Lighting device and luminaire using the same

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.

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.