JP3548696B2 - Position detection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a position detection device that detects a position of a detection target in a non-contact manner.
[0002]
[Prior art]
A conventional general position detecting device will be described with reference to FIGS. FIG. 7 is a diagram showing a mechanical structure of a general position detecting device. In the drawing, reference numeral 1 denotes a core, which has a substantially symmetrical shape. A rotating ring 2 is mounted on one side 1a (left side in the figure) of the core 1, and a fixed ring 3 is mounted on the other side 1b (right side in the figure). The rotation ring 2 is connected to a detection target (not shown) by a rotation shaft 4. The rotation of the detection target rotates the rotation shaft 4, and the rotation ring 2 moves on the core 1 a according to the rotation of the rotation shaft 4. To move. A first coil L1 and a second coil L2 are wound around the cores 1a and 1b, respectively, and a magnetic path is formed by the core 1a and the rotating ring 2 or the core 1b and the fixed ring 3, respectively.
[0003]
In such a position detection device, the rotation shaft 4 rotates as the detection target rotates as described above. In response to the rotation of the rotating shaft 4, the rotating ring 2 moves on the core 1a, and the magnetic path formed by the core 1a and the rotating ring 2 changes, so that the inductance of the first coil L1 changes. On the other hand, the magnetic path formed by the core 1b and the fixed ring 3 does not change even when the detection target rotates, and the inductance of the second coil L2 does not change. The position of the detection target is detected from the relationship between the inductance of the first coil L1 and the inductance of the second coil L2.
[0004]
The above operation will be described with reference to FIGS. FIG. 8 is a circuit diagram showing an electrical configuration of a general position detecting device. The first coil L1 and the second coil L2 are connected in series, and the amplitude is constant at both ends (terminals ac). Is applied. Further, the voltage at both ends (terminals bc) of the second coil L2 is detected as the output Vout.
[0005]
In the position detection device configured as described above, the characteristics of the first coil L1 and the second coil L2 are such that the inductance of the first coil L1 changes with respect to the change of the position of the detection target as shown in FIG. However, the inductance of the second coil L2 is constant. Since two coils having such characteristics are connected in series, the amplitude of the output Vout generated at both ends of the second coil L2 has a characteristic as shown in FIG. 10 with respect to a change in the position of the detection target. Thus, by detecting this output Vout, the position of the detection target can be detected.
[0006]
[Problems to be solved by the invention]
Since the conventional position detection device as described above applies a sine wave alternating current having a constant amplitude as an input signal, an analog circuit for applying the sine wave is required, and the circuit configuration is complicated and the circuit scale is large. There is a problem that the mounting area becomes large.
[0007]
In addition, there is a problem that an adjustment operation for obtaining a predetermined frequency and amplitude is required, which complicates the operation, and a problem that the power is continuously consumed to maintain the oscillation and the power consumption is large. Was.
[0008]
The present invention position detecting apparatus according to the a first inductance element whose inductance varies according to the position change of the detection target, and the inductance regardless of the position change of the detection target is constant second inductance elements, said first and second A DC power supply commonly connected to one end of the second inductance element ; a resistor connected to both ends of the first and second inductance elements to form a time constant circuit with the inductance element; by comparing the terminal voltage and the predetermined voltage, a first comparing means for outputting a signal switched High level and the Low level to the other end of the first inductance element according to the comparison result, the other end of the first inductance element by comparing the voltage with a predetermined voltage, Hi to the other end of the second inductance element in accordance with the comparison result a second comparing means for outputting the h level and the Low level is switched signal, compares the other voltage and the predetermined voltage of the second inductance element, and outputs a signal switched High level and the Low level in accordance with the comparison result A third comparing unit, a fourth comparing unit that compares the other end voltage of the first inductance element with a predetermined voltage, and outputs a signal that switches between a high level and a low level according to the comparison result; and the third comparing unit. And a calculating means for calculating the position of the detection target based on the output signal of the fourth comparing means, wherein the calculating means includes a time constant circuit including the first inductance element and a time constant circuit including the second inductance element. The position of the detection target is calculated from the difference between the time constants.
[0009]
Further, a first integrator for converting the output signal of the third comparing means into a voltage value corresponding to the High time of the output signal and outputting the same, and an output signal of the fourth comparing means corresponding to the High time of the output signal . includes a second integrator that converts the voltage value, the differential amplifier outputs a voltage corresponding to the difference between the output of the output and the second integrator of the first integrator, the calculating means is the difference The position of the detection target is calculated based on the output of the dynamic amplifier .
[0010]
Also, a first inductance element whose inductance changes according to a change in the position of the detection target, a second inductance element having a constant inductance regardless of the change in the position of the detection target, and one end of the first and second inductance elements A DC power supply commonly connected, a resistor connected to both ends of the first and second inductance elements to form a time constant circuit with the inductance element, and a resistor connected to the other end of each of the first and second inductance elements. Comparing the connected first and second transistors, the oscillating means connected between the bases of the first and second transistors, and the other end voltage of the first inductance element with a predetermined voltage; Fifth comparing means for outputting a signal that switches between a high level and a low level in accordance with the second inductor and the second inductor By comparing the other end voltage and the predetermined voltage of the scan element, the comparison result and the sixth comparison means for outputting a signal switched High level and the Low level in accordance with, the fifth comparison means and the sixth comparative Calculating means for calculating a position of a detection target based on an output signal of the means, wherein the calculating means calculates a difference between a time constant circuit including the first inductance element and a time constant circuit including the second inductance element. Is used to calculate the position of the detection target.
[0011]
Further, a third integrator for converting the output signal of the fifth comparing means into a voltage value corresponding to the High time of the output signal and outputting the voltage value , and an output signal of the sixth comparing means corresponding to the High time of the output signal . includes a fourth integrator that converts the voltage value, the differential amplifier outputs a voltage corresponding to the difference between the outputs of the said fourth integrator of the third integrator, calculating means the difference The position of the detection target is calculated based on the output of the dynamic amplifier .
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment of the Invention
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The mechanical configuration is the same as that of the above-described general position detecting device, and the detailed description is omitted. FIG. 1 is a circuit diagram showing a circuit configuration of an embodiment of the present invention. A DC voltage Va is connected to a connection point (terminal b) between the first coil L1 and the second coil L2, and a resistor R is connected to the other side (terminals a and c) of each of the first coil L1 and the second coil L2. Have been.
[0013]
The output of the first comparator 11 is connected to the terminal a, and the output of the second comparator 12 is connected to the terminal c. A voltage Vc obtained by dividing a constant DC voltage Vb by resistors r1 and r2 is input to the positive input of each of the first comparator 11 and the second comparator 12, and each of the negative inputs is input to the negative input. , That is, the output of the second comparator 12 is connected to the first comparator 11, and the output of the first comparator 11 is connected to the second comparator 12.
[0014]
The output of the first comparator 11 is further connected to a negative input of a fourth comparator 14, and a voltage Vc is connected to a positive input of the fourth comparator 14. Similarly, the output of the second comparator 12 is connected to the minus input of the third comparator 13, and the voltage Vc is connected to the plus input of the third comparator 13. Further, the outputs of the third comparator 13 and the fourth comparator 14 are connected to a microcomputer (hereinafter referred to as a microcomputer) 20.
[0015]
The operation of the embodiment of the present invention configured as described above will be described. FIG. 2 is a timing chart showing the operation of the embodiment of the present invention. First, in the drawing, it is assumed that the second comparator 12 inverts the output V2 to a low level at time T1 according to the comparison result of the input. Due to this inversion, the negative input of the first comparator 11 becomes Low level, is compared with the positive input Vc, and the output V1 of the first comparator 11 is inverted to High level. Thereafter, the voltage V1 changes with a time constant t1 = L1 / R determined by the first coil L1 and the resistance R, and when the voltage decreases with time and becomes lower than the voltage Vc, the output of the second comparator 12 V2 is inverted to the high level, and the output V1 of the first comparator 11 is inverted to the low level.
[0016]
Similarly, after the output V2 of the second comparator 12 is inverted to the high level, the voltage V2 changes at a time constant t2 = L2 / R determined by the second coil L2 and the resistor R, and the voltage decreases with time. Then, when the voltage Vc becomes lower than the voltage Vc, the output V1 of the first comparator 11 is inverted to High level, and the output V2 of the second comparator 12 is inverted to Low level. As described above, in the first embodiment of the present invention, by applying a DC voltage, self-sustained pulsation is performed at a period T (T = t1 + t2) determined by time constants t1 = L1 / R and t2 = L2 / R. It becomes.
[0017]
As described above, the output V2 of the second comparator 12 and the voltage Vc are input to the third comparator 13, and the output V3 is synchronized with the inversion of the output V2 of the second comparator 12. Invert. Similarly, the output V1 of the first comparator 11 and the voltage Vc are input to the fourth comparator 14, and the output V4 is inverted in synchronization with the inversion of the output V1 of the first comparator 11. These outputs V3 and V4 are input to the microcomputer 20.
[0018]
It is assumed that the position of the detection target has changed from P1 to P2 at time T2. In this case, as described above, the inductance of the first coil L1 changes and the time constant t1 changes. On the other hand, since the inductance of the second coil L2 does not change, the time constant t2 does not change. Therefore, the High time of the output V3 of the third comparator 13 changes, and the High time of the output V4 of the fourth comparator 14 does not change.
[0019]
The microcomputer 20 receives the output V3 and the output V4, and calculates the position of the detection target from the input signal. That is, as described above, the inductances of the first coil L1 and the second coil L2 have characteristics as shown in FIG. 9 with respect to the change in the position of the detection target, and the inductance difference is calculated backward from the time difference between the two outputs. The position of the detection target can be calculated from the characteristics shown in FIG.
[0020]
As described above, by configuring the self-excited oscillation cycle to change according to the position change of the detection target, there is no need to apply a sine wave signal as an input signal. The circuit can be omitted, the circuit configuration can be simplified and the size can be reduced, the mounting area can be reduced, and the device itself can be downsized.
[0021]
In addition, because of High / Low inversion, the power consumption is zero at the time of Low, and the power consumption as a whole can be reduced. Further, since oscillation using a time constant due to inductance and resistance is used, the degree of freedom in setting the frequency is high, adjustment is not required, and the operation can be simplified.
[0022]
In the first embodiment described above, the outputs of the third comparator 13 and the fourth comparator 14 are directly input to the microcomputer 20 and the difference between the High time of each output signal is calculated in the microcomputer 20. As shown in (1), a first integrator 31 and a second integrator 32 for integrating the outputs of the third comparator 13 and the fourth comparator 14, respectively, are provided, whereby each output signal corresponds to the High time of the output signal. The converted voltage values can be input to the microcomputer 20 via the differential amplifier 40 that outputs a voltage value corresponding to the difference between the converted voltage values.
[0023]
As described above, the microcomputer 20 generally converts the voltage into a voltage value corresponding to the output of the third comparator 13 and the fourth comparator 14 and inputs the voltage value according to the difference to the microcomputer 20. A signal corresponding to the position of the detection target can be obtained using the analog / digital conversion function described above, and the calculation load on the microcomputer 20 can be reduced as compared with the above-described embodiment.
[0024]
Embodiment 2 of the invention
Next, another embodiment according to the present invention will be described. FIG. 4 is a circuit diagram showing another embodiment of the present invention. A DC voltage Va is connected to a connection point (terminal b) between the first coil L1 and the second coil L2, and the first coil L1 and the second coil L1 are connected to each other. A resistor R is connected to the other side (terminals a and c) of each of L2.
[0025]
A first transistor Q1 and a second transistor Q2 are connected to the terminals a and c, respectively, as switching means. An oscillator 50 that outputs a rectangular wave is connected to the first transistor Q1 and the second transistor Q2. The output of the oscillator 50 turns the first transistor Q1 and the second transistor Q2 on or off.
[0026]
Reference numeral 15 denotes a fifth comparator, which has a positive input terminal connected to a connection point of the first coil L1 and the resistor R, and a reference voltage Vc (a constant DC voltage Vb) connected to the negative input terminal. Is divided by the resistors r1 and r2) and the voltage V1 at the connection point.
[0027]
Similarly, reference numeral 16 denotes a sixth comparator, which has a plus input terminal connected to a connection point of the second coil L2 and the resistor R, a reference voltage Vc connected to the minus input terminal, and a connection point. Is compared with the voltage V2. The output V5 of the fifth comparator 15 and the output V6 of the sixth comparator 16 are input to the microcomputer 20.
[0028]
Next, the operation of the position detecting device according to the second embodiment configured as described above will be described with reference to a timing chart shown in FIG. The first transistor Q1 and the second transistor Q2 are turned on or off by the rectangular wave output from the oscillator 50. If the output of the oscillator 50 is at the low level at the time T1, the first transistor Q1 is off and V1 is at the high level. Thereafter, the voltage decreases according to a time constant t3 = L1 / R determined by the first coil L1 and the resistor R. This V1 is input to the fifth comparator 15 as described above. The fifth comparator 15 compares this V1 with the reference voltage Vc, and keeps V5 at a high level while V1> Vc holds. Output as
[0029]
If the output of the oscillator 50 is at a low level, the second transistor Q2 is also off, and V2 is at a high level. Thereafter, the voltage drops according to a time constant t4 = L2 / R determined by the second coil L2 and the resistor R. . This V2 is input to the sixth comparator 12, and the sixth comparator 16 compares V2 with Vc and outputs V6 as a High level while V2> Vc holds.
[0030]
The second embodiment basically operates in this way, but it is assumed that the position of the detection target has changed from P1 to P2 at time T2. In this case, as described above, the rotating ring 2 moves according to the change in the position of the detection target, and the inductance of the first coil L1 changes. Due to the change in the inductance of the first coil L1, the voltage V1 at the connection point between the first coil L1 and the resistor R is affected by the change in the time constant t3 = L1 / R, and the rate of voltage decrease changes. The period t3 during which the output V5 of the detector 15 becomes High changes. On the other hand, as described above, even if the position of the detection target changes, the inductance of the second coil L2 does not change, so that the period t4 during which the output V6 of the sixth comparator 16 becomes High does not change.
[0031]
As described above, V5 in which the High period changes according to the change in the position of the detection target and V6 in which the High period does not change are input to the microcomputer 20, and the position of the detection target is calculated from this input signal. . That is, as described above, since the inductance of the first coil L1 and the inductance of the second coil L2 have a characteristic as shown in FIG. 9 with respect to a change in the position of the detection target, the microcomputer 20 sets the high period of these signals to high. The difference between t3 and t4 is calculated, the difference in inductance is calculated back from the time difference between the two outputs, and the position of the detection target can be calculated from the characteristics in FIG.
[0032]
In the second embodiment according to the present invention described above, since the on / off operation is performed using the rectangular wave, the power consumption at the time of off is zero, the power consumption as a whole can be reduced, and the inductance and the power consumption can be reduced. Since the time constant based on the resistance is used, there is a high degree of freedom in setting the period, no adjustment is required, and the operation can be simplified.
[0033]
Furthermore, compared to the above-described first embodiment of the self-excited system, the detection accuracy is not deteriorated due to a change in the ambient temperature or an aging change, and the position of the detection target can be detected more accurately.
[0034]
In the second embodiment described above, the outputs of the fifth comparator 15 and the sixth comparator 16 are directly input to the microcomputer 20, and the microcomputer 20 calculates the difference between the High times of the output signals. As shown in the figure, a third integrator 33 and a fourth integrator 34 for integrating the outputs of the fifth comparator 15 and the sixth comparator 16, respectively, are provided, and these output signals correspond to the High time of the output signal. The converted voltage values can be input to the microcomputer 20 via the differential amplifier 40 that outputs a voltage value corresponding to the difference between the converted voltage values.
[0035]
As described above, the microcomputer 20 generally includes the voltage value corresponding to the output of the fifth comparator 15 and the sixth comparator 16 and inputs the voltage value corresponding to the difference to the microcomputer 20. By using the analog / digital conversion function, a signal corresponding to the position of the detection target can be obtained, and the calculation load of the microcomputer 20 can be reduced as compared with the second embodiment.
[0036]
【The invention's effect】
The present invention position detecting apparatus according to the a first inductance element whose inductance varies according to the position change of the detection target, and the inductance regardless of the position change of the detection target is constant second inductance elements, said first and second A DC power supply commonly connected to one end of the second inductance element ; a resistor connected to both ends of the first and second inductance elements to form a time constant circuit with the inductance element; by comparing the terminal voltage and the predetermined voltage, a first comparing means for outputting a signal switched High level and the Low level to the other end of the first inductance element according to the comparison result, the other end of the first inductance element by comparing the voltage with a predetermined voltage, Hi to the other end of the second inductance element in accordance with the comparison result a second comparing means for outputting the h level and the Low level is switched signal, compares the other voltage and the predetermined voltage of the second inductance element, and outputs a signal switched High level and the Low level in accordance with the comparison result A third comparing unit, a fourth comparing unit that compares the other end voltage of the first inductance element with a predetermined voltage, and outputs a signal that switches between a high level and a low level according to the comparison result; and the third comparing unit. And a calculating means for calculating the position of the detection target based on the output signal of the fourth comparing means, wherein the calculating means includes a time constant circuit including the first inductance element and a time constant circuit including the second inductance element. , The position of the detection target is calculated from the difference between the time constants of the first and second inductance elements and each resistor. Self-excited oscillation depending on the change of the position of the detection target, and the period of the self-excited oscillation changes according to the change of the position of the detection target. Since the position of the detection target can be calculated from this period, a sine wave signal is applied as an input signal There is no need to apply this sine wave, so that the analog circuit can be omitted, the circuit configuration can be simplified and the size can be reduced, the mounting area can be reduced, and the device itself can be downsized. Play. In addition, because of High / Low inversion, the power consumption is zero at the time of Low, and the power consumption as a whole can be reduced. In addition, since the oscillation using the time constant due to the inductance and the resistance is used, the stability of the frequency and the degree of freedom in setting are high, the adjustment is not required, and the operation can be simplified.
[0037]
Further, a first integrator for converting the output signal of the third comparing means into a voltage value corresponding to the High time of the output signal and outputting the same, and an output signal of the fourth comparing means corresponding to the High time of the output signal . includes a second integrator that converts the voltage value, the differential amplifier outputs a voltage corresponding to the difference between the output of the output and the second integrator of the first integrator, the calculating means is the difference By calculating the position of the detection target based on the output of the dynamic amplifier , the calculation load of the calculation means can be reduced.
[0038]
Also, a first inductance element whose inductance changes according to a change in the position of the detection target, a second inductance element having a constant inductance regardless of the change in the position of the detection target, and one end of the first and second inductance elements A DC power supply commonly connected, a resistor connected to both ends of the first and second inductance elements to form a time constant circuit with the inductance element, and a resistor connected to the other end of each of the first and second inductance elements. Comparing the connected first and second transistors, the oscillating means connected between the bases of the first and second transistors, and the other end voltage of the first inductance element with a predetermined voltage; Fifth comparing means for outputting a signal that switches between a high level and a low level in accordance with the second inductor and the second inductor By comparing the other end voltage and the predetermined voltage of the scan element, the comparison result and the sixth comparison means for outputting a signal switched High level and the Low level in accordance with, the fifth comparison means and the sixth comparative Calculating means for calculating a position of a detection target based on an output signal of the means, wherein the calculating means calculates a difference between a time constant circuit including the first inductance element and a time constant circuit including the second inductance element. Since the position of the detection target is calculated from the above, the position can be detected by the on / off method using the rectangular wave, so that the power consumption at the time of off becomes zero, and the power consumption as a whole can be reduced. . In addition, since the time constant of the inductance and the resistance is used, the degree of freedom in setting the cycle is high, the adjustment is unnecessary, the operation can be simplified, and a rectangular wave generated by the oscillating means is used as an input signal. As a result, the detection accuracy is not deteriorated due to a change in the ambient temperature or a change over time, and the position of the detection target can be detected more accurately.
[0039]
Further, a third integrator for converting the output signal of the fifth comparing means into a voltage value corresponding to the High time of the output signal and outputting the voltage value , and an output signal of the sixth comparing means corresponding to the High time of the output signal . includes a fourth integrator that converts the voltage value, the differential amplifier outputs a voltage corresponding to the difference between the outputs of the said fourth integrator of the third integrator, calculating means the difference By calculating the position of the detection target based on the output of the dynamic amplifier , the calculation load of the calculation means can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing one embodiment according to the present invention.
FIG. 2 is a timing chart showing an operation of one embodiment according to the present invention.
FIG. 3 is a circuit diagram showing a modification of the embodiment according to the present invention.
FIG. 4 is a circuit diagram showing another embodiment according to the present invention.
FIG. 5 is a timing chart showing the operation of another embodiment according to the present invention.
FIG. 6 is a circuit diagram showing a modification of another embodiment according to the present invention.
FIG. 7 is a diagram illustrating a mechanical configuration of a general position detection device.
FIG. 8 is a circuit diagram showing a general position detecting device.
FIG. 9 is a diagram illustrating characteristics of a general position detection device.
FIG. 10 is a diagram illustrating characteristics of a general position detection device.
[Explanation of symbols]
L1 first coil L2 second coil 11 first comparator 12 second comparator 13 third comparator 14 fourth comparator 15 fifth comparator 16 sixth comparator 20 microcomputer 31 first integrator 32 second integration Unit 33 third integrator 34 fourth integrator 40 amplifier 50 oscillator

Claims (4)

A first inductance element whose inductance changes according to a change in the position of the detection target; a second inductance element having a constant inductance regardless of the change in the position of the detection target; and a common connection to one end of the first and second inductance elements. A DC power supply, a resistor connected to both ends of each of the first and second inductance elements and constituting a time constant circuit together with the inductance element, and a voltage at the other end of the second inductance element and a predetermined voltage are compared. The first comparing means for outputting a signal that switches between a high level and a low level to the other end of the first inductance element according to the comparison result, and comparing the other end voltage of the first inductance element with a predetermined voltage. , the other end of the second inductance element according to the comparison result High level and the Low level switches A second comparing means for outputting a that signal, and a third comparison means for comparing the other voltage and the predetermined voltage of the second inductance element, and outputs a signal switched High level and the Low level in accordance with the comparison result, A fourth comparing means for comparing a voltage at the other end of the first inductance element with a predetermined voltage and outputting a signal for switching between a high level and a low level in accordance with the comparison result; the third comparing means and the fourth comparing means Calculating means for calculating the position of the detection target based on the output signal of the above, wherein the calculating means calculates a difference between a time constant circuit including the first inductance element and a time constant circuit including the second inductance element. A position detecting device for calculating a position of a detection target. The third output signal of the comparison means and the first integrator that converts the voltage value corresponding to the High time of the output signal, a voltage value corresponding to the output signal of the fourth comparison means High time of the output signal includes a second integrator for converting and outputting, a differential amplifier for outputting a voltage corresponding to the difference between the output of the output and the second integrator of the first integrator, the calculating means is the differential amplifier 2. The position detecting device according to claim 1, wherein the position of the detection target is calculated based on the output of the position detecting device. A first inductance element whose inductance changes according to a change in the position of the detection target; a second inductance element having a constant inductance regardless of the change in the position of the detection target; and a common connection to one end of the first and second inductance elements. DC power supply, a resistor connected to both ends of the first and second inductance elements and forming a time constant circuit together with the inductance element, and a resistor connected to the other end of each of the first and second inductance elements. Comparing the first and second transistors, the oscillating means connected between the bases of the first and second transistors, and the other end voltage of the first inductance element with a predetermined voltage, and according to the comparison result. A fifth comparing means for outputting a signal for switching between a high level and a low level, and the second inductance element. The other end voltage and then comparing the predetermined voltage, and a sixth comparison means for outputting a signal switched High level and the Low level in accordance with the comparison result, the fifth comparison means and the sixth comparison means Calculating means for calculating the position of the detection target based on the output signal, wherein the calculating means detects from a difference in time constant between a time constant circuit including the first inductance element and a time constant circuit including the second inductance element. A position detecting device for calculating a position of an object. The fifth output signal of the comparison means and the third integrator that converts the voltage value corresponding to the High time of the output signal, the voltage value of the output signal of the sixth comparison means corresponds to the High time of the output signal includes a fourth integrator for converting and outputting, a differential amplifier for outputting a voltage corresponding to the difference between the outputs of the said fourth integrator of the third integrator, the calculating means is the differential amplifier 4. The position detecting device according to claim 3, wherein the position of the detection target is calculated based on the output of the position detecting device.

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