Current-limiting device and light-emitting diode apparatus containing the same

摘要

An LED apparatus includes an LED component and a current-limiting device. The LED component includes at least one LED having a corresponding current-limiting resistance value. The current-limiting device includes a plurality of PTC devices connected in series. The plurality of PTC devices are capable of effectively sensing the temperature of the LED and are electrically coupled to the LED component. The resistance value of the current-limiting device increases with the increment of sensed temperature. The current-limiting device has a resistance close to or equal to the current-limiting resistance value at a temperature at which the LED operates normally. When the temperature of the LED gradually increases to an abnormal temperature, current allowable to be flowed through the current-limiting device gradually decreases to be lower than LED operating current.

主权项

1. An LED apparatus; comprising:
an LED component corresponding to a current-limiting resistance value and comprising at least one LED of a forward voltage and an operating current; and a current-limiting device comprising a plurality of positive temperature coefficient devices merely connected in series, the positive temperature coefficient devices being capable of sensing temperature of the LED and electrically coupled to the LED component; wherein a resistance value of the current-limiting device increases with increasing sensed temperature, the resistance value of the current-limiting device at an LED normal operating temperature is close to or equal to the current-limiting resistance value; when the temperature of the LED gradually increases to an abnormal temperature, current allowable to be flowed through the current-limiting device gradually decreases to be lower than the operating current, wherein the plurality of positive temperature coefficient devices have yet to reach a trip temperature thereof when the at least one LED increases to the abnormal temperature.