JPH0140928B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rotation angle sensor that converts a rotation angle into an electrical signal. One of the conventional devices of this type includes a movable body that changes a rotational angle and a potentiometer that has a slider connected to the movable body. In this case, an analog voltage corresponding to the amount of angular displacement of the movable body is obtained from a potentiometer. In this rotation angle sensor, it is desired that the thin film resistor of the potentiometer has high wear resistance and that the output voltage level with respect to the slider position is stable. It is desired that the contact between the slider and the thin film resistor be sufficiently stable with little play and even against vibrations and shocks. However, since the slider and thin film resistor in the potentiometer are connected by pressure contact, wear, vibration, etc. will eventually produce an unstable output voltage with respect to the rotation angle. Further, one of the conventional sensors includes a sensor including a magnetic core, a winding wound around the magnetic core, and an oscillation circuit using the winding as a part. This type of sensor is known, for example, from Japanese Utility Model Publication No. 3018/1983, which discloses a device for detecting the rotational position of a rotor,
They are disclosed in Japanese Patent Publication No. 65275, Japanese Patent Publication No. 43-9793 which discloses a position and movement measuring device, and Japanese Utility Model Publication No. 54-56990 which discloses a device that converts pressure into positional displacement. These sensors convert displacement into frequency by using the fact that the oscillation frequency of an oscillation circuit changes due to changes in the external magnetic field applied to the magnetic core. Sensors that utilize such frequency changes are
Since the detection result is output as a frequency, a frequency measuring device is required. In addition, at least 1/2 period from the starting point of oscillation (the point of transition from the H level to the L level or from the L level to the H level) is required for measurement to output the detection result. Therefore, at the start of measurement, there is a delay between the starting point and the starting point of oscillation. Furthermore, one of the conventional sensors is a sensor that converts a change in position into a change in magnetic field, and converts the change in magnetic field into a voltage using a coil. This kind of sensor is
Japanese Unexamined Patent Publication No. 52-21875 discloses a device that converts external pressure into a change in magnetic flux using a magnetostrictive element, Utility Model Registration No. 353311 discloses a device that detects temperature using displacement of a bimetal. 48−20481
This is disclosed in Japanese Patent Publication No. 46-23674, which discloses a device in which a magnet is displaced in accordance with pressure. A sensor that converts such a change in a magnetic field into a voltage outputs a voltage value, so it is vulnerable to electrical noise and has a large error. A first object of the present invention is to provide a rotation angle sensor equipped with a non-contact conversion means that does not have a mechanical contact mechanism in a mechanical-electrical conversion system that converts mechanical displacement into an electrical signal. A second object of the present invention is to provide a robust rotation angle sensor with high vibration resistance and impact resistance. A third object of the present invention is to provide a rotation angle sensor in which electrical processing of a rotation angle detection signal is relatively simple. A fourth object of the present invention is to provide a rotation angle sensor that can read rotation angle data using relatively simple reading logic in an LSI such as a microcomputer, which has recently made remarkable progress. According to the present invention, a soft magnetic body around which an electric coil is wound is fixedly disposed inside a casing that rotatably supports a movable body, and a permanent magnet is located near the soft magnetic body. placed and fixed to a movable body. In one embodiment, the soft magnetic body and the permanent magnet are arranged so as to intersect the rotational axis of the movable body so that the soft magnetic body and the permanent magnet rotate relative to each other due to rotational angular displacement of the movable body. In one or more other embodiments, the soft magnetic body and the permanent magnet are arranged in an eccentric relationship with respect to the movable body such that rotational angular displacement of the movable body causes the soft magnetic body and the permanent magnet to approach and separate from each other. The cross-sectional area of the soft magnetic material is small enough to easily cause magnetic saturation, and the number of turns of the electric coil is sufficient to cause the soft magnetic material to magnetically saturate at a relatively low applied voltage, i.e., at a relatively low current level. The permanent magnet has a large number of windings, and the permanent magnet is small enough to apply a magnetic field of strength corresponding to the amount of movement to the soft magnetic material within its planned movement range. A voltage is applied to a coil wound around a soft magnetic material, and if T is the time from the starting point of voltage application until the soft magnetic material becomes magnetically saturated, roughly, T=N/E・(φm−φx) …( 1) becomes. However, E: voltage applied to the electric coil N: number of turns of the electric coil φm: maximum magnetic flux (≒ saturation magnetic flux) φx: magnetic flux due to external magnetic field. Therefore, when φx changes due to movement of the permanent magnet, T changes. In other words, the permanent magnet is displaced according to the rotation angle, and the external magnetic flux φx applied to the soft magnetic material changes accordingly, and the time T from when voltage is applied to the coil until the coil current reaches a predetermined level changes. Change. Therefore, the rotation angle sensor of the present invention is connected to an electric circuit or a semiconductor electronic device that measures T and represents it as an electric signal such as a voltage level or a digital code. In a preferred embodiment of the invention, the soft magnetic material is an amorphous magnetic material. Amorphous magnetic materials have to be made by rapidly cooling liquid-phase metals, so they are thin plates.Moreover, they are magnetically ferromagnetic, have high permeability and saturation magnetization, have low coercive force, and are mechanically has extremely high breaking strength and excellent elasticity and restorability. These characteristics of the amorphous magnetic material are extremely advantageous for the rotation angle sensor of the present invention, and its use has the advantage of simplifying and highly accurate signal processing when measuring T electrically, while mechanically This simplifies manufacturing and improves vibration and impact resistance. Other objects and features of the present invention will become clearer in the following description of embodiments with reference to the drawings. In one embodiment shown in FIGS. 1a and 1b, a casing 2 of a rotation angle sensor 1 is made up of a cup-shaped member 3 made of a non-magnetic material such as resin and a lid member 4, which are joined together by a connector 5. An annular sealing material 6 is interposed at the joint between the cup-shaped member 3 and the lid member 4, and water and dust from the outside are passed from the joint to the casing 2.
It's designed to prevent it from getting inside. A boss portion 7 is provided at the center of the outer surface of the lid member 4, and a stepped through hole 8 concentric with the boss portion 7 is provided in the lid member 4. An input shaft member 10 of the movable body 9 is fitted into and bearing the stepped through hole 8 . The movable body 9 includes an input shaft member 10 and a machine screw 1 at the inner end of the shaft member 10.
1, and a permanent magnet holding member 12 fixed thereto. The input shaft member 10, the permanent shaft member 10, and the permanent magnet holding member 12 are all made of non-magnetic material, and the movement of the movable body 9 inward of the casing with respect to the lid member 4 is controlled by the outer circumferential step 13 of the shaft portion 10. The outward movement of the casing is regulated by a permanent magnet holding member 12, respectively. An annular seal member 14 is disposed around the outer periphery of the shaft portion 10 to prevent external water and dust from entering into the casing through the outer peripheral gap of the shaft portion 10. The permanent magnet holding member 12 of the movable body 9 holds the permanent magnet 15 fixedly. On the other hand, a pair of terminal plates 16 and 17 made of conductive and non-magnetic material are provided on the inner wall of the cup-shaped member 3.
are fixed by machine screws 18 and 19, respectively. The terminal plates 16 and 17 fixedly support a non-magnetic bobbin 20 disposed between them. In the center hole of the bobbin 20, there is arranged an elongated soft magnetic body 21 and an insulating material 22 that fixes the soft magnetic body 21 in the hole and electrically insulates it from the terminal plates 16 and 17. An electric coil 23 is wound around the outer periphery of the bobbin 20, and one end and the other end of the coil 23 are electrically connected to terminal plates 16 and 17, respectively. Terminal plate 1
Lead wires 24, 2 electrically connected to 6, 17
5 extends out of the casing 2 through a sealing material 27 fitted into the hole 26 of the cup-shaped member 3 in a liquid-tight manner. A small screw 2 is attached to the inner wall of the cup-shaped member 3.
The holder 30 fixed by 8 and 29 serves both to prevent the sealing material 27 from coming off and to maintain the posture of the lead wires 24 and 25. As shown in FIGS. 1a and 1b, the permanent magnet 15 is arranged so that the straight line connecting its two poles is orthogonal to the rotation axis of the movable member 9, and the soft magnetic body 21 around which the electric coil 23 is wound is connected to the coil 23.
The movable member 9 is arranged such that its axis is orthogonal to the rotational axis of the movable member 9. When a rotational angular displacement is transmitted from an object to be detected (not shown) to the input shaft member 10 of the movable body 9, the rotational angular displacement of the movable body 9 causes the permanent magnet 15 to undergo a rotational angular displacement with respect to the soft magnetic body 21. This displacement position of the permanent magnet 15 is detected by an electrical processing circuit or logic processing electronics. FIG. 2a shows one electrical processing circuit 100. FIG.
A constant level DC voltage (for example, +5V) is applied to a constant voltage power supply terminal 101 of the circuit 100.
A voltage pulse of, for example, 5 to 25 KHz is applied to the input terminal 102, and the NPN transistor 103 is conductive during the positive voltage section of the voltage pulse, and is non-conductive during the ground level. The PNP transistor 104 is on while the transistor 103 is on, and is off while the transistor 103 is off. Therefore, the electric coil 23 has an input terminal 1
A constant voltage (Vcc) is applied to the positive level section of the voltage pulse applied to 02, and no voltage is applied to the ground level section. A voltage proportional to the current flowing through the coil 23 appears at the resistor 105, this voltage is integrated by an integrating circuit consisting of a resistor 106 and a capacitor 107, and an integrated voltage appears at the output terminal 108. Figure 2b shows the input and output voltage waveforms of the circuit shown in Figure 2a. The time td from when the input voltage (IN) rises to a positive level until the voltage across the resistor 105 rises above a certain level and the integrated voltage Vx of the voltage a across the resistor 105 correspond to the position of the magnet 15. FIG. 3a shows another electrical processing circuit 120. FIG. While the input voltage (IN) is at a positive level, NPN transistor 103 is on, PNP transistor 1
04 is turned on, and a voltage is applied to the coil 23. Transistor 103 is off while the input voltage (IN) is at ground level, PNP transistor 104
is turned off, and no voltage is applied to the coil 23. The coil current flows through junction type N-channel FET1 and FET2 which are connected with constant current, and is controlled to a constant level current value by FET1 and FET2.
The level of current flowing through FET2 is determined by variable resistor 122
is set. The voltage at the coil terminals connected to FET1 and FET2 is connected to the inverting amplifier IN1 and
Amplified and waveform shaped at IN2. Figure 3b shows the input and output voltage waveforms of the circuit shown in Figure 3a.
The output (OUT) of the circuit 120 is a voltage pulse that rises with a delay of td from the input pulse (IN), and this corresponds to the position of the magnet 15. td is represented by a digital code in a counting circuit 140 shown in FIG. In circuit 140, the input voltage (IN)
At the rising edge of , the flip-flop F1 is set and its Q output becomes high level "1", and the AND gate A1 is opened (on) and the pulse generated by the clock pulse oscillator 141 is applied to the count pulse input terminal CK of the counter 142. Ru. Output pulse (OUT) and Q output of F1 are AND gate A
When the output pulse (OUT) rises, the AND gate A2 rises to a high level "1", and at the rising point, the flip-flop F1 is reset and its Q output becomes a low level "0". As a result, AND gate A1 becomes gate closed (off),
The clock pulse to counter 142 is cut off. When the output of AND gate A2 becomes "1", the count code of counter 142 is loaded into latch 143. After flip-flop F1 is reset and the count code is loaded into latch 143, AND gate A3 outputs a clock pulse to clear counter 142. The output code of latch 143 indicates the number of clock pulses generated during td, and this code indicates td. The electronic processing unit 160 shown in FIG. 5 includes a one-chip microcomputer (large-scale integrated semiconductor device) 161, an amplifier 162, a junction type N-channel FET 1 for constant current control, a resistor 163, a capacitor 164, an amplifier 165, and a clock pulse oscillator 166. Consists of. The resistor 163 and the capacitor 164 constitute a filter that absorbs voltage vibrations at frequencies higher than the input and output pulse frequencies. The microcomputer 161 forms a pulse with a constant frequency within the range of 5 KHz to 30 KHz based on the clock pulse and supplies it to the amplifier 162.
On the other hand, the microcomputer 161 monitors the voltage at the connection point between the N-channel FET 1 and one end of the coil 23 (output voltage of the amplifier 165), and monitors the voltage from the rising point of the pulse outputted by itself to the rising point of the output voltage of the amplifier 165. (td) and outputs a code indicating td (DATA OUT). As described above, various electric processing circuits and logic processing electronic devices are connected to the rotation angle sensor 1 shown in FIGS. 1a and 1b, so that the rotation angle sensor 1 shown in FIGS. I can get a signal. Next, the rotation angle sensor 1 shown in FIGS. 1a and 1b and the above-mentioned electric processing circuit 10
0,120,140 or logic processing electronics 160
It will be explained that an electrical signal can be obtained according to the rotation angle. First, the rotation angle is converted into the position of the permanent magnet 15 by the movable body 9 of the field rotation angle sensor 1 . Next, the point in which the position of the permanent magnet 15 is converted into an electric signal will be explained with reference to experimental data shown in FIGS. 6b and 6c. As shown in FIG. 6a, the inventor fixes the soft magnetic body 21, maintains the permanent magnet 15 parallel to it, and passes through the center of the soft magnetic body 21 and the permanent magnet 15, perpendicular to their long axes. The long axis of the permanent magnet 15 is taken as the axis X-X.
Y'-Y' and the long axis Y-Y of the soft magnetic body 21 are X-X
V〓 and td with respect to the rotation angle θ of the permanent magnet 15 around the X-X line were measured using the point where the polarity of the permanent magnet 15 overlaps in the line direction and the polarity of the coil 23 is the same as the polarity due to the current of the coil 23 as the origin. The correspondence between the dimensions a to f indicating the shape and placement position, the material of the soft magnetic material, and the measurement data is shown in the case number in the table below.
1 and 2.

[Table] In the voltage application mode, the coil 23 is set so that the upper end of the soft magnetic body 21 becomes the north pole in Fig. 6a.
indicates that the coil 22 is connected to the electric circuit 100 or 120, and S-N indicates that the coil 22 is connected to the electric circuit 100 or 120 so that the upper end of the soft magnetic body becomes the S pole. θ is 0 to 90
It becomes N-N at 270 to 360, and θ is 90 to 270.
At this point, it becomes S-N. In case No. 1, from the data shown in Figure 6b, the voltage has high proportional accuracy to the permanent magnet rotation angle θ in the range θ of 100 to 170 and the range of 190 to 260.
V〓 is obtained. Also, from the data of case No. 2,
When θ is in the range of 30 to 70 and in the range of 100 to 140, a delay time td with high proportional accuracy to θ can be obtained. 1st a
In the sensor 1 shown in FIG. 1B, the operating range of the magnet 15 is determined within a range in which the proportional accuracy of the voltage V or the delay time td with respect to θ is high. In the rotation angle sensor 1 of the present invention shown in FIGS. 7a to 7c, the casing 2 is formed by ultrasonically welding a cup-shaped member 3 and a lid member 4 made of resin. The movable body 9 made of a non-magnetic material integrally includes an input shaft portion 10 supported by the lid member 4 and a permanent magnet housing cylinder portion 12 located inside the casing 2. A retaining ring 13 is mounted on the input shaft portion 10 to restrict axial movement of the movable body 9 with respect to the lid member 4. The permanent magnet housing cylindrical portion 12 is in an eccentric position relative to the rotation center of the movable body 9, and the opening of the cylindrical portion 12 is closed with a filler 31 after the permanent magnet 15 is inserted. The permanent magnet 15 is arranged so that a straight line connecting its two poles is parallel to the rotational axis of the movable body 9. On the other hand, the cup-shaped member 3 of the casing 2 has a pair of soft magnetic material housing cylinder parts 32 that protrude into the casing 2,
33 are provided. These cylindrical parts 32, 33
are spaced apart from the rotation center of the movable body 9 by the same distance as the eccentricity of the cylindrical portion 12 of the movable body 9, and are spaced apart from each other in the rotational direction of the movable body 9. Cylindrical parts 32 and 3
Inside 3 are soft magnetic bodies 21 and 35 around which coils 23 and 34 are wound, and fillers 36 and 3 for fixing them.
7 are arranged respectively. The soft magnetic body 21 is arranged so that the axis of the coil 23 is parallel to the rotational axis of the movable body 9. This rotation angle sensor 1
Now, due to the rotational angular displacement of the movable body 9, the permanent magnet 15
It rotates between the pair of soft magnetic bodies 21, approaches one soft magnetic body 21, and moves away from the other soft magnetic body 21 at the same time. A pair of soft magnetic bodies 21
The movement of the permanent magnet 15 is shown in FIGS. 8a and 8b.
Detected by the electrical processing circuitry 180, 200 of the figure and the logic processing electronics 220 of FIG. 8c. The electrical processing circuit 180 shown in FIG.
An analog voltage V is generated corresponding to the position of the permanent magnet 15 in the rotation angle sensor 1 shown in FIGS. In the circuit 180, during the positive level of the input voltage pulse (IN), the NPN transistor 1
03 is on, and 103 is off while it is at ground level. The collector voltage of transistor 103 is amplified and waveform-shaped through two inverting amplifiers IN3 and IN4, and then applied to the base of NPN transistor 121. Hence the input voltage pulse (IN)
The transistor 103 is on while the positive level of
121 is off, PNP transistor 104 is off,
Transistor 103 is off during ground level, 1
21 is on and the transistor 104 is off.
In other words, a pulsed voltage is applied to the coil 23 in an operation similar to that of the circuit 120 in FIG. 3a.
The resistor 105 has a delay of td ₁ from the falling edge of the input voltage pulse (IN) corresponding to the distance X ₁ = f ₍ 〓 ₎ of the permanent magnet 15 from the soft magnetic material 21 . A rising voltage pulse appears.
A constant voltage is applied to the other electric coil 34 via a PNP transistor 181. This transistor 181 is on while the input voltage pulse (IN) is at a positive level because the transistor 103 is on and the output of the inverting amplifier IN5 is at a positive level and the NPN transistor 182 is on.
Transistor 181 is off while the input voltage pulse (IN) is at ground level. This allows the second
A constant voltage is applied to the electric coil 34 while no voltage is applied to the first electric coil 23, and no voltage is applied while electricity is applied to the coil 23. That is, the input voltage pulse (IN)
A constant voltage is alternately applied to the first and second coils 23 and 34 in accordance with the above. A resistor 183 is connected to the second electric coil 34, and a distance from the soft magnetic body 35 of the permanent magnet 15 is connected to this resistor.
A voltage pulse appears that corresponds to X ₂ = f ₍ 〓 ₎ and rises with a delay of td ₂ from the rise of the input voltage pulse (IN).
Voltage Vx ₁ of resistor 105 is applied to one electrode of capacitor 184, and voltage Vx ₂ of resistor 183 is applied to the other electrode of capacitor 184. Permanent magnet 1
5 and the first and second soft magnetic bodies 21 and 34 are x ₁ and x ₂ , respectively, and x ₁ + x ₂ = K
(constant), so also Vx ₁ ∝x ₁ and Vx ₂
Since ∝x ₂ , the potential difference across the capacitor 184 corresponds to x ₁ −x ₂ . Since the capacitor 184 and the resistor 185 constitute an integrating circuit, the voltage of the capacitor 184 corresponds to x ₁ -x ₂ . here
Since x ₂ =K-x ₁ , x ₁ -x ₂ =2x ₁ +K, and the voltage on capacitor 184 corresponds to 2x ₁ . In other words,
Permanent magnet 15 based on the first soft magnetic body 21
An analog voltage corresponding to twice the amount of movement x ₁ is obtained. The voltage across capacitor 184 is applied to operational amplifier 186 in a differential amplification setting. The analog output V of amplifier 186 thus corresponds to _2x1 . Electrical processing circuit 200 shown in FIG. 8b
In each of the two circuits 120, pulses delayed by td ₁ and td ₂ from the rising edge of the input pulse are obtained,
These are applied to each of the two counting circuits 140 and generate codes S21 and S indicating td ₁ and td ₂ .
34 and applied to the subtracter 201. The subtracter 201 subtracts td ₁ -td ₂ using S21 and S34, and outputs a digital code Sx=S18-S29 representing td ₁ -td ₂ , that is, _2x1 . 8th c
In the logic processing electronic device 220 shown in the figure, a one-chip microcomputer 221 first applies one pulse to the circuit 120 connected to the electric coil 23, starts counting time from the rising edge of the pulse, and calculates td _1.
Count data S21 is created and held, then one pulse is given to the circuit 120 connected to the electric coil 34, and time counting is started from the rising edge of the pulse.
Create td ₂ count data S34, calculate td ₁ - td ₂ , and show the code Sx = S21 - S34
This continues while the measurement command signal is being given. As shown in FIG. 9a, the inventor fixed the soft magnetic bodies 21 and 35 parallel to each other on a single circular arc, and fixed the permanent magnet 15 on the circular arc between the soft magnetic bodies 21 and 35. When the permanent magnet 15 is placed in parallel with the soft magnetic body and is located between the soft magnetic bodies 21 and 35, it is assumed that the rotation angle around the rotation center O is zero, and V and V with respect to the rotation angle θ of the permanent magnet 15 are
td was measured. The relationship between the shape and dimensions a to e, r, θ ₀ and the material of the soft magnetic body and the measurement data is shown in the following table.

[Table] From Cases No. 3 and No. 4, voltage V and delay time td with high proportional accuracy to θ can be obtained in the range of θ from −15 to +15. θ−V〓characteristics and θ−td
The characteristics are affected by the strength of the magnetic field that the permanent magnet 15 exerts on the soft magnetic bodies 21 and 35, and these characteristics can be changed as appropriate by changing θ ₀ , r, the strength of the magnetic field generated by the magnet 15, etc. It is possible. The sensor 1 of the invention shown in FIGS. 10a and 10b is the sensor 1 shown in FIGS. 7a to 7c.
One soft magnetic material is removed from the second a.
It is used in combination with the circuit 100 shown in the figure, the circuit 120 shown in FIG. 3a, and the device 140 shown in FIG. In the embodiment described above, the soft magnetic body 21
and 35 are made by stacking several sheets of amorphous magnetic material that has high magnetic permeability, high elasticity, and is difficult to deform, but in the present invention, Miu Metal (Ni
−Fe−Mo alloy) and super permalloy (Ni−
Other soft magnetic materials such as Fe alloy) can be used. As can be understood from the explanations with reference to several embodiments and experimental data, the rotation angle sensor of the present invention does not have a sliding contact, and detects the rotation angle displacement of the movable body by input pulses of the electric coil and input pulses of the electric coil. Since the rotation angle displacement detection signal is obtained by electrical processing of converting the time difference TD between the current pulses and obtaining TD using an analog voltage or time count code, it has high vibration resistance and is resistant to deterioration such as mechanical wear. few. Since there is no coupling mechanism between the movable body and the transducer, the rotation angle can be detected stably without any backlash. What is noteworthy is that the configuration of the electrical processing circuit connected to the sensor is simple.In particular, a large-scale semiconductor device such as a one-chip microcomputer is used to create a rotation angle detection pulse and use that pulse to energize the electric coil. This means that the time difference between the current detection pulses can be easily obtained using a digital code.

[Brief explanation of drawings]

FIG. 1a is a vertical cross-sectional view of one embodiment of the rotation angle sensor according to the present invention, and FIG. 1b is a line A-A in FIG. 1a.
A cross-sectional view along the line, Figure 2a is the same as Figures 1a and 1b.
2b is a circuit diagram connected to the rotation angle sensor 1 shown in the figure and generates an analog voltage of a corresponding level for detection, and FIG. 2b is an electric processing circuit 10 shown in FIG. 2a.
Waveform diagram showing input and output signals of 0, Figure 3a is the first
FIG. 3B is a circuit diagram showing the electrical processing circuit 120 connected to the rotation angle sensor 1 shown in FIG. , a waveform diagram showing the output signals, FIG. 4 is a block diagram of the counting circuit 140 that converts the input and output pulse time difference td of the electrical processing circuit 120 shown in FIG. 3a into a digital code, and FIG. An electronic processing unit 16 is connected to the rotation angle sensor shown in FIG. 1b and counts the delay time of the rise of the current flowing through the electric coil with respect to the pulse voltage applied to the electric coil of the rotation angle sensor 1 using a one-chip microcomputer.
Figure 6a is a perspective view showing the relative positional relationship between the soft magnetic body 21 and the permanent magnet 15 when the pulse time difference td corresponding to the rotational position of the permanent magnet 15 with respect to the soft magnetic body 21 was determined by experiment. Figure, 6th
In Figure b, the permanent magnet 15 is rotated around the X-X line in the arrangement shown in Figure 6a, and the electric processing circuit shown in Figure 2a is connected to the electric coil 23, so that the rotation angle θ of the permanent magnet 15 is adjusted. A graph showing the measured data of the time difference td display voltage V〓, Figure 6c is Figure 6a
The permanent magnet 15 is rotated around the X-X line in the arrangement shown in the figure, the electrical processing circuit 120 shown in Fig. 3a is connected to the electric coil 23, and its input and output pulse waveforms are observed with a synchroscope. A graph showing data obtained by measuring the time difference td between the two, Fig. 7a is a vertical cross-sectional view of another embodiment of the rotation angle sensor according to the present invention, and Fig. 7b is a graph taken along line BB in Fig. 7a. 7c is a sectional view taken along line C-C in FIG. 7b, and FIG. 8a is a sectional view taken along line C-C in FIG. 7b. FIG. 8b is a circuit diagram showing an electrical processing circuit 180 that generates an analog voltage of FIG.
FIG. 8c is a block diagram showing the configuration of an electric processing circuit 200 connected to the rotation angle sensor 1 shown in FIG.
A block diagram showing the configuration of a logic processing electronic device 220 connected to the rotation angle sensor 1 shown in FIGS. a to 7c and generating a digital code corresponding to the detected angle;
FIG. 9a shows each electric coil 23, 3 corresponding to the rotational position of the permanent magnet 15 with respect to the soft magnetic bodies 21, 34.
FIG. 9b is a perspective view showing the relative positional relationship between the soft magnetic bodies 21 and 34 and the permanent magnet 15 when the difference in delay time of No. 5 was experimentally determined. The coils 23 and 35 are connected to the electrical processing circuit 18 shown in FIG. 8a.
Figure 9c is a graph showing data obtained by measuring the time difference td display voltage V〓 with respect to the rotation angle θ of the permanent magnet 15 when the permanent magnet 15 is rotated around the center O with the arrangement shown in Figure 9a. coil 2
3 and 25, an electrical processing circuit 200 shown in FIG. 8b.
Figure 10a is a graph showing data obtained by connecting the input and output pulse waveforms with a synchroscope and measuring the time difference td between the two, which shows a further embodiment of the rotation angle sensor according to the present invention. longitudinal section,
FIG. 10b is a sectional view taken along line DD in FIG. 10a. 2... Casing, 9... Movable body, 15... Permanent magnet, 21... Soft magnetic material, 23... Electric coil.

Claims (1)

[Claims] 1. A casing, a movable body rotatably supported by the casing and to which a rotational angular displacement is input from the outside, a permanent magnet fixed to the movable body within the casing, and a vicinity of the moving range of the permanent magnet. soft magnetic core means disposed along the magnetic field lines of the permanent magnet; electric coil means wound around the soft magnetic core means; voltage generating means; A rotation angle sensor comprising: a voltage switching means for applying to the electric coil; and a current detecting means for detecting a current flowing through the electric coil means, and the output value is the time from an instruction to saturation of the current measured by the current detecting means.