Lighting system for light guides
First Claim
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1. A lighting system for a light guide comprising:
- an arc-discharge-type light source;
a reflector having a parabolic reflecting surface which is arranged behind the light source; and
, an optical system for condensing light from the light source onto an end of a light guide, wherein the lighting system satisfies the following conditions
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Abstract
An apparatus and method is disclosed which stabilizes the light incident a light guide end over a guaranteed operating lifetime of a lamp used to illuminate the light guide end. The apparatus and method minimize variation in illumination incident a light guide end without, for example, controlling the electrical input to the lamp. The invention is especially effective for light guides having a narrow outer diameter, and compensates not only for movement of a region of maximum luminosity, as occurs in lamps where the cathode is partially consumed during operation of the lamp, but also for the lamp luminosity decreasing with age.
12 Citations
14 Claims
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1. A lighting system for a light guide comprising:
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an arc-discharge-type light source;
a reflector having a parabolic reflecting surface which is arranged behind the light source; and
,an optical system for condensing light from the light source onto an end of a light guide, wherein the lighting system satisfies the following conditions
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2. A lighting system for light guides comprising:
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a light source; and
an optical system for condensing light from the light source onto an end of a light guide;
wherein, at the beginning of lamp life operation, the maximum luminescent region of the light source is positioned, as measured from the position that inputs a maximum amount of condensed light into an end of the light guide, in a direction that is opposite the direction the maximum luminescent region of the light source shifts due to aging of the light source. - View Dependent Claims (3)
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4. A lighting system for light guides comprising:
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an arc-discharge light source having a first electrode and a second electrode; and
a reflector for gathering light from said arc-discharge light source;
wherein, in an arbitrary coordinate system having an origin defined by the intersection of the surface of said reflector with the optical axis of said reflector, a position vector Po is given by the following condition;
- View Dependent Claims (5, 6, 7)
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8. A lighting system for use in illuminating an end of a light guide, said lighting system comprising:
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a light source having an arc-discharge lamp which has an anode and a cathode, a reflector having a focal position, a sealed transparent envelope which surrounds the reflector, anode and cathode and which contains a gas capable of arc discharge; and
an optical system for condensing light from the light source onto a small region;
wherein the cathode of the arc-discharge lamp is arranged relative to the focal position of the reflector so as to provide less than a maximum illumination to the small region at the beginning of lamp life operation, and is instead arranged shifted from the position which provides a maximum illumination to the small region at the beginning of lamp life operation, the shift being in a direction opposite to the direction that a tip of the cathode moves as the cathode is depleted during a guarantee period of the lamp life, thereby reducing a variation in light incident said small region throughout said guarantee period. - View Dependent Claims (9, 10, 11)
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12. A method of illuminating an end of at least one light guide that may selectively be attachable to a lighting system, the lighting system using an arc-discharge type lamp to illuminate an end of an attached light guide, the arc-discharge type lamp having a cathode and an anode and an arc-discharge gas sealed within a transparent envelope and forming part of a lighting system which includes a reflector having a focal position, said method serving to reduce a variation in illumination on the end of the light guide over a guarantee period of the lamp, said method comprising the following step:
arranging the cathode of the arc-discharge lamp relative to the focal position of the reflector so as to be shifted from a position which provides a maximum illumination at the start of lamp life operation, with the direction of shift being in a direction opposite the direction that the portion of the cathode nearest the anode moves as the cathode is consumed during a guarantee period of the lamp. - View Dependent Claims (13, 14)
Specification