Microfilm reader with variable brightness - has adjustable angle louvre shutter in front of lamp

摘要

The variable brightness microfilm reader, or slide viewer has a louvre shutter (5) on a pivot mounting between the lamp (2) and the screen from which the diffuse light is directed into the equipment. The shutter is linked to a control lever (8) which moves from a position of maximum transmission to minimum light, providing a gradual brightness control. The shutter is made of thin walled aluminium and has no moving parts. It is positioned in a parallel light beam while the lamp is a complete mounting including mirror. No electronic dimmer control is required. The display allows full detail to be displayed over a wide range of outside light level.