JP2009198316A - Rotation detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detection device capable of preventing erroneous detection of rotation, when detecting rotation of a rotator. <P>SOLUTION: This rotation detection device 10 includes a comparator 43 for outputting an output signal Cm<SB>2</SB>corresponding to a difference between the second threshold voltage set on the periphery of an amplitude center of a differential output signal Vm output from an operation amplifier 41 and the differential output signal Vm, a comparator 42 for outputting an output signal Cm<SB>1</SB>corresponding to a difference between the first threshold voltage set to be higher than the second threshold voltage and the differential output signal Vm, and a comparator 44 for outputting an output signal Cm<SB>3</SB>corresponding to a difference between the third threshold voltage set to be lower than the second threshold voltage and the differential output signal Vm. The rotation detection device 10 detects a rotational position of a rotor R based on the output signal Cm<SB>2</SB>by a signal processing circuit 48, and determines whether the possibility of including an abnormal signal in the output signal C<SB>2</SB>is strong or not, based on output progress of the output signal Cm<SB>2</SB>with the output signal Cm<SB>1</SB>and the output signal Cm<SB>3</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotation detection device capable of detecting rotation of a rotating body.

As a rotation detection device capable of detecting the rotation of a rotating body, for example, there is a “rotation detection device” disclosed in Patent Document 1 below. In this type of rotation detection device, a bias magnet is used to generate a bias magnetic field toward the gear teeth of the rotating body, and the gear "mountains" (gear teeth convex) and gear "valleys" (gear teeth) Detecting the direction of the magnetic field that changes based on the change of “mountain” → “valley” and “valley” → “mountain” by the recess) with a sensor having two magnetoresistive elements (MRE) with different phases of the output signal Thus, the position of such gear teeth, that is, the rotational position of the rotating body can be detected.
Japanese Patent Laid-Open No. 11-237256

FIG. 12 is a graph showing the relationship between the differential output signal output from the operational amplifier and the comparator output signal output from the comparator in response to the differential output signal. FIG. 12B shows the relationship between the dynamic output signal and the comparator output signal, FIG. 12B shows the relationship between the differential output signal and the comparator output signal when a missing pulse occurs, and FIG. 12C shows the case where an erroneous pulse occurs. The relationship between the differential output signal and the comparator output signal is shown.
By the way, when both signals output from both MREs of the sensor according to the rotation of the rotating body are input to the operational amplifier, a differential output signal corresponding to the difference between the two signals is output from the operational amplifier to the comparator. In the comparator, a differential output signal input from the operational amplifier is compared with a predetermined threshold voltage Vth to generate a pulsed output signal (see FIG. 12A).

  However, for example, when the gap (distance) between the sensor and the rotating body increases due to secular change or the like, the change in the magnetic field direction described above decreases, and the amplitude value of the differential output signal output from the operational amplifier may decrease. is there. Further, for example, a differential output signal output from the operational amplifier may move (offset) in the amplitude direction due to endurance fluctuations such as a sensor or an operational amplifier.

  As shown in FIG. 12B, for example, when the amplitude value of the differential output signal becomes small, an L-level output pulse signal is output at the rotation angle at which the H-level output signal should be output. This may cause missing pulses. Also, as shown in FIG. 12C, for example, when the differential output signal is offset in the amplitude direction, an H level output signal is output at the rotation angle at which an L level output pulse signal should be output. There is a possibility that an erroneous pulse is generated. In particular, if such erroneous rotation detection such as missing pulses or erroneous pulses occurs in a crank sensor that detects the rotation of the crankshaft of the engine, the engine behavior may become unstable.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotation detection device capable of preventing erroneous rotation detection when detecting the rotation of a rotating body. .

In order to achieve the above object, in the rotation detection device according to claim 1, a magnetic field is generated toward the gear teeth (T) of the rotating body (R) having the gear-shaped gear (G). And a gear (30) that is arranged along a virtual straight line (K2) perpendicular to the magnetic center axis of the magnet between the gear and the magnet, and that rotates with the rotation of the rotating body Two magnetic sensors (20, 21, 22) that respectively output sensor signals whose voltages vary based on the magnetic field that changes due to tooth movement, and two sensor signals that are output at different phases from the two magnetic sensors A differential amplifier (41) that amplifies and outputs a differential output signal (Vm) corresponding to the difference between the first threshold voltage (Vth ₂ ) set near the amplitude center of the differential output signal, and Two depending on the difference with the differential output signal No. (Cm ₂₎ first comparator for outputting the one of the (43), different with respect to the voltage value smaller by the voltage value of the first threshold voltage than that corresponding to the amplitude value of the differential output signal The second comparator that outputs one of the two signals (Cm ₁ , Cm ₃ ) according to the difference between the second threshold voltage (Vth ₁ , Vth ₃ ) set as described above and the differential output signal (42, 44), a rotation position detecting means (48) for detecting a rotation position of the rotating body based on a signal output from the first comparator, and a signal output from the first comparator Occurrence determination means for determining whether or not there is a high possibility that an abnormal signal is included in the signal output from the first comparator based on the output progress of the signal output from the second comparator (48) is provided as a technical feature.

In the rotation detection device according to claim 2, the abnormality detection unit is changed for each change in the signal output from the first comparator in the rotation detection device according to claim 1. The first accumulated value (N ₂ ) in which the number of times is accumulated and the second accumulated value (N ₁ , N ₃ ) in which the number of changes is accumulated for each change in the signal output from the second comparator. When the difference is 2 or more, it is technically characterized to determine that there is a high possibility that an abnormal signal is included in the signal output from the first comparator.

  In the rotation detection device according to claim 3, the abnormality occurrence determination means is characterized in that the abnormality occurrence determination means includes the signal output from the first comparator and the second output. When one of the signals output from the comparator does not change and the other changes three or more times, the signal output from the first comparator is highly likely to contain an abnormal signal. Judgment is a technical feature.

  In the rotation detection device according to claim 4, the rotation detection device according to any one of claims 1 to 3, wherein the abnormality occurrence determination means outputs the rotation detection device from the first comparator. Differential output signal correction for offsetting the differential output signal so that the amplitude center of the differential output signal approaches the second threshold voltage when it is determined that the signal is likely to contain an abnormal signal It is a technical feature that means is provided.

In the rotation detection device according to claim 5, the voltage value corresponding to the amplitude value of the differential output signal is used instead of the second comparator in the rotation detection device according to claim 1. Of the two signals (Cm ₁ ) depending on the difference between the upper threshold voltage (Vth ₁ ) set to be larger than the first threshold voltage by a smaller voltage value and the differential output signal. A third comparator (42) for outputting one of them, and a voltage value smaller than a voltage value corresponding to the amplitude value of the differential output signal is set to be smaller than the first threshold voltage. A fourth comparator (44) that outputs one of the two signals (Cm ₃ ) according to the difference between the side threshold voltage (Vth ₃ ) and the differential output signal, and the abnormality occurrence determination means Is a signal output from the first comparator and the first comparator. Whether the signal output from the first comparator is likely to contain an abnormal signal based on the progress of the output of the signal output from the first comparator and the signal output from the fourth comparator This is a technical feature.

In the rotation detection device according to claim 6, the abnormality occurrence determination unit changes each time a signal output from the first comparator changes. The difference between the first accumulated value (N ₂ ) in which the number of times has been accumulated and the third accumulated value (N ₁ ) in which the number of times of change has been accumulated for each change in the signal output from the third comparator is 2 The difference between the first accumulated value and the fourth accumulated value (N ₃ ) in which the number of changes is accumulated for each change in the signal output from the fourth comparator is 2 or more. In this case, it is a technical feature to determine that the signal output from the first comparator is likely to contain an abnormal signal.

  In the rotation detection device according to claim 7, in the rotation detection device according to claim 5, the abnormality occurrence determination means is such that the signal output from the third comparator has not changed. The signal output from the fourth comparator while the signal output from the first comparator has changed more than three times or the signal output from the first comparator has not changed It is a technical feature that it is determined that there is a high possibility that an abnormal signal is included in the signal output from the first comparator when is changed three times or more.

  In the rotation detection device according to claim 8, the signal output from the first comparator and the third detection device are the rotation detection devices according to any one of claims 5 to 7. The differential output signal when it is determined by the abnormality occurrence determination means that the signal output from the first comparator is likely to contain an abnormal signal based on the signal output from the comparator. The differential output signal is offset so that the amplitude center of the signal approaches the upper threshold voltage, and the abnormality is based on the signal output from the first comparator and the signal output from the fourth comparator. When it is determined by the occurrence determination means that the signal output from the first comparator is likely to contain an abnormal signal, the amplitude center of the differential output signal is brought closer to the lower threshold voltage. The differential output signal And technical further comprising a differential output signal correction means for offsetting.

  In the rotation detection device according to claim 9, the signal output from the first comparator and the third detection device are the rotation detection devices according to any one of claims 5 to 7. When it is determined by the abnormality occurrence determination means that there is a high possibility that an abnormality signal is included in the signal output from the first comparator based on the signal output from the comparator, and the first There is a possibility that an abnormal signal is included in the signal output from the first comparator by the abnormality occurrence determination means based on the signal output from the comparator of the first and the signal output from the fourth comparator. It is technically characterized by comprising differential output signal correction means for increasing the amplification factor (α) of the differential amplifier when it is determined that the differential amplifier is high.

  In the rotation detection device according to claim 10, the rotation detection device according to any one of claims 1 to 9 is output from the first comparator by the abnormality occurrence determination unit. A technical feature is that it comprises notification means (50) for notifying that when it is determined that the signal is likely to contain an abnormal signal.

  According to the first aspect of the present invention, the rotation detector includes two signals according to the difference between the first threshold voltage set near the amplitude center of the differential output signal output from the differential amplifier and the differential output signal. (For example, an H level signal output when the differential output signal is equal to or higher than the first threshold voltage and an L level signal output when the differential output signal is lower than the first threshold voltage) The difference between the first comparator that outputs one and the second threshold voltage that is set to be different from the first threshold voltage by a voltage value that is smaller than the voltage value corresponding to the amplitude value of the differential output signal. Two signals (for example, an H level signal that is output when the differential output signal is equal to or higher than the second threshold voltage and a differential output signal that is less than the second threshold voltage depending on the difference from the dynamic output signal) A second comparator that outputs one of the L level signals) It is provided. The rotation detection device detects the rotation position of the rotating body based on the signal output from the first comparator by the rotation position detection means, and the signal output from the first comparator by the abnormality occurrence determination means. And a signal output from the second comparator, it is determined whether or not there is a high possibility that the signal output from the first comparator includes an abnormal signal.

  As described above, for example, the second threshold voltage is set higher than the first threshold voltage based on the output progress of the signal output from the first comparator and the signal output from the second comparator. Since only the signal output from the first comparator changes when the signal is output, the signal output from the first comparator, which is a signal for detecting the rotational position of the rotating body, is actually abnormal. Although no signal is included, it can be recognized that the above-described pulse missing may occur (hereinafter also referred to as a pulse missing warning state). Further, since only the signal output from the second comparator is changed when the second threshold voltage is set lower than the first threshold voltage, the signal output from the first comparator is changed. Although it does not actually include an abnormal signal, it can be recognized that the above-described erroneous pulse may occur (hereinafter also referred to as an erroneous pulse warning state).

Based on this recognition, for example, before the abnormal signal is actually included in the signal output from the first comparator, the differential output signal output from the differential amplifier is controlled so as to prevent this abnormality. Thus, it is possible to prevent the abnormal signal as described above from being included in the signal output from the first comparator.
Therefore, erroneous rotation detection when detecting the rotation of the rotating body can be prevented.

  In the invention according to claim 2, the abnormality occurrence determination means is configured to calculate the first accumulated value obtained by accumulating the number of changes for each change of the signal output from the first comparator and the signal output from the second comparator. When the difference from the second accumulated value obtained by accumulating the number of changes for each change is 2 or more, it is determined that there is a high possibility that the signal output from the first comparator includes an abnormal signal.

  Even in this case, when the second threshold voltage is set to be higher than the first threshold voltage, the pulse missing is based on the signal output from the first comparator and the signal output from the second comparator. A warning state can be recognized, and when the second threshold voltage is set lower than the first threshold voltage, the signal output from the first comparator and the second comparator are output. Based on the signal, it can be recognized that an erroneous pulse warning state is present.

  According to a third aspect of the present invention, the abnormality occurrence determination means is configured so that the other three times while one of the signal output from the first comparator and the signal output from the second comparator has not changed. When the above changes, it is determined that the signal output from the first comparator is highly likely to contain an abnormal signal.

  Even in this case, when the second threshold voltage is set to be higher than the first threshold voltage, the pulse missing is based on the signal output from the first comparator and the signal output from the second comparator. A warning state can be recognized, and when the second threshold voltage is set lower than the first threshold voltage, the signal output from the first comparator and the second comparator are output. Based on the signal, it can be recognized that an erroneous pulse warning state is present.

  In the invention according to claim 4, the differential output signal correcting means is configured to detect the differential when the abnormality occurrence determining means determines that the signal output from the first comparator is likely to contain an abnormal signal. The differential output signal is offset so that the amplitude center of the output signal approaches the second threshold voltage.

  As a result, when the second threshold voltage is set higher than the first threshold voltage, for example, the pulse changes because the amplitude center of the differential output signal changes due to endurance fluctuation or the like. It can be recognized that it is a missing warning state. Therefore, by offsetting the amplitude center of the differential output signal closer to the second threshold voltage, that is, increasing the amplitude center of the differential output signal, the signal output from the first comparator is added to the above-described signal. It is possible to prevent such an abnormal signal from being included.

  Further, when the second threshold voltage is set lower than the first threshold voltage, for example, an error pulse is generated because the amplitude center of the differential output signal is changed due to endurance fluctuation or the like. It can be recognized that there is a warning condition. Therefore, by offsetting the amplitude center of the differential output signal closer to the second threshold voltage, that is, increasing the amplitude center of the differential output signal, the signal output from the first comparator is added to the above-described signal. It is possible to prevent such an abnormal signal from being included.

In the fifth aspect of the present invention, instead of the second comparator, the upper side set so as to be larger than the first threshold voltage by a voltage value smaller than the voltage value corresponding to the amplitude value of the differential output signal. A third comparator that outputs one of the two signals according to a difference between the threshold voltage and the differential output signal;
Depending on the difference between the lower threshold voltage set to be smaller than the first threshold voltage by a voltage value smaller than the voltage value corresponding to the amplitude value of the differential output signal and the differential output signal, And a fourth comparator that outputs one of the signals. The abnormality occurrence determining means is configured to output the first based on the output progress of the signal output from the first comparator, the signal output from the third comparator, and the signal output from the fourth comparator. It is determined whether or not there is a high possibility that an abnormal signal is included in the signal output from the comparator.

  When determining whether or not there is a high possibility that an abnormal signal is included in the signal output from the first comparator based on the signals output from the two comparators as in the first aspect of the invention For example, only one of a missing pulse warning state and an erroneous pulse warning state can be determined. Therefore, by determining whether or not there is a high possibility that the signal output from the first comparator includes an abnormal signal based on the output progress of the signals output from the three comparators as in the present invention. Both the missing pulse warning state and the erroneous pulse warning state can be determined.

  According to a sixth aspect of the present invention, the abnormality occurrence determination means includes a first cumulative value obtained by accumulating the number of changes for each change of the signal output from the first comparator and a signal output from the third comparator. When the difference from the third cumulative value in which the number of changes for each change is 2 or more, or for each change in the signal output from the first cumulative value and the fourth comparator, When the difference from the accumulated fourth accumulated value is 2 or more, it is determined that there is a high possibility that an abnormal signal is included in the signal output from the first comparator.

  Even in this case, when the difference between the first cumulative value and the third cumulative value is 2 or more, it is possible to recognize that the pulse missing warning state is present. When the difference from the accumulated value of 2 is 2 or more, it can be recognized that an erroneous pulse warning state is present.

  In the invention of claim 7, the abnormality occurrence determination means determines whether the signal output from the first comparator has changed three or more times while the signal output from the third comparator has not changed. When the signal output from the fourth comparator changes three or more times while the signal output from the first comparator has not changed, the signal output from the first comparator includes an abnormal signal. Determine that the possibility is high.

  Even in this case, if the signal output from the first comparator has changed three or more times while the signal output from the third comparator has not changed, it indicates that a pulse missing warning state has occurred. If the signal output from the fourth comparator changes three times or more while the signal output from the first comparator has not changed, it indicates that there is a false pulse warning state. Can be recognized.

  In the invention of claim 8, based on the signal output from the first comparator and the signal output from the third comparator, for example, the amplitude center of the differential output signal is lowered due to endurance fluctuation or the like. It can be recognized that this is a pulse missing warning state. Therefore, by offsetting the amplitude center of the differential output signal closer to the upper threshold voltage, that is, in the direction of increasing the amplitude center of the differential output signal, the signal output from the first comparator is changed as described above. Inclusion of an abnormal signal can be prevented.

  In the invention of claim 8, based on the signal output from the first comparator and the signal output from the fourth comparator, for example, the amplitude center of the differential output signal is increased due to endurance fluctuation or the like. Therefore, it can be recognized that there is an erroneous pulse warning state. Therefore, the signal output from the first comparator is offset as described above by offsetting the amplitude center of the differential output signal closer to the lower threshold voltage, ie, lowering the amplitude center of the differential output signal. It is possible to prevent an abnormal signal from being included.

  In the ninth aspect of the present invention, there is a possibility that an abnormal signal is included in the signal output from the first comparator based on the signal output from the first comparator and the signal output from the third comparator. For example, a signal that is recognized as a pulse missing warning state and that is output from the first comparator based on a signal output from the first comparator and a signal output from the fourth comparator Is assumed to be an error signal, for example, a false pulse warning state is recognized. When both the pulse missing warning state and the erroneous pulse warning state are recognized as described above, for example, the gap (distance) between the sensor and the rotating body is increased due to secular change or the like, and is output from the differential amplifier. The abnormality is determined because the amplitude value of the differential output signal changes so as to be small. Therefore, by increasing the amplification factor of the differential amplifier, it is possible to prevent the abnormal signal as described above from being included in the signal output from the first comparator.

  According to the tenth aspect of the present invention, when it is determined by the abnormality occurrence determination means that the signal output from the first comparator is likely to contain an abnormality signal, the notification means notifies the user of that fact. Accordingly, there is an effect that it is possible to notify the user that there is a high possibility that an abnormal signal is included in the signal output from the first comparator.

Embodiments of the rotation detection device of the present invention will be described below with reference to the drawings.
[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. First, the configuration of the rotation detection device 10 according to the first embodiment will be described with reference to FIGS. 1 is an explanatory diagram illustrating a schematic configuration of the rotation detection device 10, FIG. 2 is an explanatory diagram illustrating a configuration of the sensor chip 20, and FIG. 3 is a circuit diagram illustrating a configuration example of the rotation detection device 10. . FIG. 4 is a graph illustrating the relationship between the differential output signal Vm output from the operational amplifier 41 and the output signals Cm ₁ , Cm ₂ , and Cm ₃ output from the comparators 42, 43, and 44.

  As shown in FIG. 1, the rotation detection device 10 can detect the rotation position and rotation direction of the rotor R, and is applied to, for example, detection of a crank angle in an internal combustion engine. The rotation detection device 10 mainly includes a sensor chip 20, a bias magnet 30, a signal processing unit 40, a warning device 50, and the like.

  The rotor R is, for example, a rotating body that rotates around an unillustrated crankshaft, and has a gear-shaped gear G on the outer periphery thereof. The gear G has gear teeth T composed of peaks T1 and valleys T2, and is made of, for example, a magnetic material. In FIG. 1, the rotation center of the rotor R is denoted by reference symbol C.

  The bias magnet 30 is a magnet that generates a magnetic field toward the gear teeth T of the rotor R, and is formed in a hollow cylindrical shape. The bias magnet 30 is magnetized to have an N pole (or S pole) on the upper surface (surface close to the rotor R) and an S pole (or N pole) on the lower surface (surface close to the signal processing unit 40). For example, the center axis J0 of the bias magnet 30 is positioned so as to intersect the rotation center C of the rotor R. As a result, the magnetic center of the bias magnet 30 is positioned substantially perpendicular to the gear G.

  The sensor chip 20 is formed by forming two MRE bridges (hereinafter also referred to as MRE bridges 21 and 22) on a common substrate formed in a strip shape. For example, the sensor chip 20 is mounted on a lead frame such as copper. Molded with a thermosetting resin such as epoxy.

  Specifically, as shown in FIG. 2A, the MRE bridges 21 and 22 mounted on the sensor chip 20 have a center axis J0 (virtual center line) of the bias magnet 30 between the gear G and the bias magnet 30. They are arranged side by side along a virtual straight line K2 perpendicular to K1). Further, the sensor chip 20 has an inner space of the bias magnet 30 in which a part of the sensor chip 20 is hollow at a position where the virtual center line K1 which is substantially the center in the longitudinal direction substantially coincides with the central axis J0 of the bias magnet 30. It arrange | positions with respect to the bias magnet 30 so that it may enter.

  These MRE bridges 21 and 22 are arranged so that the separation distance L1 between the MRE bridge 21 and the virtual center line K1 and the separation distance L2 between the MRE bridge 22 and the virtual center line K1 are equal ( L1 = L2), and the MRE bridges 21 and 22 are supplied with a power supply voltage E (power supply potential) with respect to the ground (reference potential) Gnd.

  As shown in FIG. 2B, each of these MRE bridges 21 and 22 is composed of four magnetoresistive elements MREa, MREb, MREc, and MREd, and has a strong magnetic resistance anisotropy effect. A magnetic material (Ni—Co alloy, Ni—Fe alloy, etc.) is formed in a comb shape by connecting a plurality of long sides and short sides.

  Therefore, in each of the magnetoresistive elements MREa, MREb, MREc, and MREd, the resistance value change on the long side becomes dominant, and the magnetoresistive elements MREa, MREb, MREc, and MREd are arranged along the direction in which the long side is provided. The detection axis is set. The magnetoresistive elements MREa, MREb, MREc, and MREd have the same configuration in terms of their long sides, short sides, number, etc., although the directions of the detection axes are different.

  These four magnetoresistive elements MREa, MREb, MREc, and MREd are arranged in a matrix of 2 rows and 2 columns in the sensor chip 20, and the magnetoresistive elements MRE (MREa and MREb of each column are the first). The columns, MREc and MREd are the second column, are aligned in a direction parallel to the magnetic center of the magnetic field of the bias magnet 30, and the magnetoresistive elements MRE of each row (MREa and MREc are the first row, and MREb and MREd are the second row). Row) are arranged along the rotation direction of the rotor R. The magnetoresistive element MREa and the magnetoresistive element MREd have a detection axis at an angle of about 45 ° with respect to the magnetic center of the magnetic field of the bias magnet 30, and the magnetoresistive element MREb and the magnetoresistive element MREc Each is arranged so as to have a detection axis at an angle of about −45 ° with respect to the magnetic center.

  Accordingly, since the detection axes of the magnetoresistive elements MREa and MREd and the detection axes of the magnetoresistive elements MREb and MREc are orthogonal to each other, the magnetoresistive element MREa is affected by changes in the direction of the magnetic field acting on the MRE bridges 21 and 22. , MREd and magnetoresistive elements MREb, MREc have different resistance increasing / decreasing directions.

  As shown in FIG. 2C, these four magnetoresistive elements MREa, MREb, MREc, and MREd are connected in series between the power supply voltage E and the ground Gnd in the order of MREa → MREd → MREb → MREc. Therefore, for example, the output of the MRE bridge 21 is taken out as an intermediate potential V1 between MREd and MREb. Similarly, the output of the MRE bridge 22 is taken out as an intermediate potential V2 between MREd and MREb. Regarding the connection of the four magnetoresistive elements MREa, MREb, MREc, and MREd, they may be connected between the power supply voltage E and the ground Gnd in the order of MREc → MREb → MREd → MREa.

  Therefore, if the resistance values of the magnetoresistive elements MREa, MREb, MREc, and MREd are Ra, Rb, Rc, and Rd, respectively, and the power supply voltage applied to the MRE bridge 21 is E, the midpoint potential V1 of the MRE bridge 21 is It can be expressed by the following formula 1.

[Equation 1]
V1 = (Rb + Rσ1 + Rc + Rσ2) × E / (Ra + Rσ1 + Rb + Rσ2 + Rc + Rσ1 + Rd + Rσ2)

  Here, Rσ1 and Rσ2 are the amount of change in resistance value caused by the magnetostriction effect caused by the external stresses σ1 and σ2, and the external stress σ1 and the external stress σ2 are different. When the sum of the stresses σ1 and σ2 is included in both the numerator and the denominator and at least the resistance values Ra, Rb, Rc, and Rd of the magnetoresistive elements MREa, MREb, MREc, and MREd are equal, the external stresses σ1, σ2 Does not affect the midpoint potential V1.

  That is, in the MRE bridge 21 shown in FIG. 2B, the magnetoresistive elements MREa and MREd and the magnetoresistive elements MREb and MREc are arranged in different columns in the matrix arrangement, so that different external stresses are applied to the respective columns. Even if σ1 and σ2 are applied, the sum of the magnetostrictive effects on the magnetoresistive elements MREa and MREd can be made equal to the sum of the magnetostrictive effects on the magnetoresistive elements MREb and MREc.

  For this reason, the influence of the magnetostriction effect in each of the magnetoresistive elements MREa, MREb, MREc, and MREd on the midpoint potential V1 of the MRE bridge 21 can be substantially canceled out by the element part consisting of MREa and MREd and the element part consisting of MREb and MREc. Thus, the influence of the magnetostrictive effect can be reduced, and an output signal corresponding to the direction of the bias magnetic field acting on the magnetostrictive effect can be output with high accuracy. The same applies to the MRE bridge 22.

  The signal processing unit 40 can detect the rotational position of the rotor R by differentially calculating a plurality of sensor signals V1 and V2 output in different phases from the two MRE bridges 21 and 22 mounted on the sensor chip 20. It has a function of outputting the rotation data Dp based on the differential output signal Vm. Further, the signal processing unit 40 has a function of performing a rotation error detection preventing process for preventing rotation error detection.

  Specifically, as shown in FIG. 3, the signal processing unit 40 includes an operational amplifier 41, comparators 42, 43, and 44, a signal processing circuit 48, and the like. The MRE bridge can input the sensor signal V1 output from the MRE bridge 21 to the non-inverting input (+) of the operational amplifier 41 and the sensor signal V2 output from the MRE bridge 22 to the inverting input (−) of the operational amplifier 41. 21 and 22 and the operational amplifier 41 are connected.

Comparator 42 is for preventing rotation erroneous detection, the comparator 42, the first threshold voltage Vth ₁ that is set in accordance with the reference voltage Vref ₁ inverting input (-) receives an input to an operational amplifier 41 outputs can be inputted to the non-inverting input (+).

The comparator 43 is for detecting the rotation of the rotor R, the comparator 43, a second threshold voltage Vth ₂ is set in accordance with the voltage Vref _2-inverting input - with inputs, the () The output of the operational amplifier 41 is configured to be input to the non-inverting input (+).

The comparator 44 is for preventing rotation erroneous detection, the comparator 44, a third threshold voltage Vth ₃ to be set in accordance with the voltage Vref ₃ inverting input (-) receives an input to an operational amplifier 41 outputs can be inputted to the non-inverting input (+).

As illustrated in FIG. 4, the second threshold voltage Vth ₂ (= Vref ₂ ) is set to be positioned at the amplitude center of the differential output signal Vm input from the operational amplifier 41, for example. The first threshold voltage Vth ₁ is set to be higher than the second threshold voltage Vth ₂ by, for example, 20% of the amplitude value of the differential output signal Vm, and the third threshold voltage Vth ₃ is, for example, The threshold value is set to be lower than the second threshold voltage Vth ₂ by 20% of the amplitude value of the differential output signal Vm.

By configuring the signal processing unit 40 in this way, as shown in FIG. 4, the differential voltage (V1−V2) of both inputs inputted to the operational amplifier 41 becomes a predetermined amplification factor α (for example, 2 × or 3 ×). ) And output from the operational amplifier 41 as a wave-like differential output signal Vm (= α (V1−V2)). When the differential output signal Vm output from the operational amplifier 41 is input to the comparator 42, when the differential output signal Vm is equal to or higher than the first threshold voltage Vth ₁ (= Vref ₁ ), the differential output signal Vm is When the voltage is lower than the first threshold voltage Vth ₁ , the L level output signal Cm ₁ is output from the comparator 42 (see the waveform of the broken line shown in FIG. 4). When the differential output signal Vm output from the operational amplifier 41 is input to the comparator 43, the differential output signal Vm is H level when the differential output signal Vm is equal to or higher than the second threshold voltage Vth ₂ (= Vref ₂ ). L level, the output signal Cm ₂ of the output from the comparator 43 when Vm is less than the second threshold voltage Vth ₂ (see the solid line of waveform shown in FIG. 4). Further, when the differential output signal Vm output from the operational amplifier 41 is input to the comparator 44, when the differential output signal Vm is equal to or higher than the third threshold voltage Vth ₃ (= Vref ₃ ), the differential output signal Vm is H level. L level, the output signal Cm ₃ of output from the comparator 44 when Vm is less than the third threshold voltage Vth ₃ (see the waveform of a chain line shown in FIG. 4). Since the horizontal axis in FIG. 4 is the rotor rotation angle, when the rotor R is rotating, the horizontal axis in FIG. 4 also corresponds to the time axis.

When the signal processing circuit 48 functions as the rotational position detection means, based on the output signal Cm ₂ from the comparator 43, the signal processing circuit 48 is “H” when the position of the gear teeth T of the rotor R is within a predetermined angle range. (H level), if not within the range, rotation data Dp of “L” (L level) is generated and output. Further, when the signal processing circuit 48 functions as an abnormality occurrence determination unit, based on the output signal Cm ₁ from the comparator 42, the output signal Cm ₂ from the comparator 43, and the output signal Cm ₃ from the comparator 44, A rotation error detection preventing process for preventing rotation error detection described later is performed.

  A warning device 50 is electrically connected to the signal processing circuit 48 of the signal processing unit 40. The warning device 50 is, for example, a warning light or sound provided at an appropriate position so that the user can recognize it. An output device or the like that operates in response to a warning signal output from the signal processing circuit 48.

Hereinafter, the flow of the rotation erroneous detection prevention process executed by the signal processing circuit 48 of the rotation detection device 10 according to the first embodiment will be described in detail with reference to FIGS. Note that at the start of the erroneous rotation detection preventing process, the output signals Cm ₁ , Cm ₂ , and Cm ₃ input from the comparators 42, 43, and 44 are all at the L level. Here, FIG. 5 and FIG. 6 are flowcharts showing the flow of the rotation error detection preventing process executed by the signal processing circuit 48 shown in FIG. FIG. 7 is a graph showing the relationship between the differential output signal Vm and the output signals Cm ₁ , Cm ₂ , Cm ₃ of the comparators 42, 43, 44 in the false pulse warning state. FIG. 8 is a graph showing the relationship between the differential output signal Vm and the output signals Cm ₁ , Cm ₂ , Cm ₃ of the comparators 42, 43, 44 in the pulse missing warning state.

First, when the output signals Cm ₁ , Cm ₂ , and Cm ₃ input from the comparators 42, 43, and 44 are acquired in step S101 of FIG. 5, whether or not the flag F = 1 is determined in step S103, in step S105. It is determined whether or not the flag F = 2 or not in step S107. Since the flag F is set to 0 at the start of the erroneous rotation detection preventing process, it is determined No in steps S103, S105, and S107.

Here, the flag F = 1 indicates a state in which the differential output signal Vm is equal to or higher than the first threshold voltage Vth ₁ , that is, a state in which the output signal Cm ₁ is at the H level. The flag F = 2 means that the differential output signal Vm is equal to or higher than the second threshold voltage Vth ₂ and lower than the first threshold voltage Vth ₁ , that is, the output signal Cm ₂ is at the H level and the output signal Cm ₁ is at the L level. Indicates a state that is a level. Also, the flag F = 3, the state differential output signal Vm is the third threshold voltage Vth ₃ or more and less than the second threshold voltage Vth _2, i.e., the output signal Cm ₃ is H level and the output signal Cm ₂ L Indicates a state that is a level. The flag F = 0 indicates a state where the differential output signal Vm is less than the third threshold voltage Vth ₃ , that is, a state where the output signal Cm ₃ is at the L level.

Then, in step S109, the output signal Cm ₃ is determined whether H level. Here, as indicated by the detection point Pa ₁ in FIG. 4, since the differential output signal Vm is less than the third threshold voltage Vth ₃ , if the output signal Cm ₃ is at the L level, No in step S 109. And the process from step S101 is repeated.

During this iterative process, when the differential output signal Vm becomes equal to or higher than the third threshold voltage Vth ₃ (see the detection point Pa _{2 in} FIG. 4) and the output signal Cm ₃ becomes H level (Yes in S109), in step S111, The flag F = 3 is set.

When the processing from step S101 is determined as Yes at which to step S107 performed, in step S113, the output signal Cm ₂ is determined whether H level. Here, as indicated by the detection point Pa ₂ in FIG. 4, when the output signal Cm ₂ is at the L level because the differential output signal Vm is less than the second threshold voltage Vth ₂ , No in step S113. It is determined.

Next, in step S115, the output signal Cm ₃ is determined whether L level. Here, in the case as shown in the detection point Pa ₂ in FIG. 4, the output signal Cm ₃ is at the H level since the differential output signal Vm is the third threshold voltage Vth ₃ or more, No at step S115 And the process from step S101 is repeated.

If the differential output signal Vm becomes equal to or higher than the second threshold voltage Vth ₂ (see the detection point Pa _{3 in} FIG. 4) and the output signal Cm ₂ becomes H level during the iterative process including the determination of Yes in step S107. (Yes in S113), in step S117, the flag F = 2 is set.

When the processing from step S101 is determined as Yes at which to step S105 performed in step S119 of FIG. 6, the output signal Cm ₁ is determined whether H level. Here, as shown in the detection point Pa ₃ in FIG. 4, when the output signal Cm ₁ since the differential output signal Vm is first less than the threshold voltage Vth ₁ is at the L level, No at step S119 It is determined.

Next, in step S121, the output signal Cm ₂ is determined whether L level. Here, in the case as shown in the detection point Pa ₃ in FIG. 4, the output signal Cm ₂ is at the H level since the differential output signal Vm is the second threshold voltage Vth ₂ or more, No at step S121 And the process from step S101 is repeated.

Yes and the determination in the repeating process, including in at step S105, (see detection point Pa ₄ in FIG. 4) the differential output signal Vm is the first threshold voltage Vth ₁ or more, the output signal Cm ₁ becomes H level (Yes in S119), the flag F = 1 is set in step S123 of FIG.

When the processing from step S101 is determined as Yes at which to step S103 performed in step S125, the output signal Cm ₃ is determined whether L level. Here, as indicated by the detection point Pa ₄ in FIG. 4, when the output signal Cm ₃ is at the H level because the differential output signal Vm is equal to or higher than the third threshold voltage Vth ₃ , No is determined in step S125. And the process from step S101 is repeated.

During iterative process including determination of Yes in step S103, (see detection point Pa ₅ in FIG. 4) the differential output signal Vm becomes lower than the third threshold voltage Vth _3, when the output signal Cm ₃ becomes L level (Yes in S125), in step S127, the flag F = 0 is set.

In step S115 of FIG. 5 described above, from the state a flag F = 3 (see detection point Pb ₁ in FIG. 7), the differential output signal Vm is less than the third threshold voltage Vth ₃ (see detection point Pb ₂ in FIG. 7 ), and when the output signal Cm ₃ becomes L level (Yes in S115), the lower the offset process is performed in step S131.

In this situation, as can be seen from the change from the detection point Pb ₁ to the detection point Pb ₂ in FIG. 7, only the output signal Cm ₃ changes from the H level to the L level, and the output signal Cm ₂ maintains the L level. Therefore, although the output signal Cm ₂ output from the comparator 43 does not actually include an abnormal signal, it can be recognized that the above-described erroneous pulse warning state is likely to cause the erroneous pulse.

Therefore, the lower offset process is performed in step S131 based on the determination of Yes in step S115. In this process, so as to approach the vibration center of the differential output signal Vm outputted from the operational amplifier 41 to the third threshold voltage Vth _3, to offset the differential output signal Vm on the lower side.

Further, in step S121 of FIG. 6 described above, the flag F = 2 in which state (see detection point Pc ₁ in FIG. 8), the detection point of the differential output signal Vm is the second threshold voltage Vth less than ₁ (Fig. 8 Pc ₂ reference), and the output signal Cm ₂ becomes the L level (Yes in S121), the upper offset process is performed in step S133.

In this situation, as can be seen from the change from the detection point Pc ₁ to the detection point Pc ₂ in FIG. 8, only the output signal Cm ₂ changes from the H level to the L level, and the output signal Cm ₁ maintains the L level. Therefore, although the output signal Cm ₂ output from the comparator 43 does not actually include an abnormal signal, it can be recognized that the above-described pulse missing warning state is highly likely to occur.

Therefore, an upper offset process is performed in step S133 based on a determination of Yes in step S121 of FIG. In this process, so as to approach the vibration center of the differential output signal Vm outputted from the operational amplifier 41 to a first threshold voltage Vth _1, to offset the differential output signal Vm to the upper.

When the processing in step S131 in FIG. 5 or step S133 in FIG. 6 is performed, warning processing is performed in step S135 in FIG. In this warning process, a warning signal is output to the warning device 50. In response to this warning signal, the warning device 50 warns the user that there is a high possibility that the output signal Cm ₂ output from the comparator 43 includes an abnormal signal such as an erroneous pulse warning state or a missing pulse warning state. Announcement is made using a light or sound output device.

As described above, the rotation detection device 10 according to the first embodiment has the second threshold voltage Vth ₂ and the differential output signal Vm set near the amplitude center of the differential output signal Vm output from the operational amplifier 41. A comparator 43 that outputs an output signal Cm ₂ according to the difference between the first threshold voltage Vth ₁ and the differential output signal Vm that are set to be higher than the second threshold voltage Vth _2. The comparator 42 that outputs the output signal Cm ₁ and the output signal Cm ₃ according to the difference between the third threshold voltage Vth ₃ that is set to be lower than the second threshold voltage Vth ₂ and the differential output signal Vm And a comparator 44. The rotation detection device 10 detects the rotation position of the rotor R based on the output signal Cm ₂ output from the comparator 43 by the signal processing circuit 48 functioning as rotation position detection means, and also functions as abnormality occurrence determination means. The output signal Cm ₂ output from the comparator 43 based on the output progress of the output signal Cm ₂ output from the comparator 43 by the signal processing circuit 48 and the output signal Cm ₁ and output signal Cm ₃ output from the comparator 42 and the comparator 44. ₂ determines whether or not there is a high possibility that an abnormal signal is included in ₂ .

Based on the output progress of the output signal Cm ₁ output from the comparator 42 and the output signal Cm ₂ and output signal Cm ₃ output from the comparator 43 and the comparator 44, as shown in FIG. _{Since 2} does not change and only the output signal Cm ₃ changes, it can be recognized that the output signal Cm ₂ does not actually include an abnormal signal but is in the erroneous pulse warning state described above. Further, as shown in FIG. 8, since the output signal Cm ₁ is not changed and only the output signal Cm ₂ is changed, the output signal Cm ₂ that is a signal for detecting the rotational position of the rotor R is not a real signal. Although an abnormal signal is not included in, it can be recognized that the above-mentioned pulse missing warning state is present.

Based on this recognition, before the abnormal signal is actually included in the signal output from the comparator 43, the differential output signal Vm output from the operational amplifier 41 is controlled so as to prevent this abnormality. It is possible to prevent the abnormal signal as described above from being included in the signal output from the.
Therefore, erroneous rotation detection when detecting the rotation of the rotor R can be prevented.

Further, in the rotation detection device 10 according to the first embodiment, the comparator 43 for detecting the rotation of the rotor R and the first threshold voltage Vth ₁ set to be higher than the second threshold voltage Vth ₂ . And a comparator 42 that outputs an output signal Cm ₁ corresponding to the difference between the differential output signal Vm, a third threshold voltage Vth ₃ that is set to be smaller than the second threshold voltage Vth ₂ , and the differential output signal And a comparator 44 that outputs an output signal Cm ₃ corresponding to the difference from Vm.

Thereby, it is determined whether or not the erroneous pulse warning state is based on the output signal Cm ₂ and the output signal Cm _3, and whether or not the pulse missing warning state is based on the output signal Cm ₂ and the output signal Cm ₁ . Both the determination and the determination can be made together.

Further, in the rotation detection device 10 according to the first embodiment, the amplitude center of the differential output signal Vm is changed based on the output signal Cm ₂ and the output signal Cm ₃ so that the amplitude center of the differential output signal Vm becomes high due to endurance fluctuation or the like. Therefore, it is determined that the state is an erroneous pulse warning state. In response to this determination, the output signal Cm ₂ is offset as described above by offsetting the amplitude center of the differential output signal Vm closer to the third threshold voltage Vth ₃ , that is, the direction of decreasing the amplitude center of the differential output signal Vm. It is possible to prevent such an abnormal signal from being included.

Further, in the rotation detection device 10 according to the first embodiment, the amplitude center of the differential output signal Vm is changed based on the output signal Cm ₂ and the output signal Cm ₁ so that the amplitude center of the differential output signal Vm becomes low due to endurance fluctuation or the like. Therefore, it is determined that the pulse missing warning state is present. In response to this determination, the output signal Cm ₂ is offset as described above by offsetting the amplitude center of the differential output signal Vm closer to the first threshold voltage Vth ₁ , that is, the direction of increasing the amplitude center of the differential output signal Vm. It is possible to prevent such an abnormal signal from being included.

Further, in the rotation detection device 10 according to the first embodiment, when it is determined that there is a high possibility that the output signal Cm ₂ output from the comparator 43 includes an abnormal signal, a warning device which is a notification means to that effect. 50 to notify the user. Accordingly, there is an effect that it is possible to notify the user that there is a high possibility that the output signal Cm ₂ output from the comparator 43 includes an abnormal signal.

[Second Embodiment]
Next, a rotation detection device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 9 and FIG. 10 are flowcharts showing a flow of erroneous rotation detection preventing processing executed by the signal processing circuit 48 of the rotation detecting device 10 according to the second embodiment. Note that the mechanical configuration of the rotation detection device 10 of the second embodiment is the same as that of the first embodiment described above with reference to FIGS.

In the first embodiment described above, either an erroneous pulse warning state or a missing pulse warning state based on the level change state of the output signals Cm ₁ , Cm ₂ , Cm ₃ output from the comparators 42, 43, 44. Whether or not there is detected is detected, and the differential output signal Vm output from the operational amplifier 41 is offset and corrected according to the detected warning state. On the other hand, in the second embodiment, accumulated values N ₁ and N in which the number of changes are accumulated for each change of the output signals Cm ₁ , Cm ₂ and Cm ₃ output from the comparators 42, 43 and 44. ₂ and N ₃ , it is detected whether an erroneous pulse warning state or a missing pulse warning state is detected, and the differential output signal Vm output from the operational amplifier 41 is offset according to the detected warning state. to correct.

Hereinafter, the flow of the rotation erroneous detection prevention process executed by the signal processing circuit 48 of the rotation detection device 10 according to the second embodiment will be described in detail with reference to the flowcharts shown in FIGS. 9 and 10. Note that at the start of the erroneous rotation detection preventing process, the output signals Cm ₁ , Cm ₂ , and Cm ₃ input from the comparators 42, 43, and 44 are all at the L level.

First, when the output signals Cm ₁ , Cm ₂ , and Cm ₃ input from the comparators 42, 43, and 44 are acquired in step S201 in FIG. 9, whether or not the level of the output signal Cm ₁ has changed in step S203. Is determined. Here, if the level of the output signal Cm ₁ is maintained at the L level or the H level (No in S203), the determination process in step S207 is performed. On the other hand, if the level of the output signal Cm ₁ changes from L level to H level, (Yes in S203) in the case of changes from H level to L level, 1 is added to the first cumulative value _{N 1} in step S205 Is done.

Then, in step S207, the level of the output signal Cm ₂ is determined whether or not to have changed. If the level of the output signal Cm ₂ is maintained at the L level or the H level (No in S207), the determination process in step S211 is performed. On the other hand, if the level of the output signal Cm ₂ changes from L level to H level, (Yes in S207) in the case of changes from H level to L level, 1 is added at step S209 to the second cumulative value _{N 2} Is done.

Then, in step S211, it is determined whether or not the level of the output signal Cm ₃ has changed. Here, if the level of the output signal Cm ₃ is maintained at the L level or the H level (No in S211), the determination process in step S215 is performed. On the other hand, if the level of the output signal Cm ₃ changes from L level to H level, (Yes in S211) in the case of changes from H level to L level, 1 is added at step S213 to the third cumulative value _{N 3} Is done.

Next, in step S215, the absolute value of the difference between the second cumulative value N ₂ and the third cumulative value N ₃ is determined whether it is 2 or more. Here, as shown in FIG. 7, in the erroneous pulse warning state, the level of the output signal Cm ₃ changes from the L level to the H level and then changes again to the L level as in the detection points Pb ₁ and Pb ₂ . On the other hand, the level of the output signal Cm ₂ is maintained at the L level. Therefore, when the absolute value of the difference between the second cumulative value N ₂ and the third cumulative value N ₃ is 2 or more, it is erroneous pulse alarm condition is determined.

Not error pulse alarm condition, unless the absolute value of the difference between the second cumulative value _{N 2} and the third cumulative value _{N 3} is 2 or more (No in S215), in step S217, the second cumulative value _{N 2} second 1 the absolute value of the difference between the accumulated value N ₁ is determined whether it is 2 or more. Here, as shown in FIG. 8, in the pulse missing warning state, the level of the output signal Cm ₂ changes from the L level to the H level and then changes to the L level again as in the detection point Pc ₁ and the detection point Pc ₂ . On the other hand, the level of the output signal Cm ₁ is maintained at the L level. Therefore, the absolute value of the difference between the second cumulative value N ₂ and the first cumulative value N ₁ is the case where 2 or more, it is determined that a missing pulse alarm condition.

Not missing pulses alarm condition, unless the absolute value of the difference between the second cumulative value N ₂ and the first cumulative value N ₁ is 2 or more (No in S217), the error pulse warning or missing pulse alarm condition either Since it is not a state, the process from step S201 is repeated.

In step S215 described above, an erroneous pulse is a warning state second cumulative value _{N 2} when the absolute value of the difference between the third cumulative value _{N 3} is 2 or more (Yes in S215), in step S221 of FIG. 10, the Similar to the first embodiment, the lower offset process is performed.

Further, in step S217 described above, pulse missing is a warning state and the second cumulative value _{N 2} when the absolute value of the difference between the first cumulative value _{N 1} is 2 or more (at S217 Yes), in step S223 of FIG. 10 Similarly to the first embodiment, the upper offset process is performed.

  When the process in step S221 or step S223 in FIG. 10 is performed, a warning process is performed in step S225 as in the first embodiment.

As described above, in the rotation detection device 10 according to the second embodiment, the accumulated value N ₂ in which the number of changes is accumulated every time the output signal Cm ₂ changes and the number of changes is accumulated every time the output signal Cm ₃ changes. when the difference between the accumulated value N _3, which is is 2 or more, it is likely to contain abnormal signal pulses such erroneous output signal Cm ₂ is determined. Further, when the difference between the accumulated value N ₂ and the cumulative value N ₁ to change frequency for each change is accumulated in the output signal Cm ₁ is 2 or more, can be included abnormal signal, such as a missing pulse in the output signal Cm ₂ It is determined that the property is high.

Even in this case, when the difference between the accumulated value N ₂ and the accumulated value N ₃ is 2 or more, it can be recognized that the erroneous pulse warning state is present, and the accumulated value N ₂ and the accumulated value N ₁ If the difference is 2 or more, it can be recognized that the pulse missing warning state is present.

[Third Embodiment]
Next, a rotation detection device according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a part of a flowchart showing a flow of erroneous rotation detection preventing processing executed by the signal processing circuit 48 of the rotation detecting device 10 according to the third embodiment. Since the mechanical configuration of the rotation detection device 10 of the third embodiment is the same as that of the first embodiment described above with reference to FIGS. 1 to 3, the description is omitted while referring to the same drawing.

In the second embodiment described above, accumulated values N ₁ , N ₂ , N ₃ in which the number of changes is accumulated for each change of the output signals Cm ₁ , Cm ₂ , Cm ₃ output from the comparators 42, 43, 44. The differential output signal Vm output from the operational amplifier 41 is offset and corrected in accordance with the warning state detected based on the above. On the other hand, in the third embodiment, the differential output signal Vm output from the operational amplifier 41 is offset in accordance with the warning state detected based on the accumulated values N ₁ , N ₂ , and N ₃ . Or by changing the amplification factor α of the operational amplifier 41.

Hereinafter, the flow of the rotation erroneous detection prevention process executed by the signal processing circuit 48 of the rotation detection device 10 according to the third embodiment will be described in detail with reference to the flowcharts shown in FIGS. 9 and 11. Note that at the start of the erroneous rotation detection preventing process, the output signals Cm ₁ , Cm ₂ , and Cm ₃ input from the comparators 42, 43, and 44 are all at the L level.

As in the second embodiment, (Yes in S215) step S215 in the absolute value of the difference between the second cumulative value _{N 2} and the third cumulative value _{N 3} is 2 or more in FIG. 9, the steps of FIG. 11 In S301, the flag Fa = 1 is set. Here, the state in which the flag Fa = 1 is that the absolute value of the difference between the second cumulative value N ₂ and the third cumulative value N ₃ is 2 or more and is an erroneous pulse warning state, so that step S215 in FIG. 9 is performed. In this state, the determination of Yes is even once. Also, the state is a flag Fb = 1 to be described later, the step of FIG. 9 that the second accumulated value N ₂ as the absolute value is 2 or more and a missing pulse alarm condition of the difference between the first cumulative value N ₁ In S217, the determination of Yes is even once.

  In step S303, it is determined whether or not the flag Fb = 1. If the determination of Yes in step S217 has not been made once and the flag Fb is not 1 (No in S303), the lower offset process is performed in step S305 as in the second embodiment. The

Further, the as in the second embodiment, the second cumulative value _{N 2} at step S217 in FIG. 9 when the absolute value of the difference between the first cumulative value _{N 1} is 2 or more (Yes in S217), FIG. 11 In step S307, the flag Fb = 1 is set.

  In step S309, it is determined whether or not the flag Fa = 1. If the determination of Yes in step S215 has not been made once and the flag Fa is not 1 (No in S309), the upper offset processing is performed in step S311 as in the second embodiment. .

  In the above-described step S303, if the determination of Yes is once in step S217 and the flag Fb = 1 (Yes in S303), or if the determination of Yes is once in step S215 in step S309, the flag When Fa = 1 (Yes in S309), not only the differential output signal Vm output from the operational amplifier 41 changes so as to be offset, but also, for example, between the sensor and the rotating body due to secular change or the like. A case is assumed where the amplitude of the differential output signal Vm changes so as to decrease due to an increase in the gap (distance).

  Therefore, the amplification factor α of the operational amplifier 41 is appropriately increased by the amplification factor increasing process in step S313, and the differential output signal Vm output from the operational amplifier 41 is corrected so as to increase the amplitude.

  When any one of step S305, step S311, and step S313 is performed, a warning process is performed in step S315, as in the first embodiment.

As described above, the rotation detection device 10 according to the third embodiment is recognized at least once as an erroneous pulse warning state based on the output signal Cm ₂ and the output signal Cm ₃ , and the output signal Cm ₂ and the output signal Cm ₁ , the pulse missing warning state is recognized even once, that is, when the amplitude of the differential output signal Vm changes so as to decrease, Increase amplification factor α appropriately. Thereby, in addition to the effect in the second embodiment, it is possible to prevent the abnormal signal as described above from being included in the output signal Cm ₂ due to the decrease in the amplitude of the differential output signal Vm. .

The present invention is not limited to the above embodiments, and may be embodied as follows. Even in this case, the same operations and effects as those of the above embodiments can be obtained.
(1) In the first embodiment, the present invention is not limited to determining that there is an erroneous pulse warning state when the output signal Cm ₃ becomes L level from the state where the flag F = 3 (step S115 in FIG. 5). As can be seen from the change in the differential output signal Vm near the detection point Pb ₁ and the detection point Pb ₂ in FIG. 7, the level of the output signal Cm ₃ is three times or more while the level of the output signal Cm ₂ is not changing. It may be determined that there is an erroneous pulse warning state due to the change.
Further, it is not limited to determining that the pulse missing warning state is obtained when the output signal Cm ₂ becomes L level from the state where the flag F = 2 (step S125 in FIG. 5), but the detection point Pc _{1 in} FIG. and as can be seen from the change of the differential output signal Vm of the near detection point Pc _2, pulse missing alarm condition by the level of the output signal Cm ₂ is changed three times or more while the level of the output signal Cm ₁ is not changed It may be determined.

(2) In the rotation detection device 10 in which the possibility of erroneous pulses is very high compared to the possibility of missing pulses, the comparator 42 is eliminated and the output signal Cm ₂ of the comparator 43 and the output signal Cm _{3 of the} comparator 44 are eliminated. If it is determined based on the erroneous pulse warning state, lower offset processing (S131, S221, S305) may be performed.
Further, in the rotation detection device 10 in which the possibility of pulse omission is very high compared to the possibility of occurrence of an erroneous pulse, the comparator 44 is eliminated, and the output signal Cm ₂ of the comparator 43 and the output signal Cm _{1 of the} comparator 41 are When the pulse missing warning state is determined based on the above, the upper offset processing (S133, S223, S311) may be performed.

(3) The flags Fa and Fb in the third embodiment are cleared when a certain period of time has elapsed since the start of the rotation error detection preventing process or when a certain number of output signals Cm ₁ , Cm ₂ , and Cm ₃ are acquired. May be.

(4) In the first embodiment, as in the third embodiment, the flag Fa indicating whether or not it has been determined that the erroneous pulse warning state has been detected, and the missing pulse warning state. May be provided, and a flag Fb indicating whether or not has been determined even once may be provided, and when the flag Fa = 1 and the flag Fb = 1, the amplification factor α of the operational amplifier 41 may be changed.

It is explanatory drawing which shows schematic structure of the rotation detection apparatus which concerns on 1st Embodiment of this invention. 2A is an explanatory diagram illustrating the configuration of the sensor chip, FIG. 2B is an explanatory diagram illustrating the configuration of the MRE bridge formed on the sensor chip, and FIG. 2C is a diagram illustrating the configuration of the sensor chip. It is a circuit diagram which shows the equivalent circuit of the MRE bridge shown to 2 (B). It is a circuit diagram which shows the structural example of the rotation detection apparatus which concerns on 1st Embodiment. It is a graph which illustrates the relationship between the differential output signal output from an operational amplifier, and the output signal output from each comparator. FIG. 4 is a part of a flowchart showing a flow of a rotation error detection preventing process executed by the signal processing circuit shown in FIG. 3. FIG. 4 is a part of a flowchart showing a flow of a rotation error detection preventing process executed by the signal processing circuit shown in FIG. 3. It is a graph which shows the relationship between the differential output signal in a false pulse warning state, and the output signal of each comparator. It is a graph which shows the relationship between the differential output signal in a pulse missing warning state, and the output signal of each comparator. It is a part of flowchart which shows the flow of the rotation misdetection prevention process performed by the signal processing circuit of the rotation detection apparatus which concerns on 2nd Embodiment. It is a part of flowchart which shows the flow of the rotation misdetection prevention process performed by the signal processing circuit of the rotation detection apparatus which concerns on 2nd Embodiment. It is a part of flowchart which shows the flow of the rotation erroneous detection prevention process performed by the signal processing circuit of the rotation detection apparatus which concerns on 3rd Embodiment. It is a graph which shows the relationship between the differential output signal output from an operational amplifier, and the comparator output signal output from a comparator according to this differential output signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Rotation detection apparatus 20 ... Sensor chip 21, 22 ... MRE bridge (magnetic sensor)
30 ... Bias magnet (magnet)
40: Signal processing unit 41: Operational amplifier (differential amplifier)
42 ... Comparator (second comparator, third comparator)
43 ... Comparator (first comparator)
44: Comparator (second comparator, fourth comparator)
48. Signal processing circuit (rotational position detection means, abnormality occurrence determination means, differential output signal correction means)
50. Warning device (notification means)
Cm ₁ , Cm ₂ , Cm ₃ ... Output signal G... Gear N ₁ ... Cumulative value (second cumulative value, third cumulative value)
N ₂ ... Cumulative value (first cumulative value)
N ₃ ... Cumulative value (second cumulative value, fourth cumulative value)
R ... Rotor (rotating body)
T: Gear tooth Vm: Differential output signal Vth ₁ : First threshold voltage (second threshold voltage, upper threshold voltage)
Vth ₂ ... second threshold voltage (first threshold voltage)
Vth ₃ ... third threshold voltage (second threshold voltage, lower threshold voltage)
α: amplification factor

Claims (10)

A magnet that generates a magnetic field toward a gear tooth of a rotating body having a gear-like gear;
Based on the magnetic field that is arranged along a virtual straight line perpendicular to the magnetic central axis of the magnet between the gear and the magnet, and that changes due to the movement of the gear teeth as the rotating body rotates. Two magnetic sensors that each output a sensor signal whose voltage varies,
A differential amplifier that amplifies and outputs a differential output signal corresponding to a difference between two sensor signals output at different phases from the two magnetic sensors;
A first comparator that outputs one of two signals according to a difference between a first threshold voltage set near the amplitude center of the differential output signal and the differential output signal;
According to the difference between the second threshold voltage set to be different from the first threshold voltage by a voltage value smaller than the voltage value corresponding to the amplitude value of the differential output signal and the differential output signal. A second comparator that outputs one of the two signals;
Rotational position detecting means for detecting a rotational position of the rotating body based on a signal output from the first comparator;
There is a possibility that an abnormal signal is included in the signal output from the first comparator based on the output progress of the signal output from the first comparator and the signal output from the second comparator. An abnormality occurrence determination means for determining that the height is high;
A rotation detection device comprising:   The abnormality occurrence determination unit changes the first accumulated value in which the number of changes is accumulated for each change of the signal output from the first comparator and the change of the signal output from the second comparator. When the difference from the second accumulated value in which the number of times is accumulated is 2 or more, it is determined that the signal output from the first comparator is highly likely to include an abnormal signal. The rotation detection device according to claim 1.   The abnormality occurrence determination means, when one of the signal output from the first comparator and the signal output from the second comparator has not changed, the other has changed three or more times, The rotation detection device according to claim 1, wherein it is determined that there is a high possibility that an abnormal signal is included in the signal output from the first comparator.   When it is determined by the abnormality occurrence determining means that the signal output from the first comparator is likely to contain an abnormal signal, the amplitude center of the differential output signal is set to the second threshold voltage. The rotation detection device according to any one of claims 1 to 3, further comprising differential output signal correction means for offsetting the differential output signal so as to approach each other. Instead of the second comparator,
Depending on the difference between the upper threshold voltage set to be higher than the first threshold voltage by a voltage value smaller than the voltage value corresponding to the amplitude value of the differential output signal and the differential output signal A third comparator that outputs one of the two signals;
According to the difference between the lower threshold voltage set to be smaller than the first threshold voltage by a voltage value smaller than the voltage value corresponding to the amplitude value of the differential output signal and the differential output signal And a fourth comparator that outputs one of the two signals.
The abnormality occurrence determination means is based on the output progress of the signal output from the first comparator, the signal output from the third comparator, and the signal output from the fourth comparator. The rotation detection device according to claim 1, wherein it is determined that the signal output from the first comparator is likely to include an abnormal signal.   The abnormality occurrence determination unit changes the first cumulative value in which the number of changes is accumulated for each change of the signal output from the first comparator and the change of the signal output from the third comparator. The number of changes is accumulated when the difference between the accumulated number and the third accumulated value is 2 or more, or for each change in the signal output from the first accumulated value and the fourth comparator. 6. The method according to claim 5, wherein when the difference from the fourth cumulative value is 2 or more, it is determined that there is a high possibility that an abnormal signal is included in the signal output from the first comparator. Rotation detection device.   The abnormality occurrence determination means determines whether the signal output from the first comparator has changed three or more times while the signal output from the third comparator has not changed, or whether the first comparator has changed. When the signal output from the fourth comparator changes three or more times while the signal output from the first comparator does not change, the signal output from the first comparator may include an abnormal signal The rotation detection device according to claim 5, wherein the rotation is determined to be high.   Based on the signal output from the first comparator and the signal output from the third comparator, the signal output from the first comparator by the abnormality occurrence determination means includes an abnormal signal. When it is determined that the possibility is high, the differential output signal is offset so that the amplitude center of the differential output signal approaches the upper threshold voltage, and the signal output from the first comparator and the When the abnormality occurrence determining means determines that the signal output from the first comparator is likely to contain an abnormal signal based on the signal output from the fourth comparator, the difference The differential output signal correction means for offsetting the differential output signal so that the amplitude center of the dynamic output signal approaches the lower threshold voltage is provided. Rotation detector   Based on the signal output from the first comparator and the signal output from the third comparator, the signal output from the first comparator by the abnormality occurrence determination means includes an abnormal signal. When it is determined that the possibility is high, and based on the signal output from the first comparator and the signal output from the fourth comparator, the abnormality occurrence determination means performs the first 6. A differential output signal correcting means for increasing the amplification factor of the differential amplifier when it is determined that the signal output from the comparator is likely to contain an abnormal signal. The rotation detection apparatus as described in any one of -7.   2. A notification means for notifying that when it is determined by the abnormality occurrence determination means that there is a high possibility that an abnormality signal is included in the signal output from the first comparator. The rotation detection apparatus as described in any one of -9.

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