JPH04364055A - Positioning controller - Google Patents

Abstract

PURPOSE:To shorten an aligning time and improve the throughput of a whole device by providing a means which averages the deviations of the measuring position of a moving body from a target position and comparing the average with the prescribed judging reference. CONSTITUTION:The position of an XY stage 1 is measured by a present position counter 6 based on an output signal from a length measuring machine. The moving target position of the stage is set by a CPU 7 for the target position latch 9 of the XY stage. A differenciating machine 10 outputs the deviation of the present position counter 6 from the target position latch 9. The deviation output is inputted into a position servo amplifier 11 as a feed back signal for position servo control. The output from the position servo amplifier 11 is inputted into a driver 3 and the XY stage 1 is driven by the position servo control. The CPU 7 judges the completion of the alignment of the XY stage from the value of the present position counter 6 and from the target position and an alignment completion signal 12 is outputted.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a positioning control device for positioning a moving body to a target stop position, and is particularly suitable for positioning a moving body such as an XY stage that requires high-speed and high-precision positioning. The present invention relates to a positioning control device.

0002

[Prior Art] Conventionally, X in a reduction projection exposure apparatus, etc.
A positioning control device for a moving body such as a Y stage usually
The deviation between the measured position and the target position after the Y stage movement is completed is sampled, and if the deviation remains within a predetermined determination reference value for a predetermined time, it is considered that positioning is complete.

0003

However, in the conventional example described above, only the vibration amplitude was used as a means for confirming the completion of positioning, regardless of the frequency of the residual vibration, and therefore there were the following drawbacks.

That is, since the XY stage of a reduction projection exposure apparatus requires high-speed and highly accurate positioning,
The position measurement accuracy is high, and it detects not only the vibrations of the moving body (XY stage) itself, but also the vibrations of external actuators (pulse motors, etc.). If such external vibration has a high frequency and a certain amplitude, it will not affect the printing performance of the reduction projection exposure apparatus. However, in the conventional example, positioning is not completed unless the amplitude of vibration at any frequency falls below a certain value, which increases loss time, which is not preferable for increasing the throughput of the apparatus.

As an example, FIG. 3 shows a typical positioning situation of the XY stage at the end of movement. The horizontal axis represents time t, and the vertical axis represents the deviation from the target position of the XY stage. Although this positioning waveform contains vibrations of a relatively high frequency as disturbance, it is assumed that these vibrations do not affect the printing performance of the reduction projection exposure apparatus. In the traditional method,
The deviation between the measurement position of the XY stage and the target position is the judgment standard ±
Since it does not enter T, positioning will not be completed no matter how long it takes, even though it is in a state where printing is possible.

The present invention has been made in view of the above-mentioned problems with the conventional type, and aims to increase the speed of positioning in a positioning control device that controls the movement of a moving body and positions it at a target stop position. The purpose is to achieve this without impairing the basic performance of the main unit to which it is applied.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a positioning control device for controlling the movement of a moving object and positioning it at a target stop position, and a method for confirming completion of positioning of the moving object. The determination system includes means for averaging the deviation between the measured position of the moving body and the target position over a certain period of time, and means for determining that positioning is complete when the average value satisfies a predetermined determination condition. It is characterized by

[0008] The averaging means averages the deviation, using a period of time equal to a period of a disturbance frequency that does not adversely affect the operation of the main unit to which the positioning control device is applied, as the certain period of time.

[0009] Furthermore, the determining means determines the positioning based on, for example, the average value of the deviation between the measured position of the moving object and the target position over a certain period of time being within a predetermined determination reference value continuously for a predetermined determination time. Confirm completion. In this case, the determination time is set equal to, for example, a half period of a typical positioning frequency of the moving body.

0010

[Operation] According to the present invention, as described above, in a positioning control device such as an XY stage, the deviation between the measured position of the moving object and the target position is used as a determination system for confirming the completion of positioning of the moving object. By providing an averaging means and comparing the average value with a predetermined determination condition, completion of positioning is determined while ignoring high frequency vibrations that do not affect device performance. Therefore, it is no longer necessary to wait until the high-frequency vibration has sufficiently subsided, or until the deviation caused by the superimposed high-frequency vibration accidentally falls within a predetermined positioning criterion, reducing loss time and improving positioning control. The throughput of the entire device including the device and the main device can be improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a control circuit for an XY stage positioning device according to an embodiment of the present invention. In the figure, 1 is an XY stage, 2 is a drive motor, and
The Y stage 1 and the motor 2 are coupled, for example, by a ball screw. The motor 1 is driven by a driver 3. Further, a tacho generator 4 is added to the motor 1, and the output of the tacho generator 4 is fed back to the driver 3 for speed control. The position of the XY stage 1 is measured by a current position counter 6 based on the output signal of the length measuring device 5. As the length measuring device 5, a laser interferometer or the like can be used. Microprocessor (CP)
In U) 7, the value of the current position counter 6 can be known through the main bus 8.

Numeral 9 is a target position latch for the XY stage, and the target position of the stage is set by the CPU 7. 10 is a difference device which outputs the difference between the current position counter 6 and the target position latch 9. This deviation output is input to the position servo amplifier 11 as a feedback signal for position servo control. Position servo amplifier 1
1 is input to the driver 3, and the XY stage 1 is driven by position servo control. 12 is a positioning completion signal, and the CPU 7 determines the completion of positioning of the XY stage from the value of the current position counter 6 and the target position, and outputs the positioning completion signal 12.

FIG. 2 is a flowchart for the CPU 7 to determine whether the positioning of the XY stage is complete. Referring to FIG. 2, CPU 7 first clears a determination time counter n (not shown) (step 600). Next, in step 601, the deviation between the current position and the target position is sampled during a certain period S1, and the average value is set as a. Step 6
At step 02, it is compared whether the average value a is within the determination reference value T, and if it is greater than or equal to the determination reference value T, the process returns to step 600. If the average value a is within the determination reference value T in step 602, the counter n is incremented by one in step 603. If the counter n is not equal to the determination value N in step 604, the process returns to step 601. If the counter n is equal to the determination value N in step 604, it is determined that positioning is complete and the process ends. However, in the above flowchart, when the vibration frequency that does not affect the device performance is f1 or higher, and the typical vibration frequency of the XY stage is f2, S1 and N are set to satisfy the following conditions. It is something to do.

[0014]

[Math 1]

The above operation will be explained using FIGS. 3 and 4. FIG. 3 is a graph showing a typical positioning situation of the XY stage after the movement is completed. Time on the horizontal axis, X on the vertical axis
The deviation from the target position of the Y stage is taken. Although this positioning waveform contains vibrations of relatively high frequency f1 as disturbances, it is assumed that these vibrations do not affect the printing performance of the reduction projection exposure apparatus. FIG. 4 is an average of the waveforms in FIG. 3 for each time S1. The horizontal axis shows time, and the vertical axis shows the average value of deviation. Further, the value of the counter n is shown below the waveform. Here, the determination value N=4. As shown in FIG. 4, the value of the counter n is incremented each time it reaches the determination reference value T, and is cleared to O when it exits from T. When the counter n becomes equal to the determination value 4, positioning is completed.

As described above, according to this embodiment, S1, N
By setting as ■ and ■, it is possible to capture the typical vibration frequency f2 of the XY stage while ignoring disturbance vibrations at a high frequency f1 that does not affect the performance of the device. be.

[0017]

Other Embodiments FIG. 5 shows another embodiment of the invention. In this embodiment, an average value calculator 13 is added to the one in FIG.
Average the deviation between the current position and target position of the Y stage. Based on this average value, the completion of positioning is determined according to the flowchart in FIG. In this way, in this embodiment, the load on the CPU 7 is reduced by using the average value calculator 13 to calculate the average value, so it can be used when controlling multiple axes simultaneously or when high-speed sampling is required. be advantageous to

As yet another embodiment, it is also possible to adopt a method of taking a moving average by overlapping the ranges in which the deviations are averaged, as shown in FIG. in this case,
The positioning completion signal can be issued earlier than the method shown in FIG.

[0019]

As explained above, the present invention is a positioning control device for an XY stage, etc., and is used as a determination system for confirming the completion of positioning of a moving object. By providing a means to average the values and comparing the average value with a predetermined judgment reference value, positioning completion can be determined while ignoring high-frequency vibrations that do not affect device performance. This is effective in shortening the positioning time and improving the throughput of the entire device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control circuit of an XY stage positioning device according to an embodiment of the present invention.

FIG. 2 is a flowchart for determining the completion of positioning in the positioning device of the present invention.

FIG. 3 is a waveform diagram of typical positioning deviation of the XY stage at the end of movement.

4 is a processing timing diagram when the positioning waveform of FIG. 3 is processed according to the flowchart of FIG. 2; FIG.

FIG. 5 is a block diagram of a control circuit of an XY stage positioning device according to another embodiment of the present invention.

FIG. 6 is a processing timing diagram of an XY stage positioning device according to yet another embodiment of the present invention.

[Explanation of symbols]

1: XY stage, 2: Drive motor, 3: Motor driver, 4: Tacho generator, 5: Length measuring device, 6: Current position counter, 7: Microprocessor (CPU), 8:
Main bus, 9: Target position latch, 10: Differentiator, 11
: Position servo amplifier, 12: Positioning completion signal.

Claims (4)

[Claims] Claim 1: In a positioning control device that controls the movement of a movable body and positions it at a target stop position, the deviation between the measured position of the movable body and the target position is used as a determination system for confirming the completion of positioning of the movable body. What is claimed is: 1. A positioning control device comprising: means for averaging over a certain period of time; and means for determining that positioning is complete when the average value satisfies a predetermined determination condition. 2. The judgment condition is that the average value of the deviation between the measured position and the target position of the moving object over a certain period of time is continuously within a predetermined judgment reference value for a predetermined judgment time. Item 1. Positioning control device according to item 1. 3. The positioning control device according to claim 1, wherein the time for averaging the deviations is equal to a period of a disturbance frequency that does not adversely affect the device. 4. Claim 2, wherein the determination time is equal to a half period of a typical positioning frequency of the moving body.
The positioning control device described in .