JPH0798256A - Driving force measuring instrument - Google Patents

Abstract

PURPOSE:To measure a change in driving force based on a change in relative positions between the stator and the mover in a linear motor or the like. CONSTITUTION:A pair of load cells 1a, 1b are abutted with both ends of the linear coil C1 of a linear motor R1. While the linear magnet M1 of the linear motor R1 is moved along the linear coil C1 by a servomotor 5, a difference in outputs of both load cells 1a, 1b is calculated and stored into a memory circuit 8 along with a position of the linear magnet M1 detected by a linear encoder 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor exposure apparatus, IC
The present invention relates to a driving force measuring device for measuring a change in driving force of a driving device such as a linear motor used in a bonding device, various industrial robots, NC machines and the like.

[0002]

2. Description of the Related Art In a semiconductor exposure apparatus, an IC bonding apparatus, various industrial robots, NC machines, etc., it is necessary to control a movable body such as a positioning stage and a robot hand with high precision. A high degree of uniformity is required for the driving force of a linear motion motor such as a motor or a rotary motor such as a servo rotary motor. However, a linear motor or other linear motor tends to change its driving force as the mover moves, and a general rotary motor also has some torque fluctuation depending on the number of rotations and the rotation angle during one rotation. There is usually. Therefore, as described above, in order to control the movement of the movable body such as the positioning stage and the robot hand with high accuracy, it is necessary to measure the change in the driving force of the linear motor or the rotary motor with high accuracy and compensate for this. is necessary.

Conventionally, a thrust measuring device for measuring the thrust acting on a load cell fixed to a movable body, or a torque measuring device for measuring the fluctuation of torque with respect to the rotation speed of a rotary motor has been used.

[0004]

However, according to the above-mentioned conventional technique, the change in the driving force based on the change in the relative position of the mover with respect to the stator of the linear motor or other linear motion motor or various rotary motors is measured. In addition, the measured values often include disturbances other than changes in the driving force, and therefore the driving force cannot be fully compensated, resulting in highly accurate control of the positioning stage, robot hand, etc. Difficult to do.

The present invention has been made in view of the problems of the above-mentioned prior art, and in a direct drive motor such as a linear motor and various rotary motors, the relative position of the mover with respect to the stator of the motor is set. An object of the present invention is to provide a driving force measuring device capable of measuring a change in driving force based on a change or hysteresis.

[0006]

In order to achieve the above object, the driving force measuring apparatus of the present invention has at least one pressure detecting means between one of the mover and the stator of the driving apparatus. First holding means for sandwiching, second holding means for holding the other of the mover and the stator, drive means for relatively moving the first and second holding means, and the mover And a position detecting means for detecting the relative position of the stator.

Further, it is preferable that a pair of pressure detecting means are provided which are brought into contact with both surfaces of one of the mover and the stator of the drive unit.

[0008]

By changing the relative positions of the two holding means, the driving device is driven while changing the relative positions of the mover and the stator of the drive device held by the two holding means. By detecting the driving force of the drive device based on the output of the pressure detection means and detecting the relative position of the mover and the stator, the change of the driving force based on the change of the relative position of the mover and the stator of the drive device. Can be measured.

If there is provided a pair of pressure detecting means that are in contact with either one of the mover and the stator of the driving means, the disturbance included in the measured value is canceled and the measuring accuracy is improved. be able to.

[0010]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view for explaining a driving force measuring apparatus according to an embodiment, which is a linear motor which is a driving apparatus for driving an XY stage of a known stepper (reduction projection type semiconductor exposure apparatus). It measures a change in driving force, and has a pair of load cells 1a and 1b, which are pressure detecting means, which can freely come into contact with both ends of a linear coil C ₁ which is a stator of the linear motor R _1. 1
a is fixed to a column 2a at one end of a support 2 which is a first holding means, and the other load cell 1b is provided with a support 2 through a block 1c whose distance from the column 2a is adjustable by an adjusting screw 3. Is supported by a column 2b at the other end of the.

The linear magnet M ₁ which is a mover of the linear motor R ₁ is reciprocally movable in parallel with the linear coil C ₁ along a guide 2c having low friction or no friction provided on the support 2. A holding member 4a that is held by the movable table 4 that is a holding means and is integral with the movable table 4 is reciprocated in parallel with the linear coil C ₁ by a ball screw 5a that is rotated by a servomotor 5. When the linear magnet M ₁ moves along the linear coil C ₁ by the driving of the servomotor 5, the linear encoder 6 which is the position detecting means supported by the movable table 4 detects the moving amount of the linear magnet M ₁ . The counter 6a calculates a new position of the linear magnet M ₁ from the output of the linear encoder 6 and stores it in the memory circuit 8 which is a storage means. On the other hand, the drive current of the linear motor R ₁ is DA
The linear coil C ₁ is supplied from the converter 9 through the driver amplifier 9a and is excited.

When the linear coil C ₁ is excited, the pressure measurement value of one of the load cells 1a, 1b increases and the pressure measurement value of the other load cell 1a, 1b decreases due to the reaction force of the thrust acting on the linear magnet M ₁ . The respective outputs of both load cells 1a and 1b are introduced into the difference unit 10c via the load cell amplifiers 10a and 10b, and the output of the difference unit 10c is stored in the memory circuit 8 together with the output of the counter 6a via the AD converter 10d. The servo motor 5 is driven by the servo driver 11 based on the command signal of the I / O port 11a and the output of the linear encoder 6.

[0014] of the linear motor R ₁ linear magnet M ₁
The change in the driving force based on the movement of the is measured as follows.

First, before setting the linear coil C ₁ and the linear magnet M ₁ of the linear motor R ₁ between the load cells 1a and 1b, the load cell amplifiers 10a and 10b are operated in the unloaded state of the load cells 1a and 1b. Adjust the offset so that the output becomes zero.
Next, a linear motor R ₁ is placed between the load cells 1a and 1b.
Is set, the preload acting on both load cells 1a and 1b is adjusted by the adjusting screw 3, and each load cell amplifier 10
The gain is adjusted so that the outputs a and 10b are the same. Then, from the I / O port 11a to the servo driver 1
The servomotor 5 is driven by the command signal transmitted to the motor ₁ and the linear magnet M ₁ is moved to a predetermined origin position, whereby the measurement preparation is completed.

From the DA converter 9 to the driver amplifier 9a
A predetermined drive current is supplied to the linear coil C ₁ via
When this is excited, as described above, the linear magnet M ₁
The pressure reaction value of one of the load cells 1a and 1b decreases and the pressure measurement value of the other increases due to the reaction force of the thrust acting on the load cells.
It is sent to the subtractor 10c via b and the difference is calculated.
By thus obtaining the difference between the outputs of the load cells 1a and 1b, measurement errors due to temperature drift and hysteresis of the load cells 1a and 1b are offset, and the thrust acting on the linear magnet M ₁ is measured with extremely high accuracy. be able to.

The output of the subtractor 10c is the linear magnet M
After having been stored in the memory circuit 8 as a driving force of the linear motor R ₁ in ₁ origin, to drive the servo driver 11 by a command signal of the I / O port 11a, by rotating the servo motor 5 at a predetermined moving speed While moving the linear magnet M ₁ , as described above, the linear encoder 6
The driving force calculated on the basis of the position of the linear magnet M ₁ detected by and the output of both load cells 1a and 1b is stored in the memory circuit 8.

The data stored in the memory circuit 8 is displayed by the display device of the plotter 8a or the CPU (computer) 8b, and stored in the disk device 8c if necessary.

In order to measure the hysteresis characteristic of the driving force of the linear motor R _{1 at} a predetermined position, the linear magnet M ₁ is moved to the predetermined position and the linear coil C ₁ is moved.
The drive current command value and the pressure measurement value at that time may be stored in the memory circuit 8 while changing the drive current supplied to the motor back and forth.

According to this embodiment, the change in the driving force due to the change in the position of the mover of the linear motor and the hysteresis characteristic of the driving force at a predetermined position can be measured with extremely high accuracy.
By changing the drive current of the linear motor or the like in accordance with these, it is possible to compensate for changes in drive force and hysteresis, and to keep the drive force constant at all times. As a result, the positioning stage and the robot hand can be controlled with high accuracy.

FIG. 2 shows a modification of this embodiment.
This is the linear coil C of the linear motor R ₁ of this embodiment.
Load cell 1a to ₁ at both ends, instead of to abut the 1b, to secure the ends of the linear coil C ₂ of the linear motor R ₂ to the support 2, both surfaces on the load cell 21a of the projecting portion of the linear magnet M _2, 21b respectively The driving force of the servomotor 5 is transmitted to the holding member 24a that abuts and holds them. This modification has an advantage that the output of the linear encoder 6 does not include a measurement error due to the deformation of the load cells 21a and 21b because the linear coil C ₂ is fixed to the support 2.

Further, in order to measure the fluctuation of the torque during one rotation of the rotary shaft of the rotary motor, as shown in FIG. 3, the load cells 31 are provided on both sides of the protrusion provided on the rotary shaft S _3.
a and 31b are brought into contact with each other, and these are made into an annular support 3
2 load cells 31a, 3
The torque applied to the rotating shaft S ₃ may be calculated from the output difference of 1b in the same manner as described above.

[0023]

Since the present invention is configured as described above, it has the following effects.

In linear motion motors such as linear motors and various rotary motors, it is possible to measure the change in driving force and the hysteresis characteristic based on the change in the relative position of the mover with respect to the stator of the motor with high accuracy. If the driving force of the motor is compensated based on the obtained measured value, the positioning stage, the robot hand, etc. can be driven with a uniform driving force, and these can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an example.

FIG. 2 is an explanatory diagram illustrating a modified example of the apparatus of FIG.

FIG. 3 is an explanatory diagram illustrating another modified example of the apparatus of FIG.

[Explanation of symbols]

1a, 1b, 21a, 21b, 31a, 31b Load cell 2, 32 Support body 3 Adjusting screw 4 Movable table 4a, 24a Holding member 5 Servo motor 6 Linear encoder 8 Memory circuit 10c Difference device 11 Servo driver

Claims (3)

[Claims] 1. A first means for sandwiching at least one pressure detecting means between one of a mover and a stator of a drive device.
Holding means, second holding means for holding the other of the mover and the stator, drive means for relatively moving the first and second holding means, and the mover and the stator. A driving force measuring device comprising position detecting means for detecting a relative position. 2. The driving force measuring device according to claim 1, further comprising a pair of pressure detecting means that are in contact with both surfaces of one of the mover and the stator of the driving device. 3. The driving force measuring device according to claim 1, further comprising a storage unit that stores the output of the pressure detection unit together with the output of the position detection unit.