Medical instrument with internal light source for illuminating body cavities

A medical instrument, specifically a laryngoscope, has a hollow handle containing a primary or secondary electric battery and a lamp, the latter having a light bulb disposed at the upper end of a detachable head of the handle toward which it is urged by a spring bearing upon the battery from below. The lamp is held in a metallic sleeve surrounded by a dielectric sheath which is snap-fitted into the detachable head; the sheath and the sleeve are axially repressible against the spring force. A speculum is pivoted to that head and is swingable between an idle position alongside the handle and a working position perpendicular thereto. In its working position, a camming projection on the speculum represses the assembly of battery, sheath, sleeve and lamp and closes an energizing circuit for the light bulb through the handle head. The speculum has a channel which terminates short of its tip and accommodates a fiber-optical light guide whose rear end is illuminated by the light bulb in the working position. The channel is bounded by two sheet-metal profiles joined together by arc welding and/or soldering.

FIELD OF THE INVENTION 
My present invention relates to a medical instrument, such as a 
laryngoscope, of the type wherein an applicator or speculum is pivotally 
mounted on a handle and is designed to illuminate an anatomical cavity or 
recess with the aid of light rays piped from a source inside the handle 
toward the tip of that applicator. 
BACKGROUND OF THE INVENTION 
An instrument of this description is known from U.S. Pat. No. 3,638,644 to 
F. G. Reick. The laryngoscope particularly disclosed in that patent 
utilizes a solid light guide, in the form of a curved strip of 
polyacrylate (Lucite or Plexiglas) terminating in a reduced front end at 
the tip of the applicator and in a broader rear end which in a working 
position is closely spaced from an aperture at the top of the handle 
overlying a light bulb. The latter is part of a lamp closely surrounded by 
a metallic sleeve in direct contact with the metallic shell of the handle 
which in turn is conductively connected, through a biasing spring at the 
bottom of that handle, with the negative pole of a battery stack whose 
positive pole is normally held separated, by means of another spring, from 
a centrally disposed terminal of the light bulb. When the applicator is 
swung into its working position, via a pivotal junction linking it with 
the handle, a pair of feet of that applicator cammingly engage the 
metallic sleeve in order to repress the lamp against the force of the 
last-mentioned spring so as to let its central terminal make contact with 
the positive battery pole whereby the bulb is energized to illuminate the 
proximal end of the acrylic strip. An abutment rising from the top of the 
head carries detent balls coacting with recesses on the feet bracketing 
same in order to index the applicator in its working position. 
As noted in that patent, Lucite is a brittle and fragile material wherefore 
the light-guiding strip has to be supported on the applicator by a 
depressor blade made from a tough resin, namely polycarbonate. The strip 
is flanked on one side by a reinforcing rib but is otherwise exposed, 
except at its rear end where it is shielded by a glare cover. 
The described camming mechanism for closing the lamp circuit has the 
drawback that the light bulb may be accidentally energized, with 
consequent discharge of the associated batteries, even when the applicator 
or speculum is in its inoperative or idle position. This could happen, for 
example, when the bulb is inadvertently repressed by hand or when its 
sleeve jams in the repressed state after a temporary swing of the 
applicator into its working position. In case of a burnout, extraction of 
the bulb from its socket for the purpose of replacement requires the use 
of a special tool. 
OBJECTS OF THE INVENTION 
The general object of my present invention is to provide an improved 
medical instrument of the type referred to, especially a laryngoscope, 
which obviates the disadvantages of known implements of that sort. 
A more particular object is to provide such an instrument with a speculum 
whose light guide is not made of a brittle material requiring a massive 
support and which therefore can be manufactured in its entirety from 
materials other than polycarbonate, preferably from sheet metal. 
A related object is to provide a speculum structure by which the light 
guide, advantageously a bundle of optical fibers, is enclosed over 
virtually its full length in a protective channel preventing the entry of 
bacteria into a patient's oral cavity or other recesses to be explored. 
A further specific object of my invention is to provide a handle 
construction which facilitates the extraction of a light bulb and prevents 
untimely closure of an energizing circuit therefor. 
SUMMARY OF THE INVENTION 
According to an important feature of my present invention, a medical 
instrument for the exploration of anatomical cavities, having a speculum 
pivoted to a hollow handle (considered upright for the purpose of 
definition) containing a light source and an associated generator of 
electrical energy approximately as shown in the above-discussed Reick 
patent, has light-guiding means extending within a lighttight and 
externally smooth-surfaced channel of the speculum which is bounded by a 
web and a lower transverse flange of a first profile and by a web and an 
upper transverse flange of a second profile, the first profile being of 
generally Z-shaped cross-section while the cross-section of the second 
profile is of inverted-L shape. The upper transverse flange of the second 
profile closely adjoins an upper transverse flange of the first profile, 
being preferably welded or soldered thereto so that these two transverse 
flanges form a continuous upper surface, while the web of the second 
profile rests on the lower transverse flange of the first profile to which 
it may be soldered or welded by a longitudinal seam adjoining the web and 
flange surfaces without external discontinuities. With the last-mentioned 
flange extending laterally beyond the web of the second profile, that 
flange forms a continuous lower surface which is laterally offset from the 
upper surface; the terms "upper" and "lower", as herein used, apply to a 
generally horizontal working position of the speculum substantially 
perpendicular to its upright handle. 
When the instrument is designed as a laryngoscope, as in the preferred 
embodiment more fully described hereinafter, the upper surface is upwardly 
convex to serve as a support for the palate of the patient whereas the 
lower surface is downwardly concave to serve as a tongue depressor. For 
the illumination of a sufficiently wide area of a patient's throat (or, 
more generally, some other anatomical recess to be explored), the 
light-guiding means and thus the second profile forming part of its 
protective channel should terminate short of the tip of the speculum while 
the first profile may extend lengthwise beyond the front end of the 
light-guiding means to the tip of the speculum where the two transverse 
flanges of that first profile advantageously converge. The front end of a 
fiber bundle serving as the light-guiding means preferably terminates 
flush with the second profile while being embraced by a ferrule fitting 
tightly into the channel so as to seal it against possible entry or exit 
of bacteria. A similar seal may be provided at the rear or tail end of the 
fiber bundle by a bushing preferably formed with a projecting shoulder. 
Pursuant to another important feature of my invention, the handle of the 
instrument includes not only a cylindrical metallic shell but also a 
metallic head coaxially threaded into same. In an upright handle position, 
i.e. with the common axis of the shell and the head generally vertical as 
will usually be the case when the instrument is being handled by a 
practitioner, the light source will lie at the top of the head, just below 
a metallic foot of the speculum which forms with that head the pivotal 
junction allowing the speculum to be selectively swung between its idle 
and working positions. The light source is a conventional lamp with a bulb 
received in a socket, that socket being closely surrounded by a metallic 
sleeve in conductive contact therewith and thus with a terminal of the 
bulb filament. In contradistinction to the arrangement of the 
above-identified Reick patent, however, the metallic sleeve does not 
contact the shell of the handle but is insulated therefrom by a dielectric 
sheath enveloping it inside the handle's head. Another terminal of the 
bulb is in continuous direct contact with a central (positive) pole of a 
battery, which may be of the primary or of the secondary--i.e. 
rechargeable--type and could be one of several such batteries stacked as 
in the Reick patent; the battery or batteries form together with the 
dielectric sheath, the metallic sleeve and the lamp an assembly which as a 
whole is axially movable in the handle and is urged upward by spring means 
disposed in the housing. The foot of the speculum is provided with cam 
means conductively connected with the head of the handle by their pivotal 
junction, the cam means engaging the sleeve in the working position of the 
speculum for closing an energizing circuit through the bulb while 
repressing the movable assembly against the force of the spring means. 
Thus, the bulb lights only in that working position to illuminate the 
aforedescribed light-guiding means, preferably a fiber bundle, extending 
from the vicinity of the top of the head toward the tip of the speculum. 
The cam means may be an extension of the aforementioned bushing, e.g. a 
shoulder-forming collar. 
In the event of a rechargeable or storage battery having a pair of prongs 
which flank the central pole and are insertable into a socket of a source 
of charging current, these prongs are received in a pair of diametrically 
opposite clearances of the head. One prong, i.e. the one connected to the 
negative battery pole, is conductively connected (e.g. by an interposed 
spring) to the head and thus to the shell of the handle so as to form part 
of the energizing circuit which is closed when the movable assembly is 
repressed by the cam means. The head of the handle may be provided with a 
pair of upstanding ridges bracketing the foot of the speculum, these 
ridges supporting a pivot pin which is offset from the handle axis and is 
engaged in a slot of the foot to act as a fulcrum for its swinging motion. 
The ridges can be further provided with confronting formations which are 
engageable by indexing means on the foot, such as the detent balls mounted 
on the handle abutment of the Reick laryngoscope but with an inverted 
arrangement, for yieldably retaining the speculum in its working position.

SPECIFIC DESCRIPTION 
In FIGS. 1 and 2 I have shown a laryngoscope 1 resembling the appliance 
disclosed in the above-identified Reick patent. The instrument comprises 
an upright, generally cylindrical handle 2 to which a speculum 9 is 
pivoted for selective swinging between an idle or inoperative position, 
FIG. 1, and a working or operative position, FIG. 2. The handle 2 is 
longitudinally subdivided into a tubular shell 37 and an upwardly tapering 
tubular head 32 screwed onto the upper end of that shell as more fully 
described hereinafter. The lower end of the shell 37 is closed by a cap 34 
secured thereto via a bayonet coupling which is formed by studs 90 engaged 
in slots 91 (only one of each shown). 
Details of speculum 9 are shown in FIGS. 3-6. The speculum consists, 
essentially, of a first sheet-metal profile 25 of generally Z-shaped 
cross-section, a second sheet-metal profile 26 of inverted-L-shaped 
cross-section, and a foot 43 fitted onto profile 25. This profile, 
illustrated by itself in FIG. 4, comprises a cantilevered upper transverse 
flange 23, a lower transverse flange 24 and an upstanding web 28 
interconnecting these flanges. The upper flange 23 narrows progressively 
toward the front end of the profile where it joins the lower flange 24, 
which is of substantially constant width greatly exceeding the maximum 
width of flange 23. The web 28, consequently, progressively decreases in 
height toward that front end. A slot-shaped aperture 14 near the rear end 
of flange 24 gives passage to a bundle 11 of optical fibers which is 
confined for the most part in a lighttight channel 21 that is bounded by 
web 28 and flange 24 of profile 25 and by a web 27 and a transverse flange 
29 of profile 26. The two flanges 23 and 29 are flush with each other and 
are united by an arc-welding seam 15 which has been suitably leveled off, 
as best seen in FIG. 6, to let these two flanges form a continuous upper 
surface that is upwardly convex to serve as a palate support when the 
speculum is introduced into the mouth of a patient whose throat is to be 
explored. In the assembled speculum illustrated in FIG. 3, the web 24 
terminates in a small transverse cylinder 13 designed to prevent any part 
of the patient's mouth from coming into contact with a sharp edge; web 24 
is downwardly concave to act as a tongue depressor. 
The correspondingly curved lower edge of web 27 rests on the flange 24 to 
which it is soldered along a seam 16 with a substantial initial excess of 
solder. That seam, again as best seen in FIG. 6, is also carefully 
machined and polished so as to form, in its cross-section, a small arc 
faired smoothly into the exposed surfaces of the web and the flange. 
As seen in FIG. 5, the fiber bundle 11 terminates at the front end of 
profile 26 where that bundle is embraced by a ferrule 12 fitting tightly 
into the channel 21. The ferrule has, of course, the same rectangular 
cross-section as the channel 21 at that front end. At its upper edge and 
its outer lateral edge, ferrule 12 is formed with a lip 12' of rounded 
cross-sectional contour bearing upon the front end of profile 26 to mask 
the sharp edges of the profile at that end, again without any external 
discontinuity. The ferrule thus has the dual purpose of firmly supporting 
the front end of the fiber bundle and of sealing the channel at that end 
against a possible entry or exit of bacteria which could be transferred to 
the mouth of the patient. In fact, the entire portion of the speculum 9 
receivable in the patient's mouth is externally smooth-surfaced without 
any hard-to-clean crevices in which microorganisms could collect. 
At its rear, channel 21 is closed by a back plate 17 inserted between 
flange 29 and foot 43. The sides of that foot are formed in part by two 
cheeks 18 and 19 which are recessed to receive the flange 24 of profile 25 
between them. The tail end of fiber bundle 11, which passes into the foot 
43 through the slot 14 shown in FIG. 4, is tightly gripped by a 
cylindrical bushing 47 which is firmly seated in a vertical passage of 
that foot and has a collar 47' so as to form a shoulder bearing from below 
upon the underside of the foot. The latter is further provided with a hook 
44 bounding a slot 46 which is open toward the tip of speculum 9 and 
slopes upward in the working position of FIG. 5. Slot 46 is designed to 
receive a pivot pin 45 of handle head 32, illustrated in FIG. 7, which 
serves as a fulcrum for the swing of the speculum between the idle and 
working positions respectively shown in FIGS. 1 and 2. 
From FIG. 7 it will further be noted that, in the working position 
illustrated there, the collar 47' of bushing 47 penetrates partly into the 
top of head 32 so that the end of fiber bundle 11 lies directly above a 
bulb 61 which, together with a lamp socket 59 shown in FIG. 10, serves as 
a light source for the illumination of a patient's throat by way of that 
bundle. The lamp socket 59, consisting for the most part of dielectric 
resinous material, has a conductive surface portion 59' in contact with 
one terminal of the filament of bulb 61 whose other terminal 62 extends 
along the axis O of handle 2 and is well separated from a metallic sleeve 
42 surrounding that socket. Sleeve 42 has a top section 48 provided with 
an annular groove 60 imparting to it a certain degree of elastic 
deformability. A constricted middle section 58 of that sleeve engages the 
conductive portion 59' of the lamp socket which adjoins a bottom section 
59 of the same diameter as top section 48. 
Terminal 62 of bulb 61, well separated from sleeve 42, is in direct contact 
with a central positive pole of a battery 33 disposed in the lower part of 
handle 2, i.e. inside shell 37 below the level of head 32. A coil spring 
31 at the bottom of that shell, supported by cap 34, bears upon the 
underside of battery 33 to bias it upward while also establishing a 
conductive connection between shell 37 and the negative battery terminal 
which in the usual manner is constituted by a metallic housing enclosing 
the electrochemically active material. 
Sleeve 42 is embraced by a tubular sheath 38 of dielectric material which 
is snap-fitted into a central bore 40 of head 32 with the aid of one or 
more yieldable barbs 50 projecting into an inner annular recess 51 of this 
head. Each barb is fastened to the remainder of the sheath by a reduced 
part 54 and is movable in a window 55 as best seen in FIGS. 8 and 9. An 
annular shoulder 39 of sheath 38 (see FIG. 8) confronts an internal 
shoulder 41 of bore 40 against which it is pressed by spring 31 (see FIG. 
11) when the speculum 9 is in its alternate (idle) position. Recess 51 is 
wide enough to let the barb or barbs 50 move therein axially between an 
elevated position, defined by shoulders 39 and 41, and a depressed 
position into which the assembly consisting of lamp 59, 61, sleeve 42, 
sheath 38 and battery 33 is lowered by a camming engagement between the 
collar 47' of bushing 47 and the top section 48 of sleeve 42 when the 
speculum 9 is swung about pivot pin 45 into the working position shown in 
FIG. 7. In that position, the speculum is indexed by detent balls 84 
projecting under spring pressure from a transverse bore 75 of foot 43 
(FIG. 5) and engaging in depressions 83 of a pair of parallel ridges 70, 
71 which rise from the top of head 32 as best seen in FIGS. 11-13. In 
order to prevent the balls 84 from dropping out of bore 75, they may be 
retracted more than halfway into that bore (against an interposed coil 
spring) and the rims of the bore may be somewhat peened over to reduce 
their diameter. 
Light bulb 61 may be of the type described in the Reick patent, with a lens 
at its tip. That tip projects partly into a space 52 bounded by a 
cup-shaped upper end 53 of sheath 38 lying above an outer annular recess 
56 of that sheath which imparts to the cup 53 a certain flexibility in 
order that the camming extension 47' of bushing 47 may pass readily 
thereover even in the event of some dimensional inaccuracies. 
As seen in FIG. 12, ridges 70 and 71 are respectively provided with a blind 
bore 73 and with a throughgoing bore 72 into which the pivot pin 45 is to 
be inserted with a tight fit. The two ridges lie at opposite sides of a 
substantially square plateau which tops off the head 32 whose cylindrical 
periphery is partly cut away by four flat lands 76, 78 and 81, 82 
adjoining respective sides of the plateau toward which they converge. 
Head 32 is further provided with two diametrically opposite, axially 
extending bores 64, 65 (see also FIG. 13) which are functionless in the 
handle of FIG. 7 where the generator of electrical energy is a primary 
battery 33 or possibly a stack of several such batteries as shown in the 
Reick patent. I may, however, replace that primary battery by a secondary 
or storage battery 63, shown in FIG. 11, which has a charging attachment 
with a pair of prongs 66, 67 designed to be plugged into a current source 
such as a wall socket when the battery is to be recharged. In the 
assumption that prong 66 is a ground lead, connected directly to the 
battery housing serving as its negative pole, and that prong 67 is 
connected via an internal step-down and rectification circuit to a central 
positive pole such as that shown at 68 in FIG. 7, these prongs are 
respectively inserted into bores 64 and 65. While prong 67 is inactive, 
prong 66 bears in bore 64 upon a contact-intensifying conductive coil 
spring 69 which has a reduced extremity 69' received in a similarly 
reduced upward extension 64' of that bore; the other bore 65 has a like 
extension 65', unused in this instance, as indicated in FIG. 13. Thus, the 
negative battery pole is again conductively connected with shell 37 and 
head 32 of handle 2, as is the case with battery 33 of FIG. 7. Here, too, 
bulb terminal 62 is in continuous contact with the central positive 
battery pole. 
In both cases, therefore, a swing of speculum 9 into its working position 
completes an energizing circuit through bulb 61 which extends from 
terminal 62 to the positive battery pole, thence from the negative battery 
pole to head 32 and then via ridges 70, 71 and pivot pin 45 to foot 43 
whose bushing 47 completes the circuit to the other bulb terminal by way 
of collar 47' and sleeve 42. It will further be apparent that with 
speculum 9 inoperatively positioned, as in FIG. 1, there is no possibility 
of accidental completion of this energizing circuit. 
As clearly shown in FIG. 12, head 32 has a tubular neck 92 with a fine 
thread 93 by which it is screwed into the upper part of shell 37. 
Unscrewing the head 32 from the shell 37 thus allows the subassembly of 
sheath 38, sleeve 42 and lamp 59, 61 to be extracted therefrom to 
facilitate a replacement of bulb 61, or possibly of the entire 
subassembly, if necessary. 
From the foregoing description it will be apparent that I have disclosed a 
medical instrument for the purpose set forth which is of relatively simple 
structure, consisting of a limited number of parts which can be readily 
disassembled and reassembled. Its metallic speculum is easy to clean and 
sterilize after detachment from the handle, which is conveniently 
accomplished in the idle position of FIG. 1.