JPH0537444Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a small chip variable resistor whose resistance value can be varied.

[Conventional technology]

Conventionally, one of this type of chip variable resistors is described in, for example, Japanese Utility Model Application No. 53-44305, and
As shown in FIG. 4, on the upper surface of an insulating substrate A having a through hole B, a resistive film G is formed in an arc shape centered on the through hole B, and a metal plate is disposed on the lower surface of the insulating substrate A. A hollow support shaft D that fits into the through hole B is integrally formed on the terminal plate C made of aluminum, while a slider E made of a metal plate that comes into sliding contact with the resistive film G is attached to the tip of the support shaft D. There is one in which the slider E is rotatably attached to the support shaft D by fitting the slider E in a rotatable manner and then caulking the support shaft D (this caulking portion is indicated by the symbol F). .

[The problem that the idea attempts to solve]

However, in this method of rotatably attaching the slider E to the support shaft D by caulking the tip of the support shaft D, when the slider E is rotated, Since the caulking becomes loose and the rotational torque of the slider E rapidly decreases, stable rotational torque cannot be applied to the slider E.

Therefore, in order to solve this problem, it is recommended to strengthen the caulking at the tip of the support shaft D, or insert a ring-shaped leaf spring between the caulking part F and the slider E on the support shaft D. However, the former method would result in the slider E not being able to rotate, and the latter method would require a large number of parts and assembly man-hours, resulting in a significant increase in manufacturing costs. It invites Atpu.

The present invention enables the slider to be rotatably attached to the support shaft by caulking the support shaft, without causing the slider to be unable to rotate or increasing the number of parts and assembly man-hours. The present invention provides a chip variable resistor capable of imparting stable rotational torque to a mover.

[Means to solve the problem]

In order to achieve this object, the present invention forms a resistive film on the upper surface of an insulating substrate having a through hole in an arc shape centered on the through hole, and on a terminal board disposed on the lower surface of the insulating substrate. A variable chip in which a support shaft that fits into the through hole is integrally molded, and a slider that makes sliding contact with the resistive film is rotatably attached to the tip of the support shaft by caulking the tip of the support shaft. In the resistor, a heat-resistant synthetic resin is applied to the caulked portion at the tip of the support shaft, spanning at least both the support shaft and the slider.

[Functions and effects of the idea]

In this way, the synthetic resin applied to the caulked part at the tip of the support shaft, spanning both the support shaft and the slider, will remain glued to the support shaft when the slider is rotated. Either it peels off from the slider and contacts and slides on the slider, or it peels off from the support shaft while being adhered to the slider and contacts and slides on the support shaft. This acts as a brake that applies rotational resistance to the rotation of the slider, thereby preventing the rotational torque of the slider from rapidly decreasing due to loosening of the caulking to the slider. As a result, the rotational torque applied to the slider can be stabilized.

In this case, by using a heat-resistant synthetic resin as the synthetic resin, the synthetic resin will not burn out even if it receives heat when soldering the chip variable resistor to a printed circuit board or the like. A predetermined rotational torque can be reliably applied to the mover.

In addition, the present invention provides a caulking portion of the support shaft.
All you need to do is apply heat-resistant synthetic resin, and there is no need to strengthen the caulking on the support shaft or use a ring-shaped leaf spring, so there is no risk of the slider not being able to rotate. At the same time, it has the effect of not causing a significant increase in manufacturing costs due to an increase in the number of parts and the number of assembly steps.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates an insulating substrate provided with a through hole 2 approximately in the center, and on the upper surface of the insulating substrate 1,
The resistive film 3 is formed in an arc shape with the through hole 2 at the center.

Reference numeral 4 indicates a terminal plate made of a metal plate disposed on the lower surface of the insulating substrate 1, and a hollow support shaft 5 that fits into the through hole 2 is integrally formed on the terminal plate 4. ing.

Reference numeral 6 indicates a slider made of a metal plate disposed on the upper surface of the insulating substrate 1. After the slider 6 is rotatably fitted onto the tip of the support shaft 5, the slider 6 is attached to the support shaft 5. By caulking the tip of 5 (this caulking part is indicated by reference numeral 7), it is rotatably supported with respect to the support shaft 5. A sliding terminal 8 that slides into contact is integrally formed.

Note that numerals 9 and 10 indicate terminals for both ends of the resistive film 3, and numeral 11 indicates a receiving groove for a driver tool in the slider 6. Two cutting lines 11a, 11a are carved in parallel, and both cutting lines 1
It is formed by concavely molding the portion 11b between 1a downward.

The caulking portion 7 at the tip of the support shaft 5 is made of silicone resin having a heat resistance of about 180°C.
A heat-resistant synthetic resin 12 such as an epoxy resin having a heat resistance of about 200°C or a polyimide resin having a heat resistance of about 230°C is spread over both the support shaft 5 and the slider 6. It is applied, dried and cured (in this case, the synthetic resin 12 is preferably one that has some elasticity even after drying and curing).

In this way, the synthetic resin 12 applied across both the support shaft 5 and the slider 6 remains adhered to the support shaft 5 when the slider 6 is rotated with a screwdriver tool. Either it peels off from the slider 6 and contacts and slides on the slider 6, or it peels off from the support shaft 5 while being adhered to the slider 6 and contacts and slides on the slider 6. Since contact and sliding act as a brake on the rotation of the slider 6, the synthetic resin 12 can provide rotational resistance to the rotation of the slider.

When applying the synthetic resin 12, if the inside of the hollow support shaft 5 is filled with the synthetic resin 12 as shown in the figure, the chip variable resistor can be attracted by a vacuum collect. It becomes possible.

Further, the inside of the hollow support shaft 5 is closed with a synthetic resin 12 as shown in the figure, while the slider 6 is made of a non-solderable metal material such as stainless steel or aluminum, or By applying a non-solder bondable surface treatment such as aluminum plating to the surface of the slider 6, a part of the surface of the terminal plate 4 made of a solder bondable metal material and the surface of the support shaft 5, When soldering a chip variable resistor to a printed circuit board without applying a non-solder bonding surface treatment such as aluminum plating, the printed circuit board on which the chip variable resistor is mounted in advance is immersed in molten solder. , it is possible to adopt the so-called solder dip method.

[Brief explanation of drawings]

Figures 1 to 3 show embodiments of the present invention;
The figure is a plan view, Figure 2 is a cross-sectional view of Figure 1,
FIG. 3 is a cross-sectional view taken from the side of FIG. 1, and FIG. 4 is a vertical cross-sectional front view of a conventional chip variable resistor. DESCRIPTION OF SYMBOLS 1...Insulating substrate, 2...Through hole, 3...Resistive film, 4...Terminal plate, 5...Support shaft, 6...Slider, 7...Caulking part, 8...Sliding terminal, 11...
Driver tool receiving groove, 12...synthetic resin.

Claims (1)

[Scope of utility model registration request] A resistive film is formed in an arc shape centered on the through hole on the upper surface of the insulating substrate having the through hole, and a support shaft that fits into the through hole is integrally formed on the terminal plate disposed on the lower surface of the insulating substrate. In the chip variable resistor, a chip variable resistor is provided, in which a slider which is molded in a conventional manner and is in sliding contact with the resistive film is rotatably attached to the tip of the support shaft by caulking the tip of the support shaft. 1. A chip variable resistor characterized in that a heat-resistant synthetic resin is applied to the caulked portion so as to span at least both the support shaft and the slider.