Crosstalk correction method and actuator driver
An image stabilization actuator is used to displace a movable unit in a first direction, and a position in the first direction when an AF-axis position detection signal reaches a peak value is detected. Similarly, the image stabilization actuator is used to displace the movable unit in a second direction, and a position in the second direction when the AF-axis position detection signal reaches a peak value is detected. A reference position based on the position in the first direction and the position in the second direction thus obtained is stored. Correction information indicating a relationship between a displacement amount, from the reference position, of the movable unit displaced by the image stabilization actuator and a correction amount of the position detection signal is stored.
1. A correction method applied to a camera module, the camera module including a movable unit including an imaging lens and a magnet, an autofocus position detector including a magnetic field detection element structured to detect magnetic field generated by the magnet, the autofocus position detector being structured to generate a position detection signal indicating a position of the movable unit in a Z-axis direction, an autofocus actuator structured to position the movable unit in the Z-axis direction along an optical axis, and an image stabilization actuator structured to position the movable unit in an X-axis direction and a Y-axis direction orthogonal to each other in a plane orthogonal to an optical axis direction of the imaging lens, the correction method comprising:
displacing the movable unit in a first direction using the image stabilization actuator and detecting a position in the first direction when the position detection signal reaches a peak value;
displacing the movable unit in a second direction using the image stabilization actuator and detecting a position in the second direction when the position detection signal reaches a peak value;
storing a reference position based on the position in the first direction and the position in the second direction;
storing correction information indicating a relationship between a displacement amount, from the reference position, of the movable unit displaced by the image stabilization actuator and a correction amount of the position detection signal;
acquiring, during image stabilization and autofocus operation, the displacement amount of the movable unit from the reference position on the basis of the correction information and generating the correction amount corresponding to the displacement amount; and
correcting the position detection signal using the correction amount.
2. The correction method according to claim 1 , wherein
when displacement amounts from the reference position in the first direction and the second direction are denoted by ΔU, ΔV, respectively, the correction information indicates a relationship between a radius R of R=√(ΔU 2 +ΔV 2 ) and the correction amount.
3. The correction method according to claim 1 , wherein when displacement amounts from the reference position in the first direction and the second direction are denoted by ΔU, ΔV, respectively, and A U , A V each denote a constant, the correction information indicates a relationship between a radius R of R=√(A U ΔU 2 +A V ΔV 2 ) and the correction amount.
4. The correction method according to claim 1 , wherein feedback control for autofocus is not performed in the displacing the movable unit in the first direction and the displacing the movable unit in the second direction.
5. The correction method according to claim 1 , further comprising performing linear correction on the position detection signal before the correcting.
6. An actuator driver used in a camera module, the camera module including a movable unit including an imaging lens and a magnet, an autofocus actuator structured to position the movable unit in a Z-axis direction along an optical axis, an autofocus position detector including a magnetic field detection element structured to detect magnetic field generated by the magnet, the autofocus position detector being structured to generate a position detection signal indicating a position of the movable unit in the Z-axis direction, and an image stabilization actuator structured to position the movable unit in an X-axis direction and a Y-axis direction orthogonal to each other in a plane orthogonal to an optical axis direction of the imaging lens, the actuator driver comprising:
an autofocus drive unit structured to control the autofocus actuator;
an image stabilization drive unit structured to control the image stabilization actuator;
a first memory storing a reference position;
a second memory storing correction information;
and a processor, wherein in a calibration process, the movable unit is displaced in a first direction, and a position in the first direction when the position detection signal reaches a peak value is detected,
in the calibration process, the movable unit is displaced in a second direction, and a position in the second direction when the position detection signal reaches a peak value is detected,
in the calibration process, a reference position based on the position in the first direction and the position in the second direction is stored in the first memory, and
in the calibration process, correction information indicating a relationship between a displacement amount, from the reference position, of the movable unit displaced by the image stabilization actuator and a correction amount of the position detection signal is stored in the second memory, wherein
the processor generates, during image stabilization and autofocus operation, the correction amount corresponding to the displacement amount of the movable unit from the reference position on the basis of the correction information and corrects the position detection signal using the correction amount.