Embodiments of the disclosure provide a projection display apparatus comprising: a light source for emitting a light beam; a first light path configured to project the light beam emitted from the light source to a first display position; a second light path configured to project the light beam emitted from the light source to a second display position; a light patch switching device configured to switch the light beam emitted from the light source between the first light path and the second light path; and a light modulation device through which both the first light path and the second light path pass, wherein the light modulation device is configured to modulate the light beam passing therethrough to generate a display image.

The invention relates to a wavelength conversion element including: a base material including a light-reflecting surface; a dichroic film; and a wavelength conversion layer provided between the light-reflecting surface and the dichroic film. The dichroic film reflects portion of light in a wavelength band that the wavelength conversion layer absorbs, and has a reflectance distribution, with respect to the light along a predetermined direction.

The invention relates to a wavelength conversion element including: a base material including a light-reflecting surface; a dichroic film; and a wavelength conversion layer provided between the light-reflecting surface and the dichroic film. The dichroic film reflects portion of light in a wavelength band that the wavelength conversion layer absorbs, and has a reflectance distribution, with respect to the light along a predetermined direction.

A projection-type display device includes: R, G, and B light sources that emit light beams with different colors; a projection unit that projects light beams based on image information among light beams emitted from the light sources onto a projection screen; a heat sink that radiates heat generated from the R light source, which has a maximum change in light emission intensity relative to a change in temperature, among the light sources; and a heat sink that radiates heat generated from the G and B light sources and that has a surface area smaller than that of the heat sink. In a use state, the R light source is disposed on a side apart from the other light sources in a direction opposite to a direction of gravitational force.

A front-end lighting system for projection includes: a RGB three-color LED light source, configured to generate three monochromatic lights; a reflector, configured to perform a first light mixing operation on three monochromatic lights generated by the RGB three-color LED light source; a first group of relay lenses, configured to adjust a light path; and a compound eye field lens, configured to perform a second light mixing operation on the three monochromatic lights generated by the RGB three-color LED light source. The reflector includes a reflecting surface, and three monochromatic lights emitted by the RGB three-color LED light sources, after being reflected by the reflecting surface of the reflector, pass through the first group of relay lenses and the compound eye field lens in sequence.

An apparatus and method for controlling the spectrum of stimulated Raman scattering that is used for despeckling of digitally projected images. The stimulated Raman scattering is utilized to add wavelength diversity for reduced speckle and to change the color of the light to a more desirable combination of wavelengths. Digital projection with color-sequential projectors may be enabled by alternately switching the Raman spectrum between green and red. Improved projector transmission may be achieved by minimizing the amount of yellow light generated in the Raman spectrum.

A front-end lighting system for projection includes: a RGB three-color LED light source, configured to generate three monochromatic lights; a reflector, configured to perform a first light mixing operation on three monochromatic lights generated by the RGB three-color LED light source; a first group of relay lenses, configured to adjust a light path; and a compound eye field lens, configured to perform a second light mixing operation on the three monochromatic lights generated by the RGB three-color LED light source. The reflector includes a reflecting surface, and three monochromatic lights emitted by the RGB three-color LED light sources, after being reflected by the reflecting surface of the reflector, pass through the first group of relay lenses and the compound eye field lens in sequence.