Light transmitting electromagnetic wave filter and process for producing the same

• US 20020086164A1
• Filed: 12/11/2001
• Published: 07/04/2002
• Est. Priority Date: 04/06/1999
• Status: Active Grant

• Current Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Inventors: Anzaki, Toshiaki, Ogino, Etsuo
• Granted Patent: US 6,579,423 B2
• Time in Patent Office: Days
• US Class Current: 428/432
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: C03C 17/36 at least one coating being a metal
• CPC Class Codes: C03C 17/3613 Coatings of type glass/inorganic compound/metal/inorganic compound/metal/other
• CPC Class Codes: C03C 17/3639 Multilayers containing at least two functional metal layers
• CPC Class Codes: C03C 17/3644 the metal being silver
• CPC Class Codes: C03C 17/3676 specially adapted for use as electromagnetic shield
• CPC Class Codes: C03C 2217/78 Coatings specially designed to be durable, e.g. scratch-resistant
• CPC Class Codes: C23C 14/08 Oxides C23C14/10 takes precedence
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361
• CPC Class Codes: G02B 5/287 comprising at least one layer of organic material
• CPC Class Codes: H01J 2211/446 Electromagnetic shielding means; Antistatic means
• CPC Class Codes: H05K 9/0096 for television displays, e.g. plasma display panel

Abstract

A light transmitting electromagnetic wave filter comprising a transparent and a light transmitting electromagnetic wave shield film having a laminate structure composed of 2n+1 (n≧1) layers in which at least two dielectric layers and at least one silver layer are alternately laminated, with each other with the dielectric layer being the first to be provided on the transparent substrate, wherein at least one of the dielectric layers is an antistatic metal oxide layer having a refractive index of 1.6 to 2.7 at a wavelength of 550 nm, which is preferably formed by sputtering using a metal oxide, e.g., tin-containing indium oxide, as a target in an atmosphere having a reduced oxygen content. The electromagnetic wave filter has a high visible light transmission and a low near infrared transmission, is free from pin holes or contamination, and exhibits high durability against moist heat, etc.

Claims

1. A light transmitting electromagnetic wave filter comprising a transparent substrate having on one side thereof a light transmitting electromagnetic wave shield film comprising a laminate of 2n+1 (n≧

1) layers in which at least two dielectric layers and at least one silver layer are alternately laminated, with each other with the dielectric layer being the first to be provided on the transparent substrate, wherein at least one of said dielectric layers is an antistatic metal oxide layer having a refractive index of 1.6 to 2.7 at a wavelength of 550 nm.

2. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer has a specific resistance of 5 Ω

cm or less.

3. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises indium oxide as a main component, said indium oxide containing tin.

4. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises tin oxide as a main component, said tin oxide containing at least one metal selected from the group consisting of antimony, bismuth, zinc, and indium.

5. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises zinc oxide as a main component, said zinc oxide containing at least one metal selected from the group consisting of aluminum, gallium, and indium.

6. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises zirconium oxide as a main component, said zirconium oxide containing at least one metal selected from the group consisting of vanadium, niobium and tantalum.

7. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises cerium oxide as a main component, said cerium oxide containing praseodymium.

8. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises niobium oxide as a main component, said niobium oxide containing molybdenum.

9. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said antistatic metal oxide layer comprises titanium oxide as a main component, said titanium oxide containing at least one metal selected from the group consisting of vanadium and niobium.

10. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein at least the outermost one of said dielectric layers is a laminate comprising said antistatic metal oxide layer and a barrier layer selected from the group consisting of silicon nitride, silicon oxynitride, and tin oxide.

11. The light transmitting electromagnetic wave filter as claimed in claim 1, wherein said silver layer contains 0.1 to 3% by weight of palladium and 0.1 to 3% by weight, in total, of titanium and/or copper.

12. The light transmitting electromagnetic wave filter as claimed in claim 1, which has a luminous transmittance of 60% or more and a transmission of 20% or less at a wavelength of 850 nm.

13. The light transmitting electromagnetic wave filter as claimed in claim 12, wherein said light transmitting electromagnetic wave shield film is a 7-layered laminate (n=3) in which the dielectric layer closest to the transparent substrate has a thickness of 28 to 52 nm, the four dielectric layers have a thickness ratio of 36±

4;

71±

7;

70±

7;

32±

3 in the order from the layer closest to the substrate, the silver layer closest to the transparent substrate has a thickness of 7 to 18 nm, and the three silver layers have a thickness ratio of 10±

1;

12±

1;

10±

1 in the order from the layer closest to the substrate.

14. The light transmitting electromagnetic wave filter as claimed in claim 12, which has a resin film adhered to the surface of said light transmitting electromagnetic wave shield film with a pressure-sensitive adhesive.

16. The process for producing a light transmitting electromagnetic wave filter as claimed in claim 15, wherein the sputtering for forming the antistatic metal oxide layer is carried out in such a manner that a sintered body of a metal oxide powder is set on a pair of adjacent magnetron cathodes, and a negative voltage is applied to each cathode while alternately reversing the polarities of the targets at a frequency of 10 Hz to 1 MHz to generate glow discharge plasma thereby to sputter the target.

15. A process for producing a light transmitting electromagnetic wave filter comprising a transparent substrate having on one side thereof a light transmitting electromagnetic wave shield film comprising 2n+1 (n≧

1) layers in which at least two dielectric layers comprising an antistatic metal oxide layer and at least one silver layer are alternately laminated with each other with the dielectric layer being the first to be provided on the transparent substrate, wherein said silver layer is formed by sputtering using silver as a target, and said antistatic metal oxide layer is formed by sputtering using, as a target, a metal oxide whose sheet resistance is 50 Ω

/□

or less.