Abstract: A method and apparatus is described for compressing an optical pulse period of an optical pulse signal. The apparatus comprises at least one optical circuit each including optical delay means for delaying an-input optical signal to generate a first delayed optical signal, optical guiding means for guiding the first delayed optical signal to the optical delay means, and optical coupling means for coupling optical signals. The optical delay means delays the first delayed optical signal to generate a second delayed optical signal. The optical coupling means couples the second delayed optical signal with the input optical signal.

Abstract: An apparatus and a method are described for compressing/expanding a pulse period of an optical pulse or packet signal. The apparatus includes a chirp light generator for generating a chirp light of a wavelength which changes linearly from a first predetermined wavelength to a second predetermined wavelength for every predetermined number of pulses of the optical signal, a wavelength converter for generating a wavelength-converted optical signal by wavelength-converting the optical signal with the chirp light, and a wavelength dispersion device causes a propagation delay due to the wavelength dispersion to the wavelength-converted optical signal.

Abstract: To achieve an optical RZ signal generator having a simple constitution in which the number of components is significantly reduced in comparison with a conventional one, an optical RZ signal generator according to the present invention comprises a steady-state power laser light source 103 and a Mach-Zehnnder optical modulator 104 for performing intensity modulation on the basis of an electric signal supplied from an electric data signal input terminal 101 with being connected to an output of the steady-state power laser light source 103. The electric signal is a binary voltage signal and insertion loss of the Mach-Zehnnder optical modulator is preset so as to shift from a first state to a second state other than the first one and then returns to the first state in a logic level transition process of the binary voltage signal.

Abstract: A synthesized oscillation circuit that can relax a limitation of the maximum operational frequency. A mixer (MX), a bandpass filter (BPF), an amplitude limiting amplifier (LIM), a phase detector (PD), a low-pass filter (LPF), and a voltage-controlled oscillator (VCO) are serially connected between a signal input terminal (IN) and a signal output terminal (OUT). The signal output terminal (OUT) is connected the mixer (MX) and the phase detector (PD). The bandpass filter (BPF) has a filtering characteristic which blocks the sum frequency component of the frequency component of an input signal from the signal input terminal (IN) to the mixer (MX) and the frequency component of an output signal from the voltage-controlled oscillator (VCO) to the mixer (MX), but which passes the difference frequency component between them.

Abstract: In a frequency-dividing circuit for producing an output having a frequency half that of its input, a pair of terminals of a latch circuit are connected to input terminals of a pair of amplify/delay means, and are also connected to receive through a pair of transistors, the outputs of the amplify/delay means. A single-phase input signal is input to the control electrodes of the transistors to turn on and off the transistors. When the transistors are turned from off to on, the output states of the amplify/delay means are transferred through the transistors to invert the latch circuit, and the states of complementary terminals of the latch circuits are in turn transferred through the amplify/delay means to invert the output states of the outputs of the amplify/delay means. When the transistors are turned from on to off, no change occurs in the states of the circuit. In this way, the states of the circuit are inverted each time the transistors are turned from off to on.

Abstract: A flip-flop circuit comprises a first transfer gate receiving input data and being conductive responsive to a clock signal, a second transfer gate receiving an inverted input data and being conductive responsive to said clock signal, a third transfer gate receiving said input data and being conductive responsive to an inverted clock signal, and a fourth transfer gate receiving said inverted input data and being conductive responsive to said inverted clock signal. First and second inverters are cross-coupled across output nodes of said first and second transfer gates to serve as a latch circuit. Third and fourth inverters are cross-coupled across output nodes of said third and fourth transfer gates to serve as a latch circuit. A selector selects either the outputs of the first and second transfer gates, or the outputs of the third and fourth transfer gates, as output data and inverted output data of the flip-flop circuit, in accordance with said clock and inverted clock signals.

Abstract: A flip-flop circuit comprises two basic flip-flop circuits, four field effect transistors, and four amplifiers. The two basic flip-flop circuits respectively composed of a first and a second inverter circuits, and an output terminal of the first inverter circuit is connected to an input terminal of the second inverter circuit and an output terminal of the second inverter circuit is connected to the input terminal of the first inverter circuit. The field effect transistors have sources respectively connected to input terminals of the two basic flip-flop circuits, and gates to which clock pulses and inverse clock pulses are applied. The amplifiers respectively composed of an inverter circuit are connected to output terminals of the two basic flip-flop circuits.

Abstract: A system for controlling air-fuel ratio for a carburetor for an internal combustion engine having an induction passage, a throttle valve, an exhaust passage, an exhaust gas detector such as oxygen sensor for detecting the concentration of oxygen in the exhaust gases, air-fuel mixture supply means, an on-off electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply means and an electronic controller. The electronic controller comprises a comparing circuit for comparing the output signal of the detector with a stoichiometric reference, an integration circuit connected to the comparing circuit, a triangular wave pulse generator, and a driving circuit for producing square wave pulses for driving the on-off electromagnetic valve means from the output signal of the integration circuit and of the triangular wave pulse generator for controlling the air-fuel ratio to a value approximately equal to the stoichiometric air-fuel ratio.

Abstract: A system for regulating the engine speed so as to maintain the voltage between terminals of a battery at a constant value. A constant-voltage circuit is connected at a terminal of the battery for supplying a constant voltage. A comparator is provided for comparing the voltage between the terminals of the battery with the constant voltage and for producing an output signal in dependency on the difference between the input voltages thereto. The output signal is fed to an actuator through a driving circuit. The actuator operates in response to the driving signal from the driving circuit for opening or closing the throttle valve for regulating the engine speed, so that the voltage between the terminals of the battery may be maintained at a constant level.

Abstract: A system for controlling cooling water temperature for a water-cooled engine has an intake passage, a radiator, a water jacket provided in the engine for cooling the engine, a water passage for communicating the water jacket with the radiator, a thermostat provided in the water passage, the thermostat being so arranged as to open the water passage when the water temperature exceeds a predetermined value, and a pump causing the cooling water in the water jacket to flow. There is provided a bypass connected between the outlet of the water jacket and the inlet of the pump, and a circulation pipe connected between the outlet and inlet of the pump. A solenoid valve is provided for selectively connecting the water passage and circulation pipe with the inlet of the pump and a flow control valve is provided in the water passage for controlling flow rate of water.

Abstract: A system for regulating the engine speed of an internal combustion engine having a carburetor and a throttle valve in the carburetor. The system comprises an electro-mechanical actuator having an electric motor and a push rod engaged with a throttle lever for maintaining the throttle valve to an open state, a speed sensor for detecting the speed of the engine, and an electronic control circuit. A detecting means is provided for producing a pulse train according to the number of the rotations of the electric motor. The electronic control circuit comprises a comparing circuit connected to the speed sensor, a level setting circuit for applying a standard level to the comparing circuit for comparing the output of the speed sensor with the standard level, a counter for counting the output of the detecting means, and a control circuit for producing a pair of output signals in dependency on the outputs of the comparing circuit and of the counter.

Abstract: A system for controlling air-fuel ratio for an internal combustion engine having a two-barrel carburetor. An electronic controller compares the output signal of an O.sub.2 sensor with a reference corresponding to stoichiometry and for operating on-off electromagnetic valve(s) for controlling the air-fuel ratio to a value approximately equal to the stoichiometric air-fuel ratio. A constant signal generating circuit is selectively connected to the electronic controller. An engine operation detector is provided for detecting the transition from a heavy load condition to light load condition for producing a signal. A switching circuit operatively connects the constant signal generating circuit to the electronic controller for providing a fixed duty ratio of the valve, and renders the electronic controller non-responsive to the output of the O.sub.2 sensor. A switch actuating circuit is provided to actuate the switch by the output signal of the engine operation detector for a predetermined period.

Abstract: A system for regulating the engine speed of an internal combustion engine having a carburetor and a throttle valve in the carburetor. The system comprises an electro-mechanical actuator having a push rod engaged with a throttle lever for maintaining the throttle valve to an open state, a speed sensor for detecting the speed of engine, and an electronic control circuit. The electronic control circuit comprises a comparing circuit connected to the speed sensor, a level setting circuit for applying a standard level to the comparing circuit for comparing the output of the speed sensor with the standard level, and a control circuit for producing a pair of output signals for a time period in dependency on the output of the comparing circuit.

Abstract: A system for controlling air-fuel ratio for a carburetor for an internal combustion engine having an intake passage, on air-fuel mixture supply device, a throttle valve, an exhaust passage, a detector such as an oxygen sensor for detecting the concentration of oxygen in the exhaust gases, an on-off type electromagnetic valve for correcting the air-fuel mixture and an electronic controller.The electronic controller comprises a comparing circuit for comparing the output signal of the detector with a reference, a proportional and integration circuit for producing a control signal connected to the comparing circuit, a triangular wave pulse generator, and a driving circuit for producing square wave pulses for driving the on-off type electromagnetic valve from the control signals of the proportional and integration circuit and of the triangular wave pulse, generator for controlling the air-fuel ratio to a valve approximately equal to the stoichiometric air-fuel ratio.

Abstract: A system for controlling the air-fuel ratio for an internal combustion engine having a detector for detecting the concentration of a constituent of exhaust gases passing through the exhaust passage, air-fuel mixture supply device for supplying an air fuel mixture to the induction passage, electromagnetic valves for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply device, a comparator for comparing the output signal of the detector with respect to a predetermined value, an integrating circuit having a proportional circuit for integrating the output of the comparator, a driving circuit for driving the electromagnetic valves in dependency upon the output signal of the integrating circuit.