Abstract: A method and an apparatus for recording and reproducing information for use with an optical disk apparatus in which a pit edge recording method is used. According to the pit edge recording method, the leading edge and the trailing edge of a hole pit or a record domain generated during a recording operation are dealt with as information. During the recording, the recording pulse width and the recording power are corrected, and during the reproduction, the variation in the edge position is corrected.

Abstract: Based on the fact that the recording track width depends on the width of a core at the trailing side relative to the moving direction of magnetic recording medium, narrower track recording and wider track erasing, or a two-mode recording operation either for high-density recording or normal-density recording are realized using a single magnetic head having a narrower core and a wider core opposing to each other through a gap by changing the moving direction of the magnetic recording medium relative to the magnetic head.

Abstract: For recording digital data on a magnetic recording medium, binary data signals and magnetic bias signals having a constant repetition rate are synchronized in terms of phase, are overlaid, and are subsequently supplied to a magnetic head. The phase-oriented synchronization thus occurs since the chronological spacings between two successive signal edges of the magnetic bias signals between two successive signal edges of the data signals given a plurality of magnetic bias signals are modified such that the directions of the signal edges of the data signals coincide with the directions of the corresponding signal edges of the magnetic bias signals. The sums of the components having a first binary value and a second binary value of the magnetic bias signals are identical. Preferably, the distances between two successive signal edges of each of two magnetic bias signals are respectively shortened by half between two edges of a data signal.

Abstract: The present muting control apparatus comprises a first circuit for indicating selection of the error signal relative to N-m (N and m are natural numbers satisfying N>m) data blocks of N data blocks reproduced by a first rotary head when all of the first m data blocks thereof have errors. The first circuit also indicates selection of the error signal relative to N-m data blocks of N data blocks reproduced by a second rotary head when at least one of the first m data blocks reproduced by the first rotary head has no error. The muting control circuit also comprises a second circuit for generating a muting control signal indicating whether to mute the reproduced audio signal, by using error signal which is indicated by the first circuit.

Abstract: In a magnetic disk unit for recording/reproducing data onto/from a disc by means of a magnetic head on the basis of a seek command and a recording/reproducing command received from a host processor, the execution of the data reproducing command for the disk is started upon detection of a state that the magnetic head has sought on a desired track to an extent that the centering state is still unstable but the data can be reproduced, and the execution of the data recording command is started upon detection of a condition that the magnetic head has reached the stable centering state on the desired track after the detection of the reproducible state.

Abstract: A reproducing apparatus for reproducing main information from a tape-shaped record bearing medium on which many recording tracks are formed in parallel and additional information recorded along with the main information in a predetermined position within each of a plurality of areas extending in parallel in the longitudinal direction of the medium is arranged to have one operation mode in which the main information and the additional information are reproduced from one of the plurality of areas and another operation mode in which the additional information is solely reproduced from two or more of the plurality of areas.

Abstract: When a recording track on a magnetic disc (10) is erased, a first erasing signal f.sub.1 with an upper limit of frequency (10 MHz) in a recording signal band is supplied through a magnetic head 14 over a period T.sub.1. Since the erasing signal f.sub.1 is attenuated and vibrated in a period T.sub.12, the residual component is minimized. A second erasing signal f.sub.2 with an upper limit of frequency (20 MHz) which is outside of the recording signal band and can be recording and reproduced by the magnetic head is supplied through the magnetic head 14 over a period T.sub.2, so that the residual component of the erasing signal f.sub.1 is erased. Since the erasing signal f.sub.2 is attenuated and vibrated in a period T.sub.22, the residual component is minimized.

Abstract: The invention in one embodiment thereof employs separate and respective heads for disparate signal frequency bands. One head is kept in intimate contact with the recording medium to maximize the response to the higher frequency signal band; and the other head is vibrated relative to the surface of the recording medium, thereby to augment(d.phi./dt)and to improve the playback response to the lower frequency signal band. Since the two heads cannot reside physically at the same location, a suitable delay device is employed to bring the signals from the two heads into proper timed relationship, the outputs of the two heads being appropriately band-passed to reconstruct a complex signal composed of the two signal bands.

Abstract: In an apparatus for automatically supplying and selectively reproducing a plurality of cassettes, the error rate for each cassette and for each reproduction is automatically generated and stored in a separate area of a memory and, when the error rate exceeds a threshold rate, the deteriorating cassettes are automatically dubbed onto blank cassettes to ensure that deterioration of each tape or other record medium never exceeds a predetermined amount. In addition, the operator may independently cause any cassette to be dubbed when he deems the image produced therefrom to be too highly degraded regardless of the error rate of the signal recorded therein.

Abstract: In a waveform equalizer of the present invention, first and second Hilbert-transform signals are formed from a parallel-reproduced signal, and a desired signal is obtained from these signals by an operational amplifier. The waveform equalizer includes a reflecting section having a plurality of resistors, and a switching section for selecting one of the resistors in accordance with a control signal. Therefore, the waveform equalizer can process a plurality of reproduced signals which have different ratios of the longitudinal signal component to the perpendicular signal component without being affected by inphase noise.

Abstract: A digital signal reproducing apparatus in which the frequency of a basic clock signal generated from a clock generator having a fixed oscillation frequency is divided to produce a clock signal used for processing a digital signal, and, when the transmission speed of the digital signal is changed, the frequency division ratio is also changed to produce a clock signal synchronous with the digital signal transmitted at the changed transmission speed.

Abstract: In a magnetic head drive apparatus of this invention, a coil of an erasing head is connected to a center point of the coils of a read/write head, and a drive current from a constant-current source is alternately supplied to both terminals of the coil of the read/write head, according to the polarity of the write data. When the read/write head is driven to write data in a magnetic recording medium, the erasing head and the read/write head are driven at an identical timing. In this case, the drive currents for the read/write head and the erasing head are supplied from a single-current source. For this reason, separate constant-current sources are not necessary for the read/write head and the erasing head.

Abstract: Holding means for securing a pair of eyeglasses to the wearer's head. A pair of flexible sheets each having a row of apertures provided thereon through which the opposite temple ends of the eyeglasses are extended to form a plurality of spaced apart folds engaging the wearer's head holding the eyeglasses thereto.

Abstract: A monitor display unit having a hologram dry plate, formed by coating a glass base plate with sensitive material, and installed in an instrument panel of a vehicle. On the hologram dry plate are multiply recorded light interference fringes of three-dimensional images of the vehicle seen from the front and the rear of the vehicle. Two image reproduction lamps for illuminating reproduction light toward the hologram dry plate are provided on the right front and the left front of the hologram dry plate. When one image reproduction lamp is lighted, one three-dimensional image is reproduced on the hologram dry plate. Light emission diodes are provided rearward of the hologram dry plate so as to correspond to the positions of lamps on the three-dimensional image. The light emission of the light emission diodes is recognized through the hologram dry plate.

Abstract: A pair of removable sunglasses which can be attached to conventional eyeglasses or spectacles. The sunglasses include a pair of lenses joined by a center section which functions as both a hinge and means for attaching the sunglasses to the bridge of the eyeglasses. They also include a pair of opposing side pieces attached to respective lenses by a hinge which are removably attachable to the bows of the eyeglasses.

Abstract: A tachistoscope system is presented in which separate images may be sent to the left and right hemispheres of the visual cortex. A subject-worn viewing system having electro-optical valves is used to cover the right and left visual fields of the subject and the valves are operable in response to control signals. These control signals also synchronize the inputs from 2 television cameras with the opening of the valves. An alternative embodiment employs lenses of different colors arranged to cover the right and left visual fields of the subject and means for displaying colored areas of output.