JPS6366902A - Variable resistor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a variable resistor composed of a stator, a rotor, and a case.

<Prior Art> Conventionally, as this type of variable resistor, one whose cross section is shown in FIG. 5 has been known. This variable resistor 30 is composed of a stator 31 made of an insulating substrate, a rotor 32 that is rotatably operated on the stator 31, and a case 33 that houses these.

The surface of the stator 31 has a current collecting conductor Ji3 at its center position.
Further, an arc-shaped resistance layer 34 is formed around the resistance layer 34, and lead terminals 36. ...is connected. Note that these lead terminals 36. ... penetrates the stator 31 in the thickness direction and is extended to the outside.

A recess 3 extending in the radial direction is provided at the axially inner end of the rotor 32.
2a is formed, and the wiper 37 held in this recess 32a contacts the resistance layer 34 and the current collecting conductive layer 35 in a bridging manner, and slides on both layers 34 and 35 as the rotor 32 rotates. The wiper 37 is made of a plurality of parallel bent metal pieces and is wide and elastic. Further, a convex portion 32b having a smaller diameter than the inner end is formed at the outer end in the axial direction of the rotor 32, and a driver groove 39 is formed on the upper surface of the convex portion 32b which becomes the rotation operation surface 38. .

The case 33 has a box shape with an open bottom, and a rotatable rotor 32 and a stator 31 to which a wiper 37 is fixed are housed inside the case 33 with an O-ring 41 interposed therebetween.
A rotation operation surface 38 of the rotor 32 is exposed to the outside through an opening in the upper portion 33a of the case 33. And case 3
3 Insert resin such as thermosetting epoxy resin from the open side of the bottom 4
By bonding and hardening the stator 31, the stator 31 is fixed to the case 33, and the bottom of the case 33 is hermetically sealed.

In such a variable resistor 30, the wiper 37 slides on the resistance layer 34 and the current collecting conductive layer 35 by rotating the rotor 32.

<Problems to be Solved by the Invention> By the way, the above-mentioned variable resistor has the following problems. That is, since the resin 40 is potted on the open side of the case 33 and cured by heating, time is required for the potting and cooling of the potting resin, resulting in poor productivity.

Furthermore, during bonding, the internal pressure of the sealed case 33 increases due to heating, and the potted resin 40
Inconveniences such as pinholes may occur and the airtightness may deteriorate. Furthermore, as the variable resistor is made smaller, the amount of potting resin decreases, making it difficult to make minute adjustments to the amount of resin.

In view of these conventional problems, the present invention aims to improve productivity by forming the case with a resin mold, thereby eliminating the need for resin botting, and also to facilitate the manufacture of small resistors. purpose.

Here, when the case is formed by resin molding, the rotor needs to be rotatable with respect to the case. However, when a stator or rotor is built into a pre-formed case like a conventional variable resistor, it is necessary to provide a rotation range regulating mechanism such as a protrusion and its guide groove between the case and rotor. However, if the case is made of resin mold, it is not possible to provide such a rotation range regulating mechanism between the case and the rotor.
The rotation range of the rotor is not regulated, and the rotor is rotated too much during adjustment, causing the wiper to come off the resistance layer and causing problems such as poor contact.

Therefore, a second object of the present invention is to restrict the range of rotation of the rotor while the rotor is rotatable within the case, so that the resistance value can be adjusted without any trouble.

<Means for Solving the Problems> In order to achieve the above object, the present invention uses a resistive layer and 11 conductive 1! A variable resistor comprising a stator having a stator formed on its surface, a rotor that rotates while holding a wiper that slides on the resistance layer and the current collecting conductive layer, and a case that houses the rotor and the stator. A locking member electrically connected to the current-collecting conductive layer of the stator is provided protrudingly, and the locking member is fitted into the axially inner end of the rotor to regulate the rotation range of the rotor. A case is formed by forming a groove and molding the stator and the rotor, which is in contact with a required surface portion thereof and has been subjected to mold release treatment, with a resin in a state in which the rotary operation surface of the rotor is exposed to the outside. It is characterized by its configuration.

Effects> According to the above configuration, since the insertion and sealing of the rotor and stator inside the case is completed at the same time as the case is formed, there is no need to hermetically seal the case with resin botting as in the conventional case. Further, since the rotation range of the rotor is restricted by the locking member and the groove formed in the rotor, the rotor does not rotate too much, and the resistance value can be adjusted without any trouble.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a partially cutaway perspective view of the variable resistor, FIG. 2 is a partially omitted exploded perspective view of the stator and rotor, and FIG. 3 is a bottom view of the rotor. In these figures, the symbol IO is a variable resistor. This variable resistor 10 has a stator 11
, a rotor 12 , and a case 13 .

The stator 11 is made of a rectangular flat insulating substrate, and an arcuate resistor 1114 is formed on the surface thereof.

Each of the arcuate ends of this resistance layer 14 has an electrode portion 14a.
, 14b to one side of the stator 11, and the inner ends of corresponding lead terminals 15, 16 are connected to these electrode portions 14a, 14b, respectively.

Further, in the center of the surface of the stator 11, a substantially circular current collecting conductive layer 17 is provided at a predetermined distance from the resistance layer 14.
An extending portion 17a is drawn out from this current collecting conductive layer 17, which is disposed between both arcuate ends of the resistive layer 14. A through hole is formed in this extending portion 17a, and a metal locking member 18 that is inserted through the through hole and projects onto the surface of the stator 11 is disposed. This locking member 1
8 is connected integrally with the inner end of the lead terminal 19 by drawing or the like, and is connected to the extension portion 17a of the current collecting conductor Ji 17, thereby forming a current collecting electrode terminal. Note that this locking member 18 may be formed separately from the lead terminal 19 and fixed to the lead terminal 19.

The rotor 12 is a resin rotating body having a smooth outer circumferential surface, and a recess 12a extending in the radial direction is formed at the inner end of the rotor 12 in the axial direction. A coil wiper 20 sliding on the conductive layer 17 is held with a cushion material 21 interposed therebetween. The coil wiper 20 is made of a metal wire formed into a coil shape.

Furthermore, a stator 1 is provided at the inner end of the rotor 12 in the axial direction.
An arcuate groove 22 into which the protruding locking member 18 is fitted is formed on the surface of the rotor 1, and the inner end surface of the groove 22 comes into contact with the locking member 18, thereby regulating the range of rotation of the rotor 12. It has become.

On the other hand, a circular convex portion 12b having a smaller diameter than the inner end is formed at the outer end in the axial direction of the rotor 12, and the surface of the convex portion 12b, which becomes the rotation operation surface 23, is used for rotating the rotor 12. A driver groove 24 for dynamic operation is formed.

Case 13 is formed by molding resin around stator 11 and rotor 12 . Here, the stator 11 is integrally coupled with the case 13, but the rotor 12 is inserted into the case 13 in a state of being separated from the case 13, and can rotate within the case 13.

Note that such a mold release treatment for the rotor 12 includes a method of applying a mold release agent such as silicone to the surface of the rotor 12 that comes into contact with the stator 11 and the case 13;
A method of mixing a mold release agent into the material of the rotor 12
Alternatively, there is a method of using materials with different shrinkage rates for each of the cases 13 and utilizing the difference in shrinkage. At this time, the outer ends of each lead terminal 15, 16 of the stator 11 and the lead terminal 19 of the rotor 12 are
1 to the outside of the case 13.

Next, as an example of a method of forming the case 13, there is a method as shown in FIG. That is, the rotor 12 is placed on the stator 11 inside the mold 25, and the stator IT and the rotor 12 are pressed by the pressing member 26 so that the rotary operation surface 23 of the rotor 12 comes into pressure contact with the inner wall surface of the mold 25. In this method, molten resin is injected through an opening 27 provided in a mold 25 and then cured. In this way, the case 13 is formed such that resin does not flow between the stator 11 and the rotor 12 and between the rotation operation surface 23 of the rotor 12 and the inner wall surface of the mold 25. Note that the method of forming the case 13 shown in FIG. 4 is an example, and the method is not limited to this.

Next, reference numeral 28 in FIG. 1 is a recess formed on the rotary operation surface 23 of the rotor 12 to indicate the position of the coil wiper 21, and reference numeral 29 is a recess formed on the outer surface of the case 13 at each position of the coil wiper 21. A depression corresponding to the
Both constitute a resistance value scale of the variable resistor 10.

By the way, since the coil wiper 20 in the above embodiment is narrower than the conventional wiper 37 made of a bent metal piece, the required width of the recess 12a can be narrowed, and the rotor 1
The angle range in which the groove 22 is formed, which restricts the rotation range of the groove 22, becomes larger. Further, this coil wiper 20 has the advantage that it can maintain stable contact with the resistance layer 14 and the current collecting conductive layer 17 due to the elastic force of the cushion material 21, and is easy to handle.

<Effects of the Invention> As described above, according to the present invention, since the case is formed by resin molding, the charging and sealing of the stator and rotor is completed at the same time as the case is formed. Therefore, it is not necessary to hermetically seal the case, and therefore, it is possible to improve the productivity of the variable resistor and to reduce its size.

In addition, since the rotation range of the rotor is restricted by the locking member protruding from the stator and the groove of the rotor, the rotor does not need to be rotated too much when adjusting the resistance value, and the resistance value can be adjusted without any problems. .

Furthermore, since the locking member is provided at a position where the current collecting conductive layer for collecting current extends and is outside the rotating range of the wiper, this locking member prevents the wiper from sliding on the resistance layer. The wiper can be slid over the entire range of the resistive layer as before.

Moreover, in the conventional case, it is necessary to incorporate the stator etc. into each pre-formed case, but in the present invention, each lead terminal led out from the stator is connected to each other in a hoop state. It can be manufactured by placing a rotor on each stator and forming a case around it.
Suitable for mass production.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a partially cutaway perspective view of a variable resistor, FIG. 2 is a partially omitted exploded perspective view of a stator and rotor, and FIG. 3 is a partially cutaway perspective view of a variable resistor. Bottom view of the rotor,
FIG. 4 is an explanatory diagram showing an example of a method of forming the case. Moreover, FIG. 5 is a sectional view showing a conventional example. lO... Variable resistor, 11... Stator, 12... Rotor, 13... Case, 14... Resistance layer of stator, 17... Current collecting conductive layer of stator, 18... Locking member, 20...Coil wiper (wiper), 23...Rotor rotation operation surface.

Claims (1)

[Claims] (1) A stator having a resistance layer and a current-collecting conductive layer formed on its surface, a rotor that rotates while holding a wiper that slides on the resistance layer and the current-collecting conductive layer, and the rotor and the stator. In a variable resistor comprising an internal case, a locking member serving as a current-collecting electrode terminal is provided protruding from a current-collecting conductive layer of the stator, and the locking member is fitted into an axially inner end of the rotor. a groove for regulating the rotational range of the rotor; A variable resistor characterized by having a case formed by resin molding in an exposed state.