Spectacle mounted variable neutral density filter holder

Details Spectacle mounted variable neutral density filter holder Spectacle mounted variable neutral density filter holder

1987-02-02

1988-11-08

Bovernick, Rodney B.

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

With antiglare or shading

351230, G02C 716, A61B 304

Patent

active

047831626

ABSTRACT:
A filter holder which clips on to an ophthalmic trial refraction frame or clip on to a person's spectacles with a clip on attachment is disclosed comprising a knob which rotates a shaft and a gear. The gear engages a ring with teeth in it. This ring is attached to a plate which has a channel cut through it, a pin to locate the position of the variable neutral density filter and a locking disc which holds the filter against the plate. On the back of the filter holder is a disc with an aperture mounted off the axis of symmetry of the filter holder so that the aperture is aligned with the channel in the edge of the plate. The patient sights through the aperture, the channel and the variable neutral density filter. By turning the knob, the neutral density filter rotates and the density in log units can be read on a scale on the front of the body of the filter holder.

REFERENCES:
patent: 2064812 (1936-12-01), Bouchard
patent: 2565362 (1951-08-01), Eloranta

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