JP3716774B2 - Variable resistor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable resistor, and more particularly to a variable resistor in which a slider attached to a rotatable rotating shaft slides on a resistor and a current collector on a substrate to adjust the resistance value.
[0002]
[Prior art]
Conventionally, as a rotary variable resistor having a slider, one disclosed in Japanese Patent Application 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 center hole (bearing hole) 101 and terminals 112 and 113 are embedded therein. The end portions 112 a and 113 a of the terminals 112 and 113 protrude from the side surface of the substrate 100, and the other end portions 112 b and 113 b are exposed on the upper surface of the substrate 100. On the substrate 100, the current collector 104 is formed in an annular shape, and the resistor 105 is formed in a substantially annular shape on a concentric circle. The current collector 104 is connected to the other end portion 112 b of the terminal 112, and the opposite end portions 105 a of the resistor 105 are connected to the other end portion 113 b of the terminal 113 through the extraction electrode 106.
[0003]
A rotating shaft 107 having a slider 108 made of a conductive material is rotatably mounted in the bearing hole 101 of the substrate 100. A contact piece 108a that slides on the resistor 105 and a contact piece 108b that slides on the current collector 104 are formed on the slider 108, and a terminal 112 is formed according to the rotational position of the contact pieces 108a and 108b. , 113 is adjusted. A cover 109 made of a resin molded product is attached on the substrate 100.
[0004]
[Problems to be solved by the invention]
By the way, in the variable resistor shown in FIGS. 7 to 9, a shaft (not shown) is inserted into the center hole 107 a of the rotation shaft 107, and rotational force is applied to the rotation shaft 107 by the shaft. The rotation of the rotating shaft 107 in the variable resistor may reach several million times, and the rotating shaft 107 and the bearing hole 101 for receiving the rotating shaft 107 are required to have a strength that can withstand the eccentricity and vibration of the shaft. That is, it is preferable that the effective diameter portion A of the bearing hole 101 is as large as possible and the thickness B of the rotating shaft 107 is as thick as possible.
[0005]
Therefore, in the conventional variable resistor, in order to secure a necessary amount of the effective diameter portion A of the bearing hole 101, a certain amount of the substrate 100 is required, and it is difficult to reduce the thickness. Further, it is preferable to increase the diameter of the shaft in order to increase the rotational fracture strength of the shaft itself. However, since it is necessary to secure a predetermined amount of the wall thickness B of the rotating shaft 107, the shaft (center hole 107a) is formed. When the diameter is increased, the diameter of the variable resistor itself is also increased, which goes against the demand for downsizing of electronic components, and is difficult to realize.
[0006]
In other words, if the effective diameter portion A is reduced to reduce the thickness of the substrate 100 or the wall thickness B is reduced to increase the diameter of the shaft, the strength of the bearing portion is reduced, and wear is likely to occur. Had.
[0007]
Accordingly, an object of the present invention is to provide a variable resistor that can reinforce the bearing portion of the shaft to enhance durability, and can achieve a thinner substrate and a larger shaft diameter (thinning of the rotating shaft). There is to do.
[0008]
[Means and Actions for Solving the Problems]
In order to achieve the above object, the variable resistor according to the first aspect of the present invention is provided with a resistor and a current collector electrically connected to terminals on a substrate on a concentric circle and a slider attached thereto. In the variable resistor in which the rotating shaft is attached to the substrate so that the slider can slide on the resistor and the current collector, a bearing hole in which the rotating shaft is rotatably mounted is formed in the center of the substrate. In addition, an annular protrusion that protrudes concentrically with the bearing hole is provided on the back surface of the substrate, and the annular protrusion has the same inner diameter as the central hole of the rotating shaft .
[0009]
In the variable resistor according to the second invention, a resistor and a current collector, which are electrically connected to terminals, are provided on a substrate on a concentric circle, and a rotating shaft to which a slider is attached is slid. A variable resistor in which a child is slidably mounted on a resistor and a current collector, and the rotating shaft and the slider are integrally rotated by a shaft inserted into a central hole of the rotating shaft. An annular protrusion that protrudes concentrically with the bearing hole is provided on the back surface of the protrusion, and the inner peripheral surface of the protrusion functions as a bearing for the shaft.
[0010]
In the variable resistor according to the first and second inventions, the rotation of the shaft inserted into the rotating shaft to rotate the rotating shaft is not only the center hole of the rotating shaft but also the annular shape provided on the back surface of the substrate. It will also be supported by the protrusions, increasing the strength of the bearing portion of the shaft. Therefore, it is possible to reduce the thickness of the substrate and the shaft (thinning the rotating shaft).
[0011]
In particular, the annular protrusion provided on the back surface of the substrate preferably has the same inner diameter as the central hole of the rotating shaft. Furthermore, it is preferable that the annular protrusion is fitted into the hole of the printed board on which the variable resistor is mounted. A reduction in height during mounting can be achieved as the substrate becomes thinner, and the annular protrusion is supported by the printed circuit board. It also serves to position the variable resistor with respect to the printed circuit board.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a variable resistor according to the present invention will be described with reference to the accompanying drawings.
[0013]
First, the configuration of a variable resistor according to an embodiment of the present invention will be described with reference to FIGS.
[0014]
This variable resistor includes a substrate 10 made of a resin molded product, a cover 20 made of a resin molded product, and a rotary shaft 30 made of a resin molded product provided with a slider 35. The substrate 10 has a center hole (bearing hole) 11a, and terminals 12 and 13 are embedded therein. An end 12a of the terminal 12 protrudes from the side surface of the substrate 10, and a 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 at the surface of the substrate 10.
[0015]
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 the opposite end portions 15a of the resistor 15 are the other end portions of the terminals 13. 13b. A conductive lubricating layer 14 is provided on the current collector 12b. The lubricating layer 14 is mainly composed of a resin similar to the resin component of the resistor 15. Alternatively, the lubricating layer 14 may be made of the same conductive resin material as that of the resistor 15 and applied simultaneously with the resistor 15.
[0016]
The current collector 12 b (lubricating layer 14) and the resistor 15 are provided concentrically on the surface of the substrate 10, and the current collector 12 b is located inside the resistor 15.
[0017]
The rotating shaft 30 has a center hole 31 and has a slider 35 attached around the flange portion 32, and is rotatably mounted in the bearing hole 11 a of the substrate 10. The slider 35 is made of a conductive metal material, and the brush-like first contact piece 35a that slides elastically on the resistor 15 in a pressure contact state, and the current collector 12b (lubricant layer 14) elastically. And a brush-like second contact piece 35b that slides in a pressure contact state.
[0018]
Further, the substrate 10 is provided with an annular protrusion 11b protruding to the back side. The protrusion 11 b is concentric with the bearing hole 11 a and has the same inner diameter as the center hole 31 of the rotating shaft 30. Moreover, the center hole 31 of the rotating shaft 30 has a shape in which a part of the circular hole is embedded as shown in FIG.
[0019]
As shown in FIG. 2, in the variable resistor, the protrusion 11b of the substrate 10 is fitted into the hole 46 of the printed circuit board 45, and the terminals 12 and 13 are soldered to lands (not shown) of the printed circuit board 45. Implemented in the state. In order to rotate the rotating shaft 30 and the slider 35, the operation shaft 50 inserted into the center hole 31 has a shape in which the insertion portion engages with the center hole 31. It is supported by the inner peripheral surface 11c of the protrusion 11b. Then, by rotating the shaft 50 in either the left or right direction, the slider 35 is rotated together with the rotating shaft 30, and the contact positions of the contact pieces 35a and 35b with respect to the resistor 15 and the current collector 12b are changed. By changing, the resistance value between the terminals 12 and 13 is adjusted.
[0020]
The cover 20 has a center 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. Specifically, as shown in FIG. 6, an engaging protrusion 10 a whose upper side is inclined is formed on the side surface of the substrate 10, and the first protrusion 22 provided on the side of the cover 20 is engaged with the protrusion 10 a. The mating through hole 20a is formed in the thickness direction of the projecting piece 22, and the through hole 20a is engaged with the projecting part 10a by a snap-in method. Further, the cover 20 is formed with a second protruding piece 23 located on the side surface 10 c of the substrate 10. The second projecting piece 23 is formed in a comb-like shape in order to avoid interference with the terminals 12 and 13, and only comes into surface contact with the side surface 10c and does not engage with it.
[0021]
By the way, in the variable resistor of this embodiment, the shaft 50 is supported by the center hole 31 of the rotating shaft 30 and the inner peripheral surface 11c of the annular protrusion 11b provided in the substrate 10, and the strength of the bearing portion is increased. Large and durable. And the board | substrate 10 can be thinned by the part which the protrusion 11b protrudes. Moreover, the thickness of the rotating shaft 30 may be thin, and the thinned thickness B is as shown in FIG. That the thickness of the rotating shaft 30 may be thin means that the diameter of the center hole 31 is increased, that is, the diameter of the shaft 50 is increased, and the rotational fracture strength of the shaft 50 is improved.
[0022]
Further, since the annular protrusion 11b is fitted into the hole 46 of the printed circuit board 45, the variable resistor is reduced in height during mounting, and the strength of the protrusion 11b is reinforced. It also serves to position the variable resistor with respect to the printed circuit board.
[0023]
The variable resistor according to the present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the gist.
[0024]
【The invention's effect】
As apparent from the above description, according to the present invention, the shaft inserted into the center hole of the rotating shaft is supported not only by the center hole but also by an annular projection provided on the back surface of the substrate. The strength of the part is increased and the durability is improved. In addition, since the thickness of the substrate and the thickness of the rotating shaft can be reduced and the diameter of the shaft can be increased, the rotational breaking strength of the shaft is improved.
[0025]
Further, if the annular projection provided on the back surface of the substrate has the same inner diameter as the central hole of the rotating shaft, the shaft can basically be used having a straight diameter. Furthermore, if the annular protrusion is fitted into the hole of the printed circuit board, it contributes to a reduction in height during mounting and the protrusion is reinforced. It also serves to position the variable resistor with respect to the printed circuit board.
[Brief description of the drawings]
1A and 1B show a variable resistor according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a side view.
FIG. 2 is a cross-sectional view showing a state where the variable resistor is mounted on a printed board and a shaft is inserted.
FIG. 3 is a plan view showing a substrate of the variable resistor.
FIG. 4 is a plan view showing a molding state of the substrate.
FIG. 5 is a perspective view showing a cover of the variable resistor.
FIG. 6 is a sectional view showing an example of an engagement structure between the substrate and the cover.
7A and 7B show a conventional variable resistor, in which FIG. 7A is a plan view and FIG. 7B is a side view.
8 is a cross-sectional view of the variable resistor shown in FIG.
9 is a plan view showing a substrate of the variable resistor shown in FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Board | substrate 11a ... Bearing hole 11b ... Ring-shaped protrusion 11c ... Inner peripheral surface 12, 13 ... Terminal 12b ... Current collector 15 ... Resistor 30 ... Rotating shaft 31 ... Center hole 35 ... Slider 45 ... Printed circuit board 46 ... hole 50 ... shaft

Claims (4)

Resistors and current collectors that are electrically connected to the terminals on the board are provided on concentric circles, and the slider can slide on the resistors and current collectors on the rotating shaft to which the sliders are attached. In the variable resistor attached to the substrate,
A bearing hole in which the rotating shaft is rotatably mounted is formed at substantially the center of the substrate, and an annular protrusion protruding concentrically with the bearing hole is provided on the back surface of the substrate , the annular protrusion Has the same inner diameter as the central hole of the rotating shaft ,
A variable resistor. Resistors and current collectors that are electrically connected to the terminals on the board are provided on concentric circles, and the slider can slide on the resistors and current collectors on the rotating shaft to which the sliders are attached. In the variable resistor that is attached to the substrate and in which the rotating shaft and the slider rotate integrally by a shaft inserted into the center hole of the rotating shaft,
An annular protrusion that protrudes concentrically with the bearing hole is provided on the back surface of the substrate, and an inner peripheral surface of the protrusion functions as a bearing of the shaft;
A variable resistor. Variable resistor 請 Motomeko 2 wherein you, characterized in that said annular protrusion having the same inner diameter as the central hole of the rotary shaft.   4. The variable resistor according to claim 1, wherein the annular protrusion is fitted into a hole of a printed circuit board.

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