Patent ID: 7572013

Claim:
A projection display comprising: a light source; a color separation optical system that decomposes white light from the light source into three color lights including red light, green light and blue light; three polarization beam splitters including a polarization beam splitter for the red light, a polarization beam splitter for the green light and a polarization beam splitter for the blue light; three reflective liquid crystal display elements corresponding to the three polarization beam splitters, wherein each of the three reflective liquid crystal display elements modulates polarization of incident light from one of the three polarization beam splitters and reflects modulated light to the one of the three polarization beam splitters; a color combining prism including a dichroic film, wherein the color combining prism combines lights modulated by the three reflective liquid crystal display elements, the lights entering the color combining prism in different directions from one another, so as to output combined light; a projection optical system that projects the combined light from the color combining prism; a polarization converter device disposed between an exit face of the color combining prism and an entrance face of the projection optical system, the polarization converter converting state of polarization of light, which passes through the polarization converter, mutually between linear polarization and circular polarization; and at least one wavelength selective wave plate disposed between an exit face of one of the three polarization beam splitters and an entrance face of the color combining prism, the wavelength selective wave plate showing a characteristic of a λ/2 wave plate to rotate polarization of transmitted light according to only two wavelengths corresponding to wavelengths of red light, green light and blue light passing through the wavelength selective wave plate by 90 degrees without rotating the polarization of another one of the wavelengths corresponding to transmitted red light, green light and blue light.