Abstract: A recorded tape travel control system uses a motor for rotationally driving a capstan which, in turn, drives a tape. First and second manipulation switches, respectively, generate first and second manipulation signals. A circuit for changing the rotational direction of the motor responds to the manipulation signals of the manipulation switch. A speed change circuit operates in response to the manipulation signals which are generated by manipulating, in continuous succession, a plurality of times either the first or the second manipulation switches in order to increase the rotational speed of the motor in a stepwise manner. Speed also decreases in a stepwise manner in response to manipulation signals generated by alternately manipulating the first and second manipulation switches. A circuit is also provided for stopping the rotation of the motor.

Abstract: A recorded medium is brought to its operational velocity at which a phase lock is simultaneously achieved between a recorded sync signal thereon and an external reference sync signal, during a rapid framing cycle that corresponds in time with the duration taken by the recorded medium to travel through a distance equal to two consecutive spaces between recorded sync signal pulses.

Abstract: A television receiver is provided for use as a picture display terminal for electronic peripheral equipment, where a control system with a data-bus is built into the television receiver for multitude of commands and in which the television receiver is intended to be used in addition to the normal direct reception of televised pictures for other possible applications. The television receiver can serve as a monitor for a picture tape recorder, which is equipped for recording independently of the television receiver. A complete television receiving set is provided with automatic transmitter seeking mechanism and electronic channel storage.

Abstract: An optical device for forming a stigmatic image of a laser source positioned at a predetermined point is intended to illuminate a reflecting surface while also providing a separation between the beam emerging from the source and the beam reflected from the surface. The device comprises a cube placed against a converging lens, the dimensions of the assembly thus formed being such that the cube face remote from the lens passes through a Weierstrass point of the spherical refracting surface formed by the lens. The laser source is positioned at the Weierstrass point. The cube is formed by two prisms cemented together, the interface being treated so as to have a polarization-separating effect.

Abstract: A video disc player is described for use with a video disc having frequency modulated video information recorded thereon in the form of a plurality of concentric circles or a single spiral. The information track comprises successively positioned light reflective and light non-reflective regions. A focused light beam is caused to be positioned over the center of an information track and the light reflected from the information track is gathered by an objective lens for application to electronic circuitry for recovering the recorded frequency modulated video signals. Radial tracking means are described for maintaining the focused light spot to impinge upon the center of an information track. Lens focusing means are described for positioning the objective lens at the optimum focused position above the information track for gathering the maximum amount of reflected light from the information track.

Abstract: A telephone group listening system is one in which one member of an assembled group has a telephone for communication with a remote party while the other members may only listen to the communication through the agency of a loudspeaker. The system is subject to the Larsen effect on call answering or clear down if the telephone handset is normally sited close to the loudspeaker. This effect is overcome by including a proximity switch in the loudspeaker circuit, the switch being triggered by a change in the level of coupling of a capacitively or inductively coupled circuit, the coupling being dependent on the closeness of the speaker's body to the switch or on the separation of the handset and the loudspeaker.

Abstract: A subscriber data carrier system for simultaneously carrying both base band telephone signals and full duplex digital data transmissions on a single pair of nonloaded telephone wires is disclosed. That is, the system provides for simultaneous conventional telephone signaling and audio communication and full duplex digital data communication between a pair of subscribers, each connected to the same main distribution frame of a central office by a single pair of nonloaded telephone wires. The system includes a modem (21) located at each subscriber's premises. The modems are connected to the subscriber's telephone (23) and digital data terminal (25). The modems include data transmitters (47) and receivers (49) that convert digital data from binary form into FSK form for transmission and from FSK form into binary form upon reception.

Abstract: This invention relates to a loudspeaker protection device which disconnects the drive unit, or units, of the loudspeaker from an amplifier when the voltage across, or the current through, the drive unit, or one of the drive units, exceeds a predetermined level. The protection device includes a bistable device comprising a complementary pair of transistors arranged to be changed from the reset state to the set state when the voltage on an input terminal exceeds a predetermined level. The transistors are arranged to be both non-conductive when the device is in the reset state and both conductive when the device is in the set state. When the transistors are conductive, the collector current of one of them flows through the coil of an electromagnetic relay having normally closed contacts in the output circuit of the amplifier.

Abstract: Accumulated foreign material on the signal pickup stylus of a video disc player tends to degrade the quality of the recovered information signal. The recovered information signal is detected and the nominal amplitude of the recovered signal is compared against a reference amplitude. The occurrence of a decrease in recovered signal amplitude below the level of the reference causes a comparator to generate a control or trigger pulse. The control pulse activates a pulse generator to produce a predetermined pulse sequence which is applied to a stylus deflection transducer to move the stylus fore and aft radially across the disc and thereby dislodge the foreign material from the pickup stylus.

Abstract: An optical read apparatus for a disc-shaped record carrier. The read apparatus comprises an optical read unit which includes a deflection element for controlling the radial position of the scanning spot, for which purpose said deflection element is included in a closed servo control loop. In order to enable a desired program section on the record carrier to be located rapidly, the read unit can be moved in the radial direction. During this movement of the read unit the servo control loop is rendered inoperative each time after the deflection element has reached a preset maximum deflection, after which this deflection element is reset rapidly and the servo control loop is rendered operative again. Thus it is achieved that image reproduction is also maintained during the rapid search for a desired program section.

Abstract: Piezoelectric video disc recording cutterheads have small and intricate geometries that make it difficult to compute or measure their mechanical characteristics, especially during the recording process. A monitoring circuit, for use during recording, for monitoring and measuring the mechanical characteristics of a recording cutterhead takes the form of a bridge network. The motional charge or motional current, which are related to the mechanical characteristics of the cutterhead, is measured by means of the bridge network. One branch of the bridge is arranged to include the piezoelectric cutterhead, the other branch comprises a variable capacitor which is adjusted to compensate for the shunt capacitance of the equivalent electrical circuit of the cutterhead. When the variable capacitance is properly adjusted the combination of the currents through the bridge network provides a signal representative of the displacement characteristics of the cutterhead.

Abstract: An interface unit inserted between a subscriber line of a telecommunication system and a generator of dial pulses, including a signal converter associated with a pushbutton selector and a memory for the temporary storage of selected digits, comprises a rectifier bridge in series with an impedance network which includes a shunt branch with two complementary transistors interconnected in a positive-feedback circuit and a low-threshold Zener diode in series with one of these transistors across which a reduced supply voltage for the pulse generator remains available when the shunt branch becomes conductive with saturation of the transistors upon a closure of the subscriber's hook switch. An enabling signal for the pulse generator is emitted from the shunt branch upon such conduction. An ancillary transistor, with an input connection across a small series resistor of the network, and a further Zener diode in parallel with the shunt path protect the components thereof against overcurrents and overvoltages.

Abstract: An apparatus for generating a recording time code signal having a time code data signal generator and a time code signal forming circuit which is supplied with a time code data signal from the time code data signal generator and produces a recording time code signal consisting of bi-phase coded signals, in which the above recording time code signal is corresponded to an information signal and then recorded on a recording medium continuously at word unit. In this case, the polarity of a specific bit signal of a fixed binary bit or value in the above recording time code signal of word unit is discriminated, and a changing circuit is provided in the time code signal forming circuit which changing circuit changes the above fixed binary bit in accordance with the polarity of the specific bit signal. Thus, a recording time code signal of word unit, which has a constant polarity of bit signals after the above specific bit signal, is derived from the time code signal forming circuit.

Abstract: A ringer circuit for a telephone is disclosed which is equipped with a transformer, having its primary winding connected to the telephone line through hook-switches. The secondary winding of the transformer is connected to a rectifying circuit so that it may convert the high voltage and low current of the ringer signal received into a secondary ringer signal having high current and low voltage. This secondary ringer signal is rectified and fed to an oscillator which drives a sound generator to provide a call signal.

Abstract: Apparatus for conditioning the hearing of a patient is disclosed. A signal level detector establishes whether an incoming audio signal is above or below a threshold level to gate the audio signal to one or other of two parallel channels. The first channel has a frequency response curve in which high frequencies are suppressed and thus is the channel used when the audio signal is below the threshold. The other channel has a frequency response curve in which low frequencies are suppressed and this is the channel used when the audio signal exceeds the threshold. Two parallel output stages are provided, one including an electromechanical vibrator which is placed on the patient's skull and the other including earphones worn by the patient.

Abstract: A pick-up phono cartridge in which the position of an armature disposed at a base end of a cantilever is made adjustable to thereby produce a desired output voltage. A vibrating system of the cartridge includes an armature secured to a base end of a cantilever having a stylus secured to the other end thereof. A center axis of the cantilever is vibratable around a predetermined position on the armature. A fixed system is provided including at least a front yoke and a rear yoke which are positioned to nearly clamp the armature. The vibrating system is made adjustable in the axial direction of the cantilever upon loosening a stop screw.

Abstract: An information signal recording medium of rotary type has a flat surface with successions of pits formed therein as respective concavities in response to an information signal. The successions of pits constitute respective circular tracks of a specific pitch. Each it is formed with a width, equal to the width of a track, which is substantially equal to or greater than said pitch of the track.

Abstract: According to the present invention there is provided a current detector useful in interconnection of an automatic telephone exchange with a central office via TIP and RING leads and comprising; rectifying apparatus coupled to the TIP lead for rectifying at least a portion of the current flowing therealong of either polarity; and detector apparatus receiving the rectified output of the rectifying means and providing a DC output signal indicating current passage along the TIP lead.

Abstract: A one-way receiving path is connected to the input side of a first phase-shift network which produces signals in phase quadrature at its output side, which is connected to the input side of a second phase-shift network which is conjugate to the first and whose output side is connected to a one-way transmitting path. A two-way transmission path and a balancing impedance are connected to the junction between the phase-shift networks. The arrangement provides a balanced or unbalanced hybrid circuit. Each phase-shift network can comprise a symmetrical polyphase network with cascaded network sections for handling voice frequency signals.

Abstract: A dial pulse detection circuit for partial correction of grossly distorted line current dial pulses, which provides square wave output signals for use by later timing detection circuitry. To detect such dial pulses, the present invention establishes an upper and a lower detection threshold. For a valid dial pulse to be detected, the line current must drop through both thresholds, and then rise again through at least the lower threshold. With the provision of a detection delay following detection of the leading edge of a dial pulse, the presence of a valid dial pulse can be registered. The present technique used in detecting the presence of dial pulses substantially reduces the chances of rejection of a valid dial pulse which has a grossly distorted waveform.