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US 4,977,346 AGranted
High pressure sodium discharge lamp having gas filled outer envelope
AssigneeNorth American Philips Corporation
InventorsRay G. Gibson, Joseph Droho
Life of this patent
Estimating the term…
Abstract
A discharge lamp comprises an HPS discharge device within an outer envelope filled with inert gas. A normally nonconductive spark gap device within the outer envelope is connected across conductors used to apply a voltage to the HPS discharge device. The spark gap breaks down when the applied voltage exceeds a certain value to prevent breakdown through the inert gas within the outer envelope.
Claims8
A high pressure sodium discharge lamp, comprising:
- an outer lamp envelope;
- a high pressure sodium discharge device within said outer envelope and energizable by an applied voltage for emitting light;
- means comprising conductors within said outer envelope connected to said discharge device for defining a conductive path to apply a voltage to said discharge device;
- an inert gas within said outer envelope;
- means comprising a normally nonconductive spark gap within said outer envelope, isolated from said inert gas atmosphere within said outer envelope, and responsive to the voltage between said conductors and applied to said high pressure sodium discharge device for breaking down when the applied voltage exceed a certain predetermined value to prevent breakdown through the inert gas atmosphere between said conductors.
2 more elements
A high pressure sodium discharge lamp, comprising:
- an outer lamp envelope;
- a high pressure sodium discharge device having a characteristic starting voltage and disposed within said outer envelope, said discharge device energizable to initiate a discharge therein and emit light upon the application of a voltage exceeding said characteristic starting voltage to said discharge device, and said discharge device exhibiting an increased starting voltage after said discharge device attains an elevated operating temperature;
- conductors within said outer envelope connected to said discharge device for defining a conductive path to apply a voltage to energize said discharge device;
- an inert gas atmosphere within said outer envelope, said inert gas atmosphere exhibiting electrical breakdown between said conductors when the applied voltage exceeds a certain breakdown voltage value, said breakdown voltage increasing after said discharge device attains an elevated operating temperature;
- and
- means within said outer envelope connected across said conductors and exhibiting a high impedance below a certain applied voltage and a low impedance above said certain applied voltage.
3 more elements
A high pressure sodium discharge lamp, comprising:
- a blown glass outer lamp envelope;
- a high pressure sodium discharge device within said outer envelope and energizable by an applied voltage for emitting light,
- conductors within said outer envelope connected to said discharge device for defining a conductive path to apply a voltage to energize said discharge device;
- an inert gas atmosphere within said outer envelope, said inert gas atmosphere having a fill pressure less than one atmosphere and having a pressure of approximately one atmosphere when heated by said discharge device during normal lamp operation, and said inert gas atmosphere exhibiting electrical breakdown between said conductors when the applied voltage exceeds a certain breakdown voltage value;
- and
- means comprised of a self-restoring threshold switch for establishing a low impedance circuit path between said conductors and isolated from said argon atmosphere when the voltage between said conductors exceeds the threshold voltage of said threshold switch, said threshold switch having a threshold voltage which is greater than the starting voltage of said discharge device and less than the breakdown voltage of the argon fill gas between said conductors.
3 more elements
Dependencies are inferred from the claim text.