Multichannel driver circuit for a spatial light modulator and method of calibration

In an imaging system that uses a spatial light modulator having a plurality of signal channels, an apparatus for obtaining a channel correction signal for calibrating each channel, the apparatus comprising:

• (a) for all channels, a standard signal generator for providing a standard reference video black-level signal;
• (b) a channel correction signal generator for generating, for each of said plurality of signal channels, a channel correction signal corresponding to a digital input value;
• (c) a comparator for comparing a summed signal comprising said channel correction signal and a channel video black-level signal against said standard reference video black-level signal, and for providing a comparator output signal indicative that said summed signal is equal to said standard reference video black-level signal;
• (d) a multiplexer for selectively switching said summed signal to said comparator, based on a channel selector signal;
• (e) a control logic processor for providing said channel selector signal to said multiplexer, for accepting said comparator output signal, and for executing a control program that obtains said channel correction signal for each channel and stores said channel correction signal in a memory.

In an image display apparatus employing a plurality of channel drivers for a spatial light modulator having a plurality of channels, a method for calibration of each individual channel driver, the method comprising:

• (a) over the positive half-cycle of a drive signal for said each individual channel, obtaining a positive channel correction signal by iteratively comparing, against a positive standard signal, a positive summed channel driver signal, said positive summed channel driver signal comprising a positive black-video channel driver signal added to a positive channel correction signal, and incrementing said positive channel correction signal until said positive summed channel driver signal equals said positive standard signal, at which time said positive channel correction signal is stored;
• (b) over the negative half-cycle of a drive signal for said each individual channel, obtaining a negative channel correction signal by iteratively comparing, against a negative standard signal, a negative summed channel driver signal, said negative summed channel driver signal comprising a negative black-video channel driver signal added to a negative channel correction signal, and incrementing said negative channel correction signal until said negative summed channel driver signal equals said negative standard signal, at which time said negative channel correction signal is stored;
• (c) obtaining a gain level by iteratively comparing a channel white-level signal against a standard white-level signal and incrementing a gain signal, until said channel white-level signal equals said standard white-level signal, at which time said gain signal is stored;
• and
• (d) wherein said positive channel correction signal, said negative channel correction signal, and said gain signal serve to calibrate said each individual channel driver.