JPS62142219A - Displacement detecting device for encoder - Google Patents

Abstract

PURPOSE:To improve the accuracy, also to raise the resolution, and also to output a displacement data of the present time point immediately when a power source has been turned on, by constituting the titled device so that most of processing are executed by a digital signal. CONSTITUTION:Signals sintheta, costheta which are outputted by a movement of magnetic sensors 16, 17 are A/D-converted 18, 19, respectively, and thereafter, and supplied to a PLL consisting of a function generating and multiplying part 28, a subtracter 22 and a count means 29. On the other hand, output signals of the sensors 16, 17 are supplied to a counter 34 together with an 'O' point pulse PZ which is outputted through a waveform shaping circuit 32 at every one rotation of a scale 15, through waveform shaping circuits 30, 31 and a direction discriminating circuit 33. A count value of this counter 34 becomes a value corresponding to the number of magnetic sections on the scale 15 which the sensors 16, 17 have passed through. Also, this value and an output data of the count means 29 are stored as an absolute displacement data, and even immediately after a power source has been turned on, a displacement at that time point can be outputted instantaneously. Also, most of processings are executed by a digital signal, and an analog element is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a displacement detection device for an encoder suitable for use in detecting displacement such as angle or position.

"Prior Art" A circuit shown in FIG. 3 is generally known as a circuit for converting an analog angle signal into a digital signal. The circuit shown in this figure is a circuit that converts a resolver signal into a denotal angle signal. In the figure, ``■'' is an angle detection section that outputs a resolver signal, and is made up of a non-chroma, which is a type of recirculating transformer, and a Scotto transformer, etc., that converts the output signal of this synchro into a resolver signal. In this case, the carrier wave signal sinω is applied to the non-black rotor. When L is supplied, a synchronized signal corresponding to the rotation angle θ of the rotor is obtained from the stator, and when this synchronized signal is supplied to the primary side of the Scott transformer, sin θ・sin ω is obtained from the secondary side of the Scott transformer. . L and COSθ・Sinω
. A resolver signal of t can be obtained.

Next, 2 and 3 are demodulators, which remove the carrier signal from the resolver signal by performing synchronous detection etc.
Extract each angle signal of θ and cos θ. Each output signal of the demodulator 2.3 is supplied to one input terminal of an analog multiplier 4.5, and the output signals of the analog multipliers 4 and 5 are supplied to a subtracter 6 to detect the difference. . The output signal of the subtracter 6 is supplied to a VCo (voltage controlled oscillator) 7,
The output signal of Co7 is supplied to an up/down counter 8.

In this case, when the output signal of subtracter 6 is positive, VCo7
The output signal of is supplied to the up-count terminal of the up-down counter 8, and when the output signal of the subtracter 6 is negative, V
The output signal of Co7 is supplied to the down count terminal.

The output signal Φ of this up-down counter 8 is supplied to the input terminal of an analog function generator 9, and as a result, the analog function generator 9 outputs sine and cosine signals (sinΦ and cosΦ) corresponding to the counter output Φ. do. Then, the signal sinΦ is supplied to the other input terminal of the analog multiplier 5, and the signal cosΦ is supplied to the other input terminal of the analog multiplier 4.

According to the circuit described above, the output signals of the analog multiplier 4.5 are sinθ·cosΦ and cosθ·5in, respectively.
(p. Therefore, the output signal of the subtracter 6 is 5i
nO°cosΦ-cos(9°sinΦ=5in(0
-Φ) (1) The output signal of the VCo 7 has a frequency corresponding to the value of 5 in (θ-Φ). Since the output signal Φ of the up/down counter 8 goes up or down according to the value of 5in(θ-Φ), the above-mentioned circuit ends up being 5in(θ-Φ).
-Φ) is set to 0, that is, θ=Φ, resulting in a phase-locked loop. In this case, if Φ is set to approximately IO bits, it is possible to obtain a resolution that divides the range of rotation angles O to 2π into 1024.

"Problems to be Solved by the Invention" However, since the conversion circuit shown in Figure 3 is a circuit that mainly uses analog signals, there is a limit to its degree of integration, and currently only hybrid IC types are available. So 50X5
The size is approximately 0 mm.

Further, drift is likely to occur due to fluctuations in the temperature characteristics of the VCo 7 or the power supply voltage, which causes problems in terms of reliability and accuracy.

In addition, the above conventional example was an example of displacement detection for an encoder that detects m degrees, but it can be said that the resolution and accuracy of conventional encoders that detect and measure linear displacement are still sufficient. It was a long song.

Further, it is desirable that the displacement detection for the encoder detects the current displacement immediately when the power is turned on, and it is necessary to take this point into consideration when creating the displacement detection for the encoder.

This invention was made in view of a series of circumstances.Most of the processing is done using digital signals, which makes it possible to eliminate analog circuit elements, allowing for a highly integrated circuit to be constructed on a single monolithic semiconductor substrate. The purpose of the present invention is to provide a displacement detection device for an encoder that can eliminate drift, improve accuracy, and increase resolution, and can output current displacement data immediately when the power is turned on. and(
,ing.

"Means for Solving the Problems" In order to solve the above problems, the present invention provides a scale in which a signal generation source is provided so that only a direct sine wave can be obtained from a predetermined orbit in each fixed section. , each of which is movable relative to the orbit, and outputs a level signal corresponding to the signal strength of the signal source of the orbit;
, and 1. to the wavelength of the iE sinusoidal wave. 90°
an 11th and 2nd sensor that is thrown in a staggered manner;
first and second A/I) converters that convert the output signals of the first and second sensors into digital signals, respectively, and a cosine value corresponding to predetermined data and the first A/I) converter. a function generation multiplication section that outputs the multiplication result of the output signal of the second A/D converter and the sine value corresponding to the predetermined data mentioned in Section 1 and the output signal of the second A/D converter; a subtraction means for detecting the difference between the multiplication results; the subtraction means performs a count corresponding to the difference detected; the count is switched up or down depending on the sign or negative of the difference; and the count result is sent to the function generation multiplication section. a counting means having a preset data input terminal for supplying the predetermined data and for taking in the supplied data; and output signals of the first and second magnetic sensors that are waveform-shaped to have a phase difference of 90°. Create two square waves,
From this rectangular wave, the first and second magnetic sensor detects how many detection sections on the orbit it has passed through, and 6, a passing section that has a preset data input terminal for taking in the supplied data. a number detecting section, and stores the output data of the counting means and the passing section number detecting section when the power is turned off, and stores each of the stored data in each preset of the counting means and the passing section number detecting section when the power is turned on. and non-volatile storage means respectively supplied to data input terminals, and the function generation multiplier, the subtraction means and the counter are configured to form a phase-locked loop, and the 1n input/counter and the number of passing sections are detected The output signal of the section is output as absolute displacement data.

"Operation" Sin and cos signals that do not include a carrier wave are output from each magnetic sensor, and after the signal of the magnetic sensor is converted into a digital signal, it is supplied to a phased lock loop using digital processing. Changes in the magnetization section of the magnetic sensor are outputted from the output signal.

Furthermore, by the non-volatile storage means, output values of the number of moe times are supplied from the counting means and the NFF passage section number detection section respectively when the power is turned on.

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

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, reference numeral 15 denotes a scale, which is composed of a scale 1) that is magnetized in a predetermined orbit by a sine wave of a constant period. The scale I5 of this embodiment is constructed by setting a circular orbit on the surface of a disc-shaped magnetic material and by magnetizing this circular orbit. In addition, +E used for magnetization
The wavelength λ of the string wave is set to about several 1'' to 100 pm. 6 and 17 are old magnetic sensors, and the scale 151', y) Level signal corresponding to the strength of magnetization. (-However, as the magnetic sensor I 6, 17, a sensor whose output signal does not include a carrier wave is used. For example, a half-mass element is used (or a sensor is used. f co, magnetic sensor I7 is 1/4 with respect to magnetic sensor 16
It is set to be shifted by λ (90°). Therefore, the spacing between the magnetic sensors 16 and 17 is set to be (1/4 above m) (where m is a positive integer). The magnetic sensors 16, 17 and the scale 15 are relatively movable, so that if one of them is fixed, the other will rotate. As can be seen from the above, if the signal output by the magnetic sensor I6 is a sine wave, the signal output by the magnetic sensor 17 is a CO8 wave.

Therefore, the interval of one cycle of the magnetization sine wave (scale 15
(from pole to pole of
It becomes sθ.

Next, 18 and 19 shown in FIG. 1 are respectively magnetic sensors I
It is an A/D converter that converts the output signal of 6.17 into a dental signal, and the digitized sin θ and COS θ
is supplied to one input terminal of the digital multiplier 20.21. The output signals of the multipliers 20, 21 are respectively supplied to one and the other input "J" of the digital subtractor 22,
The output signal of 2 is supplied to a digital comparator 23. This digital comparator 23 supplies an amplifier pulse to the counter 24 (8 to IO bit counter) when the subtraction result of the subtracter 22 is positive, and supplies a down pulse to the counter 24 when the subtraction result is negative. supply In this case, counter 2
4 has a preset data input terminal 24a, and when data is supplied to this terminal, it is taken into the interior. Next, 25 is a function generation ROM, which outputs sine and cosine data corresponding to the count value Φ of the counter 24. That is, the function generation ROM 25
Data of sin Φ and COS Φ are stored in advance in the counter, and the stored data is read out sequentially according to the count value Φ. And data C
OSΦ is supplied to the other input of the digital multiplier 20, and digital sinΦ is supplied to the other input 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 is positive, an up pulse is output, and if it is negative, a down pulse is output, and as a result, the count value Φ of the counter 24 increases or decreases in accordance with the value of 5 in (θ-Φ). In addition, the above (1) multiplier 20.2+ and function generator R
The OM 25 constitutes a function generation multiplication section 28. Comparator 23
The counter 24 constitutes a counting means 29.

Next, 26 shown in FIG. 1 is the output signal Φ of the counter 24.
This is a speed detection section that differentiates the difference with respect to time t and outputs the result. The speed detection principle of this speed detection section 26 will be described later.

On the other hand, 30 and 31 shown in FIG.
This is a waveform shaping circuit that converts the output signal of 6.17 into a binary signal of "[-(" level and "L" level) by determining it with a predetermined threshold value. In this case, the waveform shaping circuit 3
The output signals P , , P , of 0.31 are configured to be rectangular waves with a phase shift of π/2, as shown in FIGS. 2(a) and 2(b), respectively. When the movement of .17 is in the positive direction, the pulse P is advanced, and when the movement is in the negative direction, the pulse P2 is advanced. 33
is a direction discrimination circuit that discriminates the moving direction of the magnetic sensor 16, 17. For example, the direction is discriminated depending on whether the level of the pulse P2 at the rising edge of the pulse P1 is "H" or "L". The output signal Sw of the discrimination circuit 33 is supplied to the up/down switching terminal of the counter 3.1, and is also output to the outside.The counter 34 can be turned up or down depending on the signal Sw. While performing the switching, the pulses P are counted.In this embodiment, the magnetic sensor I6.+
When the number 7 is moving in the positive direction, an up count is performed, and when it is moving in the negative direction, a down count is performed. In addition, every time the magnetic sensor I 6.17 rotates the scale 15 once, the 0-fish signal Sz output at that position becomes a 0-point pulse Pz after passing through the waveform shaping circuit 32, and this 0-point pulse Pz is supplied to the reset terminal R of the counter 371 91. As a result, the counter 34 is controlled by the magnetic sensor 16.
, 17 reaches the reference position. Therefore, the count value of the counter 34 is the same as that of the magnetic sensor 16,
Between the current position of 17 and the reference position, the number of magnetic sections (
The value corresponds to the number of magnetic poles). Further, the counter 34 is provided with a preset data input terminal 34a.
When data is supplied to this terminal, it is taken internally. The output signal of the counter 34 and the output signal of the counter 24 are outputted to the outside as absolute position data D out. In this case, the output signal N of the counter 34 is the data D
Configures the data of the upper bits of out and stores it in counter 2.
The count value Φ of 4 constitutes the data of the lower bits of the data D out.

Next, 40 shown in FIG. 1 is a static RAM (for example, CM
OS type). 41 is a power supply monitor circuit that detects the instant when the power is turned on and off, and the static [7A M
A read signal R is supplied to the static INAM 40, and a write signal W is supplied to the static INAM 40 at the moment the power is turned off. In this case, the static RAM 40 stores the count value Φ of the counter 24 and the count value Φ of the counter 34 when the write signal W is supplied, and the count value Φ of the counter 34, and also stores the count value Φ of the counter 24 when the write signal W is supplied. The stored count values Φ and N are supplied to respective preset data input terminals of counter 24 and counter 34, respectively.

Next, the operation of this embodiment with the above configuration will be explained.

First, assuming that the magnetic sensors 16 and 17 start moving in the positive direction, the counter 34 counts up each time the magnetic sensor I6 and 17 passes through a magnetic section (magnetization pitch), and this count value becomes the data It is output to the upper bit of D out. Therefore, if we look at the upper bits of the data D out, we can see how many magnetization sections the magnetic sensors 16 and 17 have passed through, that is, how many pitches from the reference position the magnetic sensors I 6 and 17 are located at the present moment. I understand.

On the other hand, the signal sin output from the magnetic sensors 16 and 17
θ and COSθ are respectively converted into digital signals by A/D converters 18 and 19, and then multiplied by signals CO8Φ and sinΦ output from the function generation ROM 25. and,
It is supplied to the subtracter 22 and 5in (θ-Φ) is detected,
When the value of 5in (θ-Φ) is positive, the count value Φ of the counter 24 increases, and when 5in (θ-Φ) is negative, the count value Φ decreases.

Then, the outputs sinΦ and cosΦ of the function generation ROM are as follows.
Since each count increases or decreases according to the count value Φ, the circuit shown in FIG. 1 ends up being 5 inches (θ-Φ
) is set to 0, that is, θ-Φ, resulting in a phase-locked loop.

Therefore, the count value Φ of the counter 24 indicates where the magnetic sensor 16 is in the magnetization section, in other words,
This is data indicating where the magnetic sensor 16 is located between the magnetic poles. Therefore, the lower part of the data Dout is data indicating a minute position within the magnetization section of the magnetic sensor 16. In this case, since the counter 2.1 is composed of 8 to IO pins I as described above, the resolution of the upper Re Bi & lower position is 1/2 of the magnetization section.
The accuracy is about 56 to 1/2048.

Here, the detection principle of the speed detection circuit 26 will be explained 4-
Ru. As mentioned above, since the count value Φ is controlled to be equal to θ, the count value Φ is equal to the magnetic sensor l6.
! It changes depending on the relative speed of 7. Therefore, the count value (rate of change of p (dΦ/dD is the magnetic sensor l6.
The value corresponds to the relative speed of 17, and the speed detection circuit 26
A speed signal is output from.

Assuming that the operation of the device (not shown) linked to the scale I5 or the magnetic sensor 16°I7 is completed and the power source of the circuit shown in FIG. 1 is turned off, this +-[
At the moment the X source turns off, the power supply monitor circuit 11
The input signal W is supplied to static II, 8M/10.

As a result, at this point (tromagnetic sensor 16.I7
, /) The count values (p and N) corresponding to the displacements are stored in the static RAM 40. Then, when the device (not shown) is driven again and the power is turned on to the circuit shown in FIG. The circuit 41 detects this and supplies the read signal R to the static RAM=10.As a result,
Static RAM 40 supplies previously stored count values Φ and N to preset data input terminals 24a and 34a of counter 24 and counter 34, respectively. As a result, the initial values of the counter 24 and the counter 34 each become the previous value, and as a result, the absolute displacement data Dout is the same as that of the magnetic sensor 16 at the time of restarting the drive. The data corresponds to a displacement of +7. That is, even immediately after the power is turned on, accurate displacement data of the magnetic sensor I6.17 at that time is output.

In this embodiment, since most of the circuits process digital signals, analog circuit elements can be eliminated and a high degree of integration can be achieved on a single monolithic semiconductor substrate. As a result of actually manufacturing the IC, the length, width, and height are 5 x 7 x
It was possible to store it in a furanotobazukeno of about 1 mm. This is because conventional conversion circuits of this type process analog signals using hybrid l' [CL or
When compared to the fact that the size was approximately 50 x 50 x I O (mm), it can be said that this is a dramatic reduction in size.

In addition, when comparing the drift with respect to temperature changes (-20 to +80°C) and power supply voltage changes (±20%) with the circuit shown in Figure 3, it was found that the drift in the circuit shown in Figure 3 On the other hand, there was a drift of ±2 bits in both cases, or in the present application, a low drift of ±1 bit under the same conditions. In this case, since the least significant bit of the data Dout in the present application is the least significant hint of the data indicating a minute position within the magnetization section, there is an advantage that the influence of its drift is extremely small.

Note that the above-mentioned embodiment is an example in which the magnetization trajectory is circular, and is an embodiment in which the present invention is applied to a low-resolution encoder. Of course, it can also be applied to linear type encoders.

"Effects of the Invention" As explained above, according to the present invention, there is provided a scale on which a signal generation source is printed so that only a direct sine wave can be obtained from a predetermined orbit in a fixed section, and outputting a level signal corresponding to the signal strength of a signal generation source on the orbit, which is movable relative to the orbit;
and a first and a second sensor provided so that the phase is shifted by 90 degrees with respect to the wavelength of the sine wave, and the eleventh sensor.
first and second A/D converters each converting the output signal of the second sensor into a digital signal; and multiplication of the cosine value corresponding to predetermined data by the output signal of the first A/D converter. the result, the sine value corresponding to the predetermined data, and the second A
(a function generation multiplication section that outputs the multiplication result of the output signal of the /D converter, a subtraction means that detects the difference between the multiplication results of the function generation multiplication section, and a callan corresponding to the difference detected in the subtraction means) When performing ・, the count is switched between up and down depending on the sign of the difference, and the count result is supplied to the function generation multiplier as the predetermined data, and the supplied data is taken in. a counting means for determining the preset data input terminal;
The output signal of the second magnetic sensor is waveform-shaped so that the phase is 90
°Create two different square waves, and from this square wave, detect how many detection sections on the orbit the first or second magnetic sensor has passed, and capture the supplied data. a passing section number detecting section which connects a preset data input terminal a, and storing the output data of the counting means and the passing section number detecting section 11a when the power is turned off;
and non-volatile storage means for supplying each of the stored data to each preset data input terminal of the counting means and the passing section number detection section when the power is turned on, as well as the function generation multiplication section and the subtraction means. And since the counter is made to be a phase-locked loop, and the output signals of the counter and the passage section number detection section are output as absolute displacement data, when the power stage is turned on and the straight line is turned on, : A +++ point can be obtained that allows instantaneous output of J displacement. Also, since most of the processing is done using digital signals,
Since analog elements can be eliminated, a high degree of integration can be achieved on a single monolithic semiconductor substrate, and the advantages of eliminating drift, improving precision, and increasing resolution can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of an embodiment of this invention, Fig. 2 is a waveform diagram showing the output signal waveform of the waveform shaping circuit 30 and 31 in the same embodiment, and Fig. 3 is a diagram of a conventional displacement detection device. FIG. 2 is a circuit diagram showing the configuration. 15... Scale, 16.17... Magnetic sensor (first and second magnetic sensor), 18.19...
...A/D converter (first and second A/D converter),
22...Subtractor, 24a, 34a...Preset data input terminal, 28...Function generation multiplier, 29...Counting means, 40...State 2
f RAM, 11...power supply monitor circuit, B...battery (40.41.8 above are storage means).

Claims (2)

[Claims] (1) A scale provided with a signal generation source so that only a direct sine wave can be obtained from a predetermined orbit in each fixed section, each of which is movable relative to the orbit, and first and second sensors outputting a level signal corresponding to the strength of a signal from a signal generation source and provided with a phase shift of 90° with respect to the wavelength of the sine wave; , first and second A/D converters that each convert the output signal of the second sensor into a digital signal, and a cosine value corresponding to predetermined data and the output signal of the first A/D converter. a function generation multiplication unit that outputs a multiplication result and a sine value corresponding to the predetermined data and the output signal of the second A/D converter; and detecting a difference between each multiplication result of the function generation multiplication unit. a subtraction means, which performs a count corresponding to the difference detected in the subtraction means, switches up or down the count depending on the sign or negativity of the difference, and supplies this count result to the function generation multiplier as the predetermined data; and a counting means having a preset data input terminal for taking in the supplied data; waveform shaping the output signals of the first and second magnetic sensors to create two-phase rectangular waves having phases different by 90 degrees. From this rectangular wave, the first or second magnetic sensor detects how many detection sections on the orbit it has passed, and also has a preset data input terminal for taking in the supplied data. a detecting section; storing output data of the counting means and the passing section number detecting section when the power is turned off, and transmitting each of the stored data to each preset data input terminal of the counting means and the passing section number detecting section when the power is turned on; and a non-volatile storage means for supplying each of the function generating multipliers, the subtracting means, and the counter to a phase-locked loop, and output signals of the counter and the passing section number detecting section are absolute. A displacement detection device for an encoder, characterized in that it outputs displacement data. (2) The first and second A/D converters, the function generation multiplication section, the subtraction means, the counting means, the passing section number generation section, and the storage means are each mounted on a single monolithic semiconductor substrate. 2. The displacement detection device for an encoder according to claim 1, wherein the displacement detection device is incorporated into a device.