Abstract: A method for allocating and restoring a bit-stream when the code amount of the bit-stream, generated as a result of variable-length encoding with respect to macro blocks included in a segment, exceeds an allowable segment capacity. The excess bit amount is maintained at its maximum in a range where compatibility with a conventional standard definition video cassette recorder (SD-VCR) is guaranteed, to thereby improve the quality of a reproduced image.

Abstract: A head positioning system includes a feedforward operation controller which calculates a basic head position control signal to output to a head displacement providing device based upon the target track the head is to be moved to and the present head position at the time when a head positioning operation begins. Subsequently, a feedback corrected control signal for head positioning is calculated by a feedback operation controller using a detected signal indicating actual head position relative to the record disk. Until the results from the feedback operation controller are available, the basic head position control signal is utilized for the head positioning operation. This basic head position control signal is also used for controlling head positioning whenever an output from the feedback operation controller is not being provided.

Abstract: An apparatus for determining the position and/or orientation of a transducing head positioned on one side of and close to a rotating transparent-core magnetic storage disk. Light is introduced into the disk to establish total internal reflection therein. A detector disposed on the other side of the disk opposite the head detects the intensity of light on the interior region of the disk. The detected intensity is representative of the separation of the head from the disk.

Abstract: By merely using one reproducing head, an overwriting operation and an ATF operation can be performed, thereby reducing a crosstalk obstruction and modulation noises. Recording heads 7 and 8 having different azimuth angles and a reproducing head 9 having the same azimuth angle as that of the recording head 7 are provided for a drum 3. An (A) track constructed by a data region and an ATF pilot region is recorded to a magnetic tape 1 by the recording head 7. A (B) track constructed by a data region in which a single signal of a short wavelength is recorded and an ATF pilot region is recorded to the magnetic tape 1 by the recording head 8. Upon reproduction, the (A) track is reproduced by the reproducing head 9. Although the (B) track is not reproduced, the single signal is recorded as a (B) track, so that the overwriting operation and the ATF operation of an area method can be performed and, further, an excellent signal can be reproduced from the (A) track.

Abstract: A recording and reproducing apparatus records and reproduces video signals which include video information and copy protection information for restricting the number of times the video information may be copied. Original video information is recorded onto a recording medium with updated copy protection information that indicates that the video information has been copied and is also transmitted with the original copy protection information so that more than one copy of the video information may be generated from the original. The transmitted video information is outputted and/or recorded onto a recording medium with the updated copy protection information.

Abstract: The magnetic recording apparatus according to the present invention comprises a recording medium in which servo information items are provided on tracks at a predetermined interval, a head for scanning the tracks of the recording medium, a read/write circuit for reading/writing data with respect to each of recording units on the recording medium through the head, a servo circuit for sequentially reading the servo information items through the head, a first control section for performing control on the basis of the servo information items read out by the servo circuit such that drive power is supplied to the read/write circuit, a predetermined time period before a time point when the read/write circuit starts reading/writing of data with respect to a target recording unit, and a second control section for preventing supply of the drive power to the read/write circuit, upon completion of the reading/writing of the data by the read/write circuit.

Abstract: A data storage device for reading and writing information to and from a storage medium and having an actuator for moving a read/write head over a surface of the storage medium comprises an optical sensor mounted on either a surface of the data storage device or a surface of the actuator, and a gray-scale pattern provided on the other of these surfaces, opposite the optical sensor. The gray scale pattern provides an amount of reflected light at the optical sensor that varies with the position of the actuator. The optical sensor receives the reflected light and generates therefrom an output signal indicative of the position of the actuator. A control system processes the position signal output from the optical sensor for controlling the velocity of the actuator.

Abstract: A disk recording and/or reproduction device subject to shock and vibration. The track following function of the transducer is augmented by an acceleration responsive sensor. The acceleration responsive sensor is sampled at a different frequency than the sampling frequency of the head disk assembly position error signal. The variations in the gain of the acceleration responsive sensors can be compensated for in real time.

Abstract: A loading and unloading device for loading and unloading a head slider has an actuator driver circuit 11 for driving an actuator 3 with pulses. A counterelectromotive force generated by a voice coil of the actuator is detected when the pulses are off, and fed back to the actuator driver circuit 11 to enable the actuator driver circuit 11 to control the position and speed of the actuator. The speed at which the head slider is loaded and unloaded can thus be controlled into a desired value to minimize the danger of collision between a head and a disk.

Abstract: A method for controlling tape running in a tape driving apparatus in which the size of a hub is determined when a tape is inserted into the tape driving apparatus and the number of reference pulses corresponding to one rotation of the reel in an end position of the tape is calculated according to the determined size of the hub. The tape is run and the frequency of rotation of the reel is detected. A comparison is made between the number of pulses of the present reel and the number of reference pulses, and if the number of pulses of the present reel is smaller than the number of reference pulses, the running mode is continuously performed. If, however, the number of pulses of the present reel is larger than the number of reference pulses, then a stop position is judged and the tape running is stopped, resulting in entering into a stand-by mode.

Abstract: Two-phase servo patterns are recorded on a servo area of a data medium of a data storage apparatus such that patterns Q+, N+, N- and Q- are recorded in the stated order, there being a phase shift of 90 degrees between position information N and position information Q.

Abstract: In a head displacement measuring method, prior to actual data recording or data reproduction, either one of the recording head and the reproducing head is wobbled, and the test data is recorded in the disk-shaped recording medium by the recording head. Then, the test data is reproduced from the test data by the reproducing head, and displacement between the recording head and the reproducing head is detected on the basis of the reproduced test data. Thus, the displacement may be detected more easily with higher precision than with the conventional optical detecting method.

Abstract: A end report of the unloading operation is issued to a host computer for a period of time between after the start of the ejecting operation of a medium cartridge of a recording/reproducing unit based on an unloading command until before the end of the unloading operation, thereby allowing the next moving command to be issued precedently to the end of the actual unloading operation. Simultaneously with that the unloading operation is instructed to the recording/reproducing unit on the basis of the unloading command, the end report of the unloading operation is executed to the host computer, thereby allowing the host computer to issue the next moving command. In a data transfer control between the host computer and a control unit of a library apparatus, when the number of error times of the data transfer errors exceeds a threshold value, the subsequent data transfer speed is switched to the executable data transfer speed at which the data transfer can be retried, and the data transfer is executed.

Abstract: In order that a measurement error of a phase difference based on an eccentricity produced when an optical disc is inserted into a disc spindle and rotated can be eliminated to improve a measurement accuracy, a polarity adding circuit is provided between an exclusive-OR circuit for detecting an absolute value of a phase difference and a low-pass filter to determine the polarity to thereby eliminate a measurement error in the vicinity of a portion where a phase difference is zero.

Abstract: A method of inhibiting inadvertent and unauthorized writing and reading of information to and from a storage medium comprises the steps of (a) writing a first code in a predetermined location on the storage medium, the first code being indicative of a first protection mode of the storage medium; (b) receiving a command to change the protection mode of the storage medium from the first protection mode to a second protection mode; and, in response to the command, (c) writing in the predetermined location on the storage medium, in place of the first code, a second code indicative of the second protection mode. A protection mode can inhibit writing to the storage medium, both writing and reading to and from the medium, or neither. Changing of protection modes can also be password protected.

Abstract: An intelligent disk drive includes a controller which embeds user data address information into error correction code check symbols written to the data storage disk. The address information is not written to disk, but address errors are detected by decoding the error correction code check symbols during read operations. Disk space is saved while maintaining robust address error detection.

Abstract: A cartridge for a data storage disk drive has a retroreflective marker. Light from a source is reflected from the marker almost exactly on its incident path. This property makes possible unique identification of the cartridge with minimal senstivity to light reflected from other surfaces. The marker enables a disk drive enable circuit so that the drive cannot be used with improper cartridges which might damage it. Also, a retroreflective marker is used for write protection of the cartridge.

Abstract: In a video recording/reproducing apparatus, an automatic power-saving circuit determines the existence of an input video signal and controls recording/reproducing functions accordingly, whereby recording/reproducing functions continue if an input video signal is present, and, if no video signal exists and no function key is input for a predetermined period of time, the recording/reproducing actions are halted and power is automatically cut-off.

Abstract: A magnetic recording and reproducing apparatus records a signal on a recording track of a magnetic recording medium in a recording mode and reproduces the signal from the recording track of the magnetic recording medium in a reproducing mode.

Abstract: A method of controlling start-up of a sensorless spindle motor used in a disk apparatus reduces time spent on start-up of a spindle motor with high reliability. The motor is used for rotating a disk on which information is recorded, and no sensor is provided in the motor for sensing an angular position of a rotor relative to a stator of the motor. The motor is operated at a steady rotational speed and is stopped by supplying a stop command. An aligning operation is performed immediately after the motor is stopped. The aligning operation is performed to rotate the rotor to a predetermined angular position relative to the stator of said motor. The motor is operated at a steady speed by a synchronization control when operation of the motor is started by supplying a start command.