JP2953487B2 - Moving magnet type instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable magnet type instrument,
In particular, the present invention relates to a movable magnet type instrument having a plastic magnet and a return magnet provided on a bobbin.

[0002]

2. Description of the Related Art A movable magnet type instrument is built in a bobbin.
The magnets used are lighter in weight and easier to install,
A plastic magnet is used.
No. 29417. And this plastic magnet is formed by injection molding, and the gate is formed on the upper or lower surface of the plastic magnet , or
It is provided on one of the outer peripheral side surfaces of the plastic magnet .

[0003]

By the way, the plastic magnet cuts the gate after the injection molding, but if the cut mark protrudes from the surface of the plastic magnet, it contacts the inner wall surface of the bobbin. Step
The clearance between the plastic magnet and the inner wall of the bobbin had to be widened, and the instrument could not be reduced in size. Also, if the gate is provided on the outer peripheral side of the plastic magnet , the trace of the gate cut will be used as a protrusion to make the plastic .
Since it is located at a position separated from the position of the pointer shaft serving as a pivot shaft of the magnet , there is a problem that it is easily affected as a weight imbalance.

[0004] In addition, when the current to the meter is cut off, plus
Although a reset magnet for forcibly operating the tick magnet to the original rotation position is disposed on the synthetic resin bobbin,
When the bobbin opposite to the marks obtained by cutting the gate of the plastic magnet zeroing magnet is then disposed, plastic
The remaining amount of variation of traces gates were cut magnet surface, plastics strength of the magnetic force by the magnet for zeroing is also constant
This affects the distribution of the magnetic field applied to the stick magnet side. As a result, there is a problem that even if the energization to the coil is the same, the instruction is different due to the difference in the influence of the magnetic field by the zero-return magnet.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing problems, and has been made to reduce the size of an instrument and to obtain a stable indication characteristic without indication fluctuation due to the influence of a gate cut mark. It is an object of the present invention to provide a movable magnet type instrument.

[0006]

According to the present invention, in order to solve the above-mentioned problems, a concave portion is provided on an upper surface or a lower surface of a plastic magnet , and a cut mark of a gate is formed in the concave portion.
In addition, the magnet for return to zero is arranged on the bobbin facing the surface where the concave portion is not provided.

[0007]

When a concave portion is provided on the upper surface or the lower surface of the plastic magnet , and there is a cut mark of the gate in the concave portion,
In addition, by arranging the resetting magnet on the bobbin facing the surface of the plastic magnet on which the concave portion is not provided, the instrument can be reduced in size, and the indication does not change due to the influence of the trace of the gate cut . Shows stable indicating characteristics.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. 1-2 show a first embodiment of the present invention, in the figure, plus a 2-pole magnets in the radial direction
While wound to cross the coil 3 on the bobbin 2 made of synthetic resin with a built-in tick magnet 1, the plastic
The upper end of the pointer shaft 4 press-fitted and fixed to the magnet 1 is made to protrude from the bobbin 2, and the pointer 5 is attached to the tip thereof.
The plastic magnet 1 is rotated by the synthetic magnetic field of the coil 3 and is indicated by the pointer 5, and when the current to the meter is cut off, the plastic magnet 1 is forcibly rotated and the pointer 5 linked with this operation is moved. The return magnet 6 for returning to the original rotation position is replaced with the plastic magnet 1.
Is disposed on a bobbin 2 facing the upper surface of the bobbin. The bobbin 2 is housed in a substantially cylindrical case 7 made of a metallic material so as to block disturbance factors such as terrestrial magnetism.

In such a configuration, the plastic magne
A recess 8 is provided on the lower surface of the unit 1 and a gate
It has a cutting mark 9 . Therefore, plastic magne
The cut mark 9 of the gate does not protrude from the surface of the unit 1, the clearance between the plastic magnet 1 and the inner wall surface of the bobbin 2 can be narrowed, and the instrument can be downsized.

Further, the plastic magnet 1 as described above has become a surface provided with a recess 8 is the lower, side are disposed a zero reset magnet 6, i.e. for upper flat surface, the recess 8 or gate Shows a stable indicating characteristic without the influence of the magnetic field fluctuation due to the protrusion of the cutting mark 9 of FIG.

FIG. 3 shows a second embodiment of the present invention.
In this embodiment, the shape of the concave portion having the cut mark 9 of the gate is formed as an annular concave portion 10 on the lower surface of the plastic magnet 1 . Thus, the weight imbalance of the plastic magnet 1 can be reduced as compared with the first embodiment.

The number of recesses formed on the upper or lower surface of the plastic magnet is not limited to two, but may be one or more. The shape of the concave portion need not be circular but may be square. Further, in the above embodiment, the zero-reset magnet is flop
Although disposed on the bobbin facing the upper surface of the plastic magnet , it may be disposed on the bobbin facing the lower surface or the outer peripheral side surface of the plastic magnet . However, plastic
When it is arranged on the bobbin opposed to the lower surface of the magnet , a concave portion is provided on the upper surface of the plastic magnet , and a cut mark of the gate is provided in the concave portion.

[0013]

According to the present invention, a recess is provided on the upper or lower surface of a plastic magnet , and a gate is cut in the recess.
And has a Dan'ato, by which is arranged a zero-restoring magnet on the bobbin opposite to the surface which is not provided with the recess of the plastic magnet, the gate from the surface of the plastic magnet
No trace of cutting sticks out of plastic
The clearance between the magnet and the inner wall surface of the bobbin can be reduced, and the instrument can be reduced in size. Further, since the surface of the plastic magnet on the side where the zero-return magnet is disposed is flat, a stable pointing characteristic can be obtained without the influence of magnetic field fluctuation due to the protrusion of the recess or the cutting trace of the gate .

[Brief description of the drawings]

FIG. 1 is an instrument cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a plastic magnet and a pointer shaft of the embodiment.

FIG. 3 is a perspective view showing a configuration of a plastic magnet and a pointer shaft according to a second embodiment of the present invention.

[Description of Signs] 1 Plastic magnet 2 Bobbin 3 Coil 4 Pointer shaft 6 Magnet for return to zero 8 Recess 9 Cut mark of gate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01R 5/16 G01R 1/16

Claims (1)

(57) [Claims] 1. A pointer shaft rotatably supported in a hollow synthetic resin bobbin, a coil wound around the bobbin to generate a magnetic force in response to an electric current, and is coaxially fixed to the pointer shaft made of plastic magnet which rotates according to the magnetic force, plastic mug
The net is provided with a concave portion on the upper surface or the lower surface, has a cut mark of the gate in the concave portion, and faces the surface where the concave portion is not provided.
To the bobbin that, the positive at the time of non-energization of the coil
A movable magnet type instrument provided with a reset magnet for returning the tick magnet to the original rotation position.