JPH0626808Y2 - Displacement converter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement converter, and more particularly to a non-contact type displacement converter that magnetically detects and converts displacement. The displacement conversion device according to the present invention is for detecting a linear displacement or an angular displacement in a non-contact manner and converting this into an electric signal.
In particular, it has excellent linearity of characteristics between input and output, and is suitable for feedback control of the pen position of the recorder and feedback control elements such as robots.

2A and 2B are a plan view and a side view of a displacement conversion device according to West German Patent No. 2511683 as an example of a conventional magnetic detection type displacement conversion device. In the figure, an exciting coil N ₁ is wound around a magnetic core 1 having a U-shaped cross section made of a high magnetic permeability material, and this is excited by an AC power source 2 connected to exciting terminals D ₁ and D ₂ . An air gap 1a is provided in the magnetic core 1, and the printed wiring board 3 on which the detection coil N ₂ is formed is arranged so as to intersect the air gap 1a of the magnetic core 1. Each turn of the detection coil N ₂ has a shape including a blade-like constant inclined portion. Magnetic core 1 by excitation of AC power supply 2
AC flux is generated in the void 1a, but the magnetic resistance is not constant because the magnetic resistance is not constant. For example, the magnetic flux densities of the base portion, the intermediate portion, and the tip portion are B ₁ , B ₂ , B ₃ Then, B ₁ > B ₂ > B ₃ . The ratio of the magnetic permeability of a high magnetic permeability material such as ferrite to the air is on the order of 100: 1, and this nonuniform magnetic flux density cannot be ignored.

The output voltage e corresponding to the interlinkage magnetic flux of the detection coil N ₂ is induced between the output terminals T ₁ and T ₂ . Since each turn of the detection coil has the above-mentioned blade-shaped constant inclination part, this interlinkage magnetic flux depends on the relative position between the magnetic core and the printed wiring board,
Therefore, the output voltage e indicates its relative position. That is, the mechanical relative displacement x between the magnetic core and the printed wiring board is converted into an electrical output voltage e.

The origin of the coordinates of the displacement x is set to the left end of the detection coil N ₂ as shown in FIG. 2A, and the constant slope portions of each turn of the detection coil are sequentially shifted as shown in the same figure. If the distribution is uniform, the displacement x and the output voltage e
The relationship between and is a straight line indicated by the thick solid line OP in FIG. That is, the vertical height of the straight line OP is proportional to the crossing area of the magnetic core 1 and the detection coil N _2, and if the magnetic flux distribution in the air gap 1a is uniform, the output voltage e represented by the straight line OP is induced. , Good linearity can be obtained. Reference numeral 1'in FIG. 2A indicates the magnetic core 1 at the coordinate origin.

However, in reality, the magnetic flux distribution in the air gap 1a is non-uniform as described above, and the actual output voltage e is the curves 4, 5, 6 in FIG.
It becomes non-linear as shown by.

In order to avoid this non-linearization, various improved methods have been proposed. Spread the closer the gap 1a of the U-shaped magnetic core 1 to the exciting coil N _1, it is considered to substantially uniform the magnetic flux density in the gap 1a, such divergent taper cut is difficult to machine, practical It has not been. There is utility model registration No. 1634377 (Jitsuko 60-33369) as a possible improvement method. In this method, the leg length of the void 1a of the U-shaped magnetic core 1 is set to 2
The above coil N ₂ as a detection coil and the coil N ₂ ′ which is the inside thereof are doubled and arranged side by side so as to face the leg of the air gap 1a, and the sum (e + e ′) of the output voltages of both coils is set as the detection value. By doing so, the linearity is improved. By forming both coils N ₂ and N ₂ ′ side by side without geometrically arranging them side by side on the other side and using the sum of the electrical outputs of both coils, the problem of non-linearity is solved. May be resolved.

In addition, utility model registration No. 1695217 (Jitsuko Sho 62-3684)
Is a coil with a shape in which the interlinkage magnetic flux increases with displacement x on the surface of the printed wiring board, and a coil with a shape in which the interlinkage magnetic flux decreases with displacement x on the back surface of the printed wiring board. The use solves the above problem.

The problem to be solved by the invention However, the above-mentioned conventional non-linearity problem solving method has a drawback that it requires a pair of detection coils N ₂ and N ₂ ′, which complicates the manufacturing process. In particular, in the case of using an inexpensive double-sided printed wiring board, if both sides were occupied by the coils N ₂ and N ₂ ′, there was a practical inconvenience that it became impossible to have other functions (described later).

Therefore, an object of the present invention is to solve the problem of output non-linearity due to uneven magnetic flux density by using only one side of a printed wiring board.

Means for Solving the Problems Referring to the embodiments of FIGS. 1A and 1B, according to the present invention, a printed wiring board 3 provided with a detection coil N ₂ having a plurality of turns is provided for a magnetic core 1 excited by an alternating current. In the displacement conversion device which is arranged so as to intersect with the air gap 1a and changes the interlinking magnetic flux of the detection coil N ₂ according to the relative displacement x between the magnetic core and the printed wiring board, the shape of each turn of the detection coil N ₂ is changed. Center line parallel to the direction of relative displacement x between magnetic core and printed wiring board
A configuration in which the turns are symmetrical and the turns are sequentially shifted along the center line 10 is used. In the case of FIG. 1A, since the magnetic core 1 moves in the longitudinal direction of the rectangular printed wiring board 3, the center line 10 substantially coincides with the longitudinal center line of the printed wiring board 3.

As is apparent from the above description, in the printed wiring board 3 of the displacement conversion device according to the present invention, it suffices to provide the detection coil N ₂ on only one surface thereof, and the opposite surface can be used for other purposes. it can.

Operation In FIG. 1A, when the magnetic core 1 is displaced with respect to the printed wiring board 3 from the point O in the direction of the X axis, the interlinkage magnetic flux with the detection coil N _{2 on} the upper side of the center line 10 becomes x = in FIG. Although it increases along the upper dotted line 4a from the point 0, the interlinkage magnetic flux on the lower side of the center line 10 is below the straight line OP in FIG.
It increases along 4a and along the whole thick solid line OP. Therefore, the output voltage e between the output terminals T ₁ and T ₂ is a straight line
It is given as a value proportional to the average of two dotted lines 4a symmetrical with respect to OP, and the characteristic of the output voltage e can be represented by the straight line OP. That is, the linear change in the magnetic flux density of the magnetic core air gap 1a on both sides of the center line 10 acts so as to cancel each other by the interlinking magnetic flux on both sides of the center line 10, and as a result, the output voltage e becomes linear with respect to the displacement x. , The third of the prior art
The non-linearity problem shown in curve 4 of the figure is solved. The non-linearity of curves 5 and 6 in FIG.
It is clear that it will be solved as an average of 5a and 6a.

Moreover, since the detection coil N ₂ is provided only on one side of the printed wiring board 3, the present invention relates to solving the problem of non-linearity of output due to uneven magnetic flux density by using only one side of the printed wiring board. The purpose of is achieved.

Embodiment In the embodiment shown in FIGS. 1A and 1B, the detection coil N _{2 is} used to linearize the relationship between the displacement x of the magnetic core 1 and the output voltage e.
, Each turn is formed by only a straight line portion, and the pattern apex angles A ₁ , A ₂ , ... A _n at the intersection with the center line 10 are made equal. If it is necessary to make the relationship between the displacement x and the output voltage e non-linear, the pattern apex angle A ₁ ,
By slightly changing A ₂ , ... A _n , the relationship between the displacement x and the output voltage e has a non-linear polygonal line approximation characteristic.

In the above description, the change in the magnetic flux density of the magnetic core air gap 1a is assumed to be linear. However, even when the change is non-linear, the detection coils have the apex angles A ₁ , A ₂ , ... Of each turn.
The relationship between the displacement x and the output voltage e can be linearized by appropriately selecting a conductor shape that defines A _n , rather than a linear shape, according to a required change in magnetic flux density.

In another embodiment of the present invention shown in FIG. 4, the detection coil N ₂ is formed on a flexible printed wiring board 3 and the printed wiring board 3 is attached to the side wall of a cylindrical member (not shown). . When this printed wiring board 3 is developed, it becomes the same as that of the embodiment shown in FIG. 1A. The magnetic core 1 of the embodiment shown in FIG. 4 also has an air gap 1a that intersects with the printed wiring board 3, and the magnetic core 1 rotates along the cylindrical surface formed by the printed wiring board 3 and the output terminal of the printed wiring board 3 is rotated. T ₁ , T ₂
An output voltage e corresponding to the angular displacement of the magnetic core 1 is induced between them.

A control coil Nc is provided on the back surface of the printed wiring board 3 of the embodiment shown in FIG. 4, and a constant control voltage e _c is generated between the control terminals C ₁ and C ₂ thereof regardless of the angular position of the magnetic core 1. . As long as the magnetic flux density of the air gap 1a of the magnetic core 1 does not change, the control voltage e _c
Is constant. The purpose of the control coil Nc, This was detected when the magnetic flux density of the gap 1a is changed by the power supply voltage variations or temperature change by variations of the control voltage e _c, and further adjusting the voltage of the AC power source 2 above To keep the magnetic flux density constant.

In the embodiment shown in FIG. 5, the detection coil N ₂ is formed on a circular printed wiring board 11. Each turn of the detection coil has a substantially symmetrical shape with respect to the center line 10 having an average radius Rm. In this embodiment, the exciting coil N ₁ is fixed on the printed wiring board 11. To facilitate the mounting of the magnetic core 1,
The slit 12 is provided in the printed wiring board 11. Rotating shaft 13
Penetrates through the center of the printed wiring board 11 at a right angle and is rotatably supported by a bearing (not shown). The magnetic core 1 having the void 1a intersecting the printed wiring board 11 is fixed to the rotating shaft 13 by the adhesive 14. Output terminal T of printed wiring board 11
An output voltage e corresponding to the angular displacement of the rotary shaft 13 is induced between ₁ and T ₂ .

The configuration of the present invention is not limited to the above description, and various modifications can be made. For example, although it is convenient to form the detection coil N ₂ on the printed wiring board 3, the same effect can be obtained by forming the detection coil N ₂ on the alumina substrate by the thick film technique. In the above embodiment, the magnetic core 1 is movable and the output coil N ₂ is fixed.
The output is generated in proportion to the relative displacement between the output coils, and the magnetic core 1 may be fixed and the output coil N ₂ may be movable, or both may be movable. Figure 1A,
In the example of FIGS. 2A and 3, since the magnetic core 1 and the exciting coil N ₁ are movable, the AC power source 2 is connected to the exciting terminals D ₁ and D ₁ .
Need a flexible feeder to connect to ₂ .

The output waveform of the AC power supply 2 may be a sine wave, a triangular wave, a rectangular wave, or the like. The rectangular wave is most advantageous in terms of easiness of oscillation and rectification of output voltage. The inventor has found that frequencies of the order of 10 KHz are suitable for certain applications.

The shape of the iron core 1 is not necessarily limited to the U-shaped cross section, and the magnetic flux distribution in the air gap can be improved by exciting the open ends of two U-shaped magnetic cores from both ends. In FIG. 1A, the apex angles A ₁ , A ₂ ... A _n of each turn of the detection coil are made acute, but this may be 180 degrees or more to form an M-shaped coil turn. In short, it is sufficient if the shape is symmetrical with respect to the center line.

Effect of the Invention As described in detail above, according to the present invention, a printed wiring board provided with a detection coil having a plurality of turns is arranged so as to intersect the air gap of a magnetic core excited by alternating current, and the interlinkage magnetic flux of the detection coil is In a displacement conversion device that changes according to relative displacement between printed wiring boards, the shape of each turn of the detection coil is symmetric with respect to a center line parallel to the relative displacement direction between the magnetic core and the printed wiring board, and Since the configuration in which the turns are arranged in a staggered manner along the center line is used,
It has the following effects.

(A) It is possible to prevent output non-linearity due to nonuniform magnetic flux density in the air gap of the magnetic core.

(B) Since the output voltage with good linearity can be obtained by using only one side of the printed wiring board, the opposite side of the printed wiring board is used to improve the coil for controlling the magnetic flux density of the magnetic core gap or to improve the displacement detection sensitivity. It can be used as a coil.

[Brief description of drawings]

1A and 1B are a plan view and a side view of an embodiment of the present invention, FIGS. 2A and 2B are a plan view and a side view of a conventional displacement transducer, and FIG. 3 is a graph showing an output characteristic. , FIG. 4 and FIG. 5 are explanatory views of other embodiments. 1 ... Magnetic core, 1a ... Air gap, 2 ... AC power supply, 3, 11 ...
Printed wiring board 4, 5, 6 ... Curve, 10 ... Center line,
12 …… slit, 13 …… rotating shaft, 14 …… adhesive, e ・ ・ ・
… Output voltage, N ₁ …… Excitation coil, N ₂ …… Detection coil,
x: Displacement.

Claims (3)

[Scope of utility model registration request] 1. A printed wiring board provided with a detection coil having a plurality of turns is arranged so as to intersect with an air gap of a magnetic core excited by an alternating current, and an interlinking magnetic flux of the detection coil is relatively displaced between the magnetic core and the printed wiring board. In the displacement conversion device that changes in accordance with the above, the shape of each turn of the detection coil is symmetrical with respect to the center line parallel to the relative displacement direction between the magnetic core and the printed wiring board, and each turn is sequentially arranged along the center line. Displacement transducers that are staggered. 2. The displacement conversion device according to claim 1, wherein the printed wiring board has a cylindrical shape. 3. The displacement conversion device according to claim 1, wherein the printed wiring board has an annular disc shape.