A projection lens includes: first to fifth lenses; a light shielding ring; an aperture stop; and a lens barrel. The light shielding ring is rotated in a circumferential direction of the lens barrel by a rotation mechanism. In a case where an image forming panel is shifted with respect to an optical axis of the projection lens, a part, through which the light passes, is biased in the projection lens, whereby temperature distribution occurs in the lens barrel in the direction perpendicular to the optical axis. The thermal deformation of the high temperature side of the lens barrel due to the temperature distribution is greater than that on the low temperature side. The respective lenses may be tilted due to thermal deformation. By rotating the light shielding ring through the rotation mechanism, the temperature increases uniformly in the circumferential direction of the light shielding ring.

An image projection apparatus includes a light source to emit light, an image generation unit including an image generation element to generate an image using the light emitted from the light source, an optical unit to guide the light emitted from the light source to the image generation unit, and to enlarge and project the image generated by the image generation unit, a drive unit to change any one of a position of the image generation element and a position of at least a part of the optical unit at specific timing, and a cooling device to cool one or more parts disposed in the image projection apparatus. An operation sound generated by the cooling device while the cooling device is being operated has a given frequency characteristic settable according to a drive frequency of the drive unit.

A sealing unit has a case including an opening portion having an attachment surface, a seal member including an annular flat plate portion and an annular rib portion provided to rise from one flat plate surface of the annular flat plate portion and made of an elastic material, an attachment member including an annular attachment surface, a fixing member, and a fastening member, and an outer circumferential surface of the annular rib portion is brought into abutment with the attachment surface of the opening portion, an inner circumferential surface of the annular rib portion is brought into abutment with the attachment surface of the attachment member, the fixing member comes into abutment with the other flat plate surface of the seal member and is fixed to the attachment member, and the fastening member comes into abutment with the other flat surface and is fixed to the case.

A dust collector includes a casing, a fan, a filtering element, an electric field generator and an electrostatic precipitator. The casing includes an inlet, an outlet and a channel. The channel is arranged between the inlet and the outlet. An ambient airflow is introduced into the channel through the inlet by the fan. Moreover, portions of suspended particles in the airflow are filtered off by the filtering element. The electric field generator generates an electric field. The suspended particles passing through the electric field generator have a first electrical polarity. The electrostatic precipitator has a second electrical polarity, wherein the first electrical polarity and the second electrical polarity are opposite. The suspended particles with the first electrical polarity are adsorbed by the electrostatic precipitator.

An artifact mitigation system includes a projector assembly and a set of imaging optics optically coupled to the projector assembly. The artifact mitigation system also includes an eyepiece optically coupled to the set of imaging optics. The eyepiece includes a diffractive incoupling interface. The artifact mitigation system further includes an artifact prevention element disposed between the set of imaging optics and the eyepiece. The artifact prevention element includes a linear polarizer, a first quarter waveplate disposed adjacent the linear polarizer, and a color select component disposed adjacent the first quarter waveplate.

A projector includes an exterior housing including an exhaust port and a cooling device provided in the exterior housing and configured to discharge the air, which has cooled a cooling target, to the outside of the exterior housing via the exhaust port. The exterior housing includes a partition member that partitions the exhaust port and forms a plurality of openings. The partition member includes projecting sections projecting from an end edge of at least one of the plurality of openings into the opening.

A wavelength conversion module, including a substrate, a wavelength conversion member, and a fixing ring, is provided. The substrate has an annular groove. The wavelength conversion member is disposed in the annular groove of the substrate. The fixing ring is disposed on the substrate and is configured to press on an inner region and an outer region of the annular groove and a portion of the wavelength conversion member to expose another portion of the wavelength conversion member and fix the wavelength conversion member on the substrate. In addition, a projection device, applying the wavelength conversion module, is also provided. The wavelength conversion module of the present invention and the projection device applying the wavelength conversion module have better structural reliability and assembly flexibility.

In an optical module and a scanning-type image display device, a reduction in heat insulating effect due to a natural convection generated between the optical module and a case is suppressed to alleviate laser overheating and thermal expansion or contraction of each component and obtain a stable projection image quality. In an optical module that couples laser beams from a plurality of laser beam sources 1a, 1b, 1c and irradiates the laser beams to a desired position, a cover that covers the optical module is provided, a second cover is provided in a space between the optical module and the cover, and a projecting part is provided on a surface of the second cover facing the optical module.

A substrate for an electro-optical device includes a first mounting terminal and a second mounting terminal connected to a sensor element. The substrate for an electro-optical device includes a first resistive element including a first end electrically connected to the first mounting terminal and a second end electrically connected to the second mounting terminal, a second resistive element including a first end electrically connected to the first resistive element and a second end electrically connected to the second mounting terminal, and a third mounting terminal electrically connected to the second end of the first resistive element and the first end of the second resistive element.

The object is to provide a technique that allows a semiconductor laser to be efficiently cooled. A semiconductor laser light source device includes: a semiconductor laser; a cooler that cools the semiconductor laser; and a driving substrate that drives the semiconductor laser. The cooler is placed in contact with a surface of the semiconductor laser that is opposite to a light emitting surface of the semiconductor laser. Furthermore, the driving substrate is placed in contact with a surface of the cooler that is opposite to a surface of the cooler on which the semiconductor laser is placed.