Active matrix liquid crystal image generator

A system for producing modulated light having gray scale, said system comprising:

• (a) an active matrix liquid crystal spatial light modulator having
• (i) light modulating means including a layer of ferroelectric liquid crystal material which is designed to switch between ON and OFF states, and
• (ii) active matrix means including VLSI circuitry for dividing said layer of liquid crystal material into an array of individual liquid crystal pixels and for causing each of said pixels of liquid crystal material to modulate light individually by switching between said ON and OFF states in a way that depends upon the data which the VLSI circuitry is written, said VLSI circuitry of said active matrix means including an array of subcircuits, each of which is dedicated to and defines a specific one of said pixels, said layer of ferroelectric liquid crystal material being maintained at a substantially uniform thickness of at most approximately 2 microns, whereby the size of said pixels can be made smaller than would be the case if the layer of liquid crystal were much thicker, for example of the order of 6 microns as required by nematic liquid crystal material in spatial light modulators;
• (b) illumination means including a light source for directing light from said source into said pixel-divided layer of ferroelectric liquid crystal material;
• and
• (c) means for writing said VLSI circuitry with preselected data in accordance with a particular data ordering scheme such that said circuitry, in response to the data, causes said pixels of liquid crystal material to individually switch between their ON and OFF states for a plurality of subframes which make up a given time frame and therefore modulate light from said source in a way which, depending upon said data, produces a specific overall pattern of gray scale light, said particular data ordering scheme being such that said data writing means writes each of said subcircuits and therefore each of said pixels with preselected data in a predetermined successive order, timewise, such that none of said subcircuits require auxiliary data storage buffer circuitry and therefore the complexity of said array of subcircuits can be reduced.

A system for producing modulated light having gray scale during a given period of time comprising:

• (a) a spatial light modulator including a plurality of light modulating pixels switchable between different states so as to act on light in different ways during a plurality of light modulating subperiods making up said period of time said pixels being arranged in specific groups of said pixels;
• (b) illumination means for directing light of either different brightnesses or different colors alternately and successively into said light modulating pixels during predetermined ones of said light modulating subperiods of said period;
• and
• (c) switching means, responsive to preselected data signals, for switching said pixels to certain light modulating states in a controlled way during each light modulating subperiod of said period in order to modulate said light directed into said light modulating pixels during said light modulating subperiods, said switching means including means for simultaneously switching each of said groups of pixels, one group at a time, during each of said subperiods, said period further including a blackout subperiod during which said switching means switches all of said pixels to an OFF state in response to said preselected data signals in order to black out said light directed into said pixels thereby allowing either the brightness or the color of said light directed into said pixels by said illumination means to be changed without effecting the gray scale of said modulated light during said period.

A method of producing modulated light having gray scale during a given period of time, the method comprising the steps of:

• (a) providing a spatial light modulator including a plurality of light modulating pixels switchable between different states so as to act on light in different ways during a plurality of light modulating subperiods making up said period of time, said pixels being arranged in specific groups of said pixels;
• (b) directing light of either different brightnesses or different colors alternately and successively into said light modulating pixels during predetermined ones of said light modulating subperiods of said period;
• (c) in response to preselected data signals, switching said pixels to certain light modulating states in a controlled way during each light modulating subperiod of said period in order to modulate said light directed into said light modulating pixels during said light modulating subperiods, each of said groups of pixels being switched into their light modulating states, one group at a time during each of said subperiods;
• and
• (d) in response to said preselected data signals, switching all of said pixels to an OFF state during a blackout subperiod in order to black out said light directed into said pixels thereby allowing either the brightness or the color of said light directed into said pixels to be changed without effecting the gray scale of said modulated light during said period.

A method of displaying gray scale or color images, the method comprising the steps of:

• (a) providing an array of light modulating pixels organized in rows, each pixel being switchable between a first pixel state and a second blackout pixel state in response to input data;
• (b) switching all of said pixels to said second blackout pixel state;
• (c) after all of said pixels have been switched to said second blackout pixel state, illuminating said array of pixels with light of a first desired brightness and color;
• (d) while said array of pixels is being illuminated with said desired brightness and color of light, switching the states of said pixels in each of said rows such that said array of pixels forms a desired pattern of modulated light, at least some of said rows of pixels being switched at different times from other ones of said rows;
• (e) switching all of said pixels to said second blackout pixel state a second time in such a manner that the time interval between the time at which the states of the pixels in each row are switched to form said desired pattern of modulated light and the time at which that row is switched to said second blackout pixel state said second time is the same for each row of pixels;
• and
• (f) after all of said pixels have been switched to said second blackout pixel state said second time, illuminating said array of pixels with light of a second desired brightness and color.