Image stabilization control circuit
View Patent ↗A image stabilization control circuit for an image capturing device, wherein a gyro-equalizer ( 24 ) integrates an angular velocity signal from a gyro-sensor ( 12 ) in an integration circuit ( 46 ). The integration circuit ( 46 ) is composed of a low-boost filter (LBF), and a phase delay in a target compensation region is set to a value appropriate for an integration process. Furthermore, a characteristic whereby the LBF reduces the phase delay at higher frequencies is used, compensation is applied to the excess phase delay of the angular signal in the high-frequency region brought about by the effect of the phase delay generated in the high-frequency region by the output signal of the gyro-sensor ( 12 ), and the phase delay in the high-frequency region is brought nearer to 90 degrees. This allows the accuracy of the process for determining the required displacement magnitude of a lens to be increased.
1. A image stabilization control circuit in which a vibration detection signal corresponding to the movement speed of an image capturing device is obtained from a vibration detector provided to the image capturing device, and which drives a vibration compensation mechanism of the image capturing device, the image stabilization control circuit comprising:
a vibration-compensating signal generator circuit for performing an integration process on the vibration detection signal and generating a vibration-compensating signal corresponding to the displacement magnitude of the image capturing device; and
a servo-circuit for generating, on the basis of the vibration-compensating signal, a drive signal for driving the vibration-compensating mechanism;
wherein the vibration-compensating signal generator circuit has:
a high pass filter for damping a low-frequency component from the vibration detection signal, and transmitting a vibration component of the target compensation region; and
an integration circuit for performing the integration process on the vibration detection signal transmitted by the high pass filter; and
wherein the integration circuit uses a phase delay compensation circuit for compensating a phase delay in the target compensation region, achieves a counterbalance between a reduced phase delay of the phase delay compensation circuit in a high-frequency region, and a phase delay of the vibration detection signal increased in the high-frequency region by the characteristics of the vibration detector, and adjusts the phase characteristics in the target compensation region and the high-frequency region.
2. The image stabilization control circuit of claim 1 , wherein:
the phase delay compensation circuit constituting the integration circuit is a low-boost filter.
3. The image stabilization control circuit of claim 1 , wherein:
the servo-circuit generates the drive signal on the basis of a signal that is a sum of a signal corresponding to a drive magnitude of the vibration compensation mechanism obtained from a drive magnitude detector provided to the image capturing device, and the vibration-compensating signal outputted from the vibration-compensating signal generator circuit.
4. The image stabilization control circuit of claim 1 , wherein:
the vibration-compensating signal generator circuit has a centering high-pass filter for damping a direct-current component from the output signal of the integration circuit.
5. The image stabilization control circuit of claim 1 , wherein:
the high-pass filter and the integration circuit include a digital filter circuit and a register; and
the digital filter circuit performs a filtering process on the basis of a filter factor stored in the register.
6. The image stabilization control circuit of claim 4 , wherein:
the high-pass filter, the integration circuit, and the centering high-pass filter include a digital filter circuit and a register; and
the digital filter circuit performs a filtering process on the basis of a filter factor stored is the register.