Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Other

Chimei Innolux Corporation

Stephen J Battersby

Steven Charles Deane

John M Shannon

Ian D French

John R Hughes

Pieter J Van Der Zaag

Peter W Green

Martin John Edwards

Alan G Knapp

John R A Ayres

Louis Praamsma

Jeffrey J Harris

Stewart B Jones

James H Raistrick

Darren T Murley

Marek Szubert

An active matrix display has a column driver for providing signals to the pixels for driving the display elements, the column driver comprising digital to analogue converter circuitry providing a first number of display element drive levels. Within each pixel, the first number of display element drive levels is converted into a second, greater number, of pixel grey levels. This combines multi-level digital to analogue conversion with in-pixel level generation and enables the complexity of the DACs to be reduced so that they can be integrated onto the display substrate, for example using low temperature polysilicon processing.

Active matrix display

A display device has an arrayof pixels and row and column driver circuitry comprising row driver circuit portions R and column driver circuit portions C, each pixel being addressed by a row driver circuit portion R and a column driver circuit portion C which connect to respective row and column conductor lines. The array of pixels has a non-rectangular outer shape, and the device comprises at least three row driver circuit portions R and at least three column driver circuit portions C disposed alternately around the outer periphery of the array. This arrangement enables row and column drivers to be divided into portions which are arranged in such a way that addressing can be provided for complicated display shapes.

Non rectangular display device

A color liquid crystal display device has an array of display pixels () for modulating input light and an array of associated color filter elements () which comprise electro-optic filtering elements switchable electrically between a color filtering state in which a required color output is produced and a state in which they are substantially transparent to the input light. Such switching can be used beneficially, for example to reduce power consumption by sacrificing full color output and allowing the brightness level of a back light to be decreased in view of the increased optical efficiency of the pixels when the filter elements are in their transparent state, or to improve viewability in the case of a reflective display used in poor ambient lighting.

Color liquid crystal display devices

A method of producing a top gate thin-film transistor comprises the steps of forming doped silicon source and drain regions () on an insulating substrate () and subjecting the face of the substrate () on which the source and drain regions () are formed to plasma treatment to form a doped surface layer. An amorphous silicon layer () is formed on the doped surface layer over at least the spacing between the source and drain regions () and an insulated gate structure () is formed over the amorphous silicon layer (). Laser annealing of areas of the amorphous silicon layer not shielded by the gate conductor is carried out to form polysilicon portions () having the impurities diffused therein. In the method of the invention, doped silicon source and drain regions underlie the silicon layer to be crystallized using the laser annealing process. It has been found that the laser annealing process can then result in crystallization of the full thickness of the amorphous silicon layer. This results from the similar thermal properties of the doped source and drain regions and the silicon layer defining the main body of the transistor.

Top gate thin-film transistor and method of producing the same

A method of constructing an active matrix pixel device uses a universal active matrix (UAM) comprising a matrix array of switching elements whose spacing defines a base pitch and a pixel array comprising a matrix array of pixel electrodes whose spacing defines a pixel pitch. The pixel pitch is greater than the base pitch. A large proportion of the construction process can be carried out before the customization of the device. Using a common UAM enables a reduction in the time between the customer ordering the device and the completion time. The cost of meeting customer specific requirements for the fabrication of active matrix pixel devices is thus reduced.

Active matrix pixel device construction method

A transistor substrate for a liquid crystal display comprises an array of insulated-gate staggered TFTs and a capacitor () associated with each transistor. The gate insulator () comprises a first inorganic layer () and a second, polymer or spin-on glass layer (), of which layers only the polymer or spin-on glass layer () extends to the capacitor () to define the capacitor dielectric.

Liquid crystal display having a polymer or spin-on glass as a capacitor dielectric and a method of manufacture

The invention relates to an active matrix liquid crystal display, and in particular to an active matrix plate incorporating driver circuits ( ) for the row ( ) and column ( ) electrodes. The driver circuits ( ) are arranged on substrate ( ) underneath the row ( ) and column electrodes ( ) and connected to the row and column electrodes ( ) through vias ( ). Reflective pixel electrodes ( ) are provided. The driver circuits ( ) are distributed, preferably in a two dimensional array, so that each of the row and/or column electrodes is connected to a driver circuit ( ).

Active matrix liquid crystal display with local drivers

A method of constructing an active matrix pixel device uses a universal active matrix (UAM) ( ) comprising a matrix array of switching elements ( ) whose spacing defines a base pitch and a pixel array comprising a matrix array of pixel electrodes ( ) whose spacing defines a pixel pitch. The pixel pitch is greater than the base pitch. A large proportion of the construction process can be carried out before the customisation of the device. Using a common UAM ( ) enables a reduction in the time between the customer ordering the device and the completion time. The cost of meeting customer specific requirements for the fabrication of active matrix pixel devices is thus reduced.

Display having universal active matrix

The invention provides a method of manufacturing an electronic device including a vertical thin film transistor. A layer ( ) of semiconductor material is provided over an insulated gate electrode ( ). A negative resist ( ) is used to define source and drain electrodes ( ) which extend over the insulating layer ( ) up to the step formed therein adjacent an edge ( A) of the gate electrode ( ).

Electronic devices comprising thin film transistors

A method of producing a top gate thin-film transistor comprises the steps of forming doped silicon source and drain regions ( ) on an insulating substrate ( ) and subjecting the face of the substrate ( ) on which the source and drain regions ( ) are formed to plasma treatment to form a doped surface layer. An amorphous silicon layer ( ) is formed on the doped surface layer over at least the spacing between the source and drain regions ( ) and an insulated gate structure ( ) is formed over the amorphous silicon layer ( ). Laser annealing of areas of the amorphous silicon layer not shielded by the gate conductor is carried out to form polysilicon portions ( ) having the impurities diffused therein. In the method of the invention, doped silicon source and drain regions underlie the silicon layer to be crystallized using the laser annealing process. It has been found that the laser annealing process can then result in crystallization of the full thickness of the amorphous silicon layer. This results from the similar thermal properties of the doped source and drain regions and the silicon layer defining the main body of the transistor.

Method of producing a top-gate thin film transistor

A memory device includes an array of memory elements overlying a plurality of driver cells. Vias through an insulating layer connect the driver cells to the memory elements. The vias are distributed over the area of the array to connect the individual driver cells to the respective row and and/or column conductors of the memory array.

Memory circuit with memory elements overlying driver cells

Short channel thin film transistors suffer from unacceptably high leakage currents. The invention provides an electronic device including a thin film transistor in which the length ( ) of the channel of the transistor is 1 &mgr;m or less, and the mobility of the semiconductor material in the channel is less than 0.2 cm /Vs. The selection of a low mobility semiconductor material results in acceptable off-current characteristics and its effect on the switching speed of the device is compensated for by the short channel length ( ) of the device.

Electronic device including a thin film transistor

An active matrix electroluminescent display device ( ) comprises an array of display pixels ( ) arranged in rows ( ) and columns ( ). Each pixel ( ) comprises a current-driven electroluminescent display element ( ). Each row ( ) of pixels ( ) shares a common line ( ), currents through the display elements ( ) of a row ( ) of pixels passing along the common line ( ). The width of each common line ( ) tapers from one end ( ) to the other ( ), the common line ( ) being coupled to row driver circuitry at the wider end ( ). The resistance of the common lines is thus reduced at the end of the common line near to the row driver circuitry, where the current flowing is derived from all pixels within the row. The invention thereby reduces voltage drops along the common line, which contribute to cross-talk between pixels within a row.

Active matrix electroluminescent display device

An active matrix electroluminescent (EL) display device has an array of pixels ( ) on a substrate ( ) each comprising an EL display element ( ) and a driving device ( ) controlling drive current therethrough in a drive period based on a data signal applied in a preceding address period, and a drive circuit ( ) connected to the pixels via sets of address conductors ( ) for selecting the rows of pixels and supplying data signals to each selected row of pixels in a respective row address period. The data signals are provided by drive ICs ( ). To reduce the number of ICs required, a multiplexing circuit ( ) is integrated with the pixel array on the substrate ( ) and connected between the drive IC outputs ( ) and one set of address conductors ( ) and is operable to apply data signals from an individual drive IC output to a respective associated plurality of address conductors in sequence in a row address period. The display elements of a selected row of pixels are prevented from operating in the row address period to avoid unwanted cross-talk effects. Row selection signals may similarly be supplied by a multiplexing circuit ( ) integrated on the substrate.

A thin film capacitor is provided with a thin film protection element to protect the capacitor from damage that can result due to the occurrence of an electrostatic discharge event. The thin film capacitor includes two conductive film portions forming capacitor plates and a dielectric film forming the capacitor dielectric. The protection element may take the form of a thin film diode or a series of thin film diodes connected electrically in parallel with the thin film capacitor. The whole device can be fabricated using a stoichiometric silicon nitride layer to produce the capacitor dielectric and a non-stoichiometric silicon rich silicon nitride layer to provide the diode semiconductor material. One diode is formed by one capacitor plate, the semiconductor layer and an upper diode contact. In an alternative construction the protection element takes the form of a narrow gap defined by one conductive film portion electrically connected to one capacitor plate and another conductive film portion electrically connected to the other capacitor plate. During an electrostatic discharge event charge is able to cross the narrow gap rather than pass through the capacitor dielectric material.

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Haywards Heath, United Kingdom

Stephen J Battersby