JPH08122096A - Rotary encoder - Google Patents

Abstract

PURPOSE: To obtain an A/B phase signal pulse output having a very wide variation regardless of the decimal series, the binary series by one rotary encoder. CONSTITUTION: First, second and third tracks are formed on a scale 2 so that the difference of reproduced wave number per one revolution of the motors of the first and second tracks is 3*M (where M is integer except '0'). The generating timing of three phase synchronous signals is decided by a pulse forming circuit 47 by using a beam signal pulse corresponding thereto, and the logic state of the three phase signal is decided by using the demodulation signal of the recorded pattern of the zones divided corresponding to the 3*M recorded on the third track.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder most suitable for an AC servomotor used for position control and speed control of machine tools or industrial machines.

[0002]

2. Description of the Related Art Most of machine tools, industrial machines and the like (hereinafter referred to as machines) that require linear motion rely on a servomotor for the driving force, and the maximum speed and the required speed of the machine are required. Resolution with the number of rotations of the servo motor,
Ball screw pitch and A / B per rotation of the rotary encoder built into the servo motor
It is realized by combining the number of phase signal pulses (hereinafter referred to as A / B phase pulse number). Generally, the pitch of the ball screw is first determined by the maximum speed required for the machine and the maximum rotation speed of the motor. Then, the number of pulses of the A / B phase signal per one rotation of the rotary encoder incorporated in the servo amplifier is determined according to the required linear resolution.

[0003]

For example, the maximum speed required for the machine is 12 m / min, and the number of revolutions of the available servo motor (from horsepower, torque, etc.) is 3000 r.
If pm, it is necessary to use a ball screw having a pitch of at least 4 mm, and further, to obtain a linear resolution of 1 μm, it is necessary to use an encoder of 4000 pulses / rotation.

On the other hand, an amplifier for driving a servo motor (hereinafter referred to as a servo amplifier) has a built-in integrating circuit for integrating the pulses from the rotary encoder to obtain the current position, and thus the number of parts is small. Since a large number of pulses are counted by the number of points, it may be composed of a binary type integrating circuit. Due to the convenience of a servo amplifier, a ball screw having a pitch corresponding to the binary number and a rotary encoder of a binary series, the above example. However, a ball screw of 4.096 mm and a rotary encoder of 4096 pulses were sometimes required.

Therefore, in order to meet the market needs such as the maximum speed required for the machine, the number of rotations of the motor, the pitch of the ball screw that can be used, the required resolution, etc., the decimal series and the binary series are very important. It was necessary to prepare many variations, which were handled as follows. (1) One recording head corresponds to a plurality of scale media (hereinafter, referred to as drums) having the same reproduction wavelength and different wave numbers according to the number of A / B phase pulses of the rotary encoder. (2) One drum in which the reproduction wavelength is changed according to the required wave number and a plurality of recording heads corresponding to the wavelength are used. (3) Furthermore, by combining the above (1) and (2), the variations in drum diameter and recording head are optimized. According to the above-mentioned method of handling, the number of parts and the management man-hours cannot be increased, resulting in an increase in cost and a longer delivery time.

[0006] Recently, A which is excellent in maintenance
C Servomotor becomes the main force, and 3 for synchronizing the rotational position of the servomotor with the three-phase signal for driving the servomotor.
There has been an increasing demand for rotary encoders having phase synchronization signals.

In order to meet such a demand, a track for the A / B phase signal and a track for the three-phase synchronizing signal are separately provided, and a detection circuit for them is combined to realize them. Various variations of the number of phase synchronization signal pulses (hereinafter referred to as the number of synchronization signal pulses) may be required depending on the number of poles of the motor. The number of variations is increasing, and the cost is increased due to the further increase in the number of parts and management man-hours.

[0008]

The present invention has been made to solve the above-mentioned inconvenience, and the relative movement amount between the drum and the head is taken out as a change in the phase of the phase modulation signal to change the phase. The basic principle is a phase detection type displacement detection device that detects the amount of movement by detecting the amount,
(1) Supports both A / B phase pulse output of binary series and decimal series, and (2) Accurate 3 corresponding to rotational position.
(3) A rotary encoder capable of generating a phase synchronization signal and (3) an origin pulse synchronized with the three-phase synchronization signal.

As an example of the configuration of the displacement detecting device of the present invention, the following configuration can be adopted. That is, the rotary encoder of the present invention is provided with the first and second tracks having a relationship of 3 * M (where M is an integer other than 0) in the difference in the number of reproduced waves per rotation, and the first track is The number of pulses corresponding to a decimal number is 2 for the second track.
The number of pulses corresponding to the base number is recorded, and the pulse corresponding to the difference 3 * M between the reproduction wave numbers of the first and second tracks (hereinafter referred to as the beat signal pulse) is used to generate the three-phase synchronization signal. Is determined and the logical state of the three-phase signal is determined using the demodulated signal of the recording pattern of the zone divided corresponding to 3 * M recorded on the third track.

Further, the rotary encoder of the present invention multiplies the phase modulation signals from the first and second tracks and responds to the difference in the number of pulses of the first and second tracks by the low frequency component thereof. It is preferable that the beat signal is obtained. Further, the rotary encoder of the present invention waveform-shapes the phase-modulated signals from the first and second tracks, and compares the signals digitally in phase to determine the number of pulses of the first and second tracks. It is preferable to obtain the beat signal corresponding to the difference. Further, in the rotary encoder of the present invention, the recording pattern of the third track is recorded as a signal having the same reproduction wavelength or the same reproduction wave number as the first or second track and having a different phase for each zone. It is preferable that the demodulated signal is extracted in the form of phase modulation and compared with the phase modulated signal obtained from the first or second track to form a demodulation signal that specifies the zone. Furthermore, the recording patterns of the third track are each 3
Detecting the signals of the first and second tracks in the form of phase modulated signals, comprising four blocks including one zone, the recording pattern of the third track including a pattern that appears only once per motor revolution. However, it is preferable to be configured so as to be able to cope with the pulse output of the decimal series and the binary series by switching this signal.

[0011]

The rotary encoder of the present invention has the following operational advantages by having the above-mentioned configuration. (1) Since one rotary encoder has recording tracks for two series A / B phase signals of decimal and binary, and the number of divisions of the interpolation circuit can be easily changed, one rotary encoder is provided. The encoder can cope with a very wide A / B phase signal pulse output variation regardless of decimal or binary series. Therefore, the number of parts and the manufacturing control man-hour can be reduced,
The cost and delivery time can be shortened. (2) Since the three-phase synchronization signal for generating the three-phase signal for driving the AC servo motor is obtained from the above-mentioned two-series recording tracks, the accuracy is determined by the recording accuracy of the above-mentioned two-series recording tracks. The adjustment determines the pulse width and relative positional relationship of the three-phase synchronizing signal. Therefore, there are few variations in the manufacturing stage, the number of management steps can be reduced, and the cost can be reduced. (3) Since the generation position of the three-phase synchronization signal can be electrically adjusted, a complicated adjustment mechanism when connecting to the motor is not required, and simple and accurate phase adjustment is possible, and quality and cost can be improved. . (4) The number of pulses of the three-phase synchronization signal can be easily changed by a recording pattern of the third recording track or a circuit for demodulating the recording pattern of the third recording track. It can easily accommodate expansion.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the present invention is applied to a magnetic rotary encoder will be described with reference to the drawings. Here, the number of reproduction pulses of the encoder is assumed as follows. a, synchronization signal pulse ... 4 pulses / revolution b, origin signal pulse ... 1 pulse / revolution c, decimal sequence A / B phase pulse number ... 2,000 pulses / revolution d, binary sequence A / Number of B-phase pulses: ... 2,048 pulses / revolution

However, when a magnetoresistive effect element (hereinafter referred to as an MR sensor) is used as a detection head of a magnetic rotary encoder, depending on the construction method, it is 1/2 times the recording wavelength, that is, 2 times the recording wavelength. Although the doubled wave number may be obtained, here, the wavelength of the reproduction signal is defined as the effective wavelength, and in the following description, explanation will be given using this reproduction wavelength. No particular mention is made of the recorded wave number.

FIG. 10 shows a magnetic drum 1 according to the present invention.
2 shows the relationship between the scale 2 formed on the magnetic drum 1 and the magnetic head 3 for detecting the signal of each recording track on the scale 2. As shown in an enlarged view in FIG. 11, three tracks are formed on the magnetic scale 2. The first track 21 has a magnetic scale having an effective wavelength λ1 of 500 pulses, and the second track 22 has an effective magnetic scale. The magnetic scale of wavelength λ2 is recorded for 512 pulses. Further, on the third track 23, a magnetic scale having a recording wavelength of λ1 or λ2 and a phase different depending on the rotational position is recorded, which will be described later.

FIG. 1 shows the entire structure of a rotary encoder according to the present invention, which is composed of a scale 2, a magnetic head 3, and detection circuit portions 4A and 4B. The magnetic head 3 is composed of a first track detecting head 31, a second track detecting head 32, and a third track detecting head 33 corresponding to each track of the magnetic scale. For example, an MR sensor or the like is used. . Here, although each head is shown to be composed of one element, it is actually composed of a plurality of elements.

Next, the circuit section will be described. This section is composed of an A / B phase pulse generator 4A and a three-phase sync signal and origin signal generator 4B. Therefore, first, the A / B phase pulse generator 4A will be described. The phase detection circuit 1 (41) and the phase detection circuit 2 (4 shown in FIG.
In 4), the circuit configuration is exactly the same except that the input signal is a signal of wavelength λ1 or a signal of wavelength λ2, and the details thereof are shown in FIG. 2 and will be described later.

The signal S1 from the phase detection circuit 41 and the signal S2 from the phase detection circuit 44 are supplied to the input of the switching circuit 42, and one of them is passed to the interpolation circuit 43. The interpolation circuit 43 is a phase detection type interpolation circuit, and for example, the interpolation circuit described in Japanese Patent Publication No. 50-7226 is used.

Now, the phase detection circuit will be described with reference to FIG. The phase detection circuit described here is shown in FIG.
2 shows in detail the circuits shown by the phase detection circuits 1, 2, and 3. Since these detection circuits have the same structure, they will be collectively described.

The detection head 31 in FIG. 1 is composed of two heads 31a and 31b in FIG. An excitation signal is applied to these two magnetic heads, and this signal is used as a carrier signal for detection by modulating it. In the figure, the magnetic heads 31a,
As the excitation signal of 31b, a rectangular wave of frequency f and an EX signal are converted into a sine wave through the low pass filter 41f, and then the magnetic heads 31a and 3 are passed through the excitation amplifier 41g.
It is applied to 1b.

Since the magnetic heads 31a and 31b are arranged so as to be electrically separated by 90 degrees with respect to the reproduction wavelength λ1 of the scale, the CH1 preamplifier 4 is used.
From 1a and CH2 preamplifier 41b, a signal represented by the following equation is obtained. CH1 preamplifier output ...... sin ωt * cos (2πx / λ1) ・ ・ ・ (1) CH2 preamplifier output ・ ・ ・ sin ωt * sin (2πx / λ1) ・ ・ ・ (2) where ω = 2πf, x It is the amount of movement within the wavelength λ1 (the amount of movement on the circumference).

The CH2 output is added to the summing amplifier 41d after the carrier phase shift is changed by 90 degrees by the 90 degree phase shifter 41c.
, Sin {ωt + (2πx / λ1)} ... (3) is output to the output of the adding amplifier 41d.

This signal is supplied to the waveform shaping circuit 41e, converted into a rectangular wave there, and output as the signal S (where S is the signal S1 or the signal S2). Since the signals S1 and S2 are a phase detection type system, if attention is paid only to the phase, S1 = sin {ωt + (2πx / λ1)} (4) S2 = sin {ωt + (2πx / λ2)} It can be expressed as (5). That is, the phase-modulated signals S1 and S2 have a phase of 2π (360) for each movement of λ1 and λ2.
°) A phase-modulated signal that changes.

Returning to the explanation of the circuit of FIG. 1, the switching circuit 42 is a circuit for switching the phase modulation signal input to the interpolation circuit 43, and the control signal of this switching circuit is PSEL =
If the phase modulation signal S1 from the phase detection circuit 41 is input to the interpolation circuit 43 at "H", the interpolation circuit 4
3 is a clock frequency N * f which is N times the carrier frequency f of the phase modulation signal S1 and has a wavelength λ1 of 1 / N, here 1 / N.
16 is added, and 15 addition / subtraction pulses are generated for each movement of λ1.

As described above, since 500 wavelengths λ1 per rotation are recorded on the track 1, the interpolation circuit 43 generates 500 * 16 addition / subtraction pulses per rotation. As shown in FIG. 3, the addition / subtraction pulse (Up, Dn) is converted into a series of pulse trains (Up + Dn) through the pulse addition circuit 43c, and the counting direction switching circuit 43b changes the logical level according to the counting direction ( U / D), and the one-sequence pulse train (U
(p + Dn) is distributed, the flip-flops 43e and 43f are alternately toggled, and a 90-degree phase difference signal reduced to 1/4 is output. That is, from the interpolation circuit,
It is possible to output an A / B phase signal of 000 pulses.

Returning to the circuit description of FIG. 1 again, when the user switches the control signal supplied to the switching circuit 42 to set PSEL = "L", the signal from the phase detection circuit 2 is transferred to the interpolation circuit 43. Since it is supplied, 512 * 4 = 2,048 pulses are obtained at the output of the interpolation circuit. Furthermore,
It will be easily understood that a rotary encoder having an arbitrary A / B phase pulse number of a decimal series and a binary series can be realized by changing the number of interpolations of the interpolation circuit 43.

Next, the operation of the three-phase sync signal and origin signal generator 4B will be described. As the phase comparison circuit 46, for example, a circuit as shown in FIG. 9 is used, and the phase modulation signal S1 that causes a phase change of 500 * 2π per rotation is input to the CK input terminal of the D-F / F. . Therefore, as shown in FIG. 7, 12 synchronization pulses PC per rotation are obtained from the Q output terminal of the D-F / F, and this signal is input to the pulse circuit 47 (of FIG. 1). Differential pulses PG and NG synchronized with the clock pulse CK at the rising and falling edges of the synchronization pulse PC (FIG. 7)
Occurs.

The differential pulses PG and NG are output within one rotation depending on the relative phases of S1 and S2, that is, the phase relationship between the first recording track 21 and the second recording track 22 during recording. The position is automatically determined.

Therefore, as shown in FIG. 9, S1 or S2
By passing one of the phases through the variable phase circuit and then comparing the phases, it is possible to electrically change the generation positions of the differential pulses PG and NG, and it is possible to correct variations and the like during recording.

The phase detection circuit 3 (45) is exactly the same as the phase detection circuit 1 (41) and the phase detection circuit 2 (44), but as shown in FIG. 8, the third track 13 of the scale is used. One rotation is divided into 12 zones, four types of patterns (P0 to P3) having the same wavelength λ1 as the track 11 and different in phase by 90 degrees are recorded, and one of the zones is recorded. Only pattern P in one rotation
I have 0. Therefore, by comparing the phases of S1 and S2 for each cycle of the phase modulation signals S1 and S3,
The zone in which the magnetic head is located can be detected according to the recording pattern (P0 to P3), that is, the phase difference between S1 and S3.

FIG. 4 shows P for detecting the phase difference and the like shown above.
FIG. 5 shows a configuration example of the SK demodulation circuit (48) and its operation timing. The signals S1 and S3 supplied to the left end of FIG. 4 are the phase detection circuits 41 and 45 of FIG.
Signal supplied from the synchronous differentiating circuit 51.
And 52. As shown in FIG. 5, these synchronous differentiating circuits produce signals SP1 and SP3 by differentiating the rising portions of the signals S1 and S3.

The signals SP1 and SP3 are supplied to the phase comparison circuit 53, where they are compared and the signal indicated by PD in FIG. 5 is output. This signal PD opens the gate 2 and outputs the clock CK /
2 is supplied to the quaternary counter 54. This clock signal is shown as CP in FIG. The output of the quaternary counter 54 is latched by the latch circuit 55, and outputs DM1 and DM
2 is output.

On the other hand, the output of the synchronous differentiating circuit 51 is the gate 1
Is supplied to the quaternary counter 54. This signal is shown as CL in FIGS. 4 and 5 and serves to clear the counter 54. In other words, the counter 54 is cleared each time the signal CL arrives, and when the signal CP is supplied, the counter 54 adds and counts it.

Outputs DM1 and DM2 of the PSK demodulation circuit
Are supplied to the synchronizing signal generating circuit shown in FIG. In the circuit of the figure, the signals DM1 and DM2 are supplied to the decoding circuit 61, and as shown in FIG. 7, when both of these signals are "L", they become the recording pattern P0, and when they are both "H", the recording pattern P2. , "L" and "H" are recording patterns P3, "H" and "L" are recording patterns P1,
These pattern signals are applied to the JK flip-flops 62, 63 and 64, respectively, and turned on by the clock signal PG applied to the CK terminals of these flip-flops, and the signals U, V and W are output to the respective outputs Q. To do.

Each signal is also supplied to the reset pulse generating circuit 65, and the reset pulse generating circuit is supplied with the signal NG.
Is applied, the output resets the flip-flop circuit, and its outputs U, V, W are turned off. Here, among the 2-bit code signals DM1 and DM2 signals demodulated by the PSK demodulation circuit 48, DM1 = for the output from the pattern P0 unique to one rotation.
The signal generated by "L", DM2 = "L" and the signal PG generates only one pulse per one rotation and can be used as the origin signal Z.

As described above, the code signal DM1
And DM2 are input to the synchronizing signal generating circuit 49 together with the differential pulse signals PG and NG, and three-phase synchronizing signals U, V, W are generated. As shown in the operation timing chart of FIG. 7, the U signal is in zones P0 and P1.
, PG signal, V and W signals are set in synchronism with the PG signals of zones P2 and P3, respectively, U signal is set by itself, and after V signal is set, V signal is set in synchronization with NG signal and V After setting the signal and W signal,
After the signal and the U signal are set, they are reset in synchronization with the NG signal.

The signal PG and the signal NG are 1 per rotation.
Since two pulses are generated, the three patterns of the recording patterns P1, P2 and P3 are repeated four times, so that four pulses of U, V and W signals are generated in one rotation. The signals are 120 ° out of phase with each other and can be used as a three-phase synchronizing signal for driving the servo motor. Further, as described above, since the generation positions of the differential pulses PG and NG can be electrically changed, a mechanism for adjusting the mutual positional relationship when the rotary encoder is incorporated in the motor is not required,
The mutual positional relationship can be adjusted accurately and easily.

Here, it is not explained that a three-phase synchronizing signal having an arbitrary number of synchronizing pulses can be generated by changing the recording pattern for zone division or by changing the detection resolution of the PSK demodulation circuit. Ah

[0038]

According to the present invention, it is possible to obtain an A / B phase signal pulse output having a very wide variation regardless of a decimal or binary sequence with one rotary encoder. Therefore, the number of parts and the manufacturing control man-hour can be reduced,
The cost and delivery time can be shortened. Moreover, since the pulse width and relative positional relationship of the three-phase synchronization signal can be determined without adjustment, there are few variations in the manufacturing stage, the number of management steps can be reduced, and the cost can be reduced. Since the number of pulses of the three-phase synchronization signal can be easily changed, it is possible to easily deal with the expansion of the variation of the number of pulses of the three-phase synchronization signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a system configuration of a rotary encoder of the present invention.

FIG. 2 is a block diagram showing details of the phase detection circuit of FIG.

3 is a block diagram showing details of the interpolation circuit of FIG. 1. FIG.

FIG. 4 is a block diagram showing details of the PSK demodulation circuit in FIG.

5 is a waveform diagram showing an operation of the PSK demodulation circuit of FIG.

FIG. 6 is a block diagram showing details of the synchronization signal generation circuit of FIG. 1.

FIG. 7 is a waveform diagram for explaining the operation of the circuit of FIG.

FIG. 8 is a waveform diagram showing an example of a recording pattern recorded on a track 3 on the scale.

9 is a block diagram showing details of the phase comparison circuit in FIG. 1. FIG.

FIG. 10 is a schematic view showing an example of the structure of the drum of the present invention.

11 is an enlarged view of a track recorded on the drum of FIG.

[Explanation of symbols]

 2 Magnetic Scale 3 Detection Head 4A A / B Phase Pulse Generation Unit 41, 44 Phase Detection Circuit 42 Switching Circuit 43 Interpolation Circuit 4B 3 Phase Synchronization Signal and Origin Signal Generation Unit 45 Phase Detection Circuit 46 Phase Comparison Circuit 47 Pulsing Circuit 48 PSK demodulation circuit 49 Sync signal generation circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01D 5/36 K H02P 6/16

Claims (7)

[Claims] 1. The difference in the number of reproduced waves per rotation is 3 * M.
(Where M is an integer other than 0), the first and second tracks are provided, and the first track has a pulse number corresponding to a decimal number and the second track has a pulse number corresponding to a binary number. The number of recorded signals is recorded, and the generation timing of the three-phase synchronization signal is determined by using a pulse (hereinafter, referred to as a beat signal pulse) corresponding to the difference 3 * M between the reproduction wave numbers of the first and second tracks. A rotary encoder characterized in that the logical state of the three-phase signal is determined by using a demodulation signal of a recording pattern of zones divided corresponding to 3 * M recorded on three tracks. . 2. The rotary encoder according to claim 1, wherein the phase modulation signals from the first and second tracks are multiplied, and the low-frequency component thereof multiplies the number of pulses of the first and second tracks. A rotary encoder characterized by being configured to obtain a beat signal corresponding to the difference. 3. The rotary encoder according to claim 1, wherein the first and second phase modulated signals from the first and second tracks are waveform-shaped and the signals are digitally phase-compared. A rotary encoder, which is configured to obtain a beat signal corresponding to the difference in the number of pulses of the tracks. 4. The rotary encoder according to claim 1, wherein the recording pattern of the third track is the first pattern.
Alternatively, a phase-modulated signal obtained from the first or second track by recording as a signal having the same reproduction wavelength or the same reproduction wave number as the second track and having different phases for each zone and extracting in the form of phase modulation. A rotary encoder configured so as to form a demodulation signal that specifies the zone by comparing with the above. 5. The rotary encoder according to claim 4, wherein the recording patterns of the third track are each 3
A rotary encoder consisting of four blocks including one zone. 6. The rotary encoder according to claim 4, wherein the recording pattern of the third track includes a pattern that appears only once per rotation of the motor. 7. The rotary encoder according to claim 1, wherein the signals of the first and second tracks are detected in the form of a phase modulation signal, and the signals are switched to generate a decimal series pulse and a binary series pulse. A rotary encoder characterized by being adapted to output.