JPS6145521A - Small-sized electronic device - Google Patents

Abstract

(57) [Summary] 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 small electronic carrier having a key switch.

[Technical background of the invention and its problems]

Conventionally, a key switch for a small electronic device such as a small electronic calculator has generally consisted of a fixed contact, a movable contact that is provided at a distance from and facing the fixed contact, and that comes into contact with the fixed contact when pressed. However, recently, a pressure-sensitive conductive material is provided on the top surface of the key contact corresponding to the fixed contact of the contact type key switch, and the movable contact of the contact type key switch is placed on top of the pressure-sensitive conductive material. Pressure-sensitive key switches equipped with a conductor corresponding to the above are increasingly being used.

This pressure-sensitive key switch utilizes the property of pressure-sensitive conductive material, which exhibits insulating properties when no pressure is applied, and when compressed force is applied, the compressed part becomes conductive. The switch is turned on by compressing a piezoelectric material, and unlike the contact-type key switches mentioned above, this pressure-sensitive key switch does not require a space between the fixed contact and the movable contact. Therefore, if this pressure-sensitive key switch is adopted, the structure of the key switch section of a small electronic device can be simplified.

However, in the case of small electronic devices using conventional pressure-sensitive key switches, a key contact is formed on the top surface of a wiring board on which a predetermined circuit pattern is formed, and a sheet of pressure-sensitive conductive rubber is formed on top of this kill contact. Since the pressure-sensitive key switch is constructed by stacking sheets and providing a conductor facing the key contact on top of the sheets, it is difficult to position the pressure-sensitive conductive rubber sheet on the wiring board when assembling a small electronic device. The pressure-sensitive conductive rubber sheet must be polymerized and fixed, which makes it troublesome to assemble the device.Furthermore, if the pressure-sensitive conductive rubber sheet is made too thin, the pressure-sensitive conductive rubber sheet may have poor sensitivity when attached to the wiring board. Handling the pressure-sensitive conductive rubber sheet becomes extremely troublesome, and may cause wrinkles or wrinkles on the pressure-sensitive conductive rubber sheet.
Since there is a risk of damaging the pressure-sensitive rubber sheet, the pressure-sensitive conductive rubber sheet should be thickened to a certain extent (usually 0.5 to 1
．． 0mm) It is necessary to ensure its strength, which makes it impossible to make the device even thinner (Currently, small electronic switches that use contact type keys have a thickness of 1mm)
There are ultra-thin ones with a thickness of less than
If the thickness is 1.5 m, the thickness of the entire device becomes considerably thick.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a pressure-sensitive key switch that is easy to assemble, and that is easier to assemble than conventional ones. The object of the present invention is to provide a compact electronic separate device that can be made significantly thinner.

[Summary of the invention]

That is, in the present invention, a pressure-sensitive conductive layer is formed by printing on the key contact of the lower case on which a predetermined circuit pattern including the key contact and component connection terminals is formed, and the pressure-sensitive conductive layer is formed on the pressure-sensitive conductive layer. By forming a conductive layer by printing to face the key contact, it is possible to assemble a pressure-sensitive key switch without overlaying the pressure-sensitive conductive rubber sheets 1 to 1 on the key contact as in the past, and the pressure-sensitive conductive By forming the layer by printing, there is no need to ensure strength as with a pressure-sensitive conductive rubber sheet as a separate component, and the thickness can be reduced.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking a small electronic calculator as an example.

1 to 3, 10 is a lower case of a small electronic calculator, 11 is a top sheet for an upper casing forming the upper surface of the small electronic calculator, and the lower case 10
is said to be a flat plate made of synthetic resin. As shown in FIG. 3, on the upper surface of the lower case 10, a large-scale integrated circuit chip (hereinafter referred to as an LSI chip) 20,
Recesses 12, 13, and 14 into which a display body, for example, a liquid crystal display panel 30 and a solar cell 40 are fitted and held, are formed by half etching, and LSI chip connection terminals 22 are formed around the four LSI chip fitting parts 12. .2
2. ... are formed in an array. Also, on one side of the display panel fitting four part 13, a display panel connection terminal 33.3 is provided.
．． 3. ... are arranged in an array, and a pair of battery connection terminals 44a, 44b are formed on the side of the battery fitting recess 14, and the display panel connection terminals 33, 33.・
... and battery connection terminals 44a, 44b are connected to L by wiring so, so, ... formed on the upper surface of the lower case.
SI chip connection terminals 22, 22. ...is connected.

In addition, each of these electronic component connection terminals 22.22. ...
, 33, 33. ..., 44a, 44b, a hot melt type anisotropic conductive adhesive 70, 70 is printed.

The LSI chip 20 is mounted on the L of the lower case 10.
It is fitted into the SI chip fitting recess 12 and held in the lower case 10, and its respective terminals 21, 21, .
* indicates LSI chip connection terminals 22, 22. . . . By stacking it on top and applying heat and pressure, this anisotropic conductive adhesive 70 partially forms LS.
I-chip connection terminal 22.22. It is adhesively connected to... Note that the anisotropically conductive adhesive has conductivity in the film thickness direction only in the portion that is heated and pressed (the portion between the terminals).

In addition, as a part of the cross section of the liquid crystal display panel 30 is shown in FIG. The liquid crystal display panel 30 is held in the lower case 10 by fitting the portion below the upper electrode substrate 31a into the display panel fitting recess 13, and the portion below the upper electrode substrate 31a is held by the lower case 10. Each terminal (not shown) arranged on the lower surface of one side is connected to the display panel connection terminal 3 from above the anisotropic conductive adhesive 70.
3.33. ...By stacking it on top and applying heat and pressure,
Display panel connection terminals 33.33. It is adhesively connected to...

Further, the solar cell 40 is fitted into the battery fitting recess 14 and held in the lower case 10.
A pair of terminals 41a and 41b of 0 are connected to battery connection terminals 44a and 44b from above the anisotropic conductive adhesive 70.
By stacking them on top of each other and applying heat and pressure, they are adhesively connected to the battery connection terminals 44a and 44b using this anisotropically conductive adhesive 70.

On the other hand, in FIG. 3, 60.60. ... are pressure-sensitive key switches for input operation arranged and formed on the upper surface of the lower case 10, and this pressure-sensitive key switch 60 is
As shown in FIG. 1, a key contact 61 formed on the upper surface of the lower case 10, a pressure-sensitive conductive layer 62 printed on the key contact 61, and a pressure-sensitive conductive layer 62 formed on the pressure-sensitive conductive layer 62. Upper conductive layer 6 printed to face key contact 61
3, each key switch 60.60.・・・
・Key contact 61.61. . . are wires 51, 51, . ..., LSI chip connection terminal 22.22. Key signal input terminal group Kl of...
are connected to each other.

Further, the upper surface of the lower case 10 has each of the key contacts 6
1.61. . . . and the fitting recesses 12, 13, 14 for each electronic component (LSI chip 20, liquid crystal display panel 30, solar cell 40), and connection terminals 22 for each electronic component.
゜22, ..., 33.33. ..., 44a,
It is covered with a resist film 15 except for the part 44b,
Pressure-sensitive conductive fi62.62°... is connected to each key contact 61.
61. . . . is formed on the resist film 15 so as to be flush with the resist film 15.

Further, the upper conductive FB 63.63 is arranged perpendicularly to each key contact row so as to form a key matrix with the key contacts 61.61 of each row.
1ffiW! is printed on the resist film 15 so as to cover each of the upper portions of the resist film 1ffiW! I63.63 is L as follows
SI chip connection terminal 22.22. ... is connected to the key signal output terminal group KO.

That is, in FIG. 3, 52.52 is the LSI chip Jlj connection terminal 22.22. This is the wiring for connecting the upper conductive layer led out from the key signal output terminal group KO to one side edge of the lower case 10, and this distribution f152゜52
The resist film 15 is also covered with the resist film 15 except for the terminal portions 52a and 52a. Moreover, 63a and 63a are upper conductive layers 63 printed and formed on the upper surface of the resist film 15.
The upper conductive layer 63.63 is formed by printing the ends of the leads 63a, 63a over the terminal portions 52a, 52a of the upper conductive layer connection arrangement 152, 52. Conductive layer connection wiring 52.
L S 'I chip connection terminal 22.22 through 52
．． ... is connected to the key signal output terminal group KO.

4 and 5 show the pressure-sensitive key switches 60, 60. This shows the method of forming the pressure-sensitive key switches 60, 60.
．． ... is formed as follows.

First, as shown in FIG. 4(a) and FIG. 5(a),
Each pressure-sensitive key switch eo is mounted on the upper surface of the lower case 10.
Key contacts 61.eo, . f31. ... and connection terminals 22, 22, ..., 33 for each electronic component.
33. . . , 44a, 44b (wiring 50°, 51, 52) is formed by screen printing with carbon ink. Note that this wiring pattern may be formed by laminating copper foil or the like over the entire upper surface of the lower case 10 and patterning it by etching.

Next, as shown in FIG. 4(b) and FIG. 5(b),
Key contacts 61, 61.
. . . and recesses 12°13 into which each electronic component (LSI chip 20, liquid crystal display panel 30, solar cell 40) is fitted.
, 14 and connection terminals 22.22. for each electronic component.・・・
・, 33, 33. . . , 44a, 44b portions and the terminal portion 52a of the upper conductive layer connection front 852.52,
A resist film 15 is formed by printing a resist except for 52a.
This resist 11!15 forming the lower case 1
In order to protect each wiring 50, 51, 52 formed on the 0th surface, these wirings 50, 51, 52 and the upper conductive layer 63.
This resist film 15 is used to insulate between the resist film 15 and the resist film 63 and the resist film 15, and it is sufficient if the resist film 15 has a thickness of about 30a.

Next, as shown in FIG. 4(C) and FIG. 5(C), each key contact 61.6 that is not covered with the resist film 15 is
1. Resist film 1 is applied on top of ... by screen printing.
Pressure-sensitive conductive Q62.
G2. ... are printed and formed, and each electronic component connection terminal 22.22. ..., 33.33. ..., 4
Anisotropic conductive adhesive 70.7 is applied to the arrangement portions of 4a and 44b.
Print 0.

Said pressure sensitive 111i! f32.62. ... is an insulating polymer material made by mixing a thermoplastic resin with a rubber material such as silicone rubber or chloroprene rubber, and adding a solvent and a tackifier to the mixture to dissolve it, and conductive particles such as nickel (diameter 10μ). The conductive particles mixed into the insulating polymer material are printed by mixing and dispersing conductive particles in the insulating polymer material. (When conductive particles are mixed into an insulating material, the resistance value of the insulating material decreases rapidly from the point where the percentage of conductive particles mixed in exceeds a certain level, and the insulating material becomes insulating.) (changes from conductivity to conductivity). Therefore, this pressure sensitive conductive layer 62.6
2. ... is insulating in a non-pressurized state, but when a compressive force is applied to it, the density of conductive particles in the compressed part increases, and only this part becomes conductive, releasing the compressive force. The compressed part then recovers and becomes insulating again.

After that, as shown in FIGS. 4(d) and 5(d), carbon ink is printed on the upper surface of the resist film 15 by screen printing to form the pressure-sensitive conductive layer 62 of each key contact row. .62 and its leads 63a, 63a are formed. At this time, lead 63
a, the end of 63a is connected to the upper conductive layer connection wiring 52, 5
The upper conductive layers 63, 63 are printed on the terminal portions 5ga, 52a of the upper conductive layer 52.
52 through LSI chip connection terminals 22.22.・・・
・Connect to key signal output terminal fJKo.

Note that here, the pressure-sensitive conductive layer G2.62. Each electronic component connection terminal 22.22. ..., 33
．． An anisotropically conductive adhesive 70°70 is printed on the array portion of 33°..., 44a, 44b, and this anisotropically conductive adhesive 70°70 is used to form the upper conductive 51 (33, G3). You can print it after doing so.

The upper sheet 11 also includes a display window portion 11 on the layer surface of the transparent resin sheet, which faces the display surface of the liquid crystal display panel 30.
a, and a lighting window portion 11b facing the light-receiving surface of the solar cell 40
The blind printing 1G (see Figure 1) is left behind, and the pressure-sensitive key switches eo, eo,
The key codes 11°17, . . .
This top sheet 11 is stacked on the lower case 10 so as to cover each electronic component 20, 30, 40 and the key switch arrangement section, and around it, the first
As shown in the figure, it is bonded to the lower case 10 with an adhesive 18.

This small electronic meter has a key contact 61°61 on the top.
, ... and each electronic component connection terminal 22.22.・・・
・, 33, 33. ..., 44a, 44b, and each key contact point 61.61° of the lower case 10 formed with a predetermined circuit pattern includes a pressure sensitive conductor 1! Layer 62.62.・
After printing and forming the upper conductive layer 63.63 thereon, each recess 12.1 of the lower case 10 is formed.
3.14 respectively fit and hold the LSI chip 20, liquid crystal display panel 30, and solar cell 40, and connect these electronic components 20, 30, 40 to the electronic component connection terminals 22, 22, 40 of the lower case 10. ..., 33° 33, ..., 44a
, 44b, then attach the top sheet 1 from above.
This small electronic meter is manufactured by gluing the key contacts ei, ei, . . . , which form the pressure-sensitive key switch 60. ,6
2. ... and an upper conductive layer 63, 63 are sequentially printed on the upper surface of the lower case 10 to form a pressure-sensitive key switch e.
o, eo, . . . , it is possible to assemble a small electronic calculator more easily than in the conventional method in which pressure-sensitive conductive rubber sheets are aligned and polymerized.

Further, in this small electronic calculator, the pressure sensitive conductive layer 62
．． 62. Because it is formed by printing, there is no need to make it thick to prevent wrinkles or damage, unlike pressure-sensitive conductive rubber sheets that are handled as one component.
Pressure sensitive conductive layer 62.62. By making ... thinner, it is possible to achieve a significant reduction in thickness.

In the above embodiment, the upper sheet 11 is used as the upper casing means, but the upper casing may be coated with a resin, in which case it covers the display surface of the liquid crystal display panel 30 and the light-receiving surface of the solar cell 40. Parts may be coated with transparent resin and other parts may be coated with opaque resin.

Furthermore, although the solar cell 40 is used as the power source battery in the above embodiment, this power source cell may be a paper-like battery.

Furthermore, in the above embodiment, a pressure-sensitive key switch [30°6
0,... key contacts 61.61. ... are connected to the key signal input terminal of the LSI chip 20, and the upper conductive layer 63.
63 is connected to the key signal output terminal of the LSI chip 20. In this pressure-sensitive key switch 60, as shown in FIG. One contact electrode 61a is connected to the key signal input terminal of the LSI chip 20, and the other contact electrode 61b is connected to the key signal input terminal of the LSI chip 20. , 61b may be electrically connected via the pressure-sensitive conductive layer 62 and an upper conductive layer 63 printed on the pressure-sensitive conductive layer 62. In this case, since it is not necessary to lead out the leads from the upper conductive layer 63, each upper conductive layer 63 is individually coated with an insulating resin as shown in FIG. The reference numeral 65 may be printed and only the portions where electronic components such as LSI chips and liquid crystal display panels are placed may be cased with a top sheet or a resin coating film.

In addition, in the above embodiment, the key contacts 61, 61 and the electronic component connecting terminals 22,22° are provided directly on the upper surface of the lower case 10.
..., 33.33. ..., 44a, 44b are formed, but this lower case 10
may be a groove in which the film substrate on which the circuit pattern is formed is adhered to the case surface.

Note that the present invention can also be applied to small electronic devices having key switches other than small electronic calculators.

〔Effect of the invention〕

According to the present invention, although a pressure-sensitive key switch is used, assembly of a small electronic device is simplified, and the device can be made much thinner than conventional devices.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment of this invention.
Figure 1 is an enlarged sectional view taken along line A-A in Figure 2, Figure 2 is an external view of the small electronic calculator, Figure 3 is an exploded view of the small electronic calculator, and Figures 4 (a) to < 63 is a plan view showing the method of forming a pressure-sensitive key switch on the lower case surface in the order of steps, and FIGS. 5(a) to 5(d) are enlarged cross sections of the key switch portion of FIGS. It is a diagram. FIG. 6 is an enlarged sectional view of a pressure-sensitive key switch section showing another embodiment of the present invention. 10...Lower case, 11...Top sheet, 20.
...LSI chip, 22...LSI chip connection terminal, 30...Liquid crystal display panel, 33...Display panel connection terminal, 40...Solar cell, 44a, 44b
...Battery connection terminal, 50.51゜52...Wiring,
60...Pressure-sensitive key switch 1.61...Key contact, 62...Pressure-sensitive conductive layer, 63...Upper conductive layer. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 IS Figure 6 Figure 6l

Claims (1)

[Claims] a lower case on which a predetermined circuit pattern including key contacts and component connection terminals is formed; a pressure-sensitive conductive layer printed on the key contacts; The device includes a printed conductive layer, electronic components such as an integrated circuit chip and a display body connected to the component connection terminals and held in the lower case, and upper casing means that covers at least an upper surface of the electronic component. A small electronic device.