JPH0564487A - Positioning table unit - Google Patents

Abstract

PURPOSE:To provide a positioning table unit comprising a polyphase linear motor wherein the stage motion can be initialized stably even if a position detecting element is eliminated. CONSTITUTION:A positioning table unit comprising a table 1 position detector 9 and polyphase motors 3, 4 for selectively switching the coil to be conducted and the direction of current according to the position of the table 1 is provided with a section 17 for determining the coil to be conducted and the direction of current based on the moving amount of the table 1 corresponding to a predetermined command value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device having a position detector for detecting the position of a table, a coil to be energized according to the position of the table, and a polyphase type linear motor for selectively switching the current direction. The present invention relates to a table device.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional example of a positioning table device equipped with a linear motor having polyphase coils. In this figure, 1 is a table top plate, 2 is a guide, 3 is a coil support member, 4 is a linear motor coil, 5 is a position detecting element, 6 is a magnet attached to the table top plate, 7 is a light shielding plate, 8
Is an origin switch, 9 is a position detector (linear scale) for detecting the position of the table, 10 is a counter unit, 1
Reference numeral 1 is a motor amplifier, and 12 is a position and speed controller. The position detection of the movable magnet 6 is performed by the position detection element 5 arranged in the coil 4. As the position detecting element, for example, a Hall element is used, and by detecting the polarity (N, S pole) of the movable magnet 6, a predetermined coil is energized.

FIG. 2 shows an example of a polyphase linear motor.
A driving method of a linear motor having a four-phase coil is shown. The movable magnet 6 is composed of four pairs of permanent magnets. The coils are numbered 1 to 4 for convenience. B, F
The mark indicates the direction of the current that is applied to the coil. Figure 2 (a)
From (h) to (h), depending on the position of the movable magnet 6,
The movable magnet 6 can be switched by switching the direction of the energized coil and the current.
The (table) can be moved in a predetermined direction.

The motor amplifier 11 performs such a switching operation. FIG. 3 shows a configuration example of the motor amplifier. Reference numeral 13 is a selector for selecting a coil to be energized by a signal from the position detecting element, 14 is an analog switch, 15 is an inverting amplifier, and 16 is a current amplifier for supplying a current proportional to the command value to the coil. The position detector outputs a phase-shifted signal of phase A and a phase-B signal, which is converted into an up and down signal by waveform shaping in the counter unit and input to the counter circuit to obtain the stage position. However, in order to obtain the absolute position of the table, it is necessary to drive the stage to a predetermined position and initialize the counter circuit. Therefore, in such a system configuration, the relative position signal from the counter unit is differentiated in the controller to be used as a speed signal to form a speed servo loop to drive the table to the origin switch. Then, when it passes through the origin switch, a predetermined value is written in the counter circuit to set the absolute position of the table.

[0005]

However, the above-mentioned conventional example has the following problems because the position detecting element is used. (1) It is necessary to manufacture an expensive coil unit incorporating a position detection element. (2) Since many wirings are laid out from the position detection element, the wiring work is troublesome and troublesome, and the risk of disconnection increases. (3) If even one position detecting element is damaged, the table will not operate normally. (4) In order to keep the output from the position detecting element constant, it is necessary to maintain the gap between the magnet and the magnet to a predetermined accuracy, which makes maintenance maintenance troublesome.

The present invention has been made in view of the above-mentioned drawbacks of the prior art. In a positioning table device equipped with a polyphase linear motor, the stage is stable and the initializing operation is possible even if the position detecting element is eliminated. An object is to provide a device configuration that can be performed.

[0007]

In order to achieve the above-mentioned object, the present invention adds a judging section for deciding a coil to be energized and a current direction according to a moving amount of a stage with respect to a predetermined command value. The table is driven in a predetermined direction by a signal from, and a stable initialization operation is performed.

[0008]

FIG. 1 shows an embodiment of the present invention. Reference numeral 17 is a determination unit that outputs a predetermined command value Vt and determines the coil to be energized and the current direction from the amount of movement of the stage. Next, the operation will be described. First, the positional relationship between the magnet 6 and the coil is naturally unknown. However, the relative position (movement amount) of the stage can be detected by the counter unit. Now, for example, it is assumed that the positional relationship shown in FIG. Further, if the table is driven in the direction of the arrow (→) in FIG. 2, the origin switch can be passed. First, a rectangular signal is input to the coil 1 in the direction of the current shown in FIG. Here, the voltage V1 and the time t1 are appropriately determined, but may be set to a level at which the moving direction of the table can be reliably determined.

In this case, even if such a command value is given, since there is no magnet on the coil 1, the amount of movement of the stage cannot be detected. Therefore, the same command value is added to the coil 2 next.
Then, as shown in Fig. 4 (b), the magnet has an anti-arrow (anti-origin).
Although it moves to the side, this kind of movement can be easily judged because the amount of movement of the stage is detected, and in the end it is necessary to reverse the direction of the current in order to drive to the origin switch side. To do. Therefore, as shown in FIG. 4C, the direction of the current is reversed (DIR = L) and a stepwise command value V2 is applied to the coil 2. Then, the magnet moves toward the origin, but eventually stops at the next switching position due to the balance of forces.

Whether or not it has stopped can be determined by detecting the amount of displacement, and when the stop is confirmed, the same operation is repeated in the next coil 3. By performing this operation continuously, the stage is driven to the origin switch. If the origin switch is not passed even when the coil 4 is driven, the same operation may be repeated from the coil 1. After the completion of the initialization operation, the linear motor is driven according to a predetermined drive sequence (see FIG. 2).

In the above embodiment, the presence or absence of the magnet and the direction of the current are determined by the rectangular wave. However, when the friction component of the stage guide is extremely small, the stage moves greatly even when a minute rectangular wave is applied. Therefore, it may occur that the initializing operation thereafter may be hindered. Therefore, the determination unit 17 determines the command value Vt such that the integrated value of the current to be supplied, such as (a) sine wave or (b) square wave shown in FIG. 5, becomes zero.
You can solve it by giving more.

Further, in the above-mentioned embodiment, the stage is driven toward the origin side by adding a constant command (constant current) value stepwise, but it is conceivable that the stage speed becomes too high. Therefore, the command value can be solved by using a function of time as shown in FIG.

In the above embodiment, the initializing operation is performed while the coils 1 to 4 are sequentially energized. However, when the number of coils is large (the stroke is long), for example, the coils 1, 3, 5 ,. It is also possible to shorten the initialization time by energizing at intervals such as.

Further, in the above-mentioned embodiment, the next operation is started after the stage is stopped after energization. However, the initialization time can be shortened by shifting to the next operation when the stage becomes less than a certain amplitude.

Further, in the first embodiment, a linear scale (optical type, magnetic type, etc.) is used as a position detector, but in a highly accurate positioning table device such as a semiconductor stepper, a laser length measuring device is used. Is used.

Further, the present invention can be similarly applied to a rotary stage device equipped with a rotary multi-phase motor.

[0017]

As described above, according to the present invention, the position detector for detecting the position of the table and the multi-phase type motor for selectively switching the coil to be energized and the current direction according to the position of the table. In the positioning table apparatus including the above, the initialization operation can be stably performed even if the position detection element is eliminated, and the cost reduction and the reliability improvement of the apparatus can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a positioning table device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a driving state of a polyphase linear motor, in which (a) to (h) sequentially show special states.

FIG. 3 is a configuration diagram of a conventional motor amplifier.

4 (a), (b), and (c) are explanatory views of command values according to an embodiment of the present invention.

5 (a) and 5 (b) are explanatory views of special examples of command values according to other embodiments of the present invention.

FIG. 6 is an explanatory diagram of command values according to still another embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional positioning table device.

[Explanation of symbols]

1; table top plate, 2; guide, 3; coil support member,
4; motor coil, 5; position detection element, 6; movable magnet,
7: Light-shielding plate, 8: Origin switch, 9: Position detector, 1
0; counter unit, 11; motor amplifier, 12; control controller, 13; selector, 14; analog switch, 15; inverting amplifier, 16; current amplifier, 17; judgment unit.

Claims (2)

[Claims] 1. A positioning table device comprising a position detector for detecting the position of a table, a coil to be energized and a polyphase type motor for selectively switching the current direction according to the position of the table, and a predetermined command. A table device comprising: a determination unit that determines a coil to be energized and a current direction according to a movement amount of the table with respect to a value. 2. The positioning table device according to claim 1, wherein the table is driven in a predetermined origin direction in response to a signal from the determination unit to perform an initialization operation.