CIRCUIT FOR REALIZING LIQUID CRYSTAL GRADATION BY PWM

摘要

The present invention provides a circuit for realizing liquid crystal gradation by PWM. The circuit includes a pulse generation module, a gradation data reading control module, a gradation data storage, a frame synchronistical generation module and a gradation modulation module. The gradation modulation module includes a primary stage unit modulation circuit and at least one posterior stage unit modulation circuit. The posterior stage unit modulation circuit includes a first selector and a second selector. The gradation data of the posterior stage is used as the selecting signal for the first selector, while the reference pulse signal of the posterior stage and the inversion of the reference pulse signal of the posterior stage are used as the input signal for the first selector. The output signal of the first selector is used as the selecting signal for the second selector, while the gradation data of the posterior stage and the output pulse signal of the prior stage are used as the input signal for the second selector, the output signal of the second selector is used as the output pulse signal of the posterior stage.