Infocus Systems, Inc.

Tektronix, Inc.

3m Innovative Properties Company

Motorola Corporation

Dennis W Prince

Benjamin R Clifton

Terry J Scheffer

Arlie R Conner

Thomas S Buzak

Kevin J Ilcisin

Paul C Martin

Philip J Bos

John K Grosspietsch

William W Stein

William J Leybold

An LED illumination system includes control circuitry and first, second and third colored LEDs. The control circuitry sequentially drives the first, second and third colored LEDs in a color cycle frame with relative duty cycles having a known relationship that achieves a color balance. The control circuitry also operates to introduce at least one spoke period in the color cycle frame, during which the first, second and third LEDs are driven in a manner that is controlled to provide brightness adjusting light that matches the color balance achieved by the relative duty cycles of the first, second and third LEDs during sequential driving thereof.

Light emitting diode (LED) illumination control system and method

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. The adjustment can be spread across multiple addressing intervals and can be added into the column signal when rows are selected or can be applied to the column electrode when no row is selected.

Gray level addressing for LCDs

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. One embodiment modifies the column signal values applied to the column electrodes, and another embodiment adds correction time intervals to a frame period to adjust the rms voltages of the column signals applied during the frame period.

Methods and systems for detecting and correcting dynamic crosstalk

Image data or addressing signal information for a dual-scan display (110, 168) is stored in three half-frame buffers (114a, 114b, and 114c; 172a, 172b, and 172c). Each of two buffers contains complete display information, comprising either image data or column signal data, for section 126B or 126T of the display. The third buffer receives and stores image data or column signals for a subsequent frame for one of the two display sections. By offsetting the frame periods of the two independent display sections, both display sections have display information corresponding to a complete frame without requiring two complete frame buffers, thereby reducing cost, size, and complexity of the display.

Memory configuration for display information

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.

Plural line liquid crystal addressing method and apparatus

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. Another method is to analyze (220) the spectral components of the pixel voltage waveform over a frame period before it is displayed and adjust (222) the amplitude of the addressing signals to compensate for the frequency dependence of the optical response. When using a gray scale addressing method involving an adjustment factor, such as one based upon virtual pixels (266), the value of each virtual information element (270) is multiplied by a correction factor to compensate for the different frequency components associated with the virtual row.

Addressing method and system having minimal crosstalk effects

Crosstalk is reduced in any type of active matrix electro-optical display system (10) by applying a compensating signal, the value of which is dependent upon multiple data drive signals. In a preferred embodiment, a single compensating signal, equal to the inverse weighted average of all of the data drive signals applied during a row address period, can be applied to all data electrodes (20) after the data drive signals are stored in display elements (16). Such a compensating signal simultaneously reduces side-to-side crosstalk and front-to-back crosstalk to levels previously achievable for only one type of crosstalk at a time.

Adaptive drive waveform for reducing crosstalk effects in

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.

Passive matrix display having reduced image-degrading crosstalk effects

A plasma addressing structure functioning as a display panel (52) includes an ionizable gas captured within a network (110) of intersecting channels formed by multiple spaced-apart islands (60) arranged in substantially parallel rows (62) projecting from the major surface (104) of an underlying substrate (64). The network of channels includes elongated channels (112) that are positioned between adjacent rows of islands, and spur channels (114) that extend between individual islands in each row and couple adjacent elongated channels. The gas in the network of channels is selectively ionized to address display elements (54), which are aligned with the islands positioned along each of the island rows. Each island has a top surface or plateau (128) that is spaced-apart from and substantially parallel to the major surface from which the island projects. The plateaus provide a relatively large surface area for supporting addressing structure components such as a layer (68) of electro-optic material and a layer (96) of dielectric material.

Channel arrangement for plasma addressing structure

A pair of infrared linked stereoscopic glasses (18) receives a train of short infrared pulses from a transmitter (26) of a stereoscopic imaging system (10). The rising edges of the infrared pulses are synchronized with the beginnings of the even numbered fields of a stereoscopic image displayed on a video display (14). In a stereo mode, the glasses provide a three-dimensional appearance because right and left liquid crystal cells (40 and 42) switch right- and left-eye pieces (20 and 22) between transmissive and opaque states synchronously with the even and odd fields of the stereoscopic image. In a flickerless mode, the right- and left-eye pieces are both essentially continuously transmissive. An optical state controller (36) is self-synchronizing in that a single pulse of the electrical pulse train signal will control the optical states of both the right- and left-eye pieces during a complete stereoscopic image. The transmitted IR pulses are not modulated and the electrical pulse train signal produced in response to the received IR pulses is not demodulated. The glasses automatically switch from stereo mode to flickerless mode when the glasses cease receiving the IR pulses. The glasses automatically switch from flickerless mode to stereo mode when the glasses begin to receive the IR pulses. The maximum voltage (VDD) applied to the electrodes (184, 186, 206, and 208) of the right and left liquid crystal cells is substantially higher in stereo mode than that in flickerless mode.

Self-synchronizing optical state controller for infrared linked

A field sequential color display system (10) employs a liquid crystal device operating as a variable optical retarder (12) which is positioned in front of the screen (40) of a raster scanned cathode ray tube (38) to develop a high quality multicolored image. The liquid crystal device is divided into upper and lower cell segments (34 and 36) to decrease the time between successive color fields. Each cell segment has a separate electrode structure (30 and 32) and a common electrode structure (22) and is separately commanded by a switching circuit (46) to a predetermined optical retardation state when the electron beam scans the portion of the screen covered by the cell segment. The switching circuit provides signals in a predetermined time sequence to the cell segments to minimize the optical cross talk between them and thereby minimize the spurious transmission of colored light from the display system.

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Banks, OR, United States of America

Dennis W Prince