Abstract: A novel structure is provided to improve the operating stability of thioaluminate based phosphors used in ac thick film dielectric electroluminescent displays. The novel structure comprises a rare earth activated alkaline earth thioaluminate phosphor thin film layer and a silicon oxynitride layer provided directly adjacent the top and/or bottom of the phosphor thin film layer, wherein said silicon oxynitride layer comprises a composition of Si3NxOyHz where 2?x?4, 0<y?2 and 0?z?1. The invention is particularly applicable to phosphors used in electroluminescent displays that employ thick dielectric layers subject to high processing temperatures to form and activate the phosphor films.

Abstract: A thin film phosphor for an electroluminescent device, the phosphor being selected from the group consisting of thioaluminates, thiogallates and thioindates having at least one cation selected from elements of Groups IIA and IIB of the Periodic Table of Elements. The phosphor being activated by a rare earth metal and containing oxygen as a partial substitute for a portion of the sulphur in the crystal lattice of the thiogallate, thioindate or thioaluminate. The phosphor is a single phase homogeneous compound and provides improved luminance stability. An electroluminescent device comprising the thin film phosphor is also described and methods of making the phosphor of the invention.

Abstract: The invention relates to improving the stability of the lower electrodes in an electroluminescent display employing a thick film dielectric. The invention is an encapsulated electrode comprising an electrode of an electrically conductive metallic film. A layer of encapsulating material is provided on an upper and/or lower surface of the electrode layer. The encapsulating material reduces the risk of the electrode from becoming discontinuous and losing its electrical conductivity.

Abstract: A phosphor and a method of deposition. The phosphor comprises a composition of the formula M?aBa1-aM?2M??4?; RE, where M? is at least one element selected from magnesium and calcium, M? is at least one element selected from aluminum, gallium and indium, M?? is at least one element selected from sulphur, selenium and tellurium, RE is at least one rare earth element, especially europium or cerium, and 0<a<1. Deposition is preferably by dual source electron beam deposition. The phosphor may be annealed. The phosphor provides a high luminosity blue emission that does not require an optical filter to achieve acceptable color coordinates for the blue sub-pixel element for a full color thin film or thick film electroluminescent display. The blue sub-pixel pixel performance meets the luminosity and color temperature specifications for current generation cathode ray tube displays.

Abstract: The present invention is a low firing temperature, composite thick film dielectric layer for an electroluminescent display. The composite thick film dielectric layer comprises; (a) a lower zone layer of a thick film composition comprising; one or more of lead magnesium niobate (PMN), lead magnesium niobate-titanate (PMN-PT), lead titanate, barium titanate and lead oxide; and a glass frit composition comprising lead oxide, boron oxide and silicon dioxide; (b) an upper zone comprising at least one layer of lead zirconate titanate (PZT) and/or barium titanate; and (c) an intermediate composite zone comprising a composite of (a) and (b).

Abstract: A method of deposition of a phosphor in a single-source sputtering process, in which the phosphor is selected from the group consisting of ternary, quaternary or higher thioaluminate, thiogallate and thioindate phosphors, and composites thereof, synthesized with cations selected from Groups IIA and IIB of the Periodic Table of Elements. The phosphor is of a pre-determined composition of elements. The method comprising sputtering in a hydrogen sulphide atmosphere from a single source composition so as to deposit a composition on a substrate. The composition of the targets of the single source has a relative increase in concentration of elements of the phosphor that have a lower atomic weight compared to other elements in said phosphor. The relative increase is controlled such that deposition of the pre-determined composition is effected on the substrate. Preferred phosphors are barium thioaluminate (BaAl2S4:Eu), and barium magnesium thioaluminates.

Abstract: The invention relates to a laser ablation method for patterning thin film layers for thick dielectric electroluminescent displays without substantial ablation of or damage to any other layers. Typically, the thin film layers are phosphor layers.

Abstract: The invention is a novel sputter deposition process for thin film phosphors that provide high luminance and colors required for TV applications.

Abstract: A circuit and method of driving a display panel requiring gray scale control wherein the voltage applied to a row of pixels is equal to the sum of voltages of opposite sign with respect to ground applied respectively to the row electrode and column electrodes whose intersection with the row defines the pixels. Gray scale is realized through modulation of the voltage applied to the column electrodes. Typically for video application, 256 individual gray levels are required corresponding to luminance levels ranging from zero (no emissive luminance) to full luminance. The required luminance for each gray level is not a linear function of the gray level number but rather corresponds to an approximate quadratic function of this number. The present invention facilitates generation of luminance values for each gray level that approximates this functional dependence ( i.e. Gamma corrected) with a non-linear voltage ramp terminated by a digital clock having 256 (8 bit) resolution.

Abstract: A thin film phosphor for an electroluminescent device, the phosphor being a compound of the formula MgxCa1−xAl2S4:M, where the value of x is in the range 0<x<0.3 and M is a rare earth activator. A method for the preparation of the phosphor on a substrate is also disclosed.

Abstract: A thin film phosphor for an electroluminescent device, in which the phosphor is selected from the group consisting of thioaluminates, thiogallates and thioindates having at least one cation selected from elements of Groups IIA and IIB of the Periodic Table of Elements. The phosphor is activated by a rare earth metal and co-activated with gadolinium. The phosphor provides improved luminance. An electroluminescent device comprising the thin film phosphor on a substrate is also described. Further aspects provide an electroluminescent device in which the thin film phosphor is adjacent to a thin film of zinc sulphide, preferably sandwiched between thin films of zinc sulphide.

Abstract: The performance and stability of thick film electroluminescent displays is enhanced by a non-porous layer inserted between the thick film dielectric layer and thin film phosphor structures in these displays. The inserted layer facilitates increased luminance, increased energy efficiency and improved operating stability.

Abstract: A method of deposition of a phosphor in a single-source sputtering process, in which the phosphor is selected from the group consisting of ternary, quaternary or higher thioaluminate, thiogallate and thioindate phosphors, and composites thereof, synthesized with cations selected from Groups IIA and IIB of the Periodic Table of Elements. The phosphor is of a pre-determined composition of elements. The method comprising sputtering in a hydrogen sulphide atmosphere from a single source composition so as to deposit a composition on a substrate. The composition of the targets of the single source has a relative increase in concentration of elements of the phosphor that have a lower atomic weight compared to other elements in said phosphor. The relative increase is controlled such that deposition of the pre-determined composition is effected on the substrate. Preferred phosphors are barium thioaluminate (BaAl2S4:Eu), and barium magnesium thioaluminates.

Abstract: An electroluminescent display and driving method is provided wherein the rows of pixels are divided into sub-pixel sets and several different sets of sub-pixels are then addressed from within a larger superset of adjacent sub-pixels. The image data for the addressed sub-pixels is averaged with that for adjacent sub-pixels and is applied to the reduced number of larger sub-pixels in sequence. Consequently, for a given sequence of input frame data sets the time average over one frame for a portion of the sub-pixels at any location of the panel is substantially the same as that for a conventionally addressed sub-pixel in a prior art panel.

Abstract: A driving circuit for powering an electroluminescent display using energy recovered from a varying panel capacitance of the display. The driving circuit comprises a source of electrical energy; and a resonant circuit using the panel capacitance for receiving the electrical energy and in response generating a sinusoidal voltage to power the display at a resonance frequency which is substantially synchronized to a scanning frequency of the display. The resonant circuit uses a step down transformer to reduce the effective panel capacitance of the display in order to reduce its effect on the resonance frequency.

Abstract: A method of deposition of a phosphor in a single-source sputtering process, in which the phosphor is selected from the group consisting of ternary, quaternary or higher thioaluminate, thiogallate and thioindate phosphors, and composites thereof, synthesized with cations selected from Groups IIA and IIB of the Periodic Table of Elements. The phosphor is of a pre-determined composition of elements. The method comprising sputtering in a hydrogen sulphide atmosphere from a single source composition so as to deposit a composition on a substrate. The composition of the targets of the single source has a relative increase in concentration of elements of the phosphor that have a lower atomic weight compared to other elements in said phosphor. The relative increase is controlled such that deposition of the predetermined composition is effected on the substrate. Preferred phosphors are barium thioaluminate (BaAl2S4:Eu), and barium magnesium thioaluminates.

Abstract: Improved circuitry for active matrix image arrays which, in one application reduces the number of source or gate lines for a given number of pixels, and in another application extends the dynamic range of the imaging array without reducing the number of source or gate lines. Each circuit includes multiple electrodes per pixel and multiple thin film transistors for switching charge from the pixel electrodes to the data line.

Abstract: A high resolution flat panel for radiation imaging includes an array of pixels arranged in rows and columns. Gate lines interconnect the pixels of the rows while source lines interconnect the pixels of the columns. Gate driver circuits provide gate pulses to the gate lines in succession in response to input from a control circuit to select the pixels on a row-by-row basis. The source lines lead to charge amplifiers for sensing the signal charges stored by the pixels when the pixels are selected. At least one pair of adjacent pixels in each row of the array shares a source line. Gating of the pairs of pixels in the rows that share a source line is controlled by control logic to ensure that signal charges stored by only one of those pixels is applied to a shared source line at a time. This allows the number of charge amplifiers in the flat panel to be reduced while maintaining high resolution.