US 11,774,834 B2
Scanning laser projector system utilizing photodiodes inside scan area but outside of projection area for feedback
Alex Domnits, Gedera (IL); Elan Roth, Ramat Hasharon (IL); Davide Terzi, Bergamo (IT); Luca Molinari, Piacenza (IT); and Marco Boschi, Lissone (IT)
Assigned to STMicroelectronics LTD, Netanya (IL); and STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed by STMicroelectronics LTD, Netanya (IL); and STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on Sep. 20, 2021, as Appl. No. 17/479,345.
Prior Publication US 2023/0090636 A1, Mar. 23, 2023
Int. Cl. G03B 21/14 (2006.01); H04N 9/31 (2006.01); G01J 1/02 (2006.01); G01J 1/44 (2006.01); G03B 21/00 (2006.01); G03B 21/20 (2006.01)
CPC G03B 21/142 (2013.01) [G01J 1/0238 (2013.01); G01J 1/44 (2013.01); G03B 21/008 (2013.01); G03B 21/2033 (2013.01)] 29 Claims
OG exemplary drawing
 
1. A scanning laser projector, comprising:
an optical module comprising a housing carrying:
a laser generator configured to output a single laser beam;
a movable mirror apparatus including a first mirror position sensor generating output indicative of deflection of a first mirror within the movable mirror apparatus;
wherein the movable mirror apparatus is configured to scan the single laser beam across an exit window defined through the housing in a scanning pattern wider than the exit window such that the single laser beam is directed through the exit window in a projection pattern, the projection pattern being smaller than and within the scanning pattern; and
a first light detector positioned about a periphery of the exit window such that as the movable mirror apparatus scans the single laser beam in the scanning pattern, at a point in the scanning pattern where the single laser beam is scanned across an interior of the housing and not through the exit window, the single laser beam impinges upon the first light detector; and
a projection engine configured to adjust driving of the movable mirror apparatus based upon output from the first light detector by;
wherein the projection engine comprises:
a trigger circuit coupled to receive output from the first light detector and to assert a trigger signal in response to the output from the first light detector indicating that the single laser beam has impinged upon the first light detector;
a first sample/hold circuit configured to sample and hold output of the first mirror position sensor in response to assertion of the trigger signal as a first held value;
an analog to digital converter configured to digitize the first held value to produce a first digitized value; and
a control circuit configured to adjust driving of the movable mirror apparatus based upon the first digitized value.