Electric discharge tube, method of manufacturing the tube, stroboscopic device using the tube and camera

• US 6,810,208 B2
• Filed: 02/04/2004
• Issued: 10/26/2004
• Est. Priority Date: 02/19/2001
• Status: Expired due to Term

• Current Assignee: Panasonic Photo & Lighting Co. Ltd. (Panasonic Holdings Corporation)
• Original Assignee: West Electric Company Limited
• Inventors: Takahashi, Tsutomu, Saiki, Hiroshi, Omura, Fumiji
• Primary Examiner(s): PERKEY, WILLIAM B
• Application Number:
  US10/468,339
• Publication Number:
  US 20040114917A1
• Time in Patent Office: 265 Days
• Field of Search: 395/155, 313/594, 313/595, 313/613, 313/631, 313/635
• US Class Current: 396/155
• CPC Class Codes: H01J 61/0735 characterised by the material of the electrode
• CPC Class Codes: H01J 61/16 having helium, argon, neon, krypton, or xenon as the principle constituent
• CPC Class Codes: H01J 61/30 Vessels; Containers
• CPC Class Codes: H01J 61/35 provided with coatings on the walls thereof; Selection of materials for the coatings using coloured coatings H01J61/40; using luminescent coatings H01J61/42
• CPC Class Codes: H01J 61/545 using an auxiliary electrode inside the vessel H01J61/542 takes precedence
• CPC Class Codes: H01J 61/547 using an auxiliary electrode outside the vessel H01J61/544 takes precedence
• CPC Class Codes: H01J 61/82 Lamps with high-pressure unconstricted discharge having a cold pressure > 400 Torr
• CPC Class Codes: H01J 9/20 Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
• CPC Class Codes: H01J 9/247 specially adapted for gas-discharge lamps

Abstract

An electric discharge tube withstands a large electric input, and has a small size. This discharge tube provides a small photographic strobe device and a small photographic camera. The discharge tube includes a glass bulb having a wall thickness ranging from 0.2 to 0.6 mm and filled with rare gas, a pair of main electrodes provided at both ends of the glass bulb, respectively, a trigger electrode formed on the outer surface of the glass bulb, and a film of silicon dioxide having a thickness ranging from 0.05 to 0.11 μm formed inside of the glass bulb. An electric power not larger than 0.90 Ws/mm³ with respect to the inner volume of the glass bulb is applied between the main electrodes.

Claims

1. An electric discharge tube comprising:

a glass bulb having a wall thickness ranging from 0.2 to 0.6 mm and filled with rare gas;

a pair of main electrodes provided at both ends of said glass bulb, respectively;

a trigger electrode formed on an outer surface of said glass bulb; and

a film of silicon dioxide having a thickness ranging from 0.05 to 0.11 μ

m and formed on an inside of said glass bulb,

wherein an electric power not larger than 0.90 Ws/mm³ with respect to an inner volume of said glass bulb is applied between said main electrodes.

4. The electric discharge tube of any one of claims 1 to 3, wherein an weight of said film ranges from 0.35 to 0.60 μ

g/mm².

5. The electric discharge tube of any one of claims 1 to 3, wherein at least one of said main electrodes includes

a tungsten metal body, at least a portion of said tungsten metal body being sealed in said glass bulb,

a nickel metal body connected to said tungsten metal body, and

a sintered metal body provided at a leading end of said tungsten metal body, said sintered metal body being positioned inside of said glass bulb.

6. The electric discharge tube of any one of claims 1 to 3, wherein said film is provided by forming a silanol film on said glass tube before sealing said glass bulb, and by baking said silanol film.

7. The electric discharge tube of claim 6, wherein said film is provided by baking said silanol film by heating gradually from a first temperature to a second temperature.

8. The electric discharge tube of claim 6, wherein said flu is provided by immersing a portion of said silanol film for sealing said main electrode of said glass bulb in silanol-removing agent, and by cleaning and removing said silanol film.

9. The electric discharge tube of claim 8, wherein said silanol-removing agent includes aqueous solution of one of sodium hydroxide, potassium hydroxide, hydrofluoric acid, and ammonium fluoride.

17. A strobe device comprising:

said electric discharge tube of any one of claims 1 to 3;

a reflector having said electric discharge tube incorporated thereto for reflecting light emitted from said electric discharge tube;

a capacitor charged by a power source, for supplying an energy to said electric discharge tube; and

a trigger circuit for supplying a trigger voltage to said electric discharge tube.

18. A camera comprising:

said electric discharge tube of any one of claims 1 to 3;

a reflector having said electric discharge tube incorporated thereto, for reflecting light emitted from said electric discharge tube;

a capacitor charged by a power source, for supplying an energy to said electric the discharge tube; and

a trigger circuit for supplying a trigger voltage to said electric discharge tube.

19. The strobe device of claim 17, wherein an weight of said film ranges from 0.35 to 0.60 μ

g/mm².

20. The strobe device of claim 17, wherein at least one of said main electrodes includes

a tungsten metal body, at least a portion of said tungsten metal body being sealed in said glass bulb,

a nickel metal body connected to said tungsten metal body, and

a sintered metal body provided at a leading end of said tungsten metal body, said sintered metal body being positioned inside of said glass bulb.

21. The strobe device of claim 17, wherein said film is provide by forming a silanol film on said glass tube before sealing said glass bulb, and by baking said silanol film.

22. The camera of claim 18, wherein an weight of said film range from 0.35 to 0.60 μ

g/mm².

23. The camera of claim 18, wherein at least one of said main electrodes includes

a tungsten metal body, at least a portion of said tungsten metal body being sealed in said glass bulb,

nickel metal body connected to said tungsten metal body, and

a sintered metal body provided at a leading end of said tungsten metal body, said sintered metal body being positioned inside of said glass bulb.

24. The camera of claim 18, wherein said film is provided by forming a silanol film on said glass tube before sealing said glass bulb, and by baking said silanol film.

2. An electric discharge tube comprising:

a glass bulb having a wall thickness ranging from 0.2 to 0.6 mm and filled with rare gas;

a pair of main electrodes provided at both ends of said glass bulb, respectively;

a trigger electrode formed on an outside of said glass bulb; and

a film of silicon dioxide having a thickness ranging from 0.05 to 0.1 μ

m for covering an outside of said trigger electrode,

wherein an electric power not larger than 0.90 Ws/mm³ with respect to an inner volume of said glass bulb is applied between said main electrodes.

10. The electric discharge tube of claim 2, wherein said film is provided by applying a silanol film on said glass bulb except for a portion of said main electrodes, and baking said silanol film by raising a temperature of said glass bulb in gradual steps.

3. An electric discharge tube comprising:

a glass bulb having a wall thickness ranging from 0.2 to 0.6 mm and filled with rare gas;

a pair of main electrodes provided at both ends of said glass bulb, respectively,

a trigger electrode formed on an inside of said glass bulb; and

a film of silicon dioxide having a thickness ranging from 0.05 to 0.1 μ

m for covering said trigger electrode,

wherein an electric power not larger than 0.90 Ws/mm³ with respect to an inner volume of said glass bulb is applied between said main electrodes.

11. A method of manufacturing an electric discharge tube, comprising the steps of:

forming a trigger electrode on an outer surface of a glass tube;

forming a silanol film on the glass tube;

forming a film of silicon dioxide by baking the silanol film by raising a temperature of the glass tube having the silanol film from a first temperature to a second temperature higher than the first temperature; and

sealing both ends of the glass tube with a pair of main electrodes respectively, to provide a glass bulb, and filling the glass bulb with are gas.

12. The method of claim 11, wherein said step of forming the film comprises the sub-step of heating the silanol film in gradual steps from the first temperature to the second temperature.

13. The method of claim 11, further comprising the step of

removing a portion of the silanol film on the glass bulb corresponding to the main electrodes by immersing the portion of the silanol film in silanol-removing agent and cleaning the portion of the silanol film.

14. The method of claim 13, wherein the silanol-removing agent includes aqueous solution of one of sodium hydroxide, potassium hydroxide, hydrofluoric acid, and ammonium fluoride.

15. The method of claim 11,

wherein at least one of the main electrodes includes

a metal body including a tungsten metal body and a nickel metal body connected to the tungsten body, and

a sintered metal body provided at a leading end of the tungsten metal body, and

wherein said step of sealing the both ends of the glass tube comprises the sub-step of sealing the glass bulb with at least a portion of the tungsten metal body in the glass bulb while positioning the sintered metal body inside of the glass bulb.

16. A method of manufacturing an electric discharge tube, comprising the steps of:

forming a trigger electrode on an outer surface of a glass bulb having pair of main electrodes and filled with rare gas so that the trigger electrode is provided except for respective sealing portions corresponding to the main electrodes,

forming a silanol film for covering the trigger electrode, and

baking the silanol film by raising a temperature at the glass bulb having the silanol film.