Abstract: A data reproducing method in which abrupt sound transitions as the end of a recorded tape is reached are eliminated. A predetermined time period corresponding to the length of the tape is inputted, and a time instant earlier by a predetermined period of time than the end of the time period at which the end of the tape is encountered is calculated. While plural pieces of music are being reproduced in a specified order for recording on the tape, a sum of the total time from the start of reproduction is iteratively calculated. When the sum reaches the calculated period of time, the total output level is gradually reduced to zero.

Abstract: Method and system for overwriting binary data values in microscopic storage regions of a thin film ferrimagnetic layer without using external magnetic bias aiding the recording process. The ferrimagnetic layer is selected having a compensation temperature at least a few tens of degrees above room temperature. In recording data, any previously recorded data is erased to establish a known state and magnetic domains of reverse magnetic polarity are recorded when the known state differs from the binary data state by temporarily heating an area on the ferrimagnetic layer above the compensation temperature in the absence of any external aiding magnetic bias.

Abstract: An erasing device for a magnetic video recorder is disclosed which includes a means for reproducing a code signal and a video signal from a magnetic medium. The code signal is discriminated to decide whether the video signal is a field video signal or a frame video signal. When the video signal is discriminated to be the frame video signal, the erasing device erases the video signal over a broader range than when the video signal is discriminated to be a field video signal.

Abstract: An optical recording and reproducing apparatus for recording and reproducing data in an optical disk is disclosed. The optical disk has a plurality of erase test sectors in tracks, in one of which the accumulated number of tests together with test data is written. The data read from the erase test sector is compared with the recorded data to effect an erase function diagnosis. If data comparison shows an non-coincidence or the accumulated number of tests exceeds a predetermined value, a new erase test sector is used. The fatigue of the recording medium caused by a defect of the medium or reduced erasing efficiency due to an increased number of erasures of the recording medium is checked by controlling the accumulated number, completely separately from the fault of erase function of the apparatus, thus improving the reliability of the erase function self-diagnosis.

Abstract: A signal recording and reproducing device for use with an opto-magnetic disk having a number of concentric recording tracks. An optical head sweeps a given track at least twice during a time interval equal to a predetermined reproduction time for the track. Erasure signals and recording signals are supplied to the optical head during the first time sweeping and the second time sweeping, respectively, in order to effect signal erasure and recording. At the time of switching from the first time sweeping to the second time sweeping, the address data indicating the end point written on the terminal portion of the previously recorded signal area are sensed, and the recording is effected from the thus sensed recording end point.

Abstract: Methods for directly over-writing the binary data value of a bit of digital data, stored in a particular one of a multiplicity of microscopic storage regions of a thin-film magneto-optic recording layer, first locate the storage region and non-destructively read the stored data value therefrom, and then compare the recovered value against the data value of an information bit to be stored in the same storage region. If the comparison indicates that no change in the stored data value is required, then the process proceeds to read and compare the next bit of data, from the next associated storage location. If the comparison indicates that a reversal of the magnetic moment of that region is required to store the new data value, a source of energy is energized to heat the particular storage region of a sufficiently high temperature that the self-demagnetization field of the recording layer material inverts the net magnetic moment of that region.

Abstract: Targets (14) mounted on objects (12) for detection by a magnetic type theft detection system are deactivated in a target deactivator (26,64) which has magnet assembly (40,72) made up of spaced apart magnets with alternately opposed poles extending in a plane and guide walls (36, 38, 68, 70) extending perpendicular to the plane. Targets are reactivated by a reactivator (46, 76) having a magnet (52, 80) mounted thereon and arranged to be slid along the target.

Abstract: A floppy disk driving circuit comprises a memory circuit for storing a plurality of items of delay time of a pair of erase heads from the switching-ON and the switching-OFF of a read/write head for all the tracks of a floppy disk, a control circuit responsive to the memory circuit for controlling ON- and OFF-delay timing of the pair of erase heads based on the plurality of items of delay timing. The plurality of items of suitable timing are previously calculated in connection with the respective tracks of the disk and stored within the memory circuit.

Abstract: A quaternary saturated digital magnetic recording system for enhancing information entropy provides an effective bit density increase of 100% or more over the MFM code. In the simplest implementation, groups of two input binary bits are mapped into one data cell, preferably into four combinations of long or short breaks and positive or negative polarity, with the break optionally centralized within the data cell for self-clocking. A system for reproducing the recorded information provides a peak detector, responsive to the recorded signal, coupled to pulse polarity and break width detector circuitry, with an internally synchronized clock, for remapping the recorded data into binary format.

Abstract: An energy efficient means for selectively pre-magnetizing a magnetic recording medium of a thermoremanent magnetographic printer is disclosed. It consists of a pair of axially aligned, elongated two-pole, substantially cylindrical permanent magnets separated by a narrow gap and oriented so that like poles of adjacent magnets confront one another across the gap. The recording medium moves between the magnets in a direction perpendicular to the magnets. The elongated magnets produce magnetic field components that are additive in the surface of the recording medium and that cancel in the direction normal to the recording medium's surface. The magnetizing field of the magnets may be turned off for latent image retention by rotating the magnets about 90 degrees.

Abstract: A floppy disc device having a read/write head, a pair of erase heads and a delay mechanism for delaying the operation of the erase heads with respect to the operation of the read/write head is provided. The pair of erase heads is provided in the downstream direction of the read/write head with respect to the movement of a floppy disc recording medium, thereby avoiding cross coupling between the read/write and erase heads. In accordance with one aspect of the present invention, the delay mechanism delays energization and deenergization of the erase heads with respect to those of the read/write head. Another aspect of the present invention is that the delay mechanism delays energization of the erase heads with respect to energization of the read/write head for some of a plurality of concentic recording tracks. The present invention made it possible to carry out proper tunnel-erasing without under-erasing and/or over-erasing.

Abstract: A magnetizable anisotropic material layer having a pattern of regions of differently aligned material has an initial pattern of remanent magnetization, when manufactured by applying directional magnetic fields. This pattern is not easily restored, and is generally impossible to restore, after demagnetization or remagnetization. By preserving the residual pattern and selectively removing it in use by the application of a magnetic field, a security feature is provided. A secure document system using such a feature is provided.

Abstract: A magnetic recording method and apparatus is disclosed. The magnetic recording method includes forming a magnetic latent image on a recording medium with a scanning recording head so that the magnetic latent image has substantially the same width as that of the recording head, recording the magnetic latent image again with the recording head shifted from its first position by a predetermined width to cause overlapping to form a magnetic latent image with a predetermined width narrower than the width of the recording head and making the narrowed magnetic latent image visible.

Abstract: A copying machine which includes a thin flexible sheet with a layer of chromium dioxide, a lamp for shining light at the sheet and a document to be copied to form a magnetic image on the chromium dioxide layer, a drum having a layer of nickel cobalt, a transfer head for pressing the sheet against the drum while applying an anhysteretic magnetic field to them to transfer the magnetic image to the nickel cobalt, an applicator for applying toner to the drum, and a mechanism for pressing sheets of paper against the drum to transfer the toner to the paper. The nickel cobalt layer has a lower coercivity but higher remanence than the chromium dioxide, so that the magnetic field on the drum can be of greater strength than the original magnetic field on the chromium dioxide layer. Also, the nickel cobalt layer on the drum is a smooth continuous metallic layer which can perform better printing than the nonmetallic chromium dioxide particles which are held in a resinous binder on the flexible sheet.

Abstract: Process and apparatus for creating a magnetic latent image capable of being rendered visible with magnetic toner without image deletion. An area of interest on a magnetizable member is recorded with a first substantially uniform spatial pattern of magnetic transitions having a transition wavelength .lambda..sub.1 capable of retaining magnetic toner on the magnetizable member and effective to substantially completely cover the area of interest upon development with magnetic toner. A second spatial pattern of magnetic transitions having a transition wavelength .lambda..sub.2 is then recorded in the area of interest in one of imagewise and background configuration; the second spatial pattern of magnetic transitions having a transition wavelength .lambda..sub.2 incapable of retaining said magnetic toner on said magnetizable member, wherein .lambda..sub.1 is greater than .lambda..sub.