Patent ID: 8397665
Filing Date: 2013-03-19
Classification: B05C,B29D

Abstract:
1. A device to produce a gradation of tint density on a plastic ophthalmic lens comprising: a lead screw connected to a first motor to lower a vertically oriented lens holder which holds vertically mounted lenses being spun by a second motor about its vertical axis into a heated tint bath containing water based tinting solution that is conducting, the tint bath consisting of a mixture of azo and anthraquinone dyes with surfactants in water; and wherein said motors are controlled by a software program of a programmable microcontroller; and the software program of the microcontroller board configured to regulate the vertical axis spinning rate to a value between 0 and 50 RPM; and the spinning rate being adjusted, based on the size and shape of the lenses, to produce a meniscus on the surface of the tinting solution that is depressed in the center while higher at the edges of the tint bath to produce a curved tint density gradation on the lenses having a greater tint density further down at the edges than at the center of the lens; and the software program of the microcontroller board is also configured to control the lowering rate of descent of the lens holder into the tinting solution so as to obtain the desired gradation of tinting density on the lenses.