Abstract: A card is composed of a reversible thermosensitive recording portion capable of recording information therein, and an irreversible recording portion capable of recording information therein. An information recording method uses the card in which an numerical information is recorded in the reversible thermosensitive recording portion, and an information which has substantially the same contents as those of the numerical information recorded in the reversible thermosensitive recording portion is recorded in the irreversible recording portion for preventing improper alternation of the numerical information recorded in the reversible thermosensitive recording portion. The numerical information recorded in the reversible thermosensitive recording portion and the information recorded in the irreversible recording portion are recognized by an optical device.

Abstract: An image recording method of recording information in and erasing recorded information from a display medium which contains a reversible thermosensitive recording material capable of writing information therein and erasing recorded information therefrom by the application of heat thereto, by use of a heat application member with a flat portion by bringing the flat portion into contact with the display medium provided on a supporting base, at least one of the display medium or the flat portion of the heat application member having an elastically deformable portion through which one of the display medium or the flat portion of the heat application member performs elastic deformation and the display medium is capable of coming into close contact with the heat application member.

Abstract: A reversible thermosensitive recording medium includes a reversible thermosensitive recording layer which is composed of a matrix resin and an organic low-molecular material which is dispersed in the matrix resin, the transparency of the reversible thermosensitive recording layer being reversibly changeable depending upon the temperature of the reversible thermosensitive recording layer, wherein the reversible thermosensitive recording layer has a softening initiation temperature T.sub.A, the organic low-molecular-weight material has a higher crystallization temperature T.sub.B1 which is 80.degree. C. or more and a lower crystallization temperature T.sub.B2, the softening initiation temperature T.sub.A is between the higher crystallization temperature T.sub.B1 and the lower crystallization temperature T.sub.B2, and the higher crystallization temperature T.sub.B1 and the lower crystallization temperature T.sub.B2 satisfies the relationship of T.sub.B1 -T.sub.B2 .gtoreq.40.degree. C.

Abstract: A method of compensating for the distortion in a recording layer of a reversible thermosensitive recording medium, for which transparency of the recording layer is changeable, depending upon the temperature thereof, and the recording layer is capable of forming images and erasing the images reversibly. The distortion in the recording layer is caused by the repeated image formation by image formation means and/or image erasure by image erasing means. In this method, stress is applied to the recording layer before and/or after image formation by the movement of the recording medium relative to the image formation means, in a direction different from the direction of the application of stress in the course of a previous image formation or image erasure. Instead of the stress, thermal energy can be employed for compensating for the distortion in the recording layer.

Abstract: A reversible thermosensitive recording material is composed of a support and a reversible thermosensitive recording layer formed thereon. The reversible thermosensitive recording layer is composed of a matrix resin, such as polyvinyl chloride or vinyl chloride copolymer, and an organic low-molecular-weight material dispersed in the form of finely-divided particles in the matrix resin, with the weight percentage Y of the vinyl chloride repeat in the matrix resin and the average polymerization degree X of the matrix resin satisfying the relationship:-0.68 log X+3.794.ltoreq.log Y.ltoreq.-0.215 log X+2.66.

Abstract: A reversible thermosensitive recording material composed of a support, an undercoat layer formed on the support, and a reversible thermosensitive recording layer formed on the undercoat layer, capable of reversibly assuming a transparent state and a white opaque state depending on the temperature thereof, the undercoat layer having at least one colored portion and at least one light reflecting portion.

Abstract: A waveform equalization method whereby a transversal filter having 5 or more tapes is included, and a difference signal output, which is obtained when an isolated impulse response waveform of a digital modulated signal is inputted to the above described filter and the output of the filter is inputted to an adder, is allowed to have intersymbol interference at .+-.T/2 with respect to the central axis time and has zero outputs at .+-.nT/2 (where n.gtoreq.2 and n is an integer).

Abstract: A device for decoding coded digital signals for every symbol consisting of a plurality of binary signals comprises first circuit for generating a first reliability for every binary signal; hard decided from the received or reproduced signal, in the symbol and second circuit for generating a second reliability for every symbol consisting of n binary signals on the basis of the first reliability, whereby decoding processing e.g. soft decision decoding is effected for every signal, depending on the second reliability.