JPH02111273A - Drive for piezo-actuator - Google Patents

Abstract

PURPOSE:To position a piezo-element with high accuracy by an open loop by correcting the non-linearity of the piezo-element 1 by a piezo-element position- voltage-value conversion means and avoiding the hysteresis properties of the piezo-element 1 by bringing voltage applied to the piezo-element to zero volt once. CONSTITUTION:A target position input by a keyboard 6 is transmitted over a central processing section 5, and the current location of a piezo-actuator and the target position are compared. When the target position is larger than the current location of the piezo-actuator, the central processing section 5 sets the target position to a piezo-position-voltage table (ROM) 4. The target position is converted into a voltage value by the piezo-position-voltage table (ROM) 4, output to a D/A converter 3, converted by the converter 3, amplified by an amplifier 2 for voltage, and applied to a piezo-element 1. When the target position is smaller than the current location of the piezo-actuator, on the other hand, the central processing section 5 outputs zero to the piezo-position-voltage table (ROM) 4 once, and voltage applied to the piezo-element 1 is brought to zero volt once. The target position is output to the piezo-position-voltage table (ROM) 4 again.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a drive device for a vinyl actuator that moves a table tJ[K, such as a precision positioning table, which needs to perform highly accurate positioning with a small stroke.

2. Description of the Related Art Piezo actuators are used as drive sources for tables that require submicron positioning accuracy, such as semiconductor devices. The drive device for this piezo actuator is provided with a position measuring means in parallel with the actuator, and this position information is fed back to achieve high accuracy.

An example of the piezo actuator drive device described above will be described below with reference to the drawings.

FIG. 4 shows an example of a table using a conventional piezo actuator drive device. In Figure 4, 41
42 is a piezo element, 42 is a table position measuring means, 43 is a table drive section, 44 is a table base, 46 is a piezo element drive section, 46 is a table position feedback means, 47
is table target position setting means.

The operation of the piezo actuator drive table and drive device configured as above will be described below.

First, the table target position setting means 47 sets the target position of Tefle. The table position feedback means 46 compares the table target position set by the table target position setting means 47 with the table position measurement means 42.
A signal proportional to the difference between the table current positions measured in is sent to the piezo element drive unit 46. The piezo element driving section 45 increases or decreases the voltage applied to the piezo element 41 in a direction in which the difference from the target position becomes zero based on the signal sent from the table position feed bank means 46.

As a result, the Viezo element 41 expands and contracts, and the table base 44
The table drive section 43 is moved relative to the table drive section 43, and the amount of movement of the table drive section 43 is measured by the table position measuring means 42. Through a series of closed loops that repeat the above operations, the tapered comb is positioned with high precision with respect to the target position.

Problems to be Solved by the Invention However, in the above configuration, the configuration of the table binding is complicated and it is difficult to make the table smaller. Moreover, the positioning accuracy of the tape binding is determined by the accuracy of the position measuring means. Another problem is that the positioning speed of the table is determined by the response speed of the position measuring means, and thus is influenced by the characteristics of the position measuring means.

In view of the above-mentioned problems, the present invention provides a piezo actuator drive device that can perform high-viscosity positioning without using a position measuring means.

Means for Solving the Problems In order to solve the above problems, the vinyl actuator unique drive device of the present invention includes piezo element, piezo actuator target position setting means, and converts the set target position into a piezo voltage value. piezo element position-voltage value conversion means; piezo actuator target position reduction detection means for detecting that the target position has decreased from the current position; The device is equipped with a means for setting an element applied voltage of zero volts and a piezo element voltage applying means for applying a voltage to the piezo element.

According to the present invention, the target position set by the piezo actuator target position setting means is converted into a voltage value to be applied to the piezo element by the piezo element position-voltage value conversion means, and the piezo element voltage is adjusted based on this voltage value. A voltage is applied to the piezo element by the application means, so that the piezo element is positioned at a set target position. On the other hand, the piezo actuator target position decrease detection means always stores the current position, that is, the voltage value, and determines whether the target position set by the piezo actuator target position setting means has decreased from the current position. are doing. If the target position is lower than the current position, a signal is sent to the piezo element applied voltage zero volt setting means, and the piezo element applied voltage zero volt setting means immediately sets the applied voltage of the piezo element 1 to zero volts. . Thereafter, the piezo element is positioned at the target position by applying a predetermined voltage to the piezo element using the piezo element voltage applying means.

Here, the nonlinearity of the displacement amount of the piezo element 1 with respect to the voltage is corrected by the piezo element position-voltage value conversion means,
If the set voltage decreases, the hysteresis of the piezo element 1 can be avoided by reducing the voltage applied to the piezo element to zero volts. This makes it possible to achieve high-precision positioning of piezo elements.

Embodiment Hereinafter, a piezo actuator drive device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a vinyl actuator unique drive device according to one embodiment. In FIG. 1, 1 is a piezo element;
2 is a mixed pressure amplifier, 3 is a digital-to-analog converter,
4 is a piezo position/voltage tape/l/ROM, 6 is a central processing unit, and 6 is a keyboard for inputting a piezo actuator target position.

The operation of the piezo actuator drive device configured as described above will be described below with reference to FIGS. 1 to 3.

First, the target position input using the piezo actuator target position input keyboard 6 is sent to the central processing section 5, where the current piezo actuator position and the target position are compared. If the target position is larger, the central processing unit 5 sets the target position in the piezo position-voltage tape)v(ROM)4. Piezo position - voltage tape) v (R
OM) 4 converts the target position into a voltage value according to the characteristics shown in FIG. 2, and outputs it to the digital-to-analog converter 3. Here, the voltage value is converted to an analog voltage value, further amplified by voltage amplifier 2, and applied to piezo element 1. On the other hand, if the target position is smaller than the current position, the central processing unit 5 temporarily returns the piezo position to the voltage tape.
v (ROM) Outputs zero to 4, - degree viezo element 1
Set the voltage applied to zero (/L/ ). After that, change the target position again to piezo position - voltage tape/l/(ROM)
Output to 4.

Here, the characteristics of the piezo element 1 will be explained using FIG. 3. FIG. 3 shows the amount of displacement when voltage is applied to the piezo element. In FIG. 3, piezo element 1
This shows that the amount of displacement when the voltage is gradually increased from zero volts and the amount of displacement when the voltage is decreased from a certain point do not show the same value. This is the hysteresis property of the piezo element 1. Furthermore, the displacement position relative to the piezo voltage does not change linearly (nonlinearity).

Therefore, in the present invention, the former hysteresis is solved by setting the -degree voltage to zero volts when setting the voltage to a lower value than the current value, and the latter nonlinearity is solved by the characteristic shown in Figure 2. Piezo position-voltage tape with RO
M) It is solved by having 4.

Alternatively, the piezo position/voltage tape register 4 may be constructed from a RAM, and the central processing section 6 may write the characteristics shown in FIG. 2 at an appropriate time and use it. Regardless of whether the piezo position-voltage table is stored in ROM or RAM, if a position value is set as an address, the voltage value will be output as data.

As described above, according to this embodiment, the keyboard 6 is used as the vinyl actuator unique target position setting means, the piezo position-voltage tape/v (ROM) 4 is used as the piezo element position-voltage value conversion means, and the piezo actuator The target position decrease detection means and the piezo element applied voltage zero volt setting means are realized by software in the central processing section 6, and the digital-to-analog converter 3 and the voltage amplifier 2 are used as the piezo element voltage application means.

With these (4t7 configurations), the hardware configuration is simplified, and the variations between piezo elements can be fixed in the piezo position-voltage table 4 (ROM or RAM) with corresponding characteristics. , it has the advantage of having a high degree of freedom in selecting the piezo element.Also, since it is an open-loop positioning control, there is no vibration while stationary, and the positioning speed is determined only by the expansion and contraction speed of the piezo element. It is.

Effects of the Invention As described above, the present invention provides piezo element and piezo actuator target position setting means, piezo element position-voltage value conversion means for converting the target position set as described above into a piezo voltage value, and Piezo actuator target position decrease detection means for detecting that the target position has decreased from the target position, piezo element applied voltage zero volt setting means for temporarily reducing the applied voltage to the piezo element to zero volts when the target position decreases, and applying voltage to the piezo element. By providing a piezo element voltage applying means, high-speed, high-precision positioning can be achieved with a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a piezo actuator drive device according to an embodiment of the present invention, Fig. 2 is a graph showing the contents of the piezo position-voltage table, and Fig. 3 is a general voltage-displacement characteristic of a piezo element. FIG. 4 is a block diagram of a table using a conventional piezo actuator. 1...Piezo element, 2...Voltage amplifier, 3...Digital-analog converter, 4...
...Piezo position-voltage tape AI (ROM), 6.
... Central processing unit, 6 ... Keyboard for piezo actuator target position setting. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A piezo element, a piezo actuator target position setting means, a piezo element position-voltage value conversion means for converting the set target position into a piezo voltage value, and a piezo actuator for detecting that the target position is decreased from the current position. The present invention is characterized by comprising a target position decrease detecting means, a piezo element applied voltage zero volt setting means for temporarily reducing the applied voltage to the piezo element to zero volts when the target position decreases, and a piezo element voltage applying means for applying a voltage to the piezo element. Piezo actuator drive device.