Image stabilization control circuit
View Patent ↗In an image stabilization control circuit of an image-capturing device, a gyro-equalizer ( 24 ) is used to integrate an angular velocity signal corresponding to vibration, and determine a required magnitude of displacement of a lens. The gyro-equalizer ( 24 ) integrates the angular velocity signal from a gyro-sensor ( 12 ) using an integration circuit ( 46 ) (LPF), and converts the result into an angular signal. A direct-current component of the angular signal is removed using a centering circuit ( 52 ) (HPF). Excessive phase delay of the angular signal on a high-frequency side caused by a phase characteristic of the gyro-sensor ( 12 ) is compensated by a phase lead compensation circuit ( 50 ) composed of a high-boost filter, and the phase delay of the angular signal with respect to the angular velocity signal is brought nearer to 90° by an integration process.
1. An image stabilization control circuit for obtaining from a vibration-detection element provided to an image-capturing device a vibration-detection signal corresponding to a movement speed of the image-capturing device, and for driving an
image stabilization 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 magnitude of displacement 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 image stabilization 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 in a target compensation region;
an integration circuit for performing the integration process on the vibration-detection signal that has passed through the high-pass filter; and
a phase lead compensation circuit for performing phase lead compensation on a phase delay generated on a high-frequency side of the vibration-detection signal due to a characteristic of the vibration-detection element wherein the phase lead compensation circuit is configured to compensate for an increase in the phase delay beyond 90 degrees on the high-frequency side of a target compensation region.
2. The image stabilization control circuit of claim 1 , wherein:
the phase lead compensation circuit is a high-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 obtained by adding a signal corresponding to a drive magnitude of the image stabilization mechanism, and the vibration-compensating signal outputted from the image stabilization mechanism, drive magnitude being obtained from a drive magnitude detector provided to the image-capturing device.
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 an output signal of the integration circuit.
5. The image stabilization control circuit of claim 1 , further comprising:
a register for storing filter coefficients, wherein:
each of the high-pass filter, the integration circuit, and the phase lead compensation circuit is composed of a digital filter circuit; and
the digital filter circuit performs a filter operation process in accordance with a filter characteristic set depending on the filter coefficients stored in the register.
6. The image stabilization control circuit of claim 4 , further comprising:
a register for storing filter coefficients, wherein:
each of the high-pass filter, the integration circuit, the phase lead compensation circuit, and the centering high-pass filter is composed of a digital filter circuit; and
the digital filter circuit performs a filter operation process in accordance with a filter characteristic set depending on the filter coefficients stored in the register.