Abstract: A magnetic recording medium comprises a nonmagnetic substrate and at least one ferromagnetic metal layer applied thereon and a protective layer formed on this metal layer and consisting of a compound which consists of an unfluorinated or partially fluorinated alkyl radical and a disulfide, hydroxyl or keto group.

Abstract: Moving laser beams from useful tracks to alternative positions in devices in which information is stored optically or magneto-optically. This results in higher signal-to-noise ratios.

Abstract: Polymethine dyes suitable for use in an optical recording medium have the formula ##STR1## where p is 0 or 1,Z is nitrogen, oxygen, sulfur, isopropylidene, cyclohexylidene or the radical --CH.dbd.CH--,Q is a radical of the formula ##STR2## where R.sup.2 is hydrogen, chlorine, bromine or C.sub.1 -C.sub.6 -alkyl, L is C.sub.1 -C.sub.12 -alkylene, or a single bondR.sup.1 is hydrogen, substituted or unsubstituted C.sub.1 -C.sub.20 -alkyl, substituted or unsubstituted C.sub.5 -C.sub.7 -cycloalkyl or substituted or unsubstituted phenyl,X.sup..crclbar. is an anion, and the rings A may each be substituted or benzofused.

Abstract: Binary azulenesquaric acid dyes of the formula ##STR1## where X is a bridging member, Y is hydrogen, cyano or formula CO--OR.sup.5, CO--NHR.sup.5, OR.sup.5, O--CO--OR.sup.5, NH--CO--R.sup.5, NH--CO--OR.sup.5 or NH--SO.sub.2 --R.sup.5, where R.sup.5 is hydrogen, C.sub.1 -C.sub.12 -alkyl, C.sub.2 -C.sub.12 -alkenyl, C.sub.5 -C.sub.7 -cycloalkyl or unsubstituted or substituted phenyl, L.sup.1 and L.sup.2 are each, independently of one another, a chemical bond or unsubstituted or substituted C.sub.1 -C.sub.12 -alkylene and R.sup.1, R.sup.2, R.sup.3, R.sup.4, Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 are each, independently of one another, hydrogen or unsubstituted or substituted C.sub.1 -C.sub.12 -alkyl, their intermediates and an optical recording medium containing the novel dyes are described.

Abstract: An optical recording medium consists essentially of a base material and a light-absorbing layer which contains a thermoplastic binder and at least one dye, wherein the thermoplastic binder is a polycyclic hydrocarbon which has a glass transition temperature Tg of greater than 150.degree. C. and is soluble to more than 3% by weight in an aliphatic or aromatic hydrocarbon.

Abstract: Amido-containing azulene-aquaric acid dyes of the formula ##STR1## where L is C.sub.1 -C.sub.12 -alkylene which may be substituted by phenyl,R.sup.1 and R.sup.2 are each independently of the other hydrogen, substituted or unsubstituted C.sub.1 -C.sub.20 -alkyl, C.sub.5 -C.sub.7 -cycloalkyl, substituted or unsubstituted phenyl, 2,2,6,6-tetramethylpiperidin-4-yl or cyclohexylaminocarbonyl andR.sup.3, R.sup.4, R.sup.5 and R.sup.6 are each independently of the others hydrogen or substituted or unsubstituted C.sub.1 -C.sub.12 -alkyl,with the proviso that when R.sup.6 is hydrogen the positions of the substituents CH.sub.2 --L--CO--NR.sup.1 R.sup.2 and R.sup.5 on either or both azulene rings may also be interchanged with each other within an azulene ring are used in an optical recording medium.

Abstract: Methine dyes of the formula ##STR1## where R.sup.1, R.sup.2, R.sup.3, R.sup.4, X, Y and the rings A and B each have specific meanings, and methine dyes obtainable by reacting an organic mono- or polyisocyanate with such a methine dye of the abovementioned formal where only the radicals R.sup.1 and/and R.sup.4 have a group reacting with an organic mono- or polyisocyanate are useful in optical recording media.

Abstract: Azulenesquaric acid dyes of the formula ##STR1## where L is substituted or unsubstituted C.sub.1 -C.sub.12 - alkylene,R.sup.1 is C.sub.1 -C.sub.20 - alkyl, C.sub.5 -C.sub.7 - cycloalkyl or substituted or unsubstituted phenyl andR.sup.2, R.sup.3, and R.sup.5 are each independently of the others hydrogen or substituted or unsubstituted C.sub.1 -C.sub.12 -alkyl,with the proviso that when R.sup.5 is hydrogen the positions of the substituents CH.sub.2 --L--O--CO--NHR.sup.1 and R.sup.4 on an azulene ring may also be interchanged within a ring in either or both of the azulene rings, derived from azulene intermediates that contain urethane groups, are suitable for use in an optical recording medium.

Abstract: Azulenesquaric acid dyes of the formula ##STR1## where R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 each have specified meanings are prepared from azulene derivatives of the formula ##STR2## where R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 each have specified meanings as intermediates, and used in an optical recording medium.

Abstract: Quinoxalinepentamethine dyes of the formula ##STR1## where R.sup.1 is hydrogen, substituted or unsubstituted C.sub.1 -C.sub.22 -alkyl or substituted or unsubstituted C.sub.5 -C.sub.7 -cycloalkyl,R.sup.2 is hydrogen, chlorine, bromine or C.sub.1 -C.sub.6 -alkyl,Y is a radical of the formula --N.dbd.C(CH.sub.3)-- or --N(R.sup.1)--CO--, where R.sup.1 is as defined above,Z.sup.1 and Z.sup.2 are each hydrogen or together are unsubstituted or substituted C.sub.2 -C.sub.3 -alkylene,X.sup..crclbar. is an anion andthe rings A and B independently of each other may be substituted and/or benzofused and are useful in optical recording media.

Abstract: Azulenesquaric acid dyes of the formula ##STR1## where L is substituted or unsubstituted C.sub.1 -C.sub.12 -alkylene,R.sup.1 is C.sub.1 -C.sub.20 -alkyl, C.sub.5 -C.sub.7 -cycloalkyl or substituted or unsubstituted phenyl andR.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently of the others hydrogen or substituted or unsubstituted C.sub.1 -C.sub.12 -alkyl,with the proviso that when R.sup.5 is hydrogen the positions of the substituents CH.sub.2 --L--O--CO--NHR.sup.1 and R.sup.4 on an azulene ring may also be interchanged within a ring in either or both of the azulene rings, derived from azulene intermediates that contain urethane groups, are suitable for use in an optical recording medium.

Abstract: An optical recording medium comprises a support material and a light-absorbing layer consisting essentially of a soluble mixture of a thermoplastic binder and at least one dye, wherein the thermoplastic binder is a phenol-aldehyde resin having an average molecular weight of greater than 300 which is soluble in an alcohol having a boiling point of less than 200.degree. C.

Abstract: Naphtholactamsquaric acid dyes of the formula ##STR1## where R.sup.1 and R.sup.2 independently of one another are each unsubstituted or substituted C.sub.3 -C.sub.22 -alkyl, in which the alkyl chain may be interrupted by oxygen atoms, or are each unsubstituted or substituted C.sub.1 -C.sub.4 -aralkyl, unsubstituted or substituted C.sub.5 -C.sub.7 -cycloalkyl or unsubsituted or substituted phenyl, and the rings A, B, C and D are unsubstituted or substituted and/or benzofused, and optical recording materials consisting of a base and a layer which is sensitive to laser light and is composed of a thermoplastic or crosslinked polymer and one or more dyes (I).Because of the high light absorption of (I), the recording materials are very sensitive to light from the GaAlAs semiconductor laser. An excellent signal-to-noise ratio is obtained on reading the recordings.

Abstract: A tape guide system wherein a magnetic tape having different resistivities on its back and front travels in contact with guide elements, the members of these elements which are in contact with the tape being matched to the relevant face of the tape in respect of surface resistivity and/or of charge affinity. The members contacting the front of the magnetic tape accordingly consist of a conductive or low-insulation material and the members contacting the back of the tape consist of a high-insulation material. In alternative embodiments, the contact members can consist of a material of low conductivity, or of a plastic with an added conductive material. The novel guide system can be used in any type of high-speed magnetic tape transport mechanism. The invention also concerns the tape guide elements per se, and magnetic tape cassettes employing the tape guide system.

Abstract: In a tape cassette, particularly a video tape cassette, equalization of electrostatic charges between the two faces of the tape is effected by a connector element or connector elements electrically connecting at least one of two electrically conducting guide elements contacting the front of the tape and provided on the two sides, respectively, of the cassette with at least the associated one of two electrically conducting tape deflecting elements provided in the two respective front corners of the tape cassette. In this manner sticking of the tape to the deflecting elements due to electrostatic attraction therebetween and also the build-up of electrostatic charges along the tape path parallel to the front of the cassette housing due to the transporting of such charges from the deflecting elements as a result of the tape travel, are counteracted.

Abstract: An irreversible optical medium for storing information by local modification of the optical properties of a recording layer under the action of a light beam with an irradiance of from 0.05 to 10 nJ .mu.m.sup.2, essentially consisting of a substrate and, applied on this, a particulate recording layer from 0.01 to 10 .mu.m thick, wherein the recording layer consists of a three-dimensional arrangement of particles having a mean particle diameter of from 4 to 40 nm, and a process for its production.

Abstract: A method of changing video recordings with or without audio information on a single video recording/playback unit, comprising reading the originally recorded signals of a first of several tracks on a recording medium and re-recording said signals on the same first track or on a second track, as well as erasing the originally recorded signals, in order to vacate tracks for further new recordings, and devices for carrying out said method. The devices include recording/playback and erase head combinations, and a circuit for separating, changing and re-recording the video and/or audio signals.

Abstract: An erase head for erasing single tracks on multi-track magnetic recording tapes by means of a constant magnetic field applied in a direction perpendicular to the direction of tape travel, to avoid any asymmetrical residual magnetization with respect to the direction of a magnetizing field used for recording. A configuration of two pole pieces and two corresponding shields, spaced out from the pole pieces and generally coplanar with the end faces thereof, ensures that the magnetic field strength is relatively uniform in a region between the shields, and falls to a relatively low value outside this region.