Drive method and circuit for Polymer Dispersed Liquid Crystal (PDLC)

Abstract

The invention relates to a drive method and circuit for Polymer Dispersed Liquid Crystal (PDLC). A drive power supply is electrically connected with two input electrodes of the polymer dispersed liquid crystal film; the waveform of voltage applied to the input electrodes of the polymer dispersed liquid crystal film by the drive power supply is rectangular wave; and the front and rear edges of the rectangular wave are quickly changed, and the ascending and descending time of the rectangular wave is far less than the opening and closing response time of the polymer dispersed liquid crystal film. The drive power supply comprises a rectangular wave generating circuit, a drive stage and a double-arm bridge type pull output circuit, wherein the double-arm bridge type pull output circuit comprises four field effect transistors. The method effectively eliminates the screen splash phenomenon, does not need to drive the frequency of the alternating voltage of the PDLC film to synchronize with the frame frequency of a display observed through the PDLC film by adopting a scanning mode, improves the transmittance of the transparent state of the PDLC film and reduces the haze.

Description

technical field [0001] The invention relates to a driving method and circuit of a polymer-dispersed liquid crystal film. The driving method adopts an AC voltage waveform whose voltage quickly crosses zero, and its frequency and phase can be compared with those passed through the polymer-dispersed liquid crystal film. The scanning frame rate of the monitor using the scanning method is observed regardless of the scanning frame rate. Driving the polymer-dispersed liquid crystal film in this way can eliminate the flickering phenomenon of viewing other types of display screens through the polymer-dispersed liquid crystal film, increase the transmittance of the polymer-dispersed liquid crystal film in a transparent state, and reduce the haze. technical background [0002] US Patent No. 4,671,618 discloses a method for making phase-separated polymer-dispersed liquid crystals. This method can be used to make polymer-dispersed liquid crystal films and PALC films, which are collective...

AI Technical Summary

Problems solved by technology

The PDLC film is generally driven by a sinusoidal AC power frequency voltage. The disadvantage is that when the human eye observes the display screen of a display (including a projection display) that uses a scanning method through the PDLC film, due to the scanning frame rate of the display scanning system and the PDLC If the frequency of the AC working voltage or its multiplier frequency is different and the phase difference is different, you will see the phenomenon of flickering and jumping on the screen, referred to as the phenomenon of screen flickering

However, this solution cannot eliminate the screen flicker phenomenon when multiple displays with different frame rates are combined to form a display wall through the PDLC film at the same time.

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