JP7059893B2 - Detection signal processing circuit and rotation detection device equipped with this - Google Patents

Description

The present invention includes a sensor element that is arranged facing the rotating body and outputs a signal corresponding to the rotation of the rotating body, and has a detection signal processing having a function of adjusting an output signal from the sensor element. The present invention relates to a circuit and a rotation detection device including the circuit.

Conventionally, examples of this type of detection signal processing circuit include those described in Patent Document 1. This detection signal processing circuit is arranged so as to face the rotating body, and has two magnetic sensors that output a signal corresponding to the rotation of the rotating body, and a binarization circuit that binarizes the output signal from the magnetic sensor. It is provided with a forward / reverse determination circuit that determines the rotation direction of the rotating body based on the binarized pulse signal. Further, this detection signal processing circuit has a switching element that operates according to the rotation direction of the rotating body determined by the forward / reverse determination circuit, and outputs different signals according to the rotation direction of the rotating body by ECU (Electronic Control). Output to (abbreviation of Unit). This ECU includes a circuit for detecting the rotation speed of the rotating body and a circuit for detecting the rotation direction based on the output signal output from the detection signal processing circuit.

Japanese Unexamined Patent Publication No. 2005-249488

Here, the rotation detection device including this kind of detection signal processing circuit includes, for example, an IC including a detection signal processing circuit, a magnet, and a housing of a case-shaped member in which the IC is housed. In this type of rotation detection device, after processing the output signals output from the two magnetic sensors arranged facing the rotating body by the detection signal processing circuit, the detection signal is sent to the external ECU through the wiring provided in the housing. Is output to detect the rotation direction and the number of rotations of the rotating body.

However, due to problems with mounting accuracy in the manufacturing process of this type of rotation detection device, the relative position between the magnetic sensor and magnet in the mounted IC (hereinafter referred to as "mounting position") is planned in the design. It may deviate from the relative position of (hereinafter referred to as "design position"). When such a deviation between the mounting position of the magnetic sensor and the design position (hereinafter, simply referred to as “positional deviation”) occurs, the phase of the output signals from the two magnetic sensors becomes the phase of the planned output signal in the design. On the other hand, it shifts. When such a phase shift of the output signal occurs, the phase of the pulse signal generated based on the output signal also shifts, which causes a decrease in the detection angle accuracy.

Since the detection signal processing circuit described in Patent Document 1 does not include a circuit or the like for correcting the phase shift of the output signal due to the above-mentioned misalignment, the detection angle accuracy is lowered when the misalignment of the magnetic sensor occurs. Cannot be suppressed.

The present invention has been made in view of the above points, and even when the magnetic sensor is mounted at a position different from the design position, a detection signal capable of suppressing a decrease in detection angle accuracy due to the positional deviation can be suppressed. It is an object of the present invention to provide a processing circuit and a rotation detection device including the processing circuit.

In order to achieve the above object, the detection signal processing circuit according to claim 1 is a detection signal processing circuit (1) used in a rotation detection device for detecting the rotation of the rotating bodies (4) arranged to face each other. First binarization that performs binarization processing of the first magnetic sensor (51) and the second magnetic sensor (52) arranged opposite to the rotating body and the first output signal output from the first magnetic sensor. A circuit (61) and a second binarization circuit (62) that performs binarization processing of the second output signal output from the second magnetic sensor are provided. In such a configuration, the rotation detection device has a magnet, and the first magnetic sensor has a plurality of sensor units (511) that output a signal according to a change in the strength of the magnetic field. The first binarization circuit amplifies output signals output from a plurality of sensor units at a predetermined amplification factor, and outputs two gain adjustment units (611, 612) and two amplified signals. It has a signal synthesis unit (613) that synthesizes two amplified signals output from the gain adjustment unit and outputs one composite signal, and a binarization processing unit (614) that performs binarization processing of the combined signal. Therefore, the gain adjusting unit has a configuration in which the amplification factor can be changed according to the relative position between the first magnetic sensor constituting the rotation detection device and the magnet.

As a result, after the detection signal processing circuit including the binarization circuit for binarizing the output signal output from the magnetic sensor is incorporated in the rotation detection device, the amplification factor of the output signal in the binarization circuit is within a predetermined range. It will be a configuration that can be changed within. That is, the binarization circuit has a configuration in which the amplification factor in the gain adjusting unit can be appropriately adjusted even after being incorporated as a part of the rotation detection device.

Here, the present inventors have manufactured a rotation detection device using a detection signal processing circuit provided with a magnetic sensor, and when the relative position between the sensor unit and the magnet becomes a position different from the design position. We made a diligent study on measures to suppress the decrease in detection angle accuracy. As a result, the present inventors adjust the amplification factors of the two amplified signals that are the basis of the combined signal (hereinafter referred to as "gain adjustment") to obtain a pulse signal obtained by binarizing the combined signal. We have found that the phase can be adjusted within a predetermined range.

That is, the detection signal processing circuit provided with this binarization circuit is output from the binarization processing unit by adjusting the gain even when the magnetic sensor is mounted at a position different from the design position. The configuration is such that the phase of the pulse signal can be adjusted after the fact. Therefore, even if the magnetic sensor is mounted at a position different from the design position, the gain adjustment by the gain adjustment unit causes the binarization processing unit to output the output signal when the magnetic sensor is mounted at the design position. A pulse signal similar to the pulse signal output based on is output.

Therefore, even if the magnetic sensor is mounted at a position different from the design position, this detection signal processing circuit can be adjusted to output a pulse signal equivalent to the pulse signal when the position is not displaced. The configuration is such that a decrease in detection angle accuracy due to positional deviation can be suppressed.

Further, as in the invention of claim 4, by providing the above-mentioned detection signal processing circuit, the rotation detection device can suppress the decrease in the accuracy of the detection angle due to the positional deviation.

The reference numerals in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is a block diagram which shows an example of the rotation detection apparatus which includes the detection signal processing circuit of 1st Embodiment. It is a block diagram which shows the detection signal processing circuit of FIG. It is an example of an output signal and a pulse signal of two magnetic sensors in a state where a rotating body is rotating forward or reverse, (a) is a figure which shows the normal rotation state, (b) is a figure which shows the reverse rotation state. It is a figure which shows an example of the mounting position of a magnetic sensor and the pulse signal which is output corresponding to this in the conventional detection signal processing circuit, (a) is the position when the position shift has not occurred, (b) is the position. It is a figure which shows the case where the deviation occurs. It is a figure which shows the outline of the 1st magnetic sensor and the 1st binarization circuit of FIG. It is a figure which shows an example of the output signal, the composite signal and the pulse signal when the 1st magnetic sensor of FIG. 2 is mounted at a design position. FIG. 2 is a diagram showing an example of an output signal, a composite signal, and a pulse signal when the first magnetic sensor of FIG. 2 is mounted at a position deviated from the aim and gain adjustment is not performed. FIG. 2 is a diagram showing an example of an output signal, a composite signal, and a pulse signal when the gain adjustment is performed when the first magnetic sensor of FIG. 2 is mounted at a position deviated from the aim. It shows the gain adjustment of the output signal and the change of the pulse signal due to this, (a) is the gain adjustment in the first gain adjustment unit, (b) is the gain adjustment in the second gain adjustment unit, (c). Is a diagram showing a change in a pulse signal obtained by synthesizing (a) and (b) and binarizing them. It is a figure which shows the structural example of the gain adjustment part. It is a block diagram which shows the other connection example of a detection signal processing circuit and an ECU.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the parts that are the same or equal to each other will be described with the same reference numerals.

(First Embodiment)
The detection signal processing circuit 1 of the first embodiment will be described. The detection signal processing circuit 1 of the present embodiment is suitable for being applied to various rotation detection devices such as a cam angle sensor and a crank angle sensor, but other rotation detection devices such as an engine rotation sensor and a wheel speed sensor. Can also be applied to.

[Configuration of rotation detection device]
First, the rotation detection device including the detection signal processing circuit 1 of the present embodiment will be described with reference to FIGS. 1 and 2, but various configurations of known rotation detection devices are adopted except for the detection signal processing circuit 1. Therefore, in this specification, components other than the detection signal processing circuit 1 will be briefly described.

1 and 2 show the rotation direction of the rotating body 4, which will be described later, and as an example, the clockwise rotation direction in FIGS. 1 and 2 is defined as “forward rotation”, and the counterclockwise rotation direction is defined as “counterclockwise rotation”. The term "reversal" is used, but the present invention is not limited to this, and the directions of normal rotation and reverse rotation may be changed as appropriate.

In the rotation detection device including the detection signal processing circuit 1 of the present embodiment, for example, as shown in FIG. 1, the detection signal processing circuit 1 is arranged to face the rotating body 4, and the detection signal processing circuit 1 is wired 31 to 31 to It is connected to the external ECU 2 via 33. In this rotation detection device, for example, the detection signal processing circuit 1 externally outputs a pulse signal according to the rotation direction and the number of rotations of the rotating body corresponding to the rotation of the rotating body 4 including the peak portion 41 and the valley portion 42. It is configured to output to the ECU 2.

As shown in FIG. 2, the detection signal processing circuit 1 includes, for example, two magnetic sensors 51 and 52, two binarization circuits 61 and 62, a forward / reverse determination circuit 71, and a constant voltage circuit 72. It includes a current circuit 73, a constant current source 74, a switch 75, and a transistor 76.

In the detection signal processing circuit 1, two magnetic sensors 51 and 52 arranged to face the rotating body 4 output an output signal corresponding to the rotation of the rotating body, and the binarization circuits 61 and 62 2 output the output signal. It is configured to perform binarization processing. The detection signal processing circuit 1 processes the pulse signal binarized by the binarization circuits 61 and 62 by the forward / reverse determination circuit 71, and transfers the rotation number signal corresponding to the rotation number of the rotating body 4 to the signal line 32. Output. The detection signal processing circuit 1 determines the rotation direction of the rotating body 4 by the forward / reverse determination circuit 71, and opens and closes the switch 75 according to the rotation direction to change the current consumption in the detection signal processing circuit 1. Then, the potential V1 on the ECU 2 side connected via the power supply line 31 is changed. This potential change of the potential V1 corresponds to a rotation direction signal according to the rotation direction of the rotating body 4, and the detection signal processing circuit 1 outputs a rotation direction signal to the ECU 2 according to the rotation direction of the rotating body 4. Is the result of. The detection signal processing circuit 1 has, for example, the above configuration, and outputs various output signals corresponding to the rotation of the rotating body 4 toward the ECU 2. The outline of the detection signal processing circuit 1 is as described above, and details will be described later.

As shown in FIG. 1, the ECU 2 is configured to include, for example, a power supply Vcc, a rotation direction signal processing circuit 21, a rotation number signal processing circuit 22, a potential detection resistor R1, and a pull-up resistor R2. .. In the ECU 2, the power supply Vcc and the rotation direction signal processing circuit 21 are connected to the detection signal processing circuit 1 via the power supply line 31, and the current is supplied to the detection signal processing circuit 1 from the power supply Vcc. In the ECU 2, the rotation speed signal processing circuit 22 is connected to the detection signal processing circuit 1 via the signal line 32, and the internal ground portion is connected to the detection signal processing circuit 1 via the ground line 33. In the ECU 2, as shown in FIG. 1, a potential detection resistor R1 is connected in series between the power supply Vcc and the power supply line 31, and the power supply Vcc and the signal line 32 are connected, and a pull-up resistor is connected between them. R2 is connected in series.

The ECU 2 calculates the rotation speed of the rotating body 4 by processing the rotation speed signal from the detection signal processing circuit 1 by the rotation speed signal processing circuit 22. When the potential V1 changes due to the detection signal processing circuit 1 adjusting the current value according to the rotation direction of the rotating body 4, the ECU 2 transmits the potential change of the potential V1 to the rotation direction signal processing circuit 21. It is said to be composed. The ECU 2 detects the rotation direction of the rotating body 4 by processing the potential change of the potential V1 in the rotation direction signal processing circuit 21.

For example, with the above configuration, rotation detection can detect the rotation speed and rotation direction of the rotating body 4 while the detection signal processing circuit 1 and the ECU 2 are connected by three wirings 31 to 33. It is said to be a device. The above is the basic configuration of the rotation detection device.

The rotating body 4 is, for example, a component such as a gear constituting a vehicle such as an automobile, is made of a magnetic material, and has a shape in which a mountain portion 41 and a valley portion 42 are formed at a predetermined pitch. However, it is not limited to this.

[Configuration of detection signal processing circuit]
Next, the detection signal processing circuit 1 and its components will be described with reference to FIG.

The magnetic sensors 51 and 52 have, for example, an arbitrary magnetoresistive element, are arranged to face the rotating body 4 as shown in FIG. 2, and respond to changes in the strength of the magnetic field accompanying the rotation of the rotating body 4. It is configured to output a signal.

Specifically, the magnetic sensors 51 and 52 are, for example, a distance obtained by adding or subtracting a predetermined distance (for example, a distance of 1/4 of the pitch) to a distance obtained by multiplying the pitch of the mountain portion 41 of the rotating body 4 by an integer. Are placed apart from each other. As shown in FIGS. 3A and 3B, for example, the magnetic sensors 51 and 52 have a sinusoidal shape having a predetermined phase difference (1/4 phase difference in the case of the above-mentioned arrangement example). Output the output signal.

Hereinafter, for the sake of simplification of the description, as shown in FIGS. 3 (a) and 3 (b), the output signal of the first magnetic sensor 51 is referred to as a “first output signal” for convenience, and the second magnetism is used. The output signal of the sensor 52 is referred to as a "second output signal". Further, as shown in FIGS. 3A and 3B, the pulse signal obtained by binarizing the first output signal is referred to as a "first pulse signal", and the second output signal is binary. The pulse signal obtained by the conversion is referred to as a "second pulse signal". Further, in FIGS. 3 (a) and 3 (b), the first output signal and the first pulse signal are shown by a solid line, and the second output signal and the second pulse signal are shown by a broken line for convenience. Therefore, the high level and the low level of the two pulse signals are shown in a staggered state.

In the present embodiment, the first magnetic sensor 51 is used for detecting the rotation speed and the angle of rotation of the rotating body 4, and the second magnetic sensor 52 is used together with the first magnetic sensor 51 for detecting the rotation direction of the rotating body 4. An example will be described. The first output signal from the first magnetic sensor 51 is transmitted to the first binarization circuit 61, and the second output signal from the second magnetic sensor 52 is transmitted to the second binarization circuit 62. ..

Here, in the magnetic sensors 51 and 52, when the detection signal processing circuit 1 is incorporated as a part of the rotation detection device, the relative position of the rotation detection device with the magnet is the design position due to a problem of mounting accuracy or the like. May be placed in a different position. In this case, the phase of the output signals of the magnetic sensors 51 and 52 is shifted, and the phase of the pulse signal generated based on the output signal is also shifted, which causes a decrease in the detection angle accuracy. In at least one of the binarization circuits 61 and 62, when such a positional deviation of the magnetic sensors 51 and 52 occurs, the phase of the generated pulse signal is deviated from the phase of the pulse signal planned by design. It is configured to suppress the occurrence.

The positional shift at the time of mounting the magnetic sensors 51 and 52, the phase shift of the output signal and its influence thereof, and the mitigation of the phase shift influence of the output signal by the binarization circuit 61 or 62 will be described in detail later.

The binarization circuits 61 and 62 convert the sinusoidal output signal output from the magnetic sensors 51 and 52 into a rectangular binary output pulse signal depending on whether or not the set predetermined threshold value is exceeded. It is configured to perform binarization processing. At least one of the binarization circuits 61 and 62 determines the amplification factor of the output signal from the first magnetic sensor 51 or the second magnetic sensor 52 according to the relative position between the magnetic sensors 51 and 52 and the magnet. The configuration is adjustable within the range.

In the present embodiment, the first binarization circuit 61 has a configuration in which the amplification factor of the output signal of the first magnetic sensor 51 can be adjusted within a predetermined range, and the second binarization circuit 62 has the second magnetism. An example in which the amplification factor of the output signal of the sensor 52 is fixed to a predetermined value will be described. The details of the configuration and operation of the first binarization circuit 61 will be described later.

The first binarization circuit 61 generates a pulse signal based on the output signal from the first magnetic sensor 51, and outputs the pulse signal to the forward / reverse determination circuit 71 and the transistor 76. The second binarization circuit 62 generates a pulse signal based on the output signal from the second magnetic sensor 52, and outputs the pulse signal to the forward / reverse determination circuit 71.

The forward / reverse determination circuit 71 determines whether the rotation direction of the rotating body 4 is forward rotation or reverse rotation based on the pulse signals from the binarization circuits 61 and 62, and outputs an electric signal according to the rotation direction. It is said to be composed. The determination of the rotation direction of the rotating body 4 by the forward / reverse determination circuit 71 is not limited, but is performed by, for example, the following method.

For example, as shown in FIG. 3A, when the rotating body 4 is rotating in the normal direction, the magnetic sensors 51 and 52 output the first output signal and the second output signal having a predetermined phase difference. .. Depending on whether the voltage of the first output signal and the second output signal exceeds an arbitrary threshold value, the binarization circuits 61 and 62 perform binarization processing (high level when the threshold value is exceeded, high level when the threshold value is not reached). Is set to a low level, etc.), so that two pulse signals having a predetermined phase difference can be obtained.

On the other hand, when the rotating body 4 is reversed, the order of changes in the magnetic field strength between the rotating body 4 and the first magnetic sensor 51 and between the rotating body 4 and the second magnetic sensor 52 changes. Therefore, for example, as shown in FIG. 3B, the first output signal and the second output signal are output from the magnetic sensors 51 and 52 in a different order from the case of normal rotation. Therefore, the two pulse signals obtained by binarizing these output signals by the binarization circuits 61 and 62 are also in a different state from the normal rotation state.

The forward / reverse determination circuit 71 utilizes the fact that the relationship between the first pulse signal and the second pulse signal output from the binarization circuits 61 and 62 is different between the forward rotation and the reverse rotation, and the rotating body 4 has a rotating body 4. It is determined whether the rotation is normal or reverse. For example, the rotation direction of the rotating body 4 can be determined depending on whether the high level of the first pulse signal precedes or lags the second pulse signal. The determination result by the forward / reverse determination circuit 71 is used for opening / closing the switch 75, which will be described later.

The constant voltage circuit 72 internally processes the potential supplied via the power supply line 31, and is predetermined to the magnetic sensors 51, 52, the binarization circuits 61, 62, the forward / reverse determination circuit 71, and the constant current circuit 73. Apply voltage. The constant voltage circuit 72 may have an arbitrary configuration as long as it has a circuit configuration capable of processing the potential supplied from the external power supply of the detection signal processing circuit 1 to a predetermined constant voltage.

The constant current circuit 73 has an arbitrary circuit configuration that generates a predetermined constant current based on a predetermined constant voltage applied from the constant voltage circuit 72.

As shown in FIG. 2, the constant current source 74 is connected to the power supply line 31 and supplies a constant current to the ground line 33 when the switch 75 is closed. The constant current source 74 is configured to be a current mirror circuit together with the constant current circuit 73 so that the same constant current as the constant current generated by the constant current circuit 73 is generated, for example.

The switch 75 is a switching element such as a transistor, and switches the current from the constant current source 74 to the ground line 33 based on the output of the forward / reverse determination circuit 71. When the switch 75 is closed, a constant current from the constant current source 74 is supplied to the ground line 33, and as shown in FIG. 1, the switch 75 is grounded to the ground potential portion inside the ECU 2. The switch 75 is used to change the current consumption in the detection signal processing circuit 1 by opening and closing, and to change the potential of the potential V1 of the ECU 2 connected via the power supply line 31.

As shown in FIG. 2, the transistor 76 is, for example, a bipolar transistor, the base is connected to the first binarization circuit 61, the collector is connected to the signal line 32, and the emitter is connected to the ground line 33. .. The rotation speed signal from the first binarization circuit 61 supplied to the base of the transistor 76 is transmitted to the rotation speed signal processing circuit 22 of the ECU 2 via the signal line 32.

The above is the basic configuration of the detection signal processing circuit 1 of the present embodiment. The detection signal processing circuit 1 has a first binarization in which the amplification factor of the output signal from the first magnetic sensor 51 can be changed according to the relative position between the first magnetic sensor 51 and the magnet of the rotation detection device. The circuit 61 may be provided. That is, the detection signal processing circuit 1 may be provided with the first binarization circuit 61 and may be configured to output the rotation speed signal and the rotation direction signal to the ECU 2, and is not limited to the above example and is appropriately configured. May be changed.

[Position shift in mounting magnetic sensor]
Next, in the conventional detection signal processing circuit (hereinafter, simply referred to as “conventional detection signal processing circuit”) that does not include the first binarization circuit 61, the position shift in the mounting of the first magnetic sensor 51 and the position deviation thereof. The decrease in detection angle accuracy due to the above will be described with reference to FIGS. 4 (a) and 4 (b).

In FIGS. 4A and 4B, an outline of the arrangement of the magnet and the first magnetic sensor 51 in the rotation detection device and the output signal from the first magnetic sensor 51 are binarized by a conventional binarization circuit. The output pulse signal is shown. Further, in FIG. 4B, in order to help understanding, the case where the arrangement of the first magnetic sensor 51 is the design position (no positional deviation) and the case where the position is different from the design position (there is a positional deviation) are also described. The first magnetic sensor 51 and the pulse signal in the former case are shown by broken lines.

When the rotation detection device is configured by using the conventional detection signal processing circuit and the first magnetic sensor 51 including the plurality of sensor units 511 is arranged at the design position, for example, as shown in FIG. 4A. A predetermined pulse signal is output from the conventional binarization circuit. Hereinafter, the pulse signal output when the first magnetic sensor 51 is arranged at the design position is referred to as a “design pulse signal” for convenience. The sensor unit 511 is, for example, a magnetoresistive element, and in the example of FIG. 4, three are arranged in the first magnetic sensor 51, but at least two may be arranged.

However, when incorporating the conventional detection signal processing circuit into the rotation detection device, due to a problem in mounting accuracy in the manufacturing process of the rotation detection device, for example, as shown in FIG. 4B, the first magnetic sensor 51 is the subject. It may be displaced from the design position in the rotation detector. In this case, the relative position between the magnet and the first magnetic sensor 51 is different from the relative position when the first magnetic sensor 51 is arranged at the design position. That is, since the relative position between the sensor unit 511 and the magnet in the first magnetic sensor 51 is different from the designed one, the change in the magnetic field strength when the rotating body 4 rotates is also different from the design. It becomes a state.

As a result, as shown in FIG. 4B, when the position shift of the first magnetic sensor 51 occurs, the conventional binarization circuit has a pulse having a phase difference (phase shift) from the design pulse signal. Output a signal. When a pulse signal having a phase difference from the design pulse signal is output, the rotation angle and rotation number of the rotating body 4 are not accurately reflected, and the detection angle accuracy is lowered.

Therefore, as a result of diligent studies on suppressing the decrease in the detection angle accuracy, the present inventors adjusted the pulse within a predetermined range of the amplification factor of the output signal, which is the basis for generating the pulse signal. We have found that the phase of the signal can be adjusted within a predetermined range. The detection signal processing circuit 1 including the first binarization circuit 61 has been invented in this way.

[Structure of the first binarization circuit]
Next, with reference to FIG. 5, regarding the first binarization circuit 61 having a configuration in which the output signal from the first magnetic sensor 51 can be adjusted ex post facto even when the position shift occurs. explain.

In the first binarization circuit 61, for example, as shown in FIG. 5, a sinusoidal output signal is transmitted from three sensor units 511 arranged in the first magnetic sensor 51. The first binarization circuit 61 includes two gain adjustment units 611 and 612, a signal synthesis unit 613, and a binarization processing unit 614, and is relative to the magnet of the first magnetic sensor 51 and the rotation detection device. The amplification factor in the gain adjusting units 611 and 612 can be changed according to the position.

Hereinafter, for the sake of simplification of the description, as shown in FIG. 5, the three sensor units 511 are referred to as "A sensor unit 511", "B sensor unit 511", and "C sensor unit 511", respectively, for convenience. Refer to. Further, in FIG. 5, the voltage of the amplified signal output from the first gain adjusting unit 611, which will be described later, is referred to as “ _VCB ”, and the voltage of the amplified signal output from the second gain adjusting unit 612 is referred to as “ _VAB ”. It is written as. Further, in FIG. 5, the voltage of the combined signal output from the signal synthesis unit 613 is referred to as “V ₁ ”, and the voltage of the pulse signal output from the binarization processing unit 614 is described as “V ₂ ”. There is.

The gain adjusting units 611 and 612 are differential amplifier circuits that amplify the difference in the output signal from the sensor unit 511 within a predetermined range and output the amplified signal to the signal synthesis unit 613.

The first gain adjusting unit 611 includes a resistor R3, an operational amplifier OP2, and a variable resistor VR1 as shown in FIG. 5, for example. For example, the first gain adjusting unit 611 refers to the output signal from the sensor unit 511 of B as a reference, and sets the difference between the output signal from the sensor unit 511 of C and the output signal from the sensor unit 511 of B within a predetermined range. It is configured to output the amplified signal amplified by the amplification factor of.

Specifically, as shown in FIG. 5, the sensor unit 511 of B is connected to the non-inverting input terminal of the operational amplifier OP1 constituting the voltage follower. The voltage output from the operational amplifier OP1 is supplied to the inverting input terminal of the first gain adjusting unit 611 via the resistor R3, and is also supplied to the inverting input terminal of the second gain adjusting section 612 via the resistor R4. As shown in FIG. 5, the sensor unit 511 of C is connected to the non-inverting input terminal of the operational amplifier OP2 of the first gain adjusting unit 611.

As shown in FIG. 5, the first gain adjusting unit 611 has an operational amplifier OP2 in which an inverting input terminal and an output terminal are connected via a variable resistor VR1. Therefore, the first gain adjusting unit 611 is configured to be able to appropriately change the amplification factor of the output signal from the sensor unit 511 of C by adjusting the resistance value of the variable resistor VR1 within a predetermined range. The amplified signal output from the first gain adjusting unit 611 is transmitted to the signal combining unit 613 via the resistor R5.

The second gain adjusting unit 612 includes a resistor R4, an operational amplifier OP3, and a variable resistor VR2, and the output signal from the sensor unit 511 of A is within a predetermined range with reference to the output signal from the sensor unit 511 of B. It is configured to output the amplified signal amplified by the amplification factor of.

Specifically, as shown in FIG. 5, in the operational amplifier OP3, an output signal from the sensor unit 511 of B is input to the inverting input terminal via the operational amplifier OP1, and the sensor unit 511 of A is input to the non-inverting input terminal. The output signal from is input. Further, in the operational amplifier OP3, its inverting input terminal and output terminal are connected via a variable resistor VR2. Therefore, the second gain adjusting unit 612 is configured to be able to appropriately change the amplification factor of the output signal from the sensor unit 511 of A by adjusting the resistance value of the variable resistor VR2 within a predetermined range. The amplified signal output from the second gain adjusting unit 612 is transmitted to the signal combining unit 613 via the resistor R6.

The resistance values of the variable resistances VR1 and VR2 are appropriately determined according to the relative positions of the first magnetic sensor 51 and the magnet of the rotation detection device. More on this later.

The signal synthesis unit 613 is configured to synthesize two amplified signals output from the gain adjustment units 611 and 612, and output the combined signal to the binarization processing unit 614. The signal synthesis unit 613 includes, for example, an operational amplifier OP4 and a resistance R7, as shown in FIG.

As shown in FIG. 5, in the operational amplifier OP4, the amplification signal from the first gain adjustment unit 611 and the amplification signal from the second gain adjustment unit 612 are superimposed and input to the inverting input terminal. In the operational amplifier OP4, a predetermined constant voltage V _REF is input to the non-inverting input terminal from an arbitrary circuit (not shown), and the inverting input terminal and the output terminal are connected via a resistor R7. As a result, the signal synthesis unit 613 is configured to synthesize the two amplified signals from the gain adjusting units 611 and 612 and output the combined signal amplified at a predetermined amplification factor.

Unlike the gain adjusting units 611 and 612, the signal synthesizing unit 613 has a fixed resistance value of the resistor R7, and the amplification factor thereof is fixed.

The binarization processing unit 614 is, for example, an operational amplifier comparator CMP, binarizes the combined signal output from the signal synthesis unit 613, and outputs a pulse signal. In the operational amplifier comparator CMP, a predetermined reference voltage _VTH is input to the + input terminal from an arbitrary circuit (not shown), and the combined signal from the signal synthesizer 613 is input to the-input terminal.

The pulse signal output from the binarization processing unit 614 is transmitted to the forward / reverse determination circuit 71 and the transistor 76, for example, as shown in FIG.

The above is the basic configuration of the first binarization circuit 61. In the second binarization circuit 62, in the present embodiment, the first is a point other than the point where the variable resistors VR1 and VR2 in the gain adjusting units 611 and 612 are replaced with resistors having a fixed resistance value. It has the same configuration as the binarization circuit 61 of.

[Effect of the first binarization circuit 61]
Next, the effect of the first binarization circuit 61 will be described with reference to FIGS. 6 to 10.

In FIGS. 6 to 8, the auxiliary line for expressing the phase shift is shown by a two-dot chain line. In FIGS. 7 and 8, in order to make it easy to understand the difference between the case where the position shift occurs and the case where the position shift does not occur, the combined signal γ ₀ and the pulse signal δ ₀ when the position shift does not occur are shown by broken lines. There is. Further, in FIG. 7, for easy viewing, the pulse signal δ ₀ and the pulse signal δ ₁ when the gain is not adjusted when the position shift occurs are shown by shifting them to positions where the high level and low level signals do not overlap. ing. FIG. 8 shows a case where the amplification factor in the first gain adjustment unit 611 is adjusted in the same situation as in FIG. 7, and in order to make the adjustment of the amplification factor (gain adjustment) described later easy to understand, before the gain adjustment. The amplified signal α ₁ is shown by a broken line. Further, in FIG. 8, in order to help the understanding of the effect of the gain adjustment, the combined signal γ ₀ is shown by a broken line and the combined signal γ ₁ is shown by a alternate long and short dash line.

First, the generation of the pulse signal by the first binarization circuit 61 when the first magnetic sensor 51 is arranged at the design position of the rotation detection device will be described with reference to FIG.

At this time, for example, as shown in FIG. 6, the first gain adjusting unit 611 outputs the output (amplification) signal α ₀ based on the output signals from the three sensor units 511 of the first magnetic sensor 51, and the second gain. The adjusting unit 612 outputs the output (amplification) signal β ₀ . After that, the signal synthesis unit 613 synthesizes these output signals α ₀ and β ₀ to generate a combined signal γ ₀ . Then, the binarization processing unit 614 performs binarization processing on the combined signal γ ₀ depending on whether or not the voltage exceeds a predetermined threshold value, and generates a pulse signal δ ₀ . Since the pulse signal δ ₀ in the case where this positional deviation does not occur coincides with the design pulse signal, it can be referred to as a “design pulse signal”.

Subsequently, when the first magnetic sensor 51 is arranged at a position different from the design position of the rotation detection device (when the position shift occurs), the gain adjusting unit 611 in the first binarization circuit 61, The pulse signal generation when the amplification factor in 612 is not adjusted will be described with reference to FIG. 7.

When the amplification factor in the gain adjustment units 611 and 612 remains the same as the amplification factor in the case where the position deviation does not occur, the gain adjustment units 611 and 612 output (as shown in FIG. 7). Amplification) Signals α ₁ and β ₁ are output. Specifically, the amplification signal α ₁ is output from the first gain adjustment unit 611, and the amplification signal β ₁ is output from the second gain adjustment unit 612. At this time, since the relative positions of the first magnetic sensor 51 and the magnet deviate from the design, the gain adjusting units 611 and 612 have a phase difference with the amplified signals α ₀ and β ₀ as shown in FIG. Amplification signals α ₁ and β ₁ are output. That is, the amplified signals α ₁ and β ₁ are out of phase with the amplified signals α ₀ and β ₀ . The phase shift between the amplified signals α ₁ and β ₁ and the amplified signals α ₀ and β ₀ changes according to the degree of the positional shift of the first magnetic sensor 51.

These amplified signals α ₁ and β ₁ are synthesized by the signal synthesizing unit 613. As a result, the composite signal γ ₁ output from the signal synthesis unit 613 has a phase shift from the composite signal γ ₀ when the position shift does not occur. As shown in FIG. 7, the pulse signal δ ₁ obtained by binarizing the combined signal γ ₁ with the binarization processing unit 614 has a phase with the pulse signal δ ₀ (design pulse signal) when no positional deviation occurs. Will shift.

Such a phase shift of the pulse signal causes a decrease in the detection angle accuracy. Therefore, it is desirable to suppress the positional deviation of the magnetic sensor when manufacturing the rotation detection device, but it leads to an increase in the manufacturing cost and it is difficult to completely prevent the positional deviation.

Therefore, as a result of diligent studies on the suppression of the phase shift of the pulse signal in the state where the position shift remains, the present inventors adjusted the amplification factor of the amplified signal which is the basis of the synthesized signal to obtain the pulse. We have found that the phase shift of the signal can be suppressed.

Next, when the position of the first magnetic sensor 51 is displaced, the pulse signal when the amplification factors of the gain adjusting units 611 and 612 are adjusted within a predetermined range by the first binarization circuit 61. The generation will be described with reference to FIG.

When the gain is adjusted by the first gain adjusting unit 611, for example, as shown in FIG. 8, the amplified signal α ₁ does not change in phase, but the voltage of the signal changes, and the amplified signal α ₂ and the like. It becomes a waveform. When the amplified signal α ₂ after the gain adjustment and the amplified signal β ₁ from the second gain adjusting unit 612 are combined, the combined signal changes from γ ₀ to γ ₂ , for example, as shown in FIG. The combined signal γ ₂ after the gain adjustment has a waveform different from that of the combined signal γ ₁ before the gain adjustment when the position of the first magnetic sensor 51 is displaced, and the phase of the region where the voltage is equal to or lower than a predetermined threshold is combined. It will deviate from the signal γ ₁ .

The phase of the region where the voltage is equal to or lower than a predetermined threshold value (hereinafter referred to as “the region below the threshold value”) in the combined signal γ ₂ after gain adjustment changes depending on the amplification factors of the amplification signals α ₁ and β ₁ . As a result, the pulse signal δ ₂ obtained by binarizing the combined signal γ ₂ is out of phase with the pulse signal δ ₁ before the gain adjustment. In other words, as shown in FIG. 8, the phase of the region below the threshold of the combined signal γ ₂ is controlled by adjusting the amplification factors of the amplified signals α ₁ and β ₁ to bring it closer to the phase of the region below the threshold of the combined signal γ ₀ . , The actual pulse signal δ ₂ can be brought closer to the design pulse signal δ ₀ .

Specifically, the gain adjusting units 611 and 612 amplify the amplification signals α and β stepwise within a predetermined range, for example, as shown by the white arrows in FIGS. 9A and 9B. .. The resistivity within this predetermined range changes the resistance values of the variable resistors VR1 and VR2 shown in FIG. 5, and changes the ratio of the variable resistors VR1 and the resistance R3, or the resistance ratio of the variable resistors VR2 and the resistance R4. It can be adjusted by doing.

Note that FIGS. 9 (a) to 9 (c) show an example in which the amplification factor is adjusted in four stages in each of the gain adjusting units 611 and 612 for easy viewing, but the number of amplification factor adjusting stages is shown. , Not limited to the example shown in FIG. 9, and may be changed as appropriate.

That is, the waveform of the synthesized signal in the signal synthesis unit 613 can be adjusted by adjusting the amplification factor in the gain adjustment units 611 and 612, and as a result, for example, as shown by the white arrow in FIG. 9C, the binary value is obtained. The phase of the pulse signal generated by the binarization unit 614 can be adjusted.

Therefore, even if the position of the first magnetic sensor 51 is displaced, the phase difference between the pulse signal δ ₂ and the pulse signal δ ₀ is set to a predetermined state or less by adjusting the amplification factor by the gain adjusting units 611 and 612. Therefore, it is possible to suppress a decrease in the detection angle accuracy.

The "state in which the phase difference is equal to or less than a predetermined value" as used herein means that the phase difference between the pulse signal and the design pulse signal when the gain is not adjusted when the position of the first magnetic sensor 51 is displaced is due to the gain adjustment. It means that it is in a smaller state.

Here, the variable resistor VR1 of the gain adjusting unit 611 is configured as shown in FIG. 10, for example. As shown in FIG. 10, the variable resistance VR1 is connected in parallel with the resistors R8, R9, R10, R11, R12, R13 connected in series and the resistors R8 to R12, respectively, and is composed of an actuator element or the like. It has 5 switches. The variable resistance VR1 is a resistance obtained by adding the resistance value of the resistance R13 or the resistance value of the resistance R13 to at least one of the five resistances R8 to R12 by switching ON / OFF of each of the five switches. It becomes a value. As a result, the gain adjusting unit 611 has a configuration in which the resistance ratio between the resistor R3 and the variable resistor VR1, that is, the amplification factor can be changed within a predetermined range. Further, the variable resistor VR2 of the gain adjusting unit 612 has the same configuration as the variable resistor VR1.

For the variable resistors VR1 and VR2, for example, setting data for ON / OFF of the switch is stored in advance in a non-volatile memory (not shown), and the setting data is read and executed by a CPU (not shown) to determine the resistance value. Can be changed within the range of. The resistance values of the variable resistances VR1 and VR2 are determined for each detection signal processing circuit 1 mounted on the rotation detection device according to the relative position between the first magnetic sensor 51 and the magnet. The resistance values of the variable resistors VR1 and VR2 are fixed after being determined as described above, and it is not necessary to perform dynamic control.

In the example of FIG. 10, the variable resistance VR1 has a configuration in which the resistance value can be changed in 32 steps depending on the ON / OFF state of each of the five switches, but the resistance and the switch are not limited to this example. The number of and the resistance value of each resistor are changed as appropriate. This also applies to the variable resistor VR2.

In the present embodiment, unlike the first binarization circuit 61, the second binarization circuit 62 has a configuration in which the amplification factor of the output signal from the second magnetic sensor 52 cannot be changed. This is because the influence of the positional deviation is small on the detection accuracy of the rotating body 4 in the rotation direction.

Specifically, when the position shift of the first magnetic sensor 51 occurs, the position shift of the second magnetic sensor 52 also occurs to the same extent as that of the first magnetic sensor 51, and the output signals from the magnetic sensors 51 and 52 The phase shift of each of the two pulse signals generated based on the above is also generated to the same extent. However, even if the phase shifts of the two pulse signals occur to the same extent, there is no change in which of these pulse signals precedes, and there is no particular problem in detecting the rotation direction of the rotating body 4. Therefore, the second binarization circuit 62 may have a configuration in which the amplification factor of the output signal from the second magnetic sensor 52 cannot be changed. Of course, the second binarization circuit 62 may have the same configuration as the first binarization circuit 61.

According to the present embodiment, even if the position of the first magnetic sensor 51 is displaced, the amplification factor of the output signal from the first magnetic sensor 51 can be adjusted within a predetermined range. Since the circuit 61 is provided, it is possible to suppress the phase shift of the pulse signal due to the positional shift. Therefore, the detection signal processing circuit 1 can suppress a decrease in the detection angle accuracy even when the position of the first magnetic sensor 51 is still displaced.

Further, the rotation detection device provided with the detection signal processing circuit 1 is configured to be able to suppress a decrease in detection angle accuracy after the fact even if the position of the first magnetic sensor 51 is still displaced.

(Other embodiments)
The detection signal processing circuit and the rotation detection device provided with the detection signal processing circuit shown in each of the above-described embodiments show an example of the present invention, and are not limited to the above-mentioned first embodiment, and claims for a patent. It can be changed as appropriate within the range described in.

(1) For example, in the first embodiment described above, an example in which the detection signal processing circuit 1 is connected to the ECU 2 via three wirings 31 to 33 has been described, but the present invention is not limited to this, and for example, as shown in FIG. In addition, it may be connected to the ECU 2 via four wires 31 to 34. In this case, in the rotation detection device, for example, the output signal from the forward / reverse determination circuit 71 is transmitted to the rotation direction signal processing circuit 21 via the first signal line 32, and the pulse from the first binarization circuit 61 is transmitted. The signal is configured to be transmitted to the rotation speed signal processing circuit 22 via the second signal line 34. Even with such a configuration, the effect of suppressing the phase shift of the pulse signal due to the positional shift of the magnetic sensors 51 and 52 by the detection signal processing circuit 1 is not impaired.

(2) In the above first embodiment, an example in which the detection signal processing circuit 1 is configured by using the first magnetic sensor 51 including three sensor units 511 has been described, but the present invention is not limited to this, and the first magnetic sensor is not limited thereto. 51 may have at least two sensor units 511.

For example, when the number of the sensor units 511 is only two, the first magnetic sensor 51 has a configuration in which the sensor unit 511 of B shown in FIG. 5 is replaced with a ground unit having a ground potential. Even in such a case, the detection signal processing circuit 1 is configured to be able to output a signal corresponding to the rotation of the rotating body 4 based on the output signals from the sensor unit 511 of A and the sensor unit 511 of C.

1 Detection signal processing circuit 51, 52 Magnetic sensor 511 Sensor unit 61, 62 Binarization circuit 611, 612 Gain adjustment unit 613 Signal synthesis unit 614 Binarization processing unit

Claims (4)

A detection signal processing circuit (1) used in a rotation detection device that detects the rotation of rotating bodies (4) arranged opposite to each other.
The first magnetic sensor (51) and the second magnetic sensor (52), which are arranged to face the rotating body,
A first binarization circuit (61) that performs binarization processing of the first output signal output from the first magnetic sensor, and
A second binarization circuit (62) that performs binarization processing of the second output signal output from the second magnetic sensor is provided.
The rotation detection device has a magnet and is made of a magnet.
The first magnetic sensor has a plurality of sensor units (511) that output signals according to changes in the strength of the magnetic field.
The first binarization circuit has two gain adjusting units (611, 612) that amplify output signals output from the plurality of sensor units at a predetermined amplification factor and output the amplified amplified signals, and two. A signal synthesis unit (613) that synthesizes two of the amplified signals output from the gain adjustment unit and outputs one combined signal, and a binarization processing unit (614) that performs binarization processing of the combined signal. ) And have
The gain adjusting unit is a detection signal processing circuit having a configuration in which the amplification factor can be changed according to the relative position between the first magnetic sensor and the magnet constituting the rotation detection device. The gain adjusting unit is a differential amplifier circuit having variable resistors (VR1, VR2), and has a configuration in which the amplification factor can be changed by changing the resistance value of the variable resistor. The detection signal processing circuit according to claim 1. When the rotation detection device is configured by using the first magnetic sensor and the second magnetic sensor,
The variable resistance is
When the design pulse signal output by the binarization processing unit when the plurality of sensor units are arranged in a design and the arrangement in which the plurality of sensor units are different from the design arrangement. The detection signal processing circuit according to claim 2, wherein the resistance value is determined so that the phase difference between the actual pulse signal output by the binarization processing unit and the pulse signal is equal to or less than a predetermined value. A rotation detection device comprising the detection signal processing circuit according to any one of claims 1 to 3.

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