JPS61292824A - Keyswitch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a key switch used in a keyboard device, etc., and is particularly characterized by the positioning of a frame and a rubber spring that performs a key action function of the key switch. It is something.

<Prior Art> Conventionally, in keyboard devices such as electronic typewriters, word processors, and computers, from the viewpoint of reducing material costs and improving durability of key switches,
In these types of key switches, in which rubber spring action is increasingly being used in the member responsible for key action, the rubber spring is positioned relative to a circuit pattern board, and this circuit pattern board is attached to the frame of an electronic typewriter, etc. It was configured to be positioned against the Specifically, the circuit pattern board is formed with a positioning protrusion that protrudes upward, and the rubber spring is formed with an opening at a position corresponding to the positioning protrusion. (through the opening in the rubber spring), the rubber spring was positioned relative to the circuit pattern board.

Then, this stacked body was positioned from below on the frame (fixed with screws, etc.), while the key was assembled from above the frame to complete the key switch.

<Problems to be Solved by the Invention> However, the key switch assembled as described above had the following problems.

(a) Since the rubber spring is positioned with respect to the frame via a support plate, the assembly error between the rubber spring and the frame is increased, and the accuracy between the key stem and the rubber spring is increased. (b) If the frame is made of a resin material such as ABS that has a large expansion coefficient with respect to temperature changes, the rubber spring should be attached to the support plate (usually made of steel plate, which expands or contracts with temperature changes). Since the key stem and the rubber spring are positioned at a position where the key stem is difficult to move, the rubber spring cannot follow the expansion or contraction of the frame due to temperature changes, and there is a risk that the key stem and the rubber spring may become misaligned.

As a result, when a key is pressed, the key stem and the rubber spring may come into contact with each other unevenly, resulting in problems such as chattering of the key switch or a delay in key-in.

<Objective of the Invention> Therefore, the present invention solves these problems and accurately positions the key stem and the rubber spring, thereby preventing positional deviation due to temperature changes and reducing chattering or key-in delay between the key stem and the rubber spring. The purpose is to provide a key switch with few such problems.

Means for Solving the Problems This invention was made to solve the above problems, and consists of a key whose key stem is guided and supported in the vertical direction by a frame, and a pair of keys that are normally electrically insulated. A circuit pattern board that includes electrodes and both electrodes are electrically connected when the key is pressed, and a circuit pattern board that is interposed between the key and the circuit pattern board and always holds the key in the inoperative position by its own elastic force. The frame has a plurality of positioning protrusions projecting downward, and the flat base of the rubber spring has an opening at a position opposite to the positioning protrusions. A key switch configured to be positioned relative to the frame.

<Embodiment> Hereinafter, an embodiment of a key switch according to the present invention will be described based on an example of the drawings.

As shown in FIG. 1 (exploded perspective view), this key switch is constructed by passing an opening 13 formed in a flat base portion 15 of a rubber spring 11 through a positioning protrusion 5 projecting downward from a frame 3. The rubber spring 11 is positioned directly with respect to the frame 3. Each member will be explained in detail below.

As shown in FIG. 2, a cylindrical key guide 7 that guides and supports the key steam 33 of the key 31 in the vertical direction is formed on the frame 3, which also serves as the upper cover of the typewriter, and extends upward. Rubber spring 11 is paired with
A cylindrical downwardly extending portion 8 is formed to sandwich the flat base portion 15 between the circuit pattern board 21 and the circuit pattern board 21 . Furthermore, as shown in FIG. 4 (back side of the frame 3), positioning protrusions 5 are arranged at equal intervals between the first row (counting from above the 4th m; the same applies hereinafter) and the second row of the downwardly extending portion 8. Three trees are formed between the fourth and fifth columns, and three trees are formed equally spaced between the fourth and fifth columns. In addition, 9 is a boss part, and the first part of the downwardly extending part 8
Four pieces are formed at equal intervals between each row and the second row, and between the third and fourth rows. A screw 35 for fixing the support plate 25 and the frame 3 is screwed onto the boss portion 9.

This frame 3 is usually made of general-purpose resin such as ABS,
It will be done.

The rubber spring 11 has an inverted cup-shaped bulge 14 at a position facing the key guide 7 on the flat base portion 15.
A circular opening 13 is formed in the flat base portion 15 of the rubber spring at a position opposite to the positioning protrusion 5 of the frame 3, and a hole portion 19 for passing a screw 35 is formed at a position opposite to the boss portion 9. It is formed to have a diameter sufficiently larger than the diameter of the screw 35 (a so-called stupid hole). This rubber spring 11 is interposed between the key 31 and the circuit pattern board 21, and normally holds the key 31 in an inoperative position by its own elastic force. Examples of materials for the rubber spring 11 include silicone rubber from the standpoint of maintaining such elastic force for a long period of time.

The circuit pattern board 21 is a combination of a membrane switch 23 and a support plate 25. This membrane switch 23 is made by overlapping two elastic insulating films with a spacer interposed between them. A conductive layer is patterned. - The force support plate 25 supports the membrane switch 23 and shields the membrane switch 23 and other circuits. This circuit pattern board 21 has an opening 27 through which the positioning protrusion 5 of the frame 3 passes, and a membrane switch 2.
3 has a hollow hole 29 through which the screw 35 is passed and a support plate 25
Screw holes 28 are formed at opposing positions. As shown in the figure, the openings 27 have an oval shape in the longitudinal direction (horizontal direction in the figure) at both ends, and an oval shape in the width direction (in the figure) in order to allow expansion or contraction due to temperature changes in the frame 3, as shown in the figure. It is formed into an oval shape (in the diagonal vertical direction in the example). In addition, in the rubber spring 11, such distortion of the frame 3 can be followed by its own elastic deformation.As for the material of the circuit pattern board 21, a polystyrene film is used for the membrane switch 23, and a polystyrene film is used for the support plate 2.
5 shows iron plates as examples.

The assembly of each of the above members will be described based on FIG. The flat base portion 15 of the rubber spring 11 is held between the circuit pattern board 21 and the rubber spring 11, and the horizontal movement of the rubber spring 11 is restricted by the positioning protrusion 5 of the frame 3. It is fixed to the frame 3 with screws 35.

In the above, due to the below-described effects (accurate positioning ability 1 positional shift prevention ability) of the present invention, the outer circumferential shape of the key stem 33 of the key 31 is adjusted to the bulging portion 14 of the rubber spring 11 as shown in the example (see FIG. 2). Even if the key switch is formed approximately the same as the top shape of the key switch, it has little chattering and key-in delay, making it suitable for practical use.

<Effects of the Invention> As explained above, the key switch of the present invention allows the rubber spring to be moved by passing the opening formed in the flat base portion of the rubber spring through the positioning protrusion that protrudes downward from the frame. 11 is directly positioned with respect to the frame 3, the error in assembling the rubber spring and frame is smaller than in the conventional example. Furthermore, regarding the problem of expansion or contraction of the frame due to changes in environmental temperature, the rubber spring prevents the expansion or contraction of the frame by elastically deforming the flat base portion as the positioning protrusion moves as the frame expands or contracts. The position of the key stem and rubber spring will not shift.

Therefore, uneven contact between the key stem and the rubber spring is less likely to occur, and the single key switch has less chattering and key-in delay.

[Brief explanation of drawings]

The illustrated example shows an embodiment of the key switch of the present invention, and Figure i is an exploded perspective view showing the assembly of the frame 3, rubber spring 11, membrane switch 23, and support plate 25.
Figure 2 is a partially enlarged cross-sectional view of this key switch showing the contact of the key stem 33 and the connector 11; -■ A sectional view along the arrow line, and FIG. 4 is a back view of the frame 3. 3... Frame 5... Positioning protrusion 11... Rubber spring 13... Opening 15... Flat base portion 21... Circuit pattern board 24... Electrode 33... Key stem Patented wish person

Claims (1)

[Claims] A circuit including a key whose key stem is vertically guided and supported by a frame, and a pair of electrodes that are normally electrically insulated, and where the two electrodes are electrically connected when the key is pressed. The frame includes a patterned board, and an inverted cup-shaped rubber spring that is interposed between the key and the circuit pattern board and always holds the key in an inoperative position by its own elastic force, and the frame projects downward. In addition to having a plurality of positioning protrusions, the flat base portion of the rubber spring has an opening at a position opposite to the positioning protrusions, and is configured to position the rubber spring with respect to the frame. key switch.