Driving-unit operation method and controller
A driving-unit operation method includes: generating pulse blocks on the basis of driving pulses; and modifying a driving signal in accordance with a position error signal. In the modifying the driving signal, when the position error signal is in a first range, the shape of the driving pulses is modified so as to form a first driving-pulse shape, and the pulse-block duty cycle is set to a first pulse-block duty cycle value, whereas when the position error signal is in a second range, the shape of the driving pulses is modified so as to form a second driving-pulse shape, and the pulse-block duty cycle is set to a second pulse-block duty cycle value.
1. A driving-unit operation method of operating a driving unit for driving a passive element relative to an active element,
the active element including a resonator and at least one excitation section configured to excite a vibration of the resonator,
the resonator including at least one arm extending from a coupling portion of the resonator,
the at least one arm including a contact portion at an outer end of the at least one arm,
the contact portion being movable by vibrational motion of the at least one arm,
the passive element being disposed to be driven by the vibrational motion to move relative to the active element,
the passive element including a first contact region and being disposed such that the first contact region and the first contact portion make contact with each other by a prestressing force when the active element is not excited,
the driving-unit operation method comprising:
driving the at least one excitation section by a drive signal that is a periodic signal including a drive pulse repeated at an excitation frequency, while repeatedly omitting the drive pulse, thereby generating a periodically repeated pulse block with a pulse block duty cycle expressed by a relation Ton/Tb between a pulse block on time (Ton) and a pulse block cycle (Tb); and
modifying the drive signal depending on the position error signal, wherein
in the modifying the drive signal:
in case that a position error signal is within a first range, a shape of the drive pulse is modified into a first driving pulse shape or the excitation frequency is modified by a first excitation frequency detuning value, and the pulse block duty cycle is set to a first pulse block duty cycle value, and
in case that the position error signal is within a second range, the shape of the drive pulse is modified into a second drive pulse shape or the excitation frequency is modified by a second excitation frequency detuning value, and the pulse block duty cycle is set to a second pulse block duty cycle value.
2. The driving-unit operation method according to claim 1 , wherein
in the modifying the drive signal,
in case that the position error signal is within a third range, the shape of the drive pulse is modified into a third drive pulse shape or the excitation frequency is modified by a third excitation frequency detuning value, and the pulse block duty cycle is set to a third pulse block duty cycle value.
3. The driving-unit operation method according to claim 1 , wherein
the modifying the shape of the drive pulse is performed by at least one of modification of an amplitude of the drive pulse and modification of a pulse width of the drive pulse.
4. The driving-unit operation method according to claim 1 , wherein
the modifying the shape of the drive pulse includes, in every case, maintaining the excitation frequency the same and maintaining energy transmitted by each drive pulse such that the energy is greater than a non-zero minimum pulse energy value.
5. The driving-unit operation method according to claim 4 , wherein
the non-zero minimum pulse energy value is at least 5% or in particular at least 10% of maximum energy of the drive pulse.
6. The driving-unit operation method according to claim 1 , wherein
a position of the passive element relative to the active element is maintained by the prestressing force during a turn-off period in which the drive pulse is omitted.
7. The driving-unit operation method according to claim 1 , wherein
the excitation frequency is in a range of from 50 kHz to 1,000 kHz, and the repeated omission of the drive pulse is performed at a frequency of from one tenth to one hundredth of the excitation frequency.
8. The driving-unit operation method according to claim 1 , wherein:
the first range is greater than the second range,
the energy of the drive pulse having the first drive pulse shape is greater than the energy of the drive pulse having the second drive pulse shape, and
the first pulse block duty cycle value is greater than the second pulse block duty cycle value.
9. The driving-unit operation method according to claim 8 , wherein
the drive pulse having the first drive pulse shape is a rectangular pulse of a pulse duty cycle of 50% and the first pulse block duty cycle value is 100%.
10. The driving-unit operation method according to claim 8 , wherein:
the second range is greater than the third range,
the energy of the drive pulse having the second drive pulse shape is greater than the energy of the drive pulse having the third drive pulse shape, and
the second pulse block duty cycle value is greater than the third pulse block duty cycle value.
11. The driving-unit operation method according to claim 1 , further comprising:
setting a frequency of the excitation frequency depending on a sign of the position error signal.
12. The driving-unit operation method according to claim 1 , wherein:
the resonator includes at least two arms extending from a coupling portion of the resonator,
each of the at least two arms includes the contact portion at an end of each arm, and
the passive element includes a first contact region and a second contact region, and is disposed such that the first contact region and the first contact portion make contact with each other and the second contact region and the second contact portion make contact with each other respectively by a prestressing force when the active element is not excited.
13. A controller configured to perform a method according to claim 1 , wherein
the controller is configured to be connected to and supply electric power to the at least one excitation section of the driving unit, and to judge a position of the driving unit by reading a signal from a sensor.