JP2003124008A - Variable resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable resistor not affected by resin powder produced between a substrate and a rotating shaft. SOLUTION: This variable resistor is constituted so that its resistance value may be adjusted by sliding the contact pieces 35a and 35b of a slider 35 on a collector and a resistor concentrically provided on the surface of the substrate 10. In the center hole 11a of the substrate 10, a recessed section 11b having a stepped surface 11c is formed, and, on the rotating shaft 30, a stepped surface 33 is formed correspondingly to the stepped surface 11c of the recessed section 11b. When the rotating shaft 30 is rotated in a state where the stepped surfaces 11c and 33 are brought into contact with each other, the resin powder is generated by frictional. However, the resin powder is not scattered on the surface of the substrate 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable resistor, and more particularly to a slider mounted on a rotatable rotary shaft so as to slide on a resistor and a current collector on a substrate to adjust the resistance value. To the variable resistor.

[0002]

2. Description of the Related Art Conventionally, as a rotary type variable resistor provided with a slider, one disclosed in Japanese Patent Laid-Open No. 2000-138109 is known. In this variable resistor, as shown in FIGS. 7 to 9, a substrate 100 made of a resin molded product has a central hole 1
01, the terminals 112 and 113 are embedded. The ends 112a and 113a of the terminals 112 and 113 are the substrate 10
The other ends 112b and 113b are exposed from the upper surface of the substrate 100. On the substrate 100, a current collector 104 is formed in an annular shape, and a resistor 105 is formed in an approximately annular shape in concentric circles. The current collector 104 is connected to the other end 112 b of the terminal 112, and both ends 105 a of the resistor 105 facing each other are connected to the terminal 11 via the extraction electrode 106.
3 is connected to the other end 113b.

In the center hole 101 of the substrate 100, there is rotatably mounted a rotary shaft 107 made of a resin molded product having a slider 108 made of a conductive material. This slider 108
Is formed with a contact piece 108a that slides on the resistor 105 and a contact piece 108b that slides on the current collector 104. Depending on the rotational position of the contact pieces 108a and 108b, the terminals 112,
The resistance value between 113 is adjusted. Further, a cover 109 made of a resin molded product is attached on the substrate 100.

[0004]

By the way, in the variable resistor shown in FIGS. 7 to 9, the central hole 1 of the rotating shaft 107 is used.
A shaft (not shown) is inserted in 07a, and a rotational force is applied to the rotary shaft 107 by the shaft.
The rotation of the rotary shaft 107 in the variable resistor may reach several million times, and the flange portion 107b of the rotary shaft 107 and the surface of the substrate 100 are brought into sliding contact with each other (at a portion indicated by a symbol A in FIG. 8), so that the resin powder is Occur. The generated resin powder adheres to the current collector 104 and the resistor 105 which are close to each other, and the contact piece 108a,
Problems such as contact failure of 108b and deterioration of rotation life have occurred.

Therefore, an object of the present invention is to provide a variable resistor which is not adversely affected by resin powder generated between a substrate made of a resin material and a rotary shaft.

[0006]

In order to achieve the above objects, a variable resistor according to the present invention is a resistor and a current collector electrically connected to terminals on a substrate made of a resin material. In a variable resistor in which a rotary shaft made of resin material with a slider attached to the substrate is slidably mounted on the resistor and current collector, A center hole is formed on which the shaft is rotatably mounted, and a concavity that is concentric with the center hole and that is continuous with the center hole at a step surface is formed, and a step surface that faces the step surface of the recess is formed on the rotating shaft. It is characterized in that the rotary shaft and the stepped surface of the recess are in contact with each other.

In the variable resistor according to the present invention, the substrate made of a resin material and the rotary shaft are brought into contact with each other by the step surface of the recess formed in the central hole of the board and the step surface formed on the rotary shaft. The rotating shaft rotates in the contact state. Although resin powder is generated on the step surfaces that are in contact with each other, the generation place is the inner peripheral surface of the central hole of the substrate, and the resin powder does not scatter on the surface of the substrate. Therefore, the resin powder does not adhere to the current collector and the resistor provided on the surface of the substrate, and the contact failure with the slider and the deterioration of the rotation life are avoided.

In particular, it is preferable that the slider is attached to a flange portion protruding from the outer peripheral surface of the rotary shaft, and a gap is formed between the flange portion and the surface of the substrate. It is possible to reliably prevent the generation of resin powder on the surface of the substrate.

Further, the center hole may be formed in an annular protrusion projecting on the back surface of the substrate, and the strength of the bearing portion of the shaft inserted into the rotating shaft is reinforced. Furthermore, it is preferable that the annular protrusion is fitted into the hole of the printed circuit board. The height of the variable resistor when mounted is reduced, and the annular projection is supported by the printed circuit board. It also plays the role of positioning the variable resistor with respect to the printed circuit board.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a variable resistor according to the present invention will be described below with reference to the accompanying drawings.

First, the configuration of an embodiment of the variable resistor according to the present invention will be described with reference to FIGS.

This variable resistor comprises a substrate 10 made of a resin molded product, a cover 20 made of a resin molded product, and a slider 3.
5 and a rotary shaft 30 made of a resin molded product. The substrate 10 has an annular protrusion 11 protruding from the back surface thereof to form a center hole 11a, and terminals 12 and 13 are embedded therein. The terminal 12 has an end portion 12 a on the substrate 10.
, And the central portion is exposed on the surface of the substrate 10 as an annular current collector 12b. The terminal 13 has an end 13 a protruding from the side surface of the substrate 10 and the other end 13 b exposed on the surface of the substrate 10.

As shown in FIG. 4, the terminals 12 and 13 are formed by punching a long hoop material 40 into a predetermined shape, and are inserted into a molding die (not shown) to mold the substrate 10. After this resin molding, the resistor 15 is formed on the surface of the substrate 10 in a substantially annular shape by applying a conductive resin material, and both end portions 15 of the resistor 15 facing each other are formed.
a is connected to the other end 13b of the terminal 13. Also,
The conductive lubricating layer 14 is provided on the current collector 12b. The lubricating layer 14 contains a resin similar to the resin component of the resistor 15 as a main component. Alternatively, the lubricating layer 14 is the resistor 15
It is also possible to use the same conductive resin material as above and apply it at the same time as the resistor 15.

Current collector 12b (lubrication layer 14) and resistor 15
Are concentrically provided on the surface of the substrate 10, and
b is located inside the resistor 15.

The rotary shaft 30 has a center hole 31, and a slider 35 is attached around the flange portion 32, and is rotatably mounted in the center hole 11a of the substrate 10. The slider 35 is made of a conductive metal material, and has a brush-shaped first contact piece 35 a that slides on the resistor 15 in an elastically pressed state.
It has a brush-shaped second contact piece 35b that slides elastically on the current collector 12b (the lubricating layer 14) in a pressed state.

Further, a recess 11b is formed in the upper half of the central hole 11a of the substrate 10. This recess 11b
Are concentric with the central hole 11a and are continuous with the central hole 11a at a step surface 11c. Further, as shown in FIG. 1A, the central hole 31 of the rotating shaft 30 has a shape in which a part of a circular hole is embedded, and the central hole 31 and the central hole 11a of the substrate 10 have the same inner diameter. .

As shown in FIG. 2, the rotary shaft 30 has a substrate 1
When it is attached to the center hole 11a of 0, the step surface 33 is in contact with the step surface 11c of the recess 11b. Further, a gap C is formed between the flange portion 32 of the rotating shaft 30 and the surface of the substrate 10.

The cover 20 has a central hole 21 for positioning the upper portion of the rotary shaft 30, and is attached to the substrate 10 by a so-called snap-in method. More specifically, as shown in FIG. 6, the engaging projection 1 having an upper side inclined to the side surface of the substrate 10.
0a is formed, and the first part provided on the side of the cover 20 is formed.
A through hole 20a that engages with the protruding portion 10a is formed in the protruding piece 22 in the thickness direction of the protruding piece 22, and the through hole 20a is formed into the protruding portion 10a.
Snap-in method. Further, the cover 20 is provided with a second projecting piece 23 located on the side surface 10c of the substrate 10. The second projecting piece 23 corresponds to the terminal 1
It is formed in a comb-teeth shape in order to avoid interference with 2 and 13, and does not engage with the side surface 10c but only engages with it.

In the variable resistor having the above structure, the projection 11 of the board 10 is fitted into the hole 46 of the printed board 45 shown by the dotted line in FIG. 2, and the terminals 12 and 13 are connected to the land of the printed board 45. It is mounted in a soldered state (not shown). Then, in order to rotate the rotary shaft 30 and the slider 35, an operation shaft (not shown) is inserted into the center holes 31 and 11a. This shaft has a shape in which the insertion portion engages with the central hole 31, and when the shaft 35 is rotationally driven in either the left or right direction, the slider 35 rotates integrally with the rotation shaft 30, and the contact pieces 35a and 35b are rotated. Resistor 15 and current collector 1
By changing the contact position with respect to 2b, the terminal 1
The resistance value between 2 and 13 is adjusted.

In the variable resistor of this embodiment, when the rotary shaft 30 is rotationally driven by the shaft, the greatest frictional force acts on the step surfaces 33 and 11c that are in contact with each other. Causes resin powder to be generated. However, this location is the inner peripheral surface of the center hole 11a, and the resin powder does not scatter on the surface of the substrate 10.
Therefore, the resin powder does not adhere to the current collector 12b (the lubricating layer 14) or the resistor 15, and the contact failure with the slider 35 and the deterioration of the rotation life are prevented. Moreover, since the gap C is formed between the flange portion 32 of the rotary shaft 30 and the surface of the substrate 10, the generation of the resin powder here is reliably prevented.

Further, the shaft is the central hole 31 of the rotary shaft 30.
Is supported by the inner peripheral surface (center hole 11a) of the annular projection 11 provided on the substrate 10, and the strength of the bearing portion is high and the durability is improved. Then, the substrate 10 can be thinned by the amount of the protrusion 11 protruding.

Further, since the annular projection 11 is fitted in the hole 46 of the printed circuit board 45, the height of the variable resistor can be reduced at the time of mounting and the strength of the projection 11 is reinforced. To be done. It also plays the role of positioning the variable resistor with respect to the printed circuit board.

The variable resistor according to the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made within the scope of the gist thereof.

[0024]

As is apparent from the above description, according to the present invention, the step surface formed on the rotary shaft contacts the step surface of the concave portion formed on the inner peripheral surface of the central hole of the substrate to rotate. , The resin powder generated at this abutting part does not scatter on the surface of the substrate, it is possible to prevent contact failure between the slider and the current collector and resistor, and extend the rotational life of the slider. be able to.

Further, if the center hole is formed in an annular protrusion protruding from the back surface of the substrate, the strength of the bearing portion of the shaft inserted into the rotating shaft is reinforced. Further, if the annular protrusion is fitted into the hole of the printed circuit board, it contributes to the height reduction of the variable resistor at the time of mounting, and the annular protrusion is reinforced by the printed circuit board. It also plays the role of positioning the variable resistor with respect to the printed circuit board.

[Brief description of drawings]

FIG. 1 shows a variable resistor according to an embodiment of the present invention,
(A) is a plan view and (B) is a side view.

FIG. 2 is a cross-sectional view showing a state in which the variable resistor is mounted on a printed board.

FIG. 3 is a plan view showing a substrate of the variable resistor.

FIG. 4 is a plan view showing a molded state of the substrate.

FIG. 5 is a perspective view showing a cover of the variable resistor.

FIG. 6 is a cross-sectional view showing an example of an engaging structure between the substrate and the cover.

FIG. 7 shows a conventional variable resistor, (A) is a plan view,
(B) is a side view.

8 is a sectional view of the variable resistor shown in FIG.

9 is a plan view showing a substrate of the variable resistor shown in FIG.

[Explanation of symbols]

10 ... Substrate 11 ... An annular protrusion 11a ... central hole 11b ... recess 11c ... stepped surface 12, 13 ... Terminal 12b ... Current collector 15 ... Resistor 30 ... Rotary axis 31 ... central hole 32 ... Flange 33 ... Step surface 35 ... Slider 45 ... Printed circuit board 46 ... Hole C ... gap

Claims (4)

[Claims] 1. A resistor and a current collector, each electrically connected to a terminal, are concentrically provided on a substrate made of a resin material, and a rotary shaft made of a resin material having a slider attached thereto is slid. In a variable resistor in which a child is slidably mounted on a resistor and a current collector on the substrate, a center hole for rotatably mounting the rotating shaft is formed on the substrate, and the center hole is concentric with the center hole. A stepped surface that is continuous with the center hole in a stepped surface, and a stepped surface that faces the stepped surface of the recessed portion is formed on the rotary shaft, and the rotary shaft and the stepped surface of the recessed portion are in contact with each other. A variable resistor characterized by. 2. The slider is attached to a flange portion projecting from an outer peripheral surface of the rotating shaft, and a gap is formed between the flange portion and a surface of the substrate. The variable resistor according to item 1. 3. The variable resistor according to claim 1, wherein the center hole is formed in an annular projection protruding from the back surface of the substrate. 4. The variable resistor according to claim 3, wherein the annular projection is fitted in a hole of a printed circuit board.