Motion detection unit

Abstract

Motion detection unit, comprising: a movable body (1) that performs a movement in a first direction (1R); a first sensor (3A, 3B) that detects a change in a first magnetic field caused by the movement of the movable body (1) and outputs a first signal (A); a second sensor (3C, 3D) provided in the first direction (1R) at a location different from the location of the first sensor (3A, 3B), wherein the second sensor (3C, 3D) detects a change in a second magnetic field caused by the motion of the movable body (1) and outputs a second signal (B, B0); and a signal processor (4) comprising a signal generation circuit (40, 40A, 40B, 40C) which generates a third signal (A1, A3, A5) and a fourth signal (A2, A4, A6) based on the first signal (A), wherein the third signal (A1, A3, A5) and the fourth signal (A2, A4, A6) have waveforms that are different from each other, where The signal generation circuit (40, 40A, 40B, 40C) further includes: a first comparator (42A) which outputs a fifth signal (C1, C3, C5) based on a comparison between the third signal (A1, A3, A5) and the second signal (B, B0); a second comparator (42B) that outputs a sixth signal (C2, C4, C6) based on a comparison between the fourth signal (A2, A4, A6) and the second signal (B, B0); and a pulse generator (43) which combines the fifth signal (C1, C3, C5) and the sixth signal (C2, C4, C6) and thereby generates a seventh signal (D, D1, D2, D3) which contains a plurality of pulses (PL1, PL2, PL3).

Description

BACKGROUND

[0001] The technology involves a motion detection unit with a magnetic detection device that detects a change in a magnetic field.

[0002] Rotation detection units are generally used to detect rotational movements of axles or other rotating bodies. An exemplary rotation detection unit includes a gear with a magnetic body and a magnetic detection device that is provided and does not touch the gear (see, for example, unexamined Japanese patent applications with publication numbers JP H6-34645A and JP 2015-111062A).

[0003] US 2001 / 0 002 791 A1 discloses a rotary magnet in which rotation is detected by magnetic sensors and in which the rotational speed is determined from the pulse signals detected by the magnetic sensors and the direction of rotation is determined from the difference by a phase shift. US 2004 / 0 100 251 A1 further discloses an active magnetic field sensor, in particular a wheel bearing sensor unit, with at least one magnetic sensor element for converting a time-periodic magnetic field into a time-periodic electrical sensor signal at signal outputs and an electronic signal evaluation circuit. KR 10 0 897 476 B1 discloses an output signal compensation method and a compensation device, wherein a device comprises a magnetic encoder, an analog circuit unit, and an output signal calculation unit, and wherein an output signal of the magnetic encoder is composed of a sine wave and a cosine wave.EP 0 420 287 B1 shows a pulse counter circuit and a displacement measuring device that uses this pulse counter circuit. PRESENTATION OF THE INVENTION

[0004] Motion detection units according to the independent claims are specified. Preferred embodiments are specified in the dependent claims. In recent years, there has been a need for rotation detection devices to detect the rate of rotation of a gear with high precision, even at low speeds. When a gear rotates at low speed, its angle of rotation per unit of time becomes small. Therefore, a larger number of teeth on a gear may be preferred to detect even small amounts of rotation.

[0005] The maximum number of teeth a gear can have can be limited by various factors, including the dimensions of the gear itself and the machining accuracy of the teeth. Furthermore, even when many small gear teeth are precisely machined, there are cases where changes in the magnetic field around the teeth are reduced due to a decrease in tooth size, and the magnetic fields generated by adjacent teeth interfere with each other. In this case, the detection sensitivity of the magnetic detection device may be reduced.

[0006] The object of the invention is to provide a motion detection unit that detects movement at low speed with high accuracy.

[0007] A motion detection unit according to one embodiment of the technology comprises a movable body, a first sensor, a second sensor, and a signal processor. The movable body performs a movement in a first direction. The first sensor detects a change in the first magnetic field caused by the movement of the movable body and outputs a first signal. The second sensor is positioned in the first direction at a location different from that of the first sensor. The second sensor detects a change in a second magnetic field caused by the movement of the movable body and outputs a second signal. The signal processor includes a signal generation circuit that generates a third and a fourth signal based on the first signal. The third and fourth signals have waveforms that differ from each other.

[0008] In the motion detection unit according to the embodiment of the technology, the signal generation circuit generates the third and fourth signals based on the first signal, which have different waveforms. Therefore, based on the comparison between the second and third signals, as well as between the second and fourth signals, pulses are obtained at different times. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic view of an overall configuration of a rotation detection unit according to a first embodiment of the disclosure. Fig. Figure 2 is a circuit diagram of a crucial part of the Fig. 1 illustrated rotation detection unit. Fig. 3 is an exploded view of a configuration of a stack of each in Fig. 2 illustrated MR devices. Fig. 4 is a waveform diagram illustrating waveforms of signals that are in the Fig. 1 illustrated signal processor can be generated. Fig. 5A is a first enlarged view of a crucial part of the in Fig. Figure 1 illustrates a rotation detection unit and illustrates one of its operations. Fig. 5B is a second enlarged view of the crucial part of the in Fig. Figure 1 illustrates a rotation detection unit and illustrates one of its operations. Fig. 5C is a third enlarged view of the crucial part of the in Fig. Figure 1 illustrates a rotation detection unit and illustrates one of its operations. Fig. 6 is a waveform diagram according to a modification of the one in Fig. 1 illustrated rotation detection unit. Fig. Figure 7 is a circuit diagram illustrating an embodiment of a crucial part of a rotation detection unit according to a second embodiment of the technology. Fig. Figure 8 is a waveform diagram illustrating waveforms of signals that are in the Fig. The signal processor shown in the 7 illustrations can be generated. Fig. Figure 9 is a circuit diagram of a signal processor according to another modification of the first and second embodiments of the technology. Fig. 10 is a waveform diagram illustrating waveforms of signals that are in the Fig. The signal processor shown in the illustrations can be generated. Fig. Figure 11 is a circuit diagram of a signal processor in yet another modification of the first and second embodiments. DETAILED DESCRIPTION

[0009] Some embodiments of the disclosure are explained in more detail below with reference to the accompanying drawings. The description follows the order below. 1. First embodiment

[0010] A rotation detection unit with a signal generation circuit including an adder 2. Modification of the first embodiment

[0011] A rotation detection unit with an output signal with a load ratio of 0.5 3. Second embodiment

[0012] A rotation detection unit with a signal generation circuit including an amplifier 4. Other modifications [1. Embodiment] [Design of a rotation detection unit]

[0013] The following is a description of a design of a rotation detection unit according to a first embodiment of the technology, based on: Fig. 1, Fig. 2, and some other drawings. Fig. Figure 1 is a schematic view of an exemplary overall design of a rotation detection unit. The rotation detection unit can be a so-called gear tooth sensor or a so-called gear sensor. The rotation detection unit can, for example, include a gear 1 and a main body 2. It should be noted that the rotation detection unit can correspond to a "motion detection unit" in a specific, but not limiting, embodiment of the technology. (Gear 1)

[0014] The gear 1 can be a rotating body that rotates in a direction indicated by an arrow 1R. The gear can have a disk-shaped link provided with a toothed portion on its circumference. This toothed portion can include a plurality of projections 1T and a plurality of depressions 1U. These projections 1T and depressions 1U can each be made of a magnetic material and arranged alternately at predetermined intervals (e.g., approximately 2 mm to 7 mm). The rotational movement of the gear 1 can cause the projections 1T and depressions 1U to be alternately positioned at one of the positions closest to the sensor unit 3 in the main body 2. Details of the sensor unit 3 are described later. Due to the rotational movement of the gear 1, a back-bias magnetic field Hbb, which serves as an external magnetic field applied to the main body 2, can change periodically.Details of the back-bias magnetic field Hbb will be explained later using the . Fig. Described in sections 5A to 5C. It should be noted that the total number of projections 1T or the total number of depressions 1U in the gear 1 is referred to as the number of teeth in the gear 1. In a specific, but not limiting, embodiment of the technology, the gear 1 may correspond to a "movable body". (Main body 2)

[0015] The main body 2 can, for example, include the sensor unit 3, a signal processor 4, and a magnet 5. The sensor 3 can include a sensor circuit 30, and the signal processor 4 can include a signal generation circuit 40. Fig. Figure 2 is a circuit diagram illustrating exemplary configurations of the sensor circuit 30 and the signal generation circuit 40. As in Fig. As illustrated in Figure 1, the main body 2 can also have a voltage terminal Vcc, a ground terminal GND, and an output terminal Vout. A voltage can be supplied to the sensor circuit 30 via the voltage terminal Vcc. An output from the signal generation circuit 40 can be obtained via the output terminal Vout. Fig. 1. The distance AG between the sensor unit 3 and the tip of the adjacent projection 1T can be, for example, in the range of approximately 0.5 mm to approximately 3 mm. (Sensor unit 3)

[0016] The sensor circuit 30 can, for example, be a Wheatstone bridge comprising four magnetoresistive (MR) devices, i.e., MR devices 3A to 3D. A first end of MR device 3A can be coupled to a first end of MR device 3B at a node P1; a first end of MR device 3C can be coupled to a first end of MR device 3D at a node P2; a second end of MR device 3A can be coupled to a second end of MR device 3D at a node P3; and a second end of MR device 3B can be coupled to a second end of MR device 3C at a node P4. Node P3 can be coupled to the voltage terminal Vcc; node P4 can be connected to ground; node P1 can be coupled to the signal processor 4 via a wire L1. and node P2 can be coupled to signal processor 4 via a wire L2.Both MR devices 3A and 3B can correspond to a "first sensor" in a specific, but not limiting, embodiment of the technology, and both MR devices 3C and 3D can correspond to a "second sensor" in a specific, but not limiting, embodiment of the technology. The MR devices 3A and 3B that can serve as the first sensor can be arranged in the direction of rotation of gear 1, indicated by arrow 1R, at locations that differ from those of the MR devices 3C and 3D that can serve as the second sensor.

[0017] In Fig. Figure 2, marked by the reference symbol “J31”, schematically indicates the magnetization directions of the magnetically fixed layers 31 in the respective MR devices 3A to 3D. Details of the magnetically fixed layer 31 are described later. In particular, a change in the external magnetic field can cause the resistances of both MR devices 3A and 3C to change in a first direction, and the resistances of both MR devices 3B and 3D can change in a second direction. Furthermore, the first direction is opposite to the second direction. For example, the resistances of MR devices 3B and 3D can decrease if the resistances of MR devices 3A and 3C increase in response to the rotation of gear 1.

[0018] Fig. Figure 3 illustrates an example sensor stack 3S, which is a crucial component of each of the MR devices 3A to 3D. The sensor stacks 3S in the MR devices 3A to 3D can have essentially the same structure. As shown in Fig. As illustrated in Figure 3, the sensor stack 3S can have a spin-valve structure in which a plurality of functional films, including a magnetic layer, are stacked. Specifically, the sensor stack 3S can include the magnetically fixed layer 31, an intermediate layer 32, and a freely magnetizable layer 33 in that order. The magnetically fixed layer 31 can have a magnetization J31 that is fixed in a constant direction. The intermediate layer 32 can have no magnetization in a specific direction. The freely magnetizable layer 33 can have a magnetization J33 that changes with a change in a signal magnetic field. Fig. Figure 3 illustrates a state without an external magnetic field, or back-bias magnetic field Hbb. In other words, it illustrates Fig. 3 an uncharged state. The direction of the magnetization J33 of the freely magnetizable layer 33 can be substantially parallel to its slight magnetization axis AE33 and substantially orthogonal to the magnetization J31 of the magnetically fixed layer 31. For example, the magnetization J31 of the magnetically fixed layer 31 can be fixed in the positive Y direction in each of the MR devices 3A to 3C, whereas the magnetization J31 of the magnetically fixed layer 31 can be fixed in the negative Y direction in each of the MR devices 3B and 3D. Each of the magnetically fixed layer 31, the intermediate layer 32, and the freely magnetizable layer 33 can have either a single-layer structure or a multi-layer structure comprising a plurality of layers.

[0019] The magnetically fixed layer 31 can be made of a ferromagnetic material, examples of which, without limitation, include cobalt (Co), a cobalt-iron alloy (CoFe), and a cobalt-iron-boron alloy (CoFeB). An antiferromagnetic layer (not shown) can be provided on one side of the magnetically fixed layer 31 opposite the intermediate layer 32, such that the antiferromagnetic layer is adjacent to the magnetically fixed layer 31. This antiferromagnetic layer can be made of an antiferromagnetic material, examples of which, without limitation, include a platinum-manganese alloy (PtMn) and an iridium-manganese alloy (IrMn).For example, the antiferromagnetic layer in the MR device 3A can be in a state where magnetic spin moments in the positive Y and negative Y directions completely cancel each other out, and can fix the direction of the magnetization J31 of the adjacent magnetically fixed layer 31 in the positive Y direction.

[0020] The intermediate layer 32 can be a non-magnetic tunnel barrier layer, made, for example, of magnesium oxide (MgO), and can be thin enough to allow a tunnel current to flow through it according to the concepts of quantum mechanics. In this case, the sensor stack 3S can thus have, for example, a magnetic tunnel junction (MTJ) structure. The MgO-based tunnel barrier layer can be produced, for example, by a process such as sputtering using an MgO-based target, a process of oxidizing a thin layer of magnesium (Mg), and reactive sputtering, in which magnesium (Mg) is subjected to a sputtering process in an oxygen atmosphere. Instead of MgO, the intermediate layer 32 can, for example, be made of an oxide or nitride of aluminum (Al), tantalum (Ta), or hafnium (Hf). The intermediate layer 32 is not limited to the tunnel barrier layer.Alternatively, the intermediate layer 32 can be a non-magnetic, electrically conductive layer. In this case, the sensor stack 3S can, for example, have a structure with a huge electroresistive effect.

[0021] The freely magnetizable layer 33 can be a soft ferromagnetic layer and have the simple magnetization axis AE33 in the X-axis direction. The freely magnetizable layer 33 can be made, for example, from a cobalt-iron alloy (CoFe), a nickel-iron alloy (NiFe), or a cobalt-iron-boron alloy (CoFeB).

[0022] If, for example, a current I10 is applied to the Wheatstone bridge in sensor unit 3, which is located above the voltage terminal Vcc, the current I10 can flow via node P3 into both MR devices 3A and 3D. The current I10 can flow through the sensor stacks 3S into the respective MR devices 3A and 3D and then reach nodes P1 and P2. From nodes P1 and P2, the current I10 can then flow into the first ends of the respective MR devices 3B and 3C and through both MR devices 3B and 3C. Finally, the current I10 can reach the ground terminal GND via node P4. The output of the bridge circuit in sensor unit 3 from node P1 can be transmitted as signal A to the signal processor 4 via wire L1. Likewise, the output from the bridge circuit in the sensor unit 3 can be transmitted from node P2 via wire L2 as signal B to the signal processor 4. (Signal processor 4)

[0023] The signal generation circuit 40, which is included in the signal processor 4, can correspond to a "signal generation circuit" in a specific, but non-limiting, embodiment of the technology. The signal generation circuit 40 can, for example, include the adders 41A and 41B, the comparators 42A to 42C, and a combination circuit 43. The combination circuit 43 can include an AND gate 43A, an AND gate 43B, and an OR gate 43C. The signal generation circuit 40 can further include a node P5 and a node P6. The wire L1 can be split into three routes at node P5, and the wire L2 can be split into three routes at node P6. The signal generation circuit 40 can further include the wires L3 to L8. The node P5 can be coupled to the comparator 42A via the wire L3, to the comparator 42B via the wire L4, and to the comparator 42C via the wire L5.Node P6 can be connected to comparator 42A via wire L6, to comparator 42B via wire L7, and to comparator 42C via wire L8. Adder 41A can be connected to wire L3 between node P5 and comparator 42A. Adder 41B can be connected to wire L4 between node P5 and comparator 42B.

[0024] Adder 41A can be a logic circuit that adds a predetermined offset voltage to signal A flowing through wire L3, thereby generating signal A1, and transmits signal A1 to comparator 42A. Similarly, adder 41B can be a logic circuit that adds a predetermined offset voltage to signal A flowing through wire L4, thereby generating signal A2, and transmits signal A2 to comparator 42B. In this example, adders 41A and 41B can add different offset voltages to signal A, thus generating signals A1 and A2 with different waveforms. Fig. Figure 4 illustrates waveforms of signals A1, A, and A2 together with a waveform of signal B. Fig. 4 represents the vertical axis, which is associated with the signals A1, A, A2 and B, and represents the magnitude of a voltage V. Fig. Figure 4 also illustrates the locations of the projections 1T and the depressions 1U in the gear 1, a location of the MR devices 3A and 3B, and a location of the MR devices 3C and 3D. The MR devices 3A and 3B can subsequently be referred to collectively as the "first sensor," and the MR devices 3C and 3D can subsequently be referred to collectively as the "second sensor." In this example, the adder 41A can preferentially add the offset voltage to signal A in a region where the waveform of signal A1 intersects the waveform of signal B. Similarly, the adder 41B can preferentially add the offset voltage to signal A in a region where the waveform of signal A2 intersects the waveform of signal B.

[0025] Each of the comparators 42A to 42C can be a logic circuit that compares logical values ​​(in this example, voltages) of two output signals and outputs a new signal based on a numerical relationship between the voltages of the input signals. Specifically, comparator 42A can compare signal B with signal A to which an offset voltage has been added, and output a signal C1 based on the comparison result. Similarly, comparator 42B can compare signal B with signal A2 to which the offset voltage has been added, and output a signal C2 based on the comparison result. Comparator 42C can compare signal B with signal A to which no offset voltage has been added, and output a signal C based on the comparison result. Fig. Figure 4 illustrates the waveforms of the respective signals C1, C, and C2. Fig. 4. The voltage of each of the signals A1, A, and A2 corresponds to a high level (Hi) if higher than the voltage of signal B, and corresponds to a low level (Lo) if lower than the voltage of signal B.

[0026] The signal generation circuit 40 can further include a wire L9, a wire L10, and a wire L11. Wire L9 can extend from comparator 42A to AND gate 43A. Wire L10 can extend from comparator 42B to AND gate 43A. Wire L11 can extend from comparator 42C to AND gate 43A. A node P7 can be arranged on wire L9 and connected to AND gate 43B via wire L12. A node P8 can be arranged on wire L10 and connected to AND gate 43B via wire L13. A node P9 can be arranged on wire L11A and connected to AND gate 43B via wire L14. In the combination circuit 43, after the signals C1, C and C2 have been supplied to both AND gates 43A and 43B, the outputs of the AND gates 43A and 43B can be supplied to the AND gate 43C, thereby outputting a signal D from the output terminal Vout. Fig. Figure 4 illustrates a waveform of signal D. (Magnet 5)

[0027] Magnet 5 can be positioned on the side of sensor unit 3 opposite gear 1. Magnet 5 can control the back-bias magnetic field Hbb (compare Fig. 5A to 5C (described later) apply in the positive Z-direction to both gear 1 and sensor unit 3. Sensor unit 3 can detect a change in the back-bias magnetic field Hbb using MR devices 3A to 3D. In particular, sensor unit 3 can detect a change in an X-component contained within the back-bias magnetic field Hbb. [Operation and Functionality of the Rotation Detection Unit 3]

[0028] The rotation detection unit of the present embodiment is able to detect a rotational speed of the gear 1 using the sensor unit 3, the signal processor 4, and the magnet 5, which are contained in the main body 2.

[0029] If gear 1, which is in the state of Fig. 5A, for example, when rotating in the direction indicated by arrow 1R, the projections 1T and the recesses 1U in the gear 1 alternately face the MR devices 3A to 3D in the sensor unit 3 of the rotation detection device. In this case, when the projection 1T, made of a magnetic body, faces the sensor unit 3 as shown in Fig. As illustrated in Figure 5B, the magnetic flux of the back-bias magnetic field Hbb, generated by magnet 5 located behind sensor unit 3, can concentrate on this protrusion 1T. In this case, the magnetic flux can spread slightly in the X-axis direction, so that the X-component contained in the back-bias magnetic field Hbb becomes comparatively small. However, if protrusion 1T is located away from sensor unit 3 and sink 1U is located near sensor unit 3 as shown in Figure 5B, the magnetic flux can be concentrated on this protrusion 1T. Fig. As illustrated in Figure 5C, a portion of the magnetic flux of the back-bias magnetic field Hbb can be directed towards the projections 1T on both sides of the depression 1U. In this case, the magnetic flux can be distributed extensively in the X-axis direction, so that the X-component contained in the back-bias magnetic field Hbb becomes comparatively large. With this change in the X-component contained in the back-bias magnetic field Hbb, the direction of the magnetization J33 of the freely magnetizable layer 33 in each of the MR devices 3A to 3D can change. This change in the direction of magnetization J33 can cause the resistances of the MR devices 3A to 3D to change. By exploiting these changes in the resistances of the MR devices 3A to 3D, the rotation detection unit can detect the rotational speed of the gear 1.

[0030] The following is a detailed description of a process for detecting the rotation of gear 1 based on... Fig. 4 and other drawings. In Fig. In reference 4, TH denotes a period over which each of the projections 1T moves from the position nearest to the first sensor to the position nearest to the second sensor as the gear 1 rotates. Similarly, TL denotes a period over which each of the depressions 1U moves from the position nearest to the first sensor to the position nearest to the second sensor. Fig. Figure 4 illustrates an exemplary case in which gear 1 rotates in the direction indicated by arrow 1R relative to both the first and second sensors. Fig. In section 4, the horizontal axis represents the passage of time, and the passage of time increases in the clockwise direction of the horizontal axis.

[0031] As described above, when the protrusion 1T approaches sensor unit 3, the magnetic flux of the back-bias magnetic field Hbb of magnet 5 can be more strongly concentrated on protrusion 1T, so that the X-component contained in the back-bias magnetic field Hbb decreases. Conversely, when sink 1U approaches sensor unit 3, part of the magnetic flux of the back-bias magnetic field Hbb on protrusions 1T can be directed on both sides of sink 1U, so that the X-component contained in the back-bias magnetic field Hbb increases. As a result, the signal B at wire L2 can have a curve as shown in Fig. 4 is indicated by the reference symbol B. In particular, within period TH, the voltage of signal B can gradually decrease to the minimum value and then gradually increase from the minimum value. Furthermore, within period TL, the voltage of signal B can gradually increase to the maximum value and then gradually decrease from the maximum value. The signal A on wire L1 can be represented as by the letter A in Fig. Figure 4 shows a curve. In particular, during period Th, the voltage of signal A can gradually increase to its maximum value and then gradually decrease from that maximum value. Furthermore, within period TL, the voltage of signal A can gradually decrease to its minimum value and then gradually increase from that minimum value.

[0032] Signal A and signal B can be fed directly to comparator 42C via wires L5 and L8, respectively. Comparator 42C, as described above, can compare signals A and B and output signal C with a pulse waveform based on the comparison result. Specifically, over period TH, the voltage of signal A can be higher than that of signal B, in which case comparator 42C can output signal C at a high level (Hi). Over period TL, the voltage of signal A can be lower than that of signal B, in which case comparator 42C can output signal C at a low level (Lo). Fig. 4).

[0033] Signal A can be fed to adder 41A via wire L3, which branches off from wire L1 at node P5. Adder 41A can add the offset voltage to signal A, generating the new signal A1. Signal A1 can be fed to comparator 42A. Signal B can be fed to comparator 42A via wire L6, which branches off from wire L2 at node P6. Comparator 42A can compare signals A1 and B and output signal C1 with a pulse waveform based on the comparison result. Because the offset voltage is added to signal A1, the points where the waveforms of signals A1 and B intersect may differ in location from the points where the waveforms of signals A and B intersect. In particular, a period over which the voltage of signal A1 is higher than that of signal B may be longer than period TH.Furthermore, a period over which the voltage of signal A1 is lower than that of signal B can be shorter than period TL. Consequently, a period TH1 over which signal C1 is at a high level (Hi) can be longer than period TH, whereas a period TL1 over which signal C1 is at a low level (Lo) can be shorter than period TL (see ). Fig. 4).

[0034] Signal A can also be fed to adder 41B via wire L4, which branches off from wire L1 at node P5. Adder 41B can add the offset voltage, which differs from that added to signal A by adder 41A, to signal A, thus generating the new signal A2. Signal A2 can be fed to comparator 42B. Alternatively, signal B can also be fed to comparator 42B via wire L7, which branches off from wire L2 at node P6. Comparator 42B can compare signals A2 and B and output signal C2 with a pulse waveform based on the comparison result. Because the specified offset voltage is added to signal A2, the points where the waveforms of signals A2 and B intersect may differ in location from the intersection points of the waveforms of signals A1 and B.In particular, a period over which the voltage of signal A2 is higher than that of signal B can be shorter than period TH. Furthermore, a period over which the voltage of signal A2 is lower than that of signal B can be longer than period TL. Consequently, a period TH2 over which signal C2 is at a high level (Hi) can be shorter than period TH, and a period TL2 over which signal C2 is at a low level (Lo) can be longer than period TL (compare...). Fig. 4).

[0035] In the signal generation circuit 40, after signals C1, C, and C2 have been generated in the manner described above, the combination circuit 43 can generate a signal D, which is to be output via the output terminal Vout. As in Fig. Figure 4 illustrates that the signal D can contain a multitude of pulses (pulses PL1 and PL2) within the period TH. [How the rotation detection unit works]

[0036] The foregoing configuration allows the rotation detection device in the present embodiment to output the signal D, which contains the plurality of pulses, when the single projection 1T passes between the first and second sensors. One reason for this is that the signal processor 4 generates the signals A1 and A2 with different waveforms based on the signal A, and the comparators 42A and 42B generate the signals C1 and C2 with different waveforms, respectively.

[0037] If the signal processor does not generate signals A1 and A2, only signal C, which contains a single pulse, can be obtained when the single protrusion 1T and the single depression 1U occur between the first and second sensors. However, signal D, which contains the three pulses PL1 to PL3, can be obtained when the single protrusion 1T and the single depression 1U occur between the first and second sensors.

[0038] According to the rotation detection unit in the first embodiment above, the signal processor 4 is provided. This allows the number of pulses to be greater than the number of pulses obtainable solely from a relationship between signals A and B. This makes it possible to detect an extremely small rotation of the gear 1 with high accuracy. [2nd modification of the first embodiment]

[0039] In the foregoing first embodiment, the Fig. Figure 4 illustrates signal D with pulses PL1, PL2, and PL3. Furthermore, pulses PL1 and PL2 differ in pulse width from pulse PL3. Additionally, the interval between pulse PL1 and pulse PL2 differs from the interval between pulse PL2 and pulse PL3. This configuration of pulses in signal D can be used in conjunction with a complex numerical process to determine the rotational speed and angle of rotation of gear 1.

[0040] With reference to the foregoing, it may be preferable, for example, to obtain a signal D1 from the combination circuit 43 in the signal generation circuit 40, in which a plurality of pulses of substantially the same width are provided at substantially the same intervals, as for example in Fig. Figure 6 illustrates this. The aforementioned signal D1 can be obtained by adjusting the offset voltages to be added to signal A by adders 41A and 41B. As a specific example, the amplitude of the voltages of signals A and B can be ±1 V. In this case, when generating signal A1, adder 41A can add an offset voltage V1 of approximately ±1.732 V (= -2 x sin240° = -2 x sin300°) to signal A. Similarly, when generating signal A2, adder 41B can add an offset voltage V2 of approximately -1.732 V (= -2 x sin60° = -2 x sin120°) to signal A.By adjusting the offset voltages in this way, if the waveform of signal A intersects the waveform of signal B at points from approximately 0° to 180°, the waveform of signal A1 can intersect the waveform of signal B at points from approximately 240° to 300°, and the waveform of signal A2 can intersect the waveform of signal B at points from approximately 60° to 120°. As a result, when the single protrusion 1T and the single dimple 1U pass between the first and second sensors, the combination circuit 43 can generate the three pulses, each with a width or span of 60°, at intervals of approximately 60°.

[0041] By outputting signal D1 from signal processor 4 with a load ratio of approximately 0.5, where the multitude of pulses with essentially the same width are provided at essentially the same intervals as described above, it is possible to determine the rotational speed and angle of rotation of gear 1 in a simple way. [3. Second embodiment ][Design and operation of the rotation detection unit]

[0042] A second embodiment of the technology, namely a rotation detection unit, will now be described based on: Fig. 7. Fig. Figure 7 is a circuit diagram showing an exemplary embodiment of a signal generation circuit 40A in the rotation detection unit in the second embodiment. In the first embodiment described above, the signal generation circuit 40 includes the adder 41A, which generates the new signal A1, and the adder 41B, which generates the new signal A2. In the second embodiment, however, the signal generation circuit 40A can include an amplifier 44A and an amplifier 44B instead of the adders 41A and 41B. The amplifier 44A can generate a new signal A3 based on signal A, whereas the amplifier 44B can generate a new signal A4 based on signal A. Furthermore, the signal generation circuit 40A can receive a signal B0 from the sensor unit 3. A phase difference between signals A and B0 can be set to any value other than 180°.Apart from this, the signal generation circuit 40A can have essentially the same configuration as that of the signal generation circuit 40. Components that are essentially identical to those of the preceding first embodiment will subsequently be designated with the same reference numerals and will not be described where appropriate.

[0043] Amplifier 44A can be an amplifier circuit connected to wire L3, which couples node P5 to comparator 42A. Amplifier 44A can amplify the voltage of signal A flowing through wire L3 within a predetermined range, thereby generating signal A3. Amplifier 44A can then transmit signal A3 to comparator 42A. Similarly, amplifier 44B can be an amplifier circuit connected to wire L4, which couples node P5 and comparator 42B. Amplifier 44B can amplify the voltage of signal A flowing through wire L4 within a predetermined range, thereby generating signal A4. Amplifier 44B can then transmit signal A4 to comparator 42B.In this example, it may be preferable for the amplification ratio of amplifier 44A to signal A to differ from that of amplifier 44B, so that signals A3 and A4 have different waveforms. Fig. Figure 8 illustrates waveforms of signals A3, A, and A4 together with a waveform of signal B0.

[0044] Comparator 42A can compare the amplified signal A3 with signal B0 and output a signal C3 based on the comparison result. Similarly, comparator 42B can compare the amplified signal A4 with signal B0 and output a signal C4 based on the comparison result. Comparator 42C can compare the unamplified signal A with signal B0 and output a signal C0 based on the comparison result. Fig. Figure 8 illustrates waveforms of signals C3, C0, and C4.

[0045] The signals C3, C0, and C4, generated as described above, can be fed to both the AND gate 43A and the AND gate 43B in the combination circuit 43. The outputs of the AND gates 43A and 43B can then be fed to the OR gate 43C, which can then output a signal D2 from its output terminal Vout. Fig. Figure 8 illustrates a waveform of signal D2. [Effects of the rotation detection unit]

[0046] According to the rotation detection unit in the second embodiment, amplifier 44A and amplifier 44B generate two signals, i.e., signal A3 and signal A4 respectively, based on signal A and with different waveforms. Therefore, the second embodiment achieves a similar effect to the first embodiment described above. [4. Other modifications]

[0047] The technology was described above with reference to some embodiments and modifications thereof. However, the technology is not limited to these and can differ in various ways. For example, in some embodiments and modifications thereof, the signal generation circuit creates a multitude of new signals from a single signal using adders or amplifiers. However, these embodiments are merely examples and not limiting.

[0048] As an alternative example, as in Fig. Figure 9 illustrates that the signal generation circuit 40B includes a phase-shift circuit 45A, which generates a new signal A5 based on signal A, and a phase-shift circuit 45B, which generates a new signal A6 based on signal A. The phase-shift circuit 45A can be a phase control circuit, including an inductor, a capacitor, and other electrical components, and can be connected to wire L3, which couples node P5 to comparator 42A. The phase-shift circuit 45A can generate signal A5 by applying a predetermined temporal shift (delay) to signal A, which flows through wire L3, and then transmit signal A5 to comparator 42A.Similarly, phase-shift circuit 45B can be a phase control circuit containing an inductor, a capacitor, and other electrical components, arranged on wire L4, which couples node P5 to comparator 42B. Phase-shift circuit 45B can generate signal A6 by applying a predetermined temporal shift (delay) to signal A flowing through wire L4 and transmitting signal A6 to comparator 42B. In this example, phase-shift circuits 45A and 45B can delay signal A by different time intervals, thereby generating signals A5 and A6 with distinct waveforms. Fig. Figure 10 illustrates waveforms of signals A5, A, and A6 together with the waveform of signal B.

[0049] The comparator 42A can compare the phase-shifted signal A5 with signal B and output a signal C5 based on the comparison result. Similarly, the comparator 42B can compare the phase-shifted signal A6 with signal B and output a signal C6 based on the comparison result. Likewise, the comparator 42C can compare the non-phase-shifted signal A with signal B and output signal C based on the comparison result. Fig. Figure 10 illustrates waveforms of signals C5, C, and C6.

[0050] Furthermore, in the combination circuit 43, the signals C5, C0, and C6 generated in the manner described above can be fed to both the AND gate 43A and the AND gate 43B. The outputs of the AND gates 43A and 43B can then be fed to the OR gate 43C, whereupon the OR gate 43C can output a signal D3 from an output terminal Vout. Fig. Figure 10 illustrates the waveform of signal D3.

[0051] In the present example, signals A5, A, and A6 can intersect signal B at points that are temporally distinct. This makes it possible to output signal D3, which contains the multitude of pulses, when the single protrusion 1T passes between the first and second sensors. Therefore, it is possible to achieve an effect similar to that of the preceding embodiments and modifications thereof.

[0052] Furthermore, instead of circuits such as adders, amplifiers, and phase-shifting circuits, a multiplication circuit can be provided in the signal processor to generate a variety of new signals with different characteristics from a single signal.

[0053] In the aforementioned embodiments and modifications thereof, an analog circuit is described as an example of a signal processor. However, this circuit configuration is merely illustrative and not limiting. Alternatively, the signal processor can be a digital circuit. In this example, for instance, a digital comparator can be used, and a pulse generator can be used instead of the combined circuit. In this case, an analog signal from a sensor can be converted into a digital signal by a circuit such as an A / D comparator to be fed to the signal processor.

[0054] In the foregoing embodiments and modifications thereof, the signal processor generates three new signals (e.g., signals A, A1, and A2) based on the signal from the first sensor. However, the number of newly generated signals is not limited to three. Alternatively, the number of new signals can be two, four, or more.

[0055] The signal processor can generate a multitude of new signals Bn (B1, B2, ... Bn) based solely on signal B from the second sensor. Alternatively, the signal processor can generate a multitude of new signals Am (A1, A2, ... Am) based on signal A from the first sensor, and also generate a multitude of new signals Bn (B1, B2 ... Bn) based on signal B from the second sensor. Fig. Figure 11 illustrates a signal generation circuit 40C as a specific example of this. As in Fig.As illustrated in Figure 11, the signal generation circuit 40C can further include an adder 41C and an adder 41D. The adder 41C can be placed between node P6 and comparator 42A and generate a new signal B1 based on signal B. The adder 41D can be placed between node P6 and comparator 42B and generate a new signal B2 based on signal B. Apart from this, the signal generation circuit 40C can have a configuration that is essentially the same as that of signal generation circuit 40.

[0056] Furthermore, according to the technology, the number of sensors is not limited to two or four, and can be any number of two or greater.

[0057] In the foregoing embodiments and modifications thereof, the gear serving as the movable body has a disk-shaped link with a circumference on which projections and recesses are arranged alternately. This embodiment, however, is exemplary and not limiting. As an alternative example, the movable body can have a disk-shaped link or a circular link with a circumference on which a ferromagnetic part is provided. The ferromagnetic part can be provided with S-pole regions and N-pole regions arranged alternately at predetermined intervals. In the foregoing embodiments and modifications thereof, a rotation detection unit serving as a motion detection unit includes a rotating body. However, the rotating body is exemplary and not limiting. In particular, the rotating body is not limited to the rotating body described above.Alternatively, the rotating body can, for example, be a link that extends linearly in one direction. According to one embodiment of the technology, the motion detection unit can detect movement of this linearly movable body in its direction of extension.

[0058] A person skilled in the art will recognize that various modifications, combinations, sub-combinations, and alterations may occur depending on the design requirements and other factors, provided they are within the scope of protection of the attached claims or their equivalents.

[0059] It is possible to achieve at least the following embodiments from the above-described examples of the technology.

[0060] (1) Motion detection unit comprising: a movable body that performs a movement in a first direction; a first sensor that detects a change in a first magnetic field caused by the movement of the movable body and outputs a first signal; a second sensor, which is provided in the first direction at a location different from the location of the first sensor, wherein the second sensor detects a change in a second magnetic field caused by the movement of the movable body and outputs a second signal; and comprising a signal processor and a signal generation circuit that generates a third signal and a fourth signal based on the first signal, wherein the third signal and the fourth signal have waveforms that are different from each other.

[0061] (2) Motion detection unit according to (1), wherein the movable body includes a gear part with a multitude of projections and a multitude of recesses arranged alternately, and The signal generation circuit further includes a pulse generator that produces a multitude of pulses within a period in which one of the protrusions or one of the depressions passes both the first sensor and the second sensor.

[0062] (3) Motion detection unit according to (1), wherein the movable body includes a ferromagnetic part with a multitude of N-pole regions and a multitude of S-pole regions arranged alternately, and The signal generation circuit further includes a pulse generator that produces a multitude of pulses within a period in which one of the N-pole regions or one of the S-pole regions passes both the first sensor and the second sensor.

[0063] (4) Motion detection unit according to (1), wherein The signal generation circuit also includes: a first comparator that outputs a fifth signal based on a comparison between the third signal and the second signal; a second comparator that outputs a sixth signal based on a comparison between the fourth signal and the second signal; and a pulse generator that combines the fifth signal and the sixth signal, thereby generating a seventh signal containing a multitude of pulses.

[0064] (5) Motion detection unit according to (4), wherein the movable body includes a gear part with a multitude of projections and a multitude of recesses arranged alternately, and The pulse generator produces the multitude of pulses within a period in which one of the protrusions or one of the depressions passes both the first sensor and the second sensor.

[0065] (6) Motion detection unit according to (4), wherein the movable body includes a ferromagnetic part with a multitude of N-pole regions and a multitude of S-pole regions arranged alternately, and The pulse generator produces the multitude of pulses within a period in which one of the N-pole areas or one of the S-pole areas passes both the first sensor and the second sensor.

[0066] (7) Motion detection unit according to (1), wherein the signal generation circuit further generates an eighth signal and a ninth signal based on the second signal, wherein the eighth signal and the ninth signal have different waveforms from each other.

[0067] (8) Motion detection unit according to (7), wherein The signal generation circuit also includes: a third comparator that outputs a tenth signal based on a comparison between the third signal and the eighth signal; a fourth comparator that outputs an eleventh signal based on a comparison between the fourth signal and the ninth signal; and a pulse generator that combines the tenth signal and the eleventh signal to create a twelfth signal containing a multitude of pulses.

[0068] (9) Motion detection unit according to one of (1) to (8), wherein the signal generation circuit includes an adder which adds an offset voltage to the first signal.

[0069] (10) Motion detection unit according to one of (1) to (8), wherein the signal generation circuit includes an amplifier which amplifies the first signal.

[0070] (11) Motion detection unit according to one of (1) to (8), wherein the signal generation circuit includes a phase shift circuit which temporally shifts the first signal.

[0071] Although the technology has been described with reference to exemplary embodiments, it is not limited to these. It should be noted that variations in the described embodiments can be made by a person skilled in the art without deviating from the scope of protection defined by the following claims. The limitations in the claims are to be interpreted broadly in the language used in the claims and are not limited to examples described in this document or during the application process, and the examples are to be interpreted as non-limiting. For example, in this disclosure, the term "preferred" or the like is non-limiting and means "preferred" without being limited to this. The use of the terms first, second, etc., does not denote any order or importance, but rather the terms first, second, etc., are used to distinguish one element from another.The term "essentially" and its variations are defined as principally, but not necessarily completely, as a person skilled in the art would understand. The terms "about" or "approximately," if used here, may permit a certain degree of variability with respect to a value or range. Furthermore, no element or component in this disclosure is intended for public disclosure, regardless of whether the element or component is expressly mentioned in the appended claims or not.

Claims

[1] Motion detection unit comprising: a movable body (1) that performs a movement in a first direction (1R); a first sensor (3A, 3B) that detects a change in a first magnetic field caused by the movement of the movable body (1) and outputs a first signal (A); a second sensor (3C, 3D) provided in the first direction (1R) at a location different from the location of the first sensor (3A, 3B), wherein the second sensor (3C, 3D) detects a change in a second magnetic field caused by the motion of the movable body (1) and outputs a second signal (B, B0); and a signal processor (4) comprising a signal generation circuit (40, 40A, 40B, 40C) which generates a third signal (A1, A3, A5) and a fourth signal (A2, A4, A6) based on the first signal (A), wherein the third signal (A1, A3, A5) and the fourth signal (A2, A4, A6) have waveforms that are different from each other, where The signal generation circuit (40, 40A, 40B, 40C) further includes: a first comparator (42A) which outputs a fifth signal (C1, C3, C5) based on a comparison between the third signal (A1, A3, A5) and the second signal (B, B0); a second comparator (42B) that outputs a sixth signal (C2, C4, C6) based on a comparison between the fourth signal (A2, A4, A6) and the second signal (B, B0); and a pulse generator (43) which combines the fifth signal (C1, C3, C5) and the sixth signal (C2, C4, C6) and thereby generates a seventh signal (D, D1, D2, D3) which contains a plurality of pulses (PL1, PL2, PL3). [2] Motion detection unit according to claim 1, wherein the movable body (1) includes a gear part with a plurality of projections (1T) and a plurality of recesses (1U) arranged alternately, and the pulse generator (43) generates the plurality of pulses (PL1, PL2, PL3) within a period in which one of the projections (1T) or one of the sinks (1U) passes both the first sensor (3A, 3B) and the second sensor (3C, 3D). [3] Motion detection unit according to claim 1, wherein the movable body (1) includes a ferromagnetic part with a plurality of N-pole regions and a plurality of S-pole regions provided alternately, and the pulse generator (43) generates the plurality of pulses (PL1, PL2, PL3) within a period in which one of the N-pole areas or one of the S-pole areas passes both the first sensor (3A, 3B) and the second sensor (3C, 3D). [4] Motion detection unit according to one of claims 1 to 3, wherein the signal generation circuit (40, 40C) includes an adder (41A, 41B) which adds an offset voltage to the first signal (A). [5] Motion detection unit according to one of claims 1 to 3, wherein the signal generation circuit (40A) includes an amplifier (44A, 44B) which amplifies the first signal (A). [6] Motion detection unit according to one of claims 1 to 3, wherein the signal generation circuit (40B) includes a phase shift circuit (45A, 45B) which temporally shifts the first signal (A). [7] Motion detection unit comprising: a movable body (1) that performs a movement in a first direction (1R); a first sensor (3A, 3B) that detects a change in a first magnetic field caused by the movement of the movable body (1) and outputs a first signal (A); a second sensor (3C, 3D) provided in the first direction (1R) at a location different from the location of the first sensor (3A, 3B), wherein the second sensor (3C, 3D) detects a change in a second magnetic field caused by the motion of the movable body (1) and outputs a second signal (B, B0); and a signal processor (4) comprising a signal generation circuit (40, 40A, 40B, 40C) that generates a third signal (A1, A3, A5) and a fourth signal (A2, A4, A6) based on the first signal (A), wherein the third signal (A1, A3, A5) and the fourth signal (A2, A4, A6) have waveforms that are different from each other, wherein the signal generation circuit (40C) further generates an eighth signal (B1) and a ninth signal (B2) based on the second signal (B), wherein the eighth signal (B1) and the ninth signal (B2) have waveforms that are different from each other; and wherein The signal generation circuit (40C) further includes: a third comparator (42A) which outputs a tenth signal (C1) based on a comparison between the third signal (A1) and the eighth signal (B1); a fourth comparator (42B) that outputs an eleventh signal (C2) based on a comparison between the fourth signal (A2) and the ninth signal (B2); and a pulse generator (43) which combines the tenth signal (C1) and the eleventh signal (C2) and thereby generates a twelfth signal (D) which contains a plurality of pulses (PL1, PL2, PL3). [8] Motion detection unit according to claim 7, wherein the signal generation circuit (40, 40C) includes an adder (41A, 41B) which adds an offset voltage to the first signal (A). [9] Motion detection unit according to claim 7, wherein the signal generation circuit (40A) includes an amplifier (44A, 44B) which amplifies the first signal (A). [10] Motion detection unit according to claim 7, wherein the signal generation circuit (40B) includes a phase shift circuit (45A, 45B) that temporally shifts the first signal (A).

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