JPH01132183A - Magnetic proximity switch device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic proximity switch device using a ferromagnetic magnetoresistive element. The purpose of this invention is to provide a proximity switch that can be used at a low cost.

[Conventional technology]

Proximity switch devices used as main parts of positioning devices and detection devices include reed switch types, high frequency oscillation types, capacitance types, and optical switch types.

The reed switch type has the advantage of having a simple structure and low cost, while the high frequency oscillation type can detect all metal objects with extremely high accuracy and has stable detection operation. The capacitive type has the advantage of being able to detect all kinds of objects, not just metals, and the optical switch type has the advantage of being able to detect relatively large objects. This method has the advantage of being able to obtain a range of distances and accurately detecting the distance to the object to be detected.

(Problems to be Solved by the Invention) However, the above-mentioned conventional proximity switch device has
Each has its own disadvantages in terms of basic operation, functionality, and practical use.

In other words, since the reed switch type is a contact structure, it is susceptible to external vibrations and shocks, and chattering may occur at times, ensuring stable and accurate detection operation at all times. The disadvantage was that it was not always possible to do so.

Further, high-frequency oscillation type devices are currently used in large numbers due to the stability and accuracy of their detection operation, but there are complaints that they are expensive and that there is a limit to miniaturization.

Furthermore, the capacitive type requires a large number of components to configure the switch device, and therefore has the disadvantage of being considerably larger and more expensive than a proximity switch device. be.

The optical switch type has a fatal drawback in terms of its operational function: detection cannot be performed due to adhesion of dust and other contaminants, and the device as a whole is large and expensive. There is.

Therefore, the present invention targets the high-frequency oscillation type, which is the most widely used type of the conventional proximity switch device described above, and has the same performance as the high-frequency oscillation type proximity switch device and a high-frequency oscillation type proximity switch device. To provide a proximity switch device that is much cheaper and can be made smaller than a proximity switch device This is the technical issue.

[Means for solving problems]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to drawings showing one embodiment of the present invention.

The means of the present invention includes first and second permanent magnets 2.3 having a ring shape and having magnetic poles located on the end faces, coaxially with different magnetic poles facing each other via a spacer 4 made of a non-magnetic material. A ferromagnetic magnetoresistance element (hereinafter simply referred to as MRR
This MR element body color has a bias magnet 5 integrally assembled in a posture in which a straight line connecting both magnetic poles is orthogonal to the straight line K. MR element body color output It has a comparator 7 to which the terminal is connected, and it has a detection body 9 made of a magnetic material that is movable toward and away from the combination of the magnet body 1 and the MR element body color bias magnet 5. It is in.

The reason why the MR element body color is displaceable with respect to the magnet body 1 is because of the displacement of the M and R element bodies 6 with respect to the magnet body 1.
The purpose is to change the mode of action of the magnetic flux acting on the MR element body from the magnet 1, and change the MR element body color output, that is, the resistance value, in accordance with the change in the mode of action of this magnetic flux. When assembled to the magnet l, the orientation is such that both surfaces thereof are aligned along the straight line K.

[Effect]

The MR element body color is located above the magnet body 1, and the first and second permanent magnets 2 and 3 have ring shapes arranged coaxially and have different magnetic poles. As shown in FIG. 3, when the MR element is positioned at a specified location above the color straight line, the magnetic force from both permanent magnets 2.3 along the straight line K is reduced. The positive and negative effects are equal (see FIG. 3(b)), and the MR element body color is substantially in a state where no magnetic force is applied from both permanent magnets 2.3 along the straight line K.

From this state, that is, the state in which the magnetic force from the MR element color magnet body 1 is not substantially acting, as shown in FIG. When the detection body 9, which is a magnetic body, is located, a part of the magnetic flux from the magnet body 1 is drawn toward the detection body 9, and the magnetic flux from the magnet body 1 is drawn to the detection body 9 side.
The distribution of the magnetic flux that was acting on the R element body changes, and the amount of magnetic force acting in either the positive or negative direction along the straight line K increases, and this increase in the amount of magnetic force causes the MR element body to stop. The output voltage increases or decreases (see FIG. 4(b)). In other words, as the detection object 9 approaches the combination of the magnet l and the MR element holder from a distance, the MR element holder force decreases, and the distance between the MR element holder and the detection object 9 decreases. The operating characteristic is drawn as shown by the characteristic curve S in FIG. 5, in which the MR element body output becomes minimum when the value becomes zero. This M
By detecting increases and decreases in the R element output voltage, it is possible to detect that the detection object 9 has approached.

In addition, apart from this detection operation, the MR element body stopping force characteristic accompanying the relative movement displacement of the magnet I against the MR element body stopping surface is determined along the y-axis (MR Among the magnetic forces acting on the element body, if the magnetic force in the direction along the y-axis increases, the MR element body stopping force value decreases. When the body 1 and the MR element body holder are moved relative to each other,
It will look like the T'' curve in Figure 6(b). That is, MR
If the voltage applied to the element body stop is applied so that the output decreases as the magnetic force in the y-axis direction increases, and the output increases as the magnetic force increases in the x-axis direction, both permanent magnets 2 The maximum output value is reached at a position where the center O'' of the magnet body 1 and the center O of the MR element body are displaced by a distance Δ!, where the magnetic force acting along the y-axis from .3 becomes equal in the positive and negative directions.
An output characteristic is drawn in which the larger the displacement from this position along the y-axis, that is, along the +91K direction, the smaller the MR element end voltage value.

MR due to a change in the MR element body stop force value due to a change in the amount of displacement l, and a change in distance due to the approach and reversal of the detection body 9 to the combination of the magnet body 1 and the MR element body stop described above.
The change in the element end output value is exactly the same (Figures 5 and 6).
(The polarity of the output voltage is reversed in Fig. By knowing the decrease in the stopping power of the MR element, detection of the detection object 9 can be achieved.

However, the combination of the magnet body 1 and the MR element body stop shown in FIG. 3 alone cannot cause the magnetic force to act in the MR element body stop X-axis direction, and therefore the MR element body stop maximum output Since the value cannot be greater than zero (V), M
Although the comparator 7 cannot detect increases or decreases in the output voltage value of the R element element, the bias magnet 5 is integrally assembled in the MR element body in advance. Since a constant magnetic force in the X-axis direction always acts on the MR element body stop, when the magnetic force acting along the y-axis on the MR element body stop is substantially zero,
As shown by the T curve in FIG. 6(b), an output value VB is output due to the acting magnetic force from the bias magnet 5.

Therefore, by setting and fixing the displacement amount l, the MR element body output value v6 is set in advance, and the threshold value v7 of the comparator 7 connected to this MR element body is set from this output value v6. By setting M to a small value, when the detection object 9 approaches the combination of the magnet body 1 and the MR element body stop from this state, the M
The amount of action of the magnetic flux along the y-axis direction from the magnet 1 on the R element body increases, and the MR element body stop output value begins to decrease from the output value v6. When the detecting object 9 approaches a certain distance, the output value of the MR element is detected by the comparator 7.
Therefore, the comparator 7 changes its output level, and the approach of the detection object 9 is detected by this change in the output level of the comparator 7.

As described above, the detection operation of the detection object 9 by the apparatus of the present invention is achieved by changing the output value of the MR element body of the detection object 9 with respect to the threshold value v7 of the comparator 7 set to a constant value. , since the change in the MR element body output value due to the detection body 9 changes along a certain linear line according to the displacement of the detection body 9, the preset threshold value v7
By appropriately setting and changing the difference between the output value v6 and the output value v6, the position of the detection object 9 to be detected, that is, the detection distance can be freely changed.

In addition, since it is composed of an extremely small MR element body 6 and a comparator 7, a magnet body 1 that can be sufficiently miniaturized, and a bias magnet 5, the whole can be made extremely compact, and the components Since the number of parts is small, it is easy to assemble and manufacture, and since each component is inexpensive, the entire device can be manufactured at low cost.

〔Example〕

In the case of the embodiment shown in FIG. 1 and the second example, the magnet body 1 has a second permanent magnet 3 having a larger magnetic force than the first permanent magnet 2, and thus acts on the MR element body 6 on the y-axis. The position along the straight line K where the amount of action of the magnetic force in the positive and negative directions along the line K becomes equal is largely biased towards the first permanent magnet 2.

Furthermore, the connection of the MR element body 6 to the power supply 8 is such that the output value in a state where no external magnetic force is acting on the MR element body 6,
That is, the unbalanced voltage is set to be 0 [v]. In this way, the unbalanced voltage of the MR element body 6 is reduced to 0 [v
] By setting the output voltage value VB of the bias magnet 5, the output voltage value VB can be set easily and accurately.

In the embodiment shown in FIG. 6, the threshold value v of the comparator 7
7 is set to 0 [■], the position setting of the MR element body 6 along the straight line K with respect to the magnet body 1 is such that the output value v6 of the MR element body 6 due to this position setting is smaller than the output value VB. is achieved such that the value is greater than the threshold value v7.

When setting the output value v6 of the MR element body 6, if the displacement position of the MR element body 6 with respect to the magnet l is set near point a in FIG. 6(b), the MR element Since the output value of the object 6 is lower than the threshold value v7, the object 9 can be detected at a large distance. Then, unless the magnetic influence of the detecting body 9 is large, the output value of the MR element body 6 cannot be made lower than the threshold value v7, so the detecting body 9 must be sufficiently close to the MR element body 6. In other words, since the detection object 9 cannot be detected unless the distance becomes small, the detection range can be made small.

For example, the magnet 2 is a ring-shaped body with an inner diameter of 4, an outer diameter of 7 mm, and a thickness of 1 with a surface magnetic force of 100 Gauss, and the magnet 3 is a ring with an inner diameter of 4 m+n, an outer diameter of 7 mm, and a thickness of 3.5 mm. The bias magnet 5 has a rectangular parallelepiped shape with a width and depth of 2.5 mm along the straight line connecting both magnetic poles, a thickness of 1 mm, and a surface magnetic force of 100 Gauss. With the threshold value v7 of the comparator 7 set to OmV, the relationship between displacement IN and detection distance is as follows: displacement l is 1.5M, detection distance is 3 mm, displacement 1
ffi is 1.7 mm, detection distance is 3.5 mm, and displacement! was 1.8M and the detection distance was 4M, achieving highly accurate detection capability.

[Effects of the Invention] As is clear from the above description, the present invention can fully exhibit the accurate and reliable detection function of an approaching detection object, and can make the entire device extremely compact. , can be manufactured at extremely low cost, and also exhibits many excellent effects such as being able to easily and accurately set the distance at which the object to be detected is to be detected over a wide range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment of the device of the present invention and also showing the electrical connection procedure. Figure 2 shows a basic example of the configuration of a combination of a magnet body, an MR element body, and a bias magnet. Figure 2 (a) is a front view, Figure 2 (b) is a side view, and Figure (C) is a side sectional view. FIG. 3(a) is an explanatory diagram showing how the magnetic force of the magnet body acts on the MR element body, and FIG. 3(b) is an explanatory diagram showing the direction and magnitude relationship of the magnetic force acting on the MR element body. FIG. 4(a) is an explanatory diagram for explaining the influence of the detection body on the action of the magnetic force of the magnet body on the MR element body;
Figure (b) is an explanatory diagram showing the direction and magnitude relationship of the magnetic force acting on the MR element body. FIG. 5 is a characteristic diagram showing a change in the form of action of the magnetic force on the MR element body by the detecting body shown in FIG. 4. 6 is for explaining the operating characteristics of the embodiment shown in FIG. 1, FIG. 6(a) is an explanatory diagram showing the displacement form of the MR element body with respect to the magnet body, ) is an explanatory diagram showing detection operation characteristics. Explanation of symbols 1; magnet body, 2; first permanent magnet, 3; second permanent magnet, 4; spacer, 5; bias magnet, 6; ferromagnetic magnetoresistive element body (MR element body), 7; Comparator, 8; power supply, K
; Straight line, l; Displacement, L; Distance, ■6; Output value, VB,
Output value, ■7; Threshold, 0.0゛; Center. Applicant: Nippon Automation Co., Ltd. 2 Talen Maku 1--Ishigami Ushii 1 2--Itcho 51 l difference 1λ
Ji 3-・-father-in-law; 2, unwritten 74-1-s, be--fu 5-----noguiasu unridged stone 6-s leaf p not 7-
Each branch 8-・Mold (C); Chishi, Fuashi 4 Muso n y--Meξi" L, 1 door

Claims (1)

[Claims] First and second permanent magnets (2) and (3), which are ring-shaped and have magnetic poles located on their end faces, are arranged coaxially with different magnetic poles facing each other with a spacer (4) made of a non-magnetic material interposed therebetween. The arranged magnet (1) and the ferromagnetic magnetoresistive element assembled to the magnet (1) so as to be relatively displaceable along the straight line (K) which is the central axis of the magnet (1). body (6) and
a bias magnet (5) integrally assembled to the ferromagnetic magnetoresistive element body (6) with a straight line connecting both magnetic poles perpendicular to the straight line (K); and the ferromagnetic magnetoresistive element body (
The comparator (7) to which the output terminal of 6) is connected, and the combination of the magnet (1), the ferromagnetic magnetoresistive element (6), and the bias magnet (5) can be moved toward and away from the comparator (7). A magnetic proximity switch device comprising a detecting body (9) made of a magnetic material and provided in the magnetic material.