JPH0531243B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a key input device, in particular, a printed circuit board on which a contact pattern is formed is arranged with a slight gap between the two printed circuit boards by pressing one of the printed circuit boards from the outside. The present invention relates to a key input device that performs key input by touching the contact pattern.

[Prior art] In recent years, electronic desktop calculators (hereinafter referred to as calculators)
Electronic devices such as the above are rapidly becoming smaller and thinner. FIG. 1 shows a perspective view of a conventional calculator.

A keyboard section 2 is provided on the front side of the top surface of the main body 1 of the calculator shown in FIG. 1 for inputting numerical values, operators, and the like. A display section 3 such as an LCD is provided above the keyboard section 2 to display input numerical values, calculation results, and the like.
Further, inside the device main body 1, there is built-in an arithmetic processing unit for performing various arithmetic processes and a battery as a power source (both are not shown).

In such a conventional thin calculator, the overall thickness of the device is reduced by making the pressing stroke of the keys on the keyboard section 2 as small as possible. FIG. 2 shows an example of the structure of such a key input device.

In FIG. 2, the reference numeral 4 denotes an upper frame made of an insulating rigid body such as synthetic resin, and a key film 6 made of an insulating flexible member is fixed to the upper surface of the upper frame 4 by a method such as adhesive. ing. A key symbol 5 is printed on the surface of the key film 6 by silk printing or the like to indicate the function of the key. Flexible printed circuit boards 9 and 11 are stacked on the lower side of the upper frame 4 with spacers 12 in between.
These flexible printed circuit boards 9, 11 and spacer 12 are sandwiched between the upper frame 4 and the lower frame 7 and fixed by screws or the like.

For example, circular openings 13 and 14 are formed in areas of the upper frame 4 and the spacer 12 that correspond to the key symbols 5. A pressing member 15 made of an elastic body or the like is accommodated in the opening 14 of the upper frame 4. On the other hand, on the surfaces of the flexible printed circuit boards 9 and 11 facing each other in the central region of the opening 13 of the spacer 12, first and second contacts 8 are formed by printed wiring patterns formed by a known method such as vapor deposition or etching. 10 are provided respectively.

A cylindrical boss 16 is provided on the lower surface of the center of the pressing member 15 at a position corresponding to the first contact 8 and the second contact 10.
is formed. Therefore, when the area of the key symbol 5 is pressed from above through the key film 6, the boss 16 of the pressing member 15 presses and deforms the upper flexible printed circuit board 9, thereby bringing the first contact 8 and the second contact 10 into contact. Then, the desired key input is performed.

According to the structure of the conventional key input device as described above, the boss 16 of the pressing member 15 directly presses the first contact point 8 of the upper flexible printed circuit board 9 against the second contact point 10 of the lower flexible printed circuit board 11. It's getting old. That is, both contacts 8, 10
Since an external force is directly applied to the contacts 8 and 10, there is a risk that the conductive layers of the contacts 8 and 10 will wear out with repeated use, resulting in poor contact.

[Objective] The present invention has been made in view of the above-mentioned problems.
It is an object of the present invention to provide a key input device that allows reliable key input over a long period of time with short key strokes.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings. However, in the following, the same reference numerals will be given to the same or corresponding members as those in the conventional example, and detailed explanation thereof will be omitted.

FIG. 3 shows a sectional view of the key input device of the present invention. The difference from the conventional example shown in FIG. 2 is that the inside of the lower frame 7 of the key input section is hollowed out to form an opening 19, and a cylindrical boss 20 is formed in the center of the opening 19. and the first contact point 17 and the second contact point of the flexible printed circuit board 9, 11
The contact point 18 is formed in a ring shape. In this case, the boss 20 provided on the lower frame 7
The diameter of the ring is smaller than the inner diameter of the first and second contacts 17 and 18, which are formed in a ring shape. Also, a boss 16 provided at the center of the lower part of the pressing member 15
The diameter of the ring-shaped contacts 17 and 18 is approximately equal to the outer diameter of the ring-shaped contacts 17 and 18.

Next, FIG. 4 shows an exploded perspective view of the above-mentioned key input device. Note that only the structure of the input portion corresponding to one key is shown here, and the illustration of other key portions on the keyboard is omitted.

Starting from the bottom of FIG. 4, a boss 20 is provided in the opening 19 of the lower frame 7, and the height of the boss 20 is slightly lower than the upper surface of the lower frame 7. As a result, as shown in FIG. 3, under normal conditions, the boss 20 and the lower flexible printed circuit board 11 are not in contact with each other.
A flexible printed circuit board 11 and a flexible printed circuit board 9 are arranged on this upper surface of the lower frame 7 with an insulating spacer 12 interposed therebetween. As shown in FIG. 4, the first and second contacts 17 and 18 formed as printed patterns on the printed circuit boards 9 and 11 have a ring-shaped outer shape,
These contacts are connected to their respective input circuits by printed patterns 17a and 18a. Further, an upper frame 4 having an opening 14 is provided on the upper surface thereof.
are stacked and fixed using screws or other methods. A pressing member 15 having a boss 16 is housed in the opening 14, and then a key film 6 on which a key symbol 5 is printed is fixed onto the upper frame 4 by adhesive or the like, thereby forming a key input section.

In the above configuration, the finger 21 is placed on the key symbol 5.
FIG. 5 shows the state in which it is pressed. The key film 6 is bent by the pressing operation, the pressing member 15 is pushed down, and the boss 16 deforms the upper flexible printed circuit board 9. As a result, the first and second contacts 17 and 18 provided on the upper and lower flexible printed circuit boards 9 and 11 come into contact with each other, and when the pressure is continued, the lower flexible printed circuit board 11 and the boss 20 of the frame 7 The lower flexible printed circuit board 11 also abuts the flexible boss 20 in the region of the gap between them. If you keep pressing further, boss 2
0 causes the lower flexible printed circuit board 11 to be pushed up, the contact pressure of the first contact and the second contact 18 increases, the contact resistance rapidly decreases, and a predetermined key input signal is generated.

According to the above embodiment, the first and second contacts 1
No external force is applied directly to the contact areas of 7 and 18, and the load is increased indirectly due to the flexibility of the lower flexible board, significantly reducing the possibility of key input failures due to contact wear as in the past. can be done. In addition, it can be constructed at low cost simply by providing a gap below the contact area, and does not increase the key stroke or the thickness of the device.

In the above embodiment, a configuration was shown in which the flexible printed circuit board having key contacts is deformed by the pressing member 15 provided on the lower surface of the key film 6.
The same effect as described above can also be obtained by pressing a key button that is slidable in the vertical direction and is biased upward.

[Effects] As is clear from the above description, according to the present invention, a pair of printed circuit boards on which contact patterns are formed are arranged facing each other with a space between them, and a pressing force is applied to bring the pair of contact patterns into contact with each other. In a key input device for performing key input, a pair of contact patterns are formed in a ring shape, and a pressing member for pressing one of the contact patterns, and a first contact pattern for transmitting the pressing force of the pressing member to one of the contact patterns. A projection, an opening that allows the printed circuit board to be deformed by the pressing force, and a second projection that supports the center part of the other contact pattern within the opening when pressed, and the first projection is removed. The configuration is such that the boss is formed with a diameter that is approximately the same as the outer diameter of the ring, and the second protrusion is formed with a boss that has an outer diameter smaller than the inner diameter of the ring, thereby reducing contact wear and ensuring a reliable key. To easily and inexpensively provide an excellent key input device that can guarantee input, has a short key stroke, and is thin.

[Brief explanation of the drawing]

Fig. 1 is a top perspective view showing the structure of a conventional electronic desktop calculator, Fig. 2 is a sectional view showing the structure of a conventional key input device, and Fig. 3 and the following figures illustrate an embodiment of the present invention. 3 is a sectional view of the key input device of the present invention, FIG. 4 is an exploded perspective view of the key input device of the present invention, and FIG. 5 is a sectional view of the key input device of the present invention in an operating state. 4...Top frame, 5...Key symbol, 6...
...Key film, 7...Lower frame, 9, 11...
...Flexible printed circuit board, 12... Spacer, 13, 14, 19... Opening, 15... Pressing member, 16, 20... Boss, 17, 18... Contact.

Claims (1)

[Scope of Claims] 1. A key input device in which a pair of printed circuit boards on which contact patterns are formed are placed facing each other with a space between them, and a pressing force is applied to bring the pair of contact patterns into contact to perform key input. The contact pattern is formed into a ring shape, a pressing member for pressing one of the contact patterns, a first protrusion that transmits the pressing force of the pressing member to one of the contact patterns, and a printed circuit board is pressed by the pressing force. an opening that is deformable; and a second protrusion that supports the center part of the other contact pattern within the opening when pressed; A key input device, wherein the second protrusion is formed of a boss having an outer diameter smaller than an inner diameter of the ring.