JPH116744A - Encoder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a λ/4-system encoder device that can obtain an accurate detection signal without affecting the duty of the detection signal by a magnetic sensor even when a magnetization signal of a magnetic storage part fluctuates. SOLUTION: A magnetic sensor 15 is provided so that it opposes a magnetic storage part 10, the magnetic storage part 10 and the magnetic sensor 15 are relatively moved, and the magnetic sensor 15 outputs an electrical signal. In the magnetic storage part 10, N and S electrodes are alternately magnetized and stored at a given spacing, and a nonmagnetization part 12 that is magnetized at neither the N nor S electrode is formed at a position where the N electrode is switched to the S one. When a wavelength that is equal to one cycle of the N and S electrodes of the magnetic storage part 10 is set to λand the length of the non-magnetization part 12 in the magnetic pole arrangement direction of the magnetic storage part is set to A,A<λ/4 should be established.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor disposed opposite a magnetic recording unit, and the magnetic sensor detects a change in magnetism and outputs an electric signal by a relative movement between the magnetic recording unit and the magnetic sensor. The present invention relates to an encoder device that can be used as, for example, a motor speed detector.

[0002]

2. Description of the Related Art For example, as a speed detector for a small motor,
A frequency power generation magnet as a magnetic recording portion is provided on the outer periphery of the rotor case by alternately magnetizing N poles and S poles at a constant period, and is rotated integrally with the rotor to face the frequency power generation magnet. In some cases, a frequency generating coil is arranged so as to detect the motor speed from an alternation signal corresponding to the motor speed output from the frequency generating coil. Further, a magnetic sensor including a magnetoresistive element or the like is arranged in place of the frequency power generating coil, and the motor speed is detected from an alternating signal corresponding to the motor speed output from the magnetic sensor. is there. The present invention relates to the latter type of encoder device using a magnetic sensor. In the magnetic sensor composed of a magnetoresistive element or the like, a magnetic sensing portion pattern composed of a magnetoresistive element is arranged at a predetermined interval corresponding to a magnetization cycle of the magnetic recording section.

In an encoder device of the type using the above magnetic sensor, a magnetic recording portion having an N-pole and an S-pole alternately magnetized at a constant period may change its magnetic force due to disturbance of the magnetization. is there. The reasons for the disturbance of magnetization are:
There are various factors as follows. That is, when the magnetic recording portion is a molded product of a plastic magnet, molding unevenness occurs at a weld portion, a gate opening, and the like, which is a factor of disturbing magnetization. Further, the magnetization itself may be uneven.
Further, the magnetization may be disturbed by a scratch or a dent. The magnetic recording section is subjected to a finishing lace processing after molding to obtain a high mechanical precision, and is finally subjected to a predetermined magnetization. However, scratches and dents are likely to be formed during the lace processing.

On the other hand, a magnetic sensor disposed opposite to a magnetic recording section is configured to apply two magnetic sensing element patterns each composed of a magnetoresistive element to a wavelength λ of one cycle of an N pole and an S pole of the magnetic recording section. A so-called λ / 4 system arranged with a phase difference of 4 is often used. This method is advantageous in that no bias magnet is required and the configuration of the magnetic sensor is simple. However, the above λ / 4
According to the method, there is a problem that the fluctuation of the magnetic field strength due to the disturbance of the magnetization as described above causes the fluctuation of the output waveform of the magnetic sensor, and the duty after the waveform shaping changes. Hereinafter, this problem will be described in detail.

When the magnetic recording portion is alternately magnetized and recorded on the N pole and the S pole at a constant period, the magnetic field waveform becomes a sine wave. Now, as shown in FIG.
It is assumed that it has been reduced to 0%. FIG. 14A shows the resistance change rate of the magnetic sensor according to the λ / 4 method at this time, and FIG. 14C shows the phase of each resistance of each magnetically sensitive part constituting the magnetic sensor.
FIG. 14D shows the midpoint potential of each of the above resistors. As is clear from FIG. 1, the above-mentioned midpoint potential means that when the power supply voltage Vcc is applied to one end of each of the resistors R1 and R2 of the magnetically sensitive portion electrically connected in series and the other end is set to the ground G, The output at the connection point between the resistors R1 and R2, that is, the midpoint output Vout. In FIG. 14D, the numbers “1”, “2”,..., “7” indicate the phases of the magnetic field waveform for each quarter of the wavelength λ, and the other numbers “180”, “1”
92, "168", etc. are the above phases "1", "2" ...
The angle between the zero cross points of the output signal at “7” is shown. FIG. 15 shows the respective phases “1”, “2”.
Angle deviation between zero-cross points of the output signal at “7”,
That is, the amount of change in duty due to the phase shift is shown. As is apparent from FIG. 15, the duty of the output signal fluctuates due to fluctuation of a part of the magnetic field of the magnetic recording unit.

[0006]

As shown in FIG. 14B, it is desirable that the phase of the output signal does not shift even if the peak value of a part of the magnetic field waveform fluctuates. However, when a part of the peak value of the magnetic field waveform fluctuates, as is apparent from FIGS. 14D and 15, the angle between the zero cross points of the output signal fluctuates, and the duty of the shaped waveform fluctuates.
A phase shift occurs. If a phase shift occurs in the output signal, it is determined that the speed has fluctuated even though the speed has not actually fluctuated, or the speed fluctuation is not accurately detected, resulting in a deterioration in the speed control accuracy. Will do.

The present invention has been made in view of the above-mentioned problems of the prior art, and is a so-called λ / 4 encoder device.
An object of the present invention is to provide an encoder device that does not affect the duty of a detection signal from a magnetic sensor and can obtain a highly accurate detection signal.

[0008]

According to the first aspect of the present invention,
In an encoder device in which a magnetic sensor is disposed to face the magnetic recording unit and the magnetic sensor outputs an electric signal by a relative movement between the magnetic recording unit and the magnetic sensor, the magnetic recording unit includes an N pole and an S pole alternately. Magnetized recording is performed at a predetermined interval, and a non-magnetized portion that is not magnetized at either the N pole or the S pole is formed at a switching position between the N pole and the S pole. . The invention described in claim 2 is claim 1
In the invention described above, when the wavelength for one cycle of the N pole and the S pole of the magnetic recording portion is λ, and the length of the non-magnetized portion in the magnetic pole array direction of the magnetic recording portion is A, A <λ / 4 It is characterized by having.

According to a third aspect of the present invention, in the encoder device, a magnetic sensor is disposed so as to face the magnetic recording unit, and the magnetic sensor outputs an electric signal by a relative movement between the magnetic recording unit and the magnetic sensor. The portion has a main magnetized portion in which N poles and S poles are magnetized and recorded at predetermined intervals alternately, and the peak value of the magnetic field at the switching position between the N pole and the S pole is between the N pole and the S pole. A sub-magnetized portion lower than the peak value of the magnetic field is formed.

According to a fourth aspect of the present invention, in the third aspect of the invention, the sub-magnetized portion is formed by magnetizing the main magnetized portion with the third harmonic, and the magnetic field generated by the third harmonic magnetized. Is 25 to 50%. According to a fifth aspect of the present invention, in the third aspect, the wavelength of one cycle of the N pole and the S pole of the magnetic recording unit is λ, and the length of the sub-magnetized portion in the magnetic pole arrangement direction of the magnetic recording portion is Is B, B <λ / 4.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the magnetic sensor patterns of the magnetic sensor are arranged at an interval of λ / 4.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an encoder device according to the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 10 denotes a magnetic recording unit which is provided integrally with an outer peripheral portion of a rotor of a motor and rotates integrally with the rotor. The magnetic recording unit 10 has a magnetized part 11 in which N poles and S poles are alternately magnetized and recorded at a predetermined interval, and the magnetized part 11 is located at the switching position between the N pole and the S pole. , A non-magnetized portion 12 that is not magnetized at either the N pole or the S pole. A magnetic sensor 15 is arranged so as to be opposed to and close to the magnetized portion 11. The magnetic sensor 15 includes two stripe-shaped magneto-sensitive portion patterns R1 and R2 formed by folding. The magnetic sensing portion patterns R1 and R2 are composed of a magnetoresistive effect element (MR element). When the wavelength for one cycle of the N pole and the S pole of the magnetic recording portion is λ, the two magnetic sensing portion patterns R
1, R2 are arranged at an interval of λ / 4. The two magnetic sensing part patterns R1 and R2 are formed so as to be electrically connected in series, one end of which is a power supply voltage application terminal Vcc, the other end of which is a ground terminal G, and one of the magnetic sensing part patterns R1 and R2. The middle point is connected to the output terminal Vout. When the length of the non-magnetized portion 12 in the magnetic pole array direction of the magnetic recording portion 10 is A, the relationship is A <λ / 4.

A magnetized portion 11 and a non-magnetized portion 1 in a magnetic recording portion 10
FIG. 5 shows an example of a magnetizing device for forming the magnetic head 2. In FIG. 5, a head 21 of a magnetizer is arranged so as to sandwich a magnetic recording unit 10 made of a magnet material, and a magnetizing current is supplied from a power source 23 to a coil of the magnetizing head 21 while moving the magnetic recording unit 10 at a constant speed. Is supplied to the magnetic recording unit 10 in a punched shape from the thickness direction in the N pole, the non-magnetized portion, the S pole, the non-magnetized portion,
Magnetize in a pattern of N poles,..., And form a non-magnetized portion when the N pole and the S pole are reversed. The waveform indicated by a broken line 25 in FIGS. 6A and 7 is a basic magnetization waveform when the N pole and the S pole are alternately magnetized without providing a non-magnetized portion, and has a sinusoidal waveform. I have. In FIG. 6A, reference characters R1,
R2 indicates the magnetic sensing portion pattern, and the magnetic sensing portion patterns R1 and R2 are arranged at an interval of λ / 4 from each other. The waveform shown by the solid line 26 in FIG. 6B and FIG. 7 indicates a case where a non-magnetized portion that is not magnetized on either the N pole or the S pole is formed at the switching position between the N pole and the S pole. Is a magnetized waveform of FIG. As shown in FIG. 7, the width of the magnetic field waveform corresponding to the magnetized portion 11 is a in the basic magnetic field waveform 25, but the width b is smaller than a due to the provision of the non-magnetized portion. Becomes

Now, the N pole and S
The case of a basic sine wave magnetic field in which the poles are alternately magnetized will be described. As described with reference to FIG. 15, the phase of the output signal is shifted due to a part of the magnetic field of the magnetic recording unit 10 fluctuating, and the duty fluctuates. I do. The amount of change in the duty varies depending on the strength of the magnetic field. FIG. 9 (a)
Sets the magnetic field strength to 3 mT (milli-Tesler), 8 mT,
The phase shift of the detection output in a sine wave magnetic field at each magnetic field strength is shown by changing the phase gradually to 14 mT. The graph with the parallel diagonal line rising to the right shows the phase shift when 3 mT, the graph with the parallel diagonal line going down the right shows 8 mT, and the graph with the cross diagonal line shows the phase shift when it is 14 mT. As is clear from FIG. 9A, in a sine wave magnetic field, a part of the magnetic field fluctuates, so that the phase of the output signal is shifted, and the phase shift occurs regardless of the strength of the magnetic field.

Therefore, in the embodiment shown in FIG. 1, the zero-cross point of the detection output of the magnetic sensor 15 is shifted to the high resistance side, that is, the zero magnetic field side, which is hardly affected by the magnetic field fluctuation. The non-magnetized portion 12 was formed at the switching position between the N pole and the S pole of the magnetized portion 11. Therefore, according to the embodiment shown in FIG. 1, the intensity of the magnetic field fluctuates due to the disturbance of the magnetization of the magnetic recording unit 10, and the magnetic sensor 1
Even if the peak value of the output waveform of FIG. 5 fluctuates, as shown in FIG. 3A, the angle fluctuation between the zero-cross points of the output waveform is small due to the presence of the non-magnetized portion 12, and the shaping waveform of FIG. As shown in (b), the fluctuation of the duty is reduced. However, if the length of the non-magnetized portion 12 in the magnetic pole arrangement direction of the magnetic recording portion is unlimitedly increased, the opposite effect is obtained. Therefore, the length of the non-magnetized portion 12 in the magnetic pole arrangement direction of the magnetic recording portion is set to λ / 4 or less.

Next, the embodiment shown in FIG. 2 will be described. In FIG. 2, the magnetic recording unit 10 is provided integrally with the outer periphery of the rotor of the motor and rotates integrally with the rotor.
Has a main magnetized portion 11 in which N poles and S poles are alternately magnetized and recorded at predetermined intervals, and the main magnetized portion 11 is provided with a magnetic field at a position where the N pole and S pole are switched. The peak value is lower than the peak value of the magnetic field of the N pole and the S pole,
A sub-magnetized portion 13 including a pole and an S pole is formed. The magnetic pole of the sub-magnetized portion 13 is opposite to the magnetic pole of the adjacent main magnetized portion 11. A magnetic sensor 15 is arranged so as to be opposed to and close to the magnetized portion 11. The magnetic sensor 15 has exactly the same configuration as the magnetic sensor described with reference to FIG.
It consists of two magnetic sensing part patterns R1 and R2 composed of R elements. The wavelength for one cycle of the N pole and S pole of the magnetic recording portion is λ
, The two magnetic sensing part patterns R1 and R2 are λ
/ 4 intervals. Two magnetic sensing part patterns R
1 and R2 are electrically connected in series, one end of which is connected to the power supply voltage application terminal Vcc, the other end is connected to the ground terminal G, and the middle point of the magnetic sensing part patterns R1 and R2 is connected to the output terminal Vout. When the length of the sub-magnetized portion 13 in the magnetic pole array direction of the magnetic recording portion 10 is B, the relationship is B <λ / 4.

FIG. 4 shows an example of a magnetizing device for forming the main magnetized portion 11 and the sub magnetized portion 13 in the magnetic recording portion 10. FIG.
In the above, the magnetized head 20 is arranged such that its head gap is brought into close proximity to or slidable contact with the peripheral surface of the magnetic recording portion 10 made of a magnet material, and the magnetic recording portion 10 is magnetized while moving at a constant speed. Power supply 2 for coil of head 20
3, a magnetizing current is supplied to the magnetic recording unit 10 by the leak magnetizing method.
Then, a main magnetized portion 11 and a sub magnetized portion 13 are formed. That is,
At the time of reversal of the N-pole and S-pole for forming the main magnetized portion 11, the reversal is performed with a weaker magnetic field than when the main magnetized portion 11 is formed. As a result, as shown in FIG. A magnetized band having the same effect as that of forming the non-magnetized portion 12 is provided.
The waveform shown in FIG. 6C is a magnetization waveform when the sub-magnetization portion 13 is formed at the switching position between the N-pole and the S-pole of the main magnetization portion 11.

According to the embodiment shown in FIG. 2, the sub-magnetized portion 13 is formed at the switching position between the N-pole and the S-pole of the main magnetized portion 11 of the magnetic recording portion 10. As a result, FIG. Since the same effect as when the non-magnetized portion 12 is formed as in the embodiment shown in FIG. 1 is provided, the strength of the magnetic field fluctuates due to the disturbance of the magnetization of the magnetic recording portion 10, and the output waveform of the magnetic sensor 15 is changed. Even if the peak value fluctuates, the presence of the sub-magnetized portion 13 reduces the angle fluctuation between the zero-cross points of the output waveform, and reduces the duty fluctuation of the shaped waveform. However,
If the length of the sub-magnetized portion 13 in the magnetic pole arrangement direction of the magnetic recording portion is unlimitedly increased, the opposite effect is obtained. Therefore, the length of the sub-magnetized portion 13 in the magnetic pole arrangement direction of the magnetic recording portion is set to λ.
/ 4 or less.

The magnetized waveform shown in FIG. 6C has a form in which the third harmonic is superimposed on the main magnetized waveform. Therefore,
The magnetic recording unit 10 can also be formed by superimposing a third harmonic on a main magnetized sine wave. When the third harmonic is superimposed on the main sinusoidal magnetized waveform, it is inverted under the influence of the third harmonic at the switching portion between the N-pole and S-pole of the main magnetized waveform, and the N-pole of the main magnetized waveform is inverted. Then, the width becomes narrow at the center of the S pole and the waveform becomes as shown in FIG.

Therefore, a part of the main sine-wave magnetized waveform is reduced to 80%, the ratio of the third harmonic superimposed on the main sine-wave magnetized waveform is changed stepwise, and the magnetic field of the magnetic field is further reduced. When the strength was also changed step by step, it was verified how the phase shift of the detection output of the magnetic sensor according to the λ / 4 method occurs. FIG. 8B shows a sine wave magnetic field in which a part of the waveform shown in FIG.
4 shows a superimposed magnetic field waveform. Similarly, FIG. 8C shows a magnetic field waveform in which the third harmonic is superimposed by 40%, FIG. 8D shows a magnetic field waveform in which the third harmonic is superimposed by 50%, and FIG. Each shows a magnetic field waveform superimposed by 60%. As the ratio of the third harmonic increases, the N pole and S
It can be seen that the influence of the third harmonic at the switching portion between the poles increases, and the magnetic field at the sub-magnetization portion increases.

FIG. 10 shows that the third harmonic is 30% in the main magnetized portion.
(A) shows the phase of each resistance of the magnetosensitive portions R1 and R2 in the superposed magnetic field and the output of the midpoint potential thereof.
Is when the magnetic field strength is 3 mT, (b) is when the magnetic field strength is 8
In the case of mT, (c) shows the case where the magnetic field strength is 14 mT, respectively. FIG. 9B shows the phase shift between the zero-cross points of the midpoint potential output. FIG. 9B
Are compared with the above-described FIG.
As shown in FIG. 9B in comparison with FIG. 9A, the phase shift of the output waveform remains slightly, but the phase shift is greatly improved. . Therefore, if the output waveform is shaped at the zero-cross point, the amount of change in duty can be reduced, and when this is used for speed control of the motor, accurate speed control can be performed.

FIG. 11 shows that the third harmonic is 40% in the main magnetized portion.
(A) shows the phase of each resistance of the magnetosensitive portions R1 and R2 in the superposed magnetic field and the output of the midpoint potential thereof.
(B) and (c) show that the magnetic field strength is 3 mT, 8 mT,
The case of 14 mT is shown. FIG. 9C shows a phase shift between the zero-cross points of the midpoint potential output.
As is clear from FIG. 9C in comparison with FIG. 9A, the phase shift of the output waveform disappears regardless of the magnitude of the magnetic field. Therefore, if this output waveform is shaped at the zero-cross point, there is no change in duty,
When this is used for motor speed control, extremely accurate speed control can be performed.

FIG. 12 shows that the third harmonic is 50% in the main magnetized portion.
(A) shows the phase of each resistance of the magnetosensitive portions R1 and R2 in the superposed magnetic field and the output of the midpoint potential thereof.
(B) and (c) show that the magnetic field strength is 3 mT, 8 mT,
The case of 14 mT is shown. When the third harmonic is superimposed by 50%, the third harmonic component becomes considerably large as shown in FIG. 8D, and a phase shift occurs between the zero-cross points of the midpoint potential outputs of the magnetic sensing units R1 and R2. . However, this phase shift is smaller than the phase shift in the case of a sine wave magnetic field, and a practical effect is recognized.

FIG. 13 shows that the third harmonic is 60% in the main magnetized portion.
(A) shows the phase of each resistance of the magnetosensitive portions R1 and R2 in the superposed magnetic field and the output of the midpoint potential thereof.
(B) and (c) show that the magnetic field strength is 3 mT, 8 mT,
The case of 14 mT is shown. When the third harmonic is superimposed by 60%, the third harmonic component becomes too large as shown in FIG. 8E, and the phase shift between the zero-cross points of the midpoint potential outputs of the magnetic sensing units R1 and R2 becomes large. No practical effect is recognized.

As apparent from the description of FIGS. 8 to 13, the desired effect cannot be obtained unless the ratio of the third harmonic magnetic field superimposed on the sine wave magnetic field is 50% or less. The desired effect can be obtained up to a ratio of the third harmonic magnetic field of about 25%, but the desired effect cannot be obtained if the ratio is less than about 25%. Therefore, the ratio of the third harmonic magnetic field capable of obtaining the desired effect is 25% or more and 50% or less. However, it is more preferable that the content be 30% or more and 45% or less.

[0026]

According to the first aspect of the present invention, in the encoder device in which the magnetic sensor detects a change in magnetism and outputs an electric signal by a relative movement between the magnetic recording unit and the magnetic sensor, the magnetic recording unit includes: , The N pole and the S pole are alternately magnetized and recorded at a predetermined interval, and the non-magnetized portion that is not magnetized in either the N pole or the S pole is located at the switching position between the N pole and the S pole. Due to the formation, the strength of the magnetic field fluctuates due to the disturbance of the magnetization of the magnetic recording portion, and even if the peak value of the output waveform of the magnetic sensor fluctuates, the presence of the non-magnetized portion causes the zero point between the zero cross points of the output waveform. The phase shift is small, and the shaped waveform has a small variation in duty. When this waveform is used, for example, for motor speed control, high-accuracy speed control can be performed.

According to the second aspect of the present invention, the wavelength of one cycle of the N pole and the S pole of the magnetic recording portion is defined as λ, and the length of the non-magnetized portion in the magnetic pole array direction of the magnetic recording portion is defined as A. In this case, since A <λ / 4, the phase shift between the zero-cross points of the output waveform can be effectively reduced, and it is possible to prevent the non-magnetized portion from becoming too long and having the adverse effect. it can.

According to the third aspect of the present invention, in the encoder device wherein the magnetic sensor detects a change in magnetism and outputs an electric signal by a relative movement between the magnetic recording unit and the magnetic sensor, A pole and a south pole have a main magnetized portion magnetized and recorded at a predetermined interval alternately, and the peak value of the magnetic field is at the switching position between the north pole and the south pole.
Since the sub-magnetized portion lower than the peak value of the magnetic field of the pole and the S pole is formed, the intensity of the magnetic field fluctuates due to the disturbance of the magnetization of the magnetic recording portion, and the peak value of the output waveform of the magnetic sensor fluctuates. Even when the sub-magnetized portion has the same function as forming the non-magnetized portion, the phase shift between the zero cross points of the output waveform is small, and the shaped waveform has less duty fluctuation. When this waveform is used, for example, for controlling the speed of a motor, highly accurate speed control can be performed.

According to the fourth aspect of the present invention, the sub-magnetized portion is formed by subjecting the main magnetized portion to third harmonic magnetization, and the ratio of the magnetic field due to the third harmonic magnetization is 25 to 50
%, The phase shift between the zero-cross points of the output waveform can be more effectively reduced.

According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the wavelength of one cycle of the N pole and the S pole of the magnetic recording portion is set to λ, and the secondary deposition in the magnetic pole arrangement direction of the magnetic recording portion is performed. When the length of the magnetic part is B, since B <λ / 4,
The phase shift between the zero-cross points of the output waveform can be effectively reduced, and it is possible to prevent the non-magnetized portion from being too long and having the opposite effect.

[Brief description of the drawings]

FIG. 1 is a development view showing an embodiment of an objective encoder device according to the present invention.

FIG. 2 is a development view showing another embodiment of the objective encoder device according to the present invention.

FIG. 3 is a waveform chart showing an example of an output waveform of a magnetic sensor and a shaped waveform thereof according to the device of the present invention.

FIG. 4 is a front view showing an example of magnetization of a magnetic recording unit of the device of the present invention.

FIG. 5 is a front view showing another example of the magnetization of the magnetic recording unit of the device of the present invention.

FIGS. 6A and 6B show various examples of magnetization waveforms on a magnetic recording unit. FIG. 6A shows a basic waveform, FIG. 6B shows a case where a non-magnetization part is provided, and FIG. FIG. 9 is a waveform diagram in the case where the filter is provided.

FIG. 7 is a waveform diagram showing a comparison between magnetic field waveforms when a magnetic recording unit is fundamentally magnetized and when a non-magnetized unit is formed.

FIG. 8 is a waveform chart sequentially showing a change in a magnetic field waveform when a sine wave magnetic field and a third harmonic are superposed stepwise when the magnetic recording unit is fundamentally magnetized.

FIG. 9 is a graph showing the phase shift of the magnetic sensor output in the case where the magnetic recording unit is fundamentally magnetized and the case where the third harmonic is superposed stepwise.

FIG. 10 shows that the third harmonic is 30% in the main magnetized portion of the magnetic recording portion.
FIG. 9 is a waveform diagram showing the phase of the magnetic sensor output and the midpoint potential output when the intensity of the magnetic field is superimposed and the intensity of the magnetic field is changed stepwise.

FIG. 11 shows that the third harmonic is 40% in the main magnetized portion of the magnetic recording portion.
FIG. 9 is a waveform diagram showing the phase of the magnetic sensor output and the midpoint potential output when the intensity of the magnetic field is superimposed and the intensity of the magnetic field is changed stepwise.

FIG. 12 shows a 50% third harmonic in a main magnetized portion of a magnetic recording portion.
FIG. 9 is a waveform diagram showing the phase of the magnetic sensor output and the midpoint potential output when the intensity of the magnetic field is superimposed and the intensity of the magnetic field is changed stepwise.

FIG. 13 shows a third harmonic of 60% in the main magnetized portion of the magnetic recording portion.
FIG. 9 is a waveform diagram showing the phase of the magnetic sensor output and the midpoint potential output when the intensity of the magnetic field is superimposed and the intensity of the magnetic field is changed stepwise.

FIG. 14 is a waveform diagram showing an example of a magnetoresistance effect, a magnetic field waveform, a phase of a magnetic sensor output, and a midpoint potential output of a magnetic sensor in a conventional encoder device.

FIG. 15 is a graph showing a phase shift of a magnetic sensor output in a conventional encoder device.

[Explanation of symbols]

 Reference Signs List 10 magnetic recording section 11 main magnetized section 12 non-magnetized section 13 sub-magnetized section 15 magnetic sensor R1 magnetic sensitive section R2 magnetic sensitive section

Claims (6)

[Claims] 1. An encoder device, wherein a magnetic sensor is disposed opposite to a magnetic recording unit, and the magnetic sensor detects a change in magnetism and outputs an electric signal by a relative movement between the magnetic recording unit and the magnetic sensor. In the magnetic recording unit, the N pole and the S pole are alternately magnetized and recorded at a predetermined interval, and neither the N pole nor the S pole is magnetized at the switching position between the N pole and the S pole. An encoder device wherein a non-magnetized portion is formed. 2. When the wavelength of one cycle of the N pole and the S pole of the magnetic recording portion is λ, and the length of the non-magnetized portion in the magnetic pole array direction of the magnetic recording portion is A, A <λ / 4. The encoder device according to claim 1, wherein 3. An encoder device in which a magnetic sensor is disposed opposite to a magnetic recording unit, and the magnetic sensor detects a change in magnetism by a relative movement between the magnetic recording unit and the magnetic sensor and outputs an electric signal. The magnetic recording portion has a main magnetized portion in which N poles and S poles are magnetized and recorded at predetermined intervals alternately, and the N pole and the S pole are
An encoder device, wherein a sub-magnetized portion having a peak value of a magnetic field lower than the peak values of the magnetic fields of the N pole and the S pole is formed at a switching position between the poles. 4. The method according to claim 3, wherein the sub-magnetized portion is formed by performing third harmonic magnetization on the main magnetized portion, and the ratio of the magnetic field due to the third harmonic magnetization is 25 to 50%. Encoder device. 5. When the wavelength of one cycle of the N pole and S pole of the magnetic recording portion is λ, and the length of the sub-magnetized portion in the magnetic pole arrangement direction of the magnetic recording portion is B, B <λ / 4. The encoder device according to claim 4, wherein 6. When the wavelength of one cycle of the N pole and the S pole of the magnetic recording unit is λ, the magnetic sensor pattern of the magnetic sensor is λ /
The encoder device according to claim 1, 2, 3, 4, or 5, which is arranged at four intervals.