JP5600636B2 - Position detection device - Google Patents

Description

  The present invention relates to a position detection device.

  Conventionally, a resolver that detects a rotational position of a detection target is known as an inductive position detection device. The resolver includes a rotor and a stator. The rotor is provided with a primary coil, and the stator is provided with two secondary coils. The two secondary coils are provided such that the angle difference between them is 90 °. When an excitation voltage is applied to the primary coil, two output voltages (sine wave and cosine wave) having a phase difference of 90 ° are extracted through the two secondary coils. Since these output voltages change according to the rotation angle of the detection target, the rotation position of the detection target can be detected based on these output voltages. Patent Document 1 describes a tilt detection device that detects the tilt of a detection target using the same detection principle as that of the resolver. The apparatus includes a magnetic body that is displaced in accordance with the inclination of the detection target, and the inclination of the detection target is determined by changing output voltages induced in the two secondary coils in accordance with the displacement of the magnetic body. To detect.

JP-A-10-176925

  However, the conventional inductive position detection device has the following problems. That is, the output voltages induced in the two secondary coils are converted into digital signals by the two A / D conversion circuits provided corresponding to the secondary coils. Then, the position of the detection target is calculated based on these two converted digital signals. In recent years, there is a demand for simplification of the circuit configuration of the position detection device from the viewpoint of reducing the product cost, but the conventional position detection device requires two A / D conversion circuits. This has been one of the impediments to simplifying the circuit configuration.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a position detection device that can contribute to simplification of the circuit configuration.

The invention according to claim 1 is provided so as to be capable of relative displacement with respect to a detection target made of a magnetic material or a conductor in a state of being provided at 90 ° intervals around a specific axis and connected in series to each other. Two coils, an excitation signal generator for exciting each of the four coils by shifting the phase in time by 90 °, and an analog voltage generated in each of the four coils when excited through the excitation signal generator. Is obtained at a first timing at which the voltage generated in a specific coil is maximized, and at a second timing at which the phase of the voltage at the first timing is shifted by 90 ° in time. The detection based on a combination of one A / D converter and a digital value of the combined signal captured at the first and second timings by the A / D converter. A calculator for calculating the position of the elephant, to become comprise as its gist.

  According to the present invention, after four coils are connected in series, the temporal phases of the coils are excited with a 90 ° shift. In addition, first and second timings are set as capture timings of the A / D converter, and composite signals of four secondary coils are captured at these two timings. The first timing is the timing at which the amplitude of the analog voltage generated in a specific secondary coil becomes maximum, and the second timing is the timing at which the phase of the analog voltage is shifted by 90 ° with respect to the first timing. The

  For this reason, the combined signal of the four coils captured at the first timing has a value corresponding to the combined signal generated in the two coils including the specific coil excited with a phase difference of 180 °. The combined signal of the four coils captured at the second timing has a value corresponding to the combined signal generated in the remaining two coils. The value of the synthesized signal sampled at the first and second timings changes according to the position of the detection target. That is, the combination of the values of the synthesized signal sampled at the first and second timings is unambiguous with respect to the detection target position.

  Therefore, the position of the detection target can be detected by the single A / D converter based on the combination of the values of the combined signals of the four coils captured at the first and second timings. Here, it is also assumed that the combined signals of two coil pairs, each consisting of two coils excited with a phase difference of 180 °, are separately captured by two A / D converters corresponding to each group. However, unlike this case, it is only necessary to provide a single A / D converter in the present invention, which can contribute to the simplification of the circuit configuration of the position detection device.

According to a second aspect of the present invention, in the position detection device according to the first aspect, the excitation signal generator generates a clock signal having a clock frequency four times the excitation frequency, and is set based on the clock signal. The gist is to excite each of the four coils at a timing.

  According to the present invention, by shifting the sampling timing of the clock signal, it is possible to easily generate an excitation signal having a frequency that is ¼ of the clock frequency, and thus four excitation signals whose temporal phases are shifted from each other by 90 °. is there.

According to a third aspect of the invention, the position detecting device according to claim 1 or claim 2, wherein the four coils are provided on the same mounting surface, wherein the detection target, changing the distance with respect to the installation surface The gist of the invention is that it can be displaced in a manner.

According to the present invention, a composite signal corresponding to a change in the distance to the installation surface is generated. Based on this synthesized signal, the displacement of the detection target can be detected.
The invention according to claim 4 is the position detection device according to claim 3, wherein the installation surface is a plane, the specific axis is set to be orthogonal to the plane, and the detection target is: The gist of the invention is that it is provided so as to be displaceable in such a manner as to face the four coils in the direction along the specific axis and to change the distance from the plane in the direction along the specific axis.

  According to the present invention, a combined signal corresponding to the distance between the detection target and the plane that is the installation surface of the coil is obtained. Based on this combined signal, it is possible to detect a position where an external force directed to a plane with respect to the detection target, that is, a pressed position is detected.

According to a fifth aspect of the present invention, in the position detection device according to any one of the first to third aspects, the four coils are along a virtual cylindrical surface centered on the specific axis. The gist of the invention is that the detection object is provided so as to be rotatable around the specific axis or another axis parallel to the specific axis.

  According to the present invention, it is possible to detect the rotational position of the detection target based on the combination of the values of the combined signals of the four coils captured at the first and second timings by a single A / D converter.

  ADVANTAGE OF THE INVENTION According to this invention, it can contribute to simplification of the circuit structure of a position detection apparatus.

(A) is a disassembled perspective view of the position detection apparatus in 1st Embodiment, (b) is a bottom view of a board | substrate similarly. FIG. 1 is a sectional view taken along line 1-1 of FIG. The circuit block diagram of a position detection apparatus. The wave form diagram of the output signal which shows the taking-in timing of an A / D converter. (A), (b) is a wave form diagram of a clock signal which shows the generation method of an excitation signal. (A) is a 2-2 line arrow directional view of FIG. 1, (b) is each waveform diagram when not pressed down. FIG. 8A is a view taken along line 2-2 in FIG. 1 showing a pressed position, and FIG. 7B is a waveform diagram when pressed at the pressed position shown in FIG. FIG. 9A is a view taken along line 2-2 in FIG. 1 showing another pressing position, and FIG. 8B is a waveform diagram when the pressing is performed at the pressing position shown in FIG. FIG. 10A is a view taken along line 2-2 in FIG. 1 showing another pressing position, and FIG. 9B is a waveform diagram when the pressing is performed at the pressing position shown in FIG. The circuit block diagram of the position detection apparatus in 2nd Embodiment. The perspective view which shows schematic structure of the position detection apparatus in 3rd Embodiment. Sectional drawing corresponding to FIG. 2 in other embodiment.

<First Embodiment>
Hereinafter, an embodiment in which the present invention is embodied in a pressed position detecting device that detects a pressed position with respect to a detection target will be described with reference to FIGS. 1 (a), (b) to 6 (a), (b). To do.

  As shown in FIG. 1A, the pressed position detection device 11 includes a substrate 12 having insulation properties and a detection target 13 that faces the substrate 12. The detection target 13 is formed in a rectangular plate shape by a magnetic material such as iron or ferrite. Four compression coil springs 14 are interposed between the substrate 12 and the four corners of the detection target 13, respectively. The detection target 13 is normally maintained in a state parallel to the surface of the substrate 12.

  As shown in FIG. 2, when an external force is applied to the side surface of the detection target 13 opposite to the substrate 12, the detection target 13 approaches the substrate 12 against the elastic force of the compression coil spring 14. Displace in the direction. For example, when an external force directed to the substrate 12 is applied to the center of the detection target 13, the detection target 13 is resistant to the elastic force of the four compression coil springs 14 while maintaining a parallel state with respect to the substrate 12. It is displaced in the direction approaching the substrate 12. When an external force toward the substrate 12 is applied to a portion other than the center of the detection target 13, the detection target 13 is inclined with respect to the surface of the substrate 12 and the elastic force of the four compression coil springs 14. Against the substrate 12 in a direction approaching the substrate 12.

  The pressed position detection device 11 detects the displacement of the detection target 13 and detects a position where the external force is applied to the detection target 13, that is, a pressed position with respect to the detection target 13 based on the detection result. And in order to detect the said press position, the following structures are employ | adopted.

  That is, as shown in FIG. 1A, the surface of the substrate 12 is provided with first to fourth secondary coils 15a to 15d formed by winding a conductive wire in a spiral shape. The first to fourth secondary coils 15 a to 15 d are provided every 90 ° around the axis orthogonal to the substrate 12 and are connected in series to each other. As shown in FIG. 1B, first to fourth primary coils 16 a to 16 d are provided on the back surface of the substrate 12. The first to fourth primary coils 16 a to 16 d are also provided every 90 ° around the axis perpendicular to the substrate 12. The first to fourth primary coils 16a to 16d are opposed to the first to fourth secondary coils 15a to 15d with the substrate 12 interposed therebetween. Both ends of the first to fourth primary coils 16 a to 16 d and both ends of the first to fourth secondary coils 15 a to 15 d connected in series are connected to the detection circuit 17.

  The detection circuit 17 applies excitation signals to the first to fourth primary coils 16a to 16d, respectively, and induces them in the series circuit of the first to fourth secondary coils 15a to 15d according to the displacement of the detection target 13. The position of the detection target 13 is obtained based on the applied voltage (precisely, the combined signal that is the sum of the voltages induced in the first to fourth secondary coils 15a to 15d).

  The voltages induced in the first to fourth secondary coils 15a to 15d change in accordance with the proximity positional relationship of the detection target 13 with respect to the first to fourth secondary coils 15a to 15d. That is, according to the distance between the first to fourth secondary coils 15a to 15d and the detection target 13, the first to fourth secondary coils 15a to 15d and the first to fourth corresponding to these. The degree of magnetic coupling (electromagnetic induction coupling) between the primary coils 16a to 16d changes. The closer the detection target 13 is to the first to fourth secondary coils 15a to 15d, the greater the value of the voltage induced in the first to fourth secondary coils 15a to 15d. Conversely, as the detection target 13 is separated from the first to fourth secondary coils 15a to 15d, the value of the voltage induced in the first to fourth secondary coils 15a to 15d decreases. .

<Detection circuit>
Next, the configuration of the detection circuit 17 will be described. As shown in FIG. 3, the detection circuit 17 includes an A / D converter 21 and a calculator 22. The detection circuit 17 includes an excitation signal generator 23 and a capture timing controller 24.

  The A / D converter 21 captures a composite signal that is the sum of the output voltages (analog voltages) of the first to fourth secondary coils 15a to 15d, and converts the captured composite signal into a digital signal (digital value). To do.

The calculator 22 calculates the displacement of the detection target 13, that is, the pressed position with respect to the detection target 13 based on the digital signal generated by the A / D converter 21.
The excitation signal generator 23 generates an excitation signal and applies the generated excitation signal to the first to fourth primary coils 16a to 16d, respectively. In this example, the excitation signal generator 23 has a clock frequency that is four times the frequency of the excitation signal. That is, the oscillator of the excitation signal generator 23 generates a clock signal having a frequency four times the frequency of the excitation signal. For example, when the frequency of the excitation signal is 10 kHz, the clock frequency of the excitation signal generator 23 is 40 kHz. The excitation signal generator 23 generates four excitation signals whose temporal phases are shifted from each other by 90 ° at a timing set based on the clock signal generated by the oscillator, and the generated excitation signals are first to first. It applies to the 4th primary coils 16a-16d, respectively. Specifically, when the phase of the excitation signal applied to the first primary coil 16a is a reference, that is, when the phase difference is 0 °, the second primary coil 16b is 180 °, and the third primary coil 16c is 90 °. An excitation signal having a phase difference of 270 ° is applied to the fourth primary coil 16d.

  The excitation signal generator 23 generates these excitation signals as follows. That is, as shown in FIG. 5A, in a 40 kHz clock signal, an excitation signal of 10 kHz can be generated if timing is taken every four cycles. Then, as shown in FIG. 5B, an excitation signal having a phase difference of 90 ° can be generated by shifting the sampling timing of the clock signal by, for example, one pulse.

  The capture timing controller 24 applies the excitation signal to the first to fourth primary coils 16a to 16d and the combined signal of the first to fourth secondary coils 15a to 15d connected in series with each other. Synchronize with the timing of importing. That is, the capture timing controller 24 captures the clock signal generated by the excitation signal generator 23 and the conversion result of the A / D converter 21, respectively, and based on the captured clock signal and the A / D conversion result, The timing for taking in the A / D converter 21 is controlled.

  The capture timing controller 24 is a first timing at which the amplitude of the output voltage of a specific secondary coil (for example, the first secondary coil 15a) among the first to fourth secondary coils 15a to 15d is maximized. T1 is stored. As shown in FIG. 4, the capture timing controller 24 is based on the clock signal generated by the excitation signal generator 23 and each time it is detected that the first timing T1 has arrived, the A / D of the combined signal is detected. A command signal indicating that the conversion result is captured is generated. The capture timing controller 24 also has a second timing T2 in which the temporal phase of a specific secondary coil (here, the first secondary coil 15a) is shifted by 90 ° with respect to the first timing T1. I remember it. The capture timing controller 24 is a command signal indicating that the A / D conversion result of the composite signal is captured every time it is detected that the second timing T2 has arrived, based on the clock signal generated by the excitation signal generator 23. Is generated. The A / D converter 21 takes in the synthesized signal based on the command signal generated by the take-in timing controller 24 (more precisely, stores it in the RAM). Note that the first and second timings T1 and T2 are obtained in advance by experiments or simulations.

<Pressing position detection method>
Next, a method for detecting the pressed position by the pressed position detecting device will be described. Here, the timing at which the amplitude of the output signal Va (voltage) of the first secondary coil 15a is maximized is the first timing T1, and the temporal phase of the output signal Va with respect to the first timing T1 is 90. A point shifted by ° is set as a second timing T2.

<Normal state>
First, as shown in FIG. 6A, a method for detecting that the detection target 13 is in a normal state where no external force is applied will be described.

  In this case, the amplitudes of the output signals of the first to fourth secondary coils 15a to 15d change as shown in the graph of FIG. 6B. The output signals Va and Vb of the first and second secondary coils 15a and 15b are 180 degrees out of phase with each other. This is because the first and second secondary coils 15a and 15b are excited in opposite phases. Further, the output signals Vc and Vd of the third and fourth secondary coils 15c and 15d are 90 degrees in phase with respect to the output signals Va and Vb of the first and second secondary coils 15a and 15b, respectively. Shift. This is because the third and fourth secondary coils 15c and 15d are excited with a phase shift of 90 ° with respect to the first and second secondary coils 15a and 15b. Further, the output signals Vc, Vd of the third and fourth secondary coils 15c, 15d are 180 degrees out of phase with each other. This is because the third and fourth secondary coils 15c and 15d are excited in opposite phases.

  Therefore, the combined signal Vab represented by the sum of the output signals Va and Vb of the first and second secondary coils 15a and 15b, and the output signals Vc and Vd of the third and fourth secondary coils 15c and 15d. The combined signal Vcd represented by the sum of the values becomes 0 (zero). As a result, the value of the composite signal Vad, which is the sum of the output signals Va to Vd of the first to fourth secondary coils 15a to 15d, is also 0 (zero). Therefore, the values of the first and second combined signals Vad1 and Vad2 sampled at the first and second timings T1 and T2 are 0, respectively. The detection circuit 17 detects that the detection target 13 is in a normal state based on the combination of the values of the first and second combined signals Vad1 and Vad2. That is, it can be seen that the distances between the first to fourth secondary coils 15a to 15d and the detection target 13 are the same.

  In this normal state, when an external force is applied to the point P0, which is the center of the detection target 13, the amplitude of each of the output signals Va to Vd increases, but the first and second timings T1 and T2 are the first. The values of the first and second composite signals Vad1 and Vad2 are 0, respectively. Although the distance between the first to fourth secondary coils 15a to 15d and the detection target 13 is smaller than that in the normal state described above, the distance remains the same. For this reason, when detecting the presence or absence of application of external force to the point P0 of the detection target 13, for example, a detection means such as a proximity sensor is separately provided on the substrate 12. When the value of the composite signal Vad is maintained at 0 (zero) and the proximity of the detection target 13 to the substrate 12 is detected through the detection unit, the detection circuit 17 presses the point P0 of the detection target 13. Judgment is made.

  Further, when detection of pressing of the point P0 is not required, the pressed position detection device may be configured as follows. That is, as shown in FIG. 12, a pivot shaft 18 is provided at a portion corresponding to the point P0 on the back surface (surface on the substrate 12 side) of the detection target 13, and the detection target 13 can be tilted with the pivot shaft 18 as a fulcrum. To do.

<When the first point P1 is pressed>
Next, a case where a large external force is applied to a portion of the detection target 13 in the vicinity of the first secondary coil 15a as indicated by the first point P1 in FIG. 7A will be described.

  In this case, the detection target 13 is in close proximity to the first secondary coil 15a against the elastic force of the compression coil spring 14 and according to the magnitude of the external force, while on the second secondary coil 15b. It inclines so that it may space apart. Then, as shown in FIG. 7B, the amplitude of the output signal Va of the first secondary coil 15a is higher than that in the normal state shown in FIG. Increases by the proximity. On the other hand, the output signal Vb of the second secondary coil 15b has a smaller amplitude due to the separation of the detection target 13 compared to the previous normal state (in the figure, the state approximated to 0). Showing). The amplitudes of the output signals Vc and Vd of the third and fourth secondary coils 15c and 15d change in the same manner as in the normal state.

  The amplitude of the composite signal Vab represented by the sum of the output signals Va and Vb of the first and second secondary coils 15a and 15b changes in the same manner as the output signal Va of the first secondary coil 15a. That is, the amplitude of the composite signal Vab at the first timing T1 increases with a positive value compared to the previous normal state. Further, the combined signal Vcd represented by the sum of the output signals Vc and Vd of the third and fourth secondary coils 15c and 15d is 0 (zero), respectively. This is because the output signals Vc, Vd of the third and fourth secondary coils 15c, 15d are in opposite phases to each other and are cancelled. Therefore, the amplitude of the composite signal Vad represented by the sum of the output signals Va to Vd of the first to fourth secondary coils 15a to 15d changes in the same manner as the output signal Va of the first secondary coil 15a. .

  Therefore, the value of the first composite signal Vad1 at the first timing T1 is a positive value corresponding to the applied external force. Further, the value of the second composite signal Vad2 at the second timing T2 is 0 (zero). Based on the combination of the values of the first and second combined signals Vad1 and Vad2, the detection circuit 17 can recognize that the pressed position on the detection target 13 is a part corresponding to the first secondary coil 15a. . The detection circuit 17 generates information regarding the pressed position with respect to the detection target 13.

<When the second point P2 is pressed>
Next, a case where a large external force is applied to a portion of the detection target 13 in the vicinity of the second secondary coil 15b as shown by the second point P2 in FIG. 8A will be described.

  In this case, the detection target 13 is close to the second secondary coil 15b against the elastic force of the compression coil spring 14 and according to the magnitude of the external force, while the detection target 13 is close to the first secondary coil 15a. It inclines so that it may space apart. Then, as shown in FIG. 8B, the amplitude of the output signal Vb of the second secondary coil 15b is higher than that in the normal state shown in FIG. Increases by the proximity. On the other hand, the output signal Va of the first secondary coil 15a has a smaller amplitude due to the separation of the detection target 13 compared to the previous normal state (in the figure, the state approximated to 0). Is shown.) The amplitudes of the output signals Vc and Vd of the third and fourth secondary coils 15c and 15d change in the same manner as in the normal state.

  The amplitude of the combined signal Vab represented by the sum of the output signals Va and Vb of the first and second secondary coils 15a and 15b changes in the same manner as the output signal Vb of the second secondary coil 15b. That is, the amplitude of the composite signal Vab at the first timing T1 increases with a negative value as compared with the previous normal state. Further, the combined signal Vcd represented by the sum of the output signals Vc and Vd of the third and fourth secondary coils 15c and 15d is 0 (zero), respectively. This is because the output signals Vc, Vd of the third and fourth secondary coils 15c, 15d are in opposite phases to each other and are cancelled. Therefore, the amplitude of the composite signal Vad represented by the sum of the output signals Va to Vd of the first to fourth secondary coils 15a to 15d changes in the same manner as the output signal Vb of the second secondary coil 15b. .

  Therefore, the value of the first composite signal Vad1 at the first timing T1 is a negative value corresponding to the applied external force. Further, the value of the second composite signal Vad2 at the second timing T2 is 0 (zero). Based on the combination of the values of the first and second combined signals Vad1 and Vad2, the detection circuit 17 can recognize that the pressed position on the detection target 13 is a part corresponding to the second secondary coil 15b. . The detection circuit 17 generates information regarding the pressed position with respect to the detection target 13.

Note that even when a portion of the detection target 13 near the third or fourth secondary coil 15c, 15d is pressed, the pressed position can be detected in the same manner as described above.
<When third point P3 is pressed>
Next, as indicated by a third point P3 in FIG. 9A, an external force is applied to a portion of the detection target 13 between the first secondary coil 15a and the fourth secondary coil 15d. The case will be described. The external force here is an intermediate force smaller than the external force applied to the first and second points P1 and P2.

  In this case, the detection target 13 is close to the first and fourth secondary coils 15a and 15d against the elastic force of the compression coil spring 14 and according to the magnitude of the external force, while the second and It inclines so that it may space apart with respect to the 3rd secondary coils 15b and 15c. Then, as shown in FIG. 9B, the amplitude of the output signal Va of the first and fourth secondary coils 15a and 15d is larger than that in the normal state shown in FIG. 6B. The detection target 13 increases by the proximity. On the other hand, the amplitudes of the output signals Vb and Vc of the second and third secondary coils 15b and 15c are reduced by the distance from the detection target 13 as compared with the previous normal state.

  The amplitude of the composite signal Vab of the first and second secondary coils 15a and 15b is smaller than the amplitude of the output signal Va of the first secondary coil 15a. It gets smaller by the minute. That is, at the first timing T1, the value of the composite signal Vab takes a positive intermediate value. In addition, the amplitude of the composite signal Vcd of the third and fourth secondary coils 15c and 15d is that of the third secondary coil 15c having an opposite phase to the amplitude of the output signal Vd of the fourth secondary coil 15d. It becomes smaller by the amplitude. That is, at the second timing T2, the value of the composite signal Vcd takes a negative intermediate value.

  The value of the first composite signal Vad1 at the first timing T1 is a positive intermediate value corresponding to the applied external force. Further, the value of the second composite signal Vad2 at the second timing T2 is a negative intermediate value corresponding to the applied external force. Based on the combination of the values of the first and second combined signals Vad1 and Vad2, the detection circuit 17 determines the pressed position on the detection target 13 between the first secondary coil 15a and the fourth secondary coil 15d. It can be recognized that it is a part corresponding to.

  In addition, in the detection target 13, between the first secondary coil 15a and the third secondary coil 15c, between the third secondary coil 15c and the second secondary coil 15b, and When any portion between the second secondary coil 15b and the fourth secondary coil 15d is pressed, the pressed position can be detected in the same manner as described above.

  Thus, at the first timing T1, the combined signal Vab of the first and second secondary coils 15a and 15b appears. Further, at the second timing T2, the combined signal Vcd of the third and fourth secondary coils 15c and 15d appears. For this reason, even if there is only one A / D converter 21, the first and second secondary coils 15a to 15d captured at the first and second timings T1 and T2 respectively. Based on the combination of the combined signals Vad1 and Vad2, the pressed position with respect to the detection target 13 can be detected.

<Effect of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) The first to fourth secondary coils 15a to 15d are connected in series, and the secondary coils are excited with a phase shift of 90 ° from each other. Further, first and second timings T1 and T2 are set as capture timings of the A / D converter 21, and the first and fourth secondary coils 15a to 15d are first and second at these two timings. The second synthesized signals Vad1 and Vad2 are captured (that is, stored in a RAM (not shown)). Here, the first timing T1 is a timing at which the amplitude of the output voltage of a specific secondary coil (here, the first secondary coil 15a) is maximized, and the second timing T2 is the first timing T1. The timing of the phase of the output voltage is shifted by 90 °.

  For this reason, the first and second secondary coils 15a-15d of the first to fourth secondary coils 15a-15d captured at the first timing T1 are excited with a phase difference of 180 °. It becomes a value corresponding to the composite signal Vab generated in 15a and 15b. The second combined signal Vad2 of the four coils fetched at the second timing T2 has a value corresponding to the combined signal Vcd generated in the remaining third and fourth secondary coils 15c and 15d. The values of the first and second composite signals Vad1 and Vad2 sampled at the first and second timings T1 and T2 change according to the position (pressing position) of the detection target 13. That is, the combination of the values of the first and second combined signals Vad1 and Vad2 sampled at the first and second timings T1 and T2 is unambiguous with respect to the position of the detection target 13.

  Therefore, the detection target is based on the combination of the values of the combined signals of the first to fourth secondary coils 15a to 15d captured by the single A / D converter 21 at the first and second timings T1 and T2. 13 positions can be detected. Here, it is also possible to separately capture the combined signals of two coil pairs, each of which is composed of two secondary coils excited with a phase difference of 180 °, by two A / D converters corresponding to each group. Assumed, unlike this case, in this example, it is only necessary to provide a single A / D converter 21, which can contribute to simplification of the circuit configuration of the pressed position detection device 11. .

(2) Further, by simplifying the circuit configuration, it is possible to contribute to a reduction in the product cost of the detection circuit 17 and consequently the pressed position detection device 11.
(3) Since any pressing position with respect to the detection target 13 can be detected, it is also possible to construct a multidirectional switch device using the pressing position detection device 11 of this example.

  (4) The excitation signal generator 23 has a clock frequency that is four times the frequency of the excitation signal. That is, the oscillator of the excitation signal generator 23 generates a clock signal having a frequency four times the frequency of the excitation signal, and the first to fourth secondary coils 15a to 15d at a timing set based on the clock signal. Excited respectively. In other words, by shifting the sampling timing of the clock signal, it is possible to easily generate excitation signals having a frequency (10 kHz) that is 1/4 of the clock frequency (40 kHz), and thus four excitation signals whose temporal phases are shifted from each other by 90 °. Is possible.

  (5) The 1st-4th secondary coils 15a-15d were provided in the surface of the board | substrate 12 which is the same installation surface. The detection target 13 is provided so as to be displaceable in such a manner that the distance to the surface of the substrate 12 is changed. Specifically, the detection target 13 is supported on the substrate 12 via four compression coil springs 14.

  For this reason, the first to fourth secondary coils 15a to 15d are formed between the detection target 13 and the surface of the substrate 12 when the detection target 13 is pressed, that is, when an external force is applied to the detection target 13 toward the substrate 12. A composite signal corresponding to a change in the distance between them is generated. And based on the combination of the value of the 1st and 2nd synthetic | combination signal Vad1, Vad2 of the 1st-4th secondary coil 15a-15d taken in by 1st and 2nd timing T1, T2, in detection object 13 The pressed position can be detected.

<Second Embodiment>
Next, a second embodiment in which the present invention is embodied in a rotational position detection device that detects a rotational position of a detection target will be described. The rotation detection circuit has the same configuration as the detection circuit of the first embodiment shown in FIG.

  As shown in FIG. 10, the rotational position detection device 31 detects the rotational position of the detection target 32 that rotates eccentrically about a specific rotational axis O. This detection target 32 is formed in a columnar shape or a disc shape by a magnetic material such as iron. And the 1st-4th secondary coil 15a-15d is provided in the outer periphery of the detection target 32 in the non-contact state. These first to fourth secondary coils 15a to 15d are provided around the rotation axis O at intervals of 90 °. That is, the 1st-4th secondary coils 15a-15d are provided along the virtual cylindrical surface centering on the rotating shaft O as those installation surfaces. Further, the center lines of the first to fourth secondary coils 15a to 15d are directed so as to cross the rotation axis O, respectively.

  When the detection target 32 rotates eccentrically, the distances between the first to fourth secondary coils 15a to 15d and the detection target 32 change according to the rotation position. The amount of magnetic flux penetrating through the first to fourth secondary coils 15a to 15d changes according to the change in the distance. As a result, the magnitude of the voltage induced in the first to fourth secondary coils 15a to 15d also changes. Although omitted in FIG. 10, the first to fourth primary coils 16 a to 16 d are provided corresponding to the first to fourth secondary coils 15 a to 15 d in this example as well.

  The detection circuit 17 applies excitation signals to the first to fourth primary coils 16a to 16d, respectively, in the same manner as in the first embodiment, and the first according to the rotational displacement of the detection target 13. Based on the voltage induced in the series circuit of the fourth secondary coils 15a to 15d, the rotational position of the detection target 32 is obtained. That is, a combination of the first and second combined signals Vad1 and Vad2 of the first to fourth secondary coils 15a to 15d taken into the A / D converter 21 at the first and second timings T1 and T2, respectively. Based on this, the rotational position of the detection target 13 is detected. Note that the amplitudes of the combined signals of the first to fourth secondary coils 15a to 15d vary according to the change in the distance between the detection target 32 and the first to fourth secondary coils 15a to 15d. Changes according to the embodiment. For this reason, the detection circuit 17 provided with the single A / D converter 21 can detect the rotation position of the detection target 32 in one rotation (360 °). This is because each time the detection target 32 makes one rotation, the waveform of the voltage induced in the first to fourth secondary coils 15a to 15d, and thus the combined signal of the first to fourth secondary coils 15a to 15d. This is because the amplitude of the same changes.

Therefore, according to the present embodiment, the following effects can be obtained.
(6) The first to fourth secondary coils 15a to 15d were provided at 90 ° intervals around the central axis of the virtual cylindrical surface which is the same installation surface. Then, the detection target 32 is in a non-contact state with the first to fourth secondary coils 15a to 15d around the rotation axis O coinciding with the central axis of the virtual cylindrical surface and changes the distance from the virtual cylindrical surface. It is provided so that it can be rotated in a manner that allows it to rotate.

  For this reason, the first to fourth secondary coils 15a to 15d are connected to the detection target 32 and the virtual cylindrical surface (first to fourth secondary coils) accompanying rotation about the rotation axis O of the detection target 13. 15a to 15d), a composite signal corresponding to the change in the distance is generated. As in the first embodiment, the first and second combined signals Vad1 and Vad2 of the first to fourth secondary coils 15a to 15d captured at the first and second timings T1 and T2. Based on the combination of the values, the rotational position of the detection target 32 can be detected.

<Third Embodiment>
Next, a third embodiment in which the present invention is embodied in a slide position detection device that detects a slide position to be detected will be described. The detection circuit of this example has the same configuration as the detection circuit of the first embodiment shown in FIG.

  As shown in FIG. 11, this example is different from the first embodiment in that the detection target 13 is slid in parallel with respect to the substrate 12. The detection target 13 is provided so as to be slidable in two directions intersecting each other at a certain distance from the first to fourth secondary coils 15 a to 15 d on the substrate 12.

  As the detection target 13 slides, the areas of the end faces of the first to fourth secondary coils 15a to 15d facing each other change. Thus, the amount of magnetic flux penetrating the first to fourth secondary coils 15a to 15d changes according to the change in the facing area between the detection target 13 and the first to fourth secondary coils 15a to 15d. As a result, the magnitude of the voltage induced in the first to fourth secondary coils 15a to 15d also changes.

  Then, the detection circuit 17 applies excitation signals to the first to fourth primary coils 16a to 16d, respectively, in the same manner as in the first embodiment, and the first according to the slide displacement of the detection target 13. Based on the voltage induced in the series circuit of the fourth secondary coils 15a to 15d, the slide position of the detection target 32 is obtained. That is, based on the combination of the first and second combined signals Vad1 and Vad2 of the first to fourth secondary coils 15a to 15d captured at the first and second timings T1 and T2, respectively, the detection target 13 is detected. Detect the slide position.

Therefore, according to the present embodiment, the slide position of the detection target 32 can be detected by the detection circuit 17 provided with the single A / D converter 21.
<Other embodiments>
The embodiment described above may be modified as follows.

-In 1st Embodiment, although the detection target was made into the rectangular plate shape, it is good also as other shapes, such as circular and an ellipse.
In the second embodiment, the distance from the first to fourth secondary coils 15a to 15d is changed by eccentrically rotating the columnar or disk-shaped detection target 32. For example, A shape such as a so-called teardrop shape or an ellipse shape may be employed as the shape of the detection target. That is, it is only necessary that the magnetic fields of the first to fourth secondary coils 15a to 15d change according to the rotation of the detection target. Even in this way, the rotation of the detection target 32 can be detected.

  In the second embodiment, the detection target 32 rotates eccentrically about the rotation axis O that is also the central axis of the virtual cylindrical surface provided along the first to fourth secondary coils 15a to 15d. However, it may be eccentrically rotated around another axis parallel to the central axis (rotation axis O) of the virtual cylindrical surface. Even if it does in this way, according to rotation of the detection object 32, the change of the magnetic field of the 1st-4th secondary coils 15a-15d will generate | occur | produce.

  In the first to third embodiments, the first to fourth secondary coils 15a to 15d are provided on the same installation surface, but may be provided on different installation surfaces. That is, the magnetic field of the first to fourth secondary coils 15a to 15d may be changed according to the displacement of the detection targets 13 and 32.

  In the first to third embodiments, the detection target 13 is a magnetic body, but may be an electric conductor. As this conductor, for example, a non-magnetic material such as copper can be used as the detection target 13. In this case, as the detection targets 13 and 32 are closer to the first to fourth secondary coils 15a to 15d, the values of the voltages induced in the first to fourth secondary coils 15a to 15d are as follows. Get smaller. Conversely, as the detection targets 13 and 32 are separated from the first to fourth secondary coils 15a to 15d, the values of the voltages induced in the first to fourth secondary coils 15a to 15d are as follows. growing.

  In the first to third embodiments, the first to fourth primary coils 16a to 16d and the first to fourth secondary coils 15a to 15d are each a core (iron core) formed of a magnetic material. You may provide in the aspect wound around.

  In the first to third embodiments, the first to fourth primary coils 16 a to 16 d and the first to fourth secondary coils 15 a to 15 d are printed on the substrate 12 with a conductor such as metal. It may be a planar antenna. In this way, the size of the position detection device can be reduced.

  In the first to third embodiments, first to fourth secondary coils 15a connected in series with each other by individually applying excitation signals to the first to fourth primary coils 16a to 16d. Each of ˜15d is excited, but may be as follows. That is, excitation signals are individually applied to the first to fourth secondary coils 15a to 15d. In this way, since the first to fourth secondary coils 15a to 15d also function as primary coils, the first to fourth primary coils 16a to 16d can be omitted.

  In the first embodiment, the present invention is embodied as a pressed position detecting device, in the second embodiment as a rotational position detecting device, and in the third embodiment as a slide position detecting device. It can also be embodied as a device. For example, the first to fourth secondary coils 15a to 15d are fixedly provided on the case, and a detection target formed in a columnar shape or a disk shape by a magnetic material can be displaced relative to the case by its own weight. Provided. When the case is inclined, the detection target is relatively displaced with respect to the case, and consequently, the first to fourth secondary coils 15a to 15d. The first to fourth secondary coils 15a to 15d generate output signals corresponding to the displacement of the detection target. The generated output signal corresponds to the inclination of the case. As described above, even when the A / D converter 21 of the detection circuit 17 is a single unit, the first to fourth secondary coils 15a to 15d are displaced relatively with respect to the first to fourth. It is possible to detect various displacements of the detection target made of a magnetic material that changes the magnetic fields of the four secondary coils 15a to 15d.

<Other technical ideas>
Next, the technical idea that can be grasped from the above embodiment will be added below.
(A) In the above position detection device, the installation surface is a cylindrical surface, the four coils are provided at intervals of 90 ° around the central axis of the cylindrical surface as the specific axis, and the detection target is A position detection device provided so as to be capable of rotational displacement in such a manner that the distance from the cylindrical surface is changed around the central axis. According to this configuration, a combined signal corresponding to the distance between the detection target and the cylindrical surface that is the coil installation surface is obtained. Based on this synthesized signal, the rotational position of the detection target can be detected.

  DESCRIPTION OF SYMBOLS 11 ... Press position detection apparatus, 12 ... Board | substrate, 13, 32 ... Detection object, 15a-15d ... 1st-4th secondary coil, 16a-16d ... 1st-4th primary coil, 21 ... A / D Converter: 22 ... Calculator, 23 ... Excitation signal generator, 31 ... Rotation position detector, T1 ... First timing, T2 ... Second timing.

Claims (5)

Four coils provided at 90 ° intervals around a specific axis and connected in series to each other so as to be capable of relative displacement with respect to a detection target made of a magnetic material or a conductor;
An excitation signal generator for energizing each of said four coils temporal phase shifted 90 ° from each other,
When it is energized through the exciting signal generator, said four composite signal which is a sum of the respective generated analog voltage to the coil, a first timing at which the voltage generated in the particular coil becomes maximum, and the second A single A / D converter that captures at a second timing in which the phase of the voltage at the timing of 1 is shifted by 90 ° in time;
A position detection device comprising: an arithmetic unit that calculates the position of the detection target based on a combination of digital values of the combined signal that are captured by the A / D converter at the first and second timings. The position detection device according to claim 1,
The excitation signal generator, a position detecting device for exciting each generates a clock signal, the clock signal the four coils at a timing that is set based on a having four times the clock frequency of the excitation frequency. The position detecting device as claimed in Claim 1 or 2,
The four coils are provided on the same installation surface,
The detection object is a position detection device provided so as to be displaceable in a manner of changing a distance to the installation surface. In the position detection device according to claim 3,
While the installation surface is a plane, the specific axis is set to be orthogonal to the plane,
The position detection device is provided so that the detection target is opposed to the four coils in a direction along the specific axis and is displaceable in a manner of changing a distance from the plane in the direction along the specific axis. In the position detection device according to any one of claims 1 to 3,
The four coils are provided along a virtual cylindrical surface centered on the specific axis,
The detection target is a position detection device provided to be rotatable around the specific axis or another axis parallel to the specific axis.

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