KR100460169B1 - Rotary type variable resistor - Google Patents

Abstract

(Problem) Providing a heat radiation fin on the mounting plate itself by surface contact between the ceramic substrate and the attachment plate to improve heat dissipation, and at the same time, to study the arrangement of the heat radiation fin, to provide a high reliability and small sized rotary variable resistor. It is a task.

(Solution means) The bearing portion 10 rotatably supporting the operation shaft 11, the ceramic substrate 2 on which the resistor 3 is formed, and the ceramic substrate 2 are attached to the bearing portion 10. The attachment plate 1 is provided, and the attachment plate 1 is provided to the plate-shaped pressing part 1a, the 1st heat radiation fin 1b integrally formed in this pressing part 1a, and the bearing part 10 side. It has an extended attachment leg 1c, and the attachment plate 1 is fixed to the bearing part 10 by the attachment leg 1c, and this ceramic substrate is a state in which the pressing part 1a was surface-contacted to the ceramic substrate 2 It is set as the structure which supports (2) between the bearing parts 10. FIG.

Description

Rotary Variable Resistor {ROTARY TYPE VARIABLE RESISTOR}

The present invention is preferably used for a fader volume used in a vehicle-mounted stereo, a volume control of a game machine, and the like, and relates to a rotary variable resistor using ceramic on a substrate on which a resistor is installed.

11 is a side view of a conventional rotary variable resistor, and FIG. 12 is an exploded perspective view of a mounting plate, a ceramic substrate, and a leaf spring of a conventional rotary variable resistor.

Referring to FIGS. 11 and 12, a conventional rotary variable resistor will be described with reference to FIGS. 11 and 12. The mounting plate 51 may be made of a metal material, and may have a cylindrical upper portion 51a formed of a cylindrical metal plate, and the axial direction in the cylindrical upper portion 51a. It has a some attachment leg 51b which protrudes.

The ceramic substrate 52 forms a thin plate shape formed by firing ceramic, and the surface portion 52a has a horseshoe-shaped resistor 53, a current collector 54, and the resistor 53 and a current collector 54. The lead-out part 55 connected is formed. The ceramic substrate 52 is provided on both sides so as to face each other with the mounting plate 51 therebetween, and the surface portion 52a is in contact with the edge portion 51c of the cylindrical portion 51a.

The leaf spring 56 is made of a ring-shaped metal material, and a plurality of convex portions 56a are formed. The back surface portions 52b and 52b of the ceramic substrates 52 and 52 are in elastic contact with each other.

The bearing portion 57 is made of a metal die cast, has a substantially box-shaped base portion 57b which also serves as a heat radiating fin 57a, and a cylinder portion 57c protruding in the axial direction from the base portion 57b. In this cylinder portion 57c, an operation shaft 58 having a sliding seat (not shown) having a sliding member (not shown) is rotatably inserted. The bearing part 57 is fixed in the state which pinched | interposed the ceramic board | substrate 52 and the leaf spring 56 by caulking the attachment leg 51b of the attachment plate 51 to the notch part 57d. At this time, since the leaf spring 56 is disposed between the bearing portion 57 and the ceramic substrate 52, the impact generated when the attachment leg 51b is caulked is absorbed by the leaf spring 56 and the ceramic The substrate 52 is prevented from cracking. In addition, the sliding receiver (not shown) is located in the cylindrical portion 51a, and the sliding member (not shown) is a resistor 53,53 of the pair of ceramic substrates 52,52 by the rotation of the operation shaft 58. ), The resistance between the lead portions 55 and 55 is varied.

The rear radiator 59 has a disk-shaped circular plate portion 59a and a plurality of heat dissipation fins 59b extending in the axial direction from the circular plate portion 59a. The rear heat radiator 59 is fixed to the attachment plate 51 by attaching the leg 51b to the circular plate portion 59a while the ceramic substrate 52 and the plate spring 56 are sandwiched therebetween. . At this time, since the leaf spring 56 is disposed between the rear radiator 59 and the ceramic substrate 52, the impact generated when the attachment leg 51b is caulked is absorbed by the leaf spring 56, and the ceramic The substrate 52 is prevented from cracking.

Conventional rotary variable resistors have the above-described configuration, and are used as, for example, a volume control fader volume of a vehicle-mounted stereo, and are used by flowing a large current, so that heat resistance is required. Therefore, the conventional rotary variable resistor adopts a structure in which ceramics are used as the substrate material to improve heat resistance, and also radiate heat by radiating heat with the heat radiation fins 57a and 59b. The ceramic is excellent in heat resistance but very hard, and therefore has a property of being vulnerable to pressure from the outside, and thus, plate springs 56 and 56 are provided as buffer members. Then, when the operation shaft 58 is rotated, the resistance value between the lead portions 55 changes, so that the output voltage value is variable and the volume can be adjusted.

Conventional rotary variable resistors are configured to radiate heat with heat radiating fins 57a and 59b. Since heat radiating fins 57a and 59b have high heat radiating properties, heat is conducted through the leaf springs 56, resulting in poor heat dissipation. there is a problem. In addition, heat is transferred from the ceramic substrate 52 to the attachment plate 51 to radiate heat through the attachment plate 51. The surface portion 52a of the ceramic substrate 52 is an edge of the cylindrical portion 51a. Since it is in contact with the part 51c and heat conduction is not carried out efficiently, and the shape of the attachment plate 51 is cylindrical, there is a problem that the contact surface is small and heat dissipation is difficult in this shape. In addition, since the rear radiator 59 having the heat dissipation fins 59b is formed to protrude to the rear side, there is a problem in that it is enlarged in the axial direction.

The present invention improves heat dissipation by forming a heat dissipation fin on the attachment plate itself by surface contact between the ceramic substrate and the attachment plate, and at the same time, studies the arrangement of the heat dissipation fin to provide a highly reliable, thin and compact rotary variable resistor. It aims to do it.

1 is a side view of a rotary variable resistor of the present invention,

2 is a cross-sectional view of an essential part of a rotary variable resistor of the present invention;

3 is a front view of an attachment plate of the rotary variable resistor of the present invention;

Figure 4 is a side view of the mounting plate of the rotary variable resistor of the present invention,

5 is a bottom view of the attachment plate of the rotary variable resistor of the present invention;

6 is a top view of a ceramic substrate of a rotary variable resistor of the present invention;

7 is a top view of a bearing part of the rotary variable resistor of the present invention;

8 is an enlarged view of an essential part of a bearing part of a rotary variable resistor of the present invention;

9 is a side view of a bearing part of the rotary variable resistor of the present invention;

10 is a bottom view of a bearing portion of the rotary variable resistor of the present invention,

11 is a side view of a conventional rotary variable resistor,

12 is an exploded perspective view of a mounting plate of a conventional rotary variable resistor, a ceramic substrate, and a leaf spring.

Explanation of symbols on the main parts of the drawings

1: Attaching Plate 1a: Pressing Part

1b: 1st heat radiation fin 1c: attachment leg

1d: snap leg 1e: through hole

2: ceramic substrate 2a: through hole

3: resistor 4: current collector

5: withdrawal part 6: insulation member

7: terminal portion 10: bearing portion

10a: donation 10b: donation

10c: recess 10d: first side wall portion

10e: second side wall portion 10f: insertion hole

10g: storing part 10h: mounting part

10k: Convex part 10m: Hanging concave part

10n: rotation fixing protrusion 10p: second heat radiation fin

10q: abutting surface 10r: protrusion

11: operating shaft 11a: shaft portion

11b: flange 11c: rotation fixing protrusion

12: sliding receiver 12a: gas

12b: projection 13: slider

13a: Sliding part K: Connector part

S: gap

As a first means for solving the above problems, the rotary variable resistor of the present invention includes a bearing portion rotatably supporting an operation shaft, a ceramic substrate on which a resistor is formed, and an attachment plate attaching the ceramic substrate to the bearing portion. And the attachment plate has a flat plate pressing portion, a first heat dissipation fin formed integrally with the pressing portion, and an attachment leg extending toward the bearing portion side, wherein the attachment plate has the attachment leg at the bearing portion. It is set as the structure which supports this ceramic substrate with the said bearing part in the state which the said press part contacted with the said ceramic substrate by surface fixing.

Further, as a second solution, the first heat dissipation fin of the rotary variable resistor of the present invention is configured to be bent and extended toward the bearing portion side.

Further, as a third solution, the first heat dissipation fin of the rotary variable resistor of the present invention is configured to extend in parallel with the axial direction of the operation shaft.

Further, as a fourth solution, the concave portion for accommodating the first heat dissipation fin is formed in the bearing portion of the rotary variable resistor of the present invention.

Further, as a fifth solution, a gap is formed between the recess and the first heat dissipation fin of the rotary variable resistor of the present invention.

In addition, as a sixth solution means, the bearing portion of the rotary variable resistor of the present invention is made of a metal material, it is configured to dissipate heat of the ceramic substrate.

Further, as a seventh solution, a second heat dissipation fin is formed in the bearing portion made of the metal material of the rotary variable resistor of the present invention, and the second heat dissipation fin is engaged with a gap with the first heat dissipation fin. .

Further, as an eighth solution, the bearing portion of the rotary variable resistor of the present invention has a mounting portion having a flat surface, and the ceramic substrate is arranged in surface contact between the mounting portion and the pressing portion.

Embodiment of the Invention

1 is a side view of the rotary variable resistor of the present invention, Figure 2 is a cross-sectional view of the main part of the rotary variable resistor of the present invention, Figure 3 is a rotary type of the present invention 4 is a front view of the mounting plate of the variable resistance resistor, FIG. 4 is a side view of the mounting plate of the rotary variable resistor of the present invention, FIG. 5 is a bottom view of the mounting plate of the rotary variable resistor of the present invention, and FIG. 7 is a top view of a ceramic substrate of a rotary variable resistor, FIG. 7 is a top view of a bearing part of the rotary variable resistor of the present invention, FIG. 8 is an enlarged view of a main part of a bearing of the rotary variable resistor of the present invention, and FIG. 10 is a side view of the bearing portion of the rotary variable resistor of the present invention, and FIG. 10 is a bottom view of the bearing portion of the rotary variable resistor of the present invention.

1 to 10, the attaching plate 1 is made of metal, and one of the substantially square flat plate pressing portion 1a and the pressing portion 1a is explained. A first heat dissipation fin 1b composed of a plurality of protrusions protruding upward from the side edges, two attachment legs 1c protruding upward from the pair of side edges of the pressing portion 1a, respectively, and this attachment leg 1c It has a snap leg (1d) formed so as to project downward from each of the pair of side edges formed, and a through hole (1e) formed in the center of the pressing portion (1a). And, the heat-dissipating fin refers to a portion protruding from the base such as a fin to increase the surface area in contact with the outside air, and is not limited to the form of forming a plurality of protrusions, if the shape can earn a surface area concave convex plane The bent form or the form which protrudes in the direction orthogonal to a side edge in the plate surface direction of the press part 1a may be sufficient.

The ceramic board | substrate 2 is formed by baking a ceramic, forms a substantially rectangular thin plate, and has the through-hole 2a in the center. Although ceramics are excellent in heat resistance, they are very hard and therefore vulnerable to pressure from the outside. The resistors 3 are made of a metal gray-based material in which conductive powders such as ruthenium oxide are mixed in the glass frit, form an arc shape, and two prints are formed on the upper surface of the ceramic substrate 2. In addition, the current collector 4 is made of a low-resistance metal gray-based material in which an alloy of silver and palladium is mixed in a glass frit, printed in an arc shape, the outermost periphery of the resistor 3, and through holes. It is formed in the vicinity of (2a). Further, the lead portion 5 is connected to the resistor 3 and the current collector 4, respectively, and is formed to be printed outwardly.

The insulating member 6 is formed of a molded product made of synthetic resin, extends in parallel with the side of the short side of the ceramic substrate 2, and has an L-shaped cross section. The insulating member 6 has a plurality of terminal portions. (7) is embedded and the connector part K is formed. The connector portion K is attached to the side of the short side of the ceramic substrate 2 by a desired means such as snap fastening, and the plurality of terminal portions 7 are electrically connected to the lead portion 5 by a method such as pressure welding or soldering. It can be connected to an external device to output an electrical signal.

In this way, the ceramic substrate 2 in which the connector portion K is integrated is supported in a state of being in close contact with the pressing portion 1a of the attachment plate 1 and in surface contact. Since surface contact is performed in this way, although it demonstrates in detail later, heat dissipation is improved.

The bearing portion 10 is formed of zinc die-cast by casting, and has a substantially cylindrical box portion 10a, a cylindrical tube portion 10b extending upwardly from the base portion 10a and having an insertion hole 10f. And a plurality of recesses 10c formed of notches formed in the first sidewall portion 10d of the base 10a, and the second heat dissipation fins 10p are formed by the plurality of recesses 10c. In addition, the pair of second side wall portions 10e constituting the base 10a are configured to form a substantially cylindrical accommodating portion 10g, and as shown in FIG. 10, the lower surface side forms a substantially circular arc-shaped flat surface. It has a mounting part 10h and the convex part 10k formed in this mounting part 10h. Two convex parts 10k are formed in the mounting part 10h, and are arrange | positioned at equal intervals so that the line which connected each convex part 10k may become substantially square. And this convex part 10k is comprised by the cylinder of diameter 0.3mm and height 0.1mm. In addition, a rotation fixing protrusion 10n is formed on the lower surface of the base 10a, and a plurality of locking recesses 10m are formed on the upper surface of the base 10a. In addition, six projections 10r having abutting portions 10q in contact with the upper surface of the attachment plate 1 are formed on the lower surface of the mounting portion 10h.

The bearing part 10 which has such a structure is arrange | positioned so that the attachment plate 1 may be covered. Referring to FIG. 8, the 1st heat radiation fin 1b is each accommodated in each recessed part 10c, and the attachment leg ( 1c) is bent at the locking recess 10m to be attached to the attachment plate 10. At this time, the second heat dissipation fin 10q meshes with the first heat dissipation fin 1b. Further, the first heat dissipation fin 1b is in a state extending in parallel with the axial direction, which is the direction in which the tube portion 10b extends, and the downsizing in the radial direction, which is a direction orthogonal to the axial direction, is achieved. Moreover, since the 1st heat radiation fin 1b is arrange | positioned in the recessed part 10c, miniaturization is aimed also in the axial direction. Further, in a state in which the bearing portion 10 is attached to the attachment plate 1, the gap S between the first heat dissipation fin 1b and the recess 10c (the second heat dissipation fin 10p) is the first heat dissipation. It is in the state formed over the outer periphery of the fin 1b, and since there exists a clearance S in this way, as demonstrated later, the heat dissipation of the 1st heat radiation fin 1b and the 2nd heat radiation fin 10p becomes high. It is supposed to be.

As shown in FIG. 2, the ceramic substrate 2 is disposed between the mounting portion 10h of the bearing portion 10 and the pressing portion 1a of the mounting plate 1, and the mounting portion 10h and the ceramic substrate ( 2) is in a state where the surfaces are opposed to each other, and the convex portion 10k is pressed by the pressure when bending the attaching leg 1c and the ceramic substrate 2 and the convex portion 10k are in close contact with each other. That is, since the ceramic substrate 2 is very hard, it has a property of being vulnerable to pressure from the outside, and there is a risk that cracking, breakage, or the like occurs due to the pressure when bending the attaching leg 1c. Therefore, the convex portion 10k is used as the buffer member to absorb the pressure, and the pressure applied directly to the ceramic substrate 2 is alleviated, thereby preventing the ceramic substrate 2 from cracking or breaking. In addition, when the pressure is applied, the attachment plate 1 abuts against the abutting surface 10q, so that a large pressure when bending and attaching the attachment leg 1c to the ceramic substrate 2 is not applied. The pressure for pressing (10k) is only applied, and even in this sense, a large pressure is not applied to the ceramic substrate 2. 1 and 9, when the thickness of the ceramic substrate 2 is L1 and the height of the convex portion 10k after being pressed is set to L2 and the height of the convex portion 10k before being pressed is set to L3, L1 + L3>. L1 + L2> L1.

The pressure from the convex portion 10k is preferably applied to the ceramic substrate 2 on an average, and the convex portion 10k is disposed at equal intervals so as to form a substantially square, so that the convex portion 10k is not biased to one side. Is pressed so that the pressure is not concentrated on a part of the ceramic substrate 2. Moreover, since the bearing part 10 is comprised by zinc die-cast, it is comparatively soft among metals, and the convex part 10k is easy to be pressed, and it is easy to absorb a pressure. Moreover, since the convex part 10k is formed in the vicinity of the attachment leg 1c, it is comparatively easy to add weight and it is easy to be pressed. If the pressure from the convex portion 10k is applied to the ceramic substrate 2 on average, the convex portion 10k may be arranged to form an equilateral triangle or may be arranged to form an equilateral polygon. In addition, it is not necessary to necessarily set it as an equilateral triangle etc., You may make it plural sets of pair of convex part 10k arranged in a pair of mounting part 10h.

The operating shaft 11 is made of a rod-shaped metal material, the flange portion 11b formed at the lower end of the shaft portion 11a and the shaft portion 11a, and the rotation fixing protrusion 11c formed so that a part of the flange portion 11b protrudes. Have The slide receiving body 12 has a base 12a which consists of a plate-shaped cylinder, and the protrusion 12b which protrudes below this base 12a. The sliding member 13 has a plurality of sliding member pieces 13a, and is attached to the sliding receiver 12 through means such as caulking and embedding. The slide receiving body 12 integrated with the sliding member 13 is fixed to the flange portion 11b of the operating shaft 11 by means of fitting or bonding, so as to be integral with the operating shaft 11. have.

Moreover, the protrusion 12b opposes the upper surface of the ceramic substrate 2 with a slight gap, and the edge part which regulates the movement below the operation shaft 11 is formed in the middle part. Further, when the variable resistor of the present invention is mounted on a printed board (not shown), the tip end surface of the projection 12b is positioned so as to face the plate surface of the printed board with a slight gap. Therefore, when the variable resistor of the present invention is mounted on a printed board, even if a large weight is applied to the operating shaft 11, the weights applied to the ceramic board 2 in contact with the printed board 12b are alleviated. .

The operation shaft 11 to which the slide receiver 12 is fixed as described above has the shaft portion 11a inserted into the insertion hole 10f of the bearing portion 10 and the projection 12b of the slide receiver 12 is It is rotatable by being inserted into the through hole 1e and the through hole 2a. Moreover, in the storage part 10g, the slide receiving body 12 is in a state rotatable, and the sliding piece 13a is sliding-contacted on the resistor 3 and the electrical power collector 4, as shown in FIG. It is in a state. Then, when the operation shaft 11 is rotated, the sliding element 13a slides on the resistor 3 and the current collector 4, so that the resistance value between the lead portions 5 changes so that the output voltage changes. . When the operating shaft 11 is rotated, the rotating fixing protrusion 11c of the operating shaft 11 and the rotating fixing protrusion 10n of the bearing portion 10 collide with each other, so that the rotation range of the operating shaft 11 is determined. It is supposed to be.

The rotatable variable resistor of the present invention has the above configuration, and is used as a so-called fader control volume for volume control of front and rear speakers such as stereo mounted on a vehicle, and a large current flows through a line connected directly in front of the speaker on a circuit. This results in a very high temperature. Therefore, in the rotary variable resistor of the present invention, a metal gray resistor 3 and a current collector 4 are used. In this case, since the firing temperature is 500 ° C. or higher, the ceramic is used as a material for the substrate. The heat resistance of the city is improved. In the operation of the variable resistor of the present invention, since the resistor 3 and the current collector 4 become hot due to joule heat or the like, they are emitted from these resistors 3 and applied to the ceramic substrate 2. You need to dissipate losing heat. Therefore, in the rotary variable resistor of the present invention, the pressing portion 1a of the attachment plate 1 and the lower surface of the ceramic substrate 2 are brought into surface contact, and the thermal conductivity efficiency from the ceramic substrate 2 to the attachment plate 1 is maintained. The heat dissipation is efficiently performed from the first heat dissipation fin 1b. In addition, as shown in FIG. 8, the first heat dissipation fin 1b is exposed to the outside air because of the gap S, and the heat dissipation efficiency is further improved. In addition, since the upper surface of the ceramic substrate 2 is in contact with the convex portion 10k of the bearing 10 in contact with each other, heat of the ceramic substrate 2 is conducted to the bearing portion 10 made of die cast. The heat dissipation can be carried out in the whole bearing part 10, and further heat dissipation can be performed. In addition, since the second heat dissipation fin 10p is formed in the bearing portion 10 while being exposed to the outside air with a gap S, the heat dissipation can be efficiently performed even through the second heat dissipation fin 10p.

The rotary variable resistor of the present invention having such a configuration is attached to the printed circuit board disposed in the stereo case by snap-in 1d of the attachment plate 1, and is attached by soldering by dip or the like. A handle (not shown) is press-fitted to the tip of (11). When the knob is rotated, the operation shaft 11 rotates, the resistance value between the lead portions 5 changes, and the output voltage value of the connector K is variable, so that the volume can be adjusted.

Although the rotational variable resistor of the present invention has the above-described configuration and operation, the present invention is not limited to the above-described configuration, and in the embodiment, the first heat dissipation fin 1b has been described as an example in which the recess 10k is housed. The 1 heat radiation fin may extend beyond the bearing portion 10 to the operation shaft 11 side. In addition, in the said embodiment, although the 1st heat radiation fin 1b is extended to the bearing part 10 side, and is parallel to an axial direction, the form extended to parallel with the pressing part 1a of the attachment plate 1, a bearing part It may be in the form extended to the opposite side to (10).

In the above embodiment, the bearing portion 10 has been described as being made of zinc die cast, but may be made of aluminum die cast. Also in this case, since the convex part 10k is very small, it is pressed easily and has a function as a shock absorbing member. In addition, the bearing portion 10 does not necessarily need to be die-cast, and may be formed of a molded article of an insulating member. In this case, the heat dissipation effect of the bearing portion 10 is hardly obtained, but heat can be radiated from the attachment plate 1. . In addition, although the form which formed the 2nd heat dissipation fin 10p by forming a plurality of recessed parts 10c in the said embodiment was demonstrated, one recessed part 10c is formed and the 1st heat radiation fin 1b is accommodated in it. It may be in the form of.

In addition, in this embodiment, although the upper surface of the mounting part 10h and the ceramic substrate 2 has some clearances, you may make surface contact of both by pressing the convex part 10k further.

In addition, although the attachment plate 1 was demonstrated to be made of metal, the thing which was bent by press-processing one metal plate, and the thing formed by die-casting are also included. In addition, although the recessed part 10c of the bearing part 10 was demonstrated by the structure which notches the 1st side wall part 10d, the recessed part is formed by forming a hole from the lower end surface of the 1st side wall part 10d, You may make it insert the 1st heat radiation fin 1b in the inside. In this way, even if the heat radiation fin 1b is made of a thin metal plate, the risk of bending the heat radiation fin due to the pressure from the outside is reduced.

The rotary variable resistor of the present invention includes a bearing portion rotatably supporting the operation shaft, a ceramic substrate, and an attachment plate, wherein the attachment plate extends toward the plate-shaped pressing portion, the first heat dissipation fin, and the bearing portion. It has an attachment leg, and the attachment plate is fixed to the said bearing part, and it is set as the structure which supports this ceramic substrate with the bearing part in the state in which the pressing part was surface-contacted with the ceramic substrate, As a result, heat conduction is performed and heat is radiated smoothly from the first heat dissipation fin, thereby providing a rotational variable resistor having high reliability of operation.

In addition, since the first heat dissipation fin of the rotary variable resistor of the present invention is configured to be bent and extended toward the bearing portion side, the first heat dissipation fin and the bearing portion overlap in the axial direction, and thus, the small rotary variable resistor in the axial direction. Can be provided.

In addition, since the first heat dissipation fin of the rotary variable resistor of the present invention is configured to extend in parallel with the axial direction of the operation shaft, miniaturization of the radial direction, which is a direction orthogonal to the axial direction, is achieved, for example, on a printed board. When a rotary variable resistor is attached, high-density mounting can be realized by eliminating interference with other electrical components.

In addition, since the concave portion for accommodating the first heat dissipation fin is formed in the bearing portion of the rotary variable resistor of the present invention, since the first heat dissipation fin stays in the concave portion, the first heat dissipation fin does not protrude outward. Miniaturization can be achieved. In addition, the risk that the pressure from the outside is applied directly to the first heat dissipation fin is reduced to prevent deformation of the fin.

In addition, since a gap is formed between the concave portion of the rotary variable resistor of the present invention and the first heat dissipation fin, the first heat dissipation fin does not come into direct contact with the outside air, thereby further improving heat dissipation.

In addition, since the bearing portion of the rotary variable resistor of the present invention is made of a metal material and is configured to dissipate heat from the ceramic substrate, heat is also radiated through the bearing portion, so that the rotary variable resistor having higher heat dissipation can be provided. .

In addition, since the second heat dissipation fin is formed in the bearing portion made of the metal of the rotary variable resistor of the present invention, and the second heat dissipation fin is configured to be engaged with the first heat dissipation fin with a gap therebetween, even through the bearing portion. Heat dissipation can be performed. In addition, since both of the first and second heat dissipation fins directly contact the outside air, the heat dissipation is further improved.

In addition, since the bearing portion of the rotary variable resistor of the present invention has a mounting portion, and the ceramic substrate is arranged in surface contact between the mounting portion and the pressing portion, the ceramic substrate is also in surface contact with the mounting portion. It is in surface contact, and heat dissipation becomes more favorable.

Claims (8)

A bearing portion rotatably supporting the operation shaft, a ceramic substrate having a resistor formed thereon, and an attachment plate for attaching the ceramic substrate to the bearing portion, The attachment plate has a flat plate pressing portion, a first heat dissipation fin formed integrally with the pressing portion, and an attachment leg extending to the bearing portion side, The attaching plate is fixed to the bearing portion, so that the ceramic substrate is supported between the bearing portion while the pressing portion of the attaching plate is brought into surface contact with the ceramic substrate. Variable resistor. The variable resistance resistor of claim 1, wherein the first heat dissipation fin is bent and extended to the bearing portion side. The rotary variable resistor according to claim 1, wherein the first heat dissipation fin extends in parallel with the axial direction of the operation shaft. The variable resistance resistor according to claim 1, wherein the bearing portion is formed with a recess for accommodating the first heat dissipation fins. 5. The rotary variable resistor according to claim 4, wherein a gap is formed between the recess and the first heat dissipation fin. The variable resistance resistor of claim 1, wherein the bearing part is made of a metal material and dissipates heat of the ceramic substrate. 7. The rotary variable resistor according to claim 6, wherein a second heat dissipation fin is formed in the bearing portion made of the metal material, and the second heat dissipation fin is engaged with a gap with the first heat dissipation fin. 7. The variable resistance resistor according to claim 6, wherein the bearing portion has a mounting portion having a flat surface, and the ceramic substrate is disposed in surface contact between the mounting portion and the pressing portion.