UV-blocking filter comprising a layer of temperature stable silver-containing diffusion paint on a borosilicate glass body

• US 7,466,480 B2
• Filed: 09/22/2005
• Issued: 12/16/2008
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Original Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Inventors: Berninger, Wolfgang
• Primary Examiner(s): Pritchett; Joshua L
• Application Number:
  US11/232,652
• Publication Number:
  US 20070242348A1
• Time in Patent Office: 1,181 Days
• Field of Search: 359/361
• US Class Current: 359/361
• CPC Class Codes: G02B 5/283 designed for the ultraviolet

Abstract

The UV-blocking filter is a disk-shaped glass body made of borosilicate float glass, which has a layer of silver-containing diffusion paint adhering to it, which blocks ultraviolet light, so that the UV-blocking filter resists a high thermal load up to temperature of about 500° C. The preferred borosilicate float glass has a composition, in percent by weight, of SiO₂, 81; B₂O₃, 13; Σ Na₂O+K₂O, 4; and Al₂O₃, 2. The preferred diffusion paint is a red-brown mordant, which contains 44.0 percent by weight of copper-II-sulfate-5-hydrate, 25.0 percent by weight Ag₂O, Fe, and Ba.

Claims

1. A UV-blocking filter consisting of

a disk-shaped glass body, and

a silver-containing diffusion paint layer coated on and adhering to said glass body;

wherein said glass body consists of a borosilicate float glass and the silver-containing diffusion paint layer comprises 44.0 percent by weight of copper-II-sulfate-5-hydrate and 25.0 percent by weight Ag₂O, Fe and Ba;

whereby the filter is substantially light impermeable in a wavelength range of 400 to 460 nm, but transmits a major portion of incident light and infrared radiation having wavelengths greater than about 600 nm.

2. The UV-blocking filter as defined in claim 1, wherein said borosilicate float glass contains 81 percent by weight of SiO₂, 13 percent by weight of B₂O₃, 4 percent by weight of a sum of Na₂O and K₂O, and 2 percent by weight of Al₂O₃.

3. The UV-blocking filter as defined in claim 1, wherein the borosilicate float glass has a linear thermal expansion coefficient of 3.3×

10<sup>−

6</sup>/K, a transformation temperature, T_g, of 525°

C., and a softening temperature, Ew, of 820°

C.

4. The UV-blocking filter as defined in claim 1, wherein said silver-containing diffusion paint layer remains stable at temperatures up to 500°

C.

5. A UV-blocking filter consisting of

a disk-shaped glass body, and a silver-containing diffusion paint layer coated on and adhering to said disk-shaped glass body, whose effective coloring ingredients penetrate adjacent regions of the glass body, on which the diffusion paint layer adheres, after the diffusion paint is burned-in in a baking oven at temperatures of 580 to 620°

C. for a sufficiently long time interval;

wherein said glass body consists of a borosilicate float glass and said borosilicate float glass contains 81 percent by weight of SiO₂, 13 percent by weight of B₂O₃, 4 percent by weight of a sum of Na₂O and K₂O, and 2 percent by weight of Al₂O₃, and

wherein the silver-containing diffusion paint layer comprises 44.0 percent by weight of copper-II-sulfate-5-hydrate and 25.0 percent by weight Ag₂O, Fe and Ba;

whereby the filter is substantially light impermeable in a wavelength range of 400 to 460 nm, but transmits a major portion of incident light and infrared radiation having wavelengths greater than about 600 nm.

6. The UV-blocking filter as defined in claim 5, wherein the borosilicate float glass has a linear thermal expansion coefficient of 3.3×

10<sup>−

6</sup>/K, a transformation temperature, T_g, of 525°

C., and a softening temperature, Ew, of 820°

C.

7. The UV-blocking filter as defined in claim 5, wherein said silver-containing diffusion paint layer remains stable at temperatures up to 500°

C.