JPH01227922A - Encoder - Google Patents

Abstract

PURPOSE:To improve the resolution of an encoder with a simple circuit by providing a pulse multiplying circuit which inputs two kinds of multiphase AC sine waves having different phases and outputs square-wave pulses having a short period. CONSTITUTION:Two kinds of AC sine-wave signals having a phase difference of 90 deg. between their phases are obtained from magnetic sensor elements 12 and 13 and inputted to a pulse multiplying circuit 20. The pulse multiplying circuit 20 divides the signals into N pieces and, at the same time, produces N pieces of square-wave pulses by synthesizing each divided value of one kind of signals and the corresponding divided value of the other kind of signals. Then the circuit 20 outputs square-wave pulses having a period which is 1/N of the sine wave of the input signal by logically processing the N pieces of square-wave pulses.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an encoder that detects the rotation or position of a mechanical servo system or the like and outputs an electrical signal.

[Prior Art] When various types of rotary and linear actuators are servo-controlled, highly accurate rotation angle and position detectors (encoders) are attached to perform feedback control.

FIG. 3 is a schematic perspective view showing the structure of an example of a magnetic rotary encoder, in which reference numeral 11 denotes a rotary drum that is connected to an object to be measured and is rotated, and 12 and 13 denote a rotary drum 1.
A-phase and B-phase magnetic sensor elements that detect the polarity and magnitude of the magnetic field due to magnetic poles magnetized on the circumference of 1; 14 is an A-phase linear amplifier; 15 is a B-phase near amplifier; 16 is an A-phase Schmitt Trigger circuit, 17 is B phase Schmitt trigger circuit, 1
8 is an A-phase output terminal, and 19 is a B-phase output terminal.

On the circumferential surface -F of the rotating drum 11, a large number of vertical linear magnetic poles are magnetized alternately N and S. For example, when 100 pairs of N and S magnetic poles are magnetized on the circumference of the rotating drum 11, one pulse is output from the output terminals 18 and 19 for every 1/100 rotation. At this time, the output of the magnetic sensor elements 12 and 13 is a sine wave containing some harmonics, but this sine wave is waveform-shaped to obtain a pulse output. Further, in order to detect the rotation direction, two phases A and B having a 90° phase difference are output.

[Problems to be Solved] However, even if an attempt is made to further improve the resolution of an encoder such as the above-mentioned magnetic rotation sensor, there is a technical upper limit to the improvement in processing accuracy and the performance of the detection element. In addition, the assembly of the encoder requires extremely high precision, and the mechanical parts (bearings of the rotating part, supporting materials for the detection elements) also require high precision, so it is difficult to improve the resolution of the encoder shown in the example above using the same method. It is.

The present invention is intended to solve the above-mentioned problems, and aims to provide a high-resolution encoder that is easy to manufacture without modifying detection mechanism components.

[Means for Solving the Problems] The encoder of the present invention uses two polyphase AC sine waves with different phases as input signals, divides one input signal a into N parts, and divides the other input signal into N parts. 1) Create N rectangular wave pulses by combining each partial pressure value of one input signal and the corresponding partial pressure value of the other input signal, and The present invention is characterized in that a pulse multiplier circuit is provided which logically processes N rectangular wave pulses and outputs a rectangular wave pulse having a period of 1/N of the input signal sine wave.

However, N is an integer of 2 or more.

[Operation] The output waveform of the detection element of the encoder for detecting the position amount, rotation amount, etc. usually takes a form close to an AC sine wave. Also,
The output signal format of the encoder is often a binary pulse. An AC sine wave has each element of amplitude, frequency, and phase, but many encoders use only the frequency element, so to speak.

In view of the above circumstances, the present invention aims to significantly improve the resolution of the encoder by using the phase component of the AC sine wave outputted by the sensor element as output information.
When two AC sine wave signals with a phase difference of 90° are obtained as the output of the sensor element, one of them is expressed as sinθ and the other as CO8θ, and the addition theorem of trigonometric functions (1) ), the two AC sine wave signals multiplied by a constant are added and subtracted to synthesize N AC signals with equal phase differences, and the N AC signals are logically operated to calculate the original signal N. A pulse multiplier circuit is provided that generates and outputs a pulse signal with twice the resolution.

[Example code] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Note that the reference numerals mentioned above indicate the same parts, and the explanation will be omitted.

FIGS. 1(a) and 1(b) are circuit diagrams of a magnetic rotary encoder as an encoder according to an embodiment, in which 14a is an A-phase inverting amplifier, 2o is a pulse multiplier circuit, and 21 to 32 are voltage dividing resistors R133. -40 are comparators, 41-46 are exclusive OR circuits, 47 is an A-phase multiplication output terminal, and 48 is a B-phase multiplication output terminal.

Here, details of the pulse multiplier circuit 20 will be explained.

The present invention utilizes the fact that the original signal (sensor output) of an encoder is approximately a sine wave, and processes the sine wave using an electronic circuit to generate multiple pulses, thereby creating a high-resolution encoder. .

The case of an encoder with two-phase A and B outputs will be described below, but since a 90° phase difference signal can be easily created even with three or more phases, the same processing as in the two-phase case can be performed.

If the original signal generated by the sensor element is expressed by sin θ and cos θ, then the addition theorem of trigonometric functions, i.e., sin 00cosA −cos 00sinA=si
n(θ-A) ...... By (1), the signal 5in (0-A) whose phase is shifted by A from the original signal sin θ
can be created. That is, s]nO1 and cos θ are the encoder's original signal 12 in FIG.
a, 13a, and cos A and sin A are proportional constants, which can be realized by a resistive voltage divider circuit (R21 to R32).

Further, the comparators 3 to 40 in FIG. 1 are equivalent to determining whether the left side of equation (1) is positive or negative.

By appropriately selecting the value and number of resistors shown in FIG.
・Theoretically, it is possible to create an infinite number of them at equal intervals.

That is, it is possible to create a polyphase 44-hour signal with equal phase difference from the two signals of sin O and cos O.

The circuit in Fig. 1 has a pulse multiplier N of 4, and uses four signals with the phase A shifted by π/4 with respect to the original signal d signal s]nθ, and the phase with respect to (sinO−π/8). 4 (No. 1) obtained by shifting A by π/4 are synthesized to obtain a pulse multiplied A phase output from the former 4 signals and a pulse multiplied B phase output from the latter 4 signals.

Note that there is a phase difference of 90 degrees between the pulse multiplication A phase output and the pulse multiplication II 3 phase output, and the rotation direction can be expressed.

FIG. 2 is a graph showing the signal waveforms of each part in FIG.
12a is the output waveform of the magnetic sensor element 12, 13a is the output waveform of the magnetic sensor element 13, A is the A-phase multiplied output signal (terminal 47) waveform, and B is the B-phase multiplied output signal (terminal 48) waveform. The period of waveform A is one-fourth that of waveform 12a, and the phase of waveform A and waveform B is 90° different.
(the number of pulses per unit rotation amount is four times).

The rotation direction is reversed, and the input signal Sin D, cos
If the front and back of the two phases of O are reversed, A, 13 in Figure 1
The phase outputs 47 and 48 are also automatically reversed, and pulse multiplication is performed in both forward and reverse directions without any problems.

The magnetic rotation amount encoder of this embodiment is configured as described above and operates as follows.

When the rotating tram 11 connected to the actuator whose amount of rotation is to be detected rotates, alternating current signals are generated in the magnetic sensor elements f-12 and f-13. These two exchanges (No. 71 is
Linear amplifier etc. 14.14a.

After being amplified by 15, the voltage is divided by a resistor circuit. The divided AC voltage is guided to comparators 33-40. Second
As shown in the figure, the outputs of the comparators 33 to 40 are digital signals obtained by binarizing sine waves whose phases differ by π/8. These digital signals (Q) are superimposed by exclusive OR circuits 41 to 46 to output a two-phase pulse having a period of one-fourth of the original signal.

This output signal is counted by a general encoder counting circuit (not shown) and is numerically outputted to another system as the rotation angle of the actuator.

In this way, the magnetic rotary encoder of this embodiment can be used without adding weight to the component mechanisms that make up the sensor.
By adding a relatively simple signal circuit, detection accuracy and resolution can be increased four times.

In this embodiment, the resolution is improved four times, but higher resolution can be achieved by installing a large number of voltage dividing resistors R21 to R32.

Further, in this embodiment, a magnetic type sensor is used as the rotation amount sensor, but if the sensor element output of an optical sensor is a sine wave, the resolution direction -L can be suitably achieved.

Further, in this embodiment, an example of application to a rotation amount sensor has been described, but the present invention can also be suitably applied to a linear distance amount encoder whose sensor element output is a sine wave without any modification.

[Effects of the Invention] The encoder of the present invention takes two polyphase AC sine waves with different phases as input signals, divides one input signal into N parts (N is an integer of 2 or more), and divides the other input signal into N parts (N is an integer of 2 or more). Input < 1j number N
dividing the voltage into N rectangular wave pulses by combining each divided voltage value of the one input signal and the corresponding divided voltage value of the other input signal, Since a pulse multiplier circuit is provided which logically processes the same N rectangular wave pulses and outputs a rectangular wave pulse whose period is 1/N of the input signal sine wave, the circuit is simple and the cost does not increase significantly. In addition, the resolution of the encoder is significantly improved, and the encoder can be made smaller and cheaper compared to its performance, resulting in large economic benefits.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are circuit diagrams of a magnetic rotary encoder as an example, Figure 2 is a graph showing signal waveforms at various parts of the encoder of the same example, and Figure 3 is a conventional magnetic rotary encoder. FIG. 2 is a schematic perspective view of a rotary encoder. 11... Rotating drum, 12.13. Magnetic sensor element, 14... A-phase linear amplifier, 14a...
・A-phase inverting amplifier, 15... B-phase near amplifier, 2
o...Pulse multiplier circuit, 21-32...Voltage dividing resistor R133-40...Comparator, 41-46
. . . Exclusive OR circuit, 47 . . . A phase multiplication output terminal, 48 . . . B phase multiplication output terminal. Patent Applicant Shinko Electric Co., Ltd. Agent Patent Attorney Fu Kobayashi Figure 1 (b) 33-40--Comparators 41-45--j'4F I's argument fWF-Colj
l Path 47---△Introduction 8th breath A sound output kfV'+48-
---BJO source 1x output power black ten

Claims (1)

[Claims] (1) In an encoder that generates a signal as a polyphase AC sine wave from information on position amount or rotation angle amount, the two polyphase AC sine waves with different phases are used as input signals, and one input signal is N (however, N is an integer of 2 or more), and divides the other input signal into N parts, and divides the voltage of the other input signal corresponding to each divided voltage value of the one input signal. a pulse multiplier circuit that synthesizes N rectangular wave pulses to create N rectangular wave pulses, performs logical processing on the N rectangular wave pulses, and outputs a rectangular wave pulse having a period of 1/N of the input signal sine wave. An encoder characterized in that: