Abstract: The present invention relates to a rear projection type image display device comprising projection lenses (2, 3) for projecting an image displayed on an image display element onto a transmission type screen (6) on a larger scale, an optical path turn-back mirror (7) for turning back halfway a light beam projected from the projection lenses, and a drive circuit for displaying an image on the image display element, that are fixedly housed within a housing (5). When a diagonal size of the transmission type screen (6), the depth of the housing (5), and the length from a lower end of the screen (6) to a lower end of the housing (5), are assumed to be SS (inch), D (inch), and L (inch), respectively, the following conditions are satisfied: SS>40, D?SS/3.0, L?SS/10.

Abstract: A projection type display apparatus includes a housing having a first side on which an air intake opening is arranged and a second side on which an air exhaust opening is arranged, a light source for supplying light, and a light valve device which modulates the light output from the light source. A first fan is provided which draws air from the air intake opening into the housing, and a first ventilation path is coupled with the air intake opening so as to lead air flow from the air intake opening toward a lower portion of the light valve. A second ventilation path is formed from the lower portion of the light valve to an upper portion of the light valve, and a second fan is provided which draws out air flowing from the second ventilation path through the air exhaust opening to outside of the housing.

Abstract: An inexpensive projection lens unit in a rear projection type image display system, having a short focal distance (wide angle of viewing field), high focus and high contrast, and as well, including a power lens made of a glass material having a high refractive index in a range from 1.63 to 1.70 and an Abbe's number of not less than 50 with an optimized incident and emergent configuration in order to satisfactorily correct aberration with a enhanced focusing performance even with a shortened focal distance. Further, the power lens having a high refractive index can exhibit a high power, and accordingly, can carry out satisfactory aberration correction by optimizing the aspheric degree of a plastic lens even though the length of back focus is increased for enhancing the contrast.

Abstract: A projection optical unit for enlarged projection of an image displayed by an image display element includes a first projection optical unit having positive refractive power, and a second projection optical unit having positive refractive power for further enlarging the first enlarged image obtained by the first projection optical unit. The first projection optical unit is in an almost telecentric relationship with respect to the image display element side and the first enlarged image side, and the first enlarged image is formed at the image display element side, rather than at the second projection optical unit.

Abstract: In a projection type image display apparatus, a projector optical unit for projecting an image onto a screen while magnifying a size of the image to be projected with respect to an original size of the image displayed by an image forming element, has a group of lenses for magnifying the size of the image with respect to the original size thereof, and an optical path extending from the image forming element to the screen to transmit the image along the optical path.

Abstract: A projection type display apparatus includes a housing having a first side having an air intake opening and a second side having an air exhaust opening, a light source for supplying light, and a light valve device which modulates the light output from the light source. A centrifugal fan is associated with the air intake opening so as to draw air from the air intake opening. A first ventilation path is coupled with the air intake opening so as to lead air flow from the air intake opening toward a lower portion of the light valve, and a second ventilation path is formed from the lower portion of the light valve to an upper portion of the light valve. An exhaust fan is associated with the air exhaust opening so as to draw out air flowing from the second ventilation path through the air exhaust opening.

Abstract: An inexpensive projection lens unit in a rear projection type image display system, having a short focal distance (wide angle of viewing field), high focus and high contrast, and as well, including a power lens made of a glass material having a high refractive index in a range from 1.63 to 1.70 and an Abbe's number of not less than 50 with an optimized incident and emergent configuration in order to satisfactorily correct aberration with a enhanced focusing performance even with a shortened focal distance. Further, the power lens having a high refractive index can exhibit a high power, and accordingly, can carry out satisfactory aberration correction by optimizing the aspheric degree of a plastic lens even though the length of back focus is increased for enhancing the contrast.

Abstract: A projection type video display apparatus having improved color separating ability is provided. The projection type video display apparatus includes a color separating unit including an entrance plate provided with an aperture through which light beams emitted by a light source travel, an optical integrator, and a plurality of dichroic mirrors disposed with their color separating surfaces extended substantially parallel to the exit surface of the optical integrator and capable of transmitting color light beams of wavelengths in a predetermined wavelength range and of reflecting color light beams of wavelengths outside the predetermined wavelength range.

Abstract: A projection optical unit has two lens groups. A first projection optical unit disposed closest to an image display element, temporarily forms a first enlarged image (magnification: M1) at the image display element side, rather than at a second projection optical unit. The first enlarged image is subsequently projected in an enlarged form (magnification: M2, wherein M2>M1) onto a screen via the second projection optical unit. A field lens group having positive refractive power is disposed between the first projection optical unit and the second projection optical unit. Consequently, the relationship between F2, which is the F-value of the second projection optical unit, and F1, which is the F-value of the first projection optical unit, becomes F2=F1/M1, whereby it is possible to realize very-wide-angle imaging at a field angle exceeding 90 degrees.

Abstract: A projection type image display apparatus having an image display element outputting an image ray, a projection lens apparatus for performing overhead projection of the image ray from the image display element, the projection lens apparatus having a plurality of lens elements, a reflection mirror reflecting the image ray from the projection lens apparatus, and a screen on which the image ray reflected by the reflection mirror is projected.

Abstract: A projection type display apparatus includes a housing having a first side having an air intake opening and a second side having an air exhaust opening, a light source for supplying light, and a light valve device which modulates the light output from the light source. A centrifugal fan is associated with the air intake opening so as to draw air from the air intake opening. A first ventilation path is coupled with the air intake opening so as to lead air flow from the air intake opening toward a lower portion of the light valve, and a second ventilation path is formed from the lower portion of the light valve to an upper portion of the light valve. An exhaust fan is associated with the air exhaust opening so as to draw out air flowing from the second ventilation path through the air exhaust opening.

Abstract: An optical projection apparatus includes an optical lighting system provided with a polarized beam splitter for polarizing white light flux from a white light source and combining the white light flux with other light fluxes, thereby taking out a predetermined polarized wave; a multi-lens array consisting of a plurality of lens elements; and an irradiator for separating the white light flux into three primary color light fluxes of red, green, and blue and irradiating each of the three color light fluxes on the same display element at an angle different from the others; and a projecting lens unit used for projecting the three primary color light fluxes modulated by the display element. Color light fluxes modulated by the display element are separated in a horizontal direction of the screen of the display element when passing an injection pupil of the projection lens unit.

Abstract: A projection type display apparatus including a discharge lamp for supplying light, a light valve device and first and second air intake openings arranged on different sides of the apparatus. A centrifugal fan is associated with the first air intake opening so as to draw in outside air and form a first ventilation air flow from the first air intake opening through a lower side of the light valve device so as to cool the light valve device. A fan is associated with the second air intake opening so as to draw in outside air and form a second ventilation air flow so as to cool optical elements including lenses. An exhaust opening is arranged on a further side of the apparatus, and an exhaust is fan arranged proximate to a discharge lamp so as to draw out air including the first and second ventilation air flow therethrough.

Abstract: A projection type image display apparatus having an image display element outputting an image ray, a projection lens apparatus for performing overhead projection of the image ray from the image display element, the projection lens apparatus having a plurality of lens elements, a reflection mirror reflecting the image ray from the projection lens apparatus, and a screen on which the image ray reflected by the reflection mirror is projected.

Abstract: A projection type image display apparatus having an image display element outputting an image ray, a projection lens apparatus for performing overhead projection of the image ray from the image display element, the projection lens apparatus having a plurality of lens elements, a reflection mirror reflecting the image ray from the projection lens apparatus, and a screen on which the image ray reflected by the reflection mirror is projected. An optical axis of the projection lens apparatus is decentered from a center of the screen.

Abstract: For a projection lens apparatus having a six-group structure that enlarges and projects an image displayed on a projection tube, an appropriate distance is maintained between a power lens and an aspherical lens group that is located near a power lens on the image generation source side, and physical interference with the power lens is eliminated, so that productivity is increased while a cost reduction is achieved. A meniscus lens that has a concave face directed toward a screen and has a refracting power is employed as an aberration correction lens (fourth group lens 4) that is located near the power lens (third group lens 3) on the image generation source side. Further, the lens surface of the meniscus lens on the screen side has an aspherical shape, so that a curvature is increased from the light axis to a predetermined point located between the light axis and the outer edge, and is reduced from the predetermined point to the outer edge.

Abstract: An optical projection apparatus includes an optical lighting system provided with a polarized beam splitter for polarizing a white light flux received from a white light source and combining the white light flux with other light fluxes, thereby taking out a predetermined polarized wave; a multi-lens array consisting of a plurality of lens elements; and an irradiator for separating the white light flux into three primary color light fluxes of red, green, and blue and irradiating each of the three color light fluxes on the same display element at an angle different from the others; and a projector for projecting the three primary color light fluxes modulated by the display element. The optical lighting system and the projector are disposed between the white light source and the display element.

Abstract: A compact rear projection image display apparatus in which the projection distance in a projection optical system is substantially reduced and no reflection mirror is used, thereby eliminating a major cause of image trapezoidal distortion. The rear projection image display apparatus has a projection lens system which includes a first lens group with positive refractive power and a second lens group which further enlarges an image enlarged by the first lens group. The projection lens system enlarges and projects an image displayed on an image display device, on a transmission screen. No reflection mirror is provided between the second lens group and the transmission screen and the image enlarged by the second lens group is directly projected on the transmission screen.

Abstract: A projection type display apparatus including a discharge lamp for supplying light, a light valve device and first and second air intake openings arranged on different sides of the apparatus. A centrifugal fan is associated with the first air intake opening so as to draw in outside air and form a first ventilation air flow from the first air intake opening through a lower side of the light valve device so as to cool the light valve device. A cooling fan is associated with the second air intake opening so as to draw in outside air and form a second ventilation air flow so as to cool optical elements including lenses. An exhaust opening is arranged on a further side of the apparatus, and an exhaust is fan arranged proximate to a discharge lamp so as to draw out air including the first and second ventilation air flow therethrough.

Abstract: A projection optical unit has two lens groups. A first projection optical unit disposed closest to an image display element, temporarily forms a first enlarged image (magnification: M1) at the image display element side, rather than at a second projection optical unit. The first enlarged image is subsequently projected in an enlarged form (magnification: M2, wherein M2>M1) onto a screen via the second projection optical unit. A field lens group having positive refractive power is disposed between the first projection optical unit and the second projection optical unit. Consequently, the relationship between F2, which is the F-value of the second projection optical unit, and F1, which is the F-value of the first projection optical unit, becomes F2=F1/M1, whereby it is possible to realize very-wide-angle imaging at a field angle exceeding 90 degrees.