JP2015099065A - Physical quantity sensor and method of measuring physical quantity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physical quantity sensor capable of calibrating an output from a sensor element even when the output from the sensor element has changes smaller than one cycle, and a method of measuring physical quantity.SOLUTION: A physical quantity sensor includes: a maximum/minimum value detection section 6 that calculates a physical quantity Xwhen the output from a second sensor element 3 is the maximum or minimum using a formula X=(X+X)/2 based on a physical quantity Xand Xwhen an output value P of the second sensor element 3 is P; and an off-set calibration section 8 that converts an output value Y of a first sensor element 2 into an output value V by using a formula V=Y-Y+a so as to convert an output value Yof the first sensor element 2 when a physical quantity is the Xinto a reference output a of the first sensor element 2.

Description

  The present invention relates to a physical quantity sensor that detects physical quantities such as length, distance, angle, and number of rotations, and a physical quantity measuring method.

  There are various types of sensors that detect physical quantities such as length, distance, angle, and rotation speed. Examples of such a sensor include an optical type, a magnetic type, a capacitance type, and a resistance type. For example, in the case of the magnetic type, a method of measuring a physical quantity by providing a magnetic scale periodically magnetized on a member to be measured and detecting magnetism from the magnetic scale is known. In the case of a rotational speed sensor, the rotational speed can be detected by using a magnetized rotating body as a magnetic scale and counting the number of magnetic changes from the magnetic scale. For example, when the magnetic scale is magnetized at intervals of 10 ° and the output change period of the magnetic sensor element is the same as the magnetization period of the magnetic scale, the magnetic sensor element changes by 6 periods. In this case, it can be seen that the rotation speed of the magnetic scale is 1/6 rotation corresponding to 60 °. Furthermore, when detecting the rotation speed or rotation angle of less than 10 °, it can be determined from the output value of the magnetic sensor element.

  In this case, since the output from the magnetic sensor element is a sinusoidal output, two physical quantities are derived with respect to the output from the magnetic sensor element, so the number of rotations or the rotation angle is not fixed to one. . Therefore, there is a method of determining one physical quantity based on outputs of two magnetic sensor elements using two magnetic sensor elements having different output phases. Specifically, a method is known in which the phase difference between the output waveform of one magnetic sensor element and the output waveform of the other magnetic sensor element is 90 °.

  When using a sensor element, offset deviation of the sensor element and variation in amplitude are problematic. For this reason, various calibration methods have been proposed. Specifically, a method has been proposed in which output from sensor elements for at least one cycle is sampled and offset calibration is performed using an intermediate value between a maximum value and a minimum value as a reference output (for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-311741

  The physical quantity sensor can be used for various applications. Under such circumstances, for example, it is possible in principle to detect an angular displacement of an object that does not rotate until one rotation.

  However, since the calibration method of the prior art needs to sample the output of the sensor element for one cycle, there is a problem that calibration cannot be performed if the sensor element output does not change up to one cycle.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems. A physical quantity sensor capable of calibrating the output from a sensor element even when the output from the sensor element changes only less than one cycle, and the measurement of the physical quantity. It aims to provide a method.

In order to achieve the above object, the invention according to claim 1 outputs a first sensor element that outputs an output value Y corresponding to the physical quantity X, and an output value P that corresponds to the physical quantity X, and the phase of the output value is By inputting a second sensor element different from the output value of the first sensor element, an output value Y from the first sensor element, and an output value P from the second sensor element, an attempt is made to measure. A signal processing unit that outputs a physical quantity X to be output, wherein the signal processing unit has at least a calibration unit that calibrates the output value Y, and the calibration unit has an output value P of the second sensor element of P the physical quantity X _2a and X _2b when the _a, the output of the second sensor element physical quantity X ₂ when is the maximum or minimum _{X 2 = (X 2a + X} 2b) / 2
And the first sensor element so as to convert the output value Y ₂ of the first sensor element when the physical quantity is X ₂ into the reference output a of the first sensor output element. Output value Y to output value V V = Y−Y ₂ + a
And a physical quantity sensor provided with an offset calibration unit for conversion in (1).

  With the above configuration, the first sensor element can be offset calibrated even if it is a physical quantity sensor that has only an output change less than one cycle.

The invention according to claim 2, wherein the maximum minimum detector further by the physical quantity X _1a and X _1b when the output value Y of the first sensor element is Y _a, the output of the first sensor element The physical quantity X ₁ when X is maximum or minimum is X ₁ = (X _1a + X _1b ) / 2
The calibration unit further calculates the absolute value of the difference between the output value Y ₁ of the first sensor element and the output value Y ₂ when the physical quantity is X ₁ , as the output value of the first sensor element. The output value V is changed to the output value W so that the reference gain A is equal to W = A / | Y ₁ −Y ₂ | · V
And a gain calibration unit for conversion at.

  With the above configuration, even if the physical quantity sensor has only an output change that is less than one cycle, the first sensor element can be offset and gain calibrated.

According to a third aspect of the present invention, the calibration unit further calibrates the output value P, and the offset calibration unit further outputs the output value P of the second sensor element when the physical quantity is X _1. Q ₂ the output value Q of the output value P of the second sensor element to convert the reference output b of the second sensor output element = P-P ₂ + b
It is to convert with.

  With the above configuration, even if the physical quantity sensor has only an output change less than one cycle, the first sensor element offset calibration and gain calibration can be performed, and the second sensor element offset calibration can be performed. Have

The invention according to claim 4, further wherein the gain correction unit, said physical quantity is an absolute value of the difference between the output value P ₁ and the output value P ₂ of the second sensor element when the X ₂ second The output value Q is changed to an output value R so that the reference gain B of the output value of the sensor element 2 is R = B / | P ₁ −P ₂ | · Q
It is to convert with.

  With the above configuration, even if the physical quantity sensor has only an output change that is less than one cycle, the offset calibration and gain calibration of the first sensor element and the offset calibration and gain calibration of the second sensor element can be performed. It has the effect of.

The invention according to claim 5, wherein the maximum minimum detector further by the physical quantity X _1a and X _1b when the output value Y of the first sensor element is Y _a, the output of the first sensor element The physical quantity X ₁ when X is maximum or minimum is X ₁ = (X _1a + X _1b ) / 2
In
The calibration unit further calibrates the output value P, and the offset calibration unit further calculates the output value P ₂ of the second sensor element when the physical quantity is X ₁ of the second sensor output element. The output value P of the second sensor element is converted to an output value Q so as to be converted into a reference output b. Q = P−P ₂ + b
It is to convert with.

  With the above configuration, even if the physical quantity sensor has only a change in output that is less than one cycle, the first sensor element offset calibration and the second sensor element offset calibration can be performed.

The invention of claim 6 includes the steps of outputting P from the second sensor element for detecting a physical quantity X _2a and X _2b when the P _a, the output P is the maximum value from the second sensor element or The physical quantity X ₂ at the minimum value is expressed as X ₂ = (X _2a + X _2b ) / 2.
The step of detecting the output value Y ₂ of the first sensor element when the physical quantity is X ₂ , and the reference output of the output Y from the first sensor element as a, The output Y from the first sensor element is converted into the output V after conversion.
V = Y−Y ₂ + a
Performing an offset calibration for conversion according to

  By the above method, even if it is a physical quantity sensor which has only an output change less than one cycle, it has the effect that the offset calibration of the first sensor element can be performed.

The invention according to claim 7, further comprising: output Y from the first sensor element for detecting a physical quantity X _1a and X _1b when the Y _a, the output Y from the first sensor element is maximum The physical quantity X ₁ when the value is a minimum value or the minimum value is X ₁ = (X _1a + X _1b ) / 2
A step of obtaining, the physical quantity is a step of detecting the output value Y ₁ of the first sensor element when the X _1, the output value Y ₁ and the absolute value of the first difference of the output values Y ₂ The output value V is changed to the output value W so as to be the reference gain A of the output value of the sensor element.
W = A / │Y ₁ −Y ₂ │ ・ V
And a step of converting at the step.

  By the above method, even if it is a physical quantity sensor which has only an output change which is less than one period, it has the effect that the offset calibration and gain calibration of a 1st sensor element can be performed.

The invention according to claim 8 further includes the step of detecting the output value P ₂ of the second sensor element when the physical quantity is X ₁ , and the output value P ₂ of the second sensor output element. The output value P of the second sensor element is converted to an output value Q so as to be converted into a reference output b. Q = P−P ₂ + b
And a step of converting at the step.

  By the above method, even if the physical quantity sensor has only an output change that does not satisfy one cycle, the offset calibration and gain calibration of the first sensor element can be performed and the offset calibration of the second sensor element can be performed. Has an effect.

The invention according to claim 9 further includes the step of detecting the output value P ₁ of the second sensor element when the physical quantity is X ₂ , and the absolute difference between the output value P ₁ and the output value P ₂ The output value Q is set to the output value R so that the value is the reference gain B of the output value of the second sensor element.
R = B / │P ₁ −P ₂ │ ・ Q
And a step of converting at the step.

  With the above method, even if the physical quantity sensor has only an output change that does not satisfy one cycle, the offset calibration and gain calibration of the first sensor element can be performed, and the offset calibration and gain calibration of the second sensor element can be performed. Has the effect of being able to.

The invention according to claim 10, further comprising: output Y from the first sensor element for detecting a physical quantity X _1a and X _1b when the Y _a, the output Y from the first sensor element is maximum The physical quantity X ₁ when the value is a minimum value or the minimum value is X ₁ = (X _1a + X _1b ) / 2
The step of detecting the output value P ₂ of the second sensor element when the physical quantity is X ₁ , and the output value P ₂ as the reference output b of the second sensor output element. The output value P of the second sensor element is converted into an output value Q so as to convert Q = P−P ₂ + b
And a step of converting at the step.

  With the above method, even if the physical quantity sensor has only an output change less than one cycle, the first sensor element offset calibration and the second sensor element offset calibration can be performed.

  The physical quantity sensor and the physical quantity measuring method of the present invention have an effect that the output from the sensor element can be calibrated even when the output from the sensor element is less than one cycle.

Block diagram of physical quantity sensor in Embodiment 1 of the present invention Output waveform diagram of sensor element section of physical quantity sensor in embodiment 1 of the present invention Output waveform diagram of sensor element section of physical quantity sensor in embodiment 1 of the present invention Output waveform diagram of offset calibration unit of physical quantity sensor according to Embodiment 1 of the present invention Output waveform diagram of gain calibration section of physical quantity sensor according to Embodiment 1 of the present invention Block diagram of physical quantity sensor in Embodiment 2 of the present invention Block diagram of physical quantity sensor in Embodiment 3 of the present invention Block diagram of physical quantity sensor in Embodiment 4 of the present invention Block diagram of physical quantity sensor in Embodiment 5 of the present invention

(Embodiment 1)
A physical quantity sensor according to Embodiment 1 of the present invention will be described. 1 is a block diagram of a physical quantity sensor according to Embodiment 1 of the present invention, FIG. 2 is an output waveform diagram of a sensor element section of the physical quantity sensor according to Embodiment 1 of the present invention, and FIG. 3 is an embodiment 1 of the present invention. FIG. 4 is an output waveform diagram of the offset calibration unit of the physical quantity sensor in the first embodiment of the present invention, and FIG. 5 is a gain calibration unit of the physical quantity sensor in the first embodiment of the present invention. FIG.

  The physical quantity sensor 1 is a sensor for obtaining a physical quantity X to be measured. The physical quantity sensor 1 includes a first sensor element 2, a second sensor element 3, and a signal processing unit 4.

  Each of the first sensor element 2 and the second sensor element 3 has a characteristic of changing an output value according to a physical quantity X to be measured. The first sensor element 2 outputs an output Y corresponding to the physical quantity X. The second sensor element 3 outputs an output P corresponding to the physical quantity X. The first sensor element 2 and the second sensor element 3 are set so that the phases of the outputs are different. Specifically, the position of the second sensor element 3 is shifted from the phase of the first sensor element 2 so that the phase of the second sensor element 3 advances by 90 °. As the first sensor element 2 and the second sensor element 3, a magnetic sensor, an optical sensor, a potentiometer, or the like can be used.

  The signal processing unit 4 has a function of obtaining the physical quantity X using the output Y from the first sensor element 2 and the output P from the second sensor element 3 as input signals. The signal processing unit 4 includes a calibration unit 5 and a calculation unit 12. The calibration unit 5 has a function of calibrating the offset value of the output value Y from the first sensor element 2 and the output P from the second sensor element 3 and calibrating the output gain and outputting the output W and the output R. Have. The calculation unit 12 has a function of calculating the physical quantity X based on the output signal from the calibration unit 5.

  The calibration unit 5 includes a maximum / minimum detection unit 6, a maximum / minimum detection unit 7, an offset calibration unit 8, an offset calibration unit 9, a gain calibration unit 10, and a gain calibration unit 11.

The maximum / minimum detection unit 6 has a function of obtaining a physical quantity X ₁ when the output Y of the first sensor element 2 is maximum or minimum. Here, the maximum or the minimum refers to the time when the value of the output Y when the physical quantity X increases or when the value changes from increase to decrease or from decrease to increase.

  A method for obtaining the maximum or minimum of the output Y and the output P will be described with reference to FIG. The horizontal axis in FIG. 2 is a physical quantity X, and the vertical axis is an axis that serves as both output Y and output P.

In order to detect when the output Y of the first sensor element 2 is maximum or minimum, the physical quantity sensor 1 is moved from the lower limit to the upper limit of the measurable physical quantity, and the output of the first sensor element 2 is Y _The physical quantity X _1a and the physical quantity X _1b to be a are obtained, and the midpoint between the physical quantity X _1a and the physical quantity X _1b is
X ₁ = (X _1a + X _1b ) / 2
This is done by obtaining the physical quantity X ₁ that becomes In this method, the output Y of the first sensor element 2 is regarded as a part of the sine wave, and the sine wave is obtained using the property of having a waveform with the physical quantity X ₁ as a symmetric axis when the local maximum or minimum is obtained. .

  In the vicinity where the output Y becomes maximum or minimum, the rate of change of the output Y when the physical quantity X is changed is close to 0, so it is difficult to accurately determine the maximum or minimum directly from the value of the output Y. Therefore, the above method is used.

Y _a configuration can be determined in advance. In this case, it is necessary to set a value smaller than the maximum output Y _max from the first sensor element 2 and larger than the minimum output Y _min when the physical quantity sensor 1 is moved from the lower limit to the upper limit of the measurable physical quantity X. Alternatively, the Y _a as the midpoint output of the maximum output Y _max and the minimum output Y _min from the first sensor element 2,
Y _a = (Y _max + Y _min ) / 2
You may make it ask in.

The maximum / minimum detection unit 6 has a function of obtaining a physical quantity X ₁ when the output Y of the first sensor element 2 is maximum or minimum, whereas the maximum / minimum detection unit 7 has an output P of the second sensor element 3. Has a function of obtaining the physical quantity X ₂ when the value is maximum or minimum. Determination of physical quantity X _2, similarly to the case of obtaining the physical quantity X _1, obtaining the physical quantity X _2a and the physical quantity X _2b serving as a P _a. Determination of physical quantity X _2a and physical quantity X _2b likewise, the physical quantity X _2a and the physical quantity X _2b output of the second sensor element 3 is P _a determined, as the midpoint between the physical quantity X _2a and the physical quantity X _2b ,
X ₂ = (X _2a + X _2b ) / 2
It is assumed that the physical quantity X ₂ is maximal or minimal.

Setting P _a, similarly to the Y _a, to can be predetermined, maximum output P _max and the minimum output P _min when moving the physical quantity sensor 1 from the lower limit of the measurable physical quantity X to the upper limit As the midpoint output,
P _a = (P _max + P _min ) / 2
You may make it ask in.

  Next, offset calibration will be described with reference to FIG. The horizontal and vertical axes in FIG. 3 are the same as those in FIG.

The offset calibration unit 8 offset calibrates the output Y from the first sensor element 2 and outputs an output V. As an offset calibration method, when two sine waves having a phase difference of 90 ° have a maximum or minimum sine wave whose phase is advanced by 90 °, the value of the other sine wave is 0. ing. Specifically, since the output Y from the first sensor element 2 has a phase delayed by 90 ° compared to the output P from the second sensor element 3, the second sensor element 3 becomes maximum or minimum. When the reference output of the output from the first sensor element 2 at the physical quantity X ₂ is a, the output V after offset calibration is
V = Y−Y ₂ + a
It is obtained by In the present embodiment, the value of a is 0.

The offset calibration unit 8 offset calibrates the output Y from the first sensor element 2 and outputs an output V. The offset calibration unit 9 offset calibrates the output Y from the second sensor element 3 and outputs the output Q. Output. The offset calibration method is based on the same idea as the offset calibration unit 8, and the output P from the second sensor element 3 is a phase advanced by 90 ° compared to the output Y from the first sensor element 2. Therefore, when the reference output of the output from the second sensor element 3 when the first sensor element 2 is the physical quantity X ₁ that is the maximum or minimum is b, the output Q after the offset calibration is
Q = P−P ₂ + b
It is obtained by In the present embodiment, the value of b is 0.

  The relationship between the output V and output Q after the offset calibration as described above and the physical quantity X is as shown in FIG. The horizontal axis in FIG. 4 is a physical quantity X, and the vertical axis is an axis that also serves as outputs V and Q.

  Next, gain calibration will be described.

The gain calibration unit 10 calibrates the amplitude of the output V offset calibrated by the offset calibration unit 8, that is, performs gain calibration, and outputs an output W. As a specific gain calibration method, the amplitude at the output V is calibrated to the reference A. The amplitude at the output V is the absolute value of the maximum value or the minimum value of the output, which is an absolute value of Y ₁ -Y ₂ . Therefore, the output W is
W = A / │Y ₁ −Y ₂ │ ・ V
It is obtained by

The gain calibration unit 10 performs gain calibration of the output V, whereas the gain calibration unit 11 performs gain calibration of the output Q and outputs the output R. As a specific gain calibration method, the amplitude at the output Q is calibrated to the reference B. The amplitude at the output Q is the absolute value of the maximum value or the minimum value of the output, which is an absolute value of P ₁ -P ₂ . Therefore, the output R is
R = B / │P ₁ −P ₂ │ ・ Q
It is obtained by In the present embodiment, B is set to a value equal to A.

  The relationship between the output W and output R and the physical quantity X after the gain calibration as described above is as shown in FIG. The horizontal axis in FIG. 5 is a physical quantity X, and the vertical axis is an axis that serves as both output W and output R.

  The calculation unit 12 has a function of obtaining the physical quantity X from the output W and the output R. Although there are many specific ways of obtaining the physical quantity X, the relationship between the physical quantity X and the output W and output R is stored in advance in a data table, and the physical quantity X can be obtained from the output W and output R using this table. it can.

Also,
tan ^-1 (R / W)
Thus, it is possible to directly obtain without having a table.

  With the above configuration or method, even if the output change is less than one cycle, the offset calibration and gain calibration of the physical quantity sensor 1 can be performed, and the measurement accuracy can be improved.

(Embodiment 2)
A second embodiment of the present invention will be described. FIG. 6 is a block diagram of a physical quantity sensor according to Embodiment 2 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals.

  The physical quantity sensor in the second embodiment is configured by removing the gain calibration unit 11 from the physical quantity sensor in the first embodiment. The first sensor element 2, second sensor element 3, maximum / minimum detection unit 6, maximum / minimum detection unit 7, offset calibration unit 8, offset calibration unit 9, and gain calibration unit 10 according to the second embodiment are the same as those in the first embodiment. The function and operation are the same. In the physical quantity sensor 1 according to the second embodiment, the output from the first sensor element 2 performs offset calibration and gain calibration, and the output from the second sensor element 3 performs offset calibration.

  The calculation unit 12 calculates the physical quantity X from the output W obtained by offset calibration and gain calibration of the output Y from the first sensor element 2 and the output Q obtained by offset calibration of the output P from the second sensor element 3. In this case, two physical quantities X corresponding to the output W may exist, but one of the two physical quantities can be specified depending on whether the output Q is larger or smaller than the reference output b.

  Even in this case, it is possible to obtain a physical quantity sensor that can calibrate the output even if the output change is less than one cycle.

(Embodiment 3)
Embodiment 3 of the present invention will be described. FIG. 7 is a block diagram of a physical quantity sensor according to Embodiment 3 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals.

  The physical quantity sensor in the third embodiment is configured by removing the offset calibration unit 9 from the physical quantity sensor in the second embodiment. The first sensor element 2, the second sensor element 3, the maximum / minimum detection unit 6, the maximum / minimum detection unit 7, the offset calibration unit 8, and the gain calibration unit 10 in the third embodiment are the same as those in the second embodiment in terms of functions and operations. The same. The physical quantity sensor 1 according to the third embodiment performs offset calibration and gain calibration for the output from the first sensor element 2, and does not perform these calibrations for the output from the second sensor element 3.

  The calculation unit 12 calculates the physical quantity X from the output W obtained by offset calibration and gain calibration of the output Y from the first sensor element 2 and the output P from the second sensor element 3.

  In the present embodiment, when the output from the second sensor element 3 does not need to be calibrated, for example, when the output is adjusted with high accuracy in advance, even if the output change is less than one cycle, the configuration can be simplified. A physical quantity sensor that can calibrate the output can be obtained. Note that the calculation unit 12 can take a method of calculating based on the two outputs of the output W and the output P as in the case of the first embodiment, or first from the output W as in the second embodiment. It is also possible to use a method in which the number of candidates for the corresponding physical quantity X is reduced to two and which physical quantity X is selected by the output P.

(Embodiment 4)
Embodiment 4 of the present invention will be described. FIG. 8 is a block diagram of a physical quantity sensor according to Embodiment 4 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals. The physical quantity sensor in the fourth embodiment is obtained by removing the gain calibration unit 10 from the physical quantity sensor in the second embodiment. The first sensor element 2, the second sensor element 3, the maximum / minimum detection unit 6, the maximum / minimum detection unit 7, the offset calibration unit 8, and the offset calibration unit 9 in the fourth embodiment are the same as those in the second embodiment. The function is the same. The physical quantity sensor 1 according to the fourth embodiment performs offset calibration on the output from the first sensor element 2 and the output from the second sensor element 3, respectively.

  The calculation unit 12 calculates the physical quantity X based on the output V obtained by offset calibration of the output Y from the first sensor element 2 and the output Q obtained by offset calibration of the output P from the second sensor element 3.

  This embodiment is a useful method when it is not necessary to calibrate the gain of the output Y from the first sensor element 2. For example, there is a case where the gain of the output Y is adjusted in advance with high accuracy, or a case where the gain is calculated based on the magnitude compared with the reference output a of the output V and the magnitude compared with the reference output b of the output Q. In the latter case, a physical quantity in an area having a size obtained by dividing one period into four can be calculated.

  In the present embodiment as well, a physical quantity sensor capable of calibrating the output can be obtained even if the output change is less than one cycle.

(Embodiment 5)
Embodiment 5 of the present invention will be described. FIG. 9 is a block diagram of a physical quantity sensor according to Embodiment 5 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals.

  The physical quantity sensor in the fifth embodiment is obtained by removing the maximum / minimum detection unit 6 and the offset calibration unit 9 from the physical quantity sensor in the fourth embodiment. The first sensor element 2, the second sensor element 3, the maximum / minimum detection unit 7 and the offset calibration unit 8 according to the fifth embodiment have the same configuration and function as those of the fifth embodiment. The physical quantity sensor 1 in the fifth embodiment performs offset calibration on the output from the first sensor element 2.

  The calculation unit 12 calculates the physical quantity X from the output V obtained by offset calibration of the output Y from the first sensor element 2 and the output P from the second sensor element 3.

  This embodiment is useful when it is not necessary to calibrate the gain of the output Y from the first sensor element 2, and it is not necessary to perform offset calibration or gain calibration for the output P from the second sensor element 3. is there.

  In the first to fifth embodiments, the second sensor element 3 advances the phase difference between the output Y from the first sensor element 2 and the output P from the second sensor element 3 by 90 °. However, it is not limited to this. The output Y from the first sensor element 2 may be advanced by 90 ° from the output P of the second sensor element 3. Further, the phase difference may be other than 90 ° except for the phase difference of 0 ° and 180 °.

In this case, offset calibration can be performed by setting the output from the other sensor element to an appropriate value when the output of one sensor element is maximized or minimized. For example, when the phase of the output P is 45 ° ahead of the output Y, the reference output a of the first sensor element 2 when the second sensor element 3 takes a maximum is a = √2 / 2
And the reference output a when taking the minimum is a = −√2 / 2
In this case, the output waveform has an amplitude centering on 0, so that later signal processing becomes easy.

To generalize this, when the phase of the output P is advanced by θ from the output Y, the reference output a of the first sensor element 2 when the second sensor element 3 takes a maximum is a = cos θ.
age,
The reference output a of the first sensor element 2 when the second sensor element 3 is minimum is a = −cos θ
It is good to.

  The same applies to the reference output b of the second sensor element 3.

  In the maximum / minimum detection unit 6 and the maximum / minimum detection unit 7 described in the first to fifth embodiments, either the maximum or the minimum can be obtained. If it is small, it can be determined that it is maximum, and if the output value in the vicinity is large, it can be determined that it is minimum.

In the gain calibration of the first sensor element 2, the amplitude of the output waveform before gain calibration is
│Y ₁ −Y ₂ │
But using an arbitrary value c,
│ (Y ₁ + c)-(Y ₂ + c) │
As you may ask. The reason is that this formula, after all,
│Y ₁ −Y ₂ │
This is because it can be deformed.

  Therefore, the amplitude of the output V may be obtained directly.

in this case,
c = −Y ₂ + a
We are only looking for the value when
│Y ₁ −Y ₂ │
This is because it is none other than what is being asked for.

  Obviously, such a method is also one aspect of the embodiment of the present invention.

  The same applies to the method of obtaining the amplitude of the output waveform before the gain calibration of the second sensor element 3.

  The physical quantity sensor and the physical quantity measuring method according to the present invention are applicable and useful for sensors that measure various physical quantities.

DESCRIPTION OF SYMBOLS 1 Physical quantity sensor 2 1st sensor element 3 2nd sensor element 4 Signal processing part 5 Calibration part 6 Maximum / minimum detection part 7 Maximum / minimum detection part 8 Offset calibration part 9 Offset calibration part 10 Gain calibration part 11 Gain calibration part 12 Calculation Part

Claims (10)

A first sensor element that outputs an output value Y corresponding to the physical quantity X;
An output value P corresponding to the physical quantity X, a second sensor element having a phase of the output value different from the output value of the first sensor element;
A signal processing unit that outputs a physical quantity X to be measured by inputting an output value Y from the first sensor element and an output value P from the second sensor element;
The signal processing unit has a calibration unit that calibrates the output value Y at least,
The calibration unit is configured by the physical quantity X _2a and X _2b when the output value P of the second sensor element is P _a, the physical quantity X ₂ when the output of the second sensor element is a maximum or minimum X ₂ = (X _2a + X _2b ) / 2
A maximum / minimum detection unit obtained by
The output value Y of the first sensor element is converted into the output value V so that the output value Y ₂ of the first sensor element when the physical quantity is X ₂ is converted into the reference output a of the first sensor output element. V = Y−Y ₂ + a
An offset calibration unit to convert with
Physical quantity sensor equipped with. The maximum minimum detector further by the physical quantity X _1a and X _1b when the output value Y of the first sensor element is Y _a, the physical quantity when the output of the first sensor element is a maximum or minimum X ₁ is X ₁ = (X _1a + X _1b ) / 2
In
The calibration unit further determines the absolute value of the difference between the output value Y ₁ of the first sensor element and the output value Y ₂ when the physical quantity is X ₁ as a reference gain of the output value of the first sensor element. The output value V is set to the output value W such that A = W / A / | Y ₁ −Y ₂ | · V
A gain calibration section to convert with
The physical quantity sensor according to claim 1, further comprising: The calibration unit further calibrates the output value P,
The offset calibration unit is further said second sensor and the second sensor element so that the output value P ₂ is converted to the reference output b of the second sensor output elements of the device when the physical quantity is the X ₁ Output value P to output value Q Q = P−P ₂ + b
Convert with
The physical quantity sensor according to claim 2. Further, the gain correction unit, the reference physical quantity output value of the second sensor element an absolute value of the difference between the output value P ₁ and the output value P ₂ of the second sensor element when the X ₂ The output value Q is changed to the output value R so that the gain is B. R = B / | P ₁ −P ₂ | · Q
Convert with
The physical quantity sensor according to claim 3. The maximum minimum detector further by the physical quantity X _1a and X _1b when the output value Y of the first sensor element is Y _a, the physical quantity when the output of the first sensor element is a maximum or minimum X ₁ is X ₁ = (X _1a + X _1b ) / 2
In
The calibration unit further calibrates the output value P,
The offset calibration unit further physical quantity of the second sensor element to convert the output value P ₂ of the second sensor element when the X ₁ to the reference output b of the second sensor output element The output value P is changed to the output value Q. Q = P−P ₂ + b
Convert with
The physical quantity sensor according to claim 1. A step of output values P from the second sensor element for detecting a physical quantity X _2a and X _2b when the P _a,
The physical quantity X ₂ when the output value P from the second sensor element is a maximum value or a minimum value is expressed as X ₂ = (X _2a + X _2b ) / 2.
Steps to find in
Detecting an output value Y ₂ of the first sensor element when the physical quantity is X ₂ ;
When the reference output of the output value Y from the first sensor element is a, the output value Y from the first sensor element is converted into an output V after conversion.
V = Y−Y ₂ + a
Performing an offset calibration for conversion by:
Measuring method of physical quantity having. And detecting physical quantities X _1a and X _1b when the output value Y from the first sensor element is Y _a ;
The physical quantity X ₁ when the output value Y from the first sensor element is a maximum value or a minimum value is expressed as X ₁ = (X _1a + X _1b ) / 2.
Steps to find in
Detecting an output value Y ₁ of the first sensor element when the physical quantity is X ₁ ;
The output value V is set to the output value W so that the absolute value of the difference between the output value Y ₁ and the output value Y ₂ is set as a reference gain A of the output value of the first sensor element.
W = A / │Y ₁ −Y ₂ │ ・ V
The step of converting with
The physical quantity measuring method according to claim 6, wherein: A step of detecting an output value P ₂ of the second sensor element when the physical quantity is X ₁ ;
Q the output value Q of the output value P of the second sensor element to convert the output value P ₂ to the reference output b of the second sensor output element = P-P ₂ + b
The step of converting with
The physical quantity measuring method according to claim 7, wherein: A step of detecting an output value P ₁ of the second sensor element when the physical quantity is X ₂ ;
The output value Q is set to the output value R so that the absolute value of the difference between the output value P ₁ and the output value P ₂ is set as a reference gain B of the output value of the second sensor element.
R = B / │P ₁ −P ₂ │ ・ Q
The step of converting with
The physical quantity measuring method according to claim 8, wherein: And detecting physical quantities X _1a and X _1b when the output value Y from the first sensor element is Y _a ;
The physical quantity X ₁ when the output value Y from the first sensor element is a maximum value or a minimum value is expressed as X ₁ = (X _1a + X _1b ) / 2.
Steps to find in
A step of detecting an output value P ₂ of the second sensor element when the physical quantity is X ₁ ;
Q the output value Q of the output value P of the second sensor element to convert the output value P ₂ to the reference output b of the second sensor output element = P-P ₂ + b
The step of converting with
The physical quantity measuring method according to claim 6, wherein:

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