Color/black-and-white switchable portable terminal and display unit

A system comprising:

• at least one of:
• a casing, an antenna, a speaker, an input key, a microphone, a camera, a battery, an infrared interface, and operating system (OS) software;
• and,
• a display device including:
• colored-light emitting means for emitting colored light to effect a colored light-emitting display;
• reflection means for reflecting external light to effect a monochromatic reflection display;
• light polarizing state modulating means for modulating a polarizing state of the colored light;
• a colored signal processing section for processing a received image signal to effect driving of image display on the colored light-emitting display, and a monochromatic signal processing section for processing the received image signal to effect driving of image display on the monochromatic reflection display;
• and
• switching means for selecting lighting according to one of the colored light emitting means for a color display mode and the reflection means for a monochromatic display mode, and for selecting processing and driving according to one of the colored signal processing section for the color display mode and the monochromatic signal processing section for the monochromatic display mode, on a basis of the received image signal;
• wherein the colored light emitting means comprises an organic LED layer, the reflection means comprises an anode of the organic LED layer, and the light polarizing state modulating means comprises a polarizing plate, a phase difference plate and a liquid crystal layer.