JPH04525B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a measuring device, and particularly to an improvement of a device that outputs the amount of displacement of a scale as a sine wave detection signal and a cosine wave detection signal.

[Prior Art] Conventionally, various displacement detection techniques are well known in order to measure the length of an object to be measured using a detector such as a linear scale or a rotary encoder. It is widely used in applications such as positioning devices for machine tools, small digital calipers, and digital micrometers.

In such measuring devices, it is common to convert the amount of displacement of a member that is relatively displaced into a detection signal that can be approximated by a sine wave using photoelectric conversion or a change in capacitance. A detection signal that can be approximated by a cosine wave with a 90° phase difference is required for direction determination and division. Then, 1 of the detection signal
The amount of displacement is accurately measured by dividing the phase angle (360 degrees) of the cycle into a plurality of parts and outputting the value of the detection signal at the time of division as an up-count pulse or a down-count pulse.

In such devices, the conversion period of the sine wave and cosine wave detection signals has been increased as a method to increase the accuracy of displacement measurement in the detector, but in order to increase this conversion period,
The structure of the detector itself must be precisely manufactured, which naturally has its limitations. Therefore, in recent years, the resolution of the pulse generator has been increased in order to increase the measurement resolution of the measuring device itself.

According to this, the phase angle of one cycle of the detection signal from 0 to 360 degrees is divided into a plurality of angles, and each division φ is set as an interpolation angle. A pulse generator is configured to output a count pulse every time the phase θ of the sine wave and cosine wave signals output by the detector reaches a set interpolation angle φ.

Therefore, in order to improve the resolution of the pulse generator, it is necessary to finely divide the detection signal output from the detector and output count pulses.

As such a pulse generator, there is a dividing circuit using resistors (for example, Swiss Patent No. 407569), but when subdividing, a large number of high-precision resistors are required, and the quality and quality of the resistive elements are There are various drawbacks such as inability to maintain a constant accuracy due to variations in characteristics.

Therefore, in order to solve this problem, a pulse generator that automatically calculates the division angle using a digital calculator has been proposed (Japanese Patent Application No. 1973-
78120), one signal period is subdivided and enables accurate displacement measurement.

[Problems to be Solved by the Invention] However, in this conventional device, the signal processing is extremely complicated, so it is not possible to calculate the amount of displacement of the scale, etc. in real time, and it is not possible to calculate the displacement amount of the scale etc. in real time. There was a problem with delays.

As a result, the conventional device has the disadvantage that it cannot be used for feedback control of NC machines, for example, when real-time measurement of displacement is required.

On the other hand, when it comes to measuring equipment, if there is a malfunction in various circuits within the equipment or there is some problem with the measurement itself, the detected waveforms of the sine and cosine waves that are the detection signals will be disturbed, and the measurement accuracy will be significantly reduced. There's a problem.

In other words, in optical measurement devices such as photoelectric encoders, the detected waveform may be disturbed due to dust entering between the optical gratings, the shape of the slits being distorted, mechanical fixing position deviation between the scales, etc. Other measuring instruments also output abnormal detection signals due to various elements, and in this case, it is not possible to obtain a good signal waveform for detecting the amount of displacement of the scale.

In addition, abnormalities may occur due to a phase shift between the sine wave and cosine wave that are the detection signals, a phase shift in the count pulse signal, or a phase shift caused by a mixture of both the detection signal and the count pulse signal. The disadvantage was that a detected waveform was output.

Such an abnormality in the detection signal is extremely difficult to detect, and the more precise the measurement device is, the more it is necessary to eliminate abnormalities in the detection signal that arise from the function and configuration of the device.

As an abnormality detection circuit for detecting such abnormal signals, for example, Japanese Utility Model Publication No. 58-10016 has been proposed, and according to this device, the sine wave and cosine wave signals themselves are compared with a reference voltage, and further, the An abnormal signal is detected by comparing the phase of the subsequent signal with a reference phase signal.

However, this device overlooks relatively small abnormal changes in the signal, such as lamp deterioration (in the case of optical measuring instruments), and accurate detection of abnormal signals is still insufficient.

In addition, this device mainly performs analog processing, which has the disadvantage that it cannot perform immediate processing and cannot detect or warn abnormalities in real time during measurement.

Although the two problems in the measuring device mentioned above have different targets, the present invention focuses on obtaining an efficient minimum circuit configuration to solve these two problems.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to obtain the scale displacement amount in real time using sine wave (sinθ) and cosine wave (cosθ) detection signals, and to It is an object of the present invention to provide a measuring device that accurately warns of abnormalities in real time and performs these functions using a simplified circuit configuration.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a detector that outputs a relative displacement amount as a two-phase detection signal that can be approximated by sinθ and cosθ, and A measuring device that includes a pulse generator that is set with a plurality of interpolation angles φ and outputs a count pulse for measurement at each interpolation angle φ, and an abnormality alarm that warns of an abnormality in each of the detection signals. The creator is
angle data storage means in which a plurality of interpolated angle data sin φ and cos φ set corresponding to the number of divisions of the detection signal are stored in each address; and detection signals sin θ and cos θ output from the detector and the angle Interpolated angle data sinφ and output from the data storage means
a first calculation means that calculates and outputs an output signal Vc of Vc∝sin (θ−φ) based on cosφ, and compares the first calculation value Vc with a predetermined reference value Vs to perform an up count pulse or a down count The abnormality alarm includes a pulse generating means for outputting a pulse, and an address specifying means for sequentially switching and controlling a read address of interpolated angle data every time a count pulse is output, and the abnormality alarm is configured to output a pulse from the angle data storage means. Based on the interpolated angle data and the angle detection signal, Ve = Acos Δθ (Δθ = θ
−φ: phase shift angle), and a comparison means that compares the output of the second calculation means with a reference value indicating an allowable range of a normal detection signal. including, detection signal sinθ and
It subdivides cosθ according to the set interpolation angle data and outputs up-count pulses or down-count pulses, and at the same time
It is characterized by outputting an abnormality alarm signal when the signal of Acos Δθ is out of the permissible range.

[Operation] According to the above configuration, sinφ and cosφ at the interpolation angle φ stored in the angle data storage means are output, and the first calculation means calculates Vc=Asinθcosφ.
−Acosθ·sinφ=Asin(θ−φ) is calculated.

Then, the pulse generating means compares the output value Vc of the first calculating means with the reference value Vs and outputs a count pulse.

In this case, assuming that the reference value Vs = 0, a count pulse will be output when the output Vc of the first calculation means is 0 (because θ - φ = 0), but when θ is If θ increases, an up-down pulse is output when the first calculated value Vc changes from a negative value to 0, and if θ decreases, the first
When the calculated value Vc changes from a positive value to 0, an up-down pulse is output.

In this case, by appropriately selecting the interpolation angle φ, it is possible to detect the scale displacement amount with high accuracy by subdividing the phase angle.

On the other hand, in the abnormality alarm circuit, the second calculation means performs a predetermined calculation using the data of -sinφ and cosφ output from the angle data storage means used in the pulse generator.

In this case, the data of −sinφ is processed by the inverting amplifier.
After being converted to sinφ, Ve=Asinθ・sinφ+
Performs the calculation of Acos and cosφ.

The above equation can be expressed as φ=θ+Δθ when there is a phase shift angle Δθ between the phase angle θ and the interpolation angle φ, and when this is substituted into the above equation and calculated, Ve=
Acos Δθ (details will be described later).

Here, the measured value is working normally and the phase angle θ
When there is no phase shift angle between and interpolation angle φ,
Since Δθ=0, cosΔθ=1 and Ve=A
It is.

On the other hand, if there is some kind of abnormality in the measuring device, etc., and there is a phase shift, Δθ>0, Δθ<0
Therefore, cosΔθ<1 and Ve<A (when there is no abnormality in the amplitude of the detected waveform).

Further, if there is no abnormality in the phase shift but there is an abnormality in the amplitude of the detection signal, the value of the amplitude A fluctuates.

Therefore, when there is some abnormality in the detection signal, the amplitude of the output signal Ve of the calculation means will fluctuate, and by detecting this fluctuation,
It is possible to determine whether there is an abnormality in the detection signal.

This determination is made by a comparison means, which sets an allowable range for determining whether or not there is an abnormality.

For example, if the reference amplitude of the detection signal is As, the range from the reference value As-ΔA to As+ΔA is considered to be an allowable range, and anything outside of this range is considered to be abnormal. Therefore, in the comparison means, the Ve=
An abnormality alarm signal will be output when the AcosΔθ signal is outside the allowable range.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a circuit block diagram of a measuring device according to the present invention, and FIG. 2 shows an overall diagram of the measuring device.

In FIG. 2, the detector 10 is composed of an optical or capacitive linear scale, a rotary encoder, etc., and converts the amount of displacement of the scale into two detection signals sin θ and cos θ having a phase difference of 90 degrees and outputs them. Note that the detection signal processed in the present invention is
Detection signals such as triangular wave signals approximated by sin θ and cos θ can also be applied.

Further, the pulse generator 12 adjusts the phase angle θ from 0 to
The phase angle θ of the detection signals sin θ and cos θ that are subdivided in a 360 degree range and output from the detector 10 is
A count pulse is output to the counter 14 every time the set interpolation angle φ is reached.

Therefore, by sequentially counting up count pulses and down count pulses input to the counter 14, the amount of displacement of the circuit can be measured.

Furthermore, the abnormality alarm 16 inputs the detection signals sinθ and cosθ from the detector 10, and also receives the detection signals sinθ and cosθ from the pulse generator 12.
Up-count pulses and down-count pulses are input from the circuit, and arithmetic processing is performed from these signals to warn of abnormalities in the detection signal.

The characteristic feature of the present invention is that it can accurately determine the amount of scale displacement in real time, and provide an accurate and real-time warning of abnormalities in the detection signal using an efficient and simplified circuit configuration. In the embodiment, storage units 30 and 32 as angle data storage means and D/A converter 3 are included.
4 and 36, and a reversible counter 26 as an addressing means.

The pulse generator and the abnormality alarm will be explained in order below.

About the pulse generator As shown in FIG. 2, the pulse generator 12 of the embodiment divides the angle θ into 10 equal parts in the range of 0 to 360 degrees, and divides each divided angle φ ₀ , φ ₁ ...φ ₉ into 10 equal parts. It is used as an interpolation angle.

Then, the detection signal output from the detector 10
The phase angle θ of sinθ and cosθ is the set interpolation angle φ
The circuit is configured to output a count pulse every time the .

Therefore, in the pulse generator 12 of the embodiment, when the phase angle θ of the detection signal changes in the range of 0 to 360 degrees,
A total of 10 count pulses will be output.

The specific configuration will be explained in detail below.

First, each detection signal output from the detector 10
sin θ and cos θ are input to the first arithmetic circuit 24 via amplifiers 20 and 22 with an amplification factor of A, respectively.

Furthermore, the angle data storage circuit 28 outputs predetermined interpolated angle data to the first arithmetic circuit 24 .

In the embodiment, this angle data storage circuit 28
are a first storage unit (ROM) 30, a second storage unit (ROM) 32, a first D/A converter 34, a second
and a D/A converter 36.

Inside the first and second storage units 30 and 32,
Cosine waves corresponding to the interpolation angles φ0 to φ9 respectively
cosφ and sine wave -sinφ are sequentially stored at predetermined addresses.

The first storage unit 30 stores the reversible counter 2
Based on the address signal output from 6, the cosine wave signal cosφ stored at the corresponding address is output to the first arithmetic circuit 24 via the D/A converter 34.

Similarly, the second storage unit (ROM) 32
Based on the address signal output from the reversible counter 26, the sine wave signal -sinφ stored at the corresponding address is outputted to the first arithmetic circuit 24 via the D/A converter 36.

The first arithmetic circuit 24 is formed to calculate and output a signal Vc expressed by the following equation based on each data thus input.

Vc=Asin(θ−φ)...(1) In the embodiment, this first arithmetic circuit 24 is
It includes a first multiplier 38, a second multiplier 40, and an adder 42.

The first multiplier 38 is connected to the amplifier 20
and a signal output via the D/A converter 34
Asinθ and cosφ are multiplied and Asinθcosφ is calculated and output.

Further, the second multiplier 40 multiplies the signal Acosθ outputted via the amplifier 22 and the signal −sinφ outputted via the D/A converter 36, and -
Compute and output Acosθsinφ.

Then, the adder 42 adds the signals output from the first and second multipliers 38 and 40 according to the following equation, and sends the signals to the pulse generation circuit 44 to add the signals output from the first and second multipliers 38 and 40 to the first
The signal Vc expressed by the formula is calculated and output.

Vc=Asinθcosφ−Acosθsinφ=Asin(θ−φ) In the present invention, this pulse generation circuit 44 is
It is configured to output a count pulse when the calculated value Vc exceeds a predetermined reference value Vs.

In the embodiment, this pulse generating circuit 44 includes:
Comparator 46, oscillator 48, first AND gate 5
0 and a second AND gate 52.

The comparator 46 has a predetermined reference value.
Vs is set, and when the signal Vc calculated and output from the adder 42 exceeds the reference value Vs, an H level signal is output.

Further, the first AND gate 50 performs an AND operation on the output of the comparator 46 and the clock pulse CP output from the oscillator 48, and outputs an up count pulse.

Further, the second AND gate 52 and the comparator 4
The output of the oscillator 48 is inverted and inputted, and this input signal and the clock pulse CP outputted from the oscillator 48 are ANDed to output a downcant pulse.

A characteristic feature of the pulse generator of the present invention is that the read addresses of the first storage section 30 and the second storage section 32 are sequentially switched and controlled each time an up-count pulse or a down-count pulse is output. It's about doing.

For this reason, in this embodiment, the reversible counter 26 is used as the addressing means, and the up count pulse output from the first AND gate 50 and the second AND gate 52 is applied to the reversible counter 26. and a down count pulse are respectively input.

Therefore, each time the up-count pulse or down-count pulse is output, the reversible counter 26 increments or decrements the added value, and sets the read addresses of the first and second storage units 30 and 32 to the adjacent one. The switching control will be performed to the address of .

By the way, it is necessary to form the reversible counter 26 used as an addressing means in this way so as to cyclically count a value equal to the number of interpolation angle data stored in the storage units 30 and 32. If 10 pieces of interpolated angle data are stored in , it is necessary to use a method that counts values from 1 to 10 and then starts counting again from 1.

The present embodiment has the above configuration, and its operation will be explained next based on FIG. 3.

First, the detection signal output from the detector 10
Assume that the phase angle θ of sin θ and cos θ is between interpolation angles φ ₅ and φ ₆ , for example.

At this time, the first storage section 30 and the second storage section 32 output a cosine wave signal cosφ ₆ and a sine wave signal sinφ ₆ based on the interpolation angle φ ₆ according to the address signal output from the reversible counter 26. are output respectively.

Therefore, the signal output from the adder 42 at this time
Vc becomes Vc=Asin(θ−φ ₆ ).

At this time, the phase angle θ is φ ₅ < θ < φ ₆ , so
The calculated value Vc becomes a negative value, and becomes Vc=0 when θ= _φ6 .

Therefore, if the reference value Vs of the comparator 46 is set to 0, an H level signal is output from the comparator 46 at the same time as θ= _φ6 , and the clock pulse
An up count pulse is output from the first AND gate 50 in synchronization with CP.

In this way, according to the device of the embodiment, almost at the same time when the phase angle θ of the detection signals sin θ and cos θ becomes θ=φ ₆ , the first AND gate 50 outputs an up count pulse, and the up count pulse is outputted from the counter 26. Address signal is incremented.

Thereafter, the first and second ROMs 30 and 32 output a cosine wave signal cosφ ₇ and a sine wave signal sinφ ₇ based on the interpolation angle φ ₇ , and the signal Vc output from the adder 42 again takes a negative value. Then, the comparator 46
The output of is also switched to L level.

In this way, according to the device of this embodiment, the phase angle θ of the detection signals sin θ and cos θ is the interpolation angle φ ₀ ,
Since an up-count pulse is output every time it passes through φ ₁ , φ ₂ , etc., by counting this up-counter pulse using the reversible counter 26, it is possible to accurately measure the amount of displacement of the scale, etc. Become.

Furthermore, in the above embodiment, the case where the phase angle θ of the detection signals sin θ and cos θ changes in the positive direction was explained as an example, but conversely, the scale is adjusted so that the phase angle θ changes in the negative direction. If the scale moves, a down count pulse corresponding to the amount of displacement of the scale will be output from the second AND gate 52.

In addition, in this embodiment, for example, when the phase angle θ is in the region between the interpolation angles φ ₅ and φ ₆ , φ ₆ is set as the interpolation angle. The present invention is not limited to this, and in this case, it is also possible to set the interpolation angle to _φ5 . In this case,
At the same time that the phase angle θ becomes θ= _φ5 , the comparator 46
The reference value Vs is set so that an H level signal is output from
All you have to do is set .

About the abnormality alarm The characteristics of the abnormality alarm of the present invention are as follows:
A cosine wave signal was obtained at the phase difference angle between the interpolation angle and the phase angle of the detection signal, and this was used as a signal for determining whether or not the detection signal was abnormal. at interpolation angle φ
Angular data storage means for storing sinφ and cosφ and addressing means for reading the data from this storage means are required.

The present invention is characterized in that the angle data storage means and addressing means of the pulse generator are utilized in an abnormality alarm to provide an efficient circuit configuration.

Therefore, the interpolation angle data cosφ and sinφ of the first and second storage units 30 and 32 are the same as those of the first and second D/
The second arithmetic circuit 54 via the A converters 34 and 36
is supplied to.

This second arithmetic circuit 54 is connected to the second D/A
an inverting amplifier 56 that inverts the output of the converter 36;
A third multiplier 58 multiplies the output of the inverting amplifier 56 by the output of the amplifier 20, a fourth multiplier 60 multiplies the output of the D/A converter 34 and the output of the amplifier 22, and an adder 38 that adds both the output of the third multiplier 58 and the output of the fourth multiplier 60, and
Find the signal of AcosΔθ.

Further, in the present invention, a comparison circuit 64 determines whether the detection signal (waveform) is abnormal or not, and this comparison circuit 64 includes a first comparator 66, a second comparator 68, and , these two comparators 66,6
Semi-fixed value setter 7 for setting the reference value in 8
0,72 are provided. This semi-fixed value setter 70
is set to the upper limit of the allowable range for determining that the detection signal is normal, that is, A _S +ΔA, and the semi-fixed value setter 72 is set to a value that is the lower limit of the allowable range, A _S −ΔA. There is.

Therefore, the first comparator 66 detects the detected waveform when the output of the adder 62 exceeds the upper limit A _S +ΔA value, while the second comparator 68 detects the detected waveform when the output falls below the lower limit A _S −ΔA value. Outputs an alarm signal to warn that there is an abnormality. And this alarm signal is the or gate 74
is output from.

The present invention has the above configuration, and its operation will be explained below.

As described above, the present invention provides a warning of an abnormality in the detection signal by determining AcosΔθ at a phase shift angle Δθ, and AcosΔθ is theoretically determined by the following arithmetic expression.

Ve=Asinθ・sinφ+Acosθ・cosφ =Acos(φ−θ) =AcosΔθ ...(2) Applying the above equation (2) to each component of the circuit, the output of the amplifier 20 is Asinθ, which is the third The output of the first storage section 30, which is supplied to the multiplier 58 and output by the count pulse of the reversible counter 26, is -sinφ, and the output of the first storage section 30 is converted into an analog signal. Later, it is converted into sinφ by an inverting amplifier 56. and,
The sinφ signal is provided to a third multiplier 58. Therefore, the third multiplier 58 calculates Asinθ·sinφ.

On the other hand, the output of the amplifier 22 is A cos θ, which is supplied to the fourth multiplier 60, and the output of the second storage unit 32, which is output by the count pulse of the reversible counter 26, is cos φ, which is supplied to the fourth multiplier 60. The output of the storage section 32 is converted into an analog signal and then supplied to the fourth multiplier 60. Therefore, the fourth multiplier 60 calculates Acos·cosφ.

The signals from both the third multiplier 58 and the fourth multiplier 60 are then supplied to the adder 62, where the calculation Ve=Asinθ·cosθ+Acosθ·cosφ is performed. Therefore, from the adder 62, Ve=
Acos Δθ, that is, a cosine wave signal at the phase shift angle Δθ is output.

Next, the output of the adder 62 is input to the first and second comparators 66 and 68 in the comparison circuit 64, where a comparison is made to determine whether the detection signal is within the allowable range. be exposed.

That is, in the first comparator 66, the adder 62
The second comparator ₆₈ compares whether the output AcosΔθ exceeds the value of A _S +ΔA.
A comparison is made to see if it is below the value of Δθ, and as shown in FIG. 4, in the case of a normal detection signal (waveform), the peak value of the output voltage of the adder 62 is As+ΔA. and A _S -ΔA, which is the tolerance region 100. This is because in this case, Δθ≈0, Ve=Acos Δθ≈A, and the peak value remains constant.

Therefore, when it is normal, the comparators 66, 6
No alarm signal is output from any of the 8.

On the other hand, if there is an abnormality in the detection signal, Acosθ＞
A peak value exists in the abnormal region 200 in the range of A _S +ΔA or Acosθ<A _S −ΔA.

For example, if there is a phase shift in the phase angle or interpolation angle of the detection signal, Δθ≠0 and Ve=
A cos Δθ<A _S ΔA, and the peak value of the output voltage of the adder 62 falls into the abnormal region 200a. Also, if there is an abnormality in the amplitude of the detected waveform, Δθ≒0, but the amplitude A changes and Ve=A>
When A _S +ΔA, the peak value is 200b, while
When Ve=A<A _S −ΔA, the peak value is 200a
I will be coming. Therefore, when the output voltage of the adder 62 is in the abnormal region 200b, a signal of a predetermined voltage is output from the first comparator 66, and when it is in the abnormal region 200a, the second comparator 68 outputs a signal of a predetermined voltage.

The first and second comparators 66 and 68
The output is supplied to the OR gate 74, and when any signal is input to the OR gate 74, an abnormality alarm signal is output.

Note that the detection signal processed in the present invention is sinθ,
Any waveform that can be approximated by cosθ may be used; for example, a triangular wave with different phases may be used. In this case, an abnormality alarm is output by setting ΔA, which is the permissible limit of the amplitude, a little larger.

[Effects of the Invention] As explained above, according to the present invention, a simplified circuit can perform accurate real-time measurement of physical displacement amount and real-time abnormality alarm that does not miss even small abnormalities. This can be done efficiently depending on the configuration.

As a result, the device of the present invention has a detection signal sinθ and
The number of divisions of cos θ can be set arbitrarily, and compared to conventional resistance divider circuits, it is not affected by variations in circuit components, so the division accuracy can be greatly improved.

Since it is possible to output count pulses in real time based on changes in the phase angle θ of the detection signals sin θ and cos θ, it is extremely useful as a displacement measurement device for feedback control of NC machines and other real-time measurement devices. It becomes possible to use it widely.

Furthermore, the device of the present invention detects temporary or permanent decline in the signal due to lamp breakage, deterioration, or dust in the detector in the case of optical measuring instruments, by issuing an alarm of the abnormal detection signal. In the case of electrical measuring instruments, it is possible to detect cable breakage or permanent deterioration of each circuit member.

In particular, it is possible to detect failures in the pulse generation circuit, temporary or permanent changes in the signal due to frequency measurement deterioration of the measuring device, etc., thereby preventing detection errors in precision measurements and ensuring good measurement performance. It becomes possible to make it happen.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram explaining the measuring device according to the present invention, FIG. 2 is an overall diagram of the measuring device according to the present invention, third is a timing chart of the pulse generator shown in FIG. FIG. 3 is a graph diagram illustrating the operation of a comparison circuit. 10...Detector, 12...Pulse generator, 14
... Counter, 18 ... Angle data storage circuit, 2
6...Reversible counter as addressing means,
30...first storage unit (ROM), 32...second
storage unit (ROM), 34...first D/A converter, 36...second D/A converter, 38...first
Multiplier, 41... Second multiplier, 42, 62...
...Adder, 44...Pulse generation circuit, 54...Second arithmetic circuit, 58...Third multiplier, 60...
Fourth multiplier, 64...comparison circuit.

Claims (1)

[Claims] 1. A detector that outputs a two-phase detection signal that can approximate the amount of relative displacement by sin θ and cos θ, and a plurality of interpolation angles φ are set for the detection signal, and a plurality of interpolation angles φ are set for each interpolation angle φ. In the measuring device, the pulse generator includes a pulse generator that outputs count pulses for measurement, and an abnormality alarm that alarms abnormalities in each of the detection signals. angle data storage means in which a plurality of interpolated angle data sinφ and cosφ are stored at each address; detection signals sinθ and cosθ outputted from the detector; and data interpolated angle data outputted from the angle data storage means. Vc∝sin(θ−φ) based on sinφ and cosφ
a first calculating means for calculating and outputting an output signal Vc, a pulse generating means for comparing the first calculated value Vc with a predetermined reference value Vs and outputting an up-count pulse or a down-count pulse; and a pulse generating means for outputting a count pulse. an address specifying means for sequentially switching and controlling the readout address of the interpolated angle data each time the angle data is read, and the abnormality alarm detects the interpolated angle data based on the interpolated angle data and each detection signal output from the angle data storage means. Ve= including signal amplitude amplification factor A
A second calculation means for calculating an output signal Ve that can be approximated to AcosΔθ (Δθ=θ−φ: phase shift angle), and comparing the output of the second calculation means with a reference value indicating an allowable range of a normal detection signal. and a comparison means for subdividing the detection signals sin θ and cos θ according to the set interpolation angle data and outputting up-count pulses or down-count pulses, and detecting that the signal of A cos Δθ at the phase shift angle is out of the permissible range. A measuring device characterized in that it outputs an abnormality alarm signal when an abnormality occurs. 2. In the apparatus according to claim 1, the angle data storage means includes a first storage section that stores interpolated angle data sinφ, a second storage section that stores interpolated angle data cosφ, and a second storage section that stores interpolated angle data cosφ. and a first converting the output signal from the second storage unit into a digital-to-analog converter.
and a second D/A converter, and the first calculation means includes first and second multipliers that multiply and output the outputs of the first and second D/A converters and the detection signal. and an adder that calculates the sum of both the first and second multiplier outputs, and the second calculation means includes an inverting amplifier that inverts the second D/A converter output, and an adder that calculates the sum of both the first and second multiplier outputs. third and fourth outputs that multiply the inverting amplifier output and the first D/A converter output by the detection signal;
A measuring device comprising: a multiplier; and an adder for calculating the sum of both the third and fourth multiplier outputs.