JP2006126096A - Rotation sensor, rotation detecting method, proximity sensor and object sensing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a rotation frequency, a rotation speed and the like of a rotating body to be detected precisely in real time in a wide temperature range from a low temperature to a high temperature. <P>SOLUTION: A rotation sensor 10A is provided, which detects at least the rotation frequency of the rotating body 14 having a plurality of indented portions 12 along its circumferential direction. The rotation sensor 10A comprises; a core 20 which has a bending section 26 including two end faces 20a, 20b facing in the same direction and is disposed such that the second end face 20b is opposite to the indented portions 12 of the rotating body 14; a primary coil 22 which is mounted on the core 20 and supplied with high-frequency current i; a sensor main body 16 which has a secondary coil 24 being mounted on the core 20; and a detecting circuit 18 which detects at least the rotation frequency of the rotating body 14 by sensing an electromotive force V2 induced across the secondary coil 24 on the basis of variations in flux passing through at least the secondary coil 24 caused by rotation of the rotating body 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation sensor and a rotation detection method for detecting at least the rotation speed, rotation angle and rotation direction of a rotating body having a plurality of irregularities in the circumferential direction in a wide temperature range from a low temperature to a high temperature, The present invention relates to a proximity sensor and an object detection method for detecting at least that an object is approaching without contact.

Conventional tachometers: (1) using eddy currents due to magnetism, (2) using light emitting / receiving elements, (3) using a method of capturing changes in magnetic flux direction using Hall elements There is.
Japanese Patent Laid-Open No. 8-233843 JP 2002-170316 A JP, 2003-139564, A Using magnetic eddy currents, magnets and magnetic sensors that are adjacent to each other are arranged opposite to a conductive movable body that can move relative to the direction in which these magnets and magnetic sensors are arranged. Has proposed a device in which a magnetic sensor detects a magnetic field generated by an eddy current induced in a moving body and a generated current induced in the moving body (for example, a patent document). 1).

  A light-emitting / light-receiving element includes a turntable on which a disk is placed, a clamper that is attached to the turntable and fixes the disk placed on the turntable, and a rotational force on the turntable. A rotation number detecting means for detecting the number of rotations of the disk, for example, a light sensor including a light emitting element and a light receiving element, and the clamper, and is provided integrally with the clamper. There has been proposed one provided with a reflector that reflects light from the light emitting element (see, for example, Patent Document 2).

  The magnetic Hall element includes a Hall element that detects the approach of the magnetic rotating body, a permanent magnet that applies a magnetic field to the Hall element adjacent to the Hall element, and the Hall element, the permanent magnet, and the Hall element electrically There has been proposed a rotation sensor including a main body portion on which a connected terminal is mounted and a connector portion having a terminal portion for leading the terminal to the outside (see, for example, Patent Document 3).

  Conventional tachometers have problems in temperature environment from high temperature to low temperature, dust environment, high cost, difficulty of breaking, vibration resistance, shock resistance, real-time characteristics, and the like.

  The present invention has been made in consideration of such problems, and can detect the rotational speed, rotation speed, etc. of the rotating body with high accuracy in real time, and can prevent environmental noise including electromagnetic noise. Rotation sensor and rotation that have high resistance, resistance to high temperature to low temperature and dust environment, and are advantageous for cost reduction, and can contribute to the resistance to breakage, vibration resistance, and impact resistance. An object is to provide a detection method.

  Another object of the present invention is to accurately detect the approaching or moving away of an object in a non-contact manner and with high resistance to environmental noise including electromagnetic noise, from high temperature to low temperature. Another object of the present invention is to provide a proximity sensor and an object detection method that are resistant to temperature environments and dust environments, are advantageous in reducing costs, and contribute to resistance to breakage, vibration resistance, and impact resistance.

  The rotation sensor according to the present invention is a rotation sensor that detects at least the number of rotations of a rotating body having a plurality of excision portions in a non-contact manner, and includes a bending portion having two end faces facing in the same direction, and Of the two end faces, a core disposed so that at least one end face faces the cut portion of the rotating body, a primary coil attached to the core and supplied with an AC signal, and the core A sensor body having an attached secondary coil, and detecting an electromotive voltage induced in the secondary coil based on at least a change in magnetic flux passing through the secondary coil as the rotating body rotates. And a detection circuit for detecting at least the number of rotations of the rotating body.

  And the said core is arrange | positioned so that one end surface may oppose the main surface of the said rotary body, and the other end surface may oppose the said cutting part of the said rotary body among the said two end surfaces. Good. Alternatively, the core may be arranged so that the two end faces face the cut portion of the rotating body.

  The cut portion may be a plurality of irregularities formed in the circumferential direction of the rotating body. In this case, in the core, when the one end surface is at a position facing the convex portion of the rotating body, the other end surface is also at a position facing the same convex portion, and the one end surface is the position of the rotating body. When it exists in the position which opposes a recessed part, you may arrange | position so that the said other end surface may also be made into the position which opposes the same recessed part.

  The detection circuit may include a circuit that detects the rotational speed of the rotating body based on the frequency of the electromotive force induced in the detected secondary coil.

  Moreover, the said structure WHEREIN: You may make it have the said sensor main body and the said detection circuit has a circuit which detects the rotation direction of the said rotary body based on the electromotive force from each sensor main body.

  Next, the rotation detection method according to the present invention is a rotation detection method for detecting at least the number of rotations of a rotating body having a plurality of cut portions, and a core having bending portions each having two end faces facing in the same direction. A sensor body having a primary coil attached to the core and supplied with an AC signal, and a secondary coil attached to the core, the sensor body being attached to the two end faces of the core. Among them, at least one end face is arranged so as to face the cut portion of the rotating body, and is guided to the secondary coil based on a change in magnetic flux passing through at least the secondary coil as the rotating body rotates. By detecting an electromotive voltage generated, at least the number of rotations of the rotating body is detected.

  Next, a proximity sensor according to the present invention is a proximity sensor that detects at least that an object is approaching in a non-contact manner, and includes a bent portion having two end faces facing in the same direction, and the two end faces. A sensor body having a core disposed so as to face the object, a primary coil attached to the core and supplied with an AC signal, and a secondary coil attached to the core; As the object approaches or moves away from the core, the object approaches or moves away by detecting an electromotive voltage induced in the secondary coil based on at least a change in magnetic flux passing through the secondary coil. And a detection circuit for detecting.

  Next, an object detection method according to the present invention is an object detection method for detecting at least that an object is approaching in a non-contact manner, wherein the core includes a bent portion having two end faces facing in the same direction, and the core. A sensor body having a primary coil to which an alternating current signal is supplied and a secondary coil attached to the core is prepared, and the sensor body has the two end faces of the core of the rotating body. An electromotive voltage induced in the secondary coil based on a change in magnetic flux passing through at least the secondary coil as the object approaches or moves away from the core. By detecting, it is detected that the object approaches or moves away.

  According to the rotation sensor and the rotation detection method of the present invention, it is possible to detect the number of rotations, the rotation speed, and the like of the rotating body with high accuracy in real time, and it is highly resistant to environmental noise including electromagnetic noise. It is resistant to temperature and dust environments from high to low temperatures, and is advantageous for cost reduction, and can contribute to resistance to breakage, vibration resistance, and impact resistance.

  In addition, the proximity sensor and the object detection method according to the present invention can accurately detect whether an object is approaching or moving away in a non-contact manner, and is highly resistant to environmental noise including electromagnetic noise. It is resistant to temperature and dust environments from high to low temperatures, and is advantageous for cost reduction, and can contribute to resistance to breakage, vibration resistance, and impact resistance.

  Hereinafter, embodiments of a rotation sensor, a rotation detection method, a proximity sensor, and an object detection method according to the present invention will be described with reference to FIGS. 1A to 11.

  First, embodiments of a rotation sensor and a rotation detection method according to the present invention will be described with reference to FIGS. 1A to 10.

  As shown in FIG. 1A or 1B, the rotation sensor 10A according to the first embodiment is a rotation sensor that detects at least the number of rotations of a rotating body 14 having a plurality of cut portions 11 without contact. A sensor main body 16 and a detection circuit 18 are included.

  As shown in FIG. 1A, the excision part 11 may be a plurality of irregularities 12 formed along the circumference of the rotating body 14 and formed radially from the center of rotation, as shown in FIG. 1B. The plurality of through holes 13 provided in the rotating body 14 may be used. In the following description, as shown in FIG. 1A, a rotating body 14 having a plurality of irregularities 12 formed in the circumferential direction will be mainly described.

  The sensor body 16 includes a core 20, a primary coil (excitation coil) 22 attached to the core 20, and a secondary coil (detection coil) 24 attached to the core 20. A detection circuit 18 is connected to the secondary coil 24.

  As shown in FIG. 2A, the core 20 includes a bent portion 26 having two end surfaces (first end surface 20a and second end surface 20b) facing in the same direction. The bent portion 26 is formed in, for example, a U shape, a U shape, a C shape, or the like. That is, the “bending” of the bent portion 26 includes a bend and a bend. In the example of FIG. 1, the case where it forms in U shape is shown. The core 20 can be made of a magnetic material such as a ferrite core.

  A high frequency generator 28 is connected to the primary coil 22, and a high frequency current i is supplied from the high frequency generator 28 to the primary coil 22.

  On the other hand, the rotator 14 is formed of, for example, a magnetic material in a flat plate shape, and a plurality of irregularities 12 (irregularities 12 in which the concave portions 30 and the convex portions 32 are repeated) are formed on the outer circumferential portion thereof. In the example of FIG. 1, it is assumed that the arrangement pitch of the plurality of protrusions 32 (or recesses 30) is substantially the same, but the arrangement pitch may be different depending on the location. In addition, although it is preferable that the rotary body 14 is comprised with the magnetic body, you may be comprised with the material with which the magnetic body and the nonmagnetic body (copper, aluminum, etc.) were mixed.

  In this embodiment, the core 20 of the sensor body 16 has the first end surface 20a of the first and second end surfaces 20a and 20b opposed to one main surface 14a of the rotating body 14, and The second end face 20 b is disposed so as to face the unevenness 12 of the rotating body 14. That is, the core 20 is arranged in a direction perpendicular to the surface of the rotating body 14, the first end surface 20a of the core 20 is always opposed to the main surface 14a of the rotating body 14, and the second end surface 20b is set to the rotating body 14. Are arranged on a path through which the concave portion 30 passes when rotating, and as the rotating body 14 rotates, the side surfaces of the plurality of convex portions 32 of the rotating body 14 with respect to the second end surface 20b (the main surface of the rotating body 14). 14a) are opposed to each other in order.

  Here, the detection principle of the rotation sensor 10A according to the first embodiment will be described with reference to FIGS.

  First, when a high-frequency current i is supplied from the high-frequency generator 28 to the primary coil 22, a bundle of magnetic field lines (magnetic flux) corresponding to the change in the current i passes through the core 20 due to a change in the current flowing through the primary coil 22. It will be.

At this time, an electromotive force is induced in the secondary coil 24 based on a change in magnetic flux passing through the secondary coil 24. Here, if the number of turns of the secondary coil 24 is N, and the magnetic flux passing through the secondary coil 24 is changed by Δφ, the electromotive force V2 induced in the secondary coil 24 is expressed by the following equation.

V2 = N × (Δφ / Δt)
Therefore, considering only the sensor body 16, the change in the magnetic flux is proportional to the change in the current i supplied to the primary coil 22, and the voltage (electromotive force V2) output from the secondary coil 24 is As shown in FIG. 3, the waveform has substantially the same frequency as the frequency of the current i supplied to the primary coil 22.

  In this state, as the rotating body 14 rotates, when the convex portion 32 does not face the second end surface 20b of the core 20, that is, as shown in FIG. 2B, the space 34 of the concave portion 30 faces. When it is, the magnetic flux leaking from the core 20 increases. Therefore, the output voltage V2 of the secondary coil 24 based on the change of the magnetic flux is proportional to the change of the high-frequency current i supplied to the primary coil 22, as shown in FIGS. 4A and 4B (the frequencies are almost the same). ), But its peak value (amplitude) P1 is small.

  As the rotating body 14 rotates, when the convex portion 32 faces the second end surface 20b of the core 20 as shown in FIG. 2A, the core 20 and the convex portion 32 make an apparent ring core (magnetic flux loop 36). Therefore, the magnetic flux leaking from the core 20 is reduced. Therefore, the output voltage V2 of the secondary coil 24 based on the change of the magnetic flux is proportional to the change of the high-frequency current i supplied to the primary coil 22, as shown in FIGS. 4A and 4B (the frequencies are almost the same). ) And the peak value (amplitude) P <b> 2 is larger than when the convex portion 32 does not face the second end surface 20 b of the core 20.

  That is, the secondary coil 24 alternately outputs a high-frequency voltage Va having a small peak value (amplitude) P1 and a high-frequency voltage Vb having a large peak value (amplitude) P2 as the rotating body 14 rotates. become.

  On the other hand, as shown in FIG. 5, the detection circuit 18 detects the envelope waveform Se of the voltage V2 output from the secondary coil 24, and the envelope waveform Se output from the detection circuit 38 into a rectangular shape. A waveform shaping circuit 40 that shapes the pulse waveform and outputs it as a pulse train signal Sp.

  As described above, when the second end surface 20b of the core 20 is opposed to the space 34 (see FIG. 2B) of the concave portion 30 and when it is opposed to the convex portion 32, the secondary coil 24 The peak value (amplitude) of the output voltage V2 varies between P1 and P2 (see FIG. 4B). Accordingly, as shown in FIG. 4C, the envelope waveform Se corresponding to the convex portions 32 and the concave portions 30 of the rotating body 14 is output from the detection circuit 38, and the waveform shaping circuit 40, for example, as shown in FIG. The pulse train signal Sp in which the rectangular pulse waveform Pw appears at the timing when the convex portion 32 of the rotating body 14 faces the second end face 20b of the core 20 is output. By counting the number of pulse waveforms Pw (number of pulses) included in the pulse train signal Sp, the number of rotations of the rotating body 14 is detected. As shown in FIG. 5, by connecting a counter 42 that counts the pulse waveform Pw included in the pulse train signal Sp output from the waveform shaping circuit 40 to the subsequent stage of the waveform shaping circuit 40, The rotational speed can be taken out as numerical data Ds, which is suitable for digital processing such as a computer. As a result, the instantaneous speed can be calculated and used for ABS control and the like. In that case, real-time performance is good and better ABS control can be achieved.

  By the way, the output timing of the pulse waveform Pw included in the pulse train signal Sp output from the waveform shaping circuit 40, that is, the pulse period Tp (see FIG. 4D) is the convex portion of the rotating body 14 on the second end face 20b of the core 20. 32 is substantially the same as the facing timing, so that if the rotational speed of the rotator 14 is increased, the pulse period Tp is shortened (frequency is increased), and if the rotational speed is decreased, the pulse period Tp is increased (frequency). Is low). Therefore, as shown in FIG. 5, by connecting the frequency-voltage conversion circuit 44 to the subsequent stage of the waveform shaping circuit 40, the frequency-voltage conversion circuit 44 can rotate as shown in FIGS. 6A to 6C. A voltage signal Vp whose voltage level changes according to the rotational speed of the body 14 can be extracted. In the example of FIG. 6, the frequency of the pulse train signal Sp increases and the voltage level of the voltage signal Vp increases as the rotational speed of the rotating body 14 increases. For example, from the frequency-voltage conversion circuit 44, the rotating body 14 is 0V when stopped, 3V when the rotating body 14 is rotating at a low speed, and 6V when the rotating body 14 is rotating at a medium speed. If 14 is rotating at high speed, 9V is output.

  As described above, in the rotation sensor 10A according to the first embodiment, unlike the conventional type that detects a minute change in the open magnetic flux, the rotation between the core 20 and the rotation body 14 during the rotation of the rotation body 14 occurs. Since it is detected whether or not the magnetic flux loop 36 is completed in between, the movement of the unevenness 12 accompanying the rotation of the rotating body 14 can be grasped as a large amplitude change, and the rotational speed and rotational speed of the rotating body 14 etc. Can be detected in real time with high accuracy. Further, capturing the movement of the unevenness 12 accompanying the rotation of the rotating body 14 as a large amplitude change leads to an improvement in proximity sensitivity, and has a great resistance to environmental noise including electromagnetic noise. This is resistant to high and low temperature environments and dusty environments, and can be assembled with a simple structure, leading to lower costs, less breakage, vibration resistance, and impact resistance. Can also contribute to sex.

  The same applies to the through hole 13 in which the excision 11 is provided in the rotating body 14 as shown in FIG. 1B. That is, when the through hole 13 is opposed to the second end face 20b of the core 20, the magnetic flux leaking from the core 20 increases, so that the peak value (amplitude) of the output voltage V2 of the secondary coil 24 is small, and the core 20 When the through-hole 13 does not face the second end face 20b, the ring core (magnetic flux loop 36) is apparently formed, so that the peak value (amplitude) of the output voltage V2 of the secondary coil 24 increases. . 1B shows an example in which the second end face 20b of the core 20 is positioned so as to face the through hole 13 formed along the circumference indicated by the one-dot chain line m of the rotating body 14. However, although not shown in the drawings, a through hole may be formed along the circumference where the first end face 20a of the core 20 faces, that is, the circumference indicated by the two-dot chain line n. In this case, as the rotating body rotates, the first end face 20a of the core 20 faces the through-hole, so that, similarly to the above, by monitoring the output voltage V2 of the secondary coil 24, The number of rotations of the rotator 14 can be detected in real time.

  Next, a rotation sensor 10B according to a second embodiment will be described with reference to FIGS. Note that members corresponding to those in the first embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

  As shown in FIG. 7, the rotation sensor 10 </ b> B according to the second embodiment has substantially the same configuration as the rotation sensor 10 </ b> A according to the first embodiment described above, but the two end faces 20 a of the core 20. And 20b are different in that the core 20 is disposed so as to face the irregularities 12 of the rotating body 14.

  Specifically, the core 20 is disposed so that the first and second end surfaces 20 a and 20 b are both opposed to the outer peripheral surface of the rotating body 14. Therefore, as shown in FIG. 8A, if the first end surface 20a is at a position facing the convex portion 32 of the rotating body 14, the second end surface 20b is also at a position facing the same convex portion 32, and FIG. As shown, when the first end surface 20 a is at a position facing the recess 30 of the rotating body 14, the second end surface 20 b is also at a position facing the same recess 30.

  As the rotating body 14 rotates, as shown in FIG. 8B, when the concave portion 30 faces the first and second end faces 20a and 20b of the core 20, the magnetic flux leaking from the core 20 increases. The output voltage V2 of the secondary coil 24 based on the change of the magnetic flux is proportional to the change of the high-frequency current i supplied to the primary coil 22 (frequency becomes substantially the same), but its peak value (amplitude) P1 is small. (See FIG. 4B).

  As the rotating body 14 rotates, as shown in FIG. 8A, when the convex portion 32 faces the first and second end faces 20 a and 20 b of the core 20, the core 20 and the convex portion 32 make an appearance. Since the ring core (magnetic flux loop 36) is formed and the magnetic flux leaking from the core 20 is reduced, the output voltage V2 of the secondary coil 24 based on the change of the magnetic flux is the high-frequency current supplied to the primary coil 22. The peak value (amplitude) P2 is proportional to the change of i (the frequencies are substantially the same), and is larger than when the concave portion 30 faces the first and second end faces 20a and 20b of the core 20. (See FIG. 4B).

  Therefore, also in the second embodiment, from the waveform shaping circuit 40 of the detection circuit 18, for example, at the timing when the convex portion 32 of the rotating body 14 faces the first and second end faces 20 a and 20 b of the core 20. The pulse train signal Sp in which the rectangular pulse waveform Pw appears is output. Further, by connecting the frequency-voltage conversion circuit 44 to the subsequent stage of the waveform shaping circuit 40, the voltage signal Vp whose voltage level changes according to the rotation speed of the rotating body 14 can be taken out.

  As described above, also in the rotation sensor 10B according to the second embodiment, the rotational speed, the rotation speed, and the like of the rotating body 14 are highly accurate in real time as in the rotation sensor 10A according to the first embodiment described above. Can be detected. Since proximity sensitivity is also high, it has great resistance to environmental noise including electromagnetic noise, and resistance to high temperature to low temperature and dust environments. In addition, it is advantageous for cost reduction, and can contribute to the difficulty of breakage, vibration resistance, and impact resistance.

  Which one of the rotation sensor 10A according to the first embodiment and the rotation sensor 10B according to the second embodiment is used depends on the thickness t of the rotating body 14 (FIGS. 1, 2A, 7 and 8A). Reference) and the structure around the rotating body 14 may be used. For example, when the thickness t of the rotating body 14 is thin, it is difficult to make both the first and second end faces 20a and 20b face one convex portion 32. Therefore, the rotation sensor 10A according to the first embodiment can be Use it. On the other hand, when the thickness t of the rotating body 14 is thick, even if the second end face 20b of the core 20 faces the space 34 of the recess 30, the magnetic flux enters through the bottom of the recess 30, and apparently the ring core (flux loop) ) May be formed, the peak value (amplitude) of the voltage V2 output from the secondary coil 24 may hardly change. Therefore, in this case, the rotation sensor 10B according to the second embodiment may be used.

  As shown in FIG. 1B, when a plurality of through holes 13 are formed in the rotating body 14 instead of the irregularities 12, the rotation sensor 10A according to the first embodiment is optimal.

  Next, a rotation sensor 10C according to a third embodiment will be described with reference to FIGS. 9 to 10B.

  The rotation sensor 10C according to the third embodiment uses two sensor bodies (a first sensor body 16A and a second sensor body 16B) as shown in FIG. A detection circuit 18 is connected to the subsequent stage of the first and second sensor bodies 16A and 16B.

  The detection circuit 18 includes a first detection circuit 38A connected to the subsequent stage of the first sensor body 16A, a first waveform shaping circuit 40A connected to the subsequent stage of the first detection circuit 38A, and a second A second detection circuit 38B connected to the subsequent stage of the sensor body 16B, a second waveform shaping circuit 40B connected to the subsequent stage of the second detection circuit 38B, and the first and second waveform shaping circuits 40A. And a rotation direction detection circuit 46 connected to the subsequent stage of 40B.

  The rotation direction detection circuit 46 outputs the pulse waveform included in the first pulse train signal Sp1 from the first waveform shaping circuit 40A and the pulse included in the second pulse train signal Sp2 from the second waveform shaping circuit 40B. The rotational direction of the rotating body 14 is detected from the difference from the waveform output timing.

  And in this 3rd Embodiment, when it demonstrates with the arrangement | positioning similar to the rotation sensor 10B which concerns on 2nd Embodiment, as shown in FIG. 9, when the rotary body 14 has stopped, for example, One sensor body 16A is disposed such that the first and second end faces 20a and 20b of the core 20 face the convex portion 32a, and the second sensor body 16B is disposed on the first and second sides of the core 20. The end surfaces 20a and 20b are arranged so as to face the boundary between another convex portion 32b and the concave portion 30 (the boundary near the convex portion 32a in the example of FIG. 9).

  In the arrangement of FIG. 9, when the rotating body 14 rotates in the forward direction (for example, clockwise as viewed from FIG. 9: indicated by an arrow M), as shown in FIG. 10A, the output is output from the first waveform shaping circuit 40A. Since the rise time t1 of the pulse waveform Pw1 of the first pulse train signal Sp1 is earlier than the rise time t2 of the pulse waveform Pw2 of the second pulse train signal Sp2 output from the second waveform shaping circuit 40B, the rotation direction is detected. From the circuit 46, for example, a logic “01” indicating a forward rotation is output.

  On the other hand, when the rotating body 14 is rotated in the reverse direction (for example, counterclockwise when viewed from FIG. 9: indicated by the arrow N), as shown in FIG. 10B, the first output from the first waveform shaping circuit 40A. Since the rise time t1 of the pulse waveform Pw1 of the pulse train signal Sp1 of the second pulse train signal Sp1 is later than the rise time t2 of the pulse waveform Pw2 of the second pulse train signal Sp2 output from the second waveform shaping circuit 40B, the rotation direction detection circuit 46 From, for example, logic “10” indicating reverse rotation is output.

  Thus, in the rotation sensor 10C according to the third embodiment, the rotation direction of the rotating body 14 can be easily detected by arranging the two sensor bodies 16A and 16B. Of course, the rotational speed and rotational speed of the rotating body 14 are detected through the first sensor body 16A or the second sensor body 16B.

  In the example of FIG. 9, the same arrangement as the rotation sensor 10 </ b> B according to the second embodiment has been described. However, the arrangement of the rotation sensor 10 </ b> A according to the first embodiment may be used, and the first and second implementations may be used. A combination of the arrangements of the rotation sensors 10A and 10B according to the embodiment may be used. Of course, three or more sensor elements may be arranged.

  In addition, in order to detect one rotation of the rotating body 14, the number of concave or convex surrounding the rotating body is counted in advance, and the number of pulses (or the number of intervals between pulses) corresponding to that number is measured. Alternatively, it may be determined by forming a concave or convex portion having a different distance along the rotation direction with another unevenness at a predetermined position, and detecting a pulse having a different pulse width.

  Next, the proximity sensor 50 according to the present embodiment will be described with reference to FIG. In addition, about the thing corresponding to FIG. 1, the same code | symbol is described and the duplicate description is abbreviate | omitted.

  As shown in FIG. 11, the proximity sensor 50 uses a sensor body that is substantially the same as the sensor body 16 of the rotation sensor 10A according to the first embodiment described above.

  That is, the sensor body 16 includes a core 20, a primary coil 22 attached to the core 20, and a secondary coil 24 attached to the core 20. A detection circuit 18 is connected to the secondary coil 24. The detection circuit 18 has at least a detection circuit 38 (see FIG. 5).

  A high frequency generator 28 is connected to the primary coil 22, and a high frequency signal i is supplied from the high frequency generator 28 to the primary coil 22.

  Then, by supplying the high frequency signal i from the high frequency generator 28 to the primary coil 22, the secondary coil 24 outputs a voltage V 2 having substantially the same frequency as the frequency of the current i supplied to the primary coil 22. Is done.

  In this state, when the object 52 is away from the sensor body 16 (indicated by a two-dot chain line), the magnetic flux leaking from the core 20 increases, so that the output voltage V2 of the secondary coil 24 based on the change of the magnetic flux is Although proportional to the change of the high-frequency current i supplied to the primary coil 22 (frequency is substantially the same), its peak value (amplitude) P1 is small (see FIG. 4B).

  When the object 52 approaches the sensor body 16 and a part of the object 16 faces the first and second end surfaces 20a and 20b of the core 20 (when the object 16 is at a position indicated by a solid line), the core 20 Since the ring core (flux loop 36) is apparently formed by the object 52 and the object 52, the magnetic flux leaking from the core 20 is reduced, and the output voltage V2 of the secondary coil 24 based on the change of the magnetic flux is the primary coil. 22 is proportional to the change in the high-frequency current i supplied to 22 (the frequencies are substantially the same), and its peak value (amplitude) P2 is larger than when the object 52 is moving away (see FIG. 4B).

  As described above, in the proximity sensor 50 according to the present embodiment, by monitoring the output waveform of the detection circuit 38 (see FIG. 5) in the detection circuit 18, it is possible to determine whether the object 52 is approaching or moving away without contact. Can be detected with high accuracy.

  That is, unlike the conventional type that detects a minute change in the open magnetic flux, the magnetic flux loop 36 is completed by directing the first and second end faces 20a and 20b of the core 20 toward the adjacent object (object 52). Therefore, it can be detected as a large amplitude change.

  Moreover, since the proximity sensor 50 according to the present embodiment can take a large proximity sensitivity, it has a great resistance to environmental noise including electromagnetic noise. In addition, a small change in distance between the both ends of the core and the object can be regarded as a large voltage change, and there is an advantage that detection accuracy is high.

  The rotation sensor, the rotation detection method, the proximity sensor, and the object detection method according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention. is there. For example, FIG. 12 shows a modification of the rotation sensor according to the first embodiment of FIG. 1A. In that example, irregularities 30 and 32 are formed on the rotating body detected by the rotation sensor toward the center of rotation. By arranging the end faces 20a, 20b of the core 20 of the rotation sensor above the irregularities 30, 32, the rotational speed of the rotating body is detected. FIG. 13 shows a modification of the rotation sensor according to the second embodiment of FIG. In that example, irregularities 30 and 32 are formed on the rotating body detected by the rotation sensor toward the center of rotation. By arranging the end surface 20a and the end surface 20b of the core 20 of the rotation sensor in the concave portion 30 or the convex portion 32, the number of rotations of the rotating body and the like are detected. Although not shown, a sensor body larger than the sensor body 16 of the rotation sensor shown in FIG. 13 and deformed into a substantially C shape is used, and both sides of the convex portion 32 are formed by both end faces 20a and 20b of the sensor body 16. The sensor body may be arranged so as to sandwich each of the surfaces.

FIG. 1 is a perspective view showing a configuration of the rotation sensor according to the first embodiment with a part thereof omitted, and FIG. 1A is an example corresponding to a rotating body in which irregularities are formed outward from the center of rotation. FIG. 1B shows an example corresponding to a rotating body in which a plurality of through holes are formed. FIG. 2A is an explanatory view showing a state where the second end face of the core and the convex part of the rotating body are opposed to each other, and FIG. 2B is a state where the second end face of the core and the space of the concave part of the rotating body are opposed to each other. It is explanatory drawing which shows. FIG. 3 is a diagram showing a waveform of an electromotive force (output voltage) induced in the secondary coil when a high-frequency current of the primary coil is passed. 4A is a diagram illustrating timing when the sensor main body and the concave portion and the convex portion face each other, FIG. 4B is a waveform diagram illustrating an output voltage of the secondary coil, and FIG. 4C is an envelope output from the detection circuit. FIG. 4D is a waveform diagram showing a pulse train signal output from the waveform shaping circuit. FIG. 5 is a block diagram showing the configuration of the detection circuit. FIG. 6A is a diagram showing how the rotational speed of the rotating body changes, and FIG. 6B is a waveform diagram showing how the frequency of the pulse train signal output from the waveform shaping circuit changes depending on the rotational speed of the rotating body. FIG. 6C is a diagram illustrating a voltage waveform output from the frequency-voltage conversion circuit. FIG. 7 is a perspective view showing a part of the configuration of the rotation sensor according to the second embodiment with a part omitted, and a perspective view showing an example corresponding to a rotating body in which unevenness is formed from the rotation center to the outside. FIG. FIG. 8A is an explanatory view showing a state in which the first and second end faces of the core and the convex part of the rotating body face each other, and FIG. 8B shows the first and second end faces of the core and the concave part of the rotating body. It is explanatory drawing which shows the state which faced. FIG. 9 is a configuration diagram illustrating a rotation sensor according to the third embodiment. FIG. 10A is a diagram showing the waveforms of the first and second pulse train signals when the rotating body is rotated forward, and FIG. 10B is the first and second pulse train signals when the rotating body is rotated backward. It is a figure which shows these waveforms. FIG. 11 is a configuration diagram illustrating the proximity sensor according to the present embodiment. FIG. 12 is a perspective view showing a modification of the rotation sensor according to the first embodiment of FIG. 1A, and is a perspective view showing an example corresponding to a rotating body in which irregularities are formed toward the rotation center. . FIG. 13 is a perspective view showing a modification of the rotation sensor according to the second embodiment of FIG. 7, and is a perspective view showing an example corresponding to a rotating body in which irregularities are formed toward the rotation center. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 10A, 10B, 10C ... Rotation sensor 12 ... Concavity and convexity 14 ... Rotating body 14a ... Main surface 16 ... Sensor main body 18 ... Detection circuit 20 ... Core 20a ... 1st end surface 20b ... 2nd end surface 22 ... Primary coil 24 ... 2 Next coil 26 ... Bending part 28 ... High frequency generator 30 ... Concave part 32 ... Convex part 36 ... Magnetic flux loop 38 ... Detection circuit 40 ... Waveform shaping circuit 44 ... Frequency-voltage conversion circuit 46 ... Rotation direction detection circuit 50 ... Proximity sensor 52 ... object

Claims (11)

A rotation sensor for detecting the rotation of a rotating body having a plurality of cut portions formed at intervals along a circumference in a non-contact manner,
A core having two end surfaces facing the rotating body, and a core disposed so that at least one of the two end surfaces faces the cut portion of the rotating body;
An exciting coil attached near the one end face of the core;
A detection coil attached near the other end face of the core;
A detection circuit that detects an electromotive force induced in the detection coil, and the magnitude of the electromotive force generated in the detection coil when the end surface of the core passes through the plurality of cut portions when the rotating body rotates. A rotation sensor that detects the rotation of the rotating body based on the change of the rotation.   2. The rotation sensor according to claim 1, wherein one end face of the core faces the main surface of the rotating body and the other end face faces the cut portion of the rotating body. A rotation sensor characterized by being arranged.   2. The rotation sensor according to claim 1, wherein the core is disposed such that the two end faces face the cut portion of the rotating body.   The rotation sensor according to any one of claims 1 to 3, wherein the cut portion is a recess formed at intervals along an outer edge of the rotating body.   The rotation sensor according to any one of claims 1 to 3, wherein the cut portion is a hole formed at intervals along a rotation direction of the rotating body.   The rotation sensor according to claim 1, wherein the detection circuit rotates the rotating body based on a pulse corresponding to a change in the magnitude of the electromotive force induced in the detection coil. A rotation sensor characterized by detecting.   The rotation sensor according to claim 6, wherein the detection circuit determines a rotation number, a rotation speed, or a rotation angle of the rotating body based on the pulse number.   The rotation sensor according to claim 6, wherein the detection circuit determines a rotation speed, a rotation speed, or a rotation angle of the rotating body by converting the pulse frequency into a voltage. The rotation sensor according to any one of claims 1 to 6,
A rotation sensor comprising: a plurality of rotation sensors arranged on the rotation body; and a circuit that detects a rotation direction of the rotation body based on a detection output from each detection circuit. In a proximity sensor that detects that an object is approaching without contact,
A core having a bent portion having two end faces arranged to face the object;
An exciting coil attached near the one end face of the core;
A detection coil attached near the other end face of the core;
A detection circuit for detecting an electromotive force induced in the detection coil, and a change in the magnitude of the electromotive force generated in the detection coil when the distance between the object and the end surface of the core changes. And a proximity sensor for detecting that the object is approaching or moving away from the proximity sensor. In an object detection method for detecting that an object is approaching without contact,
A core having a bent portion having two end faces, comprising: an excitation coil attached near one end face of the core; and a detection coil attached near the other end face of the core Arranging the two end faces of the core to face the object;
Detecting a change in the magnitude of the electromotive force generated in the detection coil when the distance between the object and the end face of the core changes;
An object detection method comprising: detecting that the object approaches or moves away from the proximity sensor based on a change in the magnitude of the electromotive force.

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