Abstract: A light source device includes a plurality of light sources with different polarizations. A combined wavelength band of the light of a first polarization and second polarization is a first wavelength band. A combined wavelength band of a third polarization and fourth polarization is a second wavelength band. A plurality of selective transmission elements transmits one or more combined light of one or more polarizations and reflects one or more light of one or more polarizations. Thus, the light of the first polarization, the light of the second polarization and the light of the third polarization passing through a third selective transmission element, and the light of the fourth polarization reflected by the third selective transmission element proceed in the same direction.

Abstract: A light source device includes a first light source that emits light of a first polarization, and a second light source that emits light of a second polarization whose polarization direction is different from the light of the first polarization by 90 degrees. A combined wavelength band of the light of the first polarization and the light of the second polarization is a first wavelength band. A third light source emits light of a third polarization and of a wavelength band which is different from the first wavelength band, and a fourth light source emits light of a fourth polarization whose polarization direction is different from the light of the third polarization by 90 degrees. A combined wavelength band of the light of the third polarization and the light of the fourth polarization is a second wavelength band which is different from the first wavelength band. A reflecting element reflects the light of the first polarization.

Abstract: Not only abnormality of a light output to an exterior but also overturning, vibration, disassembly, deformation, or breakage of a display apparatus including a case and a screen are reliably and promptly detected. A projection display apparatus includes a light source (22) for generating illumination light, which is provided in a case (28) having a light-shielding function, a movable aperture (23) for adjusting the amount of illumination light from the light source (22), a light valve (9) for adjusting the amount of light based on an image signal to generate image light for forming an image from the illumination light, a projection optical system (10) for enlarging the image light from the light valve (9), and a transmission-type screen (29) for displaying the image, which is provided to a window of the case (28).

Abstract: A transparent screen and a projection display unit capable of reducing the speckle with maintaining the brightness of the image light. A wavefront-dividing phase-modulating component 21, which divides the wavefront of the image light emitted from a Fresnel lens screen 7 and modulates the phases of the wavefronts divided, is disposed before an optical diffusing component 10. Alternatively, a spatial frequency modulating component 22, which modulates the spatial frequency of the image light diffused by the optical diffusing component 10, is disposed on the light-output side (observer side) of the optical diffusing component 10.

Abstract: Not only abnormality of a light output to an exterior but also overturning, vibration, disassembly, deformation, or breakage of a display apparatus including a case and a screen are reliably and promptly detected. A projection display apparatus includes a light source (22) for generating illumination light, which is provided in a case (28) having a light-shielding function, a movable aperture (23) for adjusting the amount of illumination light from the light source (22), a light valve (9) for adjusting the amount of light based on an image signal to generate image light for forming an image from the illumination light, a projection optical system (10) for enlarging the image light from the light valve (9), and a transmission-type screen (29) for displaying the image, which is provided to a window of the case (28).

Abstract: A transparent screen and a projection display unit capable of reducing the speckle with maintaining the brightness of the image light. A wavefront-dividing phase-modulating component 21, which divides the wavefront of the image light emitted from a Fresnel lens screen 7 and modulates the phases of the wavefronts divided, is disposed before an optical diffusing component 10. Alternatively, a spatial frequency modulating component 22, which modulates the spatial frequency of the image light diffused by the optical diffusing component 10, is disposed on the light-output side (observer side) of the optical diffusing component 10.

Abstract: An illumination apparatus and a projection type display apparatus of lower cost are provided, in which extra-axial aberrations, especially distortion and lateral aberration, are favorably corrected, and the dimensional margin of illumination is suppressed to enhance the utilization factor of light. The illumination apparatus includes a first group of lenses which includes a meniscus lens having a positive refracting power, a second group of lenses which includes first lens means having a negative refracting power and second lens means having a positive refracting power, and lens means whose surface immediately before a surface to-be-illuminated is a plane surface, whereby an illuminating light beam is caused to exit in a telecentric state.

Abstract: An illumination apparatus and a projection type display apparatus of lower cost are provided, in which extra-axial aberrations, especially distortion and lateral aberration, are favorably corrected, and the dimensional margin of illumination is suppressed to enhance the utilization factor of light. The illumination apparatus includes a first group of lenses which includes a meniscus lens having a positive refracting power, a second group of lenses which includes first lens means having a negative refracting power and second lens means having a positive refracting power, and lens means whose surface immediately before a surface to-be-illuminated is a plane surface, whereby an illuminating light beam is caused to exit in a telecentric state.