CN101188099A

CN101188099A - LCD display impulse width modulation and light adjusting mode

Info

Publication number: CN101188099A
Application number: CNA2007101901503A
Authority: CN
Inventors: 韩伟伟
Original assignee: LG Electronics Nanjing Plasma Co Ltd
Current assignee: LG Electronics Nanjing Plasma Co Ltd
Priority date: 2007-11-19
Filing date: 2007-11-19
Publication date: 2008-05-28

Abstract

The invention discloses a PWM light-adjusting manner of a LCD, which can adjust the brightness of the display by changing the duty cycle of the lamp current of a module compared with the prior art. The invention comprises that (1) the E < 2 > ROM storage value of a register on a motherboard can be changed according to the brightness setting of users; (2) a microcontroller on the motherboard adjusts the output of the duty cycle of the Dimming signals; (3) the output driving signals of a control chip in an inverter module are changed according to the Dimming signals; (4) the control chip adjusts the duty cycles of output voltage and output current of a transformer in the inverter module; (5) the brightness of the module is changed. The invention has the beneficial effects that the brightness contrast of the LCD can be optimized, and the lumen ratio can be improved to the maximum of 4:1; and the brightness of the display can be increased by changing the duty cycle of the lamp current of the module, so that viewers can get a better visual experience.

Description

The LCD display impulse width modulation and light adjusting mode

Technical field

The present invention relates to a kind of brightness adjustment approach of LCD display, particularly a kind of LCD display width modulation (PWM) dimming mode.

Background technology

The brightness regulation of existing LCD display adopts the simulation dimming mode, this is a kind of traditional dimming mode, the main progress of work is described as: mainboard is by MCU and peripheral circuit, offer DC voltage of power panel (LIPS-LCD inverter power supply) of LCD, control IC on the Inverter is according to the output of the height control transformer of this voltage, and transformer offers the output voltage of module and the effective value of output current.The voltage and current that offers moduler because of power panel all exchanges, so effective value, amplitude A refer to the parameter (rms) of this AC signal and change, the mode that changes is the variation by amplitude, changing of the light tube electric voltage of module and lamp current, brightness also changes thereupon, and Here it is simulates the principle of work of dimming mode.The testing standard requirement LCD display of up-to-date TCO03 can be at Luminance＜150cd/m ²The Shi Jinhang operate as normal.But the lumen of traditional simulation dimming mode can only reach 2: 1 than maximum, is 300cd/m with the brightness of shielding ²Be example, be difficult to satisfy the requirement of TCO03, also lack allowance.

Summary of the invention

Goal of the invention: the present invention is directed to the defective of existing LCD display dimming mode, a kind of LCD display PWM dimming mode of optimization is provided.

Realize that technical scheme of the present invention is: a kind of LCD display PWM dimming mode is characterized in that this dimming mode may further comprise the steps:

(1) according to user's brightness settings, changes register E on the mainboard ²The storing value of ROM;

(2) microcontroller on the mainboard is adjusted the output of Dimming signal dutyfactor;

(3) according to the Dimming signal, the output drive signal of the control chip in the inverter module changes;

(4) dutycycle of transformer output voltage and output current in the control chip adjustment inverter module;

(5) change of the brightness of Module.

Wherein the Dimming signal in step (2) and the step (3) is the one group of square-wave signal that can regulate.

Beneficial effect: the present invention can optimize the luminance contrast of LCD display, makes lumen can reach 4: 1 than maximum, and the dutycycle of the lamp current by changing module increases the display brightness of display, makes the beholder can obtain better visual experience.

Description of drawings

Fig. 1 is a workflow diagram of the present invention.

Fig. 2 is a structured flowchart of the present invention.

Lamp current was the maximal value waveform when Fig. 3 a was BRT=100.

Lamp current was the minimum value waveform when Fig. 3 b was BRT=0.

Fig. 4 a is that the output voltage of BRT=100 transformer and electric current are because the dutycycle waveform.

Fig. 4 b is that the output voltage of BRT=80 transformer and electric current are because the dutycycle waveform.

Fig. 4 c is that the output voltage of BRT=50 transformer and electric current are because the dutycycle waveform.

Fig. 4 d is that the output voltage of BRT=0 transformer and electric current are because the dutycycle waveform.

Embodiment

Below in conjunction with accompanying drawing the present invention is done further explanation:

As shown in Figure 1, maximum characteristics of the present invention are exactly the amplitude that does not change electric current, but change the dutycycle of electric current, regulate the brightness of display.This dimming mode may further comprise the steps: in the 1st step, according to user's brightness settings, change register E on the mainboard ²The storing value of ROM; In the 2nd step, the microcontroller on the mainboard is adjusted the output of Dimming signal dutyfactor; In the 3rd step, according to the Dimming signal, the output drive signal of the control chip in the inverter module changes; The 4th step, the dutycycle of transformer output voltage and output current in the control chip adjustment inverter module; The 5th step, the change of the brightness of Module.

Wherein the Dimming signal in the 2nd step and the 3rd step is the one group of square-wave signal that can regulate.

As shown in Figure 2, mainboard is input to inverter module with signal, and inverter module is transferred to the demonstration module again after with signal Processing.Comprise MCU microcontroller and register E on the mainboard ²Two parts of ROM; Inverter module comprises control chip and two parts of transformer.

The dimming signal of microcontroller (MCU) output is one group of square-wave signal that dutycycle can be regulated.The user regulates display brightness by menu, has changed to be stored in E ²The value of the register of ROM the inside, the dimming signal dutyfactor of the MCU output on the mainboard changes, and the dimming signal offers inverter on the power panel by mainboard, and the control chip in the inverter module is according to the output of dimming signal controlling transformer; During BRT=100, the duty=100% of dimming signal, lamp current are maximal value=7.05mA shown in Fig. 3 a and Fig. 3 b; During BRT=0, dimming signal duty=40%, lamp current are minimum value=3.74mA.

Shown in Fig. 4 a, Fig. 4 b, Fig. 4 c and Fig. 4 d, Brightness is transferred at 0 o'clock from 100, and the output voltage of transformer and electric current are because the change of dutycycle, and effective value changes, and output current is from 7.05mA～3.7mA, thereby regulates the brightness of module.The special feature of this mode is that by the combination of software and hardware, the dutycycle of regulating lamp current (voltage) realizes the variation of brightness, uses the PWM mode, and luminance ratio can reach 4: 1.

Claims

1. LCD display PWM dimming mode is characterized in that this dimming mode may further comprise the steps:

(5) change of the brightness of Module.

2. a kind of LCD display PWM dimming mode as claimed in claim 1 is characterized in that, the Dimming signal in step (2) and the step (3) is a prescription ripple signal.