JP2003124009A - Variable resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable resistor that has high connection reliability between terminals and a collector and can be reduced in cost. SOLUTION: This variable resistor is constituted so that its resistance value may be adjusted by sliding the contact pieces of a slider on the collector 12b and a resistor 15 both concentrically provided on the surface of a substrate 10. The collector 12b is composed of an annular metallic material integrally formed with a first terminal 12 and exposed on the surface of the substrate 10. A conductive lubricative layer may be provided on the collector 12b and, when the lubricative layer is provided, it is preferable to form the layer by using the same material as that of the resistor 15.

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. This variable resistor is shown in FIGS.
As shown in FIG. 3, a substrate 100 made of a resin molded product has a center hole 101, and first and second terminals 112 and 113 are embedded. Ends 112a, 1 of the terminals 112, 113
13a projects from the side surface of the substrate 100, and the other end 112
b and 113b are exposed on 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. Current collector 104
Is connected to the other end 112b of the terminal 112, and the resistor 10
The opposite ends 105a of the electrode 5 are connected to the extraction electrode 106.
It is connected to the other end portion 113b of the terminal 113 via.

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]

[Problems to be Solved by the Invention]
In the variable resistor shown in FIG. 3, the current collector 104 is formed on the substrate 100 by applying and firing a paste containing a good conductive material such as silver, and is physically different from the other end 112 b of the first terminal 112. It has a predetermined bonding strength. However, this bonding is performed by burning the metal material (terminal 112) and the paste (collector 10).
It was a joint between different kinds of objects called 4) and was not necessarily strong. That is, the connection is likely to be peeled off due to a stress generated due to a load when cutting or bending the terminal 112 or a difference in thermal expansion coefficient between the substrate 100 and the current collector 104, and reliability as an electric component. There was a problem with sex. Further, silver has a problem in quality that it is sulfurized to increase the contact resistance.

Further, since the current collector 104 is formed by applying a paste on the substrate 100 and firing it, the number of facilities and processes is increased, and the cost is increased.

Therefore, an object of the present invention is to provide a variable resistor which has a highly reliable connection between a terminal and a current collector and which can reduce the cost.

[0007]

In order to achieve the above objects, the variable resistor according to the present invention is electrically connected to the first and second terminals on a substrate made of a resin material. In a variable resistor in which a current collector and a resistor are provided on a concentric circle, and a rotary shaft having a slider is attached to the substrate so that the slider can slide on the current collector and the resistor. , The current collector is made of an annular or substantially annular metal material integrally formed with the first terminal, is exposed on the surface of the substrate, and corresponds to the rotational position of the slider. The resistance value between the first and second terminals is adjusted by changing the length of the extended surface of the current collector and the resistor.

In the variable resistor according to the present invention, the first terminal and the current collector are made of one metal material and have no joint portion. Therefore, even if a load is applied to the terminal or a thermal stress is applied to the current collector, a functional failure such as deterioration of electrical characteristics, malfunction, or failure occurs between the first terminal and the current collector. There is nothing to do. Further, the current collector may be handled integrally with the terminal and cut into a metal material or may be inserted into a resin molded product (substrate), and it is not necessary to form the current collector by a process of applying and firing a paste.

In particular, it is preferable to provide a conductive lubricating layer on the current collector. If the current collector is made of a metal material, wear is promoted by sliding of the slider, but if a lubricating layer is provided, wear is reduced and life can be extended. If this conductive lubricating layer is made of the same material as the resistor, it can be applied (for example, screen printing) in the same step as the resistor.

The width dimension of the conductive lubricating layer is preferably the same as or smaller than the width dimension of the current collector. By doing this, the lubricating layer is formed only on the current collector, and stress due to the difference in thermal expansion coefficient between the metal material (current collector) and the resin material (substrate) is not applied, and cracks occur in the lubricating layer. Is prevented.

[0011]

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 Embodiment, See FIGS. 1 to 6 First, the configuration of the first 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 a central hole 11 and a first terminal 12
And the second terminals 13 and 13 are buried.

The first terminal 12 has ends 12a, 12a.
Is projected from the side surface of the substrate 10, and the central portion is exposed on the surface of the substrate 10 as an annular current collector 12b. The first terminal 12 has its end portions 12a, 12a and the current collector 12b 1
It is an integrally cut piece of metal material. The end portions 13 a of the second terminals 13, 13 project from the side surface of the substrate 10, and the other end portion 13 b is 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 in a substantially annular shape on the surface of the substrate 10 by applying a conductive resin material, and both end portions 15a of the resistor 15 that oppose each other are formed.
Is connected to the other end 13b of the terminal 13. Current collector 1
2b and the resistor 15 are concentrically provided on the surface of the substrate 10, and the current collector 12b is located inside the resistor 15.

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

As shown in FIG. 1A, the central hole 31 of the rotary shaft 30 has a shape in which a part of a circular hole is embedded. An operation shaft (not shown) is inserted into the center hole 31 and is rotated in either the left or right direction, so that the rotation shaft 3
The slider 35 rotates integrally with 0, and the contact pieces 35a, 3
By changing the contact position of 5b with respect to the resistor 15 and the current collector 12b, the extension surface length of the resistor 15 and the current collector 12b is changed, and the resistance value between the terminals 12 and 13 is adjusted.

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, 13, and 13, and does not engage with the side surface 10c but only in surface contact therewith.

By the way, in the variable resistor according to the first embodiment, the current collector 12b is made of one metal material and the first terminal 1.
2 is integrally formed with the current collector 12b and the terminal 12
There is no joint between and. Therefore, the terminal 12
Even if a load is applied to the current collector 12b or a thermal stress is applied to the current collector 12b, no functional failure such as deterioration of electrical characteristics, malfunction, or inability occurs between the terminal 12 and the current collector 12b. In addition, to provide a current collector on the substrate 10,
It is possible to cut the current collector 12b integrally with the terminal 12 and insert it into a mold and provide it on the substrate 10 without requiring a separate process such as paste application and firing, thus reducing manufacturing costs. You can Further, since the paste containing silver is not used, the problem that the contact resistance becomes large due to the sulfuration of silver does not occur.

(Second Embodiment, see FIGS. 7 and 8) Next, a second embodiment of the variable resistor according to the present invention will be described. This variable resistor has basically the same configuration as that of the first embodiment, except that a conductive lubricating layer 14 is provided on the current collector 12b as shown in FIG. The lubricating layer 14 is made of a material containing carbon or graphite as a main component, which reduces frictional resistance with the slider 35.
The main component is a resin similar to the resin component of the resistor 15. Alternatively, the lubricating layer 14 may be made of the same material as the resistor 15. If the lubricating layer 14 and the resistor 15 are made of the same material, both can be simultaneously applied by screen printing or the like, which improves workability.

If the conductive lubricating layer 14 is provided on the current collector 12b as in the second embodiment, the wear generated between the current collector 12b and the slider 35 is significantly reduced, and the life of the current collector 12b is extended. Can be achieved. In order to improve the slidability, the lubricating layer 14 is
It is conceivable that the contact pieces 35a and 35b are surface-treated in accordance with the resistor 15 and the current collector 12b so that the sliding resistance is reduced, in addition to the provision of the above. However, the slider 35
Different treatment specifications at two locations (contact pieces 35a, 35b) of one member are not preferable because they increase the manufacturing cost. In the second embodiment, the life of the current collector 12b can be extended to almost the same as that of the resistor 15 by an inexpensive method of providing the conductive lubricating layer 14 on the current collector 12b.

By the way, as shown in FIG. 8, the width dimension B of the hatched lubricating layer 14 is the same as or smaller than the width dimension A of the current collector 12b, in other words, the lubricating layer 14 is the current collector 1.
It is preferable that the protrusion 2b does not stick out and hang on the substrate 10. The metal material (current collector 12b) and the resin material (substrate 10) have different coefficients of thermal expansion, and if the lubricating layer 14 is the current collector 12b.
When formed over both the substrate 10 and the substrate 10, cracks may occur in the lubricating layer 14 due to thermal stress.
Therefore, by satisfying the condition of B ≦ A, the lubricating layer 14
It is possible to prevent a problem that a crack is generated on the contact piece and adversely affects the contact piece 35b.

The effect of providing the lubricating layer 14 can be similarly applied to the current collector 104 of the variable resistor shown in FIGS. 9 to 11 which is a conventional example.

(Other Embodiments) The variable resistor according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist thereof. In particular, the current collector may not be a complete annular shape, but may be a substantially annular shape with a part missing.

[0025]

As apparent from the above description, according to the present invention, the current collector and the first terminal are formed integrally with the first terminal and exposed on the surface of the substrate. The connection reliability with the terminal is high, the step of separately forming the current collector on the substrate is not required, and the variable resistor can be manufactured at low cost. Furthermore, since the paste containing silver is not used for the current collector, the problem of increase in contact resistance due to sulfuration of silver does not occur.

Further, in the present invention, if a conductive lubricating layer is provided on the current collector, the life of the current collector can be extended. Furthermore, if this lubricating layer is made of the same material as the resistor, the lubricating layer and the resistor can be formed in the same step. Further, if the width dimension of the lubricating layer is the same as or smaller than the width dimension of the current collector, it is possible to avoid the possibility of cracks in the lubricating layer due to the effect of thermal stress.

[Brief description of drawings]

FIG. 1 shows a variable resistor according to a first 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 is a plan view showing a substrate of a variable resistor according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a relationship between width dimensions of a current collector and a lubricating layer.

FIG. 9 shows a conventional variable resistor, (A) is a plan view,
(B) is a side view.

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

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

[Explanation of symbols]

10 ... Substrate 12 ... first terminal 12b ... Current collector 13 ... second terminal 14 ... Conductive lubricating layer 15 ... Resistor 30 ... Rotary axis 35 ... Slider

Claims (4)

[Claims] 1. A first substrate and a second substrate on a substrate made of a resin material.
The current collector and the resistor, which are in electrical connection with the terminals of, respectively, are provided on the concentric circles, and the rotary shaft to which the slider is attached enables the slider to slide on the current collector and the resistor. In the variable resistor attached to the substrate, the current collector is made of an annular or substantially annular metal material integrally formed with the first terminal, and is exposed on a surface of the substrate, The resistance value between the first and second terminals is adjusted by changing the extended surface length of the current collector and the resistor according to the rotational position of the slider. Variable resistor. 2. The variable resistor according to claim 1, wherein a conductive lubricating layer is provided on the current collector. 3. The variable resistor according to claim 2, wherein the conductive lubricating layer is made of the same material as the resistor. 4. The variable resistor according to claim 2, wherein the width dimension of the conductive lubricating layer is the same as or smaller than the width dimension of the current collector.