JP2007057501A - Angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detector being manufactured through a simple process and moreover accurately detecting a wide range of angles. <P>SOLUTION: This angle detector is a detector for detecting an operation angle of a component such as a shift lever by utilizing a plurality of (e.g. four) of magnetoresistive elements. The magnetoresistive elements are mounted on a vehicle body, etc. at disposition intervals of 45°. Differences are severally obtained between outputs of magnetoresistive elements leaving disposition intervals of 90° from each other to calculate the voltage value of the sum of the differences. Subsequently, an AC wave W1 of the voltage value of the sum is converted into a pulse signal V1 by being half-wave rectified while sine wave current passed through the group of magnetoresistive elements is also converted into a pulse signal V2 by being likewise half-wave rectified to calculate an absolute value ¾V¾ of a difference between them. The absolute value ¾V¾ is smoothed during a half cycle T/2 of the sine wave current to output it as an angle signal corresponding to the direction θ of a magnetic field. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an angle detection device that detects an angle when an operation component is operated.

  Conventionally, an angle detection device that detects an operation angle (that is, a rotation angle) of an operation component such as a shift lever using a magnetoresistive element has been widely used. In this angle detection device, for example, a magnet is attached to an operation component such as a shift lever, and a magnetoresistive element is disposed on a frame or the like that supports the operation component. When the operating component is operated, the direction of the magnetic field applied from the magnet to the magnetoresistive element as shown in FIG. 6 (hereinafter referred to as the direction of the magnetic field) as the relative position between the magnet and the magnetoresistive element changes. Therefore, the magnetoresistive element detects the direction of the magnetic field and detects the rotation angle of the operation component.

By the way, the resistance characteristic (output characteristic) of the magnetoresistive element is such that the resistance value of the magnetoresistive element is R (θ), the output reference of the magnetoresistive element (the amplitude center of the output waveform) is R ₀ , and the magnetoresistive element receives from the magnet. When the magnetic field direction is θ and the maximum resistance of the magnetoresistive element is ΔR, the following equation (1) is given.
R (θ) = R ₀ + ΔR · cos ² θ (1)

Therefore, as shown in FIG. 7, the resistance characteristic of the magnetoresistive element is as follows. When the horizontal axis is the magnetic field direction θ and the vertical axis is the variable value (R (θ) −R ₀ ) / ΔR, the magnetic field direction θ is −90 degrees. When the angle is +90 degrees, the variable value takes the minimum value “0”, and when the magnetic field direction θ is 0 degrees, the sinusoidal characteristic waveform S ₀ where the variable value takes the maximum value “1” is satisfied. As can be seen from the figure, when the rotation angle is detected by using one magnetoresistive element, the characteristic waveform S ₀ has a symmetrical waveform centering on the magnetic field direction θ of 0 degree. The detectable angle detection range is limited to a range of 0 degrees to 90 degrees.

Further, in the curvilinear portion of the characteristic waveform S ₀ (that is, the magnetic field direction θ is around −90 degrees, 0 degrees, and +90 degrees), the same value is always obtained every time the angle is detected due to the performance of the magnetoresistive element. There is no guarantee of output. Therefore, if the rotation angle is detected using the curvilinear portion of the characteristic waveform S ₀ , there arises a problem that the detection accuracy is deteriorated in the curvilinear portion. Therefore, it is conceivable to perform the rotation angle detected by using only linear portion of the characteristic waveform S _0, the use of this angle detection range is further reduced, it is not suitable for practical use.

  Therefore, for example, Non-Patent Document 1 discloses a technique for accurately detecting a rotation angle over a wide range. In this technique, as shown in FIG. 8, two Hall elements 51 and 52 are arranged in an orthogonal direction, one Hall element 51 has a cosine wave current I · cosωt, and the other Hall element 52 has a sine wave current. Run I and sinωt respectively. When a magnetic field H is applied to these Hall elements 51 and 52, assuming that K is a Hall coefficient and B is a magnetic flux density, the Hall elements 51 and 52 have Hall voltages kIB · cosωt · sinθ, kIB corresponding to the strength of the magnetic field H.・ Sinωt and cosθ are output.

By the way, when the Hall voltage kIB · cosωt · sinθ and the Hall voltage kIB · sinωt · cosθ are added to obtain a voltage signal, the voltage signal becomes kIB · cos (ωt−θ). This voltage signal kIB · cos (ωt−θ) has a waveform that is out of phase with the sine wave current I · sinωt (cosine wave current I · cosωt) as much as the magnetic field direction θ, as can be seen from the equation. Take. Therefore, in the technique of Non-Patent Document 1, the voltage signal kIB · cos (ωt−θ) is obtained, and the phase difference is calculated to detect the magnetic field direction θ.
G. Steinbaugh, “Hall compass points digitally to headings”, Electronics, USA, 1980, Vol. 53, No. 27, p. 112-114

  By the way, in this technique, since the Hall elements 51 and 52 must be arranged orthogonally, for example, a manufacturing method of simultaneous manufacturing on the same substrate using sputtering or the like cannot be adopted, and the Hall elements 51 and 52 are sequentially formed. A manufacturing method that goes through a process of manufacturing a substrate must be used. For this reason, it is difficult to arrange the Hall elements 51 and 52 in an accurate orthogonal state, and there is a problem that variations between the Hall elements 51 and 52 occur and sufficient angle detection accuracy cannot be obtained. In addition, if the Hall elements 51 and 52 are manufactured with high manufacturing accuracy, it is possible to ensure the accuracy of the orthogonal arrangement of the Hall elements 51 and 52, but this is adopted from the viewpoint of manufacturing efficiency and manufacturing cost. Is currently difficult.

  An object of the present invention is to provide an angle detection device that can be manufactured through a simple process and that can accurately detect a wide range of angles.

  According to the present invention, in the angle detection device that detects the angle formed by the operation component with respect to the support component that supports the operation component so as to be relatively movable when the operation component is operated, the operation to generate a magnetic field is performed. A plurality of magnetic field generating means provided on one of the component and the support component, and a plurality of mounting states provided on the other of the operation component and the support component and arranged at a predetermined angular interval to detect the magnetic field. A current generating circuit for supplying alternating currents having different phases to each set comprising a magnetoresistive element and a magnetoresistive element having an arrangement interval of a constant multiple of the constant angle; and the magnetoresistor in the same set in each set A differential circuit that takes an output difference between elements, an adder circuit that calculates a sum of differences output from the differential circuit in pairs, an AC wave of the differential sum, and an AC wave of the AC current The phase difference between And a smoothing circuit that obtains a voltage value after smoothing as a value corresponding to the angle by smoothing the phase difference in half-cycle units. To do.

  According to this configuration, when the operation component is operated, the operation component relatively moves with respect to the support component. Therefore, the direction of the magnetic field applied from the magnetic field generating unit to the magnetoresistive element changes according to the relative movement position. . By the way, the magnetoresistive elements of the present invention are arranged at an arrangement interval of a constant angle, and an alternating current having a different phase is generated in each of the magnetoresistive elements at an arrangement interval of a constant multiple of a constant angle. Shed by the circuit. Therefore, the magnetoresistive element has output characteristics based on the arrangement direction determined from the arrangement state and the waveform of the alternating current flowing through the magnetoresistive element.

  The differential circuit takes a difference between the outputs of the magnetoresistive elements in the group in which the currents flowing from the current generation circuit are in phase, and outputs each output signal corresponding to the difference to the adder circuit. When the difference circuit receives the difference from the difference circuit, the adder circuit calculates the sum of these differences and outputs an output signal corresponding to the difference sum to the phase difference detection circuit. The phase difference detection circuit detects a phase difference between the AC wave of the sum of the differences and the AC current that flows through the magnetoresistive element, and outputs an output signal corresponding to the phase difference to the smoothing circuit.

  By the way, the AC wave obtained from the sum of the differences is output with the phase changed with respect to the waveform of the AC current flowing through each magnetoresistive element. This phase difference (phase change amount) is smoothed in a half cycle. The converted value is a value corresponding to the direction of the magnetic field applied to the magnetoresistive element. Therefore, since the magnetic field direction can be understood by looking at the value obtained by smoothing the phase difference between the alternating current wave of the sum of the differences and the alternating current wave of the alternating current, a value obtained by smoothing this phase difference by the smoothing circuit is calculated, Based on this smoothed value, the direction of the magnetic field applied to the magnetoresistive element, that is, the operation angle of the operation component is calculated.

  Therefore, according to the configuration of the present invention, the phase difference calculated by the phase difference detection circuit can be output as a value capable of detecting the direction of the magnetic field in a range of 90 degrees or more. For example, only one magnetoresistive element is used. Therefore, it is possible to accurately detect a wide range of angles of 90 degrees or more compared to the case where angle detection is performed. Further, in the configuration of the present invention, the arrangement of the magnetoresistive elements is not changed, but the arrangement angle interval of the magnetoresistive elements is changed, so that the magnetoresistive elements can be simultaneously manufactured on the substrate by sputtering or the like. Is possible. Therefore, it is possible to manufacture a magnetoresistive element having high placement accuracy without going through a troublesome manufacturing process.

  According to the present invention, the phase difference detection circuit generates a first pulse signal by half-wave rectifying the alternating current wave of the difference, and secondly rectifies the alternating current wave of the alternating current. A signal is generated, a voltage difference between the first pulse signal and the second pulse signal is obtained as the phase difference, and the smoothing circuit smoothes the voltage difference in a half cycle unit, and the smoothed voltage value is The gist is to obtain the value corresponding to the angle.

  According to this configuration, a simple method of taking the voltage value between the voltage value of the first pulse signal based on the sum of the differences and the voltage value of the second pulse signal based on the alternating current and smoothing it. Thus, the operation angle of the operation component can be calculated.

  According to the present invention, the phase difference detection circuit generates a first pulse signal by half-wave rectifying the alternating current wave of the difference, and secondly rectifies the alternating current wave of the alternating current. A signal is generated, a time difference between the edge of the first pulse signal and the edge of the second pulse signal is obtained as the phase difference, and the smoothing circuit smoothes the time difference in half-cycle units, The gist is to obtain the averaged time as a value corresponding to the angle.

  According to this configuration, the operation angle is calculated based on the time difference between the edges of the first pulse signal and the second pulse signal, rather than performing the angle detection by looking at the voltage values of the first pulse signal and the second pulse signal. Is done. Therefore, even if the voltage value of the first pulse signal or the second pulse signal fluctuates due to an external factor such as a temperature change, these voltage values are not used as parameters for angle calculation. Therefore, if the configuration of the present invention is adopted, it is effective to ensure angle detection accuracy.

  According to the present invention, it can be manufactured through a simple process, and a wide range of angles can be detected with high accuracy.

Hereinafter, an embodiment of an angle detection device embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a shift lever 2 that is operated when a gear of an automatic transmission is switched is disposed in a vehicle (commonly referred to as an automatic vehicle) 1 in which gear shifting is performed by an automatic transmission. The shift lever 2 is supported by the vehicle body 3 so as to be rotatable about its base end as a fulcrum. The shift lever 2, the angle detection device 4 for detecting an operation angle of the shift lever 2 R _theta is disposed. The angle detection device 4 detects the operation position when the shift lever 2 is shifted to each position such as the P position, the R position, the N position, the D position, the second position, and the L position. The shift lever 2 corresponds to an operation part, and the vehicle body 3 corresponds to a support part.

  As shown in FIG. 2, a substrate 5 of the angle detection device 4 is attached to the vehicle body 3 in the vicinity of the shift lever 2, and a plurality of magnetoresistive elements 6 are mounted on the substrate 5. The magnetoresistive element 6 of this example is made of, for example, a NiCo (nickel cobalt) ferromagnetic material, and four are used in this example. These magnetoresistive elements 6a to 6d are attached to the vehicle body 3 in a state where the arrangement interval between adjacent elements is 45 degrees, and each is applied in the direction of the applied magnetic field H (hereinafter referred to as the magnetic field direction θ). The corresponding element voltages (output signals) Va to Vd (see FIG. 3) are output.

On the other hand, as shown in FIG. 2, a magnet 7 is attached to the shift lever 2 at a position facing the magnetoresistive elements 6 a to 6 d. The magnet 7 is made of a commonly used material such as a ferrite magnet, and is arranged at a position where the direction of the magnetic field applied to the magnetoresistive elements 6a to 6d sequentially changes when the shift lever 2 is operated. Yes. When the shift lever 2 is operated, the direction of the magnetic field H around the magnetoresistive elements 6a to 6d changes as the magnet 7 moves, so that the magnetoresistive elements 6a to 6d detect the magnetic field direction θ. by the operation angle of the shift lever 2 R _theta it is detected. The magnet 7 corresponds to a magnetic field generating unit.

As shown in FIG. 3, the magnetoresistive elements 6a and 6c, which form a set having an arrangement interval of 90 degrees from each other, are connected in series from the power source side in the order of 6c and 6a. The magnetoresistive element group is connected to a first constant current circuit 8 for flowing a cosine wave current I ₀ · cosωt to the element group when the angle detection device 4 is operated. Further, another magnetoresistive element 6b, 6d, which is a set having an arrangement interval of 90 degrees, is connected in series in the order of 6d, 6b from the power source side. The magnetoresistive element group is connected to a second constant current circuit 9 for flowing a sine wave current I ₀ · sinωt to the element group when the angle detection device 4 is operated. I ₀ is the maximum current flowing through the magnetoresistive element group. The first constant current circuit 8 and the second constant current circuit 9 correspond to a current generation circuit, and the cosine wave current I ₀ · cosωt and the sine wave current I ₀ · sinωt correspond to an alternating current.

  Each of the magnetoresistive elements 6a to 6d is connected to a differential amplifier circuit 10 to 13 for detecting a voltage generated in the magnetoresistive elements 6a to 6d. These differential amplifier circuits 10 to 13 are composed of, for example, an operational amplifier or a resistor, and a high input impedance differential amplifier circuit or the like is used. In the differential amplifier circuits 10 to 13, of the magnetoresistive elements 6 a to 6 d, one input terminal is connected to the input terminal of the magnetoresistive element, and the other input terminal is connected to the output terminal of the magnetoresistive element. The device voltages (voltage signals) Va to Vd that are respectively connected and generated in the magnetoresistive elements are output.

The differential amplifier circuits 10 and 12 are connected to a differential amplifier circuit 14 that detects a difference between outputs of the differential amplifier circuits 10 and 12. The differential amplifier circuit 14 is also composed of an operational amplifier, a resistor, and the like, and a high input impedance differential amplifier circuit or the like is used. The differential amplifier circuit 14 has one input terminal connected to the output terminal of the lower differential amplifier circuit 10 and the other input terminal connected to the output terminal of the lower differential amplifier circuit 12. The difference between the element voltage Va input from the element and the element voltage Vc input from the differential amplifier circuit 12 is taken, and a difference voltage V ₁₃ corresponding to the difference is output.

The differential amplifier circuits 11 and 13 are connected to a differential amplifier circuit 15 that detects a difference between outputs of the differential amplifier circuits 11 and 13. The differential amplifier circuit 15 is also composed of an operational amplifier, a resistor, and the like, and a high input impedance differential amplifier circuit or the like is used. The differential amplifier circuit 15 has one input terminal connected to the output terminal of the lower differential amplifier circuit 11 and the other input terminal connected to the output terminal of the lower differential amplifier circuit 13. The difference between the voltage signal Vb input from the signal Vb and the voltage signal Vd input from the differential amplifier circuit 13 is taken, and a difference voltage V ₂₄ corresponding to the difference is output. The differential amplifier circuits 10 to 15 correspond to differential circuits.

An adder circuit 16 for detecting the sum of the outputs of the differential amplifier circuits 14 and 15 is connected to the differential amplifier circuits 14 and 15. The adder circuit 16 has one input terminal connected to the output terminal of the lower differential amplifier circuit 14 and the other input terminal connected to the output terminal of the lower differential amplifier circuit 15. taking the sum of the differential voltage V ₁₃ and the differential voltage ₂₄ input from the differential amplifier circuit 15 which outputs the addition voltage Vout corresponding to the sum.

Here, the addition voltage Vout is calculated as a value satisfying the equation (8) obtained from the following equations (2) to (7). First, the four magnetoresistive elements 6a to 6d in this example are arranged so that the interval between adjacent elements is 45 degrees. Therefore, the resistance values (characteristic values) R _{1 to} R ₄ of the magnetoresistive elements 6 a to 6 d are R ₀ and the magnetoresistive elements 6 a to 6 are the output reference (the amplitude center of the output waveform) of the magnetoresistive elements 6 a to 6 d. When the maximum resistance of 6d (maximum change value of resistance) is ΔR and the direction of the magnetic field applied to the magnetoresistive elements 6a to 6d is θ, values satisfying the following expressions (2) to (5) are obtained.
R ₁ = R ₀ + ΔR · cos ² (θ−45) (2)
R ₂ = R ₀ + ΔR · cos ² (θ) (3)
R ₃ = R ₀ + ΔR · cos ² (θ + 45) (4)
R ₄ = R ₀ + ΔR · cos ² (θ + 90) (5)

As shown in FIG. 4, the characteristic waveforms S _{1 to} S ₄ of the resistance values R _{1 to} R ₄ have an alternating waveform with an amplitude of “1”, and the arrangement interval of the magnetoresistive elements 6a to 6d forms 45 degrees. Therefore, in the waveform between adjacent magnetoresistive elements, the phase is displaced by 45 degrees. That is, phase shifted -45 degrees relative to the characteristic waveform _{S 1} characteristic waveform _{S 2} of the magnetoresistive element 6b magnetoresistive element 6a, characteristic waveform _{S 3} of the magnetoresistive element 6c magnetoresistive element 6b characteristic waveform _{S 2} phase shifted -45 degrees relative to the characteristic waveform _{S 4} of the magnetoresistive element 6d phase is shifted -45 degrees relative characteristic waveform _{S 3} of the magnetoresistive element 6c.

  However, in this example, the resistance characteristics of the magnetoresistive elements 6a to 6d are all the same. Here, as an example of manufacturing the magnetoresistive elements 6a to 6d having uniform resistance characteristics, for example, a manufacturing method in which four materials of the magnetoresistive elements 6a to 6d are simultaneously attached to the substrate 5 by sputtering or the like is employed. Further, when this manufacturing method is used, not only the resistance characteristics of the magnetoresistive elements 6a to 6d are uniform, but also the patterns of the magnetoresistive elements 6a to 6d become extremely small, and the size of the angle detection device 4 is reduced. Is also effective.

Subsequently, a difference R ₁₃ (= R ₁ −R ₃ ) between the resistance values R ₁ and R ₃ is obtained in the magnetoresistive elements 6a and 6c which are a set having a 90 ° interval, and the 90 ° interval is also obtained. set a is magnetoresistive element 6b, in 6d, obtains a difference R ₂₄ of the resistance value _R 2, _{R 4} a ₍₌ R 2 -R ₄₎ in a similar manner. These differences R ₁₃ and R ₂₄ take values that satisfy the following expressions (6) and (7).
R ₁₃ = R ₁ −R ₃ = ΔR · sin 2θ (6)
R ₂₄ = R ₂ −R ₄ = ΔR · cos 2θ (7)

As shown in FIG. 4, the characteristic waveforms S ₁₃ and S ₂₄ of the differences R ₁₃ and R ₂₄ are AC waveforms having amplitude ranges of “−1” to “+1”, and their phases are shifted by 45 degrees from each other. It becomes a waveform. That is, characteristics waveform S ₁₃ of the differential R ₁₃ takes the sine wave characteristic waveform S ₂₄ of the differential R ₂₄ is taking the cosine wave.

Here, the magnetoresistive element 6a, the cosine wave current I ₀ · cos .omega.t flows to 6c, the magnetoresistive element 6b, since the sinusoidal current I ₀ · sin .omega.t are flowed to 6d, the differential voltage V ₁₃ is R The value of ₁₃ I ₀ · cosωt is taken, and the differential voltage V ₂₄ takes the value of R ₂₄ I ₀ · sinωt. Thus, addition voltage Vout is the sum of the differential voltage V ₁₃ and the differential voltage V ₂₄ takes a value that satisfies the following equation (8).

従って、式(8) からも分かるように、加算電圧Ｖout の電圧波形は、正弦波電流I₀・sinωt の電流波形に対して位相が２θずれた状態となる。即ち、図５（ａ）に示すように、加算電圧Ｖout の交流波Ｗ_１は、正弦波電流I₀・sinωt の交流波Ｗ_２に対して位相が２θずれた波形をとる。

Therefore, as can be seen from the equation (8), the voltage waveform of the added voltage Vout is in a state where the phase is shifted by 2θ with respect to the current waveform of the sine wave current I ₀ · sinωt. That is, as shown in FIG. 5A, the AC wave W ₁ of the added voltage Vout takes a waveform whose phase is shifted by 2θ with respect to the AC wave W ₂ of the sine wave current I ₀ · sinωt.

As shown in FIG. 3, the second constant current circuit 9 and the adding circuit 16, an angle signal D _theta based on the AC wave W ₂ of the AC wave W ₁ and sinusoidal current I ₀ · sin .omega.t the addition voltage Vout An angle signal generation circuit 17 to be generated is connected. The angle signal generation circuit 17 performs a half-wave rectification on each of the AC waves W ₁ and W ₂ of the addition voltage Vout and the sine wave current I ₀ · sinωt, so that a pulse that outputs an H level signal when the voltage value is 0 or more. The signals are converted into signals V ₁ and V ₂ (see FIGS. 5B and 5C), respectively.

After the pulse signal conversion, the angle signal generation circuit 17 calculates the absolute value | V | (= | V ₁ −V ₂ |: refer to FIG. 5D) of the difference between the pulse signals V ₁ and V ₂ as a phase difference. . Then, the angle signal generation circuit 17 smoothes (averages) the absolute value | V | with the half cycle T / 2 of the AC wave W ₂ of the sine wave current I ₀ · sinωt (AC wave W ₁ of the added voltage Vout). ), and it outputs a voltage value Vr after the smoothing as the angle signal D _theta.

By the way, since the smoothed voltage value Vr takes a value corresponding to the magnetic field direction θ, the magnetic field direction θ applied to the magnetoresistive element group, that is, the operation angle R _{θ of the} shift lever 2 can be seen from the voltage value Vr. Can be detected. Therefore, the operation angle R _θ of the shift lever 2 can be detected by looking at the angle signal D _θ output from the angle signal generation circuit 17. In this example, since the phase difference is calculated as “2θ”, one cycle of the AC wave is 360 degrees, and therefore the angle detection range is 0 degrees to 180 degrees due to the relationship of “2θ = 360 degrees”. Become. The angle signal generation circuit 17 constitutes a phase difference detection circuit and a smoothing circuit.

Next, the operation of the angle detection device 4 of this example will be described.
For example, when the engine is applied to a parked vehicle and the brake pedal is depressed, the shift lever 2 at the P position can be operated. At this time, if the shift lever 2 is operated, for example, from the P position to the D position, the magnetic field direction θ applied to the magnetoresistive element group changes in a direction corresponding to the D position of the shift lever 2 with this lever operation. .

In this case, the device voltage Va output from the differential amplifier circuit 10 includes a resistance R ₁ of the magnetoresistance element 6a which is determined by the magnetic field direction θ at that time, based on the cosine wave current I ₀ · cos .omega.t flowing through the magneto-resistive element 6a Takes a value. Similarly, the element voltages Vb to Vd output from the differential amplifier circuits 11 to 13 are also AC waves flowing through the resistance values R _{2 to} R ₄ determined by the magnetic field direction θ and the magnetoresistive elements 6 b to 6 c, respectively. It takes a value based on the current (the magnetoresistive element 6c is a cosine wave current I ₀ · cosωt, and the magnetoresistive elements 6b and 6d are sine wave currents I ₀ · sinωt).

The element voltages Va and Vc of the differential amplifier circuits 10 and 12 are input to the differential amplifier circuit 14, and a differential voltage V ₁₃ between these element voltages Va and Vc is calculated by the differential amplifier circuit 14. The element voltages Vb and Vd of the differential amplifier circuits 11 and 13 are input to the differential amplifier circuit 15, and a differential voltage V ₂₄ between these element voltages Vb and Vd is calculated by the differential amplifier circuit 15. The differential voltages V ₁₃ and V ₂₄ of the differential amplifier circuits 14 and 15 are input to the adder circuit 16, and an adder voltage Vout obtained by adding the differential voltages V ₁₃ and V ₂₄ is calculated by the adder circuit 16.

The addition voltage Vout of the addition circuit 16 and the sine wave current I ₀ · sinωt of the second constant current circuit 9 are input to the angle signal generation circuit 17, and the angle signal generation circuit 17 causes the AC wave W of the addition voltage Vout to be added. ₁ is converted into a half-wave pulse signal V ₁ , and an AC wave W ₂ of a sine wave current I ₀ · sinωt is converted into a half-wave pulse signal V ₂ . Then, the absolute value | V | of the difference between these pulse signals V ₁ and V ₂ is calculated by the angle signal generation circuit 17.

This absolute value | V | is smoothed by the angle signal generation circuit 17 in a half cycle T / 2 of the sine wave current I ₀ · sinωt, and the smoothed voltage value is a voltage value Vr corresponding to the magnetic field direction θ. Calculated. Here, since the voltage at the phase difference 2θ is the absolute value | V |, if the voltage value at the half cycle T / 2 is obtained using this relationship, it is calculated as the smoothed voltage value Vr. Is done. The voltage value Vr is output from the angle signal generation circuit 17 as an angle signal _Sθ . Therefore, the operation angle _Rθ can be calculated by looking at the angle signal _Sθ output from the angle signal generation circuit 17.

Therefore, in this example, the magnetic field direction θ (the operating angle R _θ of the shift lever 2) is uniquely calculated by looking at the potential difference | V | whose value changes proportionally according to the magnetic field direction θ. Therefore, by performing angle detection using the calculation method of this embodiment, section (the example of the phase difference between the AC wave W ₁ and sinusoidal current I ₀ · sin .omega.t AC wave W ₂ of the addition voltage Vout is 2θ However, it is possible to accurately detect a wide range of angles (in this example, 0 degrees to 180 degrees) as compared with, for example, the case of using one magnetoresistive element.

  In this example, since the magnetoresistive elements 6a to 6d are used as the magnetic detection elements instead of the Hall elements, the magnetoresistive elements 6a to 6d are manufactured using a manufacturing method in which a magnetic material is attached to the substrate by sputtering or the like. Since it is possible, the magnetoresistive elements 6a to 6d can be manufactured simultaneously. Accordingly, when the magnetoresistive elements 6a to 6d are simultaneously manufactured, it is difficult for the resistance characteristics to be shifted, so that the resistance characteristics of the magnetoresistive elements can be substantially uniform without a troublesome manufacturing process. It becomes possible to ensure detection accuracy.

According to the angle detection device 4 of the present embodiment, the following effects can be obtained.
(1) Since the magnetic field direction θ is calculated by observing the potential difference | V | whose value changes proportionally according to the magnetic field direction θ, a wide range of angles of 90 ° or more can be detected with high accuracy. Moreover, since this example uses the magnetoresistive elements 6a to 6d, it is possible to use a manufacturing method in which the magnetoresistive elements 6a to 6d are simultaneously manufactured on the substrate by sputtering or the like. Therefore, the resistance characteristics of the magnetoresistive elements 6a to 6d are almost uniform, and this also ensures high angle detection accuracy.

(2) The absolute value | V | of the difference between the pulse signal V ₁ based on the addition voltage Vout which is the sum of the differential voltages V ₁₃ and V ₂₄ and the pulse signal V ₂ based on the sine wave current I ₀ · sinωt The magnetic field direction θ can be calculated by a simple method of smoothing it.

In addition, this embodiment is not limited to the said structure, You may change into the following aspects.
The processing performed after obtaining the pulse signals V ₁ and V ₂ for angle detection is not limited to the processing for smoothing the absolute value | V | of the difference between the pulse signals V ₁ and V ₂ . For example, the time t between the falling edge of the pulse signal V _{1 and} the falling edge of the pulse signal V ₂ is counted, and this time t is calculated by a half cycle T / 2 of the sine wave current I ₀ · sinωt. The angle may be detected by using the time tave after smoothing. Since this time tave is also output as a value corresponding to the magnetic field direction θ, the magnetic field direction θ can be detected by looking at this time tave. If the angle is detected using the time t, even if the voltage values of the pulse signals V ₁ and V ₂ fluctuate due to an external factor such as a temperature change, these voltage values are used as parameters for angle calculation. Therefore, this external factor does not affect the angle calculation, which is highly effective in ensuring the angle detection accuracy.

  The number of the magnetoresistive elements 6 is not limited to four as in the present example, and a configuration using, for example, six or eight may be used. Also in this case, these magnetoresistive elements 6,... Are attached at an arrangement interval of 45 degrees, the difference between the elements forming the arrangement interval of 90 degrees is taken, and the linearity portion is cut out from the characteristic waveform of the difference to obtain a linear equation. Take the calculation method.

The attachment location of the magnetoresistive element 6 and the magnet 7 is not limited to the magnetoresistive element 6 being on the vehicle body 3 side and the magnet 7 being on the shift lever 2 side, and this combination may be reversed.
The magnetic field generation means is not limited to the magnet 7 as long as it can generate a magnetic field.

  The angle detection device 4 of this example is not limited to the shift lever 2 but may be a seat inclination detection device that detects the amount of inclination of the seat back, for example, and the installation target of the angle detection device 4 is particularly limited. Not.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) In an angle detection device that detects an angle formed by the operation component with respect to a support component that supports the operation component so as to be relatively movable when the operation component is operated, the operation component and the A magnetism generating means provided on one of the support parts, and a plurality of magnetic field resistance elements provided on the other of the operation part and the support part and attached at an arrangement interval of 45 degrees to detect the magnetic field, and 90 A set of magnetoresistive elements having an arrangement interval of degrees, a first current generating circuit for passing a first alternating current, and a set of magnetoresistive elements having an arrangement interval of 90 degrees apart from the set A second current generating circuit for passing a second alternating current whose phase is 45 degrees different from that of the first alternating current, a differential circuit for taking a difference in output between the magnetoresistive elements in the same set, and the difference Output from the dynamic circuit in pairs. An addition circuit for calculating a sum of differences; a phase difference detection circuit for detecting a phase difference between the alternating current wave of the difference and one of the first alternating current and the second alternating current; An angle detection apparatus comprising: a smoothing circuit that smoothes the phase difference in units of half cycles to obtain a voltage value after the smoothing as a value corresponding to the angle.

  (2) In the technical idea (1), the first current generation circuit passes the first alternating current as a cosine wave signal, and the second current generation circuit passes the second alternating current to a sine wave. The phase difference detection circuit calculates a difference between the sum AC wave of the difference and the sine wave output from the second current generation circuit as the phase difference. In this case, since the AC wave of the sum of differences is calculated as a sine wave equation, the phase difference can be calculated using the sine wave equation, and the calculation of the phase difference can be simplified.

The perspective view which shows the vehicle interior in one Embodiment. The top view which shows the attachment state of the magnetoresistive element and magnet which comprise an angle detection apparatus. The block diagram which shows the electric constitution of an angle detection apparatus. The wave form diagram which shows the characteristic waveform of a magnetoresistive element. (A) is a waveform diagram showing an AC wave of an addition voltage and a sine wave current, (b) is a waveform diagram showing a pulse signal of the addition voltage, (c) is a waveform diagram showing a pulse signal of a sine wave current, (d). Is a waveform diagram showing the absolute value of the difference between pulse signals. The top view which shows the state in which the magnetic field of the predetermined direction was applied to the conventional magnetoresistive element. The wave form diagram which shows the characteristic waveform of a magnetoresistive element. Explanatory drawing which shows the principle of the angle detection apparatus using a Hall element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Shift lever as operation component, 3 ... Vehicle body as support component, 4 ... Angle detection device, 6 (6a-6d) ... Magnetoresistive element, 7 ... Magnet as magnetic field generation means, 8, 9 ... Current generation circuit Constant current circuit as 10-15 ... differential amplifier circuit as differential circuit, 16 ... adder circuit, 17 ... angle signal generation circuit constituting phase difference detection circuit and smoothing circuit, H ... magnetic field, I _0. cosωt: cosine wave current constituting AC current, I ₀ · sinωt: sine wave current constituting AC current, W ₁ , W ₂ : AC wave, 2θ: phase difference, T / 2: half cycle, Vr: voltage value , Differences R ₁₃ , R ₂₄ .

Claims (3)

In an angle detection device that detects an angle formed by the operation component with respect to a support component that supports the operation component so as to be relatively movable when the operation component is operated,
Magnetic field generating means provided on one of the operating component and the support component to generate a magnetic field;
A plurality of magnetoresistive elements that are provided on the other of the operation component and the support component and have a mounting state at a certain angle from each other to detect the magnetic field;
A current generation circuit for supplying alternating currents having different phases to each set of magnetoresistive elements having an arrangement interval of a constant multiple of the constant angle;
A differential circuit that takes a difference in output between the magnetoresistive elements in the same set in each set;
An adder circuit for calculating a sum of differences output from the differential circuit in units of sets;
A phase difference detection circuit for detecting a phase difference between the AC wave of the differential sum and the AC wave of the AC current;
An angle detection apparatus comprising: a smoothing circuit that obtains a voltage value after smoothing as a value corresponding to the angle by smoothing the phase difference in half-cycle units.   The phase difference detection circuit generates a first pulse signal by half-wave rectifying the AC wave of the sum of the differences, and generates a second pulse signal by similarly half-wave rectifying the AC wave of the AC current, The voltage difference between the first pulse signal and the second pulse signal is obtained as the phase difference, and the smoothing circuit smoothes the voltage difference in half-cycle units, and sets the smoothed voltage value as a value corresponding to the angle. The angle detection device according to claim 1, wherein the angle detection device is obtained.   The phase difference detection circuit generates a first pulse signal by half-wave rectifying the AC wave of the sum of the differences, and generates a second pulse signal by similarly half-wave rectifying the AC wave of the AC current, The time difference between the edge of the first pulse signal and the edge of the second pulse signal is obtained as the phase difference, and the smoothing circuit smoothes the time difference in half-cycle units, and calculates the smoothed average time as the time difference. The angle detection device according to claim 1, wherein the angle detection device is obtained as a value corresponding to the angle.

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