JPH0373252A - Moving stable device - Google Patents

Abstract

PURPOSE:To perform high-precision and high-reliability moving control of a table over a long stroke by comparing table position detected signals from a detecting means with a signal for a table desired position and providing a control means which outputs signals to drive a micrometer displaced element based on the comparison result. CONSTITUTION:A detector 22 detects the axial position variation, the feed nonuniformity, etc., of a moving table 18. Next, a controller 23 drives a micrometer displayed element 21 using piezoelectric effect with a difference in comparison of the position detected signals with the respective desired values defined as electric input and corrects and controls the operation of the moving table 18.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is suitable for being incorporated as a sample stage in microfabrication devices such as video disks and ultra-LSIs, and the present invention is suitable for incorporating as a sample stage in microfabrication devices such as video disks and VLSIs, and the positional accuracy of the moving table is This invention relates to a movable table device with high performance.

(Prior Art) In a movable table device incorporated in microfabrication equipment such as a video disk or a VLSI, the table on which the sample is mounted is generally moved horizontally at a constant speed or positioned at a fixed position. Finely processed. in this case,
If the table is not moved smoothly and with high accuracy over a long stroke, there is a problem that the processing accuracy of the sample will be significantly degraded.

However, in the conventional movable table device,
There are various problems as shown below, and reliability is poor.

For example, as shown in FIG. 1, in many cases as a moving table device conventionally used for this purpose, a rotationally controlled motor 1 is decelerated by gears 2 and 3, and a feed screw 5 is rotated. Since the feed screw 5 is supported in the axial direction by the bearing 4, the nut 6 moves in the axial direction. The movement of this nut 6 is connected to a moving table 8 by a connecting rod 7, and the movement of the moving table 8 supported relative to a base 10 by a guide 9 is controlled.

In this case, even if the rotation of the motor is controlled with high accuracy, there is a drawback that speed unevenness in the feeding direction occurs due to the accuracy of machining and assembly of mechanical parts such as transmission parts such as gears, bearings, and feed screw nuts. Furthermore, there is a limit to the accuracy of processing and assembling these parts, and there is also a drawback in that the accuracy deteriorates due to wear and the like. Since such a drive mechanism was directly connected to the movable table, the movement of the movable table was greatly affected by the accuracy of the drive mechanism, which was a major hindrance in microfabrication, which required precision of about 11 μm. It had become.

On the other hand, as shown in Japanese Unexamined Patent Publication No. 49-101812, a fine movement feeder using a laminated electrostrictive body and an electromagnetic device has been proposed. This is an intermittent feed type fine movement device that combines the expansion and contraction of a laminated electrostrictive body with the fixing and opening of an electromagnetic device.

Since this fine feeder is an intermittent feeder, it takes time to perform coarse feed with a long stroke. Therefore, high-speed positioning cannot be achieved.

Furthermore, even if the above two examples were simply used in combination, the result would be a two-stage table consisting of a coarse movement feed table and a fine movement feed table, and its size cannot be expected to be reduced.

(Problems to be Solved by the Invention) In this way, the conventional moving table device that uses mechanical parts to convert the rotation of a motor into linear feed has a limit in feed accuracy, is not suitable for micromachining, and is Fine-movement feed devices using strained bodies or the like have had problems in that long stroke feed is not possible or the feed is intermittent, making high-speed positioning difficult.

The present invention has been made to solve these drawbacks in consideration of the above circumstances, and its purpose is to provide a system suitable for incorporating into a microfabrication device that has high table movement accuracy and can be made compact and simple. An object of the present invention is to provide a highly practical moving table device.

[Structure J of the Invention (Means for Solving the Problems) The movable table device of the first invention includes a base serving as a stationary part, a table supported so as to be movable in a predetermined direction with respect to the base, a motor that is fixed to the base and generates a driving force for moving the table; a conversion mechanism that converts the rotational driving force of the motor into a linear movement force in the moving direction of the table; In order to connect the table, a piezoelectric actuator is interposed between the conversion mechanism and the table so that its displacement direction matches the movement direction of the table, and is movable with respect to the base integrally with the table. A fine movement displacement element utilizing the effect, a detection means for detecting the position of the table, a position detection signal from this detection means and a signal of the target position of the table are compared, and the fine movement displacement element is detected based on the result of this comparison. The device is characterized by comprising a control means for outputting a signal for driving the element.

On the other hand, in the movable table device of the second invention, there is provided a base serving as a stationary part, a table supported so as to be movable in a predetermined direction with respect to the base, and a movable table fixed to the base for moving the table. A motor that generates a driving force, a conversion mechanism that converts the rotational driving force of the motor into a linear movement force in the moving direction of the table, and a connection between the conversion mechanism and the table,
a fine movement displacement element using a piezoelectric effect that is interposed between the conversion mechanism and the table so that its displacement direction coincides with the movement direction of the table, and is movable with respect to the base integrally with the table; , a detection means for detecting feed unevenness of the table, and a feed unevenness signal from the detection means and a feed target signal of the table are compared, and a signal for driving the fine movement displacement element is generated based on the comparison result. The present invention is characterized by comprising a control means for outputting the output.

(Function) According to the present invention configured as described above, in the first invention, it is possible to correct table movement errors by the fine movement displacement element that is movable integrally with the table. Therefore, a long stroke, high-speed positioning, and high-precision positioning can be achieved simultaneously with a small device.

In addition, in the second invention, in order to correct the feed error so that it always becomes small by using a fine displacement element that can move integrally with the table, the rotational driving force of the motor is converted into linear movement force. It can be corrected to always cancel vibrations caused by the mechanism to the table, and although it is a small device, it can achieve long strokes, high-speed, high-precision positioning, and smooth feeding without vibrations during movement.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

Figure 2 shows the schematic configuration. rotationally controlled motor 11;
The reduction gears 12, 13, bearings 14, feed screws 15, nuts 16, and guides 19 are the same as in the conventional example shown in FIG. The connecting rod 17 and the moving table 18 are connected to each other via a fine displacement element 21 that utilizes a piezoelectric effect between the connecting rod 17 and a moving table 18 that is movable with respect to the base 20 . Although the internal structure of the fine displacement element 21 that utilizes the piezoelectric effect is not shown in the figure, the internal piezoelectric element operates by slightly displacing it in response to electrical human power. On the other hand, the detector 22 detects changes in the axial position of the moving table 18, unevenness in feed rate, etc., and the controller 23 compares the difference with each target value and uses the difference as an electrical input to drive the fine displacement element 21 using the piezoelectric effect. is used to correct and control the operation of the moving table 18.

Here, in the first invention, the positioning target value of the moving table 18 and the actual moving position of the moving table 18 are compared, and the fine movement displacement element 21 is driven to perform a minute correction.

Further, in the second aspect of the invention, the unevenness in the feed rate of the moving table 18 is always detected and compared with the target value of the feed rate of the moving table 18. As mentioned in the prior art section, the cause of the uneven feed rate is largely due to the precision of mechanical parts, but both appear as vibrations of the movable table 18 and the like.

By constantly correcting these feeding irregularities using the fine displacement element 21, the moving table 18 can achieve smooth feeding without causing vibration or the like.

Thus, according to the movable table device having the above structure,
Since the feeding accuracy of the drive mechanism composed of mechanical parts is sufficient as long as it is within the correction ability of the fine displacement element using the piezoelectric effect, a long stroke drive mechanism can be easily created. By making it movable integrally with the micro-displacement element that utilizes the piezoelectric effect over the entire stroke, it is possible to make minute corrections over the entire stroke, ensuring a highly reliable long-stroke precision that guarantees a feed accuracy of 0.1 μm or less. A moving table is effectively realized.

Note that the present invention is not limited only to the above embodiments. For example, the effects of the present invention will not change even if the components of the drive mechanism, such as the motor, gear bearing, and feed screw, are replaced with other parts, and even if the configuration of the measurement system, such as the detector, is modified in various ways. Further, the mechanical conversion mechanism such as the nut 16 and the moving table 18 can be connected to the fine displacement element 21 without using the connecting rod 17.
The connection may be made directly through the connection, or indirectly through a plate spring or the like that provides preload to provide flexibility. Furthermore, it is also possible to incorporate this device into devices other than video disks and VLSIs.

In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As detailed above, according to the present invention, the drawbacks of the conventional device are eliminated, the movement of the table can be controlled with high accuracy and reliability over a long stroke, and the device is small in size and highly practical. A moving table apparatus can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the structure of a conventional moving table apparatus, and FIG. 2 is a block diagram showing the structure of a moving table apparatus according to an embodiment of the present invention. 1.11...Motor, 4,14...Bearing, 2,3゜12.13...Gear, 5.15...Feed screw, 6゜16...Nut, 9,19...・Information, 7, 17...
・Connecting rod, 8, 18...Moving table, 10.20・
... base, 21 ... fine movement displacement element using piezoelectric effect, 22 ... detector, 23 ... controller. 3.

Claims (5)

[Claims] (1) A base as a stationary part; a table supported so as to be movable in a predetermined direction with respect to the base; a motor fixed to the base and generating a driving force for moving the table; a conversion mechanism for converting a rotational driving force into a linear movement force in the movement direction of the table; and a conversion mechanism whose displacement direction is made to match the movement direction of the table in order to connect the conversion mechanism and the table. a fine displacement element using a piezoelectric effect that is interposed between the conversion mechanism and the table and is movable with respect to the base integrally with the table when the table is moved by the driving force of the motor; and a detection means for detecting the position of the table, comparing a position detection signal from the detection means with a signal of a target position of the table, and outputting a signal for driving the fine displacement element based on the comparison result. A movable table device comprising: a control means for controlling; (2) a base as a stationary part; a table supported so as to be movable in a predetermined direction with respect to the base; a motor fixed to the base and generating a driving force for moving the table; a conversion mechanism for converting a rotational driving force into a linear movement force in the movement direction of the table; and a conversion mechanism whose displacement direction is made to match the movement direction of the table in order to connect the conversion mechanism and the table. a fine displacement element using a piezoelectric effect that is interposed between the conversion mechanism and the table and is movable with respect to the base integrally with the table when the table is moved by the driving force of the motor; and a detection means for detecting feed unevenness of the table, comparing a feed unevenness signal from the detection means with a feed target signal of the table, and driving the fine displacement element based on the comparison result. A moving table device comprising: a control means for outputting a signal; and a control means for outputting a signal. (3) In order to reduce vibrations during movement of the table, the control means constantly compares the feed unevenness signal from the detection means with the feed rate target of the table while the table is moving, and performs this comparison. 3. The movable table device according to claim 2, wherein a signal for driving the fine displacement element is outputted so that the difference becomes small. (4) The fine displacement element is located at at least one location between a connecting portion connecting the converting mechanism and the table, between the converting mechanism and the connecting portion, or between the connecting portion and the table. A high-precision moving table device according to claim 1 or 2, characterized in that at least one is arranged. (5) The conversion mechanism is comprised of a feed screw that is rotationally driven by the motor, and a nut that moves linearly in the movement direction of the table by rotation of the feed screw. High-precision moving table device according to item 1 or 2.