Back to results
US 8,605,764 B1Granted
Laser diode junction temperature compensation
AssigneeMicrovision, Inc.
InventorsBruce C. Rothaar, Dale Eugene Zimmerman, Joel Sandgathe
Life of this patent
Estimating the term…
Abstract
A projection apparatus includes at least one laser diode and a laser diode junction temperature estimator to estimate the junction temperature of the at least one laser diode. Laser diode current drive values are modified in response to the estimated laser junction temperature. The modification of laser diode current drive values may occur as frequently as once per pixel.
Claims17
An apparatus comprising:
- a laser diode coupled to be responsive to a drive signal;
- a junction temperature estimator to create an estimate of a junction temperature of the laser diode;
- a calibration control circuit to periodically measure optical power from the laser diode and generate a calibration gain value and a calibration offset value;
- and
- at least one device that includes a table of gain values and a table of offset values used to modify the drive signal as a function of the estimate of the junction temperature, wherein the at least one device further includes at least one multiplier to modify the drive signal using the calibration gain value and a gain value from the table of gain values, and at least one adder to modify the drive signal using the calibration offset value and an offset value from the table of offset values.
2 more elements
A projection apparatus comprising:
- a scanning mirror to scan modulated laser light and display pixels;
- at least one laser diode coupled to be responsive to a drive current value, and to create the modulated laser light;
- and
- a calibration control circuit to perform a calibration sequence that occurs less frequently than every pixel by periodically measuring optical power from the at least one laser diode and generating a calibration gain value and a calibration offset value;
- and
- a drive current generator to generate the drive current value, wherein the drive current generator creates the drive current value by multiplying a nominal drive value with the calibration gain value and a drive current gain, and then adding the calibration offset value and a drive current offset, wherein the drive current gain and the drive current offset are retrieved from tables driven by a junction temperature estimator that estimates a junction temperature of the at least one laser diode for every pixel.
3 more elements
An apparatus comprising:
- a first circuit to remove luminance-to-current calibration effects from a laser diode drive signal value, wherein the first circuit comprises a subtractor to remove a previously applied offset value;
- a laser diode junction temperature estimator to estimate a laser diode junction temperature as a function of past laser diode drive signal values;
- and
- a second circuit to modify the laser diode drive signal value in response to the laser diode junction temperature estimator, wherein the second circuit comprises a gain table responsive to the laser diode junction temperature estimator to provide a gain value to be multiplied with the laser diode drive signal value, an offset table responsive to the laser diode junction temperature estimator to provide an offset value to be summed with the laser diode drive signal value, and an adder to add back in the previously applied offset value.
1 more element
Dependencies are inferred from the claim text.