Liquid crystal counterdrawing screen based on novel light dimming mechanism

Abstract

The invention discloses a liquid crystal counterdrawing screen based on a novel light dimming mechanism. The liquid crystal counterdrawing screen comprises a liquid crystal module, an LED lamp board,a driving board, an optical regulating system and a heat radiation board, wherein the LED lamp board is arranged at the lower end of the liquid crystal module; the driving board is used for driving anLED lamp; the optical regulating system is arranged at the lower end of the driving board; the heat radiation board is arranged at the lower end of the optical regulating system; the optical regulating system is used for selecting different modes to realize the brightness regulation on the LED lamp in different lamp light environments, and comprises a computer, an RS485 interface, a C8051330 chip, an analog light dimming module, a digital light dimming module and a driving module; the driving module is arranged on the driving board; the digital light dimming module realizes the brightness regulation by controlling the on-off time of the LED lamp; the analog light dimming module regulates the light brightness by controlling the power of an LED lamp loop; the RS485 interface is mainly usedfor communication; the C8051330 chip is used for controlling the signal output; the computer sends commands to the C8051330 chip according to the requirements so as to conduct the digital light dimming module or the analog light dimming module; and the driving module is used for driving the LED lamp to be turned on.

Description

technical field [0001] The invention relates to a liquid crystal screen, in particular to a copying liquid crystal screen based on a novel dimming mechanism. Background technique [0002] The dimming methods of the two kinds of LED LCD screens in the prior art are PMW dimming and DC dimming respectively. PWM dimming is due to cycle switching LED lights, and the screen flickers obviously in the high-brightness mode. Compared with the dimming mode of PMW, DC dimming The balance of dimming is not good in low current mode, black edges are easy to appear, and the circuit heats up seriously under the condition of high load and high power. [0003] The existing technology combines the above two modulation methods, adopts high-frequency PWM dimming mechanism under low brightness conditions, and adopts DC dimming mechanism under high brightness conditions; through the use of PWM signals under low brightness conditions to control the on-off cycle of LED lights, In order to achieve di...

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Problems solved by technology

[0004] However, under high brightness conditions, the DC linear dimming method is easy to overload the current under high power and high load, which is easy to burn electronic components; and the PWM high-frequency pulse signal at the zero crossing point is prone to waveform distortion, which affects the accuracy of dimming

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