JP2548303Y2 - Push button switch - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 more particularly to a push button switch suitable for miniaturization and thinning.

[0002]

2. Description of the Related Art FIG. 7 is a cross-sectional view showing a conventional example of a push button switch of this type. In the drawing, reference numeral 1 denotes a reinforcing plate made of a hard material such as metal, and a membrane switch is provided on the reinforcing plate 1. 2 is placed. The membrane switch 2 includes 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, 2d. A housing 3 made of a synthetic resin is mounted on the membrane switch 2. The housing 3 has an annular guide cylinder 3a and a projection 3b located outside thereof.
And are integrally formed. In the guide cylinder 3a, a stem 4a vertically suspended from the ceiling surface of a synthetic resin key top 4 is slidably inserted. A coil spring 5 is attached to the stem 4a by strong fitting. I have. A return spring 6 is interposed between a flat surface formed between the guide cylinder 3a and the projection 3b and a ceiling surface of the key top 4. Although not shown, a cutout groove having an upper end serving as a locking surface is formed in the protruding portion 3b in a direction orthogonal to the paper surface of FIG. 7, while the key top 4 has a notch. A locking piece that moves up and down along the notch groove is projected from the housing 3 of the key top 4 by locking the claw tip of the locking piece to the upper end of the notch groove when not operating. Is prevented from falling off.

Next, the operation of the push button switch configured as described above will be described. In the non-operation state shown in FIG. 7, the key top 4 is positioned at the highest point of the stroke where the tip claw portion of the not-shown locking piece abuts on the upper end of the notch groove by the elastic force of the return spring 6. At this time, since the lower end of the coil spring 5 is separated 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. From this state, when the operator pushes the key top 4 against the elastic force of the return spring 6, the outer wall of the stem 4a descends along the inner wall of the guide tube 3a, and the key top 4 is moved to the lowest stroke point. At this time, the coil spring 5 held in the stem 4a
Is gradually compressed by contact with the upper sheet 2b, the elastic force of the coil spring 5 causes the upper sheet 2b to bend downward, the movable contact 2a comes into contact with the fixed contact 2c, and the membrane switch 2 is turned off. It is switched to the ON state. When the pressing operation force on the key top 4 is removed in this ON state, the key top 4 is raised to the highest point of the stroke shown in FIG. 7 by the elastic force of the return spring 6, so that the bent upper sheet 2b is restored. Accordingly, the movable contact 2a is separated from the fixed contact 2c, and the membrane switch 2 is switched from on to off.

[0004]

In the case of this type of push button switch, the stem 4a is inserted into the guide tube 3a and brought into sliding contact, whereby the key top 4 is held in the housing 3 so as to be able to move up and down. Therefore, attempts have been made to reduce the height of the guide cylinder 3a in order to reduce the thickness of the push button switch while securing a desired operation stroke. In this case, however, the insertion of the stem 4a into the guide cylinder 3a is attempted. The amount is inevitably reduced, and the key top 4 is easily inclined with respect to the housing 3 due to the minute clearance required for sliding contact. In particular, when the operator pushes the edge of the key top 4 so-called end pushing, the stem 4a is moved to the guide cylinder 3a.
And the operation feeling becomes extremely poor.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a push button switch which can be reduced in size and thickness without deteriorating the operation feeling.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cylindrical portion between a housing and a key top, which is slidable with respect to a guide cylinder and a stem and one end of which drives a switch element. An actuator having a resilient piece extending laterally from the other end of the cylindrical portion and abutting on the key top is provided.
This is achieved by forming a concave notch for loosely inserting the base of the elastic piece.

[0007]

According to the above means, since the cylindrical portion of the actuator moves relative to the guide tube and the stem, the height of the guide tube can be reduced without reducing the sliding distance. Since the tubular portion presses and drives the switch element, it is not necessary to incorporate a driving coil spring in the stem, so that the diameter of the stem and the guide tube can be reduced, and the concave cutout of the guide tube during the pressing operation. By releasing the base of the elastic piece of the actuator into the inside, the uppermost point of the stroke of the actuator can be set at a lower position.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a non-operation state of a push button switch according to an embodiment of the present invention, FIG. 2 is a transverse sectional view of the push button switch, FIG. 3 is a perspective view of an actuator used for the push button switch, FIG. 4 is a side view of the actuator, and FIG.
FIG. 6 is a bottom view of a key top used in the push button switch, and FIG. 6 is a longitudinal sectional view showing a pressing operation state of the push button switch. Parts corresponding to those in FIG. is there. In these figures, a stem 4b suspended from the ceiling surface of the key top 4 is formed in a columnar shape, and a pair of locking pieces 4c is protruded at a position opposed to the stem 4b via the stem 4b. The tip claw portions of the locking pieces 4c are freely lifted and lowered into the notch grooves 3d of the pair of locking walls 3c provided upright on the inner bottom surface of the housing 3 via the guide cylinder 3a. When the key top 4 is inserted and is not operated, the locking pieces 4c are locked to the upper ends of the notches 3d so that the key top 4 does not fall off the housing 3. In addition to the stem 4b and the locking piece 4c, a flat portion 4d and projections 4e and 4f having the same height on the bottom surface protrude from the ceiling surface of the key top 4, but the ceiling surface as a whole is It is tilted along the top. That is, the key top 4 is formed into a shape having a substantially uniform plate thickness. The actuator indicated by reference numeral 7 in the drawing has a cylindrical portion 7a having an outer diameter equal to the inner diameter of the guide tube 3a and an inner diameter equal to the outer diameter of the stem 4b, and the cylindrical portion 7a.
A pair of substantially crank-shaped elastic pieces 7b extending in opposite lateral directions from the upper end of the pair of elastic pieces 7b, and a pair of locking pieces 7 which are respectively suspended from the elastic pieces 7b and face each other via the cylindrical portion 7a.
c, and the actuator 7
Is inserted into the guide cylinder 3a, and the cylindrical part 7a is inserted into the guide cylinder 3a.
The lower end of the cylindrical portion 7a can press and drive the membrane switch 2 at the time of operation by inserting the stem 4b into a. Further, by making the tip portions of the pair of elastic pieces 7b stand up and making contact with the flat portions 4d and the protrusions 4e of the key top 4, when the key top 4 is lowered by a predetermined amount, each elastic piece 7b is elastically deformed. Further, each elastic piece 7b is formed with a protruding piece 7d extending toward the gap A so that the gap A defined between them is smaller than the plate thickness dimension. Have been. The notch grooves 3f of the pair of locking walls 3e, which are provided on the inner bottom surface of the housing 3 at the positions opposed to each other via the guide cylinder 3a, respectively, are provided at the tip claw portions of the pair of locking pieces 7c.
The actuator 7 is prevented from dropping from the housing 3 by being freely inserted into the inside of the housing 3 so as to freely move up and down, and each of the locking pieces 7c is locked to the upper end of each of the notch grooves 3f when not operating. The two notches 3 on the inner bottom surface of the housing 3
The arrangement of d and the two notch grooves 3f is set such that these four notch grooves 3d and 3f are located at the respective vertices of the rhombus. In other words, the two locking pieces 4c of the key top 4 are positioned at two opposing vertices of the diamond in plan view, and the two locking pieces 7c of the actuator 7 are positioned at the remaining two vertices of the diamond. The projecting positions of the two locking pieces 4c and 7c are determined. Further, the guide cylinder 3a of the housing 3
A pair of concave notches 3g for loosely inserting the bases of the elastic pieces 7b of the actuator 7 are formed at the distal end of the elastic piece 7b.
Is set about 0.6 mm lower than the lowest point of the stroke of the base. Further, the guide cylinder 3a of the housing 3
The height position of the upper end surface is set to be about 0.3 mm lower than the lowermost point of the stroke of the ceiling surface of the key top 4, and the height position of the upper end surface of both locking walls 3c is the flat portion of the key top 4. It is set to be about 0.3 mm lower than the lowermost point of the stroke of the projections 4d and the projections 4f. That is, the dimensions are designed in advance to allow a clearance of about 0.3 mm so that the key top 4 and the actuator 7 do not collide with the housing 3 at the lowest point of the stroke. The click rubber indicated by reference numeral 8 in the drawing is formed in an inverted dome shape, is interposed between the housing 3 and the actuator 7, and has a large-diameter portion on the upper end abutting on the elastic piece 7b, and a lower end on the lower end. The small diameter portion is inserted outside the guide cylinder 3a. Other configurations such as the reinforcing plate 1 and the membrane switch 2 are the same as those of the above-described conventional example. Next, the operation of the push button switch configured as described above will be described. FIG.
In the non-operation state shown in FIG. 7, the key top 4 and the actuator 7 are pushed up to the respective stroke top points by the elastic force of the click rubber 8. That is, each locking piece 4c of the key top 4 contacts the upper end of the notch groove 3d, and each locking piece 7c of the actuator 7 contacts the upper end of the notch groove 3f. At this time, the lower end of the cylindrical portion 7a of the actuator 7 is separated from the upper sheet 2b, and the membrane switch 2 is in the off state. From this state,
When the operator pushes the key top 4 against the elastic force of the click rubber 8, the click rubber 8 generates a click feeling and reverses as the cylindrical portion 7a descends in the guide tube 3a, and the pair of elastic pieces 7b Are loosely inserted into the pair of concave notches 3g. Next, as shown in FIG. 6, as the stem 4b descends inside the cylindrical portion 7a,
Each elastic piece 7b pushed into the flat portion 4d and the projection 4e of the key top 4 bends, and the lower end of the tubular portion 7a presses the membrane switch 2 by the reaction force. In other words, the lower end of the cylindrical portion 7a presses the upper sheet 2b and the movable contact 2
a contacts the fixed contact 2c, and the membrane switch 2 is switched from off to on. Then, when the pressing operation force on the key top 4 is removed from the on state,
Since the actuator 7 rises to the highest point of the stroke by the elastic force of the click rubber 8, the movable contact 2a is separated from the fixed contact 2c, and the membrane switch 2 is switched from the on state to the off state. And, it rises to the stroke top point by the elastic force of both elastic pieces 7b. As described above, in the above embodiment, the actuator 7 is interposed between the housing 3 and the key top 4, and when the key top 4 is pressed, the cylindrical portion 7a of the actuator 7 is moved relative to the guide cylinder 3a and the stem 4b. The sliding distance is approximately doubled without changing the height of the guide cylinder, compared to the conventional product, in which the stem slides directly on the guide cylinder. Can be. In other words, it is possible to reduce the overall height of the push button switch while maintaining the same sliding feeling as that of the conventional product. In addition, when the base of the elastic piece 7b of the actuator 7 is released into the concave notch 3g of the guide cylinder 3a during the pressing operation, the highest point of the stroke of the actuator 7 is set to a low position, and the storage space for the actuator 7 Are designed so as not to hinder the reduction of the overall thickness of the push button switch. Further, since the lower end of the cylindrical portion 7a of the actuator 7 presses and drives the membrane switch 2, the diameter of the stem 4b and the guide cylinder 3a is smaller than that of a conventional product in which a driving coil spring is incorporated in the stem. As a result, a small push button switch capable of storing the click rubber 8 outside the guide cylinder 3a is obtained. Further, in the above embodiment, the key top 4 is placed on the actuator 7 in which the pair of locking pieces 7c are locked to the housing 3, so that the key top 4 has its own locking piece 4c and the actuator 7 Are supported at a total of four locations of the locking pieces 7c, and the occurrence of backlash can be prevented. Moreover, the locking piece 7c prevents the actuator 7 from dropping out of the housing 3, so that the housing 3, the click rubber 8 and the actuator 7 can be semi-finished, and the actuator 7 is provided with a protruding piece 7d. Since the gap A is made smaller than the thickness of the elastic piece 7b, the elastic pieces 7b of the actuator 7 are not entangled with each other during the assembling work, so that good assembling workability can be expected. Further, in the above embodiment, a projection 4e for pushing the tip of the elastic piece 7b of the actuator 7 is provided at a portion of the ceiling surface of the key top 4 where the ceiling rises, whereby the key top 4 is moved to the ceiling. Since the surface is inclined in the same manner as the top surface and has a substantially uniform thickness, the moldability of the top 4 is good. Further, in order to prevent the key top 4 and the actuator 7 from colliding with the housing 3 at the lowermost point of the stroke, 0.
The design dimension is designed to allow for a clearance of about 3 mm, and the protrusion 7a of the actuator 7 pushes the upper sheet 2b of the membrane switch 2 to determine the lowest point of the stroke. The impact sound and impact at the time are greatly reduced, and the distance between the contact portion of the membrane switch 2 and the cylindrical portion 7a becomes larger than the design value due to the deformation of the reinforcing plate 1 and the error of the processing dimension of each member. In the event of an accident, if the increase is within the range of the clearance that is anticipated in advance, the lowest point of the stroke of the key top 4 and the actuator 7 is slightly lowered, and there is no possibility of malfunction. That is, as compared with a conventional product in which little clearance is expected between the key top and the housing at the lowest point of the stroke, an operation failure due to deformation and dimensional error is less likely to occur, and the reliability is high. In the above-described embodiment, the click rubber 8 is used as an elastic member for raising (returning) the key top 4, but a coil spring may be used instead of the click rubber and used as a non-click push button switch.

As described above, the push button switch according to the present invention can reduce the height of the guide tube of the housing without reducing the sliding distance,
By releasing the base of the elastic piece into the concave notch of the guide cylinder, the uppermost point of the stroke of the actuator can be set at a lower position, so that the entire push button switch can be made thinner and the key top stem can be made thinner. Since there is no need to incorporate a driving coil spring into the drive unit, the diameter of the stem and the guide cylinder can be reduced, and the pushbutton switch can be downsized. If the clearance is designed in advance so that the key top and the actuator do not collide with the housing at the lowest point of the stroke, malfunctions due to deformation and dimensional errors are less likely to occur, and the effect of increasing reliability is also achieved. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a non-operation state of a push button switch according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the push button switch.

FIG. 3 is a perspective view of an actuator used for the push button switch.

FIG. 4 is a side view of the actuator.

FIG. 5 is a bottom view of a key top used for the push button switch.

FIG. 6 is a vertical cross-sectional view showing a pressing operation state of the push button switch.

FIG. 7 is a vertical sectional view of a push button switch according to a conventional example.

[Explanation of symbols]

 2 Membrane switch 3 Housing 3a Guide cylinder 3g Concave cutout 4 Key top 4b Stem 7 Actuator 7a Cylindrical part 7b Elastic piece 8 Click rubber

Claims (2)

(57) [Scope of request for utility model registration] 1. A switch element, a housing having a guide cylinder, a key top having a stem for elevating and lowering along the guide cylinder, and an elastic member for elevating the key top. The switch element is pressed and driven by lowering the key top, and between the housing and the key top, one end of the switch element is slidable with respect to the guide cylinder and the stem, and one end of the switch element is slidable. An actuator having a tubular portion for pressing and driving, and an elastic piece extending in the lateral direction from the other end of the tubular portion and abutting on the key top, is provided. A push button switch having a concave notch for loosely inserting a base of a piece. 2. The housing according to claim 1, wherein an end surface of the housing facing the ceiling surface of the key top is set at a position lower than a lowest stroke point of the ceiling surface, and a concave notch of a guide cylinder of the housing is provided. A push button switch wherein the inner bottom surface is set at a position lower than the lowest stroke point of the base of the elastic piece of the actuator.