JPH0492321A - Push button - Google Patents

Abstract

PURPOSE:To prevent invasion of forein matters such as dust into the inside by relatively moving a sliding member to the housing and a stem, besides overlapping three side walls of the stem, a sliding member and the housing. CONSTITUTION:When the top surface of a key top 12 is pressed into, a sliding projection 58 goes down inside a guide tube 26 to compress a coil spring 10, and spring force of the compressed coil spring makes the guide tube 26 to go down inside a guide tube 14 to press and reverse a moving contact 8 by the underface of a sliding member 9 and the contact 8 comes in contact with a fixed contact 17 to turn a switch from OFF to ON. In this case, the sliding surface between the sliding member 9 and the stem 11 is ensured at both in-and outside between the guide tube 26 and a projection 38 as well as between both sidewalls 29 and 39, and the sliding surface between the housing 7 and the member 9 is ensured by both in-and outsides between the guide tube 14 and the guide tube 26 as well as between both side walls 13 and 29.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a push button switch used as a key switch of an input device such as a personal computer or a word processor, and particularly relates to a push button switch suitable for thinning.

[Conventional technology]

FIG. 7 is a sectional view showing a conventional example of this type of push button switch.
is placed. This membrane switch 2 is composed of an upper sheet 2b having a movable contact 2a, a lower sheet 2d having a fixed contact 2C, and a spacer 2e laminated between the upper and lower sheets 2b and 2d. A housing 3 made of synthetic resin is placed on the membrane switch 2.
is mounted on the housing 3, and an annular guide tube 3a and a protrusion 3b located outside the annular guide tube 3a are integrally molded into the housing 3. A stem 4a hanging vertically from the top surface of a key top 4 made of synthetic resin is slidably inserted into the inner wall 3c of the guide tube 3a, and a coil spring 5 is tightly fitted into the stem 4a. It is installed by Furthermore, a flat surface 3d is formed between the guide cylinder 3a and the protrusion 3b of the housing 3, and a return spring 6 is interposed between the flat surface 3d and the top surface of the key top 4. It is set up.

Although not shown, a notch groove is formed in the protruding portion 3b in a direction perpendicular to the paper surface of FIG.
On the other hand, the key top 4 is provided with an engaging pawl that moves up and down within these notched grooves, and when this engaging pawl comes into contact with the upper end of the notched groove, the key top 4 is prevented from falling off from the housing 3. Prevented.

Next, the operation of the push button switch configured as described above will be explained.

In the non-operating state shown in FIG. 7, the key top 4 is located at the highest stroke point where the engaging pawl (not shown) comes into contact with the upper end of the notch groove due to the elastic force of the return spring 6. Since the lower end of the spring 5 is spaced apart from the upper sheet 2b, the membrane switch 2 is in an off state in which the movable contact 2a and the fixed contact 2C are not in contact with each other.

From this state, the operator returns the key top 4 to the spring 6.
When the key top 4 is pushed in against the elastic force, the outer wall of the stem 4a descends along the inner wall 3C of the guide cylinder 3a, and the key top 4 is moved to the lowest stroke point. In this case, stem 4a
The coil spring 5 held at the upper seat 1-2b comes into contact with the upper seat 1-2b and is gradually compressed, so that the upper seat 2b is bent by the elastic force of the coil spring 5, and the movable spring 2a is moved toward the fixed contact 2.
C is contacted and the membrane switch 2 is switched from off to on.

When the pressing operation force on the key top 4 is removed in this ON state, the key top 4 rises to the highest stroke point shown in FIG. 7 due to the elastic force of the return spring 6, so that the bent upper seat 2b With this restoration, the movable contact 2a separates from the fixed contact 2C, and the membrane switch 2 is switched from the on state to the off state.

[Problem to be solved by the invention]

By the way, in this type of push button switch, stem 4
By inserting the key top 4 into the inner wall 3C of the guide tube 3a and making it slide into contact with the inner wall 3C of the guide tube 3a, the key top 4 is held in the housing 3 so as to be able to move up and down. Attempts have been made to reduce the height of the guide tube 3a, but in this case, the amount of insertion of the stem 4a into the guide tube 3a inevitably becomes smaller, and the distance between the two required for sliding contact is reduced. Due to the small clearance between the key top 4 and the housing 3,
It becomes easier to lean towards the opposite direction. Particularly, when the operator presses the edge of the key top 4 into a so-called end push, the stem 4a gets caught on the guide tube 3a, resulting in an extremely poor operating feel.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a push button switch that can be made smaller and thinner, without deteriorating the operating feel, and has excellent dust resistance.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a bottomed box-shaped housing containing a switch element, a sliding member disposed so as to be movable up and down with respect to the housing. , a stem disposed to be movable up and down with respect to the sliding member; a first return spring interposed between the housing and the sliding member;
a second return spring interposed between the sliding member and the stem; when the stem is not pressed, the housing and the sliding member each side wall, and the sliding member and the The stem is characterized by overlapping side walls.

[For production]

When the stem is pressed, the side walls of the sliding member overlap the housing, and the side walls of the stem, sliding member, and housing overlap each other at the top of the stroke, preventing foreign matter such as dust from entering inside. It can be prevented.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

1 and 2 are cross-sectional views of a push-button switch according to an embodiment of the present invention, viewed from different directions, FIG. 3 is a plan view of a housing provided in the push-button switch, and FIG. 4 is a cross-sectional view of the push-button switch. 5th plan view of the sliding member provided in
The figure is an exploded perspective view of the push button switch, and FIG. 6 is a sectional view showing the push button switch in a pressed state.

As shown in these figures, the push-button switch according to this embodiment includes a housing 7, a movable contact 8, a sliding member 9, a coil spring 10, a stem 11, and a key top 12.

The housing 7 has a box shape with a bottom and a side wall 13 around the periphery, and a first guide cylinder 1 with a bottom is provided at the center of the bottom surface.
4 are erected. This first guide tube 14 protrudes downward from the bottom surface, and a pair of slots 15 are formed at the upper end of the guide tube 14. The housing 7
First and second fixed contacts 16.17 are respectively inserted into the bottom surface of the holder, and these contacts 16.17 are led out to the outside as terminals 18.19.

The first fixed contact 16 is located inside the side wall 13, and a groove 20 is formed in the vicinity thereof.
7 is located outside the first guide cylinder 14. Further, first engaging claws 21 projecting outward are formed at two opposing corners of the side wall 13, respectively.

The movable contact 8 is made of an elastic plate made of phosphor bronze or the like which is pressed into a roughly S-shape, and has hook parts 22 at both ends and an annular part 23 in the center. This movable contact 8 is formed into a dome shape with a bulged center by hooking the hooking parts 22 at both ends to the groove 20, and in this state, the first fixed contact work 6 and the movable contact 8 are hooked together. The annular portion 23 is electrically connected to the stop portion 22 , and the annular portion 23 is loosely fitted onto the outer peripheral surface of the first guide cylinder 14 and is spaced apart from the second fixed contact 17 .

The sliding member 9 has an annular wall 24 at the center of the bottom surface, and a second guide cylinder 2 is provided inside the annular wall 24 via a rib 25.
6 is integrally formed. The outer diameter of the second guide tube 26 is set to be approximately the same as the inner diameter of the first guide tube 14, and a pair of slots 27 are also formed at the upper end of the second guide tube 26. ing. On the other hand, the inner diameter of the annular wall 24 is set to be somewhat thicker than the outer diameter of the first guide cylinder 14, and a recess 28 is formed on the outside of the annular wall 24. ing.

Further, a side wall 29 is erected on the outer peripheral edge of the bottom surface of the sliding member 9, and a flange portion 30 projecting outward is formed around the entire upper end of the side wall 29. Retaining holes 31 are bored in two opposing corners of the collar 30, and the bottom of a hanging wall 32 that is hung down from the collar 30 to surround these engaging holes 31, that is, the engaging A first retaining step portion 33 is formed on the outer inner bottom surface of the matching hole 31 . Further, second locking step portions 34 are formed at the remaining two corners of the flange portion 30, and cutout portions 35 are formed near these second locking step portions 34.

The side wall 29 of the sliding member 9 is the same as the side wall 1 of the housing 7.
3, and is urged upward by the elastic force of the movable contact 8.
1 comes into contact with the first locking step 33 in the locking hole 31, thereby preventing the sliding member 9 from falling off from the housing 7.

In this state, the second guide tube 26 is in sliding contact with the inner circumferential surface of the first guide tube I4, the rib 25 is located within the slot 15, and the side walls of the housing 7 and the sliding member 9 are 13.29 has more overlap (see Figure 1).

The stem 11 has a pair of half-moon-shaped notches 3 in the center of the top surface.
6, and a cylindrical sliding protrusion 38 is vertically provided at the center of the notch 36 via a connecting piece 37. The diameter of this sliding protrusion 38 is set to be approximately the same as the inner diameter dimension of the second guide tube 26. Further, a side wall 39 is provided vertically on the periphery of the top surface of the stem 11, and leg pieces 40 extending downward are provided on two opposing corners of the side wall 39. Four second engaging claws are formed that protrude in the direction. Further, a pair of fitting holes 42 are bored in the top surface of the stem 11, and these fitting holes 42 communicate with the inner walls of the leg pieces 40, respectively. On the other hand, a pair of fitting protrusions 43 having the same planar shape as the fitting hole 42 are vertically provided on the lower surface of the key top 12 .

The side wall 39 of the stem 11 is similar to the side wall 29 of the sliding member 9.
The spring receiver of the sliding member 9 is urged upward by the elastic force of the coil spring 10 interposed between the recess 28 and the top surface of the stem 11. Matching claw 41
The stem 11 is prevented from falling off from the sliding member 9 by contacting the second retaining step portion 34 (lower surface of the collar portion 30).

In this state, the sliding protrusion 38 is connected to the second guide cylinder 26.
The sliding member 9 and the respective side walls 29, 39 of the stem ll overlap further (the second
(see figure). Further, the stem 11 and the key top 12 are integrated by the fitting protrusion 43 being press-fitted into the fitting hole 42 , and the fitting protrusion 43 abuts against the inner surface of the leg piece 40 , so that the leg piece 40 is deformed and the second retaining step portion 34 and the second
The engagement with the engagement claw 41 is prevented from being released. Note that 44 is a printed circuit board having a through hole 45, and the push button switch is placed on the printed circuit board 44 with the first guide tube 14 protruding from the lower surface of the housing 13 inserted into the through hole 45. Terminals 18 and 19 are soldered to a pattern (not shown) on the printed circuit board 44.

Next, the operation of the push button switch configured as described above will be explained.

In the non-operating state shown in FIGS. 1 and 2, the stem 11 integrated with the key top 12 is urged by the coil spring 10 in a direction away from the bottom surface of the sliding member 9. is urged by the movable contact 8 in a direction away from the bottom surface of the housing 7, and the key top 12 is located at the highest point of its stroke. At this time, since the movable contact 8 has a dome shape, the movable contact 8 and the second fixed contact 17 are not in contact with each other, and the switch is in an off state.

When the operator pushes in the top surface of the key top 12 from this state, the sliding protrusion 38 descends inside the second guide tube 26 and compresses the coil spring 10, as shown in FIG. The second guide tube 26 moves down inside the first guide tube 14 due to the elastic force of the coiled spring 10, and as a result, the movable contact 8 is pressed and reversed by the lower surface of the sliding member 9, and the movable contact 8 moves into the second guide tube 14. The switch contacts the fixed contact 17 of No. 2 and is turned from off to on. in this case,
The sliding surface between the sliding member 9 and the stem 11 is secured both inside and outside between the second guide cylinder 26 and the sliding protrusion 38 and between the side walls 29 and 39, and the sliding surface between the housing 7 and the sliding The sliding surfaces between the member 9 and the member 9 are secured both inside and outside between the first guide cylinder 14 and the second guide cylinder 26 and between the side walls 13 and 29. In addition, as mentioned above, at the lowest point of the stroke when the switch is in the on state, the first and second
The upper ends of the guide tubes 14 and 26 are both located within the notch 36 of the stem 11, while the connecting piece 37 of the stem 11 is located within the first
and slot 15.27 of second guide tube 14.26
Located within.

When the pressing force on the key top 12 is removed, the sliding member 9 and the stem 11 rise to the highest stroke point shown in FIG. 2 due to the elastic force of the movable contact 8 and the coil spring 10, respectively. The switch is switched from an on state to an off state at a distance from the fixed contact 17 of the switch.

In this way, in the above embodiment, the first guide tube 14 of the housing 7 is located between the housing 7 and the stem 1.
Since the sliding member 9 having the second guide cylinder 26 that can freely slide against the sliding protrusion 38 of the stem 11 and the sliding protrusion 38 of the stem 11 is provided, it is compared to the conventional product in which the stem slides directly on the guide cylinder of the housing. The sliding distance can be doubled,
In other words, the height of the push button switch can be significantly shortened while maintaining the same sliding feel as conventional products.

Further, when the stem II is not pressed, that is, at the highest point of the stroke, the side wall 39 of the stem 11 and the side wall 29 of the sliding member 9 and the side wall 29 of the sliding member 9 and the side wall 13 of the housing 7 are overlapped. Therefore, it is possible to prevent foreign matter such as dust from entering the inside and cause contact failure, and it is possible to provide a push button switch with excellent dustproof properties.

In addition, in the above embodiment, a case was explained in which the switch element for switching the contacts is composed of the second fixed contact 17 provided on the bottom surface of the housing 7 and the movable contact 8 for returning the sliding member 9. It is also possible to arrange a membrane switch on the inner bottom surface of the housing instead of these fixed contacts and movable contacts, and to operate this membrane switch by a sliding member or an elastic member for returning the sliding member. be.

Further, in the above embodiment, a case is described in which the side wall 39 of the stem 11 is brought into sliding contact with the inner surface of the side wall 29 of the sliding member 9, and the side wall 29 of the sliding member 9 is brought into sliding contact with the inner surface of the side wall 13 of the housing 7. However, the positional relationship of these members is opposite to that of the above embodiment, that is, the side wall 29 of the sliding member 9 is slid on the outer surface of the side wall work 3 of the housing 7, and the side wall 29 of the sliding member 9 is slid on the outer surface of the side wall 29 of the sliding member 9. It is also possible to slide the side wall 39 of the stem 11.

〔Effect of the invention〕

As explained above, according to the present invention, the height dimension can be shortened without reducing the sliding distance, and foreign matter such as dust can be prevented from entering the interior, making it suitable for downsizing and thinning. A push button switch with excellent dust resistance can be provided.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a push-button switch according to an embodiment of the present invention, viewed from different directions, FIG. 3 is a plan view of a housing provided in the push-button switch, and FIG. 4 is a cross-sectional view of the push-button switch. 5th plan view of the sliding member provided in
FIG. 6 is an exploded perspective view of the push button switch, FIG. 6 is a cross-sectional view showing the press operation state of the push button switch, and FIG. 7 is a cross-sectional view of a conventional push button switch. 7・・・・・・・・・Housing, 8・・・・・・・・・
・Movable contact (first return spring), 9...
Sliding contact, IO... Coil spring (second return spring), 11... Stem, 12...
...Key top, 13, 29.39...
...Side wall, 14...First guide tube, 15.27...Slot, 16...
......First fixed contact, 17...
・Second fixed contact, 18.19......Terminal, 20......Groove, 21......
First engaging claw, 22...Latching portion, 23.
・・・・・・・・・Annular part, 24・・・・・・Annular wall, 25・・・・・・Rib, 26・・・・・・・・・
...Second guide cylinder, 28... Spring receiver is recessed part, 30... Flam part, 31...
...Engagement hole, 32...Descent wall, 33.
...Old...First engagement step section, 34...
Second engagement step portion, 35...Notch portion, 36
......Notch, 37...Inner connecting piece, 38...Sliding protrusion, 40...
...Leg piece, 41...Second engagement claw, 4
2... Old... Fitting hole, 43... Fitting protrusion, 44... Printed circuit board, 45...
......Through hole. Figure 3 - Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] a bottomed box-shaped housing containing a switch element; a sliding member disposed so as to be movable up and down with respect to the housing;
a stem arranged to be able to rise and fall freely with respect to the sliding member;
a first interposed between the housing and the sliding member;
and a second return spring interposed between the sliding member and the stem, and when the stem is not pressed, side walls of the housing and the sliding member, respectively;
and a push button, characterized in that the respective side walls of the sliding member and the stem overlap.