JPH02195208A - Detected signal processing circuit for encoder - Google Patents

Abstract

PURPOSE:To obtain highly accurate absolute position data by providing a non- volatile memory wherein error correcting data are written beforehand, the absolute position data from a position detecting circuit are made to be address input data, the absolute position data after the error correction are outputted, and the data can be rewritten. CONSTITUTION:In a main body 1 of a rotary encoder, a position detecting circuit 12 and a data conversion memory 2 are provided. The memory 2 is composed of a PROM which can be erased electrically. Data for error correction area written beforehand. When absolute position data D, which correspond to the relative displacement of a scale 13 that is outputted from the circuit 12, are inputted into the input terminal of the memory 2, absolute position data Da after the error correction are outputted from the terminal. The dected error of an individual encoder 1 due to the fluctuation of the gap between the scale 13 and magnetic sensors 14 and 15 is corrected. The highly accurate (+ or - three seconds) data Da are obtained. The error correcting data can be arbitrarily changed in periodic detections.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a detection signal processing circuit for an encoder suitable for use in a magnetic encoder or the like that detects displacement such as angle or position.

"Prior Art" FIG. 6 is a block diagram showing an example of a position detection circuit 12 incorporated in a conventional magnetic rotary encoder.

In this figure, 13 is a scale made of a disc-shaped magnetic recording medium rotatably supported by a shaft, and 14 and 15 are magnetic sensors disposed opposite to the scale 13 with a gap therebetween.

Position information of a sine wave of wavelength λ is magnetized and recorded on this scale 13 along a circular orbit facing the magnetic sensors 14 and 15. Moreover, the magnetic sensor 14°15 has a scale of 1
It outputs a signal corresponding to the strength of the magnetic field on the magnetic field 3, and is constructed of, for example, a magnetic resistance screen. here,
The magnetic sensor 15 has an angle of 1/4λ (9
The magnetic sensors 14 and 15 are spaced apart from each other by (m+1/4)λ.
However, the mountain is set as a positive integer). and,
As can be seen from the above, if the signal output from the magnetic sensor 14 is a sine wave, the signal output from the magnetic sensor 15 is a cosine wave. Therefore, if the interval of one period of the magnetization sine wave (the magnetization section from pole to pole of the scale 13, hereinafter referred to as magnetization pitch) is θ=θ~2π, then
The detection signals output from the magnetic sensors 14 and 15 are sin θ and cos θ, respectively.

Next, l 6 and 17 are amplifiers that amplify the detection signals sin θ and cos θ output from the magnetic sensors 14 and 15, respectively. Reference numeral 18.19 denotes an A/D converter that converts the detection signals of the magnetic sensors 14 and 15, each amplified by the amplifiers 16.17, into digital signals, and converts the digitized sin θ and COS θ to the digital multiplier 20.2.
1.

The output signals of multipliers 20 and 21 are respectively output to digital subtracters 2
2, and the output signal of the subtracter 22 is supplied to a digital comparator 23. This digital comparator 23 sends the U/I5 signal to the up/down switching terminal U of the counter 24, which becomes "l" if the subtraction result of the subtracter 22 exceeds 0, and becomes "0" if it does not exceed 0. /[). The counter 24 counts the clock signal CK, and when the "l" signal is supplied to the up/down switching terminal U/b, it starts counting up and "
When a 0" signal is supplied, a down count is performed. Next,
Reference numeral 25 denotes a function generation ROM, which outputs sine and cosine data corresponding to the count value Φ of the counter 24. That is, sin is stored in the function generation ROM 25 in advance.
Data of Φ and cosΦ are stored, and the stored data is read out sequentially according to the count value Φ. The data COSΦ is then supplied to the other input terminal of the digital multiplier 20, and the digital sin
Φ is supplied to the other input end of the digital multiplier 21.

According to the above configuration, the output of the subtracter 22 is 5 inches (θ−
Φ). Therefore, the comparator 23 is 5 inches (θ−Φ
) If the value of Increase or decrease depending on the sign. The components mentioned above! Divided circuit 28 by 8-25
is configured.

Next, 30.31 determines the detection signals of the magnetic sensors 14 and 15, each amplified by the amplifiers 16.17, using a predetermined threshold value to generate two levels, the "1 degree level" and the "0" level.
This is a waveform shaping circuit that converts into a value signal. In this case, the output signals Pl+Pffi of the waveform shaping circuits 30 and 31 become rectangular waves whose phases are shifted by π/2, and the magnetic sensors 14 and 1
When the scale 13 is displaced in the positive direction with respect to 5, the pulse P advances, and when it is displaced in the negative direction, the pulse P,
is progressing. 33 is the magnetic sensor 14, 15
This is a direction determining circuit that determines the direction of displacement of the scale 13 relative to the direction of the scale 13. For example, the direction is determined depending on whether the level of the pulse P at the rising edge of the pulse P is "1" or "o". The output signal Sw of this direction discrimination circuit 33 is connected to the up/down switching terminal U of the counter 34.
/[5 and is also output to the outside. The counter 34 counts the pulses P while switching up or down in response to the signal Sv. In this case, the magnetic sensors 14, 15
When the scale 13 is displaced in the positive direction, an up count is performed, and when the scale 13 is displaced in the negative direction, a down count is performed. Also, scale 1
3 rotates once, the zero fish signal Sz output at the reference position becomes the zero point pulse Pz after passing through the waveform shaping circuit 32, and this O point pulse Pz is supplied to the reset terminal R of the counter 34. As a result, the counter 34 is reset each time the magnetic sensors 14, 15 reach the reference position. Therefore, counter 3
A count value of 4 indicates that the scale 13 has passed over the magnetic sensors 14 and 15 between the reference position and the position on the scale 13 that is currently facing the magnetic sensors 14 and 15.
The value corresponds to the number of magnetization pitches.

Then, the output signal N of the counter 34 is the absolute position data D.
The count value Φ of the counter 24 constitutes the data of the lower bits of the absolute position data D.

According to the above-described configuration, the scale 13 is connected to the magnetic sensor 14.
, 15 in the positive direction, the counter 34 indicates that the magnetization pitch of one of the scales 13 is equal to
Every time it passes over 5, it counts up, and this count value is output to the upper bit of the absolute position data D. Therefore, if we look at the upper bits of the absolute position data D, we can tell how many magnetization pitches of the scale 13 have passed over the magnetic sensors 14 and 15. In other words, at the present moment, You can see how many pitches the part is located from the reference position.

In addition, the detection signal s output from the magnetic sensors 14 and 15
inθ and cosθ are each amplified by amplifiers 16.17, converted to digital signals by A/D converters 18.19, and then outputted from the function generation ROM 25 as a signal eO8Φ.
, sin Φ, and as a result, each output signal of the multiplier 20.21 becomes sin θ·cos Φ and cos θ·si
It becomes nΦ. These multiplication results are supplied to the subtracter 22, whereby the output signal of the subtracter 22 is sinθ'cosΦ−cosθ・sinΦ=sin(θ
-Φ) (1), and 5 inches (θ-Φ) is detected. Then, the count value Φ of the counter 24 increases or decreases depending on whether the value of 5 inches (θ-Φ) is positive or negative, and the outputs sin Φ and cos Φ of the function generation ROM increase or decrease in accordance with this count value Φ. As a result, the dividing circuit 28 shown in FIG.
such that the value of in(θ−Φ) is 0, that is, θ=
It becomes a phase-locked loop like Φ.

Therefore, the count value Φ of the counter 24 becomes data indicating where the magnetic sensor 14 is located within one magnetization pitch. In this case, if the number of bits of the counter 24 is 8 to 10 bits, the detection position resolution based on the count value Φ will be approximately 1/256 to 1/2048 of l magnetization pitch.

In this way, the dividing circuit 28 electrically divides one magnetization pitch into small pieces to obtain highly accurate position data.

[Problems to be Solved by the Invention] Incidentally, although the position detection circuit 12 incorporated in the conventional magnetic rotary encoder described above is provided with the division circuit 28 for obtaining highly accurate absolute position data, for example, the scale No means were taken to correct the detection error (about ±20 seconds) of each rotary encoder caused by gap fluctuations between the rotary encoder 13 and the magnetic sensors 14 and 15. In this case, for example, there may have been an ultraviolet-erasable FROM (programmable ROM) installed in the dividing circuit 28 and used to correct the position data. During periodic verification of the delivered rotary encoder, the FROM for error correction was removed.
This was accompanied by the complexity of having to write new data.

This invention was made in view of the above-mentioned circumstances, and allows highly accurate absolute position data to be obtained, error correction data to be arbitrarily written on the production line, and error correction data to be written during periodic inspection. It is an object of the present invention to provide a detection signal processing circuit for an encoder that can arbitrarily change data.

[Means for Solving the Problems] This invention provides a method for outputting sine wave and cosine wave detection signals corresponding to the position information when a recording medium on which the position information of the sine wave is recorded is relatively displaced. an encoder comprising first and second sensors, and a position detection circuit that outputs absolute position data corresponding to the relative displacement of the recording medium based on the detection signals of the first and second sensors. A rewritable nonvolatile memory is provided in which error correction data is written, the absolute position data output from the position detection circuit is used as an address input, and the absolute position data after error correction or the error data for correction is output. It is characterized by

"Operation" According to the above configuration, when the absolute position data output from the position detection circuit is input as an address input to the nonvolatile memory in which error correction data is written in advance, the error will be detected from the data output terminal. Since corrected absolute position data or error data for correction is output, highly accurate absolute position data can be obtained. In this case, since rewritable non-volatile memory is used, error correction data can be arbitrarily written on the production line, and error correction data can also be arbitrarily changed during periodic verification. It is possible.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention. In this figure, the rotary encoder body i
A position detection circuit 12 and a data conversion memory 2 are provided inside. Data conversion memory 2 is EEPROM (
It is composed of electrically erasable PROM),
Data for error correction is written in advance. and,
The absolute position data D (20 bits) corresponding to the relative displacement of the scale 13 output from the position detection circuit 12, that is, the absolute position data D before error correction, is input to the address input terminal of the data conversion memory 2 as address data. When input, error-corrected absolute position data Da (20 bits) is output from the data output terminal. As a result, detection errors of the individual rotary encoders caused by gap fluctuations between the scale 13 and the magnetic sensors 14 and 15 are corrected, and highly accurate (within ±3 seconds) absolute position data Da is obtained. Also, data conversion memory 2 is EE.
Since it is configured with a PROM, error correction data can be arbitrarily written without being removed on the production line, and error correction data can also be arbitrarily changed during periodic verification.

FIG. 2 is a diagram showing the configuration of a modification of the first embodiment described above. In this modification, only the position detection circuit 12 is provided in the rotary encoder main body 1, and the output from the position detection circuit 12 is Absolute position data D before error correction is supplied to the receiving board 3 via the cable 4. It looks like this. Then, the absolute position data D before error correction is supplied to the data conversion memory 2 via the reception circuit 5 provided in the reception board 3, and is converted into error-corrected absolute position data Da. ing.

Next, FIG. 3 is a diagram showing the configuration of a second embodiment of the present invention. In this diagram, when the data conversion memory 2a receives absolute position data D output from the position detection circuit 12, , error data Db corresponding to each error component is output. Then, this error data Db is added to the absolute position data D by the addition circuit 6, so that the error-corrected absolute position data D
a is output. FIG. 4 shows a modification in which the data conversion memory 2a and the adder circuit 6 are provided on the reception board 3.

Next, FIG. 5 is a diagram showing the configuration of a third embodiment of the present invention. In this figure, the data conversion memory 2b has data related to error correction written in advance in various display units of 1 μm per second. It is. Then, a signal specifying a specific display unit from among these various display units is sent to the terminal Ta,
By inputting it as part of the address data via Tb and Tc, the absolute position data Da' corrected by this specific display unit is output. Thereby, the display unit of the absolute position data Da' can be arbitrarily selected.

In addition, in the above-mentioned embodiment, the case where it is applied to a position detection circuit of a magnetic rotary encoder is explained as an example, but the application is not limited to this, and it can be applied to a rotary encoder or a linear encoder such as an optical type, an electromagnetic type, a capacitance type, etc. Of course, it is also possible to apply the present invention to a position detection circuit of an encoder.

"Effects of the Invention" As explained above, according to the present invention, absolute position data output from a position detection circuit is inputted as an address of a nonvolatile memory in which error correction data is written in advance, and the data is Since absolute position data after error correction or error data for correction is output from the output terminal, highly accurate absolute position data can be obtained, and since rewritable non-volatile memory is used, production line The advantage is that the data for error correction can be arbitrarily written in the above data, and the data for error correction can also be arbitrarily changed during periodic verification.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the invention, FIG. 2 is a block diagram showing the configuration of a modification of the same embodiment,
FIG. 3 is a block diagram showing the configuration of a second embodiment of the present invention, FIG. 4 is a block diagram showing the configuration of a modification of the same embodiment,
FIG. 5 is a block diagram showing the configuration of a third embodiment of the present invention, and FIG. 6 is a block diagram showing the configuration of a position detection circuit incorporated in a conventional magnetic rotary encoder. l...Rotary encoder main body, 2.2a,
2b... Memory for data conversion, 3...
Receiving board, 5... Receiving circuit, 6... Adding circuit, 12... Position detection circuit, 13... Scale (recording medium), 14.15・
...Magnetic sensor (first and second sensor).

Claims (3)

[Claims] (1) first and second sensors that respectively output sine wave and cosine wave detection signals corresponding to the position information when a recording medium on which the sine wave position information is recorded is relatively displaced; In an encoder comprising a position detection circuit that outputs absolute position data corresponding to the relative displacement of the recording medium based on the detection signals of the first and second sensors, data for error correction is written in advance, and the A detection signal for an encoder, characterized in that it is provided with a rewritable nonvolatile memory that takes absolute position data output from a position detection circuit as an address input and outputs absolute position data after error correction or error data for correction. processing circuit. (2) A claim characterized in that an addition/subtraction means is provided for adding and subtracting the absolute position data output from the position detection circuit and the error data output from the nonvolatile memory to calculate absolute position data after error correction. The detection signal processing circuit for an encoder according to item 1. (3) Data related to error correction is written in advance in the nonvolatile memory for each type of display unit, and by specifying a specific display unit from among the various display units as part of address input, 2. The encoder detection signal processing circuit according to claim 1, wherein the encoder detection signal processing circuit outputs the absolute position data after correction based on the specific display unit.