JPH07244057A - Fine adjustment mechanism - Google Patents

Abstract

PURPOSE:To make large displacement quantity and vibration-resistant characteristics compatible with each other in a fine adjustment mechanism using a parallel spring. CONSTITUTION:In the fine adjustment mechanism having a parallel spring 10 and the actuator 4 brought into contact with one point on the parallel spring and applying load to the parallel spring to displace the parallel spring in a predetermined displacement direction, a mechanism applying pre-load to the parallel spring 10 in the direction opposite to the displacement direction through a buffer material 7 at the point set to the same axis with respect to the contact point of the actuator 4 and the parallel spring 10 and the displacement direction on the side opposite to the contact point is provided. Pref., pre-load is applied so that the parallel spring 10 becomes a self-supporting state or a state slightly inclined in the minus direction of the displacement direction in a zero displacement state wherein no displacement due to the actuator 4 is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine movement mechanism suitable for use in a scanning tunnel microscope and the like, and a fine movement scanning mechanism of a scanning tunnel microscope using the fine movement mechanism.

[0002]

2. Description of the Related Art There are various types of fine movement mechanisms used for scanning tunneling microscopes, and one of them is a parallel spring mechanism. FIG. 6 shows a conventional fine movement mechanism using a parallel spring.
Shown in. The parallel spring 30 is composed of two arms 32 extending in parallel to each other from a fixed portion 31 which is a base, and a connecting portion 33 connecting end portions of the two arms. Then, an actuator 34 such as a piezoelectric actuator fixed to the fixed portion is brought into contact with a point on the parallel spring 30 via a steel ball 35. When the actuator 34 is operated, the parallel spring moves the steel ball 35.
4, the hinge portions 36 formed by cutting out a part of the parallel spring are deformed as hinges, and the connecting portion 33 moves in parallel with the fixed portion. Figure 6
The position of the parallel spring after movement is indicated by a two-dot chain line in FIG. The advantages of the parallel spring are that it has excellent straightness of displacement, it is easy to expand the displacement of the actuator by lever magnification, and it is easy to install an interferometer or displacement meter for displacement position detection. .

[0003]

When a displacement mechanism is constituted by a parallel spring and an actuator, in order to ensure that the load point at which the actuator applies a force to the parallel spring is in constant contact, a preload (preload) in the load direction is applied. )is necessary. A method of utilizing the elasticity of the parallel spring itself can be considered as a method of applying a pressure. To do this, before moving the parallel spring by the actuator, contact the actuator so that the parallel spring is already pushed in the displacement direction (that is, the direction to be displaced by the actuator) beyond its equilibrium point. (In this case, a steel ball or the like may be inserted between the actuator and the parallel spring to bring about the point contact). However, this method has the following problems. That is, in the case of an integral notch type parallel spring having extremely high accuracy, if the hinge portion is subjected to excessive bending stress, it will enter the plastic deformation region, so there is a limit to the maximum bending angle. Therefore, in the above configuration in which the parallel springs already have an inclination of the applied pressure in the displacement direction at the point of zero displacement,
The range of angles that can be effectively used is limited, which is an obstacle to obtaining a large displacement amount.

If the arm is lengthened in order to obtain a larger displacement with the same angle change, the mechanical resonance point is lowered, and the arm becomes weak against disturbance vibration. As a countermeasure against this, it is possible to reduce the Q value by applying a dump and to utilize the effect of the deformation of the contact portion of the steel ball due to sufficient pressurization. The latter effect is as follows. That is, since the parallel spring is made of an elastic material, when a contact point with the steel ball is deformed by pressurization, the part behaves as one local spring. This local spring is harder than the original parallel spring. Since the parallel spring is driven via its local spring, the system as a whole (that is, the system including the local spring, the parallel spring, and its mass) becomes a hard spring, and the resonance point rises to the disturbance vibration. The effect of becoming stronger is born.

Although it is useful as a countermeasure against vibration to reduce the Q value by applying a dump as described above, when a rubber or gel-like substance is sandwiched between a fixing portion and a method of dumping, the spring itself is used. Since it is also an element, it hinders the movement of the parallel spring depending on the mounting position. In the method of applying the cushioning material to the hinge portion, which is the pivot of the parallel spring, the hinge, such as pitch, yaw, and rolling, is deformed other than the original deformation of the parallel spring, and the characteristics are deteriorated. It is an object of the present invention to provide a fine movement mechanism that makes it possible to increase the amount of displacement of the parallel spring and does not cause the above-mentioned problems.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a parallel spring,
In a fine movement mechanism having an actuator which is brought into contact with a point on the parallel spring and is displaced in a predetermined displacement direction by applying a load to the parallel spring, the actuator and the contact point of the parallel spring and the displacement direction are coaxial with each other. And a mechanism for applying a pressure to the parallel spring via a cushioning material in a direction opposite to the displacement direction at a point opposite to the contact point with the parallel spring member interposed therebetween. The present invention also provides a fine movement scanning mechanism of a scanning tunneling microscope using the fine movement mechanism as described above. In that case, the probe of the scanning tunneling microscope or the sample stage may be fixed to the parallel spring.

[0007]

According to the above construction, since the pressure is applied through the cushioning material, the damping effect of the cushioning material can suppress the resonance due to the disturbance. Further, there is also an effect of the deformation of the contact portion of the steel ball due to the above-mentioned pressurization, and the vibration resistance characteristic of the parallel spring can be improved. The cushioning material may be rubber or a gel-like substance, and since it acts as both a damper and a pressurizing spring, it has a simple structure. Since the pressure applied to the parallel spring is applied to a point on the same axis as the load point by the actuator with the parallel spring interposed therebetween in the opposite direction of the load direction, no moment force is applied to the parallel spring. Therefore, unnecessary deformation other than the original deformation of the parallel spring does not occur and displacement is not hindered. Also, since the parallel spring applies pressure in the direction opposite to the direction in which it should be displaced by the actuator (displacement direction, that is, load direction), the parallel spring is bent in the same direction as the self-supporting state or in the minus direction of the actuator displacement direction. The state can be set to the zero point of the displacement, and the range in which the parallel spring can be displaced within the elastic limit of the hinge portion can be effectively used.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a fine movement mechanism of a first embodiment of the present invention. A parallel spring 10 is composed of two arms 2 extending in parallel to each other from a fixed portion 1 which is a base or a substrate, and a moving portion 3 which connects end portions of the two arms. The laminated piezoelectric element 4, which is an actuator for displacing the parallel spring 10, has one end bonded to the fixed portion 1 and the other end bonded with a steel ball 5 having a diameter of 2 mm. The other end of the steel ball is in point contact with the moving portion 3 of the parallel spring 10. On the opposite side of the piezoelectric element 4 with respect to the parallel spring, one end of a cushioning material 7 made of rubber or gel-like material is bonded to the fixed portion 1. A metal plate 9 having a steel ball 8 bonded to the center thereof is bonded to the other end of the cushioning material 7. The cushioning member 7 is in a compressed state in order to apply a pressure to the parallel spring 10 in the left direction in FIG. In this embodiment, when the piezoelectric element is not operating (zero displacement state), the parallel spring is in a self-supporting state (that is, a posture taken in a natural state in which no external force is applied).
It is designed to be. FIG. 1 shows this zero displacement state. In FIG. 1, the fixed portion to which the piezoelectric element 4 and the cushioning material 7 are attached is shown integrally with the lower fixed portion which is the base of the parallel spring, but it does not necessarily have to be integrated. Further, the cushioning material is not limited to rubber or gel-like material, and may be any material having incomplete elasticity that can perform both the functions of pressurization and damper.

In the mechanism as described above, when a voltage is applied to the piezoelectric element 4, the piezoelectric element 4 causes a mechanical strain and pushes the parallel spring 10 to the right in FIG. 1 via the steel ball 5. As a result, the parallel spring is deformed by using the four hinge portions 6 formed by cutting out a part thereof as hinges, and the moving portion 3 moves in parallel with the fixed portion. This moving portion 3 is a portion that is finely moved by the fine movement mechanism, and by adjusting the voltage applied to the piezoelectric element 4, a desired amount of fine displacement is generated in the horizontal direction in the figure. In this fine movement mechanism, the cushioning material 7 plays the role of a damper even if the fixed portion 1 vibrates due to disturbance,
Vibration is unlikely to occur in the parallel spring 10.

FIG. 2 shows a fine movement mechanism of the second embodiment of the present invention. The mechanism of the present embodiment is almost the same as the mechanism of FIG. 1, and corresponding parts are designated by the same reference numerals and description thereof is omitted. The difference from the embodiment of FIG. 1 is that in the zero displacement state in which the displacement by the piezoelectric element 4 has not occurred, the parallel spring 10 is bent in advance in the negative direction of the displacement direction by the piezoelectric element 4 by the applied pressure, and the parallel spring is hinged. The point is that the range of displacement within the elastic limit of can be effectively used. FIG. 2 shows this zero displacement state. In this way, theoretically, a maximum displacement range from the left elastic limit to the right elastic limit of the parallel spring can be taken, so that a large displacement amount can be secured.

FIG. 3 shows a fine movement mechanism of a third embodiment of the present invention. Also in this embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, the point where the force from the piezoelectric element acts is located at the center of the arm of the parallel spring, so that the displacement amount of the piezoelectric element is expanded with a double lever ratio. That is, in this mechanism, the displacement amount of the moving portion 3 is doubled with respect to the displacement amount of the piezoelectric element 4. Any of the fine movement mechanisms of the above embodiments can be suitably used as the scanning mechanism of the scanning tunneling microscope. The scanning mechanism is for relatively moving the probe of the scanning tunneling microscope and the stage on which the object is placed.

FIG. 4 shows an example in which the fine movement mechanism shown in FIG. 1 is used as a moving mechanism of a probe of a scanning tunneling microscope. A probe 20 is fixed on the moving portion 3 via a vertical direction fine movement element 22 which performs fine movement in the vertical direction in the figure. Reference numeral 21 is a holder of the probe. With this structure, scanning is performed by slightly moving the probe in the horizontal direction in the figure.

FIG. 5 shows an example in which the fine movement mechanism shown in FIG. 1 is also used as a stage movement mechanism of a scanning tunneling microscope. A stage 23 is fixed on the moving unit 3 and the stage is moved in the horizontal direction in the figure to perform scanning.

[0014]

According to the present invention, since the pressure is applied through the cushioning material, the damping effect of the cushioning material can suppress the resonance caused by the disturbance. Further, there is also an effect of the deformation of the contact portion of the steel ball due to the above-mentioned pressurization, and the vibration resistance characteristic of the parallel spring can be improved. The cushioning material may be rubber or a gel-like substance, and since it acts as both a damper and a pressurizing spring, it has a simple structure. Further, since the pressure applied to the parallel spring is applied to points coaxial with the load point of the actuator with the parallel spring interposed therebetween in the opposite direction to the load direction, no moment force is applied to the parallel spring. Therefore, unnecessary deformation other than the original deformation of the parallel spring does not occur,
It does not hinder displacement. Further, since the parallel spring applies pressure in the direction opposite to the direction in which it should be displaced by the actuator, the state where the parallel spring is the same as the self-standing state or bent in the minus direction of the displacement direction of the actuator is taken as the zero point of the displacement. Therefore, the range in which the parallel spring can be displaced within the elastic limit of the hinge portion can be effectively used.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a fine movement mechanism that is a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing a fine movement mechanism that is a second embodiment of the present invention.

FIG. 3 is a diagram schematically showing a fine movement mechanism that is a third embodiment of the present invention.

FIG. 4 is a diagram showing an embodiment in which the fine movement mechanism shown in FIG. 1 is used as a probe moving mechanism of a scanning tunneling microscope.

5 is a diagram showing an example in which the fine movement mechanism shown in FIG. 1 is used as a sample stage moving mechanism of a scanning tunneling microscope.

FIG. 6 is a diagram showing a conventional example of a fine movement mechanism using a parallel spring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed part 2 Arm of parallel spring 3 Moving part 4 Laminated piezoelectric element 5, 8 Steel ball 6 Hinge part 7 Buffer material 9 Metal plate 10 Parallel spring 20 Probe 23 Stage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display H02N 2/00 B

Claims (7)

[Claims] 1. A fine movement mechanism comprising: a parallel spring; and an actuator that comes into contact with a point on the parallel spring, the actuator displacing a load on the parallel spring in a predetermined displacement direction. At a point that is coaxial with the contact point in the displacement direction and is opposite to the contact point with the parallel spring member interposed, the parallel spring is pressed in the opposite direction to the displacement direction via a cushioning material. A fine movement mechanism having a mechanism for applying a force. 2. A steel ball bonded to the actuator, wherein the actuator applies point load to the parallel spring through the steel ball to make point contact with the parallel spring.
Fine movement mechanism described. 3. A cushioning member attached to a fixing member fixed relative to a fixing portion to which the parallel spring is fixed, and a cushioning member in the mechanism for applying pressure through the cushioning member. 2. The fine movement mechanism according to claim 1, further comprising a member that makes point contact with the parallel spring attached to the buffer member on a side opposite to the fixed member side. 4. The fine movement mechanism according to claim 1, wherein the pressurizing force is applied by utilizing elasticity of the cushioning material itself. 5. The pressurizing force is in the same state as when the parallel spring stands alone by itself in a zero displacement state in which no displacement is caused by the actuator, or is slightly inclined in the minus direction of the displacement direction. The fine movement mechanism according to claim 1, wherein the fine movement mechanism is hung so as to be in a state. 6. A parallel spring including two arms extending substantially in parallel from a fixed part and a moving part connecting the ends of the two arms, and an actuator for contacting a point on the parallel spring,
An actuator in a fine movement scanning mechanism of a scanning tunnel microscope having an actuator that applies a load to a parallel spring to deform it to cause a minute displacement of the moving part in a predetermined direction, and a probe fixed to the moving part of the parallel spring. At a point on the opposite side of the contact point of the parallel spring with respect to the contact point of the parallel spring and the displacement direction, and on the opposite side of the contact point with the parallel spring member sandwiched, the parallel spring is provided with a cushioning material in a direction opposite to the displacement direction. A fine movement scanning mechanism characterized by having a mechanism for applying a pressure through the. 7. A parallel spring including two arms extending substantially in parallel from a fixed part and a moving part connecting the ends of the two arms, and an actuator for contacting a point on the parallel spring,
An actuator in a fine movement scanning mechanism of a scanning tunneling microscope having an actuator that applies a load to a parallel spring to deform it to cause a minute displacement of the moving part in a predetermined direction, and a sample stage fixed to the moving part of the parallel spring. At a point on the opposite side of the contact point of the parallel spring with respect to the contact point of the parallel spring and the displacement direction, and on the opposite side of the contact point with the parallel spring member sandwiched, the parallel spring is provided with a cushioning material in a direction opposite to the displacement direction. A fine movement scanning mechanism characterized by having a mechanism for applying a pressure through the.