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US 2017/0285078 A1Published application
Apparatus with device with fault detection protection
AssigneeSTMicroelectronics (Research & Development) Limited
InventorShatabda Saha
Life of this patent
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Abstract
A device such as a laser diode is provided with a monitoring arrangement. The monitoring arrangement has voltage to current convertors arranged to provide respectively currents which are proportional to the respective voltages on an anode and on a cathode of the laser diode. The monitoring arrangement provides a first output signal when the laser diode is on too long. That output signal is used to cause the laser diode to be switched off.
Claims20
A ranging device, comprising:
- an optical device configured to emit a pulse of light;
- a detector configured to detect a reflection of the pulse of light off an object;
- a distance determination circuit configured to determine, in response to an output of the detector, a distance between the object and the ranging device;
- a comparator configured to be responsive to a first current indicative of a first voltage at a first node of the optical device and a second current indicative of a second voltage at a second node of the optical device, the comparator being further configured to generate an indication signal indicating that the optical device is switched on;
- and
- a monitoring circuit having an input coupled to an output of the comparator, the monitoring circuit being configured to receive the indication signal and to generate a control signal in response to the indication signal being received for greater than a threshold period of time, the control signal being configured to cause the optical device to switch off.
3 more elements
A ranging device, comprising:
- a laser diode configured to emit a photon at an object in response to a first control signal;
- a controller configured to generate the first control signal to drive the laser diode;
- a light-sensitive detector configured to receive a reflection of the photon off the object;
- and
- a fault-detection circuit configured to determine whether the laser diode is switched on for greater than a threshold period of time and to generate a second control signal configured to cause the laser diode to switch off in response to a determination that the laser diode is switched on for greater than the threshold period of time.
2 more elements
A ranging device, comprising:
- a driver circuit;
- an optical device configured to emit a photon and to be switched on and off by the driver circuit;
- a detector configured to receive a reflection of the photon off an object;
- a distance determination circuit configured to determine, in response to an output of the detector, a distance between the object and optical device;
- a first voltage-to-current circuit configured to provide a first current dependent on a voltage at a first node of the optical device;
- a second voltage-to-current circuit configured to provide a second current dependent on a voltage at a second node of the optical device;
- a comparator configured to be responsive to the first current and the second current and to generate a first output when the optical device is switched on;
- and
- a monitoring circuit having an input coupled to an output of the comparator, the monitoring circuit being configured to receive the first output and to generate a control signal in response to the first output being received for greater than a threshold period of time, the control signal being configured to cause the driver circuit to switch off the optical device.
6 more elements
Dependencies are inferred from the claim text.