JP2003109808A - Varistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a varistor where unnecessary apertures are not formed at its cover and the immersion of small foreign materials can be prevented and further there is no risk of causing deformation in a slider that is an internal component when assembling the cover to a substrate. SOLUTION: In this varistor, a resistance value is adjusted by sliding a first contact strip and a second contact strip of the slider on a collector and a resistor that are concentrically provided on the surface of the substrate. The substrate A is covered with the cover 20, and the cover 20 comprises first protruding parts 22 and second protruding parts 23. Through-holes 20a opening in a transverse direction are formed at the first protruding parts 22 and the through-holes 20a engage with protrusions formed at a side of the substrate. The second protruding parts 23 come into face contact with the side of the substrate merely by the face and never engage with each other.

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. 5, a substrate 100 made of a resin molded product has a central hole 101, and terminals 112 and 113 are embedded therein. The ends 112a and 113a of the terminals 112 and 113 protrude from the side surface of the substrate 100, and the other ends 112b and 113b.
Is exposed on the upper surface of the substrate 100. On the substrate 100, the current collector 104 has an annular shape, and the resistor 105 has an almost annular shape.
It is formed on concentric circles. Current collector 104 is terminal 112
The other end portion 105a of the resistor 105, which is connected to the other end portion 112b of the resistor 105, is connected to the other end portion 113b of the terminal 113 via the extraction electrode 106.

A rotary shaft 107 having a slider 108 made of a conductive material is rotatably mounted in the center hole 101 of the substrate 100. The 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.
The resistance value between the terminals 112 and 113 is adjusted according to the rotational position of b.

A cover 109 made of a resin molded product is mounted on the substrate 100. This cover 10
Reference numeral 9 denotes an engaging claw 109a that engages with the rear edge of the substrate 100.
Are formed as shown in FIG. That is, when the cover 109 is resin-molded using the molds 121 and 122 shown in FIG. 16, the engaging claw 109a is the pin portion 12 of the mold 121.
Although it is formed by 1a, an opening 109b is formed at the trace of the pin portion 121a coming off. 12
Six openings 109b are shown in FIG.

[0005]

By the way, FIGS.
In the variable resistor shown in FIG. 5, the opening 109b is unavoidably formed in the trail of the pin portion 121a for forming the engaging claw 109a, so that dust or the like may enter the inside of the cover 109 through the opening 109b. Therefore, such fine foreign matter easily enters, and problems such as contact failure of the slider 108, short circuit, and deterioration of rotation life occur.

Further, when the cover 109 is attached to the substrate 100, the cover 109 may tilt irregularly,
For example, when the cover 109 tilts in the direction of the arrow Y shown in FIG. 13, the ceiling portion of the cover 109 causes the contact piece 108 of the slider 108 to move.
There is also a problem that the contact piece 108a is deformed by pressing a.

Therefore, an object of the present invention is to provide a variable resistor capable of preventing intrusion of fine foreign matter without forming an opening penetrating inside the unnecessary variable resistor in the cover. is there.

Another object of the present invention is to provide a variable resistor in which a slider, which is an internal component, is not likely to be deformed when a cover is attached to a substrate.

[0009]

In order to achieve the above object, a variable resistor according to a first aspect of the present invention includes a resistor and a resistor electrically connected to terminals on a substrate made of a resin material. A current collector is provided on a concentric circle, a rotary shaft having a slider is attached to the substrate so that the slider can slide on the resistor and the current collector, and the substrate is covered with a cover made of a resin material. In the covered variable resistor, a first engaging portion is formed on a side surface of the substrate, and a second engaging portion engages with the first engaging portion on a protrusion provided on a side portion of the cover. Is formed so that there is no opening penetrating inside the variable resistor in the vicinity of the projecting piece.

In the present specification, the inside of the variable resistor specifically means a space formed between the surface of the substrate and the cover covering the substrate.

In the variable resistor according to the first aspect of the present invention, the second engaging portion formed on the projecting piece of the cover is formed so that there is no opening penetrating inside the variable resistor in the vicinity of the projecting piece. As a result, the dust-proof property inside the cover is secured, and intrusion of minute foreign matter is prevented.

In particular, by forming the second engaging portion as a through hole formed in the projecting piece in the thickness direction thereof, the trace of the pin portion provided in the mold at the time of resin molding of the cover has a trace of the vicinity of the projecting piece. Never remains. The through hole can be easily formed by providing a movable member that can move forward and backward from the side on the side wall of one of the molds when the cover is resin-molded.

In the variable resistor according to the second aspect of the present invention, a resistor and a current collector electrically connected to the terminals are provided on a substrate made of a resin material in a concentric circle, and a slider is provided. In the variable resistor in which the attached rotating shaft is attached to the substrate so that the slider can slide on the resistor and the current collector, and the substrate is covered with a cover made of a resin material, a first resistor is provided on a side surface of the substrate. And a second engaging portion that engages with the first engaging portion is formed as a through hole formed in a thickness direction of the protruding piece on the side portion of the cover. However, this through hole is formed by a movable member which can be advanced and retracted from the side in a side wall portion of one mold when the cover is resin-molded.

The operation of the variable resistor according to the second invention is basically the same as the operation described for the variable resistor according to the first invention.

Further, in the variable resistor according to the third aspect of the present invention, the resistors electrically connected to the terminals and the current collectors located inside the resistors are concentrically formed on the substrate made of a resin material. The first contact piece of the slider is slidable on the resistor and the second contact piece of the slider is slidable on the current collector with the rotary shaft having the slider attached thereto. Attached to the substrate,
In a variable resistor in which a cover made of a resin material covers the substrate, first and second projecting pieces located on a side surface of the substrate are formed on a side portion of the cover, and the first projecting piece includes the substrate. A second engaging portion that engages with the first engaging portion formed on the side surface of the second projecting piece, and the second projecting piece does not have the engaging portion.
Is a first piece of the slider at the time of initial setting of assembly.
Is provided farther from the position of the contact piece than the first projecting piece.

In the variable resistor according to the third aspect of the present invention, the cover is pressed against the substrate to form the second protrusion on the first protrusion.
The engaging portion of is engaged with the first engaging portion formed on the side surface of the substrate. A constant engagement force is required for this engagement. On the other hand, the second projecting piece is located on the side surface of the substrate without particularly requiring the engaging force. At this time, assuming that the cover is inclined with respect to the substrate, the second
Since the projecting piece of the second tilts in a state of sinking first, if the second projecting piece is provided at a position apart from the first contact piece located on the outer side, the cover deforms the first contact piece. There is no fear.
Further, since the second contact piece is located inside, there is no possibility of deformation even if the cover is slightly inclined in this way.

In the variable resistor according to the third aspect of the present invention, the second engaging portion formed on the first protrusion has an opening penetrating inside the variable resistor in the vicinity of the first protrusion. If it is formed so that it does not exist, it is possible to prevent the entry of minute foreign matter, like the variable resistor according to the first and second aspects of the invention. Further, the second engaging portion may be a through hole formed in the first projecting piece in the thickness direction thereof, and this through hole is laterally provided on the side wall portion of one mold during resin molding of the cover. It can be easily formed by providing a movable member that can move back and forth.

[0018]

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 includes 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-formed product. The substrate 10 has a central hole 11 and has terminals 12, 13
Is buried. The terminal 12 has an end 12a on the substrate 1.
0 is projected from the side surface, 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 ends 15a of the resistor 15 that oppose each other are the other end of the terminal 13. 13b is connected. Further, 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 can be made of the same conductive resin material as the resistor 15 and applied simultaneously with 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 11 of the substrate 10. The slider 35 is made of a conductive metal material, and elastically moves between the brush-shaped first contact piece 35a that slides elastically on the resistor 15 in a pressed state and the current collector 12b (the lubricating layer 14). And a brush-shaped second contact piece 35b that slides in a pressure contact state.

As shown in FIG. 1A, the center 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
The resistance value between the terminals 12 and 13 is adjusted by changing the contact position of the resistor 5 and the current collector 12b of 5b.

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. The snap-in method is a joining method in which two engaging parts are forcibly fitted by the elasticity of resin etc., and special processing is required compared to other joining methods such as caulking, welding, welding and brazing. Therefore, it is easy to assemble and is excellent in mass productivity and cost.

More specifically, as shown in FIG. 6, the side surface of the substrate 10 is formed with an engaging projection 10a whose upper side is inclined, and the projection is provided on the first projection 22 provided on the side of the cover 20. 1
A through hole 20a that engages with 0a is formed in the thickness direction of the protruding piece 22, and the through hole 20a engages with the protruding portion 10a by a snap-in method. This through hole 20a is, as shown in FIG.
When resin molding the cover 20 using the molds 51 and 52,
The mold 51 is provided with a movable pin member 53 that can move forward and backward from the side, and is formed as a trace of the pin member 53.

As shown in FIG. 3, the engaging projections 10a are formed at four positions on the side surface of the substrate 10 in the slightly recessed recesses 10b, and the first projections 22 are formed in the recesses 10b.
Is formed in a state in which the elasticity required for engaging with the snap-in method is retained in correspondence with. Then, the through hole 20
Since a is formed by the pin member 53 that advances and retracts from the side, an opening 109b that is a trace of the pin 121a shown in FIG. 16 is formed on the surface of the cover 20 (FIG. 12).
(See (A)) Therefore, a minute foreign substance does not enter the cover 20 to cause a trouble such as a contact failure of the slider 35, a short circuit, or a deterioration of the rotation life.

Further, the cover 20 is formed with a second projecting piece 23 located on the side surface 10c of the substrate 10. The second projecting piece 23 is formed in a comb-teeth shape in order to avoid interference with the terminals 12 and 13, and only makes a surface contact with the side surface 10c but does not engage with it. As shown in FIG. 2, the end portion of the cover 20 is positioned by the step 25 contacting the surface of the substrate 10.

In addition to the first example shown in FIG. 6, the snap-in type engagement structure between the substrate 10 and the cover 20 is the second example shown in FIGS. 8 and 9 and the third example shown in FIGS. An example may be adopted. Of course, other structures can be adopted.

The second example is an engagement structure composed of a combination of a shallow recess 20d formed in the first projecting piece 22 shown in FIG. 8 and a low engagement projection 10d formed in the recess 10b shown in FIG. is there. The third example is a rectangular bulging portion 20e formed on the first projecting piece 22 shown in FIG. 10 and a concave portion 10b shown in FIG.
The engaging structure is a combination with the step surface 10e formed in the above.

By the way, in the initial stage of the assembling of the slider 35, as shown in FIG.
The second contact piece 35b so that the second contact piece 35b is in contact with position 5 at position A
Is set to contact the current collector 12b (the lubricating layer 14) at the position B. This initial setting state is also shown in FIG. The first protruding piece 22 of the cover 20 is provided at a position relatively close to the first contact piece 35a, and the second protruding piece 23 is provided on the second contact piece 35b side. That is, the second projecting piece 23 is provided farther from the position A of the first contact piece 35a than the first projecting piece 22 at the time of initial setting of assembly.

In the variable resistor of this embodiment, the substrate 1
If the upper surface of the cover 20 is pressed when the cover 20 is attached to the cover 0, the cover 20 tends to sink from the side of the second protrusion 23 that does not engage with the side surface 10c of the substrate 10, and the cover 20 will be temporarily removed. Even if is tilted, it will be tilted in the arrow Y direction shown in FIG. This inclination direction is a direction in which the ceiling portion of the cover 20 moves away from the first contact piece 35a located on the outer side, and there is no risk of the first contact piece 35a deforming. Further, since the second contact piece 35b is located inside, even if the cover 20 is slightly inclined in the arrow Y direction, there is no possibility of deformation.

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

[0034]

As is apparent from the above description, according to the first and second aspects of the present invention, the variable resistor is penetrated into the variable resistor in the vicinity of the protrusion engaging with the engaging portion formed on the side surface of the substrate. Since there is no such opening, the dust-proof property inside the cover is ensured, and it is possible to prevent the entry of minute foreign matter. Therefore, problems such as contact failure of the slider, short circuit, and deterioration of rotational life are eliminated.

According to the third aspect of the invention, even if the cover is tilted when it is attached to the substrate, the tilt affects the first contact piece of the slider, which is located on the outer side and is susceptible to deformation. Moreover, it is possible to obtain a variable resistor having high contact reliability.

Further, in all of the first, second and third inventions, the so-called snap-in method is used for the engagement between the substrate and the cover, so that no special processing is required as compared with other coupling methods. Easy to assemble, excellent in mass productivity and cost.

[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 sectional view showing the variable resistor.

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 a first example of the engagement structure between the substrate and the cover.

FIG. 7 is a cross-sectional view showing a mold for resin-molding the cover.

FIG. 8 shows a cover-side engaging portion in a second example of the engaging structure, (A) is a front view and (B) is a sectional view.

9A and 9B show a board-side engaging portion in a second example of the engaging structure, FIG. 9A being a front view and FIG. 9B being a sectional view.

FIG. 10 shows a cover side engaging portion in a third example of the engaging structure, (A) is a front view and (B) is a sectional view.

FIG. 11 shows a board-side engaging portion in a third example of the engaging structure, (A) is a front view, and (B) is a sectional view.

FIG. 12 shows a conventional variable resistor, (A) is a plan view,
(B) is a side view.

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

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

15 is a cross-sectional view showing an engaging structure of the variable resistor shown in FIG.

16 is a sectional view showing a mold for resin-molding the cover of the variable resistor shown in FIG.

[Explanation of symbols]

10 ... Substrate 10a ... Engaging protrusion (first engaging portion) 12, 13 ... Terminal 12b ... Current collector 15 ... Resistor 20 ... Cover 20a ... through hole (second engaging portion) 22 ... First protrusion 23 ... Second protrusion 30 ... Rotary axis 35 ... Slider 35a ... first contact piece 35b ... second contact piece 51 ... Mold 53 ... Movable pin member

Claims (8)

[Claims] 1. A resistor and a current collector, which are electrically connected to terminals, are concentrically provided on a substrate made of a resin material, and a rotary shaft having a slider is attached to the slider for resistance. A variable resistor in which a body and a current collector are slidably attached to the substrate and the substrate is covered with a cover made of a resin material, wherein a first engaging portion is formed on a side surface of the substrate, A second engaging portion that engages with the first engaging portion is formed on the protrusion provided on the side portion so that there is no opening penetrating inside the variable resistor in the vicinity of the protrusion. A variable resistor characterized by. 2. The second engaging portion is a through hole formed in the protrusion in the thickness direction thereof.
Variable resistor described. 3. The through hole is formed by a movable member which can be moved forward and backward from a side wall of one of the molds when the cover is resin-molded. Variable resistor described. 4. A resistor and a current collector, each electrically connected to a terminal, are concentrically provided on a substrate made of a resin material, and the slider is attached to a rotary shaft to which the slider is resistant. A variable resistor in which a body and a current collector are slidably attached to the substrate and the substrate is covered with a cover made of a resin material, wherein a first engaging portion is formed on a side surface of the substrate, A second engagement portion that engages with the first engagement portion is formed as a through hole formed in the thickness direction of the protrusion on the protrusion provided on the side portion, and the through hole is formed by resin-covering the cover. A variable resistor, characterized in that it is formed by a movable member which can be moved back and forth from the side on the side wall of one of the molds at the time of molding. 5. A rotating body in which a resistor electrically connected to a terminal and a current collector located inside the resistor are concentrically provided on a substrate made of a resin material, and a slider is attached. A shaft is attached to the substrate so that the first contact piece of the slider is slidable on the resistor and the second contact piece of the slider is slidable on the current collector, and a shaft made of a resin material is used. In the variable resistor covering the substrate, first and second projecting pieces located on the side surface of the substrate are formed on a side portion of the cover, and the first projecting piece is formed on the side surface of the substrate. A second engaging portion that engages with the first engaging portion, and does not form an engaging portion on the second projecting piece, and the second projecting piece is the sliding member at the time of initial setting of assembly. A variable resistor, wherein the variable resistor is provided farther from the first contact piece of the child than the first projecting piece. 6. The second engaging portion formed on the first projecting piece is formed so that there is no opening penetrating inside the variable resistor in the vicinity of the first projecting piece. The variable resistor according to claim 5, wherein 7. The variable resistor according to claim 6, wherein the second engaging portion is a through hole formed in the first projecting piece in a thickness direction thereof. 8. The through hole is formed in a side wall portion of one of the molds by a movable member that can move forward and backward when the cover is resin-molded. Variable resistor described.