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US 9,368,936 B1Granted
Laser diode firing system
AssigneeGoogle Inc.
InventorsSamuel William Lenius, Pierre-yves Droz
Life of this patent
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Abstract
A laser diode firing circuit for a light detection and ranging device is disclosed. The firing circuit includes a laser diode coupled in series to a transistor, such that current through the laser diode is controlled by the transistor. The laser diode is configured to emit a pulse of light in response to current flowing through the laser diode. The firing circuit includes a capacitor that is configured to charge via a charging path that includes an inductor and to discharge via a discharge path that includes the laser diode. The transistor controlling current through the laser diode can be a Gallium nitride field effect transistor.
Claims20
An apparatus, comprising:
- a voltage source;
- an inductor coupled to the voltage source, wherein the inductor is configured to store energy in a magnetic field;
- a diode coupled to the voltage source via the inductor;
- a transistor configured to be turned on and turned off by a control signal;
- a light emitting element coupled to the transistor;
- a capacitor coupled to a charging path and a discharge path, wherein the charging path includes the inductor and the diode, and wherein the discharge path includes the transistor and the light emitting element;
- wherein, responsive to the transistor being turned off, the capacitor is configured to charge via the charging path such that a voltage across the capacitor increases from a lower voltage level to a higher voltage level and the inductor is configured to release energy stored in the magnetic field such that a current through the inductor decreases from a higher current level to a lower current level;
- and
- wherein, responsive to the transistor being turned on, the capacitor is configured to discharge through the discharge path such that the light emitting element emits a pulse of light and the voltage across the capacitor decreases from the higher voltage level to the lower voltage level and the inductor is configured to store energy in the magnetic field such that the current through the inductor increases from the lower current level to the higher current level.
6 more elements
A method, comprising:
- turning off a transistor, wherein the transistor is coupled to a light emitting element, wherein both the transistor and the light emitting element are included in a discharge path coupled to a capacitor, wherein the capacitor is also coupled to a charging path including a diode and an inductor, wherein the inductor is configured to store energy in a magnetic field, wherein the diode is coupled to a voltage source via the inductor, and wherein, responsive to the transistor being turned off, the capacitor is configured to charge via the charging path such that a voltage across the capacitor increases from a lower voltage level to a higher voltage level and the inductor is configured to release energy stored in the magnetic field such that a current through the inductor decreases from a higher current level to a lower current level;
- and
- turning on the transistor, wherein responsive to the transistor being turned on, the capacitor is configured to discharge through the discharge path such that the light emitting element emits a pulse of light and the voltage across the capacitor decreases from the higher voltage level to the lower voltage level and the inductor is configured to store energy in the magnetic field such that the current through the inductor increases from the lower current level to the higher current level.
A light detection and ranging (LIDAR) device comprising:
- a light source including:
- a voltage source;
- an inductor coupled to the voltage source, wherein the inductor is configured to store energy in a magnetic field;
- a diode coupled to the voltage source via the inductor;
- a transistor configured to be turned on and turned off by a control signal;
- a light emitting element coupled to the transistor;
- a capacitor coupled to a charging path and a discharge path, wherein the charging path includes the inductor and the diode, and wherein the discharge path includes the transistor and the light emitting element;
- wherein, responsive to the transistor being turned off, the capacitor is configured to charge via the charging path such that a voltage across the capacitor increases from a lower voltage level to a higher voltage level and the inductor is configured to release energy stored in the magnetic field such that a current through the inductor decreases from a higher current level to a lower current level;
- and
- wherein, responsive to the transistor being turned on, the capacitor is configured to discharge through the discharge path such that the light emitting element emits a pulse of light and the voltage across the capacitor decreases from the higher voltage level to the lower voltage level and the inductor is configured to store energy in the magnetic field such that the current through the inductor increases from the lower current level to the higher current level;
- a light sensor configured to detect a reflected light signal comprising light from the emitted light pulse reflected by a reflective object;
- and
- a controller configured to determine a distance to the reflective object based on the reflected light signal.
10 more elements
Dependencies are inferred from the claim text.