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 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 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.

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. The first unit has a negative power and includes at least three lens elements L1, L2, and L3, where L1 is composed of plastic and has two aspherical surfaces, L2 has a positive power and is composed of a flint material, and L3 has a negative power and is composed of a crown material. The second unit has two subunits U2.sub.S1 and U2.sub.S2, each of which has a positive power, with the power of U2.sub.S2 being greater than the power of U2.sub.S1. At its minimum effective focal length f.sub.min, the projection lens has a back focal length to focal length ratio greater than one, the ratio being achieved by arranging the first unit, the second unit, and the subunits of the second unit so that:D.sub.12 /f.sub.min >1.0,D.sub.S1S2 /f.sub.min >1.0,andD.sub.12 /D.sub.S1S2 >1.0,where D.sub.

Abstract: Projection lenses for use with pixelized panels, e.g., LCD panels, are provided. The lenses have a large focus range, e.g., a focus range of greater than 0.05 and in many cases greater than 0.1, and a limited (mini) zoom range, e.g., a zoom range of less than 15% (.+-.7.5% from the center of the range). By limiting the zoom range, complex lens structures involving large numbers of lens elements are avoided. In particular, the lenses employ at most one additional lens element and in many cases no additional lens elements compared to non-zooming lenses having a similar focus range.

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 panels is provided. The lens has two aspherical meniscus elements which are concave to each other and are located in the vicinity of the lens' aperture stop and a color-correcting doublet which provides most of the positive optical power of the lens. The lens can also include an aspherical corrector lens element of weak optical power which is located on the side of the two meniscus elements opposite to the color correcting doublet.

Abstract: Six-component projection lens systems for use in projection televisions are provided. From the screen side, the systems preferably have a + - +++ - configuration. The use of a second lens element having a negative power results in improved sagittal modulation transfer functions (MTFs) at large field locations. The negative second lens element can be made of a low dispersion material, such as styrene, so as to provide partial correction of axial color.

Abstract: A method for producing a lens system is provided in which an exact field curvature (EFC) value is determined for at least one principal ray, the EFC value being given by:EFC=-.SIGMA.(n'-n)c/nn'the summation being taken over the surfaces of the system, and for each of the surfaces, n is the index of refraction on the object side of the surface, n' is the index of refraction on the image side of the surface, and c is the curvature of the surface at the intersection of the surface with the principal ray, c being positive if the center of curvature is on the image side of the surface.

Abstract: Telecentric lens systems for use with pixelized panels, such as LCD or DMD panels, are provided. The systems have a long aperture stop to object distance (ASOD) and a high level of aberration correction, including a high level of lateral color correction. Preferably, the systems also have a low f-number and are wide angle. The systems include a negative first unit which produces the long ASOD, a weak second unit which includes two meniscus elements which surround the system's aperture stop, and a positive third unit which images the aperture stop to form the system's telecentric pupil.

Abstract: A projection lens in which a lens unit which may comprise one or two elements is closely coupled at the object end of the lens to a cathode ray tube. At the image end is a lens unit of overall weak optical power which comprises from the image end a first positive element followed by a closely spaced negative element of substantially higher dispersion. Intermediate the object side lens unit and the image side lens unit is a lens unit of substantial optical power supplying substantially all of the positive optical power of the lens. Closely spaced to this power lens unit on the object side is a negative lens element of high dispersion. This negative lens element may be considered to be part of the power lens unit.

Abstract: A lens comprising from the image side a first lens unit which is a positive element with at least one aspheric surface; a three element lens unit consisting of a biconcave element, a biconvex element and another positive component, in that order; a third lens unit having a strongly concave image side surface and which serves as a field flattener and to correct the Petzval sum of the lens.

Abstract: A projection lens for a cathode ray tube display which comprises from the image end a first lens unit of relatively weak optical power serving primarily to correct aperture dependent aberrations, a second lens unit of strong positive power permitting decreased equivalent focal length and resulting wide field angle, and a third lens unit having a strongly concave image side surface and serving to correct the Petzval curvature of the surfaces of the other lens units. The second lens unit comprises two elements of overall biconvex shape separated by an air gap. The facing surfaces of the two elements of the second lens unit are of relatively weak optical power and at least one of the surfaces of the two elements of the second lens unit is aspheric to contribute to the corrections provided by said second lens unit.