JP2006226816A - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a downsized rotation angle detector for reducing detection errors in a rotation angle. <P>SOLUTION: A yoke and a permanent magnet rotate together with a detecting object. Hall elements 30 and 31 are placed so as to form an angle of 90° with the rotating direction of the detecting object. The hall elements 30 and 31 output analog signals with their phases different from each other correspondingly to a magnetic field changing with the rotation of the detecting object. These analog signals are converted into digital form by an A/D converter 52 and offset-corrected by an offset adjustment circuit 56. A control part 58 calculates an output angle by an arctangent operation from the outputs of the hall elements 30 and 31 after the digital conversion and offset correction. The control part 58 and an angle signal generation circuit 60 generate an angle signal by analog-converting the output angle. The control part 58 and a pulse signal generation circuit 62 generate a pulse signal by changing its output according to the result of comparison between a plurality of angle candidates and the output angle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle detection device.

2. Description of the Related Art Conventionally, a so-called electromagnetic pickup (MPU) type rotation angle detection device that rotates a rotor in conjunction with rotation of a detection target and detects a rotation angle of the detection target from an output signal that changes due to rotation of the rotor of the pickup sensor is known. ing. For example, as the rotor, a gear is used in which teeth are provided at regular intervals on the outer periphery in the rotational direction except for the missing teeth. In such an MPU-type rotation angle detection device, a reference rotation angle (reference angle) is obtained from a specific waveform of the output signal of the pickup sensor (for example, a waveform corresponding to the aforementioned tooth missing portion of the gear), and the pickup sensor The relative rotation angle (relative angle) with respect to the reference angle is acquired from the level change of the output signal (for example, the level change corresponding to the gear tooth portion described above), and the rotation of the detection target is obtained from the reference angle and the relative angle. Detect the angle.
On the other hand, a rotation angle detection device that detects a rotation angle of a detection target in a range of 0 ° to 360 ° is known (for example, see Patent Document 1). In the rotation angle detection device described in Patent Document 1, a magnetic detection means having two Hall elements is rotated relative to a magnetic field generation means such as a permanent magnet, and an output signal that changes depending on the rotation of the detection target of the Hall elements. To detect the rotation angle of the detection target. Specifically, an analog signal that changes one-to-one in a 360 ° cycle with respect to the rotation angle of the detection target is generated by inverse calculation of a trigonometric function based on the output signal of the Hall element, and the rotation of the detection target is generated from the angle signal. The angle is detected in the range of 0 ° to 360 °.
JP-A-62-95402

However, in the MPU rotation angle detection device, since the rotor for which the pickup sensor detects the reference angle and the relative angle is machined, the dimensional tolerance of the rotor becomes a rotation angle detection error. On the other hand, the rotation angle detection device described in Patent Document 1 detects a rotation angle of a detection target from an analog angle signal, and thus there is a problem that a rotation angle detection error increases due to noise superimposed on the angle signal.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a rotation angle detection device that can reduce a rotation angle detection error and can be miniaturized.

According to the first to eighth aspects of the invention, since the angle signal generated by the angle signal generating means indicates the rotation angle of the detection target, the absolute rotation angle of the detection target can be detected from the angle signal.
However, when detecting the rotation angle of the detection target from the angle signal, if noise is superimposed on the analog angle signal, the rotation angle detection error increases due to the noise.
Therefore, in the inventions according to claims 1 to 8, the pulse signal generation means generates a pulse signal that is not easily affected by noise. Since the signal level of the pulse signal changes when the rotation angle of the detection target is one of a plurality of angle candidates, if the rotation angle detected from the angle signal is used as the reference angle, the rotation angle of the detection target from the pulse signal Can be identified from among a plurality of angle candidates. As described above, according to the first to eighth aspects of the present invention, since the rotation angle of the detection target can be detected from the pulse signal that is not easily affected by noise, the rotation angle of the detection target is determined from the pulse signal in a noisy environment. It is also possible to detect. Thereby, compared with the case where the analog signal which shows the rotation angle of a detection target is produced | generated from the output of a magnetic detection means, and it detects from an analog signal, the detection error of the rotation angle by noise can be suppressed.
Note that the MPU rotation angle detection device detects the reference angle from a specific waveform of the output signal of the pickup sensor (for example, a waveform corresponding to a missing tooth portion formed at one location on the outer periphery in the rotation direction of the rotor). The absolute rotation angle of the detection object cannot be detected until the detection object rotates once after the object starts. However, according to the invention described in claims 1 to 8, in order to obtain the reference angle from the angle signal, the reference angle is set even before the detection target rotates once, for example, before the detection target is started or immediately after the detection target is started. Can be acquired. That is, according to the first to eighth aspects of the invention, the rotation angle of the detection target can be detected from the pulse signal at the early stage of the rotation start of the detection target.

  According to the invention described in claims 1 to 8, the magnetic detection means is rotated relative to the magnetic field generation means by the rotation of the detection target, thereby changing the magnetic field detected by the magnetic detection means relatively. Yes. That is, the dimensional tolerance related to the component for changing the magnetic field detected by the magnetic detection means does not affect the change of the magnetic field. The magnetic detection element of the magnetic detection means can be manufactured using a semiconductor manufacturing process. If the magnetic detection element is manufactured using a semiconductor manufacturing process, the magnetic detection element can be appropriately arranged in the magnetic detection means. Therefore, according to the first to eighth aspects of the invention, since the rotation angle detection error caused by the dimensional tolerance of machining can be eliminated, the rotation angle detection error can be reduced.

Here, the pulse signal may be generated from a digital signal indicating the rotation angle to be detected (for example, a signal output from a microprocessor described in Patent Document 1). In that case, a pulse signal may be generated by changing the signal level according to the comparison result between the rotation angle indicated by the digital signal and the angle candidate. However, since the pulse signal generated in this way includes a sampling error when converting the output of the magnetic field detection means into a digital signal, the rotation angle detected from the pulse signal has a detection error due to the sampling error. included.
Therefore, in the second aspect of the invention, the pulse signal is generated by changing the output signal level according to the comparison result between the output signal level of the second magnetoresistive element group and the predetermined threshold value. That is, a pulse signal is generated from the output signal of the second magnetoresistive element group without performing A / D conversion by analog signal processing. Therefore, according to the second aspect of the present invention, since the rotation angle detection error caused by the sampling error can be eliminated, the rotation angle detection error can be reduced.

Here, the magnetic detection element outputs a signal of a certain level (hereinafter referred to as an offset) even in a state where no magnetic field is generated. That is, the output of the first magnetic detection element group and the output of the second magnetic detection element group include a direct current component.
Accordingly, in the third and fourth aspects of the invention, the direct current component of the output signal of the second magnetic detection element group is removed, and a pulse signal is generated from the output signal of the second magnetic detection element group after the removal of the direct current component. Therefore, since the rotation angle detection error caused by the offset can be eliminated, the rotation angle detection error detected from the pulse signal can be reduced.
According to the fourth aspect of the present invention, the correcting means is constituted by an AC coupling circuit. In general, since the circuit scale of the AC coupling circuit is small, the correction means can be miniaturized.

In the invention according to claim 5, the first correction means and the second correction means respectively remove the direct current component of the output signal of the first magnetic detection element group and the direct current component of the output signal of the second magnetic detection element group. .
The first correction means acquires the offset of each magnetic detection element of the first magnetic detection element group in a state where no magnetic field is generated, and removes the DC component of the output signal of the first magnetic detection element group based on the offset To do. Therefore, the DC component of the output signal of the first magnetic detection element group can be removed regardless of the frequency of the signal output from the first magnetic detection element group, that is, the rotational speed of the detection target.
On the other hand, a 2nd correction | amendment means removes the direct current component of the output signal of a 2nd magnetic detection element group by an AC coupling circuit. As described above, since the circuit scale of the AC coupling circuit is small, the second correction means can be reduced in size. However, in the AC coupling circuit, when the frequency of the output signal of the second magnetic detection element group is low, that is, when the rotation speed of the detection target is low, the AC component of the low-frequency output signal and the DC component due to offset are properly separated. The DC component cannot be removed because it cannot.
Therefore, in the fifth aspect of the present invention, when the rotation speed of the detection target is a predetermined speed or less, the first candidate pulse signal generated from the output signal of the first magnetic detection element group is selected as the pulse signal. As described above, the direct current component of the output signal of the first magnetic detection element group can be removed by the first correction means even when the rotation speed of the detection target is low, so that the detection target is detected from the first candidate pulse signal selected as the pulse signal. If the rotation angle is detected, a rotation angle detection error caused by the offset can be eliminated.

However, the rotation angle detected from the first candidate pulse signal includes a detection error caused by a sampling error similar to the case where the pulse signal is generated from the digital signal described above. This detection error is small and does not cause a problem when the rotation speed of the detection target is slow, but increases as the rotation speed of the detection target increases.
Therefore, in the invention according to claim 5, when the rotational speed of the detection target is faster than a predetermined speed and the DC component of the output signal of the second magnetic detection element group can be removed by the AC coupling circuit, A / D conversion is performed. The second candidate pulse signal generated from the output signal of the second magnetic detection element group without analog processing is selected as the pulse signal. Thereby, the detection error of the rotation angle due to the sampling error can be eliminated. Therefore, according to the invention described in claim 5, when the rotation speed of the detection target is slow, the detection error due to the offset can be eliminated, and when the rotation speed of the detection target is high, the rotation angle due to the sampling error can be eliminated. Detection error can be eliminated. Therefore, the rotation angle detection error can be reduced.

According to the invention described in claim 6, since the magnetic detection means, the angle signal generation means, and the pulse signal generation means are mounted on one chip, noise superimposed on the analog signal output from the magnetic detection means can be reduced. The rotation angle detection error due to noise can be suppressed.
Further, since the magnetic detection means, the angle signal generation means, and the pulse signal generation means are integrated on one chip, the magnetic detection means, the angle signal generation means, and the pulse signal generation means can be reduced in size.

Hereinafter, a plurality of embodiments of the present invention will be described based on the drawings. In each embodiment, the component to which the same code | symbol was attached | subjected corresponds to the component of the other embodiment to which the code | symbol was attached | subjected.
(First embodiment)
As shown in FIG. 2, the rotation angle detection device 10 according to the first embodiment of the present invention is a crank angle detection device mounted on, for example, an internal combustion engine ignition device 12. At this time, the rotation angle detection device 10 outputs an analog signal and a pulse signal correlated with the angle of the crankshaft as a detection target (hereinafter referred to as a crank angle), and an electronic control unit (ECU) 40 of the internal combustion engine The cylinder to be ignited is determined based on the crank angle specified from these signals.

FIG. 1 is a block diagram of the rotation angle detection device 10. FIG. 3 is a schematic diagram of the rotation angle detection device 10.
The yoke 20 and the permanent magnets 22 and 24 shown in FIG. 3 rotate together with the detection target. The permanent magnets 22 and 24 are formed in an arc shape, and are arranged on the inner peripheral wall of the cylindrical yoke 20 on the opposite side by 180 °. The permanent magnet 22 and the permanent magnet 24 form a parallel magnetic field having a constant magnetic flux density.

The drive circuit 50, Hall elements 30 and 31, amplifier 52, A / D converter 54, offset adjustment circuit 56, control unit 58, angle signal generation circuit 60, and pulse signal generation circuit 62 shown in FIG. It is mounted on an element (hereinafter referred to as a sensor chip) 70. The sensor chip 70 is attached to a support member that does not rotate with the rotation of the detection target so that the Hall elements 30 and 31 are located near the center of the yoke 20.
The Hall element 30 and the Hall element 31 are each driven with a constant current by the drive circuit 50. The Hall element 30 and the Hall element 31 are arranged so as to form an angle of 90 ° in the rotation direction of the detection target. The Hall element 30 and the Hall element 31 may be driven with a constant voltage.

When the yoke 20 and the permanent magnets 22 and 24 rotate together with the detection target, the Hall element 30 and the Hall element 31 output sinusoidal output signals 100 and 101 as voltages as shown in FIG. The output signal 100 of the Hall element 30 and the output signal 101 of the Hall element 31 have a phase difference of 90 °. That is, the output signal 100 of the Hall element 30 and the output signal of the Hall element 31 have a relationship of 101 sin and cos. Therefore, the rotation angle of the detection target is θ, the output signal 100 of the Hall element 30 is Va, the output signal 101 of the Hall element 31 is Vb, the coefficient determined by the sensitivity of the Hall elements 30 and 31 is k, and the permanent magnets 22 and 24 If the magnetic flux density of the magnetic field formed by B is B and the constant current supplied to the Hall elements 30 and 31 is I, Va and Vb are expressed by the following equations (1) and (2).
Va = kBI · sin θ (1)
Vb = kBI · sin (θ + 90) = kBI · cos θ (2)
The amplifier 52 amplifies the output signals 100 and 101 of the Hall element 30 and the Hall element 31. The A / D converter 54 converts the amplified signal into digital numerical data by sampling at a predetermined period.

Here, an offset may occur in the output of the Hall element. The rotation angle of the detection target cannot be accurately detected based on the output signals Va and Vb of the Hall elements 30 and 31 in which the offset is generated. Therefore, the offset adjustment circuit 56 corrects the offset of the Hall elements 30 and 31.
The control unit 58 cooperates with the offset adjustment circuit 56 to correct the offset of the Hall elements 30 and 31, and cooperates with the angle signal generation circuit 60 and the pulse signal generation circuit 62 to output an angle signal and a pulse signal described later. Generate. Hereinafter, the offset correction process, the angle signal generation process, and the pulse signal generation process will be described in this order.

First, the offset correction process will be described.
First, the control unit 58 reads the output signals of the Hall elements 30 and 31 without being affected by the magnetic field. Next, the rotation angle detection device 10 stores the signal level of the read output signal as an offset value. Specifically, for example, the rotation angle detection device 10 has a nonvolatile memory as the offset adjustment circuit 56, and the control unit 58 stores the offset value in the nonvolatile memory. Next, the control unit 58 subtracts the stored offset value from the output signals of the Hall elements 30 and 31 read during the angle signal generation process and the pulse signal generation process. In this way, the control unit 58 and the offset adjustment circuit 56 correct the offset of the Hall elements 30 and 31. The controller 58 and the offset adjustment circuit 56 at this time correspond to “correction means” described in the claims. In the following description, it is assumed that Va (see Equation 1) and Vb (see Equation 2) are numerical data after the output signals of the Hall elements 30 and 31 are A / D converted and offset and gain correction is performed.

Next, the angle signal generation process will be described.
First, the control unit 58 calculates tan θ from the ratio of Va and Vb (see the following equation (3)), and calculates the calculation angle 110 shown in FIG. 5 by its arctangent calculation (see the following equation (4)). ). The cycle of the calculation angle 110 is 180 °.
Va / Vb = sin θ / cos θ = tan θ (3)
θ = arctan (Va / Vb) (4)

  Next, the control unit 58 determines the signs of Va and Vb as shown in FIG. 7, and identifies the rotation angle position of the detection target within the 360 ° angle range. Next, the control unit 58 calculates the output angle 120 shown in FIG. 6 by adding an offset angle to the calculation angle 110 based on the identified rotational angle position of the detection target. Then, the control unit 58 causes the angle signal generation circuit 60 to output an analog angle signal correlated with the output angle 120. Specifically, the control unit 58 outputs the output angle 120 to the angle signal generation circuit 60. Then, the angle signal generation circuit 60 generates an angle signal having a signal level proportional to the output angle 120 by converting the output angle 120 to analog by a digital / analog converter (not shown). In this way, the control unit 58 and the angle signal generation circuit 60 generate an angle signal. The control unit 58 and the angle signal generation circuit 60 at this time correspond to “angle signal generation means” recited in the claims.

Next, the pulse signal generation process will be described.
The control unit 58 causes the pulse signal generation circuit 62 to generate a pulse signal whose signal level changes when the rotation angle to be detected is one of a plurality of angle candidates. Here, the angle candidate is a rotation angle that the rotation angle detection device 10 should detect. For example, when the rotation angle detection device 10 is a crank angle detection device mounted on the internal combustion engine ignition device 12, the angle candidate is This is the crank angle corresponding to the timing to be ignited. Specifically, the control unit 58 compares the plurality of angle candidates with the output angle 120, and changes the signal level of the output of the pulse signal generation circuit 62 when any of the plurality of angle candidates matches the output angle 120. The control unit 58 and the pulse signal generation circuit 62 at this time correspond to “pulse signal generation means” recited in the claims.

As shown in FIG. 2, the sensor chip 70 and the ECU 40 are electrically connected by a signal line 80 that transmits an angle signal and a signal line 81 that transmits a pulse signal. The A / D converter 42 converts an analog angle signal into digital numerical data.
The control unit 44 includes a ROM and a RAM (not shown), and by executing a program stored in the ROM, the rotation angle of the detection target is specified from the numerical data obtained by digitizing the angle signal or is detected from the pulse signal. Specify the target rotation angle. Hereinafter, processing for specifying the rotation angle of the detection target from the pulse signal will be described.

FIG. 8 is a diagram showing a specific example of processing for specifying the rotation angle of the detection target from the pulse signal. In the specific example shown below, it is assumed that 12 angle candidates (0 °, 30 °, 60 °... 330 °) are set every 30 ° in the range of 0 ° to 360 °.
First, the control unit 44 of the ECU 40 specifies a rotation angle to be detected from the output angle 120 and sets the rotation angle as a reference angle. Then, the control unit 44 selects an angle candidate corresponding to the rotation angle of the detection target when the signal level of the pulse signal changes from a plurality of angle candidates based on the reference angle. For example, if the control unit 44 of the ECU 40 specifies that the reference angle is 45 ° from the angle signal, as shown in FIG. 8, when the pulse signal rises immediately after that, it selects 60 ° from 12 angle candidates. Then, when the pulse signal falls, 90 ° is selected. The selected angle candidate is the rotation angle of the detection target when the signal level of the pulse signal changes.
In addition, when the detection target is not only in the same direction but also forward and reverse rotation, two pulse signals with different phases are generated, such as an A-phase pulse signal and a B-phase pulse signal of an incremental rotary encoder, What is necessary is just to discriminate | determine a rotation direction.

According to the rotation angle detection device 10 according to the first embodiment of the present invention described above, the rotation angle of the detection target can be detected from both the angle signal and the pulse signal.
Here, analog signals such as signals and angle signals output from the D / A converter described in Patent Document 1 are easily affected by noise. According to the rotation angle detection device 10 according to the first embodiment of the present invention, since the rotation angle of the detection target can be detected also from the pulse signal, the rotation angle detection error under a noisy environment can be reduced.
Further, the direction of the magnetic field detected by the Hall elements 30 and 31 is changed by rotating the yoke 20 and the permanent magnets 22 and 24 relative to the sensor chip 70 together with the detection target. Therefore, the dimensional tolerance between the yoke 20 and the permanent magnets 22 and 24 does not affect the change of the magnetic field. Further, since the Hall elements 30 and 31 are manufactured using a semiconductor manufacturing process, the Hall elements 30 and 31 can be appropriately arranged on the sensor chip 70. Accordingly, since the rotation angle detection error caused by the dimensional tolerance of machining can be eliminated, the rotation angle detection error can be reduced.

(Second embodiment)
FIG. 9 is a schematic diagram of a rotation angle detection device according to the second embodiment of the present invention.
The rotation angle detection device 210 includes Hall elements 32 to 35 in addition to the Hall element 30 and the Hall element 31.
The Hall elements 30 to 35 are located on a circle 90 centered on the central axis 20a of the yoke 20, and each Hall element of the Hall elements 30 to 35 is point-symmetrical with respect to the central axis 20a of the yoke 20 where other Hall elements are formed. And are arranged differently. The reason why the Hall elements 30 to 35 are arranged in this manner is that the two Hall elements arranged in a point-symmetrical position with respect to the central axis 20a of the yoke 20 output signals having inverted phases with each other. This is because it cannot be used for the pulse signal generation processing in the circuit 62. Specifically, for example, each of the Hall elements 30 to 35 is arranged in a range of 150 ° on the circle 90 so as to rotate 30 ° in the rotation direction of the detection target with respect to the adjacent Hall elements. By arranging the Hall elements 30 to 35 in this way, it is possible to generate a pulse signal whose signal level changes at 12 angle candidates every 30 ° in the range of 0 ° to 360 °. Details will be described later.

  A constant current is supplied to each of the Hall elements 30 to 35 by the drive circuit 50. The Hall element 30 and the Hall element 31 correspond to the “first magnetic detection element group” recited in the claims, and the Hall elements 30 to 35 correspond to the “second magnetic detection element group” recited in the claims. Hereinafter, the Hall element 30 and the Hall element 31 are referred to as a first magnetic detection element group, and the Hall elements 30 to 35 are referred to as a second magnetic detection element group.

FIG. 10 is a block diagram of the rotation angle detection device 210.
The offset adjustment circuit 256 and the pulse signal generation circuit 262 are mounted on the sensor chip 70.
The offset adjustment circuit 256 corrects the offset of the second magnetic detection element group. Specifically, for example, the offset adjustment circuit 256 has a resistor whose resistance value can be adjusted in each Hall element of the second magnetic detection element group, and the hole is adjusted according to the offset of each Hall element in the second magnetic detection element group. The offset of the second magnetic detection element group is adjusted by adjusting the resistance value of the resistor corresponding to the element.
The pulse signal generation circuit 262 generates a pulse signal by changing the output signal level according to the comparison result between the output signal of the second magnetic detection element group after offset correction and a predetermined threshold value. That is, the pulse signal generation circuit 262 generates a pulse signal from the output signal of the second magnetic detection element group without performing A / D conversion by analog processing. Hereinafter, a specific example of the pulse signal generation processing in the pulse signal generation circuit 262 will be described with reference to FIG.

FIG. 11 is a graph for explaining the relationship between the output signal of the second magnetic detection element group and the pulse signal generated by the pulse signal generation circuit 262. (A) shows the output signal of the second magnetic detection element group, and (B) shows the pulse signal generation circuit 262 from the output signal of the second magnetic detection element group shown in (A) when the above threshold is set to 0. The pulse signal to be generated is shown.
The pulse signal generation circuit 262 changes the sign of any signal level of the output signals 100 to 104 when any of the comparison results between the signal levels of the output signals 100 to 104 of the Hall elements 30 to 35 and the threshold value 0 changes. When the signal changes, the output signal level is changed. More specifically, the pulse signal generation circuit 262 increases the signal level of the output when the sign of the signal level of the output signal 104 changes from positive to negative (see the vicinity of the rotation angle of 30 ° in FIG. 11A). When the sign of the signal level of the output signal 103 changes from positive to negative (refer to the vicinity of the rotation angle of 60 ° in FIG. 11A), the output signal level is changed to low level. In this way, the pulse signal generation circuit 262 forms one pulse that rises at a rotation angle of 30 ° and falls at a rotation angle of 60 °.

In this way, the pulse signal generation circuit 262 changes the output signal level in accordance with the comparison result between the output signal level of the second magnetic detection element group and the threshold value 0, so that the range of 0 ° to 360 ° is obtained. Thus, it is possible to generate a pulse signal whose signal level changes with 12 angle candidates every 30 °. The angle candidate can be set to a desired angle by designing the formation position of each Hall element of the second magnetic detection element group and the above-described threshold value.
According to the rotation angle detection device 210 according to the second embodiment of the present invention described above, a pulse signal is generated from the output signal of the second magnetic detection element group without performing A / D conversion by analog processing. A rotation angle detection error caused by a sampling error in D conversion can be eliminated.

(Third embodiment)
FIG. 12 is a block diagram of a rotation angle detection device 310 according to the third embodiment of the present invention.
The offset adjustment circuit 356, the first candidate pulse signal generation circuit 362, the AC coupling circuit 357, and the selection circuit 364 are mounted on the sensor chip 70.
Similarly to the offset adjustment circuit 56 according to the first embodiment, the offset adjustment circuit 356 serves as a first magnetic detection element group based on the offset between the Hall element 30 and the Hall element 31 acquired in a state where no magnetic field is generated. The offset between the Hall element 30 and the Hall element 31 is corrected. Accordingly, the offset adjustment circuit 356 can remove the offset between the Hall element 30 and the Hall element 31 regardless of the frequency of the output signal 100 of the Hall element 30 and the frequency of the output signal 101 of the Hall element 31, that is, the rotational speed of the detection target.
The first candidate pulse signal generation circuit 362 is substantially the same as the pulse signal generation circuit 62 according to the first embodiment. The first candidate pulse signal generation circuit 362 generates a first candidate pulse signal corresponding to the pulse signal generated by the pulse signal generation circuit 62 based on the numerical data that has been offset adjusted by the offset adjustment circuit 356.

The AC coupling circuit 357 corrects the offset of the second magnetic detection element group.
The second candidate pulse signal generation circuit 363 is substantially the same as the pulse signal generation circuit 262 according to the second embodiment. The second candidate pulse signal generation circuit 363 generates a second candidate pulse signal corresponding to the pulse signal generated by the pulse signal generation circuit 262 from the output signal of the second magnetic detection element group offset-adjusted by the AC coupling circuit 357. Generate. The AC coupling circuit 357 is a circuit with a small circuit scale that can be configured with a capacitor or the like as compared with the offset adjustment circuit 256 or the like according to the second embodiment. Therefore, the rotation angle detection device 310 can be reduced in size.

However, the AC coupling circuit 357 cannot correct the offset of the output signal of the second magnetic detection element group when the rotation speed of the detection target is low, as described in the section “Means for Solving the Problems”. .
Therefore, the selection circuit 364 selects one of the first candidate pulse signal and the second candidate pulse signal according to the rotation speed of the detection target, and outputs the selected one candidate pulse signal as a pulse signal. Specifically, the selection circuit 364 selects the first candidate pulse signal when the rotation speed of the detection target is equal to or lower than a predetermined speed, and selects the second candidate pulse signal when the rotation speed of the detection target is faster than the predetermined speed. . By selecting the first candidate pulse signal when the rotation speed of the detection target is slow, the first magnetic detection element group offset-corrected by the offset adjustment circuit 356 capable of offset adjustment even when the rotation angle of the detection target is slow is selected. The rotation angle of the detection target can be detected from the output signal. In addition, by selecting the second candidate pulse signal when the rotation speed of the detection target is high, the rotation angle detection error due to the sampling error described in the second embodiment can be eliminated.

(Fourth embodiment)
The rotation angle detection devices 410, 510, and 610 according to the fourth to sixth embodiments of the present invention, except for the sensor chip, are the rotation angle detection device 210 according to the second embodiment described above or the rotation angle detection according to the third embodiment. Substantially identical to device 310.
FIG. 13 is a schematic diagram showing the arrangement of the Hall elements mounted on the sensor chip according to the fourth embodiment of the present invention. FIG. 14 is a schematic diagram showing a comparative example.

  In the pulse generation processing described in the second embodiment, the number of angle candidates can be increased by increasing the number of Hall elements as the second magnetic detection element group and decreasing the angle formed by adjacent Hall elements. Specifically, for example, 18 Hall elements 430 to 447 as a comparative example shown in FIG. 14 are arranged on a circle 90 by rotating by 10 ° in the rotation direction of adjacent Hall elements and the detection target. By arranging 18 Hall elements 430 to 447 in this way, 36 angle candidates for every 10 ° can be set in the range of 0 ° to 360 °. However, as the number of angle candidates increases, the angle formed by adjacent Hall elements becomes smaller, so that it is not easy to form a wiring pattern related to the Hall elements.

Thus, in the sensor chip according to the fourth embodiment of the present invention, the Hall elements 439 to 447 of the comparative example described above are arranged so as to be moved point-symmetrically with respect to the central axis 20a of the yoke 20. Here, when the Hall element is moved point-symmetrically with respect to the central axis 20a of the yoke 20, the output signal of the Hall element after the movement becomes the inverted phase of the output signal of the Hall element before the movement. However, two sine waveforms (or cosine waveforms) whose phases are inverted have the same angle and an amplitude of zero. Therefore, if the pulse signal is generated in accordance with the sign change of the output signal level of the Hall element as in the pulse generation process described in the second embodiment, the output of the Hall element before the movement by the output signal of the Hall element after the movement The same angle candidate as the signal can be set. That is, the sensor chip according to the fourth embodiment can set 36 angle candidates every 10 ° in the range of 0 ° to 360 °, similarly to the sensor chip as the comparative example. In this way, adjacent Hall elements (except for Hall elements 430 and 447) can be arranged at positions rotated by 20 °.
It is desirable that the Hall elements as the first magnetic detection element group include Hall elements (for example, Hall elements 430 and 443) arranged at positions rotated by 90 ° relative to each other.

  According to the rotation angle detection device according to the fourth embodiment described above, the Hall elements are moved point-symmetrically with respect to the central axis 20 a of the yoke 20, and a large number of Hall elements are distributed on the circle 90. Accordingly, since a large number of Hall elements can be arranged with a large distance from the adjacent Hall elements, a wiring pattern related to the Hall elements can be easily formed. In addition, the overall chip size can be reduced.

(Fifth embodiment)
FIG. 15 is a schematic diagram showing the arrangement of Hall elements mounted on a sensor chip according to the fifth embodiment of the present invention.
The Hall elements 430 to 447 are arranged on a circle 90 and a circle 91 that are concentric with the central axis 20 a of the yoke 20. The Hall elements 430 to 438 are arranged on a circle 90 after being rotated by 20 ° in the rotation direction of the detection object with the adjacent Hall elements. Similarly, the Hall elements 439 to 447 are arranged on a circle 91 after being rotated by 20 ° in the rotation direction of the detection object with the adjacent Hall elements. The Hall elements 439 to 447 are rotated by 10 ° in the rotation direction of the detection target around the central axis 20a of the yoke 20 with respect to the Hall elements 430 to 438.
According to the rotation angle detecting device according to the fifth embodiment described above, a large number of Hall elements can be arranged with a large distance from adjacent Hall elements by dispersively arranging the multiple Hall elements on two circles. The wiring pattern related to the Hall element can be easily formed.

(Sixth embodiment)
FIG. 16 is a schematic diagram showing the arrangement of Hall elements mounted on the sensor chip according to the sixth embodiment of the present invention.
The Hall elements 430 to 438 and the Hall elements 439 to 447 are respectively formed in different layers of the sensor chip. The Hall elements 430 to 438 are formed in one layer of the sensor chip by rotating by 20 ° in the rotation direction of the detection object with the adjacent Hall elements. Similarly, the Hall elements 439 to 447 are formed in the other layers of the sensor chip by rotating by 20 ° in the rotation direction of the detection object with the adjacent Hall elements. The Hall elements 438 to 447 are rotated by 10 ° in the rotation direction of the detection target around the central axis 20a of the yoke 20 with respect to the Hall elements 430 to 438.
According to the rotation angle detection device according to the sixth embodiment described above, a large number of Hall elements can be arranged with a large distance from adjacent Hall elements by forming the Hall elements dispersed in two layers. Therefore, the wiring pattern related to the Hall element can be easily formed. Further, the overall chip size can be further reduced as compared with the fifth embodiment.

(Other embodiments)
In the plurality of embodiments described above, the Hall element is exemplified as the magnetic detection element. However, the magnetic detection element may be a magnetoresistive element or a giant magnetoresistive element.
In the first to third embodiments, the Hall elements as the first magnetic detection element group are described as the Hall elements 30 and 31, but two Hall elements as the first magnetic detection element group are provided. That's all.
In the second embodiment and the third embodiment, the Hall elements as the second magnetic detection element group are described as Hall elements 30 to 35. In the fourth to sixth embodiments, it has been described that the Hall elements as the second magnetic detection element group are the Hall elements 430 to 447. However, the number of Hall elements as the second magnetic detection element group may be two or more, and may not be six or eighteen.
In the above embodiments, the second magnetic detection element group (for example, the Hall elements 30 to 35) is described as including the Hall elements (for example, the Hall elements 30, 31) of the first magnetic detection element group. However, the first magnetic detection element group and the second magnetic detection element group may be composed of different Hall elements.

In the first embodiment, the Hall elements 30 and 31, the amplifier 52, the A / D converter 54, the offset adjustment circuit 56, the angle signal generation circuit 60, and the pulse signal generation circuit 62 are mounted on one sensor chip 70. As explained. However, the Hall elements 30, 31, the amplifier 52, the A / D converter 54, the offset adjustment circuit 56, the angle signal generation circuit 60, and the pulse signal generation circuit 62 may be mounted on a plurality of different chips in a predetermined combination. , All of which may be different parts. Similarly, in the second embodiment and the third embodiment, the plurality of components described as being mounted on the sensor chip 70 may be mounted on a plurality of different chips in a predetermined combination, or all of them may be mutually connected. Different parts may be used.
The offset adjustment circuit 256 according to the second embodiment may be an AC coupling circuit.

It is a block diagram of the rotation angle detection apparatus by 1st embodiment of this invention. It is a mimetic diagram of an ignition device for internal-combustion engines carrying a rotation angle detection device by a first embodiment of the present invention. (A) is a schematic diagram of the rotation angle detection apparatus by 1st embodiment of this invention, (B) is the sectional view on the AA line of (A). It is a figure which shows the relationship between a rotation angle and the output of a Hall element. It is a characteristic view which shows the relationship between a rotation angle and the calculation angle calculated | required by the inverse calculation of the trigonometric function from the output signal. It is a characteristic view which shows the relationship between a rotation angle and the output angle made into the period of 360 degrees. It is a figure which shows the relationship between the code | symbol of an output signal, and a rotation angle. It is a figure which shows the relationship between a rotation angle and a pulse signal. (A) is a schematic diagram of the rotation angle detection apparatus by 2nd embodiment of this invention, (B) is the BB sectional drawing of (A). It is a block diagram of the rotation angle detection apparatus by 2nd embodiment of this invention. (A) is a figure which shows the relationship between a rotation angle and the output of a Hall element. (B) is a figure which shows the relationship between a rotation angle and a pulse signal. It is a block diagram of the rotation angle detection apparatus by 3rd embodiment of this invention. It is a schematic diagram of the rotation angle detection apparatus by 4th embodiment of this invention. It is a schematic diagram of the rotation angle detection apparatus as a comparative example according to the fourth embodiment of the present invention. It is a schematic diagram of the rotation angle detection apparatus by 5th embodiment of this invention. It is a schematic diagram of the rotation angle detection apparatus by 6th embodiment of this invention.

Explanation of symbols

10, 210, 310, 410, 510, 610 Rotation angle detection device, 30, 31 Hall element (first magnetic detection element group, second magnetic detection element group), 32-35, 430-438 Hall element (second magnetic) Detection element group), 58 control unit (angle signal generation means, pulse signal generation means), 60 angle signal generation circuit (angle signal generation means), 62 pulse signal generation circuit (pulse signal generation means), 256 offset adjustment circuit, 262 Pulse signal generation circuit 356 Offset adjustment circuit (first correction means), 357 AC coupling circuit (second correction means), 362 First candidate pulse signal generation circuit (pulse signal generation means), 362 Second candidate pulse signal generation circuit (Pulse signal generating means), 364 selection circuit (pulse signal generating means)

Claims (8)

In the rotation angle detection device for detecting the rotation angle of the detection target,
Magnetic field generating means for generating a magnetic field;
Magnetic detection means that rotates relative to the magnetic field generation means by rotation of the detection target;
A plurality of magnetic detection elements provided in the magnetic detection means for outputting analog signals having different phase differences according to the magnetic field that is relatively changed by relative rotation of the magnetic detection means with respect to the magnetic field generation means; ,
An angle signal generation means for generating an analog angle signal indicating the rotation angle of the detection target from the output of the magnetic detection means;
Pulse signal generating means for generating a pulse signal whose signal level changes when the rotation angle of the detection target is one of a plurality of angle candidates from the output of the magnetic detection means;
A rotation angle detection device comprising: The angle signal generating means is a first magnetic detection composed of at least two magnetic detection elements installed such that the phase of the output signal of one magnetic detection element is different from the inverted phase of the output signal of the other magnetic detection element. The angle signal is generated by inverse calculation of a trigonometric function based on the output signal of the element group,
The pulse signal generation means changes the output signal level according to a comparison result between the output signal level of the second magnetic detection element group including at least two magnetic detection elements and a predetermined threshold value, thereby generating the pulse signal. The rotation angle detection device according to claim 1, wherein the rotation angle detection device is generated. A correction means for removing a direct current component of the output signal of the second magnetic detection element group;
3. The rotation angle detection device according to claim 1, wherein the pulse signal generation unit generates the pulse signal in accordance with an output signal level of the second magnetic detection element group after removal of a direct current component.   4. The rotation angle detecting device according to claim 3, wherein the correcting means is an AC coupling circuit. In the state where the magnetic field is not generated, the first magnetic detection element includes at least two magnetic detection elements installed so that the phase of the output signal of one magnetic detection element is different from the inverted phase of the output signal of the other magnetic detection element. First, an offset for removing a DC component is acquired based on an output signal of each magnetic detection element of one magnetic detection element group, and a DC component of an output signal of the first magnetic detection element group is removed based on the offset Correction means;
A second correction means for removing a direct current component of an output signal of the second magnetic detection element group comprising at least two magnetic detection elements by an AC coupling circuit;
The angle signal generation means generates the angle signal by inverse calculation of a trigonometric function based on the output signal of the first magnetic detection element from which a direct current component has been removed,
The pulse signal generation means changes the signal level according to the comparison result between the inverse calculation result of the trigonometric function based on the output signal of the first magnetic detection element from which the DC component is removed and the angle candidate. A candidate pulse signal is generated, and a second candidate pulse signal is generated by changing the output signal level according to the comparison result between the output signal level of the second magnetic detection element group from which the DC component is removed and a predetermined threshold value. The first candidate pulse signal is selected as the pulse signal when the rotation speed of the detection target is equal to or lower than a predetermined speed, and the second candidate pulse signal is selected as the pulse when the rotation speed of the detection target is higher than the predetermined speed. The rotation angle detection device according to claim 1, wherein the rotation angle detection device is selected as a signal.   6. The rotation angle detection according to claim 1, wherein the magnetism detection unit, the angle signal generation unit, and the pulse signal generation unit are mounted on one chip. apparatus.   The rotation angle detection device according to any one of claims 1 to 6, wherein the magnetic detection element is a Hall element.   The Hall elements are arranged concentrically with a virtual axis as a center, and each Hall element is installed so as to be different from a point-symmetrical position with respect to the virtual axis of the other Hall elements. The rotation angle detection device according to claim 7.

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