Abstract: The plasma display apparatus has a noise filter circuit with a noise filter connected to an AC supply disposed at the back side of a plasma display panel. The plasma display apparatus also has a back cover composed of a magnetic metal material disposed at the back side of the plasma display panel to cover the noise filter circuit, wherein magnetic lines of force in a core, made of magnetic material and including the noise filter direct approximately identical to the in-plane direction of the back cover. The configuration can eliminate audible noises because the amount of leakage flux passing through the back cover is reduced.

Abstract: The plasma display apparatus disclosed comprises: a noise filter circuit, having noise filter (253), connected to an AC supply disposed at the back side of the plasma display panel; and a back cover (12) composed of a magnetic metal material disposed at the back side of the plasma display panel to cover the noise filter circuit, wherein magnetic lines of force in the core, made of magnetic material and consisting the noise filter (253), direct approximately identical to the in-plane direction of the back cover (12). The configuration can eliminate audible noises because the amount of leakage flux passing through the back cover is reduced.

Abstract: In a method of electrically testing an active matrix substrate having a plurality of semiconductor switching devices, a row group of a plurality of parallel conductors and a column group of a plurality of parallel conductors, a gate electrode of each of the semiconductor switching devices being connected to one of the conductors of the row group, and a source electrode of each of the semiconductor switching devices being connected to one of the conductors of the column group, there are provided the steps of short-circuiting the conductors of the row group at both ends thereof; short-circuiting the conductors of the column group at both ends thereof; applying a predetermined voltage between the row and column groups of the conductors; and measuring a current flowing from the row group to the column group of the conductors. Moreover, in determining whether the active matrix substrate is defective, there is also provided the step of determining whether the following formula is satisfied or not:I.sub.1 .ltoreq.n.

Abstract: In an electro-optical effect display apparatus, a number of pairs of two parallel and closely disposed scanning bus-lines (21-21, 21-21, . . . ) are disposed on a substrate with a predetermined interval therebetween, and a first electrode bus-line (25) is disposed between each other neighboring two pairs of the scanning bus-lines (21-21 and 21-21). Then respective storage capacitors (26) belonging to two display elements (24, 24), each other neighboring with respect to the first electrode bus-line (25), are connected commonly to the first electrode bus-line (25), thereby utilizing a single first electrode bus-line (25) commonly for two storage capacitors (26, 26) which are disposed substantially symmetrically to the first electrode bus-line (25); and thus, the number of bus-lines can be reduced, and consequently, the area of the display element increases.

Abstract: A method of production of active matrix display substrates using thin film transistors and more particularly to a method for production of substrates for liquid-crystal display use. The active matrix substrate using the thin film transistor is produced by the mask processes of smaller number. The process of the present invention can reduce the number of the masks, by one, of the active matrix substrate using the inverted staggered thin film transistor which requires the masks from five levels to six levels. Further improvements reduce the number of the masks to four levels from three levels, thus contributing greatly towards lower cost, improved yield.

Abstract: An optical switch usable for an optical circuit adapted to be operated by utilizing the electro-optical effect inherent therein. A pair of electrodes are arranged in spaced relation on an optical wave guide which is branched to branch optical wave guides and transmission of light beams is controlled by applying a certain voltage to the electrodes. Both the optical wave guide and the branch optical wave guides are made of electro-optical material. Specifically, the optical wave guides are constituted by a layer of PLZT ((Pb, La) (Zr, Ti) O.sub.3) based thin film which is formed by epitaxial growth on a base plate located on the C-plane of sapphire (.alpha.-alumina). The switch is effective for controlling the transmission of light beams.