Light source device, light-emitting unit, and measurement apparatus
A light source device includes: a light-emitting section including a light-emitting element, the light-emitting element including a thyristor; a setter that sets the light-emitting element of the light-emitting section as a light-emitting element that emits light; and a controller that cancels an ON setting received from the setter after shifting the light-emitting element to a state in which the light-emitting element is able to emit light and that causes the light-emitting element to emit light multiple times by turning ON and OFF a light-emitting current, the light-emitting current causing the light-emitting element to emit light.
1. A light source device comprising:
a light-emitting section including a light-emitting element, the light-emitting element including a thyristor;
a setter that sets the light-emitting element of the light-emitting section as a light-emitting element that emits light; and
a controller that cancels an ON setting received from the setter after shifting the light-emitting element to a state in which the light-emitting element is able to emit light and that causes the light-emitting element to emit light a plurality of times by turning ON and OFF a light-emitting current, the light-emitting current causing the light-emitting element to emit light,
wherein the setter is constituted by thyristors,
wherein a substrate is provided, and the light-emitting element is provided as a result of sequentially stacking a surface emitting element and a thyristor on the substrate.
2. The light source device according to claim 1 , wherein a light-emission interval between light-emitting operations performed by the light-emitting element the plurality of times is set in accordance with a preset period for which the light-emitting element is ready to reemit light, the preset period starting after the light-emitting current supplied to the light-emitting element is turned OFF in a state in which the ON setting is not received from the setter.
3. A measurement apparatus comprising:
the light source device according to claim 2 ; and
a light receiver that receives light which is emitted from the light-emitting section of the light source device and which is reflected by a subject to be measured.
4. The light source device according to claim 1 , wherein, before canceling the ON setting received from the setter, the controller causes the light-emitting element to emit light at least one time.
5. A measurement apparatus comprising:
the light source device according to claim 4 ; and
a light receiver that receives light which is emitted from the light-emitting section of the light source device and which is reflected by a subject to be measured.
6. The light source device according to claim 1 , wherein:
the controller includes a driver that turns ON and OFF the light-emitting current at a ground side of a power source, the power source supplying the light-emitting current to the light-emitting element; and
an OFF-resistance of the driver is set in accordance with a preset period for which the light-emitting element is ready to reemit light, the preset period starting after the light-emitting current supplied to the light-emitting element is turned OFF.
7. The light source device according to claim 6 , wherein the OFF-resistance of the driver is formed by a driver element and a resistor disposed in parallel with the driver element.
8. A measurement apparatus comprising:
the light source device according to claim 7 ; and
a light receiver that receives light which is emitted from the light-emitting section of the light source device and which is reflected by a subject to be measured.
9. The light source device according to claim 6 , wherein the OFF-resistance of the driver is able to be switched between a plurality of values.
10. A measurement apparatus comprising:
the light source device according to claim 9 ; and
a light receiver that receives light which is emitted from the light-emitting section of the light source device and which is reflected by a subject to be measured.
11. A measurement apparatus comprising:
the light source device according to claim 6 ; and
a light receiver that receives light which is emitted from the light-emitting section of the light source device and which is reflected by a subject to be measured.
12. The light source device according to claim 1 , wherein the controller supplies a pulse having a current value smaller than a current value of the light-emitting current while the light-emitting element is emitting light the plurality of times or before the light-emitting element starts to emit light the plurality of times.
13. The light source device according to claim 1 , wherein:
the light-emitting element includes a plurality of light-emitting elements;
the setter is a shifter that performs a shift operation to set, among the plurality of light-emitting elements of the light-emitting section, a light-emitting element that emits light; and
the controller sets a shift signal, which is to be supplied to the shifter, to be a ground potential so as to change a state of the shifter to an OFF state.
14. A measurement apparatus comprising:
the light source device according to claim 1 ; and
a light receiver that receives light which is emitted from the light-emitting section of the light source device and which is reflected by a subject to be measured.
15. A light source device comprising:
a light-emitting section including a light-emitting element, the light-emitting element including a thyristor;
a setter that sets the light-emitting element of the light-emitting section as a light-emitting element that emits light; and
a controller that cancels an ON setting received from the setter after shifting the light-emitting element to a state in which the light-emitting element is able to emit light and that causes the light-emitting element to emit light a plurality of times by turning ON and OFF a light-emitting current, the light-emitting current causing the light-emitting element to emit light,
wherein the controller supplies a reemission stop pulse to the light-emitting section, the reemission stop pulse making the light-emitting element unable to reemit light.
16. The light source device according to claim 15 , wherein:
the controller includes a first driver and a second driver, the first driver turning ON and OFF the light-emitting current at a ground side of a power source, the power source supplying the light-emitting current to the light-emitting element, the second driver supplying the reemission stop pulse; and
an ON-resistance of the second driver is smaller than an OFF-resistance of the first driver and is set to a value which makes the light-emitting element become unable to reemit light when the second driver is turned ON while the first driver is OFF.
17. A light-emitting unit comprising:
a light-emitting section including a plurality of light-emitting elements, each of the plurality of light-emitting elements including a thyristor; and
a setter that sequentially transfers an ON state and that enters the ON state to set, among the plurality of light-emitting elements of the light-emitting section, a light-emitting element which emits light,
wherein a gate of the thyristor of each of the plurality of light-emitting elements is connected to a voltage supply line via a resistor, a light-emitting current being supplied to the light-emitting elements through the voltage supply line.
18. The light-emitting unit according to claim 17 , wherein the setter is constituted by thyristors.
19. The light-emitting unit according to claim 18 , wherein:
a substrate is provided; and
each of the plurality of light-emitting elements is provided as a result of sequentially stacking a surface emitting element and a thyristor on the substrate, the thyristor forming the thyristor of the corresponding light-emitting element, and the thyristors of the setter are provided on a structure on the substrate, the structure being equivalent to a structure of the light-emitting element.
20. The light-emitting unit according to claim 19 , wherein the light-emitting element and the thyristor of the setter are electrically isolated from each other.