JP2014155421A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator with an enhanced usability.SOLUTION: A linear actuator 1 comprises: a first magnet 23; a second magnet 24; a movable element 22; a fixed element 21; a controller 30; and an amplitude controller 40. The fixed element 21 is attached to the first magnet 23. The movable element 22 is attached to the second magnet 24. The movable element 22 performs a linear movement with respect to the fixed element 21 and the first magnet 23. The controller 30 controls the current amount applied to the first magnet 23 on the basis of the current supply time to cause the movable element 22 to perform a linear movement. The amplitude controller 40 detects a displacement of the movable element 22. The controller 30 performs a feed back control of the current supply time to make the displacement closer to a target value on the basis of a difference between the displacement and the target value. The controller 30 switches the target value on the basis of the increase or decrease of the current supply time.

Description

  The present invention relates to a linear actuator.

  Patent Document 1 discloses an example of a linear actuator. The linear actuator includes a first magnet, a second magnet, a mover, and a control unit. The mover is attached to one of the first magnet and the second magnet. The mover reciprocates with respect to the other of the first magnet and the second magnet. The control unit controls the amount of current supplied to the first magnet by the current supply time, and causes the mover to linearly move with respect to the other of the first magnet and the second magnet.

JP 2001-16892 A

  In the linear actuator, a load is applied to the mover due to contact with an object or the like. For example, in a hair removal instrument having a linear actuator, when the hair to be removed comes in contact with the mover, the load on the mover increases. For this reason, the feeling of shaving can be improved by increasing the target value of the drive amount when the load applied to the mover increases. Thus, the linear actuator can improve the convenience of a linear actuator by performing the drive corresponding to load.

  The present invention was created based on the above background, and an object of the present invention is to provide a linear actuator that can enhance convenience.

  This means is that "a first magnet formed as an electromagnet, a second magnet formed as a permanent magnet or an electromagnet, one of the first magnet and the second magnet is attached, the first magnet and the first magnet A mover that linearly moves with respect to the other of the two magnets, and an amount of current that is supplied to the first magnet is controlled by a current supply time, and a controller that moves the mover in the linear motion, the displacement of the mover, and the movable A drive amount detection unit that detects at least one of a reciprocation speed of the child and an acceleration of the reciprocation as a drive amount, and the control unit calculates a difference between the drive amount and a target value of the drive amount. , A linear actuator that performs feedback control of the current supply time to bring the drive amount close to the target value, and switches the target value based on the increase or decrease of the current supply time. Including.

  In the linear actuator, when the load applied to the mover increases or decreases, the deviation between the drive amount and the target value of the drive amount becomes large. When the load applied to the mover decreases, the driving amount with respect to the current supply time increases. For this reason, when the load applied to the mover decreases, the current supply time is feedback-controlled so as to decrease. Further, when the load applied to the mover increases, the driving amount with respect to the current supply time decreases. For this reason, when the load applied to the mover increases, feedback control is performed in a direction in which the current supply time increases.

  The linear actuator switches the target value based on an increase or decrease in current supply time. That is, the target value can be switched according to the load. For this reason, the convenience of a linear actuator can be improved.

  One form of the above means is that “the control unit has an upper limit value for limiting the current supply time switched according to the target value, and a total supply time that is a sum of unit times of the current supply time is predetermined. A linear actuator that reduces the upper limit value based on becoming larger than time.

  One form of the above means is that the control unit has a final target value as the target value and an intermediate target value between the final target value and the target value before switching, and switches the target value. A linear actuator that switches stepwise to the final target value via the intermediate target value.

  One form of the above means is that “the control unit determines the current supply time to bring the drive amount close to the target value from the difference between the drive amount and the target value of the drive amount using integral control or differential integration control. When the feedback control is performed, and the difference between the drive amount and the switched target value after switching the target value changes from a value larger than a predetermined difference to the predetermined difference or less, the integral control or the differential integral control Includes a linear actuator that sets the accumulated deviation at “0” or approaches “0”.

  One form of the means is as follows: “The controller supplies the drive amount to the target value by using differential control or differential integration control from the difference between the drive amount and the target value of the drive amount. A linear actuator that performs the feedback control and sets the differential gain in the calculation cycle when the target value is switched or the calculation cycle immediately after the target value is switched to “0” or to make it close to “0” ” Including.

  This means is that "a first magnet formed as an electromagnet, a second magnet formed as a permanent magnet or an electromagnet, one of the first magnet and the second magnet is attached, the first magnet and the first magnet A mover that linearly moves with respect to the other of the two magnets, and an amount of current that is supplied to the first magnet is controlled by a current supply time, and a controller that moves the mover in the linear motion, the displacement of the mover, and the movable A drive amount detection unit that detects at least one of a reciprocation speed of the child and an acceleration of the reciprocation as a drive amount, and the control unit calculates a difference between the drive amount and a target value of the drive amount. Feedback control of the current supply time to bring the drive amount close to the target value, and based on the increase or decrease of the current supply time, a linear controller that determines increase or decrease of the load on the mover Including the Chueta ".

  The linear actuator can determine the increase or decrease of the load applied to the mover based on the increase or decrease of the current supply time. For this reason, a linear actuator can be controlled according to load. For this reason, the convenience of a linear actuator can be improved.

  This linear actuator can improve convenience.

The schematic diagram which shows the whole structure of the linear actuator 1 of 1st Embodiment. The block diagram which shows the electric constitution of the linear actuator 1 of 1st Embodiment. The timing chart which shows an example of the execution aspect of the target value change process of 1st Embodiment. The timing chart which shows an example of the execution aspect of the target value change process of 1st Embodiment. The timing chart which shows an example of the execution aspect of the target value change process of 1st Embodiment. The timing chart which shows an example of the execution aspect of the target value change process of 2nd Embodiment. The timing chart which shows an example of the execution aspect of the target value change process of 3rd Embodiment. The timing chart which shows an example of the execution aspect of the target value change process of 4th Embodiment.

(First embodiment)
With reference to FIG. 1, the structure of the linear actuator 1 as an electric shaver is demonstrated.

  The linear actuator 1 includes a frame 11, a movable blade 12, a drive unit 20, a control unit 30, and an amplitude control unit 40. The linear actuator 1 uses a battery as the power source 50. The amplitude controller 40 corresponds to a “driving amount detector”.

The frame 11 houses the movable blade 12, the drive unit 20, the control unit 30, and the power source 50. The frame 11 holds an outer blade (not shown).
The drive unit 20 includes a stator 21, a mover 22, a first magnet 23, a second magnet 24, and a spring 25.

  The stator 21 is fixed to the frame 11. The stator 21 has an opening 21A. The mover 22 is attached to the stator 21 via a spring 25 inside the opening 21A. The mover 22 linearly moves in the reciprocating direction X with respect to the stator 21. The mover 22 reciprocates. The mover 22 holds the movable blade 12. The spring 25 connects both end portions in the reciprocating direction X of the mover 22 and the inner peripheral surface of the opening 21A.

  The first magnet 23 is formed as an electromagnet. The first magnet 23 has a coil 23A. The first magnet 23 is attached to the stator 21. The first magnet 23 is formed, for example, by winding a coil 23 </ b> A around a laminate of a magnetic material sintered body or a magnetic material iron plate.

  The second magnet 24 is formed as a permanent magnet. The second magnet 24 has an N pole 24A and an S pole 24B. The second magnet 24 is attached to the mover 22. Specifically, the N pole 24A and the S pole 24B are magnetized on the mover 22 side by side in the reciprocating direction X. The N pole 24A and the S pole 24B are opposed to the coil 23A through a predetermined gap.

The control unit 30 includes a control output unit 31 and a drive circuit 33.
The control unit 30 supplies power to the coil 23A. The control unit 30 switches the direction of the current supplied to the coil 23A. The control unit 30 controls the amount of current supplied to the coil 23A.

The configuration of the control unit 30 will be described with reference to FIG.
The drive circuit 33 is connected to the coil 23A. The drive circuit 33 operates based on the power supply voltage Vcc from the power supply 50 (see FIG. 1), and supplies the drive current Id to the coil 23A.

  The amplitude control unit 40 is connected to the coil 23A. The amplitude control unit 40 detects the amplitude of the mover 22 from the induced voltage generated in the coil 23A. The amplitude control unit 40 outputs the detected amplitude information to the control output unit 31. The control unit 30 performs feedback control based on PID control in accordance with the output from the amplitude control unit 40. The PID control has differential control and integral control.

  The control output unit 31 performs PWM (Pulse Width Modulation) control of the drive current Id to the coil 23 </ b> A based on the output from the amplitude control unit 40. That is, the control output unit 31 outputs a PWM signal to the drive circuit 33. The control output unit 31 outputs a PWM signal so that the drive current Id is supplied to the coil 23A at a frequency synchronized with the mechanical resonance frequency of the linear actuator 1 determined by the weight of the mover 22, the spring constant of the spring 25, and the like. Is generated. The control output unit 31 is supplied with a constant voltage generated by the constant voltage power supply 60 based on the power supply voltage Vcc from the power supply 50 as an operating voltage.

  When the drive current Id flows through the coil 23A, the mover 22 and the second magnet 24 drive in the reciprocating direction X while bending the spring 25 according to the direction in which the drive current Id flows. When the direction in which the drive current Id flows is switched at an appropriate timing under the control of the control output unit 31, the mover 22 is reciprocated in the reciprocating direction X. The movable blade 12 is held by the movable element 22. For this reason, the movable blade 12 reciprocates with respect to the stator 21 together with the movable element 22. At this time, the hair introduced into the outer blade (not shown) is cut off by being sandwiched between the outer blade (not shown) and the movable blade 12 that reciprocates.

An example of the internal configuration of the drive circuit 33 will be described.
The drive circuit 33 is configured as a full bridge circuit including switching elements such as MOSFETs. In the drive circuit 33, a coil 23A is connected between a connection point between the switching elements Q1 and Q3 and a connection point between the switching elements Q2 and Q4. In the drive circuit 33, the pair of switching elements Q 1 and Q 4 and the pair of switching elements Q 2 and Q 3 are alternately turned on based on the PWM signal from the control output unit 31. At this time, the direction of the drive current Id flowing through the coil 23A is switched, and the mover 22 reciprocates.

An example of the internal configuration of the amplitude control unit 40 will be described.
The amplitude control unit 40 includes an amplifier circuit 41, comparison circuits 42 and 43, a microcontroller (hereinafter “microcomputer”) 44, and an amplitude conversion circuit 45.

  The amplifier circuit 41 amplifies the voltage across the coil 23A, that is, the induced voltage E generated in the coil 23A, and outputs the amplified voltage Vn after the amplification to the comparison circuits 42 and 43. The comparison circuit 42 compares the reference voltage V0, which is a zero voltage, with the amplified voltage Vn, and outputs an output signal S1 having a signal level corresponding to the comparison result to the amplitude conversion circuit 45 in the microcomputer 44. The comparison circuit 43 compares the amplified voltage Vn with a reference voltage V1 lower than the reference voltage V0 by a predetermined voltage, and outputs an output signal S2 having a signal level corresponding to the comparison result to the amplitude conversion circuit 45. The reference voltage V1 may be set to a voltage higher than the reference voltage V0 by a predetermined voltage.

  The microcomputer 44 has an amplitude conversion circuit 45. The amplitude conversion circuit 45 detects a time T0 when the amplified voltage Vn becomes the same voltage as the reference voltage V0 (= 0 V) based on the signal level of the output signal S1, and returns the time T0 to the amplitude of the movable element 22. Judge as a point. Specifically, a sinusoidal induced voltage E is generated in the coil 23 </ b> A according to the reciprocation of the mover 22. The waveform of the induced voltage E is the same frequency as the mechanical resonance frequency of the linear actuator 1. In addition, the induced voltage E changes according to the displacement, speed, acceleration, the direction of linear increase, and the like, which are differences from the reference position of the mover 22. The induced voltage E increases as the speed of the mover 22 increases. For example, when the mover 22 reaches the end in the reciprocating direction X, that is, when the speed of the mover 22 becomes “0”, the movement of the second magnet 24 attached to the mover 22 is temporarily stopped. For this reason, there is no change in magnetic flux. For this reason, the induced voltage E becomes “0”. Therefore, the time when the induced voltage E (amplified voltage Vn) of the coil 23A becomes “0” corresponds to the turning point at which the direction of the linear motion of the mover 22 is switched.

  The amplitude conversion circuit 45 detects a time T1 when the amplified voltage Vn becomes the same voltage as the reference voltage V1 based on the signal level of the output signal S2. Further, the amplitude conversion circuit 45 detects a time difference Ts from time T1 to time T0, and obtains a displacement of the mover 22 (hereinafter, “displacement Y”) based on the time difference Ts. The displacement Y corresponds to “driving force”.

  The amplitude conversion circuit 45 calculates a time (time difference Ts) from when the induced voltage E becomes a predetermined voltage (reference voltage V1) to when the amplitude turns back (time T0). The linear actuator 1 vibrates at a constant frequency, and the position and speed of the mover 22 change as a sine curve. For this reason, the driving state (sine curve) of the linear actuator 1 can be uniquely specified by measuring the time difference Ts. For this reason, the displacement Y as the position of the mover 22 can be uniquely specified based on the time difference Ts.

  The induced voltage E of the coil 23 </ b> A is determined by the electromagnetic force, the amplitude, and the frequency, and the variation here depends only on the amplitude of the mover 22. For this reason, the induced voltage E increases as the amplitude of the mover 22 increases. For this reason, the time difference Ts becomes shorter as the amplitude of the mover 22 becomes larger. On the contrary, the time difference Ts becomes longer as the amplitude of the mover 22 becomes smaller. Thereby, this time difference Ts can be converted as the displacement Y. The detection of the displacement Y by the amplitude conversion circuit 45 is preferably performed during a non-energization period in which the drive current Id does not flow through the coil 23A.

  When the reference voltage V1 is set to a voltage higher than the reference voltage V0 by a predetermined voltage, the amplified voltage Vn becomes the same voltage as the reference voltage V1 from the time T0 when the amplified voltage Vn becomes the same voltage as the reference voltage V0. The displacement Y may be obtained by detecting the time difference Ts up to the time T1.

The amplitude conversion circuit 45 outputs the displacement Y to the control output unit 31.
The control output unit 31 generates a PWM signal so as to control the output timing of the drive current Id in accordance with the return timing of the amplitude detected by the amplitude conversion circuit 45. Specifically, the control output unit 31 generates a PWM signal so as to control the output timing of the drive current Id in accordance with the return timing of the amplitude detected by the amplitude conversion circuit 45. Specifically, the control output unit 31 turns on the switching elements Q1 and Q4 for a predetermined time Tb after a predetermined time Ta from the turning point of the amplitude, and supplies the drive current Id in the first direction to the coil 23A. Further, the control output unit 31 turns on the switching elements Q2 and Q3 for a predetermined time Td after a predetermined time Tc (> Ta + Tb) from the turning point of the amplitude, so that the drive current Id in the direction opposite to the first direction is applied to the coil 23A. Supply. Hereinafter, the sum of the predetermined time Tb, the predetermined time Tb, and the predetermined time Td in one cycle is referred to as “current supply time D”.

  Based on the displacement Y, the control output unit 31 generates a PWM signal so that the maximum width of the displacement Y of the mover 22 matches the target value of the displacement Y (hereinafter, “target value W”). Specifically, the control output unit 31 controls the lengths of the predetermined times Tb and Td, that is, the duty ratio so that the displacement Y of the mover 22 coincides with the target value W, thereby reducing the current amount of the drive current Id. Control. The control output unit 31 sequentially stores the calculated current supply time D. The control output unit 31 switches the target value W based on the current supply time D. The control output unit 31 has an upper limit value DX set for the target value W. When the calculated current supply time D is greater than the upper limit value DX, the control output unit 31 limits the current supply time D to the upper limit value DX.

  The displacement Y of the mover 22 is controlled to coincide with the target value W by feedback control by the control output unit 31. When the load applied to the mover 22 (hereinafter “load A”) increases, the displacement Y with respect to the current supply time D decreases. For this reason, in the feedback control, the current supply time D in the next cycle is increased. Further, when the load A decreases, the displacement Y with respect to the current supply time D increases. For this reason, in the feedback control, the current supply time D in the next cycle is reduced. The calculation of the predetermined time Tb and the predetermined time Td can be performed during the predetermined time Ta.

  In the linear actuator 1, the hair is cut by the hair being sandwiched between the outer blade (not shown) fixed to the stator 21 and the movable blade 12 connected to the movable element 22. For this reason, the load A becomes large when the linear actuator 1 cuts hair. The amount of change in load A correlates with the amount of hair. The load A increases as the hair to be cut increases. Moreover, when the hair has been cut, the load A decreases. The linear actuator 1 can smoothly cut the hair by increasing the displacement Y when cutting the hair. For this reason, the control output unit 31 switches the target value W based on the current supply time D correlated with the load A. Specifically, when it is determined that a preset target value switching condition is satisfied based on the current supply time D, the control output unit 31 executes a target value changing process and switches the target value W for displacement.

The control unit 30 executes the following (Processing C1) to (Processing C5) as the target value changing process according to the target value switching condition.
(Process C1) When the current supply time D falls below the lower limit threshold DA over a predetermined period, the control unit 30 switches the target value W to a target value WB that is larger than the target value WA at that time, and sets the proportional gain in feedback control. Change a lot.

  (Process C2) When the current supply time D exceeds the upper limit threshold DB over a predetermined period, the control unit 30 switches the target value W to a target value WB smaller than the target value WA at that time, and sets a proportional gain in feedback control. Change it small.

  (Process C3) When the current supply time D decreases while oscillating in a predetermined cycle and the change width ΔD of the current supply time D exceeds the lower limit range ΔDA, the control unit 30 sets the target value W from A at that time. Is switched to a larger target value WB. Further, the differential gain in the feedback control is changed to be smaller and the integral gain is changed to be larger.

  (Process C4) The control unit 30 increases the current supply time D while oscillating in a predetermined cycle, and the target value WB smaller than the target value WA when the change width ΔD of the current supply time D exceeds the upper limit range ΔDB. Switch to. Further, the differential gain in the feedback control is changed to be smaller and the integral gain is changed to be larger.

  (Process C5) When the current supply time D maintains the upper limit DX over a predetermined period, the control unit 30 switches the target value W to a smaller one. Further, the upper limit value DX is changed to be smaller as the target value W is changed.

FIG. 3 shows an example of how the target value changing process is executed when the load A becomes a constant value after decreasing with time. In this case, the control unit 30 executes the process C1.
Time t10 indicates the time when the load A starts to decrease.

Time t11 indicates the time when the decrease in the load A has stopped. After time t11, the load A is constant.
In the period from time t10 to t11, that is, the period when the load A is decreasing, the displacement Y increases as the load A decreases. For this reason, feedback control is performed so that the current supply time D decreases as the displacement Y increases.

  When the load A becomes sufficiently small, the current supply time D falls below the lower limit threshold DA. Further, when the change of the load A becomes constant, the current supply time D becomes constant. For this reason, when the current supply time D falls below the lower limit threshold DA over a predetermined period (for example, three periods), the target value W of the displacement Y is switched to a target value WB that is smaller than the target value WA before the change. Also, the proportional gain in PID control is changed to be larger.

  Time t12 indicates the time when the current supply time D falls below the lower limit threshold DA over a predetermined period. At this time, the target value W is switched to the target value WB, and the proportional gain is changed. After time t12, the current supply time D is changed to a small value according to the switched target value WB. Since the load A is constant after time t12, the displacement Y converges to the target value WB by feedback control. Further, the current supply time D converges to a constant value by feedback control.

FIG. 4 shows an example of an execution mode of the target value changing process when the load A decreases while vibrating and becomes a constant value. In this case, the control unit 30 executes the process C3.
Time t20 indicates the time when the load A starts to decrease.

Time t21 indicates the time when the decrease in the load A has stopped. The load A is constant after time t21.
In a period from time t20 to t21, that is, a period in which the load A decreases while oscillating, the displacement Y increases while oscillating as the load A decreases. For this reason, feedback control is performed so that the current supply time D decreases as the displacement Y increases.

  When the current supply time D decreases while oscillating in a predetermined cycle (for example, 3 cycles) and the change width falls below the lower limit range ΔDA, the target value W of the displacement Y is smaller than the target value WA before the change. Switch to WB. Further, the differential gain in the feedback control is changed to be smaller, and the integral gain is changed to be larger.

  Whether the current supply time D is decreasing while oscillating in a predetermined cycle is determined by either the number of times the current supply time D has increased or the number of times it has decreased with respect to the change in the current supply time D in two consecutive cycles. It is judged by. When the number of times the current supply time D increases in a predetermined cycle (for example, three cycles) is greater than the number of times the current supply time D decreases, it is determined that the current supply time D increases while oscillating. . When the number of times the current supply time D has decreased in the predetermined period is greater than the number of times the current supply time D has increased, it is determined that the current supply time D has decreased while oscillating.

  Time t22 indicates the time when it is determined that the current supply time D decreases while oscillating in a predetermined cycle. At this time, the target value W is switched from the target value WA to the target value WB. After time t22, the current supply time D is changed to a small value according to the target value WB. Moreover, since the load A becomes constant after time t22, the displacement Y converges to the target value WB by feedback control. Further, the current supply time D converges to a constant value by feedback control.

FIG. 5 shows an example of an execution mode of the target value changing process when the load A increases with time and becomes a constant value. In this case, the control unit 30 executes the process C5.
Time t30 indicates the time when the load A starts to increase.

A time t31 indicates a time when the increase in the load A is stopped. The load A becomes constant after time t31.
In the period from time t30 to t31, that is, during the period when the load A is increasing, the displacement Y decreases as the load A increases. For this reason, feedback control is performed so that the current supply time D increases as the displacement Y decreases. At time t31, the current supply time D reaches the upper limit value DX.

  Time t32 indicates a time when the current supply time D has continued to be equal to or greater than the upper limit value DX over a predetermined period (for example, three periods). At this time, the sum (hereinafter, “total supply time DS”) of the current supply time D in a predetermined cycle becomes longer than the predetermined time DL. The total supply time DS corresponds to about three times the upper limit value DX and not more than three times the upper limit value DX when the predetermined period is three. At this time, the target value W of the displacement Y is switched to a target value WB that is smaller than the target value WA before the change. At this time, the upper limit value DX of the current supply time D is changed to be smaller. After time t32, the current supply time D is changed to a small value according to the switched target value W. Since the load A becomes constant after time t32, the displacement Y converges to the target value WB by feedback control. Further, the current supply time D converges to a constant value by feedback control.

The operation of the linear actuator 1 will be described.
The linear actuator 1 switches the target value W when the current supply time D increases or decreases. An increase or decrease in the current supply time D correlates with an increase or decrease in the load A. For this reason, the linear actuator 1 can switch the target value W according to the load A.

The linear actuator 1 has the following effects.
(1) In the linear actuator 1, when the load A applied to the mover 22 increases or decreases, the deviation between the displacement Y and the target value W increases. When the load A decreases, the displacement Y with respect to the current supply time D increases. For this reason, when the load A decreases, the current supply time D is feedback-controlled so as to decrease. Further, when the load A increases, the displacement Y with respect to the current supply time D decreases. For this reason, when the load A increases, the current supply time D is feedback-controlled so as to increase.

  The linear actuator 1 switches the target value W based on the increase or decrease in the current supply time D. That is, the target value W can be switched according to the load A. For this reason, the convenience of the linear actuator 1 can be improved.

  (2) The linear actuator 1 performs control according to increase / decrease of the load A using the current supply time D. Therefore, a circuit configuration for detecting increase / decrease in the load A, for example, control according to the load A without using a load current detection circuit that detects the load A by comparing the displacement Y with the past displacement Y is performed. Can be executed.

  (3) When the sum of the current supply time D in the unit time is larger than the predetermined time, it is estimated that the load A is in an abnormal state. The linear actuator 1 reduces the upper limit value DX based on the fact that the total supply time DS, which is the sum of the current supply time D in unit time, becomes larger than the predetermined time DL. For this reason, it can suppress that the electric current supply time D becomes large too much. In other words, the linear actuator 1 can determine that the load A is in an abnormal state based on the total supply time DS becoming greater than the predetermined time DL. Further, by reducing the upper limit value DX of the current supply time D, heat generation due to overcurrent can be suppressed.

  (4) When switching the target value W, the linear actuator 1 switches the proportional gain, the differential gain, and the integral gain. For this reason, the vibration of the displacement Y and the current supply time D can be controlled. For this reason, it can suppress that operation | movement of the needle | mover 22 at the time of switching of the target value W becomes unstable. For this reason, the time for the target value W to converge the displacement Y can be shortened.

(Second Embodiment)
The linear actuator 1 of 2nd Embodiment has a different structure in the following part compared with the linear actuator 1 of 1st Embodiment, and has the same structure in another part. That is, the linear actuator 1 switches the target value W in stages. In the description of the linear actuator 1 of the second embodiment, the same reference numerals as those of the linear actuator 1 of the first embodiment are attached to the configurations common to the linear actuator 1 of the first embodiment.

  When the target value W is changed from the target value WA at that time to the target value WB according to the target value switching condition, the control unit 30 gradually changes from the target value WA before switching to the final target value WB through the intermediate target value. Change to As the intermediate target value, an intermediate value between the target value WA and the final target value WB is set.

FIG. 6 shows an example of how the target value changing process is executed when the load A becomes a constant value after decreasing with time. In this case, the control unit 30 executes the process C1.
Time t41 indicates the time when the decrease in the load A has stopped. The load A becomes constant after time t41.

  When the load A becomes sufficiently small, the current supply time D falls below the lower limit threshold DA. Further, when the change of the load A becomes constant, the current supply time D becomes constant. For this reason, when the current supply time D falls below the lower limit threshold DA over a predetermined period (for example, three periods), the target value W of the displacement Y is switched stepwise toward a smaller final target value WB. Further, every time the target value W is switched, the proportional gain in the PID control is changed to be larger.

Time t42 indicates the time when the target value W is switched to the intermediate target value W1. After time t42, the target value W decreases stepwise.
Time t43 indicates the time when the target value W is switched to the intermediate target value W2. The target value W is switched to an intermediate target value W2 smaller than the intermediate target value W1 when the displacement Y is smaller than the intermediate target value W1 and smaller than the intermediate target value W1 by a predetermined value ΔW1.

  Time t44 indicates the time when the target value W is switched to the intermediate target value W3. The target value W is switched to an intermediate target value W3 that is smaller than the intermediate target value W2 when the displacement Y is smaller than the intermediate target value W2 and smaller than the intermediate target value W2 by a predetermined value ΔW2.

  Time t45 indicates the time when the target value W is switched to the final target value WB. The final target value WB is switched to a final target value WB smaller than the intermediate target value W3 when the displacement Y is smaller than the intermediate target value W3 and smaller than the intermediate target value W3 by a predetermined value ΔW3.

  After time t45, since the load A is constant, the displacement Y converges to the final target value WB by feedback control. Further, the current supply time D converges to a constant value by feedback control.

The linear actuator 1 of the second embodiment has the following effects in addition to the effects (1) to (4) of the first embodiment.
(5) When switching the target value W, the linear actuator 1 switches from the target value WA before switching to the final target value WB through the intermediate target values W1 to W3. For this reason, it can suppress that the displacement Y changes rapidly with the target value W changing.

(Third embodiment)
The linear actuator 1 of 3rd Embodiment has a different structure in the following part compared with the linear actuator 1 of 1st Embodiment, and has the same structure in another part. That is, the linear actuator 1 of the third embodiment sets the accumulated deviation B in the integral control to “0” when the target value W is switched. In addition, the description of the linear actuator 1 of 3rd Embodiment attaches | subjects the code | symbol same as the linear actuator 1 of 1st Embodiment with respect to the structure which is common in the linear actuator 1 of 1st Embodiment.

  After the target value W is switched from the target value WA to the target value WB, the control unit 30 accumulates the integral control when the difference between the displacement Y and the target value WB changes from a value larger than the predetermined difference to a predetermined difference or less. Deviation B is set to “0”.

FIG. 7 shows an example of an execution mode of the target value changing process when the target value W is changed to a smaller value by the process C1, the process C2, or the process C5.
Time t51 indicates the time when the target value W is switched. After time t51, the current supply time D is changed to a small value according to the switched target value WB. Since the load A becomes constant after time t51, the displacement Y converges to the target value WB by feedback control. Further, the current supply time D converges to a constant value by feedback control. Further, the cumulative deviation B starts to decrease as the target value WB is switched.

  Time t52 indicates the start time of the calculation cycle immediately after the cycle in which the displacement Y is less than the target value WB and has changed to a value smaller than the target value W by a predetermined value ΔYA. At this time, the accumulated deviation B generated in the integral control in the feedback control is cleared and set to “0”.

The linear actuator 1 of the third embodiment has the following effects in addition to the effects (1) to (4) of the first embodiment.
(6) With the switching of the target value W, the linear actuator 1 sets the accumulated deviation B to “0”. For this reason, the influence of the cumulative deviation B before switching of the target value W is eliminated. For this reason, the time until the displacement Y reaches the target value W after the switching of the target value W is longer than that of the virtual linear actuator 1 (two-dot chain line in FIG. 7) in which the accumulated deviation B is not set to “0”. The risk of becoming is reduced.

(Fourth embodiment)
The linear actuator 1 of 3rd Embodiment has a different structure in the following part compared with the linear actuator 1 of 1st Embodiment, and has the same structure in another part. That is, the linear actuator 1 of the third embodiment sets the accumulated deviation B to “0” when the target value W is switched. In addition, the description of the linear actuator 1 of 3rd Embodiment attaches | subjects the code | symbol same as the linear actuator 1 of 1st Embodiment with respect to the structure which is common in the linear actuator 1 of 1st Embodiment.

The control unit 30 corrects the differential gain in the differential control to “0” in the calculation cycle for switching the target value W from the target value WA to the target value WB.
FIG. 8 shows an example of an execution mode of the target value changing process when the target value W is changed to a larger value by the process C2 or the process C4.

  Time t61 indicates the time when the target value W is switched. After time t61, the current supply time D is changed to a target value WB that is larger than the target value WA before switching. Since the load A is constant after time t61, the displacement Y converges to the target value WB by feedback control. Further, the current supply time D converges to a constant value by feedback control. At this time, the differential gain of the differential control is corrected to “0”.

  Time t62 indicates the time of the calculation cycle in which the differential control is executed immediately after the target value W is switched. At this time, the correction of “0” of the differential gain of the differential control is finished, and after time t62, the differential control is executed with the normal differential gain.

In addition to the effects (1) to (4) of the first embodiment, the linear actuator 1 of the fourth embodiment has the following effects.
(7) A virtual linear actuator (two-dot chain line in FIG. 8) that does not correct the differential gain to “0” exceeds the displacement Y according to the deviation between the target value WA before switching and the target value WB after switching. A shoot occurs.

  The linear actuator 1 corrects the differential gain in the calculation cycle when the target value W is switched as the target value W is switched to “0”. For this reason, the influence of the deviation of the target value W in the switching of the target value W is eliminated. For this reason, compared with a virtual linear actuator (two-dot chain line in FIG. 8), the overshoot amount of the displacement Y immediately after switching the target value W can be reduced. For this reason, the possibility that the time until the displacement Y reaches the target value W after switching the target value W is reduced.

  (8) The linear actuator 1 corrects only the differential gain to “0” in one calculation cycle when the target value W is switched in accordance with the switching of the target value W. Thereby, by continuing the correction | amendment which makes a differential gain "0", a possibility that the load response performance obtained by a differential gain may deteriorate can be reduced.

(Other embodiments)
This hair removal instrument contains embodiment other than said each embodiment. Hereinafter, the modification of said each embodiment as other embodiment of this hair removal tool is shown. The following modifications can be combined with each other.

  The linear actuator 1 according to the third embodiment sets the accumulated deviation B to “0” when the target value W is switched. However, the configuration of the linear actuator 1 is not limited to this. For example, when the target value W is switched, the linear actuator 1 of the modified example brings the accumulated deviation B close to “0”.

  -The following structure can also be added to the linear actuator 1 of 3rd Embodiment. The linear actuator 1 of this modification has a lower limit value of the current supply time D. When switching the target value W to a smaller value, the linear actuator 1 changes the lower limit value of the current supply time D to a smaller value. According to this configuration, the target value WB after switching can be reached in a shorter time. Moreover, if the linear actuator 1 is equipped with the brake device which generates a negative thrust, a structure will become complicated. The linear actuator 1 of this modification can increase the decrease rate of the displacement Y with a simple configuration as compared with a configuration that includes a brake device or the like and generates a negative thrust.

  The linear actuator 1 of the fourth embodiment corrects the differential gain to “0” when the target value W is switched. However, the configuration of the linear actuator 1 is not limited to this. For example, when the target value W is switched, the linear actuator 1 according to the modification performs correction to bring the differential gain closer to “0”.

  The linear actuator 1 of the fourth embodiment corrects the differential gain of the calculation cycle when the target value W is switched to “0”. However, the configuration of the linear actuator 1 is not limited to this. For example, the linear actuator 1 of the modified example corrects the differential gain in the calculation cycle immediately after the target value W is switched to “0”.

  The linear actuator 1 of the fourth embodiment corrects the differential gain of one calculation cycle to “0” as the target value W is switched. However, the configuration of the linear actuator 1 is not limited to this. For example, the linear actuator 1 according to the modification corrects the differential gain to “0” over a predetermined period immediately after the target value W is switched.

  The third embodiment and the fourth embodiment can be combined. That is, in the linear actuator 1 of the third embodiment, the differential gain of the calculation cycle when the target value W is switched is set to “0”. The linear actuator 1 of this modified example can converge the displacement Y faster than the target value W after the target value W is switched.

  The linear actuator 1 of each embodiment switches the proportional gain, the differential gain, and the integral gain when the target value W is switched. However, the configuration of the linear actuator 1 is not limited to this. For example, when the target value W is switched, the linear actuator 1 according to the modification does not switch the proportional gain, the differential gain, and the integral gain.

  In the linear actuator 1 of each embodiment, the stator 21 is fixed to the frame 11. However, the configuration of the linear actuator 1 is not limited to this. For example, the modified stator 21 is connected to the frame 11 by an elastic member. For this reason, the stator 21 vibrates with respect to the frame 11 as the movable element 22 reciprocates.

  -The control part 30 of each embodiment has detected the displacement Y as a driving force by detecting the induced voltage E which generate | occur | produces in the coil 23A. However, the configuration of the control unit 30 is not limited to this. For example, the control unit 30 according to the modification includes a sensor that directly detects displacement, speed, or acceleration as a driving force of the mover 22 and calculates the displacement Y based on the output of the sensor.

  The control unit 30 of each embodiment calculates the current supply time D based on the difference between the displacement Y as the driving force of the mover 22 and the target value W. However, the configuration of the control unit 30 is not limited to this. For example, the control unit 30 of the modification calculates the current supply time D based on the speed or acceleration as the driving force of the mover 22.

  -The 2nd magnet 24 of each embodiment is formed as a permanent magnet. However, the configuration of the second magnet 24 is not limited to this. For example, the modified second magnet 24 is formed as an electromagnet.

  In the drive unit 20 of each embodiment, the first magnet 23 is attached to the stator 21 and the second magnet 24 is attached to the mover 22. However, the configuration of the drive unit 20 is not limited to this. For example, in the driving unit 20 of the modification, the first magnet 23 is attached to the mover 22 and the second magnet 24 is attached to the stator 21.

-Although the linear actuator 1 of each embodiment was applied to the electric razor, it can also be applied to other hair removal instruments, such as a clipper and a hair removal device.
-Although the linear actuator 1 of each embodiment was applied to the hair removal instrument, it can also be applied to the linear actuator employ | adopted other than a hair removal instrument.

  DESCRIPTION OF SYMBOLS 1 ... Linear actuator, 22 ... Movable element, 23 ... 1st magnet (electromagnet), 24 ... 2nd magnet (permanent magnet), 30 ... Control part, 40 ... Amplitude control part (drive amount detection part).

Claims (6)

A first magnet formed as an electromagnet;
A second magnet formed as a permanent magnet or an electromagnet;
One of the first magnet and the second magnet is attached, and a mover that linearly moves with respect to the other of the first magnet and the second magnet;
The amount of current supplied to the first magnet is controlled by a current supply time, and the displacement of the control unit that moves the mover in the linear motion, the speed of the reciprocation of the mover, and the acceleration of the reciprocation A drive amount detector that detects at least one drive amount,
The control unit performs feedback control of the current supply time to bring the drive amount close to the target value from the difference between the drive amount and the target value of the drive amount, and increases or decreases the current supply time. A linear actuator that switches the target value based on the linear actuator. The control unit has an upper limit value for limiting the current supply time switched according to the target value, and is based on the total supply time being a sum of unit times of the current supply time being larger than a predetermined time The linear actuator according to claim 1, wherein the upper limit value is reduced. The control unit has a final target value as the target value, and an intermediate target value between the final target value and the target value before switching, and when the target value is switched, The linear actuator according to claim 1, wherein the linear actuator is gradually switched to the final target value. The control unit performs the feedback control of the current supply time to bring the drive amount closer to the target value using integral control or differential integration control from the difference between the drive amount and the target value of the drive amount, and the target When the difference between the drive amount and the switched target value changes from a value larger than a predetermined difference to the predetermined difference or less after the value is switched, the accumulated deviation in the integral control or the differential integral control is set to “0”. The linear actuator as described in any one of Claims 1-3. The control unit performs the feedback control of the current supply time to bring the drive amount close to the target value using differential control or differential integration control from the difference between the drive amount and the target value of the drive amount, and the target The correction gain in the calculation cycle when the value is switched, or the differential gain in the calculation cycle immediately after switching the target value is set to “0” or close to “0”. Linear actuator. A first magnet formed as an electromagnet;
A second magnet formed as a permanent magnet or an electromagnet;
One of the first magnet and the second magnet is attached, and a mover that linearly moves with respect to the other of the first magnet and the second magnet;
The amount of current supplied to the first magnet is controlled by a current supply time, and the displacement of the control unit that moves the mover in the linear motion, the speed of the reciprocation of the mover, and the acceleration of the reciprocation A drive amount detector that detects at least one drive amount,
The control unit performs feedback control of the current supply time to bring the drive amount close to the target value from the difference between the drive amount and the target value of the drive amount, and increases or decreases the current supply time. A linear actuator that determines increase / decrease in the load applied to the mover based on the linear actuator.