JPH07139968A - Displacement measuring device - Google Patents

Abstract

PURPOSE:To properly inform the generation of abnormality even with respect to gradually advancing abnormality by providing a cumulated tolerance difference memory means storing the value of a measuring error and detecting abnormality from the change tendency of the measuring error. CONSTITUTION:In a displacement measuring device using an encoder A1 to measure the displacement of an object to be measured, a measuring error detection means A2 detects the measuring error at a reference position. When the measuring error detected by the detection means A2 is a predetermined value or less, a cumulated tolerance difference memory means A3 stores the value of the measuring error. A device abnormality judging means A4 judges the generation of device abnormality from the change tendency of the measuring error stored in the memory means A3. Since the measuring error detected at every measurement by the detection means A2 is stored in the memory means A3, the generation tendency of the measuring error can be detected. Therefore, gradually advancing abnormality can be detected and the judging means A4 can inform the generation of abnormality in a relatively slight trouble stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement measuring device, and more particularly to a displacement measuring device having an abnormality detecting means capable of detecting abnormality of the device.

[0002]

2. Description of the Related Art Conventionally, there has been known a displacement measuring device which measures a length or a displacement distance of an object to be measured by using a linear or rotary encoder. 13 and 15 are diagrams showing an example of a conventional displacement measuring device. The displacement measuring device 100 is composed of a displacement measuring device main body 100a and a sensor unit 100b. First, the configuration of the sensor unit 100b will be described.

As shown in FIG. 14, the sensor unit 100b is roughly composed of a pair of optical sensors 180a, 18a.
0b, a reference sensor 180c, a light source 185, an index scale 187, a main scale 189 and the like.

The index scale 187 is arranged on a fixed base, and has a slit portion 187a facing the optical sensor 180a, a slit portion 187b facing the optical sensor 180a, and a reference slit portion 187z facing the reference sensor 180c. Has been done. The slits 187a, 187b, 187z are formed with slits at a predetermined pitch.

Further, the main scale 189 is arranged on a moving object to be measured.
89 also has a slit portion 189a and a reference slit portion 189.
z is formed. Among these, the slit portion 189a has a slit structure in which reflective portions that reflect the emitted light and non-reflective portions that do not reflect the emitted light are alternately formed at equal intervals. On the other hand, the reference slit portion 189z is formed at a position facing the reference sensor 180c when the index scale 187 moves to a predetermined position (reference position) in the direction of the arrow X2 in the figure, and one light beam is emitted. It is composed of a reflecting portion that reflects light. Main scale 189 above
Indicates an arrow A in the figure with respect to the index scale 187.
It is configured to be displaceable in the A1 and A2 directions.

In the above structure, the light emitted from the light source 185 passes through the light passage portion 187d formed on the index scale 187 and is applied to the slit portion 189a of the main scale 189. And the slit portion 189a
The light reflected by the reflection part of the index scale 187
After passing through the slit portions 187a, 187b formed in the optical sensor, the optical sensors 180a, 180b detect the light.

Each slit portion 187a, 187b and 18
Since slits 9a are formed at the same intervals in all of 9a, the light reflected by the slit portion 139a is caused by the relative movement of the scales 187 and 189 caused by the displacement of the index scale 187.
Transmission and non-transmission are repeated at 87a and 187b. And
Only the light transmitted through the slit portions 187a and 187b is detected by the optical sensors 180a and 180b, and an output signal is generated. That is, each slit portion 187a, 187b, 187
z, 189a, 189z and each sensor 180a, 180
b and 180z form a linear encoder.

Further, as described above, the main scale 189
The reference slit portion 189z formed in the reference slit portion 189z when the main scale 189 moves to the reference position.
It is configured to face 7z. Therefore, when the main scale 189 moves to the reference position, the light emitted from the light source 185 is reflected by the reference slit portion 189z, and the reference slit portion 18 formed on the index scale 187 is reflected.
The reference sensor 180z passes through 7z and is incident on the reference sensor 180z, and the reference sensor 180z outputs a reference position signal.

FIG. 13 is an overall block diagram of the displacement measuring device 100. Each of the above sensors 180a, 180b,
The displacement signal detected and generated at 180 z is the signal conversion unit 1.
At 70, waveform shaping and analog / digital conversion (A / D conversion) are performed and the result is input to the displacement measuring device main body 100a. The displacement measuring apparatus main body 100a includes a power supply circuit 102, a central control circuit 110 (hereinafter, referred to as CPU), a read only memory 120 (hereinafter, referred to as ROM), a random access memory 130 (hereinafter, referred to as RAM), an input / output unit 140a.
.About.140c, counting section 150, comparing section 155, displacement detecting section 160, abnormality detecting section 165, and internal bus 101 connecting them. Further, the signal conversion section 170 is connected to the displacement detection section 160, and the display 143 composed of a CRT or the like is connected to the input / output section 1.
40b includes a setting device 145 including a keyboard or the like.
Is connected to the input / output unit 140c, and the input / output unit 140a is connected to an external computer (PC).

In each of the above-mentioned configurations, the power supply circuit 102 is connected to an external power supply, and is composed of a constant voltage circuit for converting the voltage of the external power supply including fluctuations to a constant voltage. This constant voltage is supplied to each circuit described above.
The CPU 110 centrally controls each circuit and arithmetic unit. The ROM 120 is a read-only memory in which various programs necessary for displacement measurement such as an abnormality detection program described later are stored in advance. The RAM 130 is a rewritable memory of information, and stores data, instructions, etc. input by the measurer using the setting device 145. Counting unit 150, comparing unit 155, displacement detecting unit 160, and abnormality detecting unit 165
Cooperate with each other to perform displacement measurement processing and abnormality detection processing in displacement measurement.

The displacement measuring operation of the conventional displacement measuring apparatus will be described.

FIG. 15 shows a signal output from the sensor 180a (A phase) and a signal output from the sensor 180b (B phase).
Phase). As described above, the sensors 180a, 1
80b are arranged separately, and are configured so that the output signals thereof have a phase difference of 90 °. Each sensor 18
The displacement signals generated at 0a and 180b are subjected to A / D conversion and waveform shaping processing in the signal conversion unit 170 as described above. FIG. 16 shows a displacement signal output from the signal conversion unit 170. In the signal conversion unit 170, the sensor 180
PA signal obtained by A / D conversion of the displacement signal output at a, * PA signal obtained by inverting this PA signal, PB signal obtained by A / D conversion of the displacement signal output at sensor 180b, this P signal
A * PB signal is generated by inverting the B signal. Further, the signal output from the reference position sensor 180z becomes one rectangular pulse (Z signal) by being A / D converted by the signal conversion unit 170.

The displacement detecting section 160 has the signal converting section 17
The displacement measurement is performed based on the signal transmitted from 0. PA signal, * PA signal, PB transmitted from the signal converter 170
The signal and the * PB signal are respectively supplied to the slits 187a and 187.
b, output at a cycle corresponding to the formation pitch of 189a,
Moreover, the PA signal, * PA signal and the PB signal, * PB signal are out of phase with each other by 90 °. Therefore, the moving distance of the main scale 189 with respect to the index scale 187 can be calculated by counting the number of pulses of each signal, and the moving direction can be detected by detecting the phase shift state. The pulse number counting process of each signal is performed by the counting unit 150, and the displacement detecting unit 160 calculates the displacement amount based on the counting result processed by the counting unit 150.

On the other hand, it is necessary to set a reference position and count the number of pulses from this reference position when the number of pulses of the signal is counted by the counting section 150. The Z signal output from the reference position sensor 180z is used as a signal for detecting this reference position.

The counting unit 150 is configured to perform up-counting when the main scale 189 moves in the A1 direction in the figure in FIG. 14 and down-counting when it moves in the A2 direction in the figure. Therefore, when the displacement from the reference position is made in the A1 direction, and then the displacement is made in the A2 direction to return to the reference position (this displacement is regarded as one cycle of displacement), the count value must be zero.

However, when measuring the length of the workpiece, the sensor 1 mounted on the index scale 187 is used.
If a miscount occurs for some reason during the relative operation of 80a, 180b, 180z and the main scale 189, which is a movable part, in one cycle, the main scale 18
In some cases, the count value does not become zero when 9 returns to the reference position again. In such a state where a miscount occurs, the displacement amount calculated by the displacement detection unit 160 is different from the regular displacement amount, and therefore it is necessary to notify the measurer of this abnormality occurrence.

Conventionally, as means for informing the measurer of this abnormality occurrence, a permissible miscount value is set in the displacement detecting section 160, and the permissible miscount value and the error after the end of one cycle are set in the comparing section 155. The count values are compared, and if the miscount value after the end of this one cycle is larger than the allowable miscount value, the anomaly detection unit 165 detects this and an anomaly occurs in the display unit 143 via the input / output unit 140b. It was configured to output.

[0018]

However, in the above-mentioned conventional displacement measuring device, when the main scale 189 is displaced for one cycle and returns to the reference position again, even if the miscount value is not zero, this miscount If the value is less than the allowable miscount value, it is not considered to be abnormal. Further, if the value is equal to or less than the allowable miscount value, the structure is not considered abnormal even if the miscount value continues to be non-zero.

Therefore, the sensors 180a, 180b, 1
When the 80z, the signal conversion unit 170, or the like suddenly breaks down, the abnormality can be detected, but when the abnormality gradually progresses due to, for example, a change over time, the abnormality cannot be detected and the abnormality is detected. There is a problem that the detection of the occurrence is delayed and the response to the abnormal occurrence is delayed accordingly.

The present invention has been made in view of the above points, and stores the measurement error at the reference position and detects the abnormality from the change tendency of the measurement error, so that the abnormality gradually progresses. Even if it is, an object of the present invention is to provide a displacement measuring device capable of appropriately notifying the occurrence of an abnormality.

[0021]

FIG. 1 shows the principle of the present invention. As shown in the figure, in order to solve the above problems, in the present invention, in a displacement measuring device that performs displacement measurement of an object to be measured using an encoder (A1), a measurement error detecting means for detecting a measurement error at a reference position. (A2) and, if the measurement error detected by this measurement error detection means (A2) is less than or equal to a predetermined value, the cumulative tolerance storage means (A
3) and an apparatus abnormality determination means (A4) for determining the occurrence of an apparatus abnormality from the change tendency of the value of the measurement error stored in the cumulative tolerance storage means (A3). is there.

Further, the device abnormality determining means (A4) may be configured to output an abnormality advance notice signal when it is detected that the value of the measurement error tends to increase.

[0023]

[Operation] By configuring the displacement measuring device as described above, since the measurement error detected by the measurement error detection means (A2) for each measurement is stored in the cumulative tolerance storage means (A3), the measurement error is generated. Trends can be detected.

Therefore, this can be detected even for an abnormality that gradually progresses, and the apparatus abnormality determination means (A4)
Can notify the occurrence of an abnormality at a relatively mild failure stage.

Further, by making the device abnormality judging means (A4) output the abnormality notice signal only when it is detected that the value of the measurement error is increasing, the measurement in which the abnormality is improving Since the abnormality warning signal is not output when the error value is decreasing, the reliability of the abnormality warning signal can be improved.

[0026]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 2 is a block diagram showing the displacement measuring device 103 according to the first embodiment of the present invention. The displacement measuring device 103 is roughly composed of a sensor unit 100b and a displacement measuring device main body 103a. Of this,
The sensor unit 100b has the same structure as the sensor unit described above with reference to FIG. Therefore, the description of the sensor unit 100b is omitted.

The displacement measuring device body 103a is shown in FIG.
For the displacement measuring apparatus main body 100a described with reference to FIG.
20 includes a tolerance accumulation processing unit 121 and an abnormality detection unit 1
It is characterized in that a cumulative tolerance storage unit 166 is newly added in 65. Hereinafter, a displacement signal (PA signal, *) output from the sensor unit 100b will be described with reference to FIG.
The displacement measuring process executed by the displacement measuring apparatus main body 103a based on the PA signal, PB signal, * PB signal, and Z signal) will be described.

FIG. 3 is a flow chart showing the displacement measuring process executed by the displacement measuring apparatus main body 103a. As will be described later, the abnormality detecting process which is a feature of the present invention is also executed in this displacement measuring process. The displacement measuring process shown in the figure is configured to be activated when the power supply 102 of the displacement measuring device 103 is turned on.

When the power supply 102 is turned on and the displacement measuring process shown in FIG. 3 is started, first in step 1000, a self-diagnosis process is executed. Here, the self-diagnosis process is a process of checking a system program stored in the ROM 120 or checking each sensor 180a, 180b, 180z arranged in the sensor unit 100b.

When the self-diagnosis processing is performed in step 1000, it is determined in the following step 1010 whether the currently designated mode is the program mode or the operation mode. Here, the program mode means that the measurer uses the setting device 1
This is a mode in which initial data is input using 45, and the operation mode is a mode in which displacement measurement is actually performed.

If the program mode is currently designated in step 1010 (this designation is also performed using the setter 145), the process proceeds to step 1040, and the measurement is performed by communicating with the setter 145. The setting device 1
RAM13 which reads the initial data input using 45
Store in 0.

Here, the initial data is, for example, the length of the main scale 189, each slit 189a, 187a,
The pitch of 187b and 187z, the allowable miscount value described later, the maximum displacement amount of the object to be measured, and the like. Step 10 above
The process of 40 is executed until the displacement measuring device 103 is switched to the operation mode.

On the other hand, if it is determined in step 1010 that the operation mode is currently designated, the process proceeds to step 1020 and the process for displacement measurement is executed. Step 1020
Then, various set values (for example, the maximum displacement amount) for the object to be measured, which are input in advance by the measurer from the setter 145, are read from the RAM 130. In the following step 1030, the current count number of the counting unit 150 is set to zero for the time being, and the displacement signal supplied from the sensor unit 100b is prepared.

Here, the current count number of the counting section 150 is reset to zero in the RAM 130 in the first measurement after the power is turned on.
This is because the count number indicating the position of is not stored (since it disappears when the power is turned off), the position of the main scale 189 cannot be known. Therefore, only the first time, the displacement measurement is performed with reference to the position of the main scale 189 when the power is turned on, and after the main scale 189 is displaced to the reference position, the displacement measurement is performed based on this reference position.

In the following step 1050, the sensor unit 1
It is determined whether the reference position signal (Z signal) is input from 00b. If it is determined in step 1050 that the reference position signal is not input, the process proceeds to step 1100, and the main scale 189 detects the displacement direction based on the displacement signal input from the sensor unit 100b. As described above, the PA signal (* PA signal) and the PB signal (* PB signal) input from the sensor unit 100b are 90 °
Since there is a phase shift of, the PA signal (* P
The main scale 189 can detect the displacement direction from the state where the phase shift between the A signal) and the PB signal (* PB signal) occurs.

In this embodiment, the counting unit 150 is configured to count up when the main scale 189 moves in the direction of arrow A1 in FIG. 14, and the main scale 189 moves in the direction of arrow A2. In some cases, it is configured to down count. Therefore,
When it is determined in step 1100 that the moving direction of the main scale 189 is the A1 direction, the process proceeds to step 1120, and the counting unit 150 performs up-counting corresponding to the displacement amount of the main scale 189.

On the other hand, when it is determined in step 1100 that the moving direction of the main scale 189 is the A2 direction, the process proceeds to step 1110, and the counting unit 150 performs the down count corresponding to the displacement amount of the main scale 189. . The count value counted in steps 1110 and 1120 is transmitted to the displacement detection unit 160, and the displacement detection unit 160 calculates the displacement amount of the main scale 189 based on the transmitted count value. The displacement amount calculated by the displacement detection unit 160 is transmitted to the display device 143, and the displacement amount display of the display device 143 is stepped in correspondence with this displacement amount (step 113).
0).

In the following step 1140, the set value (maximum displacement amount) of the object to be measured preset in step 1040,
The actual displacement amount calculated by the displacement detection unit 160 as described above is compared. If the actual displacement amount is equal to or greater than the designated maximum displacement amount, the process proceeds to step 1150 to notify the external computer (PC) of that fact. On the other hand, when it is determined that the actual displacement amount is smaller than the designated maximum displacement amount, the processing returns to step 1050,
The processing from step 1050 onward is repeatedly executed.

On the other hand, if an affirmative decision is made in step 1050, that is, if it is decided in step 1050 that the reference position signal has been input, the processing advances to step 1055,
It is determined whether the reference position signal input this time is the first input after the power is turned on. Then, when it is determined that the reference position signal input in step 1055 is not the first time, the process proceeds to step 1060. The processing after step 1060 is processing for performing abnormality detection, which is a feature of the present invention.

In step 1060, it is determined whether the absolute value of the count number (current value) at the time when the reference position signal is input is equal to or larger than the allowable miscount value. Now
Assuming that no failure or abnormality has occurred in the components of the sensor unit 100b, the count number at the time when the reference position signal is input should be zero. However, when a failure or abnormality has occurred in the components of the sensor unit 100b (for example, the slits 187a and 187).
b, when a defect occurs at 187z),
The count number does not become zero (the count number at this time is called a miscount value).

However, the slits 187a, 187b,
Since 187z is formed with a narrow pitch, a slight amount of miscount value does not pose a problem in displacement measurement. Therefore, the maximum value of the miscount value that does not cause a problem in this displacement measurement is preset as the allowable miscount value,
When it is determined that the miscount value is larger than the allowable miscount value, it is determined that the measured displacement amount is affected, and the abnormality is notified in step 1090. The abnormality notification output by the processing of steps 1060 and 1090 is the same as the abnormality notification that has been conventionally performed. Therefore, an abnormality that gradually progresses cannot be dealt with early by only detecting the abnormality.

The reason for providing the processing of step 1055 is as follows.
When the reference position signal is input for the first time, step 10
This is because the displacement reference of the main scale 189 is not the reference position but the position where the main scale 189 was located when the power was turned on, as described in the process of 30. When the abnormality is notified in step 1090, the process returns to step 1050 to prepare for the subsequent displacement measurement of the main scale 189.

On the other hand, if a negative determination is made in step 1060, the process proceeds to step 1070. Step 1070 is an essential part of the present invention, and the allowable value accumulating process is performed. Here, the allowable value accumulating process means the accumulative allowable difference storing unit 1 provided in the abnormality detecting unit 165 for calculating the above miscount value.
66, and the change tendency of the miscount value is stored in the CPU 110 and the tolerance interruption unit 111 and RO provided in the CPU 110.
This is a process of detecting by the tolerance accumulation processing unit 121 provided in the M120, and outputting an abnormality notice signal when the change tendency of the detected miscount value advances to the side where the abnormality occurs. For details of this allowable value accumulation process,
For convenience of explanation, it will be described later.

If an affirmative decision is made in step 1055, and if the allowable value accumulation processing is carried out in step 1070, the processing advances to step 1080, and the current main scale 189 position is the reference position, so the counter value is set. After being stored in the cumulative tolerance storage unit 166 provided in the abnormality detection unit 165, zero reset is performed to prepare for the subsequent displacement measurement processing in step 1100 and subsequent steps.

Next, the allowable value accumulating process, which is the main part of the present invention, will be described.

As described above, the allowable value accumulating process is a process of outputting an abnormality advance notice signal when the tendency of change of the miscount value stored in the accumulated tolerance storage unit 166 has advanced to the side where the abnormality occurs. Yes, this is the process executed in step 1070 of the displacement measurement process shown in FIG.

In this embodiment, the following three modes will be described as examples of the changing tendency of the miscount value.

Miscount value increases (increase tendency) Miscount value repeats increase and decrease (repetition tendency) Miscount value makes small stepwise changes (small step tendency) FIGS. It is a figure which shows a tendency concretely. 4 shows an increasing tendency, FIG. 5 shows a repeating tendency, and FIG. 6 shows a small step tendency. In each drawing, the horizontal axis indicates the number of times the main scale 189 is displaced to the reference position (since there is the processing of step 1055, the first time the processing after step 1060 is performed), and the vertical axis. Indicates a miscount value.
Further, in the figure, D (1) to D (n) represent the respective miscount values at the 1st time to the nth time. Furthermore, V _A
Is an error value of the counting unit 150 itself (hereinafter referred to as a counting unit error value. Note that this value is always a constant value),
V _B is the allowable miscount value.

As shown in FIG. 4, when the miscount value tends to increase as the number of times increases, the light source 18
5 is deterioration with time, or the entire scale 187 and main scale 189 is contaminated. Therefore, when the miscount value tends to increase, it is possible to deal with this before the occurrence of a large displacement measurement error by notifying the display 143 of the light source deterioration and the abnormality notice of the entire scale contamination. .

Further, as shown in FIG. 5, when the miscount value tends to increase and decrease repeatedly, it means that the index scale 187 and the main scale 189 are partially contaminated. . Therefore, when the miscount value tends to be repeated, by notifying the display unit 143 of the abnormality notice of the partial stain on the scale,
It is possible to deal with this before large displacement measurement errors occur.

Further, as shown in FIG. 6, when the value of the miscount value shows a small stepwise change tendency,
This is the case where the index scale 187 and the main scale 189 have small scratches. In the example shown in the figure, K
An example in which a scratch is generated in the first measurement and the K + 1th measurement is shown. Therefore, when the miscount value shows a small step tendency, it is possible to deal with this before a large displacement measurement error occurs by notifying the display 143 of the abnormality notice of the small scratch occurrence. Become.

FIG. 7 shows the case where the index scale 187 and the main scale 189 have large scratches. When the scales 187 and 189 are seriously damaged, the miscount value is the allowable miscount value V.
_It exceeds _B. In such a case, as described above, the abnormality notification is performed by the processing of step 1060 and step 1090 shown in FIG.

As described above, by detecting the change tendency of the miscount value, even in the case of a gradually progressing abnormality such that the abnormality notification by the processing of steps 1060 and 1090 shown in FIG. 3 is not performed, It becomes possible to detect this, and it is possible to deal with this before a large displacement measurement error occurs. Below, the increasing trend,
Specific detection processing for detecting each tendency of the repeating tendency and the small step tendency will be described with reference to FIGS. 8 to 10.

FIG. 8 shows a process for detecting that the change in the miscount value shows an increasing tendency. When the process shown in the figure is started, first, in step 2000, it is determined whether or not the number of times the miss count value is measured is a predetermined number (n) or more. If the number of measurements has not been performed the predetermined number of times, it is determined that sufficient data for detecting the increasing tendency has not been collected, and the process ends without performing the detection process from step 2010.

On the other hand, if it is determined in step 2000 that the number of measurements has been performed n times or more, the process proceeds to step 20.
The process proceeds to step 10 and reads the latest n pieces of data of the miscount value stored in the cumulative tolerance storage unit 166 and sets them as D (1) to D (n). The initial value of is set (i = 0, j = 0).

In the following step 2030, it is judged whether or not the i-th miscount value D (i) is smaller than the i + 1-th miscount value D (i + 1) measured next time. The state in which affirmative judgment is made in step 2030 is from the i-th time to the i-th time.
For the + 1st time, it means that the miscount value is increasing. Specifically, D (1) and D in FIG.
In the case of (2), D (3) and D (4), D (6) and D (7), etc., a positive determination is made in step 2030.

If a negative determination is made in step 2030, the process proceeds to step 2060 to increment the variable i, and in the following step 2070 it is determined whether or not the variable i has become the data number n, and the variable i is the data number. If not n, the process returns to step 2030 again.

On the other hand, if an affirmative decision is made in step 2030, then the processing advances to step 2040, in which a variable j (hereinafter, this variable j is referred to as the number of increments) is incremented. That is, the value of the increment count j indicates the number of increments of the miss count value in two consecutive miss count measurements.

In the following step 2050, the number of increments j
Is more than half (n / 2) of the total number of times of measurement n (n / 2) or more. If the number of times of increase j is n / 2 times or less, the process proceeds to step 2060 described above, the variable i is incremented, and the variable i is incremented in step 2070.
Is not the number of data n, the process returns to step 2030 again.

If it is determined in step 2050 that the number of increases j is n / 2 times or more, the process proceeds to step 20.
The routine proceeds to 90, where it is judged whether or not the first miscount value D (1) and the nth miscount value D (n) are separated by a predetermined value V _c or more. If an affirmative decision is made in step 2090, the process advances to step 2100 to output a notice of abnormality of light source deterioration or contamination of the entire scale. This allows
The display 143 is informed of the deterioration of the light source or the abnormality of the entire scale dirt.

That is, the increasing tendency detecting process in this embodiment.
Then, increase in the measurement of two adjacent miscount values.
The number of additions is n / 2 or more (more than half of the number of measurements)
And the first miss count value D (1) and the nth miss count value
Count value D (n) is a predetermined value V _cIncreased when the distance is more than
It is configured to judge that there is an increasing tendency.

If a negative decision is made in step 2090,
If the number of increases resulting from the comparison of the two miss count values is less than n / 2 at the stage when the process for the nth miss count value D (n) is completed, the process proceeds to step 2080. The display 143 displays that no advance abnormality has occurred.

FIG. 9 shows a process for detecting that the change in the miscount value shows a repeating tendency. When the process shown in the figure is started, first, in step 3000, it is determined whether or not the number of times the miss count value is measured is a predetermined number (n) or more. If the number of measurements has not been performed the predetermined number of times, it is determined that sufficient data for detecting the change tendency has not been collected, and the process ends without performing the detection process from step 3010.

On the other hand, if it is determined in step 3000 that the number of measurements is n or more, the process proceeds to step 30.
The process proceeds to step 10, and the latest n pieces of data of the miscount value stored in the cumulative tolerance storage unit 166 are read and set as D (1) to D (n). The initial value of is set (i = 0, j = 0).

At the next step 3030, it is judged whether or not the i-th miscount value D (i) is larger than the counter error value V _A. As described above, since the counting unit error value V _A is an error value of the counting unit 150 itself, when a repeating tendency occurs, the counting unit error value V _A is repeatedly increased and decreased centering on the counting unit error value V _A. Therefore, step 3030
The state of being affirmed by means that the miscount value is increasing.

If a negative determination is made in step 3030, the process proceeds to step 3060 to increment the variable i, and in the subsequent step 3070, the variable i is the number of data n.
If the variable i is not the number of data n, the process returns to step 3030.

On the other hand, if an affirmative decision is made in step 3030, the processing advances to step 3040 and the variable j (hereinafter, this variable j is referred to as the number of times of increase) is incremented. That is, the value of the increase count j indicates the number of times the miscount value has increased.

In the following step 3050, the increment number j
Is more than half (n / 2) of the total number of times of measurement n (n / 2) or more. If the number of times of increase j is n / 2 times or less, the process proceeds to step 3060 described above, the variable i is incremented, and the variable i is incremented in step 3070.
Is not the number of data n, the process returns to step 3030 again.

If it is determined in step 3050 that the number of increases j is n / 2 or more, the process proceeds to step 30.
Proceed to 90 and reset the variable i to i = 1 and the variable j'to j '= 0. In the following step 3100, it is judged whether or not the i-th miscount value D (i) is larger than the i + 1-th miscount value D (i + 1) measured next time. The state in which affirmative determination is made in step 3100 is from the i-th time to the i-th time.
For the + 1st time, this means that the miscount value has decreased. Specifically, D (2) and D in FIG.
In the case of (3), D (4) and D (5), D (6) and D (7), etc., a positive determination is made in step 3100.

If a negative determination is made in step 3100, the process proceeds to step 2060 and the above-mentioned step 306
In the same way as 0,3070, the variable i is incremented and the variable i
Is determined to be the data number n. If the variable i is not the data number n, the process returns to step 3100.

On the other hand, if an affirmative decision is made in step 3100, the process advances to step 3110 to increment the variable j '. That is, the value of the variable j ′ after executing the processing of step 3110 indicates the number of times the miscount value has decreased in two consecutive miscount measurements (hereinafter, the variable j ′ is referred to as the decrease frequency).

In the following step 3120, the decrease number j ′ is half (n / 3) of the total measurement number n.
It is determined whether or not there is the above. The number of reductions j'is n /
If it is three times or less, the process proceeds to step 3130, the variable i is incremented, and if the variable i is not the number of data n in step 3140, the process is again performed.
Return to 3100.

In step 3120, the number of reductions j '
Is determined to be n / 3 times or more, the process proceeds to step
Proceed to 3150 to output a notice of abnormality of scale stains. As a result, the display unit 143 is informed of the abnormality of the stain on the scale.

That is, in the increasing tendency detection processing in this embodiment, the miscount value exceeding the counter error value V _A is n / n.
When the number of times of decrease is two or more and the number of times of decrease in the adjacent two miscount values is n / 3 or more, it is determined that the tendency tends to be repeated.

At the stage when the processing for the n-th miscount value D (n) is completed, the miscount value exceeding the counting section error value V _A is less than n / 2 times, and the miscount value for the second time is less than n / 2. As a result of comparison, the number of decrease is n / 3
If it is less than the number of times, the process proceeds to step 3080 to display on the display 143 that no abnormality has occurred.

FIG. 10 shows a process for detecting that the change in the miscount value shows a small step tendency.
When the process shown in the figure is started, first, in step 4000, it is determined whether or not the number of times the miss count value is measured is a predetermined number (n) or more. If the number of measurements has not been performed the predetermined number of times, it is determined that sufficient data for detecting the increasing tendency has not been collected, and the process ends without performing the detection process of step 4010 and thereafter.

On the other hand, if it is determined in step 4000 that the number of measurements has been performed n times or more, the process proceeds to step 40.
In step 4020, the latest n pieces of data of the miscount value stored in the accumulative tolerance storage unit 166 are read and designated as D (1) to D (n), and the variable i is initialized at step 4020. The value is set (i = 0).

In the following step 4030, it is judged whether or not the i-th miscount value D (i) is larger than the counter error value V _A. As described above, since the counting section error value V _A is the error value of the counting section 150 itself, the miscount value D (i) does not exceed the counting section error value V _{A in} the normal state. Therefore, when a negative determination is made in step 4030, the process proceeds to step 4110 and the display 143 displays that no abnormality has occurred.

On the other hand, if an affirmative decision is made in step 4030, each processing of step 4040, step 4050 is executed, and n
Step 40 for all data D (1) to D (n)
Execute 30 judgment processes. Also, in step 4040, step n is performed for all the data D (1) to D (n).
If the determination processing of 4030 is performed, the processing is step
Proceed to 4060 and set the variable i to 1.

In the following step 4070, it is judged whether or not the difference between the i-th miscount value D (i) and the i + 1-th miscount value D (i + 1) measured next time exceeds a predetermined value V _D. It As described with reference to FIG. 6, the scales 187 and 189 (specifically, the slits 187 a and 1
87b, 187z, 189a) has small scratches, the miscount value is stepped up at the scratched position. The predetermined value V _D is set to the step-up amount (this value can be obtained by experiment) of the miscount value that occurs when a scratch occurs. Therefore, when the difference between the miscount value D (i) and the miscount value D (i + 1) exceeds the predetermined value V _D , the scale 18
It can be detected that a small scratch has occurred in 7,189.

If a negative determination is made in step 4070, the process proceeds to step 4080 to increment the variable i, and in the following step 4090, it is determined whether or not the variable i becomes the number of data n, and the variable i is the number of data. If it is not n, the process returns to step 4070 again. On the other hand, if an affirmative decision is made in step 4070, the processing advances to step 4100 and outputs an abnormality notice of small scratch occurrence. As a result, the display 143 is notified of the abnormality of the small scratch occurrence.

When the difference between the miss count value D (i) and the miss count value D (i + 1) does not exceed the predetermined value V _D at the stage where the process of step 4070 is repeatedly executed n times, The process proceeds to step 4110 described above, and displays on the display 143 that no abnormality has occurred.

By executing the allowable value accumulation process as described above, the tendency of change in the miscount value is detected even if a small abnormality occurs that is not reported in the processes of steps 1060 and 1090 (see FIG. 3). By doing so, it is possible to find the cause, and it is also possible to specify the cause of the abnormality. Therefore, it is possible to detect this at a relatively mild abnormality occurrence stage, so that it is possible to deal with it before the measurement result is greatly adversely affected.

In addition, in the increasing tendency detection processing described with reference to FIGS. 4 and 8, the abnormality notice is output only when it is detected that the miscount value is increasing, and the abnormality tends to improve. Since the abnormality warning signal is not output when the error count value is decreasing (that is, the miscount value is decreasing), the reliability of the abnormality warning signal can be improved.

FIG. 11 is a block diagram showing the displacement measuring device 104 according to the second embodiment of the present invention. The displacement measuring device 104 is roughly composed of a sensor unit 100b and a displacement measuring device main body 104a. Among these, the sensor unit 100b has the same configuration as the sensor unit described above with reference to FIG. Therefore, the description of the sensor unit 100b is omitted.

The displacement measuring device body 104a is shown in FIG.
For the displacement measuring device main body 100a described with reference to FIG.
It is characterized in that a scale length comparison processing unit 122 is added to the OM 120 and a scale length setting unit 132 is newly added to the RAM 130.

Hereinafter, the sensor unit 10 will be described with reference to FIG.
0b displacement signal (PA signal, * PA signal,
The displacement measuring process executed by the displacement measuring apparatus main body 104a based on the PB signal, * PB signal, and Z signal) will be described. The displacement measuring process according to the second embodiment shown in FIG. 12 only adds steps 1021 to 1026 to the displacement measuring process according to the first embodiment shown in FIG. Since the processing of the steps 1 to 6 is the same, only the processing of steps 1021 to 1026 which characterizes the second embodiment will be described.

The process shown in the figure is started and the process is stepped.
Proceeding to 1021, in step 1021, the main scale 1 preset from the RAM 130 in the processing of step 1040 is set.
Read the length of 89. Also, in the following step 1022, R
From the AM 130, various set values (especially the maximum displacement amount, etc.) for the object to be measured, which are input in advance by the measurer from the setter 145, are read out.

Then, in step 1024, step 1021
The length of the main scale 189 read out in step 102 is compared with the maximum displacement amount of the object to be measured read out in step 1022. When the maximum displacement amount of the measured object is large with respect to the length of the main scale 189, the displacement measurement cannot be performed on the entire measured object. Therefore, the main scale 1
When the maximum displacement amount of the object to be measured is large with respect to the length of 89, that is, when the affirmative determination is made in step 1024, the abnormality is notified in step 1026.

With this configuration, when the measurer inputs the maximum displacement amount of the object to be measured using the setter 145,
Even when a large value is erroneously input, this erroneous input can be detected by the abnormality notification before the sensor unit 100b is activated. In the present embodiment, the length of the main scale 189 is limited in steps 1021 and 1024, but from the viewpoint of standardizing the production of the displacement measuring device, the measurement effective range is set by the measurer in step 1040. However, depending on this setting value, the sensor unit 100b
It may be configured to limit the operation of.

In the above embodiments, the linear encoder is used as the sensor unit 100b, but the encoder type is not limited to the linear type, but may be a rotary type or other type. The present invention can also be applied to an encoder.

[0093]

As described above, according to the present invention, even if a small abnormality occurs that is not reported in the conventional abnormality detection processing, it can be found by detecting the tendency of change in the measurement error (miscount value). Therefore, it is possible to specify the cause of the abnormality. Therefore, it is possible to detect this at a relatively mild abnormality occurrence stage, so that it is possible to deal with it before the measurement result is greatly adversely affected.

Further, when the abnormality notice is output only when it is detected that the measurement error tends to increase, the abnormality is improving (that is, the measurement error is decreasing). Since the abnormality notice signal is not output to, the reliability of the abnormality notice signal can be improved.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a block diagram showing a displacement measuring device according to a first embodiment of the present invention.

FIG. 3 is a flowchart showing a displacement measuring process executed by the displacement measuring apparatus body in the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of changes in a miscount value in an increasing tendency.

FIG. 5 is a diagram showing an example of changes in a miscount value in a repeating tendency.

FIG. 6 is a diagram showing an example of a change in a miscount value in a small step tendency.

FIG. 7 is a diagram showing an example of a change in a miscount value in a large step tendency.

FIG. 8 is a flowchart showing a process of detecting that the change in the miscount value shows an increasing tendency.

FIG. 9 is a flowchart showing a process of detecting that the change in the miscount value shows a repeated tendency.

FIG. 10 is a flowchart showing a process of detecting that the change in the miscount value shows a small step tendency.

FIG. 11 is a block diagram showing a displacement measuring device according to a second embodiment of the present invention.

FIG. 12 is a flowchart showing a displacement measuring process executed by the displacement measuring apparatus body in the second embodiment of the present invention.

FIG. 13 is a block diagram showing a conventional displacement measuring device.

FIG. 14 is a diagram showing a configuration of a sensor unit.

FIG. 15 is a diagram showing an output waveform of a sensor.

FIG. 16 is a diagram showing a waveform output by a signal conversion unit.

[Explanation of symbols]

 100, 103, 104 Displacement Measuring Device 101 Internal Bus 102 Power Supply 100a, 103a, 104a Displacement Measuring Device Main Body 100b Sensor Unit 110 CPU 111 Tolerance Interrupting Unit 112 Scale Length Interrupting Unit 120 ROM 121 Tolerance Accumulation Processing Unit 122 Scale Length comparison processing unit 130 RAM 132 Scale length setting unit 140a, 140b, 140c Input / output unit 143 Display device 145 Setting device 150 Counting unit 160 Displacement detection unit 165 Abnormality detection unit 166 Cumulative tolerance storage unit 170 Signal conversion unit 180a, 180b sensor 180z reference sensor 185 light source 187 index scale 187a, 187b, 189a slit 187z reference slit 189 main scale

Front page continuation (72) Inventor Hideaki Omori 24 Kiyohara Industrial Park, Utsunomiya City, Tochigi Mitsutoyo Co., Ltd.

Claims (2)

[Claims] 1. A displacement measuring device for measuring displacement of an object to be measured using an encoder, comprising: a measuring error detecting means for detecting a measuring error at a reference position; and a measuring error detected by the measuring error detecting means is a predetermined value. In the following cases, cumulative tolerance storage means for storing the value of the measurement error, and apparatus abnormality determination means for determining the occurrence of the apparatus abnormality from the change tendency of the value of the measurement error stored in the cumulative tolerance storage means. Displacement measuring device characterized by being provided with. 2. The apparatus abnormality determination means outputs an abnormality advance notice signal when detecting that the value of the measurement error tends to increase.
Displacement measuring device described.