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(11) | EP 0 186 708 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 158(3) EPC |
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| (54) | FLAT KEYBOARD |
| (57) A flat keyboard which is used as an operating board for numerical control units,
and as an input device for calculators and electronic balances. It is an object of
this invention to easily and accurately position an outer sheet (70) with which the
outer surface of a keyboard assembly (100) is covered. A keyboard assembly (100) consisting
of a printed board (1) on which keys (4) are arranged is attached to the rear surface
of a smooth, flat panel (6) with holes therein. The outer surface of the keyboard
assembly (100) and the outer sides of the holes in the smooth, flat panel (6) are
covered with an outer sheet (70). The positioning means (11,12) which are opposed
to the keyboard assembly (100) are provided on a peripheral portion of the outer sheet
(70). A smooth, flat frame (8) placed on the peripheral portion of the outer sheet
(70) is fastened to the smooth, flat panel (6) by fixing means (9) to hold the peripheral
portion firmly between the smooth, flat panel (6) and smooth, flat frame (8). |
Technical Field
[0001] This invention relates to a flat keyboard and, more particularly, to a flat keyboard used in an operator's panel of a numerical control unit, an input unit of a computer, an input unit of an electronic weigher and the like.
Background Art
[0002] Figs. 4 and 5 illustrate an example of a conventionally used flat keyboard. Fig. 4 is a sectional view taken along line IV-IV of Fig. 5, and Fig. 5 is a plan view. The structure of the conventionally used flat keyboard will now be described based on Figs. 4 and 5. In the Figure, numeral 1 denotes a printed board on which wiring is formed by a printing method. Numeral 2 denotes a reed switch a plurality whereof are arranged on the printed board. Numeral 4 denotes a key a plurality of which oppose and overlie respective ones of the plural reed switches 2. Fixed to the bottom surface of each key is a magnet 3 for turning the reed switch 2 on and off. The key 4 is urged upwardly by a spring or the like, not shown, so that the magnet 3 fixed to the bottom surface ordinarily is spaced away from the reed switch 2. By pressing the key, the magnet 3 is made to approach the reed switch 2. Numeral 5 denotes a guide plate of key 4. The central portion of the guide plate is so formed as to project upwardly and is equipped with a guide hole 51a into which the crown portion of the key is fitted, thus constructing a guide portion 51. The peripheral portion 52 thereof is attached to the printed board 1 via a spacer 10. Numeral 7 denotes a surface sheet covering the surface of the guide plate 5 and keys 4 and fixed to the overall surface of the guide plate 5 as by an adhesive. The above-described printed board 1, read switches 2, keys 4, magnets 3, guide plate 5, spacer 10 and surface sheet 7 construct a keyboard assembly. This keyboard assembly is mounted on a decorative panel 6, which has an opening 6a, from the inner side thereof (the lower side in Fig. 4) and is attached to the back side of the decorative panel 6 with the guide portion 51 being fitted into the opening 6a.
[0003] Since the surface sheet 7 is affixed to the guide plate 5 as by an adhesive, it is difficult to position the surface sheet. In particular, if a large number of keys are provided, affixing the surface sheet in such a manner that the sheet accurately coincides with the keys is a very difficult operation. In addition, there is the possibility that the surface sheet 7 will be damaged. How to readily position the surface sheet and improve positioning accuracy when the sheet is replaced are problems to be solved.
Disclosure of the Invention
[0004] The present invention has been devised to solve the foregoing problems of the above-described conventionally employed flat keyboard and its object is to provide a flat keyboard in which the surface sheet covering the surface of the keyboard assembly can be readily positioned and accurately affixed.
[0005] According to the present invention, there is provided a flat keyboard having a decorative panel equipped with an opening, a keyboard assembly arranged opposite the opening and attached to the back side of the decorative panel, a detachable surface sheet covering the surface of the keyboard assembly and the outer side surface of the decorative panel at the opening, positioning means provided on a peripheral portion of the surface sheet and corresponding to the keyboard assembly, and fixing means for detachably fixing the surface sheet to the decorative panel.
[0006] Since the flat keyboard according to the present invention is constructed as described above and the surface sheet is provided at its peripheral portion with the positioning means located at a position corresponding to the keyboard assembly, the surface sheet can be easily and accurately positioned when affixing the same. In addition, assembly and replacement operations can be greatly facilitated.
[0007] Other objects and features of the present invention will become clear from the description that follows.
Brief Description of the Drawings
[0008] Figs. 1 and 2 illustrate an embodiment of a flat keyboard according to the present invention, in which Fig. 1 is a sectional view along line I-I of Fig. 2 and Fig. 2 is a plan view, Fig. 3 is a sectional view illustrating another embodiment of a flat keyboard according to the present invention, and Figs. 4 and 5 illustrate a conventionally used flat keyboard, in which Fig. 4 is a sectional view taken along line IV-IV of Fig. 5 and Fig. 5 is a plan view.
Best Mode for Carrying Out the Invention
[0010] Figs. 1 and 2 illustrate an embodiment of a flat keyboard according to the present invention, in which Fig. 1 is a sectional view along line I-I of Fig. 2 and Fig. 2 is a plan view. Parts identical with those of the conventional flat keyboard shown in Figs. 4 and 5 are designated by like characters.
[0011] In Figs. 1 and 2, numeral 1 denotes a printed board on which wiring is'formed by printing. Numeral 2 denotes a reed switch arranged on the printed board 1. Numeral 4 denotes a key arranged to oppose and overlie the reed switch 2 and having a magnet 3 fixed to its bottom surface. Numeral 5 denotes a guide plate comprising a guide portion 51 having a guide hole 5la into which the crown portion of the key 4 is fitted, a peripheral mounting portion 52, and a connection portion 53 connecting the peripheral mounting portion 52 and guide portion 51. Numeral 10 denotes a spacer interposed between the guide plate 5 and printed board 1 for securing the two as by an adhesive. A keyboard assembly 100 is constructed by assembling these members and is substantially the same as that shown in Figs. 4 and 5. For this reason, a detailed description thereof will be deleted.
[0012] In the present embodiment, the peripheral portion 52 of the guide plate 5 constituting the keyboard assembly 100 is provided with a plurality of implanted positioning pins 11.
[0013] The keyboard assembly 100 thus constructed is attached to the decorative plate 6 by fitting the guide portion 51 of guide plate 5 into an opening 6a, which is formed in the decorative plate 6, from the inner side (the lower side in Fig. 1), and is positioned by inserting the positioning pins 11 into plural positioning holes 6b provided in the decorative plate 6 at the portion thereof surrounding the opening 6a.
[0014] A surface sheet 70 covering the surface of the keyboard assembly 100 is formed to be larger than the opening 6a formed in decorative panel 6 and the peripheral portion thereof is provided with positioning holes 12 at positions corresponding to the positioning pins. The surface sheet 70 is attached from the outer side (the upper side in Fig. 1) of the decorative plate 6 to which the keyboard assembly 100 is attached and the positioning holes 12 are fitted on the positioning pins, whereby the surface sheet can be easily and accurately mounted at a predetermined, prescribed position. Thus, the surface sheet 70 attached to the surface of keyboard assembly 100 and decorative panel 6 is fixed by the decorative frame 8 arranged on the upper side of the peripheral portion. In other words, the surface sheet 70 is clamped and secured by the decorative panel 6 and the decorative frame 8, which is attached to the decorative panel 6 by screws 9. It should be noted that the degree to which the surface sheet 70 follows up manipulation of the keys 4 can be improved by constructing the surface sheet of an elastic material such as rubber.
[0015] The flat keyboard according to the present embodiment is constructed as set forth above. In mounting the surface sheet 70, the positioning holes 12 provided in the peripheral portion are fitted on the positioning pins 12 implanted in the peripheral portion of the guide plate 5 constituting the keyboard assembly 100, thereby positioning the surface sheet accurately and with facility.
[0016] Fig. 3 illustrates another embodiment of a flat keyboard according to the present invention, in which parts identical with those shown in Figs. 1 and 2 are designated by like reference characters and are not described again. The flat keyboard according to this embodiment includes a plurality of projections 14 provided on the peripheral portion of a surface sheet 71 on the back side thereof. The projections 14 are inserted into the postioning holes 13 provided in the decorative plate 6, whereby the surface sheet 71 can be positioned and attached accurately and with facility. In the present embodiment, the positioning pins lla implanted in the guide plate 5 constituting the keyboard assembly 100 are formed to have a length that will allow the pins to penetrate half way into positioning holes 13 provided in the decorative plate 6.
Industrial Applicability
[0017] A flat keyboard according to the present invention enables the surface sheet covering the surface of the keyboard assembly to be positioned easily and accurately. Accordingly, the flat keyboard is well-suited particularly for use on the operator's panel of a numerical control unit for a machine tool, where the surface sheet is likely to be damaged by scraps from cutting or the like and is therefore frequently replaced. The keyboard can also be used on an input unit of a computer or electronic weigher.
1. A flat keyboard comprising:
a keyboard assembly;
a surface sheet covering a surface of said keyboard assembly; and
positioning means provided on a peripheral portion of said surface sheet and corresponding to said keyboard assembly.
2. A flat keyboard according to claim 1, characterized in that the positioning means
provided on the peripheral portion of said surface sheet is a positioning hole fitted
on a positioning pin implanted in said keyboard assembly.
3. A flat keyboard according to claim 1, characterized in that the positioning means
provided on the peripheral portion of said surface sheet is a projection fitted into
a positioning hole formed in said decorative panel provided at a position corresponding
to said keyboard assembly.