Abstract: An image projection system is provided for generating an energy efficient output representative of a desired input image. The image projection system includes a light source positioning device for directing the light from a light source onto a spatial light modulator. An image source provides the desired image to the spatial light modulator and also image information to a light source position controller for coordinating the light source positioning device, such that the light from the light source impinges substantially only the area of the spatial light modulator which contains the desired image. In particular, the controller actuates the light source positioning device by using a predefined scan that corresponds to the desired image. The spatial light modulator modulates the light with the desired input image and generates an output representative of the desired image.

Abstract: A process for implementing shading corrections in a video projector. The process selects a color to be shaded, and then sets a projector video level at a selected high video level. A target brightness map is then generated for each of a plurality of preselected shading correction application points at the selected high video level. The process sets the projector video level at a selected low video level, and generates a target brightness map for each of the plurality of shading correction application points at the low video level. Actual light levels are then measured at both the high and low video levels for each shading correction application point, and differences between the target and measured brightness values are minimized. The shading process of the present invention is automatically preformed during projector set-up, and thereby eliminates the inherent subjective and time consuming need for conventional manual shading processes.

Abstract: A projection system includes first and second light valve projectors which project a composite image onto a screen by overlapping the first and second images in an overlap region. Each projector includes a light source, a light valve for reflecting or transmitting image light, a condensing lens for directing light from the light source to the light valve, and a projection lens. An improved light valve projector includes a blending device, associated with the first and second light valve projectors and being located in the path of the light between the light valve and the projection lens, the light source and the condensing lens, or the projection lens and the screen. The blending device smoothes off-state and on-state illumination levels in the overlap region without reducing the contrast ratio of said light valve projector. The blending device includes physical devices such as filters, solid masks, and/or a combination thereof as a substitute for electronic blending.

Abstract: An improved high-performance vertical sync separator which can reliably operate during high frequency and non-standard video signal conditions and that utilizes a device-independent methodology. The synch separator includes a signal separator circuit having an input port for receiving a composite signal. A measuring device connected to the input port measures a first and second characteristic of the composite signal. A processor receives and compares the first and second characteristics, and recovers a vertical sync signal from the composite signal.

Abstract: A high contrast polarizer and color beam splitter for use in a full color light valve projector includes a light source for providing input light on a first optical axis and first, second and third light valves for modulating light of first, second and third colors. The polarizer and color beam splitter includes a color and angle sensitive interface, located on the first optical axis, for reflecting at least part of the input light. A polarizer, located on a second optical axis, receives the input light reflected by the color and angle sensitive interface and reflects light of a first polarization along the second optical axis. A first color separator, located on the second optical axis at a first angle with respect to a plane orthogonal to the second optical axis, reflects light of the first color onto the color and angle sensitive interface.

Abstract: Color and/or polarization beam splitters are used in a multi-color light valve projection systems. The color and/or polarization beam splitters each include first and second prisms with a thin-film stack located therebetween. The prisms are made of glass which has an index of refraction between 1.65 and 1.85. The color and polarization beam splitters operate at an angle of incidence of 45 degrees. By operating at 45 degrees, the color and/or polarization beam splitters can be assembled in a compact and parallel manner and thereby reduce the size of the color and/or polarization beam splitter while increasing the contrast of the light valve projection system. The high index of refraction glass also produces a smaller optical path for a given physical path. The disadvantages associated with index of refraction oil prisms are also eliminated.

Abstract: A high power image projector includes a plurality of rows of spaced-apart cooling fins on the exterior surface of its light source reflector. The cooling fins are offset relative to adjacent cooling fins, thus disrupting the thermodynamic boundary layer of cooling air flowing over the reflector surface with a shroud. Thus the high-power projector can be adequately cooled with cooling air or other gases, without the need for a liquid cooling system.

Abstract: A polarized light optimization system for increasing the percentage of usable light for image projector illumination purposes. The system includes a light source, and a beam splitter that splits randomly polarized light from the light source into first and second beams having first and second polarizations. A polarization converter or rotator converts the polarization of one of the beams into the polarization of the other beam. Recombination means recombines the beams into a singularly polarized third beam, thereby increasing system illumination by increasing the percentage of usable light output from the light source.

Abstract: A light valve image projection system (10) wherein the optical registration of individual primary color images on a projection screen (14) is substantially immune to modification of the projection throw distance is disclosed herein. The inventive light valve projection system (10) is operative to project a composite optical image onto the screen (14), and includes an optical light valve apparatus (18, 19, 20) for generating first and second optical images. A converging optical system (22), in optical alignment with one or more light valves (20), is disposed to overlap the first and second images into a composite image along an optical axis. The projection system (10) of the present invention further includes a projection lens (24) for illuminating the screen (14) with the composite image.

Abstract: An adjustable gamma correction circuit that is operative to adjust grey scale distortion in a projected video signal by dynamically changing the gamma transfer function without the need to reset projector high and low amplification thresholds. The circuit includes both a linear amplification stage and a non-linear amplification stage that function to reshape the projector transfer function. At the non-linear stage consists of two pairs of emitter coupled amplifiers set at different voltage thresholds. The two pairs of emitter coupled transistors allow adjustment of the grey level of the circuit transfer function to thereby compensate for mid-level variations in the projector transfer function, thereby resulting in improved projected image quality.

Abstract: An optical system is provided that has an enclosure which is substantially filled with a fluid. The enclosure also has an aperture for receiving an electromagnetic wave that is altered by an optical component contained in the enclosure. The enclosure also has an aperture mask and blocker that are at least partially immersed in the fluid.

Abstract: An optical system including a transparent fluid and a container filled with the fluid as well as at least one optical element having an index of refraction which approximately matches that of the fluid. The fluid is chosen to have a viscosity no greater than 40 centistokes. As a result, the low viscosity of this optical fluid reduces thermal irregularities. Also, improved transmission, particularly in the blue spectrum is achieved as compared to conventional optical fluids.

Abstract: A system for measuring the illumination uniformity of a liquid light value (LCLV) for a LCLV projector includes a projection device including a first LCLV. The projection device reflects light from the first LCLV to form an image on a screen. An image sensing device senses illumination values for a plurality portions of said image. A processor is coupled to the image sensing device and the projection device. The processor determines an optimum voltage bias which provides a maximum illumination for the plurality of image pixels. The illumination uniformity measuring system can independently measure the illumination non-uniformity of the LCLV and illumination non-uniformity resulting from other sources such as projection lens roll-off, screen gain, and other illumination non-uniformities. Using the measured illumination non-uniformity, a correction system can improve the quality of the displayed image.

Abstract: A CRT compensation system (10) is disclosed which utilizes a cathode stabilizer circuit (16) to correct a cathode current I.sub.k which deviates from an ideal transfer function. The cathode stabilizer circuit (16) takes the cathode voltage V.sub.K and the cathode current I.sub.K and removes the ideal gamma transfer function from I.sub.K to produce a linear output. This linear output is then subtracted from the cathode voltage V.sub.K to produce an error voltage V.sub.err which is used to adjust the CRT drive to minimize the error in the cathode current. For example the V.sub.err the error voltage may be utilized to change the voltage level of the grid one element of the CRT (14). As a result, the CRT (14) will more closely approximate the ideal transfer function. The system (10) operates continuously and thus is able to correct for short term cathode current effects on a real time basis.

Abstract: An LCLV projection system (10) includes color separation dichroic mirrors (50, 52) positioned between a group of reflective liquid crystal light valves (38, 40, 42) and a polarizer analyzer (26) which enables a single projection lens (34) to project all colors via a light beam of single linear polarization with a high degree of contrast, efficiency and color separation. The polarizer analyzer (26) directs a light beam with a single polarization state to a pair of dichroic filters (50, 52) which separate the beam into three different colors that are sent to three different reflective liquid crystal light valves (38, 40, 42). The light valves reflect the respective colored light beams with change in polarization state back to the dichroic mirrors (50, 52) which combine the three colors into a single combined multi-color beam that is fed through the polarizer analyzer (26) to a single system projection lens (34).

Abstract: In a liquid crystal light valve projector, a quarter-wave compensator plate is disposed between a polarization plate and a liquid crystal light valve to compensate for polarization irregularities induced by the off-incident reflections in the cone of light projected onto the LCLV. The quarter-wave compensation plate reverses the phase of the P component of said illumination light with respect to said compensator plate by 180.degree. thereby eliminating P-polarization leakage during the dark state of an LCLV projector. The invention also combines the compensator plate with a heat shield and a low stress-optical coefficient counter electrode substrate to reduce the birefringence of the LCLV thereby also minimizing leakage of P-polarized light onto the projection screen during the dark state of the projector.

Abstract: A reflective liquid crystal light valve includes transparent conductive layers of indium tin oxide (30) employed as an electrode to electrically modulate orientation of molecules of a liquid crystal material that receives a high intensity reading light (40) applied through the transparent electrode. Unwanted double reflection (64,66) from interfaces between the indium tin oxide electrode (30) and adjacent layers (22,32) are minimized by application of broad band anti-reflective coatings (70,72,74,76) formed by one or more pairs of thin layers having alternately high and low indices of refraction.

Abstract: A liquid crystal light valve (12) is sequentially modulated with images corresponding to three primary color components of a scene at a rate which is faster than flicker can be perceived. A color switching apparatus (20) receives a white light beam from a high intensity light source (18), separates the white light beam into three color light beams of the respective primary colors, and sequentially illuminates the light valve (12) with the three color light beams in synchronism with modulation of the light valve (12) with the corresponding color image components. An optical system (26) projects an image of the modulated light valve surface on a screen (28), such that the three color component images appear to merge together in time and thereby synthesize a full color image of the scene.

Abstract: A video projection system employs a reflective light valve (10) that is optically addressed by an image from a cathode ray tube (12) and provides an output image for projection by means of a high intensity reading light directed to the output face of the liquid crystal light valve. Improved reading illumination is provided by scanning the face of the liquid crystal light valve (10) with a narrow beam of light (80) that moves across the liquid crystal in synchronism with the scanning image from the writing CRT (12). The scanned narrow band (80) of illumination is provided by a circular sequence of three quasi cylindrical lens (56, 58, 60) or mirrors (56a, 58a, 60a) mounted on a rotating wheel (52) and which may be made of sequentially different colors to provide a color display. Rotation of the lens or mirror bearing wheel (52) is synchronized with the vertical sync of the CRT scan, as are the index positions of each of the three lens or mirror segments on the wheel.

Abstract: A color video projection system (10) in which images of three separate colors (22,24,26) are separately projected to converge on a common region of the screen (20) is provided with automatic convergence control to ensure that three images are precisely superimposed upon each other. A test pattern of a number of pattern units (36,38) of an intensity (42,44,48) that varies over each unit in a similar manner is imaged on a two dimensional matrix array of charged coupled devices (CCD) (32). The test pattern is projected in sequence by each of the three CRT projectors (50,54,58,14,16,18) of the system, and during the projection of the test pattern, the position of the centroid (40) of each unit of the test pattern is determined from the light intensity pattern received by the CCD matrix array, and stored (112). The centroid positions of each unit of a test pattern of two of the projectors are compared with positions of the centroids of each unit of the test pattern projected by a third one of projectors.