US 3595222 A
Description (OCR text may contain errors)
United States Patent [72} inventors William Noel Vellacott 71 Albert Road South, Malvem; Anthony James Sear, l8, Lansdowne Crescent, Malvern, both of Worcestershire,
' England  Appl. No. 735,689  Filed June 10, 1968  Patented July 27,1971  Priority June 13, 1967 [33} Great Britain  27204/67 [54 LARYNGOSCOPE 8 Claims, 5 Drawing Figs.
 References Cited UNITED STATES PATENTS 2,070,820 2/1937 Allyn 2,289,226 7/1942 Von Foregger 128/11 2,648,329 8/1953 Morch 128/11 3,393,3 ll 7/1968 Dahl 240/10.6
Primary Examiner-Richard A. Gaudet Assistant ExaminerG. F. Dunne Attorney-Young and Thompson .ABSTRACT: A laryngoscope comprising a main body provided by an integral moulding with handle and blade portions the latter of which has a forwardly facing socket for a light .bulb. The handle is adapted to house a dry cell battery for operating the bulb and the laryngoscope incorporates a fixed electrical lead comprising a brass tube for electrically interconnecting a side terminal of the bulb with one terminal of the battery. A mobile electrical lead is provided for insertion into the brass tube which is embedded in the blade and which terminates at the socket, and the lower end of the handle incorporates manually operable means for moving the battery upwardly within the handle and towards the blade to an operative position in which the two ends of the mobile lead are respectively urged into contact with the central end terminal of the bulb and the other terminal of the battery.
2 PATENTEU m2? l97| SHEET 1 0F 2 IN \IENTORS BY 117M ATTORNEYS LARYNGOSCOPE This invention relates to medical instruments and more particularly to laryngoscopes used for intubation purposes or to assist examination of the larynx or neighboring parts of the throat.
Laryngoscopes normally have a blade for insertion into the throat and on which is mounted an electric light bulb energized by a battery housed in a hollow handle of the instrument. The majority of existing constructions employ a blade which is detachably connected to the handle of the instrument and suffer from electrical contact problems with a tendency to a flickering light in use. An object of the invention is to provide a laryngoscope employing more satisfactory electrical contact arrangements.
According to the invention a laryngoscope comprises a main body provided by an integral moulding with handle and blade portions the latter of which has a forwardly facing socket for a light bulb, i.e. facing away from the handle which is adapted to house a dry cell battery for poweringthe bulb, a fixed electrical lead for interconnecting a side terminal of the bulb with one terminal of the battery, a mobile electrical lead for insertion into a passage through the blade, which passage terminates at the socket, and manually operable means for completing the electrical circuit with the two ends of the mobile lead respectively urged into contact with the central end terminal of the bulb and the other terminal of the battery.
Preferably said means for completing the circuit operate to move the battery within the handle, desirably upwardly towards the blade and to urge the mobile lead towards the bulb socket, instead of employing a switch which introduces additional electrical circuits.
The handle preferably has an aperture which may be closed by a detachable side cover and through which the battery can be replaced and the mobile lead withdrawn from said passage for cleaning ofthe end contact points of that lead.
in a preferred embodiment the fixed lead is provided by a metal tube which may be of brass and is embedded in the blade and which defines said passage, one end of the tube providing the bulb socket and the other end terminating at the upper end of and centrally within the hollow handle. The mobile lead is preferably of resilient stainless steel wire with an insulating sheath movable in the metal tube with radial clearance so that when the twoends of the mobile lead are urged into respective contact with the bulb and battery, the mobile lead bows within the tube to provide a spring action which ensures positive electrical contact for the two ends of the wire. ln a preferred construction the tube forms part of a subassembly of the electrically conducting parts which is prefabricated from a metal such as brass and around which the body ofthe laryngoscope is molded.
The subassembly may include an internally threaded brass sleeve which is connected to the brass tube by a side connecting wire and is embedded in a lower end wall of the handle in the completed laryngoscope and into which is screwed a threaded stem of an end cap forming said manually operable means.
The invention will now be further described with reference to the accompanying drawings which show, by way of example, a laryngoscope in accordance with the invention. la the drawings: I
FIG. 1 is a side view of the laryngoscope with a detachable side cover in a detached position, and with an end cap shown in section,
FlG. 2 is a sectional view on the line 11-" of H6. 1.
FIG. 3 is a rear view ofa subassembly of the laryngoscope,
HO. 4 is a side view, partly in section, showing the subassembly with a mobile lead in position therein, and
FIG. 5 is a sectional view, to an enlarged scale, of two portions of the subassembly and mobile lead as they appear after moulding.
The laryngoscope has a main body with a curved blade portion 1 and a hollow handle portion 2 integrally molded from a synthetic plastics material. The blade 1 is of the so-called Macintosh shape with an upper rib 3 on the right-hand side of the blade 1 when viewed from the rear and a slot 4 on the left lateral aspect which accommodates an electric light bulb 5 powered by a pair of dry batteries 6 housed within a partcylindrical recess 7 formed in the handle portion 2.
The electrically conducting subassembly of FIG. 3 is fabricated from brass and comprises a brass tube 8, a cup member 9, a side connecting wire 10 and an internally threaded sleeve 12, these four components being soldered together (with the tube 8 also being screwed into the cup member 9) so that the tube 8 and sleeve 12 are permanently electrically interconnected. The body of the laryngoscope is molded around the subassembly with the tube 8, which is suitably bent, embedded in the rib 3 of the blade 1 and the cup member 9just projecting into the battery recess 7, as shown in FIG. 1. An end wall 13 of the handle 2 is molded around the sleeve 12 and the wire 10 is embedded in a curved sidewall 14 of the handle 2, the sidewall 14 defining the recess 7. In order to ensure that the sleeve 12 is firmly held in the end wall 13 it is externally grooved. The lower end of the lead wire 10, i.e. the end remote from the cup member 9 is bent to form a spring arm 16 which is soldered to the grooved portion of the sleeve 12 and which allows the relative positions of the sleeve 12 and cup member 9 to be varied, within certain limits, to fit into the mold tools accurately before the body is molded around the subassembly. The spring arm 16 thus enables sub assemblies with substantial dimensional variations to be readily accommodated in the mold prior to molding of the body, and accommodates shrinkage of the molding without distorting the latter.
The front end 17 of the tube 8, which terminates adjacent the slot 4, is internally threaded at 11 (as shown in FIG. 5) to provide a socket for the reception of the bulb 5 the glass envelope of which is thus disposed within the slot 4 and faces forwardly towards the free end of the blade 1. The rib 3 on the blade 1 is molded with an undercut recess 18 forwardly of the slot 4 so as not to impede the direct forward transmission oflight from the bulb 5 along the blade 1.
The battery recess 7 is closed by a detachable molded side cover 19 which is part-cylindrical in shape and'which, when in position on the handle 2, cooperates with the sidewall 14 to provide a cylindrical handle shape. A lug 20 molded at the upper end of the cover 19 locates within a recess 22 in the body and each longitudinal edge of the cover 19 has an elongated projecting side rib 23 which locates within the corresponding edge of the sidewall 14, as shown in FIG. 2. Additional location for the cover 19 is provided by two projections 24 (H6. 1) which define between them a gap in which an integrally molded protrusion 25 on the body locates when the cover 19 is fitted on the handle 2.
The cover 19 is retained in position by means of an end cap 26 which has a molded in and screwed brass stem 27 threaded into the sleeve 12 and a surrounding skirt 28 which, when the cap 26 is screwed fully into the sleeve 23, surrounds lower end portions of the sidewall 14 and cover 19, the latter being removed by unscrewing the cap 26 and pulling the cover 19 downwardly and away from the handle 2. When the cap 26 is screwed fully into the sleeve 12, the upper end of the stem 27 contacts the casing terminal of the lower of the two batteries 6 and thereby provides electrical interconnection between this terminal and the side terminal of the bulb 5 through the wire 10 and tube 8.
The central end terminals of the bulb 5 and the upper of the two batteries 6 are electrically interconnected by a mobile lead inserted in the tube 8 and comprising a stainless steel wire 29 with an insulating sheath 30 of polytetrafluoroethylene. One end of the wire 29 has a swaged-on stainless steel contact 31 and the other end is bent into a loop 32 around which is molded a plastics cap 33 which is slidable in the manner of a plunger within the cup member 9. The extreme end of the loop 32 on the wire 29 is exposed and, when the cap 26 is screwed into the sleeve 12, the contact 31 is urged into contact with the central terminal ofthe bulb 5 and thus completes the electrical circuit to provide the required illumination.
The sheath 30 is a loose fit on the wire 29 and is positioned within the tube 8 with radial clearance so that when the ends of the mobile lead are urged into respective contact with the upper battery 6 and the bulb 5, the wire 29 and sheath 30 bow within the tube 8 to provide a spring action which ensures positive electrical contact and prevents flickering of the light provided by the bulb 5. The sheath 30 is held captive on the wire 29 between the contact 31 and cap 33 so that these three components form a further subassembly which can readily be withdrawn from the laryngoscope, following removal of the side cover 19, for cleaning of the ends of the mobile lead to maintain a good electrical contact. This is particularly important as any corrosion, particularly due to disinfectant or other sterilizing agents which may be used, would seriously impair the light emission and result in flickering. Undue inward movement of the mobile lead into the tube 8 which would damage the end contact of the bulb is prevented by the interengagement of the cap 33 with the radial end surface of the cup member 9, as shown in FIG. 5.
At the inner end of the thread 11 the tube 8 is counterbored at 34 and a pair of opposed feed bores 35 (FIG. 5) through the wall of the tube communicate with the counterbore. The plastics material of the body flows through the bores 35 during molded to form an internal insulating sleeve 36 within the tube 8, during the molding operation a removable core member with a cylindrical stern which just fits the tube bore being screwed into the bulb socket thread 11. Thus the sleeve 36 just fills the counterbore 34, and it operates to centralize and insulate the contact 31 which is a sliding fit within the sleeve 35.
I. A laryngoscope comprising an integral molded body comprising a hollow handle portion housing a dry cell battery and a hollow, forwardly extending blade portion, an electrically conductive tube member mounted in the blade portion and provided with a forwardly facing light bulb socket, a fixed electrical lead in circuit between the battery and said tube member and embedded in said handle portion, an internally threaded sleeve embedded in the handle portion of the lower end thereof, said fixed lead terminating around the sleeve as a spring arm which is connected to the sleeve, a mobile electrical lead which extends from said handle portion of said light bulb socket for contact-making engagement with an end terminal of the battery, said tube member being shorter than the mobile lead and through which said lead extends, and a threaded member screwed into the sleeve to act through the battery to urge the mobile lead in the tube member towards the light bulb socket, whereby to effect bowing of the mobile lead in the tube member to provide a spring contact pressure at each end of the mobile lead.
2. A laryngoscope according to claim 1, wherein the handle has an aperture which is closed by a detachable side cover and through which the battery can be loaded in the handle and the mobile lead withdrawn.
3. A laryngoscope according to claim 1, wherein the mobile lead is of stainless steel wire with an insulating sheath.
4. A laryngoscope according to claim 1, wherein said means for completing the circuit operate to move the battery upwardly within the handle to urge the mobile lead towards the bulb socket.
5. A laryngoscope comprising a molded body comprising a handle portion which provides a battery housing and a hollow, forwardly extending blade portion, an electrically conductive tube member mounted in the blade portion and provided with a forwardly facing light bulb socket, a fixed electrical lead interconnecting a side terminal of said tube member with one end of said battery housing, a removable and mobile electrical lead which extends from the other end of said battery housing to said bulb socket for contact-making engagement with an end terminal of saidbulb, said tube member having an internal passage through which the mobile lead extends, and manually operable means for completing the bulb-energizing circuit through said fixed and mobile leads, said mobile lead being longer than said passage thereby in use the mobile lead bows to provide a spring contact pressure at one end with the battery and at the other end with the bulb.
6. A laryngoscope according to claim 5, wherein said mobile lead has an insulating sheath and said electrically conductive tube is embedded in said blade portion with the forward end of the tube screw threaded to provide said light bulb socket.
7. A laryngoscope according to claim 6, wherein said fixed lead is embedded in said handle portion of the molding and interconnects the tube and an internally threaded sleeve disposed internally at the lower end of the handle, and wherein an end cap threaded into the sleeve provides said manually operable means.
8. A laryngoscope according to claim 5, wherein the metal tube forms part of an electrically conducting subassembly which also includes said sleeve and which is prefabricated from metal and embedded in the body molding.