Medical instrument support mechanism

A medical instrument support mechanism, particularly suitable for ophthalmological instruments, including first and second support arms and a suitable base member in which the first arm is vertically pivotal with respect to the base member and the base member is pivotal with respect to another support member, such as a support pole. The second arm is also pivotally connected to the first arm. A locking mechanism is operatively connected to each of the pivot connections to allow an operator to selectively lock and unlock the pivot connections substantially simultaneously by operating a lever movable in a direction extending along the length of the first support arm. This lever is preferably disposed along a lower side of the first support arm and specifically operates screw locking mechanisms and respective clamp members.

FIELD OF THE INVENTION 
This invention generally pertains to medical instrument support apparatus 
and, more particularly, to instrument support mechanisms that are used to 
hold ophthalmic or optical instrumentation to allow easy movement between 
different positions relative to a patient. 
BACKGROUND OF THE INVENTION 
Many different types of instrument support mechanisms exist in the medical 
industry for supporting medical instrumentation in front of a patient. 
Often, the patient is seated in an examination chair. As examples, 
ophthalmic instruments such as slit lamps, indirect ophthalmometer and 
vision tester must be placed in front of a patient during eye examination 
procedures while the patient is seated in an examination chair. These 
instruments are typically placed on a movable table or on movable 
instrument support arms mounted adjacent the patient. Instrument support 
arms are generally attached to support poles forming part of an instrument 
stand. In some systems, two arms may be used with one arm supporting 
lighter weight instruments and the other arm supporting heavier weight 
instruments. Heavier weight instrumentation may also be supported on the 
movable tables mentioned above. 
Support mechanisms that have taken the form of arms which move with 
multiple degrees of freedom. A typical support mechanism may, for example, 
rotate about the support pole and move up and down along the support pole. 
The mechanism may also have a first arm which adjusts vertically using a 
pivotal motion and have a second arm at an outer end which is pivotally 
connected to the first arm. Additional arms or support structure may be 
connected to the arms. 
Each of the above described movements should be lockable such that a 
practician may set the mechanism and, therefore, the attached 
instrumentation in the desired location relative to the patient. Certain 
instrument arms are not lockable, however, this is not desirable in many 
situations. Most arms in the past have required at least two separate lock 
mechanisms and two separate manually operated levers or knobs to lock and 
unlock the various pivot connections of the mechanism. This makes locking 
and unlocking the mechanism cumbersome and often difficult for the 
practician. One known type of instrument support mechanism does include a 
single lever for locking and unlocking the three main pivoting movements 
described above. However, this lever must be rotated generally in a 
direction perpendicular to the mechanism. Therefore, the practician must 
use two hands to hold the mechanism against rotation about the support 
pole while rotating the lever to lock the mechanism in place. The same 
holds true when unlocking the mechanism. Also, the levers and knobs as 
previously located on such mechanisms may not be easily accessed or 
actuated by the practician. 
For the reasons stated above as well as other reasons, it would be 
desirable to provide an adjustable medical instrument support mechanism, 
and especially a mechanism suitable for use in the ophthalmic area, in 
which a simplified and easily actuated locking mechanism is used and 
includes a single lever which may be actuated in a simple motion to either 
lock or unlock various pivot connections of the support mechanism. 
SUMMARY OF THE INVENTION 
The present invention therefore provides a medical instrument support 
mechanism which includes a unique locking mechanism allowing easier use by 
a practician. The mechanism is especially suitable for use in the 
ophthalmic or ophthalmologic industry but could be used in other medical 
areas as well. More specifically, the instrument support mechanism of this 
invention includes a base member which could be a stationary support, such 
as a pole, or a separate member connected to a pole. A first support arm 
is connected to the base member and a second support arm is connected to 
the first support arm. The first support arm is connected to the base 
member by a pivot connection at one end allowing the other end to be moved 
with respect to the first end. This movement preferably is a vertical, 
pivotal motion but could alternatively or additionally comprise a pivoting 
motion about the base member. The second arm is also preferably connected 
by a pivot connection to the first support arm to allow the second support 
arm to swing about an axis relative to the first support arm. In the 
preferred embodiment, the base member is connected to a vertical support 
pole for rotation about the pole and height adjustment along the pole. 
In accordance with the invention, a locking mechanism is uniquely connected 
to two or more pivot connections to allow an operator to selectively lock 
and unlock the pivot connections. More specifically, the locking mechanism 
is operated by a lever which is movable in a direction extending along the 
length of the first support arm. This helps ensure that pivoting motion 
does not occur while locking or unlocking the mechanism. More preferably, 
the lever is disposed along an underside of the first support arm and is 
operated by a simple push/pull movement. 
More specifically, the locking mechanisms of this invention are 
advantageously designed as unique screw locking mechanisms. Each screw 
locking mechanism locks and unlocks to at least one pivot connection by 
operating a clamp member associated therewith. The clamp members used in 
the present invention may be generally U-shaped clamp members that receive 
an element of the pivot connection. In the case of the vertically 
adjustable pivot connection, the screw clamps or unclamps linkage members 
associated with the vertically adjustable pivot connection. Also in 
accordance with the invention, the screws used in the screw locking 
mechanisms are preferably double helical threaded screws. While single 
lead screws will function, the use of double lead screws shortens the 
required travel of the actuating lever. 
In accordance with the preferred embodiment of this invention, heavy duty 
and light duty instrument support mechanisms are constructed in accordance 
with the invention. In a heavy duty version of a medical instrument 
support mechanism, for example, multiple counterbalancing springs may be 
used in place of a single counterbalancing spring and heavier duty and/or 
larger numbers of linkage members may be used to support the heavier 
instrumentation. In each case, the broader principles of this invention 
may be employed to achieve the advantages of the invention. 
These and other object and advantages of the invention will be more readily 
apparent to those of ordinary skill in the art upon review of the 
following detailed description of the preferred embodiments taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates a typical ophthalmic instrument system showing one 
potential use for a heavy duty support mechanism 10 and a light duty 
support mechanism 11, each being constructed in accordance with principles 
of this invention. Mechanisms 10, 11 are shown affixed to one type of 
instrument stand 12, however, it will be understood that many other 
supports may be used for mechanisms 10 and 11, as shown in FIG. 1, or 
mechanisms taking other forms in accordance with the invention. Instrument 
stand 12 generally includes a base 14 which may hold a plurality of 
instruments 14a, 14b, 14c and which includes an upwardly extending pole 
16. Pole 16 may have an overhead light 18 attached at the upper end. As 
further shown in dotted lines in FIG. 1, support mechanism 11 may carry a 
lighter weight ophthalmic instrument, such as a vision tester 17, while 
mechanism 11 may carry heavier weight structure such as a chin rest 19 and 
a slit lamp 21 or other instrument (not shown). 
Referring now to FIG. 2, instrument support mechanism 10, which is suitable 
for heavier duty applications, includes a first arm 20 and a second arm 22 
pivotally connected together by means to be described below. A cover 20a 
is preferably used to conceal the internal components and conventional 
wiring (not shown) associated with arm 20. A similar cover may be used on 
arm 11 (FIG. 1) as mentioned below. First arm 20 comprises a first link 
member 24 and a second, lower link member 26. Link members 24, 26 are 
respectively affixed by pivots 28, 30 to a base member 31. These pivots 
28, 30 allow the opposite end of arm 20 to be moved vertically with 
respect to base member 31. Referring briefly to FIG. 3, respective pairs 
of links 36a, 36b and 38a, 38b assist with the locking of arm 20 in a 
desired vertical orientation relative to base member 31. In this regard, 
links 36a, 36b and 38a, 38b are pivotally connected to first link member 
24. One pivot 40 for securing one end of links 36a, 36b is shown in FIG. 2 
with the understanding that a similar pivot connects links 38a, 38b to the 
same link member 24. As best shown in FIG. 3, the opposite ends of links 
36a, 36b and 38a, 38b include respective slots 42a, 42b and 44a, 44b for 
reasons to be described below. 
Still referring to FIG. 2, along with the vertical pivoting movement 
allowed by the pivoting nature of link members 24, 26, first arm 20 may 
pivot about support pole 16 by a pivot connection 46 and second arm 22 may 
pivot with respect to both the first arm 20 and support pole 16 by a pivot 
connection 48. More specifically, pivot connection 46 is made by way of a 
tube 50 that may be rigidly locked to support pole 16 and which receives a 
portion of base member 31 thereabout. To act as a stop for pivoting motion 
about pole 16, a screw 52 is contained in base member 31 and extends into 
a slot 54 contained in tube 50. A conventional screw operated clamp 
mechanism 56 is used to secure tube 50 rigidly to pole 16. When lock 56 is 
in an unlocked position, tube 50 and the attached mechanism 10 may be 
height adjusted along support pole 16. 
At the opposite end of first arm 20, pivot connection 48 more specifically 
comprises a pivot support 58 which holds a pivot tube 60 for rotation 
therein. Pivot tube 60 is held for rotation within bearing members or low 
friction bushings 62, 64. A retaining ring 68 holds pivot tube 60 in place 
within pivot support 58. Retaining ring 68 rests against a washer 66 as 
shown in FIG. 2, to keep second arm 22 held in place within pivot support 
58. Pivot tube 60 may also be used to accommodate wiring (not shown) to 
arm 22. Rotation of tube 60 and, therefore, arm 22 is limited by a screw 
69 which engages a stop 71 at a desired limit of rotation. 
As further shown in FIG. 2 and 2A, counterbalancing springs 70a and 70b 
help to counterbalance any weight being supported on second arm 22, or on 
an additional arm attached thereto, in a generally conventional manner. 
Specifically, springs 70a and 70b are connected to an adjustment screw 72 
to allow adjustment of the counterbalancing force. Ends 74a, 74b are each 
connected to a pin which includes an internally threaded bore receiving 
the adjustment screw 72. The opposite ends of springs 70a and 70b are 
connected to pivot pin 34. 
Still referring to FIG. 2, a locking mechanism 90 operates to lock each of 
the above described pivot connections in place after mechanism 10 has been 
adjusted vertically and rotationally to the desired orientation. Locking 
mechanism 90 is operated by a lever 92 which may be moved in a simple and 
short push or pull manner in a direction extending along the length of 
first support arm 20 as generally shown by arrow 94. Lever 92 is connected 
by a pivot 96 to link member 26 and is further connected to a connecting 
link 98 by a pin 100 extending from connecting link 98 and into a slot 102 
contained in the end of lever 92. Connecting link 98 is pivotally attached 
at opposite ends to respective short links 104, 106 by respective pivots 
108, 110. The opposite end of each short link 104, 106 is connected to 
rotate a respective screw 112, 114. As will be described below, these 
screws operate to simultaneously lock pivot connections 46 and 48 as well 
as the general pivot connection formed by pivots 28, 30, 32, 34 allowing 
arm 20 to move vertically with respect to base member 31. 
Referring now to FIG. 3, to lock pivot connection 48 in place, a clamp 
member 116 is provided around pivot tube 60. Thus, it will be appreciated 
that when clamp member 116 is tightened against pivot tube 60, pivot tube 
60 will not be capable of rotating and, therefore, second arm 22 will not 
be capable of rotating with respect to first arm 20. As more specifically 
shown in FIG. 3, clamp member 116 includes a first portion 118 having an 
internally threaded insert 120 and a second portion 122 having a hole 124. 
Threaded insert 120 receives a threaded portion 112a of screw 112, while 
hole 124 receives an unthreaded portion 112b of screw 112 with clearance 
to allow rotation of screw 112. Preferably, the threaded portion 112a is a 
double helical thread. Most preferably, screws 112, 114 are 3/8"--10 
double lead screws. Additional clamp members 126, 128 are provided for 
locking the above described vertical movement of first arm 20 with respect 
to base member 31 (FIG. 2). These clamp members 126, 128 each include 
flange portions 126a, 128a that serve to clamp links 36a, 36b and 38a, 38b 
against a portion of pivot support 58 to prevent any movement of links 
36a, 36b and 38a, 38b and thereby prevent any vertical movement of first 
arm 20 with respect to base member 31 (FIG. 2). It will further be 
appreciated that in an unlocked state, tubular portions 126b, 128b act as 
guides that ride within slots 42a, 42b and 44a, 44b during the vertical 
movement of first arm 20 with respect to base member 31. The tubular 
portion 128b is preferably internally threaded and carries threaded member 
130 to provide adjustment capability and a force bearing surface. Washers 
134, 136 are located about tubular portion 126b and between pivot support 
58 and link member 36b and link members 36a and 36b. Likewise, washers 
138, 140 are located between pivot support 58 and link 38b and links 38a, 
38b. 
Turning now to FIG. 4, pivot connection 46 more specifically comprises a 
clamp member 150 having a first portion 152 with a threaded insert 154 and 
a second portion 156 with a hole 158. In a manner similar to pivot 
connection 48, threaded insert 154 contains a double helically threaded 
portion 114a of screw 114 and hole 158 receives an unthreaded portion 114b 
of screw 114 with clearance to allow rotation of screw 114. Clamp member 
150 is disposed about tube 50 and, therefore, when clamp member 150 is 
tightened, no rotation of base member 31 about tube 50 may take place. A 
set screw 159 allows adjustment in the clamping action. As further shown 
in both FIGS. 3 and 4, short links 104, 106 are rigidly connected to 
screws 112, 114 at intermediate locations thereon with retainer pins 160, 
162. 
Thus, a review of FIGS. 2-4 will indicate that moving lever 92 away from 
base member 31 in the direction of arrow 94 will result in connecting 
member 98 moving toward base member 31 and short links 104, 106 rotating 
screws 112, 114 clockwise as viewed in FIG. 2. As shown in FIG. 3, this 
will cause screw 112 to move in the direction of arrow 163 to urge clamp 
member 126 against links 36a, 36b until they are wedged against washers 
134, 136 and pivot support 58. This will lock up and down motion of first 
arm 20 with respect to base member 31 (FIG. 1). Simultaneously, clamp 116 
will be rotated slightly around pivot tube 60 and move generally in the 
direction of arrows 164, 165. This will urge clamp member 128 against 
links 38a, 38b and clamp these links against washers 138, 140 and against 
pivot support 58 to further assist in locking vertical movement of arm 20. 
As clamp portion 118 moves further toward clamp portion 122, pivot tube 60 
is locked against any rotational movement. As long as short links 104, 106 
(FIG. 2) are maintained in the position shown, mechanism 10 will be locked 
completely in place by the friction of screws 112, 114. To unlock 
mechanism 90, lever 92 is moved in the direction of arrow 95 toward base 
member 31 (FIG. 5). This moves short links 104, 106 to an oppositely 
angled position and rotates screws 112, 114 counterclockwise to reverse 
and unlock the various clamping movements discussed above. 
Referring now to FIG. 6, the lighter duty instrument support mechanism 11 
is shown in more detail. Mechanism 11 works on very similar principles to 
those discussed above with respect to mechanism 10. Mechanism 11 comprises 
a first arm 170 and second arm 172 which are pivotally connected to one 
another in a manner to be described below. First arm 170 may have a cover 
170a (FIG. 7) to conceal internal components. First arm 170 is also 
pivotally connected to a base member 174 to allow vertical, pivoting 
movement with respect thereto as will also be described below. First arm 
170 comprises a first link member 176 and a second link member 178. First 
and second link members 176, 178 are connected to base member 174 by 
respective pivots 180, 182 which allow vertical pivoting motion with 
respect to base member 174 in a vertical orientation as shown in FIG. 6, 
i.e., when support pole 16 extends in a vertical orientation. Links 188a, 
188b are connected at a pivot 190 to first link member 176 as shown in 
FIG. 6. As further shown in FIG. 7, links 188a, 188b include respective 
slots 192a, 192b for reasons similar to those described above with respect 
to mechanism 10 as will be described in more detail below. 
Again referring to FIG. 6, in addition to the pivot connections allowing 
generally vertical movement of the outer end of first arm 170 with respect 
to base member 174, pivot connections 194, 196 are provided to 
respectively allow pivoting motion of mechanism 11 about support pole 16 
and pivoting motion of second arm 172 with respect to first arm 170. For 
height adjustment, like the first embodiment, a tubular support member 198 
is provided to hold mechanism 11 on support pole 16 and may be locked in 
place by a conventional screw locking clamp mechanism 200 when positioned 
at the desired height along pole 16. 
Referring now to FIGS. 6 and 7, pivot connection 196 more specifically 
comprises a cylindrical rod 206 received within a pivot support or housing 
208 and connected to second arm 172 by a connecting member 210. As best 
shown in FIG. 7, cylindrical rod 206 is preferably contained within a low 
friction sleeve or bearing member 211 which, in turn, is disposed within a 
clamp member 212. As further shown in FIG. 6, a retainer 214 keeps the 
cylindrical rod 206 held within pivot support or housing 208. Link members 
176, 178 of first arm 170 are attached to housing 208 by pivots 184, 186. 
Still referring to FIG. 6, like the first embodiment, a counterbalancing 
spring 216 is preferably provided and connected to an adjustment screw 218 
at one end for allowing adjustment in the counterbalancing force to be 
made upon initial assembly or by the user. One end 220 of spring 216 is 
connected to a threaded member 222 which receives adjustment screw 218 for 
threaded adjustment therein. The other end 224 of spring 216 is connected 
to pivot pin 186. 
As further shown in FIG. 6, a locking mechanism 230 is provided for locking 
the various pivot connections of arm 11. Locking mechanism 230 is similar 
to locking mechanism 90 of instrument support mechanism 10. Specifically, 
a lever 232 operates generally in the direction of arrow 234 to lock pivot 
connections 194 and 196 as well as the general pivot connection made 
between base member 174 and first arm 170 which allows vertical adjustment 
of first arm 170 with respect to base member 174. More specifically, lever 
232 is connected by a pivot 236 to second link member 178 and is further 
connected to a connecting link by a pin 240 extending therefrom and into a 
slot 242 in the end of lever 232. Short links 244, 246 are connected at 
respective ends of connecting link 238 by pivots 248, 250. The opposite 
end of each short link 244, 246 is rigidly affixed to respective screws 
252, 254 by retainer pins 256, 258. Thus, it will be appreciated that when 
lever is pulled away from base member 174 to the position shown in FIG. 6, 
short links 244, 246 will rotate screws 252, 254 clockwise to 
simultaneously lock the various pivot connections as will be described. 
Preferably, screws 252, 254 are each 3/8"--10 double lead screws. 
Referring now more specifically to FIG. 7, the locking mechanism 230 
preferably operates clamp member 212 to selectively allow or prevent 
rotation of cylindrical rod 206. Specifically, a first portion 260 of 
clamp member 212 includes a threaded insert 262 for receiving threaded 
portion 252a of screw 252. A second portion 264 of clamp member 212 
interacts with an adjustable screw stop 266. Finally, similar to the first 
embodiment, a clamp member 268 including a flange portion 268a and a 
tubular portion 268b is operated by one end of screw 252 to selectively 
allow and prevent movement of links 188a, 188b. As also provided in the 
first embodiment, washers 270, 272 are respectively disposed between pivot 
support housing 208 and link 188b and between links 188a and 188b. Thus, 
when screw 252 is rotated by short link 244 to move in the direction of 
arrow 274, clamp member 268 will move upwardly as viewed in FIG. 7 and 
flange portion 268a will clamp links 188a, 188b against washers 270, 272 
and the inside of pivot support or housing 208. This will prevent movement 
of links 188a, 188b by way of slots 192a, 192b riding along tubular clamp 
portion 268b and thereby prevent any articulating up and down movement of 
first arm 170 (FIG. 6). At the same time, portion 260 of clamp member 212 
will move generally in the direction of arrow 276 and, as portion 264 is 
stopped against threaded stop member 266, this will clamp cylindrical 
pivot rod 206 against any rotation. 
Referring now to FIG. 8, a clamp member 280 is provided at the opposite end 
of first arm 170 to selectively allow or prevent rotation of first arm 170 
and any attachments about support pole 16. Specifically, clamp member 280 
includes a first portion 282 having a threaded insert 284 for receiving 
threaded portion 254a of screw 254. A second portion 286 of clamp member 
280 includes a hole 286a which receives an unthreaded portion 254b of 
screw 254 with clearance for rotation. Thus, when short link 246 is 
rotated by connecting link 238 in a clockwise direction as viewed in FIG. 
6, screw 252 will move in the direction of arrow 288 and bear against the 
inside of base member 174. This will cause portion 282 of clamp member 280 
to move in an opposite direction and, as portion 286 bears against 
adjustment screw 290, a clamping action will take place against tubular 
support member 198. Like the other adjustment screws, screw 290 allows 
adjustment in the clamping action. Therefore, base member 174 will not be 
able to rotate about tubular support member 198. 
Generally referring to FIGS. 6-8, and to summarize the operation of 
mechanism 11, when lever 232 is pulled in the direction of arrow 234 away 
from base member 174, short links 244, 246 will be rotated by connecting 
link 238 and thereby rotate screws 252, 254 in a clockwise direction as 
viewed in FIG. 6. As shown in FIG. 7, this will move screw 252 in the 
direction of arrow 274 to clamp links 188a, 188b against any movement and 
further move first clamp portion 260 in the direction of arrow 276 to 
prevent any rotational movement of pivot rod 206. In this manner, pivoting 
of second arm 172 with respect to first arm 170 is prevented and vertical 
movement of first arm 170 with respect to base member 174 is also 
prevented. At the same time and referring more specifically to FIG. 8, 
screw 254 will be moved in the direction of arrow 288 and thereby clamp 
member 280 against support tube 198 in the manner described above to 
prevent any rotational movement of mechanism 11 about support pole 16. As 
schematically shown in FIG. 9, movement of lever 232 in an opposite 
direction toward pole 16 will rotate screws 252, 254 in a counterclockwise 
direction thereby unlocking all of the pivot connections described above 
and allowing readjustment of mechanism 11 to a desired position. 
While the present invention has been illustrated by a description of 
various embodiments and while these embodiments have been described in 
considerable detail, it is not the intention of the Applicant to restrict 
or in any way limit the scope of the appended claims to such detail. As an 
example, the various features of the mechanisms described herein in detail 
may be combined or substituted in various manners. Additional advantages 
and modifications will readily appear to those skilled in the art. The 
invention in its broader aspects is therefore not limited to the specific 
details, representative apparatus and methods as shown and described. This 
has been a description of the present invention, along with the preferred 
methods of practicing the present invention as currently known. However, 
the invention itself should only be defined by the appended claims, 
wherein