JP2015219180A - Absolute position detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absolute position detection device capable of outputting data indicating the absolute position of a mobile entity without newly installing a magnetic scale or a detector.SOLUTION: The absolute position detection device comprises: a magnetic scale 7 in which a magnetic pattern is recorded that has, in a linearly moving or rotating mobile entity, an n-bit non-repetitive serial code combined to occur only once over the entire length; a detector group 2 for detecting the magnetic pattern, in which at least four sets or more of detectors, one set consisting of n detectors, are arranged facing the magnetic scale at 1-pitch intervals of the magnetic pattern; a comparator group 3 for comparing each of detection signals from a group of two sets of detectors among the group of four or more sets of detectors; a switch unit 4 for selecting one set of detection signals from among the group of four or more sets of detectors on the basis of the comparison result and outputting it as an n-bit serial code; and a conversion unit 5 for converting the n-bit serial code into absolute position information indicating the absolute position of the mobile entity and outputting the converted data.

Description

  The present invention relates to an apparatus for detecting an absolute position and an absolute angle of a linear or rotationally moving object.

  2. Description of the Related Art Conventionally, there is known an absolute position detection device that forms a pattern so that a combination code of the same bit is not generated on a moving body that moves linearly or rotates, and detects the absolute position by reading the pattern. For example, Patent Document 1 discloses an absolute position detection in which an absolute position is detected based on signals having different levels obtained from light receiving elements by using an absolute pattern 13 of a code disc 12 between four light sources and the light receiving elements. An apparatus is disclosed.

  However, in the absolute position detection apparatus of Patent Document 1, when the light source and the light receiving element are in the vicinity of the boundary between the transparent area and the opaque area of the absolute pattern 13 and the absolute position detection is started, Since each light receiving element detects which area is unstable, there is a problem in that an erroneous detection code is output. In order to solve such a problem, for example, in Patent Document 2, the output of the detector group near the boundary of the magnetic pattern is switched by switching between two sets of detector groups provided for each pitch of the magnetic scale. An absolute value type magnetic scale device in which no is selected is disclosed.

JP-A-1-152314 Japanese Patent No. 2571394

  However, in the absolute value type magnetic scale device of Patent Document 2, in order to generate timing for switching the outputs of the two sets of detector groups, a magnetic scale on which a magnetic pattern is formed and a detector for detecting the magnetic pattern. There was a problem that it was necessary to provide a new one.

  An object of the present invention is to provide an absolute position detection device capable of solving the above problems and outputting data indicating the absolute position of a moving body without newly providing a magnetic scale and a detector. .

The absolute position detection device according to the present invention is:
An absolute position detection device that forms a magnetic pattern indicating a non-repetitive serial code of a natural number n bits on a moving body that moves linearly or rotates, and outputs data indicating the absolute position of the moving body based on the formed magnetic pattern Because
A magnetic scale on which the magnetic pattern having the n-bit non-repetitive serial code combined so as to occur only once over the entire length of the magnetic scale;
A set of n detectors arranged opposite to the magnetic scale within one pitch interval of the magnetic pattern as a set, at least four sets of detectors for detecting the magnetic pattern; and
A comparator group for comparing detection outputs from two detector groups of the four or more detector groups;
Based on the comparison results, the detection signals from one set of the detector groups are selected from the four or more sets of detector groups, and the selected detection signals are output as an n-bit serial code. A switching unit;
And a conversion unit that converts the n-bit serial code into absolute position information indicating the absolute position of the moving body and outputs the absolute position information.

  According to the absolute position detection device of the present invention, data indicating the absolute position of the moving body is generated and output based on a detection signal from a detector group that is not near the boundary of the magnetic pattern. It is possible to output data indicating the absolute position of the moving body without newly providing.

It is a block diagram which shows the component of the absolute position detection apparatus 1 which concerns on Embodiment 1 of this invention. It is a block diagram which shows the component of the comparator 3a of FIG. It is a block diagram which shows the component of the detector Aa of FIG. FIG. 2 is a non-repetitive code array diagram of a magnetic track 70 in FIG. 1. It is an operation | movement timing diagram of the absolute position detection apparatus 1 of FIG. It is an example of the table stored in the table memory 5m of FIG. It is the schematic for demonstrating operation | movement of the selector 4 of FIG. (A) is a perspective view of the magnetized rotor 10a which concerns on the modification of the magnetic scale 7 of the absolute position detection apparatus 1 of FIG. 1, (b) is the schematic which shows the magnetic pattern of the magnetic track 70a of (a). is there. It is a perspective view of the magnetized rotor 10b which concerns on another modification of the magnetic scale 7 of the absolute position detection apparatus 1 of FIG. It is a block diagram which shows the component of 1 A of absolute position detection apparatuses which concern on Embodiment 2 of this invention. FIG. 10 is a block diagram illustrating components of the comparator group 3 in FIG. 9. It is a block diagram which shows the component of the comparator 3c of FIG. FIG. 10 is an operation timing chart of the absolute position detection device 1A of FIG. It is an example of the table stored in the table memory 5ma of FIG. It is the schematic for demonstrating operation | movement of the selector 4a of FIG.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following embodiments, the same components are denoted by the same reference numerals, and description thereof is omitted.

Embodiment 1 FIG.
The absolute position detection device 1 according to the present embodiment forms a magnetic pattern indicating a 4-bit non-repetitive serial code on a moving body that moves linearly or rotates, and based on the formed magnetic pattern, the absolute position of the moving body is determined. Data indicating the position is generated and output. This will be briefly described below.

  FIG. 1 is a block diagram showing components of an absolute position detection apparatus 1 according to Embodiment 1 of the present invention. In FIG. 1, an absolute position detector 1 includes a magnetic scale 7 recorded on the S pole or N pole of each magnetic track 70, a detector group 2 composed of detector groups A to D, and a comparator. A comparator group 3 composed of 3a and a comparator 3b, a selector 4 which is a switching unit for switching to output a detection signal from one detector group among the detector groups A to D, and the output In addition, a data conversion unit 5 that is a conversion unit that converts a 4-bit non-repetitive serial code into absolute position information that indicates the absolute position of the moving object, and division position information that indicates a position within a 1-bit length pitch P is generated. An encoder 6 serving as a division position information generation unit is provided. Here, each of the detector groups A to D is composed of four detectors arranged to face the magnetic scale 7 with a pitch P of 1 bit length. The detector group A is composed of detectors Aa to Ad, the detector group B is composed of detectors Ba to Bd, the detector group C is composed of detectors Ca to Cd, and the detector group D is a detector. The units Da to Dd. The detectors Aa to Dd are arranged so that the distance between the detectors is P / 4. Here, each of the detector groups A to D detects a magnetic pattern indicating a 4-bit non-repetitive serial code.

  In FIG. 1, 4-bit non-repetitive serial codes are combined on each magnetic track 70 so as to be generated only once over the entire length of the magnetic scale 7 and recorded as a non-repetitive magnetic pattern.

  The comparator 3a compares the detection signal SA from the detector group A with the detection signal SC from the detector group C, and outputs the comparison result CMP1 to the selector 4 and the encoder 6. The comparator 3b compares the detection signal SB from the detector group B with the detection signal SD from the detector group D, and outputs the comparison result CMP2 to the selector 4 and the encoder 6. That is, the comparator group 3 compares detection signals from two detector groups among the four detector groups A to D, respectively.

  The selector 4 selects a detection signal from one detector group from the four detector groups A to D based on the comparison results CMP1 and CMP2 from the comparator 3a and the comparator 3b. The detected signal is output to the data converter 5 as a 4-bit serial code S1.

  Based on the table stored in the table memory 5m, the data conversion unit 5 converts the 4-bit serial code S1 output from the selector 4 into absolute position information S2 indicating the absolute position of the moving object and outputs the converted information.

  Based on the comparison results CMP1 and CMP2 from the comparators 3a and 3b, the encoder 6 generates and outputs divided position information S3 indicating a position obtained by further dividing the 1-bit length pitch P into four.

  FIG. 2 is a block diagram showing components of the comparator 3a of FIG. In FIG. 2, the comparator 3 a includes exclusive OR circuits 31 to 34 respectively connected to an output terminal from the detector group A and an output terminal from the detector group C, and the exclusive OR circuits 31 to 34. 34 and an AND circuit 30 connected to each other via an inverter circuit. Here, the comparator 3a compares the respective bits (the detection signal SAa and the detection signal SCa, the detection signal SAb and the detection signal SCb, the detection signal SAc and the detection signal SCc, and the detection signal SAd and the detection signal SCd). If they are the same, “1” is output. The comparator 3b in FIG. 1 has the same configuration as the comparator 3a in FIG.

  In FIG. 2, an exclusive OR circuit 31 takes an exclusive OR of the detection signal SAa from the detector group A and the detection signal SCa from the detector group C, and outputs an AND circuit 30 via an inverter circuit. Output to. The exclusive OR circuit 32 takes the exclusive OR of the detection signal SAb from the detector group A and the detection signal SCb from the detector group C and outputs the result to the AND circuit 30 via the inverter circuit. The exclusive OR circuit 33 takes the exclusive OR of the detection signal SAc from the detector group A and the detection signal SCc from the detector group C and outputs the result to the AND circuit 30 via the inverter circuit. The exclusive OR circuit 34 takes an exclusive OR of the detection signal SAd from the detector group A and the detection signal SCd from the detector group C, and outputs the result to the AND circuit 30 via the inverter circuit.

  The AND circuit 30 outputs a logical product of signals obtained by inverting the output signals from the exclusive OR circuits 31 to 34 to the selector 4 and the encoder 6 as selection signals.

  FIG. 3 is a block diagram showing components of the detector Aa of FIG. In FIG. 3, the detector Aa includes a fixed resistor R1, a magnetoresistive effect device R2, and a comparator 20 having a threshold voltage Vth. Here, one end of the fixed resistor R1 is connected to the power supply VDD, and the other end of the fixed resistor R1 is connected to one end of the magnetoresistive effect device R2 and to the plus terminal of the comparator 20. The other end of the magnetoresistive effect device R2 is grounded. Here, for the detector Aa, for example, when the detector Aa is opposed to the S pole using a magnetoresistive effect device whose resistance value varies depending on the magnetic field, such as GMR (Giant Magneto Resistance) and TMR (Tunnel Magneto Resistance), The resistance value of the magnetoresistive effect device R2 decreases, and the midpoint voltage at the connection point between the fixed resistor R1 and the magnetoresistive effect device R2 decreases. On the contrary, when the detector Aa faces the N pole, the resistance value of the magnetoresistive device R2 increases, and the midpoint voltage at the connection point between the fixed resistor R1 and the magnetoresistive device R2 increases.

  In FIG. 3, the detector Aa compares the midpoint voltage with a predetermined threshold voltage Vth, and outputs “1” when the comparison result is equal to or higher than the threshold voltage Vth. Is less than the threshold voltage Vth, "0" is output. That is, the detector Aa outputs “0” when the detector Aa faces the south pole, and outputs “1” when the detector Aa faces the north pole. The configurations and operations of the detectors Ab to Ad, Ba to Bd, Ca to Cd, and Da to Dd are the same as those of the detector Aa.

  The operation of the absolute position detection apparatus 1 configured as described above will be described below.

  FIG. 4 is a non-repeated code array diagram of the magnetic track 70 of FIG. In FIG. 4, a 19-bit long magnetic pattern is illustrated, and the magnetic pattern is detected by the detector group A arranged to face the magnetic track 70. Each of the detectors Aa to Ad constituting the detector group A outputs “0” when facing the S pole and “1” when facing the N pole. Since the detectors Aa to Ad are arranged at a pitch P of 1 bit length, the magnetic scale 7 having the magnetic track 70 on which the magnetic pattern of FIG. 4 is recorded has a pitch P of 1 bit length in the direction of the arrow in the figure. When moved, the 4-bit serial code detected by each detector group changes from “0000” (= 0h) to “1000” (= 8h). That is, when the magnetic scale 7 is moved by a 1-bit length pitch P in the direction of the arrow in the figure, the 4-bit serial code detected by each detector group is changed from “0000” (= 0h) to “0001” (= 1h). Further, when the sheet moves by a pitch P of 1 bit length in the direction of the arrow in the figure, it changes from “0001” (= 1h) to “0010” (= 2h). Next, when the magnetic scale 7 changes by a pitch P of 1 bit length in the direction of the arrow in the figure, “0100” (= 4h), “1001” (= 9h), “0011” (= 3h), “0110” (= 6h), “1101” (= Dh), “1010” (= Ah), “0101” (= 5h), “1011” (= Bh), “0111” (= 7h), “1111” (= Fh) “1110”, (= Eh) “1100”, (= Ch) “1000” (= 8 h) are sequentially changed. Accordingly, since the 4-bit serial codes detected by each detector group are all different, it is possible to specify which magnetic track 70 each detector group faces, so that data indicating the absolute position of the moving body is output. Is possible. The 4-bit serial code is converted into the above-described hexadecimal number and processed by a computer.

  FIG. 5A is an operation timing chart of the absolute position detection device 1 of FIG. In FIG. 5A, the magnetic scale 7 and the detector group 2 are used to output data indicating the absolute position of the moving body. A magnetic pattern having a 4-bit serial code is detected by four detectors Aa to Ad arranged at a pitch P of 1 bit length, and similarly a total of four sets of detectors Ba to Bd, Ca to Cd, Da Each of .about.Dd detects a magnetic pattern having a 4-bit serial code. Each of the detectors Aa to Ad, Ba to Bd, Ca to Cd, and Da to Dd outputs “0” when facing the S pole and “1” when facing the N pole. Here, the detection signals SAa to SAd, SBa to SBd, SBa to SBd, SCa to SCd from the detectors Aa to Ad, Ba to Bd, Ca to Cd, Da to Dd when the magnetic scale 7 moves in the direction of the arrow, A timing chart of SDa to SDd is shown. In addition, timing charts of detection signals SA to SD, which are 4-bit serial codes output from the detector groups A to D when the magnetic scale 7 moves in the direction of the arrow, are illustrated. For example, when each detector is at the boundary of the magnetic pattern, it is unstable which of the four detectors Aa to Ad outputs which detection result, so that when each detector Aa to Ad detects a different pattern Would output an incorrect detection result. Therefore, in the first embodiment, one set of detector groups A to D that are not near the boundary of the magnetic pattern is selected from the four sets of detectors Aa to Ad, Ba to Bd, Ca to Cd, and Da to Dd. By selecting and outputting, the wrong detection result is not output. In FIG. 5A, it can be understood that the shaded portions of the waveforms of the detector groups A, B, and C are portions selected by the selector 4 and are not near the boundary of the detection results.

  In FIG. 5A, the data conversion unit 5 outputs “0” as the absolute position information S2 when a 4-bit serial code “0000” is input in accordance with the table stored in the table memory 5m shown in FIG. 5B. When the serial code “0001” is input, “1” is output as the absolute position information S2, and when the 4-bit serial code “0010” is input, “2” is output as the absolute position information S2. That is, as the magnetic scale 7 moves, the count value is counted up from 0 to 16 and this count value is output as absolute position information S2 indicating the absolute position of the moving body. Further, if both the comparators 3a and 3b output “0”, the encoder 6 generates and outputs “0” as the division position information S3, the comparator 3a outputs “1”, and the comparator 3b outputs “0”. If “0” is output, “1” is generated and output as the division position information S3. If both the comparators 3a and 3b output “1”, “2” is generated and output as the division position information S3. If the comparator 3a outputs "0" and the comparator 3b outputs "1", "3" is generated and output as the division position information S3. Here, the encoder 6 outputs division position information with resolution obtained by further dividing the 1-bit length pitch P into four.

  FIG. 6 is a schematic diagram for explaining the operation of the selector 4 of FIG. 6A to 6D show various positional relationships between the magnetic track 70 and the detector group 2. Here, when the detection results of the detector group A and the detector group C are the same and the detection results of the detector group B and the detector group D are also the same, the comparators 3a and 3b both output "1". To do. Therefore, since all the detection results of the detector group A to the detector group D are the same, the boundary of the magnetic pattern is between the detector group D and the detector group A as shown in FIG. It can be judged. In this case, since the detector group A and the detector group D are near the boundary of the magnetic pattern, the selector 4 selects the detector group B or the detector group C (detector group B in this embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern.

  When the detection results of the detector group A and the detector group C are the same, but the detection results of the detector group B and the detector group D are different, the comparator 3a outputs “1”, and the comparator 3b Outputs “0”. Accordingly, the detection results from the detector group A to the detector group C are the same, and only the detection results of the detector group D are different. Therefore, the boundary of the magnetic pattern is as shown in FIG. 6B. It can be determined that it is between C and the detector group D. In this case, since the detector group C and the detector group D are near the boundary of the magnetic pattern, the selector 4 selects the detector group A or the detector group B (detector group B in the present embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern.

  When the detection results of the detector group A and the detector group C are different from each other, and the detection results of the detector group B and the detector group D are also different from each other, the comparators 3a and 3b both output “0” and are detected. The detection results of instrument groups A and B and C and D are the same. Therefore, it can be determined that the boundary of the magnetic pattern is between the detector group B and the detector group C as shown in FIG. In this case, since the detector group B and the detector group C are near the boundary of the magnetic pattern, the selector 4 selects the detector group A or the detector group D (detector group A in the present embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern.

  If the detection results of the detector group A and the detector group C are different, but the detection results of the detector group B and the detector group D are the same, the comparator 3a outputs “0”, and the comparator 3b Outputs “1”, the detection results of detector group B to detector group D are the same, and only detector group A is different. Therefore, it can be determined that the boundary of the magnetic pattern is between the detector group A and the detector group B as shown in FIG. In this case, since the detector group A and the detector group B are near the boundary of the magnetic pattern, the selector 4 selects the detector group C or the detector group D (detector group C in the present embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern. The description of these operations is shown in FIG. 5A, and it can be understood that the hatched portions of the waveforms of the detector groups A, B, and C are portions selected by the selector 4 and are not near the detection result boundaries. .

  According to the absolute position detection device 1 according to the above embodiment, a detector group that is not near the boundary of the magnetic pattern is selected, and the absolute position of the moving body is based on the detection signal from the selected detector group. Therefore, it is possible to output data indicating the absolute position of the moving body without newly providing a magnetic scale and a detector. Further, since it is possible to generate and output division position information obtained by dividing the 1-bit length pitch P into four, output data indicating the absolute position of the moving object with a resolution obtained by dividing the 1-bit length pitch P into four. Is possible.

  In the present embodiment described above, as shown in FIG. 6, the data converter 5 converts the output result of the selector 4 so as to increment one by one as the magnetic scale 7 moves, and the encoder 6 Although the codes 0 to 3 are converted based on the comparison results CMP1 and CMP2 from the comparators 3a and 3b, the present invention is not limited to this. For example, the output result of the selector 4 is converted so as to be incremented by a pitch P of 1 bit length, the encoder 6 is converted into a code incremented by ¼ of the 1 bit length, and each is added to the actual result. The movement distance may be output. Even in this case, the same effect as in the first embodiment can be obtained.

  Moreover, in this Embodiment mentioned above, although the magnetic scale 7 was moved with respect to the fixed detector group 2, this invention is not restricted to this. For example, the magnetic scale 7 may be fixed, and the detector group 2 arranged to face the fixed magnetic scale may be moved. Even in this case, the same effect as in the first embodiment can be obtained.

  In the above-described embodiment, the magnetic track 70 is recorded in a linear shape on the magnetic scale 7, but the present invention is not limited to this. For example, as shown in FIGS. 7A and 7B, a magnetic track 70a may be recorded on the upper surface or the lower surface of the cylindrical magnetized rotor 10a. Alternatively, as shown in FIG. The magnetic track 70b may be recorded on the side surface of the magnetized rotor 10b. In these cases, the detector group 2 is opposed to the magnetic tracks 70a and 70b recorded on any one of the upper surface, the lower surface, and the side surfaces of the magnetized rotors 10a and 10b, and the rotating shaft 14 is the center. When the magnetized rotors 10a and 10b are rotated, the absolute position, that is, the absolute angle of the magnetized rotors 10a and 10b can be detected by the detector group 2. Even in this case, the same effect as in the first embodiment can be obtained.

Embodiment 2. FIG.
In the first embodiment described above, four detectors in which a non-repetitive magnetic pattern in which a 4-bit combination serial code is recorded on the magnetic track 70 are arranged at a pitch P having a 1-bit length are included in a set of detector groups. The non-repetitive magnetic pattern was detected using only four sets of the detector group. On the other hand, in the present embodiment, a set of six detectors in which a non-repetitive magnetic pattern in which a 6-bit combination serial code is recorded on the magnetic track 70 is arranged with a pitch P having a 1-bit length is provided. A non-repetitive magnetic pattern is detected by using only eight sets of the detector groups as the detector group.

  FIG. 9 is a block diagram showing components of the absolute position detection device 1A according to the second embodiment of the present invention. In FIG. 9, the absolute position detection device 1 </ b> A includes a detector group 2 a instead of the detector group 2 and a selector 4 a instead of the selector 4 as compared with the absolute position detection device 1 of FIG. 1. And

  In FIG. 9, each of the detector groups A to H is composed of six detectors arranged to face the magnetic scale 7 within one pitch interval of the magnetic pattern. The detector group A is composed of detectors Aa to Af, the detector group B is composed of detectors Ba to Bf, the detector group C is composed of detectors Ca to Cf, and the detector group D is detected. The detector group E is composed of detectors Ea to Ef, the detector group F is composed of detectors Fa to Ff, and the detector group G is composed of detectors Ga to Gf. The detector group H is composed of detectors Ha to Hf. Here, with respect to the pitch P of 1 bit length, the detectors are arranged at intervals of P / 8, and the detector groups A to H respectively detect magnetic patterns indicating 6-bit non-repetitive serial codes. .

  In each magnetic track 70, a 6-bit non-repetitive serial code is combined and recorded as a non-repetitive magnetic pattern so that it is generated only once over the entire length of the magnetic scale 7.

  FIG. 10 is a block diagram showing components of the comparator group 3 of FIG. In FIG. 10, the comparator group 3 includes four comparators 3c to 3f. FIG. 11 is a block diagram showing components of the comparator 3c in FIG. In FIG. 11, the comparator 3 c includes exclusive OR circuits 31 to 36 respectively connected to the output terminal from the detector group A and the output terminal from the detector group E, and the exclusive OR circuits 31 to 36. 36 and an AND circuit 30 connected to each other via an inverter circuit. Here, the comparator 3c performs the same operation as the comparator 3a of FIG. 2 according to the first embodiment described above. Further, the configurations and operations of the comparators 3d to 3f in FIG. 10 are the same as those of the comparator 3c in FIG.

  In FIG. 10, the comparator 3c compares the detection signal SA from the detector group A with the detection signal SE from the detector group E, and outputs the comparison result signal to the encoder 6a and the selector 4a. The comparator 3d compares the detection signal SB from the detector group B with the detection signal SF from the detector group F, and outputs the comparison result signal to the encoder 6a and the selector 4a. The comparator 3e compares the detection signal SC from the detector group C with the detection signal SG from the detector group G, and outputs the comparison result signal to the encoder 6a and the selector 4a. The comparator 3f compares the detection signal SD from the detector group D with the detection signal SH from the detector group H, and outputs the comparison result signal to the encoder 6a and the selector 4a.

  Here, each of the comparators 3c to 3f includes a detector group A and a detector group E, a detector group B and a detector group F, a detector group C and a detector group G, a detector group D and a detector group. The detection signal of each detector of H is input. For example, in the comparator 3c, the detection signal of the detector group A and the detection signal of the detector group E are input, and the detector Aa and the detector Ea, the detector Ab and the detector Eb, the detector Ac and the detector Ec. The detection outputs of the detector Ad and the detector Ed, the detector Ae and the detector Ee, and the detector Af and the detector Ef are compared. If all are the same, “1” is output as the comparison result cmp [0]. . Similarly, in the comparators 3d, 3e, and 3f, the detection outputs of the detectors of the detector group B and the detector group F, the detector group C and the detector group G, and the detector group D and the detector group H are compared. If all are the same, “1” is output as each comparison result cmp [1], cmp [2], cmp [3]. Furthermore, the outputs from the comparators 3c and 3f are output to the selector 4a as the comparison results sel [0] and sel [1].

  Based on the comparison results sel [0] and sel [1] from the comparator 3c and the comparator 3f, the selector 4a receives detection signals from one detector group among the eight detector groups A to H. The selected detection signal is output as a 6-bit serial code S1.

  Based on the table stored in the table memory 5ma, the data converter 5a converts the 6-bit serial code S1 input from the selector 4a into absolute position information S2 indicating the absolute position of the moving body and outputs the information.

  Based on the comparison results from the comparators 3c to 3f, the encoder 6a generates and outputs divided position information S3 indicating the position where the 1-bit length pitch P is further divided into eight.

  The operation of the absolute position detection apparatus 1A configured as described above will be described below.

  12A is an operation timing chart of the absolute position detection device 1A of FIG. In FIG. 12A, absolute position information indicating the absolute position of the moving body is output using the magnetic scale 7 and the detector group 2a. A detector group A composed of six detectors Aa to Af arranged at a pitch P of 1 bit length detects a magnetic pattern having a 6-bit serial code. Similarly, each of the detector groups B to H detects a magnetic pattern having a 6-bit serial code. Here, each detector Aa-Af, Ba-Bf, Ca-Cf, Da-Df, Ea-Ef, Fa-Ff, Ga-Gf, Ha-Hf is "0" when facing the S pole, When facing the N pole, “1” is output respectively. Here, a timing chart of detection signals SA to SH, which are 6-bit serial codes output from the detector groups A to H when the magnetic scale 7 moves in the direction of the arrow, is illustrated. For example, when the detector group A is at the boundary of the magnetic pattern, it becomes unstable which detection result the detector group A outputs. Therefore, when the detector group A detects a different magnetic pattern, an erroneous detection result is output. On the other hand, in the second embodiment, an erroneous detection result is output by selecting one set of detector groups that are not near the boundary of the magnetic pattern from among the eight sets of detector groups A to H. It is characterized by not. In FIG. 12A, it is understood that the shaded portions of the detector groups C, F, and H are portions selected by the selector 4a and are not near the boundary between detection results.

  In FIG. 12A, the data conversion unit 5a outputs “0” when a 6-bit serial code “000000” is input according to the table stored in the table memory 5ma shown in FIG. 12B, and the 6-bit serial code “000001”. "1" is output as absolute position information S2, "2" is output as 6-bit serial code "000010", and 6-bit serial code "000100" is input. When “3” is output as the absolute position information S2 and the 6-bit serial code “001000” is input, “4” is output as the absolute position information S2.

  The encoder 6a receives the comparison results cmp [3] to cmp [0] input from the comparator group 3, and obtains the division position information S3 based on the input comparison results cmp [3] to cmp [0]. Generate and output. That is, a value obtained by dividing the 1-bit length pitch P into 8 is output. Here, if the comparison results cmp [3] to cmp [0] are “0001”, “0” is output as the division position information S3, and if “0011”, “1” is output as the division position information S3. If “0111”, “2” is output as the division position information S3. If “1111”, “3” is output as the division position information S3. If “1110”, “4” is output as the division position information S3. "1100", "5" is output as the division position information S3, "1000" is output as "6" as the division position information S3, and "0000" is the division position information. “7” is output as S3. Therefore, a resolution obtained by further dividing the 1-bit length pitch P into 8 can be obtained.

  FIG. 13 is a schematic diagram for explaining the operation of the selector 4a of FIG. 13A to 13D show various positional relationships between the magnetic track 70 and the detector group 2a. Here, when the detection results of the detector group A and the detector group E are the same, and the detection results of the detector group D and the detector group H are also the same, the detection results of the detector group A to the detector group H All are the same, there is no magnetic pattern boundary between the detector group A and the detector group H, and there is no magnetic pattern between the detector group H and the detector group A as shown in FIG. It can be judged that there is a boundary. In this case, since the detector group A and the detector group H are near the boundary of the magnetic pattern, the selector 4a selects the detector group G from the detector group B (detector group C in this embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern.

  When the detection results of the detector group A and the detector group E are the same, but the detection results of the detector group D and the detector group H are different, there is a magnetic field between the detector group A and the detector group E. Since there is no pattern boundary and there is a magnetic pattern boundary between the detector group D and the detector group H, the magnetism is detected between the detector group E and the detector group H as shown in FIG. It can be determined that there is a pattern boundary. In this case, since the detector group E and the detector group H are near the boundary of the magnetic pattern, the selector 4a can select the detector group D from the detector group A (detector group C in this embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern.

  When the detection results are different between the detector group A and the detector group E, and the detector group D and the detector group H, the boundary of the magnetic pattern is between the detector group A and the detector group E, and the detector group Since it is also between D and the detector group H, it can be determined that there is a magnetic pattern boundary between the detector group D and the detector group E as shown in FIG. In this case, since the detector group D and the detector group E are near the boundary of the magnetic pattern, the selector 4a operates from the detector group A to the detector group C or from the detector group F to the detector group H (this embodiment). Then, if the detector group H) is selected, it is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern.

  If the detection results of the detector group A and the detector group E are different, but the detection results of the detector group D and the detector group H are the same, the boundary of the magnetic pattern is the detector group A and the detector group E. And not between the detector group D and the detector group H, it can be determined that it is between the detector group A and the detector group D as shown in FIG. In this case, since detector group A and detector group D are near the boundary of the magnetic pattern, selector 4a selects detector group H from detector group E (detector group F in the present embodiment). It is possible to avoid outputting an unstable detection signal from the detector group near the boundary of the magnetic pattern. The description of these operations is shown in FIG. 12A, and it can be understood that the hatched portions of the detector groups C, F, and H are portions selected by the selector 4a and are not near the detection result boundaries.

  According to the absolute position detection device 1A according to the above embodiment, the same effect as that of the absolute position detection device 1 according to Embodiment 1 can be obtained. Furthermore, the absolute position detection device 1A can generate and output divided position information obtained by dividing the 1-bit length pitch P into eight, compared with the absolute position detection device 1 according to the first embodiment. It is possible to detect the absolute position of the moving body with a resolution obtained by dividing the long pitch P into eight. Therefore, the absolute position detection device 1A can detect the absolute position of the moving body with twice the resolution of the absolute position detection device 1 according to the first embodiment.

  In the present embodiment described above, in the comparator group 3, the detector group A and the detector group E, the detector group B and the detector group F, the detector group C and the detector group G, and the detector group D and Although the detection output of each detector of the detector group H is compared and the comparison results cmp [3] to cmp [0] are output, the present invention is not limited to this. For example, any combination of detector groups may be compared as long as the subsequent position can be uniquely generated by the encoder 6a. Furthermore, in the present embodiment, the comparator group 3 includes four comparators 3c to 3f, but the present invention is not limited to this. For example, the comparator group 3 may include an arbitrary number of comparators, and the division position information may be generated and output using the comparison result.

  Further, in the above-described embodiment, the comparator group 3 compares the detection signals of the detectors of the detector group A and the detector group E, the detector group D and the detector group H, and compares them. Although the selector 4a selects the detector group based on the results sel [1] to sel [0], the present invention is not limited to this. For example, the detector group compared by the comparator group 3 may be other than that. In this case, the detector group is set such that four combinations (0, 0), (0, 1), (1, 0), and (1, 1) are generated for the comparison result sel [1: 0]. It is desirable to cross and compare A and detector group E and detector group D and detector group H.

Modified example.
In the above-described embodiment, the absolute position information S2 indicating the absolute position of the moving body is output by detecting a non-repetitive magnetic pattern in which a 4-bit or 6-bit combination serial code is recorded on the magnetic track 70. However, the present invention is not limited to the above-described embodiment. For example, as a modification of the above-described embodiment, a non-repetitive magnetic pattern in which a combination serial code of a natural number n bits is recorded is arranged with a 1-bit length P. The present invention can also be applied to an absolute position detection device that detects non-repetitive magnetic patterns by using n detectors as a set of detector groups and using only m sets of the detector groups. In this case, the detectors are arranged at intervals of P / m, and the absolute position detection device can output division position information obtained by dividing the pitch P of the magnetic pattern into m.

For example, an absolute position where a magnetic pattern indicating a non-repetitive serial code of a natural number n bits is formed on a moving body that moves linearly or rotates, and data indicating the absolute position of the moving body is output based on the formed magnetic pattern A magnetic scale on which the magnetic pattern having the non-repetitive serial code of n bits is combined so as to be generated only once over the entire length of the magnetic scale; and the magnetic at one pitch interval of the magnetic pattern N detectors arranged opposite to the scale as one set, at least four or more sets are arranged, and a detector group for detecting the magnetic pattern and two sets of the four or more sets of detector groups. Based on the comparison results obtained by comparing the detection signals from the detector groups with the comparison results obtained by comparing the detection signals from the respective detector groups, A switching unit that selects a detection signal from a set of detectors from a detector group, and outputs the selected detection signal as serial code n bits,
A conversion unit that converts the n-bit serial code into absolute position information indicating the absolute position of the mobile body and outputs the absolute position information.

  In addition, the absolute position detection device according to the above-described embodiment includes a division position information generation unit that generates and outputs division position information indicating a position obtained by further dividing one pitch interval based on the comparison results compared with each other. Further prepare.

  In the absolute position detection device according to the above-described embodiment, the comparator group includes a first comparator that compares detection signals from two non-adjacent detector groups, and two non-adjacent sets. And a second comparator for comparing a detection signal from a detector group located between the detector groups and a detection signal from a detector group not located between the two non-adjacent detector groups. .

  Furthermore, in the absolute position detection apparatus according to the above-described embodiment, the detectors of the four or more sets of detector groups are arranged at equal intervals within one pitch interval of the magnetic pattern.

  Furthermore, in the absolute position detection device according to the above-described embodiment, the magnetic scale is formed in a linear shape, and the magnetic pattern is recorded on the surface of the magnetic scale.

  In the absolute position detection device according to the above-described embodiment, the magnetic scale is formed in a cylindrical shape, and the magnetic pattern is recorded on the top surface, bottom surface, or side surface of the magnetic scale.

  As described above in detail, according to the absolute position detection device of the present invention, data indicating the absolute position of the moving body is output based on a detection signal from a detector group not near the boundary of the magnetic pattern. It is possible to output data indicating the absolute position of the moving body without newly providing a scale and a detector.

  1, 1A absolute position detector, 2 detector group, 3 comparator group, 3a-3f comparator, 4, 4a selector, 5, 5a data conversion unit, 5m, 5ma table memory, 6, 6a encoder, 7 magnetic scale 10a, 10b Magnetized rotor, 14 rotation axes, 30 AND circuit 30, 31-36 Exclusive OR circuit, 70, 70a, 70b Magnetic track.

Claims (6)

An absolute position detection device that forms a magnetic pattern indicating a non-repetitive serial code of a natural number n bits on a moving body that moves linearly or rotates, and outputs data indicating the absolute position of the moving body based on the formed magnetic pattern Because
A magnetic scale on which the magnetic pattern having the n-bit non-repetitive serial code combined so as to occur only once over the entire length of the magnetic scale;
A set of n detectors arranged to face the magnetic scale at one pitch interval of the magnetic pattern as a set, at least four sets of detectors for detecting the magnetic pattern; and
A comparator group for comparing detection signals from two detector groups of the four or more detector groups, respectively;
Based on the comparison results, the detection signals from one set of the detector groups are selected from the four or more sets of detector groups, and the selected detection signals are output as an n-bit serial code. A switching unit;
An absolute position detection apparatus comprising: a conversion unit that converts the n-bit serial code into absolute position information indicating the absolute position of the moving body and outputs the absolute position information.   2. The absolute position according to claim 1, further comprising: a divided position information generation unit that generates and outputs divided position information indicating positions obtained by further dividing one pitch interval based on the comparison results respectively compared. Detection device.   The comparator group includes a first comparator for comparing detection signals from two non-adjacent detector groups, and a detection signal from a detector group positioned between the two non-adjacent detector groups. The absolute position detection according to claim 1, further comprising: a second comparator that compares a detection signal from a detector group that is not positioned between the two non-adjacent detector groups. apparatus.   The absolute detector according to any one of claims 1 to 3, wherein the detectors of the four or more sets of detector groups are arranged at equal intervals within one pitch interval of the magnetic pattern. Position detection device.   The absolute position detecting device according to any one of claims 1 to 4, wherein the magnetic scale is formed in a linear shape, and the magnetic pattern is recorded on a surface of the magnetic scale.   The absolute position detection according to claim 1, wherein the magnetic scale is formed in a cylindrical shape, and the magnetic pattern is recorded on an upper surface, a bottom surface, or a side surface of the magnetic scale. apparatus.

Images