JPH0537443Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a semi-fixed variable resistor whose resistance value can be adjusted, for example, during or after assembly of an electric circuit, and in particular to a chip-type semi-fixed variable resistor. Regarding variable resistors.

[Conventional technology]

Chip-type semi-fixed variable resistors have a relatively simple structure in which the slider piece is exposed and is attached to the circuit board using reflow soldering, and others have a relatively simple structure in which the slider piece is sealed inside a molded case. There are known devices that are attached to a circuit board using dip solder.

FIG. 4 is a sectional view showing a conventional example of this type of chip type semi-fixed variable resistor, which is constructed for reflow soldering.

In the figure, 1 is a resistor board having a through hole 1a approximately in the center, 2 is a resistor printed on this resistor board 1, 3 is a terminal connected to the end of this resistor 2, and 4 is a An eyelet member 5 is inserted into the through hole 1a, an intermediate terminal 5 is formed by leading one end of the eyelet member 4 to the lower surface of the resistor board 1, and a slider 6 is made of a thin metal plate and has an external appearance as shown in FIG. It is a moving piece. This slider piece 6 has an engagement hole 7 of a predetermined shape.
It is formed by folding in half an upper plate 7 having a diameter of 1.a and a lower plate 8 having a sliding contact 8a and a caulking hole 8b. It is formed. and,
By tightening the upper end of the eyelet member 4 inserted into the caulking hole 8b, the slider piece 6 becomes
It is held in a rotatable state on the resistance substrate 1 via a ring-shaped spacer 9.

The semi-fixed variable resistor having the above configuration is soldered to a predetermined position on a circuit board by reflow soldering, and then an adjustment tool such as a screwdriver is engaged with the engagement hole 7a of the top plate 7 to remove the slider piece. If you rotate 6,
Since the contact position of the sliding contact 8a on the resistor 2 is changed, a desired resistance value can be set.

[Problem that the invention attempts to solve]

By the way, chip-type semi-fixed variable resistors are extremely small with a diameter of several millimeters, but as high-density packaging is progressing these days, there is a demand for semi-fixed variable resistors to be even smaller than ever before. ing.

However, in the conventional semi-fixed variable resistor, it is necessary to secure a space for inserting an adjustment tool between the top plate 7 and bottom plate 8 of the slider piece.
A drawing has to be formed around the caulking hole 8b of the lower plate 8, and this drawing process becomes difficult when the slider piece 6 is miniaturized. Therefore, in a semi-fixed variable resistor equipped with a slider piece having such a shape, it has not been possible to achieve the desired size reduction compatible with high-density packaging.

Therefore, an object of the present invention is to provide a semi-fixed variable resistor that solves the problems of the prior art described above and is easy to downsize.

[Means for solving problems]

In order to achieve the above object, the present invention includes a resistance board having a through hole, an eyelet member inserted into the through hole, an upper member provided with an engagement groove, and a lower member provided with a sliding contact. and a slider piece that is held in a rotatable state on the resistance board by caulking the eyelet member, and the adjustment tool is engaged with the engagement groove of the slider piece and rotated. In the semi-fixed variable resistor whose resistance value can be finely adjusted by dynamic operation, the upper member of the slider piece has a caulking hole whose peripheral edge is eyeleted in the eyelet member, and a caulking hole in the resistor board. A pair of upright parts each having a drawn bulge that stands up against the other and protrudes outward in a semi-cylindrical shape are provided, and the engagement groove is defined by these upright parts.

[Effect]

According to the above means, the upper member of the slider piece is provided with a pair of raised parts defining the engagement groove, and the height of these raised parts ensures insertion space for the adjustment tool. Since the rigidity of each of the upright parts is increased by the semi-cylindrical bulge part which is partially drawn, even a small slider piece can be easily formed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figures 1 to 3 are for explaining one embodiment of the present invention. Figure 1 is a cross-sectional view of a chip-type semi-fixed variable resistor for dip soldering, and Figure 2 is a cross-sectional view of this semi-fixed variable resistor. A perspective view of a slider piece used in a variable resistor, and FIG. 3 is a developed view of this slider piece.

In these figures, 10 is a molded case made of synthetic resin such as polyphenylene sulfite, and a through hole 11a is provided in this molded case 10.
A resistor substrate 11 having the following characteristics is incorporated. A carbon-containing resistor 12 is printed on the surface of the resistor substrate 11 in a substantially horseshoe shape, and both ends thereof are connected to a terminal 13 and a terminal (not shown), respectively. 14 is an eyelet member made of a metal material such as copper and passed through the through hole 11a;
One end of this eyelet member 14 is led out from the lower surface of the resistance board 11 to the outside of the molded case 10 to form an intermediate terminal 15.

Reference numeral 16 denotes a slider piece made of an elastic metal foil plate such as nickel silver. The member 17 is drawn and formed by folding the upper member 17 and the lower member 18 into two at the position of the broken line in the figure. That is, as shown in the external appearance in FIG.
A pair of upright portions 17b having 7a and a caulking hole 17
The lower member 18 is provided with a sliding contact 18a and a through hole 18b, and these bulging portions 17a and upright portions 17b are formed by drawing a thin metal plate as described above. It has high rigidity due to work hardening at that time.

By eyeleting the upper end of the eyelet member 14 inserted into the through hole 18b of the lower member 18 and the caulking hole c of the upper member 17, the slider piece 16 is moved through the ring-shaped spacer 19. is restrained in a rotatable state on the resistance board 11,
An adjustment tool (not shown) is inserted into the engagement groove 21 defined by both the upright portions 17b, and the sliding contact 1 exposed in the notch 17d of the upper member 17 is engaged.
By rotating the slider piece 16 while checking the position of the slider piece 8a, the resistance value can be finely adjusted. Here, the pair of standing parts 1 of the upper member 17
Resistor board 1 at the position where 7b pinches the caulking hole 17c.
1 and the engagement groove 21 is formed between these raised portions 17b, this slider piece 16 has sufficient space to insert the adjustment tool. It is secured.

Reference numeral 20 denotes an airtight cover made of a heat-resistant film such as polyimide. Since this airtight cover 20 closes the opening of the mold case 10, the above-mentioned resistor board 11, slider piece 16, etc. are attached to the mold case 1.
It is in a sealed state within 0.

The semi-fixed variable resistor having the above structure is temporarily fixed to a predetermined position on a circuit board together with other electronic components, and then soldered using dip soldering. Intrusion is prevented by the sealing cover 20. When adjusting the resistance value of the semi-fixed variable resistor after mounting is completed, either peel off the sealing cover 20 or break it with the tip of an adjustment tool such as a screwdriver, and then insert the adjustment tool into the engagement groove 20. If the slider piece 16 is rotated by engaging with the resistor 12
Since the contact position of the upper sliding contact 18a is changed, a desired resistance value can be set.

In the above embodiment, the upper member 1 is formed by appropriately drawing and bending the thin metal plate.
7 is provided with a pair of upright portions 17b for defining the engagement groove 21, the height of the upright portion 17b provides a space into which an adjustment tool can be inserted without drawing around the caulking hole as in the conventional case. Therefore, even small slider pieces can be easily formed. Moreover, the above-mentioned standing portion 1
Since the rigidity of 7b is increased by the outwardly protruding bulge 17a, there is little deformation of the standing portion 17b due to rotational torque during adjustment, and from this point of view, the slider piece can be made smaller. It is advantageous for moreover,
Since the bulging portion 17a projects outward in a semi-cylindrical shape, the bulging portion 17a allows the adjustment tool to be inserted into the engagement groove 21.
The adjustment tool used when there is no bulge 17a can be used as is, and defects such as cracks can be suppressed when drawing the bulge 17a. It is.

Further, since the upper member 17 of the slider piece 16 is provided with a notch 17d at a position corresponding to the slider piece 18a of the lower member 18, the position of the sliding contact 18a can be visually confirmed when adjusting the resistance value. Adjustment work can be done easily.

In addition, although the above embodiment describes a semi-fixed variable resistor for dip soldering, the present invention improves the shape of the slider piece, and can also be applied to a semi-fixed variable resistor for reflow soldering. Needless to say, they are equally applicable.

[Effect of idea]

As explained above, according to the present invention, the engagement groove of the slider piece is defined by a pair of raised parts provided on the upper member, and the height of these raised parts determines the adjustment tool. Since the insertion space is secured, the drawing process around the caulking hole, which hinders miniaturization, can be omitted, and the above-mentioned upright part has a semi-cylindrical bulge that protrudes outward to provide rigidity. Since the height is increased, the operation of inserting the adjustment tool into the engagement groove is not hindered by the bulge, and furthermore,
There is little risk of deformation of the upright piece during adjustment, making it possible to downsize a semi-fixed variable resistor that is compatible with high-density packaging.

[Brief explanation of the drawing]

Figures 1 to 3 are for explaining one embodiment of the present invention. Figure 1 is a cross-sectional view of a chip-type semi-fixed variable resistor for dip soldering, and Figure 2 is a cross-sectional view of this semi-fixed variable resistor. A perspective view of a slider piece used in a variable resistor, FIG. 3 is a developed view of this slider piece, and FIGS. 4 and 5 are for explaining conventional examples. 5 is a sectional view showing a chip type semi-fixed variable resistor for reflow soldering, and FIG. 5 is a perspective view of a slider piece used in this semi-fixed variable resistor. 11...Resistance board, 11a...Through hole, 12...
...Resistor, 14...Eyelet member, 16...Slider piece, 17...Upper member, 17a...Bulging portion, 17
b... Standing portion, 17c... Caulking hole, 18... Lower member, 18a... Sliding contact, 21... Engagement groove.

Claims (1)

[Scope of utility model registration request] The resistor board includes a resistor board having a through hole, an eyelet member inserted into the through hole, an upper member provided with an engagement groove, and a lower member provided with a sliding contact. The slider piece is held in a rotatable state, and the resistance value can be finely adjusted by engaging an adjustment tool in the engagement groove of the slider piece and rotating the slider piece. In the semi-fixed variable resistor, the upper member of the slider piece has a caulking hole whose peripheral edge is eyeleted in the eyelet member;
A pair of upright portions are provided in which a bulging portion that stands up against the resistor substrate and projects outward in a semi-cylindrical shape is drawn, and the engagement groove is defined by these upright portions. Semi-fixed variable resistor.