Light-emitting device and camera
A small light-emitting device is provided. A light-emitting device which is less likely to produce a shadow is provided. A structure including a switching circuit for supplying a pulsed constant current and a light-emitting panel supplied with the pulsed constant current has been conceived.
1. A light-emitting device comprising:
a battery for supplying a first voltage;
a first DC-DC converter configured to be supplied with the first voltage and configured to supply a second voltage higher than the first voltage;
a capacitor configured to be supplied with the second voltage;
a second DC-DC converter configured to be supplied with power from the capacitor and configured to supply a constant current;
a switching circuit configured to be supplied with the constant current and a control pulse signal and configured to supply a constant current pulse;
a constant current power source configured to supply the constant current;
a driver circuit configured to supply the control pulse signal, the driver circuit comprising a start switch; and
a light-emitting panel configured to be supplied with the constant current pulse,
wherein the driver circuit outputs the control pulse signal in response to a switching operation of the start switch so that the switching circuit supplies a constant current with a half width of more than or equal to 1 millisecond and less than or equal to 1000 milliseconds.
2. The light-emitting device according to claim 1 ,
wherein the light-emitting panel comprises a support substrate and a light-emitting element extending in a planar manner over the support substrate, and
wherein the light-emitting element comprises a first electrode on a support substrate side, a second electrode overlapping with the first electrode, and an EL layer between the first electrode and the second electrode.
3. The light-emitting device according to claim 1 ,
wherein the light-emitting panel comprises a curved surface, a support substrate having flexibility, and a light-emitting element extending in a planar manner over the support substrate, and
wherein the light-emitting element comprises a first electrode on a support substrate side, a second electrode overlapping with the first electrode, and an EL layer between the first electrode and the second electrode.
4. A camera or a digital still camera comprising the light-emitting device according to claim 1 .
5. A light-emitting device comprising:
a switching circuit configured to be supplied with a constant current and a control pulse signal and configured to supply a constant current pulse;
a constant current power source configured to supply the constant current;
a driver circuit configured to supply the control pulse signal, the driver circuit comprising a start switch;
a counter circuit configured to count the number of times the driver circuit supplies the control pulse signal; and
a light-emitting panel configured to be supplied with the constant current pulse,
wherein the driver circuit outputs the control pulse signal in response to a switching operation of the start switch so that the switching circuit supplies a constant current with a half width of more than or equal to 1 millisecond and less than or equal to 1000 milliseconds.
6. The light-emitting device according to claim 5 ,
wherein the light-emitting panel comprises a support substrate and a light-emitting element extending in a planar manner over the support substrate, and
wherein the light-emitting element comprises a first electrode on a support substrate side, a second electrode overlapping with the first electrode, and an EL layer between the first electrode and the second electrode.
7. The light-emitting device according to claim 5 ,
wherein the light-emitting panel comprises a curved surface, a support substrate having flexibility, and a light-emitting element extending in a planar manner over the support substrate, and
wherein the light-emitting element comprises a first electrode on a support substrate side, a second electrode overlapping with the first electrode, and an EL layer between the first electrode and the second electrode.
8. The light-emitting device according to claim 5 ,
wherein the constant current power source comprises:
an AC-DC converter for supplying a direct current; and
a DC-DC converter configured to be supplied with the direct current and configured to supply the constant current.
9. A camera or a digital still camera comprising the light-emitting device according to claim 5 .
10. A light-emitting device comprising:
a battery for supplying a first voltage;
a first DC-DC converter configured to be supplied with the first voltage and configured to supply a second voltage higher than the first voltage;
a capacitor configured to be supplied with the second voltage;
a second DC-DC converter configured to be supplied with power from the capacitor and configured to supply a constant current;
a switching circuit configured to be supplied with the constant current and a control pulse signal and configured to supply a constant current pulse;
a constant current power source configured to supply the constant current;
a driver circuit configured to supply the control pulse signal, the driver circuit comprising a start switch;
a counter circuit configured to count the number of times the driver circuit supplies the control pulse signal; and
a light-emitting panel configured to be supplied with the constant current pulse,
wherein the driver circuit outputs the control pulse signal in response to a switching operation of the start switch so that the switching circuit supplies a constant current with a half width of more than or equal to 1 millisecond and less than or equal to 1000 milliseconds.
11. The light-emitting device according to claim 10 ,
wherein the light-emitting panel comprises a support substrate and a light-emitting element extending in a planar manner over the support substrate, and
wherein the light-emitting element comprises a first electrode on a support substrate side, a second electrode overlapping with the first electrode, and an EL layer between the first electrode and the second electrode.
12. The light-emitting device according to claim 10 ,
wherein the light-emitting panel comprises a curved surface, a support substrate having flexibility, and a light-emitting element extending in a planar manner over the support substrate, and
wherein the light-emitting element comprises a first electrode on a support substrate side, a second electrode overlapping with the first electrode, and an EL layer between the first electrode and the second electrode.
13. A camera or a digital still camera comprising the light-emitting device according to claim 10 .