JPS6298215A - Displacement detector - Google Patents

Abstract

PURPOSE:To obtain a small-sized detector capable of detecting with a highly precise absolute value even under the adverse environment by changing the magnetic flux in accordance with the changing position of an object to be measured and finding the intrinsic code signals from magnetic sensors on the position. CONSTITUTION:A rotation bearing 2 holds a rotation axis 3 interlocking with rotation of the object to be measured and a round bar 4 is connected with an end of the rotation axis 3. The tip of the round bar 4 can be rotated while sliding on an opening part of the center of a disk 5. Then, magnetized annular magnets 6 are mounted on the top of the disk 5 so that the counter poles are made with the upper and lower parts and a semiconductor chip 7 is arranged in contact with the magnets in a state that the rotation axis 3 is put through the opening part of a central part. Further, many magnetic sensors 8 consisting of magnetic resistance elements are arranged at the prescribed equal intervals along the magnets 6 in the neighborhood of the outside periphery of the chip 7. Then, a needle 10 of magnetic substance is fixed on the round bar 4 vertically to the axis center on the rotation axis 3 and its tip part is circulated above the sensors 8 in accordance with the rotation of the rotation axis 3. Then, when the needle 10 opposes a sensor 8, the magnetic flux is increased and the intrinsic code signals of the sensors 8 are found from this.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a displacement detection device for detecting a rotational or linear displacement position of an object to be measured.

[Technical background of the invention and its problems]

Conventionally, for example, in a rotary encoder which is a part of a displacement detection device, as shown in Fig. 6, a digital pattern consisting of slits or openings shown as scratches in the figure is formed at different radial positions at each predetermined central angle. In case 6, a disc-shaped code plate 604 having a
01 is coaxially attached to the rotating shaft 600 held by a bearing 602, and the detecting W503 irradiates light from one side of the code plate 604 toward the digital button with a light source and detects the transmitted light with an optical sensor. The absolute value indicating the rotation angle of is obtained as a coded digital signal.

In such a rotary encoder, in order to improve the resolution of the detected rotation angle, it is necessary to increase the number of digits of the digital button, which causes the diameter of the code plate 604 to increase, making the device larger and more expensive. There is.

Furthermore, if the number of digits is increased by arranging the digital pattern finely in the radial direction on the code plate 604,
In the detection unit 603, the light source and the optical sensor are required to have high precision.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide a compact displacement detection device that can detect displacement positions with highly accurate absolute values even under adverse environments. [Summary of the Invention] The present invention, which has been made to achieve the above object, provides a magnetic sensor that has a function of changing a state in response to changes in a plurality of magnetic fluxes arranged in a row at a predetermined interval. , a magnetic flux changing means that is movably arranged along the row of magnetic sensors and changes the magnetic flux according to the position of the object to be measured, and the magnetic sensor at the position where the magnetic flux is changed by the magnetic flux changing means. This displacement detection device is characterized by comprising displacement detection signal output means for converting a detection signal obtained from the magnetic sensor into a unique code signal corresponding to the position of the magnetic sensor and outputting a displacement detection signal.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

A first embodiment of the present invention shown in FIGS. 1 to 4 c.
The present invention is applied to a rotary encoder.

In this embodiment, the configuration is such that, as shown in FIG. 1, a rotary bearing 2 arranged at the center of the upper surface of a flat cylindrical case 1 indicated by a dashed line in the drawing is linked to the rotation of the object to be measured. The rotating shaft 3 is held so that its axis is perpendicular to the upper surface. A circular rod 4 made of a magnetic material and having approximately the same diameter as the rotating shaft 3 is coaxially connected to one end of the rotating shaft 3 held inside the case 1 by the rotating bearing 2.
The tip of the circular rod 4 is inserted into an opening with approximately the same diameter as the rotating shaft 3 formed in the center of a magnetic disk 5 placed inside the lower surface of the case 1, and can rotate while sliding. It looks like this.

On the upper surface side of the case 1 of the magnetic disc 5, there is a disc 5 whose outer diameter is approximately
A ring-shaped ring magnet 6 is mounted so that the disk 5 side and the rotary bearing 2 (11!l) are opposite poles, and the ring magnet 6 is narrowed. At a position facing the disk 5, a semiconductor chip 7 having a disk shape having approximately the same diameter as the disk 5 and in close contact with the annular magnet 6 is arranged with the rotating shaft 3 inserted through an opening formed in the center. Near the outer periphery of the semiconductor chip 7, on the surface of the surface in contact with the annular magnet 6, a large number of magnetoresistive elements, such as indium antimonide, whose states such as specific resistance change according to changes in magnetism, are installed. Magnetic sensors 8 are arranged at predetermined intervals along the same circumference along the annular magnet 6.Furthermore, a magnetic material is placed on the rotating shaft 3 so as to be perpendicular to the center of the circular magnet 6. needle 10
is fixed to a circular rod 4 made of a magnetic material, and one end of the needle 10 faces the magnetic sensor at a predetermined distance. That is, as the rotating shaft 3 rotates, the tip of the needle 10 rotates inside the case l above facing each magnetic sensor 8. As shown in FIG. 2, for example, when the tip of the needle 10 is located at a position facing above the magnetic sensor 208 as the rotating shaft 3 rotates, the magnetic sensor placed on the annular magnet 6 The magnetic flux passing through 208 increases compared to other magnetic sensors 8.

That is, along the route shown by the dashed-dotted line 201 in FIG.
The magnetic flux emitted from the annular magnet 6 passes through the needle 10 via the magnetic sensor 208, passes through the tip 4 of the rotating shaft 3, passes through the disk 5, and reaches the annular magnet 6.

Thus, the magnetic flux density of the magnetic field containing the magnetic sensor 208 increases due to the opposing needles 10, so that the resistance value of the magnetic sensor 208 changes. A change in the resistance value of each magnetic sensor 8 is detected by a conversion circuit (not shown) disposed on the semiconductor chip 7, and converted into a code unique to each magnetic sensor.

Next, referring to FIG. 3, a conversion circuit 30 that outputs a unique code signal to each magnetic sensor 8 whose resistance value has changed in response to a change in magnetic flux density will be explained.

A predetermined number of magnetic sensors 8 are arranged on the semiconductor chip 7 at equal intervals around the same circumference, and a set of four magnetic sensors 8 forms a bridge circuit. For example, in FIG. 3, each magnetic sensor 8-o, S-i
, S.2. -8-n-2, 5-n-1, 4 magnetic sensors S.4 out of S.n. S・5. S・6°S・7 forms a bridge circuit. Of the pair of terminals of each of these individual bridge circuits, one connection point of the magnetic sensor 8 is connected to the power supply Vcc, and the other connection point is short-circuited to the ground E. Two sets of magnetic sensors 8 in which two magnetic sensors 8 are connected in series between the power supply Vcc and the earth E constituting the bridge circuit have a connection point where each magnetic sensor 8 is connected in series. Separate first differential amplifier A
・I, A-2, A-3, -, A-n-1, A-n (
7) Connected to the input terminal. Further, the connection points are connected to the first differential amplifiers A.1. A.2. A
・3°...A-n-1, a second differential amplifier A.1°A-2, A.3. -A-n-1, A-n
is connected to the input terminal. Each of the first differential amplifiers A.1. A・2゜A・3. ..., A-n-1, A-n
The output is branched into two, and one is connected to NA via a diode.
The second differential amplifier B.1. which is input to the ND circuit 300 has one input shorted to ground. B.2. B-3,-・
・B-n-1° It is input to B-n and the polarity is inverted and output.

This second differential amplifier B.l, B.2. B.3.・・・
- The output signals of B-n-1 and B-n are input to the NAND circuit 300 via the diode 310.

Here, the number of NAND circuits 300 is the same as the number of magnetic sensors, and the two input terminals are connected to the first differential amplifiers A-1, A.2. A.3. -A-n-1.

The output signal of A-n and the second differential amplifier B.1. B.2,
The output signals of B-3, . . . A-3, -A-n-
1, A-n output signal and each second differential amplifier B.1
．． B.2. B.3. . . , B-n-1, and B-n are all input to the NAND circuit 300 in different combinations. That is, as shown in FIG. 3, the arrows K.1, K.2. on the output line side from each diode 310.
K.3. - to -n-1, to -n and each NAND circuit 30
Arrow K・1. indicates the input terminal on the 0 side. K・2゜K・3.
・, ni-n-1, ni-n are connected by arrows with the same number written in the drawing.'-I R
, 2k', 3 k'-6-1k', 7'1 each resistance Aya + 4 + mountain, μ, ..., Cape Shose 2 songs broom and 4 so\old η-
'+' The derivation line of the sign signal is connected to the connection point with E, forming a NOT circuit.9. .

A code signal is output via , . In this embodiment, as shown in FIG. 3, each NAND circuit 300 and each resistor R.1. R・2. R・3. ..., R・n-1,
R-n means each magnetic sensor 8-0.8. l.

S・2. ..., each NOT with a code signal indicating a binary alternating signal assigned in order to 8-n-1, 8-n, respectively.
Circuit 22. .

It is connected through a diode 7 so that it is output from the terminal.

In addition, each NOT circuit 1 1 1 1,
are suddenly each digit of the binary alternating signal 2° 21 , respectively.
22,,,. 2n-1, 2n force compatible city. still,
The lines indicated by arrows P.1 and P.2 in FIG. 3 are connected. Moreover, the magnetic sensor 8 and the above-mentioned conversion circuit are
It is placed on the semiconductor chip 7 according to a normal manufacturing process for integrated circuits and the like.

In the conversion circuit 30 configured as described above, each magnetic sensor S.0. S・1゜S-2
, .

In addition, in FIG. 4, the tip of the needle 10 is connected to each magnetic sensor S.0.0 as the rotating shaft 3 rotates. S・1. S・2. ....

8-n-1, 8-n, each first differential amplifier A.l, A.2゜A.
3. . . . indicates the extreme pressure of the output from A-n-1 and A-n. In the figure - upward arrows indicate positive outputs and downward arrows indicate negative outputs.

First, as a first example, a case where the tip of the needle 10 faces the magnetic sensor S.2 due to rotation of the rotating shaft 3 will be described. At this time, the first differential amplifier A.1 provides a positive output, whereas the first differential amplifier A.2 provides a negative output. The positive output from the first differential amplifier A.1 is input via a diode 310 to a NAND circuit 300 having an input terminal indicated by an arrow Kl in FIG.

On the other hand, the negative output from the first differential amplifier A.2 is
The signal is inverted and outputted by the differential amplifier B.2, and is inputted as a positive output signal via a diode 310 to a NAND circuit 300 having an input terminal indicated by an arrow 4 in the figure. In the figure, the resistor 几・l and the resistor 几・2 connected to the NAND circuit 300 whose non-output signal became °°O'' at arrows 1 and 4 are 1.NAND circuit negative logic signal ``0++
is input, so an inverted positive logic signal 1 is output. Also, resistor R・1 and resistor →−−,・negative logic signal +
+ II+ is input, inverted and positive logic signal “O′”
Output.

Therefore, each NOT circuit 1. l j l
111)...00pa is output to l-, l-<μm+T→shi-n→→ox, respectively, and this negative signal is the two-signal alternating signal unique to magnetic sensor S・2. The code signal is shown as .

Next, as a second example, a case will be described in which the tip of the needle 10 faces the magnetic sensor 8-n.

At this time, the first differential amplifier A-n-1 provides a negative output, while the first differential amplifier A-n provides a positive output.

The output of the first differential amplifier A-n-1 is inverted by the second differential amplifier B-n-1 and passed through the diode 310 as a positive output signal to -n indicated by the arrow in FIG. The signal is input to a NAND circuit 300 having an input terminal indicated by -2. Of the NAND circuit 300 having an input terminal indicated by -n-1 at the arrow in FIG. 3, the positive output from the differential amplifier A-n is inputted via a diode. The output signal of the NAND circuit having the input terminal indicated by -n-2 is "0". As a result, the resistor 几・n is short-circuited to ground, and the other resistors R-1, R-2, R-3,
・-, R-n-1 is the first not short-circuited, and each NOT circuit N
・→T calculation "-N---3-, . . . outputs a - set of positive logic signals "ooo...01". This - set of positive logic signals "000...・01'' is a code signal that is a displacement detection signal unique to the magnetic sensor S.n.

In this way, to each NOT circuit -F-iN r
+ +, a set of 2 which is the code signal output from
Since the magnetic sensor whose resistance value has changed can be identified using an alternating signal, the position of the needle 10 that has changed the resistance value of the magnetic sensor, in other words, can be sequentially opposed to each magnetic sensor in conjunction with the rotation of the object to be measured. The position of the rotating hand 10 can also be specified at the same time. Therefore, according to the rotary encoder according to this embodiment, the rotation angle of the object to be measured can be accurately detected in absolute value from the output code signal. In addition, the rotary encoder of the same example does not have reading errors between the receiving and emitting elements unlike the 5'1 type rotary encoder, and also has the ability to significantly reduce the volume of the device compared to a rechargeable type with the same resolution, and malfunctions. It has excellent reliability, environmental resistance, impact resistance, and noise resistance, such as the fact that there is no need to cover the entire device with a highly airtight container in order to reliably block external light that causes noise.

Next, as shown in FIG. 5 as a second embodiment, the present invention can also be applied to a linear enhancer.

The main structure of the linear enhancer of this embodiment is a bar magnet 50 which has an elongated prismatic shape and is magnetized in a direction perpendicular to a plane in the longitudinal direction. A semiconductor chip 52 is in close contact with the surface of the bar magnet 50, and a semiconductor chip 52 has a large number of magnetic sensors 51 arranged in rows at equal intervals in the longitudinal direction, and the semiconductor chip 52 faces the plane of the bar-shaped magnet 50 in close contact with the semiconductor chip 52. A magnetic plate 53 having a difference on both sides in the longitudinal direction, which is joined to the surface in just the right amount.
The support body 55 is made of a magnetic material and supports the needle 54 made of a magnetic material at both ends, which contacts both sides of the plate 53 in the longitudinal direction and faces the magnetic sensor 51 sequentially. It consists of a movable slider and a conversion circuit (not shown) arranged on the semiconductor chip 52 that detects changes in the resistance value of each magnetic sensor 51 and outputs a unique code signal to each magnetic sensor 51. . In these configurations, when the needle 54 is opposed to a certain magnetic sensor 51 by the slider 56, the magnetic flux passing through that magnetic sensor 51 increases compared to other magnetic sensors 51.

A detection signal from the magnetic sensor 51 that detects this change in magnetic flux is converted into a unique code signal by a conversion circuit integrated on a semiconductor chip and outputted by each magnetic sensor 51. Therefore, the position of the slider equipped with the magnetic sensor 51 and needle 54 where the passing magnetic flux has changed can be specified from the output code signal. That is, the displacement of the object to be measured in conjunction with the slider can be determined from the output code signal. Note that the configuration of the conversion circuit used in this embodiment may be the same as that used in the first embodiment described above.

Note that the embodiments of the present invention are not limited to the contents described above, and various changes can be made within the scope of the technical idea of the present invention.

For example, the code signal present in each magnetic sensor is output from the NOT circuit as a binary alternating signal (gray code), and
By changing the connections between each NAND circuit and each resistor via diodes, it is possible to output in binary code, logarithmic output, etc.

Alternatively, the negative logic signal may be directly output without going through the NOT circuit. Furthermore, the magnetic sensor can also be formed with a Hall element.

Furthermore, in the above-mentioned embodiments, the permanent magnet used as the magnetic flux generation source is placed in a position in contact with the semiconductor chip on which the magnetic sensor is formed; Also, how to magnetize, especially the first
In an embodiment, the tip of the rotating shaft may also be magnetized to support the needle, and in a second embodiment, the support may also be magnetized to support the needle. In other words, if it is a means of changing the magnetic flux density of the magnetic field containing the magnetic sensors along the rows of each magnetic sensor, the structure of the main parts such as the needle and the support member that supports the needle may be changed as long as the original function is not impaired. Do not add unnecessary limitations.

[Brief explanation of drawings]

Figure 1 shows a first example in which the present invention is applied to a rotary encoder.
FIG. 2 is a cross-sectional view showing a main part of the embodiment with some parts cut away, and FIG. 3 is a conversion circuit formed on a semiconductor chip in the embodiment. 4 is an explanatory diagram showing the wedging of the output of a differential amplifier, FIG. 5 is a perspective view showing the configuration of a second embodiment in which the present invention is applied to a linear encoder, and FIG. 6 is a circuit diagram. FIG. 2 is a perspective view showing a conventional rotary encoder. 6...Circular magnet, 8...Magnetic sensor, 10...Needle agent Patent attorney Nori Ken Yudo Chika Kikuo Takehana Fig. 1 57 2θl Fig. 2 Fig. 4 In1 Fig. 5 Fig. 6 figure

Claims (1)

[Claims] A plurality of magnetic sensors arranged in a row at predetermined intervals have a function of changing the state according to changes in magnetic flux, and a magnetic sensor arranged movably along the row of magnetic sensors and capable of detecting changes in the object to be measured. A magnetic flux changing means for changing the magnetic flux according to the position, and a detection signal obtained from the magnetic sensor at the position where the magnetic flux is changed by the magnetic flux changing means is converted into a unique code signal corresponding to the position of the magnetic sensor. 1. A displacement detection device comprising: displacement detection signal output means for outputting a displacement detection signal.