Abstract: An optical reproducing apparatus according to the present invention includes a land/groove switching circuit for alternately switching reproduction of a record mark on a groove portion and a land portion. This allows a tracking operation to be carried out continuously at a connection point to a subsequent track in the recording direction without a laser beam from an optical pickup passing through an end of a spiral track. A recording medium according to the present invention includes a recording track formed of a groove portion and a land portion, and a record mark used for switching a tracking operation so that a light beam emitted from the optical pickup should be irradiated alternately on the groove portion and the land portion. When the record mark is detected, a track jump operation is carried out, and information is reproduced from the groove portion and the land portion alternately.

Abstract: An optical recording method according to the invention is provided such, that when an optical pickup (2) is moved over an optical disk (1), the optical pickup (2) being positioned onto the target track location, record marks are recorded on the optical disk (1) by a light beam irradiated onto the optical disk (1) through the optical pickup (2). An irradiation position of the light beam is offset during recording by a predetermined amount to a track at the recording direction side relative to the target track location, and a record mark is formed on a target track by the offset light beam.

Abstract: A recording and reproducing apparatus according to the invention has: at least a pair of rotary heads having different azimuth angles; a run controller for controlling the run of the magnetic tape; and a recording timing controller for controlling so that the recording by the rotary heads is performed at the first period when digital data having a first data rate is inputted, wherein the digital data is recorded on the magnetic tape at a recording timing. The recording and reproducing apparatus also has a memory for storing the digital data which is supplied from the outside, a reader for reading the digital data stored in the memory, and a signal processor for executing a predetermined process to the digital data read from the memory.

Abstract: A video signal receiver receives a plurality of video channels simultaneously carrying, offset by a transmission interval, a single video program, selects one channel from which to obtain the program for display to a user, and achieves a pause function in the display of the transmitted video program by temporarily storing a segment of the video program equal to the length of the transmission interval and obtaining the remainder of the program at a later time from the same or another channel.

Abstract: A video signal receiver receives a plurality of video channels simultaneously carrying, offset by a transmission interval, a single video program, selects one channel from which to obtain the program for display to a user, and achieves a pause function in the display of the transmitted video program by temporarily storing a segment of the video program equal to the length of the transmission interval and obtaining the remainder of the program at a later time from the same or another channel.

Abstract: A video signal receiver receives a plurality of video channels simultaneously carrying, offset by a transmission interval, a single video program, selects one channel from which to obtain the program for display to a user, and achieves a pause function in the display of the transmitted video program by temporarily storing a segment of the video program equal to the length of the transmission interval and obtaining the remainder of the program at a later time from the same or another channel.

Abstract: A homogeneous membrane or an asymmetric membrane which is made of polyimide resin containing fluorine as a main component and has high separation and permeation properties, is used in a method of separating unsaturated hydrocarbon from a mixture of unsaturated and saturated hydrocarbon. The method includes the steps of contacting the mixture onto the membrane made of the polyimide resin having a repeating unit shown in the following formula as a main component, selectively permeating unsaturated hydrocarbon through the membrane, and separating unsaturated hydrocarbon from the mixture. The membrane satisfies the condition of a solubility coefficient ratio between unsaturated and saturated hydrocarbon.gtoreq.1.2 at 25.degree. C. and more than 50 Torr when the absorption of hydrocarbon to the polyimide resin is in equilibrium.

Abstract: A video signal receiver receives a plurality of video channels simultaneously carrying, offset by a transmission interval, a single video program, selects one channel from which to obtain the program for display to a user, and achieves a pause function in the display of the transmitted video program by temporarily storing a segment of the video program equal to the length of the transmission interval and obtaining the remainder of the program at a later time from the same or another channel.

Abstract: An exhibit explaining system to enable a plurality of visitors to receive an explanation of an exhibit at their own pace. Spectacle-type displays 51-1 to 51-10 are provided, the frequencies f1 to f10 of a carrier wave being set to be different from each other. Image generating devices 61-1 to 61-10 are provided to correspond to the spectacle-type displays 51-1 to 51-10. When operating explanation request button 52-1 of the spectacle-type display 51-1, a VTR 76-1 of the image generating device 61-1 with the corresponding channel is reproduced, which is output from a transmitter-receiver circuit 72-1 to the spectacle-type display 51-1 through an antenna 71-1 on a radio wave. In the spectacle-type display 51-1, this radio wave is demodulated to observe an image on an LCD thereof.

Abstract: A gas separating composite membrane comprising two types of polyimide resin layers having different molecular structures and each having solubility in an organic solvent different from each other, the two layers being laminated being substantially independent or via a mixed layer, the first polyimide resin layer comprising a porous polyimide supporting membrane having a nitrogen gas permeation flux density at 25.degree. C. of at least 2 Nm.sup.3 /m.sup.2 /h/atm., and the second polyimide resin layer, which contributes to a gas separating performance comprising a fluorine-containing polyimide thin film containing at least three fluorine atoms in a repeating molecular structure unit which constructs the second polyimide resin layer has a very high gas permeation flux density while maintaining a high gas permeability, excels in heat resistance and chemical resistance, and satisfies a practical use in terms of cost.

Abstract: Time-based compressed data representing a program is supplied from a local conditional access circuit to two recording signal processing circuits which supply the data to be recorded simultaneously in time-compressed form by a digital VTR and an HDD (hard disc drive). The HDD need only store enough data to allow the digital VTR to record the entire program and to synchronize the output of the VTR with the output of the HDD. Once the program has been recorded on the VTR, it is reproduced therefrom concurrently with the portion of the program reproduced by the HDD and, once synchronization therebetween is reached, the VTR-reproduced data replaces the HDD-reproduced data. The reproduced data is supplied to an MPEG decoder circuit to be output as a reconstructed program for immediate display.

Abstract: This invention relates to a method of removing dissolved gas from liquid, which comprises bringing the liquid containing the gas dissolved therein into contact with a membrane, thereby causing the dissolved gas to selectively permeate the membrane. The membrane is a permselective, composite membrane composed of a porous support and a nonporous, active membrane of a synthetic resin formed on the porous support, or is a permeable membrane having such characteristics that the nitrogen gas permeation rate at 30.degree. C. is in the range from 7.times.10.sup.-4 to 2.times.10.sup.2 Nm.sup.3 m.sup.2 .multidot.h.multidot.atom and that the amount of permeated steam is 100 g/m.sup.2 .multidot.h or less when 20.degree. C. water is supplied to the membrane under atmospheric pressure while maintaining the pressure on its permeate side at 40 mmHg.

Abstract: A process for separating methane from a gaseous mixture containing methane and carbon dioxide by concentration is disclosed, which comprises contacting said gaseous mixture with a membrane comprising a film of a polyimide resin having a repeating unit represented by formula (I): ##STR1## wherein R.sup.1 represents a divalent aromatic, alicyclic or aliphatic hydrocarbon group, or a divalent organic group composed of these hydrocarbon groups linked via a divalent organic linking group. The membrane exhibits excellent selective permeability to carbon dioxide, enabling efficient and stable separation of methane.