to be unclamped by the admission of
fluid under pressure to these clamping means under the
control of a switch device operable when it is desired to
adjust the position of an instrument supported by the
support~ Conveniently, each of the clamping means
associated with the first, second and third joint
arrangements comprises a tapered annular surface associated
with one of the joint members and a brake ring associated
with the other one of the joint members and having a
tapered surface movable into wedging engagement with that
on the first mentioned joint member under the action of
spring means and the admission of fluid under pressure to
the clamping means causes a piston to act on the brake ring
in opposition to spring means when it is desired to urge
the brake ring out of clamping engagement. Furthermore,
to facilitate adjustment both of orientation of the
instrument(s) ~arried by the instrument carrier and of the
~ ;~S7~
9.
spatial position of the instrument(s), it is convenient
to arrange that each of the clamping means associated with
the first, second and third joint arrangements is
unclamped by the admission of air under pressure under
the control of a valve arrangement which is actuatable
by the switch device by which the clamping means associated
with the ball joint arrangement for the instrument carrier
is actuated. Such switch device may be mounted on a
handle on the instxument carrier, or may be foot operated,
or mouth operated.
From what has been said hereinbefore it will be
appreciated that an adjustable support in accordance with
the invention is likely to possess a number of advantages
over supports currently available. For example, it may
be pointed out that the ball joint arrangement of an
adjustable support as set out in the last preceding
paragraph but eight provides a relatively inexpensiveJ
simple and compact arrangement, for permitting a substantially
universal movement of the instrument carrier about a centre
(provided by the centre of the ball) as compared, for
example, with the triple axis linkage of the support
disclosed in said UK patent specification No.1357261
which necessitates a number of specially shaped component
links which, toge-ther, occupy a considerable space around
the observation point. Furthermore, with the ball joint
arrangement only one clamping means is re~uired to hold
the carrier in its desired orientation instead of the
three clamping (or blocking) devices required with the
triple axis linkage of the support disclosed in the said
specification, As for the clamping means referred to
in the last preceding paragraph and in the last preceding
paragraph but six respectively, it will be appreciated
that they are of the "fail~safe" type so as to leave the
various components clamped in the event of failure of
the supply.
There will now be given, with reference to the
accompanying drawings, a more detailed description of an
~ ~ ~7~8
adjustable support which is illustrative of the invention.
It is, however, to be clearly understood that the
i:Llustrative support is selected for description by way
of exemplification and not by way of limitation of the
inventionO
Brief description of the drawings.
In the accompanying drawings:-
Figure 1 is a general, somewhat schematic, view of theillustrative support, mainly in right hand side
elevationg but with some parts broken away;
Figure 2 is a side elevation view of first counter
balancing means and a ball joint arrangement for an
instrument carrier;
Figure 3 is a viewy partly in front elevation and
partly in section on the line III - III in Figure 2;
Figure 4 is a section on khe line IV - IV in
Figure 2;
Figure 5 is a section on the line V - V in Figure 3;
Figure 6 is a view showing, largely in section, a
first joint arrangement by which a carrier supporting arm
is pivoted on a second supporting arm;
Figure 7 is a view of said first joint arra~gement,
chiefly in section on the line VII - VII in Figure 6,
showing also, from beneathJ a portion o the first
carrier supporting arm and the ball joint arrangement;
Figure 8 is a detail view chiefly in section on the
line VIII - VIII in Figure 6;
Figure 9 is a vie-w partly in section on the line
IX ~ IX in Figure 7;
Figure 10 is a view, in side elevation with some
parts broken away, showing a second joint arrangement
between the second carrier supporting arm, a tie rod,
and a turret head;
Figure 11 is a view, chiefly in end elevation, but
partly in section on the line XI - XI in Figure lO, of
the second joint arrangement and associated parts; and
Figure 12 is a view, partly in elevation and partly
~ 157~
11 .
in section on the line XII - XII in Figure l and looking
in the direction of the arrows, of a third joint
arrangement, and clampin~ means associated therewith, by
which the turret head is rotatably mounted on a column
of a trolley of ~he illustrative support.
Best mode of carrying out the invention.
The illustrative stand is arranged to support an optical
instrument, such as a binocular microscope suitable for use
as an aid to surgery9 in such manner that the optical
instrument may be readily moved, by a surgeon performing
a surgical operation, from one position to another within
a desired envelope, and/or adjusted to direct its optical
axis in a desired orientation, and may then be clamped in
the desired position/orientation without the expenditure
of any great effort.
With these and other objectives (to be mentioned
hereinafter) in mind, the optical instrument such as a
binocular microscope M (Figure 1) is attached, in any
convenient manner, to a lower end portion of an elongated
rod-like carrier, conveniently provided by a shaft 10,
which extends through a ba~l 12 (and is rigidly secured
thereto) of a ball joint arrangement 14, a ball supporting
member of which is mounted on a linkage system rotatably
supported on a column 30. The linkage system is
constructed and arranged (as will be hereinafter described)
to provide for adjustment of the position of an instrument
carried by the instrument carrier in the desired spatial
envelope. The ball joint arrangement facilitates
adjustment of the orientation of the instrument carried
by the instrument carrier at any given position within
the spatial envelope just referred to. The linkage
system sUppOrtinCJ the ball joint arrangernent comprises
a first carrier supporting arm 16 on an outer end portion
of which said ball supporting member is carried and which
is pivotally supported, at its inner end portion, for
rotation about a rlrst axis A which is provided by a
first joint arrangement 18 which is supported by an
1 :~ 5'~
12.
outer end portion of a second supporting arm 20. An inner
end portion of the arm 20 is pivotally mounted for movement
about a shaft 22 of a second joint arrangement 23 mounted,
as hereinafter described, in a turret 2~, the shaft 22
providing a second axis B, which is arranged transversely
with respect to the first axis A but considerably displaced
therefrom. As will be seen from Figure 1 the second axis
B is arranged to be horizontal so that the pivoting of the
arm 20 about -the shaft 22 provides for raising or lowering
of the joint arrangement 1~ and hence of the carrier 10
and apparatus supported thereby.
The arm 20, and the tie rod 26 arranged parallel with
the arm 20, provide a parallel linkage arrangement which
will be hereinafter described, the func-tion of which is to
maintain the~first axis A in a vertical direction during
heightwise movements o~ the joint arrangement 18~ arm 16
and parts supported thereby. The turret 2~ is itself
mounted for pivotal movement about a third axis C of a
third joint arrangement 28 supported by an upper end
portion of the column 30, the axis C being also vertically
disposed (as seen in Figure 1). As will be hereinafter
described, the column 30 forms part of a trolley 32 by
which the stand can be readily moved from one location
to another.
The illustrative stand also includes first counter-
balancing means for counterbalancing the weight of the
optical instrument about the ball 12 and second counter-
balancing means for counterbalancing turni~g movements
of the arm 20 and parts supported thereby about the axis
provided by the shaft 22. The first counterbalancing
means comprises a weight W and means (hereinafter described)
for mounting the weight on an upwardly extending portion
of the carrier shaft lO (i.e. at an end portion remote from
that at which an instrument is supported) with provision
for adjusting the position of the weight along three
mutually perpendicular axes so that the centre of gravity
o~ the optical instrument supported on the carrier shaft,
the supporting parts and the first counterbalancing means
~ :I S'~
13.
can readily be adjusted to coincide with the centre of the
ball 12 of the ball joint arrangement. This facility is
desirable when instruments of different mass and
configuration are supported by the carrier shaft 10. The
5- second counterbalancing means comprises a tension spring
300 housed within the column 30 and connected, at an upper
end portion, by means of a cable 34 to a block 36
adjustable lengthwise of a portion of the arm 20 which
extends, to the right as shown in Figure 1, beyond the
shaft 22. A lower end portion of the spring is anchored
in the column by means for adjusting the tension exerted
by the spring.
Clamping means is pxovided (as will hereinafter be
described) ln association with the ball joint arrangement
14, and ~ith each of the first~ second and third joint
arrangements, 18, 23 and 28 for retaining the optical
instrument in a desired position and/or orientation, the
clamping means being arranged to be unclamped by the
application of pneumatic pressure under the control of a
switch device operable by the surgeon when he desires to
adjust the position and/or orientation of the optical
instrument. A fail-safe arrangement is thus provided
whereby in the event of failure of the electrical or
pneumatic supply, the clamping means remains in the
clamping position to prevent inadvertant movement of the
stand or instrument(s) carried thereby.
The various portions of the illustrative stand will
now be described in greater detail.
Fixedly secured, as by welding for example, to the
upper end portion of the carrier shaft 10 is a locating
sleeve 40 (see Figures 3 and 4) which is shaped to provide
guiding surfaces extending axially of the shaft 10. As
shown in ~igure 4 the locating sleeve 4~ may conveniently
be of hexagonal cross section providing six guide surfaces
42 on which is slidably fitted corresponding inner faces
of a sleeve-like slide 44 an upper portion of which has a
cylindrical outer surface 47 while a lowex portion 45 is
threaded to engage with an internally threaded adjusting
1~ .
sleeve 46 (see also Figure 2). A disc 48 (Figure 3) is
secured to a lower end portion of the loca-ting sleeve ~0
and a shoulder 49 formed internally at a lower end portion
of the adjusting sleeve 46 rests on the disc 48, being
retained thereagainst by a circlip 50. The adjusting
sleeve is thereby res-trained against axial movement with
respect to the carri.er shaft 10 but may be rotated
therearound to move the adjusting slide 44 a~ially of
the shaft, such movement being limited in an upwards
direction (as viewed in Figure 3) by engagement of the
upper end of the portion 45 with a screw 52 extending
through an upper end portion of the adjusting sleeve 46.
A block 54 has a depending stem portion which is
received within and secured to an upper end portion of
the adjusting slide 44 and an elongated box-like guide
member 56 (see Figures 2 and 3) is clamped to the block
54 by a clamp 58 and screws 60. The lengthwise dimension
of the guide member 56 extends perpendicularly to the axis
of the carrier shaft 10~ Slidably received on the guide
member 56 is a carrier 62 which is secured, by a screw 64,
to a block 66 (see also Figure 5) slidably received within
the guide member 56, the screw 64 extending through a slot
68 extending lengthwise of the guide member. A threaded
rod 70 is rotatably mounted in bearing blocks 72, 74
secured within the guide member 56 (the rod being held
against axial movement relatively to the block 74 by means
of a flange 76 on the rod 70 and a washer and locknut
arrangement 78) and has threaded engagement within a bore
in the block 66. Rotation of the threaded rod 70, by
means of a ]~nob 80 on one end thereof, causes the block 66
to move lengthwise of the guide member 56 similarly to move
the carrier 62. The block 54 (see Figures 2 and 3) is
provided with grooves 55 to perm.it the passage of inwardly
directed flange portions of the carrier 62 therepast. The
carrier 62 h~s secured thereto a second elongated box-like
guide member 82 the lengthwise dimension of which extends
perpendicularly to the plane containing the axes of guide
member 56 and of the carrier shaft 10. The counterweight
L~
5 .
W is guided for movements lengthwise of the guide member ~2
and is secured by a screw 84 (extending through a slot 85
in one wall of the guide member 82) to a block 86 slidably
received within the guide member 82 and threaded onto a
threaded rod 88 rotatably mounted in bearing blocks 90~ 92
secured in opposite end portions of the guide member 82.
Knobs 94 are provided at each end of the threaded rod for
adjustment of the counterweight along the guide member ~2.
The ball 12 of the optical instrument carrier 10 is
supported upon an inclined annular face 104 of a ball
supporting member 102 (as shown in Figure 9)Y The member
102 is flxedly secured to an outer end portion of the
first carrier-supporting arm 16 which is fabricated from
sheet metal into an elongated hollow rectangular boxlike
form. The ball supporting member 102 is cut away to
pro~ide a shallow conical face 106 to permit the sha:Ft 10,
and hence an optical instrument supported thereonJ to
partake of a wide range oE angular mo~ement of adjustment.
Associated with the ball joint arrangement is a clamping
device comprising a brake ring llO ha~ing an internal
inclined surface 112 which surrounds an upper portion of
the ball 12 and is arranged to engage the ball surface
with a wedging action firmly to clamp the ball and parts
supported thereby in any desired position relati~ely to
the ball supporting member 102, for which purpose an upper
recessed surface 114 of the ring 110 is acted upon by a
series of disc springs 116. A key 118, received in
recesses in the ring 110 and in a peripheral upstanding
wall 120 of the ball supporting member 102, holds the ring
110 against rotation. The springs 116 are retained in
place by a locking ring 122 comprising an internal circlip
received in an annular yroo~e in the wall 120. The
clamping de~ice is unclamped to permit movement of the
ball 12 by the action of pressurised fluid (in this case
compressed air) on an annular rubber U-ring type piston 124
housed within an annular channel 126 formed in an upper
surface of the ball supporting member 102 just below an
underface of the brake ring 110. Air under pressure
16.
may be admitted via an inlet passage 128 which extends
through the member 102 and opens into the channel 126
beneath the U-shaped cavity in the piston 124 to cause
the piston to raise the brake ring against -the action of
5 the springs 116. A flexible protective rubber cover 130
seals the upper side of -the ball joint arrangement. A
flexible hose 132 supplies compressed air (under the
control of a valve arrangement hereinafter referred to)
to the inlet passage 128 when desired.
An inner end portion of the carrier arm 16 is
reinforced at 109 (Figure 6) and is secured (as by welding~
to a lower end portion of a hollow shaft 134 forming part
of the first joint arrangement 18. ~ower and upper ball
bearings 136, 13~ surround the shaft and are spaced apart
1~ by a spacing sleeve 140. A retaining ring 142 holcls the
ball races in place upon the shaft as shown in ~igure 6.
'~le ball bearings 136, 138 are respectively seated against
shoulders 147 and 149 formed in an internal wall of a
sleevelike bearing housing 144, lower and upper end portions
of which are secured, conveniently by welding, to lower and
upper end plates 146 and 148. ~ridging the end plates
and securely fixed thereto is a face plate 150 provided
with a pair of flanges 151 which extend lengthwise of the
bearing housing and to the right as viewed in Flgures 6
and 7. By these flanges the first joint arrangement is
pivotally connected with outer end portions of the
supporting arm 20 and the tie rod 26. The bearing
arrangement just described permits free pivotal movement
of the first carrier supporting arm 16 relatively to the
bearing housing 1~4 but restrains it against heightwise
(axial) movement relatively thereto.
To clamp the sha~t 134 against pivotal movement
relatively to the housing 144 at all times except when
it is desired to free it for adjustment of the position
of the optical instrument supported by the carrier arm 16,
a clamping device is provided. This clamping device
comprises a base member 152 which is secured, by screws 153,
to the upper end plate 148 of the bearing housing and
~ :~S7'~8
surrounds an upper end portion of the shaft 134 which is
provided with an external tapered surface 154 extending
upwardly beyond an upper surface of the base member 152
over which extends a brake ring 156. I'he brake ring has
a tapered bore providing an internal inclined surface 158,
the inclination of which corresponds to that of the
surface 154 of the shaft 134. A series of disc springs
160 act on an upper face of the brake ring 156 and are
retained in position by a locking ring 162 received in an
annular groove in a wall portion 164 of the base member
152, the thrust of the springs being effective to urge the
brake ring into clamping engagement with the surface 154
of the shaft 134. The brake ring 156 is restrained
against rotation relatively to the base member 152 by
means of a key (not shown). The clamping device just
described is unclamped by the action of compressed air
(supplied via an~nlet passage 165 from a hose 163) on
an annular rubber piston 166 housed in an annular channel
168 f ormed in the upper face of the base member 152, the
action being generally similar to that of the clamping
device associated with the ball 12 of the carrier 10
hereinbefore described. A cover 170 (conveniently of
sheet metal or plastic~ is provided for the joint
arrangement just above described.
Rotatably moun~ed in bush bearings provided in
bearing housings 172 (Figure 7) secured (e.g. by welding)
in aligned bores in the flanges 151 is a lower pivot pin
174 which is pinned in a sleeve 176 which extends between,
and is secured to, opposite side walls of the second
supporting arm 20. The outer end portion of the tie rod
26 is provided with a part spherical rod end bearing 178
(Figures 6 and 8) through which extends an upper pivot
pin 18OJ the inner member o~ the bearing 178 being
located between two spacing sleeves 182 surrounding the
pin 180. The pin ~80 is housed in aligned bores in the
flanges 151 and secured in place by screws 184 and
associated washers.
1 1 5 7 '.t ~ 8
18.
The second carrier supporting arm 20 is rigidly
secured to the shaft 22 of the second joint arrangement 23
(see Figure ll), the shaft extending from both sldes o~
the box-like structure forming the arm 20 into bearings 190
and associated clamping devices, one of which is shown,
partl~ in section, in Figure ll. The other is like it
but a mirror image thereof. An inner race of each bearing
190 is clamped between a shoulder on a bearing spacer 192
and an inner face on a lock wedge member 194 which is
keyed to an outer end portion o~ the shaft 22. A washer
196 secured against the end of the shaft by a screw 198
(see also Figure lO) clamps the parts 1~4 and 192 together
against a shoulder formed on the shaft 22 (see Figure 11).
The other race of each bearing l90 is received in-a
central bore in a bearing housing block 200~ and is
retained therein by a circlip 202 and a shoulder formed
in said bore.
The two blocks 200 are secured on the turret 24 by
means of screws 204. Each lock wedge member 194 has an
inclined circumferencial face 206 on which rides a
correspondingly inclined face 208 of a brake ring 210.
As in the clamping devices above described, the brake ring
210 is held against rotation relati~ely to the block 200 by
means of a key (not shown) and is urged in a direction to
e~fect clamping of the shaft 22 (as a consequence of the
wedging action of the faces 206~ 208) by a series of
spring discs 212 retained in place by a circlip 214 (see
also Figure lO)received within an annular groove in a wall
portion 216 (Figure 11) of the block 200. An annular
30 rubber piston 218 housed in an annular channel 220 in the
block 200 is provided for moving the brake ring 210
against the action of the springs 212 when compressed air
is admitted to the channel 220 through a passage (not shown)
when it is desired to unclamp the shaft 22.
An inner end portion of the tie rod 26 is secured, by
means of a bolt 224 (Figure 11), to a forked member 226
pivotally mounted on a pivot pin 228 opposite end portions
1 ;~ C '~ L~ %
19.
of which extend through arcuate slots 229 in walls of the
arm 20 and are secured in blocks 230 supported by the
bearing housing blocks 200. The slots 229 are concentric
with the axis of the shaft 22. The axes of the pivot pins
5 174, 180 (Figure 6) and the pivot pin 228 and shaft 22
(Figure 11) are all parallel and are so spaced that the
arm 20, link 26 and their anchorages provide a parallel
linkage system, as above mentioned, which is arranged to
maintain the axis of the shaft 13a~ (Figure 6) vertical
lO during heightwise movements of the optical instrument
carrier 10, so that the orientation of the optical
instrument supported by the carrier shaft lO does not
change during such heightwise movement.
The turret 2~ iS fabricated from sheet metal and
15 comprises spaced parallel outer walls 240 and inner walls
242 (Figure 11) which are connected together by a base
portion 244 and two top members 246. The bearing housing
blocks 200 are carried by the top members 2~6, while the
base portion 24-4 is secured (as by welding) to a plate 2~8
20 which is, in turn, secured to a flange 250 (Figure 12) of
a hollow shaft 252 the axis of which is disposed vertically
and is part of the third joint arrangement 2~ by which the
turret is rotatably mounted on the column 30 of the txolley
32. The shaft 252 iS rotatably mounted in ball bearings
25 254, 256 supported in a bearing housing sleeve 258 having
upper and lower flange members 260, 262. Circlips 264,
266 retain the bearings in place in the bearing housing
while a circlip 268 received in an annular groove in the
shaft 252 engages the lower ball bearing 256 to restrain
30 the shaft against axial movement. The upper flange
member 260 iS received within an upper end portion of the
column 30 and is secured thereto by a clamping ring 270,
the column 30 being hollow and fabricated from sheet metal.
The lower flange member 262 iS secured to a base member 272
35 which surrounds a lower end portion of the shaEt 252 and
forms part of a clamping de~rice ~or holding the shaft
against rotation. The base member 272 is pro~ided with
,
~S 7~
20~
downwardly extending lugs 274 which are secured, by
brackets 276, to wall portions or the column 30. The
clamping device ~or the shaft 252 is generally similar to
those above described and comprises a brake ring 278
having an internal tapered surface 280 co-acting with a
similar tapered surface 282 formed on the sha~t 252.
Spring discs 2849 supported by a circlip 286, urge the
brake ring upwardly to clamp the shaft 252 against
rotation, and a rubber ring piston 288 housed in an
annular channel 290 in the base member 272 is acted upon
by compressed air supplied to the channel 290 (through a
passageJ not shown) when it is desired to unclamp the
shaft for rotation relatively to the column 30.
m e second counterbalancing means for counterbalancing
the turning movements of the arm 20 and parts carried
thereby about the axis of the shaft 22 comprises a
tension spring 300 (Figure 1) housed within the column 30
and anchored, at a lower end portion, to spring tenSiQn
adjusting means comprising a collar 302 threaded onto
a threaded rod 304 rotatably mounted in a plate 306 secured
in the coll~mn 30. An upper end portion of the spring 300
is connected to a double cable 34 which extends through the
hollow shaft 252 of the turret and passes o~er a pulley 310
rotatably mounted on a cross-shaft 311 in the turret (see
Figure 11). An upper end portion of the cable 34 (see
Figure lO) is connected, by a link 312 and a pivot pin 314a
to a lug 316 depending from the block 36 which is slidably
mounted between guide bars 320 and 322 secured to end
plates 324 and 326 which guide bars extend parallel to the
lengthwise dimension of the arm 20 and are secured by
screws 323 to a right hand end portion of the arm as seen
in Figure 10. The block 36 is threaded on to a
threaded rod 328 extending parallel to the guide bars 320
and 322 and rotatably mounted in the end plates 324 and
326 and held against axial movement by a circlip 330 and
and a collar 332 adjacent a head portion 333 of the
screwed rod by which it may be rotated to adjust the block
~S7~1~
21.
36 along the arm 20. The arrangement just above
described provides a coarse adjustment of the counter-
balancing action of the spring 300 (by rotation of the
threaded rod 304 of the tension adjusting means, see
Figure 1) and a fine adjustment (by means of the threaded
rod 328, see Figure lO). Conveniently7 the tension
adjusting means is set with the block 36 at the mid point
of its travel and an instrument of average mass supported
by the carrier shaft 10. When the instnlment is changed
for one of a different mass (or when an additional
instrument is added or removed) the change in mass may
usually be counterbalanced merely by adjustment of the
fine adjustment on rotation of the threaded rod 328 to
re-adjust the position of the bloc~ 36.
A base portion of the trolley 32 may conveniently be
formed to house any necessary electrical components such
as trans~ormers 9 rectifiers~ relays and the like to
provide low voltage supplies for lighting or other
equipment with the optical instrument in use or for other
20 .purposes. Outlet sockets and switches may be provided
for example on a panel (not shown) beneath the arm 16.
The base portion of the trolley may also conveniently
house any necessary valve arrangements associated with
control equipment for the clamping devices, and connections
wherehy the stand may be connected to a "mains" supply of
electricity and compressed air. Cables and hoses within
the stand pass from the trolley base portion up the inside
of the column 30, through the hollow shaft 252 of the
turret and thence through a ducting 334 (Figures 6 and 10)
with.in the arm 20, through a gro~met 336 in the cover 170
(Figure 6), via the hollow shaft 13~ and thence, through
an aperture 33~ therein, into the hollow arm 16.
As indicated in Figure 1, the trolley is provided with
castors 340 and is pre~erably provided with supporting pads
(not shown) which are coupled in well known manner, with a
trolley handle (not shown) so that, when the handle is
raised~ the suPPorting pads are lowered to engage the
~ ~ S ~ L~
22.
floor and take the weight of the stand, while, when the
handle is lowered ! the pads are raised to permit movement
of the trolley on the castors 340 by pulling or pushing the
handle. The base portion of the trolley may be weighted
5 as necessary to ensure the desired stability when the
carrier arms 16 and 20 are in positions giving maximum
reach of -the microscope or other optical instrument(s)
mounted on the carrier 10. The provision of a handle
arrangement for moving the trolley as just described
10 avoids the need for moving the stand by the application
of ~orce to upper portions of the column or turret and
thus tends to avoid instability problems such as are found
with certain known stands.
The supply of compressed air to the various clamping
15 devices is conveniently controlled by a single ~alve
arrangement situated in the base of the trolley - for
example an electromagnetic valve arrangement operated by a
switch device (not shown) which may be conveniently located
on a handle 350 associated with the carrier 10 by ~hich
20 handle the position and/or orientation of the optical
instrument supported by the carrier 10 may be adjusted.
Alternatively the switch device may be a foot operated
switch or a mouth operated switch suspended on the
carrier 10. Thus only one switch device is required to
25 unclamp simultaneously all the clamping devices.
A sensing device (not shown) associated with the
second counterbalancing means is so organised that, in the
event of loss o~ tension (e.g. by breakage of a part) in
the system comprising the spring 300 and parts by which
30 it is connected to the column 30 or the extension of the
arm 20, the supply of compressed air i9 dumped so that,
despite actuation of the switch device just above re~erred
toJ the various clamping devices remain c~amped (or move
to clampiny position if the switch device is in its
35 actuate~ po6ition at the time the loss in tension occurs).
