What is the aperture ratio of the LCD?

One of the more important specifications in LCD is brightness. The most important factor in determining brightness is the aperture ratio. What is the aperture ratio?

 The

     In simple terms, that is the proportion of the effective area through which light can pass. On the left side of the figure below is a block diagram of a liquid crystal display viewed from directly above or below. When light is emitted through its backlight, not all light can pass through the panel. For example, the signal traces used to drive the LCD source driver chip and the gate driver chip and the TFT itself, as well as some storage capacitors used for storage voltage, etc., in addition to incomplete light transmission, these places are generally The light passing through these places will not be controlled by the voltage and cannot display the correct gray scale. Therefore, it is necessary to use a matrix block to shield the light so as not to interfere with the correct brightness of some other light-transmitting areas. Therefore, it is effective. The light-transmitting area is left only in the area shown on the right side of the figure. The ratio of the effective light-transmitting area and the entire area is called the aperture ratio.

 The

     When light is emitted from the backlight, it passes through polarizers, glass, liquid crystals, color filters, and so on. We assume the penetration of each part as shown below.

 The

     Polarizing plate penetration: 50% (because it is only allowed to pass through polarized light waves in one direction):

 The

     Glass penetration rate: 95% (this needs to calculate the upper and lower two pieces of glass);

     Liquid crystal transmittance: 95%; aperture ratio: 50% (effective light transmission area is actually only half);

     Color filter transmittance: 27% (We assume that the material's own transmittance is 80%, but because the filter itself is coated with color, it can only tolerate the passage of light waves of this color in RGB. For the three primary colors, only one of these three types can be allowed to pass, leaving only 1/3 of the brightness, so a total of only 80% x 33% = 27% can be passed.

 The

     If you use the above penetration rate to calculate, then only 6% of the light from the backlight will be left, which is really very poor, which is why in the design of TFT LCD screen to try to The important reason for increasing the aperture ratio is that as long as the aperture ratio is increased, the brightness can be increased. At the same time, the brightness on the backlight board is not so high, and power consumption and cost can be saved.