JPH04194616A - Optical encoder - Google Patents

Abstract

PURPOSE:To obtain a pulse encoder which can inexpensively take out pulses for detecting magnetic poles by providing reflective optical sensors for U, V and W phases for applying light to a magnetic pole detecting pattern in a peripheral direction with predetermined intervals. CONSTITUTION:A rotating slit board 20 is formed with a slit array 10 for A and B phases and a slit 11 for a Z phase, while a surface of a sheet 30 on the side of a terminal board 9 provides a magnetic pole detecting pattern where two bright parts Wh and dark parts Bk are alternately contiguous. On the inner face of the terminal board 9, three reflective optical sensors 50 for U, V and W phases are provided on a peripheral direction with intervals of 60 deg. sequentially so that the sheet 30 can be subjected to irradiation. When reflected light from the bright part Wh of the sheet 30 begins to be incident on the sensor 50 for the U phase, the sensor 50 is turned ON and an output is at an H level. When the slit board 20 rotates 90 deg. and the dark part Bk begins to enter a view field of the sensor 50, the sensor 50 is turned OFF and the output is at an L level. Thus magnetic field detecting pulses can be taken out.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a pulse encoder for AC servo.

[Conventional technology]

The most common pulse encoder is a two-phase pulse encoder that can extract A-phase pulses and B-phase pulses that are out of phase by 90' in electrical angle, as well as a Z-phase pulse that serves as a zero marker signal. When used with a magnet, it is necessary to be able to extract the pulse for magnetic pole detection.

FIG. 5 shows a conventional pulse encoder of this type, where 1 is a four-pole AC motor and 3 is an encoder. 4
is a frame of the pulse encoder 3, which is attached to the end plate of the AC motor 1 with a mounting member 5, through which the rotating shaft 2 passes. The pulse encoder 3 includes a fixed slit plate 7 fixed to the inner surface of one side ii6 of the frame 4 and a rotating shaft 2.
A rotating slit plate 8 is fixed to the rotary slit plate 8, and a light emitting element group A is disposed on the inner surface of the other end plate 9, and a light receiving element group B is disposed on the outer surface of the one end plate 6.

As shown in FIG. 6, the rotating slit plate 8 has slit rows 1 for A phase and B phase formed around the entire circumference near its outer periphery.
0, in addition to having one Z-phase slit 11 formed inside this slit row 10 and located on the base line R in the radial direction,
It has a magnetic pole detection pattern formed with or without slits. That is, this magnetic pole detection pattern has the slit 11
It consists of a 90° circular arc slit 12A that is located inside the base line R and extends from the base line R, a 90° circular arc slit 12B that is formed symmetrically with the circular arc slit 12A with respect to the center O, and a non-slit portion between both circular arc slits. .

As shown in FIG. 7, the fixed slit plate 7 has an A-phase slit row 10A and a B-phase slit row 1 formed near its outer periphery.
0B, one Z-phase slit 112 formed inside the slit rows 10A and 10B and located on the radial base line R;
One U-phase slit 130 located inside this Z-phase slit 11Z and on the base line R, this U-phase slit 13U
■ phase slit 13V located 60° apart from this ■
It has a W-phase slit 13W located 60° apart from the phase slit 13V.

The light emitting element group A includes light emitting elements for A phase and B phase located at a position where light can be emitted to the slit row 10, and a light emitting element for Z phase located at a position capable of emitting light to the slit 11. It consists of six light projecting elements for the U phase, the light projecting element for the ■ phase, and the light projecting element for the W phase, arranged at intervals. In addition, the light receiving element group B includes light emitting elements for the human phase and B phase, a light emitting element for the Z phase, a light emitting element for the U phase, a light emitting element for the ■ phase, and a light emitting element for the W phase. Rotating slit plate 8 for each
, consisting of six light-receiving elements located at opposing positions with a fixed slit plate 7 interposed therebetween.

In this configuration, the A-phase light receiving element receives light from the A-phase light projecting element that has passed through both the slit row 10 and the IOA, and the B-phase light receiving element receives light from the A-phase light projecting element that has passed through both the slit row 10 and the IOA. The light receiving element for Z phase receives the light from the Z phase light projecting element that has passed through both the slit 11 and IIZ. In addition, the light receiving element for the U phase receives the light from the U phase light emitting element that has passed through the circular arc slit 12A, the circular arc slit 12B and the U phase slit 13U, and the light receiving element for the ■ phase receives the light from the circular arc slit 12A. 12A, arc slit 12B and V phase slit)
Receives the light from the V-phase light projecting element that transmits 13V, and
The Japanese light receiving element receives the light from the W-phase light projecting element that has passed through the circular arc slit 12A, the circular arc slit 12B, and the W-phase slit 1-13W. The outputs U, VSW of the light receiving elements of the U, V, W combination are subjected to signal processing, and the magnetic pole position signals PU, Pv, P1. It is converted to l. P2 is Z
This is the output of the phase light receiving element.

[Problem to be solved by the invention]

In this way, in the conventional model, the magnetic pole detection pattern is formed in the form of a slit, so the fixed slit plate 7
．． There is a problem in that the cost of the one-turn slit plate 8 is high, and the pulse encoder is correspondingly expensive.

The present invention has been made to solve this problem, and an object of the present invention is to provide an optical pulse encoder that can extract pulses for magnetic pole detection and can be obtained at a lower cost than conventional ones. .

[Means to solve the problem]

In order to achieve the above object, the present invention provides an optical pulse encoder that has a rotating slit plate or a pair of a rotating slit plate and a fixed slit plate, a light emitting element and a light receiving element, and is attached to an AC motor. A magnetic pole detection pattern is formed on the surface of the plate, and this magnetic pole detection pattern is a pattern in which an even number of bright areas and dark areas are alternately continuous in the circumferential direction. The structure is such that three reflective optical sensors of W additive are sequentially arranged at predetermined intervals in the circumferential direction.

In claim 2, the pattern is formed by a sheet attached to a rotating slit plate; in claim 3, the pattern is formed by applying paint; and in claim 4, the rotating slit plate is formed by a metal plate. , the pattern was formed by plating.

[Effect]

In the present invention, the reflected light from the bright part of the magnetic pole detection pattern is
When the light starts to enter the phase reflective optical sensor, the optical sensor turns on and its output U becomes rH.

level. When the rotary slit plate rotates by a predetermined angle and a dark area begins to enter the field of view of this optical sensor, the optical sensor is turned off and its output becomes the "L" level. ■
The reflective optical sensor for the phase and the reflective optical sensor for the W phase perform the same output operation with a delay of a certain angle.

Since the magnetic pole detection pattern is formed of non-slit bright areas and dark areas, the cost of the rotating slit plate and the fixed slit plate can be reduced.

〔Example〕

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

In FIG. 1, reference numeral 20 denotes a rotating slit plate, which includes the same A-phase and B-phase slit arrays 10 provided on the aforementioned rotating slit plate 8, and is formed inside this slit array 10, with a base line R in the radial direction. One Z-phase slit 11 is formed at the top, and a circular sheet 30 is attached to the surface of the end plate 9 side.

The surface of this sheet 30 has two bright areas (high reflectance areas) W.
h and two dark areas (low reflectance areas) Bk form a magnetic pole detection pattern that alternately continues in the circumferential direction. That is, sheet 3
The surface of 0 is divided into four sections at 90° intervals, one opposing portion being a bright portion wh, and the other opposing portion being a dark portion Bk.

A fixed slit plate 40 is provided with the same A-phase slit array lOA, B-phase slit array 10B, and Z-phase slit 11C as those provided on the fixed slit plate 7 described above.

Three reflective optical sensors 50 for U, V, and W phases are arranged on the inner surface of the end plate 9 at intervals of 60° in the circumferential direction (on concentric circles) so as to be able to irradiate the sheet 30. has been done.

Note that the light projecting element group A in this embodiment has a slit row 10.
The light receiving element group B consists of a light emitting element for the A phase and B phase, which is located at a position where it can emit light to the slit 11, and a light emitting element for the Z phase, which is located at a position where it can emit light to the slit 11. , a B-phase light receiving element, and a Z-phase light receiving element.

In this embodiment, when the reflected light from the bright portion W of the sheet 30 begins to enter the U-phase reflective optical sensor 50, the optical sensor 50 is turned on and its output U becomes the rHJ level. When the rotary slit plate 20 rotates 90 degrees and the dark area Bk begins to enter the field of view of the optical sensor 50, the optical sensor 50 goes to 0FFL and its output U goes to the "L" level. During this 90' rotation (rotated by 60°), the reflected light from the bright portion W of the sheet 30 begins to enter the V-phase reflective optical sensor 50, so the output v of the optical sensor 50 becomes rH, level. An additional 30 degrees from the above 90° rotation
When rotated by °, the reflected light from the bright part W of the sheet 30 starts to enter the W-phase reflective optical sensor 50, so the output W of the optical sensor 50 becomes r HJ level, and at the same time,
■The dark area Bk begins to enter the field of view of the reflective optical sensor 50 for the phase, the optical sensor 50 turns OFF, and the output ■
Becomes L level.

Therefore, the waveform time chart of the outputs U, V, and W is the same as the waveform time chart shown in FIG. It can be taken out.

In the above embodiment, the magnetic pole detection pattern is formed by the sheet 30, but it may also be formed by applying light and dark color paint to the rotating slit plate 20. Alternatively, a metal plate may be used as the rotating slit plate 20. In this case, the bright portion wh may be left as the base metal plate, and the dark portion Bk may be formed by plating using a plating material with low reflectance.

As described above, in the above embodiment, the magnetic pole detection pattern is formed on the surface of the rotary slit plate 20 with different reflectances without slits. , the fixed slit plate 40 can be manufactured at low cost.

Furthermore, in the embodiment described above, since the reflective optical sensor 50 is used for the magnetic pole detection pattern, the number of required optical elements can be reduced compared to the conventional one.

In the above embodiment, the rotating slit plate 20 and the fixed slit plate 400 pairs are used, but as shown in FIG.
If a two-phase sensor module 60 is used,
Since the fixed slit plate 40 is not required, the structure is further simplified.

〔Effect of the invention〕

As explained above, the present invention has the following features:
Since the magnetic pole detection pattern is formed by forming non-slit bright and dark areas, the magnetic pole detection pattern can be formed at a lower cost than when using slits. The price can be lowered and the number of optical elements required can be reduced.
It also makes handling the wiring easier.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of the present invention, Fig. 2 is a plan view of a rotating slit plate in the above embodiment, Fig. 3 is a plan view of a fixed slit plate in the above embodiment, and Fig. 4 is a plan view of the invention. 5 is a side view of a conventional pulse encoder, FIG. 6 is a plan view of the rotating slit plate in the conventional example, and FIG. 7 is a plan view of the fixed slit plate in the conventional example. , and FIG. 8 is a waveform time chart of the magnetic pole detection pulse of the above-mentioned conventional example. 20 - Single rotation slit plate, 30 - Sheet, 40 - Fixed slit plate, 50 - Reflective optical sensor, wh - Bright part of magnetic pole detection pattern, Bk - Dark part of magnetic pole detection pattern, A
- Light projecting element group, B- Light receiving element group. Patent applicant Kami-mii-ki Co., Ltd.

Claims (4)

[Claims] (1) A rotating slit plate or a pair of a rotating slit plate and a fixed slit plate, a light emitting element and a light receiving element, and an AC
In the optical pulse encoder attached to the motor, a magnetic pole detection pattern is formed on the surface of the rotating slit plate. An optical pulse encoder characterized in that three reflective optical sensors for U, V, and W phases that irradiate light toward a detection pattern are sequentially arranged at predetermined intervals in the circumferential direction. (2) The optical pulse encoder according to claim 1, wherein the pattern is formed of a sheet adhered to a rotating slit plate. (3) The optical pulse encoder according to claim 1, wherein the pattern is formed by applying paint. (4) The optical pulse encoder according to claim 1, wherein the rotating slit plate is formed of a metal plate, and the pattern is formed by plating.