Illumination assembly having fluid-tight seal
An illumination assembly for a medical diagnostic instrument, includes an open ended lamp housing, an incandescent lamp disposed within the housing. A peripheral sealing member is disposed in intimate contact with the exterior surface of the lamp envelope such that initial energization of said lamp causes the sealing member to create a substantial fluid-tight seal with the lamp to protect the interior of the housing, including the electrical contacts of the assembly.
1. An illumination assembly for a medical diagnostic instrument, said assembly including:
an open-ended lamp housing made from an electrically conductive material,
an incandescent lamp disposed within one end of said open-ended lamp housing, and
an O-ring disposed in intimate contact with said lamp, said O-ring being made from a material which has a transition temperature that is lower than that of an energized lamp, said O-ring being interposed between said electrically conductive lamp housing and the envelope of said lamp such that initial energization of said lamp causes said O-ring to chemically bond with said envelope and create a permanent circumferential fluid-tight seal with said lamp to prevent fluids from entering the confines of said lamp housing.
2. An assembly as recited in claim 1 , wherein said O-ring is made from silicone.
3. An assembly as recited in claim 1 , including a heat-resistive sleeve for covering the exterior of said open-ended lamp housing.
4. An assembly as recited in claim 1 , wherein the interior surface of said lamp housing includes an inner slot for retaining a peripheral portion of said O-ring.
5. A method of effectively and permanently sealing a lamp within an open-ended lamp housing, the method including the steps of:
disposing a miniature incandescent lamp into one end of an open-ended lamp housing, said lamp housing being made from an electrically conductive material;
placing the exterior surface of an O-ring disposed in said lamp housing between an interior surface of said electrically conductive lamp housing and said lamp and into compressive contact with the envelope of said miniature incandescent lamp, said O-ring being made from a material which has a transition temperature lower than that of an energized lamp; wherein
energizing said lamp creates a permanent substantially fluid tight seal between said lamp and said O-ring wherein said O-ring chemically interacts and coalesces with said lamp envelope.
6. A method as recited in claim 5 , wherein said O-ring is made from a material that is similar to that of the envelope of the incandescent bulb.
7. A method as recited in claim 6 , wherein said O-ring is made from silicone.
8. A method as recited in claim 5 , wherein the interior surface of said electrically conductive lamp housing includes at least one interior feature for retaining said O-ring.
9. A method as recited in claim 5 , wherein said lamp housing is part of an illumination assembly for a hand-held medical instrument.
10. A method as recited in claim 5 , wherein said O-ring is placed into said lamp housing prior to disposing said incandescent lamp therein.
11. A method for assembling an illumination assembly, said method comprising the steps of:
placing an annular sealing member within a circumferential slot of an open-ended lamp housing;
positioning a miniature incandescent lamp within said open-ended lamp housing such that the envelope of said lamp is in put into intimate compressive contact with the annular sealing member, said annular sealing member being made from a material which is similar to that of said lamp envelope and having a transition temperature that is lower than that of the exterior of an energized lamp; and
energizing said lamp thereby fusing said sealing member and said lamp housing together and creating a permanent fluid-tight seal between said lamp and said lamp housing wherein said energizing step fixedly positions said lamp in said illumination assembly.