JP2009053186A - Moving body detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving body detector with simplified configuration, stably and properly sensing. <P>SOLUTION: The moving body detector 1 includes a magnetic scale portion 11 having a magnetic pattern along the predetermined direction; a highly magnetized portion 14 with higher magnetization than the magnetic pattern applied to one end in the predetermined direction of the magnetic scale portion 11; a magnetic field-generating means 13 closely disposed to the magnetic scale portion 11; and a magnetic detector 12 movably disposed along the predetermined direction of the magnetic scale portion 11 closely facing to the magnetic scale portion 11 and detecting the magnetic pattern and the magnetic field of the highly magnetized portion 14. The magnetic pattern and highly magnetized portion 14 are placed on a moving trace of the magnetic detector 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a moving body detector, and more particularly to a moving body detector using a scale material.

  Conventionally, magnetic scale sensing using a moving body detector (magnetic scale) composed of a magnetic sensor using a magnetoresistive effect element (MR element) or the like and a scale material provided with a magnetic pattern is known as an origin detection device of a magnetic encoder. ing.

  In such magnetic scale sensing, it is necessary to detect the origin position in order to determine the position of the magnetic sensor. As a method for detecting the origin, there is conventionally known a method in which a magnetic mark for origin detection is provided in a channel different from that of the scale material and this is detected (see, for example, Patent Document 1). In the conventional origin detection method, since a magnetic mark for origin detection is provided in another channel, it is necessary to provide a magnetic sensor for origin detection separately from the magnetic sensor for scaling.

  Magnetic scale sensing is used, for example, in a mixing console or the like to set parameters corresponding to filter characteristics for setting frequency characteristics of input signals and output signals, and parameters for adjusting input levels and output levels. It is applied to a slide operator (see, for example, Patent Document 2).

  When applying magnetic scale sensing to the slide operator, for example, a magnetic sensor is arranged on the moving block, and the moving block is moved on a moving guide that also serves as a magnetic scale material, thereby detecting the magnetic pattern. Based on the detection result, the position, movement amount, movement direction, and the like of the moving block are determined, and parameters are set according to the determination result.

  Magnetic scale sensing has enabled high-precision detection, and the moving body detector itself has been miniaturized. On the other hand, it is becoming more difficult to manage the gap between the magnetic scaler and the magnetic sensor. As the pitch (interval) between the polarities of the magnetic scaler becomes smaller, the gap between the magnetic sensor and the magnetic scaler that are movably disposed corresponding to the magnetic scaler inevitably becomes narrower.

Japanese Patent Publication No. 6-84893 JP 2006-332074 A

  In the conventional origin detection method, since the origin detection magnetic mark is provided in a separate channel, it is necessary to provide the origin detection magnetic sensor on a separate track from the scaling magnetic sensor. As a result, there is a problem that the apparatus using the moving body detector is increased in size and the cost is increased.

  In general, a moving body detector has a structure in which a magnetic sensor moves with respect to a magnetic scaler because of its structure, and thus requires a clearance (play) for movement. If the clearance is set as small as possible, the slidability is deteriorated. If the clearance is increased, rattling or a missing sensing pulse occurs.

  Therefore, it is necessary to set the magnetic scaler and magnetic sensor with an appropriate clearance, but the gap has become smaller than the predetermined value due to some reasons such as the clearance is not constant within the sliding range due to aging. It may happen that they face each other. In this case, the detection of the origin (the Z phase representing the reference point of the magnetic scale) and the detection of the A and B phases (the signals for reading the pitch magnetically recorded on the scale and signals shifted by 90 degrees from each other) are made common. In Z-phase detection, the magnetic sensors face each other in the saturation region of the sensor sensitivity, and the resolution of the signal ("logical value 0" or "logical value 1") becomes difficult to take. That is, “1” may continue or “0” may continue.

  Considering such cases, in order to perform proper sensing, it is conceivable to increase the gap between the magnetic scaler and the magnetic sensor, or to weaken the magnetic force (magnetization) of the magnetic scaler. There is a drawback that it is vulnerable to disturbance magnetism. In addition, as described above, the gap between the magnetic scaler and the magnetic sensor needs to be reduced as the moving object detector becomes more accurate and smaller. Further, for example, a weakly magnetized magnetic scaler is easily demagnetized against disturbances such as when the magnet approaches the scale material, and is strongly affected by disturbances when the magnets are weakened or turned sideways. Therefore, the magnetic scaler needs to be magnetized in the full range (magnetize so that the area of the hysteresis loop of magnetization reaches the maximum value). Note that if the gap between the magnetic scaler and the magnetic sensor is simply set narrow and the magnetic force of the magnetic scaler is set strong, the magnetic sensors will face each other in the saturation region of the sensor sensitivity, making it difficult to obtain signal resolution. .

  In addition, in a general origin detection method, since a magnetic mark for origin detection is provided in a separate channel, it is necessary to provide a magnetic sensor for origin detection separately from the magnetic sensor for scaling, which increases the size of the moving object detector. As a result, there is a problem that the apparatus using the moving body detector is increased in size and the cost is increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a moving body detector that can share the detection of the origin and the detection of the movement amount and the movement direction. It is another object of the present invention to provide a moving body detector that can perform appropriate sensing stably.

  According to an aspect of the present invention, the moving body detector includes a magnetic scale portion having a magnetic pattern along a predetermined direction, and magnetization stronger than the magnetic pattern applied to one end portion of the magnetic scale portion in the predetermined direction. A strong portion, magnetic field shaping means arranged close to the magnetic scale portion, and arranged to be movable close to and opposed to the magnetic scale portion along the predetermined direction of the magnetic scale portion. Magnetic detection means for detecting a magnetic field of the strong magnetization portion.

  Preferably, the magnetic pattern and the strong magnetization portion are arranged on a movement locus of the magnetic detection means.

  The strong magnetization part is an origin signal generation part.

  In one aspect, the magnetic field shaping means is disposed on a side opposite to the side where the magnetic field detection means is arranged with respect to the magnetic scale unit, and absorbs magnetic flux to shape the magnetic field.

  In another aspect, the magnetic field shaping means is provided along a side of the magnetic scale portion.

  In another aspect, the magnetic field shaping means comprises a permanent magnet.

  In another aspect, the magnetic field shaping means is provided along both sides of the magnetic scale portion, and includes a permanent magnet disposed on one side of the both sides and a high permeability material disposed on the other side.

  In another aspect, the magnetic field shaping means comprises a permanent magnet provided along both sides of the magnetic scale portion.

  In another aspect, the magnetic scale portion and the magnetic field shaping means are formed of a pipe material, the magnetic scale portion is formed in a part of the pipe material having a cross-sectional ring shape, and the magnetic field shaping means is formed in a portion opposite to the magnetic scale portion. Means are formed.

  According to another aspect of the present invention, the moving body detector is stronger than the magnetic pattern provided on a magnetic scale portion having a magnetic pattern along a predetermined direction and one end portion of the magnetic scale portion in the predetermined direction. A magnetic strong portion, and a magnetic detection means that is arranged so as to be movable close to and opposed to the magnetic scale portion along the predetermined direction of the magnetic scale portion, and detects the magnetic pattern and the magnetic field of the strong magnetic portion; And a detection circuit for detecting a magnetic detection signal detected by the magnetic detection means separately into a scale signal and a magnetic strong part signal.

  Preferably, the detection circuit includes first and second comparators to which a magnetic detection signal is input from the magnetic detection unit, and the first comparator has a first comparison level lower than a peak of the scale signal. The second comparator has a second comparison level higher than the peak of the scale signal and lower than the peak of the magnetic strong part signal, the first comparator outputs the scale signal, The second comparator outputs a magnetic strong part signal.

  Further, the detection circuit generates an origin signal representing the origin of the magnetic scale unit based on the magnetic strong part signal separated from the magnetic detection signal.

  The detection circuit is constituted by a digital circuit.

  The magnetic detection means is composed of a magnetoresistive element.

  Further, magnetic field variable means for deforming the pattern magnetic field of the magnetic flux radiated from the magnetic pattern is provided.

  The magnetic field varying means changes the magnetic anisotropy of the scale portion.

  According to one aspect of the present invention, it is not necessary to provide a separate track for detecting the origin, the track width is halved compared to the conventional one, the scale portion is magnetized only once, and a dedicated sensor is provided for detecting the origin. There is an effect that it is not necessary.

  In addition, according to another aspect of the present invention, it is possible to provide a moving body detector capable of performing appropriate sensing stably even when the origin detection and the movement amount detection are shared.

  The present invention positively magnetizes the magnetic scale part to strengthen the magnetic field, while arranging magnetic field shaping means to shape the spatial distribution of the magnetic field and weaken the magnetic flux entering the magnetic detection means, A strong guard field is formed on the side. First, the scale portion is positively magnetized to make it difficult for the magnetic flux generated from the scale portion to be demagnetized. Due to the strong magnetization, it is less susceptible to disturbance magnetic fields. Second, the magnetic field shaping means is arranged to shape the spatial distribution of the magnetic field and weaken the magnetic flux entering the magnetic detection means. If the magnetic flux above the scale portion entering the magnetic detection means remains strong, the magnetic strength will exceed the magnetic saturation level of the magnetic detection means. Therefore, the flow of the magnetic field generated from the magnetic scale unit is changed by the magnetic field shaping means. This weakens the magnetic flux entering the magnetic detection means and prevents saturation of magnetic sensing. Third, a strong guard field is formed by, for example, the side of the scale portion by the magnetic shaping means. Thereby, it becomes difficult to be influenced by the disturbance magnetic field, and stable magnetic sensing can be performed.

  FIG. 1 is a schematic side view showing a basic configuration of a moving object detector (magnetic scale) 1 according to a first embodiment of the present invention. FIG. 1A is a side view in the longitudinal direction of the magnetic scale 1, and FIG. 1B is a side view in the end face direction of the magnetic scale 1.

  The magnetic scale 1 includes a scale material (magnetic scale portion) 11, a magnetic sensor (magnetic detection means) 12, and a magnetic disturbance material (magnetic disturbance means or magnetic malfunction prevention means) 13.

  The scale material 11 is, for example, a rod-like member formed of a permanent magnet such as a rubber magnet formed by mixing ferrite magnet powder and a rubber material or a ferrite magnet made of a metal oxide. Alternatively, the scale material 11 may be formed by, for example, forming a filled magnet material in which the rubber magnet is formed into an elongated shape (for example, a diameter of 1.5 to 5.0 mm) in a groove portion of a stainless rod (for example, a diameter of 4.0 to 8.0 mm). After the filling, a scale material obtained by magnetizing the filled magnet material from the upper part 11a with a predetermined magnetization means may be used. On the scale material 11, magnetic poles are formed at equal intervals by alternately finely polarizing N poles and S poles in the longitudinal direction as a magnetic pattern. The arrangement pitch (scale magnetization pitch) P between the N pole and the S pole is, for example, about 0.1 mm to 2.0 mm. Further, a magnetization strong portion 14 for detecting the origin is provided on one end face of the scale material 11 on the same line (same track) as the scale magnetization. The strong magnetization portion 14 is magnetized to the saturation level, while the magnetic pattern is kept at 70% to 80% of the saturation level.

  The magnetic sensor 12 includes, for example, a plurality of magnetoresistive elements (MR elements), giant magnetoresistive elements (GMR elements), and the like, and changes in the magnetic field in the longitudinal direction of the scale material 11 and the presence or absence (or strength) of a magnetic material. Is detected as a change in voltage. The magnetic sensor 12 is installed to be movable in the longitudinal direction of the scale material 11 so that the sensing surface faces the scale material 11 with a slight clearance (interval). The clearance is set to 0.1 to 0.5 mm, for example.

  The magnetic disturbance material 13 is formed of, for example, a highly permeable material such as Fe or Fe—Ni alloy, and is installed below the scale material 11 over the entire length of the scale material 11. In this way, by placing the magnetic disturbance material 13 formed of a highly permeable material close to the lower surface of the scale material 11, the strength of the magnetic field output from the magnetic poles magnetized on the scale material 11 to the surface space is increased. Thus, the magnetic saturation of the magnetic sensor 12 is eliminated, and the strong magnetization portion 14 provided on the end face of the scale material 11 can be reliably detected.

  In the present invention, the magnetic scale material 11 is positively magnetized to strengthen the magnetic field, while the magnetic field shaping material 13 is arranged to shape the spatial distribution of the magnetic field so that the magnetic field of a predetermined portion (for example, above the scale material) is increased. While weakening, a strong guard field is formed, for example, on the side of the scale material 11.

  First, the scale material 11 is positively magnetized to make it difficult for the magnetic flux generated from the scale material 11 to be demagnetized. The weakly magnetized magnetic scale material 11 is easily demagnetized against disturbances such as when the magnet is approaching, and the magnetic force is weakened, or the magnetic vector is directed sideways, and is strongly influenced by the disturbances. Therefore, it is preferable to increase the magnetization level of the magnetic scale material 11 to strengthen the magnetic field.

  Second, the magnetic field shaper 13 is arranged to shape the spatial distribution of the magnetic field and weaken the magnetic field of a predetermined portion (for example, above the scale material 11). If the magnetic field above the scale material 11 remains strong, the magnetic strength may exceed the magnetic saturation level of the magnetic sensor 12. Therefore, in the present invention, in order to detect the origin, the flow of the magnetic field generated from the magnetic scale material 11 is changed by the magnetic field shaping material 13 (magnetic material, magnet and / or iron plate). This weakens the magnetic flux entering the magnetic sensor 12 and prevents saturation of magnetic sensing.

  Third, a strong guard field is formed, for example, on the side of the scale material 11 by the magnetic shape trimming material 13. Thereby, it becomes difficult to be influenced by the disturbance magnetic field, and stable magnetic sensing can be performed.

  With the above configuration, when the magnetic sensor 12 moves in the longitudinal direction of the scale material 11, the magnetic sensor 12 outputs a pulse signal (scale signal) corresponding to the reversal of the polarity of the N pole and the S pole of the scale material 11. The amount of movement of the magnetic sensor 12 can be detected by counting the scale signal by a control unit (not shown). Further, as will be described later, the magnetic sensor 12 has the magnetic detection units 121 and 122 arranged with a shift corresponding to 1 / 2π, so that the scale signals output from these two magnetic detection units 121 and 122 The moving direction of the magnetic sensor 12 can be determined by the direction opposite to the phase shift. Further, when the magnetic sensor 12 detects the strong magnetization portion 14, an origin forming signal (a signal that is a source of the origin signal and may be used as it is as an origin signal) is output. Based on the detected movement amount, movement direction, and origin signal, the position of the magnetic sensor 12 on the scale material 11 is detected.

  FIG. 2 is a schematic diagram showing the configuration of the main part 123 of the magnetic sensor 12 according to the first embodiment of the present invention and the positional relationship between the magnetic scale material 11. The main part 123 is composed of eight MR elements. For example, the dimension from the left end element 121a1 to the right end element 121a2 is about 3 mm. FIG. 3 is an equivalent circuit diagram of the magnetic detection units 121 and 122 constituting the magnetic sensor 12. FIG. 4 is a graph showing characteristics of individual MR elements 123 constituting the magnetic detection units 121 and 122.

  The magnetic sensor 12 includes two magnetic detection units 121 and 122. The magnetic detection unit 121 includes magnetic detection elements 121a1, 121a2, 121c1, and 121c2 made of MR elements. The magnetic detection elements 121a1 to 121c2 and the scale material 11 are arranged as shown by parts (b) and (c) in FIG. That is, the magnetic detection elements 121a1 to 121c2 are arranged so that each element crosses the longitudinal direction at a right angle so as to oppose the arrangement direction of the magnetic poles NSNS. 2 is a plan view of the magnetic detection element 121 as viewed from above for easy understanding of the configuration of the magnetic detection elements 121a1 to 121c2. The magnetic detection elements 121a1 and 121a2 constitute a resistance MRa in the equivalent circuit diagram of the magnetic detection unit 121, and the magnetic detection elements 121c1 and 121c2 constitute a resistance MRc in the equivalent circuit diagram of the magnetic detection unit 121. The resistance value a1 of the magnetic detection element 121a1 and the resistance value a2 of the magnetic detection element 121a2 have a relationship of a1 = a2, and the resistance value c1 of the magnetic detection element 121c1 and the resistance value c2 of the magnetic detection element 121c2 are c1 = This is the relationship of c2. Further, the sum of the combined resistance (MRa) of the magnetic detection element 121a1 and the magnetic detection element 121a2 and the combined resistance (MRc) of the magnetic detection element 121c1 and the magnetic detection element 121c2 is always constant.

  As shown in FIG. 3, the resistors MRa and MRc are connected in series between the power supply Vcc (A1) and the ground GND (C1) to form a half bridge circuit. An analog signal accompanying the movement of the magnetic sensor 12 on the scale material 11 is output from the midpoint potential B1 of the half bridge circuit.

  The magnetic detection surfaces of the magnetic detection elements 121a1 to 121c2 are arranged such that the longitudinal direction thereof is perpendicular to the longitudinal direction of the scale material 11. Assuming that the scale magnetization pitch of the N pole and S pole of the scale material 11 is P, in the magnetic detection unit 121, the magnetic detection elements 121a1 and 121a2 are arranged with a gap P, and the magnetic detection elements 121a2 and 121c1 are spaced. The magnetic detection elements 121c1 and 121c2 are arranged with a distance P between them.

  Here, the absolute value of the magnetic field strength H in the longitudinal direction of the scale member 11 is maximum between the magnetic poles and is minimum on the magnetic poles. As shown in FIG. 4, when the absolute value of the magnetic field strength H is the minimum, the resistance value of the MR element MR becomes the maximum value, and when the absolute value of the magnetic field strength H is the maximum, The resistance value is the minimum value. For this reason, when the magnetic detection elements 121a1 and 121a2 are positioned between the N-pole and S-pole poles, the resistance value of the resistor MRa is low, and at the same time, the magnetic detection elements 121c1 and 121c2 are positioned on the N-pole and S-pole. Therefore, the resistance value of the resistor MRc is increased. Therefore, in the positional relationship shown in FIG. 2, the output B1 of the magnetic detection unit 121 is “high level (logical value 1)”.

  The magnetic detection unit 122 is configured in the same manner as the magnetic detection unit 121, and includes MR elements 122 a 1, 122 a 2, 122 c 1, 122 c 2. The magnetic detection unit 122 is opposed to the magnetic poles NSNS arranged at equal intervals on the scale material 11 and has a longitudinal direction at a right angle. Each element is arranged so as to cross. The magnetic detectors 121 and 122 are arranged so as to oppose the scale material with a shift of 3/4 pitch with respect to the pitch of the NSNS. This pitch may be shifted by 1/4 or 5/4. That is, in the positional relationship shown in FIG. 2, the resistance value of the resistance MRa of the magnetic detection unit 122 is slightly higher than that of the magnetic detection unit 121, and the resistance value of the resistance MRc is slightly lower than that of the magnetic detection unit 121. . Therefore, the output B2 of the magnetic detection unit 122 becomes “low level (logical value 0)” when the magnetic detection unit 122 is subsequently moved to the right by 1/4 pitch. That is, the magnetic detection units 121 and 122 output an A phase signal and a B phase signal whose phases are shifted by 1 / 4π.

  As described above, the direction and amount of movement of the sensor 12 are obtained by counting the number of pulses from the magnetic sensor 12 by the A-phase and B-phase outputs.

  FIG. 5 is a block diagram showing the configuration of the signal forming circuit 15 according to the first exemplary embodiment of the present invention. FIG. 6 is a graph showing the detection analog signal of the magnetic detection unit 121 input to the signal forming circuit 15, the output scale signal of the signal forming circuit 15, and the origin forming signal (the signal that is the origin of the origin signal).

  The signal forming circuit 15 includes an amplifier 151 for amplifying an analog output signal from the magnetic detection unit 121, a comparator 152A, a comparator 152B, and two types of comparison level output circuits 153A and 153B.

  An analog signal as indicated by a solid line in FIG. 6 is input from the magnetic detection unit 121 to the amplifier 151. The analog signal amplified by the amplifier 151 is input to one input terminal of the comparator 152A and one input terminal of the comparator 152B. The comparator 152A compares the input analog signal with the comparison level A to output a digital signal (scale signal) A shown in FIG. The comparator 152B compares the input analog signal with the comparison level B to output a digital signal (origin forming signal) B shown in FIG. The comparison level A is set as low as possible in consideration of the noise of the magnetic detection unit 121 so that the scale detection by the magnetic detection unit 121 can be reliably detected, and the comparison level B is analog by the detection of the scale magnetization. Set to a value that is greater than or equal to the maximum value of the signal and less than or equal to the value when the origin forming signal is detected. By providing the comparison levels A and B in this way, it is possible to reliably detect the scale magnetization and the magnetization strong portion (origin) that are installed on one track.

  In FIG. 6, a broken line represents an analog output signal from the magnetic detection unit 121 when the magnetic disturbance material 13 is not installed. When the magnetic disturbance material 13 is not installed, the strength of the magnetic field of the scale magnetization reaches the saturation region of the magnetic detection unit 121, and the signal detected by the scale magnetization and the signal detected by the strong magnetization portion have the same amplitude. Thus, the origin cannot be detected. Therefore, in the present embodiment, by installing the magnetic disturbance material 13, the magnetic field of the scale material 11 is weakened to be below the saturation region of the magnetic detection unit 121, and an analog signal as indicated by a solid line is obtained.

  In the process of magnetizing the scale material 11, since it is difficult to accurately magnetize the end portion, an analog signal W1 that appears at the right end of FIG. May be detected. Therefore, since the signal at the end should be ignored, the strong magnetization portion 14 that is the source of the B signal is not at the end of the scale material 11 but from the center of the scale material 11 for one to several memories in the magnetic scale. Be placed.

  With the configuration as described above, according to the first embodiment of the present invention, both the scale signal and the origin forming signal can be obtained by one track / one sensor. In addition, since the magnetic disturbance material 13 is installed, the magnetic field of the scale material 11 is set to be equal to or less than the saturation region of the magnetic detection unit 121. Therefore, the magnetization of the scale material 11 is strengthened and the influence of disturbance magnetism or the like is exerted. And the occurrence of demagnetization can be suppressed.

  FIG. 7 is a plan view showing a modification of the first embodiment of the present invention.

  FIG. 7A is a plan view showing a first modification of the first embodiment of the present invention. In this example, the magnetic disturbance materials 13a and 13b are installed close to both side surfaces of the scale material 11, thereby reducing the strength of the magnetic field output from the magnetic poles magnetized on the scale material 11 to the surface space. In this example, the magnetic disturbance material 13a is formed of a high magnetic permeability material such as Fe or Fe—Ni alloy, for example, as in the first embodiment, and the scale material 11 is formed on one side surface of the scale material 11. It is installed over the entire length in the longitudinal direction. The magnetic disturbance material 13 b is formed of, for example, a permanent magnet, and is installed on the other side surface of the scale material 11 over the entire length in the longitudinal direction of the scale material 11. Here, the upper surface of the scale material 11 and the upper surfaces of the magnetic disturbance materials 13a and 13b are arranged with a gap D therebetween. The interval D is set so that the origin can be reliably detected in consideration of the scale magnetization pitch, the magnetization width, the strength of the magnetic field, and the like. In addition, if the space | interval D is narrowed, the magnetic field of the scale material 11 will become weak and it will become easy to take out an origin formation signal. It becomes difficult to be disturbed by a disturbance magnetic field.

  FIG. 7B is a plan view showing a second modification of the first embodiment of the present invention. In this example, by installing the magnetic disturbance material 13b close to the side surface of the scale material 11, the strength of the magnetic field output from the magnetic poles magnetized on the scale material 11 to the surface space is reduced. In this example, the magnetic disturbance material 13 b is formed of a permanent magnet, for example, and is installed on the other side surface of the scale material 11 over the entire length in the longitudinal direction of the scale material 11. Also in this example, the upper surface of the scale material 11 and the upper surface of the magnetic disturbance material 13b are arranged with an interval D therebetween.

  FIG. 7C is a plan view showing a third modification of the first embodiment of the present invention. In this example, the magnetic disturbance material 13b is installed close to both side surfaces of the scale material 11, thereby reducing the strength of the magnetic field output from the magnetic poles magnetized on the scale material 11 to the surface space. In this example, for example, the magnetic disturbance material 13 b is formed of a permanent magnet, and is installed on both side surfaces of the scale material 11 over the entire length in the longitudinal direction of the scale material 11. Also in this example, the upper surface of the scale material 11 and the upper surface of the magnetic disturbance material 13b are arranged with an interval D therebetween. The pair of permanent magnets 13a and 13b are arranged so that the same poles (S pole and S pole, or N pole and N pole) are opposed to each other with the scale material 11 in between. However, the present invention is not limited to these. The pair of permanent magnets 13a and 13b may be arranged so that different poles (S pole and N pole) face each other with the scale material 11 in between.

  FIG. 7D is a perspective view and a plan view of an end surface showing a fourth modification of the first embodiment of the present invention. In this example, for example, an outer pipe 16 is formed using a magnetic disturbance material 13a made of a highly permeable material such as Fe, Fe-Ni alloy, and a groove is formed on the upper surface of the outer pipe 16, and the groove is formed in the groove. By embedding the scale material 11, the same effects as those of the above-described embodiments can be obtained. In this example, a magnetic disturbance material 13 b made of a permanent magnet is installed on the bottom surface of the outer pipe 16 over the entire length of the scale material 11 in the longitudinal direction. The magnetic disturbance material 13 b is magnetized in a direction perpendicular to / separating from (facing to) the scale material 11 in the longitudinal direction of the scale material 11.

  FIG. 8 is a perspective view showing an outline of the bias magnetic field generator 17 according to the second embodiment of the present invention. In the second embodiment, a bias magnetic field generation unit 17 is added to the configurations of the first embodiment and its modifications. Since the configuration other than the bias magnetic field generator 17 is the same as that of the first embodiment, the description thereof is omitted.

  The bias magnetic field generator 17 is formed of, for example, a rubber magnet, and is disposed on the back surface of the magnetic sensor 12 (main surface opposite to the magnetic detection surface) so as to be rotatable in parallel with the back surface. By rotating the bias magnetic field generation unit 17, it is possible to apply a bias magnetic field in the shape anisotropy direction of the magnetic sensor 12 and perform adjustment to an optimum state (a level at which the origin can be detected).

  In the second embodiment, the magnetic disturbance material 13 in the first embodiment and its modification can be omitted.

  FIG. 9 is a schematic plan view showing the basic configuration of the moving object detector (magnetic scale) 2 according to the third embodiment of the present invention.

  The difference between the third embodiment and the first embodiment is that, instead of the magnetic disturbance material 13 arranged over the entire length of the scale material 11, the magnetic disturbance material 23 made of a permanent magnet is used only in the vicinity of the end of the scale material 11. It is arranged in. Since the other basic configuration is the same as that of the first embodiment, the description thereof is omitted.

  Since the moving body detector (magnetic scale) 2 according to the third embodiment has the magnetic disturbance material 23 disposed only on the end surface of the scale material as described above, a process for extracting the origin forming signal is required. . Therefore, as shown in FIG. 10, an EXOR of the scale signal A and the origin forming signal B is created, and the EXOR signal that is output for the first time when the magnetic sensor 12 moves toward the end face is used as the origin. In the third embodiment, since the magnetic disturbance material 23 is disposed only in the vicinity of the end face of the scale material 11, the magnetic field of the scale material 11 is strong and the scale signal and the origin formation signal between the scale material 11 and other places. It may not be possible to distinguish. However, in the vicinity of the end surface of the scale material 11, the magnetic field of the scale material 11 is weakened due to the influence of the magnetic disturbance material 23, and only the detection signal of the magnetization strong portion 14 provided on the end surface exceeds the comparison level B. In the vicinity of the end, the origin forming signal once disappears, and the origin forming signal appears in the strong magnetization portion 14.

  Further, in the timing chart shown in FIG. 10, when the magnetic sensor 12 moves toward the end face, the origin forming signal is lost and a plurality of scale signals are in a section without the origin forming signal. Next, the signal B when the origin forming signal is detected can be used as a true origin forming signal. The processing in this case will be described in a fourth embodiment described later. In FIG. 10, the right end portion of the A signal corresponds to the analog signal of the right end portion of FIG. 6 and the right end portion of the A signal based on the analog signal. The signal is ignored.

  FIG. 11 is an exploded perspective view of the main part of the slide volume device 3 according to the fourth embodiment of the present invention. The same members as those in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  The slide volume device 3 is attached to a front panel such as a mixer, for example, and controls the volume and the like.

  The slide volume device 3 includes a frame 31 having an opening 31h, a moving body 32 attached to be movable along the longitudinal direction of the opening 31h, movement guides 33 and 34, a motor 36, drive pulleys 36a and 36b, and the like. Consists of.

  The moving body 32 is attached to the movement guides 33 and 34 so as to be slidable in the longitudinal direction of the opening 31h. The movement guide 33 is constituted by a pipe 16 as shown in FIG. 7D, for example, and the magnetic scale material 11 is installed on the upper surface thereof. The movement guide 33 includes a combination of any of the magnetic scale material 11 and the magnetic disturbance material 13 in the first embodiment and the modifications thereof, the second embodiment, and the third embodiment. May be.

  A motor 36 is attached to one side of the frame 31. A drive pulley 36 a is attached to the drive shaft of the motor 36, and a driven pulley 36 b is disposed at the other end of the frame 31. A timing belt (not shown) is wound around the driving pulley 36a and the driven pulley 36b, and the upper portion of the moving body 32 is attached to one position of the timing belt. Thereby, the moving body 32 reciprocates along the longitudinal direction of the opening 31h by forward and reverse rotation of the motor 36.

  The moving body 32 includes a slide operation element 37, the magnetic sensor 12, and a control unit 35. One end of the slide operator 37 is attached to the moving body 32, and the other end protrudes upward from the opening 31h. The magnetic sensor 12 is attached so that the magnetic detection surface faces downward and the magnetic detection surface corresponds to the magnetic scale material 11. The control unit 35 processes the analog output signal from the magnetic sensor 12 and outputs position information of the slide operation element 37.

  When the user operates the slide operator 37, the moving body 32 reciprocates along the longitudinal direction of the opening 31h. With this reciprocal movement, the magnetic sensor 12 moves on the magnetic scale material 11, and the magnetic sensor 12 outputs an analog detection signal corresponding to the movement to the control unit 35. The control unit 35 processes the detection signal and outputs position information of the slide operator 37.

  When the slide volume device 3 is configured as a manual device, the slide volume device 3 is configured without the motor 36, the pulleys 36a and 36b, the belt, and the like.

  FIG. 12 is a block diagram showing functions of the control unit 35 according to the fourth embodiment of the present invention. FIG. 13 is a timing chart showing signal processing in the control unit 35 according to the fourth embodiment of the present invention. In this example, a case will be described in which the third embodiment is used as the moving body detector of the fourth embodiment. The same members as those in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  The control unit 35 includes a signal forming circuit 15, an EXOR circuit 51, an AND circuit 52, an RS flip-flop circuit 53, a D flip-flop circuit (DFF) 54, a differentiation circuit (one-shot OS) 55, and an up / down counter 56 shown in FIG. The waveform shaping means (amplifier and waveform shaping circuit) 57 is included.

  The analog detection signal input from the magnetic detection unit 121 is output as the scale signal A and the origin formation signal B by the signal forming circuit 15 (see FIG. 5). The scale signal A is input to the CK terminal of the up / down counter 56 and also input to the D terminals of the EXOR circuit 51 and the D flip-flop circuit 54. The origin forming signal B is input to the other input terminal of the EXOR circuit 51 and the R terminal of the RS flip-flop circuit 53.

  The analog detection signal input from the magnetic detection unit 122 is input to the clock input terminal CK of the D flip-flop circuit 54 via the waveform shaping unit 57. Since the DFF 54 inputs the A phase signal A (scale signal A) shown in FIG. 13 from the A terminal of the signal forming circuit 15 to the D input terminal, the input clock (the b signal as the B phase signal, or FIG. ) B2 output signal and the D input data “1” at the rising edge of the waveform b ′ in FIG. 13 are taken in, and an R (2Q) output is obtained as a 2Q output. R (2Q) is an R (right) direction signal obtained from 2Q when the sensor 12 of FIG. 11, FIG. 1 or FIG. 7 is moved to the right. L (2Q) in FIGS. 13 and 14 is an L (left) direction signal obtained from 2Q when the sensor 12 is moved to the left. 13 and 14, the horizontal axis represents the time axis or position information. The U / D counter 56 is set to the up-count state by the R direction signal 2Q “1”. At this time, the AND circuit 52 sets the flip-flop circuit 53 by ANDing the 2Q = “1” input and the EXOR output input. Since the EXOR output generates two (or two or more) pulses only when the sensor 12 comes to the right end, the flip-flop circuit 53 causes Q = “1”, / Q (hereinafter, / Q indicates Q inverse) = “0”, and / Q = “1” at timing t1 when the B output (B signal) of the signal forming circuit 15 rises to “1”. This is reset in the counter 56 by a differentiation circuit (one-shot OS) 55. That is, the zero point adjustment of the detector 1 is performed by this reset.

  When the moving body 32 (sensor 12) moved to the right end is moved to the left from the position Pr indicated by the timing t1, the EXOR output generates two pulses at the same position as in FIG. , L (2Q) (indicated by time), since 2Q = “0” is output, the flip-flop circuit 53 is not set. Therefore, it remains reset, the OS output is “0”, and the counter 56 is not reset. That is, the U / D counter 56 is reset only when it is moved from the left to the right end and reaches the right end. Therefore, it is reset only when the slide operation element 37 moves in the direction of the origin and reaches the origin. As shown in the figure, the reset signal (origin signal) is output at the same timing t1 as the rise of the origin formation signal.

  The output OUT of the counter 56 is used as an accurate position of the moving body 32 (see FIG. 11) in a use circuit or means in a subsequent stage (not shown). For example, it is used as movement control position information of a fader device of a mixer or an electronic musical instrument, and its control target is used for setting an acoustic level, a PAN control level, effect control, tone color modulation control, or the like. Furthermore, it can be used for other industrial products such as printers.

  In the present embodiment, when there are at least two EXOR signals (signals that are origin signals), the signals that are used as origin signals are temporary, such as when a strong magnet approaches. This is to ensure accuracy when a strong disturbance magnetic field is generated by generating a strong disturbance magnetic field for some reason. When a strong disturbance magnetic field approaches temporarily, a magnetic field from the magnetic scale is found, and the B signal may not be detected (an EXOR signal is generated) even though it is not near the origin. In order to prevent such erroneous detection of the origin, accuracy is ensured by using it as an origin formation signal only when there are at least two EXOR signals (source signals of origin signals).

  From this point of view, when a home return signal (EXOR output) due to a disturbance is output at an intermediate position other than the origin in the solid line portion in FIG. 12, a malfunction occurs in which the disturbance is regarded as the origin at the position where the disturbance is removed (B Signal generation). In order to avoid this, a retriggerable counter 58 may be provided between the AND circuit 52 and the RS flip-flop circuit 53, and this counter 58 may be additionally inserted and installed as shown by a one-dot chain line in FIG.

  The counter 58 is counted up by the output of the AND circuit 52, and has a function of returning the counter value to zero unless the count is continuously counted up within a predetermined time, for example, 0.1 seconds. For example, only when 1 becomes 2 or more, “1” is output and the flip-flop circuit 53 is set.

  With this configuration, the magnetic disturbance means 13 functions as a magnetic malfunction prevention means (means that are hard to cause a magnetic malfunction), and even if a disturbance occurs, a one-dot chain line reinforcing means (counter 58) is added. Therefore, there is an effect of repelling the disturbance (not affected by the disturbance). In this case, in order to reset the detector according to the embodiment of the present invention by the origin signal, it is necessary to perform a fast end contact operation in consideration of the above-described conditions. This is because the counter 56 cannot be reset because the reset state after the setting of the RS flip-flop circuit 53 cannot be obtained by the overflow output of the counter 58 if the end contact operation is performed slowly.

  In addition, in this example, the case where the thing of the 3rd Example was used as a moving body detector of the 4th Example was demonstrated, However, The movement of 1st Example, its modification, and 2nd Example The body detector can also be used as the moving body detector of the fourth embodiment. In this case, the timing chart is as shown in FIG. 14, but as a result, a reset signal (origin signal) can be output at the origin formation signal detection timing (right end position) t1. Further, when the moving body detector of the first embodiment and its modified examples and the second embodiment is used as the moving body detector of the fourth embodiment, the EXOR circuit 51, the AND circuit 52 of the control unit 35, The RS flip-flop circuit 53 may be omitted and the origin formation signal B may be directly input to the differentiation circuit (one-shot OS) 55.

  Although not shown in FIG. 13 and FIG. 14, the analog signal at the right end portion of FIG. 6 and the A signal corresponding to the right end portion of the A signal based on the analog signal appear at the right end portion of FIG. This signal is ignored because it is an inaccurate magnetized portion at the end portion of the scale material 11.

  As described above, according to each embodiment of the present invention, the scale magnetic pattern for detecting the scale signal and the magnetization strong portion for detecting the origin signal are arranged on the same line. This arrangement may be the same track arrangement, and the line may be a curve, and may be arranged on a continuous line. This greatly simplifies the configuration of the moving object detector. By adopting such a configuration, it is not necessary to separately prepare a magnetic sensor for detecting a scale signal and a magnetic sensor for detecting an origin signal, and it becomes unnecessary to align two different sensors, thereby improving accuracy.

  In addition, according to the embodiment of the present invention, the magnetic disturbance material is installed close to the scale material, thereby reducing the strength of the magnetic field output from the magnetic poles magnetized to the scale material to the surface space. The magnetic saturation of the sensor can be eliminated. This also makes it possible to reliably detect the strong magnetization portion provided on the end face of the scale material, distinguishing it from the scale magnetic pattern for detecting the scale signal.

  Furthermore, by installing the magnetic disturbance material close to the scale material, the strength of the magnetic field output from the magnetic poles magnetized on the scale material to the surface space can be reduced. Can be maximized and stable scale sensing can be performed.

  In the above-described embodiment, only the example in which the moving body detector according to each embodiment of the present invention is applied to the slide volume device has been described. However, the moving body detector according to each embodiment of the present invention includes a vehicle suspension, The present invention can also be applied to a position detection sensor of a printer.

  In the above-described embodiment, only the linear scale has been described, but the embodiment of the present invention can also be applied to a rotary encoder or the like.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is a schematic side view showing the basic composition of the mobile detector (magnetic scale) 1 by the 1st example of the present invention. FIG. 3 is a schematic view showing the configuration of the main part of the magnetic sensor 12 according to the first embodiment of the present invention and the positional relationship between the magnetic scale material 11. 2 is an equivalent circuit diagram of magnetic detection units 121 and 122 constituting the magnetic sensor 12. FIG. 5 is a graph showing characteristics of MR elements 123 constituting magnetic detection units 121 and 122. 1 is a block diagram showing a configuration of a signal forming circuit 15 according to a first exemplary embodiment of the present invention. 5 is a graph showing a detection analog signal of the magnetic detection unit 121 input to the signal forming circuit 15, an output scale signal of the signal forming circuit 15, and an origin forming signal. It is a top view showing the modification of the 1st Example of this invention. It is a perspective view showing the outline | summary of the bias magnetic field generation part 17 by the 2nd Example of this invention. It is a schematic plan view showing the basic composition of the mobile body detector (magnetic scale) 2 by the 3rd Example of the present invention. It is a timing chart for demonstrating the detection of the origin signal by the 3rd Example of this invention. It is a principal part disassembled perspective view of the slide volume apparatus 3 by the 4th Example of this invention. It is a block diagram showing the function of the control part 35 by the 4th Example of this invention. It is a timing chart showing the signal processing in the control part 35 by the 4th Example of this invention. It is a timing chart showing the signal processing in the control part 35 by the 4th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Moving body detector (magnetic scale), 3 ... Slide volume apparatus, 11 ... Scale material (magnetic scale part), 12 ... Magnetic sensor (magnetic detection means), 13 ... Magnetic disturbance material (magnetic disturbance means; Magnetic) 14 ... Magnetization strong part, 15 ... Signal forming circuit, 16 ... Outer pipe, 17 ... Bias magnetic field generation part, 31 ... Frame, 32 ... Moving body, 33, 34 ... Movement guide, 35 ... Control part 36 ... Motor, 36a, 36b ... Drive pulley, 37 ... Sliding operator, 51 ... EXOR circuit, 52 ... AND circuit, 53, 54 ... Flip-flop circuit, 55 ... Differentiation circuit (one-shot OS), 56 ... Up-down Counter, 58... Retriggerable counter, 121, 122, Magnetic detection unit, 123, MR sensor main part, 151, Amplifier, 152, Comparator, 15 ... comparison level output circuit

Claims (16)

A magnetic scale portion having a magnetic pattern along a predetermined direction;
A magnetic strong portion stronger than the magnetic pattern applied to one end of the magnetic scale portion in the predetermined direction;
Magnetic field shaping means arranged close to the magnetic scale portion;
A movable body detection comprising: a magnetic detection unit configured to be able to move close to and opposite to the magnetic scale unit along the predetermined direction of the magnetic scale unit, and to detect the magnetic pattern and the magnetic field of the strong magnetization unit. vessel. The moving body detector according to claim 1, wherein the magnetic pattern and the strong magnetization portion are arranged on a movement locus of the magnetic detection means. The moving body detector according to claim 1, wherein the magnetization strong part is an origin signal generation part. The magnetic field shaping means is disposed on a side opposite to the side where the magnetic field detection means is arranged with respect to the magnetic scale unit, and absorbs magnetic flux to shape the magnetic field. The moving body detector according to any one of the above. The said magnetic field shaping means is provided along the side of the said magnetic scale part, The moving body detector of any one of Claims 1-3 characterized by the above-mentioned. The moving body detector according to claim 1, wherein the magnetic field shaping means is made of a permanent magnet. The magnetic field shaping means is provided along both sides of the magnetic scale portion, and includes a permanent magnet disposed on one side of the both sides and a high permeability material disposed on the other side. The moving body detector of any one of 1-3. The said magnetic field shaping means consists of a permanent magnet provided along the both sides of the said magnetic scale part, The moving body detector of any one of Claims 1-3 characterized by the above-mentioned. The magnetic scale portion and the magnetic field shaping means are formed of a pipe material, the magnetic scale portion is formed in a part of the pipe material having a ring-shaped cross section, and the magnetic field shaping means is formed in a portion opposite to the magnetic scale portion. The moving body detector according to any one of claims 1 to 3, wherein the moving body detector is provided. A magnetic scale portion having a magnetic pattern along a predetermined direction;
A magnetic strong portion stronger than the magnetic pattern applied to one end of the magnetic scale portion in the predetermined direction;
A magnetic detecting means for detecting a magnetic field of the magnetic pattern and the strong magnetic part, wherein the magnetic scale part is arranged movably close to and opposite to the magnetic scale part along the predetermined direction;
A moving body detector comprising a detection circuit for detecting a magnetic detection signal detected by the magnetic detection means separately into a scale signal and a magnetic strong part signal. The detection circuit includes first and second comparators to which a magnetic detection signal is input from the magnetic detection unit,
The first comparator has a first comparison level lower than a peak of the scale signal;
The second comparator has a second comparison level higher than the peak of the scale signal and lower than the peak of the magnetic strong part signal;
11. The moving body detector according to claim 10, wherein the first comparator outputs the scale signal, and the second comparator outputs a magnetic strong part signal. The moving body detector according to claim 10 or 11, wherein the detection circuit generates an origin signal representing an origin of the magnetic scale unit based on the magnetic strong part signal separated from the magnetic detection signal. The moving body detector according to any one of claims 10 to 12, wherein the detection circuit is configured by a digital circuit. The moving body detector according to claim 1, wherein the magnetic detection unit includes a magnetoresistive effect element. The moving body detector according to any one of claims 1 to 14, further comprising magnetic field variable means for deforming a pattern magnetic field of magnetic flux radiated from the magnetic pattern. 16. The moving body detector according to claim 15, wherein the magnetic field varying means changes the magnetic anisotropy of the scale portion.

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