Illuminating devices employing titanium dioxide photocatalysts

• US 7,157,840 B2
• Filed: 12/24/2002
• Issued: 01/02/2007
• Est. Priority Date: 10/31/1994
• Status: Expired due to Fees

• Current Assignee: Kanagawa Academy of Science and Technology, Nippon Soda Company Limited
• Original Assignee: Kanagawa Academy of Science and Technology, Nippon Soda Company Limited
• Inventors: Fujishima, Akira, Iyoda, Tomokazu, Yoshimoto, Tetsuo, Saitoh, Tokuyoshi, Fukayama, Shigemichi, Hashimoto, Kazuhito
• Primary Examiner(s): Patel; Ashok
• Application Number:
  US10/327,042
• Publication Number:
  US 20030096701A1
• Time in Patent Office: 1,470 Days
• Field of Search: 313/485, 313112-114, 313/572, 313/573, 313/635, 313/580, 313/594, 313/607, 313/234, 359/359, 359/580, 359/584, 359/885, 359588-590, 359/891, 359/614, 362/2, 362/293, 362/296, 362/341
• US Class Current: 313/112
• CPC Class Codes: A61L 9/205 using a photocatalyst or photosensitiser
• CPC Class Codes: B01D 2255/20707 Titanium
• CPC Class Codes: B01D 2255/802 Photocatalytic
• CPC Class Codes: B01J 21/06 Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: C03C 17/2456 Coating containing TiO2
• CPC Class Codes: C03C 17/256 Coating containing TiO2
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• 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 61/42 by transforming the wavelength of the light by luminescence

Abstract

An illuminating device is made from a transparent hollow envelope that encloses a filler gas. The envelope has inner and outer surfaces. The illuminating device has a coating of a fluorescent material deposited on the inner surface of the transparent envelope where the fluorescent material emits light having a visible component and an ultraviolet component; and a titanium dioxide film having first and second opposing surfaces where the first surface of the titanium dioxide film is formed on the outer surface of the transparent envelope. A light transmittance of the titanium dioxide film is at least 50% for light having a wavelength of 550 nm, and the light transmitted from the fluorescent material through the transparent envelope and the first surface of the titanium dioxide film to the second surface thereof causes photocatalytic activity to be generated on the second surface of the titanium dioxide film.

Claims

1. An illuminating device comprising:

a transparent hollow envelope enclosing a filler gas, said envelope having inner and outer surfaces;

a coating of a fluorescent material deposited on the inner surface of said transparent envelope, said fluorescent material emitting light having a visible component and an ultraviolet component; and

a titanium dioxide film having first and second opposing surfaces, the first surface of said titanium dioxide film being formed on the outer surface of said transparent envelope, a light transmittance of said titanium dioxide film being at least 50% for light having a wavelength of 550 nm, the light transmitted from said fluorescent material through said transparent envelope and the first surface of said titanium dioxide film to the second surface thereof causing photocatalytic activity to be generated on the second surface of said titanium dioxide film wherein said titanium dioxide film contains an anatase crystal.

2. The illuminating device according to claim 1 wherein said fluorescent material is a phosphor having an ultraviolet component with a center wavelength of 365 nm, said titanium dioxide film reducing the ultraviolet component at the wavelength of 365 nm as it passes from the first to the second surfaces of said titanium dioxide film by at least 80%, whereby at least 0.5 μ

g of linoleic acid deposited per day per cm² on the second surface of said titanium dioxide film is decomposed.

3. The illuminating device according to claim 1 wherein said titanium dioxide film has a thickness of 0.3 μ

m to 5.0 μ

m.

4. The illuminating device according to claim 1 wherein said filler gas is argon at a pressure of 5 Torr.

5. An illuminating device comprising:

a transparent hollow envelope enclosing a filler gas, said envelope having inner and outer surfaces;

a coating of a fluorescent material deposited on the inner surface of said transparent envelope, said fluorescent material emitting light having a visible component and an ultraviolet component; and

a titanium dioxide film having first and second opposing surfaces, the first surface of said titanium dioxide film being formed on the outer surface of said transparent envelope, a light transmittance of said titanium dioxide film being at least 50% for light having a wavelength of 550 nm, the light transmitted from said fluorescent material through said transparent envelope and the first surface of said titanium dioxide film to the second surface thereof causing photocatalytic activity to be generated on the second surface of said titanium dioxide film wherein a transparent precoat film is interposed between the outer surface of said transparent envelope and said titanium dioxide film.

6. The illuminating device according to claim 5 wherein said transparent precoat film is composed of SiO₂.

7. The illuminating device according to claim 5 wherein said transparent precoat film has a thickness of 0.02 μ

m to 0.2 μ

m.

8. The illuminating device according to claim 5 wherein said transparent precoat film is composed of SiO₂ and indium tin oxide.

9. The illuminating device according to claim 5, wherein said transparent precoat film is composed of SiO₂ and has a thickness of 0.02 μ

m to 0.2 μ

m.