Bidirectional dichroic circular polarizer and reflection/transmission type liquid-crystal display device

A combination reflective/transmissive liquid-crystal display device comprising:

• a light source;
• a polarization separation layer comprising one of a function of transmitting one direction of left or right circularly polarized light components incident from said light source or from an opposite direction and reflecting a circularly polarized light component of the opposite direction and a function of transmitting one direction component of linearly polarized light incident from said light source or from an opposite direction and reflecting a component of the other direction which is perpendicular thereto;
• a half-wavelength layer, which, in response to on/off switching of a voltage either shifts incident polarized light from said polarization separation layer or from an opposite direction or does not shift said light;
• a first light-absorbing type bidirectional dichroic polarization layer disposed on the opposite of the half-wavelength layer from the polarization separating layer, and comprising one of a function of transmitting, of light incident thereto from said half-wavelength layer or from the opposite direction, circularly polarized light of one of the left and right rotation directions and absorbing circularly polarize light of the other rotation direction, and a function of transmitting, of light incident thereto from said half-wavelength layer or from the opposite direction, linearly polarized light of only one direction, and absorbing linear polarized light of the direction perpendicular thereto;
• a liquid-crystal layer that converts or does not convert one incident circularly polarized light or linearly polarized light to another circularly polarized light or linearly polarized light before it exits the opposite side, and comprises one of a function of changing the ellipticity when light exits with circular polarization and changing the polarization axis direction when light exits as linearly polarized light;
• a second light-absorbing type bidirectional dichroic polarization layer disposed on the opposite of the liquid-crystal layer from the first bidirectional dichroic polarization layer, and comprising one of a function of transmitting, of light incident thereto from said liquid-crystal layer or from the opposite direction, circularly polarized light of one of the left and right rotation directions and absorbing circularly polarize light of the other rotation direction, and a function of transmitting, of light incident thereto from said liquid-crystal cell or from the opposite direction, linearly polarized light of only one direction, and absorbing linear polarized light of the direction perpendicular thereto;
• wherein, by switching a voltage with respect to said half-wavelength layer on and off, it is possible to freely select between a reflective mode in which said display device operates in the reflective mode and a transmissive mode in which said display device operates in a transmissive mode, the configuration of the first bidirectional dichroic polarizing layer being such that said first bidirectional dichroic polarizing layer transmits polarized light having passed through said polarization separating layer,
• and wherein when said half-wavelength layer is in the transmissive mode, polarized light having passed through said polarization separating layer is transmitted without a shift of phase, or with a shift of phase so that it is transmitted through the first bidirectional dichroic polarizing layer, but when said half-wavelength layer is in the reflective mode, the phase of polarized light having passed through said second bidirectional dichroic polarizing layer, said liquid-crystal layer, and said first bidirectional dichroic polarizing layer is shifted so that it is reflected by said phase shifting layer, or not shifted and also polarized light reflected from said phase shifting layer is shifted so as to be transmitted by the first bidirectional dichroic polarizing layer, or not shifted.