Abstract: A projection television system (10) is provided which has a CRT (16) and a projection lens system (13) for forming an image on a screen (14). The projection lens system (13) is characterized by a diffractive optical surface (DOS) which provides color correction for the lens system. The diffractive optical surface (DOS) can be formed as part of a diffractive optical element (DOE) or as part of an existing lens element of the lens system. The diffractive optical surface (DOS) is located between the object side (S2) of the lens' first lens unit (U1) and the image side (S11) of the lens' third lens unit (U3). The distance between the diffractive optical surface (DOS) and the lens' aperture stop (AS) is less than 0.1·f0, where f0 is the focal length of the projection lens (13).

Abstract: Projection lens systems for use in CRT projection televisions are provided. The lens systems include a negative lens unit (U4) which is associated with the CRT during use of the lens system and four lens elements (L1, L2, L3, CR) on the image side of the negative lens unit (U4). Three of those lens elements (L1, L2, L3) are arranged as follows from the long conjugate to the short conjugate of the lens system: a first lens element (L1) which has a weak optical power and at least one aspherical surface; a second lens element (L2) which has a positive focal length and provides most of the optical power of the lens system; and a third lens element (L3) which has a positive focal length and at least one aspherical surface. The last lens element of the system is a corrector lens element (CR) which is located adjacent to the second lens element (L2) and has a weak optical power, at least one aspherical surface, and is substantially flat.

Abstract: Optical systems for use with reflective LCDs (8,9,32,34,36) are provided. The systems include a polarization beam splitter (5) which can be composed of polarization beam splitting cubes (26) having sheet polarizers (30) and/or half wave plates (28) at their mating surfaces. By orienting the half wave plates (28) so that they convert S polarization to P polarization and P polarization to S polarization, the polarization beam splitter (5) can provide a high contrast ratio at a viewing screen between light from the “on” and “off” pixels of the reflective LCDs (8,9,32,34,36).

Abstract: A prism (13) for use in a projection system which employs a digital light panel (35) is provided. The prism includes first (19) and second (21) spaced part surfaces which are oriented such that: (a) light from a light source (33) will pass through the spaced apart surfaces to the digital light panel; (b) light from “on” pixels will undergo total internal reflection at the second surface (21) and be directed into the acceptance angle of a projection lens (39); and (c) light from “off” pixels which reflects from the second surface will be directed away from the lens' acceptance angle.

Abstract: Six-component projection lens systems (13) for use in CRT projection televisions (10) are provided. To provide an improved overall modulation transfer function across the field of view of the lens, the system's first lens element (L1) has an object side surface (S2) which has a best fit spherical surface which is convex to the CRT (16). To provide partial axial color correction, the system's second lens element (L2) is made of a high dispersion material, such as styrene.

Abstract: A zoom projection lens for use with LCD or DMD panels is provided. The lens has two units U1 and U2, which are moved relative to one another for zooming. It also has a corrector unit (CR) at a fixed distance from the LCD or DMD panel (PP). The corrector unit, which may be a color correcting doublet, is at the object (panel) end of the lens and has a weak power. This unit allows for a high level of distortion and lateral color correction, without unduly increasing the complexity or cost of the lens.

Abstract: Projection lens for use with pixelized panels are provided which consist of a first lens unit which has a negative power and a second lens unit which has a positive power. The V-values and Q-values of the lens elements of the first and second lens units are selected so that the projection lenses can simultaneously have: (1) a high level of lateral color correction, including correction of secondary lateral color; (2) low distortion; (3) a large field of view in the direction of the image (screen); (4) a telecentric entrance pupil; and (5) a relatively long back focal length.

Abstract: A zoom projection lens for use with pixelized panels is provided. The projection lens has a negative/positive (retrofocus) form, with the positive lens unit (U2) having two positive subunits (U2S1, U2S2). The image (screen) side subunit (U2S1) serves as focus corrector for the lens, i.e., after zooming, this subunit is moved to adjust the focus of the lens. Compared to moving the negative unit (U1), this approach achieves better aberration correction and involves moving less mass through smaller distances.

Abstract: Focusable, color corrected, high performance projection lens systems are provided which include three lens units (U1, U2, U3), the first lens unit being composed of two subunits (U.sub.S1, U.sub.S2). The lens systems can have f/190 's less than 1.0, total fields of as much as 90.degree., low vignetting losses, and MTF values greater than 0.5 at 10 cycles/mm through 0.85 of the full field. By varying the space between the first and second lens units, these performance levels can be maintained as the lens system is focused over a range of conjugates of approximately .+-.7.5% from a center value of about 4 meters. The lens systems can be used in such demanding applications as flight simulators.

Abstract: A coupler system (13) for mounting a projection lens (15) to a cathode ray tube (16) in a projection television (10) is provided. The system includes a first member (20) composed of a heat and chemical resistant plastic and a second member (22) composed of metal. The second member (22) is mounted to the periphery (18) of the faceplate (17) of the cathode ray tube (16) to provide a high level of heat transfer from the tube. The second member also absorbs x-rays emitted by the tube. The first member can be readily molded from high performance plastic resins and thus reduces the overall cost of the coupler system compared to couplers composed entirely of metal.

Abstract: A projection television lens system having a device that distorts for telescopically adjusting an A/B assembly, the tubular member that carries the A and B lens elements within a focus mount of a projection television lens system. Additionally, at one end of the lens, there is provided a fixed mounting site, i.e. a mounting site which is fixed in position with respect to the CRT 9 assembly. A device is then provided which connects the fixed mounting site to the tubular member. The thermal and structural characteristics of the device are selected so that the device itself distorts in response to temperature changes and thereby moves the A and B lens elements toward or away from the C element in response to, respectively, increased or decreased ambient temperature. In the most preferred embodiment, the fixed mounting site is on the focus mount at the image side of the lens assembly.

Abstract: A lens system for an electronic system has two lenses. The first lens (S1/S2) has a negative power, and the second lens (S4/S5 or S5/S6) has a positive power and is spaced from the first lens (S1/S2) by a distance of at least a quarter of the focal length of the lens system. In one embodiment (FIG. 3), the second lens (S4/S5) is a refractive-diffractive hybrid lens; in which case both the first and the second lenses (S1/S2 and S4/S5) can be composed of acrylic, and can have only spherical and conic surfaces. In other embodiments (FIG. 1, 2, 4), the first lens (S1/S2) has a higher dispersion than the than the second lens (S4/S5 or S5/S6); for example, the first lens (S1/S2) is composed of styrene, and the second lens (S4/S5 or S5/S6) is composed of acrylic. In this case, the first lens (S1/S2) can have a spherical surface and a general aspherical surface, and the second lens (S5/S6) can have conic surfaces (FIG.

Abstract: A projection lens for use with a pixelized panel (LCD) is provided. The lens has two positive lens units with an aperture stop between them. The optical powers of each of the units are such that f1 is substantially shorter than f2, where f1 and f2 are the focal lengths of the first lens unit and the second lens unit, respectively, the first lens unit being on the system's long conjugate side and the second lens unit being on the short conjugate side. The ratio of f1 to f2 is preferably less than about 0.75.

Abstract: A projection television system (10) is provided which has a CRT (16) with a curved faceplate and a projection lens system (13) for forming an image on a screen (14). The projection lens system (13) is characterized by a power lens unit (U2) which (a) provides color correction for the lens system and (b) has two positive lens elements and a negative lens element with one of said positive lens elements (L.sub.P) being at the image side of the unit. The positive lens element (L.sub.P) at the image side of the second lens unit (U2) is preferably the strongest positive lens element in the lens system, having a focal length (f.sub.P) which is less than 1.5 times the focal length of the system (f.sub.0).

Abstract: A projection lens for use with LCD panels is provided. The lens has a first lens unit which has a positive power and a second lens unit which has a negative power. The first lens unit contains at least four lens elements, namely, a positive first lens element, a negative second lens element which is composed of a high dispersion material, a third lens element of weak optical power, and a positive fourth lens element of strong optical power. The projection lens achieves a correction of chromatic aberration on the order of about a quarter of pixel for large LCD panels having pixels on the order of 200 microns.

Abstract: Projection lens having long focal lengths for use with LCD panels are provided. The lenses have a first lens unit which has a positive power and a second lens unit which has a negative power. The first lens unit contains at least three lens elements organized into two subunits, namely, a positive first lens subunit having a positive lens element and a negative lens element and a positive second lens subunit having a positive lens element. The second lens unit contains at least two lens elements, namely, a positive lens element and a negative lens element. The projection lens preferably employs only five lens elements arranged in a positive, negative, positive, positive, negative configuration.

Abstract: A projection lens for use with LCD or DMD panels is provided. The lens has three lens units, the first unit having a negative power and at least one plastic lens element having two aspheric surfaces, a second lens unit having a negative power or a weak positive power and at least one color correcting doublet, and a third lens unit having a positive power and an aspheric surface either on a glass element or on a weak plastic element. The projection lens has a back focal length to focal length ratio of at least 3.0, the ratio being achieved by arranging the first, second, and third lens units so that:D.sub.12 /f.sub.0 >1.0,D.sub.23 /f.sub.0 >0.7,and1.5<(D.sub.12 +D.sub.23 +BFL)/BFL<4.0where: f.sub.0 is the effective focal length of the combination of the first, second, and third lens units; BFL is the back focal length of the combination of the first, second, and third lens units; D.sub.12 is the distance between the first and second lens units; and D.sub.

Abstract: A projection lens for use with LCD or DMD panels is provided. The lens has three lens units, the first unit having a weak power, at least one aspheric surface, a high dispersion negative lens element, and a low dispersion positive lens element, the second lens unit having a positive power, and the third lens unit having a negative power and an overall meniscus shape. The projection lens satisfies the following relationships:0.3>D.sub.23 /f.sub.0 >0.1,.vertline.f.sub.1 .vertline./f.sub.0 >1.3, andBFL/f.sub.0 >0.3where (i) f.sub.0 is the effective focal length of the combination of the first, second, and third lens units; (ii) f.sub.1 is the effective focal length of the first lens unit; (iii) D.sub.23 is the distance between the second and third lens units; and (iv) BFL is the back focal length of the combination of the first, second, and third lens units for an object located at infinity along the long conjugate side of the projection lens.

Abstract: A four element, athermalized projection lens for use in forming an enlarged color image of a LCD panel is disclosed. The powers of the elements from the screen to the LCD are negative/positive/negative/positive and the dispersions are low dispersion/low dispersion/high dispersion/low dispersion. The first three elements are composed of plastic and the last element is composed of glass. The projection lens exhibits a high level of aberration correction over magnifications ranging from about 5.times. to about 12.times.. The four element design comprises the minimum number of elements capable of achieving a relatively long back focal length, athermalization, and lateral color correction of less than about half a pixel.

Abstract: Variable focus, liquid coupled, front projection, lens systems (13) are provided for use with large screens (14), e.g., screens having a full diagonal of 1.5 meters and above. The lens systems (13) can be focused over a range of screen diagonals of at least 1.5:1 while maintaining a high level of performance as evidenced by relatively small changes in the lens system's modulation transfer function (MTF) as it is focused. The lens systems can include four lens units, namely, a positive first lens unit having a positive subunit and a negative subunit, a positive second lens unit having four lens elements at least one of which is negative, a negative corrector lens unit having an aspherical lens element, and a third lens unit which is liquid coupled to a cathode ray tube (16) during use.