DE2841447A1 - CHARACTERISTIC PLATE OF AN ELECTRIC KEYBOARD FOR DATA ENTRY - Google Patents

Description

284H47

_ 4 -

Applicant: International Business Machines

Corporation, Armonk, N.Y. 10504

ar / ib

Character support plate of an electric keyboard for data entry

This invention relates according to the preamble of the first claim the construction of a character carrier plate for a touch-sensitive, electric keyboard for data and / or command input. Such touch-sensitive, electric keyboards require a switching point to operate no or only a small actuation pressure and / or deflection stroke on the keypad above the switching point, which is located in the character carrier plate.

Such touch-sensitive keyboards, which also only have a relatively low overall height in relation to the well-known mechanical keyboards with key tappets, levers or key buttons are also easier, cheaper to manufacture and faster to use. These touch sensitive keyboards are versatile, for example in data processing devices, in entertainment technology devices or in control systems, etc.

The present invention aims at the construction of a new character support plate for touch sensitive keyboards further simplification and cheaper production of these keyboards, especially in mass production. aside from that the recognizability of the individual keys or associated key groups is improved.

The well-known electromechanical keyboards which are currently in use in large numbers have one

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Number of key buttons that appear individually when pressed are depressible. Except for these keyboards, the key buttons of which have a relatively large deflection when they are hit and require a relatively large pressing force, there has been another type of known electric for several years Keyboards, which are hereinafter referred to as "touch-sensitive keyboards". With these touch-sensitive Keyboards do not have individual key buttons that are separated from each other. Instead are with these Keyboards in a character support plate preferably plan a number corresponding to the keyboard switching points or slightly raised keypads. These keypads are arranged in the common character carrier plate in such a way that that they are located above the switching point to be actuated of a planar switching mechanism, on its top the character carrier plate rests.

A touch-sensitive keyboard that contains, for example, a membrane contact switch mechanism, usually has a layered one Construction. The lower plate-shaped layers contain the multi-layer membrane contact switching mechanism. On this one there is an actuating plate that can be deflected at the switching points and a character carrier plate is arranged on this, which can be easily recognized in the keypads is labeled with the symbols that are assigned to the switching points below with the switchgear. These keypads are elastically deflectable by a very small stroke when the key is pressed and they require their Actuation for this purpose only a very small actuation force.

There are different types of known touch-sensitive keyboards, the switching mechanisms of which are based on completely different ones Principles are based. Touch-sensitive keyboards, which contain the membrane contact switchgear, which has already been briefly mentioned.

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Holders are described, for example, in U.S. Patents 3,308,253, 3,668,337 and 4,017,697. Other kinds of switching mechanisms in touch-sensitive keyboards are based on a change in the capacitive coupling or a Change in the capacitance or conductivity of semiconductors. Reference is made to UK patents 1,435,265 and 1,457,572 in this regard. A touch sensitive one Keyboard using the piezoelectric effect has been published in the IBM Technical Disclosure Bulletin Vol. 20., No. 1, June 1977, pages 315,316.

Depending on the functional principle of a switching mechanism in a touch-sensitive keyboard, for example, whether this switchgear contains a membrane contact system, or the capacitive coupling of capacitor layers changes - is also the keystroke or the actuation of a keypad different in the character carrier plate in order to close the switching point arranged below. Some switching points require only a very small deflection stroke and a small pressure or actuation force for their actuation. With derailleurs, which contain a membrane contact or microswitch, a deflection of about 0.5 mm is sufficient to close a switching point. With other touch-sensitive keyboards, which contain switching mechanisms on a coupling system based on the so-called keystroke no actuation force or no deflection is required. at such touch-sensitive keyboards can be activated by a light touch of the keypad in the character carrier plate, the switching point of which is to be actuated. Some character carrier plates are also designed in such a way that that touches the associated keypad in the character carrier plate with a pen to operate a switching point can be.

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Character carrier plates with keypads for touch-sensitive keyboards are available in various designs. One well-known character carrier plate, which contains key fields of different surface shapes combined in groups, is designed so that the key fields apart from the colored characters of the assigned switching points also have a remaining background area of a different color have and thereby form a contrast to the color of the symbol for the switching point. These keypads can also use graphic group or function symbols included, which in turn are executed in a different color. This known character support plate has as follows briefly describes a multilayer structure and requires a number of fabrication steps to produce it; consequently theirs are due to the great effort Costs relatively high. Touch-sensitive keyboards, which are equipped with such complex character carrier plates are only used in devices where the relatively high costs are justified. These relatively expensive character carrier plates are z. B. used in bank or cash register terminals, where the overall appearance of the Key support plate or the graphic design of the key fields, the recognizability of the characters and symbols improved, compared to cheaper key carrier plates, to possibly to prevent serious operating errors. Such a known, complex character carrier plate has as follows briefly describes a structure which consists of five layers:

Layer 1 serves as the top or front layer and they consists of a 0.025 mm thick and transparent film made of polyethylene terephthalate.

Layer 2 is also transparent and consists of a 0.12 mm thick polyvinyl chloride acetate film.

Layer 3 is also transparent and consists of a 0.12 mm thick polyvinyl chloride film.

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This third layer of film has the screen printing process

I generated character patterns for the differently labeled,

Keypads on a character carrier plate. With character carrier ι plates or their keypads, which different j jRusted characters and different colored background image areas | included, for example in eight different colors from j

i, eight different j

Color printing screens and eight individual screen printing operations be j compels. j

Layer 4 is also transparent and, like layer 2, consists of a 0.12 mm thick polyvinyl chloride acetate •Foil.

The layer 5 - if this is required - is 0.025 mm thick and it consists, for example, of a red polyethylene iTerephathaltat foil.

During the successive process steps for the production of the differently colored screen printing patterns, opaque or shimmering layers of color are generated in the corresponding keypads for the characters, course instructions or other graphic symbols assigned to the switching points. It should be noted that only contrasts, for example black or white, can be produced by screen printing, or explained differently; A plate surface can either contain a layer of paint or none. Certain surface areas in the key fields of the character carrier plate, which serve as a colored background surface, are formed, for example, by the red film layer 5, which is not provided with a screen-printed pattern. This transparent red film layer 5 is expediently used ₇ when certain surface areas in the character carrier plate or the key fields are to be illuminated from below by individually switchable display light sources.

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In the known character support plate for touch-sensitive keyboards briefly described above, there is also the Disadvantage of the complex and therefore expensive production by means of screen printing, another disadvantage that is added to the To further increase manufacturing costs. Keyboards are required for the same device in countries with different languages, whose character carrier plate contain characters and instructions in the keypads that are adapted to the national language are. Or the same keyboard is to be used for another device that has a different label on the key fields conditionally in the character carrier plate. In these last two operating cases, too, the more complex, expensive screen printing process used to produce the character carrier plates.

It is the object of the invention to provide a better construction of a character support plate with keypads for touch-sensitive ones To create keyboards that can be produced more easily and cheaply with less effort and without screen printing processes is. This new character carrier plate is to have a different lettering of its key fields in each case on simpler ones Way to be adaptable to the respective requirements.

This problem is solved by the features specified in the characterizing part of the first claim.

Appropriate developments and refinements of the invention Character carrier plates with keypads for touch-sensitive keyboards are identified in the subclaims.

In exemplary embodiments of the present invention, which are explained in more detail in the description part the known character support plates for touch-sensitive keyboards produced by the screen printing process

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-ΙΟΙ j new character carrier plates according to the invention exchanged, at | where in the keypad the colored switch point designation, colored course instructions, or other graphic signs or symbols from a developed photographic color plan! are displayed movie, the emulsion on a ^transparent: is th film carrier itself. The new character Substrate: can also be in surface regions outside the keypads: additional guidance short information or other graphic signs, and symbols, which in _developed: are included diagrams Color film. All of the aforementioned various characters, instructions and symbols can be produced in various colors with the exception of white in a known photographic process in a simple manner by an exposure of the desired pattern on the color film and a subsequent development process. The development process of the exposed color film can take place automatically according to known processes.

The use of a developed ink film in the character carrier plate on which the various characters, brief instructions and symbols are shown in different colors a much simpler manufacturing process and is therefore considerably cheaper than the currently used one Method in which the characters, brief instructions and symbols can be produced using the screen printing process. In the screen printing process, different patterns of printing screens are required and besides the screen printing can only be done in several separate process steps for different colors to be printed, whereby the relatively high manufacturing costs arise.

The character carrier plate according to the invention has the following advantageous difference compared to the known embodiment on, if at the character carrier plate, or in their keypads the background of a surface or a sign should be colored and illuminated, is used in this case with the

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known character support plate jwähnte the ER already as layer 5 \, · for example, red, transparent film needs. In contrast, in the case of the character carrier plate according to the invention; No additional color film is required, a corresponding layer of color in the developed color film is sufficient, which also glows in color when exposed to light from below. In the case of the color film provided for use in the character carrier plate according to the invention, the emulsion of which is on a transparent carrier, a black image area can be produced photographically, but not a white image area, because a white color creates transparency in the film. However, if white characters, white graphic symbols or white background surfaces are desired in the keypads of the character carrier plate, these can also be produced in white color by adding the transparent, non-colored areas in the color film that correspond to the characters or symbols be deposited with a white layer of paint. In comparison with the well-known character carrier plates, which by means of | Screen printing processes were produced and in which only a few! ge different colors were used, consists in the; Character carrier plate according to the invention for the designer through the use of a color film a greater freedom and possibility in the color design and the graphic representation of characters, symbols and instructions. The character carrier plates with characters arranged in the keypads and adapted to the different languages of the countries can now be produced much more cheaply by using a color film in the character carrier plate than the known character carrier plates produced by screen printing.

Below are some embodiments of the invention Character carrier plate for touch-sensitive keyboards based on drawings, FIGS. 1 to 3 in more detail described. Of the drawing figures represent:

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Fig. 1 in a schematic, exploded illustration, the first embodiment of a Touch-sensitive keyboard with a 'membrane contact switching mechanism, which is an inventive Character carrier plate is assigned.

Fig. 2 also schmematisehen in a, [image drawn apart a second execution, 'for example a touch-sensitive keyboard ,; with a capacitive switching mechanism, one | Character carrier plate according to the invention is assigned I. ί

3 shows the schematic top view of a character carrier plate according to the invention, around the arrangement and design of the various key fields to show some of which are grouped together are.

With reference to FIG. 1, the following is the first application example a character carrier plate according to the invention explained in a touch-sensitive keyboard, which has a membrane contact switching mechanism contains. This keyboard contains a base plate made of aluminum and provided with an edge Mounting plate 1, the cavity of which to accommodate the membrane contact switching mechanism and the character carrier plate is used. At the edge of the mounting plate 1 is an elastic, rectangular Sealing sleeve 3 is provided. In the case of the mounting plate 1, the inner sides of the edge are not shown Provided slots into which the plate-shaped layers that make up the keyboard can be pushed. For alignment of these plate-shaped layers 8, 11, 13, 15, 17 on top of one another and in the correct position to fix them these plate-shaped layers 8, 11, 13, 15, 17 with holes provided, through which bolts 2 can be inserted. The recording

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Plate 1 contains a number of holes 4 in its base plate, which are in the same grid dimension as the switching points of the membrane contact schaltx «7erkes 8, 11, 13, 15 or like the keypads 18 are arranged in the character carrier plate 17. The protruding on a carrier plate 5 into the holes 4 of the base plate 1 attached light-emitting diodes 6, which are used to illuminate the key fields located at a small distance above 18 in the character carrier plate 17 are used. To fix this keyboard in a device by means of screws its mounting plate 1 is provided with lateral fastening tabs 7. The lighting plate 5 as a carrier light-emitting diodes 6 is connected to a plug-in contact base via its connection strip tied together.

On the perforated bottom part of the receiving plate 1, the lower contact plate 8 is the lowest layer of the membrane contact switching mechanism arranged. This lower contact plate 8 consists of an insulating material, the synthetic resin and glass threads contains. The contact plate 8 is provided with holes in the area of the switching points in the same grid dimension as the receiving plate 1. These holes 9 are used to transmit the light generated by the light emitting diodes 6 to the keypads 18 in FIG the character carrier plate 17. On the top of the lower contact plate 8 are in the grid of the switching points or the keypad 18 has a number of gold-plated conductor tracks (which, however, are not shown in FIG. 1), which extend in columns in the vertical direction and are part of a contact switching matrix. At least one end of such a vertical conductor track leads to a contact terminal strip 10 of the lower one protruding over the edge Contact plate 8. On this contact plate 8 there is a known manner which is also provided with holes 12 at the switching points Spacer plate 11, the thickness of which determines the contact spacing the open switching points of a membrane switch determined. This relatively thin spacer plate 11 consists of

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Polyethylene terephthalate. On top of the spacer plate 11 rests on the upper contact plate 13, its layer material is a tough membrane. On the bottom ; this upper membrane contact plate 13 adhere - (not in the Fig. 1 shown) - gold-plated conductor tracks, which extend in the horizontal direction and which with a con

clock connection strip 14 are connected to the edge of the upper contact plate 13. The vertical conductor tracks on the lower contact plate 8 and the horizontal conductor tracks on the upper contact plate 13 cross at the switching points or in the center of the holes 12 in the spacer plate 11 and they form a preferably rectangular switching matrix, '. wherein the opposing conductor track locations form the j switching contacts of the membrane switching mechanism. |

The actuating plate 15 rests on the top of the upper contact plate 13, which is a deflectable membrane. 'which also consists of a resistant material. , This actuating plate 15 is with each switching point

izwei narrow, punched-out elongated holes 16 provided between ! which have a narrow bar that serves as an actuating element for the switching point below.

On this actuating plate 15 lies as the top layer or The front layer has the multilayered character carrier plate 17, which has the keys assigned to the switching points in the switchgear contains feider 18, which are precisely aligned with the underlying switching points. More detailed information about the character carrier plate 17 will be explained later. The multi-layered, touch-sensitive one formed in this way Keyboard is held together by screws 19, which are provided Holes in a connecting plate 20, a washer 21, the character carrier plate 17, the actuating plate 15, the upper contact membrane 13, the spacer plate 11 and penetrate the lower contact plate 8 and the threaded

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holes 2 are screwed into the base plate of the mounting plate 1.

To operate a switching point, ie to close the open contact point, a finger tip or a pen is used to apply slight pressure to the surface of the keypad 18 arranged above the switching point. practices, as long as the switching point should be closed. As a result of the action of pressure, the layers of the keypad 18 and the central web 16 in the actuating plate 15 and the contact membrane 13 underneath are deflected downward. As a result, the upper contact conductor arches through the hole 12 in the spacer plate 11 until it rests on the lower conductor path. Establishes contact connection. _;

In this first embodiment, the multilayered character carrier plate 17 consists of three superimposed plate-shaped, flexible film layers, which for example! are connected to each other by an adhesive process and a; Form unit. The top or front layer 1, which is touched by the finger of the person being touched, is one 0.025 mm thick, plate-shaped, transparent film, which is made of Polyethylene terephthalate is made. This material is very resistant to wear and tear and is also glare-free.

The second plate-shaped layer in the character carrier plate 17 is a photographic color film with the emulsion on the underside of a flexible and transparent carrier plate adheres to the different colored characters, brief instructions and other graphic symbols. The transparent carrier plate of the color film consists of a material that based on an ester or an acetate. Such a color film is available as sheet film from film manufacturers or commercially available.

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The third lower plate-shaped layer in the character carrier plate 17 is a preferably white, 0.12 now thick, flexible one , Film, which consists of polyvinyl chloride and is opaque. This white foil serves as the background for the color film - Layer 2 - characters shown, which, as already mentioned, as a transparent pattern on the film carrier exist if the desired characters in the keypad 18 are to have a white color. By depositing These transparent character patterns with a white layer of paint in the color film become the characters when viewed from above the operator is more visible because there is a stronger contrast to the surroundings in the keypad 18. The lower one - or the third white film layer contains holes in the area of the switching points so that the light can be drawn in from the underneath the bottom plate arranged light-emitting diodes 6 lightens the keypad.

Instead of the white film layer described briefly above as a background covering for the characters, it is also possible to use 'A transparent, plate-shaped film made of polyvinyl chloride can be used, the surface of which is either completely or only in the ! The area of the drawing pattern is coated with white paint, which is applied to the film by means of screen printing, for example can be. If one or more key fields 18 in the area or under a symbol have a strong red background should have, is as a supplement to the third transparent, colorless foil plate - which only in some areas has a white color print - to arrange a fourth transparent, red foil plate. The example may consist of polyethylene terephthalate. This fourth film covering can be about 0.025 mm thick and it is in his Material mass colored red.

To form a compact character carrier plate 17, which, according to the above explanations in its structure

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consists of three or four layers of film, the superimposed, plate-shaped layers connected to one another by an adhesive process.

To create patterns of characters, symbols and instructions, which are different in shape and color, with the area of the keypad 18 a template must be made by hand on the color plan film, which contains the desired colors and patterns. ! All color films for the required number of character carrier plates 17 are made with this pattern on the template by means of photographic processes exposed, developed and fixed. Are character plates required for keyboards, which If you want to have characters and brief instructions in other languages, it is advisable to first use a transparent film to label these desired characters and cure instructions and then stick this labeled film onto the template. The color film can then be exposed again be done with this modified template. :

A second application example of a character according to the invention4 support plate for a touch-sensitive keyboard, which contains a switching mechanism based on a capacitive coupling principle is shown in FIG. The character carrier plate 25 also contains a number of two-dimensional, preferably rectangular, key fields 26, which with Individual characters, graphical symbols not shown, or short texts 27 are labeled. This carrier plate 27 is similar in structure to the character carrier plate 17 already described in the first embodiment and they contains just like this a photographic color sheet film. In the character fields 26, the characters 27 and short instructions should appear in white. Because this Characters 27 are present on the color film as a transparent pattern, the last or lowermost layer 28 of the multi-layer Zexch support plate

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form the white background, as with the first one

ι embodiment was explained. This white on its upper surface lower layer 28 is disposed on a printed circuitry 'card 29, which rectangular on its displayed to the layer 28 × surface having the metallic surfaces; Form capacitor coatings 30, of which one coating 30 is arranged congruently below a keypad 26. Each pad 30 is tractive to a pair of capacitive elements. ordered, which are not shown and which are on the lower; side of the circuit board 29 are located. These capacitive elements are individually connected to the connection contacts 31 on the plug-in side of the circuit card 31 by conductor tracks. In this capacitive keyboard, the character support plate 25, the white dielectric layer 28 and the circuit board 29 form a unit. These three superimposed plates 25, 28 and 29 are connected to one another, for example by gluing, to form a stable plug-in plate, which at the bottom; . Has a strip-shaped projection which contains the connection contacts 31. This circuit card, which is formed from several layers of covering, contains, in addition to the character carrier plate 125, components of the capacitive switching mechanism to which the dielectric plate 28 and the circuit card 29 belong. The white dielectric plate 28 fulfills a function in the zexch support plate 25 as well as in the capacitive switching mechanism. The plug-in circuit card, which forms a unit and consists of the three plates 25, 29 and 31, can be plugged into the contact strip 32 which is equipped with contact springs and which is arranged in the lower region of a second circuit card 33. This circuit card 33 is provided on the insertion side with printed conductor tracks 34 and it is equipped on the opposite surface side with electrical components that generate the electrical switching signals when a keypad 26 in the character carrier plate 25 is actuated when this is touched by a finger. The electronic circuits 34, 35 of the circuit board 33

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form from the capacitive changes that occur in the! | Touching a keypad 26 shown switching pulses, which keypads are assigned \. .

Alternatively, such a character carrier plate can have the following

Have structure:!

! i

The first layer serves as protection against wear and glare and it rests on the front or operating side of the keyboard. It consists preferably of a plate-shaped, transparent 0.025 mm thick polyethylene terephthalate ■ film.

The second layer is formed by the developed color planar film, the emulsion of which is located on the underside of the transparent film carrier. This film layer contains the characters, symbols and brief information of the keypad in different colors. '·

The third layer is a 0.12 mm thick sheet of trans-i parent polyvinyl chloride. If the color that is in the second! Layer contained, transparent pattern of these characters, j

Symbols or short instructions should be white, this is the one Cover the transparent third layer with white paint in the required areas, possibly using screen printing. In In the third layer, the white paint is not required in the areas where the light from the indicator lamps comes from below or of the light-emitting diodes to brighten or illuminate the keypad, or also at the points where the film layer 2 is black in color.

The fourth layer can be a transparent 0.12mm thick, be plate-shaped film made of polyvinyl chloride acetate.

The fifth and bottom layer can consist of a 0.025 mm thick sheet-like film that is red in color consist of polyethylene terephthalate. This red layer can be used optionally and is only required when a red background is required for the keypad, which is still illuminated by indicator lamps.

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The five superimposed layers are connected to form a unit, for example by means of an adhesive process, so that they form a stable character support plate.

For keyboards that do not require a drawing board with multi-colored keypads to be used, the second layer can consist of a Scharζ white film instead of a color film, which is cheaper. Possibly The fifth red film layer can also be omitted if colored ones are used to illuminate the background of the key fields Light sources are used as indicator lamps, for example light emitting diodes. A white background of the Keypads or the various characters is covered with a white paint or one in the mass v / white colored film.

3 shows the top view of a character carrier plate! For a touch-sensitive keyboard, which for example used in equipment for banks. This character carrier plate 17 has a length of about 380 mm and a width of about 200 mm. This elevation of the character support plate 17 j shows the arrangement of keypads, which various j have surface shapes and are summarized in groups 40, 41, 43 are. These different keypads are not

colored like in reality, but only as line drawings shown in black and white. The surface of the character carrier plate 17 is outside the surface areas the keypads are black «In the keypads, the characters have a white background on.

In the case of the eight keypads 40, the background is blue and the characters are white. In the group's keypads the background is green and the characters are white. The two key field groups 40, 41 have in common that

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each keypad in its upper left corner has a transparent, circular, red point 42 on v / eist, which is surrounded by a black ring. The keypad group 43 contains 10 circular keypads, which are labeled with the numeric digits 0 to 9. These digits are 0 through 9 also shown in white, but the area around these keypads is red.

The rectangular key fields 44 to 47 arranged one below the other in a column on the right side of the character carrier plate 17 are also designed in color. In the keypad 44 the writing is white and the surroundings are red. That _; Keypad 45, however, is completely white and the key; Field 46 shows yellow writing and a black surrounding field. In the keypad 47, the writing is white again and the surrounding area is green. _:

Fig. 3 illustrates that a character support plate according to the invention for touch-sensitive keyboards can be designed very versatile in terms of the surface shape ι of the individual key fields and in the color design of the various characters, symbols and short texts. The designer can choose the color contrasts very freely in order to obtain good legibility of the labeling characters and to get an assignment of the key fields to groups.

Another character carrier plate in the embodiment according to the invention, which is not shown, for example, may contain certain characters or symbols in the keypads, which light up remotely when one of these specific buttons is to be pressed.

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Claims (1)

284H47 -Χ- PATENT CLAIMS IJ character carrier plate with delimited keypads, the each contain the characters of a touch-sensitive, electric keyboard assigned to a switching point, in the case of the actuation of a preferably arranged in a two-dimensional switching mechanism under the keypad Switching point no or only a small actuation pressure j and / or deflection stroke of the keypad is required and j in which the symbol carrier plate rests on the top of the switchgear, characterized in that the character carrier plate (17, 25) has one with the desired character pattern (27) of the key fields (18, 26, 40 to 47) exposed and using known photographic developing and fixing processes contains treated photographic sheet film, which in each key field (18, 26, 40 to 47) the respective, the switching point assigned, represents characters (27) and its surrounding area clearly visible in high contrast. 2. character carrier plate according to claim 1, characterized in that that the photographic sheet film is a color film, the emulsion of which on a transparent, thin Carrier layer adheres. 3. character carrier plate according to one of claims 1 or 2, characterized in that at least in a partial area of the touch-sensitive keyboard in the key fields (18, 26, 40 to 47) the characters (27), digits or characterizing the key or switching positions Symbols have a white hue, in that they Sign (27) on the sheet film by complete detachment of the photoemulsion in the carrier layer transparent Form character patterns and that at least in these , 809 81 5/07 5 9 ÜK 977 016 A white background layer (28) is arranged on the underside of the sheet film. Sign carrier plate according to claim 3, characterized in that that the white background layer (28) for lightening the characters has holes that allow the transfer of Allow light from a display illumination source (5, 6) to the keypad (18). 5. character carrier plate according to claim 3, characterized in that that the background layer consists of a thin, colorless plate (28), which only in certain the Character (27) assigned surface areas is printed with white color. 6. character carrier plate according to one of claims 1 to 5, characterized in that it is multilayered and In addition to the sheet film, it has a lower colored, transparent plate layer that is strong in the selected Color is illuminated by light transmitted to it from a display illumination source (5, 6). 7. character carrier plate according to one of claims 1 to 6, characterized in that it has a transparent, thin and plate-shaped surface on its operating top Protective layer is covered, which prevents glare and the material is resistant to Abrasion and wear and tear is. 8. character carrier plate according to one of claims 1 to 7, characterized in that the individual switching points assigned key fields (40 to 47) for better differentiation between different surface shapes, small text instructions (27) or graphical symbols in different colors. ^{ÜK 977} ° ¹⁶ 9098 15/0759 284H47 9. character carrier plate according to one of claims 1 to 8, characterized in that their various made of plastic materials existing, plate-shaped layers stacked on top of one another and aligned with one another, by Gluing or other mechanical means are connected together and a replaceable unit of the keyboard form. 10. character carrier plate for a keyboard with membrane switches according to claim 9, characterized in that as lowest layer an elastic actuating layer (15) is provided, which is congruent with the keypads (18) has two elongated holes (16) separated from one another by a deflectable central web that on the actuating plate (15) has a perforated, elastic film layer that forms the white background, that the photographic film rests on this film layer forming the white character background and that the top of which is covered with a transparent film. (Fig. 1) 11. Character carrier plate for a capacitive keyboard according to one of claims 1 to 9, characterized in that the one arranged below the photographic film layer (25) Background plate (28) at least in the areas where the transparent character pattern (27) of the film (25) are opposite, a white color that this background plate (28) made of dielectric material exists and rests with its underside on a circuit card (29), which is congruent with each of the keypads (26) contains a capacitive surface covering (30) and that the film plate (25) the background plate (28) and the circuit board (29) are a compact structural unit that can be plugged into a contact base (32) form. (Fig. 2) ^{ÜK 977} ° ¹⁶ 9098 15/0759