Abstract: A DC-to-DC conversion circuit for supplying dual positive and negative DC output voltages of the same level in absolute value to a load circuit such as a class B power amplifier. An alternative fluctuation in the positive and negative DC output voltages is regulated, making it unnecessary to regulate both simultaneously.

Abstract: This invention relates to a method of converting a digital signal into an analog signal and a digital-to-analog converter therefor.In the invention, a digital signal having varying pulse width values is converted into a first pulse width signal, with each pulse varying in its pulse width in response to its respective data values and with the center of each pulse width being at a fixed time position within a respective sampling period, while a complement of the digital signal is converted into a second pulse width signal with each pulse varying in its pulse width in response to its respective data value and relative to said center of each respective pulse width. The first and second pulse width signals, after one of them is inverted, are mixed and pass through a smoothing filter to demodulate the digital signal into the analog signal.

Abstract: In the invention, a digital signal consisting of upper and lower bits is sampled while the upper and lower bits are divided. The sampled digital signal components of upper and lower bits are converted into upper and lower pulse width signals having a pulse width responding to their data value, respectively. Thereafter, the upper and lower pulse width signals are mixed and pass through a smoothing filter to convert the digital signal into an analog signal. The upper pulse width signal is formed of a pulse signal varying in a pulse width in response to the data value of the upper bits relative to a center of pulse width which has a fixed time position within a sampling period. The lower pulse width signal is formed of a combination of pulse signals varying in each pulse width in response to the data value of the lower bits relative to each center of pulse width which is at each pulse edge of the upper pulse width signal.

Abstract: This invention relates to a magnetic head device. An azimuth position of a gap of a magnetic head is adjusted relative to the position of a signal on a magnetic tape in a playback mode wherein the magnetic head functions as a reproducing head, while the azimuth position of the magnetic head is returned to a predetermined reference position in response to a selection of a record mode wherein the magnetic head functions as a recording head.

Abstract: This invention relates to an improvement in a dual capstan drive unit for a reversible tape recorder. A dual capstan drive unit has means to generate variable frequency signals varying in their frequencies corresponding to the revolution speed of first and second capstans which serve to transport a magnetic tape. A single clock oscillator feeds two frequency dividers to produce first and second slightly different reference frequency signals to produce a slight difference between the peripheral speeds of upstream and downstream capstans to maintain tape tension for both tape directions. Control means to controls the revolution of the first and second capstans and compares the detected frequency signals with the respective reference frequency signals so that the revolution of the first and second capstans have a predetermined value.

Abstract: This invention relates to a signal conversion circuit, and more particularly to a signal conversion circuit to convert a digital signal sampled in synchronism with a sampling pulse into a pulse width signal having a pulse width corresponding to the digital value of the digital signal.A first counter is preset to a first count value corresponding to the digital value of the sampled digital signal and begins to count a first clock signal having a predetermined pulse period from the first count value. A second counter is preset to a second count value which is a complement of the first count value and begins to count a second clock signal having a pulse period twice as many as that of the first clock signal from the second count value in response to the detection of a full count of the first counter.

Abstract: This invention relates to a magnetic head for providing azimuth information therefrom relative to a signal recorded on a magnetic tape. The magnetic head of the invention has first and second coils for providing a reproduced signal corresponding to a recorded signal on the entire width of a recording track and a reproduced signal corresponding to a recorded signal on a part of width of the said recording track.

Abstract: This invention pertains to a method of correcting a position of a disk record on a turntable for positioning the record on the turntable in a concentric manner relative to the rotational center of the turntable.In the method of the invention, a stylus which is mounted on a pickup arm traces a groove of a record placed on a turntable. On tracing the groove of the record, an angular displacement of the pickup arm is detected for detecting an eccentricity of the record relative to the rotational center of the turntable. The position of the record on the turntable is corrected in accordance with the detected eccentricity.

Abstract: This invention relates to a volume control for an audio apparatus and more particularly to a fader for fading in or out a level of an audio signal. The volume control of the invention comprises a charge and discharge circuit having a capacitor charged and discharged by a constant current in response to a fade-in or fade out operation, and a function generator to generate a signal having a logarithmic waveform periodically repeated. A control signal generator compares the voltage across the capacitor of the charge and discharge circuit with the logarithmic waveform signal from the function generator to generate a control signal logarithmically varying in accordance with variation in the voltage across the capacitor of the charge and discharge circuit. An impedance controller logarithmically changes an impedance of an audio signal line in accordance with the control signal to logarithmically change the level of the audio signal in substance.

Abstract: A magnetic head suitable for a reversible stereo cassette tape recorder is disclosed. The magnetic head had a larger operating gap for the recording head than for the reproducing head. This is accomplished by a thicker spacer between the core pieces for the recording head than for the reproducing head. The two spacers are in line, and the core pieces are held on one hand by a common holding member and on the other hand by separate lower and upper holding members.

Abstract: This invention pertains to a recording bias setting device for a magnetic recording and reproducing apparatus.

Abstract: This invention relates to azimuth adjustment means for a magnetic head and, more particularly, to azimuth adjustment means for a magnetic head adapted to precisely adjust the azimuth of the magnetic head by remote control. The head azimuth adjustment means comprises an azimuth adjustment screw having its end acting on a head base on which a magnetic head is mounted and rotatable so that the head base is positioned so as to have the proper azimuthal position of the magnetic head. The head azimuth adjustment means further comprises an adjustment member interposed between the end of the azimuth adjustment screw and the head base and slidably movable in its longitudinal direction, the adjustment member having an inclined surface provided thereon in a direction of its slidable movement.

Abstract: This invention relates to an information read device for reading the information of a coded AC signal.

Abstract: This invention pertains to a fluorescent indicator adapted to indicate a level of a signal to be measured in an acoustic instrument and/or a vertical condition of a magnetic head in a multi-channel tape recorder.The fluorescent indicator comprises a fluorescent indicating tube having a plurality of segment anodes arranged in a row from a lowest level side to a highest level side, pulse generator means to generate clock pulses having the number of pulses corresponding to the level of a signal, and counter means including a plurality of output terminals connected to the respective segment anodes to have output signal sequentially generated corresponding to the count of the clock pulses to operate the segment anodes of the fluorescent indicating tube.

Abstract: This invention relates to head adjustment means for a tape recorder. The head adjustment means comprises a pair of adjusting screws having the same pitch to threadedly extend through said base plate, respectively, and to engage said head mounting plate at two points spaced from each other in a plane in which a gap of said magnetic head is contained and which plane is perpendicular to a running plane of said magnetic tape whereby independent rotation of each of said adjusting screws adjusts the tilt of said magnetic head relative to a surface of said magnetic tape and a connecting member to be selectively connected with both of said adjusting screws so as to cause said screws to rotate at the same time and at the same rate of rotation whereby their associated rotation adjusts a vertical position of said magnetic head without varying the tilt attitude of said magnetic head.

Abstract: This invention relates to a pad abutting device for a magnetic head of a dual capstan type cassette tape recorder. This pad abutting device comprises a pair of upper and lower abutting members mounted on a front face of a magnetic head which is to be extended through an opening of a cassette having a pad provided therein, the abutting members being disposed apart by a distance less than the width of the pad, but greater than the width of a magnetic tape in the cassette. When the cassette is placed in the tape recorder so that the magnetic head enters the opening of the cassette, the abutting members abut against the pad at its upper and lower edges whereby the pad is prevented from resiliently pressing the magnetic tape against the magnetic head.

Abstract: This invention relates to a mode changing system for a cassette tape recorder in which operating members such as a head base plate and a pinch roller are selectively moved to one of various modes such as stopping, fast forwarding, rewinding, pausing, cueing and playing. This system comprises control means to control the movable components so as to move them to a position corresponding to a selected one of the modes. The control means is actuated by a control electric motor.

Abstract: This invention relates to a control system for a tape recorder wherein magnetic head means is selectively moved relative to a magnetic tape. A recording and reproducing circuit including a recording amplifier and a reproducing amplifier is connected to the magnetic head means. Control means driven by a control electric motor moves the magnetic head means from a stopping mode to an operating mode including at least recording mode and reproducing mode. Mode selecting switches are provided to operate the control electric motor. The control system of the invention comprises means provided in the recording and reproducing circuit to energize it when instruction signals are received.

Abstract: This invention relates to a mode changing system for a cassette tape recorder in which operating members such as a head base plate and a pinch roller are selectively moved to one of various modes such as stopping, fast forwarding, rewinding, pausing, cueing and playing. This system comprises control means to control the operating members so as to move them to a position corresponding to a selected one of the modes. The control means is actuated by a control electric motor.