JP2669694B2 - Keyboard switch - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a keyboard switch used in a keyboard device such as a computer typewriter word processor, and in particular, opening and closing a membrane switch by vertically moving a key stem. The present invention relates to an improvement of the key switch having the structure.

[Prior Art] FIG. 7 is a sectional view of a keyboard switch proposed by the present applicant in Japanese Patent Application No. 63-46829. As shown in the figure, a membrane switch 3 is fixed to a lower end surface of the opened frame 1 by a contact plate 2. Also,
A sliding portion 4 is provided on the frame 1 so as to be movable up and down, and is configured to press a contact portion 5 of the membrane switch 3. This sliding part 4
A columnar key stem 7 that is guided vertically through the guide hole 6 of the frame 1, a key top 8 attached to the upper end of the key stem 7, and a base member 9 provided at the lower end of the key stem 7. A pressing portion 10 provided on the base member 9 so as to surround the key stem 7 and pressing the membrane switch 3, and a plate provided on the base member 9 so as to push back the entire depressed sliding portion 4 upward. Spring part 11
And

In a keyboard provided with a large number of keyboard switches having such a configuration, rotation (play) of the key stem 7 is prevented by the following structure in order to arrange the key tops 8 in order on the frame. . That is, as shown in FIG. 8, a rotation stopper 12 is formed in the guide hole 6 of the frame 1 for guiding the key stem 7, and the connecting portion 13 between the key stem 7 and the base member 9 is slidable on the rotation stopper 12. Was engaged.

[Problem to be Solved by the Invention] According to the conventional structure for suppressing the rotation of the key stem 7,
A gap must be provided between the rotation stopping portion 12 and the connecting portion 13 for sliding the key stem 7 up and down. The position of the rotation stopper 12 and the connecting portion 13 is the key stem 7.
Since the center of rotation is close to the center of rotation, there is a problem in that the key top 8 is rotated (backlash) even if the gap is the minimum required for sliding the key stem 7.
More specifically, in order for the key stem 7 to smoothly slide, the above-mentioned gap needs to be 0.05 to 0.1 mm on one side, but if such a clearance is provided near the center axis of the key stem 7, rotation will occur. The backlash could not be avoided.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a keyboard switch having a guide means capable of preventing rotation of a key top even when a gap required for sliding of a key stem is set.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a keyboard switch of the present invention includes a membrane switch arranged on a backing plate, a frame provided above the membrane switch, and a guide to the frame. And a sliding portion for pressing the membrane switch, wherein the sliding portion is a columnar key stem guided by a frame, and a base member provided at the lower end portion of the key stem via a connecting portion, A pressing portion that is provided on the base member so as to surround the key stem and presses the membrane switch, and a leaf spring portion that is provided on the base member to push the pressing portion, the base member, and the key stem upward. In a keyboard switch provided with, a post provided on the base member in parallel with the key stem, and a guide provided on a frame for guiding the post. It is characterized by having an id hole.

Further, according to the present invention, in the keyboard switch, the key stem of the sliding portion, the base member, and the post have rigidity, and the pressing portion and the plate spring portion have elasticity. Good.

According to the present invention, in the keyboard switch, the sliding portion may be integrally formed of plastic.

[Operation] The post that slides against the guide hole provided in the frame is provided on the base member that is provided at the lower end of the key stem via the connecting part, so the distance from the center of the key stem is the connecting part. Greater than the distance to. Therefore, even if a gap necessary for sliding is provided between the guide hole and the post, the key stem does not undesirably rotate (backlash).

[Embodiment] A first embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 1 to 3, a keyboard switch 20 of the present embodiment includes a frame 21 which is a base of the switch, a membrane switch 23 which is attached to a lower end surface of the frame 21 by a backing plate 22, A sliding part (24) for pressing a contact part (25) of a membrane switch (23) vertically movable in a frame (21) is provided.

The sliding portion 24 is a member formed by integrally molding plastic as a whole, and has a cylindrical key stem 27 that is vertically slidably guided by a boss-shaped stem guide 26 formed on the upper surface of the frame 21. It is used as a base. The key stem 27 also needs to have a length such that the upper end protrudes out of the frame 21 even when pressed, and a key top 28 is inserted and fixed to the upper end protruding out of the frame 21. Key stem
On one side of the bottom surface of 27, there are two sound muffling projections 29, and when the key stem 27 is pressed down, it hits the membrane switch 23 with a part of the bottom surface, so that the collision sound is softened There is. Although the key stem 27 has a cylindrical shape, the key stem 27 may of course have a prism shape.

At the lower end of the key stem 27, a rod-shaped base member 31 is horizontally provided via a connecting portion 30. This base member 31,
It is a member for attaching a pressing portion, a leaf spring portion, and a post, which will be described later, and a member for transmitting the movement of the key stem 27 to these respective members. The base member 31 is configured to have an appropriate thickness to obtain rigidity. Therefore, the base member 31 moves in the same manner as the key stem 27, but does not deform. A pair of sound deadening protrusions 32 is provided on the lower surface of the base member 31,
A collision between the sliding portion 24 and the membrane switch 23 is buffered.

A substantially U-shaped pressing portion 33 having elasticity is formed in the base member 31 in a cantilever shape so as to surround the periphery of the key stem 27. The pressing portion 33 has a pair of horizontal portions 34 extending horizontally from the base member 31 and an inclined portion 35 extending obliquely downward from the horizontal portion 34. Inclined part 35
A pressing projection 36 having a spherical contact portion is formed on the lower surface of the distal end of the membrane switch 23 so as to contact the contact portion 25 of the membrane switch 23. The inclination angle of the inclined portion 35 is 45.
If the structure is such that the pressing protrusion 36 is provided on the lower surface of the inclined portion 35 extending from the horizontal portion 34, the height of the pressing protrusion 36 can be made shorter than that of a simply horizontal pressing portion. When the contact portion 25 is pressed by pressing down the sliding portion 24, the length of the sliding contact between the pressing protrusion 36 and the membrane switch 23 can be shortened. Also, the horizontal part
A sound deadening protrusion 37 is provided on the upper surface of 34. The sound deadening protrusion 37 protrudes above the upper surfaces of the base member 31 and the connecting portion 30, and when the entire sliding portion 24 is pushed back upward, it abuts against the upper end surface of the frame 21 and slides. A collision between the moving part 24 and the frame 21 is buffered.

A substantially U-shaped leaf spring portion 38 is formed on the base member 31 so as to surround the pressing portion 33. This leaf spring part 38
Is a plastic molded integrally with the base member 31 and the key stem 27, and has a proper elasticity by adjusting the thickness appropriately and having a shape inclined obliquely downward. That is, the leaf spring portion 38 has a pair of horizontal portions 39 extending horizontally from the base member 31 and a pair of inclined portions 40 extending diagonally downward from the horizontal portion 39. There is. The distal ends of the pair of inclined portions 40 are connected by a connecting member 41 substantially parallel to the base member 31, and are in contact with portions of the membrane switch 23 other than the contact portions 25. Also, this connecting member 41
A pair of protrusions 42 are provided on the lower surface of the device to reduce wear by reducing the contact area with the membrane switch 23. As described above, if the leaf spring portion 38 is configured by the horizontal portion 39 and the inclined portion 40, it becomes possible to set the spring length to be as large as possible within the limited allowable dimension in the frame 21, and the stress is dispersed. By leaf spring
The life of 38 can be extended. In addition, with such a bent shape, the projection 42 is always connected to the membrane switch 23.
Can be kept in contact with. Also, a pair of inclined portions 4
With the structure in which 0 and 40 are integrally connected by the connecting member 41, when integrally molded with plastic, there is no difference in vertical deformation between the two inclined portions 40 and 40 when releasing from the mold, and the spring It is possible to avoid the inconvenience that the sex is different.

When the sliding portion 24 is incorporated into the frame 21, the leaf spring portion 38 is bent so that the frame
The lifting force is applied to the sliding part 24 within 21.

A post 43 is erected on the upper end of the base member 31. The post 43 is parallel to the key stem 27, and its shape may be a cylinder or a prism, but its base and tip have the same diameter. A guide hole 44 is formed at an important part of the frame 21 corresponding to the post 43. Also, post 43
The length needs to be such that the key stem 27 is pushed all the way out so that it slightly protrudes upward from the guide hole 44 of the frame 21. Further, it is necessary that the post 43 be integrally molded with other parts of plastic and have rigidity together with the base member 31 and the key stem 27. According to this structure, the position where the post 43 is provided is behind the connecting portion 30 when viewed from the center of the key stem 27, so that the sliding movement of the sliding portion 24 in the horizontal direction can be prevented.

To assemble the keyboard switch 20 having the above-described structure, first, the sliding portion 24 having an integral structure in which the key top 28 is removed from below the frame 21 is incorporated, and the key stem 27 is inserted into the stem guide 26. Then, the membrane switch 23 and the contact plate 22 are framed so that the leaf spring portion 38 bends to some extent.
Mount on the bottom side of 21. Then, the key top 28 is attached to the upper end of the key stem 27 protruding to the upper surface side of the frame 21.

 Next, the operation of the above configuration will be described.

As shown in FIG. 4 (a), in a state where no load is applied to the switch, the leaf spring portion 38 is slightly bent and the projection 42 is brought into contact with the membrane switch 23. The entire 24 is urged upward. The sound deadening projection 37 of the pressing portion 33 is in contact with the frame 21.

As shown in FIG. 4 (b), a key top 28 (not shown)
Press down with your finger to lower the key stem 27, and
Then, the pressing protrusion 36 of the pressing portion 33 starts pressing the contact portion 25 of the membrane switch 23.

As shown in FIG. 4 (c), when the sliding portion 24 is pushed down, the leaf spring portion 38 is deformed into a U-shape projecting upward.
The pressing protrusion 36 of the pressing portion 33 rotates slightly and rubs against the membrane switch 23 to further press the contact portion 25. At this time,
Since the key stem 27 and the base member 31 come into contact with the membrane switch 23 by the noise canceling projections 29 and 32, no loud noise is generated. Further, if there is only one muffling protrusion on the base member 31 side only, the key stem 27 may tilt as shown in FIG. 5 (a), but in the present embodiment, the base member 31 and the key stem 27. It is provided in both
In addition, since the sound deadening protrusion 29 is formed on the side opposite to the base member 31 with respect to the central axis of the key stem 27, the key stem 27 does not tilt even when it is pushed completely as shown in FIG. 5 (b).

Next, except for the load, the sliding portion 24 returns upward by the elastic force of the leaf spring portion 38. At this time, the sound deadening protrusion of the pressing portion 33
37 abuts the frame 21 to support the sliding portion 24 and absorb the collision noise.

In the above operation, the key stem 27 is regulated in the positional deviation in the rotation direction by the post 43 and the guide hole 44 which are located at a position considerably separated from the center thereof. Therefore, the base member 31
Unlike the conventional structure for preventing rotation by the connecting portion 30, the post 43 and the guide hole 44 are sufficiently useful for preventing rotation while securing sufficient clearance for sliding.

Further, the pressing portion 33 that presses the contact portion 25 of the membrane switch 23 has a bent shape including the horizontal portion 34 and the inclined portion 35, and the height of the pressing protrusion 36 can be made lower than in the conventional case.
Therefore, the sliding contact length between the contact portion 25 and the pressing protrusion 36 can be shortened, and the durability of the portion can be improved.

Further, since the leaf spring portion 38 has a bent shape including the horizontal portion 39 and the inclined portion 40, the effective spring length can be lengthened within a defined space, and the life of the spring can be lengthened. Further, since the tip of the leaf spring portion 38 is always in contact with the membrane switch 23, it may be plastically deformed into a shape that warps upward. In this case, the entire length of the leaf spring portion 38 cannot be used as a spring, but the tip of the leaf spring portion 38 can always be brought into contact with the membrane switch 23 in the shape of the embodiment.

In the above-described embodiment, the entire sliding portion 24 is integrally formed of plastic, but only the leaf spring portion may be made of metal. For example, as shown in the second embodiment of FIG. 6, the leaf spring portion 50 is not provided with a connecting member, and the leaf spring portion 50 including a pair of horizontal portions 51 and inclined portions 52 is formed of stainless steel or phosphor bronze. When the plastic key stem 55, the base member 53 and the pressing portion 33 are molded, the leaf spring portion 50 is formed integrally with the plastic portion by insert molding.
Also in this case, the protrusion 54 is provided at the tip of the inclined portion 52, and the wear of the membrane switch can be prevented. In this embodiment, one or a pair of muffling projections 56 are provided on the lower end surface of the key stem 55.

[Effect of the Invention] As described above, according to the present invention, the post is provided at a position on the base member that is distant from the center of the key stem, and the post is guided to the guide hole of the frame.
There is an effect that the rotation of the key stem can be surely suppressed.

[Brief description of the drawings]

1 is a sectional view of a first embodiment of the present invention, FIG. 2 is a sectional view of a sliding part and a membrane switch in the same embodiment, and FIG. 3 is a plan view of a sliding part and a membrane switch in the same embodiment. 4 (a), (b), and (c) are cross-sectional views showing the action of the sliding portion in the same embodiment, and FIG. 5 (a) is a case in which there is no silencing protrusion at the lower end of the key stem in the same embodiment. FIG. 5 (b) is a sectional view showing a state in which the sliding portion is pushed down in the same embodiment, and FIG. 6 is a plan view of the sliding portion in the second embodiment of the present invention. FIG. 7 is a sectional view showing an example of a conventional keyboard switch, and FIG. 8 is a sectional view showing an example of a structure for suppressing rotation of a key stem in the conventional keyboard switch. 20 …… Keyboard switch, 21 …… Frame, 22 …… Patch plate, 23 …… Membrane switch, 24 …… Sliding part, 27…
… Key stem, 30 connecting part, 31 base member, 33 pressing part, leaf spring part, 43 post, 44 guide hole.

Claims (3)

(57) [Claims] 1. A slide switch, comprising: a membrane switch disposed on a backing plate; a frame provided above the membrane switch; and a sliding portion which is guided by the frame and presses the membrane switch. A columnar key stem guided by a frame, a base member provided at the lower end of the key stem via a connecting portion, and a base member surrounding the key stem to press the membrane switch. In a keyboard switch including a pressing portion, the pressing portion, the base member, and a leaf spring portion provided on the base member so as to push up the key stem, a post provided on the base member in parallel with the key stem. And a guide hole provided in a frame for guiding the post. 2. The keyboard switch according to claim 1, wherein the key stem, the base member and the post of the sliding portion have rigidity, and the pressing portion and the leaf spring portion have elasticity. 3. The keyboard switch according to claim 1, wherein said sliding portion is integrally formed of plastic.