JPS60220874A - Detecting device for vector magnetic field - Google Patents

Abstract

PURPOSE:To obtain the small-sized, high-resolution device which has high-speed responsibility and low-speed safety by converting the output current of a magnetic sensor into a voltage and feeding it back to the sensor. CONSTITUTION:The two-dimensional magnetic sensor 1 composed of transistors (TR) with plural collector pairs c1-c4 detects the magnetic field of a body to be detected in two dimensions, and differences between output currents of the respective pairs are detected by current mirror circuits 2A and 2B and supplied to inverted input terminals of current/voltage converters 3A and 3B. Then, a specific DC voltage is applied to uninverted input terminals of the converters 3A and 3B. Consequently, the input voltages are converted into DC voltages, which are applied to collectors of the sensor 1 through the circuits 2A and 2B. Outputs of the converters 3A and 3B are inputted to an arithmetic device 5 through A/D converters 4A and 4B to calculate and supply the azimuth angle of the vector magnetic field of the objective body to a display device 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vector magnetic field detection device used in an encoder or the like.

[Prior art]

In recent years, with the development of NCIC machines, industrial robots, etc., the development of encoders, which are important elements in determining their accuracy, has been attracting attention again. For example, the conditions required for a rotary encoder include high-speed response, short-range stability, compactness and especially thinness, high resolution, and low salivary properties, but nothing that satisfies these requirements has yet been developed. I am in a situation where I am not. In particular, magnetic encoders have poor resolution, and improvement has been slow.

[Purpose of the invention]

The present invention was invented in view of the above situation, and can be used not only as an encoder but also for magnetic flaw detection and other purposes, and moreover, it has less The object of the present invention is to provide a vector magnetic field detection device that satisfies the conditions.

\ [Summary of the Invention] In order to achieve all of the above objects, the vector magnetic field detection device according to the present invention includes a transistor two-dimensional magnetic sensor, a current mirror circuit, a current/voltage converter, an A/D converter, and an arithmetic unit. # Fully equipped.

A transistor two-dimensional magnetic sensor has a plurality of collector bears and detects the magnetic field of an object in two dimensions. Details will be described later. The current mirror circuit detects the difference tone of each bare output current of the magnetic sensor. In the current/voltage converter, the output of the current mirror circuit is supplied to an inverting input terminal, and a predetermined DC voltage is supplied to a non-inverting input terminal. In this way, the input current 1r is converted into a voltage, and the DC voltage is supplied to the collector of the magnetic sensor via the current mirror circuit. The A/D converter converts each output of the current/voltage converter into a digital value. The computing device is 1. Based on the output of the A/D converter, calculate the azimuth or magnitude of the vector magnetic field of the object to be detected.
do.

[Embodiments of the Invention] Next, embodiments of the present invention will be described based on the drawings. 1st
FIG. 2 is a block diagram of a device according to an embodiment of the present invention, FIG. 2 is a plan view of a transistor two-dimensional magnetic sensor, and FIG. 3 is a cross-sectional view showing its basic operation.

First, an overview of the magnetic sensor will be explained based on FIGS. 2 and 3. In the figure, (, (E) is an emitter, 03) is a base, and (C+) to (C4) are collectors. This sensor (1) is a planar type NPN transistor having four collectors (C1) to (C4). Electrons (e-) injected from the emitter (E) are transferred to the base (B)
It will spread throughout the area. At this time, collector (2), rC
z) is arranged symmetrically with respect to the emitter [with]), the '1 child (e-) in the base (B) becomes [fl] as shown by the solid line in Fig. 6, and the collector (C1) and (C2), and there is no difference in current between both collectors (-) and (C2). This also applies to the collectors (Cs) and (C4).

However, when the magnetic field H exists in the y direction, electrons (e-)
receives a force in the X direction due to the Lorentz force, moves as shown by the broken line, and reaches the collector CC2). As a result, a current difference occurs between both collectors (CI) and (C2). Since the current difference is proportional to the magnetic field H, the value of the magnetic field H can be determined by detecting the entire current difference.

Next, a method for detecting a one-vector magnetic field will be explained. The magnetic field Hvr felt by the magnetic sensor is decomposed into components in two directions, and H
Consider x and Hy separately. Then, the collector pair (C
s) and rC4) output an output proportional to Hx, and the collector pair (Cs) and (C) output an output proportional to HyK. Output kcx of collector pair rc3), (C4”)
h Assuming the output Cy of the collector pair (2) and (C2), the direction θ of the magnetic field is θ=Arc tan (Cy/Cx)...
... Old... (1), and the magnitude of the magnetic field H is determined by H = πTC2y... (2).

Next, a detection device of this embodiment using such a magnetic sensor will be explained based on FIG. 1.

In the same figure, (ri) is the above-mentioned magnetic sensor, and includes an emitter (E), a base (B), and collectors (2) to (C4).
It consists of The emitter (E) has a direct current source (
Ve) is applied, and the base (B) is grounded. (
2A).

(2B) are current mirror circuits, and one circuit (2A) is composed of resistors (R1), (R2) and a differential amplifier (At), and has a collector pair (Cs).
, (C<>) are supplied with output currents (I x+) and (Iyg). , collector pair (2), (CS> output current (I)Fl), (Iy*) are supplied. (
3A) and (IB) are current/voltage converters, and one converter (3A) is composed of a resistor (R6), a DC power supply (Eca), and a differential amplifier (A3), and is a current mirror circuit ( An output '1 current (Ix) of 2A) is supplied. Its output (VX) corresponds to the magnitude of the magnetic field in the X direction. The other converter (3B) similarly has a resistor (R6)
, a DC power supply ("cb"), which supplies the output current (Iy) of the current mirror circuit (2B). Its output (vy) corresponds to the magnitude of the magnetic field in the y direction (4A
) and (dB) are A/D converters, respectively, which convert the analog outputs of the current/voltage converters (3A) and (3B) into digital values. (5) is an arithmetic unit, consisting of a microcomputer, an A/D converter (4A), (
The direction or magnitude of the magnetic field of the object to be detected is calculated based on the output of step 4B). (6) is the output display section, and the arithmetic unit t
Display the calculation result of (5).

When using such a detection device as an encoder, a permanent magnet may be attached to the object to be detected.

Now, for example, when the magnetic sensor (1) receives a magnetic field, the output current t-(Ixs) of the collector pair (Ca), (C4)
, (IX2), the resistance (R1) of the current mirror circuit (2A), the electron tube (If) flowing through (R2),
(I2), and the output current of this circuit (2A) is (Δ
Ic), the current flowing into the input terminals of the differential amplifier (p, x) can be ignored, so Ixl ''= 11 ・
・・・・・・・・・・・・・・・・・・・・・(3) Ix
l=I2+ΔIc・・・・・・・・・・・・・・・
......(4). In addition, a differential amplifier (Al
), the potential of the non-inverting input terminal is (V+), the potential of the inverting input terminal is (V-), and the potential of the output terminal is (v
out), then V+ == Vout R4 conflict 11
・・・・・・・・・・・・(5) ■-: vout R
z”h =・old・−(6).Here, ■+=v−
Therefore, R1・I,=R,・I2 *”a I! == uLll ・・・・・・・・・
・・・・・・・・・・・・(7) It becomes R. (7) 2t (Substituting into formula 41, R1=R,
Then, ΔIc = IXII - Ixl ・・・・・・・・・
・・・・・・・・・・・・(9) In this way, the difference current (ΔI) between the collector pair (Cs) and (C4) is
C), i.e. (IX) is obtained. This (■x) is converted into a voltage (Vx) by a current/voltage converter (6A), and a voltage value (VX) corresponding to the X-direction component of the magnetic field is obtained. Output current (I) of collector pair (-), (C2)
yl) and (Iy2) are also current mirror circuits (
2B) and the current/voltage converter (6B), the magnetic field y
The voltage value (Vy) corresponding to the directional component is converted into K. Here, the DC power supply (
Ecl) + (Ecl)) are at the same potential (Ee), and the potential of the non-inverting input terminal and the potential of the inverting input terminal of the differential amplifier are equal, so each collector (CI),
(C2), (C3).

A 4-' voltage (Ec) is applied to (C4) to enable stable operation.

The outputs converted into digital values by the A/D converters (jiA) and (4n) are subjected to the following calculation in the calculation device (5).

θ=Arc tan (My/Vx) −・” ”
``・''・(10 In this way, the direction θ of the magnetic field, that is, the angle, is determined and displayed on the output display section (6). θ
As the magnitude of is smaller, the error in the above calculation becomes larger, so in such a case, θ=Arcot(vy/■large)......aυ.

In this example, we have explained the case where this device is used as an encoder, but when it is used for magnetic flaw detection, H=K = i7... ...CI
You can request the size of the magnetic field depending on the position. and K is the proportionality constant.

Furthermore, although the magnetic sensor has been described as being of the NPN type, it goes without saying that it may be of the PNP type.

〔Effect of the invention〕

As described above, according to the present invention, a transistor-type magnetic sensor is used, and further current/stable operation is obtained, high-speed response, low-speed stability, miniaturization, high resolution, and low cost. It has become possible to realize a detection device that satisfies the following conditions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic vector detection device according to an embodiment of the present invention, FIG. 2 is a plan view of a two-dimensional magnetic sensor, and FIG. 3 is a cross-sectional view showing the basic operation of the two-dimensional magnetic sensor. be. (1)...Two-dimensional magnetic sensor, (2A), (2B)
...Current mirror circuit, (3A), (3B)...1
Current/tortoise pressure converter, (4A), (4B)... /D converter, (5)... Arithmetic device, (6)... Output display section. Agent: Patent Attorney Sanro KimuraFigure 2Figure 3

Claims (1)

[Claims] A transistor two-dimensional magnetic sensor that has multiple collector bears and detects the magnetic field of the object to be detected over two dimensions; A current mirror circuit that calculates the difference in the output current of each collector bear of the magnetic sensor: The output of the current mirror circuit is A current/voltage converter that is supplied to an inverting input terminal, a predetermined DC voltage is supplied to a non-inverting input terminal, and converts the output current t- of the current mirror circuit into pressure; the output of the current/voltage converter and an arithmetic device that calculates the azimuth or magnitude of the vector magnetic field of the object to be detected based on the output of the A/D converter. Magnetic vector detection device.