Stanley Electric Co., Ltd

Takashi Fujino

Shigeru Murata

Kazuaki Ashinuma

An LED vehicle lighting apparatus including a fail-safe function can supply a plurality of LEDs connected in series with a requisite voltage that is larger than a supply voltage of a battery. The vehicle lighting apparatus can include a DC-DC convertor and a subsidiary feed circuit. The DC-DC convertor can be configured to supply the LEDs with a substantially constant current by a controller. At least one output of the subsidiary feed circuit is connected to an LED in the LEDs, and a switching element can also be connected between the LED and ground. When the controller has a breakdown or trouble, LEDs between the LED and ground can be directly lighted by the battery in accordance with a signal provided by the controller. Thus, the disclosed subject matter can provide various LED lighting apparatuses including a user friendly fail-safe function.

LED vehicle lighting apparatus

An LED drive circuit of the disclosed subject matter can include an LED unit and a serial circuit connected in parallel therewith. The serial circuit includes a resistor and a positive temperature coefficient resistor having a positive linear temperature coefficient. A voltage across the positive temperature coefficient resistor is fed back to an output control circuit. An output voltage that is PWM-controlled on the basis of a reference voltage set at the output control circuit is used to drive the LED unit.

LED drive circuit

An LED lighting apparatus can be configured to supply a number of LEDs connected in series with a requisite voltage and power even if an amount of forward voltage of the LEDs connected in series is larger than a supply voltage of a battery. The LED lighting apparatus can include a boosting circuit and an inverted boosting circuit. LEDs can be connected between outputs of the boosting circuit and the inverted boosting circuit. The LED lighting apparatus can also include a current detection circuit configured to detect an LED current, and can include a dual PWM control IC configured to control the boosting circuit and the inverted boosting circuit in accordance with the LED current detected by the current detection circuit so as to keep the LED current substantially constant. The LED lighting apparatus can include a shutdown circuit to stop supplying a power supply when a load that includes the LEDs is in a circuit that is either opened or shorted.

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Tokyo, Japan

Takashi Fujino