JPH0653805A - Displacement detecting sensor - Google Patents

Abstract

PURPOSE:To display a reference position set up by a user in a displacement detecting sensor as a reference and to input an object detecting position corresponding to the reference position. CONSTITUTION:A sensor part 1 is provided with an oscillation circuit 4 having an oscillation coil 3 and a thermistor 5 to be a temperature sensor and a CR oscillation circuit 6 is connected to the thermistor 5. Counters 9, 10 for measuring the frequency of respective oscillation circuits 4, 6 are connected. A temperature correction table memory 13 for correcting the outputs of the counters 9, 10 corresponding to respective temperatures is previously prepared and the count value of the counter 9 is corrected based upon the contents of the memory 13 to detect a distance up to an object. Position data inputted by a user are subtracted from measured position data and the subtracted value is displayed by a scale from the reference position set up by the user.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement detection sensor for non-contact detection of displacement due to approach of an object to be detected,
In particular, the present invention relates to a displacement detection sensor which is characterized by its threshold input method and display.

[0002]

2. Description of the Related Art A conventional high-frequency oscillation type proximity switch has an oscillation circuit provided with an oscillation coil and oscillates at a constant frequency. I am trying to detect.
For example, in the proximity switch shown in FIG.
An oscillating coil 102 is provided to oscillate at a constant frequency, and its output is given to a detection circuit 103. The detection circuit 103 detects the output, converts it into a DC level signal, and linearizes it by a linearizer 104 to obtain a signal corresponding to the distance. Then, in the comparison circuit 105, this signal is discriminated based on the set value set by the user, so that the signal is output when the object comes close to a specific distance.

[0003]

In such a conventional proximity switch, however, the change in temperature is larger than the change in the conductance of the oscillation coil 102 due to the arrival of an object. Therefore, in order to eliminate the effect of temperature, a temperature compensating element 107 such as a thermistor is connected to the feedback circuit section of the oscillation circuit 101 to perform temperature compensation. However, variations in the conductance temperature characteristics of the oscillation coil 102 and variations in the thermistor constants have an effect, which makes it difficult to obtain a proximity switch that is highly accurately compensated for temperature.

There is also a demand for a sensor for discriminating an area to be output by designating a moving range from a detection switch in addition to the presence / absence of an object. In the conventional proximity switch, if an output is set when an object arrives within a predetermined range, it is necessary to set a plurality of thresholds, and it is necessary to set a positional relationship to the object. Become. Therefore, it is difficult to set these accurately.

The present invention has been made by paying attention to such a conventional problem, and there is no influence of variations in the temperature characteristics of the oscillation coil, variations in the temperature of the thermistor, etc., and the reference position set by the user. An object of the present invention is to provide a displacement sensor that can detect the displacement of an object from the body with high accuracy.

[0006]

According to a first aspect of the present invention, there is provided a first oscillating circuit having an oscillating coil, the oscillating frequency of which changes when an object to be detected approaches the oscillating coil, and a first oscillating circuit. A second oscillating circuit whose oscillating frequency changes according to changes in the temperature of the circuit, first and second counting means for counting the oscillating frequencies of the first and second oscillating circuits, and a first oscillating circuit in the operating temperature range. A first count table is generated by calculating a calculation value to be obtained by the second counting means corresponding to each temperature of the oscillator circuit, and a first count table is generated, and a first count table is generated corresponding to each temperature of the first oscillator circuit in the operating temperature range. Count values obtained by the first and second counting means are respectively generated as second and third counting tables, and second and third counting tables are generated.
By proportionally distributing the data of the counting table of No. 1, the calculated value to be obtained from the first counting unit corresponding to the calculated value at each temperature of the first table is calculated, and the calculated value of the first counting unit is calculated from each calculated value. By subtracting the reference count value N _R and calculating the fourth count table of the correction value ΔN at each temperature,
A correction table memory using the obtained first and fourth counting tables as correction table data, and a correction value ΔN corresponding to the count value M _T obtained by the second counting means based on the correction table are calculated by proportional distribution. Temperature correction processing unit, correction value ΔN and reference value N obtained from the temperature correction processing unit
_R and the addition means for adding the count value N of the first counting means
First to subtract the addition value (ΔN + N _R ) of the addition means from s
Subtraction unit, a displacement calculation processing unit that linearizes the output Nd obtained by the first subtraction unit with respect to the distance d from the oscillation coil to the object, and a first input that inputs the displacement reference position as displacement data. Means, a second subtraction means for subtracting the value of the reference position input by the first input means from the linearized output, and a display means for displaying the output of the second subtraction means. It is characterized by.

According to a second aspect of the present invention, the second input means for inputting the range (IN2) of the deviation from the reference position (IN1) input by the first input means and the second subtracting means are provided. Comparing means for judging whether or not the deviation is within this range based on the output and the range of the deviation inputted by the second input means; and outputting means for outputting a comparison signal of the second comparing means.
It is characterized by including.

According to a third aspect of the present invention, the second input means for inputting the displacement from the reference position input by the first input means, the output of the second subtracting means and the second input means are used. It is characterized by comprising a comparison means for comparing the input displacement and an output means for outputting the comparison signal of the second comparison means.

According to a fourth aspect of the present invention, there is provided switching means for switching between the first and second modes for setting the range or displacement of the deviation from the reference position input from the first input means, and the switching means for switching between the first and second modes. When the first mode is selected, the range of the deviation from the reference position input by the second input means is input, and when the second mode is selected by the switching means, it is input by the first input means. Controlled by the second input means for inputting the displacement from the reference position and the switching means,
It is characterized by further comprising: comparison means for comparing the output of the second subtraction means and the range or displacement of the deviation input by the second input means; and output means for outputting the comparison signal of the comparison means. It is a thing.

[0010]

According to the invention of claim 1 of the present application having such a feature, the first count table is generated by first calculating the calculation value to be obtained by the second counting means by calculation. Then, the temperature of the first oscillation circuit is continuously changed within the use range, and the count values obtained from the first and second counting means corresponding to each temperature are used as second and third counting tables. Then, by calculating the proportional distribution of the data of the second and third counting tables, the calculated value to be obtained from the first counting means corresponding to the counted value at each temperature of the first counting table is calculated, and the reference count value N The fourth table of the correction value ΔN is obtained by subtracting _R. A correction table is generated by using the fourth counting table of ΔN and the first counting table as correction table data. Then, using this correction table, the count value M obtained from the second counting means
_The correction value ΔN corresponding to the temperature at that time is obtained from _T. Then, the distance information Nd that does not depend on the temperature is obtained by adding it to the reference value N _R and subtracting it from the count value N _S from the first counting means. Further, this data Nd is linearized by the displacement calculation processing section. Then, the linearized displacement data is subtracted from the reference position data set by the user obtained from the first input means, and linearized so that the displacement from the reference position set by the user is displayed by the display means. ing.

In the invention of claim 2 or 3, the deviation range or displacement from the reference position is input by the second input means, the deviation range or displacement is compared by the comparing means, and the comparison is made. I am trying to output a signal.
Further, in the invention of claim 4 of the present application, the switching means switches the first and second modes of claims 2 and 3.

[0012]

1 is a block diagram showing the overall construction of a displacement detecting sensor according to an embodiment of the present invention. In this figure, this displacement detection sensor is shown as a sensor unit 1 and other electronic circuit unit 2
Composed of. The sensor unit 1 is provided with a first oscillating circuit 4 having an oscillating coil 3 and a temperature detecting element such as a thermistor 5 as shown in the figure. Here, it is assumed that the sensor unit 1 has an oscillating coil 3 on its front surface, and that when the object approaches, the oscillating frequency f _S changes depending on the distance to the object.

The electronic circuit section 2 is provided with a second CR oscillator circuit 6 having the thermistor 5 as one resistance.
The oscillation frequency of the CR oscillation circuit 6 and f _T. The outputs of the oscillator circuit 4 and the CR oscillator circuit 6 are given to the frequency dividing circuits 7 and 8, respectively. The frequency dividing circuits 7 and 8 divide the oscillation frequency by 1 / Ks and 1 / Kt, respectively.
s and Kt can be set. The frequency-divided outputs are given to the counters 9 and 10, respectively. Further, the electronic circuit section 2 has a reference clock oscillator 11 having a constant frequency, for example, a clock frequency of 10 MHz and 4000 Hz, and the respective clock signals are given to the counters 9 and 10. The counters 9 and 10 are counters for counting the number of clocks of the reference clock oscillator 11 by using the frequency-divided output as a gate signal, and constitute the first and second counting means together with the frequency dividing circuits 7 and 8 and the reference clock oscillator 11, respectively. is doing. Here, the count value of the counter 9 is set to N _S , and the counter 1
The count value of 0 is N _T, and these outputs are given to the microcomputer 12. The microcomputer 12 is connected to a temperature correction table memory 13 and a linear correction table memory 14, which are tables for correction described later. These memories 13 and 14 are composed of E ² PROM, for example. The microcomputer 12 performs temperature correction processing using this temperature correction table, converts it into displacement data, and linearizes it using a linear correction table. Then, as will be described later, based on the data of the reference position input by the input unit 15, the displacement data is converted into a scale defined by the user, and an output is given by comparison with a predetermined position on this scale. There is. The display unit 16 displays the distance information on the user scale, and the output unit 17 outputs the determination output thus obtained.

Next, detailed functional blocks in the microcomputer 12 will be described with reference to FIG. In the microcomputer 12, a temperature correction processing unit 21 that calculates a correction value ΔN in the number of pulses of the current temperature with respect to the reference temperature based on the temperature correction table memory 13 that corrects the count value M _T from the counter 10. It is provided. A reference value output unit 22 that outputs a reference value N _{R of the} number of pulses is provided. This reference value N _R is set to 25600 in this embodiment. This ΔN and the reference value N _{R of the} pulse number are added by the adding means 23.
Given to. The adding means 23 adds these, and the output thereof is given to the subtracting means 24. The subtracting means 24 calculates the addition value N _R + ΔN from the count value N _S of the counter 9.
A first subtraction means for subtracting Nd (= N _S −
(N _R + ΔN)) is calculated. Then, this Nd is given to the displacement calculation processing unit 25 as displacement information. The displacement calculation processing unit 25 linearizes this and obtains displacement information ± Δd from the reference position specific to the displacement detection sensor.

The input section 15 switches the output mode of the displacement detection sensor and inputs a pair of inputs IN1 and IN2 in accordance with each output mode. Then, the mode selection means 26 in the microcomputer 12
Receives a mode selection signal from the input unit 25,
And B, the inputs of the pair of inputs IN1 and IN2 corresponding to the respective modes are held in the register 27, and IN1 is given to the subtracting means 28. The subtracting means 28 is a second subtracting means for subtracting the set value IN1 from the displacement information Δd. In this way, the value is converted into displacement information from the reference position IN1 set by the user, and this value is displayed on the display unit 16. Further, the mode selection means 26 gives a necessary comparison value to the comparison section 29 depending on the mode A or B, as will be described later.
The comparison unit 29 outputs the pair of outputs OUT1 or OUT2 by comparing the comparison reference value thus obtained with the value subtracted by the subtraction unit 28. These outputs are output from the output unit 17 to the outside.

FIG. 3 is a front view showing the structure of the displacement detecting sensor according to this embodiment. As shown in this figure, the above-mentioned sensor unit 1 is connected to the displacement detection sensor body via a cable, and an input unit 15 and a display unit 16 are provided on the front surface of this case 20. The input unit 15 is as shown in the figure.
Slide switch 15a, "UP" key 15b, "S" for switching the operation mode between "RUN" and "SET" modes
A "HIFT" key 15c and a "TEACH" key 15d are provided. Further, the display unit 16 has a mode display unit for displaying an operation mode of either A or B, and an input IN1.
Alternatively, a display unit for switching IN2 and a numerical display unit for displaying the position of the object in the operation mode are provided.

Next, the processing in the temperature correction processing section 21 will be described in detail. In this embodiment, first, the temperature of the sensor unit 1 is detected by the thermistor 5 in the sensor unit 1.
The CR oscillation circuit 6 oscillates at an oscillation frequency corresponding to the resistance R of the thermistor 5. Therefore, the temperature information of the sensor unit 1 can be obtained from the oscillation frequency. Now, the resistance value R of the thermistor 5 at an arbitrary temperature T is determined by the following equation. R = R ₀ expB (1 / T-1 / T ₀ ) ... (1) T: arbitrary temperature (° K) R: resistance value at temperature T T ₀ : reference temperature (° K) R ₀ : Resistance value B at reference temperature T ₀ : B constant

The creation of the temperature correction table used in the temperature correction process will be described. The oscillation frequency of the CR oscillation circuit 6 is the resistance value R of the thermistor 5, that is, the temperature and the characteristic B.
It depends on the constant. In this embodiment, the individual data of the thermistor 5 and the count value of the counter 9 due to the peculiar variation of the oscillation coil 3 are fetched as data, and the correction is performed based on this. FIG. 4 is a block diagram showing a correction table generation device 30 for generating the temperature correction table 13 based on the data of these individual elements. In this figure, each block having the same reference numeral as in FIG. 1 is the same as that in FIG. 1, and the sensor unit 1 itself having the oscillation coil 3 and the thermistor 5 unique to each displacement sensor is placed in the constant temperature bath 31. The temperature of the constant temperature bath 31 is controlled by the controller 32. Then, the count values N _S and N _T of the counters 9 and 10 corresponding to the oscillation frequencies f _S and f _T at the predetermined temperature are obtained. Then, the outputs from the counters 9 and 10 are written in the data memory 34 via the data writing unit 33. The data memory 34 is composed of an E ² PROM.

[0019] Referring now to accurately temperature, for example -10 ° C. and + 60 ℃ definable in a thermostat 31, M _T table calculating section 35 calculates the resistance value of the thermistor 5 from the oscillation frequency at this temperature, whereby B Calculate the constant. In this way, the resistance value of the thermistor 5 at an arbitrary temperature can be calculated.

Next, for all temperatures at which this displacement sensor can be used, in this embodiment, from -30 ° C to 78 ° C, the resistance value with respect to the temperature of the thermistor in steps of 2 ° C is determined. Then, the oscillation frequency of the CR oscillation circuit 6 and the count value M _T of the counter 10 corresponding to this oscillation frequency are calculated from each resistance value. And M at each temperature
_{The T} value is written in the M _T table area in the data memory 36. FIG. 5A shows the M _T thus calculated.
It is a 1st counting table which shows the change of a value. Where M _T
The table calculation unit 35 is a first counting table calculation unit that calculates a calculation value at each temperature obtained from the second counting unit.

Now, as shown in FIG. 4, the sensor unit 1 is actually put in the constant temperature bath 31, and the control unit 32 is operated to change the temperature. FIG. 7 is a graph showing changes in the count value N _S of the counter 9 with respect to the distance d to the object. As shown in this figure, the detection area is defined as 100% of the distance d to the object, and the distance up to 1/2 thereof is set as the reference distance d _R. Reference temperature at this reference distance d _R , N of 24 ° C. in this embodiment
_{Let the S} value be the reference value N _R. Set N _R to be 25,600 pulses. For example, when the first clock frequency of the reference clock oscillator 11 is set to 10 MHz, the frequency division number Ks is changed to set the output pulse width of the frequency division circuit 7 to 2.56.
Set to ms. The reference value N _R thus obtained can be output from the reference value output unit 22 shown in FIG. Further, the M _T value at this reference temperature is set to be 8000 pulses, for example. In this case, the frequency dividing number K _T of the frequency dividing circuit 8 is changed to set the output pulse width to 2 seconds, and the reference clock oscillator 11
By counting the second clock frequency of 4000 Hz, the pulse number of 8000 is obtained.

By continuously changing the temperature of the thermostat 31 with the sensor unit 1 in the thermostat 31, the M _T value and the M _T value in steps of 2 ° C. at each temperature from −30 ° C. to 78 ° C. Get the N _S value. And this data is shown in Figure 6.
Data is written in the data memory 34 as shown in (a) and (b). Note the temperature at this time is not strictly defined, is used to know the relationship N _S values for M _T values. Here, the data writing unit 33 uses the count values N _S and M _T obtained by the first and second counting means at each temperature in the operating range of the oscillator circuit 3.
To constitute a second counting table generating means. The tables of FIGS. 6A and 6B thus obtained are the second and third tables.

[0023] Now N _S table calculating unit 37 from the table of M _T obtained in thus obtained was calculated as shown in the table and figure M _T and N _S in FIG. 6 5 (a), N _S value at each temperature Is calculated and written in the data memory 36. That is, FIG. 5 (a)
Corresponding to each M _T value of the M _T table of FIG. 6, the M _T values before and after that are searched for from the table of FIG. Then, the N _S value corresponding to each M _T value in FIG.
It is calculated as shown in (b). Also, the ΔN table calculation unit 3
8 is the N _S value at each temperature thus obtained and the reference temperature,
Here, ΔN is calculated from the difference with the N _S value (= N _R = 25600) at 24 ° C., and this is shown as ΔN in FIG. 5 (c).
The data is written in the data memory 36 as a table (fourth table). Here, the N _S table calculation unit 37 is shown in FIG.
A third count for calculating the calculated value to be obtained by the first counting means corresponding to the calculated value at each temperature in the table of FIG. 5A by proportionally distributing the data of the counting table shown in FIG. 5B. The N _S table calculating unit 38, which is a table calculating means, calculates a fourth table of the correction value ΔN by subtracting the reference count value N _R from this table Δ
It constitutes N table calculation means.

Thus, as shown in FIGS. 5 (a) and 5 (c), a pair of tables in which the ΔN values corresponding to M _T at each temperature are written are shown as E in the temperature correction table memory 13 shown in FIGS. ² Data is transferred to PROM and used as a temperature correction table. Note here forms a table for the N _S value once corresponding to each temperature, as shown in FIG. 5 (b), by subtracting a predetermined reference value N _R from this value, shown in FIG. 5 (c) Δ
Although the N table is generated, it goes without saying that the ΔN table may be directly generated after the proportional distribution.

In FIG. 7, the curve A is the distance d at the reference temperature.
Is a graph showing the change of the N _S value with respect to, and the curve obtained by using data from a large number of specific displacement sensors is used as it is. Then, at a temperature higher than the reference temperature, the number of pulses N _{S with} respect to the distance d
Changes as shown by the curve B, and changes as shown by the curve C at low temperatures. Therefore, the difference Nd from the reference value is calculated by subtracting ΔN from N _S, and the difference is converted into the curve A, and the distance data is obtained based on the corrected pulse number Nd.

FIG. 8 is a graph showing changes in the number Nd of temperature-corrected pulses with respect to the distance d. This graph uses a prescribed curve obtained based on the data of a plurality of displacement sensors, and by fitting this to the distance information d. Then, 256 of Nd is changed by 1%, and data corresponding to this distance is held in the linear correction table 14 as shown in FIG. In this correction table, for example, in a portion where the curve has a small inclination, distance data d ₁₀ , d _11, ... Are sequentially recorded in the table T1 in 0.5% units. Further, in the portion where the distance is shorter than the reference distance d _R , the distance is sequentially recorded by the table T2, the tables T3, T4, ... The distance Δd from the actual reference distance d _R is obtained by the following equation (2).

[Equation 1] Here, P is the number of data from the reference position. The first term of the equation (2) is the sum of displacements when n is 0 to P-1,
The term indicates the proportional distribution value of the distance with respect to the pulse number Nd within the displacement.

Next, the operation of this embodiment will be described with reference to the flow charts of FIGS. First, when the operation is started, the slide switch 15a is set to the set state and IN1 and IN2 are input. First, when the operation is started, the slide switch 15a is set to "S" in step 41.
Check whether it is in the "ET" state. When entering "SE
If the "T" mode is set, the routine proceeds to step 42, where the mode selection state is determined. Here, as shown in FIG. 3, "UP"
Use the key 15b to switch between modes A and B,
It is fixed by the "T" key 15c. First, mode A
Then, in step 43, "IN1" is displayed on the display unit 16. At this time, the object is arranged at the center position of the object detection of the sensor unit 1 of the displacement detection sensor. Then, the center value is set by pressing the "TEACH" key 15d of the input section (step 44). At this time, the subtraction means 28
The obtained value is written in the register 27 as the central value.

On the other hand, in mode B, "IN1" is first displayed in step 45. Then, the user places the object at a position closest to the detection range of the displacement detection sensor.
Then, by pressing the "TEACH" key 15d, the value obtained by the subtracting means 28 at that time is set in the register 27 as the MIN value. This MIN value sets the closest contact point to the object of the displacement detection sensor. Here, steps 42 to 46 constitute first input means for inputting the reference position set by the user. In this case, in the mode A, this reference position becomes the center value as shown in FIG. 12, and in the mode B it becomes the closest point as shown in FIG.

When the processing of step 44 or 46 is completed, the routine proceeds to step 47, where the "SHIFT" key 15c
Wait for input. When the "SHIFT" key 15c is pressed, "IN2" is displayed on the display unit 16 (step 48). Next, in steps 49 and 50, the "UP" key 15a is pressed to select the place of several digits, and the "SHIFT" key 16c at the desired position is continuously pressed. By doing so, the numerical value in the display unit 16 continuously changes at that position, and thus IN2 is input. When the numerical value on the display unit 16 reaches the desired value, the routine proceeds to step 51, where the "TEACH" key 15d is pressed. In this way, this numerical value is confirmed as IN2. The mode selection means 26 holds this value in the register 27 and finishes the setting. Here, IN2 sets the range of the deviation from the center position in mode A as shown in FIG. In mode B, the displacement from the closest contact point to the object is set as shown in FIG. Here, in steps 47 to 51, the second input means for inputting the range of change from the reference position or the displacement from the reference position is configured. Next, when operating, slide switch 15a to "R
UN "mode.

In operation, first, the sensor portion 1 of the displacement detecting sensor is placed in the measurement area of the object. When an object approaches the oscillation coil 3, the oscillation circuit 4 oscillates at an oscillation frequency corresponding to the distance d to the object. Also, at the oscillation frequency f _T corresponding to the temperature at this time, CR
The oscillator circuit 6 oscillates. Therefore, the count value M _T of the counter 10 corresponding to the temperature is obtained. Figure 5 this M _T
By correcting by the temperature correction table memory 13 shown in (a) and (c) and obtaining the proportional distribution value of ΔN, ΔN at this temperature of the sensor unit 1 can be obtained. In this way, ΔN and N _R are added by the adding means 23, and the subtracting means 24 obtains the difference from N _S , whereby the pulse number Nd corresponding to only the distance d that does not depend on the temperature or the element of each displacement sensor.
Is obtained. Then, by converting this value based on the conversion table as shown in FIGS. 8 and 9, the linearized position information Δd can be obtained. This Δd indicates the displacement from the reference value d _{R on} the reference scale specific to the displacement sensor.

If the switch is not in the "SET" mode, the flow advances to step 61 in FIG. 11 to first check whether or not the mode is the "RUN" mode. In the case of the "RUN" mode, the routine proceeds to step 62, where the value of Δd is fetched from the displacement calculation processing section 25. The IN stored in the register 27
Subtract one. IN1 is the center value in mode A, mode B
Is the minimum value MIN. Then, the obtained value is transferred to the display unit 16 and displayed on the user scale. Here, steps 62 to 64 are the second subtraction means 28 for converting the displacement Δd obtained from the displacement calculation processing section 25 into a user scale.
Are configured. Then, in step 65, it is checked whether or not the mode set in the mode selecting means 26 is the mode A. In the case of mode A, the process proceeds to step 66 and the subtraction value is set in the register 28 IN1 +
It is checked whether it exceeds IN2 and whether it is less than IN1-IN2. If the conditions of steps 66 and 67 are satisfied, the process proceeds to steps 68 and 69, respectively, and the output OUT
2 is switched to H and OUT1 is switched to H level, and the process returns to step 62. By doing so, as shown in FIG. 12A, the reference scale unique to the displacement detection sensor is converted into a user scale having IN1 as the center point, and the IN2 set based on the user scale is converted to the user scale shown in FIG. A pair of outputs corresponding to the distance can be obtained as shown in (b).

Next, when the mode B is set in step 65, the process proceeds to step 70 and the subtraction means 2
It is checked whether or not the value subtracted in step 8 is negative. If the subtracted value is negative, the routine proceeds to step 71, where the output OUT1 is set to H level. If not negative, it is checked in step 72 whether the subtracted value exceeds IN2. I
If N2 is exceeded, OUT is output in step 73.
2 is set to H level. By doing this, FIG. 13 (a), (b)
As shown in, the reference scale specific to the displacement detection sensor is converted into a user scale with IN1 set as the closest contact point set by the user, and an output is obtained depending on whether or not the distance from the position to the set displacement is reached. You can

In the present embodiment, when the reference position IN1 set by the user is input, an object is placed in front of the displacement detection sensor and the subtraction value at that time is set to IN1, but it is also possible to directly input a numerical value. Needless to say. Further, the range of deviation from the reference position or the second position displaced from the reference position is numerically input, but when the second position is input, the object is placed at that position and a predetermined key is pressed. It goes without saying that it may be possible to input by doing so.

Further, although the thermistor is used as the temperature sensor connected to the second oscillation circuit in this embodiment, it goes without saying that various temperature sensors can be used without being limited to the thermistor.

[0035]

As described in detail above, according to the invention of claim 1 of the present application, the temperature compensation means for compensating the temperature includes the temperature detecting means specific to each displacement sensor and the change with respect to the temperature of the oscillation coil. Created and corrected based on this data. Therefore, there is no temperature compensation error due to variations in the oscillation coil or the temperature sensor. Then, the displacement of the object from the reference position where the user arranges the object or inputs it numerically can be accurately measured and displayed. Further, in the invention of claim 2 of the present application, by inputting the reference position and the range of the deviation from the reference position, it is possible to obtain a determination signal as to whether or not it is within this range. According to the third aspect of the invention, it is possible to determine whether or not the position is within a range separated from the reference position by a certain range. Therefore, it becomes possible to input the position extremely easily. Further, in the invention of claim 4, it is possible to switch between the first and second modes and input the range or displacement of the deviation by the second input means, and determine the range or the displacement by the comparing means. In the invention of claim 5, the setting can be easily performed by directly inputting a numerical value by the second input means.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a displacement detection sensor according to an embodiment of the present invention.

FIG. 2 is a block diagram showing functional blocks of a microcomputer of this embodiment.

FIG. 3 is a front view showing the front surface of the displacement detection sensor of this embodiment.

FIG. 4 is a block diagram showing a configuration of a correction table generation device for creating a correction table memory 13 according to the present embodiment.

[5] (a) M _T table, obtained in the examples operation (b) the number of pulses Nd corresponding thereto, (c)
Is a table showing the correction value ΔN.

FIG. 6 (a) is a table showing M _T values at each temperature obtained when the sensor unit is inserted into a constant temperature bath in the operating temperature range of this displacement detection sensor, and FIG. 6 (b) is N _{T in} that case. It is a table showing a value.

FIG. 7 is a graph showing changes in the number of pulses N _S with respect to the distance in this embodiment.

FIG. 8 is a temperature-compensated Nd with respect to the distance d in the present embodiment.
It is a graph which shows change of a value.

FIG. 9 is a diagram showing a conversion table for linearizing Nd in the present embodiment.

FIG. 10 is a flowchart showing the operation of the position input unit of this embodiment.

FIG. 11 is a flowchart showing the operation of this embodiment.

FIG. 12 is a diagram showing a relationship between a reference scale and a user scale in A mode and an output state in the user scale.

FIG. 13 is a diagram showing the relationship between the reference scale and the user scale and the output with respect to the detection distance on the user scale in the present embodiment.

FIG. 14 is a block diagram showing a configuration of a conventional high frequency oscillation type proximity switch.

[Explanation of symbols]

1 Sensor Section 2 Electronic Circuit Section 3 Oscillation Coil 4 Oscillation Circuit 5 Thermistor 6 CR Oscillation Circuit 7, 8 Frequency Divider Circuit 9, 10 Counter 11 Reference Clock Oscillator 12 Microcomputer 13 Temperature Correction Table Memory 14 Linear Correction Table Memory 15 Input Section 16 Display unit 17 Output unit 20 Case 21 Temperature correction processing unit 22 Addition unit 23 Reference value output unit 24, 28 Subtraction unit 25 Displacement calculation processing unit 26 Mode selection unit 27 Register 29 Comparison unit 30 Correction table generation device 31 Constant temperature bath 32 Control unit 33 data writing unit 34, 36 a data memory 35 M _T table calculating section 37 N _S table calculating unit 38 .DELTA.N table calculating section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Iwatsuki, No. 10 Hanazono Dodo-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture Omron Co., Ltd. Within Muron Co., Ltd.

Claims (5)

[Claims] 1. A first oscillating circuit which has an oscillating coil and whose oscillating frequency changes when an object to be detected approaches the oscillating coil; and an oscillating frequency which changes due to a temperature change of the first oscillating circuit. A second oscillating circuit, first and second counting means for counting oscillating frequencies of the first and second oscillating circuits, and the first oscillating circuit corresponding to each temperature of the first oscillating circuit in a working temperature range. The first counting table is generated by calculating the calculation value to be obtained by the second counting means, and the first and second counting means are associated with each temperature of the first oscillation circuit in the operating temperature range. The obtained count values are respectively generated as second and third count tables, and the data of the second and third count tables are proportionally distributed to correspond to the calculated values at each temperature of the first table. Should be obtained from the first counting means First values obtained by calculating operation values, subtracting the reference count value N _R of the first counting means from each operation value, and calculating a fourth count table of the correction value ΔN at each temperature. , A correction table memory using the fourth counting table as correction table data, and a temperature correction process for calculating a correction value ΔN corresponding to the count value M _T obtained by the second counting means based on the correction table by proportional distribution. Section, the correction value ΔN and the reference value N obtained from the temperature correction processing section.
An addition means for adding _R and _R , a first subtraction means for subtracting the addition value (ΔN + N _R ) of the addition means from the count value Ns of the first counting means, and an output obtained from the first subtraction means A displacement calculation processing unit that linearizes Nd with respect to the distance d from the oscillation coil to the object, a first input unit that inputs a reference position of displacement as displacement data, and a first input unit that inputs the displacement reference position. A displacement detection sensor comprising: second subtraction means for subtracting the value of the reference position from the linearized output; and display means for displaying the output of the second subtraction means. 2. A second input means for inputting a range (IN2) of a deviation from a reference position (IN1) inputted by the first input means, an output of the second subtracting means and the second Comparing means for judging whether or not the deviation is within this range based on the range of the deviation input by the input means, and output means for outputting the comparison signal of the second comparing means,
The displacement detection sensor according to claim 1, further comprising: 3. A second input means for inputting a displacement from a reference position inputted by the first input means, an output of the second subtracting means, and a displacement inputted by the second input means. Comparing means for comparing and, output means for outputting a comparison signal of the second comparing means,
The displacement detection sensor according to claim 1, further comprising: 4. A switching means for switching between first and second modes for setting a range or displacement of a deviation from a reference position input from the first input means, and the first mode is selected by the switching means. When the second mode is selected by the switching means, the range of deviation from the reference position input by the second input means is input, and the reference input by the first input means when the second mode is selected by the switching means. Second input means for inputting a displacement from a position, and comparison for comparing the output of the second subtracting means and the range or displacement of the deviation input by the second input means, which is controlled by the switching means. The displacement detection sensor according to claim 1, further comprising: a means and an output means that outputs a comparison signal of the comparison means. 5. The displacement detection sensor according to claim 2, wherein the second input means inputs a numerical value corresponding to the output scale of the subtraction means.