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US 2002/0117965 A1Published application
High buffer gas pressure ceramic arc tube and method and apparatus for making same
AssigneeOsram Sylvania Inc.
InventorsStefan Kotter, Gregory Zaslavsky, Fred Whitney
Life of this patent
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Abstract
A ceramic arc tube for high intensity discharge (HID) lighting applications is provided wherein the arc tube contains a high buffer gas pressure. A method and apparatus for making the arc tube are also provided wherein RF induction heating is used to melt a frit material to form a hermetic seal.
Claims31
A ceramic arc tube comprising:
- a discharge vessel having at least one capillary having an electrode assembly, the capillary extending outwardly from the discharge vessel to a distal capillary end, the electrode assembly being hermetically sealed to the distal capillary end with a frit material, the electrode assembly passing through the capillary to the discharge chamber and being connectable to an external source of electrical power, the discharge vessel enclosing a discharge chamber containing a buffer gas and an ionizable fill material, the pressure of the buffer gas being from 2 bar to 8 bar.
An apparatus for making a ceramic arc tube comprising:
- a pressure jacket having a pressure chamber containing an RF susceptor, the susceptor having an opening for receiving a capillary of the arc tube, an RF induction coil situated external to the pressure jacket and surrounding the RF susceptor, the RF induction coil being connected to an RF power source;
- the pressure chamber being connected to a source of pressurized buffer gas and a vacuum source, the source of pressurized buffer gas being regulated by a valve connected to a pressure controller having a pressure sensor for measuring the pressure in the pressure chamber;
- a holder having a support for the arc tube, the height of the support being selected to cause an unsealed end of the arc tube to be positioned within the RF susceptor when the holder is sealed to the apparatus;
- and
- the apparatus when sealed being capable of alternately evacuating the pressure chamber and filling the pressure chamber with buffer gas.
2 more elements
A method for sealing a ceramic arc tube comprising:
- (a) sealing the arc tube within a pressure chamber, the arc tube comprising a discharge vessel and at least one capillary, the capillary extending outwardly from the discharge vessel to a distal capillary end having a frit material, the chamber containing an RF susceptor surrounding the distal capillary end;
- (b) filling the chamber with a buffer gas to a predetermined pressure;
- and
- (d) heating the RF susceptor by energizing an RF induction coil with an RF power source, the RF induction coil being external to the chamber and surrounding the RF susceptor, the heat generated by the RF susceptor causing the frit material to melt and flow into the distal capillary end;
- and
- (e) cooling the frit material to form a hermetic seal.
3 more elements
Dependencies are inferred from the claim text.