1. Field of the Invention
This invention relates to a light-diffusing hollow glass brick composed of two half-bricks.
2. Description of the Related Art
As a general rule, hollow glass bricks are produced by fusing to one another two half-bricks produced by a pressing process. In this case, it is common to provide the wall of at least one of the half-bricks with an ornamental, decorative or light-deflecting impression. These glass bricks keep their transparency to a certain extent. Due to the design of the impression, the light is often deflected in determined, preferred directions.
Glass bricks are also known that scatter or diffuse the light to a large extent. These glass bricks, when they are part of an exterior wall of a room, make possible a very uniform lighting of the room independently of the angle of incidence of the light rays. In addition, they make the glass translucent, quite like opal glass.
A known light-diffusing glass brick contains fine particles in the bulk of the glass, for example particles of sodium sulfate or sodium sulfide in a dispersed state (document DE-38 20 600 A1). In this case, the glass is an opal glass having reduced overall transparency which, for a glass thickness of 10 mm, is between 20 and 80% in the wave length range of 400 to 700 nm. These glass bricks can be produced only by use of special glass compositions having an appreciably increased sulfur content. However, the process of melting these glasses is disturbing for the environment.
Further, it is known to make a glass brick with scattering or diffusion of light by frosting, e.g., by sandblasting or acid treatment (document DE-GM 1 874 435), of the exterior surface of the wall intended for the passage of light. These frosted surfaces are very susceptible to soiling. Moreover, they lose their light diffusion effectiveness when they are wet, for example in case of rain. Surface frosting, in addition, involves an additional treatment step, which inevitably increases the cost of the product.