JP2007010449A - Rotation angle detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturizable rotation angle detection device capable of detecting highly accurately a rotation angle of a rotating magnetic field. <P>SOLUTION: This device is equipped with the first to fourth magnetoelectric devices 10a-10d arranged radially at about 90&deg; on a semiconductor substrate 1. The first to fourth magnetoelectric devices 10a-10d output sine wave signals having approximately the same period and approximately the same amplitude following rotation of the magnetic field. The first and third magnetoelectric devices 10a, 10c output the first sine wave signals 100a, 100c having approximately the same phase, and the second and fourth magnetoelectric devices 10b, 10d output the second sine wave signals 100b, 100d having approximately the same phase with a phase difference of about 1/4 wavelength with the first sine wave signals 100a, 100c. Arctangent operation and averaging operation are applied based on the first and second sine wave signals 100a-100d, and hereby the first and second sine wave signals 100a-100d are transformed into a detection signal displayed approximately linearly, to thereby detect the rotation angle &theta;. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating magnetic field using a magnetoelectric transducer that converts a rotating magnetic field change into an electric signal and outputs the change.

  A rotation angle detection device that detects a rotation angle of a magnetic field by detecting a change in a rotating magnetic field by a magnetoelectric conversion element and performing a predetermined calculation on an electric signal output from the magnetoelectric conversion element is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-2004. -271495 (patent document 1).

  FIG. 12 shows a concept in which the conventional rotation angle detection device 40 detects the rotation angle of the magnetic field B. As shown in FIG. 12A, the rotation angle detection device 40 has two magnetoelectric conversion elements 50 and 51. Further, the two magnetoelectric transducers 50 and 51 are arranged close to the rotation center P of the magnetic field B so as to output electrical signals having a phase difference of ¼ wavelength.

The rotation angle detection device 40 detects the magnetic field BB ′ rotated by the magnetoelectric conversion elements 50 and 51, performs a predetermined calculation on the electric signal output from the magnetoelectric conversion elements 50 and 51, and rotates the magnetic field BB ′. A corner is detected. In other words, the output terminals 50a-50b and 51a-51b of the two magnetoelectric transducers 50 and 51 receive a sinusoidal electric signal shown in FIG. Is output. Then, by applying a predetermined calculation process to these electric signals, the calculation result (sensor output voltage) shown in FIG. 12C is obtained, and the rotation angle of the magnetic field BB ′ can be detected.
JP 2004-271495 A

  Incidentally, the rotation angle detection device 40 shown in FIG. 12 does not take effective means for reducing or reducing noise generated by peripheral devices installed outside the rotation angle detection device 40. That is, when noise generated by a peripheral device or the like installed outside enters at least one of the electrical signals output from the magnetoelectric conversion elements 50 and 51, for example, as shown in FIG. If noise enters the electrical signal output from the element 51 when the rotation angle of the magnetic field is φ, this noise causes a sensor output error as shown in FIG. The detection accuracy may be reduced. Further, even when the magnetoelectric conversion elements 50 and 51 have different conversion characteristics with respect to the rotating magnetic field, it may cause a sensor output error and the detection accuracy of the rotation angle detection device 40 may be reduced.

  Therefore, the present invention has been made in view of the above-described problems, and the object of the present invention is to use a magnetoelectric transducer that converts a change in a rotating magnetic field into a change in an electric signal and outputs the change. Rotation angle detection device that detects the rotation angle, and errors caused by external peripheral devices, etc., variations in the manufacture of magnetoelectric transducers, placement positions of magnetoelectric transducers, differences in temperature distribution in the surrounding environment, etc. Is to provide a small rotation angle detection device with excellent detection accuracy of the rotation angle of the magnetic field.

  In order to solve the above-mentioned problem, a rotation detection device according to claim 1 uses a magnetoelectric conversion element that converts a change in a rotating magnetic field into a change in an electrical signal and outputs the change, thereby detecting a rotation angle of the magnetic field. A detection apparatus, comprising first to fourth magnetoelectric transducers arranged radially on the same semiconductor substrate at an interval of approximately 90 degrees, wherein the first to fourth magnetoelectric elements are accompanied by rotation of the magnetic field. The sine wave signal output by the conversion element is a sine wave signal having substantially the same period and substantially the same amplitude, and the first and third magnetoelectric conversion elements output the first sine wave signal having substantially the same phase. The second and fourth magnetoelectric transducers output a second sine wave signal having the same phase as that of the first sine wave signal and having a phase difference of approximately ¼ wavelength, and the first and second sine wave signals. Based on the wave signal, arc tangent calculation and averaging calculation are performed, and the first and second The sine wave signal is converted into a detection signal that appears almost linearly with respect to the rotation angle, and detects the rotation angle of the magnetic field.

  According to the first aspect of the present invention, when detecting the rotation angle of the rotating magnetic field, four magnetoelectric conversion elements having substantially the same conversion characteristics are arranged radially by 90 degrees. Then, even if noise from the outside enters the sine wave signal output from at least one magnetoelectric conversion element at a specific rotation angle, the averaging operation is performed based on the sine wave signal output from each magnetoelectric conversion element. For example, this noise is averaged together with the averaging of other sinusoidal signals into which noise has not entered. Thereby, the influence which noise has on the measurement result of a rotation detection apparatus can be reduced. Furthermore, offset caused by manufacturing variations of magnetoelectric conversion elements, arrangement positions of the magnetoelectric conversion elements, differences in temperature distribution in the surrounding environment, and the like can be reduced. In addition, as the magnetic field rotates, arc tangent calculation is performed based on the sine wave signal output by each magnetoelectric conversion element, so that the sine wave signal output by each magnetoelectric conversion element can be converted into a substantially linear detection signal, The rotation angle of the rotating magnetic field can be easily detected.

  The rotation detection device according to claim 2 performs an averaging operation based on the first and second sine wave signals, respectively, and an arc tangent operation based on the averaged first and second sine wave signals. And the averaged first and second sine wave signals are converted into detection signals displayed substantially linearly with respect to the rotation angle, and the rotation angle of the magnetic field is detected. As a result, since the sine wave signal can be averaged by performing an averaging operation based on the sine wave signal output from each magnetoelectric conversion element, variations in manufacture of the magnetoelectric conversion element, the arrangement position of the magnetoelectric conversion element, and the periphery Offset caused by differences in environmental temperature distribution can be reduced.

  In addition, arc tangent calculation is performed on the averaged sine wave signal, so the sine wave signal output by each magnetoelectric transducer is displayed in a substantially straight line with the effect of noise removed with a small calculation load. Can be converted into a detected signal.

  The rotation detection device according to claim 3 sets two sets of the first and second sine wave signals as one set, performs arctangent calculation in each set, and performs the first and second sine wave signals. Is converted into a detection signal displayed substantially linearly with respect to the rotation angle, and an averaging operation is performed based on the detection signal to detect the rotation angle of the magnetic field. As a result, in the calculation process of converting the sine wave signal output from each magnetoelectric conversion element into a detection signal displayed substantially linearly, the noise that has entered the sine wave signal is averaged. Therefore, it is possible to obtain a rotation angle detection device in which detection accuracy due to noise entering from the outside is unlikely to decrease.

  The rotation detection device according to claim 4 includes a plurality of sets of first to fourth magnetoelectric transducers, and alternately arranges the magnetoelectric transducers constituting different sets at predetermined intervals. The first and second sine wave signals are converted into detection signals that are displayed substantially linearly with respect to the rotation angle, and the phase difference of the detection signal is corrected based on the predetermined angle, and the phase difference is calculated. An averaging process is performed based on the corrected detection signal, and the rotation angle of the magnetic field is detected. As a result, by arranging at least two sets of four magnetoelectric transducers and eight at predetermined intervals, the sine wave signal output by at least one magnetoelectric transducer at a specific rotation angle is externally provided. Even if noise intrudes, the noise can be averaged based on the sine wave signals respectively output from the magnetoelectric transducers constituting each set. Further, by correcting the phase of the detection signal based on the interval (angle) of the magnetoelectric conversion elements, it is possible to disperse and average the intruding noise, so the influence of the noise on the measurement result of the rotation detection device Can be further reduced. Therefore, it is possible to obtain a rotation angle detection device with better detection accuracy.

  The rotation angle detection device according to claim 5 is characterized in that the magnetoelectric conversion element is a vertical Hall element. Thus, unlike the case where a magnetoresistive element (MRE) is used as the magnetoelectric conversion element, it is not necessary to install a bias magnet for each of the magnetic conversion elements, so that the rotation detecting device can be downsized.

  Hereinafter, the best mode for carrying out the present invention will be described. In the present invention, a Hall element is used as the magnetoelectric conversion element. Therefore, first, the Hall element will be briefly described with reference to FIG. FIGS. 11A and 11B are diagrams showing the operation principle of a general Hall element. The Hall effect of the semiconductor is that when there is a carrier flow in a conductor (Hall element 20) placed so as to be orthogonal to the magnetic flux B, an electromotive force (Hall voltage) in a direction perpendicular to both the magnetic field B and the carrier flow. ).

  As shown in FIG. 11 (a), when the thickness of the Hall element 20 is d and the current I is applied between the terminals Ti, when the magnetic field B orthogonal to the Hall element 20 is applied, between the output terminals Tv. The generated output voltage (Hall voltage) is VH. At this time, the expression (1) in the figure is established. In the formula (1), Rh is a Hall coefficient, which is a value determined by the material of the Hall element 20.

  As shown in FIG. 11B, when the magnetic field rotates and the angle (rotation angle θ) between the surface direction of the Hall element 20 and the magnetic field B changes, the output voltage VH is expressed by the equation (2) in the figure. It changes to an equation multiplied by cos θ. Therefore, as shown in FIG. 11B, when the Hall element 20 is arranged between the N and S magnets and the magnet or the Hall element 20 is rotated, the output voltage output from the Hall element 20 is sine. It becomes a wave shape. The rotation angle θ of the rotating magnetic field B can be detected using this sine wave shaped output voltage.

  FIGS. 11C and 11D are diagrams showing an example of a Hall element classified as a vertical Hall element. FIG. 11C is a top view of the vertical Hall element 22, and FIG. ) Is a sectional view taken along the line DD in FIG. A vertical Hall element 22 shown in FIGS. 11C and 11D is a Hall element in which a hole plate portion is formed perpendicular to the surface of the semiconductor substrate 1 and carriers flow in the vertical direction on the surface of the semiconductor substrate 1. The vertical Hall element 22 is a junction-separated vertical Hall element, and an n-type low-concentration diffusion layer (n−) 2 is separated by a p-type high-concentration layer 4b.

  As shown by the dotted arrows in FIG. 11D, the carriers are perpendicular to the surface of the semiconductor substrate 1 between the terminals Ti0 and Ti1 and between the terminals Ti0 and Ti2 via the n-type high concentration buried layer 4u. Flowing into. It is to be noted that the hall plate portion 2t in the center operates as an element, and an output voltage (Hall voltage) VH generated by a magnetic field orthogonal to the hall plate portion 2t is detected between the terminals Tv.

  The above is an example of the vertical Hall element, and not only the structure shown in FIGS. 11C and 11D but also various structures can be taken. For example, the n-type high-concentration buried layer 4u may be eliminated, and carriers flowing out from the terminal Ti0 may reach the terminals Ti1 and Ti2 so as to go around the tip of the p-type high-concentration layer 4b. Further, not the junction isolation by the p-type high concentration layer 4b but the trench isolation may be used. Furthermore, in the vertical Hall element 12 shown in FIGS. 11C and 11D, terminals Ti1 and Ti2 are provided so that carriers flowing out from the terminal Ti0 flow on both the left and right sides of the figure, but only on one side. There may be.

(First embodiment)
A rotation angle detection device 30 according to a first embodiment of the present invention will be described with reference to FIGS. Note that the vertical Hall element described in FIG. 11 can be used as the magnetoelectric conversion element. Therefore, description will be made assuming that the magnetoelectric conversion element is a vertical Hall element.

  As shown in FIG. 1, it is assumed that a magnetic field B (indicated by a thin arrow) to be detected rotates in a direction indicated by a thick arrow so as to become a magnetic field B ′ (indicated by a dashed arrow). Note that the magnetic fields B and B 'are both directional vectors, and their directions are the directions indicated by the arrows.

  As shown in FIG. 1, the rotation angle detection device 30 according to the present embodiment has first to fourth vertical Hall elements 10a to 10a each having substantially the same conversion characteristics with respect to changes in the rotating magnetic field BB ′. 10d and arranged radially on the same semiconductor circuit board 1 in the order of 10a to 10d so as to have an interval of approximately 90 degrees.

  The first to fourth vertical Hall elements 10a to 10d arranged in this way convert the change of the rotating magnetic field BB 'into sine wave signals 100a to 100d having substantially the same period and substantially the same amplitude. Output. Then, the rotation angle detection device 30 performs an averaging operation and an arctangent operation, which will be described later, by a signal processing circuit (not shown) based on the sine wave signals 100a to 100d, and rotates the sine wave signals 100a to 100d. The rotation angle θ of the magnetic field BB ′ is detected by converting it into a detection signal 15 displayed substantially linearly with respect to the rotation angle θ of the magnetic field BB ′. The signal processing circuit described above may be arranged on the semiconductor circuit board 1 together with the first to fourth vertical Hall elements 10a to 10d, or the semiconductor circuit board 1 on which the vertical Hall element is formed and May be arranged on another semiconductor circuit board.

  By the way, although the relationship between the change of the magnetic field and the current flowing through the vertical Hall element has been described with reference to FIGS. 11A to 11D, the first to fourth vertical Hall elements 10a to 10d are substantially the same. It arrange | positions so that it may become radial at intervals of 90 degree | times, and it arrange | positions so that the direction of the electric current which flows through these vertical Hall elements may become the same direction with rotation of a magnetic field. Then, the voltages output from the first to fourth vertical Hall elements 10a to 10d are out of phase by ¼ wavelength (90 degrees) in the order of the sine wave signals 100a, 100b, 100c, and 100d.

  That is, there is approximately a half wavelength (180 degrees) between the sine wave signal 100a output from the first vertical Hall element 10a and the sine wave signal 100c output from the third vertical Hall element 10c. A phase difference will occur. The sine wave signal 100b output from the second vertical Hall element 10b and the sine wave signal 100d output from the fourth vertical Hall element 10d are approximately ½ wavelength (180 degrees). A phase difference will occur.

  However, in the rotation angle detection device 30 in the present embodiment, as shown in FIG. 2A, the sine wave signal 100a output from the first vertical Hall element 10a and the third vertical Hall element 10c output. The direction of the current flowing through the first vertical Hall element 10a and the third vertical Hall element so as to be a sine wave signal (first sine wave signal) having no phase difference with the sine wave signal 100c. The first vertical Hall element 10a and the third vertical Hall element 10c are arranged so that the direction of current flowing through 10c is opposite.

  Further, as the magnetic field rotates, there is no sine phase difference between the sine wave signal 100b output from the second vertical Hall element 10b and the sine wave signal 100d output from the fourth vertical Hall element 10d. The direction of the current flowing through the second vertical Hall element 10b is opposite to the direction of the current flowing through the fourth vertical Hall element 10d so that a wave signal (second sine wave signal) is obtained. The second vertical Hall element 10b and the fourth vertical Hall element 10d are arranged.

  When the vertical Hall elements 10a to 10d are arranged in this manner, as shown in FIG. 2A, between the first sine wave signal and the second sine wave signal (between the sine wave signals 100a and 100b). The phase difference between the sine wave signals 100c and 100d) is ¼ wavelength (90 degrees).

  As can be seen from FIG. 2 (a), the sine wave signals 100a and 100c and the sine wave signals 100b and 100d are substantially in phase, but as indicated by the solid and broken lines in FIG. 2 (a). The waveforms may not be perfectly matched due to offsets caused by manufacturing variations of vertical Hall elements, slight deviations in the arrangement position on the semiconductor substrate 1, temperature differences in the surrounding environment, and the like. Further, when the rotation angle φ (0 ° ≦ φ <360 °) of the magnetic field BB ′, the noise 4 may enter the sine wave signal 100a output from the vertical Hall element 10a. Such offset and noise 4 may cause a measurement error of the rotation angle detection device 30.

  Therefore, the rotation angle detection device 30 in the present embodiment performs a calculation described later based on the sine wave signal output by each vertical Hall element when detecting the rotation angle θ of the rotating magnetic field BB ′. The offset and noise are reduced, and the rotation angle θ of the magnetic field BB ′ is accurately detected.

  In order to accurately detect the rotation angle θ of the rotating magnetic field BB ′, the rotation angle detecting device 30 firstly has a first sine wave signal 100a indicated by a solid line and a first broken line indicated by a broken line in FIG. An averaging operation is performed based on the 1 sine wave signal 100c. Further, an averaging operation is performed based on the second sine wave signal 100b indicated by a solid line and the second sine wave signal 100d indicated by a broken line in FIG.

  By this averaging operation, the averaged first sine wave signal 100ac and the averaged second sine wave signal 100bd are calculated. It is possible to reduce offset due to manufacturing variations of the respective magnetoelectric conversion elements, arrangement positions of the magnetoelectric conversion elements, differences in temperature distribution of the surrounding environment, and the like, and noise 4 at the rotation angle φ remaining in the sine wave signal 100a is This averaging operation averages the noise 4a, and its influence is reduced.

  Next, arc tangent calculation is performed based on the averaged first sine wave signal 100ac and the averaged second sine wave signal 100bd. Then, the averaged first sine wave signal 100ac and the averaged second sine wave signal 100bd are substantially linearly detected with respect to the rotation angle θ of the rotating magnetic field BB ′. Converted into (sensor output voltage). FIG. 3 shows this detection signal 15. The noise 4 at the rotation angle φ remains in the detection signal 15 as noise 4a, but the influence of the noise 4a on the detection signal 15 is reduced compared to the noise 4.

  Then, the rotation detection device 30 in the present embodiment detects the rotation angle θ of the rotating magnetic field BB ′ based on the detection signal 15 displayed substantially linearly.

(Second Embodiment)
The rotation angle detection device 31 according to the second embodiment of the present invention performs a calculation in an order different from the calculation order described in the first embodiment, and detects the rotation angle θ of the rotating magnetic field BB ′. It is. In the rotation angle detection device 31 according to this embodiment, the magnetoelectric conversion element is assumed to be a vertical Hall element and will be described with reference to FIGS. 4 and 5. The arrangement of the first to fourth vertical Hall elements 10a to 10d is the same as that of the first embodiment.

  In other words, the first to fourth vertical Hall elements 10a to 10d are arranged radially in the order of 10a to 10d so as to have an interval of about 90 degrees. In this arrangement, the first vertical Hall elements are arranged. The sine wave signal 100a output from the 10a and the sine wave signal 100c output from the third vertical Hall element 10c are arranged so as to be a sine wave signal (first sine wave signal) having no phase difference. In addition, a sine wave signal (second sine wave) having no phase difference between the sine wave signal 100b output from the second vertical Hall element 10b and the sine wave signal 100d output from the fourth vertical Hall element 10d. (Wave signal). Note that the sine wave signals 100a to 100d have substantially the same period and substantially the same amplitude.

  At this time, as shown in FIG. 4A, a sine wave signal 100a (first sine wave signal) output from the first vertical Hall element 10a and a sine wave output from the second vertical Hall element 10b. The phase difference from the signal 100b (second sine wave signal) is ¼ wavelength (90 degrees). Further, as shown in FIG. 4B, a sine wave output from the sine wave signal 100c (first sine wave signal) output from the third vertical Hall element 10c and the fourth vertical Hall element 10d. The phase difference between the signal 100d (second sine wave signal) is ¼ wavelength (90 degrees).

  Therefore, the rotation angle detection device 31 in the present embodiment sets two sets of the first sine wave signal and the second sine wave signal as one set when detecting the rotation angle θ of the magnetic field BB ′. That is, the sine wave signal 100a (first sine wave signal) and the sine wave signal 100b (second sine wave signal) shown in FIG. 4 (a) are paired, and the sine wave shown in FIG. 4 (b). The signal 100c (first sine wave signal) and the sine wave signal 100d (second sine wave signal) are taken as a set.

  In each set, arctangent calculation is performed. Then, as shown in FIG. 5A, the first sine wave signal 100a, the second sine wave signal 100b, the first sine wave signal 100c, and the second sine wave signal 100d are displayed almost linearly. Converted into detection signals 16 and 17, respectively. At this time, the noise 4 that has entered the sine wave signal 100a at the rotation angle φ remains in the detection signal 16 at a substantially unchanged noise level.

  Subsequently, an averaging operation is performed based on the detection signals 16 and 17. Then, as shown in FIG. 5B, the detection signal 18 (sensor output voltage) displayed in a substantially straight line is calculated with respect to the rotation angle θ of the rotating magnetic field BB ′. This averaging operation can reduce the offset caused by manufacturing variation of each magnetoelectric conversion element, the arrangement position of the magnetoelectric conversion element, the temperature distribution difference in the surrounding environment, and the like, and the rotation angle remaining in the voltage signal 16. The noise 4 in φ is averaged into the noise 4a, and the influence on the detection signal 18 is reduced.

  The rotation detection device 31 in the present embodiment detects the rotation angle θ of the rotating magnetic field BB ′ based on the detection signal 18 displayed on the substantially straight line.

(Third embodiment)
The rotation angle detection device 32 according to the third embodiment of the present invention has two sets of first to fourth vertical Hall elements each having substantially the same conversion characteristics with respect to changes in the rotating magnetic field BB ′. 10a to 10d (first set) and 11a to 11d (second set) are provided to detect the rotation angle θ of the rotating magnetic field BB ′. In the rotation angle detection device 32 in the present embodiment, the magnetoelectric conversion element is assumed to be a vertical Hall element and will be described with reference to FIGS. Note that the arrangement of the first to fourth vertical Hall elements 10a to 10d and 11a to 11d in the first and second sets is the same as that of the first and second embodiments.

  That is, the first to fourth vertical Hall elements 10a to 10d and 11a to 11d are arranged radially in the order of 10a to 10d and 11a to 11d so as to have an interval of approximately 90 degrees. As shown in FIG. 4, the vertical Hall elements constituting different sets are arranged so as to be staggered at equal intervals (for example, in the order of 10a, 11a, 10b, 11b...). Accordingly, the interval between adjacent vertical Hall elements is approximately 45 degrees.

  In this arrangement, in the first set, as shown in FIG. 7A, the sine wave signal 100a output from the first vertical Hall element 10a and the sine wave signal output from the third vertical Hall element 10c. The sine wave signal 100b and the fourth vertical type output from the second vertical Hall element 10b are arranged so as to be a sine wave signal (first sine wave signal) having no phase difference with respect to 100c. It arrange | positions so that it may become a sine wave signal (2nd sine wave signal) without a phase difference between the sine wave signals 100d which Hall element 10d outputs.

  In the second set, as shown in FIG. 7B, a sine wave signal 110a output from the first vertical Hall element 11a and a sine wave signal 110c output from the third vertical Hall element 110c. The sine wave signal 110b output from the second vertical Hall element 11b and the fourth vertical Hall element are arranged so as to be a sine wave signal (first sine wave signal) having no phase difference between them. The sine wave signal 110d output by 11d is arranged to be a sine wave signal (second sine wave signal) having no phase difference. Note that the sine wave signals 100a to 100d and 110a to 110d have substantially the same period and substantially the same amplitude.

  The rotation angle detection device 32 corrects the phase, which will be described later, by a signal processing circuit (not shown) based on the first to fourth sine wave signals 100a to 100d and 110a to 110d of the first and second sets. The arc tangent calculation and the averaging calculation are performed to convert the sine wave signals 100a to 100d and 110a to 110d into a detection signal 27 displayed almost linearly with respect to the rotation angle θ of the rotating magnetic field BB ′. The rotation angle θ of the magnetic field BB ′ is detected.

  By the way, as can be seen from FIGS. 7A and 7B, the sine wave signal 100a and sine wave signal 100c which are the first sine wave signals, the second sine wave signal 100b and 100d, and the first sine wave. The wave signals 110a and 110c and the second sine wave signals 110b and 110d are sine wave signals having substantially the same phase, but are indicated by solid lines and broken lines in FIGS. 7 (a) and 7 (b). As described above, the waveform may not completely match due to the offset caused by the manufacturing variation of the vertical Hall element, the slight displacement of the arrangement position on the semiconductor substrate 1, the difference in the temperature distribution of the surrounding environment, and the like. . Further, as shown in FIG. 7A, the noise 4 enters the sine wave signal 100a output from the vertical Hall element 10a when the rotation angle φ (0 ° ≦ φ <360 °) of the magnetic field BB ′. Sometimes. Such offset and noise 4 may cause measurement errors of the rotation angle detection device 32.

  Therefore, the rotation angle detection device 32 performs the calculation described below on the basis of the sine wave signal output by each vertical Hall element when detecting the rotation angle θ of the rotating magnetic field BB ′, and thus the offset and The noise 4 is reduced and the rotation angle θ of the rotating magnetic field BB ′ is detected more accurately.

  The rotation angle detection device 32 performs an averaging operation on each of the sine wave signal 100a, the sine wave signal 100c, the sine wave signal 100b, and the sine wave signal 100d, and averages them as shown in FIG. The sine wave signal 100ac and the averaged sine wave signal 100bd are calculated. Further, the sine wave signal 110a, the sine wave signal 110c, the sine wave signal 110b, and the sine wave signal 110d are averaged, and the averaged sine wave signal 110ac shown in FIG. The averaged sine wave signal 110bd is calculated.

  At this time, there is a phase difference of ¼ wavelength (90 degrees) between the averaged sine wave signal 100ac and the averaged sine wave signal 100bd. Further, there is a phase difference of ¼ wavelength (90 degrees) between the averaged sine wave signal 110ac and the averaged sine wave signal 110bd. In addition, this averaging calculation can reduce offset caused by manufacturing variations of the respective magnetoelectric conversion elements, arrangement positions of the magnetoelectric conversion elements, differences in temperature distribution in the surrounding environment, and the like, and remains in the sine wave signal 100a. The noise 4 at the rotation angle φ is averaged into the noise 4a, and its influence is reduced.

  Next, following the above-described averaging calculation, arctangent calculation is performed based on the averaged sine wave signal 100ac and the averaged sine wave signal 100bd, and is approximately shown in FIG. The detection signal 25 is displayed in a straight line. At this time, the averaged noise 4a remains in the detection signal 25 at a substantially unchanged noise level. Further, arc tangent calculation is performed based on the averaged sine wave signal 110ac and the averaged sine wave signal 110bd, and the detection signal 26 displayed in a substantially straight line as shown in FIG. Convert.

  By the way, since the rotation angle detection device 32 arranges the vertical Hall elements constituting different sets so as to keep the same interval, the interval between the adjacent vertical Hall elements is almost equal. 45 degrees. Therefore, the detection signal 25 calculated based on the vertical Hall elements 10a to 10d constituting the first set, and the detection signal 26 calculated based on the vertical Hall elements 11a to 11d constituting the second set; In between, there is a phase difference of 1/8 wavelength (45 degrees).

  Therefore, in order to eliminate the phase difference between the detection signal 25 and the detection signal 26, for example, the detection signal 26 is 1/8 wavelength (45 degrees) in the direction of the arrow shown in FIG. The moving phase is corrected. By performing this correction, the phase difference between the detection signal 25 and the detection signal 26 is eliminated.

  Then, an averaging operation is performed based on the detection signals 25 and 26 from which the phase difference has been eliminated. Then, the detection signal 27 (sensor output voltage) displayed almost linearly with respect to the rotation angle θ of the rotating magnetic field BB ′ can be obtained. FIG. 9B shows the detection signal 27.

  The rotation detection device 32 can detect the rotation angle θ of the magnetic field BB ′ based on the detection signal 27. The noise 4a remaining in the detection signal 25 is averaged to the noise 4b by the averaging calculation based on the detection signals 25 and 26. Therefore, the noise 4b is transferred to the detection signal 27 as compared with the noise 4. The effect is further reduced.

(Other embodiments)
In the first and second embodiments, the rotation angle detection devices 30 and 31 having four vertical Hall elements, and in the third embodiment, the rotation angle detection device 32 having eight vertical Hall elements. Explained.

  However, the present invention is also effective as a rotation angle detection device in which the number of vertical Hall elements is further increased. For example, as shown in FIG. 10, the rotation angle detection device 33 includes three sets of vertical Hall elements having substantially the same conversion characteristics, and 12 sets (10a to 10d, 11a to 11d, and 12a to 12d) in different sets. May be arranged so that the interval between adjacent vertical Hall elements is approximately 30 degrees, so that the vertical Hall elements constituting the same are maintained at equal intervals.

  Thus, by arranging three sets of vertical Hall elements, the rotation angle detection device 33 is caused by manufacturing variations of the vertical Hall elements, slight deviations in the arrangement position, differences in temperature distribution in the surrounding environment, and the like. Offset can be further reduced. In addition, even if noise enters the sine wave signal output from the vertical Hall element, this noise is averaged during the averaging calculation process, and measurement errors due to noise can be reduced. It can be set as a rotation angle detection apparatus.

  Although the best mode for carrying out the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. is there. In the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted.

3 is a schematic top view of rotation angle detection devices 30 and 31. FIG. It is a figure which shows the relationship between the rotation angle (theta) of rotating magnetic field BB ', and the sine wave signal (Hall voltage) which a vertical Hall element outputs in the rotation angle detection apparatus 30, (a) is the vertical Hall element 10a. FIG. 10B is a diagram illustrating the sine wave signals 100a to 100d output from the first sine wave signal 100a and the second sine wave signal 100b and 100d. It is a figure which shows 100 sine wave signal 100bd. It is the figure which converted the averaged 1st, 2nd sine wave signal 100ac and 100bd in the rotation angle detection apparatus 30 into the straight line. It is a figure which shows the relationship between rotation angle (theta) of the rotating magnetic field BB ', and the sine wave signal (Hall voltage) which a vertical Hall element outputs in the rotation angle detection apparatus 31, (a) is the vertical Hall element 10a. 10B is a diagram illustrating sine wave signals (Hall voltages) 100a and 100b output from 10b, and FIG. 10B is a diagram illustrating sine wave signals (Hall voltages) 100c and 100d output from vertical Hall elements 10c and 10d. It is the figure which converted the 1st and 2nd sine wave signal 100a, 100c and 100b, 100d in the rotation angle detection apparatus 31 into the straight line, (a) is the 1st sine wave signal 100a and the 2nd sine wave. FIG. 5B is a diagram in which the set of the signal 100b and the set of the first sine wave signal 100c and the second sine wave signal 100d are converted into straight lines 16 and 17 for each set, and FIG. FIG. It is a typical top view of rotation angle detection device 32 in a 3rd embodiment. It is a figure which shows the relationship between rotation angle (theta) of rotating magnetic field BB ', and the sine wave signal (Hall voltage) which a vertical Hall element outputs in the rotation angle detection apparatus 32, (a) is vertical Hall element 10a-. The figure which shows the sine wave signal which 10d outputs, (b) is a figure which shows the sine wave signal which the vertical Hall elements 11a-11d output. It is the wave form diagram obtained by performing the averaging calculation based on the in-phase sine wave signal in the rotation angle detection apparatus 32, (a) is based on the sine wave signal which the vertical Hall elements 10a-10d output. FIG. 5B is a waveform diagram in which the averaging calculation is performed based on the sine wave signals output from the vertical Hall elements 11a to 11d.

It is a figure which shows the relationship between rotation angle (theta) of the rotating magnetic field BB ', and the electrical signal (Hall voltage) which a vertical Hall element outputs in the rotation angle detection apparatus 32, (c) is vertical Hall elements 12a-12d. It is a figure which shows the electric signal which outputs.
FIG. 7 is a diagram illustrating a detection signal calculated by performing an arctangent calculation based on the first sine wave signal and the second sine wave signal in the rotation angle detection device 32, and FIG. , 26 is a diagram showing a change in the detection signal 27, and FIG. 7B is a diagram showing the detection signal 27 calculated by performing an averaging operation based on the detection signals 25, 26. The typical top view of rotation angle detection device 33 in other embodiments. It is a figure which shows an example of a Hall element, (a) And (b) is a figure which shows the principle of operation of a general Hall element, (c) is a top view of a vertical Hall element, (d) is in (c). It is DD sectional drawing. In the schematic diagram of the conventional rotation angle detection device, (a) is a top view of the rotation angle detection device, (b) is a waveform diagram when noise has entered the electrical signal output from the magnetoelectric transducer, (c), It is the figure which showed the calculation result obtained by performing a predetermined calculation with respect to the electric signal which a magnetoelectric conversion element outputs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Low concentration diffused layer, 4, 4a, 4b ... Noise, 10a-10d, 11a-11d, 12a-12d, 20, 22 ... Vertical Hall element (magnetoelectric conversion element), 15, 16, 17, 18, 25, 26, 27 ... detection signal, 30, 31, 32, 33, 40 ... rotation angle detector, 50, 51 ... magnetoelectric transducer, 50a, 50b, 51a, 51b ... output terminal, 100a to 100d , 110a to 110d ... sine wave signal, 100ac, 110ac ... first averaged sine wave signal, 100bd, 110bd ... second averaged sine wave signal

Claims (5)

A rotation angle detection device that detects a rotation angle of the magnetic field using a magnetoelectric conversion element that converts a change in a rotating magnetic field into a change in an electric signal and outputs the change.
Comprising first to fourth magnetoelectric transducers arranged radially on the same semiconductor substrate at intervals of approximately 90 degrees;
A sine wave signal output from the first to fourth magnetoelectric transducers with the rotation of the magnetic field is a sine wave signal having substantially the same period and substantially the same amplitude, and the first and third magnetoelectric signals. The conversion element outputs a first sine wave signal having substantially the same phase, and the second and fourth magnetoelectric conversion elements have a phase difference of approximately ¼ wavelength with respect to the first sine wave signal. Outputs a second sine wave signal of the same phase,
Based on the first and second sine wave signals, arc tangent calculation and averaging calculation are performed, and the first and second sine wave signals are displayed substantially linearly with respect to the rotation angle. A rotation angle detection device that converts the detection signal into a detection signal and detects the rotation angle of the magnetic field. Based on the first and second sine wave signals, respectively, the averaging operation is performed,
Based on the averaged first and second sine wave signals, the arc tangent calculation is performed, and the sine wave signals output by the first to fourth magnetoelectric transducers are expressed with respect to the rotation angle. The rotation angle detection device according to claim 1, wherein the rotation angle of the magnetic field is detected by converting the detection signal into a substantially linear display. Two sets of the first and second sine wave signals are set as one set,
In each set, the arc tangent calculation is performed to convert the first and second sine wave signals into two sets of the detection signals displayed substantially linearly with respect to the rotation angle,
The rotation angle detection device according to claim 1, wherein the averaging calculation is performed based on two sets of the detection signals to detect a rotation angle of the magnetic field. A plurality of sets of the first to fourth magnetoelectric transducers are provided,
The magnetoelectric transducers constituting different sets are alternately arranged at predetermined intervals,
For each set, the first and second sine wave signals are converted into the detection signal displayed substantially linearly with respect to the rotation angle;
Based on the predetermined angle, the phase difference of the detection signal is corrected,
The rotation angle detection device according to claim 1, wherein the rotation angle of the magnetic field is detected by performing an averaging process based on the detection signal in which the phase difference is corrected.   The rotation angle detection device according to claim 1, wherein the magnetoelectric conversion element is a vertical Hall element.

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