Abstract: A speaker diaphragm includes a combined fiber paper made with crushed silk chips and a crushed bast fiber. In the preferred embodiment, the bast fiber is a natural Manila hemp fiber. The silk fiber contributes vibration damping to the diaphragm while the bast fiber contributes strength and stiffness. The crushed silk chips and the crushed bast are mixed with water to produce a slurry from which the water is drained to produce the combined fiber paper. In a further embodiment of the invention, a layer of a different material is disposed between two layers of the combined filter paper. The layer of different material is selected from a hard wound silk gauze, a glass fiber, a polyamid fiber and a carbon fiber.

Abstract: A PCM difference data is obtained from an original data, and an absolute data having a lower bit number than the original data is obtained at every data block, each data block comprising a plurality of the difference data. The transmission data includes the difference data and absolute data which is transmitted. The received data is separated into the difference data and the absolute data and the received difference data is integrated to provide the demodulated data. The integrated data is refreshed by the received absolute data only when the difference between the integrated data and absolute data is more than a predetermined value.

Abstract: This invention discloses an AM stereo transmission method characterized in that when left and right audio signals L and R are transmitted as an AM stereo signal which is represented by S=A cos(.omega.t+.phi.) wherein A denotes an amplitude, .omega. a carrier angular frequency and .phi. a phase angle given by tan.sup.-1 (L-R)/1+L+R, the audio signal of low frequency is transmitted at an amplitude A=(1+L+R), and the audio signal of high frequency is transmitted at an amplitude A=.sqroot.(1+L+R).sup.2 +(L-R).sup.2. The modulator according to the present invention comprises a matrix circuit for providing signals (L+R) and (L-R), an orthogonal modulator to produce an AM stereo signal .sqroot.(1+L+R).sup.2 +(L-R).sup.2 cos(.omega.t+.phi., an amplitude controller, an amplitude control signal generator circuit and a low-pass filter. In the modulator the said AM stereo signal S is changed to the signal (1+L+R)cos(.omega.t+.phi.) for audio signal of low frequency by controlling the amplitude controller.

Abstract: A data transmission system combines a near-instantaneous companding system with PCM or DPCM transmission data. In the transmitting side, lower bits are removed from an original data, to form transmission data and are accumulated in an accumulator. When a carry is caused as a result of such accumulation, the carry is added to the transmission data. Thus, total amount of the original data can be transmitted to the receiving side, thereby to improve a transmission quality and to reduce quantizing-noise. When the removed bits are subject to an addition, it is determined whether an overflow occurs. When the overflow occurs, the addition is not performed and such a logic operation as to prevent the overflow is performed.

Abstract: The present invention discloses a relative velocity control device which enables to generate constant relative velocity between a head and a tape in a magnetic recording and reproducing system with a rotating head. When the tape running speed and direction are given at input terminals, the number of drum rotations is calculated by the first calculation means based on the conditional equation which makes the relative velocity constant, and the drum motor can then be rotated according to the control of the drum rotating controller which generates an output voltage corresponding to the difference between the drum rotation number calculated from the first calculation result and the present number of drum rotations detected by the drum frequency generator.

Abstract: The present invention provides a digital signal waveform shaping circuit for reproducing a digital signal recorded on a recording medium. The waveform shaping circuit includes at least one comparator for receiving an input signal and a delay circuit connected to the output of the comparator for delaying the comparator output by one-bit-cell. The input signal is compared with a threshold level associated with the output of the delay circuit.

Abstract: In a read clock producing system for generating a read clock signal which is used for extracting a digital information portion of a digital coded signal, the system comprises means for delaying a pulse obtained by comparing data with a certain threshold level, means for generating a clock pulse having a pulse width proportional to the delay, said generating means including a frequency division circuit, flip-flop and EOR means for comparing the pulse width with a predetermined pulse width, a differential amplifier for comparing the data with a second threshold level adapted to change in accordance with the above comparison, and the control means for controlling the delay by the use of an output from said comparison.

Abstract: A digital signal reconstruction circuit includes a reproduction means for reading a digital data signal recorded on a recording medium, signal derivation means for deriving a plurality of shifted signals produced by sequentially shifting the read digital data, arithmetic means, comprising a logical sum circuit and a logical product circuit, for processing the output from the signal derivation means, selector means for selecting either the output from the logical sum circuit or the logical product circuit and latch means receiving the output of the selection means, the output of the latch means being fed back to the selector means to control the selection of either the logic sum circuit or the logic product circuit in accordance with the logic level of the latch means output.

Abstract: Disclosed is an amplifier wherein, in order to prevent the mixing of hum and other noise from the ground potential of the amplifier, the driving power supply circuit of the amplifier is separated from the ground potential into a floating state. In addition, the overall capacity of the power supply is reduced.

Abstract: In a record player of the direct drive system wherein a turntable and a motor for driving the turntable are directly coupled; a record player characterized in that a cancellation mechanism is disposed coaxially with the driving motor, said cancellation mechanism performing a reciprocating rotational motion to generate to a torque equal in magnitude and reverse in direction with respect to a torque fluctuation developed by rotation of said driving motor, thereby to cancel counteractive rotational vibrations exerted on a cabinet of said record player by said driving motor.

Abstract: A record player wherein a second turntable and motor which are respectively equivalent to an ordinary turntable and motor are additionally disposed, and both the motors are driven and controlled so as to cancel their torques each other, thereby to eliminate a cross modulation distortion from a pickup.

Abstract: A bias circuit for use in the single-ended push-pull circuit has NPN and PNP transistors whose emitters are connected to each other and whose collectors provide a bias voltage, diodes and resistance elements. On the operating side, the diode gives a reference voltage and the resistance element detects the voltage corresponding to the increase of the output voltage exceeding the reference voltage. Simultaneously, on the unoperating side, the diode decreases the voltage between its both terminals. Thus the bias voltage is made larger, by positive feedback operation on the operating side and by negative feedback operation on the unoperating side, enough to prevent output power transistor on the unoperating side from being cut off.

Abstract: An amplifying device comprising a pre-amplifier, a first high power amplifier of a relatively bad lineality for amplifying the outputs of the pre-amplifier, a first impedance element for applying the outputs of the first amplifier to a load, a negative feedback circuit for feeding back the outputs of the first amplifier to the input of the pre-amplifier and a second low power amplifier of the relatively good linearity for amplifying the inputs of the first amplifier and supplying the outputs through a second impedance element to the load. The amplifying device can cancel the distortion in the high frequency band caused in the first amplifier through the first and second impedance elements by the outputs of the first amplifier.

Abstract: A differential amplifier able to produce differential-mode output signals different from one another in DC voltage level, is formed by connecting a pair of NPN transistors and another pair of PNP transistors so that the emitter electrodes of these four transistors are coupled to one another by a resistive coupling circuit. The resistive coupling circuit is so arranged that the resistance between the emitter electrodes of the NPN transistors is equal to that between the emitter electrodes of the PNP transistors, with the resistances between the emitter electrodes of one of the NPN transistors and of one of the PNP transistors being equal to that between the emitter electrodes of the other NPN transistor and the other PNP transistor.

Abstract: Disclosed herein is a protection circuit for a power amplifier. The protection circuit comprises a current detecting section for detecting a level of a load current of the power amplifier, a voltage detecting section for detecting a level of a load voltage across a load, an AND-gate circuit responsive to outputs of the current detecting section and the voltage detecting section for detecting a short-circuit of the load, and a control section responsive to an output of the AND-gate circuit for disconnecting the load from the amplifier.

Abstract: Coupling an outer antenna with a radio receiver having a bar antenna is achieved by connecting the outer antenna to a coupling coil which is able to be removably mounted on a bar core of the bar antenna and by mounting the coupling coil on the bar core with such an orientation of the coupling coil that the signal received at the outer antenna does not cancel the signal received at the bar antenna. The connection between the outer antenna and the coupling coil may be made by the use of a coaxial cable with the outer conductor of the cable being not grounded to function as a ground plane. A series circuit of a switch and a resistor may be connected in parallel with the coupling coil to selectively reduce the quality factor Q of the bar antenna.

Abstract: A pickup cartridge is disclosed, which comprises a cantilever having one end provided with a stylus and the other end provided with an armature magnetized in the axial direction thereof, a yoke having at least three leg portions each having an end face, the end faces being faced to a peripheral side surface of the armature except a lower side surface portion thereof and a plurality of coils wound on at least two of the three leg portions and connected to detect only change of magnetic flux due to a desired slanted vibration of the armature.