Image stabilization control circuit
View Patent ↗In an image stabilization control circuit for 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 lens displacement. The gyro-equalizer ( 24 ) integrates the angular velocity signal from a gyro-sensor ( 12 ) using an integration circuit ( 46 ) (LPF), and converts the signal into an angular signal. A direct current component of the angular signal is removed using a centering circuit ( 50 ) (HPF). The LPF and HPF can produce an insufficient phase delay in a low-band side of a target compensation region. A phase lag compensation circuit ( 48 ) comprising a low-boost filter compensates for the insufficient phase delay, and brings the phase delay of the angular signal with respect to the angular velocity signal close to 90° in 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 that corresponds to displacement velocity, 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 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 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 lag compensation circuit for performing phase lag compensation, and configured to adjust a phase characteristic of the vibration-compensating signal generator circuit closer to a 90° delay across an entirety of the target compensation region.
2. The image stabilization control circuit of claim 1 , wherein:
the phase lag compensation circuit is a low-boost filter in which the gain on a lower-frequency side of the target compensation region is greater than on a higher-frequency side.
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 vibration-compensating signal generator circuit, the 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 the output signal of the integration circuit.
5. The image stabilization control circuit of claim 1 , wherein:
the high-pass filter, the integration circuit, and the phase lag compensation circuit include a digital filter circuit and a register; and
the digital filter circuit performs a filter operation process on the basis of a filter coefficient stored in the register.
6. The image stabilization control circuit of claim 4 , wherein;
the high-pass filter, the integration circuit, the phase lag compensation circuit, and the centering high-pass filter include a digital filter circuit and a register; and
the digital filter circuit performs a filter operation process on the basis of a filter coefficient stored in the register.