Abstract: A light absorbing layer, and a window layer formed thereon constitutes a first conduction-type semiconductor layer. In a part of this first conduction-type semiconductor layer there is provided a second conduction-type region extending to the light absorbing layer through the window layer. A part of the window layer around the second conduction region is selectively removed. Consequently even when light intended to enter a light detecting region is incident outside of the light detecting region, most of the carriers generated there are recombined at a surface level of the light absorbing layer before diffusing in a depletion layer. This light detecting device therefor does not substantially detect sensitivity to light incident outside the light detecting region.

Abstract: This invention relates to a photodetector including a package having a window disposed in a light incident part, and a light detecting element installed in the package. The light detecting element includes a first region formed of a second conduction-type semiconductor and embedded in a first conduction-type semiconductor layer; a second region formed of second conduction-type semiconductor and embedded so as to be spaced from and to surround the first region; and a conductor layer provided both on at least one part of top surface of the first conduction-type semiconductor layer and on at least one part of top surface of the second region. The first region is surrounded by a second conduction-type second region. On the surface of the semiconductor crystal layer, an electrode is formed on the first region, and a reflection preventing layer is formed on that part of the first region inside the electrode, and a device protecting film is formed on that part of the first region outside the electrode.

Abstract: A region of a second conductivity type is selectively formed in a portion of a semiconductive layer of a first conductivity type to form a pn junction area which serves as a photo-sensing region. A metal film is formed on a surface of the semiconductive layer of the first conductivity type to surround the photo-sensing region. When light to be directed to the photo-sensing region spreads outside the photo-sensing region, the light is reflected by the metal film provided on the surface of the semiconductive crystal layer around the photo-sensing region. Accordingly, the light does not reach the photo-sensing layer of the semiconductive crystal layer and the generation of undesired carriers is prevented.

Abstract: In a subscription television system, only a video signal for a specific program is scrambled in a television signal in accordance with a predetermined scrambling mode. A key signal, used for unscrambling the scrambled video signal, is generated in response to the scrambling mode. The key signal is transmitted after the scrambled program.

Abstract: A double-scanning non-interlace television receiver for receiving an interlace television signal having alternating odd and even fields of scan lines which are normally interlaced, as displayed, comprises a receiver circuit which receives the interlace television signal and generates received line signals representative of the scan lines of a field being received, a visual display apparatus, and a non-interlace converting circuit connected to the receiver circuit which generates an averaged line signal from two consecutive received line signals and serially supplies the averaged line signal and the consecutive received line signals to the visual display apparatus for display by the latter, with each averaged line signal being supplied and displayed between the respective received line signals.