Direction of rotation detector and method of detecting direction of rotation

Abstract

To detect the direction of rotation of a rotor without using a rotor with special magnetization pattern and based on a sensor signal from one magnetic sensor.SOLUTION: A sensor device 20 is installed such that a detection axis direction of a magnetic sensor element 22 is displaced from a tangential direction of a circular rotor 30. Thus, wave form of a sensor signal outputted from the magnetic sensor element is distorted along with the rotation of the rotor. A pulse signal generation part 24 generates a pulse signal with reversed level when the sensor signal satisfies either one of on threshold and off threshold. The on threshold and the off threshold are set to have different values. Duty ratios the generated pulse signals therefore differ from each other between a case where the rotor rotates in one direction and a case where the rotor rotates in the other direction opposite the one direction. As such, direction of rotation of the rotor can be determined based on the duty ratio of the pulse signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a rotation direction detection device and a rotation direction detection method. [Background technology]

[0002] Patent Document 1 describes a magnetic encoder having a magnetic sensor and an annular magnetic rotor. A magnetization pattern is formed on the surface of the magnetic rotor, with alternating north and south poles. The magnetization pattern defines divided regions by dividing the entire circumference of the magnetic rotor at equal angles. Within each divided region, the ratio of the widths of the north and south poles is constant, while the ratio of the widths of the north and south poles varies among the divided regions. In this way, a certain duty ratio corresponding to the ratio of the widths of the north and south poles is measured, and then, when a different duty ratio is measured or when it is determined that the same duty ratio continues, the absolute angle of the magnetic rotor can be determined. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-64897 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, for a motor that rotates in both forward and reverse directions, such as a motor that opens and closes a vehicle window, it may be necessary to detect the direction of rotation of the motor to confirm whether the motor is rotating correctly in the desired direction.

[0005] Generally, to detect the rotation direction of a motor, for example, a magnetic rotor is attached to the rotating shaft of the motor, and two magnetic sensors are arranged to output sensor signals with a predetermined phase difference relative to the magnetic rotor. In this case, the rotation direction of the motor can be determined based on the order in which the sensor signals from the two magnetic sensors change.

[0006] Furthermore, as described in the above-mentioned Patent Document 1, by varying the ratio of the widths of the north and south poles in the magnetization pattern of the magnetic rotor for each divided region, the duty ratio corresponding to the ratio of the widths of the north and south poles changes according to the rotation of the magnetic rotor. In this case, it is possible to determine the rotation direction of the magnetic rotor based on the order in which the duty ratio changes.

[0007] However, in the former case, two magnetic sensors are required to detect the rotation direction of the motor, which leads to problems of increased costs and size.In the latter case, although the rotation direction can be detected with one magnetic sensor, the magnetic rotor requires a special magnetization pattern, which makes manufacturing the magnetic rotor more time-consuming and increases manufacturing costs.

[0008] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a rotation direction detection device and a rotation direction detection method that are capable of detecting the rotation direction of a rotating body based on a sensor signal from a single magnetic sensor, without using a rotating body with a special magnetization pattern. [Means for solving the problem]

[0009] In order to achieve the above object, the rotation direction detection device according to the present disclosure includes: a substantially circular rotor (30) magnetized at equal intervals in the rotational direction; a magnetic sensor (22) that outputs a sensor signal corresponding to a change in magnetic flux due to rotation of a rotor; a determination processing unit (10, 24) that determines the rotation direction of the rotating body based on a sensor signal output from the magnetic sensor, The magnetic sensor is installed so that the direction of its detection axis is shifted from the tangential direction of the rotating body. the determination processing unit generates a pulse signal whose level is inverted when the sensor signal satisfies either an ON threshold or an OFF threshold; The on-threshold and off-threshold are set to different values, The determination processing unit is configured to determine the rotation direction of the rotating body based on the duty ratio of the pulse signal.

[0010] A rotation direction detection method according to the present disclosure is executed by at least one processor and determines the rotation direction of a rotor based on a sensor signal output from one magnetic sensor (22) corresponding to a change in magnetic flux due to rotation of a substantially circular rotor (30) magnetized at equal intervals in the rotation direction, the method comprising: The magnetic sensor is installed so that the direction of its detection axis is shifted from the tangential direction of the rotating body. generating a pulse signal whose level is inverted when the sensor signal satisfies either an ON threshold or an OFF threshold; The on-threshold and off-threshold are set to different values, and The rotation direction of the rotating body is determined based on the duty ratio of the pulse signal.

[0011] In the rotation direction detection device and rotation direction detection method disclosed herein, the magnetic sensor is installed so that the direction of its detection axis is shifted from the tangent direction of the rotating body. As a result, the waveform of the sensor signal output from the magnetic sensor is distorted as the rotating body rotates. As a result, the magnitude of change in the sensor signal relative to the amount of rotation of the rotating body, i.e., the rate of change in the sensor signal, on both sides of the maximum (peak) or minimum (trough) of the sensor signal, is not symmetrical around the maximum (peak) or minimum (trough) but is different.

[0012] In the rotation direction detection device and rotation direction detection method disclosed herein, the on threshold and off threshold for generating a pulse signal from a sensor signal are set to different values. Therefore, the point at which the level of the pulse signal inverts is different when the sensor signal changes from a high rate of change to a low rate of change via a maximum or minimum value and when the sensor signal changes from a low rate of change to a high rate of change via a maximum or minimum value. As a result, the duty ratio of the pulse signal generated when the rotating body rotates in one direction differs from that generated when the rotating body rotates in the opposite direction. Therefore, the rotation direction of the rotating body can be determined based on the duty ratio of the generated pulse signal.

[0013] In this way, according to the rotation direction detection device and rotation direction detection method disclosed herein, it is possible to detect the rotation direction of a rotating body based on a sensor signal from a single magnetic sensor, without using a rotating body with a special magnetization pattern.

[0014] The reference numbers in parentheses above merely indicate an example of a correspondence with specific configurations in the embodiments described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0015] Furthermore, the technical features of the present disclosure other than those described above will become apparent from the following description of the embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a configuration diagram showing the configuration of a rotation direction detection device according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing a modified example of a rotating body. [Figure 3] 1 is an explanatory diagram for explaining a characteristic configuration of a rotation direction detection device according to a first embodiment and the effects of the characteristic configuration. FIG. [Figure 4]10A and 10B are diagrams showing the positional relationship between a magnet, which is a rotating body, and a Hall element, which is a magnetic sensor element, and the waveform of the measured sensor signal, in which a sensor signal was actually measured. [Figure 5] FIG. 3 is another explanatory diagram for explaining the characteristic configuration of the rotation direction detector according to the first embodiment and the effects of the characteristic configuration. [Figure 6] 10A and 10B are diagrams illustrating an example of the duty ratio of a pulse signal when a rotating body rotates clockwise and the duty ratio of a pulse signal when a rotating body rotates counterclockwise. [Figure 7] 4 is a flowchart showing a process executed in the rotation direction detection device. [Figure 8] 10 is an explanatory diagram for explaining a characteristic configuration of a rotation direction detecting device according to a second embodiment and the effects of the characteristic configuration. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of a rotation direction detection device and a rotation direction detection method according to the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, in addition to the following, various modifications can be implemented without departing from the spirit of the present disclosure. The embodiments and various modifications can be implemented in appropriate combinations as long as no technical contradiction occurs. In the following description, identical or similar components may be assigned the same reference numerals across multiple drawings, and their description may be omitted. Furthermore, when only a portion of a component is mentioned, the description provided elsewhere may apply to the other components.

[0018] (First embodiment) First, a rotation direction detection device and a rotation direction detection method according to a first embodiment of the present disclosure will be described in detail with reference to the drawings. Fig. 1 is a diagram showing the configuration of a rotation direction detection device 100 according to this embodiment.

[0019] As shown in FIG. 1, the rotation direction detection device 100 includes a microcomputer 10 and a sensor device 20. The microcomputer 10 may be configured as a known computer including at least one processor (CPU), memory (ROM and RAM), and an I / O circuit for exchanging signals with the outside. In the microcomputer 10, the CPU executes various processes according to programs stored in the ROM, for example. As an example, the microcomputer 10 determines the rotation direction of the rotating body 30 based on a pulse signal output from the sensor device 20 corresponding to the rotation of the rotating body 30. In addition to determining the rotation direction of the rotating body 30, the microcomputer 10 can also execute other processes, such as calculating the amount of rotation of the rotating body 30 and controlling a motor (not shown) that rotates the rotating body 30.

[0020] The sensor device 20 includes a magnetic sensor element 22, such as a Hall IC or a magnetic resistance element, installed near the rotating body 30. The sensor device 20 also includes a pulse signal generator 24 that generates a pulse signal based on a sensor signal output from the magnetic sensor element 22 in response to a change in magnetic flux due to the rotation of the rotating body 30. The pulse signal generator 24 may be configured, for example, by a dedicated hardware circuit or a microcomputer with a simple configuration. In this case, the dedicated hardware circuit or the microcomputer with a simple configuration is included in at least one processor of the present disclosure. The sensor device 20 will be described in detail later.

[0021] The rotor 30 is attached to the rotating shaft of a motor (not shown) and rotates together with the motor. The rotor 30 is formed in a substantially circular shape and is magnetized with south and north poles at equal intervals in the rotational direction. "Evenly spaced in the rotational direction" means that the south and north poles that appear alternately as the rotor 30 rotates have equal circumferential lengths.

[0022] FIG. 1 shows an example in which the rotating body 30 is provided with one south pole and one north pole. However, multiple south poles and multiple north poles may be provided. For example, as shown in FIG. 2, two south poles and two north poles may be magnetized alternately at equal intervals in the rotational direction on the rotating body 30. The rotating body 30 may be made of a permanent magnet itself, or may have a permanent magnet embedded in the rotating body 30 or a permanent magnet attached to the outer circumferential surface.

[0023] The motor that rotates the rotor 30 drives a driven object by rotating in a forward direction and a reverse direction. For example, the motor can be a vehicle window. In this case, the motor drives the vehicle window to open and close by rotating in a forward direction and a reverse direction. However, the driven object is not limited to a vehicle window, and may be, for example, an air mix door in an air conditioning system, a door mirror, a wiper, or the like. Furthermore, the driven object may be various devices other than vehicle devices installed in a vehicle.

[0024] The motor that rotates the rotor 30 may be, for example, a brushed DC motor. A brushed DC motor includes a rotor made of a laminated iron core wound with a coil and a stator made of a permanent magnet. When the rotor rotates in a magnetic field, the commutator attached to the rotor also rotates, and the brushes that the commutator comes into contact with change places. Each time the brushes that the commutator comes into contact with change places, the direction of the current flowing through the coils changes, causing the rotor to continue rotating and driving the DC motor. A brushed DC motor can switch its direction of rotation between forward and reverse by switching the direction of the current flowing through the coils via the brushes.

[0025] However, the motor that rotates the rotor 30 is not limited to a brushed DC motor. For example, the motor that rotates the rotor 30 may be a brushless DC motor, an AC motor, or a stepping motor. In short, the motor may be a motor whose rotation direction can be switched between forward and reverse.

[0026] For example, when a DC motor is used to control the opening and closing of a vehicle window, if an object is pinched by the window while the window is closing, a pinch prevention control is generally executed, which rotates the DC motor in the reverse direction. To ensure reliable execution of such pinch prevention control, it is necessary to be able to confirm whether the DC motor is rotating in the desired direction, i.e., to detect the rotation direction of the DC motor. However, detecting the rotation direction of the DC motor requires arranging two magnetic sensors to output sensor signals with a predetermined phase difference or using a rotating body with a special magnetization pattern, which results in increased costs and an increase in size.

[0027] Therefore, the rotation direction detection device 100 according to this embodiment is designed to detect the rotation direction of the rotor 30 without using a rotor with a special magnetization pattern, and based on a sensor signal from one magnetic sensor element 22. The characteristic configuration of the rotation direction detection device 100 according to this embodiment and the effects of this characteristic configuration will be described in detail below.

[0028] First, in the rotation direction detection device 100 according to this embodiment, the sensor device 20 is disposed at position B shown in FIG. 3(a). Position A shown in FIG. 3(a) illustrates an example in which the sensor device 20 is disposed so that the detection direction (also referred to as the detection axis) of the magnetic sensor element 22 and the tangential direction of the rotor 30, which is substantially circular, are the same. On the other hand, position B shown in FIG. 3(a) illustrates an example in which the sensor device 20 is disposed so that the detection direction of the magnetic sensor element 22 and the tangential direction of the rotor 30 are different. In other words, at position B, the detection direction of the magnetic sensor element 22 and the tangential direction of the rotor 30 are misaligned.

[0029] As shown in FIG. 3( a), when the sensor device 20 is disposed at position A, when the boundary between the north and south poles of the rotating body 30 reaches a position facing the sensor device 20, the direction of the magnetic flux from the north pole to the south pole coincides with the detection direction of the magnetic sensor element 22 of the sensor device 20. At this time, the value of the sensor signal output by the magnetic sensor element 22 of the sensor device 20 reaches a maximum value (peak). Then, when the rotating body 30 rotates and the boundary on the opposite side between the north and south poles of the rotating body 30 reaches a position facing the sensor device 20, the direction of the magnetic flux from the north pole to the south pole coincides with the detection direction of the magnetic sensor element 22 of the sensor device 20. At this time, the value of the sensor signal output by the magnetic sensor element 22 of the sensor device 20 reaches a minimum value (trough). In this way, the direction of the magnetic flux acting on the magnetic sensor element 22 changes between a first direction that coincides with the detection direction of the magnetic sensor element 22 and a second direction that is opposite to the detection direction (first direction) as the rotating body 30 rotates. The direction of the magnetic flux acting on the magnetic sensor element 22 changes between a first direction and a second direction in accordance with the rotation of the rotating body 30. The sensor signal output from the magnetic sensor element 22 decreases as the angle difference between the direction of the magnetic flux acting on the magnetic sensor element 22 and the first direction increases.

[0030] FIG. 3(b) shows an example of a sensor signal output by the magnetic sensor element 22 of the sensor device 20 placed at position A. Because the detection direction of the magnetic sensor element 22 coincides with the tangent direction of the rotating body 30, the direction of the magnetic flux before the sensor signal reaches its maximum value (peak) and the direction of the magnetic flux after it reaches its maximum value (peak) change at approximately the same rate relative to the amount of rotation of the rotating body 30. As a result, the manner in which the sensor signal increases before it reaches its maximum value (peak) and the manner in which the sensor signal decreases after it reaches its maximum value (peak) are also approximately the same. In other words, the change in the sensor signal is symmetrical around the maximum value (peak). The same is true for the minimum value (valley).

[0031] 3(c) shows an example of a sensor signal output by the magnetic sensor element 22 of the sensor device 20 placed at position B. Because the detection direction of the magnetic sensor element 22 differs from the tangential direction of the rotating body 30, the waveform of the sensor signal output from the magnetic sensor as the rotating body rotates is distorted from the sensor waveform shown in FIG. 3(b). As a result, the magnitude of change in the sensor signal relative to the amount of rotation of the rotating body 30, i.e., the rate of change in the sensor signal, on both sides of the maximum value (peak) and minimum value (trough) of the sensor signal, is not symmetrical about the maximum value (peak) and minimum value (trough) but is different.

[0032] The inventors of the present application actually positioned a sensor device 20 using a magnet (18 mm in diameter) as the rotating body 30 and a Hall element as the magnetic sensor element 22 in the positional relationship shown in FIG. 4(a), and measured the sensor signal output from the magnetic sensor element 22. As shown in FIG. 4(a), the sensor device 20 has a detection direction parallel to the Z axis. The sensor device 20 is spaced 2.71 mm from the X axis. Therefore, the detection direction of the magnetic sensor element 22 is different from the tangential direction of the rotating body 30. The distance from the Z axis of the sensor device 20 is 12.55 mm.

[0033] FIG. 4(b) shows the sensor signal output by the magnetic sensor element 22 of FIG. 4(a). As can be seen from FIG. 4(b), the rate of increase (slope) of the sensor signal as the electrical angle increases until it reaches a maximum value (peak) near electrical angle 310 degrees or 670 degrees is relatively gentle. In contrast, the rate of decrease (slope) of the sensor signal as it moves away from each maximum value (peak) as the electrical angle increases is relatively steep. The same can be said for the rate of decrease (slope) of the sensor signal as it moves toward a minimum value (trough) and the rate of increase (slope) of the sensor signal as it moves away from the minimum value (trough) as the electrical angle increases.

[0034] In the rotation direction detection device 100 according to this embodiment, the pulse signal generating unit 24 is configured to generate a pulse signal whose level is inverted when the sensor signal output from the magnetic sensor element 22 exceeds the ON threshold and falls below the OFF threshold, as shown in FIG. 5. In this manner, in this embodiment, when the sensor signal output from the magnetic sensor element 22 exceeds the ON threshold and falls below the OFF threshold, it is determined that the sensor signal satisfies either the ON threshold or the OFF threshold, and the level of the pulse signal is inverted. As shown in FIG. 5, the ON threshold and the OFF threshold are set to different values. In the example shown in FIG. 5, the ON threshold is set to a value greater than the OFF threshold. The ON threshold may also be set to a value smaller than the OFF threshold.

[0035] For example, when the motor rotates in the forward direction and the rotor 30 rotates clockwise (CW), when the sensor signal exceeds the ON threshold (times T11, T13, T15), the pulse signal generating unit 24 inverts the level of the pulse signal by lowering the level of the pulse signal. On the other hand, when the sensor signal falls below the OFF threshold (times T12, T14, T16), the pulse signal generating unit 24 inverts the level of the pulse signal by raising the level of the pulse signal.

[0036] The pulse signal generating unit 24 generates a pulse signal when the motor rotates in the reverse direction and the rotor 30 rotates counterclockwise (CCW) in the same way as when the rotor 30 rotates clockwise. That is, when the sensor signal exceeds the ON threshold (times t11, t13, t15), the pulse signal generating unit 24 inverts the level of the pulse signal by lowering the level of the pulse signal. On the other hand, when the sensor signal falls below the OFF threshold (times t12, t14, t16), the pulse signal generating unit 24 inverts the level of the pulse signal by raising the level of the pulse signal.

[0037] As described above, the waveform of the sensor signal output by the magnetic sensor element 22 is distorted, and the rate of change of the sensor signal on both sides of its maximum value (peak) is different from symmetrical about the maximum value (peak). Furthermore, the on-threshold and off-threshold for generating a pulse signal from the sensor signal are set to different values. Therefore, the point at which the level of the pulse signal is inverted differs between the case where the rotating body 30 rotates clockwise and the sensor signal changes from the side with a small rate of change to the side with a large rate of change via the maximum value and the case where the rotating body 30 rotates counterclockwise and the sensor signal changes from the side with a large rate of change to the side with a small rate of change via the maximum value.

[0038] For this reason, as shown in FIG. 5 , the falling and rising times (T11, T12, T13, T14, T15, T16) of the pulse signal when the rotor 30 is rotating clockwise differ from the falling and rising times (t11, t12, t13, t14, t15, t16) of the pulse signal when the rotor 30 is rotating counterclockwise. As a result, the duty ratio of the pulse signal generated when the rotor 30 is rotating clockwise differs from that generated when the rotor 30 is rotating counterclockwise. Note that the duty ratio of the pulse signal when the rotor 30 is rotating clockwise and the duty ratio of the pulse signal when the rotor 30 is rotating counterclockwise do not substantially change depending on the rotation speed of the rotor 30.

[0039] For example, as shown in Fig. 6(a), when the rotor 30 rotates clockwise, the pulse signal generating unit 24 generates a pulse signal with a rising period ratio of 70%. In contrast, as shown in Fig. 6(b), when the rotor 30 rotates counterclockwise, the pulse signal generating unit 24 generates a pulse signal with a rising period ratio of 60%. In this way, the duty ratio of the pulse signal generated when the rotor 30 rotates clockwise differs from that when the rotor 30 rotates counterclockwise, so the microcomputer 10 can detect the rotation direction of the rotor 30 based on the duty ratio of the generated pulse signal.

[0040] Next, the processing executed in the rotation direction detection device 100 to detect the rotation direction of the rotating body 30 will be described with reference to the flowchart of Fig. 7. The flowchart of Fig. 7 includes processing executed in the pulse signal generation unit 24 and processing executed in the microcomputer 10. Execution of the processing shown in the flowchart of Fig. 7 in the rotation direction detection device 100 corresponds to execution of the rotation detection method according to this embodiment. Furthermore, the microcomputer 10 and the pulse signal generation unit 24 correspond to a determination processing unit of the present disclosure.

[0041] In step S100, the pulse signal generating unit 24 receives the pulse signal output from the magnetic sensor element 22. In step S110, the pulse signal generating unit 24 compares the magnitude of the received sensor signal with an ON threshold and an OFF threshold.

[0042] In step S120, the pulse signal generating unit 24 determines whether the sensor signal exceeds the ON threshold based on the comparison result in step S110. If it is determined that the sensor signal exceeds the ON threshold, the pulse signal generating unit 24 proceeds to processing in step S130, where it inverts the level of the pulse signal by lowering the level of the pulse signal. If it is not determined that the sensor signal exceeds the ON threshold, the pulse signal generating unit 24 proceeds to processing in step S140.

[0043] In step S140, the pulse signal generating unit 24 determines whether the sensor signal has fallen below the OFF threshold based on the comparison result in step S110. If it is determined that the sensor signal has fallen below the OFF threshold, the pulse signal generating unit 24 proceeds to processing in step S150, where it inverts the level of the HAL signal by raising the level of the pulse signal. If it is not determined that the sensor signal has fallen below the OFF threshold, the processing in step S140 is executed.

[0044] In step S160, the microcomputer 10 determines whether the level of the pulse signal output from the pulse signal generating unit 24 has inverted. If it is determined that the level of the pulse signal has inverted, the microcomputer 10 proceeds to processing in step S170. If it is determined that the level of the pulse signal has inverted, the microcomputer 10 ends the processing shown in the flowchart of FIG.

[0045] In step S170, the microcomputer 10 calculates the duty ratio of the pulse signal based on the pulse signal whose level has been inverted. Therefore, the microcomputer 10 can calculate the latest duty ratio of the pulse signal every time the level of the pulse signal is inverted. In step S180, the microcomputer 10 detects the rotation direction of the rotating body 30 based on the calculated duty ratio.

[0046] In the first embodiment described above, the pulse signal generating unit 24 generates a pulse signal by inverting the level of the pulse signal so that the pulse signal falls when the sensor signal exceeds the on threshold and rises when the sensor signal falls below the off threshold. However, the pulse signal generating unit 24 may generate a pulse signal by inverting the level of the pulse signal so that the pulse signal rises when the sensor signal exceeds the on threshold and falls below the off threshold.

[0047] In the first embodiment, the pulse signal generating unit 24 sets the ON and OFF thresholds with different magnitudes near the maximum value (peak) of the sensor signal. However, the pulse signal generating unit 24 may set the ON and OFF thresholds with different magnitudes near the minimum value (trough) of the sensor signal. In this case, when the sensor signal output from the magnetic sensor element 22 falls below the ON threshold or exceeds the OFF threshold, the sensor signal is determined to satisfy either the ON or OFF threshold, and the level of the pulse signal is inverted. In this case, as in the case where the ON and OFF thresholds are set near the maximum value (peak), the duty ratio of the pulse signal when the rotor 30 rotates clockwise can be made different from the duty ratio of the pulse signal when the rotor 30 rotates counterclockwise. Therefore, the microcomputer 10 can detect the rotation direction of the rotor 30 based on the duty ratio of the pulse signal.

[0048] (Second embodiment) Next, a rotation direction detector 100 according to a second embodiment of the present disclosure will be described with reference to the drawings. The rotation direction detector 100 according to this embodiment is configured similarly to the rotation direction detector 100 according to the first embodiment. Therefore, a description of the configuration of the rotation direction detector 100 according to this embodiment will be omitted.

[0049] In the rotation direction detection device 100 according to the first embodiment, the pulse signal generation unit 24 inverts the level of the pulse signal when the sensor signal satisfies the on threshold or the off threshold in either a vicinity of where the direction of the magnetic flux acting on the magnetic sensor element 22 is a first direction that coincides with the detection direction of the magnetic sensor element 22 (i.e., near the maximum value of the sensor signal) or a vicinity of where the direction of the magnetic flux acting on the magnetic sensor element 22 is a second direction that is opposite to the detection direction of the magnetic sensor element 22 (i.e., near the minimum value of the sensor signal). Since the rotation direction of the rotating body 30 is detected based on the duty ratio of the pulse signal, the rotation direction detection device 100 according to the first embodiment can be said to determine the rotation direction of the rotating body 30 either in a vicinity of where the direction of the magnetic flux acting on the magnetic sensor element 22 is the first direction or in a vicinity of where the direction of the magnetic flux acting on the magnetic sensor element 22 is the second direction. In this specification, determining the rotation direction of the rotating body 30 either in a vicinity of where the direction of the magnetic flux acting on the magnetic sensor element 22 is the first direction or in a vicinity of where the direction of the magnetic flux acting on the magnetic sensor element 22 is the second direction is referred to as one-sided determination.

[0050] In contrast, in the rotation direction detection device 100 according to the second embodiment, the pulse signal generation unit 24 is configured to determine the rotation direction of the rotating body 30 both in the vicinity where the direction of the magnetic flux acting on the magnetic sensor element 22 is the first direction and in the vicinity where the direction of the magnetic flux acting on the magnetic sensor element 22 is the second direction. In this specification, determining the rotation direction of the rotating body 30 both in the vicinity where the direction of the magnetic flux acting on the magnetic sensor element 22 is the first direction and in the vicinity where the direction of the magnetic flux acting on the magnetic sensor element 22 is the second direction is referred to as two-sided determination.

[0051] To perform bilateral determination, the pulse signal generating unit 24 in this embodiment sets an ON threshold and an OFF threshold with different magnitudes near the maximum value (peak) of the sensor signal, and also sets an ON threshold and an OFF threshold with different magnitudes near the minimum value (trough) of the sensor signal. Fig. 8 shows an example in which an ON threshold and an OFF threshold with different magnitudes are set near the maximum value (peak) and near the minimum value (trough) of the sensor signal.

[0052] 8, when the motor rotates in the forward direction and the rotor 30 rotates clockwise (CW), when the sensor signal exceeds the ON threshold near the maximum value (times T21, T25, T29) and when the sensor signal falls below the ON threshold near the minimum value (times T23, T27), the sensor signal satisfies the ON threshold, and the pulse signal generating unit 24 inverts the level of the pulse signal by lowering the level of the pulse signal. On the other hand, when the sensor signal falls below the OFF threshold near the maximum value (times T22, T26, T30) and when the sensor signal exceeds the OFF threshold near the minimum value (times T24, T28), the sensor signal satisfies the OFF threshold, and the pulse signal generating unit 24 inverts the level of the pulse signal by raising the level of the pulse signal.

[0053] The pulse signal generating unit 24 generates a pulse signal when the motor rotates in the reverse direction and the rotor 30 rotates counterclockwise (CCW) in the same way as when the motor rotates clockwise. That is, when the sensor signal exceeds the ON threshold near the maximum value (times t21, t25, t29) and when the sensor signal falls below the ON threshold near the minimum value (times t23, t27), the pulse signal generating unit 24 determines that the sensor signal satisfies the ON threshold and inverts the level of the pulse signal by lowering the level of the pulse signal. On the other hand, when the sensor signal falls below the OFF threshold near the maximum value (times t22, t26, t30) and when the sensor signal exceeds the OFF threshold near the minimum value (times t24, t28), the pulse signal generating unit 24 determines that the sensor signal satisfies the OFF threshold and inverts the level of the pulse signal by raising the level of the pulse signal.

[0054] As described above, the rotation direction detection device 100 according to this embodiment can determine the rotation direction of the rotating body 30 by a two-sided determination. Therefore, it is possible to determine the rotation direction of the rotating body 30 earlier than with a one-sided determination.

[0055] The above describes preferred embodiments of the present disclosure, but the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications within the scope of the gist of the present disclosure.

[0056] For example, in the above-described first and second embodiments, an example has been described in which the pulse signal generating unit 24 is provided in the sensor device 20. However, the function of the pulse signal generating unit 24 may be configured to be possessed by the microcomputer 10. In this case, the sensor device 20 inputs a sensor signal detected by the magnetic sensor element 22 to the microcomputer 10.

[0057] When the microcomputer 10 is configured to have the function of the pulse signal generating unit 24, the microcomputer 10 may be configured to be able to switch between one-sided and two-sided determination in response to, for example, an external instruction signal. In the case of one-sided determination, as described above, the timing of the rise and fall of the pulse signal is determined either near the maximum value of the sensor signal or near the minimum value of the sensor signal, and a pulse signal is generated. On the other hand, in the case of two-sided determination, the timing of the rise and fall of the pulse signal is determined both near the maximum value of the sensor signal and near the minimum value of the sensor signal, and a pulse signal is generated. Therefore, compared to two-sided determination, one-sided determination has the advantage of requiring less computational processing load on the microcomputer 10 and the like. On the other hand, two-sided determination has the advantage of being able to detect the rotation direction of the rotating body 30 more quickly than one-sided determination. Therefore, when the microcomputer 10 is configured to be able to switch between one-sided determination and two-sided determination, it is possible to select a more preferable determination method depending on the application and needs.

[0058] In addition, even when the pulse signal generating unit 24 is provided in the sensor device 20, the sensor device 20 may be configured to be able to switch between one-sided judgment and two-sided judgment by instructing the sensor device 20 which judgment method to adopt.

[0059] Alternatively, the microcomputer 10 may be configured to determine which determination method to use, rather than relying on an external instruction signal. For example, the microcomputer 10 may be configured to determine to perform one-side determination when the motor rotates in the forward direction to open the window, and to perform two-side determination when the motor rotates in the reverse direction to close the window. When the window is being closed, if pinching is detected, it is necessary to immediately perform pinch prevention control and reverse the opening and closing direction of the window. Therefore, it is preferable to perform two-side determination to detect the rotation direction of the motor (rotating body 30) as early as possible. On the other hand, when the window is being opened, there is little need to detect the rotation direction as early as possible. Therefore, it is preferable to perform one-side determination to reduce the processing load on the microcomputer 10.

[0060] Furthermore, the microcomputer 10 may be configured to perform a two-sided determination when the window is closed, from when the window approaches a predetermined distance to the closed position where the window is completely closed until the window reaches the closed position. In other words, when the window is closed, a one-sided determination may be performed until the window reaches the predetermined distance to the closed position, and a two-sided determination may be performed from when the window reaches the predetermined distance to the closed position. This is because the importance of entrapment prevention control increases particularly from when the window approaches a predetermined distance to the closed position until it reaches the closed position. [Explanation of symbols]

[0061] 10: Microcomputer 20: Sensor device 22: Magnetic sensor element 24: Pulse signal generator 30: Rotating body 100: Rotation direction detection device

Claims

1. a substantially circular rotor (30) magnetized at equal intervals in the rotational direction; a magnetic sensor (22) that outputs a sensor signal corresponding to a change in magnetic flux due to rotation of the rotor; a determination processing unit (10, 24) that determines the rotation direction of the rotating body based on the sensor signal output from the magnetic sensor, the magnetic sensor is installed such that the direction of the detection axis is shifted from the tangential direction of the rotating body, the determination processing unit generates a pulse signal whose level is inverted when the sensor signal satisfies either an ON threshold or an OFF threshold; The on-threshold value and the off-threshold value are set to different values, The determination processing unit determines the rotation direction of the rotating body based on the duty ratio of the pulse signal.

2. a direction of magnetic flux acting on the magnetic sensor changes between a first direction and a second direction opposite to the first direction in response to rotation of the rotating body; 2. The rotation direction detection device according to claim 1, wherein the determination processing unit determines the rotation direction of the rotating body in at least one of a vicinity where a direction of magnetic flux acting on the magnetic sensor is in the first direction and a vicinity where a direction of magnetic flux acting on the magnetic sensor is in the second direction.

3. a direction of magnetic flux acting on the magnetic sensor changes between a first direction and a second direction opposite to the first direction in response to rotation of the rotating body; 2. The rotation direction detection device according to claim 1, wherein the determination processing unit is configured to be able to switch between one-sided determination in which the rotation direction of the rotating body is determined either near the vicinity where a direction of magnetic flux acting on the magnetic sensor is the first direction or near the vicinity where the direction of magnetic flux acting on the magnetic sensor is the second direction, and two-sided determination in which the rotation direction of the rotating body is determined both near the vicinity where a direction of magnetic flux acting on the magnetic sensor is the first direction and near the vicinity where the direction of magnetic flux acting on the magnetic sensor is the second direction.

4. 4. The rotation direction detector according to claim 1, wherein the rotation direction detector is used to detect the rotation direction of a motor that opens or closes a window by rotating in a forward or reverse direction.

5. a direction of magnetic flux acting on the magnetic sensor changes between a first direction and a second direction opposite to the first direction in response to rotation of the rotating body; the determination processing unit is configured to be able to switch between one-sided determination in which the rotation direction of the rotating body is determined by one of a vicinity where a direction of magnetic flux acting on the magnetic sensor is the first direction and a vicinity where the direction of magnetic flux acting on the magnetic sensor is the second direction, and a two-sided determination in which the rotation direction of the rotating body is determined by both a vicinity where a direction of magnetic flux acting on the magnetic sensor is the first direction and a vicinity where the direction of magnetic flux acting on the magnetic sensor is the second direction, 5. The rotation direction detection device according to claim 4, wherein the determination processing unit performs the one-side determination when the motor rotates in a forward direction to open the window, and performs the both-side determination when the motor rotates in a reverse direction to close the window.

6. 6. The rotation direction detection device according to claim 5, wherein the determination processing unit performs the both-side determination when the window is closed from when the window approaches a closed position where the window is completely closed within a predetermined distance until the window reaches the closed position.

7. A rotation direction detection method executed by at least one processor, for determining the rotation direction of a substantially circular rotating body (30) magnetized at equal intervals in the rotation direction based on a sensor signal output from one magnetic sensor (22) corresponding to a change in magnetic flux due to rotation of the rotating body, the method comprising: the magnetic sensor is installed such that the direction of the detection axis is shifted from the tangential direction of the rotating body, generating a pulse signal whose level is inverted when the sensor signal satisfies either an ON threshold or an OFF threshold; The on-threshold and the off-threshold are set to different values; and determining a rotation direction of the rotating body based on a duty ratio of the pulse signal.

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