JPS61160011A - Encoder - Google Patents

Abstract

PURPOSE:To obtain accurate and highly resolvable rotating position by simple and easy assembly and adjustment, by generating the secondary signals with an accurate phasediflerence of 90 deg. in a phase adjusting unit and conducting an accurate 90 deg. phase division by the succeeding phase division. CONSTITUTION:Signal SA1=A-phase signal-reversed A-phase signal, signal SB1=B-phase signal-reversed B-phase signal are fed out from adders 81, 82 of a signal detecting unit 8 respectively and from an adder 31 of a signal adjusting circuit 3, a signal AB1=SA1+SB1, and from an adder 32, a signal AB2=SA1-SB1 is obtained. Signal SA1 and SB1 are of the same maximum amplitude,and even if they are of the wave form with the same frequency, but not of the phase difference of 90 deg., signal AB1 and AB2 of the circuit 31 intersect through a right angle with the phase difference of 90 deg.. Consequently, by using signal AB1 and AB2 intersecting correctly through a right angle, a phase dividing signal is available in a phase dividing circuit 4 and using this signal, a rotating signal generating circuit 6 can feed out accurate rotating direction detection signal and rotating position pulse signal.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a rotary encoder, and more particularly to an incremental type rotary encoder that is easy to assemble and adjust and is capable of obtaining highly accurate angle signals.

2. Description of the Related Art For example, an optical incremental rotary encoder, as shown in FIG. Z), LII) 7 which emits a beam from one of the slits of the rotary code plate, and a light receiving part (LR
D) It has 8'. The light receiving unit 8' detects the rotational position of the rotary code plate, and generates two signals having a certain phase relationship, for example, an ideal phase difference of 90 degrees, so that the rotation direction can be detected. and two light-receiving elements, for example, 7 otodiodes (
FD) is arranged so as to receive the light transmitted through the slit of the rotary code plate via the fixed slit and the top plate. The human phase and B phase signals have waveforms as shown in FIGS. That is, each offset voltage V.

It is a sinusoidal periodic changing waveform superimposed by ff,
In the case of forward rotation, the physiognomic signal (Fig. 3 (A)) as shown in the figure
The phase 00 phase is ahead of the B phase signal (Fig. 3 (b)). For convenience of signal processing, inverted A-phase and B-phase signals are obtained for the human phase and B-phase signals, respectively (Fig. 3 (B) and (
g)), and the physiognomic signal SAI which does not include the DC component =
SA -SA (Figure 3 (C)) Oh! and B phase signal 8
B1=SR-8B (Fig. 3(F)) is obtained. The AC A phase signal SAI and the AC B phase signal SBI are the same as above 9
There is a phase difference of 0''.

The human phase signal SAI and the B-phase signal SBI have a phase difference of 90 degrees and a phase difference of, for example, 22.5 degrees.
Phase difference splitting circuit (or interpolation circuit) 4 that splits into different signals
The phase difference dividing circuit 4 is useful for obtaining an angular signal with a resolution higher than that of the actually detected signal. However, the signal that can actually be detected by one rotation of the rotary code plate is 2,500 cycles, and its resolution is 172,500 cycles, but by using the 4-division phase signal as described above, 1/10,000
This results in a signal with a resolution of .

While the phase difference dividing circuit 4 contributes to obtaining a higher resolution than K as described above, even if the rotational code plate has fewer slits, it can produce signals with the same accuracy as a signal with a large number of slits and grooves. This contributes to the acquisition of In particular, with a magnetic type encoder, it is difficult to obtain a detection signal having a resolution comparable to that of an optical encoder due to the size of the magnet, the minimum interval for magnetic flux discrimination, etc.

Therefore, in the magnetic encoder, it is necessary to generate a signal having a resolution higher than that of the detection signal by using the signal obtained by such phase division.

The phase-divided signal obtained in this way is applied to the rotation signal generation circuit 5, and is subjected to pulse shaping. If the A-phase signal is ahead of the B-phase signal, the phase-divided signal is regarded as normal rotation and the phase-divided signal is The line driver (LD) 6 outputs an incremental pulse signal according to the signal, and in the opposite case, a decremental pulse signal to the line driver (LD) 6. The line driver 6 is a device that requires a rotational position signal. , for example, outputs the amplified signal to the NC side.

C6 Problems to be Solved by the Invention In the above explanation, when the phase dividing circuit 9 generates a plurality of signals, the human phase signal and the B phase signal must be
It is assumed that there is a phase difference of '.

However, if the directivity of the LIm (LIm) is not properly adjusted and the rotary code plate, fixed slit plate, photodiode, etc.
Signals SAI and SBI do not have a phase difference of 90''.

Therefore, a signal calculated using a signal generated secondarily based on a signal with such an inaccurate phase difference will contain an error. However, the problem with K, which allows accurate phase differences to be obtained, is that it takes considerable time and effort to assemble and adjust the encoder.

In addition, even if the assembly and adjustment are performed accurately as described in 5 above, there is a problem in that a predetermined phase difference cannot be obtained (due to deterioration of characteristics due to aging and changes in characteristics depending on temperature), resulting in false detection. There is. In this case, there is a problem in that troublesome reassembly adjustments occur.

The above problem can be solved by optical incremental type rotary
The same applies not only to coders but also to magnetic encoders, for example. That is, problems similar to those described above arise, such as adjustment of the permanent magnet attachment and changes in magnetic flux.

20 Means for Solving the Problems The present invention aims to solve the above-mentioned problems and provide accurate rotational position signals with simple and easy assembly and adjustment. As shown in FIG. 1, first and second signals have a periodic waveform according to the rotation of the rotating part and have a predetermined phase difference from each other so that the rotation direction of the rotating part can be identified. and a signal that calculates a third signal as a vector sum and a fourth signal as a vector difference so that the vector sum and vector difference of the first and second signals are orthogonal. an adjustment section 3; and a phase division section 4 that arbitrarily divides the phase difference between the third and fourth signals to generate a plurality of signals having predetermined phase differences.
and a rotation signal generating section 5 that generates signals corresponding to the rotational direction and rotational position of the rotating section based on the plurality of signals from the phase dividing section.

E 1 action signal adjustment section 3 generates third and fourth signals, which are secondary signals having an accurate 90'' phase difference, and a subsequent phase division section 4 divides the accurate 9011 phase. go.

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

The encoder shown in FIG. 1 has an incremental mechanism part l and a periodic waveform according to the rotation of the rotating part, and has a predetermined phase difference between them so that the direction of rotation of the rotating part can be identified. a rotational signal detection unit 2 that generates first and second signals having a rotation signal, and a third signal as a vector sum and a third signal as a vector difference so that the vector sum and vector difference of the first and second signals are orthogonal. a signal adjustment circuit 3 that calculates a fourth signal; a phase division circuit 4 that arbitrarily divides the phase difference between the third and fourth signals to generate a plurality of signals having a predetermined phase difference; A rotation signal generation circuit 5 that generates signals corresponding to the rotational direction and rotational position of the rotating part based on a plurality of signals from the circuit, and a line driver 6
It consists of

As a more specific embodiment of the encoder shown in FIG. 1, the construction of an optical incremental encoder is shown in FIG.

The encoder shown in FIG. 5 includes the rotating shaft, the rotating code plate, the fixed slit, the top plate (none of which are shown), the light emitting diode (IJD) 7, and the light emitted from said 1, as described above in connection with FIG. It has a signal detection unit 8 that includes two photodiodes that receive light that has passed through the slits of the rotating code plate and the fixed slit plate and generate two signals with different phases, an A-phase signal and a B-phase signal. . The encoder further includes a 1-signal adjustment circuit 3, a phase division circuit 4, a rotation signal generation circuit 5, and a line driver 6.

The signal detector 8 also outputs a human phase signal SA, an inverted A-phase signal SA, an AC A-phase signal SAI, and a B-phase signal SB.

The inverted B-phase signal SR and the AC B-phase signal 8B1 are the third
This is similar to that shown in FIGS. (4) to (g).

A detailed circuit diagram of a part of the signal detection section 8, the signal adjustment circuit 3, and the phase division circuit 4 is shown in FIG.

In the signal detection section 8, both 81 and 82 are adders (to which the A-phase signal SA and the B-phase signal SB are applied to the non-inverting input terminals, and the inverted human face signal 臥 and the inverted B-phase signal plane are applied to the inverting input terminals).
ADR), in other words indicates a subtracter. Therefore adder 81
From, 5A1=SA-8A, from adder 82, SBI
= SB - SB is output.

The signal adjustment circuit 3 consists of an adder 31 that adds the above-mentioned SAI and SBI, and an adder 32 in which sAl is connected to the non-inverting input terminal K and 8B1 is connected to the inverting input terminal, in other words, a subtracter. Therefore, from the adder 31, the third signal ABI,
ABI = SAY + SBI, fourth signal AB2 from adder 32, AB2 = SAI - SB
I is obtained.

Here, consider a case where the signals SAI and SBI have approximately the same maximum amplitude and have periodic waveforms with the same period, as shown by vectors in FIG. 7, but the phase difference φ is not 90°.

However, it should be noted that under the above conditions, theoretically, the signals ABI and AB2 from the signal conditioning circuit 3 are always orthogonal, regardless of the value of the phase difference φ between SAI and SBI. That is, when the rotary shaft rotates in the forward direction, the signal AB2 leads the signal AB1 in phase by 90 degrees as shown in FIG. 7, and in the case of reverse rotation, the signal AB1 leads the signal AB2 in phase by 06 degrees. Signal AB due to phase difference φ
Although the amplitudes of I and AB2 are different, the phase difference is always 90''.

Therefore, by using the accurately orthogonal signals ABI and AB2, an accurate phase division signal can be obtained in the phase division circuit 4, and by using such a phase division signal, the rotation direction can always be detected accurately in the rotation signal generation circuit 5. It becomes possible to output a rotational position Norse signal, that is, an incremental signal or a decremental signal, in accordance with the rotational position. These incremental signals or decremental signals are outputted via the line driver 6.

In other words, even if there is a phase difference between the human phase signal and the B phase signal, as long as the amplitudes are the same, an accurate rotational position pulse can be obtained. This means that the adjustment does not require great precision. Therefore, automatic assembly is possible and productivity is greatly improved.

In the above example, it is assumed that the human phase and B phase signals have the same amplitude and period. The period is almost determined by the settings of the slits in the rotary code plate, and is generally not affected by changes over time or temperature, and can be considered to be approximately constant. However, the amplitude does not necessarily match depending on the directivity of LII), the mounting position of the photodiode, and the difference in the characteristics of the two photodiodes, and furthermore, the amplitude
It may be affected by changes over time.

For this purpose, the adder 31 shown in FIG. 6 includes an inverting amplifier layer and variable human resistors R1 and R2 as shown in FIG. 8, and the amplitude of the signal SAI is The amplitude of the signal SRI and the amplitude of the signal SRI can be adjusted so that they become the same. In the adder 32, in FIG. 8, SAI is connected to the inverting input terminal of the amplifier, and SB
This is equivalent to I being connected to a non-inverting input terminal, and the amplitude can be adjusted in the same way as the adder 31.

As a result, the variable resistor R of the adder 31, 32 can be adjusted without the need for complicated assembly adjustment as in the conventional case during the initial assembly.
1. Phase difference signal SAI with high accuracy only by adjusting R2
, SBI is obtained. In addition, temperature changes,
Even if there is a difference in amplitude due to aging, the variable resistors R1 and R2 can be adjusted without reassembly and adjustment as in the past.
You can easily obtain high-quality signals by simply adjusting the resistance values of SAI and S.
B1 is obtained.

The phase dividing circuit 4 receives such high quality signals SAI and 8B1.
A desired phase division signal CI+02+...Cn is obtained by combining
A plurality of adders 41,42°43, .
··have. Each of the adders 41, 42, . . . is similar to that shown in FIG.

For example, considering the case where a signal C1 with a 45° phase is generated as the output of the adder 41, if the attenuation rate kt = 1 and the vector sum of the orthogonal signals ABI and AB2 is calculated, however, the amplitudes of the signals ABI and AB2 are If the axes are equal, a signal with an amplitude of 1 AM and a phase difference of 4560 between the signals ABI and AB2 can be obtained. Therefore, taking the adder circuit shown in FIG. 8 as an example, the resistance values of the variable resistors R1 and R2 may be set to the same value.

Furthermore, in order to make the amplitude of one signal C1 equal to A, the resistor 81 is set so that the amplitude of each input signal is 1/v/T.
．． It is sufficient to set the value of R2.

Also, the resistors R1 and R2 should be set so as to receive the signal C3 with a phase of 22.5° from the adder 42, and the resistors R1 and R2 should be set to receive the signal C3 with a phase of 67.5° from the adder 43. Good.

When obtaining a general Kn-divided phase signal using the phase division circuit 4 of FIG. 6, the following calculation may be performed.

= ABI' + k4AB2 or = JAJ31 + Al32' The present invention can take many variations of the above-described embodiments. For example, as shown in FIG. 9, in the rotation signal detection section 8'', the A-phase signal SA and the B-phase signal SR are transmitted through DC component subtracters 83 and 84, respectively, as shown in FIG. 3(4).
and Φ), the voltage V shown in the figure. ff is removed to obtain the AC component A-phase signal SA'.

Take out the B-phase signal SB'. Thereafter, the signal SA' is applied to the adder 36, 37 via the amplifier 33, and the signal SB
' is applied to an adder 36 via an amplifier 34 and to an adder 37 via an inverting amplifier 35. Signal adjustment circuit 3
' performs the same operation as described above. Therefore, signals ABI and AB2 with a phase difference of 900 are obtained. Next, the phase division circuit 4' includes adders 401, 402, 403, . . A signal C3 having a phase difference is generated, and the adder 403 generates a signal C3 having a phase difference of 67.5× by combining the signal C1 and the signal AB2. The same applies below.

The present invention is applicable not only to the above-mentioned optical encoder but also to a magnetic encoder. That is, the mechanism section 1 and signal detection section 2 shown in FIG. 1 are only magnetic.
This is because the other signal processing systems are the same as those described above.

1. Effects of the Invention As described above, the present invention provides an encoder that is simple and easy to assemble and adjust, and provides accurate, high-resolution rotational position signals.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an encoder as an embodiment of the present invention, Fig. 2 is a block diagram showing an example of a conventional encoder, Fig. 3 is a waveform diagram of a detection signal of the encoder, and Fig. 4 is a block diagram of a conventional encoder. A vector diagram of the A-phase and B-phase signals of the encoder, FIG. 5 is a specific configuration diagram of the optical encoder of FIG. 1, FIG. 6 is a specific circuit diagram of a part of FIG. 5, and FIG. is a vector diagram of the signal obtained by the encoder shown in FIGS. 5 and 6, FIG. 8 is a detailed circuit diagram of the adder shown in FIG. 6, and FIG. This is a detailed circuit diagram of (Explanation of symbols) 1... Mechanism section, 2... Rotation signal detection section, 3... Signal adjustment circuit, 4... Phase division circuit, 5... Position signal detection circuit, 6... Line driver, 7...LED,
8... Light receiving section.

Claims (1)

[Claims] 1. First and second signals having a periodic waveform according to the rotation of the rotating part and having a predetermined phase difference from each other so that the rotation direction of the rotating part can be identified. rotation signal detection means for generating a rotation signal; and signal adjustment for calculating a third signal as a vector sum and a fourth signal as a vector difference so that the vector sum and vector difference of the first and second signals are orthogonal. a phase dividing means for arbitrarily dividing the phase difference between the third and fourth signals to generate a plurality of signals having a predetermined phase difference; and a rotating unit based on the plurality of signals from the phase dividing means. An encoder comprising rotation signal generating means for generating a signal corresponding to the rotation direction and rotation position of the encoder. 2. The encoder according to claim 1, wherein the signal adjustment means includes an amplifier circuit capable of adjusting the amplitudes of the first and second signals. 3. The phase dividing means has a plurality of adder circuits provided in parallel, and the third and fourth signals are applied to each adder circuit so that signals with a desired phase difference are obtained. the amplitude of at least one of the fourth signals is adjusted;
An encoder according to claim 1 or 2. 4. The phase dividing means has a plurality of adder circuits arranged in series so as to sequentially divide the phase difference between the third and fourth signals into signals with a desired phase difference, and the first adder circuit is applied with the third and fourth signals, and the outputs of the adder circuits up to the previous stage are applied in an appropriate combination to the adder circuit in the subsequent stage, and the amplitude of at least one of the input signals of the plurality of adder circuits is adjusted to a desired level. The encoder according to claim 1 or 2, which is adjusted so as to obtain a phase difference signal. 5. The encoder according to claim 4, wherein amplitude adjustment of the plurality of adder circuits can be changed.