Liquid crystal light control device and circuit

Claim 2

A camera including in combination: lens means located in an image path suitable for transmitting an image to be photographed; and normally closed liquid crystal shutter means located in the image path and arranged to receive the image transmitted by said lens means, said liquid crystal shutter means including first and second liquid crystal cells and means for supplying operating potentials to said liquid crystal cells, the application of operating potential to the first of said cells causing molecules of liquid crystal material in said first cell to align and thereby to pass light through said shutter means, the subsequent application of operating potential to said second cell causing molecules of liquid crystal material in said second cell to align and thereby to block passage of light through said shutter means.

Claim 3

The camera of claim 1 further including: normally closed mecHanical shutter means located in said image path and in parallel with said lens means and said liquid crystal shutter means; mechanical means connected to said mechanical shutter means for opening said mechanical shutter means for a first fixed predetermined period of time; and electrical circuit means electrically connected to said liquid crystal shutter means for opening said liquid crystal shutter means for a second variable predetermined period of time which has a maximum value that is less than said first fixed predetermined period of time. 3. The camera of claim 2 wherein said liquid crystal shutter means includes in combination: first polarizer means polarized in a first predetermined direction; first liquid crystal cell means with a first surface juxtapositioned along said first polarizer means and a second surface which is parallel to said first surface, said first liquid crystal cell means having liquid crystal material with selectively oriented molecules interposed between said first and second surfaces thereof; second polarizer means juxtapositioned along said second surface of said first liquid crystal cell means, said second polarizer means also being polarized in said first predetermined direction; second liquid crystal cell means with a first surface juxtapositioned along said second polarizer means and a second surface which is parallel to said first surface of said second liquid crystal cell means, said second liquid crystal cell means having liquid crystal material with molecules selectively oriented in the manner that said molecules of said first liquid crystal cell means are oriented; and third polarizer means juxtapositioned along said second surface of said second liquid crystal cell means, said third polarizer means being polarized in a second predetermined direction which is perpendicular to the polarization of said first polarizer means and said second polarizer means.

Claim 4

The camera of claim 3 wherein: said first and said second liquid crystal cell means each include twisted nematic liquid crystal material located between and adjacent to said first and second surfaces thereof, said liquid crystal material adjacent said first surface being aligned in said first predetermined direction, said liquid crystal material adjacent said second surface being aligned in said second predetermined direction, said liquid crystal material between said first and second surfaces having unactivated orientations which very between said first and said second predetermined directions.

Claim 5

The camera of claim 4 further including: electrical circuit means having a first set of electrodes connected to said first liquid crystal cell means and a second set of electrodes connected to said second liquid cell means; said electric circuit means having a first circuit providing a first control voltage which activates said first liquid crystal cell to render the light control device transmissive; and said circuit means having a second circuit providing a second control voltage which activates said second liquid crystal cell to render the light control device non-transmissive.