JPH0451376Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a tact switch used in operation switches for VTRs, audio equipment, etc., information input switches for OA equipment, etc., and control switches for various industrial equipment.

<Conventional technology> Figure 2 shows the general structure of a tact switch.

In the figure, reference numeral 1 denotes a base on a disc made of an insulator, and a circular recess 2 is provided on the top surface, and a flat portion 3 is provided on the side surface at an axially symmetrical position. A protrusion 4 is provided. 5,6
is an elongated contact terminal formed by punching and forming a conductive metal plate, and is embedded parallel to the above base by means of insert molding,
One contact terminal 5 integrally has a central fixed contact 7 located at the center of the bottom surface of the recess 2, and the other contact terminal 6 is also located symmetrically with respect to the central fixed contact 7 on the bottom surface of the recess 2. Peripheral fixed contact 8,
It has 8 integrally. Further, both ends of the contact terminals 5, 6 protrude outward from the side surface of the base 1, and are bent downward at right angles at the protruding portions to form connection terminals 9, 9, 10, 10 for the printed circuit board. Reference numeral 11 denotes a movable contact curved upward into a dome shape, which is punched out of an elastic conductive metal plate;
Has reversal characteristics. The movable contact 11 is housed in the recess 2 with its curved protrusion facing upward so that its peripheral edge is always in contact with the peripheral fixed contacts 8, and its center is spaced apart and opposed to the central fixed contact 7. be done. Reference numeral 12 denotes a disc-shaped pressing plate which is in contact with the movable contact 11 and is housed in the recess 2 so as to be able to move up and down, and is made of an insulator. It has a protrusion 13 that comes into contact with the part and presses it to reverse it, and also has a knob 14 for pressing operation in the center of the upper surface. Further, the press plate 12 has an annular engagement step portion 15 on the upper surface periphery, and its cross section connects the press plate 12 to the movable contact 11 in the recess 2.
It is formed so as to be substantially flush with the upper surface of the base 1 when placed on top. Reference numeral 16 denotes an annular cover formed by stamping a metal plate placed on the upper surface of the base 1, and the inner edge of the annular portion 21 protrudes toward the center of the recess and abuts against the engagement step portion 15 of the pressing plate 12. This prevents the movable contact 11 and the pressing plate 12 from coming out of the recess 2 upward. The cover 16 has a pair of elastic locking pieces 1 extending downward from opposing peripheral edges thereof.
7 and 17, and the cover 16 is fixed to the upper surface of the base 1 by fitting and locking the window 18 provided on the elastic locking piece 17 into the locking protrusion 4 provided on the side surface of the base. In addition, 19 is a reinforcing annular rib formed by punching the center part of the plate surface of the annular part 21 upward, and 20 is the outer peripheral edge of the annular part 21 as well.
This is an annular rib for positioning that is bent downward along the side surface of the holder. In the tight switch configured in this way, when the knob 14 is pressed and the pressing plate 12 is pushed down, the protrusion 13 presses the curved protrusion of the movable contact 11 downward and reverses it, bringing it into contact with the central fixed contact 7. Thereby, conduction is established between the central fixed contact 7 and the peripheral fixed contacts 8, 8, thereby obtaining a switching operation. Furthermore, when the pressure on the knob 13 is removed, the movable contact 11 returns to its original shape due to its own elasticity and pushes the press plate 12 up to its original position.

In the above-described tact switch, the annular portion 21 of the cover 16 has conventionally been formed into a flat, unbent shape as shown in FIG.

<Problems to be Solved by the Invention> However, according to the conventional cover 16 in which the annular portion 21 is formed flat, the window 18 of the locking piece 17 is fitted and locked to the locking protrusion 4 of the base 1. When the cover 16 is fixed on the top surface of the locking piece 17
If there is a positional error between the window 18 of the base 1 and the locking protrusion 4 of the base 1, especially between the lower edge of the window 18 and the lower edge of the locking protrusion 4, the window 18 as shown in FIG. 18
The cover 16 was loosely fitted into the locking protrusion 3.3 and locked, causing the cover 16 to wobble on the top surface of the base 1. If the cover 16 is loose, the fourth
As shown by the arrow in the figure, when a pressing force is applied to the knob 14 from diagonally above in a direction perpendicular to the line connecting the locking pieces 17, 17 fitted and locked to the base 1,
As shown in FIG. 5, a lift occurs at one end of the cover 16, and the pressing plate 12 is tilted greatly and a part of its peripheral edge comes into contact with the bottom surface of the recess 2, and the pressing force by the protrusion 13 is sufficient to apply to the movable contact 11. There was a problem where the switch was not being communicated properly and the switch was malfunctioning.

This invention was made in view of the above circumstances, and aims to provide a tact switch that eliminates the rattling of the cover, stabilizes the pressing operation of the press plate against the movable contact, and provides reliable switch operation.

<Means for Solving the Problems> In order to achieve the above object, this invention provides a fixed contact on the bottom surface of a recess formed on the upper surface of the base, and also provides a movable contact and a movable contact in the recess opposite to the fixed contact. Pressing plates for pressing and driving the movable contacts are stored respectively on the movable contacts, and a cover is disposed on the upper surface of the base to prevent the pressing plates from coming out of the recess, and a cover 1 extending downward from a peripheral edge facing portion of the cover is arranged.
In a tact switch in which a pair of locking pieces are locked and fixed to a side surface of the base, both sides of the cover sandwiching a line connecting the pair of locking pieces are bent slightly downward, and the cover is attached to the top surface of the base. The cover is elastically pressed to prevent the cover from wobbling.

<Example> Hereinafter, an example of the tact switch according to this invention will be explained using FIGS. 1 and 2.
In this embodiment, the only difference from the conventional example is the shape of the cover, and all other parts are the same, so the same parts will be given the same reference numbers and redundant explanation thereof will be omitted.

FIG. 1 shows a cover 16A according to this invention.
This cover 16A is attached to the conventional cover 16 shown in FIG. 3 in such a way that the line connecting the locking pieces 17, 17 of the annular portion 21 forms a mountain, and the two sides of the cover 16A are located at the positions indicated by dotted lines in the figure. It is bent slightly downward. In order to fix this cover 16A to the upper surface of the base 1 in which the fixed contacts 7, 8, the movable contact 11, and the pressing plate 12 are assembled in the recess 2, the cover 16A is
The annular part 21 is arranged on the upper surface of the base 1, and the peak part of the central part is pressed against the upper surface of the base against the elasticity of the annular part, and the windows 18, 18 of the locking pieces 17, 17 are closed.
is fitted and locked into the locking protrusion 4 on the side surface of the base 1. At this time, the window 18 of the locking piece 17 and the locking protrusion 4
Even if there is some positional error between the annular portion 21 and
Since the cover 16A is bent into a chevron shape, the positional error is absorbed by the elasticity of the annular portion 21, and the cover 16A
There is no wobbling on the top surface of base 1. Therefore, according to the tact switch using the cover 16A of this invention, since the cover 16A has no looseness, the knob 14 of the pressing plate 12 can be fitted and locked to the base 1 as shown by the arrow in FIG. Locking piece 17,
Even if a pressing operation force is applied diagonally from above perpendicular to the line connecting 17, the pressing plate 12 does not tilt significantly and the pressing force can be reliably transmitted to the movable contact 11, so that the switch operation is reliable.

<Effects of the invention> This invention is constructed as described above, but the both sides of the cover that sandwich the pair of locking pieces are bent slightly downward, and the pair of locking pieces are locked to the side of the base. Since the cover is elastically pressed against the upper surface of the base to prevent wobbling when the cover is pressed, the pressing operation of the pressing plate against the movable contact becomes stable, and a reliable switching operation can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a plan view and a front view showing an embodiment of the cover of this invention, Fig. 2 is a plan view, a front view and a sectional view showing the structure of a tact switch, Figs.
5 and 5 respectively show conventional examples. 1...base, 2...recess, 4...locking protrusion,
7...Central fixed contact, 8...Peripheral fixed contact, 11
...Movable contact, 12...Press plate, 16A...Cover, 17...Locking piece, 18...Locking window.

Claims (1)

[Scope of utility model registration request] A fixed contact is provided on the bottom of a recess formed on the upper surface of the base, a movable contact is housed in the recess opposite to the fixed contact, and a pressing plate for pressing and driving the movable contact is housed in the recess. In a tact switch, a cover is disposed to prevent the pressing plate from coming out of the recessed part, and a pair of locking pieces extending downward from a peripheral edge opposing part of the cover are locked and fixed to the side surface of the base, A tact switch characterized in that both sides of the cover sandwiching a line connecting the pair of locking pieces are bent slightly downward to elastically press the cover against the upper surface of the base.