The LCD TV backlight circuit (also called "inverter circuit") is usually a screen assembly formed by assembly of a specially produced backlight circuit assembly purchased by a screen manufacturer. This phenomenon leads to the lack of a working circuit diagram of the backlight circuit. It is difficult to support the circuit diagram for the faults that occur after the product is used, which makes it difficult to determine the fault.
A Changhong LTZ6810U LCD color TV, the screen turns on once and goes out, and the screen goes black. The black screen failure is not only related to the backlight drive circuit, but also to the motherboard. Judging from the phenomenon reflected in the maintenance, the screen belongs to the Changhong LS20A movement. If the fault is on the main board, usually the data saved in the user memory or the FLASH block program has changed, or the main board control system is faulty, the EaPROM memory needs to be replaced, and the main board Replace the AT24C64 with a model of M24C64-MN6T; sometimes the motherboard is replaced incorrectly or the circuit status of the motherboard has changed.
In order to conveniently and accurately adjust the ultra-low color temperature of the 8-bit LED-backlit LCD screen, the fill color RGB value is set through Adobe Photoshop software, and the color blocks are displayed on the LED-backlit LCD screen, combined with the self-made blue light absorption film of the mobile phone screen to achieve ultra-low color temperature adjustment. The changes of color coordinate Z value, color tolerance, dominant wavelength, color purity, peak wavelength, centroid wavelength, half-value width, color rendering index Ra with color temperature of 1931 CIE-XYZ standard chromaticity system of LED backlight LCD screen are studied through spectral analysis. , It realizes the 1000K ultra-low color temperature adjustment of the 8-bit LED backlight LCD screen; the average relative error of the 10 measured color temperatures of 6500~1000 K and the target color temperature is 0.349%.
The average absolute error of the liquid crystal display is 7.1K, which can guarantee the white balance. The results of spectrum analysis show that after adding the blue light absorption film of the self-made mobile phone screen, the center of mass wavelength will be reduced by an average of 15 nm at the same color temperature. When the color temperature is less than 4100 K, the same The half-peak width at the color temperature is reduced by about 4nm, and the other 6 parameters have little effect. The color temperature adjustment method and conclusion have reference value for the best optimization of the anti-blue film effect and the related research of LCD screen.
