JPH0752240A - Manufacture of embossed sheet for membrane switch - Google Patents

Abstract

PURPOSE:To provide the manufacturing method of embossed sheet for membrane switch, from which the embossed sheet excellent in heat resistance can be produced and, at the same time, which is excellent in productivity. CONSTITUTION:PET sheet 1a is conveyed one by one with a conveying means from sheet bundle 1 so as to heat the PET sheet 1a with heaters 2 in a heater zone 5 up to its glass transition temperature or higher. The resultant PET sheet 1a embossed by a crank press 4 so as to obtain embossed sheet 1b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an embossed sheet for a membrane switch used as a click feeling imparting member in a membrane switch which is one of thin switches used for electronic equipment and the like.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing an example of a membrane switch. One or a plurality of pairs of electrodes 12 are patterned on the printed circuit board 11. On the printed board 11, an insulating layer 13 (spacer) having an opening 13a in a portion aligned with the electrode 12 is joined.
A flexible sheet 14 is arranged on the insulating layer 13, and a counter electrode 15 is provided on a portion of the back surface of the flexible sheet 14 corresponding to the electrode 12.

In the membrane switch thus constructed, the flexible sheet 15 is deformed by pushing a portion of the flexible sheet 14 corresponding to the counter electrode 15 with a finger or the like, and the pair of the counter electrodes 15 are paired. Both of the electrodes 12 are contacted. Then, the pair of electrodes 12 are electrically connected via the counter electrode 15.

However, in the membrane switch shown in FIG. 2, since there is no click feeling when the flexible sheet 14 is pressed with a finger, it is determined whether the counter electrode 15 and the pair of electrodes 12 are in contact with each other. There is a drawback in that it cannot be confirmed visually.

FIG. 3 is a sectional view showing a membrane switch which eliminates the above-mentioned drawbacks. This membrane switch is different from the membrane switch shown in FIG. 2 in that a click spring 17 is provided on the flexible sheet 14, and other configurations are basically the same as those shown in FIG. 3, the same components as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

That is, in this membrane switch, the insulating layer 16 (spacer) is bonded onto the flexible sheet 14. The insulating layer 16 is provided with an opening 16a in a portion aligned with the electrode 12, and the opening 16a is provided.
A circular dome-shaped metallic click spring 17 is provided in a. A flexible surface sheet 18 is provided on the insulating sheet 16.

In the membrane switch thus constructed, when the portion of the surface sheet 18 corresponding to the click spring 17 is pushed with a finger or the like, the top of the click spring 17 is displaced and deformed. In this case, since the deformation of the click spring 17 is such that the top of the dome is dented, a click feeling is obtained during this displacement. Then, the dome top of the recessed portion presses the flexible sheet 14, and the flexible sheet 1
4 is deformed, and the counter electrode 15 electrically contacts the pair of electrodes 12. As a result, the pair of electrodes 12 are electrically connected via the counter electrode 15, and the switch is turned on. Then, when the finger or the like is released from the surface sheet 18, the elastic force of the click spring 17 returns to the initial state, the pair of electrodes 12 is electrically separated, and the switch is turned off.

By the way, in the case of the membrane switch shown in FIG. 3, a metal click spring is used as a member for obtaining a click feeling. Therefore, in this membrane switch, a step of forming the metal plate into a dome shape is required, and a click spring is required to be arranged in the opening 16a of the insulating layer 16, which is a drawback that the manufacturing process is complicated. is there. Therefore, a membrane switch has been developed in which the sheet can be embossed (convexed) to provide a click feeling without using a metal spring.

FIG. 4 is a cross-sectional view showing a membrane switch provided with an embossed sheet. The difference between this membrane switch and the switch shown in FIG. 3 is that
The embossing sheet 24 is provided in place of the flexible sheet 14 and the click spring 17, and other configurations are basically the same as those shown in FIG. Are denoted by the same reference numerals and detailed description thereof will be omitted.

That is, in the membrane switch shown in FIG. 4, the embossed sheet 2 which is embossed.
4 is disposed on the insulating layer 13. The embossed sheet 24 is arranged so that the convex portions 24 a are aligned with the pair of electrodes 12. Further, on the inner surface of the convex portion 24a,
A counter electrode 25 is provided. On the embossed sheet 24, an insulating layer 16 having an opening 16a provided in a portion aligned with the convex portion 24a is joined. A flexible surface sheet 18 is provided on the insulating layer 16.

In the membrane switch thus constructed, when a portion of the surface sheet 18 corresponding to the convex portion 24a is pushed with a finger or the like, the convex portion 24a is deformed and the top thereof is dented, and the counter electrode 25 forms a pair. Contact the electrode 12. As a result, the pair of electrodes 12 are electrically connected to each other via the counter electrode 25. In this case, a click feeling is obtained when the convex portion 24a is deformed. When the finger or the like is released from the surface sheet 18, the convex portion 24a returns to the initial state by the elastic force, and the pair of electrodes 12 is electrically separated.

The membrane switch using the embossed sheet has the advantages that the number of constituent members can be reduced, the manufacturing cost can be reduced, and inversion failure hardly occurs and the switch operation is stable.

Conventionally, an embossed sheet for a membrane switch is manufactured by molding a flat insulating resin sheet with a hot press machine heated to a high temperature, holding it for a certain period of time, and then pressing it with a cold press machine. There is also a method of embossing a sheet only with a cold press machine without using a hot press machine.

[0014]

However, the method for producing an embossed sheet by using both a hot press machine and a cold press machine has the advantage that the characteristic deterioration of the embossed sheet due to high temperature is small, but it does not affect the sheet. Due to the need for heat transfer, it is necessary to hold the sheet for a certain period of time while being pressed by a hot press machine, which has the drawback of poor productivity. On the other hand, the method of embossing a sheet with only a cold press machine has good productivity because it does not require holding time, but when the embossed sheet is stored or used at high temperature for a long time, the shape of the convex portion changes. Then, there is a drawback that characteristics such as elasticity are deteriorated. Therefore, the embossed sheet produced only by the cold press machine is difficult to store and use for a long time, and
Applications are limited to devices that are not exposed to high temperatures.

The present invention has been made in view of the above problems, and is an emboss for a membrane switch capable of producing an emboss sheet having excellent productivity, heat resistance, and long-term storage and use. It is an object to provide a method for manufacturing a sheet.

[0016]

A method for manufacturing an embossed sheet for a membrane switch according to the present invention comprises a step of heating an insulating resin sheet to a temperature not lower than its glass transition temperature, and then the insulating resin sheet by a press machine. And a step of embossing.

[0017]

The insulating resin such as PET (polyethylene terephthalate) has the characteristic that when it is deformed at a temperature higher than its glass transition temperature, it retains its shape even when returned to room temperature. In the present invention, this property is utilized to improve the heat resistance of the embossed sheet. That is, in the present invention, first, the insulating resin sheet is heated to a temperature equal to or higher than its glass transition temperature by an appropriate heating means so as to be easily subjected to the thermoplastic deformation. Then, the insulating resin sheet is embossed by using a press machine, and thereafter, for example, it is forcibly cooled. Then, the insulating resin sheet maintains the shape when embossed, and deformation is suppressed even when exposed to high temperature. That is, the embossed sheet produced in this manner has a small change in properties such as deterioration of elasticity even when stored or used at high temperature, and has good heat resistance.

Further, in the method of the present invention, the insulating resin sheet is heated to a temperature not lower than its glass transition temperature by an appropriate heating means and then plastically deformed by a press machine for embossing. Unlike the case, it is not necessary to hold the insulating sheet in the hot press machine for molding. Therefore, according to the present invention, since continuous molding by a press machine is possible, productivity is improved.

[0019]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing a method for manufacturing an embossed sheet for a membrane switch according to an embodiment of the present invention. First, the PET sheet 1a is separated from the PET sheet bundle 1 one by one by an appropriate conveying means, and the heater zone 5 is separated.
Transport to. In the heater zone 5, the preheating heater 2 is arranged above and below the sheet conveying path. A crank press 4 including a lower die 3a and an upper die 3b for embossing is arranged in the heater zone 5. In the heater zone 5, the PET sheet 1a is heated by the heater 2 to a temperature equal to or higher than the glass transition temperature (about 69 ° C.) while the PET sheet 1a is being conveyed by the conveying means. The PET sheet 1a heated to the glass transition temperature or higher is sandwiched between the lower die 3a and the upper die 3b of the crank press 4 to emboss the PET sheet 1a.

Next, the embossed PET sheet (embossed sheet 1b) is carried out from the heater zone 5 by the carrying means. An air blower 6 is provided near the outlet of the heater zone 5, and cool air is blown toward the embossed sheet 1b by the air blower 6 to forcibly cool the embossed sheet 1b. This completes the production of the embossed sheet.

In this embodiment, the heater 2 is used for PE.
Since the T sheet 1a is heated above its glass transition temperature and then embossed by the crank press 4, the high temperature characteristics of the embossed sheet 1b are good, and the shape changes little even when exposed to high temperatures. Further, since the PET sheet 1a is heated by the heater 2 while being conveyed in the heater zone 5, the holding time required in the method using the conventional hot press machine is unnecessary, and the PET sheet 1a is continuously embossed sheet. Therefore, the productivity is improved.
As a result, the present invention has the effect of expanding the product applicable range of the membrane switch provided with the embossed sheet.

[0023]

As described above, in the method for manufacturing an embossed sheet for a membrane switch according to the present invention,
Since the insulating resin sheet is heated to a temperature equal to or higher than its glass transition temperature and the insulating resin sheet is embossed by a press machine, it is possible to produce an embossed sheet having excellent productivity and excellent heat resistance. .

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a method for manufacturing an embossed sheet for a membrane switch according to an example of the present invention.

FIG. 2 is a cross-sectional view showing an example of a membrane switch.

FIG. 3 is a cross-sectional view showing a membrane switch having a click feeling.

FIG. 4 is a cross-sectional view showing a membrane switch provided with an embossed sheet.

[Explanation of symbols]

 1; Sheet bundle 1a; PET sheets 1b, 24; Embossed sheet 2; Heater 4; Crank press 5; Heater zone 6; Air blow device 11; Printed circuit board 12; Electrodes 13, 16; Insulating layer 14; Flexible sheet 15 , 25; counter electrode 17; click spring 18; surface sheet

Claims (1)

[Claims] 1. An emboss for a membrane switch comprising: a step of heating an insulating resin sheet to a temperature equal to or higher than its glass transition temperature; and a step of embossing the insulating resin sheet with a press machine. Sheet manufacturing method.