A quarter-wave film having a wide bandwidth is invented. A preferred device configuration
includes a chromatic half-wave film adjacent to a twisted nematic liquid crystal
(TN-LC) film. When a linear polarizer is attached to the side of chromatic half-wave
film and the angles of all the optical components are properly set, the combination
of chromatic half-wave film and TN-LC film behaves as a broadband quarter-wave
film. Based on this idea, a broadband circular polarizer is invented if the linear
polarizer, the chromatic half-wave film and the TN-LC film are combined together.
In addition, this idea can also be applied to reflective liquid crystal display
devices, which include a linear polarizer, a chromatic half-wave film, a TN-LC
cell and a reflector.