JPH109896A - Encoder for linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce factors for changing measuring accuracy by directly detecting a magnetic pole position of a mobile part and linear movement thereof. SOLUTION: A transmission part and a light shielding part on the position detecting side are passed between a projection part and a photodetecting part of two photo interrupters 1a and 1b so that outputs of the photo interrupters 1a and 1b are turned ON or OFF to obtain pulses of a phase (a) and a phase (b), which allows the detecting of a moving value and a moving speed of a linear synchronous motor 4. In addition, a transmission part of light made larger than the length of one magnetic pole and a magnetic pole detection side of a slit plate 3 as light shielding part formed at a part other than the transmission part are passed between projection parts and photodetecting parts of three photo interrupters 2a, 2b and 2c arranged with a phase difference of 120 deg. at each pitch of the magnetic pole of the linear motor 4. For example in the case of the linear synchronous motor 4 having three phases of armature windings at the mobile part, it can be detected that any of windings (u), (v) and (w) exists at an operation position of the photo interrupters thereby helping accomplish smooth movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor encoder for detecting the position, moving speed, and position of magnetic poles of a linear synchronous motor.

[0002]

2. Description of the Related Art An encoder for detecting the position of a linear synchronous motor converts a linear movement into a rotational movement by combining a rotary rotary encoder with a rack and a pinion.
The linear movement distance was measured. FIG. 6 shows a configuration diagram of a conventional rotary encoder. In FIG. 6, 11
Is a light emitting element, 12 is a rotating disk provided with a slit 13 for transmitting the light of the light emitting element 11 on a disk, 14 is an a phase detecting light transmitted from the light emitting element 11 through the slit 13 of the rotating disk 12 at a fixed position, A fixed slit plate serving as a b-phase light source and a z-phase light source, 15 a light receiving element for a phase, 16 a light receiving element for b phase, and 17 a light receiving element for z phase. In FIG. 6, the rotating disk 12 is connected via its axis to a gear (pinion) outside the rotary encoder, and the gear meshes with a rack provided with a linear tooth profile to convert the linear movement of the rack into a rotational movement. Then, the linear moving distance of the rack is converted into the rotation angle of the rotating disk 12.

The light of the light emitting element 11 is received by the respective light receiving elements through the slit 13 of the rotary disk 12 and further through the slit of the fixed slit plate 14, so that the rotation of the rotary disk 12 causes the light receiving and the light shielding to be alternately performed. Is pulsed. Further, the light receiving elements are arranged so as to be shifted from each other so as to have a phase difference of 90 ° electrically, so that a-phase and b-phase pulses can be obtained.

The moving distance can be measured by counting the a-phase pulses. Further, the moving speed is detected by counting the a-phase pulses within the unit time. The b-phase pulse is used to determine the moving direction depending on which pulse rises first in comparison with the a-phase pulse. The z-phase pulse is used to determine a reference position. Usually, this kind of rotary encoder is used by adjusting with a gear so that the entire moving stroke is within one rotation of the rotating disk 12.

[0005]

By the way, in the conventional configuration, the linear movement is converted into the rotational movement by using a rotary encoder, a rack and a pinion, a chain and a chain sprocket to detect the linear movement. There is a problem that the detection unit cannot be downsized because the position is detected from the position. When a chain or a wire is used instead of the chain, it is necessary to compensate for a change in measurement accuracy due to the elongation of the chain or the wire.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a linear motor encoder which directly detects a linear movement and does not need to compensate for a change in measurement accuracy. .

[0007]

According to the first aspect of the present invention, in a linear motor encoder for transmitting a detection signal of a position of a linear motor, the position detecting section is attached to a movable section of the linear motor. Over substantially the entire length of one side parallel to the traveling direction of the linear motor, alternately having a transmitting portion that transmits light at a predetermined pitch, and a light shielding portion, and over substantially the entire length of the other side, at every magnetic pole pitch of the linear motor. A strip-shaped slit plate having a light-transmitting portion longer than the length of one magnetic pole, and a light-shielding portion in a portion other than the transmitting portion;
The same number of magnetic pole detecting photo-interrupters as the number of magnetic poles, each having a light emitting unit and a light receiving unit, and arranged at the magnetic pole detection side of the slit plate, and a slit plate position detecting side having a light emitting unit and a light receiving unit respectively. 9 electrically placed in
It is assumed that the encoder of the linear motor includes a photo interrupter that transmits a signal having a phase difference of 0 °.

With the above configuration, the output of the photo-interrupter is turned on and off by passing between the light-projecting unit and the light-receiving unit of the two photo-interrupters through the transmission unit and the light-shielding unit on the position detection side. Then, a-phase and b-phase pulses are obtained. In addition, between the light emitting part and the light receiving part of the three photo-interrupters arranged with a phase difference of 120 °, at every magnetic pole pitch of the linear motor, a light transmitting part longer than one magnetic pole and a part other than the transmitting part For example, in the case of a linear synchronous motor having a three-phase armature winding in the movable part,
Since it is possible to detect which of the windings u, v, and w is at the operating position of the photo interrupter, it is possible to determine the magnitude and polarity of the current to be applied to the windings of each phase when the movement is started.

According to the second aspect of the present invention, in the linear motor encoder according to the first aspect, the slit plate is formed by providing a light-transmitting plate with a light-shielding film in a portion other than a portion forming a transmission portion. Linear motor encoder. With the above configuration, the light transmitting portion and the light shielding portion can be configured with or without the light shielding film, so that the number of processed portions of the slit plate is reduced, and the width of the transmission portion is narrowed, so that the detection accuracy can be improved. In addition, it is possible to prevent the photo interrupter from being caught when moving.

According to the third aspect of the present invention, in the linear motor encoder according to the first or second aspect, the slit plate has a corner portion cut off so that both ends in the longitudinal direction form a trapezoid. Encoder. According to the above configuration, it is possible to prevent a collision with the photo interrupter when the slit plate enters between the light emitting unit and the light receiving unit of the photo interrupter.

According to a fourth aspect of the present invention, in the encoder for a linear motor according to any one of the first to third aspects, the moving range is longer than the length of the slit plate attached to the movable portion of the linear motor. In addition, a photointerrupter for magnetic pole detection and speed / position detection at a predetermined pitch is provided to provide a linear motor encoder capable of transmitting a detection signal over the length of the slit plate.

With the above configuration, it is possible to transmit a position detection signal over a moving range that is longer than the length of the slit plate of the encoder.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A and 1B show a main part of an embodiment of the present invention. FIG. 1A is a side view, and FIG.
FIG. 3C shows an arrangement diagram with an interrupter, and FIG. In FIG. 1, reference numeral 1 denotes a speed / position detection sensor (photo interrupter), and reference numeral 1a denotes an A-phase pulse photo interrupter unit. Reference numeral 1b denotes a B-phase pulse photo interrupter provided in the speed / position detection photo interrupter unit 1. 2 is a magnetic pole detection sensor (photo interrupter), 2a is a U-phase magnetic pole photo sensor.
An interrupter, 2b is a photo-interrupter for a V-phase magnetic pole, and 2c is a photo-interrupter for a W-phase magnetic pole, which is provided in the photointerrupter unit 2 for magnetic pole detection. 3 is a rectangular slit plate provided with a light transmitting portion and a light blocking portion, 4 is a linear synchronous motor, 5 is a speed / position detecting photo interrupter 1a, 1b, and a magnetic pole detecting photo interrupter 2a, 2b, 2c. 3 shows a mounting plate. Each interrupter includes a light emitting unit and a light receiving unit, and a slit plate 3 is arranged between the light emitting unit and the light receiving unit.

In FIG. 1 (a), a slit plate 3 is attached to a movable portion of a linear synchronous motor 4. On one side of the slit plate 3, photo-interrupters 1a and 1b for speed / position detection are moved in the traveling direction. The magnetic pole detection photo-interrupters 2a, 2b, and 2c are electrically disposed in the traveling direction on the other side.
Are disposed on the mounting plate 5 with a phase difference of
(B)).

When the linear synchronous motor 4 is moved in the above configuration, the magnetic pole detection photo interrupters 2a, 2b, 2
c, U, each having an electrical phase difference of 120 °,
The V and W waveforms are output, and the A / B phases having an electrical 90 ° phase difference are output from the speed / position detection photo interrupters 1a and 1b (see (c)). Since the movement amount of the linear synchronous motor 4 can be detected by counting the A-phase pulse, the position of the linear synchronous motor 4 can be detected by combining with another sensor (not shown) for detecting an absolute position. . Further, the moving speed can be detected by counting the A-phase pulses per unit time. The B-phase pulse is used to detect the moving direction depending on which of the A-phase pulse rises first.

On the other hand, a photo interrupter 2 for detecting magnetic poles
Regarding a, 2b, and 2c, a linear synchronous motor 4 having a three-phase armature winding on a movable portion and a permanent magnet disposed on a fixed side.
An example will be described with reference to FIG. In FIG.
The three-phase alternating currents are arranged in the order of U, W, and V in order to move the linear synchronous motor 4 from left to right as viewed in the drawing, and the W and V phases are reversely connected. If this is performed in the order of U, V, and W, the moving direction is from right to left as viewed in the drawing. In the figure, N and S are magnetic poles of a permanent magnet, which are electrically arranged at a pitch of 180 °, and u, v, and w are u phases,
5 shows a v-phase and w-phase armature winding. The winding of each phase is electrically 2
Within the width of 40 °, the innermost of the reciprocating conductors are wound so that they are close to each other and are sequentially superimposed on each other to form an oval flat plate, and each phase is an independent winding of an oval flat plate. And
The u, v, and w phases are sequentially electrically overlapped by 120 °. In this configuration, U-, W-, and V-phase alternating currents are applied, for example, fixed permanent magnets N and S poles and armature windings u,
When a current corresponding to 0f is applied when the relative position of the v and w phases is 1P, the maximum value Im of the u phase flows to the left side from the front side of the paper to the back side when viewed in the cross section of the winding, and the right side The same maximum value Im flows from the back to the front of the paper. v
As for the phase and the w-phase, 1/2 Im flows from the back side to the front side of the drawing when viewed in the cross section of the winding, and the same 1 /
2Im flows from the front to the back of the paper. As a result, since n and s magnetic poles are generated in the armature winding, N and n repel and n and S are attracted to the N and S fixed magnetic poles. Thus, the armature moves from left to right as viewed on the page. The speed of this movement is expressed by a fixed magnetic pole pitch τ _p × 2 × frequency f of the alternating current.

Therefore, the movement amount in one cycle is electrically 2
× τ _p × 1 = 360 °. 1 / 6f and 2 / 6f in the figure
Indicates the instantaneous value of the alternating current at the point of time when it has electrically advanced 1/6 cycle (= 60 °), and the amount of movement = 2 × τ _p × 1/6 cycle = 60 ° every 1/6 cycle from the start Is a diagram showing magnetic poles n and s at which instantaneous values of the alternating current at the positions 2P and 3P are generated on the armature winding. Also at 1 / 6f and 2 / 6f, the n and s magnetic poles of the armature winding repel N and n with the N and S fixed magnetic poles,
It can be seen that n and S are sucked and the armature continuously moves from left to right with respect to the paper surface. Below 3 / 6f, 4 / 6f, 5 / 6f, 6 / 6f
Similarly, the n and s magnetic poles of the armature winding are generated while sequentially moving, and the repulsion and the attraction are repeated between the N and S fixed magnetic poles, so that the armature continues from left to right with respect to the paper surface. Move, but details are omitted.

In the above description, when the positional relationship between the fixed magnetic pole and the armature winding is 1P, the u phase has the maximum value Im at the start.
And v-phase and w-phase are は Im in the opposite direction to u-phase.
, The linear synchronous motor can be moved smoothly in accordance with the change of the alternating current. When the positional relationship between the fixed magnetic pole and the armature winding is 2P or 3P at the start, the currents applied to each phase of the armature winding correspond to instantaneous values of 1 / 6f and 2 / 6f, respectively. By setting the value, the linear synchronous motor can be moved smoothly in accordance with a change in the alternating current. Detecting the positional relationship between the fixed magnetic pole and the armature winding as described above is necessary for smoothly moving the linear synchronous motor, and for this purpose, the magnetic pole detection photo interrupters 2a, 2b, and 2c are used. Is done.

[0019]

FIG. 3 is a block diagram showing a main part of an embodiment of the present invention. In FIG. 3, a rectangular slit plate 30 is a transparent plate coated with a light-shielding film except for a light transmitting portion.
Denotes a transmission part for magnetic pole detection, and 30b denotes a transmission part for speed / position detection. FIG. 4 is a block diagram showing a main part of another embodiment of the present invention. In FIG. 4, a rectangular slit plate 30 is shown.
Reference numeral 0 denotes a transparent plate coated with a light-shielding film except for the light transmitting portion. Reference numeral 30a denotes a magnetic pole detecting transmitting portion, and 30b denotes a speed / position detecting transmitting portion. The front and rear ends in the longitudinal direction are formed in a trapezoidal shape in order to prevent collision when entering the photo interrupter.

FIG. 5 is a block diagram showing a main part of another embodiment of the present invention. In FIG. 5, the slit plate 30 or 300 which is attached to the linear synchronous motor and moves together with the linear synchronous motor has substantially the same length as the linear synchronous motor and is used for speed / position detection when a longer moving distance is required. The speed / position detection photo interrupters 10a, 10b and the magnetic pole detection photo interrupters 20a, 20b are different from the photo interrupters 1a, 1b and the magnetic pole detection photo interrupters 2a, 2b, 2c.
By arranging the 20c at a distance shorter than the length of the slit plate 30 or 300, it is possible to detect the position and the magnetic pole over a moving range longer than the length of the linear synchronous motor. .

[0021]

According to the present invention, since mechanical parts such as a chain and a chain sprocket are not required, the size of the apparatus can be reduced, and the start can be smoothly performed by detecting the magnetic poles. In addition, by forming the light transmitting portion of the slit plate from the cutout to a transparent plate and making the front and rear ends trapezoidal, there is an effect that the sensor is not caught when moving.

[Brief description of the drawings]

FIGS. 1A and 1B are main parts of an embodiment of the present invention, wherein FIG. 1A is a side view, FIG. 1B is a layout diagram of a slit plate and a photo interrupter, and FIG.

FIG. 2 is a diagram illustrating the operation of a linear synchronous motor.

FIG. 3 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 4 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 5 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Speed / position detection photo interrupter 1a, 10a A-phase pulse photo interrupter 1b, 10b B-phase pulse photo interrupter 2 Magnetic pole detection photo interrupter 2a, 20a u-phase magnetic pole detection photo interrupter 2b, 20b v-phase magnetic pole detection photo-interrupter 2c, 20c w-phase magnetic pole detection photo-interrupter 3, 30 slit plate 300 slit plate 4 linear synchronous motor 5 mounting plate

Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01L 31/12 H01L 31/12 D H02P 5/00 101 H02P 5/00 101B // H02K 11/00 H02K 41 / 02 Z 41/02 11/00 C

Claims (4)

[Claims] In a linear motor encoder configured to transmit a detection signal of a position of a linear motor, a position detecting section is attached to a movable section of the linear motor, and extends over substantially the entire length of one side parallel to the traveling direction of the linear motor. A transmission portion that transmits light at a predetermined pitch and a light-shielding portion are alternately provided, and the transmission portion of light longer than the length of one magnetic pole for each pitch of the magnetic poles of the linear motor and the transmission over substantially the entire length of the other side. A strip-shaped slit plate having a light-shielding portion in a portion other than the portion, a light-emitting portion and a light-receiving portion, each of which is provided at the magnetic pole pitch on the magnetic pole detection side of the slit plate, and has the same number of magnetic pole detection photo interrupters as the number of magnetic poles; And a photo-interrupter, each of which has a light projecting part and a light receiving part, and is arranged on the position detecting side of the slit plate and electrically transmits a signal having a phase difference of 90 °. Encoder linear motor characterized. 2. The linear motor encoder according to claim 1, wherein the slit plate is formed by providing a light-transmitting plate with a light-shielding film on a portion other than a portion forming a transmission portion. Encoder. 3. The encoder for a linear motor according to claim 1, wherein the slit plate has a corner portion cut off so that both ends in the longitudinal direction form a trapezoid. 4. The linear motor encoder according to claim 1, wherein a magnetic pole is detected at a predetermined pitch in a moving range of a length longer than a length of a slit plate attached to a movable portion of the linear motor. A linear motor encoder characterized in that a photo interrupter for speed and position detection is provided so that a detection signal can be transmitted over the length of the slit plate.