Control circuit of light-emitting element
View Patent ↗A control circuit of a light-emitting element comprises a rectifying unit ( 30 ), a switching element ( 38 ), a transformer ( 48 ) having a first winding (L 1 ) which generates a magnetic field using a current controlled by switching of the switching element ( 38 ), a second winding (L 2 ) which is magnetically coupled to the first winding (L 1 ) and which generates a current flowing to an LED ( 102 ), and a third winding (L 3 ) which is magnetically coupled to the first winding (L 1 ) and which generates a voltage (Sfbk), and an averaging capacitor ( 32 ) which averages a voltage derived by superposing a voltage (Srec) rectified by the rectifying unit ( 30 ) and the voltage (Sfbk), and a voltage averaged by the averaging capacitor ( 32 ) is applied to the first winding (L 1 ), so that light is emitted from the LED ( 102 ).
1. A control circuit of a light-emitting element, comprising:
a rectifying unit which full-wave rectifies an alternating current power supply;
a switching element;
a feedback voltage generating unit comprising a transformer having a first winding which generates a magnetic field using a current controlled by switching of the switching element, a second winding which is magnetically coupled to the first winding and which generates a current flowing to the light-emitting element, and a third winding which is magnetically coupled to the first winding and which generates a feedback voltage;
a reference voltage generating unit which divides a voltage rectified by the rectifying unit and generates a reference voltage;
a comparator which compares a comparative voltage corresponding to a current flowing to the first winding and the reference voltage and outputs a control signal which controls the switching of the switching element according to a comparison result; and
an averaging capacitor which averages a voltage derived by superposing the voltage rectified by the rectifying unit and the feedback voltage, wherein
a voltage averaged by the averaging capacitor is applied to the first winding, so that light is emitted from the light-emitting element.
2. A control circuit of a light-emitting element, comprising:
a rectifying unit which full-wave rectifies an alternating current power supply;
a switching element which switches a current flowing to the light-emitting element;
a feedback voltage generating unit comprising a transformer having a first winding which generates a magnetic field using the current flowing to the light-emitting element, and a second winding which is magnetically coupled to the first winding and which generates a feedback voltage;
a reference voltage generating unit which divides a voltage rectified by the rectifying unit and generates a reference voltage;
a comparator which compares a comparative voltage corresponding to the current flowing to the light-emitting element and the reference voltage and outputs a control signal which controls the switching of the switching element according to a comparison result; and
an averaging capacitor which averages a voltage derived by superposing the voltage rectified by the rectifying unit and the feedback voltage, wherein
a voltage averaged by the averaging capacitor is applied to the light-emitting element, so that light is emitted from the light-emitting element.
3. The control circuit of the light-emitting element according to claim 1 , further comprising
an extraction circuit which extracts charge from a dimmer including a triac which adjusts a conduction angle of the alternating current power supply.
4. The control circuit of the light-emitting element according to claim 2 , further comprising
an extraction circuit which extracts charge from a dimmer including a triac which adjusts a conduction angle of the alternating current power supply.