JPH117862A - Key switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a key switch in which the freedom of indication printing on a key top is enhanced, and the switching operation of a contact is ensured. SOLUTION: An LED 5 is mounted on a lower base 1 having a central fixed contact 6 and a peripheral fixed contact 7, and an upper sheet 3 consisting of a light diffusive material is laminated on the lower base 1 and integrated thereto. The top part of a momentary spring 2 functioning as a movable contact is adhered to the lower surface of the upper sheet 3, so that the peripheral part of the momentary spring 2 is regularly brought into contact with the peripheral fixed contact 7, and its top part is separated from the central fixed contact 6 with a prescribed distance. A projection 8 is formed by printing on the upper surface of the upper sheet 3, and the forming position of the projection 8 is made to coincide with the top part of the momentary spring 2. A display part is formed by printing on the flat bottom surface of a key top 4 formed of a transparent material, and the pressing force is transmitted to the top part of the momentary spring 2 through the projection 8 and the upper sheet 3 when the top surface of the key top 4 is pressed, whereby the momentary spring 2 is buckled and reversed to make contact with the central fixed contact 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key switch which switches contacts by pressing a key top.

[0002]

2. Description of the Related Art A key switch is used as an input device of a cellular phone, an audio device, or the like, and is generally composed of a switch unit for switching contacts and a key top for operating the switch unit.

Conventionally, as such a key switch, a lower substrate provided with fixed contacts and a bowl-shaped tact spring are laminated and integrated using a sheet member or the like to constitute a switch unit portion. One in which a key top is supported by an outer case or the like in which the switch unit is incorporated has been proposed. The tact spring functions as a movable contact, and an on / off switching operation is performed when the tact spring contacts and separates from the fixed contact. The key top is printed with a display portion such as a numeral or a character indicating the function content, and a projection for pressing the top of the tact spring is formed integrally at the center of the bottom surface of the key top.

In the key switch constructed as described above, when the user presses the top surface of the key top, the pressing force is transmitted to the top of the tact spring via the projection on the bottom surface of the key top. Are buckled and inverted with a click feeling and come into contact with the fixed contact, so that the switch is turned on. Further, when the pressing force on the key top is removed, the tact spring returns to a bowl shape by its own resilience, so that the key top is pushed back to the initial position, and the switch is turned off.

[0005]

The display portion of the key top may be printed on the top surface or on the bottom surface. In the case of an illuminated key switch, the key top formed of a transparent material is used. Print the display on the bottom of the
A configuration in which a light source such as an LED is turned on in a dark place such as at night to irradiate light from the light source on the bottom surface of the keytop and visually recognize a display unit has been widely adopted.

However, in the above-described conventional key switch, since a projection for pressing the top of the tact spring is integrally formed on the bottom surface of the key top, a flat printing surface is secured on the bottom surface of the key top. However, there is a problem that the printing area of the display unit is largely limited.
In this case, it is conceivable to print the display unit on the top surface of the key top, but since the top surface of the key top is a part directly touched by the user, the display unit is easily peeled off due to repeated use. In the conventional key switch described above,
Since the switch unit and key top are positioned via the outer case etc., the key top projection is misaligned with respect to the top of the tact spring due to dimensional errors and assembly errors of each member. There is also a problem that the operation feeling of the tact spring is deteriorated, and the switching operation of the contacts becomes uncertain.

[0007]

According to the present invention, a movable contact is integrally provided on a lower surface of an upper sheet, and a projection for transmitting a pressing force from a keytop to the movable contact is formed on the upper sheet. I do. When the protrusion is formed on the upper sheet in which the movable contact is integrated in this way, not only can a flat printing surface be secured on the bottom surface of the key top, but also,
Even if the key top and the movable contact are displaced,
The pressing force from the keytop can be reliably transmitted to the movable contact.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a key switch according to the present invention, a lower substrate having fixed contacts, an upper sheet integrated with the lower substrate, and a lower surface of the upper sheet are provided integrally with the fixed contacts. A movable contact opposed to the fixed contact at a predetermined interval, and a key top for bringing the movable contact into and out of contact with the fixed contact; forming a protrusion at a position corresponding to the movable contact on the upper sheet; The pressing force from the top is transmitted to the movable contact via the projection.

The projections can be formed on either the upper surface or the lower surface of the upper sheet. When the projections are formed on the upper surface of the upper sheet, a part of the upper sheet may be expanded by embossing or the like. However, it is preferable to print a urethane resin or an epoxy resin on the upper sheet. Also,
An adhesive printed on the lower surface of the upper sheet may be used as the projection. In this case, a tact spring having a circular bowl shape may be used as the movable contact, and the tact spring may be bonded to the lower surface of the upper sheet by the projection.

The material of the upper sheet is not particularly limited. If an upper sheet made of a light-diffusing material is used, light from a light source is diffused by the upper sheet and applied to the bottom of the keytop. This is suitable for an illumination type key switch.

[0011]

Embodiments will be described with reference to the drawings.
FIG. 1 is a sectional view of a key switch according to one embodiment of the present invention,
FIG. 2 is a plan view of an upper sheet provided in the key switch. The key switch according to the embodiment is used as an operation panel of a mobile phone or the like. As shown in FIG. 1, the key switch drives a lower substrate 1, an upper sheet 3 having a tact spring 2 adhered to a lower surface, and a tact spring 2. And a key top 4 for performing the operation.

An LED as a light source is provided on the surface of the lower substrate 1.
5 is mounted, and a central fixed contact 6 and a peripheral fixed contact 7 surrounding it are provided. FIG. 1 shows only a pair of central fixed contacts 6 and peripheral fixed contacts 7,
In the embodiment, a plurality of pairs of the central fixed contact 6 and the peripheral fixed contact 7 are arranged in a matrix.

The tact spring 2 functions as a movable contact, and is formed by forming a metal spring material such as phosphor bronze into a bowl shape. The peripheral portion of the tact spring 2 is always in contact with the peripheral fixed contact 7, but the top is separated from the central fixed contact 6 with a predetermined space. The top of the tact spring 2 is adhered to the lower surface of the upper sheet 3. In the embodiment, a plurality of tact springs 2 are arranged in a matrix on the lower surface of the upper sheet 3 in accordance with the arrangement of the central fixed contact 6 and the peripheral fixed contact 7. Has been established.

The upper sheet 3 is made of PE having a matte surface.
It is made of a light diffusing material such as a T film, and has a projection 8 formed on the upper surface thereof. The positions where the projections 8 are formed correspond to the tops of the tact springs 2 bonded to the lower surface of the upper sheet 3. As shown in FIG. Is formed. These projections 8 are formed by, for example, printing a urethane-based resin on the upper surface of the upper sheet 3, and the projection amounts are made uniform by a printing technique. The peripheral portion of the upper sheet 3 and the lower substrate 1 are integrated with the frame 9 using an adhesive or the like, and these members constitute a switch unit.

The key top 4 is made of a transparent material such as an acrylic resin, and has a flat bottom surface on which a display portion (not shown) for numbers, characters, etc. is formed by printing. The upper part of the key top 4 protrudes from the guide hole 10a of the outer case 10, and the outer case 10 is fixed to the frame 9 using a screw or an adhesive. The bottom surface of the key tops 4 faces the projections 8 of the upper sheet 3. Therefore, in the embodiment, a plurality of key tops 4 are arranged in a matrix on the outer case 10.

In the key switch configured as described above, when the user presses the top surface of the desired key top 4, the pressing force is transmitted to the top of the lower tact spring 2 via the projection 8 and the upper sheet 3. Therefore, when the key top 4 is lowered by a predetermined stroke, the corresponding tact spring 2 buckles and reverses with a click feeling, and the top of the tact spring 2 contacts the central fixed contact 6 to switch on. Becomes At this time, even if the relative positions of the key tops 4 and the switch unit part are slightly shifted due to a dimensional error or an assembly error of each member, the protrusion 8 printed on the upper surface of the upper sheet 3 and the upper sheet 3 Since the relative position of the tact spring 2 adhered to the lower surface of the tact spring 2 is maintained with high accuracy, the operation feeling of the tact spring 2 does not deteriorate. Then, when the pushing force to the key top 4 is removed, the tact spring 2 returns to the bowl shape by its own spring property, and accordingly, the upper sheet 3 and the key top 4 are pushed back to the initial position, and the switch is turned on. It turns off. Further, when the LED 5 is turned on in a dark place such as at night, the light emitted from the LED 5 is diffused by the upper sheet 3 and illuminates the bottom surface of the key top 4 with substantially uniform brightness.
The display unit printed on the bottom surface of the display unit is illuminated with uniform and sufficient brightness, and the display unit can be clearly seen through the key top 4.

In the embodiment shown in FIG. 3, an adhesive is printed on the lower surface of the upper sheet 3 to form the projections 11, and the projections 11 are formed.
The top part of the tact spring 2 is adhered to the bottom. In this case, the projection 11 has a function of transmitting the pressing force of the key top 4 to the tact spring 2 and a function of bonding the tact spring 2 to the upper sheet 3.

In the embodiment shown in FIG. 4, a bulge 3a is formed in the upper sheet 3 by embossing.
A conductive ink serving as the movable contact 12 is printed on the lower surface of a, and a protrusion 8 is formed on the top of the upper surface of the bulging portion 3a. In this case, the bulging portion 3a and the movable contact 12 perform the same function as the tact spring 2 described above, and the bulging portion 3a buckles as the key top 4 is pressed, generating a click feeling.

In the embodiment shown in FIG. 4, when a click feeling is not required, a flat upper sheet 3 having no bulging portion 3a is connected to a lower substrate via a spacer as seen in a normal membrane switch. 1 and the protrusions 8 may be formed on the upper surface of the upper sheet 3 corresponding to the movable contacts 12, and a film material may be used as the lower substrate 1.

[0020]

The present invention is embodied in the form described above and has the following effects.

A lower substrate having a fixed contact, an upper sheet integrated with the lower substrate, and a movable contact integrally provided on a lower surface of the upper sheet and facing the fixed contact at a predetermined interval. A key top for bringing the movable contact into and out of contact with the fixed contact, forming a projection at a position corresponding to the movable contact on the upper sheet, and pressing force from the key top is applied via the projection. When configured to be transmitted to the movable contact, not only can a flat print surface be secured on the bottom surface of the key top, but even if the key top and the movable contact are displaced, The pressing force can be reliably transmitted to the movable contact.

When a light diffusing material is used as the upper sheet, light from a light source can be diffused by the upper sheet and applied to the bottom surface of the keytop, which is suitable for an illumination type key switch.

[Brief description of the drawings]

FIG. 1 is a sectional view of a key switch according to an embodiment of the present invention.

FIG. 2 is a plan view of an upper sheet provided in the key switch.

FIG. 3 is an explanatory view showing a modified example of a projection.

FIG. 4 is an explanatory view showing a modified example of a movable contact.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower board 2 Tact spring 3 Upper sheet 3a Swelling part 4 Key top 5 LED 6 Center fixed contact 7 Peripheral fixed contact 8, 11 Projection 9 Frame 10 Outer case 10a Guide hole 12 Movable contact

Claims (4)

[Claims] 1. A lower substrate having fixed contacts, an upper sheet integrated with the lower substrate, and a movable body integrally provided on a lower surface of the upper sheet and facing the fixed contacts at a predetermined interval. A contact and a key top for bringing the movable contact into and out of contact with the fixed contact, forming a projection on the upper sheet at a position corresponding to the movable contact, and a pressing force from the key top acting on the projection. The key switch is configured to be transmitted to the movable contact through the key switch. 2. The key switch according to claim 1, wherein the protrusion is made of a resin printed on the upper surface of the upper sheet. 3. The method according to claim 1, wherein the projections are formed of an adhesive printed on a lower surface of the upper sheet.
A key switch, wherein the movable contact made of a tact spring having a bowl shape is bonded to the projection. 4. The key switch according to claim 1, wherein the upper sheet is made of a light diffusing material.