JPS6362117A - Waterproof flat keyboard - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a waterproof flat keyboard, and particularly to a flat keyboard with improved waterproofness due to a novel structure.

[Technical Background of the Invention] As a recent trend, membrane-type keyboards having extremely thin and flat switch sections have been increasingly used in electronic desktop calculators, electronic pillars, and the like. Compared to keyboards made of mechanical switches or diaphragm-type rubber switches, this keyboard does not feel as clicky when pressed, but it has the advantage that the key tops are flat and the overall structure is thin.

Conventionally, the following two methods have been used to manufacture membrane type keyboards. (1) An opening corresponding to the conductive layer area is provided between the conductive layer area formed on the back side of the button with numbers, letters, symbols, etc. and the corresponding electric circuit forming each desired contact point. A method of incorporating a flexible intermediate insulating sheet, ie, a spacer (Japanese Utility Model Publication No. 52-5798). (2) Thickness o, ogo ~ in the part of the electric circuit that formed each contact part, excluding the contact part.
A method of providing a spacer made of printed and hardened insulating rubber to a thickness of about 0.300 mm and bonding this to a conductive layer area formed on the back side of a button with numbers, letters, symbols, etc. 59340).

Of these two methods, method (1) uses a hard spacer made of an insulating sheet, which creates a slight gap between the spacer and the board forming the electric circuit, which is fatal to waterproof performance. becomes. In addition, this method requires a long and complicated assembly process, and the cost is high because the spacer opening must be manufactured accurately.

Method (2), as shown in Japanese Unexamined Patent Publication No. 56-59340, uses a method such as screen printing on a part of the spacer using a paint made of rubber-based and resin-based insulating adhesive. This method is superior in airtightness compared to method (1). However, in order to obtain high reliability as a switch function,
It is necessary to select the thickness of the spacer film within the range of o, oao to 0.300 mm. However, obtaining this film thickness in one step of screen printing requires extremely advanced technology, which is considered a major drawback. In addition, there has been a recent demand for improvement in the waterproofness of keyboard switches, as applications other than electronic desktop calculators have expanded and the required characteristics have become more stringent. is becoming stronger.

[Object of the Invention] The object of the present invention is to solve the above-mentioned drawbacks and, in response to the demands, to provide a waterproof flannel keyboard which is particularly excellent in waterproofness, and which significantly improves the reliability of the switch function and the lifespan of the keyboard. The goal is to provide the following.

[Structure of the Invention] As a result of intensive studies to achieve the above object, the inventors of the present invention have provided an insulating elastic film and an adhesive layer each consisting of a thin layer in the middle of a substrate having a pair of contact electrodes. The present inventors have discovered that the interposed structure is extremely excellent in waterproofing properties of keyboard switches, and have come up with the present invention.

That is, the present invention provides a flat keyboard comprising a pair of first and second insulating substrates and a contact portion (frame) having a thickness o, oos ~ 0.050 mm at mutually corresponding positions on both substrates. (a) At least one of the insulating substrates is provided on the area excluding the contact electrode and the narrow part inside the outer periphery of the contact electrode, and has a thickness equal to that of the contact electrode. or more, and 0.010 to 0.080mm
(b) an insulating adhesive layer provided on the elastic film and having a thickness of o, oio to 0.080 mm; The waterproof flat keyboard is characterized in that a flexible substrate and a pair of the insulating substrate are fixed together through the adhesive layer.

The insulating (all electrically insulating in this specification means electrically insulating) substrates used in the present invention are composed of a pair of first and second substrates.

The substrate materials include polyester, polyamide, polyimide, polycarbonate, polypropylene, polyvinyl chloride, natural and synthetic rubber, unsaturated polyester resin,
You can choose from epoxy resins, phenolic resins, silicone resins, etc. However, the materials illustrated here are not particularly limited, and other materials may also be used. In addition, these materials may be used singly or as a composite of two or more types, such as laminates obtained by impregnating paper or glass cloth, or molded products containing solid materials such as metal oxides and glass fibers. It may also be a composite material. These substrates may be either film-like or plate-like.

In the present invention, the first substrate is placed on the operation surface side of the keyboard, and generally there are displays such as numbers and symbols on the front surface of the operation side, and contact electrodes are located at the corresponding positions on the back surface of the display. It is provided. That is,
The first substrate is deformed and moved by compression and comes into contact with contact electrodes provided at opposing positions on the second substrate,
It performs a switch function in an electric circuit.

Therefore, the substrate material must have a certain degree of surface deflection and restoring force against compression, as well as good chemical resistance and Δ adhesion of printing.

For this purpose, it is preferable to use a flexible film or sheet with a thickness in the range of 0.015 to 0.2 mm, or more specifically in the range of 0.01 to 0.150 mm.
If the thickness is less than 0.015 mm, the strength will be weak, resulting in poor switch performance and life, and if it exceeds 0.2 mm, the flexibility will be poor.

The second substrate may be in the form of a film or a plate, but its thickness is preferably in the range of 0.015 to 2 mm.

If the thickness is less than 0.015 mm, the strength is weak and it is difficult to maintain the shape of the keyboard switch. If the thickness exceeds 2 mm, there is no problem in terms of strength, but the overall thickness of the keyboard switch is unnecessarily thick. This is also because it is disadvantageous from a financial standpoint.

Thus, the first and second substrates may be identical to each other in material, shape, and thickness, or may be different from each other in any or all of these.

Contact electrodes and wiring circuits provided on such an insulating substrate can be formed by conventionally known methods.
For example, pattern formation is performed by etching a copper-clad substrate, or by printing (screen or gravure printing) with a conductive paint (ink) made of conductive fine particles (silver, graphite, carbon black, etc.) and a matrix polymer. obtain. The thickness of the contact electrode and wiring circuit of the present invention is o, oos to 0.0501 m.
A range of is appropriate. That is, the thickness is 0.005m
If the thickness is less than 0.05 mm, reliability will be poor, especially in the case of contact electrodes.On the other hand, the reason for setting the upper limit to 0.050 mm is that there is no need for a thickness exceeding this for performance reasons, and that if it is thick, it will form an insulating spacer. This is because many problems arise in terms of manufacturing and quality when doing so, which is undesirable.

When attempting to assemble an electric circuit through the contact electrodes and wiring circuits on the first and second insulating substrates formed in this way, due to the design, as shown in FIG.
and a contact electrode 2.2 on each of the second substrates 1, 1'.
' and wiring circuits 2a, 2a', and as shown in FIG. The wiring circuit 9b connecting the electrodes may be formed only on one of the substrates, in this case the substrate 9.

In the latter case, the contact electrode portion having the wiring circuit has a shape in which the electric circuit is open.

Therefore, when closing the circuit, the other contact electrode (conductive layer) is brought into contact with the open electrode portion to enable current to flow, thereby closing the electric circuit. That is, in the latter case, one of the substrates does not have a wiring circuit and is composed only of a conductive layer.

Next, on at least one of the first and second substrates having the contact electrodes, a portion having a thickness equal to that of the contact electrodes is placed on an area including a portion excluding the contact electrodes and a narrow portion around the contact electrodes. Equal to or greater than o, oi
A spacer is provided by adhering and forming an insulating elastic film layer selected from a range of 0 to 0,080 mm. It is difficult to make the spacer thinner than the contact electrode when forming it, and the spacer can be applied to a small area around the electrode, so it can provide sufficient performance as a switch despite being a thin film. This thickness is selected because it is the easiest and most accurate thickness to obtain by a method such as screen printing. That is, the thickness is 0.010mm
If it is less than 0.0, it will be difficult to manufacture and have poor reliability.
If it exceeds 80 n+m, it is not preferable because it has an adverse effect on ease of manufacture and improvement in water resistance.

The insulating elastic film thus obtained has excellent workability, water repellency, heat resistance, durability, etc., has adhesive properties to substrate materials and contact electrodes, and is a material that can be cured to become an insulating elastic body. Due to necessity, it is suitable to use a liquid silicone rubber-based adhesive material.

Next, the present invention comprises providing another insulating adhesive layer on the insulating elastic film.

The role of this adhesive layer is not only to fix the first and second substrates together, but also to prevent moisture from entering and maintain airtightness in combination with the elastic film.

Its thickness is 0.010~o, oa.

Selected from the range of mm. If the thickness is less than 0.010 mm, there will be an adverse effect on the reliability for bonding the substrates together and the airtight/waterproof performance, and if the thickness exceeds 0.080 mm, it is unfavorable in terms of ease of manufacture.

Materials that can be used for the adhesive layer include silicone,
Known adhesives such as acrylic and polyether adhesives can be used. Although any of these can be implemented in the present invention, it is particularly important to use a silicone adhesive that exhibits waterproofness and durability superior to those described above in order to manufacture the keyboard switch of the present invention. It was suitable.

The waterproof flat keyboard of the present invention can be obtained by bonding and fixing the first and second substrates thus obtained such that the contact electrodes correspond to each other.

Ru. However, in addition to the method described above, the method for manufacturing the keyboard of the present invention includes, for example, printing or brushing conductive ink on an insulating substrate to provide an electrode portion.
Next, the insulating elastic film and adhesive layer can be manufactured according to the design pattern using printing, brush painting, and other techniques in the same manner as in the case of the conductive ink, so the keyboard of the present invention is extremely advantageous in manufacturing. ,You can say that.

[Effects of the Invention] Compared to the conventional technology, the flat keyboard having the above-mentioned structure has an insulating elastic film formed even in the narrow peripheral area on the contact electrodes, and therefore has extremely excellent waterproof properties. Further, when manufacturing a keyboard, the cylinder is completed simply by bonding the substrates together using an adhesive layer, which has great effects in streamlining, continuous production, and saving labor.

As described above, the flat keyboard of the present invention has excellent waterproof properties and is highly effective in terms of manufacturing, so it can be used in analyzers that handle water and chemicals, and household electrical appliances that are used near water and sinks. , especially useful for applications as keyboard switches where waterproofness is required.

[Examples of the Invention] The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the Examples without departing from the gist of the present invention.

Example 1 The keyboard of Example 1 was manufactured as shown in the process diagram of FIG. That is, conductive urethane resin is used on polyester films 1 and 1' with a thickness of 125 μm shown in FIGS. 1(a) and (b), and a film with a diameter of 10 mm and a thickness of 1
An electric circuit with a contact electrode 2.2' of 5 μm was formed [FIGS. 1(C) and (d)].

Next, 1 m inside from the outer periphery of the contact electrode area in Figure 1 (C).
Additive silicone rubber [Toshiba Silicone Corporation'! An insulating elastic film 3 with a thickness of 60 μm was formed using ATSE33601 [Fig.
e) ]. FIG. 2 shows a cross section of this insulating elastic film layer-formed substrate film along line ff-II.

Next, the insulating elastic seat ll! i! An insulating adhesive layer 4 having a thickness of about 40 μm was formed using a silicone adhesive [ME65 manufactured by Toshiba Silicone Corporation] by stacking the layers [see Fig. 1 ([ )]. ■ of this insulating adhesive layer forming substrate film
A cross section taken along line -■ is shown in FIG.

The insulating adhesive layer-formed substrate film shown in FIG. 1(f) and the electric circuit board film shown in FIG. g) Cross-sectional view] was prepared.

Table 1 shows the characteristics of the keyboard switch thus obtained and the results of the water resistance test.

Example 2 Using the same electric circuit forming substrate film as that used in Example 1 [Fig. An insulating elastic film 3, 3' with a thickness of 30 μm is formed, and an insulating adhesive layer 4.4 with a thickness of about 20 μm is formed with a silicone adhesive.
′ were formed respectively. Both were bonded together in the same manner as in Example 1 to produce a flat keyboard. A cross section of this keyboard is shown in FIG.

The characteristics of the keyboard switch thus obtained are also listed in Table 1. Note that the substrate shown in FIG. 1(e) of Example 1 and the paired substrate of Example 2 [FIG. 1(d)
The same results were obtained when a switch was constructed using a substrate formed in the same manner as in Example 2.

Example 3 As shown in the process diagram of Fig. 5, the thickness of Fig. 5 (a) is 12
A contact electrode 6 having a thickness of 30 μm and a square size of 12×12n+m was formed using a 1-meter urethane resin on a polyester film 5 having a thickness of 5 μm [FIG. 5(b)].

Next, an insulating elastic film 7 [M5 (C)] similar to that in Example 1 was applied on the substrate film including the inner part of the contact electrode 6 with a width of 2 mm and 11 m, and then an insulating adhesive layer 8 [ FIG. 5(d) 1 was formed.

A glass epoxy resin printed wiring board 9 (this is an electrically insulating board having comb-shaped contact electrodes 9a) having a thickness of 1.6IIII and a substrate film on which the insulating adhesive layer 8 is formed are connected to both contact electrodes 6. and 9a face each other, and form a flat keyboard [Fig. 5 (r)
] was created.

The characteristics of the keyboard switch thus obtained are also listed in Table 1.

Comparative Example 1 The same electric circuit forming substrate film as that used in Example 1 [Fig. 1 <c> and (d)] was used, and the frontage part 11 was 11 mm in diameter as shown in No. 6, and the thickness was 240 μm. A flat board as shown in FIG. 7 was prepared using the intermediate spacer film 10 (both sides of which were coated with an acrylic adhesive).

The characteristics of this switch are also listed in Table 1.

Comparative Example 2 The same contact electrode forming substrate film as that used in Example 3 [FIG. 5(b) 1] and a glass epoxy resin printed wiring board [FIG. 5(e)], and further as shown in FIG. Na1
3X 13n+m square opening 13, thickness 188μ
A flat keyboard as shown in FIG. 9 was prepared using the ugly intermediate spacer film 12.

The characteristics of this switch are also listed in Table 1.

Comparative Example 3 Prepare the same substrates as in Figs. 1 (C) and (d) of Practical Example 1, and as shown in Fig. 10, using one of the substrates (C), contact electrode 2 and a concentric circle therewith, Diameter is 12mm
Insulation 9 with a thickness of 150 μm in the area excluding the part consisting of
1 i-type film layer (spacer)! '7 Example 1
Screen printing was performed using the same addition-type silicone rubber TSE3360.

This was heated and cured to form an insulating spacer 14.
On top of this spacer 14, a 20 μm film 15 was further applied by screen printing using the same uncured silicone rubber as above to obtain the substrate shown in FIG. After the substrate in FIG. 10 obtained in this way and the substrate in FIG. We created a flat keyboard shown in . As a result of testing the characteristics and water resistance of this switch, the characteristics before the water resistance test were as follows:
Although the level was the same as in Example 1, after the water resistance test, 76 out of 100 key switch sections were in a conductive state in terms of insulation resistance, suggesting the possibility of water intrusion.

[Brief explanation of drawings]

FIG. 1 is a process diagram for explaining the flat keyboard of Example 1 of the present invention, FIG. 1<a) and (b) are plan views of the film substrate, and FIG. Figure 1 (e) is a plan view of a film substrate on which an electric circuit is formed.
1 is a plan view of a film substrate on which an insulating elastic film layer is formed, FIG. 1 (a) is a plan view of a film substrate on which an insulating adhesive layer is formed, and FIG. FIG. 2 is a schematic cross-sectional view showing a keyboard switch. Figure 2 is a schematic cross-sectional view along line II-U in Figure 1;
3 is a schematic cross-sectional view taken along the line ■--■ in FIG. 1, and FIG. 4 is a schematic cross-sectional view showing a keyboard switch according to a second embodiment of the present invention. FIG. 5 is a process diagram explaining the keyboard switch of Example 3 of the present invention, FIG. 5(a) is a plan view of the film substrate, FIG. 5(1)) is a plan view of the film substrate on which contact electrodes are formed, FIG. 5(C) is a plan view of a film substrate on which an insulating bullet film layer is formed, FIG. 5(d) is a plan view of a film substrate on which an insulating adhesive layer is formed, and FIG. ) is a plan view of a printed wiring board, and FIG. 5 ( ) is a schematic cross-sectional view showing a keyboard switch according to Example 3. FIG. 6 is a plan view of a spacer film according to Comparative Example 1.
FIG. 7 is a schematic cross-sectional view showing a keyboard switch according to Comparative Example 1. FIG. 8 is a plan view of a spacer film according to Comparative Example 2;
FIG. 9 is a schematic cross-sectional view showing a keyboard switch according to Comparative Example 2. FIG. 10 is a plan view of a film substrate on which an insulating elastic skin III and an uncured insulating rubber layer are formed according to Comparative Example 3, and FIG. 11 is a schematic cross-sectional view showing a keyboard switch according to Comparative Example 3. 1.1'... Film substrate, 2.2'... Contact electrode, 3... Insulating elastic film layer, 4... Insulating adhesive layer, 5... Film substrate, 6 ...Contact electrode, 7...Insulating elastic film layer, 8...Insulating adhesive layer, 9...Printed wiring board, 9a...
・Switch part of printed wiring board (comb-shaped electrode), 1
0... Spacer film, 11... Opening,
12... Spacer film, 13... Opening,
14°15... Insulating elastic film layer (cured and uncured silicone rubber). Figure 1 Figure 10

Claims (1)

[Claims] A pair of first and second insulating substrates, with a thickness of 0.005 to 0.050 mm at mutually corresponding positions on both substrates.
A flat keyboard having contact electrodes,
At least one of the insulating substrates is (a) provided on an area including a portion excluding the contact electrode and a narrow portion inside the outer periphery of the contact electrode, and has a thickness equal to or equal to that of the contact electrode; or more, and 0.010 to 0.080m
(b) an insulating adhesive layer provided on the elastic film and having a thickness of 0.010 to 0.080 mm; 1. A waterproof flat keyboard comprising an insulating substrate and another insulating substrate paired with the insulating substrate, which are fixed together via the adhesive layer. 2. The waterproof flat keyboard according to claim 1, wherein the first insulating substrate is a film having a thickness in the range of 0.015 to 0.2 mm. 3. The waterproof flat keyboard according to claim 1, wherein the second insulating substrate is a film or plate having a thickness in the range of 0.015 to 2 mm. 4. The waterproof flat keyboard according to claim 1, wherein the insulating elastic film is formed of adhesive silicone rubber. 5. The waterproof flat keyboard according to claim 1, wherein the insulating adhesive layer is formed of a silicone adhesive.