Cholesteric liquid crystal display

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Cholesteric liquid crystal displays ( English cholesteric liquid crystal display , briefly ChLCD ) are a based on cholesteric liquid crystals built up ads . This type of liquid crystal display was developed by Kent Displays .

The pixels of a display have a bistable state that they can maintain without an applied supply voltage . This means that the displayed image content is retained without consuming any further energy ( zero power ). The disadvantages of this technology are the slow refresh rate and the limited temperature range.

Bistable displays are used, for example, as price tags in supermarkets or in public transport to display timetables.

functionality

The cholesteric liquid crystals can be converted into three states by applying an electrical voltage.

In the homeotropic texture , light is transmitted almost unhindered.

The focal-conical texture is an unstable intermediate step. If the voltage is removed in this phase, the display falls back into the homeotropic phase.

In the planar texture , part of the visible light is reflected by the Bragg reflection.

Usually, an absorption surface is attached behind the display and implemented, for example, with a black coating. Depending on the control, incident light is either absorbed or reflected.

See also

Individual evidence

  1. ChLCD based display system from BMG MIS .
  2. Peter M. Knoll: Displays - Introduction to the technology of active and passive displays. 1986, ISBN 3-7785-1357-5 .