JPS62277818A - Rotary encoder - Google Patents

Abstract

PURPOSE:To simplify the constitution, miniaturization and low cost by constituting the titled rotary encoder with an INC encoder having a sufficient split number for the sinusoidal wave drive and an ABS encoder generating a signal having an enough split number to drive various servo motors without any reaction torque. CONSTITUTION:The totary encoder consists of the incremental (INC) encoder 5 having an enough split number for sinusoidal wave drive and an absolute (ABS) encoder generating a signal having an enough split number to drive various servo motors without any reaction torque. Further, the ABS encoder consists of a rotary disk 10 processed easily and six position detectors 9, and the detectors 9 are arranged at an electric angle in reponse to number of poles of a motor while the mutual interval of the detectors 9 is parted sufficiently. Thus, a drive signal is generated from the ABS encoder at the initial start of a servo motor and a position signal from the INC encoder is used as a motor drive signal at the generation of a zero signal of the INC encoder, then miniaturization is attained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the rotational position of a 2P pole (P is an integer of 1 or more) 3-phase brushless motor (3-phase AC servo motor). The present invention relates to a rotary encoder suitable for detection.

[Conventional technology]

When detecting the rotational position of a three-phase AC servo motor, not only a position detection signal of the workpiece but also a position detection signal for driving the motor is required.

The position detection signal for motor drive requires a large number of divided signals per rotation in order to make the drive current waveform a sine wave with little distortion, and must also provide absolute position information with respect to the motor coil. .

Therefore, a resolver or an absolute (hereinafter abbreviated as ABS) encoder has been used as a position detector.

[Problem that the invention seeks to solve]

However, resolvers and ABS encoders have the following drawbacks. In other words, a resolver requires a signal processing circuit including a resolver-to-digital converter that converts the analog signal of the resolver into a digital signal as position information, but the presence of this signal processing circuit complicates the configuration of the device. And it is expensive. Also A
In a BS encoder, as the number of divided signals increases, the external size becomes larger, and the number of detection elements and signal lines also increases.

In addition to increasing the size of the device, it is also expensive like a resolver.

On the other hand, an incremental (hereinafter abbreviated as INC) encoder has a relatively simple processing circuit, does not have a large external size, and is very advantageous in terms of cost.

However, since the signal obtained is not an absolute position signal, a problem arises in this respect. That is, during steady rotation, counting is performed based on the zero signal (built into the INC encoder), so no particular problem occurs, but a problem occurs during initial startup. For this reason, some INC encoders have a built-in battery, counter, etc. to memorize the absolute position, but considering the battery life, the main advantage of AC servo motors, which is maintenance-free characteristics, cannot be maintained. .

Therefore, the present invention has a simple configuration, can be manufactured in a small size and at low cost, can easily obtain absolute position information, can perform initial startup without any trouble, is easy to maintain, and can be used to position a three-phase AC servo motor. It is an object of the present invention to provide a rotary encoder that is extremely suitable for detection.

[Means for solving problems]

In order to solve the above-mentioned problems and achieve the object, the present invention takes the following measures. That is, a rotary encoder is constructed by an INC encoder having a sufficient number of divisions for sine wave driving and an ABS encoder that generates a signal having a division number sufficient to drive various servo motors without counter torque.

The ABS encoder consists of a rotary plate that is easy to work with and six position detectors. Each position detector has an electrical angle position that corresponds to the number of poles of the motor, and the distance between each detector is sufficient. It is desirable to use one that is arranged to open.

[Operation] By taking such measures, a drive signal is generated from the ABS encoder at the initial startup of the servo motor,
Since the position signal from the INC encoder becomes the motor drive signal from the time when the zero signal of the INC encoder is generated, a small and inexpensive rotary encoder for an AC servo motor can be obtained.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the present invention.

As shown in the figure, bearings 4a and 4b for supporting a rotating shaft 3 are press-fitted into the bottom wall of a case 1 and a lid 2 of the encoder body, respectively. The dotted line section 5 is an INC encoder, which outputs two-phase pulses divided into many parts as the rotating shaft 3 rotates, and zero signal pulses generated at a rate of one pulse per rotation. The fixed side of the INC encoder 5 is case 1. It is fixed to the inner surface of the lid 2 or to the substrate 6.

, 7 is the thrust direction (horizontal direction in the figure) and the N-8 pole is 11.
The magnets 1 to 1 serve as position detector components, and are fixed on a cylindrical yoke 8 disposed over the inner surface of the bottom wall and the inner surface of the peripheral wall of the case 1. The yoke 8 and the substrate 6, which is partially coupled to the end of the yoke 8, are both made of ferromagnetic material so as to form a magnetic path for the magnet 7. On the surface of the substrate 6 facing the magnet, an etched copper foil is adhered via an e11 layer. On this copper foil, 6 g of magnetic sensors 9 as position detector components are disposed in the circumferential direction.

A rotary plate 10 is fixed via a mounting member 11 so as to be interposed between the magnetic sensor 9 and the magnet 7,
It rotates integrally with the rotating shaft 3. The rotating plate 1o is made of a ferromagnetic material such as a rust-proofed steel plate, and has a notch in its outer circumference as described later. This changes the magnetic resistance of the magnet. The magnetic sensor 9 detects this change in magnetic resistance and outputs it as an electrical signal. The placement positions of the six sensors 9 and the notch width of the rotary plate 10 differ depending on the number of motors coupled to the rotary shaft 3. In the following description of this embodiment, a case will be described in which the connected AC servo motor has four poles.

FIG. 2(a) is a plan view of the rotary plate 10. Convex portion 10a
, 10c, and the opening angles of the recesses 10b and 10d are each 900
, which corresponds to 180° in electrical angle. Symbol 10e is a hole for fitting the mounting member 11.

FIG. 2(b) is a plan view of the substrate 6 viewed from the magnet side. 5a, 6b, and 6c are mounting holes for mounting on the yoke 8. 9a to 9f are magnetic sensors, each having an alternating opening angle of 45°.

75' (1! 906.150° in air angle).

FIG. 3 is a diagram showing the relative positions of the rotary plate 10 and the magnetic sensor 9 when the rotary plate 10 rotates in the direction of the arrow in FIG. 2(a). That is, FIG. 3 is a diagram in which the rotating plate 10 and each sensor 9a to 9f are expanded in the rotation direction, and FIG. 2 (a>,
This is the arrangement when facing each other at the position shown in (b). Each sensor 9
a to 9f are hatched convex portions 10a and IO of the rotary plate 10;
When facing C, it outputs an H level signal, and the recess 10b.

When facing 10d, it outputs an L level signal.

The rotating plate 10 moves (rotates) in the direction of the arrow from the illustrated position.
Then, the boundaries between the convex portions and the concave portions at four locations face one of the sensors 9a to 9f every 15''<300 electrical angles.Therefore, each sensor 9a to 9f detects the change in magnetic flux at this time. , the output signal has the H and L levels inverted.

FIG.
60') Shows the output of each sensor when moving. In FIG. 4, waveforms 12a-12f correspond to sensors 9a-9f. As shown in the figure, the signal (
gray signal), so no erroneous signals are generated when performing waveform conversion. From waveforms 12a to 12f, electrical angle ○
Twelve types of signals can be discriminated between 360° and 360°.

Waveform conversion is performed to convert these signals into driving position signals when starting the motor. In this case, there are two methods: one is to directly generate a motor drive signal (120° or 180° energization signal), and the other is to generate the upper bits of a binary signal formed from the two-phase pulses of the INC encoder 5.

Signal waveforms 138 to 13d in FIG. 5 represent the latter signal waveforms. Further, signal waveforms 13c, 13d, and 13e are the waveforms of the former 120' energization signal. These waveforms are R
Obtained by OM or simple logic circuits. To show an example of the case obtained by a logic circuit, signal waveform 1
Logical variables corresponding to 2a to 12f are set to P1 to P6. If the logical variables corresponding to signal waveforms 138 to 13e are Q1 to Q5, the logical formula is Q2 = P1 - Ps + P3 · Ps +
Ps 弗 PIQ3-Ps · Ps Q4 - Pi · Ps Qs - Ps · Pi (However, ■: Exclusive OR). Therefore, it is sufficient to construct a logic circuit that satisfies the above equation.

As described above, the electric angle 30
An absolute position signal is obtained every '.

In this way, the minimum absolute position information necessary for starting the motor is obtained, so the motor started at the same time as 1 ml is injected is operated by the ABS encoder until a zero signal is obtained at the INC encoder 5. And IN
When a zero signal is generated from the c encoder 5, sine wave driving is performed based on the information received from the two-phase signal of the INC encoder 5, and a steady operating state is established. Note that when performing trapezoidal wave driving instead of sine wave driving, the ABS
It can also be driven directly using only the information from the encoder.

By the way, as for the arrangement opening angle of the magnetic sensors 9a to 9f for position detection, as mentioned above, in the case of a three-phase motor, basically it is sufficient to arrange six pieces at intervals of 30 degrees in electrical angle, and the necessary information can be grayed out. Obtained by signal. That is, if the number of poles of the motor is two, the number of poles may be 306, and if the number of poles is four, the number of poles may be arranged at 15° intervals. "However, in order to make the encoder more compact, it is better to have the opening angle of each sensor as large as possible, and it is easier to achieve accuracy. Therefore, in the configuration of the present invention, the opening angle of each sensor should be around 60" or more than 60". The phase transition of the sensor is performed so that

This is because the same position signal can be obtained even if the opening angle increases or decreases by the notch angle of the rotary plate 1o.

If the motor has 4 poles, the opening angles are 45° and 60°.

The arrangement can be performed at four different opening angles: 75° and 75° or more. In the example shown in Figure 2(b), 75°, 456
The necessary signal is obtained by alternating the opening angle of 4.
Other arrangement examples (modifications) of sensor arrangement in the case of poles will be described below.

FIG. 6(a) shows the magnetic sensors 14 (14a to 14f).
) (M; f! Angle wo, lL are respectively 45° and 60'.

In this example, the angles are 600.75°, 60', and 60°, and the outputs of the sensors 14a to 14f are the waveforms 12a and 12a in FIG.
12f, 12d, 12b, 12e, and 12C (however, the outputs of the sensors 14b to 14d are inverted). Further, FIG. 6(b) shows the magnetic sensor 15 (15a to l5
f) opening angles of 45', 60', 45°, and 6, respectively.
0' 45°.

1056, and the output of each sensor 15a to 15f is the waveform 12a, 12f, 12d, 12e,
12c, 12b (however, the outputs of the sensors 15b to 15e are inverted). Therefore, the desired signal can also be obtained with the sensor arrangement shown in FIGS. 6(a) and 6(b).

Next, the case of connecting to a motor other than the four-rod motor will be explained.

7(a) and 7(b) are diagrams showing a second embodiment in which the motor has six poles, and FIG. 7(a) is a plan view of the rotary plate 20, and FIG.
b) shows the arrangement of the magnetic sensor 21. Figure (a)
The rotating plate 2o shown in FIG. 2(a) corresponds to the rotating plate 10 in FIG.
) A notch is provided for each. As shown in the same figure (b),
The five opening angles between the sensors 21a to 21f are each 50''.The outputs of the sensors 21a to 21f have waveforms 12a, 12b, 12e, and 12f in FIG. 4, respectively.

12C, 12d <However, the outputs of the sensors 21c and 21d are inverted), and the absolute position information necessary for starting the motor can be obtained as in the case where the motor has four poles.

8(a) and 8(b) are diagrams showing a third embodiment in which the motor has eight poles, and FIG. 8(a) is a plan view of the rotating plate 30, and FIG.
b) shows the arrangement of the magnetic sensor 31. Figure (a)
The rotary plate 30 shown in FIG. 2 corresponds to the rotary plate 10 in FIG.
A notch is provided for each. As shown in FIG. 3(b), the opening angle between each sensor 31a to 31f is 52.5°, 67°.
5' are alternated. The outputs of the sensors 31a to 31f have waveforms 12a and 12f in FIG. 4, respectively.

12e, 12d, 12c, and 12b, and necessary absolute position information can be obtained. In the case of 8 poles, see Figure 8 (1))
Absolute position information can also be obtained with sensor arrangements other than the above.

FIG. 8(c)<d) shows an example (modified example) of the sensor arrangement. That is, FIG. 8(C) shows that each sensor 32a to 32
This is an example in which the opening angle between f is 52.5°, and each sensor 3
The outputs of 2a to 32f are waveforms 12a, 12d, and 12d in FIG.
12c, 12f.

12e, 12b (however, sensors 32b, 32c).

The output of 32f is inverted). Also, Figure 8 (d
) 'each opening angle between each sensor 33a to 33f is 52.
5°, 60', 52.5°.

5265°, 67.5', and 75', and the outputs of the respective sensors 33a to 33f are waveforms 12a and 12' in FIG.
12d, 12f, 12e, 12b, and 12C (however, the outputs of the sensors 33b to 33d and 33f are inverted).

As mentioned above, if the corresponding motor has 2 P poles (P is a positive integer), cutouts are provided in the rotary plate every 180°/P (II electrical angle 1806), and six sensors facing each other are provided. Basically, the sensors are spaced apart by 30'/P (30 degrees in electrical angle) and have a phase transition of 0 times (n x 180 degrees/P in mechanical angle, n x 180 degrees in air angle).
, n is an integer and O≦n<2P>, and the opening angle of 6 lines is 60
By arranging the encoder so that the angle is '-30°/P, 60°, 60'+30''/Pt or more, it is possible to reduce the diameter of the encoder and generate a gray signal that does not generate an error signal.

By detecting the position of the AC servo motor using the rotary encoder of the above-described embodiment, high-resolution position information can be obtained during steady operation, and the inconvenience of waiting for startup can be solved by using a simple absolute position detection means. Further, since a complicated signal processing circuit or the like is not required, the rotary encoder becomes small and inexpensive.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, a magnet and 6
Although we used several magnetic sensors, it is sufficient to detect changes in the physical characteristics of the rotary plate 10. For example, if the rotary plate 10 is a plate with optical shading, a photocoupler or the like may be used as the sensor. Bye. Further, when the rotating plate 10 is a metal plate such as aluminum, a proximity switch using an air-core coil or the like may be used as the sensor. These may be selected as appropriate depending on the corresponding environment.

It goes without saying that various other modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, a rotary encoder is configured by an INC encoder having a sufficient number of divisions for sine wave driving and an ABS encoder that generates a signal having a division number sufficient to drive various servo motors without counter torque. It has a simple configuration, can be manufactured compactly and at low cost, can easily obtain absolute position information, can perform initial startup without any trouble, and is easy to maintain, making it extremely suitable for position detection of 3-phase AC servo motors. We can provide a rotary encoder with a wide range of functions.

[Brief explanation of the drawing]

Figures 1 to 6 (a) and (b) are diagrams showing a first embodiment of the rotary encoder of the present invention, in which Figure 1 is a cross-sectional view, Figure 2 (a> is a plan view of the rotary plate, Fig. 2(b) is a layout diagram of magnetic sensors for position detection, Fig. 3 is a plan development view showing the relative position of the rotary plate and the magnetic sensor, Fig. 4 is an output waveform diagram of each magnetic sensor, and Fig. 5 6(a) and 6(b) are diagrams showing a modified arrangement of the magnetic sensor. FIG. 7(a>(b) is a diagram showing a second embodiment of the present invention. 8(a) is a plan view of the rotating plate, and FIG. 8(b) is a layout diagram of the magnetic sensor. (a) is a plan view of the rotating plate, (1)) is a layout diagram of the magnetic sensor, and (c>
(L is a modified layout diagram of the magnetic sensor. 1... Case, 3... Rotating shaft, 5... INC encoder, 7... Magnet, 8... Yoke, 10,
20°30... Rotating plate, 9 (9a to 9f), 14
(14a-14f), 15 (15a-15f)
, 21 (21a to 21f), 31 (31a to 3
1f>. 32 (32a ~ 32f), 33 (33a ~
33f)...Magnetic sensor for position detection. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 et al. (a) (b) Figure 9 Figure 5 (a) (b) (a) (b) Figure 7 (a) (C) Figure 8r (b) et al (d)

Claims (2)

[Claims] (1) In a rotary encoder connected to a 2P pole (P is an integer greater than or equal to 1) three-phase brushless motor, there is an encoder body, a rotating shaft supported by a bearing provided in the case of the encoder body, and coupled to the motor. , an incremental encoder mounted on the rotating shaft, an absolute encoder installed coaxially with the incremental encoder and outputting 12 types of position signals every 1/P rotation of the rotating shaft, and a predetermined position signal. 1. A rotary encoder comprising: signal converting means for converting into a signal of a different format. (2) The absolute encoder includes a rotating plate that is attached to the rotating shaft and whose physical characteristics change alternately every 180°/P.
In order to detect changes in the physical characteristics of this rotating plate, a
+6n) x 30°/P (m and n are each integers, 0≦m
≦5, 0≦n<2P), and at least 5 of the 6 adjacent opening angles are 60° or 60°.
2. The rotary encoder according to claim 1, further comprising six position detectors arranged opposite to said rotary plate at positions of ±30°/P.