Drive circuit and light emitting device

A drive circuit configured to generate an output current for driving a light emitting element, comprising:

• a power source;
• two or more current control units configured to control an amount of current supplied to the light emitting element in accordance with a pulse modulation signal;
• and
• a calculation unit configured to change a duty ratio of the pulse modulation signal, wherein
• each of the two or more current control units includes
• a switching element configured to be switched on or off in accordance with the pulse modulation signal,
• an inductor, and
• a diode configured to limit flow of a current from the inductor to ground,
• wherein
• the switching element and the inductor are serially connected between the power source and the light emitting element,
• the diode is connected between the ground and a contact point of the switching element and the inductor,
• the two or more current control units are connected in parallel, and
• the calculation unit is configured to individually stop at least a first current control unit among the two or more current control units.

A drive circuit configured to generate an output current for driving a light emitting element, comprising:

• a power source;
• two or more current control units configured to control an amount of current supplied to the light emitting element in accordance with a pulse modulation signal;
• and
• a calculation unit configured to change a duty ratio of the pulse modulation signal, wherein
• each of the two or more current control units includes,
• a first switching element configured to be switched on or off in accordance with the pulse modulation signal,
• a second switching element configured to be switched on or off in accordance with an inversion signal of the pulse modulation signal input to the first switching element, and
• an inductor,
• the first switching element and the inductor are serially connected between the power source and the light emitting element,
• the second switching element is connected between ground and a contact point of the first switching element and the inductor,
• the two or more current control units are connected in parallel, and
• the calculation unit is configured to adjust the duty ratio in accordance with the output current, a voltage of the power source, a number of the two or more current control units, an internal resistance of the two or more current control units, an internal resistance of the light emitting element, and a threshold voltage due to a potential barrier of the light emitting element.