Lighting device and luminaire using the same

1. A lighting device for lighting a solid light-emitting element, comprising:

a DC power source circuit configured to output DC power;

a power conversion circuit including a semiconductor element connected between output terminals of the DC power source circuit, the power conversion circuit configured to supply power to the solid light-emitting element through a control of a conduction state of the semiconductor element;

a first control circuit configured to control an output of the DC power source circuit; and

a second control circuit configured to control an output of the power conversion circuit by controlling the conduction state of the semiconductor element; a short-circuit detection circuit configured to detect a short-circuit in the semiconductor element,

wherein the first control circuit reduces the output of the DC power source circuit when the short-circuit detection circuit detects the short-circuit in the semiconductor element,

wherein the semiconductor element is a switching element, switching of the switching element being controlled by the second control circuit,

wherein the power conversion circuit is a chopper circuit that supplies a desired power to the solid light-emitting element through a control of current flowing in the switching element,

wherein, the lighting device further comprises;

a current detection circuit configured to detect a current flowing in the switching element; and

a timer configured to start to count when the second control circuit outputs an on-signal to turn on the switching element, and configured to reset a counted value when a detection result by the current detection circuit reaches a predetermined value, and

wherein the short-circuit detection circuit determines that the switching element is in a short-circuit state if the counted value by the timer exceeds a threshold value.

2. A luminaire, comprising:

the lighting device of claim 1 ; and

the solid light-emitting element to be powered by the lighting device.

3. A lighting device for lighting a solid light-emitting element, comprising:

a DC power source circuit configured to output DC power;

a power conversion circuit including a semiconductor element connected between output terminals of the DC power source circuit, the power conversion circuit configured to supply power to the solid light-emitting element through a control of a conduction state of the semiconductor element;

a first control circuit configured to control an output of the DC power source circuit; and

a second control circuit configured to control an output of the power conversion circuit by controlling the conduction state of the semiconductor element; a short-circuit detection circuit configured to detect a short-circuit in the semiconductor element,

wherein the first control circuit reduces the output of the DC power source circuit when the short-circuit detection circuit detects the short-circuit in the semiconductor element,

wherein the semiconductor element is a switching element, switching of the switching element being controlled by the second control circuit,

wherein the power conversion circuit is a chopper circuit that supplies a desired power to the solid light-emitting element through a control of current flowing in the switching element,

wherein, the lighting device further comprises;

a current detection circuit; and

a timer configured to measure time,

wherein the chopper circuit includes an inductor, in which the solid light-emitting element, the inductor and the switching element are connected in series to one another between the output terminals of the DC power source circuit;

wherein the current detection circuit detects current flowing in the inductor;

wherein the timer starts to count when the control circuit outputs an on-signal to turn on the switching element and resets a counted value when a detection result by the current detection circuit becomes lower than a predetermined value; and

wherein the short-circuit detection circuit determines that the switching element is in a short-circuit state if the counted value by the timer exceeds a threshold value.

4. A luminaire, comprising:

the lighting device of claim 3 ; and

the solid light-emitting element to be powered by the lighting device.

5. A lighting device for lighting a solid light-emitting element, comprising:

a DC power source circuit configured to output DC power;

a power conversion circuit including a semiconductor element connected between output terminals of the DC power source circuit, the power conversion circuit configured to supply power to the solid light-emitting element through a control of a conduction state of the semiconductor element;

a first control circuit configured to control an output of the DC power source circuit; and

a second control circuit configured to control an output of the power conversion circuit by controlling the conduction state of the semiconductor element; a short-circuit detection circuit configured to detect a short-circuit in the semiconductor element,

wherein the first control circuit reduces the output of the DC power source circuit when the short-circuit detection circuit detects the short-circuit in the semiconductor element,

wherein the semiconductor element is a switching element, switching of the switching element being controlled by the second control circuit,

wherein the power conversion circuit is a chopper circuit that supplies a desired power to the solid light-emitting element through a control of current flowing in the switching element,

wherein, the lighting device further comprises;

a voltage detection circuit configured to detect an output voltage of the DC power source circuit,

wherein the chopper circuit includes an inductor, in which the solid light-emitting element, the inductor and the switching element are connected in series to one another between the output terminals of the DC power source circuit; and

wherein the short-circuit detection circuit determines that the switching element is in a short-circuit state if a detection result by the voltage detection circuit is less than threshold value while the second control circuit outputs an off-signal to turn off the switching element.

6. A luminaire, comprising:

the lighting device of claim 5 ; and

the solid light-emitting element to be powered by the lighting device.