JPS60135768A - Rotation detector - Google Patents

Abstract

PURPOSE:To eliminate distortion due to higher harmonics and reduce the size of a magnet by using a magnetism sensitive element and another magnetism sensitive element which has a pattern slanting at a specific angle to the pattern of said element, and adding outputs of those two elements together. CONSTITUTION:A detector 15 is constituted by arranging a magnetism sensitive element a which consists of ferromagnetic materials elememtns A1-D2 (elements A1 and B1, and B2 and A2) having magneto-resistance effect and is provided with a couple of mutualy orthogonal current paths and another magnetism sensitive elements B (composed of elements C1 and D1, and D2 and C2) of the same constitution with said element which is slanted at the specific angle (e.g. 45 deg.) to the couple of current paths, closely to a magnet which is magnetized to have two poles and provided on a rotating shaft. Then, output voltages e1 and e2 of the element A and output voltages e3 and e4 of the element B are applied to differential amplifiers respectively. Then outputs of those differential amplifiers are added together to obtain a rotation detection signal. Consequently, higher harmonic distortion in the detection signal is removed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotation detection device that detects the rotation speed, rotation phase, etc. of a rotating body using a magnetically sensitive element.

BACKGROUND ART AND PROBLEMS The present applicant has previously proposed a magnetically sensitive element that senses the direction of a magnetic field in Japanese Patent Application No. 79655/1983. This article relates to a rotation detecting device using the above-mentioned magnetically sensitive element, and first, an outline of the above-mentioned magnetically sensitive element will be explained.

Figure 1 shows the structure of a magnetically sensitive element (10), in which the surface pressure of a substrate (1) made of glass or the like, a ferromagnetic element (A
) The thin film of (B) is formed. The ferromagnetic elements (A) and (B) can be formed by depositing a ferromagnetic material in a comb-teeth shape or by depositing it on the entire surface and then etching it. These elements (A) (B) are each composed of a plurality of straight parts (2A) (2B) that serve as main current paths, and bent parts (5A) (3B') that connect these parts. The straight line portions (2A) and (2B) are arranged to be substantially orthogonal to each other. Also, the straight line part (2 people) (2B
) are connected, and the elements (A) and (B) are connected in series. An output terminal (5) is formed at the above connection part, and the straight part + (2A)
Current terminals (7A) (7B) are formed at the other ends (6A) (6B) of (2B), respectively. These terminals (5) (74X7B) are made of a conductive thin film.

Figure 2 is a diagram of the operating principle, in which the current terminals (7A) (7B) are connected to the power supply (8), and one current terminal (7B) is grounded, and the magnetoelectric conversion circuit (9) is constructed as a whole. It consists of ′ :・: ′ ・, Now, a magnetic field H of sufficient strength to saturate magnetize elements (A), , (, B) is applied to the element (A) in the plane formed by the elements (A) and (B). When added at an angle θ to the direction of the straight line part (two people), that is, the current direction, the element (A) (B
), each electrical resistance ρA1ρB changes, and the change is caused by the angle θ
) is expressed by the following formula.

ρA−ρ1Sin2θ+scoS2θ・・・・・・・・・
・・・・・・・・・・・・・・・■ρB=ρlCo52θ
+p,, 5in2θ ・・・・・・・・・Crystal...
・・・・■ However, ρ is the electric resistance of the element (A) (B) when the element (B) is saturated in the direction perpendicular to the current, and ρ1 is the electric resistance of the element (A) (B) when it is saturated (magnetized) in the direction parallel to the current. This is the electrical resistance of elements (A) and (B) at the time.

Also, the voltage V at the output terminal (5) is the element (A) (B)
are connected in series, so if the power supply voltage is Vo, it can be expressed by the following equation.

■θ=-hL-・VD ・・・・・・・・・・・・・・・
・・・・・・・・・■ρ人＋ρB Substituting the ■■ expression into the ■expression and rearranging it, we get (However, Δρ=ρ9−ρwork).

becomes. In this equation (2), the first term on the right side represents the reference voltage, and the second term represents the amount of change ' η, where Δ■θ=
--! ! -L 2θ・Vo ・・・・・・・・・・・・
・・・・・・・・・■4ρ.

And Sagoru Urayama. Let 2ρ0=~10ρ, and ρ. is the electrical resistance in the demagnetized state □.

□ Therefore, the voltage ■θ of the output terminal (5) changes depending on the direction of the magnetic field, and the output change is the minimum value when the magnetic field direction is 08.180°, and 90 °
, 27O0 becomes a sine waveform with a maximum value.

FIG. 4 shows an equivalent circuit, and it can be considered that the elements (A) and CB) are variable resistors whose resistance value changes depending on the direction of the magnetic field H.

When such a magnetically sensitive element (QO) is used in a rotation detection device, as shown in FIG. The magnetically sensitive element a0 is placed in the position shown by the solid line by being in contact with the magnetic signal 01). When the rotating body rotates in the direction of the arrow a, the direction of the magnetic field H of the magnetic signal aυ for the sensitive element allIl changes, and the output voltage θ shown in FIG. 6A from this sensitive element (11) is obtained. In the same way, if the magnetically sensitive element αω is mechanically tilted by 45° as shown by the imaginary line at the same position as shown by the solid line, or if the patterns of elements (A) and (B) are tilted by 45°, , the output voltage V, shown in FIG. 6B, has a phase difference of 90° with respect to the output voltage Ve shown in FIG. 3A. That is, the output voltage Vθ of FIG. If the waveform is a sine wave, the waveform of the output voltage ■θ in Fig. 6B is a cosine wave.
) If the pattern in (B) is shifted by mechanical angle β0, the output is,
A phase difference of electrical angle 2β0 occurs in the voltage Vθ.

FIG. 6 shows an embodiment of the detection circuit, in which the element (A)
Two sets of (B) are used to form a bridge configuration, with each set having one. With this bridge configuration, the temperature of the circuit can be compensated.

Fig. 7 shows two sets of magnetically sensitive elements (10) formed with two sets of elements (A) and (B).
are formed on the same board, and have output terminals for taking out the output voltages e1 and e2, a 10B power supply terminal, and a ground terminal (GND
) is provided.

Thus, the rotation detection device according to the method shown in FIG.
It is required to accurately record a magnetic signal consisting of a large number of north and south poles, and it is difficult to miniaturize the device. :.

Therefore, as shown in FIGS. 8 and 9, the magnet αJ, which has two poles magnetized on its plane, is attached to the rotation axis (1
A rotation detection device has been proposed in which the rotation of the magnet (13) is detected by a detector 051 using a gd element. With this configuration, no particular precision is required for the magnetization of the magnet Q3), and the device can be miniaturized. ,・In this rotation detection device, a sine wave output signal a: sin α and a cosine wave output signal ycos α are obtained from the detector a5 using a magnetically sensitive element, and from these two output signals, the following equation is obtained. The rotation detection signal VC is obtained by utilizing the properties of the trigonometric functions shown in FIG.

Vc= xsma +ycma =m s-(α0m-'-2-) ・・・・・・・・・
...■ However, α is the detection signal V. When expressed in electrical angles and expressed in mechanical angles, according to the above formula 0, α = 2
becomes θ.

As shown in FIGS. 8 and 9, since a two-pole magnetized magnet (13) is used, the above detection signal V.
14) changes only once per rotation, which is unsatisfactory when the rotation detection device is used as a frequency generator or the like. For this reason, an AC power source is connected all around the power source of the detector (15), so as to reduce the frequency of the detection signal (2).

Namely 1. When using an AC power supply with r=eosω and y=siaω, the above equation 0 is as follows.
・・・・・・・・・■. According to this equation 0, the detection signal V. It can be seen that if there is any distortion, the detection accuracy will be affected. As mentioned above, the magnetically sensitive element is used in a saturated magnetic field, but in the case of the rotation detection device shown in FIGS. If the magnetically sensitive element is not used in a saturated magnetic field, harmonic distortion is likely to appear in the output, resulting in deterioration of detection accuracy.

Object of the Invention The object of the present invention is to eliminate the output distortion due to the above-mentioned harmonics in a rotation detection device based on the principles described in connection with the above-mentioned formula (1) or (0) and Fig. 8.9.

Summary of the Invention The present invention provides If &
By using a magnetically sensitive element provided with an element having a pattern tilted at a predetermined angle with respect to the pattern of the m-type element dye element (A) and CB), and adding the outputs of these two magnetically sensitive elements, high-frequency harmonics can be obtained. It is processed to remove distortion caused by waves.

In this example, in order to obtain the sine wave output and cosine wave output in the above formula used. This detector a9 consists of eight elements (AI) (A2) (B1) CB2) (
01) (02) (DI) (B2)

FIG. 11 shows an equivalent circuit of the detector a9, and the eight elements described above constitute two sets of bridge circuits on the own side and the width side as shown.

In FIGS. 10 and 11, the element (A1XA2) corresponds to the element (A) in FIG. 1, and 1. element t, (B1) (B
2) is the 11th? element + (B) and corresponding 6・element (0・X0
2) It corresponds to the pattern of the element (A) tilted by 45 degrees, and the element (DI) (B2) corresponds to the pattern of the element (B) tilted by 45 degrees.

In m pieces, one end of the element (A1) is connected to the power supply terminal, and the other end is connected to one output terminal (1'JK/
It is connected together with one end of the element (B1). The above element (
The other end of B1) is connected to ground terminal a8 via conductor Q4). One end of the element (B2) is connected to the power supply terminal e above through the conductor (c), and the other end is connected to the output terminal -
It is connected to the. One end of the i-element (A2) is connected to the ground terminal a8, and the other end is connected to the output terminal (2) via the conductor (2).

Power terminal (17a) (17
b) are externally connected to each other and connected to the power supply terminals a in FIG.
η. One end of the element (C1) is a power supply terminal (17a)
K connection, and the other end is connected to the output terminal Qυ. One end of the element (Dl) is connected to the above output terminal (
2I), and the other end is connected to a ground terminal (18). One end of the element (B2) is a power supply terminal (17b)
The other end is connected to the output terminal (2 hot water) through the conductor @. One end of the element (C2) is connected to the output terminal (
The other end is connected to the ground terminal - via the conductor (2).

The power supply terminals α6) and η of the detector α9 configured as described above are supplied with the power supply voltages X%y of equations (6) and 0, respectively. Output voltages e1 and C2 are obtained from the output terminal H (XJ), and these positive output voltages e1s and e2 are applied to the differential amplifier in the same manner as in the case of Fig. 6.
Output voltages e5 and e4 are obtained from the katana @, and these output voltages are applied to other differential amplifiers. By adding the output signals of the two differential amplifiers using an adder, the detection signal (2) can be obtained as the added output.

Next, the principle of removing the sixth harmonic included in the detection signal will be explained.

Letting the output voltage of the magnetically sensitive element be Vα1, and expressing α1 including the 6th harmonic, Va1= al sin α+B, 3Sjn 5α ・・
・・・・・・・・・・・・・・・・・・■. 12th A
The solid line in the figure indicates the fundamental wave H18jnα, and the 12th B
The solid line in the figure indicates the 6-arrow harmonic a58if13α.

Here, for the pattern of elements (A) (B,), the machine Va
2= al sin (α-60°) + a55in
3 (α−60°)...■. The dotted line in FIG. 12A is the fundamental wave a1Bin.

(α-60°), and the dotted line in FIG. 12B represents the 6-arrow harmonic a38in3 (α-60°). Therefore, if we perform the calculation of Vα1+Vα2 according to formula 0 above, we get v
c= Val +'Va2 = al (sin α+sin (α-60°)) 10a3 (5in5α+sin (3α-180°)) = Js, al 5tn (am 30') ---0
--'D, and the 6th harmonic can be canceled.

In order to realize a rotation detecting device to which the above-described principle is applied, a magnetically sensitive element that can obtain the output voltage Vα2 and whose element patterns are shifted by 60 degrees in mechanical angle is used. In the case of FIG. 11, two magnetically sensitive elements are required, one on the sea side and one on the opposite side. In that case, a second detector having the same pattern as the detector aω in FIG. 10 is prepared, and this second detector is stacked on the first first detector (I5). The eight patterns constituting the second detector may be laminated so as to be shifted by 60° from the patterns of the eight elements (A1) to (B2) constituting the detector αω. Alternatively, on the same substrate (toward) as the first detector α9, eight elements of the second detector shifted by 30 degrees are placed as elements (A1) to (B2).
It may also be formed by being placed between the two. .

Figure 16 shows the first detector α9 and the second detector 0υ.
An embodiment of a rotation detection device that cancels the sixth harmonic using the following will be described. 11. Portions corresponding to those in FIG. 11 are designated by the same reference numerals.

On the i side, the elements (
AI) (A2) (B1) (B2) Bridge circuit and its elements (A1) (A2) (B1)
Elements (A11) of the second detector Gυ each having a pattern delayed by 60 degrees in mechanical angle with respect to the pattern in (B2)
(A22) (B11) (B22) A bridge circuit is provided. The power supply voltage X is applied from the power supply terminal (161c3a) to these two bridge circuits. The second detector 0
The output signal 611% eZ2 of the bridge circuit of υ is applied to the differential amplifier 09 from the output terminal 04)(e)).

The output signal of the differential amplifier C3119e1 is connected to the adder circuit (
421 is added. As this addition output, an output signal e01 in which the sixth harmonic is canceled can be obtained.

After processing such as wa i is performed, addition -(46) i is added. ' □ ゛On the fourth side, the first prosecutor α51tl - the constituent elements' (01) (02) (DI> The bridge circuit by (B2) and these electrons (01) (02) '
(Dl) and (B2) are respectively 60°' in mechanical angle! The element (011) (C!22) (Dll) (B22
) is provided. These two bridge circuits have power terminals a! 7) Power supply voltage y is applied from C35). ``Bridge low output'' of the first detector Q51.

Voltage "65%" e4 is applied from output terminal (2I) (221 to differential amplifier (4α9).

It is made so that it can be done. The output signals e55 and C44 of the bridge circuit of the second detector Gυ are output terminals (to)
It is configured to be added to the differential amplifier (4υ) from the OD. The output signals of the differential amplifier (41) are added in the adder circuit (c). The third harmonic is canceled as the added output. An output signal e02 can be obtained. This signal e02 is subjected to processing such as level matching in a signal processing circuit (49), and then added to an adder (46) where it is added to the signal eoi. A rotation detection signal (■) can be obtained as this addition output.

The case where the sixth harmonic is canceled has been described above, but next, the case where the second harmonic is canceled simultaneously with the sixth harmonic will be described. □In this case, the first detector (19) and the sixth and fourth detectors having patterns shifted by 45° and 75°, respectively, with respect to the pattern of each element of the detector α9 of the first detector A detector is used.First:
~ Assuming the output voltage of the fourth detector as ■α1 to ■α4, 2
Expressed including the next and 6th harmonics, V+a1= a1sinα +a28in2α +a5
Bin3αVa2 = alsin (α-60°)
10a2stn2 (α-60°) + a′53in3
(α-60 Va5 = al sin (α-90°
)+a28in(α-90°)+a6!1in3
(α-90°) Va4= a38m (α-150')
+ a2 sin (α-150°) + a38in
3 (α-150°) Adding these together, v0 = ■α1 + Vα2 + Va3 + ■α4”
” to −al sin (α−30°) +a2Bi
n2 (α-60°) + phantom' ai stn ((α-
60°)-90°)+a2sin2 ((α-30°)
-90°) = q7・a18Ln(α-75°), and the 14th harmonic cancels the 2nd and 6th harmonics.
Figures A and 1'4B are waveform diagrams showing that the 12th and 6th harmonics are canceled.

Figure '+4A, Oi 7, (V(11' 7)-, Va2
') and (Vas + ■α4), the third harmonic is internally canceled in the same manner as in FIG. 12A. This, =t, (vα1 + V(22) and (Vas +
The waveforms of Va4) have a phase difference of 90°, and their second harmonics have opposite phases to each other as shown in FIG. 14B.

Therefore, by adding these together, the second harmonic is canceled.

Effects of the Invention Harmonic distortion contained in the rotation starting signal can be effectively removed. Therefore, a magnetically sensitive element can be used in a saturated magnetic field and can be omitted, making it possible to use a small magnet.

4. Brief explanation of the drawings ゛Figure 1 is a plan view showing the structure of the magnetically sensitive element used in the present invention, Figure 2 is a theoretical equivalent circuit diagram, Figure 6 is an output voltage waveform diagram, Figure 4 is an equivalent circuit diagram, Fig. 5 is a diagram explaining the principle of detecting magnetic signals using a magnetically sensitive element, and Fig. 6 is an equivalent circuit diagram.
The figure shows an example of the detection circuit, Figure 7 is a schematic plan view of a magnetically sensitive element with a bridge configuration, Figure 8 is a side view of the principle of a rotation detector, and Figure 9 is a diagram showing the principle of a rotation detector. 8 is a plan view, FIG. 1b is a plan view showing an embodiment of the rotation detector used in the present invention, FIG. 11 is an isometric circuit diagram of the rotation detector,
12A and 12B are waveform diagrams for explaining the cancellation of the 6th harmonic, 1'3 are block diagrams showing an embodiment of the present invention, and 14A and 14B are 2 FIG. 7 is a waveform diagram for explaining canceling the next harmonic.

In addition, the symbols used in the drawings are (2A) (2B)... Straight line part (II...
・・・・・・Magnetic element 1α9・・・・・・・・・
・・・First inspection, small instrument □(3υ・・・・・・・・・・
...Second detector' (France) (B)...It is a ferromagnetic element.

Agent: Masaru Saturn, Yoshio Tsune, Toshiki Sugiura, 1F'1 Figure 2 Figure 4 Figure 3A Mr. Commissioner of the Japan Patent Office 1. Indication of the case: Patent Application No. 248973/1983, 5, Date of amendment order (shipment date): Month, Day, 6, 1980;
The number of inventions will increase due to the amendment.
2β° in electrical angle.”

(2j1 same! Same page, lines 7-15 “■c=・・・・・・・・・
・・・・・・・・・It will be accomplished. ” is corrected as follows.

VoL = xiKgma + ytKcaaa However, -y2 is the coefficient determined by the partial voltage resistance ratio of x and y above, α
is the case where the detection signal ■c is expressed in electrical angles, and when expressed in mechanical angles, α=20 from the above equation 0.

As shown in FIGS. 8 and 9, since a two-pole Ic magnetized magnet (13) is used, the detection signal Vc changes only once per rotation of the rotation axis circle.

Therefore, when the rotation detection device is used as a frequency generator or the like, signals having several phase differences are generated by using several resistance ratios -/yi. Accuracy in this case depends on the resistance ratio, making it difficult to detect with high precision and high resolution. Therefore, in order to convert the position information into a phase difference and perform digital processing using pulses, an AC power source is used as the power source of the detector t151, and phase modulation is performed. ” +31, same ji page 112, line 3 “vc=va, +Va2
rva J.

==: Va, 10 ■ a2”.

(41, page 14, line 1, ``output signal e.1'' is corrected to ``output signal eo1 (equivalent to VαojC in the above [phase] formula)''.

- Above -

Claims (1)

[Claims] a first magnetically sensitive element made of a ferromagnetic material having a magnetoresistive effect and provided with a pair of current paths orthogonal to each other;
A second magnetically sensitive element is provided with a pair of current paths that are inclined at a predetermined angle with respect to the pair of current paths and are orthogonal to each other. A rotation detection device characterized in that the rotation detection device is arranged such that the outputs of the first and second magnetically sensitive elements are added.