Abstract: An optical disk data recording and reproducing apparatus includes variable delay circuits in the recording and reproducing sections of the apparatus. The delay of the reproducing section delay circuit is adjusted when the error ratio determined for a reproduced data signal corresponding to a recorded data signal is greater than a predetermined value. When the error ratio is less than the predetermined value after adjustment of the delay circuit, the delay of the delay circuit in the recording section is adjusted to match the adjusted delay of the reproducing section delay circuit and the delay of the latter circuit is retured to its original value.

Abstract: A disc player comprising a signal pickup unit to read information from a disc on which program information including address information is recorded, the signal pickup unit being movable with respect to the disc, pickup drive means to drive the pickup unit for movement with respect to the disc, and a control circuit including an address memory for storing the newest one of the addresses read from the disc, a counter operative to count addresses at predetermined time intervals for producing a signal representative of an expected address indicative of the position to which the pickup unit is expected to move in the next, the expected address being updated at predetermined time intervals, a detector circuit to produce a signal each time a discrepancy is found to exist between the newest address and the expected address.

Abstract: A recording-reproducing clock generator circuit generates a reproduced clock having a predetermined frequency from a read out signal including such pulses that the interval between two successive pulses thereof at a predetermined length is to be used as a synchronizing signal region. The circuit generates a reference clock of a predetermined frequency, generates a first sync signal detection signal when the distance between two successive pulses in the input signal measured by means of the clock pulses is equal to a predetermined reference value, separates a clock edge pulse from the input signal by using the first sync signal detection signal, and generates the reproduced clock having the predetermined frequency and synchronized with the separated clock edge pulse.

Abstract: An RF signal processing circuit for processing an RF signal read from an optical disk or the like in which the entire dynamic range of an A/D converter circuit used to digitize the RF signal. An edge detector circuit detects the edges of the amplified RF signal, and a synchronizing signal detector detects a synchronizing signal in correspondence to the output of the edge detector. A timing signal is produced in correspondence to the output of the synchronizing signal detecting circuit. A clamping circuit clamps the input of the edge detector at a predetermined voltage in correspondence to the timing signal, whereby the input of the edge detector is clamped for at least a portion of the time period to the synchronizing signal.

Abstract: A servo circuit for use in an optical disk player or the like, which can track a disk having a large eccentrically without abnormal sampling of the RF signal produced as a result of scanning the disk.

Abstract: An automatic disc player including a housing, disc carrier means to convey a disc between predetermined playback position and a predetermined withdrawal position ready to be withdrawn out of the housing upon termination of plaback operation, signal generating means for producing control signals to be predominant over various steps of the playback operation, and an electric control circuit responsive to the control signals to control the various steps of the playback operation, the signal generating means comprising position detecting means responsive to movement of the disc to the withdrawal position and operative to produce a signal when the disc being moved away from the playback position reaches the withdrawal position, and playback re-start switch means which is operative to produce a signal in response to slight movement of the disc from the withdrawal position toward the playback position, the control signals to be produced by the signal generating means including signals to control the start of playbac

Abstract: In an optical data recording and reproducing system in which recording and reproducing data are carried out with a semiconductor laser, circuitry is provided to reduce the level of a high frequency current to be superposed on the laser during a data recording operation relative to the level during a data reproducing operation, to provide laser output only when necessary, to prolong laser life.

Abstract: An actuator drive circuit for driving a load using a single power supply. The current drive is not dependent on load impedance characteristics. Drive means provides a voltage across the first terminal and the second terminal during at input signal positive phase, and reverse voltage across the first terminal and the second terminal during a negative phase. A current detection resistor is connected in series with the load, and the voltage across the resistor is input to a differential amplifier. The amplifier output provides feedback to the drive means.

Abstract: An automatic disc player including a housing, disc carrier means to convey a disc between predetermined playback position and a predetermined withdrawal position ready to be withdrawn out of the housing upon termination of playback operation, signal generating means for producing control signals to be predominant over various steps of the playback operation, and an electric control circuit responsive to the control signals to control the various steps of the playback operation, the signal generating means comprising position detecting means responsive to movement of the disc to the withdrawal position and operative to produce a signal when the disc being moved away from the playback position reaches the withdrawal position, and playback re-start switch means which is operative to produce a signal in response to slight movement of the disc from the withdrawal position toward the playback position, the control signals to be produced by the signal generating means including signals to control the start of playba

Abstract: A high frequency signal detection device to be used in an information playback system for playing back signals from a record medium having a plurality of record tracks, includes first and second positive peak hold circuits having different time constant and a negative peak hold circuit. A difference circuit is provided to generate a difference signal between output signals of the first positive peak hold circuit and the negative peak hold circuit and an output signal of the difference circuit is compared with an output signal of the second positive peak hold circuit, to produce a high frequency signal detection signal. Thus, a very accurate detection signal is produced irrespective of the polarity of the input signal and whether or not the envelope of the high frequency signal is symmetric.

Abstract: A data reading device for reading out data modulated according to a system wherein the time ratio of low to high level signals is substantially unity employs a time ratio detector and an intermediate level detector. A comparator compares the reproduced output level with a synthesized signal which may represent a combination of the outputs of the time ratio detector and the intermediate level detector.

Abstract: An electronic impedance circuit is constructed of a voltage-current converter and a variable gain current amplifier. The voltage-current converter includes first and second transistors of the PNP-type differentially connected. The variable gain current amplifier includes third and fourth transistors of the NPN-type differentially connected, and fifth and sixth transistors of the PNP-type as load means. The bases of the third and fourth transistors are respectively driven by collector signals of the first and second transistors, and a collector signal of the third transistor is fed back to the base of the second transistor. In order to reduce a d.c. offset attributed to a current flowing between the base of the second transistor and the collector of the third transistor, a compensation circuit is connected to the variable gain amplifier.

Abstract: An electronic impedance device provides a variable impedance in, for example, a Dolby noise reduction system. The device includes an input terminal connected to a source of a signal voltage. A differential voltage-to-current converter circuit, having a relatively high input impedance, converts the input signal voltage into two differential output currents that are variable with the input signal voltage. A pair of p-n junction elements, such as diodes, are connected to the converter circuit via a current transfer circuit. The current transfer circuit transfers the differential output currents to the p-n junction elements. A differential current amplifier circuit is responsive to the voltage built up across the p-n junction elements. The differential current amplifier has an output terminal to produce an output current.

Abstract: Conventional Dolby B-type or C-type noise reduction systems respond sensitively to an A.C. bias signal during recording onto a magnetic tape. As a result, the system might exhibit a large encode error. In order to reduce such encode error, the gain - frequency characteristic control sensitivity of a side chain in the system to the A.C. bias signal to be supplied to a recording head is set at a value smaller than that of the gain - frequency characteristic control sensitivity of the side chain to an encode input signal at an audio frequency. Such a reduction of the encode error is achieved by connecting a bias trap circuit to a gain control amplifier included in the side chain.

Abstract: The auxilliary signal path in a compander system includes, in series, a first amplifier 7, a weighting function amplifier 8, and a detection circuit 9. The output of the latter controls the gain of a voltage-controlled variable gain circuit 11 also connected to the first amplifier output, and the integrated output of the variable gain circuit is fed back to the input of the first amplifier via a subtraction circuit 13 also supplied with the auxilliary signal path input. Alternatively, the first amplifier may comprise an operational amplifier, in which case the integrated signal is directly coupled to one of its inputs.