Abstract: A video projection device has one of a plurality of types of projection lenses replaceably loaded and projects a video on a screen at a fixed position. The video projection device includes: a converter lens which is composed of a plurality of lenses, which is afocal as a whole, and which is detachably provided in front of the projection lens to convert projection magnification; and a gap adjustment mechanism changing a predetermined gap in the converter lens to a setting in accordance with at least one of a projection distance to the screen and the type of the projection lens loaded.

Abstract: The invention provides an optical system for image projection, wherein when used in an image projection apparatus, a screen-continuing portion (e.g., screen-underlying portion) of the apparatus can be reduced to a small size, or can be removed, and thereby the apparatus can be so compacted, and provides an image projection apparatus mounting such optical system. An optical system 10 for image projection including a lighting optical system 1 leading light from a light source 11 for lighting a display element 4 (or 4?), and a projecting optical system 3 for projecting projection light containing image information from the display element 4 (or 4?). The lighting optical system 1 is arranged such that a straight optical axis ? from the light source 11 in the lighting optical system 1 is positioned in an area deviated from a luminous flux ? of the projection light incident into the projecting optical system 3 toward an area where the projection light ? from the projecting optical system 3 passes.

Abstract: A video projection device has one of a plurality of types of projection lenses replaceably loaded and projects a video on a screen at a fixed position. The video projection device includes: a converter lens which is composed of a plurality of lenses, which is afocal as a whole, and which is detachably provided in front of the projection lens to convert projection magnification; and a gap adjustment mechanism changing a predetermined gap in the converter lens to a setting in accordance with at least one of a projection distance to the screen and the type of the projection lens loaded.

Abstract: The invention provides an optical system for image projection, wherein when used in an image projection apparatus, a screen-continuing portion (e.g., screen-underlying portion) of the apparatus can be reduced to a small size, or can be removed, and thereby the apparatus can be so compacted, and provides an image projection apparatus mounting such optical system. An optical system 10 for image projection including a lighting optical system 1 leading light from a light source 11 for lighting a display element 4 (or 4?), and a projecting optical system 3 for projecting projection light containing image information from the display element 4 (or 4?). The lighting optical system 1 is arranged such that a straight optical axis ? from the light source 11 in the lighting optical system 1 is positioned in an area deviated from a luminous flux ? of the projection light incident into the projecting optical system 3 toward an area where the projection light ? from the projecting optical system 3 passes.

Abstract: A projection optical system includes from the enlargement side a first lens unit, a mirror which is an optical path bending member, a second lens unit, and a third lens unit. The projection optical system is designed so that a condition (1), 5.5<T12/FL<12.0, is fulfilled. Here, T12 is the air equivalent distance between the first lens unit and the second lens unit, and FL is the overall focal length of the projection optical system. By fulfilling the condition (1), it is unnecessary that the diameter of the first lens unit be extremely large. It is also unnecessary to change the lens shape to prevent interference between the first lens unit and the second lens units, so that an increase in the cost of the projection optical system can be suppressed.

Abstract: A projection optical system includes from the enlargement side a first lens unit, a mirror which is an optical path bending member, a second lens unit, and a third lens unit. The projection optical system is designed so that a condition (1), 5.5<T12/FL<12.0, is fulfilled. Here, T12 is the air equivalent distance between the first lens unit and the second lens unit, and FL is the overall focal length of the projection optical system. By fulfilling the condition (1), it is unnecessary that the diameter of the first lens unit be extremely large. It is also unnecessary to change the lens shape to prevent interference between the first lens unit and the second lens units, so that an increase in the cost of the projection optical system can be suppressed.

Abstract: An illuminating apparatus has a light source emitting illumination light; and a prism having a plurality of reflecting surfaces and reflecting the illumination light from said light source by the reflecting surfaces to thereby bend an illumination optical path at an obtuse angle.

Abstract: An optical system includes a first prism having a first surface and a second surface forming an acute angle therebetween, and a second prism having a third surface. The first prism and the second prism form an air gap between the second surface and the third surface. The air gap formed by the second surface and the third surface has a cross section perpendicular to the first surface and the second surface which is a wedge shape which is wide at a part thereof near the first surface and narrower at a part thereof more distant from the first surface.

Abstract: A projection system that is capable of providing a high-performance projection system and producing a high contrast projection image by using an optical modulation element, which can be positioned a predetermined distance away from an illumination optical system and a projection optical system. The optical modulation element is capable of modulating light received from the illumination optical system and projecting the modulated light to a projection optical system in the direction of a projection surface.

Abstract: An illumination optical system has a light source, an integrator for making the intensity distribution of the light from the light source even, and a relay optical system for imaging the light from the integrator on a plane conjugate with the exit surface of the integrator. The relay optical system includes a rear lens unit of which the refractive power is asymmetrical in one direction so that the plane on which the light is imaged is inclined relative to the optical axis of the relay optical system. This makes it possible to direct light to an inclined surface with an even intensity distribution and with minimum loss of the illumination light.

Abstract: A scanning optical system is used to re-form an original image on a CCD line sensor. The optical system has an object side lens unit, a mirror and an image side lens unit. The object side lens unit condenses light from the object. The mirror is arranged between the object side lens to deflect the light having passed through the object side lens unit for scanning. An exit pupil of the object side lens unit coincide with an entrance pupil of the image side lens unit.

Abstract: An illumination system has a light source for emitting illumination light, a color wheel, a first deflecting member, and a second deflecting member. The color wheel transmits or reflects the illumination light while rotating about a rotation axis in such a way that illumination light exiting from the color wheel has colors that are switched sequentially with time. The first deflecting member deflects the illumination light in such a way that the illumination light enters the color wheel. The second deflecting member deflects the illumination light having exited from the color wheel. The illumination light entering the first deflecting member and the illumination light exiting from the second deflecting member are both substantially perpendicular to the rotation axis of the color wheel.

Abstract: A scanning optical system is used to re-form an original image on a CCD line sensor. The optical system has an object side lens unit, a mirror and an image side lens unit. The object side lens unit condenses light from the object. The mirror is arranged between the object side lens to deflect the light having passed through the object side lens unit for scanning. An exit pupil of the object side lens unit coincide with an entrance pupil of the image side lens unit.

Abstract: An illumination optical system has a light source, an integrator for making the intensity distribution of the light from the light source even, and a relay optical system for imaging the light from the integrator on a plane conjugate with the exit surface of the integrator. The relay optical system includes a rear lens unit of which the refractive power is asymmetrical in one direction so that the plane on which the light is imaged is inclined relative to the optical axis of the relay optical system. This makes it possible to direct light to an inclined surface with an even intensity distribution and with minimum loss of the illumination light.

Abstract: In a projector optical system provided with a DMD having minute mirror devices regularly arranged on one plane so as to correspond to the pixels of an image and selectively reflecting illuminating light in the direction of the optical axis of a projection optical system or in a direction different from the direction of the optical axis by bringing the mirror devices into an ON state or an OFF state according to the input video signals, and a prism disposed between the DMD and the projection optical system and having a first surface reflecting the illuminating light to be directed to the DMD and transmitting the light reflected at the DMD, the prism has a second surface transmitting, of the light transmitted by the first surface, light reflected at the mirror devices in the ON state and reflecting light reflected at the mirror devices in the OFF state.

Abstract: An illuminating apparatus has a light source emitting illumination light; and a prism having a plurality of reflecting surfaces and reflecting the illumination light from said light source by the reflecting surfaces to thereby bend an illumination optical path at an obtuse angle.

Abstract: A projection optical apparatus has a light source for emitting light, an illumination optical system for emitting as illumination light the light radiated from the light source, a Digital Micromirror Device™, having a plurality of micromirrors, for separating the illumination light into signal light and unnecessary light by varying, in accordance with a signal, the angles at which the individual micromirrors reflect the illumination light shone thereon, a total internal reflection prism composed of a first prism for totally reflecting and thereby directing the illumination light exiting from the illumination optical system to the Digital Micromirror Device™ and a second prism for transmitting the signal light reflected from the Digital Micromirror Device™, and a projection optical system for projecting the signal light transmitted through the second prism onto a projection surface.

Abstract: An optical apparatus has a reflection-type spatial light modulator having a plurality of minute variable-reflection-angle mirrors that individually deflect the light incident thereon in one of two different directions, namely in a first direction or in a second direction, in accordance with a signal fed in, an optical system to which the light deflected in the first direction by the modulator is directed, a prism disposed between the modulator and the optical system so as to direct the light deflected in the first direction by the modulator to the optical system and direct the light deflected in the second direction by the modulator to a side face of the prism, and a light-absorbing member shaped like a plane-parallel plate and disposed with an entrance face thereof kept in close contact with the side face of the prism.

Abstract: A projection system that is capable of providing a high-performance projection system and producing a high contrast projection image by using an optical modulation element, which can be positioned a predetermined distance away from an illumination optical system and a projection optical system. The optical modulation element is capable of modulating light received from the illumination optical system and projecting the modulated light to a projection optical system in the direction of a projection surface.

Abstract: In an optical system includes a first prism having a first surface and a second surface forming mutually acute angles, and a second prism having a third surface. The first prism and the second prism forms an air gap between the second surface and the third surface. The air gap formed by the second surface and the third surface is a cross section perpendicular to the first surface and the second surface having a wedge shape which widens at a part near the first surface and narrows at a part distant from the first surface.