Abstract: A projector (12N) of this invention employs a 380 mm diagonal, amorphous silicon LCD (80) for receiving light rays from a light source (70), which achieves a small source size by employing four lamps (160) with small arc gaps (166) and a “pinwheel” mirror (164) that overlaps light rays from each of the arc lamps into a single collimated light bundle. The small source size produces a small cone angle (130) of light through the LCD. A lens (78) directs the narrow cone of light though the LCD at an optimal angle for achieving a 1,500:1 contrast ratio. Only a 4× magnification ratio is required to achieve a 170 cm (67 inch) diagonal projected image, which ratio enables projecting SXGA or greater resolution images with a five element projection lens (86). The LCD achieves an operational life of at least 50,000 hours before projected images display color degradation.

Abstract: A stackable mechanical package for a digitally addressed projector (12N) includes a housing portion (22) having top and rear surfaces (44) that are shaped to form a contoured recess (46), and a pedestal portion (20) having bottom and front surfaces (60) that are sized to mate with the contoured recess when the package is in a shippable configuration. When a top side (50) of the pedestal portion is mated to a bottom side (32) of the housing portion, the stackable package is in a first operational configuration. Alternatively, when the stackable package is stacked below another similar stackable package (12F), the shippable configuration further forms a second operational configuration. The stackable package includes legs (24, 26) attached to and protruding from the pedestal portion to support the package apparatus in the first operational configuration or to fasten together the housing and pedestal portions when the package is in the shippable configuration.

Abstract: A stackable mechanical package for a digitally addressed projector (12N) includes a housing portion (22) having top and rear surfaces (44) that are shaped to form a contoured recess (46), and a pedestal portion (20) having bottom and front surfaces (60) that are sized to mate with the contoured recess when the package is in a shippable configuration. When a top side (50) of the pedestal portion is mated to a bottom side (32) of the housing portion, the stackable package is in a first operational configuration. Alternatively, when the stackable package is stacked below another similar stackable package (12F), the shippable configuration further forms a second operational configuration. The stackable package includes legs (24, 26) attached to and protruding from the pedestal portion to support the package apparatus in the first operational configuration or to fasten together the housing and pedestal portions when the package is in the shippable configuration.

Abstract: An LCD projection unit employs a luminance and color balance system employing an LCD array characterization lookup table storing multiple sets of luminance and gamma correction values that are user selectable to control luminance and color balance. The lookup table values are determined by measuring the transfer function of the LCD array in the projection unit for each of a set of red (“R”), green (“G”), and blue (“B”) input data values, converting the resulting S-curve responses to corresponding sets of gamma responses and scaling the gamma responses to generate multiple R, G, and B families of luminance and gamma corrected values. Color balance is adjusted by selecting the particular R, G, and B families of luminance and gamma corrected values that cause the LCD projection unit to match a predetermined ratio of R, G, and B luminance values.

Abstract: An LCD projection display (120) houses a projection module (10) in which light propagates through an LCD module (38) at a shallow angle (62) that improves the contrast ration of and intentionally Keystones the image bearing light. The Keystoned light is reflected by a fold mirror (64) that is mounted at a 52° upward angle, which introduces more intentional Keystoning. A projection lens (16) is mounted coaxial to a tilted optical axis (12), but the Keystoned image bearing light is refracted about 10° off the optical axis and follows a Keystoning axis (70) through the projection lens. The light propagating from the projection lens is reflected by a main fold mirror (122) that is mounted at a 57° angle from the vertical to project the image bearing light onto a 10° slanted projection screen (98).

Abstract: A liquid crystal display ("LCD") projection unit (12) employs a luminance and color balance system having a lookup table (100) storing multiple sets of gain and/or gamma corrected responses (92-99) for color balance and luminance control. The lookup table values are determined by measuring an S-curve response (90) of an LCD array (40) for each of a set of R, G, and B input data values, converting the S-curve responses to a corresponding set of gamma responses, and scaling the gamma responses to generate red ("R"), green ("G"), and blue ("B") families of gain and gamma corrected values. Color balance is adjusted by selecting the particular R, G, and B families of gain and gamma corrected values that cause the LCD projection unit to match a predetermined ratio of maximum R, G, and B luminance values. Luminance is adjusted by selecting families of lookup table values that adjust the transmittance of the LCD while maintaining the color balance.

Abstract: A mechanical package for an LCD projector includes approximately equally sized tower and enclosure portions. The tower portion is supported on forward protruding legs and contains optical and electronic modules that slide into its rear and are also accessible from the front of the enclosure portion. The enclosure portion supports on its front a removable projection screen and is mounted vertically offset on the tower portion. A triply folded optical axis provides a suitably long light pathway for projecting a large image on the projection screen without requiring the package to have an undue depth. To stack multiple packages vertically, side margins of the tower portion top surface include L-channels that receive the legs of a package stacked above. The enclosure portion further includes openings that receive the legs protruding from the tower portion stacked above. The legs are supported within the enclosure portion by sliding into U-brackets that are attached to the inner surfaces of the enclosure portion.

Abstract: Method and apparatus for providing gray level addressing for passive liquid crystal display (LCD) panels having overlapping row and column electrodes defining pixels are disclosed. Depending upon whether the rows are being addressed by "standard" or "Swift" addressing, the signals for applying to the column electrodes are determined by different calculations, in all of which modes the amplitudes of the column signals are related to the gray level desired to be displayed by the individual pixels. For a split interval system, column signals of appropriate amplitude and polarity are applied during different subintervals of a characteristic time interval of the display panel depending upon the method of addressing the rows. In the full interval mode, the column signals applied over a full time interval are based on the desired gray level of all the pixels in the column, adjusted to provide the proper rms voltage across all the pixels so that they display the desired gray levels.

Abstract: An addressing method and apparatus addresses faster responding liquid crystal display panels (LCDs) so that video rate, high information content LCDs having time constants on the order of 50 ms or less are perceived as having improved contrast by limiting peak voltage levels across the pixels. In a preferred embodiment, a first set of LCD electrodes is continuously driven with signals each comprising a train of pulses that are periodic in time, have a common period T, are independent of the information to be displayed, and are preferably orthonormal. Plural column signals are generated from the collective information states of the pixels defined by the overlap with a second electrode pattern. Each column signal is proportional to the sum, obtained by considering each pixel in the column, of the exclusive-or (XOR) products of the logic level of the amplitude of each row signal times the logic level of the information state of the pixel corresponding to that row.

Abstract: Method and apparatus for providing gray level addressing for passive liquid crystal display (LCD) panels having overlapping row and column electrodes defining pixels are disclosed. Depending upon whether the rows are being addressed by "standard" or "Swift" addressing, the signals for applying to the column electrodes are determined by different calculations, in all of which modes the amplitudes of the column signals are related to the gray level desired to be displayed by the individual pixels. For a split interval system, column signals of appropriate amplitude and polarity are applied during different subintervals of a characteristic time interval of the display panel depending upon the method of addressing the rows. In the full interval mode, the column signals applied over a full time interval are based on the desired gray level of all the pixels in the column, adjusted to provide the proper rms voltage across all the pixels so that they display the desired gray levels.

Abstract: Method and apparatus are disclosed for providing gray level addressing for passive matrix liquid crystal display (LCD) panels having pixels defined by overlapping row and column electrodes. The pixels have optical states determined by the rms voltage appearing across the pixels during a frame period. The frame period is divided into characteristic time intervals, which are further divided into sub-intervals. The amplitude of the column signals during each of the sub-intervals is determined from the desired gray level of the pixel or pixels defined by the corresponding column electrode and selected one or ones of the row electrodes.

Abstract: The invention identifies the cause of and solves so-called display pattern splicing in passive matrix displays implemented with Active Addressing.TM. techniques or other techniques that produce column signals having more than one magnitude. Splicing is an optical aberration that is manifested by a transient pixel rms voltage deviation from a current, frame-averaged value that occurs when one image changes to a new one. Active solutions to display pattern splicing apply a correction of some type to counteract the effects of the transient optical response. Preferred active solutions are premised on the observation that splicing is an effect common to all pixels on a column. One type of active solution includes different embodiments that entail determining the amplitude and character of the display pattern splice and introducing a compensating signal as a function of the amplitude and character of the splice to counteract it.

Abstract: Different gray shades or hues may be displayed in accordance with an active addressing technique that addresses faster responding passive matrix liquid crystal display panels (LCDs) so that video rate, high information content LCDs are perceived as having improved contrast by limiting peak voltage levels across the pixels. A preferred embodiment of the active addressing technique is implemented such that a first set of LCD electrodes is continuously driven with signals each comprising a train of pulses that are periodic in time, have a common period T, are independent of the information to be displayed, and are preferably orthonormal. Multiple column signals are generated from the collective information states of the pixels defined by the overlap with a second electrode pattern.

Abstract: Integrated driver circuitry including row and column signal generators addresses faster responding liquid crystal display panels (LCDs) so that video rate, high information content LCDs having time constants on the order of 50 ms or less are perceived as having improved contrast by limiting peak voltage levels across the pixels. In a preferred embodiment, a row signal generator includes a row signal function generator and row driver circuitry including a level shifter that delivers to each of the row electrodes a signal level corresponding to the row signal value at a time interval of a frame period. A column signal generator applies to each of the column electrodes a column signal having an amplitude that is determined by the row signals causing selections at a particular time interval and by pixel input data components of corresponding pixels defined by the overlap of the row and column electrodes.

Abstract: A method and an apparatus for addressing a liquid crystal display (10) groups together row electrodes (28) and applies the same row addressing signal to all row electrodes in the group (48). The groupings are cyclically changed in successive addressing cycles. An image data conditioner (54) determines for use in calculating the column signals a pixel information value based upon the information values of one or more of the pixels in the selected group of row. Grouping the row electrodes reduces the effective multiplex ratio, thereby increasing the selection ratio and producing a faster responding display having higher contrast and a wider viewing angle.

Abstract: An addressing method and apparatus addresses faster responding liquid crystal display panels (LCDs) so that video rate, high information content LCDs having time constants on the order of 50 ms or less are perceived as having improved contrast by limiting peak voltage levels across the pixels. In a preferred embodiment, a first set of LCD electrodes is continuously driven with signals each comprising a train of pulses that are periodic in time, have a common period T, are independent of the information to be displayed, and are preferably orthonormal. Plural column signals are generated from the collective information states of the pixels defined by the overlap with a second electrode pattern. Each column signal is proportional to the sum, obtained by considering each pixel in the column, of the exclusive-or (XOR) products of the logic level of the amplitude of each row signal times the logic level of the information state of the pixel corresponding to that row.

Abstract: The optical response of the pixels of many flat panel display devices, such as liquid crystal displays (2), depends upon the spectral components, as well as the rms value, of the pixel voltage waveform during a frame period. Because each row and column electrode (10 and 11) addresses multiple pixels (14), the spectral voltage components of the voltage across any pixel during a frame period will depend upon the optical state of other pixels in the same column (11). This crosstalk phenomena can be greatly reduced by modifying the addressing signals. One method of modifying the addressing signals is to modulate them so that the spectral components of all pixel voltage waveforms fall primarily in a frequency band (54) in which the optical response is nearly independent of the frequency.

Abstract: Method and apparatus for providing gray level addressing for passive liquid crystal display (LCD) panels having overlapping row and column electrodes defining pixels are disclosed. Depending upon whether the rows are being addressed by "standard" or "Swift" addressing, the signals for applying to the column electrodes are determined by different calculations, in all of which modes the amplitudes of the column signals are related to the gray level desired to be displayed by the individual pixels. For a split interval system, column signals of appropriate amplitude and polarity are applied during different subintervals of a characteristic time interval of the display panel depending upon the method of addressing the rows. In the full interval mode, the column signals applied over a full time interval are based on the desired gray level of all the pixels in the column, adjusted to provide the proper rms voltage across all the pixels so that they display the desired gray levels.

Abstract: Image quality is improved in an rms-responding, passive matrix display system (10) by correcting for voltages induced onto row addressing electrodes (22) by voltage transitions on column electrodes (24). Net crosstalk voltages sensed at nodes (88N and 88P) between a row driver (72) and voltage sources (70N and 70P) correspond to the voltage induced on a row electrode plane (136). A correction voltage corresponding to the net crosstalk voltage on the row plane is applied to the voltage sources to correct the rms pixel voltages for the crosstalk.