JPH08229251A - Portable electric equipment with switch - Google Patents

Abstract

PURPOSE: To attain beautiful three-dimensional curved surface constitution by making the cross section curvature radius of the tip part and rear end part of a case sliding surface approximately equal to the cross section curvature radius of a switch knob inner surface in an equipment being turned on and off by the reciprocating motion of the switch knob whose front and back inner surfaces are bent by the different curvature radiuses. CONSTITUTION: In this portable electric equipment such as a shaver or the like for which a switch is turned on and off by moving the switch knob 1 whose front and back inner surfaces are bent by the different curvature radiuses back and forth along a sliding surface, the sliding surface of a case 2 to be mounted so as to let the switch knob 1 move back and forth is divided into the tip part 2A, the rear end part 2B and a center part 2C. Then, the cross section curvature radius of the tip part 2A is made approximately equal to the cross section curvature radius of the tip part 1A of the switch knob inner surface and the cross section curvature radius of the rear end part 2B is made approximately equal to the cross section curvature radius of the rear end part 1B of the switch knob inner surface. Also, a connection hole 3 for which a connection arm for connecting a supporting plate inside the case 2 and the switch knob 1 is disposed is opened at the center part 2C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a portable electric device with a switch, and more particularly to a portable electric device in which a switch is reciprocally mounted on a curved surface of a case.

[0002]

2. Description of the Related Art A portable electric device such as a shaver is provided with a switch knob capable of reciprocating movement on the surface of a case.
The switch knob is an operation unit that turns a switch of a portable electric device on and off. The switch knob is connected to a support plate provided in the case for reciprocating movement,
The support plate is reciprocated to turn the switch on and off.

Many portable electric devices such as shavers are
The switch knob is attached to the flat part of the case. Since the switch knob of the flat portion linearly reciprocates on the plane, the switch knob and the case can be reciprocated so that a facing surface between the case and the case is a flat surface so that there is no gap therebetween. However, if the mounting position of the switch knob is specified on the plane portion of the case, it becomes difficult to freely design the outer shape of the case. In particular, electric appliances in recent years have an outer shape with many curved surfaces in order to have a beautiful design. The curved shape of the case is aesthetically pleasing and is especially prone to women.

[0004]

SUMMARY OF THE INVENTION An electric device having an outer shape of a case as a curved surface and a switch knob mounted on the curved surface for reciprocating movement, has a curved surface of the case when the switch knob is switched to an on / off position. It is necessary to reciprocate along. The switch knob that cannot reciprocate along the curved surface of the case protrudes from the case depending on the operating position,
Alternatively, there is a gap between the switch knob and the case.

Even if the case has a curved surface, the tubular case having the same cross-sectional shape can reciprocate the switch knob along the case. By reciprocating the switch knob in the axial direction of the case, the switch knob can reciprocate along the case without a gap. However, in the case of this shape, the mounting portion of the switch knob needs to be cylindrical, and the surface of the case cannot be a three-dimensional curved surface. For this reason, the outer shape of the case cannot be a free three-dimensional curved surface.

In other words, if a switch knob is attached to a case having a three-dimensional curved surface, that is, a portion where the radius of curvature of the cross-section partially changes, and the switch knob is shaped to follow the three-dimensional curved surface of the case sliding surface, the switch knob When reciprocating the, there is a drawback that a gap is created between the switch knob and the case. By the way, in this specification, the "curvature radius of the cross section" means the radius of curvature of a portion cut in a direction orthogonal to the direction in which the switch knob is reciprocated. When reciprocating on a three-dimensional curved sliding surface, a gap is created between the sliding surface and the switch knob.
This is because it is necessary to match the radius of curvature of the cross section of the switch knob with the portion having the largest radius of curvature of the cross section. For example, the stroke for reciprocating the switch knob is 5 mm.
As for the tip of the switch knob, the radius of curvature of the cross section is 7
mm to 11 mm, and the rear edge of the switch knob has a cross-section radius of curvature of 13 mm to 17 mm.
If the portion that changes to is moved, the radius of curvature of the cross section of the leading edge of the switch knob should be 11 mm and the radius of curvature of the rear edge should be 17 mm. If the cross-sectional radius of curvature of the tip is designed to be 7 mm and the cross-sectional radius of curvature of the rear edge is designed to be 17 mm, both sides will contact smoothly when moved to a part with a small cross-sectional radius of curvature. This is because it cannot reciprocate. When the radius of curvature of the cross section of the switch knob is set to the maximum radius of curvature of the sliding surface, when it is moved to a portion having a small radius of curvature, there is an adverse effect that a gap is formed on both side portions.

The present invention has been developed for the purpose of solving these drawbacks. An important object of the present invention is to mount a switch knob on a three-dimensional curved surface portion of a case so that the case can be reciprocally moved. An object of the present invention is to provide a portable electric device with a switch that can form a mounting portion of a switch knob into a beautiful three-dimensional curved surface. Another important object of the present invention is to use a connecting hole that connects the switch knob and the support plate together with a portion that absorbs a difference in cross-sectional curvature radius between the tip end portion and the rear end portion of the switch knob, An object of the present invention is to provide a portable electric device with a switch that can smoothly reciprocate a switch knob along a three-dimensional curved surface of a case.

[0008]

The portable electric device of the present invention has the following constitution in order to achieve the above-mentioned object.
The portable electric device is equipped with the switch knob 1 so that it can be reciprocated by being exposed on the curved surface of the case 2 having a three-dimensional curved surface. The switch knob 1 is curved so that the inner surfaces before and after the reciprocating motion have different radii of curvature. Further, the sliding surface 2a of the case on which the switch knob 1 is slidably mounted is also curved in a shape along the inner surface of the switch knob 1. The switch knob 1 is configured to reciprocate along the sliding surface 2a to switch the switch on and off.

Further, the portable electric device of the present invention has the following unique structure. (A) The sliding surface 2a of the case 2 on which the switch knob 1 is reciprocally mounted is divided into a front end portion 2A, a rear end portion 2B and a central portion 2C. (B) The radius of curvature of the cross section of the tip 2A of the case sliding surface 2a is substantially equal to the radius of curvature of the cross section of the tip 1A of the switch knob inner surface. (C) The front end portion 2A of the case sliding surface 2a has substantially the same cross-sectional curvature radius. (D) The cross-sectional radius of curvature of the rear end portion 2B of the case sliding surface 2a is substantially equal to the cross-sectional radius of curvature of the switch knob inner surface rear end portion 1B. (E) The rear end portion 2B of the case sliding surface 2a has substantially the same cross-section radius of curvature. (F) The connecting hole 3 is formed in the central portion 2C of the case sliding surface 2a.
Is open. (G) A connecting arm 11 for connecting the switch knob 1 and the support plate 4 in the case is provided in the connecting hole 3.

[0010]

As a portable electric device of the preferred embodiment of the present invention, a ready shaver is exemplified. In the ready shaver shown in the enlarged view of FIG. 1, a switch knob 1 is arranged in a portion curved in a three-dimensional curved surface of a case. FIG. 1 is an enlarged view of a switch portion of the ready shaver shown in FIG.
In the switch knob 1 shown in this figure, the radius of curvature of the cross section of the front end 1A is made small and the radius of curvature of the cross section of the rear end 1B is made large in order to follow the case surface curved in a three-dimensional curved surface. . The case sliding surface 2a is divided into a front end portion 2A, a central portion 2C and a rear end portion 2B. The tip 2A of the sliding surface 2a has the same radius of curvature in cross section as a whole, and is made equal to the radius of curvature of cross section of the tip 1A of the switch knob. The rear end portion 2B also has the same cross-sectional curvature radius as a whole, but is made equal to the cross-sectional curvature radius of the switch knob rear end portion 1B. The switch knob 1 of this structure has a front end portion 1A and a rear end portion 1A in all stroke regions when reciprocating.
B is moved to the same radius of curvature portion of the sliding surface 2a. Therefore, there is no gap between the switch knob 1 and the sliding surface 2a during the reciprocating movement.

Furthermore, the ready shaver shown in the drawing is
A central portion 2C is provided between the front end portion 2A and the rear end portion 2B of the sliding surface 2a having the same cross-sectional radius of curvature, and the connecting hole 3 is opened in the central portion 2C. The opened central portion 2C is a space because the sliding surface of the case is removed. The central portion 2C having no sliding surface is an ideal portion as a connecting portion between the front end portion 2A and the rear end portion 2B of the sliding surface 2a having different cross-section curvature radii. It is not restricted by the shape of the central portion 2C, and the front end portion 2A and the rear end portion 2B of the sliding surface 2a having different cross-section curvature radii are freely designed according to the cross-section curvature radius of the switch knob. Because you can.

If the sliding surface of the case is designed without opening the central portion, it is necessary to design this portion so that the switch knob does not come into contact with it. To simplify the design, when the central portion 2C is designed in a shape that linearly connects the front end portion 2A and the rear end portion 2B, when the switch knob is reciprocally moved, the inner surface having a small cross-sectional curvature radius is in the center. It will contact the portion 2C. In order to prevent this state, it is necessary to make this portion a recess so that the switch knob or the case sliding surface 2a does not come into contact with the central portion. Providing a recess in the center makes the switch knob and case considerably thicker.
This not only makes the case and switch knobs heavier, but it also makes it impossible to design the whole in a smart and compact manner.

In the portable electric device of the present invention, since the central portion 2C of the sliding surface 2a is cut off as the connecting hole 3, there is no such an adverse effect, and the leading end portion 2A and the rear end portion of the sliding surface 2a are eliminated. 2B
It is not necessary to design and have different cross-section curvature radii and connect the differences in shape at the central portion 2C. Furthermore, in the portable electric device of the present invention, since the connecting hole 3 provided in the central portion 2C is also used as the through hole that connects the switch knob 1 to the support plate 4, the connecting hole 3 in the central portion 2C is It can also be used to connect the switch knob 1 to the support plate 4. For this reason, the switch knob is mounted on the case having a three-dimensional curved surface without a gap without specially making the case a complicated structure, and the feature that the reciprocating motion can be smoothly performed is realized.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below are examples of portable electric devices for embodying the technical idea of the present invention, and the portable electric devices of the present invention include the types of constituent parts, types, materials, The shape, structure, and arrangement are not specified below. The portable electric device of the present invention can be modified without departing from the scope of the claims.

Further, in this specification, for easy understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "claims column", "action column", and "action column". It is added to the members shown in the section of "Means for Solving the Problems". However, the members shown in the claims are
It is by no means specific to the members of the examples.

The ready shaver, which is a portable electric device shown in FIGS. 1 to 3, has a case 2, a switch mounted on the case 2, a motor 5 which is turned on / off by the switch, and a reciprocating motion by the motor 5. The movable blade 6 and the fixed blade 7 elastically pressed by the movable blade 6 are provided.

The case 2 is a plastic molded product, and is composed of a main body portion 8 for mounting the switch, a lid portion 9 for closing the storage portion of the motor 5 of the main body portion 8, and an opening / closing lid 10 for closing the storage portion of the battery. To be done. The lid 9 is connected to the main body 8 in a hooking structure, and the opening / closing lid 10 is connected to the main body 8 so as to be opened and closed when the battery is replaced. The body portion 8 of the case 2 has a connection hole 3 formed in the switch mounting portion. A sliding surface 2a, which is positioned above and below the connecting hole 3 and on which the switch knob 1 is reciprocally movable, is provided as a step portion on the outside of the case 2.

The main body portion 8 of the case 2 has a sliding surface 2a of the switch knob 1 and its vicinity curved into a three-dimensional curved surface. In the case 2 shown in the figure, the switch knob 1 is attached to a portion that becomes thinner from a thick portion. Sliding surface 2a of switch knob 1
Is divided into a front end portion 2A, a rear end portion 2B and a central portion 2C.

In the case 2 shown in the figure, the radius of curvature of the cross section of the front end 2A is made smaller than the radius of curvature of the cross section of the rear end 2B. Further, the sliding surface 2a is curved so that the radius of curvature of the cross section of the tip 2A is substantially equal to the radius of curvature of the cross section of the tip 1A on the inner surface of the switch knob, and the radius of curvature of the cross section of the rear end 2B is The inner surface of the switch knob is curved to have a radius of curvature substantially equal to the radius of curvature of the cross section of the rear end portion 1B. In the present specification, the sliding surface 2a is defined to have a cross-section radius of curvature substantially equal to that of the switch knob 1.
It means that there is no visible gap between a and the switch knob 1. Furthermore, case 2
In the sliding surface 2a, the radius of curvature of the cross section of the entire front end portion 2A is substantially equal, and the radius of curvature of the cross section of the entire rear end portion 2B is also substantially equal.

A connecting hole 3 for connecting the switch knob 1 to the support plate 4 is opened in the central portion 2C of the sliding surface 2a. A connection arm 11 that connects the switch knob 1 and the support plate 4 in the case 2 is provided in the connection hole 3 of the central portion 2C. The sliding surface 2a of the case 2 shown in FIG.
Since the radius of curvature of the cross section is smaller than that of the rear end portion 2B, a stepped step portion 12 is formed on the side portion of the connecting hole 3.

Further, as shown in the sectional view of FIG. 4 and the plan view of FIG. 5 in which the main body 8 is opened, the main body 8 of the case 2 is locked and slid on the switch knob 1. A first sliding guide 14 that slides the claw 13 and a second sliding guide 15 that slides the connecting arm 11 are provided. The first sliding guide 14 is provided along the side edge of the connecting hole 3.
The second sliding guide is provided on the bottom surface of the main body 8.
The switch knob 1 reciprocates in the direction indicated by arrow A in FIG. At this time, the locking sliding claw 1 of the switch knob 1
3 slides on the first slide guide 14, and the lower surface of the connecting arm 11 slides along the second slide guide 15. The first sliding guide 14 and the second sliding guide 15 are sandwiched between the upper and lower sides of the switch knob 1 to prevent the switch knob 1 from being displaced in the vertical direction (direction orthogonal to the paper surface in FIG. 5). To be done. Further, the hook portion of the locking sliding claw 13 and the inner surface of the switch knob 1 slide on the sliding surface 2a, so that the positional displacement of the switch knob 1 from side to side (left and right in FIG. 5) is prevented.

The switch includes a switch knob 1, a support plate 4 which is connected to the switch knob 1 and reciprocates in the case 2, an elastic contact 16 which is turned on and off by the support plate 4, and an elastic contact 16. Lead plate 17 to be contacted
With. The switch is connected between the motor 5 and the battery. When the switch is turned on, the motor 5 is rotated and the movable blade is vibrated. When the switch is turned off, the rotation of the motor 5 is stopped.

The switch knob 1 has a sliding surface 2a of the case 2.
It is mounted so that it can reciprocate. The switch knob 1 has a curved shape along the curved surface of the case 2 having a three-dimensional curved surface. The switch knob 1 has a reciprocating tip 1A.
The radius of curvature of the cross section of the rear end portion 1B is set to be different in order to adapt to the case 2 having a three-dimensional curved surface. FIG.
In the switch knob 1 shown in FIG. 6, the radius of curvature of the cross section of the front end 1A is small, and the radius of curvature of the cross section of the rear end 1B is large. It is the case 2 where the switch knob 1 is attached.
This is because the radius of curvature in the vicinity gradually decreases toward the tip.

The switch knob 1 is entirely made of plastic, and integrally projects a locking sliding claw 13 and a connecting arm 11 which is connected to the support plate 4 and protrudes inward.

In the switch knob 1 shown in FIG. 4, the locking sliding claw 13 is integrally formed on the upper portion and the connecting arm 11 is integrally formed on the lower portion in the figure. The locking sliding claw 13 is the first of the case 2.
The tip is formed into a hook shape so that the sliding guide 14 can slide along the sliding surface 2a in a hooked state. The hook-shaped locking and sliding claw 13 has elasticity such that it is elastically deformed and is inserted into the case 2 through the connection hole 3.

As shown in FIG. 6, the connecting arm 11 has a sandwiching opposed piece 11A that sandwiches both upper and lower surfaces of the support plate 4. The sandwiching opposing piece 11A projects into the case 2 from the connecting hole 3 of the case 2 and sandwiches the upper and lower surfaces of the support plate 4 in the case 2. In the switch knob 1 shown in the figure, the upper sandwiching facing piece 11A extends longer than the lower sandwiching facing piece 11A. The upper long sandwiching facing piece 11A is fitted into the connecting groove on the upper surface of the support plate 4 to connect the support plate 4 in a non-rotating state. The sandwiching facing pieces 11A are formed at intervals that allow the support plates 4 to be connected with almost no space. In FIG. 6, the lower sandwiching facing piece 11A slides on the second slide guide 15 provided on the inner surface of the case 2 when the switch knob 1 reciprocates on the sliding surface 2a.

The support plate 4 is manufactured by integrally molding plastic as a whole. The support plate 4 is provided with a connection groove 18 on the upper surface for connecting the upper sandwiching facing piece 11A. The connecting groove 18 is provided so as to extend laterally so that the sandwiching facing piece 11A of the switch knob 1 can be inserted in the lateral direction.
As shown in FIG. 5, when the switch knob 1 is reciprocated in the direction indicated by arrow A, the support plate 4 of this structure causes the connecting arm 11 of the switch knob 1 and the support plate 4 to move relative to each other in the direction indicated by arrow C. Move it. The switch knob 1 in FIG. 5 reciprocates in the direction indicated by arrow A, and the support plate 4 reciprocates in the direction indicated by arrow B. The support plate 4 is reciprocated in the direction of arrow B because this direction can switch the switch on and off without difficulty. In other words, switch knob 1
The support plate 4 does not move in the same direction when reciprocating. When both reciprocate, they move relatively in the direction indicated by arrow C. The connecting arm 11 shown in FIG. 6 can slide in the connecting groove 18 of the support plate 4 in the vertical direction and can relatively move in the direction of arrow C. Therefore, the switch knob 1 and the support plate 4 of this structure have a feature that both can be reciprocated in the optimum direction and can be smoothly moved smoothly.

Further, the switch knob 1 projects forward and integrally forms a moderation protrusion 19. Moderation protrusion 19
Has a convex portion inside the tip. The convex portion of the moderation projection 19 goes up and down over the shaft fixing convex portion 15 formed integrally with the case 2 to stop the switch knob 1 up and down.

Furthermore, the support plate 4 shown in FIGS.
Has a guide slit 20 along the left side in the figure. The guide slit 20 is a guide that reciprocates the support plate 4 in the direction indicated by the arrow C. Therefore, the guide slit 20 is provided so as to extend in the direction of arrow C, which is the direction of reciprocal movement of the support plate 4. Guide slit 2
As shown in the cross-sectional view of FIG. 4, a guide protrusion 21 integrally formed with the case 2 is guided to 0. The guide slit 20 and the guide protrusion 21 specify the direction in which the support plate 4 reciprocates, and smoothly move the support plate 4 in parallel.

The support plate 4 presses the ridges of the elastic contacts 16 shown in FIG. 2 to come into contact with the lead plate 17 to turn on the switch, while the ridges of the elastic contacts 16 are not pressed, the switch is turned off. To do. At the center of the support plate 4, a non-pressing portion 4A that does not press the peak portion of the elastic contact 16 is provided. The support plate 4 shown in the drawing has a through hole at the center to form a non-pressing portion 4A. When the support plate 4 is in the lowered position, the elastic contact 1
The mountain portion 6 is guided to the non-pressing portion 4A. The elastic contact 16 whose ridge portion enters the non-pressing portion 4A of FIG. 4 is not pressed by the support plate 4 and therefore does not contact the lead plate 17, and the switch is turned off. When the support plate 4 is moved to the raised position, the crests of the elastic contact 16 come out of the non-pressing portion and are pressed against the lower surface of the support plate 4. Therefore, the switch is turned on.

As shown in FIG. 3, the elastic contact 16 has an upper end bent in a chevron shape. When the mountain portion is pressed by the support plate 4, the tip 2 comes into contact with the lead plate 17, so that the case 2
The lead plate 17, which is fixed to, has its tip bent in an L shape. The bent end of the lead plate 17 is located below the tip of the elastic contact 16 and is arranged at a position where it comes into contact when the ridge of the elastic contact 16 is pressed. The lead plate 17 connects the rear end to the battery electrode, and the elastic contact 16 connects the rear end to the motor 5.
Connected to The other terminal of the motor 5 is directly connected to the electrode of the battery.

The ready shaver of this structure is turned off when the switch knob 1 is lowered. When the switch knob 1 is slid upward, the support plate 4 is raised together with the switch knob 1, and the support plate 4 presses the ridge portion of the elastic contact 16 to contact the lead wire to turn on the switch. Rotate the motor 5. When the motor 5 rotates, the rotation of the motor 5 rotates the crankshaft via the gear shown in FIG. The crankshaft is connected to the movable blade 6 via a connecting rod to vibrate the movable blade 6.

[0033]

The portable electric device with a switch according to the present invention is characterized in that the switch knob can reciprocate along a case having a three-dimensional curved surface, and the mounting portion of the switch knob of the case can be molded into a beautiful three-dimensional curved surface. This is because the portable electric device of the present invention forms the cross-sectional curvature radii of the front end portion and the rear end portion of the switch knob into different curvature radii according to the three-dimensional curved surface of the case, and further reciprocates the switch knob. The case sliding surface is divided into a front end portion, a rear end portion, and a central portion, and the front end portion and the rear end portion of the sliding surface are designed to be equal to the radius of curvature of the cross section of the front end portion and the rear end portion of the switch knob, Furthermore, this is because the entire front end portion of the sliding surface has the same cross-section radius of curvature, and the entire rear end portion of the sliding surface has the same cross-section radius of curvature. Thus, the portable electric device of the present invention,
Although the leading end and the rear end of the sliding surface have different cross-section radii of curvature, the respective cross-section radii of the leading end and the rear end are formed to have the same cross-section radius of curvature. When the knob is reciprocated, there is no gap between the switch knob and the sliding surface, and the switch knob smoothly reciprocates without collision between the switch knob and the sliding surface. It has the feature that the part where the knob is attached to the case can be beautifully processed.

Further, in the portable electric device of the present invention, a central portion is provided between the front end portion and the rear end portion of the sliding surfaces having different cross-section curvature radii, and the connecting hole is opened in this portion. The connecting hole is also used as a through hole for penetrating a connecting arm that connects the switch knob to the support plate. The structure in which the connecting hole is opened at the center of the front end and the rear end of the sliding surface allows the radius of curvature of the cross section of the front end and the rear end to be freely designed, and
The part that connects the front end and the rear end with different radii of curvature,
There is no need to design the switch knob so that it does not collide.
For this reason, there is no need to design the case sliding surface in a special shape, and the connecting hole in the center is also used as a through hole for connecting the switch knob and the support plate, so that the switch knob is smooth. There is no need to specifically open a through hole for reciprocating motion.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing a switch knob and a case sliding surface of a portable electric device of the present invention.

FIG. 2 is an exploded perspective view of a portable electric device according to an embodiment of the present invention.

3 is an exploded perspective view showing a case, a switch knob, and a support plate of the portable electric device shown in FIG.

FIG. 4 is an enlarged cross-sectional view of a connecting portion of a case, a switch knob, and a support plate of the portable electric device shown in FIG.

FIG. 5 is a plan view of a switch knob mounting portion of the portable electric device shown in FIG.

6 is a perspective view showing a connection state between a switch knob and a support plate of the portable electric device shown in FIG.

[Explanation of symbols]

1 ... Switch knob 1A ... Tip 1
B ... rear end 2 ... case 2a ... sliding surface 2A ... front end 2B ... rear end
2C ... Central part 3 ... Connection hole 4 ... Support plate 4A ... Non-pressing part 5 ... Motor 6 ... Movable blade 7 ... Fixed blade 8 ... Body part 9 ... Lid part 10 ... Open / close lid 11 ... Connection arm 11A ... Clamping opposing piece 12 ... Step portion 13 ... Locking sliding claw 14 ... First sliding guide 15 ... Second sliding guide 16 ... Elastic contact 17 ... Lead plate 18 ... Connection groove 19 ... Moderation projection 20 ... Guide slit 21 ... Guide projection

Claims (1)

[Claims] 1. A switch knob (1) is mounted on the curved surface of the case (2) having a three-dimensional curved surface so that the switch knob (1) can reciprocate. The switch knob (1) reciprocates. The front and rear inner surfaces are curved with different radii of curvature.
The sliding surface (2a) of the case on which the switch knob (1) is slidably mounted is curved so as to follow the inner surface of the switch knob (1). An electric device configured to reciprocate along 2a) to switch a switch on and off, which is characterized by having all the following structures. (A) The sliding surface (2a) of the case (2) is divided into a front end portion (2A), a rear end portion (2B) and a central portion (2C). (B) The radius of curvature of the cross section of the tip portion (2A) of the case sliding surface (2a) is substantially equal to the radius of curvature of the cross section of the tip portion (1A) of the inner surface of the switch knob. (C) The entire tip end portion (2A) of the case sliding surface (2a) has substantially the same cross-sectional radius of curvature. (D) The cross sectional radius of curvature of the rear end portion (2B) of the case sliding surface (2a) is substantially equal to the cross sectional radius of curvature of the switch knob inner surface rear end portion (1B). (E) The rear end portion (2B) of the case sliding surface (2a) has substantially the same overall cross-sectional radius of curvature. (F) A connecting hole is formed in the center (2C) of the case sliding surface (2a).
(3) is opened. (G) The connecting hole (3) is provided with a connecting arm (11) connecting to the switch knob (1) and the support plate (4) in the case.