# LCD的1/2，1/3bias是什么意思

• LCD Bias(LCD 偏置电压)数代表使用了多少个电压参考点来驱动LCD。偏置电压通常由电阻分压网产生。如最底下的图示出了1/5 Bias，使用Vdd=5V，电阻的数量由上表来决定。
电阻器的电阻值由要求的电压参考点和可能的波形失真决定。因为LCD是容性负载，电阻值应当降低以减少失真，或者用更大的显示屏，使用运放来缓冲电压参考点。

The control signals that drive an LCD are AC in nature. The basic configuration of how to generate a waveform to control an LCD are covered in the sections "LCD Multiplex Ratio (above)" and "LCD Static Drive Technology".  But to control LCDs with a larger multiplex ratio, we need to provide the waveform generator with multiple bias voltage level points. The resulting waveform sent to the LCD segment/dot control lines and backplane commons will contain a stair-stepped waveform that will maintain specific ac voltages across any given segment/dot to keep it in it's "on" or "off" state (or in a grayscale module, states between those two points). The LCD Bias number (example: 1/5 bias) will indicate how many voltage reference points are created to drive a specific LCD. The table below shows the relationship between the number of driving bias voltages and the display multiplex ratios typically used:

 Mux Ratio Static 1/2 1/3 1/4 1/7 1/8 1/11 1/12 1/14 1/16 1/24 1/32 1/64 Biases 2 31/2 Bias 41/3 Bias 51/4 Bias 61/5 Bias

The necessary bias voltages are usually generated by the use of a resistor dividing network, and example of which is shown below using Vdd at 5 volts, and the number of resistors in the ladder determined using the table above.The values of the resistors is determined by the required voltage reference points and possible waveform distortion. Because an LCD is a capacitive load, the values should be decreased to decrease distortion, or with larger displays, buffering the voltage reference points with op-amps.