Infrared absorption filter

• US 6,522,463 B1
• Filed: 11/13/2000
• Issued: 02/18/2003
• Est. Priority Date: 05/15/1998
• Status: Expired

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Kobayashi, Masanori, Shimomura, Tetsuo, Yamada, Yozo, Yokoyama, Seiichiro, Onomichi, Shinya
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): ASSAF, FAYEZ G
• Application Number:
  US09/700,299
• Time in Patent Office: 827 Days
• Field of Search: 359/350, 359/359, 359/360, 359/885, 252/587
• US Class Current: 359/350
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation

Abstract

The infrared absorption filter of the present invention has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm; a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm; and a transmittance of not lower than 50% at a wavelength of 550 nm, the filter being so excellent in environmental stability that after being left to stand in the air atmosphere at a temperature of 60° C. and a humidity of 95% for 1000 hours, the filter can maintain said spectral property in said range. Consequently, when used for a plasma display or the like, the filter can absorb the unwanted infrared rays radiated from the display, resulting in preventing erroneous operation of a remote control using infrared radiation even in such a high-temperature and high-humidity environment. The filter is gray in color so that when placed in front of a display, the color originated in the display can be seen without discoloration.

Claims

1. An infrared absorption filter which has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm;

a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm; and

a transmittance of not lower than 50% at a wavelength of 550 nm,

said filter, after being left to stand in the air atmosphere at a temperature of 60°

C. and a humidity of 95% for 1000 hours, having

a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm, and

a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm,

said filter having an infrared-absorbing layer on a transparent substrate,

the infrared-absorbing layer being composed of a coloring matter, dye or pigment absorbing infrared radiation and a polymer serving as a dispersing medium and

the transparent substrate having a total light transmittance of not lower than 89%, a haze of not higher than 1.6%, a coefficient of static friction of not higher than 0.6 and a coefficient of dynamic friction of not higher than 0.6.

2. The infrared absorption filter according to claim 1, wherein after being left to stand in the air atmosphere at a temperature of 80°

C. for 1000 hours, the filter has a transmittance of not higher than 30% in the near-infrared region in the wavelength of 800 to 1100 nm and has a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength of 450 to 650 nm.

3. The infrared absorption filter according to claim 1, wherein the amount of a solvent remaining in the infrared-absorbing layer is 5.0 wt. % or less.

4. The infrared absorption filter according to claim 1, wherein the transparent substrate is a polyester film.

5. The infrared absorption filter according to claim 1, wherein the polymer constituting the infrared-absorbing layer has a glass transition temperature of not lower than 80°

C.

6. The infrared absorption filter according to claim 5, wherein the polymer constituting the infrared-absorbing layer is a polyester resin.

7. The infrared absorption filter according to claim 1, wherein the filter has an electroconductive layer of metal mesh having an aperture ratio of not less than 50% on the same side as the infrared-absorbing layer of the filter or on the opposed side thereof.

8. The infrared absorption filter according to claim 1, wherein the filter has a transparent electroconductive layer on the same side as the infrared-absorbing layer of the filter or on the opposed side thereof.

9. The infrared absorption filter according to claim 8, wherein the transparent electroconductive layer is formed of a metal oxide.

10. The infrared absorption filter according to claim 8, wherein the transparent electroconductive layer has a repeatedly laminated structure in which at least three layers are laminated in the order of metal oxide/metal/metal oxide.

11. The infrared absorption filter according to claim 10, wherein the constituent metal layer of the transparent electroconductive layer is formed of silver, gold or a compound containing any of them.

12. The infrared absorption filter according to claim 1, wherein a hard coat-treated layer is formed as an outermost layer of the filter.

13. The infrared absorption filter according to claim 1, wherein an antireflection layer is formed as an outermost layer of the filter.

14. The infrared absorption filter according to claim 1, wherein an antiglare-treated layer is formed as an outermost layer of the filter.

15. The infrared absorption filter according to claim 1, wherein the filter is disposed in front of a plasma display.