Abstract: A circuit board includes: an inductor and a control IC which are included in a switching power supply circuit; and a substrate having a first face, a second face on a reverse side of the first face, and an opening in a center portion of the substrate. The inductor is disposed on the first face, the control IC is disposed on the second face, and at least part of the inductor overlaps with at least part of the control IC when viewed from a direction perpendicular to the first face.

Abstract: A circuit board includes: an inductor and a control IC which are included in a switching power supply circuit; and a substrate having a first face, a second face on a reverse side of the first face, and an opening in a center portion of the substrate. The inductor is disposed on the first face, the control IC is disposed on the second face, and at least part of the inductor overlaps with at least part of the control IC when viewed from a direction perpendicular to the first face.

Abstract: A light-emitting device includes a light emission controller which causes first and second light-emitting element groups to emit light, by supplying undulating voltage to the first and second light-emitting element groups. The light emission controller supplies the undulating voltage to the first light-emitting element group during a first period in which a magnitude of the undulating voltage is greater than a first predetermined value and at most a second predetermined value. The second predetermined value is less than a maximum value of the undulating voltage. The light emission controller supplies the undulating voltage to the first and second light-emitting element groups during a second period in which the magnitude of the undulating voltage is greater than the second predetermined value. The second light-emitting element group surrounds the first light-emitting element group.

Abstract: A light-emitting device includes a light emission controller which causes first and second light-emitting element groups to emit light, by supplying undulating voltage to the first and second light-emitting element groups. The light emission controller supplies the undulating voltage to the first light-emitting element group, during a first period in which a magnitude of the undulating voltage is greater than a first predetermined value and at most a second predetermined value. The second predetermined value is less than a maximum value of the undulating voltage. The light emission controller supplies the undulating voltage to the first and second light-emitting element groups during a second period in which the magnitude of the undulating voltage is greater than the second predetermined value. The first light-emitting element group surrounds the second light-emitting element group.

Abstract: A lighting device which outputs a current to a solid-state light emitting element includes: a direct current-to-direct current (DC-to-DC) converter; and an output detector which detects an output from the DC-to-DC converter, wherein the DC-to-DC converter includes: a switching element; a control device which controls the switching element in order to generate the output; and a current detector which detects a current which flows through the switching element, and if a current value of the current detected by the current detector is less than a predetermined threshold, the control device controls the switching element according to a duty cycle determined based on an output value of the output detected by the output detector, and if the current value is greater than the predetermined threshold, the control device controls the switching element according to a duty cycle lower than the duty cycle determined based on the output value.

Abstract: A lighting device which outputs a current to a solid-state light emitting element includes: a direct current-to-direct current (DC-to-DC) converter; and an output detector which detects an output from the DC-to-DC converter, wherein the DC-to-DC converter includes: a switching element; a control device which controls the switching element in order to generate the output; and a current detector which detects a current which flows through the switching element, and if a current value of the current detected by the current detector is less than a predetermined threshold, the control device controls the switching element according to a duty cycle determined based on an output value of the output detected by the output detector, and if the current value is greater than the predetermined threshold, the control device controls the switching element according to a duty cycle lower than the duty cycle determined based on the output value.