LED pixel structures and methods that improve brightness uniformity by reducing current nonuniformities in a light-emitting diode of the pixel structures are disclosed.

Active matrix light emitting diode pixel structure and concomitant method

A display panel is formed using essentially single crystal thin-film material that is transferred to substrates for display fabrication. Pixel arrays form light valves or switches that can be fabricated with control electronics in the thin-film material prior to transfer. The resulting circuit panel is than incorporated into a display panel with a light emitting or liquid crystal material to provide the desired display.

Single crystal silicon arrayed devices for display panels

A color active matrix display system allows random access of pixel electrodes. The control electronics is fabricated with the active matrix circuitry using single crystal silicon technology. The control electronics includes a random access data scanner and random access spec scanners. By selectively actuating pixel electrodes in the active matrix display region, compressed video information can be directly displayed on the active matrix display panel. Color stripes are used to generate sequential color systems to produce a color image from the active matrix display panel.

Color sequential display panels

By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.

Light Emitting Device

A back-lighted color LCD display (231) is formed by placing a single matrix of liquid crystal devices (LCDs) over a bank of red, green and blue fluorescent lamps (202-218). The LCD matrix is operated to sequentially form separate red, green and blue images synchronous with the illumination of the respective red, green and blue lamps. The flashing of the sequential red, green and blue images is perceived as a color image. The images are scanned, one line at a time, onto the LCD matrix. The bank of fluorescent lamps includes several lamps of each color which are arranged in parallel with the lines of the LCD matrix. The different lamps of each color are activated in synchronism with the scanning of the LCD matrix. Each LCD in the matrix includes a rapidly varying liquid crystal material, sandwiched between conductive plates. The electric field between the conductive plates may be controlled by a polysilicon thin-film transistor (256).

Field-sequential display system utilizing a backlit lcd pixel array and method for forming an image

A drive network for a TFEL panel includes a series resonant drive circuit for producing pulses of a predetermined frequency, a transformer for coupling the drive circuit to a TFEL panel, and symmetrically driven push-pull row drivers, a plurality of which may be implemented on a single integrated circuit chip. The transformer includes switching means for alternately providing positive and negative high-voltage pulses for the row drivers on alternate frames of data. The network formed by the series resonant drive circuit and the TFEL panel is a series RLC circuit which is driven at its resonant frequency.

Transformer-coupled drive network for a TFEL panel

An electrode structure for an AC matrix-addressed TFEL panel includes top and bottom sets of scanning electrodes, each located in a respective half of the panel, and top and bottom sets of data electrodes extending at right angles to the scanning electrodes where each electrode in the top and bottom set extends for a distance slightly less than halfway across the panel to provide a split screen display. The scanning electrodes are driven by driver amplifiers that simultaneously energize complimentary pairs of the scanning electrodes in the top and bottom halves of the panel driving them in line-by-line fashion. The top and bottom sets of data electrodes are driven simultaneously by top and bottom sets of electrode drivers simultaneously with each scan of the data electrodes. In this way the top and bottom halves of the panel are scanned simultaneously, and the writing of one frame of data is faster. Also, the column electrodes are shorter and therefore require less energy and consume less power per frame.

Split screen electrode structure for TFEL panel

A matrix-addressed AC TFEL panel includes odd- and even-numbered scanning electrodes driven from opposite sides of the panel by separate power supplies. The data electrodes are divided into top and bottom sets so that they are arranged as complementary pairs extending towards each other slightly less than halfway across the screen leaving a small gap in the middle. The odd- and even-numbered scanning electrodes are divided into top and bottom subsets so that the top and bottom halves of the panel may be scanned simultaneously in line-by-line fashion. When an even electrode in the top half of the panel is scanned with a voltage of a first polarity, an odd electrode in the bottom half may be scanned with a voltage of an opposite polarity. Thus, the load for the scanning of the top and bottom halves is divided between positive and negative power supplies. To provide symmetric drive the polarities may be reversed each frame.

Alternate polarity symmetric drive for scanning electrodes in a split-screen AC TFEL display device

A driving architecture for a matrix addressed TFEL display includes upper and lower data electrode arrays divided by a narrow gap and scanning electrodes arranged in complementary pairs one for each array of data electrodes The data electrodes are charged at a rate which minimizes the power loss in the resistive component of the data electrode circuitry The top and bottom data electrode arrays may be driven simultaneously, thereby decreasing the time needed to scan the panel, thus permitting more electrodes and larger screens The split-screen array provides shorter data electrodes which take less time to charge, thus permitting use of energy-saving techniques which require a slower charging rate

Energy-efficient split-electrode TFEL panel

A TFEL panel includes orthogonally disposed sets of scanning and data electrodes. The scanning electrodes are strobed with a preconditioning voltage and data is provided to selected data electrodes simultaneously with the line by line strobing of the scanning electrodes. A refresh pulse is applied to the screen once per frame of data at times which vary from frame to frame. This may be accomplished either by varying the time of occurrence of the refresh pulse within each frame or by holding the time of occurrence of the refresh pulse constant and varying the strobing sequence of the scanning electrodes. This technique prevents certain portions of the screen from generating a latent image due to charge accumulation which would otherwise result from the timing asymmetry between the scanning of certain electrodes and the fixed timing of the refresh pulse.

Robert T. Flegal

Papers

Transformer-coupled drive network for a TFEL panel

Split screen electrode structure for TFEL panel

Alternate polarity symmetric drive for scanning electrodes in a split-screen AC TFEL display device

Energy-efficient split-electrode TFEL panel

Staggered refresh pulse generator for a TFEL panel