Abstract: An LED driving circuit is provided for making it possible to economically drive a serially connected LED circuit by means of a switching device with a relatively low withstanding voltage even if the number of serially connected LED devices increases. In an LED driving circuit provided with a serially connected LED circuit (11) in which many LED devices are serially connected and a switching device (13) serially connected with the serially connected LED circuit (11) to control that an electrical current flowing through the serially connected LED circuit (11) is turned on or off, wherein a circuit device (15), which comprises a resistor, a constant voltage diode, a constant current diode, or the like, is connected in parallel with the switching device to make a minute current flow through the serially connected LED circuit (11) to the extent that the LED devices are not turned on when the switching device is turned off.

Abstract: An LED driving circuit is provided for making it possible to economically drive a serially connected LED circuit by means of a switching device with a relatively low withstanding voltage even if the number of serially connected LED devices increases. In an LED driving circuit provided with a serially connected LED circuit (11) in which many LED devices are serially connected and a switching device (13) serially connected with the serially connected LED circuit (11) to control that an electrical current flowing through the serially connected LED circuit (11) is turned on or off, wherein a circuit device (15), which comprises a resistor, a constant voltage diode, a constant current diode, or the like, is connected in parallel with the switching device to make a minute current flow through the serially connected LED circuit (11) to the extent that the LED devices are not turned on when the switching device is turned off.

Abstract: An emergency electric power supply unit (9) for backing up the main electric power supply system (1, 10) at the time of the malfunction of the main electric power supply system (1, 10) which includes an industrial apparatus operated by cooperatively controlling an auxiliary machinery (2) operated by the electric power supplied from the main electric power supply system (1, 10), an auxiliary electric power supply (20) for storing the electric power, a charging circuit (21) for charging the electric power supplied from the main electric power supply (1) in the auxiliary electric power supply (20), a discharging circuit (22) for supplying the electric power charged in the auxiliary electric power supply (20) to the auxiliary machinery (2), and an emergency controlling circuit (40) for controlling the discharging circuit (22) so that the electric power from the auxiliary electric power supply (20) is supplied to the auxiliary machinery (2) at the time of the malfunction of the main electric power supply system (1

Abstract: An emergency electric power supply unit (9) for backing up the main electric power supply system (1, 10) at the time of the malfunction of the main electric power supply system (1, 10) which includes an industrial apparatus operated by cooperatively controlling an auxiliary machinery (2) operated by the electric power supplied from the main electric power supply system (1, 10), an auxiliary electric power supply (20) for storing the electric power, a charging circuit (21) for charging the electric power supplied from the main electric power supply (1) in the auxiliary electric power supply (20), a discharging circuit (22) for supplying the electric power charged in the auxiliary electric power supply (20) to the auxiliary machinery (2), and an emergency controlling circuit (40) for controlling the discharging circuit (22) so that the electric power from the auxiliary electric power supply (20) is supplied to the auxiliary machinery (2) at the time of the malfunction of the main electric power supply system (1

Abstract: A plastic card mounting an IC memory of a credit card size called a music card stores encoded digital music information including tone, musical interval, musical length and loudness of each musical note and pause, and said music information actuates a synthesizer which generates music sound signal. The music card also stores a character code for indicating title of music on said synthesizer. As music note is encoded and stored in a digital form, a small capacity of IC memory is enough for storing a long play music.

Abstract: An improved telephone answering and message recording system (100) having a microphone (4), an analog-digital converter (6) for converting the analog speech signal of the microphone (4) to a digital signal, a digital memory (M.sub.1, M.sub.2, M.sub.3, M.sub.4, MEM.sub.1 -MEM.sub.n) for storing the digital speech signal of the analog-digital converter (6), a digital-analog converter (7) for re-converting the digital signal of the output of the memory to an analog signal, and a speaker (5) coupled with the output of said digital-analog converter (7). The system has further a PB (push button) receiver (40) for detecting a PB code which is composed of the combination of two frequencies, and the operational mode and/or the memory to record or reproduce a speech is switched by the particular PB code.

Abstract: A circuit for preventing a telephone set from being used without approval, the telephone set including a handset, telephone lines coupled to the handset, a dial pulse signal generator and hookswitches for coupling the telephone lines to the handset and for cooperating with the handset. A circuit is provided for converting the dial pulse signals into a binary code, a prohibit circuit is provided for generating a prohibit signal which prohibits a telephone call when the binary codes corresponding to prohibited dial numbers are input thereto, and an unlock circuit is provided for generating during a predetermined period a control signal which allows a telephone call when the binary codes corresponding to secret dial numbers are input thereto. A transfer switching means is provided for selectively coupling the converting circuit to either the prohibit circuit or to the unlock circuit and for cooperating with the hookswitches.

Abstract: Light emitting elements such as light emitting diodes provided in the viewfinder of a camera are connected with a light measuring circuit including a photodetector through an A-D converter, a decoder and a gate circuit so that the light emitting elements may indicate exposure information in a digital form in accordance with the output of the light measuring circuit. An oscillator is connected with the A-D converter and the gate circuit for giving sampling pulses to the A-D converter and clock pulses to the gate circuit. Between the oscillator and the gate circuit is provided a duty modulator to change the duty cycle of the square wave transmitted from the oscillator to the gate circuit. The duty modulator is connected with the light measuring circuit or the A-D converter so as to control the duty cycle of the square wave in accordance with the output from the light measuring circuit.

Abstract: An exposure indicating means comprising a plurality of light emitting elements which are selectively energized to indicate exposure information in a digital form is connected with an exposure measuring circuit. The light emitting elements are connected with a warning circuit. The warning circuit comprises a warning signal generator which generates a warning signal when a warning is required, a square wave generator which constantly generates a square wave and an AND circuit which transmits the square wave to the light emitting elements when the warning signal is transmitted thereto. The light emitting elements are intermittently turned off by the square wave coming from the AND circuit. The frequency of the square wave is selected so that the intermittent turning off of the light emitting elements is sensed by the photographer viewing through the viewfinder of the camera.

Abstract: An accurate, simple and compact analog-to-digital converter has been found. The converter comprisesA voltage divider circuit including a plurality of stepped voltage dividing points separated by a plurality of resistors for dividing the input voltage received from the analog input terminal;A group of switches for receiving said divided voltages; andA switching decision circuit for determining the amplitude of the voltage from a decision point through said switch group, the output of said decision circuit being applied to a logic circuit to provide digital signal output.