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.
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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