JP2006047228A - Rotation angle detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle-of-rotation sensitive device for securing precision of an angle-of-rotation calculation, even if sensitive sensitivity of a sensitive element is lowered and simplifying the angle-of-rotation calculations. <P>SOLUTION: When a vehicle is started with engine, the angle-of-rotation sensing device 1 is started, and a calculation circuit 12 inputs a sine value Y1 and a cosine value Y2 through an A/D converter 10 from magnetic sensors 6 and 7. The calculation circuit 12 calculates arctangent function, to calculate the arctangent value Vh and calculates the angle of rotation θ of a magnet 3 from the arctangent value Vh. In addition, the magnetic sensors 6 and 7 are used under the same bias conditions, namely, with the same impression voltage. Thus, since the amplitude A1 of a sine signal Sa output from the magnetic sensor 6 and an amplitude A2 of a cosine signal Sb output from the magnetic sensor 7 are the same value, the amplitude A1 of the sine value Y1 and the amplitude A2 of the cosine value Y2 are canceled, when the arctangent value Vh is calculated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle detection device that calculates a relative rotation angle between a detection object and a detection element.

  Conventionally, as this type of rotation angle detection device, for example, a device disclosed in Patent Document 1 using a magnetic detection element has been disclosed. The rotation angle detection device shown in the document 1 has a configuration in which a magnet is fixed to a rotation shaft such as a throttle valve and a Hall IC is disposed at a position where the magnet can be detected. The Hall IC consists of a Hall element and other devices. When the magnet rotates due to the rotation of the throttle valve, the magnetic flux angle to the magnetic sensing surface of the Hall element changes. Based on this change in the magnetic flux angle, the throttle valve Is calculated.

  Here, the Hall element outputs a sine wave detection signal (voltage value), but if the detection signal changes linearly (linearly), the rotation angle can be calculated with a simple calculation process, so the detection signal changes linearly. In this range, the rotation angle can be calculated accurately in a short time. However, since the linear change range of the detection signal is narrow when the detection signal is a sine wave, there is a problem that the calculation accuracy of the rotation angle is lowered if the detection range of the rotation angle is forcibly widened. Further, if the rotation angle is calculated by strictly calculating the curved portion of the detection signal, a complicated calculation process is required, resulting in a problem that the calculation processing speed becomes slow.

Therefore, in the literature 1, when the sine signal Sxa shown in FIG. 8 is output as a detection signal from the Hall element, the sine signal Sxa is converted into a signal Sxb of an inverse sine function (arcsin), thereby obtaining a sine signal. The rotation angle is calculated by converting Sxa into a linear signal. In this way, the rotation angle can be calculated with a linear signal, and the rotation angle can be obtained with high accuracy by simple arithmetic processing.
JP 2001-124511 (page 3-5, FIG. 1)

  By the way, there are cases where the temperature of the rotation angle detection device rises due to long-time use or severe use environment. Since the Hall element has a characteristic that the output changes due to the influence of the temperature, the detection sensitivity of the Hall element decreases when the temperature of the device rises, and the detection signal of the Hall IC is displayed as shown by the two-dot difference line in FIG. The inverse sine signal Sxb also shifts as shown by the two-dot line in FIG. If this happens, a deviation occurs in the correlation between the inverse sine value (inverse cosine value) and the rotation angle, causing a problem that an accurate rotation angle cannot be calculated.

  Further, when a cosine signal is output as a detection signal from the hall element, the cosine signal can be similarly converted into an inverse cosine signal (arccos) signal, and the rotation angle can be calculated with a linear signal. As with Sxa, the output changes due to the influence of temperature, and the inverse cosine signal also fluctuates. Further, even if the calculation accuracy of the rotation angle is ensured, there is a demand for a rotation angle calculation program that can satisfy the calculation angle from the viewpoint of the calculation speed and the memory amount, and to simplify the rotation angle calculation and reduce the calculation program amount as much as possible. .

  On the other hand, as another idea, for example, a temperature sensor is used to detect the temperature in the environment of use, and a rotation angle is calculated by correcting an inverse sine signal (inverse cosine signal) based on the temperature value. . However, when this method is used, a temperature sensor is separately required. Therefore, from the viewpoint of increasing the cost and size of the apparatus, there is a current situation in which this method cannot be adopted, and another method that does not use the temperature sensor has been desired.

  An object of the present invention is to provide a rotation angle detection device that can ensure the accuracy of rotation angle calculation even if the detection sensitivity of a detection element is reduced, and that can simplify the rotation angle calculation.

  In order to solve the above-described problems, in the invention according to claim 1, a plurality of detection elements that output detection signals in different phases according to relative rotation with the detected object, and detection of the detection elements A rotation angle detecting device comprising: a calculating means for calculating an angle of rotation between the detected object and the detection element based on the arc tangent value by obtaining an arc tangent value according to an arc tangent function according to a signal; The gist is that the applied voltages to be supplied have the same value.

  According to this invention, in order to obtain the arc tangent signal, the calculating means first inputs a sine signal from the detection signal of one detection element and also inputs a cosine signal from the detection signal of the other detection element, Calculate based on value and cosine value. At this time, if the arc tangent value is obtained through a calculation process in which the sine value is divided by the cosine value, the tangent value obtained by the calculation takes the ratio of the sine value and the cosine value. Even if the sensitivity of the element decreases and the sine value and cosine value change, the value does not change. Therefore, since the rotation angle is calculated based on the arctangent value, the rotation angle obtained by the calculation means is not affected by the sensitivity reduction, and the detection accuracy of the rotation angle is ensured.

  Also, if the applied voltage supplied to the detection element is set to the same value, the amplitudes of the sine signal and the cosine signal have the same value, so that when the sine value is divided by the cosine value, each of the sine value and the cosine value is obtained. The amplitude term of the included signal waveform is canceled. Accordingly, since the arc tangent function calculation is simplified, in addition to the effect of ensuring the detection accuracy of the rotation angle even when the sensitivity of the detection element is reduced, there is an effect that the arc tangent value can be easily calculated. It should be noted that the detection condition of the detection element with respect to the detection target is the same condition, where the value of the condition includes a slight error.

  According to a second aspect of the present invention, in the first aspect of the present invention, the calculating means calculates the sine value based on a sine value according to the sine function and a cosine value according to the cosine function input from the detection element. The gist is to calculate a tangent value by dividing by the cosine value and to calculate the rotation angle by calculating the arc tangent value.

  According to the present invention, in addition to the operation of the first aspect, the tangent value is calculated by dividing the sine value by the cosine value, and the rotation angle is calculated by the inverse tangent value. Therefore, even if the sensitivity of the detection element decreases and the sine value and the cosine value change, when the tangent value is calculated, the change in the detection sensitivity is canceled, and the arc tangent value itself does not change. Therefore, since the rotation angle is calculated based on the arctangent value, the rotation angle obtained by the calculation means is not affected by the sensitivity reduction, and the detection accuracy of the rotation angle is ensured.

  In the invention according to claim 3, in the invention according to claim 1 or 2, the calculation means includes at least one of a sine value according to a sine function and a cosine value according to a cosine function input from the detection element, and The gist is to calculate the rotation angle based on the arctangent value.

  According to this invention, in addition to the operation of the invention described in claim 1 or 2, the arc tangent signal takes a waveform shape in which the waveform is repeated every 180 degrees, and therefore the rotation angle is calculated from 0 to 360 degrees. Two angles are obtained in one cycle from one arctangent value. However, if at least one of the sine value and the cosine value is used, it is possible to determine in which quadrant the obtained two arc tangent values exist. Accordingly, the rotation angle is uniquely derived from one arctangent value, and the rotation angle can be calculated from 0 to 360 degrees.

  According to the present invention, even when the detection sensitivity of the detection element is lowered, the accuracy of rotation angle calculation can be ensured, and the rotation angle calculation can be simplified.

Hereinafter, an embodiment of a rotation angle detection apparatus embodying the present invention will be described with reference to FIGS.
FIG. 1 is a schematic perspective view showing a schematic configuration of the rotation angle detection device 1. The rotation angle detection device 1 is used for, for example, a neutral start switch of a vehicle, and more specifically, is a detection device that detects an operation position of a shift lever (not shown) that is operated when a gear position of an automatic transmission is changed. The rotation angle detection device 1 includes a hollow case 2 and is assembled to a vehicle by fixing the case 2 to a vehicle body (not shown).

  Inside the case 2 is housed a magnet 3 that generates a predetermined magnetic field around itself. The magnet 3 is, for example, a cylindrical permanent magnet (neodymium, samarium, etc.), and is fixed to a rotating shaft 4 that rotates in conjunction with a shift lever. Therefore, when the shift lever is operated, the magnet 3 rotates in the corresponding rotation direction (the direction of arrow A in FIG. 1). The rotating shaft 4 is led out of the case through an insertion hole 2a on the upper wall of the case 2, and the magnet 3 is fixed so that the axis of the rotating shaft 4 coincides with the axis. The magnet 3 corresponds to the detection target.

  A substrate 5 on which various elements are mounted is attached to the inner bottom surface of the case 2. A plurality (two in this example) of magnetic sensors 6 and 7 for detecting the magnetic flux of the magnet 3 are mounted on the substrate 5 at positions facing the magnet 3. Each of the magnetic sensors 6 and 7 is a sensor using a magnetoresistive element (MRE), and is a circuit in which four resistive elements R1 to R4 are connected in a bridge shape as shown in FIG. Each of the resistance elements R1 to R4 is made of a ferromagnetic material such as Ni—Co having an anisotropic magnetoresistance effect, and its resistance value changes according to the direction of the magnetic flux applied to the magnetic sensor 6 (7). The magnetic sensors 6 and 7 correspond to detection elements.

  The magnetic sensors 6 and 7 output the midpoint potential ΔV of the bridge circuit as a magnetic flux detection signal. Here, since the direction of the magnetic flux passing through the magnetic sensors 6 and 7 changes according to the rotation position of the magnet 3, that is, the operation position (operation angle) of the shift lever, the midpoint potential ΔV is also set to the operation position of the shift lever. Will change accordingly. Therefore, the magnetic sensors 6 and 7 receive the magnetic flux from the magnet 3 in a direction corresponding to the operation position (operation angle) of the shift lever, and output a detection signal at a potential corresponding to the operation position of the shift lever.

  As shown in FIG. 2B, the directions of the resistance elements R1 to R4 are set so that the phases of the signal waveforms of the detection signals output from the magnetic sensors 6 and 7 are shifted by 90 degrees. Therefore, in this example, one of the magnetic sensors 6 is a sensor that outputs a signal according to a sine function, and outputs a sine signal Sa indicated by a one-dot chain line in FIG. The other magnetic sensor 7 is a sensor that outputs a signal corresponding to a cosine function, and outputs a cosine signal Sb indicated by a two-dot chain line in FIG.

  The magnetic sensors 6 and 7 are arranged in close proximity so that the magnetic field detection conditions for the magnet 3 are substantially the same, that is, both receive magnetic fluxes having substantially the same magnetic field (magnetic flux direction, magnetic field strength) from the magnet 3. As described above, when the magnetic sensors 6 and 7 are arranged close to each other, the output characteristics of the sine signal Sa and the cosine signal Sb output from the magnetic sensors 6 and 7 are synchronized, that is, the amplitude, the period, and the like are substantially the same. It becomes the state output by value. The magnetic sensors 6 and 7 are mounted on the substrate 5 by transferring a mask pattern onto the substrate 5.

  FIG. 3 is an electrical configuration diagram showing an electrical configuration of the rotation angle detection device 1. The rotation angle detection apparatus 1 converts a analog signal into a digital signal, a microcomputer 8 that controls the main control of the apparatus, a power supply circuit 9 that supplies a predetermined level of voltage to various devices (elements) in the apparatus, and the like. An A / D converter 10 and a D / A converter 11 that converts a digital signal into an analog signal are provided. The rotation angle detection device 1 is connected to the battery B of the vehicle as a power supply source and operates based on the power of the battery B.

  The power supply circuit 9 inputs the battery voltage from the battery B, converts it into a predetermined voltage level corresponding to various devices (elements), and outputs these voltages to the magnetic sensors 6 and 7 and the microcomputer 8 and the like. The magnetic sensors 6 and 7 and the microcomputer 8 are inputted with a stable predetermined level voltage as a driving power supply, and are operated by this power supply.

  Since both of the magnetic sensors 6 and 7 input the same voltage from the power supply circuit 9 as the drive power supply, they are used under the same bias condition, that is, the same applied voltage. When the magnetic sensors 6 and 7 are used under the same bias condition, the amplitude A1 of the sine signal Sa output from the magnetic sensor 6 and the amplitude A2 of the cosine signal Sb output from the magnetic sensor 7 have the same value. The magnetic sensors 6 and 7 are driven with the same bias, and output to the A / D converter 10 a sine value Y1 and a cosine value Y2 corresponding to the rotational position of the magnet 3, that is, the operation position of the shift lever. The A / D converter 10 digitally converts the sine value Y1 (cosine value Y2) input from the magnetic sensors 6 and 7, and outputs the sine value Y1 and cosine value Y2 after digital conversion to the microcomputer 8.

  The microcomputer 8 includes a calculation circuit 12 that calculates the rotation angle θ as the rotation position of the magnet 3, based on the sine value Y1 and the cosine value Y2, that is, the operation position of the shift lever, the ROM 13 that stores the rotation angle calculation program P, the rotation A RAM 14 and the like used as a work area at the time of angle calculation are provided. The rotation angle calculation program P is a program that calculates a tangent value according to a tangent function based on the sine value Y1 and the cosine value Y2, and calculates the rotation angle θ of the magnet 3 from the arc tangent value Vh. The calculation circuit 12 operates based on the rotation angle calculation program P and calculates the rotation angle θ of the magnet 3. As described above, the tangent value is calculated from the sine value Y1 and the cosine value Y2, and the rotation angle θ is calculated based on the arc tangent value Vh. The detection sensitivity of the sine wave and the cosine wave decreases due to a change in the external environment. Even when the sine value is obtained, the change in detection sensitivity is canceled out, so that a stable output can be obtained. The calculation circuit 12 and the rotation angle calculation program P correspond to calculation means.

  A method for calculating the rotation angle θ will be described below. First, the sine signal Sa (the signal indicated by the one-dot chain line in FIGS. 4 and 5) is the following equation (1), and the cosine signal Sb (the signal indicated by the two-dot chain line in FIGS. 4 and 5) is the following equation (2). And In these equations, Y1 is a sine value, Y2 is a cosine value, A1 is an amplitude of a sine signal Sa, and A2 is an amplitude of a cosine signal Sb.

Y1 = A1sin θ (1)
Y2 = A2 cos θ (2)
Then, the calculation circuit 12 calculates an arc tangent value Vh using the following equation (3) in order to obtain an arc tangent function.

Vh = arctan (Y1 / Y2) = arctan (tan θ) = θ (3)
Here, since the arc tangent value Vh corresponds to the rotation angle θ of the magnet 3, the calculation circuit 12 calculates the rotation angle θ by obtaining the arc tangent value Vh. The inverse tangent value Vh is output as a linear (substantially linear) inverse tangent signal Sc indicated by a solid line in FIG. 4 according to the value of the rotation angle θ. That is, the arc tangent signal Sc is a signal in which the output value (voltage value) takes a linear value according to the rotation angle θ of the magnet 3 and the signal waveform is repeated every 180 degrees.

  Here, even if an attempt is made to detect the rotation angle θ in the range of 0 to 360 degrees, the signal waveform of the arctangent signal Sc takes the same waveform every 180 degrees, so that the same arctangent value Vh is 0 to 180 degrees. The rotation angle θ is derived in each region of 180 to 360 degrees. Therefore, even if an attempt is made to obtain the rotation angle θ using only the arctangent value Vh, one rotation angle θ is not uniquely determined by one arctangent value, and if it is 0 to 180 degrees, the rotation angle can be detected. There is a current situation in which rotation angle detection cannot be performed between ˜360 degrees.

  Therefore, the calculation circuit 12 detects the rotation angle in consideration of the signal waveform of the sine signal Sa so that the rotation angle can be detected in the range of 0 to 360 degrees. Specifically, as shown in FIGS. 6A and 7, the sine value Y1 is when the rotation angle θ is 0 to 90 degrees (first quadrant) and 90 to 180 degrees (second quadrant). And a negative value when the rotation angle θ is 180 to 270 degrees (third quadrant) and 270 to 360 degrees (fourth quadrant). On the other hand, as shown in FIGS. 6B and 7, the tangent value takes the same value in the first quadrant, the third quadrant, the second quadrant, and the fourth quadrant. Therefore, when the arctangent value Vh is calculated, if the quadrant where the sine value Y1 at that time is located, the two rotation angles θ that can be obtained from one arctangent value Vh are respectively in which quadrant. Therefore, the rotation angle θ can be calculated uniquely from the arctangent value Vh.

  For example, when the arctangent value Vh1 (> 0) is calculated as shown in FIG. 4, the rotation angle θ1 between 0 and 90 degrees or 180 to 270 degrees from the arctangent value Vh1. Can be calculated. At this time, considering the value of the sine value Y1, for example, if the rotation angle θ is 0 to 90 degrees, the sine value Y1 takes a positive value, and if the rotation angle θ is 180 to 270 degrees, the sine value Y1 is negative. Takes the value of Therefore, if the sine value Y1 is a positive value, the rotation angle θ is calculated as θ1, and if the sine value Y1 is a negative value, the rotation angle θ is calculated as θ2.

  As shown in FIG. 3, when calculating the arctangent value Vh, that is, the rotation angle θ, the calculation circuit 12 outputs a digital output signal corresponding to the calculated value to the D / A converter 11. The D / A converter 11 analog-converts the output signal input from the calculation circuit 12 and supplies the output signal after analog conversion to various control devices (various ECUs) of the vehicle.

Next, the operation of the rotation angle detection device 1 of this example will be described.
When the engine is started on the vehicle, the rotation angle detection device 1 is activated, and the calculation circuit 12 inputs the sine value Y1 and the cosine value Y2 from the magnetic sensors 6 and 7 via the A / D converter 10. The calculation circuit 12 calculates the arc tangent value Vh using the above-described equation (3), that is, the arc tangent function, and calculates the rotation angle θ of the magnet 3 from the arc tangent value Vh. Thus, when the rotation angle detection device 1 is used in an engine neutral switch of the vehicle, the operation position of the shift lever that changes the gear of the automatic transmission of the vehicle is detected.

  Here, for example, it is assumed that a temperature rise occurs around the rotation angle detection device 1 and the detection sensitivity of the magnetic sensors 6 and 7 is lowered. At this time, if the state shown in FIG. 4 is a normal state, the output of each of the magnetic sensors 6 and 7 (that is, the sine value Y1 and the cosine value Y2) is affected due to this sensitivity reduction, and the sine signal Sa. The cosine signal Sb has an output waveform shown in FIG. 5 in which the amplitudes A1 and A2 are reduced. Here, if the rotation angle is detected using the sine signal Sa or the cosine signal Sb, an error will occur in the calculation of the rotation angle θ due to a decrease in sensitivity.

  However, in the calculation of the rotation angle θ in this example, the tangent value is obtained by dividing the sine value Y1 by the cosine value Y2, and the rotation angle θ is calculated from the inverse tangent value Vh. Therefore, even if the sine value Y1 and the cosine value Y2 are decreased due to a change in the external environment, the tangent value undergoes a calculation procedure for dividing the sine value Y1 by the cosine value Y2, that is, the ratio of the sine value Y1 and the cosine value Y2 is obtained. Therefore, the change in detection sensitivity between the sine value Y1 and the cosine value Y2 is canceled out. For this reason, even if the sensitivity of the magnetic sensors 6 and 7 is reduced and the values of the amplitudes A1 and A2 are lowered, no change occurs in the arctangent value Vh that is an inverse function of the tangent value. Therefore, if the rotation angle is detected using the arctangent function, the sensitivity of the rotation angle θ is not affected and the detection accuracy of the rotation angle θ is ensured.

  Further, the magnetic sensors 6 and 7 are arranged in proximity so that the magnetic sensors 6 and 7 detect substantially the same magnetic field from the magnet 3. Therefore, the output characteristics of the magnetic sensors 6 and 7 (that is, the amplitude and period of the sine signal Sa and cosine signal Sb) are synchronized. Here, if an error occurs in the output characteristics between the magnetic sensor 6 and the magnetic sensor 7, a correction process for matching the output characteristics between them is necessary to accurately derive the rotation angle θ. It is not necessary to perform such correction processing, and the rotation angle θ can be obtained with high accuracy by simple calculation processing.

  Further, since the magnetic sensors 6 and 7 are used under the same bias condition (same applied voltage), the amplitude A1 of the sine signal Sa and the amplitude A2 of the cosine signal Sb have the same value (A1 = A2). It becomes. Therefore, the arc tangent value Vh undergoes a calculation process in which the sine value Y1 is divided by the cosine value Y2. Therefore, when calculating the arc tangent value, the term of the amplitude A1 included in the sine value Y1 and the amplitude included in the cosine value Y2. The term A2 is offset. Accordingly, the calculation of the arc tangent value Vh is simplified, the calculation of the arc tangent value is not complicated, and the calculation speed of the arc tangent value Vh is improved and the program amount of the calculation program is suppressed.

  Further, as described above, since the arctangent signal Sc has a waveform shape in which the waveform is repeated every 180 degrees, the rotation angle θ cannot be calculated in the range of 360 degrees only with the arctangent value Vh. However, if the rotation angle θ is calculated by combining the sign of the sine value Y1 in addition to the calculation of the arctangent value Vh, the rotation angle θ can be uniquely calculated from one arctangent value Vh. Therefore, in this example, since the rotation angle is calculated using the arctangent value Vh and the sine value Y1, the rotation angle θ can be calculated in the range of 0 to 360 degrees. Will cover a wide area.

According to the configuration of the above embodiment, the following effects can be obtained.
(1) The rotation angle θ of the magnet 3 is calculated by obtaining a tangent value based on the sine value Y1 and the cosine value Y2, and obtaining its arc tangent value Vh. Therefore, even if the sensitivity decreases in the magnetic sensors 6 and 7 and the values of the amplitudes A1 and A2 decrease, for example, the decreased amount is canceled when calculating the tangent value Vh. There is no change in the value of the tangent value Vh. Therefore, even if the sensitivity of the magnetic sensors 6 and 7 is reduced, the detection accuracy of the rotation angle θ can be ensured. Further, since the magnetic sensors 6 and 7 are arranged close to each other, the output characteristics of the magnetic sensors 6 and 7 are in a synchronized state, so that correction to match the output characteristics is not necessary, and accuracy can be achieved by simple calculation processing. The rotation angle θ can be calculated well.

  Furthermore, since the magnetic sensors 6 and 7 are used under the same bias condition, that is, the same applied voltage, the amplitude A1 of the sine signal Sa output from the magnetic sensor 6 and the amplitude of the cosine signal Sb output from the magnetic sensor 7 A2 takes the same value. The arc tangent value Vh undergoes a calculation process in which the sine value Y1 is divided by the cosine value Y2. Therefore, in the calculation, the term of the amplitude A1 included in the sine value Y1, the term of the amplitude A2 included in the cosine value Y2, and Is canceled out, and the arctangent value Vh can be easily calculated. Further, with the simplification of the calculation procedure, it is effective in improving the calculation speed of the arc tangent value Vh and reducing the program amount of the calculation program of the arc tangent value Vh.

  (2) The rotation angle θ can be detected only during a half cycle (0 to 180 degrees) with the arctangent value Vh alone. However, when the rotation angle θ is detected in the range of 0 to 360 degrees, the sign of the sine value Y1 in addition to the arc tangent value Vh even if a plurality of rotation angles θ are derived from one arc tangent value Vh. As can also be seen, the rotation angle θ can be uniquely calculated from one arctangent value Vh, and the rotation angle θ can be calculated in one cycle, that is, 0 to 360 degrees.

  (3) Since the magnetic sensors 6 and 7 are manufactured by transferring the mask pattern onto the substrate 5, the magnetic sensors 6 and 7 in the proximity state can be manufactured with high dimensional accuracy. As described above, if the magnetic sensors 6 and 7 in the proximity state can be manufactured with high dimensional accuracy, errors in magnetic detection conditions (for example, a magnetic field received from the magnet 3) between the magnetic sensors 6 and 7 can be suppressed low. This further contributes to improvement in the detection accuracy of the rotation angle θ.

  (4) As a coping method when the sensitivity drop occurs in the magnetic sensors 6 and 7, the method of calculating the inverse sine value (inverse cosine value) described in the prior art is used. For example, a temperature sensor is mounted on the substrate 5. A method of correcting the inverse sine value (inverse cosine value) based on the temperature value obtained from the temperature sensor is also conceivable. However, if this method is used, a temperature sensor is required separately, which may increase the cost and size of the apparatus. However, since this type of temperature sensor is unnecessary if the configuration of this example is used, there is no fear of increasing the cost and size of the apparatus.

In addition, you may change the said embodiment not only to the said structure but to the following aspects.
-When using the magnetic sensors 6 and 7 under the same bias condition, the same bias condition is not limited to using the same power supply, and even if different power supplies are used, the magnetic sensors 6 and 7 are finally supplied. It is only necessary that the applied voltages are the same.

  When the rotation angle θ can be detected in the range of 0 to 360 degrees, the rotation angle θ is uniquely calculated from the arctangent value Vh by adding the sign of the sine value Y1 in addition to the arctangent value Vh. For example, the rotation angle θ of the arctangent value Vh may be specified by the sign of the cosine value Y2 instead of the sine value Y1.

  The magnetic sensors 6 and 7 are not limited to those using magnetoresistive elements (MRE), but may be those using Hall elements, for example. Further, the detection element is not limited to the magnetic type, and may be an optical type, for example.

  The rotation angle detection device 1 is not limited to detecting the rotation angle θ within a range of one rotation of 0 to 360 degrees. For example, the calculation circuit 12 may count each time the rotation angle θ exceeds 360 degrees so that two or more rotations can be detected.

The magnet 3 is not limited to a columnar shape, and may be, for example, a plate-like shape, and is not particularly limited as long as it is a shape that matches the attachment destination of the rotation angle detection device 1.
The magnet 3 is attached to the shift lever side and the magnetic sensors 6 and 7 are not attached to the vehicle body side. This combination is reversed, that is, the magnetic sensors 6 and 7 are attached to the shift lever side and the magnet 3 is attached to the vehicle body side. It may be attached.

  The rotation angle detection device 1 is not limited to being employed as a neutral start switch (inhibitor switch). For example, the brake pedal operation amount detection, the accelerator pedal operation amount detection, the steering rotation angle detection, and the motor throttle opening degree You may employ | adopt for a detection etc.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(1) In any one of Claims 1-3, the said detection element was arrange | positioned in the proximity | contact state so that the detection conditions of the said detection element with respect to the said to-be-detected body may become the same conditions.

(2) In any one of Claims 1-3, the said detection element is a magnetic detection element which detects the magnetic field output from the said to-be-detected body.
(3) In any one of Claims 1-3, the said detection element is manufactured on the board | substrate by transferring the mask pattern to the board | substrate to the said detection element.

The schematic perspective view which shows schematic structure of the rotation angle detection apparatus in one Embodiment. (A) is an equivalent circuit schematic of a magnetic sensor, (b) is a top view of a board | substrate. The electrical block diagram which shows the electrical structure of a rotation angle detection apparatus. The wave form diagram which shows the waveform of the arc tangent function at the normal time. The wave form diagram which shows the waveform of the arctangent function at the time of a sensitivity fall. (A) is a wave form diagram which shows the waveform of a sine function, (b) is a wave form diagram which shows the waveform of a tangent function. The model figure which shows the code | symbol in each quadrant of a sine value and an arctangent value. The wave form diagram which shows the waveform of the conventional inverse sine function.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rotation angle detection apparatus, 3 ... Magnet as to-be-detected body, 6, 7 ... Magnetic sensor as detection element, 12 ... Calculation circuit which comprises calculation means, (theta) ((theta) 1, (theta) 2) ... Rotation angle, P ... Calculation Rotation angle calculation program constituting means, Vh (Vh1): arc tangent value, Y1: sine value, Y2: cosine value, Sa: sine signal, Sb: cosine signal, Sc: arc tangent signal.

Claims (3)

A plurality of detection elements that output detection signals corresponding to relative rotation with the detected object in different phases, and an arc tangent value according to an arc tangent function based on the detection signal of the detection element is obtained, and the arc tangent value is obtained. A rotation angle detection device comprising: a calculation means for calculating a rotation angle between the detection object and the detection element based on
The rotation angle detection device characterized in that the applied voltages supplied to the detection elements have the same value.   The calculation means calculates a tangent value by dividing the sine value by the cosine value based on a sine value according to the sine function and a cosine value according to the cosine function input from the detection element, and calculates the arc tangent value. The rotation angle detection device according to claim 1, wherein the rotation angle is calculated by calculation.   The calculation means calculates the rotation angle based on at least one of a sine value corresponding to a sine function and a cosine value corresponding to a cosine function input from the detection element, and the arctangent value. Or the rotation angle detection apparatus of 2.

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