Optical image stabilization techniques
An optical image stabilization (OIS) of a camera system includes a controller, a lens and an image stabilizing arrangement (ISA), including one or both of an actuator mechanically coupled with the lens. The controller is configured to: (1) receive measured accelerometer data relating to camera orientation with respect to a gravitational field and causes the actuator to locate the lens at a gravity-adjusted neutral position; and/or (2) synchronously relocate, during a time interval that falls at least partially between a first successive frame and a second successive frame, one or both of the camera lens and an image sensor by controlling a slew motion of the camera lens or image sensor, monitor and controls one or more of exposure time, effective readout time, lens relocation time and frame period, and rebalance the auto exposure algorithm such that the exposure time is less than a critical value.
1. An apparatus for optical image stabilization (OIS) of a camera system, the apparatus comprising:
a lens of the camera system;
a camera lens suspension mechanism;
an image stabilizing arrangement, including an actuator mechanically coupled with the lens;
a motion sensor system comprising an accelerometer; and
a controller, communicatively coupled with the image stabilizing arrangement and the motion sensor system, wherein the controller is configured to:
receive measured camera motion information from the motion sensor system;
prior to acquisition of a succession of image frames, determine a first desired start position, for the camera lens;
during acquisition of each respective image frame in the succession of image frames, cause the image stabilizing arrangement to shift the camera lens so as to compensate for the measured camera motion; and
during a time interval that falls at least partially between a first successive frame and a second successive frame, slew the camera lens to a second desired start position for the second successive frame;
the controller being further configured to:
receive measured accelerometer data from the motion sensor system relating to camera orientation with respect to a gravitational field; and
cause the actuator to locate the lens at a gravity-adjusted neutral position, the gravity-adjusted neutral position being a position at which a force applied by the camera lens suspension mechanism balances a gravitational force.
2. The apparatus of claim 1 , wherein:
the controller is communicatively coupled with at least one motion sensor for measuring camera motion, and is configured to:
receive measured camera motion information from the at least one motion sensor of the motion sensor system; and
cause the image stabilizing arrangement to shift the camera lens so as to compensate for the measured camera motion.
3. The apparatus of claim 1 , wherein the controller is configured to monitor and control one or more of exposure time, effective readout time, lens relocation time or frame period.
4. The apparatus of claim 3 , wherein the controller is configured to control one or more of the exposure time, the effective readout time, the lens relocation time or the frame period so as to cause the sum of the exposure time, the effective readout time and the lens relocation time to be less than the frame period.
5. The apparatus of claim 4 , wherein:
the camera system includes an auto exposure algorithm that relates light sensitivity (ISO) to exposure time; and
the controller is configured to rebalance the auto exposure algorithm such that the exposure time is less than a critical value.
6. The apparatus of claim 5 , wherein the controller is configured to select the critical value so as to provide that the sum of the exposure time, the effective readout time and the lens relocation time is less than the frame period.
7. The apparatus of claim 1 , wherein the controller is configured to synchronously relocate the camera lens by controlling a slew motion of the camera lens after acquisition of the first successive frame and prior to initiating acquisition of the second successive frame.
8. The apparatus of claim 1 , wherein the controller is configured to select at least one of the first and second respective desired start position so as to reduce power consumption.
9. The apparatus of claim 1 , wherein the respective desired start position is proximate to the gravity-adjusted neutral position.
10. The apparatus of claim 1 , wherein the second desired start position is disposed, with respect to a geometrically neutral position and with respect to an end position reached at completion of an immediately preceding frame, such that the gravity-adjusted neutral position is approximately midway between the second desired start position and the end position.
11. A method for optical image stabilization (OIS) of a camera system, the method comprising:
receiving, at a controller, measured accelerometer data relating to camera orientation with respect to a gravitational field, the camera including a lens, a camera lens suspension mechanism and an image stabilizing arrangement, including an actuator mechanically coupled with the lens; and
under direction of the controller, causing the actuator to locate the lens at a gravity-adjusted neutral position, the gravity-adjusted neutral position being a position at which a force applied by the camera lens suspension mechanism balances a gravitational force; the method further comprising:
receiving, at the controller, measured camera motion information from at least one motion sensor; and with the controller:
prior to acquisition of a succession of image frames, determining a first desired start position, for the camera lens;
during acquisition of each respective image frame in the succession of image frames, causing the image stabilizing arrangement to shift the camera lens so as to compensate for the measured camera motion; and
during a time interval that falls at least partially between a first successive frame and a second successive frame, causing the stabilizing arrangement to slew the camera lens to a second desired start position for the second successive frame.
12. The method of claim 11 , further comprising monitoring and controlling, with the controller, one or more of exposure time, effective readout time, lens relocation time and frame period.
13. The method of claim 12 , wherein the controller controls one or more of the exposure time, the effective readout time, the lens relocation time and the frame period so as to cause the sum of the exposure time, the effective readout time and the lens relocation time to be less than the frame period.
14. The method of claim 11 , wherein the controller is configured to select at least one of the first and second respective desired start position so as to reduce power consumption.
15. The method of claim 11 , wherein the respective desired start position is proximate to the gravity-adjusted neutral position.
16. An apparatus for optical image stabilization (OIS) of a camera system, the camera system including an auto exposure algorithm that relates light sensitivity (ISO) to exposure time, the apparatus comprising:
a lens of the camera system;
an image stabilizing arrangement, including one or both of:
an image sensor optically coupled with the camera lens; and
an actuator mechanically coupled with one or both of the lens and the image sensor; and
a controller, the controller communicatively coupled with the image stabilizing arrangement and at least one motion sensor for measuring camera motion, wherein the controller is configured to:
synchronously relocate one or both of the camera lens and the image sensor by controlling a slew motion of the camera lens or image sensor during a time interval that falls at least partially between acquisition of a first successive frame and initiating acquisition of a second successive frame;
monitor and control one or more of exposure time, effective readout time, lens relocation time and frame period; and
rebalance the auto exposure algorithm such that the exposure time is less than a critical value.
17. The apparatus of claim 16 , wherein the controller is configured to select the critical value so as to provide that the sum of the exposure time, the effective readout time and the lens relocation time is less than the frame period.
18. The apparatus of claim 16 , wherein the controller is configured to:
receive measured camera motion information from the at least one motion sensor;
prior to acquisition of a succession of image frames, determine a first desired start position, for one or both of the camera lens and the image sensor;
during acquisition of each respective image frame in the succession of image frames, cause the image stabilizing arrangement to shift one or both of the camera lens and the image sensor so as to compensate for the measured camera motion; and
between a first successive frame and a second successive frame, relocate one or both of the camera lens and the image sensor to a second desired start position for the second successive frame.
19. The apparatus of claim 18 , wherein the controller is configured to synchronously relocate the camera lens by controlling a slew motion of the camera lens after acquisition of the first successive frame and prior to initiating acquisition of the second successive frame.
20. The apparatus of claim 18 , wherein the controller is configured to select at least one of the first and second respective desired start position so as to reduce one or both of (i) likelihood of railing and (ii) power consumption.
21. The apparatus of claim 18 , wherein the respective desired start position is proximate to a geometrically neutral position.
22. The apparatus of claim 18 , wherein the second desired start position is disposed, with respect to a geometrically neutral position and with respect to an end position reached at completion of an immediately preceding frame, such that the geometrically neutral position is approximately midway between the second desired start position and the end position.
23. The apparatus of claim 18 , wherein the controller is configured to drive the actuator to relocate the lens.
24. The apparatus of claim 18 , wherein the motion sensor includes one or more of a gyroscope, an accelerometer, a magnetometer or other inertial sensor.
25. A method for optical image stabilization (OIS) of a camera system, the camera system including, the apparatus including a lens of the camera system, an image stabilizing arrangement including an image sensor optically coupled with the camera lens and an actuator mechanically coupled with one or both of the lens and the image sensor, the method comprising
synchronously relocating, with a controller, one or both of the camera lens and the image sensor by controlling a slew motion of the camera lens or image sensor during a time interval that falls at least partially between acquisition of a first successive frame and initiating acquisition of a second successive frame, the controller being communicatively coupled with the image stabilizing arrangement and at least one motion sensor for measuring camera motion;
monitoring and controlling, with the controller, one or more of exposure time, effective readout time, lens relocation time and frame period; and
rebalancing, with the controller, the auto exposure algorithm such that the exposure time is less than a critical value.
26. The method of claim 25 , wherein the controller selects the critical value so as to provide that the sum of the exposure time, the effective readout time and the lens relocation time is less than the frame period.
27. The method of claim 25 , further comprising receiving, at the controller, measured camera motion information from the at least one motion sensor; and, with the controller:
prior to acquisition of a succession of image frames, determining a first desired start position, for one or both of the camera lens and the image sensor;
during acquisition of each respective image frame in the succession of image frames, causing the image stabilizing arrangement to shift one or both of the camera lens and the image sensor so as to compensate for the measured camera motion; and
between a first successive frame and a second successive frame, relocating one or both of the camera lens and the image sensor to a second desired start position for the second successive frame.
28. The method of claim 25 , wherein the controller synchronously relocates the camera lens by controlling a slew motion of the camera lens after acquisition of the first successive frame and prior to initiating acquisition of the second successive frame.