Tdk Corporation

Mitsuyuki Tsujisaka

Kazunori Oshima

Hironobu Masuoka

Yukiharu Miyaoka

A light emitting element drive device with PWM dimming includes an LED module, a power conversion circuit that supplies electric power to the LED module, a dimming switch element that performs an open/close operation for a path in which a current flows in the LED module, and a voltage detection circuit that detects a voltage value of a voltage that is output from the power conversion circuit. When the dimming switch element is turned ON, a control circuit performs feedback control so as to make a current value of the current close to a first target value. When the dimming switch element is turned OFF, the control circuit performs feedback control so as to make the voltage value close to a second target value. Wherein, the first target value is a predetermined value and the second target value is set based on the voltage value.

Light emitting element drive device

A light emitting element drive device includes an electric conduction switch that is provided along a power input line, a voltage detection unit that detects a power source voltage containing a noise component when the electric power is supplied to the power input line, a conversion processing unit that converts the detected power source voltage containing the noise component to a digital value, a data generation unit that generates data of a predetermined number of bits, and a control unit that turns on the electric conduction switch. The control unit determines a delay time based on the predetermined number of bits. The delay time corresponds to a time between supplying the electric power to the power input line and turning on the electric conduction switch. The control unit turns on the electric conduction switch after the delay time passes. Thus, an excessive rush current is prevented.

Light emitting element drive device and lighting device

A power supply device includes a converter and an arithmetic circuit. The arithmetic circuit calculates a present control command value at predetermined intervals based on a digital value, which reflects an output voltage of a converter, from a conversion circuit. The arithmetic circuit calculates the difference value between the present control command value and a previous control command value. Based on the difference value, it is determined whether a signal output circuit outputs a high-level signal toward a charge terminal or a low-level signal toward a discharge terminal. As a result, the number of output lines corresponds to at least the number of charge terminals and discharge terminals. The above features can be achieved with a simple circuit configuration by adding a discharge and charge circuit and without increasing the number of output lines.

Power supply device and light-emitting element drive device

A power supply device includes a convertor and an arithmetic circuit. The convertor supplies electric power by performing an ON and OFF operation of a switching element. The arithmetic circuit calculates a control command value at predetermined intervals based on a digital value, which reflects an output voltage of the convertor, from a conversion circuit. Based on the control command value, a pulse signal generation circuit determines a duty ratio of a pulse signal to make the output voltage of the convertor stable. A driving signal with a finely adjusted duty ratio can be generated by an operation clock signal having a lower frequency than a conventional device. As a result, the number of output lines is appropriate if there is at least a single output line for the pulse signal from the pulse signal generation circuit.

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Tokyo, Japan

Mitsuyuki Tsujisaka