Driving method for photoconductive-type SLM

A display apparatus comprising:

• a light-emitting array (REA) including N light-emitting elements disposed in a row in connection with N picture elements;
• drive circuit means (DCT) for activating each of said N light-emitting elements to emit a writing light (WL) whose light quantity varies from a predetermined minimum value to a predetermined maximum value (Iw.times..GAMMA.) on the basis of image information of a corresponding one of N picture elements;
• deflecting means (Mg) for deflecting said writing light (WL) emitted from said light-emitting array (REA);
• a spatial light modulator (SLM) including a photoconductive layer member (PCL), a photo-modulation layer member (PML) used in a birefringence operating mode, and two electrodes (Et1, Et2) sandwiching said two members (PCL, PML);
• a converging means (L) for focusing said writing light (WL) deflected at the deflection means (Mg) on said photoconductive layer member (PCL) in said spatial light modulator (SLM);
• said photoconductive layer member (PCL) changing its electric resistance value in accordance with the light quantity of said writing light (WL), thereby applying a voltage (Vp) between both ends of said photo-modulation layer member (PML);
• a light source (LS) for generating a reading-out light (RL);
• a polarization beam splitter (PBS) reflecting said reading-out light (RL) supplied from said light source (LS) toward said spatial light modulator (SLM);
• said reading-out light (RL) being modulated in said spatial light modulator (SLM), so as to have a polarization plane modulated in accordance with said image information;
• said polarization beam splitter (PBS) receiving the reading-out light (RL) reflected back from said spatial light modulator (SLM);
• a projection lens (Lp) for diffusing said reading-out light (RL) from said polarization beam splitter (PBS) onto a screen (S);
• and
• adjusting means for adjusting said voltage (Vp) to be larger than a reference voltage when said writing light (WL) having said predetermined maximum value (Iw.times..GAMMA.) enters into said photoconductive layer member (PCL), said reference voltage being identical with a voltage at which intensity of said reading-out light (RL) takes an extreme value in a characteristic curve (E.sub.0 .fwdarw.A.fwdarw.B.fwdarw.C) showing a relationship between the voltage (Vp) applied to said photo-modulation layer member (PML) and the intensity of reading-out light (RL).