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

• US 20070242348A1
• Filed: 09/22/2005
• Published: 10/18/2007
• 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
• Granted Patent: US 7,466,480 B2
• Time in Patent Office: Days
• 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 is BOROFLOAT® and the preferred diffusion paint is marketed by Schmelzfarben GmbH, Germany, under the product name, Red-brown mordant, and Type No. P 76 050.

Claims

1. A UV-blocking filter comprising a disk-shaped glass body and at least one layer of silver-containing diffusion paint adhering to the glass body that blocks ultraviolet light, said glass body consisting of a borosilicate float glass.

2. The UV-blocking filter as defined in claim 1, wherein said borosilicate float glass is marketed under the trademark BOROFLOAT®

.

3. The UV-blocking filter as defined in claim 1, wherein the diffusion paint is marketed by Schmelzfarben GmbH, Germany under the product name, Red-brown mordant, and Type No. P 76 050.

4. The UV-blocking filter as defined in claim 2, wherein the diffusion paint is a paint marketed by Schmelzfarben GmbH, Germany, under the product name, Red-brown mordant, and Type No. P 76 050.

5. 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.

6. The UV-blocking filter as defined in claim 1, which 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 in a range greater than about 600 nm.

7. The UV-blocking filter as defined in claim 1, wherein the silver-containing diffusion paint is applied to the glass body and burned-in to the glass body in a baking oven at temperatures of 580°

C. to 620°

C. for a sufficiently a long holding time, so that diffusion of silver ions into the borosilicate glass takes place and the at least one layer of the silver-containing diffusion paint is stable at temperatures up to 500°

C.

8. The UV-blocking filter as defined in claim 1, wherein said at least one layer of the silver-containing diffusion paint is stable at temperatures up to 500°

C.