Monochrome lcd display technology

What is the advantage about monochrome lcd display?  Why we still need monochrome lcd display even color tft lcd is more and more popular, And do you know how many technology types for monochrome lcd display? Let’s introduce in the following:

Advantage of monochrome lcd:

Monochrome lcd could be in the simple interface such as in I2C interface, SPI interface, 6800/8080 parallel interface, that is we could connect it to the cheaper MCU, and make our system in cost competitive.

On the other hand, monochrome lcd is the better in power saving, it is easily to make the transflective lcd display that most suitable for outdoor application or for battery power devices.

The monochrome lcd have the TN display lcd and STN LCD, and the new monochrome tft lcd mode.

What is TN lcd display:

TN lcd means twisted nematic LCD, the namatic liquid crystal elements inside the lcd glass cell,its twisted angle is 90 degree, intergrated the front and rear polarizes on the lcd, the polarized angle is also in 90 degree in cross, it control the light transmission and make the tn lcd display on and off.

TN lcd display is based on the precisely controlled realignment of liquid crystal molecules between different ordered molecular configurations under the action of an applied electric field. This is achieved with little power consumption and at low operating voltages.

What is STN LCD?

STN lcd is super-twisted nematic lcd display, it is a type of monochrome lcd display, it is also passive liquid crystal display (LCD). compare to TN lcd, STN LCD twist angle is 240 degree, instead of 90 degree of TN LCD, so we call it STN LCD. STN lcd have yellow-green display mode, gray,black-white mode, blue display mode, available. The yellow-green STN LCD means the lcd background with yellow-green mode, but its display characters is black. While the blue mode STN lcd, its background is blue mode with white display pixels. Black-white lcd means the white background with black display pixels (positive mode) or black background with white display colors.

Monochrome tft lcd display:

The monochrome tft lcd is the monochrome type of tft lcd screen, compare to color tft lcd, it is without RGB color filter inside the tft lcd cell, so it display in monochrome type. But because tft lcd is active lcd display type, it is without cross-talk problem as TN or STN lcd, monochrome tft lcd could achieve higher display contrast that traditional monochrome TN or STN lcd display.