Optical device, method for controlling optical device, and image display apparatus
A method for controlling an optical device including a movable section including an optical section that refracts incident video image light in accordance with the angle of incidence of the video image light and outputs the refracted video image light and a holding section that supports the optical section, an actuator that causes the movable section to swing, and a drive circuit that applies a drive signal to the actuator via a coupling capacitor and an amplifier, the method including applying voltage that is intermediate potential for a first period and then applying a trapezoidal wave having an upper base corresponding to second voltage and a lower base corresponding to third voltage.
1. A method for controlling an optical device including a movable section including an optical section that refracts incident video image light in accordance with an angle of incidence of the video image light and outputs the refracted video image light and a holding section that supports the optical section, an actuator that causes the movable section to swing, and a drive circuit that applies a drive signal to the actuator via a coupling capacitor and an amplifier, the method comprising:
applying first voltage to the actuator for a first period and then periodically applying second voltage and third voltage to the actuator to cause the movable section to swing,
wherein the second voltage is a maximum of the voltage applied during causing the movable section to swing,
the third voltage is a minimum of the voltage applied during causing the movable section to swing, and
the first voltage is intermediate voltage between the second voltage and the third voltage.
2. The method for controlling an optical device according to claim 1 , wherein the first period is at least three times a time constant τ, where τ is a time constant determined by a capacity of the coupling capacitor and resistance including input impedance of the amplifier.
3. The method for controlling an optical device according to claim 1 , wherein the first voltage is applied to the actuator after the operation of driving the actuator based on the drive signal is completed or in a drive standby state in which the actuator is ready to be driven.
4. The method for controlling an optical device according to claim 1 , wherein a signal waveform periodically applied to the actuator is a waveform of a trapezoidal wave having an upper base corresponding to the second voltage and a lower base corresponding to the third voltage.
5. An optical device comprising:
a movable section including an optical section that refracts incident video image light in accordance with an angle of incidence of the video image light and outputs the refracted video image light and a holding section that supports the optical section;
an actuator that causes the movable section to swing; and
a drive circuit that applies a drive signal to the actuator,
wherein the drive circuit applies the drive signal to the actuator via a coupling capacitor and an amplifier,
the drive circuit applies first voltage to the actuator for a first period and then periodically applies second voltage and third voltage to the actuator to cause the movable section to swing,
the second voltage is a maximum of the voltage applied during causing the movable section to swing,
the third voltage is a minimum of the voltage applied during causing the movable section to swing, and
the first voltage is intermediate voltage between the second voltage and the third voltage.
6. An image display apparatus comprising:
the optical device according to claim 5 ; and
a projection optical system that enlarges and projects the video image light outputted from the optical device.