Abstract: An illumination optical system that illuminates a plurality of image display elements comprises; a color separating optical system that separates light emitted from a light source into a plurality of color light components; and a plurality of light-guiding optical systems, each of which guides light component to a corresponding one of the plurality of image display elements. An illumination area on the image display element that is illuminated by at least one of the plurality of light-guiding optical systems is larger than those on the image display elements illuminated by the other ones of the plurality of light-guiding optical systems. This provides a compact projection type image display apparatus which can project bright images.

Abstract: A method of manufacturing different types of image display apparatuses includes the steps of producing a lens barrel (housing) for holding optical elements, the lens barrel being commonly usable in the different types of image display apparatuses; selecting one type of image display apparatus to be manufactured among the different types of image display apparatuses; and manufacturing the one type of image display apparatus using the common lens barrel. In the image display apparatus manufactured by the method mentioned above, selective use of retainers for retaining the optical elements included in the illumination system, when arranging at least two different types of the illumination systems varying according to whether or not microlenses are provided, enables the different types of illumination systems to be easily constituted in accordance with the characteristics of image display elements varying according to whether or not microlenses are provided, and so on.

Abstract: A projection apparatus having a light source, a color separating system for separating the light from the light source into a plurality of color beams, a plurality of light modulating elements for modulating the separated color beams, based on an image signal, a color combining system for combining the modulated color beams, and a projection optical system for projecting composite light of the combined color beams, onto a screen. The color combining system incorporates a cross dichroic prism with dichroic films on joint surfaces between four prisms, each of the color beams incident to the cross dichroic prism is converted into linearly polarized light, and the following relation is met: 0°<&thgr;<90° where &thgr; is an angle between a polarization direction of a color beam component transmitted by all the dichroic films and a polarization direction of a color beam component reflected by the dichroic film.

Abstract: An image display apparatus includes a light source for supplying illumination light, a reflective display element for reflecting and modulating the illumination light into image light, a first optical system for guiding the illumination light to the reflective display element, and a second optical system for guiding the image light to an observer. Particularly, the first optical system has an optical element including a first surface on which the illumination light is incident, a second surface for totally reflecting the light incident on the first surface, and a third surface from which the light totally reflected by the second surface emerges toward the reflective display element. The first optical system is arranged so that the image light is again incident through the third surface on the optical element and emerges from the second surface toward the second optical system.

Abstract: An image display apparatus includes: a color separation optical system having a color separation optical member for reflecting a color light component in a specific wavelength range of the converging light and transmitting color light components in the other wavelength ranges. An optical axis of light incident on the color separation optical member forms an angle smaller than 45 degrees with a normal to a light incident surface of the color separation optical member.

Abstract: For increasing the illumination efficiency to a liquid-crystal display element, an illuminating apparatus has a reflector for reflecting light from a light source, a negative meniscus lens, which is convex on the light source side, a first lens array unit of lens elements, a second lens array unit of lens elements, which is conjugate with the light source, and an optical polarization converting element in the stated order along a traveling direction of the light from the light source. The illuminating apparatus illuminates the liquid-crystal display element through the optical polarization converting element.

Abstract: A projection lens arranged to project an image formed on a display panel onto a screen includes a plurality of lens units movable along an axis for varying magnification, wherein at least one of lenses constituting the plurality of lens units has at least one lens surface of shape having no symmetry with respect to the axis, so that the trapezoidal deformation which tends to occur when the image formed on the display panel is projected onto the screen is corrected well.

Abstract: An illumination apparatus is constructed to illuminate an effective range of a surface, rectangular in shape, to be illuminated with light from a light source via a first lens array, a second lens array, and a condensing optical system. Wherein the illumination apparatus satisfies conditions defined by the length along a longitudinal direction of the area to be illuminated, a length along a transverse direction thereof, a focal length of individual lenses forming the second lens array, a focal length of the optical system, a width of transverse aberration caused by the optical system in the longitudinal direction against an object at infinity, a width of transverse aberration caused by the optical system in the transverse direction, a length along a longitudinal direction of individual lenses of the first array, and a length along a transverse direction of the lenses of the first lens array.

Abstract: A projection lens arranged to project an image formed on a display panel onto a screen includes a plurality of lens units movable along an axis for varying magnification, wherein at least one of lenses constituting the plurality of lens units has at least one lens surface of shape having no symmetry with respect to the axis, so that the trapezoidal deformation which tends to occur when the image formed on the display panel is projected onto the screen is corrected well.

Abstract: A magnetic disk apparatus includes a requesting unit for requesting the magnetic disk apparatus to re-set a value of specification information capable of determining performance of the magnetic disk apparatus in combination with either identification result or flag information; a performance unit for causing the magnetic disk apparatus which receives the request to re-set the own specification; a detecting unit for detecting an internal condition of the disk apparatus; a processing unit for processing the detection result; a conversion unit for converting the internal condition of the magnetic disk apparatus into states of a numeral value, a figure, a color, and a sound in combination with the process result, and for notifying the converted condition to a user; and a battery.

Abstract: This specification discloses an illuminating device in which lights emitted from a plurality of light sources are made into substantially parallel lights and are made to enter a lens array system, and illumination is effected by the lights from the lens array system, characterized in that an optical system in which the action of compressing the incident light in the direction of arrangement of the plurality of light sources is greater than the action of compressing the incident light in a direction perpendicular thereto is provided between the light sources and the lens array system. The specification also discloses a projection type display apparatus including such illuminating device.

Abstract: An illuminating apparatus includes a condensing optical system for converting light from a light source into convergent light, a first convex lens array for receiving the convergent light, and a collimating optical system for making a plurality of light beams from the first convex lens array parallel to one another. In addition, a polarization converting element array individually converts the plurality of light beams from the collimating optical system into polarized lights.

Abstract: In the image observation apparatus of the invention, image light is guided to an observer's eye by using a first refractive surface on which the image light from an image display device made incident, a reflective surface for reflecting the image light made incident from the first refractive surface, and an optical element having a second refractive surface for emitting the image light reflected from the reflective surface. A diffraction optical part integrated with the optical element is provided at or in the vicinity of the reflective surface of the optical element Thereby, an image observation apparatus in which chromatic aberrations in images can be satisfactorily corrected can be realized without complication and an increase in the size of the optical system.

Abstract: For detecting commutation timing of an inverter when operating a DC brushless motor under a starting thereof or a light load condition, with certainty, a micro-computer generates driving signals so as to drive switching elements of the inverter by PWM signals of those driving signals, in a predetermined order by every turn-on interval, thereby supplying driving current to the DC brushless motor, wherein a timing for exchange between the turn-on intervals (i.e., the commutation timing) is detected by detection of level of magnetic pole position detecting signals upon a basis of the PWM signals.

Abstract: A color combining optical system according to this invention aims at reducing the size of an optical system and suppressing the occurrence of color unevenness. According to this invention, there is provided a color combining optical system for combining color light reflected by a dichroic film and color light transmitted through the dichroic film. The optical thickness of the dichroic film increases or decreases from one end side to the other end side in the inclining direction of the dichroic film with respect to the incident optical axis of the color light reflected by the dichroic film.

Abstract: Conventionally, concentrated illumination of a central portion of an image (about 40-60% of the whole image) in which information such as letters and a picture tends to concentrate (centrally concentrated illumination) and uniform illumination of the whole image (uniform illumination) can be carried out by using two separate apparatuses, but no single conventional image display apparatus can carry out both of the two types of illumination. Accordingly, an object of the present invention is to provide a liquid crystal display apparatus which can carry out centrally concentrated illumination, uniform illumination, and various other illumination states (illumination distributions). According to the present invention, an image display apparatus (such as a liquid crystal projector) is structured such that a fly-eye lens or a part thereof in an illumination optical system for illuminating an image forming element is moved to vary the illumination distribution on the image forming element.

Abstract: An optical low-pass filter comprises a phase advancing area which advances a phase of a wavefront of an incident pencil of rays with respect to a phase of a wavefront of a center of the incident pencil of rays, and a phase retarding area which retards the phase of the wavefront of the incident pencil of rays with respect to the phase of the wavefront of the center of the incident pencil of rays, the phase advancing area and the phase retarding area alternately existing in the optical low-pass filter, and an optical apparatus comprises an image forming optical system, an image pickup element, and such an optical low-pass filter.

Abstract: An image display apparatus includes a light source for supplying illumination light, a reflection type display device which reflects the illumination light and modulates the illumination light into image light, an illumination optical system for guiding the illumination light to the reflection type display device, and a projection optical system for guiding the image light to an observer.

Abstract: An image display apparatus includes a light source for supplying illumination light, a reflection type display element for modulating the illumination light into image light by reflecting the light, an illumination optical system for guiding the illumination light to the reflection type display element, and a projection optical system for guiding the image light to an observer. The image light is incident on the projection optical system via at least a portion of said illumination optical system. The projection optical system includes a member for correcting an optical path length difference between rays of the image light caused when the image light is incident on the projection optical system via at least a portion of the illumination optical system.

Abstract: An image display apparatus includes a light source for supplying illumination light, a reflective display element for reflecting and modulating the illumination light into image light, a first optical system for guiding the illumination light to the reflective display element, and a second optical system for guiding the image light to an observer. Particularly, the first optical system has an optical element including a first surface on which the illumination light is incident, a second surface for totally reflecting the light incident on the first surface, and a third surface from which the light totally reflected by the second surface emerges toward the reflective display element, and the first optical system is arranged so that the image light is again incident through the third surface on the optical element and emerges from the second surface toward the second optical system.