JPH1097819A - Membrane switch - Google Patents

Abstract

(57) [Summary] [Problem] To provide a membrane switch in which an on-timing based on a touch of depression and an actual on-timing match. SOLUTION: An upper sheet 22a having an embossed portion 26 and a lower sheet 23a overlapped on a concave side of the upper sheet are formed by bending one PET film 21. This upper sheet 21a
A spacer sheet 25 is bonded between the lower sheet 21b and the lower sheet 21b. Embossed part 2 of upper sheet 21a
A circular electrode 22a is formed by printing on the concave surface of No. 6, and a circular electrode 23a is formed by printing at a position matching the electrode 22a of the lower sheet 21b. Electrode 22
a is led out to the surface of the lower sheet 21b where the electrodes 23a are formed by the conductive leads 22b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane switch as a thin switch used for electronic equipment such as a cellular phone, and more particularly to a membrane switch having a click feeling.

[0002]

2. Description of the Related Art A conventional membrane switch having a click feeling is provided with an upper sheet provided with embossed PET (polyethylene terephthalate) substrate, a lower sheet made of PET, and interposed between the upper sheet and the lower sheet. PE
And a spacer sheet made of T.

FIG. 6 is a sectional view showing a conventional membrane switch having a click feeling by embossing. A spacer sheet 3 is interposed between the upper sheet 1 and the lower sheet 2. The upper sheet 1, the lower sheet 2, and the spacer sheet 3 are all made of a PET base material, and the upper sheet 1 has an embossed portion 6. An electrode 4 is formed on the inner surface (concave surface) of the embossed portion 6 of the upper sheet 1 by an Ag paste circuit, and the inner surface of the lower sheet 2 facing the electrode 4 is similarly formed of Ag.
The electrode 5 is formed by the paste circuit.

The electrode 4 has a circular shape as shown in FIG. 7A, and the electrode 5 has a comb shape as shown in FIG. 7B. That is, the electrodes 5 are arranged such that one comb-tooth electrode 5a and the other comb-tooth electrode 5b enter between the other teeth. Then, when the opposing electrode 4 simultaneously contacts the electrodes 5a and 5b by pressing the embossed portion 6, the electrodes 5a and 5b conduct through the electrode 4, and the electrodes 5a and 5b are electrically connected. Turned on. The spacer sheet 3 is a PET sheet having a hole perforated with a diameter larger than the embossing diameter at a position matching the embossed portion 6 of the upper sheet 1, and a conventional membrane switch has such an upper sheet, a lower sheet,
It is composed of a three-layer laminate with the spacer sheet 3.

FIG. 8 is a view showing a method of embossing the upper sheet of the conventional membrane switch. The mold includes an upper mold 11 having a concave portion 13 for embossing and a lower mold 12 having a convex portion 14 for embossing. The convex portion 14 has a shape matching the concave portion 13. Then, after forming the electrode 4 made of a circular Ag contact circuit at a predetermined position on the upper sheet 1 made of PET, the upper sheet 1 is arranged so that the electrode 4 comes into contact with the convex portion 14. Thereafter, the upper mold 11 and the lower mold 12 are overlapped while the upper mold 11 and the lower mold 12 are heated by the internal heater, and the upper sheet 1 is moved to the upper mold 11 and the lower mold 1.
2 between. Then, the upper sheet 1 is deformed into the shape of the convex portion 14 and the concave portion 13 by the heat of the upper die and the lower die, and after maintaining this state for a predetermined time, the upper sheet 1 is separated from another unheated upper die and lower die. The upper sheet is sandwiched and the upper sheet is cooled. Thus, the embossed portion 6 shown in FIG. 6 is formed by hot pressing and cold pressing the upper sheet 1. At the time of embossing with a mold, a cushion sheet may be provided on the surface of the upper sheet on which the electrodes are not formed.

[0006] Next, PET coated with an adhesive on both sides
The membrane switch shown in FIG. 8 is manufactured by laminating the upper sheet 1 and the partial sheet 2 on both surfaces of the spacer sheet 3 formed by perforating a film at a portion corresponding to the embossed portion 6.

[0007]

However, the conventional membrane switch having an embossed portion has a disadvantage that the on-timing is delayed. FIG. 9 is a graph showing the relationship between the pressing distance of the upper sheet embossed portion 6 on the horizontal axis and the load value (reaction force) required for pressing the embossed portion on the vertical axis. When a load value measuring probe (not shown) is pressed at the moving speed of 3 mm / min to the center of the embossed portion 6 (convex portion) and the load value at that time is measured by a load cell, the load value is proportional to the pressing distance first. And increase. Thereafter, when the load value reaches the maximum load value, the convex shape of the embossed portion 6 is depressed as shown in FIG. 10, and the load value rapidly decreases. This gives a click feeling. Then, when the probe is going to descend further than the pressed point of the minimum load value, as shown in FIG. Therefore, the load value increases.

[0010] In the conventional membrane switch, as shown in FIG. 10, when the pressed position reaches the minimum load value, the electrode 4 comes into contact with both of the comb-teeth electrodes 5 a and 5 b of the electrode 5. No, and therefore not yet turned on. When the embossed portion 6 is further depressed, the comb-teeth electrodes 5a and 5b contact the electrode 4 for the first time and are turned on. Therefore, this on-load is higher than the minimum load value. Essentially, the click feeling is given when the center of the embossed portion 6 is concave and the center is convex downward in cross section. At this time, the load value drops to the minimum load value at a stretch, and if the load is turned on at this minimum load value, the on-feel when pressed down and the actual on-timing coincide. However, as described above, the conventional membrane switch has a problem that the on-timing is shifted from the timing of the minimum load value and is delayed by one tempo.

The actual ON timing is determined by the upper sheet 1
Is different depending on the parallelism, flatness, and approach angle of the rubber actuator 7 that presses down, and therefore, the degree of delay of the on-timing varies.

[0010] Further, since the conventional membrane switch uses the comb-tooth electrode, there is a problem that a contact failure with the opposing electrode is likely to occur due to blurring at the time of printing.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a membrane switch in which an on-timing based on a touch of depression and an actual on-timing match.

[0012]

SUMMARY OF THE INVENTION A membrane switch according to the present invention includes an embossed upper sheet, a lower sheet superimposed on a concave surface of the upper sheet, and printing on an embossed portion of the upper sheet. And a circular second electrode formed by printing at a position matching the first electrode on the lower sheet, and leading from the first electrode to the second electrode forming surface of the lower sheet. And a spacer inserted between the upper sheet and the lower sheet.

In the membrane switch, it is preferable that the upper sheet and the lower sheet are formed by folding one sheet, and the spacer is a spacer sheet sandwiched between the folded sheets.

In the present invention, a circular first electrode is formed on the upper sheet side, and the first electrode is led out to the lower sheet by conductive leads, and a circular second electrode is formed on the lower sheet side. The ON timing is detected by the contact between the two. For this reason, in the present invention, when the first electrode formed on the embossed portion of the upper sheet contacts even the second electrode of the lower sheet, at least partially, the on-timing is detected. As a result, the first and second electrodes are brought into contact with each other when the load value reaches the minimum load value due to the central portion being dented and deformed, and ON timing is obtained. For this reason, the on-timing based on the touch of depression corresponds to the actual on-timing.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a membrane switch according to an embodiment of the present invention, and FIG.
(A) is a circular electrode 22a formed on the upper sheet 21a.
FIG. 2B is a schematic view showing a circular electrode 23a formed on the lower sheet 21b. By bending the PET film 21, an upper sheet 21a and a lower sheet 21b are formed. A plurality of embossed portions 26 are formed in a portion to be the upper sheet 21a, and a circular electrode 22a is formed on an inner surface (concave surface) of the embossed portion 26. This circular electrode 22a is made of PE
It is led out to the lower sheet 21b side through the conductive lead 22b formed on the inner surface of the folded back of the T film,
It is connected to a circuit formed on the lower sheet 21b. A circular electrode 23a is formed at a position matching the electrode 22a of the lower sheet 21b. This circular electrode 23a
Are connected to the circuit 24 formed on the lower sheet 21b by the conductive leads 23b. The lower sheet 2
An electronic component (not shown) may be mounted on 1b.

The membrane switch of the present embodiment having the above-described configuration includes a circular electrode 22a formed on the upper sheet 21a and a circular electrode 23 formed on the lower sheet 21b.
When a is in contact with even a part of them, both electrodes are electrically connected and turned on. Therefore, the embossed portion 2
6 is depressed at its center, the load value drops sharply, and when the upper electrode 22a contacts the lower electrode 23a and the load value becomes the minimum value, the electrode 22a and the electrode 23a conduct and turn on. Becomes For this reason, as shown in FIG. 3, in the relationship between the load value and the pressing distance, the ON timing is obtained when the load value is the minimum load value. For this reason, the on-timing based on the feeling of pressing matches the actual on-timing.

Next, a method for manufacturing the above-described membrane switch will be described. FIG. 4 shows a processing apparatus for the PET film 21 of the present embodiment, and FIG. 5 is a view showing an embossing method in this processing apparatus. As shown in FIG. 4, a plurality of power supply units 30 are installed near the board 35, and a gate-shaped gantry 34 is installed so as to straddle the board 35. The main head 32 is disposed on the gantry 34 so as to be movable in the horizontal X direction by a ball screw.
A rail 35a extending in the Y direction perpendicular to the X direction is formed on two sides of the board 35.
Can move in the Y direction with respect to the gantry 34.

In the main head 32, a plurality (four in the illustrated example) of processing heads 31 are arranged with the block-shaped heater chip 40 portion downward. Each processing head 3
1 has a heater chip 40 having a hemispherical lower end as shown in FIG. 5, and the heater chip 40 can be moved up and down with respect to the head 31. Each of the heads 31 is connected to the power supply unit 30, and the heater chip 40 is supplied with power from the power supply unit 30 through the head 31 and generates resistance heat. In the vicinity of the heater chip 40, a nozzle 41 (see FIG. 5, not shown in FIG. 4) for jetting cooling air is arranged. The board 35 has a through hole 36 at a position to be embossed.

In the embossing apparatus thus configured, the electrodes 22a, 2a
3a and the leads 22b and 23b are formed by an Ag circuit, and the PET film 21 on which the electronic component is mounted is placed with the Ag circuit side facing upward. Then, while the gantry 34 is moved in the Y direction, the main head 32 is moved in the X direction, and the processing head 31 is moved to a position where the embossed portion is to be provided. Then, only the necessary one of the four processing heads 31 is lowered in the heater chip 40. Then, as shown in FIG.
Comes into contact with the PET film 21 and further descends so that the heater chip 40 enters the inside of the hole 36 and pushes down the PET film 21 locally. By maintaining this state for a predetermined time, an embossed portion 26 (recess) as shown in FIG. 1 is formed in the PET film 21. Thereafter, the heater chip 40 is raised and retracted, and air is jetted from the nozzle 41 to make the PET film 21 by the heater chip 40.
The pressing part is cooled. Next, the main head 32 and the gantry 34 are moved, and embossing is performed on another portion. In this way, the PET film can be embossed with high efficiency.

As described above, in this embossing apparatus, as shown in FIG. 8, unlike the case where embossing is performed using a die, the PET film 21 comes into contact with the heater chip 40 only at the position where the embossing is to be performed. Heat. Therefore, the embossed portion 2 of the PET film 21
Even if the leads 22b and 23b of the Ag circuit are formed in portions other than 6, the heater chip 40 does not come into contact with the portion of the Ag circuit, and embossing can be performed after the formation of the Ag circuit. When embossing is performed by using a mold as in the related art, the Ag circuit or the resist ink for insulating the circuit is transferred to the mold, and the embossing after the circuit is formed cannot be substantially performed. Further, as described above, since the embossing is performed by local heating and cooling, even if an electronic component is mounted on a portion to be the lower sheet 21b, there is no problem. It is also possible to emboss after shaping the outer shape of the upper sheet and the lower sheet. Further, electronic components can be mounted on portions other than the embossed portion 26 of the upper sheet. For this reason, the circuit layout is facilitated, and the degree of freedom in design is improved.

In this way, the electrodes and the Ag circuits for leads are formed on the PET film 21, the components are mounted, and after embossing, the PET film 21 is bent.
The spacer sheet 25 and the PET film 21 are joined together with a spacer sheet 25 made of PET coated with an adhesive on both sides interposed therebetween. Thereby, the membrane switch shown in FIG. 1 is manufactured.

In place of the spacer sheet 25, P
By forming a thick resist by printing on the surface of the ET film 21, a spacer can also be formed. Further, in this case, a pressure-sensitive adhesive layer is formed by printing on a portion to be the upper sheet, and thereafter, by embossing, the pressure-sensitive adhesive layer and the resist are bonded to each other, whereby a membrane switch can be assembled.

[0023]

As described above, according to the present invention,
When the first electrode and the second electrode are both circular electrodes, and the embossed portion is deformed beyond its maximum load by pressing down, when the load value is minimized by contacting both electrodes, Conduction occurs between the two electrodes, and the contact is turned on.
For this reason, the on-timing based on the feeling of pressing the membrane switch and the actual on-timing match, the delay of the on-timing is eliminated, and a membrane switch with excellent operational feeling can be obtained.

Further, by forming the upper sheet and the lower sheet into a single sheet folded back, the upper sheet and the lower sheet are integrated with each other. Only sticking and bending are required, making assembly easier.

Furthermore, since the present invention is a circular electrode, the influence of blurring at the time of printing, which has been a problem with the comb-shaped contact, is eliminated, and the defect rate is reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a membrane switch according to an embodiment of the present invention.

2A is a diagram showing a circular electrode formed on an upper sheet, and FIG. 2B is a diagram showing a circular electrode formed on a lower sheet.

FIG. 3 is a diagram showing a relationship between a load value and a pressing distance of the membrane switch of the embodiment.

FIG. 4 is a schematic perspective view showing a processing device of the embossed portion of the present embodiment.

FIG. 5 is a sectional view showing the embossing method.

FIG. 6 is a sectional view showing a conventional membrane switch.

FIG. 7 (a) is an electrode formed on the upper sheet,
(B) is a figure which shows the electrode formed in the lower sheet.

FIG. 8 is a view showing a conventional embossing device.

FIG. 9 is a diagram illustrating a relationship between a load value and a pressing distance of a conventional membrane switch.

FIG. 10 is a view for explaining a drawback of a conventional membrane switch.

[Explanation of symbols]

 1, 21a: upper sheet 2, 21b: lower sheet 3, 25: spacer sheet 21: PET film 22a, 23a: circular electrode 22b, 23b: lead 31: processing head 35: board 40: heater chip

Claims (2)

[Claims] 1. An embossed upper sheet, a lower sheet superimposed on a concave surface of the upper sheet, a circular first electrode formed by printing on a concave surface of the embossed portion of the upper sheet, and A circular second electrode formed by printing at a position corresponding to the first electrode of the sheet; conductive leads extending from the first electrode to a second electrode forming surface of the lower sheet; A membrane switch comprising: a spacer interposed between a sheet and a sheet. 2. The membrane according to claim 1, wherein the upper sheet and the lower sheet are formed by folding one sheet, and the spacer is a spacer sheet sandwiched between the folded sheets. switch.