| 摘要 |
<p>A two transistor pixel drive circuit is presented for use with active matrix displays. A first transistor (T1) transfers video information from a video line to a storage capacitor (Cs2) when strobed. The stored charge modulates an alternating current (56, 60) flowing through a second transistor (T2). A light-modulating element (44), in series with an AC power supply (56) in one leg of the second transistor (T2), is activated by the modulated current for the duration of a frame time. A second AC power supply (60), in series with an additional capacitance (Ca) in the other leg of the second transistor (T2), generates a waveform of equal magnitude and opposite polarity to the first supply (56). The additional capacitance (Ca) provides an impedance that is about equal to that of the light-modulating element (44) at the activation frequency provided by the AC supplies (56, 60). With equal impedances in each leg of the second transistor (T2), a symmetrical circuit is created that holds the input to the second transistor (T2) at a fairly constant DC level independent of the relative phase between the strobe and AC power supply waveforms. This feature prevents the appearance of moving bands across the display. <IMAGE></p> |
