Drive apparatus, drive system, and drive method
First Claim
1. A drive apparatus for driving an actuator having two shape memory alloys connected in a push-pull arrangement to a movable part to give a displacement to said movable part on the basis of a displacement target value, comprising:
- (a) a feeder configured to feed current to a shape memory alloy to be heated on the basis of a drive current signal, thereby making said shape memory alloy perform a regaining operation towards a memorized shape to interlock with said displacement of said movable part; and
(b) a controller configured to generate a first drive current signal based on said displacement target value for one of said two shape memory alloys which performs said regaining operation and feed a first drive current based on said first drive current signal to said one of said two shape memory alloys, said controller further configured to generate a second drive current signal for another shape memory alloy which does not perform said regaining operation and feed a second drive current based on said second drive current signal to said other shape memory alloy as a bias current while passing said first drive current.
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Accused Products
Abstract
An actuator has two shape memory alloys (SMAs) connected in a push-pull arrangement to a movable part. By passing current to each of the SMAs from a drive circuit part, the movable part can be driven. When a target position signal of the movable part is input to the drive circuit part, a current is passed to an SMA of the contraction side on the basis of a drive waveform obtained by adding a voltage according to the target position signal to a bias voltage, and a current is passed to the SMA on the expansion side on the basis of a signal waveform obtained by subtracting the voltage according to the target position signal from the bias voltage. Consequently, the SMA of the expansion side maintains a pre-heat state and is not cooled excessively, so that response delay at the time of the next heating can be prevented. As a result, the response of the actuator can be increased.
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Citations
15 Claims
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1. A drive apparatus for driving an actuator having two shape memory alloys connected in a push-pull arrangement to a movable part to give a displacement to said movable part on the basis of a displacement target value, comprising:
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(a) a feeder configured to feed current to a shape memory alloy to be heated on the basis of a drive current signal, thereby making said shape memory alloy perform a regaining operation towards a memorized shape to interlock with said displacement of said movable part; and (b) a controller configured to generate a first drive current signal based on said displacement target value for one of said two shape memory alloys which performs said regaining operation and feed a first drive current based on said first drive current signal to said one of said two shape memory alloys, said controller further configured to generate a second drive current signal for another shape memory alloy which does not perform said regaining operation and feed a second drive current based on said second drive current signal to said other shape memory alloy as a bias current while passing said first drive current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10)
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8. A drive apparatus for driving an actuator having two shape memory alloys connected in a push-pull arrangement to a movable part to give a displacement to said movable part on the basis of a displacement target value, comprising:
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(a) a feeder configured to feed current to a shape memory alloy to be heated on the basis of a drive current signal, thereby causing said shape memory alloy to perform a regaining operation towards a memorized shape to interlock with said displacement of said movable part; and (b) a controller configured to generate a first drive current signal based on said displacement target value for one of said two shape memory alloys which performs said regaining operation and feed a first drive current based on said first drive current signal to said one of said two shape memory alloys, said controller further configured to generate a second drive current signal for another shape memory alloy which does not perform said regaining operation and feed a second drive current based on said second drive current signal to said other shape memory alloy as a bias current while passing said first drive current, wherein said first drive current signal is a pulse width modulation signal obtained by adding a first duty ratio according to said displacement target value to a predetermined duty ratio, and said second drive current signal is a pulse width modulation signal obtained by subtracting said first duty ratio from said predetermined duty ratio. - View Dependent Claims (9)
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11. A drive system for giving a displacement to a movable part on the basis of a displacement target value, comprising:
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(a) an actuator having two shape memory alloys connected in a push-pull arrangement to said movable part; (b) a feeder configured to feed current to a shape memory alloy to be heated on the basis of a drive current signal, thereby making said shape memory alloy perform a regaining operation towards a memorized shape to interlock with said displacement of said movable part; and (c) a controller configured to generate a first drive current signal based on said displacement target value for one of said two shape memory alloys which performs said regaining operation and feed a first drive current based on said first drive current signal to said one of said two shape memory alloys, said controller further configured to generate a second drive current signal for another shape memory alloy which does not perform said regaining operation and feed a second drive current based on said second drive current signal to said other shape memory alloy as a bias current while passing said first drive current.
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12. A drive system for giving a displacement to a movable part on the basis of a displacement target value, comprising:
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(a) an actuator having two shape memory alloys connected in a push-pull arrangement to said movable part; (b) a feeder configured to feed current to a shape memory alloy to be heated on the basis of a drive current signal, thereby performing a regaining operation towards a memorized shape to interlock with said displacement of said movable part; and (c) a controller configured to generate a first drive current signal based on said displacement target value for one of said two shape memory alloys which performs said regaining operation and feed a first drive current based on said first drive current signal to said one of said two shape memory alloys, said controller further configured to generate a second drive current signal for another shape memory alloy which does not perform said regaining operation and feed a second drive current based on said second drive current signal to said other shape memory alloy as a bias current while passing said first drive current, wherein said first drive current signal is a pulse width modulation signal obtained by adding a duty ratio according to said displacement target value to a predetermined duty ratio, and said second drive current signal is a pulse width modulation signal obtained by subtracting the duty ratio according to said displacement target value from said predetermined duty ratio.
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13. A drive method for driving an actuator having two shape memory alloys connected in a push-pull arrangement to a movable part to give displacement to said movable part on the basis of a displacement target value, comprising the steps of:
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(a) feeding current to a shape memory alloy to be heated on the basis of a drive current signal, thereby making said shape memory alloy perform a regaining operation towards a memorized shape to interlock with said displacement of said movable part; and (b) generating a first drive current signal based on said displacement target value for one of said two shape memory alloys which performs said regaining operation and feeding a first drive current based on said first drive current signal to said one of said two shape memory alloys; and (c) generating a second drive current signal for another shape memory alloy which does not perform said regaining operation and feeding a second drive current based on said second drive current signal to said other shape memory alloy as a bias current while passing said first drive current. - View Dependent Claims (14, 15)
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Specification