Victor Company of Japan, Limited

Susumu Sakakibara

Hiroyuki Sugiyama

Ryozo Abe

Isami Kaneda

Yasushi Sano

Masaki Sakurai

Kenji Yoshihara

Hideo Nomura

Yutaka Osada

In a head position control apparatus, a magnetic pole disc mounted on a DC motor has a plurality of opposite magnetic poles arranged on its circumference in a predetermined relationship with tracks on a floppy disk. A sensor located close to the pole disc generates a pulse signal having pulses corresponding to the tracks and a voltage representing the actual speed of the motor. The pulses are counted in an incremental or a decremental mode. The difference between a track position indicating command signal from a keyboard and the pulse count is detected for deriving a direction signal which indicates the direction of the head and determines the count mode, a speed reference variable according to a predetermined transfer function and a switching signal when the difference reduces below a certain limit. A speed control signal is generated representing the difference between the speed reference and the actual speed of the motor. A position control signal is generated representing the difference between the amplitude of the pulse signal and a reference voltage. In response to the switching signal one of the control signals is applied to a polarity inverter for inverting or noninverting its polarity depending on the direction signal and on its amplitude relative to the reference voltage.

Head positioning apparatus using a DC motor

A periodical signal detection circuit in a reproducing apparatus which reproduces an information signal and a periodical signal from a recording medium recorded with the information and periodical signals comprises a separation circuit for separating the periodical signal from the reproduced signal, a reference pulse generating circuit for generating a reference pulse having a same repetition frequency as the periodical signal, a window signal forming circuit for forming window signals respectively having differing widths, with a repetition period identical to that of the reference pulse, a first gate circuit for producing the periodical signal from the periodical signal obtained from the separation circuit and the window signal obtained from the window signal forming circuit, a first counter for generating a switching control signal every time the reference pulse is counted N (N is an integer including zero) times, to produce an output when counting is performed for a predetermined number of times, a window signal supplying circuit responsive to the switching control signal obtained from the first counter of the window signals from the window signal forming circuit, for supplying a window signal having a width corresponding to the switching control signal to the first gate circuit, a second gate circuit for passing the signal from the separation circuit according to the output of the first counter, and an output circuit for producing the reference pulse, the output of the first gate circuit, or the output of the second gate circuit as a detected periodical signal.

Periodical signal detection circuit within a variable window length

A reproducing element feeding and driving circuit is provided in a rotary recording medium reproducing apparatus consisting of a signal pickup device having a reproducing element for reproducing recorded signals from a rotary recording medium, a feeding mechanism for feeding the signal pickup device, and a tracking error signal obtaining circuit for obtaining a tracking error signal so as to perform tracking control with respect to the reproducing element. The feeding and driving circuit comprises a sampling circuit for sampling the tracking error signal when the reproducing element is reproducing a point on the rotary recording medium corresponding to one of a plurality of pairs of points on the rotary recording medium, where the pairs of points are points which are at symmetrical positions along a diametrical direction of the rotary recording medium with respect to a center of the rotary recording medium, averaging circuit for averaging a value sampled by the sampling circuit and obtaining a signal substantially corresponding to a DC component of the tracking error signal, and a feed pulse applying circuit for obtaining a feed pulse having a pulse width which is in accordance with the DC component obtained from the averaging circuit and applying the feed pulse thus obtained to the feeding mechanism.

Drive circuit for feeding a reproducing element across a rotary medium

A rotary recording medium reproducing apparatus for reproducing a rotary recording medium recorded with a program information signal and different kinds of address signals having mutually different predetermined codes in correspondence with the program information signal within a program information signal recorded section. The reproducing apparatus comprises a reproducing element for reproducing recorded signals from the rotary recording medium, a moving device for moving the reproducing element along a radial direction of the rotary recording medium, an address signal detecting circuit for detecting address signals from signals reproduced by the reproducing element, and a driving voltage generating circuit set with an address signal to be searched, for generating a driving voltage in accordance with the kind of set address signal, and supplying the driving voltage thus generated to the moving device. The moving device moves the reproducing element at a speed in accordance with the kind of the address signal.

Rotary recording medium reproducing apparatus address search

A reference signal detection circuit in a rotary recording medium reproducing apparatus has a reproducing transducer for reproducing an information signal recorded in a rotary recording medium and reference signals for tracking servo recorded for every predetermined period, from the rotary recording medium rotating at a predetermined rotational speed, and a tracking servo circuit for obtaining a tracking servo signal from the reference signals and performing a tracking servo operation according to the tracking servo signal thus obtained. The detection circuit further comprises a single rectifying and smoothing circuit for rectifying and smoothing the reproduced reference signals obtained for every predetermined period. The detection circuit has a lowpass filter characteristic wherein the cutoff frequency is within a frequency range between one third and twice the gain crossover frequency of the tracking servo loop.

Reference signal detection circuit in a rotary recording medium

A rotary recording medium reproducing apparatus reproduces a rotary recording medium in which one and the other of first and second reference signals are alternately recorded every track turn between each track turn of a main information signal track. The reproducing apparatus comprises a reproducing transducer having a reproducing element for reproducing the main information signal and the first and second reference signals at both sides of the main information signal track from said rotary recording medium, where the reproducing transducer has a tracking control mechanism for controlling tracking of the reproducing element, a separation circuit for respectively separating the first and second reference signals from a signal reproduced by the reproducing transducer, a wave detection circuit for respectively wave-detecting the separated reference signals, a time constant circuit for eliminating an unwanted component of an output signal of the wave detection circuit and holding a required signal, a tracking control signal applying circuit for obtaining a tracking control signal from an output signal of the time constant circuit and applying the tracking control signal to the tracking control mechanism of the reproducing transducer, and an interrupting circuit provided at a stage before the time constant circuit, for interrupting transmission of the reproduced reference signals during a mode in which a tracking control operation is not performed.

Rotary recording medium reproducing apparatus with a tracking control

A transfer control device for a reproducing transducer in a rotary recording medium reproducing apparatus having a reproducing transducer for reproducing recorded signals from a rotary recording medium and a driving motor for transferring said reproducing transducer on said rotary recording medium comprises a micro-computer having first and second output ports, where the first output port produces a signal of a pulse form which repeats high-level and low-level periods during a normal-speed transferring mode, and the second output port produces a continuous high-level or low-level signal according to the transferring mode so that a combination of a predetermined level is obtained between the output signal from the first output port, a square wave signal generating circuit applied with the output signal from the first output port of the micro-computer, where the square wave signal generating circuit is triggered to produce a predetermined square wave signal when applied with the signal of a pulse form and not triggered when applied with other signals of constant level, and a switching circuit applied with the output signal from the first and second output ports of the micro-computer, to switch over a plurality of input terminals according to the levels of the applied signals and pass the input terminal voltage through to an output side as an output voltage. The switching circuit supplies the output voltage thus obtained to the driving motor.

Growing community of inventors

Sagamihara, Japan

Susumu Sakakibara