JPH0522475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to a moving member that moves linearly.

[Technical background of the invention and its problems]

Conventionally, linearly moving one-dimensional actuators that enable particularly minute position control include those that use the longitudinal strain effect of piezoelectric elements. An example is shown in FIG.

The linear movement is given by applying a DC voltage to the laminated piezoelectric unit 1, which is composed of laminated piezoelectric elements, and the direction of movement is given by the laminated piezoelectric unit 1.
It can be controlled by the polarity of the voltage applied to the
The amount of movement at that time is proportional to the voltage applied to the laminated piezoelectric unit 1. For example, when using PZT with a thickness of 0.5 mm,
0.25μ in a laminated piezoelectric unit made of 400 layers
m/V, and even if 1000V is applied, the amount of movement is
It becomes only 250μm. In order to extend the amount of movement, laminated piezoelectric units 2 and 3 configured similarly to the laminated piezoelectric unit 1 are provided, and a voltage is applied alternately to the laminated piezoelectric units 2 and 3 according to the expansion and contraction of the laminated piezoelectric unit 1, and the housing 5 and the slide rod 4 is moved.

In this way, an actuator that uses the longitudinal strain effect of a piezoelectric element has a displacement sensitivity (μ
m/V) is low, the driving power supply is 1000V or more.
Since it requires a high voltage power supply of 2000V, which is not practical, there has been a desire for an actuator with high displacement sensitivity that can be driven with a low voltage power supply that is easy to control voltage.

[Purpose of the invention]

An object of the present invention is to provide a moving member that can obtain a large amount of displacement using a low voltage power source and can move linearly.

[Summary of the invention]

This invention is characterized by arranging a plurality of bimorph-shaped piezoelectric elements in parallel, increasing the driving force times the number of piezoelectric elements arranged in parallel, and realizing a moving member that moves linearly and can obtain large displacements with low voltage. did.

〔Effect of the invention〕

According to this invention, since a plurality of bimorph-shaped piezoelectric elements are arranged side by side, it is possible to obtain a desired driving force and displacement amount.

[Embodiments of the invention]

FIG. 2a shows the basic configuration of a one-dimensional actuator using a bimorph-shaped piezoelectric element. It is known that the piezoelectric element formed in the bimorph type used in this invention can obtain a large displacement with a low voltage. For example, if the thickness is 9 μm and the length is 2 cm.
The PVαF (polyvinylidene fluoride) bimorph element (polymer piezoelectric element) has a free end displacement of 1 mm at an applied voltage of 10 V, a thickness of 0.2 mm, and a length of 23 mm.
PZT bimorph element (ceramic piezoelectric element)
When the applied voltage is 50V, the displacement of the free end is as much as 150μm. However, when used alone, the driving force is weak, but this invention solves this problem.

The actuator in this embodiment basically has a plurality of bimorph-shaped piezoelectric elements (abbreviated as bimorph in the following explanation) 7a fixed to a slider 6a.
The free end of a is adapted to fit into a non-slip groove provided in the slider 6b. Similarly, a plurality of bimorphs 7b are fixed to the slider 6b, and the free end of the bimorph 7b is attached to the slider 6b.
It is designed to fit into the anti-slip groove provided in part a.

For the above configuration, each bimorph operates as follows.

FIG. 3 will be used to explain this operation. FIG. 3 schematically shows a state in which a variable power source 32 whose output voltage is variable is connected to the bimorph 31 . The bimorph 31 consists of a metal 33 such as stainless steel and a piezoelectric element 34.

As is well known, the piezoelectric element 34 is polarized, and the direction in which the bimorph deforms is determined by the direction of this polarization (indicated by arrow 30) and the direction of the applied electric field (direction of potential difference).

When the potentials of the metal 33 and the piezoelectric element 34 are equal and no electric field is generated, the bimorph 31 is not displaced as shown in FIG.

Next, for the polarization shown in FIG. 3, as shown in FIG. 4a, for example, the metal 33 side is set to a positive potential.
When the piezoelectric element 34 side is set to a negative potential and an electric field is generated from the piezoelectric element 34 toward the metal 33, the bimorph 31 is displaced in the direction shown by the arrow 35. In this embodiment, the manner in which a potential is applied to generate this electric field is referred to as a state in which a negative voltage is applied.
At this time, the piezoelectric element 34 is contracted. or,
The amount of displacement described above is proportional to the absolute value of the applied voltage.

On the other hand, as shown in FIG. 4b, for example, if the piezoelectric element 34 side is set to a negative potential and the metal 33 side is set to a positive potential, and an electric field is generated from the metal 33 to the piezoelectric element 34, the bimorph 31 will arrow 3
A displacement occurs as shown in 6.

However, the bimorph 31 is not limited to the type made of metal and a piezoelectric element as described above, but may also be a type made of two piezoelectric elements bonded together as is well known. At this time, there are two types of bonding methods: a series type and a parallel type. In the former case, the polarization directions of the piezoelectric elements are opposite to each other. Such bimorphs are connected in series between positive and negative potentials. In the latter case, the polarization directions of the piezoelectric elements are directed in the same direction. In such a bimorph, both sides of the bimorph are set at the same potential, and their junctions are set at opposite polarities. Therefore, they will be connected in parallel.

Assuming the above operation, if a positive voltage is applied to all the bimorphs on the slider 6a side in the actuator shown in FIG. Displaced to the right when viewed from.

Therefore, the slider 6a tries to move the slider 6b toward the arrow 37, and conversely, the slider 6b tries to move the slider 6a toward the arrow 38 in opposite directions.

Therefore, one of the sliders 6a, 6b
If it is fixed to a fixed plate (not shown), when the slider 6a is fixed, the slider 6b can be moved to the left as shown in the figure, and when the slider 6b is fixed, the slider 6a can be moved to the right.

Here, assuming that a PVαF polymer piezoelectric element is used as the bimorph element and its sensitivity is such that the displacement of the free end is 1 mm for an applied voltage of 10 V, the slider 6a is fixed and the bimorphs 7a and 7b are applied with +10 V.
When a voltage of 1 mm is applied, the slider 6b moves 1 mm to the left. Next, if the slider 6b is fixed and the applied voltage is -10V, the free ends of the bimorphs 7a and 7b will be displaced by the same amount in the opposite direction to that shown in FIG. 2b, so the slider 6a will move 2 mm to the left. .

In this way, the slider 6 can be adjusted depending on the polarity of the voltage applied to the bimorphs 7a, 7b and the selection of the sliders 6a, 6b to be fixed to the fixed plate at that time.
a, 6b can be moved alternately to the left or right. Furthermore, if the applied voltage is minutely controlled, the amount of movement can also be minutely controlled.

Next, a one-dimensional actuator according to an embodiment of the present invention will be explained with reference to FIG. The figure is a perspective view thereof.

The sliders 6a and 6b are sandwiched from both sides by a guide plate 8, and are movable along guide grooves provided in the guide plate 8. The support rod 10 is for supporting the two upper and lower guide plates 8 at a constant interval. Bimorph-shaped piezoelectric elements 9a and 9b with both ends fixed are installed on the upper surfaces of the sliders 6a and 6b, respectively.

For example, as shown in FIG. 9, the bimorphs 9a and 9b are fixed at both ends. The configurations of the bimorphs 9a and 9b are the same as the bimorphs 6a and 6b described above.

Therefore, if the bimorphs 9a and 9b are horizontal when no voltage is applied, as shown in FIG. 7, for example, when a negative voltage is applied, the piezoelectric element side becomes convex.

Here, when no voltage is applied, it is in a convex state as shown in FIG. 9. However, the bimorphs 9a and 9b are not in contact with the guide plate 8. On the other hand, when a potential is applied to the bimorph 9a as shown in FIG. 8, the bimorph 9a becomes convex toward the piezoelectric element as shown in FIG. 10, and the bimorph 9a and the guide plate 8
is in contact. This is shown in FIG. In this state, the bimorph 9a and the guide plate 8 are in a fixed state.

Therefore, a potential is selectively applied to the bimorph 9a or 9b. Sliders 6a and 6b are selectively fixed. Here, it is natural that the bimorphs may be provided not only at the upper ends of the sliders 6a and 6b but also at the lower ends.

Based on the above operation, driving of the actuator shown in FIG. 5 will be explained.

It is assumed that the voltages supplied to the bimorphs 7a and 7b are the same. The relationship between bimorphs 7a and 7b is
It is necessary to pay attention to the fact that it is shown in FIG. 2a. Such bimorph 7a, 7
As shown in FIG. 6a, a monotonically increasing voltage from 0 to +V ₀ volts is applied to voltage 0 (this period is referred to as the first period).

Next, a monotonically decreasing voltage is applied from +V ₀ to -V ₀ volts (this period is referred to as the second period).
Furthermore, a voltage that monotonically increases from -V ₀ to 0 volts is supplied (this period is referred to as a third period).

Correspondingly, a voltage is selectively applied to the bimorphs 9a and 9b provided at the upper ends of the sliders 6a and 6b, as shown in FIGS. 6b and 6c. That is, for the first and third periods, voltage is supplied to the bimorph 9a. For the second period, a voltage is supplied to the bimorph 9b.

By supplying voltage in this way, the fifth
The actuator shown in the figure operates as follows. First, in the first period, bimorph 7
When the above-mentioned voltage is supplied to a and 7b,
The individual bimorphs 7a, 7b operate as shown in FIG. 4b. At the same time, when voltage is supplied to bimorph 9a, slider 6a is locked.
Therefore, the slider 6a is in a fixed state (fixed to the entire device), and the slider 6b is
moves to the left in FIG. This is done for the entire first period.

Next, in the second period, bimorph 7a,
When 7b is supplied with a voltage as described above, the individual bimorphs 7a, 7b will have voltages ranging from ±V ₀ to 0 volts, as shown in FIG. 4b, and from 0 to −V ₀
Up to the bolt, the operation is as shown in Figure 4a. However, in the former case, bimorph 7a,
The bending direction of the bimorphs 7b changes in a direction in which it becomes smaller (in a direction in which the curvature becomes larger), and in the latter case, the bending direction in the bimorphs 7a and 7b changes in a direction in which it becomes larger (in a direction in which the curvature becomes smaller). At this time, as shown in FIG. 6c, for the bimorph 9b,
When voltage is supplied, the bimorph 9b comes into contact with the guide plate 8 (see FIG. 10).

Therefore, the slider 6b is locked to the guide plate 8, and is fixed to the entire device. Bimorphs 7a and 7b, as mentioned above,
It moves in the direction of less bending, that is, it tries to return to its original state. However, in the second period, since the slider 6b is in a fixed state (contrary to the first period), the slider 6a is pulled by the slider 6b as shown in FIG. Move to.

When a negative voltage is supplied to the bimorphs 7a, 7b, the bimorphs 7a, 7b will move as shown in FIG.
Displaced as shown in .

Slider 6b is still locked, forcing slider 6a to move. Therefore, with the slider 6b as a fixed end, the slider 6a moves to the left as shown by the dotted line in FIG.

Next, in the third period, the slider 6b moves to the left in the same manner, and the sliders 6a and 6b move to the left throughout the entire period.

In order to change the moving direction of the sliders 6a, 6b, it is sufficient to change the locked state of the sliders 6a, 6b, that is, the voltage application timing.

In the above configuration and operation, the object conveyed by such an actuator is the side surface (outer surface that does not face each other) of the sliders 6a, 6b.
It may also be supported. Alternatively, a guide member may be provided along the guide groove separately from the sliders 6a, 6b, and this guide member may be structured so that the sliders 6a, 6b push it, and the object to be conveyed may be supported at the tip of the guide member. .

[Other embodiments of the invention]

In the embodiment shown in FIG. 5, a guide plate 8 is provided to limit the moving direction of the sliders 6a and 6b, and this is done by a guide groove provided in the guide plate 8, but other guiding methods are also available. The same effect can be obtained even if it is twisted.

Similarly, in order to fix the sliders 6a and 6b to the guide plate 8, a bimorph 9 is fixed at both ends.
A, 9b were provided and this was done by deforming the bimorphs 9a, 9b, but the same effect can be achieved by using other fixing methods, such as an electrostatic chuck using electrostatic force, a magnetic one, or one by deforming an electrostrictive element. Effects can be obtained. Further, in this embodiment, the bimorphs 9a and 9b are already in a convex state when no voltage is applied, but bimorphs that are horizontal when no voltage is applied may be used.

Furthermore, in order to fix the sliders 6a, 6b to the guide plate 8, one bimorph-shaped piezoelectric element 9a, 9b was provided for each of the sliders 6a, 6b, but the bimorph 7 for movement
If the driving force increases due to an increase in the number of plates a and 7b installed, a large number of bimorphs for locking can be installed above and below, in series, in parallel, etc. to increase the fixing force to the guide plate 8. It is also preferable to aim.

Depending on the required driving force, the driving force can be increased by increasing the number of piezoelectric elements installed.

The basic unit is the slider 6a shown in FIG. 2 and the bimorph 7a fixed thereto, and the two are combined as an actuator unit as shown in FIG. 2, and this actuator unit is used as a standard. It goes without saying that the driving force can also be increased by connecting the actuator units in parallel, in series, or in series and parallel, depending on the application.

Furthermore, in the above embodiment, one end of the bimorph is fixed to one slider, and the other end is supported by another slider, but this mode of support is not limited to this embodiment. do not have.

That is, the slider may be provided with a concave portion as shown in FIG. 13, or the slider may be provided with a convex portion (protrusion) as shown in FIG. 14. In other words, the key point of this support is that the bimorph is free to move in a direction approximately perpendicular to the direction in which the bimorph is displaced (i.e., in the direction connecting the ends that contact the slider mentioned above), and that the bimorph is free to move in the direction in which the bimorph changes. is to regulate the movement of the bimorph. This is because when a predetermined potential is applied to the bimorph and the bimorph is displaced, the support point of the bimorph by the slider changes, so conversely, a degree of freedom is given so that this support point can be changed. That is an important point. However, the protrusion shown in FIG. 14 can also be regarded as a groove added to the side surface of the bimorph.

Furthermore, the bimorph referred to in this application does not have to be a structure in which a piezoelectric element and a metal are stacked as in the embodiment, but may be a structure in which two piezoelectric elements are stacked. Here, as shown in FIG. 15, instead of the entire surface of the metal 51, only a portion thereof may be overlapped with the piezoelectric element 53.

In other words, the bimorph referred to here is, as shown in a schematic diagram like FIG.
In the cross section, it is sufficient that there is only a region having a structure in which the piezoelectric element and the metal are overlapped.

A modification of the configuration shown in FIG. 2 is shown.

As shown in FIG. 16, sliders 60a, 60b
One end of the bimorph is fixed and facing the other. The other end is a free end. This free end is connected to the grooves 62a and 62 provided in the sliders 60a and 60b.
It is set to fit into b. slider 60
a and 60b have substantially the same structure including bimorphs 64a and 64b.

In such a configuration, driving is performed as follows. As a first method, there is a driving method in which a slider to which a bimorph to which a voltage is applied is fixed is fixed to a housing (not shown).

According to this method, when a voltage is applied to the bimorph 64a, as shown in FIG.
The tip of the bimorph 64a is displaced, and the slider 6
Press 0b. This slider 60b is free to move (not fixed) and moves in the direction indicated by the arrow. The bimorph 64b does not perform any particular operation.

Next, when the fixation of the sliders 60a and 60b is reversed and the voltages applied to the bimorphs 64a and 64b are also reversed, the slider 60a moves.

As a second method, sliders 60a, 60b
The fixing timing may be the same as above, and opposite potentials may be simultaneously applied to the bimorphs 64a and 64b, and their polarities may be reversed at predetermined intervals.

In other words, the bimorph referred to here is, as shown in a schematic diagram like FIG.
In the cross section, it is sufficient that there is only a region having a structure in which the piezoelectric element and the metal are overlapped. Furthermore, in the above embodiments, the actuator was formed by combining the sliders 6a and 6b of the same structure, but the actuator is not necessarily limited to this, and as shown in FIG.
The bimorphs belonging to a (the fixed state indicated by a black circle in the figure) may be made consecutive.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional actuator using laminated piezoelectric elements, and FIG. 2 is a basic configuration diagram of an actuator that is an embodiment of the present invention.
3 and 4 are explanatory diagrams of driving the components of the actuator shown in FIG. 2, FIG. 5 is a block diagram of a preferred embodiment, and FIG. 6 is a drive diagram of the device shown in FIG. 5. FIGS. 7 to 12 are schematic diagrams for explaining the operation of the components of the device shown in FIG. 6, and FIGS. 13 to 18 are diagrams showing modified examples. be. 6a, 6b...Slider, 7a, 7b...Bimorph.

Claims (1)

[Claims] 1. A first member, a second member provided opposite to the first member, and a plurality of members provided in parallel between the first and second members. The first group of bimorphs consists of a bimorph whose one end is located in a direction substantially perpendicular to the direction of the potential difference. The structure is such that the bimorphs are fixed to the first member and the other end is supported by the second member, and one end of the bimorphs of the second group among the bimorphs is fixed to the second member. , the other end is supported by the first member, selectively fixing one of the first and second members, and supporting the first or second group of bimorphs. A moving member characterized by comprising: control means for moving the other member by selectively applying a potential. 2 Claims characterized in that the structure in which the first or second member supports one end of the bimorph is configured to transmit displacement of one end of the bimorph to the first or second member. The moving member according to item 1. 3. The supporting structure is a groove formed on opposing side surfaces of the first or second member, and the supporting structure is a groove that allows the bimorph and the first or second member to move along the displacement direction of one end of the bimorph. The moving member according to claim 2, wherein the moving member is in contact with each other. 4. The supporting structure is a protrusion formed on opposing side surfaces of the first or second member, and the bimorph and the protrusion are in contact with each other along the displacement direction of one end of the bimorph. A moving member according to claim 2. 5. The method according to claim 1, characterized in that a fixing means is provided that is selectively fixed to the side surfaces of the first and second members that do not face each other and that face the reference member. moving parts. 6. The movable member according to claim 5, wherein the fixing means is constituted by a bimorph whose both ends are fixed to the first or second member.