JPS5834786B2 - Moving coil type device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moving coil type device such as a galvanometer that is displayed by the rotational angular displacement of a moving coil in a constant magnetic field, and is particularly compact and lightweight, and has a large deflection angle of the coil to achieve high resolution. It relates to a device that can obtain.

In this type of moving coil type device, especially when the device is small and the swing angle of the coil (or swing width of the pen) is large compared to the width, the relationship between the input current and the swing angle is such that the input current increases significantly. This tends to deteriorate linearity, so
The shape of the magnet has been improved to improve its characteristics.

Fig. 1 is a cutaway view of a conventional moving coil type device, Fig. 2 is a perspective view of its main parts, 1.2 is a fixed part, that is, an upper and lower cover;
3 (3a t 3 b ) is a shaft pivotally attached to the upper and lower lids 1 and 2, 4 is a coil having the shaft 3, 5 is a magnet, 6 is a combined yoke to which the magnet 5 is attached, and 7 (7a).

7b) are two sets of independent closed magnetic circuits each acting on the coil 4.

The coil 4 is formed into a rectangular frame shape having one side 4a and the other side 4b parallel to the axis 3, and is connected to a closed magnetic circuit 7C7.
a, 7b) is a yoke 6 whose cross section is loop-shaped.
formed by.

Then, the coil 4 is assembled by freely inserting the corresponding side 4a or 4b into this loop.
are respectively subjected to the action of the closed magnetic circuit 7.

Further, the closed magnetic circuit 7 is configured such that a longitudinal gap 9 surrounding the shaft 3 is formed in the coil 4 between the two combined yokes 6.

Further, the coil 4 is wound around a rectangular coil frame 10, and a shaft 3a or 3b is provided at the center of the upper and lower sides of the coil frame 10.
The coil frame 10 is rotatably attached to the fixed part, that is, the upper and lower lids 1.2.

12 are upper and lower bearings of the shaft 3, respectively.

As shown in FIG. 2, the combined yoke 6 has an internal yoke 14 having a Σ-shaped cross section and only the opposing inner surface 13 deformed into an arc shape, and -
A plate-shaped external yoke 15 having a rare earth magnet 5 adhered to its surface is assembled with the magnet 5 disposed inside.

The coil 4, that is, the sides 4a and 4b of the coil frame 10, are provided with external yokes so that the cross section is loop-shaped enough to pass through the coil frame 10 vertically and rotate, and a space 16 of approximately equal width is provided over the shaft 3. The inner surface of the tag magnet 5 is also formed into an arc shape, and both ends of the tag magnet 5 in the width direction are formed to be shorter than those of the external yoke 15.

Furthermore, the outer yoke 15 is formed longer than the inner yoke 14, and the combined yoke 6 has a space 17 between the top and bottom of the internal yoke 14 and the upper and lower lids 1 and 2, through which the coil frame 10 passes laterally. Each is made separately.

Further, both combined yokes 6 independently form closed magnetic circuits 7 from the magnets 5.

Then, the coil frame 10 with the coil 4 attached and the combined yoke 6
is assembled with upper and lower covers 1 and 2.

Furthermore, one side 4a or the other side 4b of the coil frame 10 is passed through the space 16, and the inner and outer yokes 14 and 15 are assembled to form a combined yoke 6, and both combined yokes 6 are attached to the arc-shaped inner surface. 13 are arranged axially symmetrically so as to face each other, and the other shaft 3a,
3b are passed through the upper or lower lids 1 and 2, respectively.

Then, both the combined yokes 6 and the coil frame 10 are fixed in a predetermined position in the vertical direction by the upper and lower lids 1 and 2, and the upper and lower inner peripheral edges of the outer yoke 15 are brought into contact with the positioning protrusions 18 of the lids 1 and 2. By doing so, positioning can be performed in the circumferential direction, and at this time, the coil frame 10 can be rotatably supported and assembled as a whole.

Reference numeral 22 denotes a mounting hole in the upper lid 1 when this device is attached to another device.

By the way, in the conventional moving coil type device having the above-mentioned configuration, when the swing angle of the coil 4 (or the swing width of the pen) is set to a large value, it is possible to avoid deterioration of the direct relationship between the input current and the swing angle. In order to do this, the center O' of the curved surface of the magnet 5 on the coil 4 side is moved from the rotation center O of the coil 4, as shown in the cross-sectional view of the main part in FIG. Coil 4 is a curved surface with radius R' from center of rotation O'.
The gap length is changed with respect to the rotation angle of , and the magnetic flux distribution in the gap is made uniform.

FIG. 4 shows the case where the center of the curved surface 5a of the magnet 5 on the coil 4 side is not moved from the rotation center O of the coil 4, and the magnetic flux density distribution in the gap is shown by a curve 23.

In this case, the effective magnetic flux density that acts as a torque on the coil 4 when it swings at a certain angle can be expressed as the sum of the effective magnetic flux densities that act as a torque for each conductor 4' of the coil 4 divided by the coil width W. , this is called the average magnetic flux density acting on the coil 4, and is shown by a curve 26 in FIG.

5 and 6 are magnetic flux density distribution diagrams in the gap in the conventional method. When the center O' of the curved surface of the magnet 5 on the coil 4 side is gradually moved from the rotation center O of the coil 4, the magnetic flux The density distribution changes like curves 24 and 25.

As can be seen from this, in the past, the magnetic flux density distribution was made flat in order to improve the linearity of the relationship between the input current and the deflection angle.

Note that the curve 23 is also shown as a broken line in FIGS. 5 and 6 for comparison.

A curve 29 in FIG. 7 is a magnet that does not move the center of the curved surface 5a of the magnet 5 on the coil 4 side from the rotation center O) /I6.
The curve 30 in FIG. 8 shows the customization of the average magnetic flux density acting on the coil versus the rotation angle of the coil in this device.

Moreover, in order to improve these characteristics, the curve 31 in FIG. This shows a slightly improved customization of the linearity of the rotation angle of the coil versus the coil, and curve 32 in Figure 8 shows a slightly flattened customization of the average magnetic flux density acting on the coil versus the rotation angle of the coil in this case. .

However, although it is effective for slightly correcting the linearity of the input current versus the rotation angle of the coil, when correcting it beyond a certain level, the customization of the rotation angle versus magnetic flux density may not be very flat, as shown in Figure 8. If the linearity is to be further corrected, the center of the curved surface on the coil 4 side of the magnet should be
There is a disadvantage that the current sensitivity of the O coil 4 is significantly deteriorated since it is necessary to move the O coil 4.

In view of these points, the present invention provides a moving coil that improves the current sensitivity of the coil by slightly improving the structure of the magnet in the moving coil type device, reducing the cost by improving the customization of the input current versus deflection angle. This paper aims to propose a molding device.

An embodiment of the present invention will be described below in detail with reference to FIGS. 9 to 13, and parts corresponding to those in FIGS. 1 to 8 will be described with the same reference numerals.

FIG. 9 is a sectional view of a main part of an embodiment of the present invention, and is illustrated in correspondence with FIG. 3.

In this example, a groove-shaped notch 33 is formed in the direction of the winding of the coil 4 (perpendicular to the plane of the paper) approximately at the center of the surface 5a facing the coil 4 of the magnet 5 having a structure similar to that shown in FIG. establish.

Although the cross section of the notch 33 is a yamabushi shape in the illustrated example, it is not necessarily limited to this.

The magnet 5 is magnetized in a direction perpendicular to the surface of the coil 4, and the notch 3
When the inner part of 3 is magnetized to N pole, for example, the stepped part 5b of the surface 5a
.

Numerals 5c are N poles of the same polarity, and generate magnetic fields (diamagnetic fields) in opposite directions in directions that lie on the surface 5a.

Furthermore, the deeper the notch 33 is, the lower the magnetomotive force at the inner part thereof, and the more the magnetic resistance increases.

As a result, the magnetic field directed from the deep part of the notch 33 toward the surface of the coil 4 is weakened.

This situation is shown in FIG.

FIG. 10 is a distribution diagram of magnetic flux density near the magnet 5,
For convenience, only changes are shown.

If there is no notch 33, the magnetic flux density distribution will be as shown by the broken line 27, and if the notch 33 is provided, the magnetic flux density distribution will be as shown by the solid line 34.

In this state, the average magnetic flux density V (integral value of magnetic flux) acting on the coil 4 becomes a curved, substantially flat curve like a curve 35.

Furthermore, when the shape of the notch 33 is cut deep and wide, the magnetic flux becomes a curve 36 as shown in FIG. 11, and the average magnetic flux density acting on the coil 4 becomes completely flat as a curve 37.

By the way, the magnitude of the demagnetizing field can be adjusted appropriately by selecting various shapes of the width and depth of this notch 33, and the average magnetic flux density acting on the coil can be adjusted by customizing the input current vibration angle and the rotation angle of the coil. Custom orders can be selected at will.

Figure 12 shows the characteristics of the input current versus the rotation angle of the coil when the shape of the magnet 5 is variously changed.
, 1.3, 1.5, and 1.7 mm) In the device using A3-/16.6, the rotation angle of the input terminal and the coil becomes curves 38, 39, 40, and 41. This is a custom-made product with excellent linearity over a wide range of areas.

Furthermore, Fig. 13 shows the average magnetic flux density acting on the coil with respect to the rotation angle of the coil in this case. The curves 42°, 43, 44, and 45 represent the special order.

As is clear from these custom-made drawings, instead of making the magnetic flux distribution uniform in the gap where the coil 4 is located as in the past, the present invention creates a relationship between the coil rotation angle and the average magnetic flux density acting on the coil. Since the current sensitivity is made uniform, the linearity of the input current vs. coil rotation angle characteristic can be improved over a wide range without significantly deteriorating the current sensitivity, and the average magnetic flux acting on the coil with respect to the coil rotation angle can be improved. The density characteristics can be flattened over a wide range.

Therefore, according to the present invention, since the amplitude range of the coil can be widened compared to the width W of the device, the device can be easily made smaller and lighter, and a moving coil type device with high resolution and high precision can be obtained. be able to.

Note that the notch 33 in the above embodiment may be made as deep as possible, and the magnet 5 may be divided into two parts as shown in FIG. It is also possible to use

Further, although the above example uses a pair of magnets, the present invention can also be applied to a device using a single magnet.

Furthermore, in the present invention, one side of the coil 4 is connected to the magnet 5 and the external yoke 1.
5, or the coil is not limited to a rotating type, but can also be applied to a movable type.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional moving coil type device, Fig. 2 is a perspective view of the main part of the conventional example, Fig. 3 is a sectional view of the main part of the conventional example, and Fig. 4 is a sectional view of the main part of the conventional example.
Figure 6 is a magnetic flux density distribution diagram of the conventional example, Figure 7 is a custom diagram of input current vs. coil rotation angle of the conventional example, and Figure 8 is a custom diagram of coil rotation angle vs. average magnetic flux density acting on the coil in the conventional example. FIG. 9 is a sectional view of essential parts of an example of the present invention, and FIG. 10 is a characteristic diagram of
Figures 1 and 11 are magnetic flux density distribution diagrams of an example of the present invention.
Figure 2 is a characteristic diagram of the input current versus rotation angle of the coil in each embodiment of the present invention, Figure 13 is a custom diagram of the rotation angle of the coil versus the average magnetic flux density acting on the coil in each embodiment of the present invention, and Figure 14 is a characteristic diagram of the rotation angle of the coil in each embodiment of the present invention.
The figure is a schematic diagram showing another example of the magnet used in the present invention. 3 is a shaft, 4 is a coil, 5 is a magnet, and 33 is a notch.

Claims (1)

[Claims] 1. In a moving coil type device in which at least one side of a substantially rectangular frame-shaped moving coil is disposed within a gap in a magnetic circuit consisting of a magnet and a yoke, the above-mentioned A magnet magnetized in a direction perpendicular to the surface of the moving coil is disposed opposite to the surface of the moving coil, and a groove-shaped groove is formed in the substantially central part of the surface of the magnet facing the moving coil in the direction of the winding of the moving coil. A moving coil type characterized in that a notch is provided, and the average magnetic flux density acting on the moving coil is made almost constant by selecting the width and depth of the notch (maximum being the thickness of the magnet). Device.