JP3417237B2 - Driving device using electromechanical transducer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device using an electromechanical conversion element, for example, an XY driving table, a photographing lens of a camera, a projection lens of an over head projector, a lens of binoculars. The present invention relates to a driving device using an electromechanical conversion element suitable for driving general precision mechanical devices such as driving parts.

[0002]

2. Description of the Related Art Conventionally, a driving device using an electric motor has been used for driving an XY driving table and a photographing lens of a camera, but the device becomes large and a magnetic field is generated. It was pointed out that inconveniences such as noise were generated. Therefore, as means for solving such various problems, the present applicant frictionally couples a moving member to an actuator using an electromechanical conversion element, that is, a driving member fixedly coupled to the electromechanical conversion element, An actuator has been proposed in which a drive pulse having a sawtooth waveform is applied to the electromechanical conversion element to generate displacement in different expansion / contraction directions at different speeds to move a moving member frictionally coupled to the driving member in a predetermined direction.

14 to 16 show an example of an actuator using the electromechanical conversion element described above. FIG. 14 is a perspective view showing the actuator disassembled into its constituent members, and FIG. 15 shows the actuator. FIG. 16 is a perspective view showing an assembled state, and FIG. 16 is a sectional view showing a structure of a contact portion between the drive shaft, the slider block, and the pad.

In FIGS. 14 to 16, an actuator 100 includes a frame 101, a support block 103, and a support block 103.
4, a drive shaft 106, a piezoelectric element 105, a slider block 102, and the like. The drive shaft 106 is supported by a support block 103a and a support block 104 so as to be movable in the axial direction. One end of the piezoelectric element 105 is adhesively fixed to the support block 103, and the other end is adhesively fixed to one end of the drive shaft 106. The drive shaft 106 is supported so as to be displaceable in the axial direction (the direction of arrow a and the opposite direction) when the piezoelectric element 105 is displaced in the thickness direction.

A drive shaft 106 extends laterally through the slider block 102, and an opening 102a is formed in the upper portion of the drive shaft 106, so that the upper half of the drive shaft 106 is exposed. Further, the drive shaft 1 is provided in the opening 102a.
The pad 108 that abuts on the upper half of 06 is fitted and the projection 108a is provided on the upper portion of the pad 108. The projection 108a of the pad 108 is pushed down by the plate spring 109, and the pad 108 is attached to the pad 108. A downward urging force F that abuts against is applied. Incidentally, 110 is a screw for fixing the leaf spring 109 to the slider block 102. The structure of the contact portion between the drive shaft 106, the slider block 102, and the pad 108 can be understood with reference to FIG.

With the above structure, the slider block 102 including the pad 108 and the drive shaft 106 are provided with a leaf spring 109.
Are pressed against each other by the urging force F and are frictionally coupled.

Next, the operation will be described. First, when a sawtooth wave drive pulse having a gently rising portion and a rapidly falling portion as shown in FIG. 17A is applied to the piezoelectric element 105, the piezoelectric element 105 is driven at the gently rising portion of the driving pulse. The drive shaft 106, which is gradually extended and displaced in the thickness direction and coupled to the piezoelectric element 105, is also in the positive direction (direction of arrow a).
Displace gently to. At this time, the slider block 102 frictionally coupled to the drive shaft 106 moves in the positive direction together with the drive shaft 106 by the friction coupling force.

At the rapid falling edge of the drive pulse, the piezoelectric element 105 is rapidly contracted and displaced in the thickness direction, and the piezoelectric element 1
The drive shaft 106 connected to 05 is also rapidly displaced in the negative direction (the direction opposite to the arrow a). At this time, the slider block 102 frictionally coupled to the drive shaft 106 overcomes the friction coupling force by the inertial force and substantially stays at that position and does not move. By continuously applying the drive pulse to the piezoelectric element 105, the slider block 102 can be continuously moved in the positive direction.

The term "substantially" as used herein refers to the slider block 10 in both the forward direction and the opposite direction.
Also included are those that follow the friction coupling surface between the drive shaft 106 and the drive shaft 106 with slippage, and move in the direction of arrow a as a whole due to the difference in drive time.

To move the slider block 102 in the opposite direction (the direction opposite to the arrow a), the piezoelectric element 10
17 is changed to change the waveform of the sawtooth wave drive pulse applied to FIG.
This can be achieved by applying a drive pulse having a rapid rising portion and a gradual falling portion as shown in (b).

[0011]

In the actuator described above, the pad 1 which abuts on the upper half of the drive shaft 106 in the opening 102a in the upper portion of the slider block 102.
08 is inserted, and the opening 102a and the pad 108 are
The fitting gap between and is set as small as possible, but the gap required for assembly remains.

On the other hand, the slider block 102 and the pad 1
If there is a gap between 08, when the drive shaft 106 moves in the axial direction, the pad 108 moves together with the drive shaft 106 by the gap, and the drive energy received from the drive shaft 106 cannot be sufficiently transmitted to the slider block 102. Drive energy is lost.

Further, in order to make the fitting gap between the opening 102a and the pad 108 as small as possible, it is necessary to process with high processing accuracy, which results in an increase in cost. Further, in order to reduce the fitting gap to zero, the opening 102
There is also processing means such as press-fitting the pad 108 into a.
When the fitting gap is reduced to zero by such processing means, the pad 108 is pushed down by the leaf spring 109 to drive the drive shaft 106.
There is an inconvenience that an appropriate frictional force cannot be applied between and.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a drive device in which drive energy is not lost due to a fitting gap.

[0015]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems and comprises an electromechanical conversion element, a drive member fixedly coupled to the electromechanical conversion element, and displaced together with the electromechanical conversion element, and the drive unit. A driven member frictionally coupled to the member, a friction member fitted into the opening of the driven member and frictionally coupled to the driving member, drive pulse generating means for giving expansion / contraction displacement to the electromechanical conversion element, and drive control Equipped with means,
A drive device using an electromechanical conversion element for driving a drive member by causing the electromechanical conversion element to expand and contract by the drive pulse generation means, and moving a driven member frictionally coupled to the drive member in a predetermined direction. An elastic member is arranged in a fitting gap between the friction member and the driven member fitted into the opening of the driven member.

The elastic member arranged in the fitting gap between the friction member fitted in the opening of the driven member and the driven member is driven by the spring constant k of the elastic member in the displacement direction of the electromechanical transducer. When the frictional force between the member and the driven member is F and the displacement of the electromechanical conversion element is x, the spring constant k is k
The elastic member is preferably made of a material having a value represented by> F / 10x.

The elastic member arranged in the fitting gap is made of one or more materials selected from urethane resin, silicon resin, vinyl resin, polyamideimide resin, and rubber. Good to do.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an actuator 10 will be described with reference to FIGS. The actuator 10 is composed of a frame 11, support blocks 13 and 14, a drive shaft 16, a piezoelectric element 15, a slider block 12, and the like. The drive shaft 16 is movable in the axial direction by the support blocks 13 a and the support blocks 14. Supported by. One end of the piezoelectric element 15 is adhesively fixed to the support block 13, and the other end is the drive shaft 1.
6 is bonded and fixed to one end. The drive shaft 16 is the piezoelectric element 15
When it is displaced in the thickness direction, it is supported so as to be displaceable in the axial direction (the direction of arrow a and the opposite direction).

The friction coupling portion where the slider block 12 and the pad 18 are frictionally coupled to the drive shaft 16 has the drive shaft 16 penetrating the slider block 12 in the lateral direction as shown in FIG. Opening 12a at the top
Is formed, and the upper half of the drive shaft 16 is exposed. In addition, a pad 18 that abuts on the upper half of the drive shaft 16 is fitted into the opening 12a, and the pad 18 is pushed down by a leaf spring 20 to apply a downward biasing force F that abuts the drive shaft 16. The slider block 12 including the pad 18 and the drive shaft 16 are frictionally coupled to each other.

As shown in FIG. 3, the slider block 12
A coil spring 19 is fitted in a gap H between the pad 18 and the pad 18. As a result, the pad 18 is pushed to the left side in FIG. 3 and abuts the upper half of the drive shaft 16 while keeping contact with the slider block 12, so that the axial displacement of the drive shaft 16 caused by the expansion and contraction displacement of the piezoelectric element 15 is generated. The displacement is transmitted to the slider block 12 and the pad 18 without waste.

Assuming that the frictional force between the driving member and the driven member is F and the displacement (amplitude) of the driving shaft is x, the pad 18 does not vibrate even when the driving shaft axially expands or contracts (vibrates). In order to achieve this, it is considered necessary that the spring constant k in the displacement direction of the elastic member such as the coil spring, the leaf spring, or the synthetic resin plate fitted in the gap H satisfies at least the condition of k> F / x. According to the result of the experiment, if the spring constant k of the elastic member in the displacement direction satisfies the condition of k> F / 10x, the effect of improving the performance is recognized.

A coil spring, a leaf spring, a synthetic resin plate, or the like can be used as the elastic member fitted in the gap H, and the pad can be kept in contact with the slider block. As the synthetic resin plate material used as the elastic member, urethane resin, silicon resin, vinyl resin, polyamideimide resin, rubber, etc. are suitable, and one or more materials selected from these materials are used. It is good to configure with.

[0023]

Embodiments of the present invention will be described below.
First, the actuator of the present invention is similar to the structure described above in the prior art, but the structure of the slider block and the pad portion is different from that of the conventional example.

FIG. 1 is a perspective view showing the actuator of the present invention by disassembling the constituent members, FIG. 2 is a perspective view showing the assembled state of the actuator shown in FIG. 1, and FIG. 3 is a drive shaft and a slider block. It is sectional drawing which shows the structure of the frictional coupling part with a pad.

1 and 2, the actuator 10 is shown.
Is a frame 11, support blocks 13 and 14, drive shaft 1
6, a piezoelectric element 15, a slider block 12, and the like. The drive shaft 16 is supported by a support block 13a and a support block 14 so as to be movable in the axial direction. One end of the piezoelectric element 15 is adhesively fixed to the support block 13, and the other end is adhesively fixed to one end of the drive shaft 16. Drive shaft 16
When the piezoelectric element 15 is displaced in the thickness direction, is supported so as to be displaceable in the axial direction (the arrow a direction and the opposite direction).

As shown in the perspective view of FIG. 1 and the sectional view of FIG. 3, the slider block 12 and the pad 18 are frictionally connected to the drive shaft 16. As shown in the perspective view of FIG. 16 penetrates, and an opening 12a is formed in the upper part where the drive shaft 16 penetrates.
The upper half of 6 is exposed. A pad 18 that abuts on the upper half of the drive shaft 16 is fitted into the opening 12a. The pad 18 is provided with a protrusion 18a on the upper portion thereof, and the protrusion 18a of the pad 18 is formed by the leaf spring 20. A downward urging force F that contacts the drive shaft 16 is applied to the pad 18 by being pushed down. The slider block 12 including the pad 18 and the drive shaft 16 are pressed against each other by the urging force F of the leaf spring 20 and frictionally coupled.

Reference numeral 21 is a screw for fixing the leaf spring 20 to the slider block 12, and the urging force F of the leaf spring 20 can be adjusted by adjusting the tightening amount of the screw 21. The screw hole 22 is a screw hole for attaching the slider block 12 to a member to be moved.

Hereinafter, the slider block 12 and the pad 1 will be described.
A configuration of a frictional coupling portion in which 8 frictionally couples with the drive shaft 16 and a modification thereof will be described with reference to FIGS. 3 to 6. 3 to 6, the leaf spring 20 that pushes down the pad 18 is not shown in the drawings.

As shown in FIG. 3, the slider block 12
There is a gap H between the pad 18 and the pad 18, and the coil spring 19 is fitted in the gap H. This makes the pad 18
Is abutted against the upper half of the drive shaft 16 while being kept in contact with the slider block 12 by being pushed to the left side in FIG.
The axial displacement generated in the drive shaft 16 due to the expansion and contraction displacement of the piezoelectric element 15 is transmitted to the slider block 12 and the pad 18 without waste.

Although the coil spring 19 is fitted in the gap H between the slider block 12 and the pad 18 described above, the member fitted in the gap H is not limited to the coil spring. 4 to 6 show other examples of the members fitted into the gap H, and the configuration shown in FIG.
The leaf spring 23 is inserted in the pad spring 23, and like the coil spring, the pad 18 is pressed to the left side in FIG. 4 to keep the pad 18 in contact with the slider block 12.

In the structure shown in FIG. 5, the synthetic resin plate 2 is provided in the gap H.
4, the pad 18 is pressed to the left side in FIG. 5 by utilizing the elasticity of the synthetic resin plate 24 to keep the pad 18 in contact with the slider block 12.

Table 1 shows the results of comparative experiments of driving speeds in the case where the synthetic resin plate was not press-fitted into the gap H and when it was press-fitted.

As the synthetic resin plate material, urethane resin,
In addition to silicone resin, vinyl resin, polyamide-imide resin and the like, rubber and the like are suitable, and one or more materials selected from these materials may be used.

Table 1: ―――――: ――――――――――――――: ―――――――――――――: ： Load ： When the synthetic resin plate is not press-fitted ： When a synthetic resin plate is pressed in: ： ――――――――――――――――――――――――――――――――: ： 40g ： 23 mm / sec ： 31 mm / sec :: 60 g: 18 mm / sec: 23 mm / sec :: ―――: ――――――――――――――: ―――――――――――― -: However, the thickness of the synthetic resin plate is 0.1 mm, the elastic coefficient is about 200 kgf / mm ² , and the spring constant is about 1000 kgf / mm.
In this case, it is desirable that the spring constant is 200 kgf / mm or more, and even at 20 kgf / mm, a temporary effect was recognized.
Further, when the thickness of the synthetic resin plate was thin, the effect was recognized even with a resin material having a smaller elastic coefficient.

Here, when the frictional force between the driving member and the driven member is F and the displacement (amplitude) of the driving shaft is x, the pad 18 is also caused by expansion / contraction displacement (vibration) in the axial direction of the driving shaft. Does not vibrate, a spring constant k in the displacement direction of an elastic member such as a coil spring, a leaf spring, or a synthetic resin plate fitted in the gap H is required.
However, it is considered necessary to satisfy at least the condition represented by the following formula (1).

K> F / x (1) According to the results of the experiment, the spring constant k in the displacement direction of the elastic member
As a result, it has been found that if the condition represented by the following formula (2) is satisfied, it is effective in improving the performance of a linear actuator using this type of piezoelectric element.

K> F / 10x (2) In the configuration shown in FIG. 6, the liquid synthetic resin material 25 is pressed into the gap H on the left and right of the pad 18. The gap H is filled and solidified by pouring, and the pad 18 is kept in contact with the slider block 12 by the elasticity of the filled and solidified synthetic resin material 25. According to this structure, the pad 18 is
It is possible to suppress energy loss due to generation of noise or heat generated by collision between the slider block 12 and the slider block 12. Further, since the synthetic resin material is injected under pressure, there is an effect that the assembly becomes easy.

The driving of the actuator having the above structure is the same as the driving of the actuator described in the prior art.
The piezoelectric element 15 has a sawtooth wave drive pulse having a gentle rising portion and a rapid falling portion as shown in FIG. 17A, or a rapid rising portion and a gentle rising portion as shown in FIG. 17B. By applying the sawtooth wave drive pulse having the falling portion, the slider block 12 frictionally coupled to the drive shaft 16 can be driven in a predetermined direction.

Next, a second example of the structure of the portion where the slider block and the pad are frictionally coupled to the drive shaft will be described. In the frictional coupling portion shown in FIGS. 3 to 6 described above, the drive shaft 16 penetrates the slider block 12 in the lateral direction,
A pad 18 that abuts the upper half of the drive shaft 16 is fitted into the upper opening 12a through which the drive shaft 16 penetrates, and the pad 18 is pushed down by a leaf spring 20 so that the pad 18 abuts the drive shaft 16. A downward biasing force F is applied.

In this structure, the frictional force generated between the slider block and pad and the drive shaft is generated by the downward urging force F of the leaf spring, and the optimum frictional force is obtained according to the expected load. A leaf spring having an appropriate elastic coefficient is selected so that the leaf spring 20 can be generated, and fine adjustment of the frictional force is performed by a screw 21 for fixing the leaf spring 20. This configuration is simple and works well when load fluctuations are small.

However, the optimum frictional force for obtaining the maximum driving speed varies depending on the load as shown in FIG. That is, when the load is small, as shown by the line (a),
The maximum speed is obtained when the frictional force is F1, the maximum speed is obtained when the load is large, as shown by the line (c), and the maximum velocity is obtained when the frictional force is F3, as shown by the line (b) at an intermediate load. Maximum speed is obtained when the frictional force is F2.

Therefore, the construction of the friction coupling portion between the slider block and the pad and the drive shaft as shown in FIGS. 3 to 6 is not suitable for the use where the load fluctuates. In the second example and the third example described below, the biasing force F of the frictional coupling portion can be finely adjusted, and an optimum frictional force can be generated according to the change of the load.

FIG. 8 is a sectional view showing a second example of the structure of the friction coupling portion, which is a sectional view taken along a plane perpendicular to the axial direction of the drive shaft. Reference numeral 31 is a slider block, which has a substantially U-shaped cross section, and is provided with two fork-shaped members 32 and 33 joined by a hinge portion 34. Coupling portions 32a and 33a having arcuate friction coupling surfaces directed inwardly in a substantially U shape are formed at positions close to the open ends of the fork-shaped members 32 and 33. The two fork-shaped members 32, 33 are urged by the elasticity of the hinge portion 34 in the direction in which the fork-shaped members 32, 33 are closed, and the drive shaft 16 penetrating the coupling portions 32a, 33a is It is held by being strongly frictionally coupled by the coupling portions 32a and 33a.

The fork-shaped members 32 and 33 of the slider block 31 are provided with piezoelectric elements 35 at positions distant from the coupling portions 32a and 33a, and the ends of the piezoelectric elements 35 in the direction of expansion and contraction are forked. It is adhesively fixed to the strip members 32 and 33. When a voltage is applied to the piezoelectric element 35 to cause extension displacement or contraction displacement, the coupling portions 32a and 33a can be displaced in a direction away from or close to the drive shaft 16. By adjusting the magnitude of the expansion displacement or the contraction displacement generated in the piezoelectric element 35, the coupling portions 32a, 3
It is possible to adjust the urging force F by which 3a presses against the drive shaft 16 and generate an optimum frictional force according to the load.

FIG. 9 is a sectional view showing a third example of the structure of the frictional coupling portion, which is a sectional view taken along a plane perpendicular to the axial direction of the drive shaft. Reference numeral 31 is a slider block, which has a substantially U-shaped cross section, and is provided with two fork-shaped members 32 and 33 joined by a hinge portion 34. Also, the fork-shaped member 32,
At a position close to the open end of 33, coupling portions 32a and 33a having arcuate surfaces facing inward are formed. The drive shaft 16 penetrates the coupling portions 32a and 33a and is frictionally coupled. ing. The above points are the same as the above-mentioned second configuration.

Fork-shaped member 3 of slider block 31
2 and 33 are acting members 37 which are connected to each other by the hinge portion 34, and two arm portions 37a and 37b which are connected to the fork-shaped members 32 and 33 at a position close to the hinge portion 34. The piezoelectric element 35 is connected between the hinge portion 34 and the acting member 37, and is bonded and fixed. The two fork-shaped members 32 and 33 include a hinge portion 34.
The fork-shaped members 32 and 33 are urged in the closing direction by the elasticity of the drive shaft 16, and the drive shaft 16 penetrating the coupling portions 32a and 33a is strongly frictionally coupled and held by the coupling portions 32a and 33a.

When a voltage is applied to the piezoelectric element 35 to generate an expansion displacement or a contraction displacement, the acting member 37 moves in a direction away from or close to the hinge portion 34.
This movement is magnified via arms 37a and 37b,
The two fork-shaped members 32 and 33 are connected to each other by a connecting portion 32a,
33a is displaced in a direction away from or close to the drive shaft 16. By adjusting the magnitude of the elongation displacement or the contraction displacement generated in the piezoelectric element 35, the coupling portion 32a,
It is possible to adjust the urging force F that 33a presses against the drive shaft 16 and generate an optimum frictional force according to the load.

Next, a structure for fixing the actuator to the drive shaft so that the slider block does not move unintentionally when the drive of the actuator is stopped will be described.

FIG. 10 is a view showing the structure of a frictional coupling portion for fixing the slider block to the drive shaft, and is a sectional view taken along a plane perpendicular to the axial direction of the drive shaft. This is a structure in which the slider block is fixed to the drive shaft in addition to the structure of the second friction coupling portion shown in FIG. The same parts as those of the frictional coupling portion shown in FIG. 8 are designated by the same reference numerals, and the detailed description thereof will be omitted. Only the constituent parts for fixing the slider block will be described.

Reference numeral 31 is a slider block, which is a hinge portion 34.
It is provided with two fork-shaped members 32 and 33 which are connected by. The two fork-shaped members 32 and 33 include a hinge portion 34.
The fork-shaped members 32 and 33 are urged in the closing direction by the elasticity of the drive shaft 16, and the drive shaft 16 penetrating the coupling portions 32a and 33a is strongly frictionally coupled and held by the coupling portions 32a and 33a.

In order to fix the slider block to the drive shaft, the fork-shaped member 32 is provided with an arc on the side opposite to the drive shaft 16.
And a hinge member 38 is provided.
Are bound to. Fork-shaped member 32 and arm member 38
A piezoelectric element 39 is disposed between the two, and both ends of the piezoelectric element 39 are adhesively fixed to the fork-shaped member 32 and the arm member 38, respectively.

When the slider block is fixed to the drive shaft, a voltage is applied to the piezoelectric element 39 to cause the piezoelectric element 39 to expand and displace in the thickness direction. As a result, the fork-shaped member 32 is pushed down in FIG. 10, the drive shaft 16 is strongly pressed against the coupling portions 32a and 33a, and the slider block 31 can be fixed to the drive shaft 16. To release the fixation, the application of voltage to the piezoelectric element 39 may be stopped.

FIG. 11 is a block diagram showing the control circuit of the actuator. This control circuit 50 has the above-described second friction coupling portion configuration shown in FIG. 8 or the third friction coupling portion configuration shown in FIG. 9, and further has a configuration in which the slider block shown in FIG. 10 is fixed to the drive shaft. It is applicable.

The control circuit 50 includes a drive control circuit 51, a drive pulse generating circuit 52, a frictional force adjusting voltage generating circuit 53,
A moving body speed detection circuit 56 for calculating the driving speed of the slider block, a reference speed storage circuit 57 for storing preset reference speed data, a comparison circuit 58, a frictional force control circuit 59, and a slider block fixing voltage generation. It is composed of a circuit 60. A speed sensor 55 for detecting the moving speed of the slider block is arranged near the slider block 31.

Next, the operation will be described. In the drive pulse generation circuit 52, under the control of the drive control circuit 51, as shown in FIG.
17A, a sawtooth wave drive pulse having a gentle rising portion and a rapid falling portion, or a rapid rising portion and a gentle falling portion as shown in FIG. 17B is generated. . The generated drive pulse is applied to the piezoelectric element 15, and the slider block 31 is driven in a predetermined direction.

The moving speed of the slider block 31 is detected by the speed sensor 55, and the driving speed is calculated in the moving body speed detecting circuit 56. The calculated drive speed is compared with the reference speed read from the reference speed storage circuit 57 in the comparison circuit 58. The comparison result is input to the friction force control circuit 59, the friction force adjustment data is determined based on the input comparison result, and the friction force adjustment voltage generation circuit 53 is input.

In the frictional force adjusting voltage generating circuit 53, the input frictional force adjusting data is controlled under the control of the drive control circuit 51.
The magnitude of the voltage applied to the piezoelectric element 35 for adjusting the frictional force is determined based on the parameter, and is applied to the piezoelectric element 35. The piezoelectric element 35 is displaced according to the applied voltage,
The urging force F by which the coupling portions 32a and 33a are brought into pressure contact with the drive shaft 16, that is, the frictional force is adjusted, and the optimal frictional force according to the load can be generated.

Further, when the drive control circuit 51 outputs a command signal for fixing the slider block to the drive shaft to the slider block fixing voltage generating circuit 60, the circuit 60 needs to fix the slider block to the drive shaft. A different voltage is output and applied to the piezoelectric element 39. The piezoelectric element 39 is displaced based on the applied voltage, the fork-shaped member 32 is pushed downward in FIG. 10, the drive shaft 16 is strongly pressed against the coupling portions 32a and 33a, and the slider block 31 is moved. Is fixed to the drive shaft 16.

In the actuator according to the present invention, the frictional force between the drive shaft and the slider block can be adjusted to an optimum value according to the load. However, even if the frictional force is adjusted, the slider block moves in a predetermined direction while sliding with the drive shaft, and therefore the frictional force between the drive shaft and the slider block periodically fluctuates in the driven state. Also, the drive speed of the slider block also fluctuates periodically, and if the fluctuation range of the drive speed exceeds a predetermined allowable value, smooth driving cannot be performed.

In such a movement mode, a frequency significantly lower than the frequency of the drive pulse of the piezoelectric element for driving the slider block, for example, the drive pulse frequency is 250.
In the case of 00 Hz, when the frictional force between the slider block and the drive shaft is periodically changed at a low frequency of about 10 Hz, for example, a sine wave shape is changed, the drive force between the drive shaft and the slider block is changed according to the load. It was found that the frictional force can be adjusted and the driving can be performed smoothly.

12 and 13 show a frictional force control circuit 59.
FIG. 7 is a diagram illustrating the operation of FIG. That is, when the frictional force between the slider block and the drive shaft is periodically changed, if the amplitude t1 of the fluctuation of the drive speed is less than or equal to the predetermined amplitude T as shown in FIG. It need not be changed periodically. However, the amplitude t2 of the fluctuation of the driving speed is shown in FIG.
When the amplitude exceeds the predetermined amplitude T as shown in (b) of (3), the frictional force is adjusted so as to reduce the amplitude of the fluctuation of the driving speed.

FIG. 13 is a diagram for explaining the flow of processing for adjusting the frictional force according to the amplitude of fluctuations in drive speed. First,
The frictional force between the slider block and the drive shaft is periodically changed (step P1). Next, it is judged whether or not the amplitude of the fluctuation of the driving speed exceeds the specified level (step P2), and if it does not exceed the specified level, the process is terminated. If it exceeds the specified level, the phase shift of the drive speed fluctuation and the phase shift of the frictional force fluctuation are judged (step P3). If the phase shift is 0 °, that is, if there is no phase shift. Adjusts the frictional force so as to increase the average frictional force (step P4). If the difference between the phase of the fluctuation of the driving speed and the phase of the fluctuation of the frictional force is 180 °, the frictional force is adjusted so as to reduce the average frictional force (step P5). As a result, the amplitude of fluctuations in drive speed can be reduced.

[0063]

As described above, according to the present invention, an electromechanical conversion element, a driving member fixedly coupled to the electromechanical conversion element and displaced together with the electromechanical conversion element, and a driven member frictionally coupled to the driving member. A drive device using an electromechanical conversion element configured by: a friction member that is fitted into the opening of the driven member and frictionally coupled to the drive member;
The elastic member is arranged in the fitting gap between the driven member and the friction member fitted in the opening of the driven member.

With this structure, a gap can be eliminated between the driven member and the friction member fitted in the opening, so that the driving energy received from the driving member is efficiently transmitted to the driven member, and the driving energy is The loss of can be eliminated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of constituent members of an actuator according to the present invention.

FIG. 2 is a perspective view showing an assembled state of the actuator shown in FIG.

FIG. 3 is a cross-sectional view showing the structure of a frictional coupling portion of the actuator shown in FIG.

FIG. 4 is a cross-sectional view showing another example of the configuration of the frictional coupling portion shown in FIG.

5 is a cross-sectional view showing another example of the configuration of the frictional coupling portion shown in FIG.

6 is a cross-sectional view showing another example of the configuration of the frictional coupling portion shown in FIG.

FIG. 7 is a diagram illustrating a state in which the optimum frictional force fluctuates according to the load.

FIG. 8 is a cross-sectional view showing a second example of the configuration of the frictional coupling portion.

FIG. 9 is a cross-sectional view showing a third example of the configuration of the frictional coupling portion.

FIG. 10 is a diagram showing a configuration for fixing a drive shaft to a friction coupling portion.

FIG. 11 is a block diagram of the control circuit of the actuator.

FIG. 12 is a diagram illustrating a change in drive speed.

FIG. 13 is a diagram illustrating a flow of a process of adjusting a frictional force according to an amplitude of a change in driving speed.

FIG. 14 is an exploded perspective view showing constituent members of a conventional actuator.

FIG. 15 is a perspective view showing an assembled state of a conventional actuator.

FIG. 16 is a cross-sectional view showing a structure of a frictional coupling portion of a conventional actuator.

FIG. 17 is a diagram illustrating a waveform of a drive pulse.

[Explanation of symbols]

10 Activator 11 frames 12 slider block 12a opening 13, 14 Support block 15 Piezoelectric element 16 drive shaft 18 pads 19 coil spring 20 leaf spring 23 leaf spring 24 Synthetic resin plate 31 slider block 32, 33 fork-shaped member 32a, 33a coupling part 34 Hinge part 35 Piezoelectric element 38 Arm member 39 Piezoelectric element 50 control circuit 51 Drive control circuit 52 Drive pulse generation circuit 53 Friction force adjustment voltage generation circuit 55 Speed sensor 56 Moving speed detection circuit 57 Reference speed memory circuit 58 Comparison circuit 59 Friction force control circuit 60 Slider block fixing voltage generation circuit

─────────────────────────────────────────────────── ─── Continued Front Page (72) Haruyuki Nakano, Inventor Haruyuki Nakano, 2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka, Osaka International Building Minolta Co., Ltd. (72) Inventor Fujita, Azuchi, Chuo-ku, Osaka-shi, Osaka 2-13-3 Machi Osaka International Building Minolta Co., Ltd. (72) Inventor Yoshitaka Sugimoto 2-3-3 Azuchicho Chuo-ku, Osaka City, Osaka Prefecture Osaka International Building Minolta Co., Ltd. (56) References Japanese Patent Laid-Open No. 8-149860 (JP, A) Japanese Patent Laid-Open No. 8-111991 (JP, A) Japanese Patent Laid-Open No. 3-15007 (JP, A) Japanese Patent Laid-Open No. 7-7973 (JP, A) Japanese Patent Laid-Open No. 8-168245 (JP , A) Actual development Sho 60-162997 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02N 2/00

Claims (3)

(57) [Claims] 1. An electromechanical conversion element, a drive member fixedly coupled to the electromechanical conversion element, and displaced together with the electromechanical conversion element, a driven member frictionally coupled to the drive member, and the driven member of the driven member. The electromechanical conversion element is provided with a friction member that fits in the opening and frictionally couples to the drive member, a drive pulse generation unit that applies expansion / contraction displacement to the electromechanical conversion element, and a drive control unit. A driving device using an electromechanical conversion element for driving a driving member by generating expansion and contraction displacement, and moving the driven member frictionally coupled to the driving member in a predetermined direction, which fits into an opening of the driven member. A driving device using an electromechanical conversion element, wherein an elastic member is arranged in a fitting gap between the friction member and the driven member. 2. The elastic member disposed in the fitting gap between the friction member fitted in the opening of the driven member and the driven member has a spring constant of the elastic member in the electromechanical conversion element displacement direction of k, When the frictional force between the driving member and the driven member is F and the displacement of the electromechanical conversion element is x, the spring constant k is an elasticity composed of a material having a value represented by k> F / 10x. It is a member, The drive device using the electromechanical conversion element of Claim 1 characterized by the above-mentioned. 3. The elastic member arranged in the fitting gap between the friction member fitted in the opening of the driven member and the driven member is urethane resin, silicon resin, vinyl resin, polyamideimide resin, And one or two selected from rubber
2. The material according to claim 1, which is composed of one or more kinds of materials.
A drive device using the electromechanical conversion element described.