CA2049150A1 - Flat piezoelectric keyboard - Google Patents
Flat piezoelectric keyboardInfo
- Publication number
- CA2049150A1 CA2049150A1 CA002049150A CA2049150A CA2049150A1 CA 2049150 A1 CA2049150 A1 CA 2049150A1 CA 002049150 A CA002049150 A CA 002049150A CA 2049150 A CA2049150 A CA 2049150A CA 2049150 A1 CA2049150 A1 CA 2049150A1
- Authority
- CA
- Canada
- Prior art keywords
- laminate
- cover
- base
- keyboard according
- flat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000011888 foil Substances 0.000 claims description 17
- 239000010410 layer Substances 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 8
- 239000012790 adhesive layer Substances 0.000 claims description 6
- 238000005452 bending Methods 0.000 claims description 5
- 239000004020 conductor Substances 0.000 claims description 3
- 239000000853 adhesive Substances 0.000 description 6
- 230000001070 adhesive effect Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 125000006850 spacer group Chemical group 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 239000000543 intermediate Substances 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- 229920005372 Plexiglas® Polymers 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- -1 resin Chemical class 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/96—Touch switches
- H03K17/964—Piezoelectric touch switches
- H03K17/9643—Piezoelectric touch switches using a plurality of detectors, e.g. keyboard
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H2239/00—Miscellaneous
- H01H2239/038—Anti-vandalism
Landscapes
- Push-Button Switches (AREA)
- Micro-Organisms Or Cultivation Processes Thereof (AREA)
- Medicines Containing Plant Substances (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Input From Keyboards Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The flat keyboard is provided with a base laminate and with a cover laminate which are connected to each other. At the key locations, blister-like chambers are provided between the laminates. Each chamber contains a piezoelectric element.
Upon mechanical stress, but almost without travel, the element generates an electric signal. The flat keyboard can be manu-factured economically and has a reduced thickness. The keyboard is immune to humidity and mechanical fatigue.
The flat keyboard is provided with a base laminate and with a cover laminate which are connected to each other. At the key locations, blister-like chambers are provided between the laminates. Each chamber contains a piezoelectric element.
Upon mechanical stress, but almost without travel, the element generates an electric signal. The flat keyboard can be manu-factured economically and has a reduced thickness. The keyboard is immune to humidity and mechanical fatigue.
Description
2 0 '~
(45 309 c) FLAT PI~ZOELECTRIC KEYBOARD
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention is directed to a flat key-board comprising a base laminate or foil, respectively, a cover laminate or foil, respectively, and piezoelectric elements arranged between said laminates or foils, respectively, and defining key locations of said keyboard, which piezoelectric elements generate an electric signal upon mechanical bending of -said elements almost without travel.
2. DESCRIPTION OF THE PRIOR ART
Such a keyboard is known e.g. from the European Patent No. 210 386 (corresponding to U.S. Patent No.
4 857 887). In this keyboard a rigid~spacer laminate is pro-vided between the base laminate and the cover laminate. The : , spacer laminate is provided with recesses for receiving the piezoelectric elements and has a thickness that corresponds to the~thickness of the elements. This rigid spacer serves for posit~ioning the piezoelectric elements, for separating the conducting ætrips provided on the base and cover laminate, and for reducing cross talk between adjacent keys.
: ~ : :: : :
~: :
2 2 ~ 3 ~
Such a spacer laminate leads to additional working operations during manufacturing of the keyboard. Further, three laminates and adhesive layers are necessary.
Piezoelectric keyboards are further known from U.S.
Patent No. 4,458,173 and No. 4,618,797 and from French Patent Application No. 2 576 726.
SUNMARY OF THE INVENTION
It is therefore a general object of the invention to provide a keyboard of the aforementioned type that does not exhibit these disadvantages. Now, in order to implement this and still further objects of the invention, which will become more readily apparent as the description proceeds, the keyboard is manifested by the features that the base and the cover laminate are directly connected to each other and are forming blister-like chambers between each other, each of said chambers containing one of said piezoelectric elements.
By these features, the spacer laminate can be eliminated without adversely affecting the function of the keyboard. The keyboard can be manufactured with less working operations and with less thickness.
::
: ' ~ : -, ~ ' . ' , ' :, , :
-2 $ ~ 't ~
BRIEF DESCRIPTION_OF_THE DRAWINGS
The invention will be better understood and objectsother than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:
Pigure 1 is a sectional vîew of a first embodiment of the flat keyboard;
Figure 2 is a sectional view of a keyboard according to Fig. 1 with an additional support plate;
Figure 3 is a schematic representation of a first way to produce a keyboard according to the invention;
Figure 4 is a sectional view of another embodiment of the flat keyboard with an additional support plate;
: Figure 5 is a sectional view of a third embodiment of the~keyboard with additional support plate;
Figure 6 i8 a schematic representation of an arrangement of the conducting strips;
Figure 7 is a sectional view of a keyboard :according to the first embodiment with an additional rigid : front panel;
m ~ Figure 8~is yet another embodiment of the keyboard with a bulged out cover and base:laminate;
Figure 9 is an:embodiment of the flat keyboard, :wherein the cover laminate is provided wlth recesses for the ;: ~
' ' ' ' , : ' .
,:
.. : .
' 4 2 ~
piezoelectric elements;
Figure 10 is a second schematic representation of the production of a keyboard according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The general construction of the flat keyboard will be explained first, with reference to Fig. 1. The use of the terms cover laminate and base laminate in the following description does not exclude that the keyboard can be used -depending on the application - in inverted position, i.e. with the base laminate forming the key area. Figure 1 shows a sec-tional view of two ad~acent keys 1, 2 of the keyboard. The keyboard i8 provided with a base laminate or base foil 3, respectively, and a cover laminate or cover foil 4, respec- -tively. These laminates enclose the piezoelectric elements 5 between them at each key 1, 2. The piezoelectric elements are platelet shaped ceramic or~crystal elements. When stressed méahanicaily, a voltage is generated between the upper and the lower surface o~ the platelet, which voltage can be picked off and can be detected as;key actuation signal by an interface circuit, as well known. Each piezoelectric element 5 is mounted on a~disc-like metal or~ceramic support 7, which support lends mechanical stability to the element and serves at the same time as the~lower contact surface for the element.
The piezoelectric elements are each provided with a `
:
:' ' ' ' ~ . " " . . . '' ' contact layer 10 of conducting material on their upper sur-faces. The lower contact surface 7 and the contact layer 10 each are in contact with conducting strips arranged on the inner surfaces of the laminates or foils, respectively, as will be described in detail below.
Either the cover laminate 4 or the base laminate 3 or both laminates can be bulged out at each key l, 2, so that chambers 6 between cover laminate and base laminate are formed, each for receiving a piezoelectric element. The dimensions of these chamberæ conform essentially to the piezoelectric element and its support 7 contained within the chamber. In the embodi-ment of Fig. l, only the cover laminate 4 is provided with the bulged out zones, so that the base laminate 3 is flat.
The base laminate 3 and the cover laminate 4 are attached to each other between chambers 6, e.g. by means of an adhesive layer 8 or by laminating or by lamination coating. The chambers 6 are therefore blisters between the two foils 3, 4 attached to each other, the blisters containing the piezo-electric elemQnts 5, 7. The actuation of the keys is neverthe-le~s possible since the actuation occurs almost without tra~el as will be described below.
Now, with reference to Fig. 2, the function of the keyboard will be described in detail. The flat keyboard as shown in Fig. 1 has been arranged on a support plate 9 by means of a transfer adhesive 19 which has openings 14 at the key locations. The transfer adhesive (e.g. the type no. 468 of the r~ ~
3M Company) may have a thickness of approximately only 1/10 millimeter. The openings 14 make sure that the piezoelectric elements S are bendingly stressed when the key is actuated. The elements stressed in the bending mode but almost without detectable travel generate a voltage signal that is used as the key actuation signal. In Figure 2, the actuation force K on the cover laminate 4 of key 2 is represented by an arrow. Since the cover laminate abuts on the base laminate 4 in the intermediate area between the keys and is attached to the base laminate, the actuation force K will be completely absorbed by this inter-mediate area, even if the cover laminate is a rather stiff material. Accordingly, no crosstalk occurs between adjacent keys 1, 2, even if these keys are located close together.
Since almost no travel occurs during actuation of the keys, the stress on the cover laminate 4 is minimal.
As mentioned before, the cover laminate 4 may be made of relatively stiff material. In such a case, the bulges 11 are permanently embossed in the cover laminate or foil 4, respectively. If a relatively elastic laminate is used, the bulges will form by elastic deformation of the laminate, as shown in the examples o~ Fig. 4 and Fig. 8. In both cases, a rounded, edgeless shape of the bulges 11 will reduce the mechanical stress in this area.
Figure 4 shows an embodiment of the invention where the element 5 and the metal support 7 have a convex shape. The metal support 7 abuts on the laminate 3 only with its periphery - . ~ '' '; ' ' .
. .
. . . ~
, .
~ ~ ~ 9 ~
and can be stressed to bend elastically in its center. Accord-ingly, the piezoelectric element S is stressed in the bending mode and generates a voltage signal. The signal is generated even if there is almost no travel and, therefore, essentially without a detectable depression of the bulge 11 of the cover foil 4. The base laminate 3 is supported by a support plate 9 as has been described before, with the exception that no openings 14 in a transfer adhesive layer are necessary with this embodiment. It is therefore possible to make the base laminate 3 itself in the form of a rigid support plate.
The same holds true for the embodiment of Figure 5.
In this embodiment the bending stress of the pie20electric element 5 on the support 7 is caused by a knob 13 on the cover laminate 4 and by a circular rest 12 on the base laminate 3.
To pick off the voltage generated across each piezoelectric element 5 upon actuation of the keys, the contact surfaces 7, 10 of the elements are connected by conducting strips with an interface circuit. The conducting strips are ~arranged on the inner surfaces of the base laminate and the cover laminate, as already mentioned. The conducting strips can be formed, e.g. by a printing process, as is well known.
Figure 6 shovs such an arrangement of conducting strips in the boundary plane of the base and the cover :
laminate. The conducting strips shown as black, filled out strips 15 are arranged on the cover laminate and the conducting strips shown as double line 16, forming a common contact, are ': '' . ' :' ::
' . ', ' ' .' ' , 2 ~
arranged on the base layer. As can be seen, the conducting strips 15 on the cover laminate intersect the conducting strips 16 on the base laminate only at the keys, so that no short circuit occurs, although all conducting strips are arranged in the same plane.
The upper and lower contact surfaces 10 and 7, respectively, of the piezoelectric elements are contacted at the intersections.
If an insulating adhesive layer 8 is used between laminates 3, 4, or if insulated strips 16 are used, an arrangement of conducting strips is possible which intersect in the boundary plane. The cover foil or the base foil can be a metal foil in this case and can perform as common ground con-tact 16 for all of the piezoelectric elements. In this case, the metal foil has to be provided with an insulating layer except at the key locations to avoid a short circuit with the ~conducting strips 15. The insulating layer may serve as adhesive 8 between foils 3, 4 at the same time.
The cover laminate and the~base laminate may be plastic foils ~or metal foils). The base laminate may have a thickness of approximately 0.4 milllmeters and the cover laminate of approximately 0.1 millimet~rs.
Figure 3 represents schematicalIy a first method for joinlng laminates 3, 4 together to form a flat keyboard.
This method is suitable for relatively rigid, platelike arrangements of limited size. First, the piezoelectric elements - - - - .-- .
., - .: , .
- - " . -- : . . - .
', ' '. : . . -:
, ~
2 ~ t~
5, already mounted on their supports 7, are arranged on the base laminate. To this end, areas 17 on the base laminate are left free of adhesive 8, if such adhesive is used. Afterwards, the cover laminate 4 is pressed against the base laminate 3 by means of a tool 18 (only represented schematically) which is provided with recesses 19 corresponding to the bulges 11.
The tool 18 may be heatable so that the cover laminate 4 and the base laminate 3 are laminated together by pressure and heat.
The cover laminate may have been provided before-hand with embossed bulges 11, or the bulges may be produced only during the joining of cover and base laminates. If an elastic cover laminate 4 is used, this element will elastically stretch over the piezoelectric element (see e.g. Fig. 4). In this way a small force acts permanently on the element which insures good electrical contact of the element.
If the production process shown in Figure 3 is carried out ln an atmosphere of inert gas, the blisters remain filled with this gas, preventing oxidation of the contact surfaces over a long time, insuring the faultless operation of the keys.
Figure 10 represents schematically another produc-tion process for producing flat keyboards continuously. The base laminate and the cover laminate, which have been provided with conductor strips by a printing process beforehand, are joined together continuously~between two rollers 22, 23.
2 ~
Beforehand, an adhesive 8 has been applied to the base laminate except at the areas 17. The piezoelectric elements 5 mounted on their supports 7 are placed at these areas before joining the laminates. The rollers 22, 23 are provided with corresponding recesses 24, avoiding that a high pressure is exerted on the elements 5 and that the elements 5 are damaged. Instead of glueing the laminates together, the laminates may be heat sealed.
By the described process a flat keyboard in the form of a band is produced. Single keyboards may be cut from the band. As can be seen in Figure 8, bulges 11 can be provided on the base laminate as well as on the cover laminate. The bulges 11 on the base laminate extend into the openings 14 of the transfer adhesive layer 19.
The cover laminate may constitute directly the top surface of the keyboard, especially if rather thick cover laminates 4 are used.
If the keyboard has to have an essentially flat top surface or an especially resistant top surface, a rigid front panel 20 is mounted atop of the laminate 4, as shown in Figure 7. The~front panel may be a metal panel or a plexiglass panel o 5 millimeter thickness, which is provided with recesses 21 at the keys 1, 2 receiving the bulges 11. The panel has thus a reduced thickness of approximately 2 millimeters at the key locations, providing weaker areas of the panel for transmitting the key actuation force to the construction below.
, , ~,. . , ., . . :
, 2 ~
The front panel abuts with the weakened zones on the bulges 11 and with the nonweakened zones on the cover laminate areas between the k~ys. In this way, cross talk between the keys is prevented in this embodiment as well. The front panel embodiment secures the keyboard against damage, especially against vandalism, but provides a keyboard with only a small increase of total thickness. Instead of the panel 20, a cover layer produced by using a sealing compound, e.g. resin, may be used. In this way, the locally weakened zones above each key are produced automatically when the compound is provided on the cover laminate.
The front panel may conætitute the cover laminate 4 at the same time as shown in Figure 9. Recesses 25 in the bot-tom surface of this front panel 4 are forming the chambers 6.
The flat keyboard as described is suitable for a multitude of uses, especially where keyboards are subject to high mechanical stresses and humidity. The sensitivity of the travelless keys can be adjusted by selecting the thickness of the cover laminates or front panels, respectively, and by the interface circuit.
While there are shown and described present pre-ferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims.
(45 309 c) FLAT PI~ZOELECTRIC KEYBOARD
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention is directed to a flat key-board comprising a base laminate or foil, respectively, a cover laminate or foil, respectively, and piezoelectric elements arranged between said laminates or foils, respectively, and defining key locations of said keyboard, which piezoelectric elements generate an electric signal upon mechanical bending of -said elements almost without travel.
2. DESCRIPTION OF THE PRIOR ART
Such a keyboard is known e.g. from the European Patent No. 210 386 (corresponding to U.S. Patent No.
4 857 887). In this keyboard a rigid~spacer laminate is pro-vided between the base laminate and the cover laminate. The : , spacer laminate is provided with recesses for receiving the piezoelectric elements and has a thickness that corresponds to the~thickness of the elements. This rigid spacer serves for posit~ioning the piezoelectric elements, for separating the conducting ætrips provided on the base and cover laminate, and for reducing cross talk between adjacent keys.
: ~ : :: : :
~: :
2 2 ~ 3 ~
Such a spacer laminate leads to additional working operations during manufacturing of the keyboard. Further, three laminates and adhesive layers are necessary.
Piezoelectric keyboards are further known from U.S.
Patent No. 4,458,173 and No. 4,618,797 and from French Patent Application No. 2 576 726.
SUNMARY OF THE INVENTION
It is therefore a general object of the invention to provide a keyboard of the aforementioned type that does not exhibit these disadvantages. Now, in order to implement this and still further objects of the invention, which will become more readily apparent as the description proceeds, the keyboard is manifested by the features that the base and the cover laminate are directly connected to each other and are forming blister-like chambers between each other, each of said chambers containing one of said piezoelectric elements.
By these features, the spacer laminate can be eliminated without adversely affecting the function of the keyboard. The keyboard can be manufactured with less working operations and with less thickness.
::
: ' ~ : -, ~ ' . ' , ' :, , :
-2 $ ~ 't ~
BRIEF DESCRIPTION_OF_THE DRAWINGS
The invention will be better understood and objectsother than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:
Pigure 1 is a sectional vîew of a first embodiment of the flat keyboard;
Figure 2 is a sectional view of a keyboard according to Fig. 1 with an additional support plate;
Figure 3 is a schematic representation of a first way to produce a keyboard according to the invention;
Figure 4 is a sectional view of another embodiment of the flat keyboard with an additional support plate;
: Figure 5 is a sectional view of a third embodiment of the~keyboard with additional support plate;
Figure 6 i8 a schematic representation of an arrangement of the conducting strips;
Figure 7 is a sectional view of a keyboard :according to the first embodiment with an additional rigid : front panel;
m ~ Figure 8~is yet another embodiment of the keyboard with a bulged out cover and base:laminate;
Figure 9 is an:embodiment of the flat keyboard, :wherein the cover laminate is provided wlth recesses for the ;: ~
' ' ' ' , : ' .
,:
.. : .
' 4 2 ~
piezoelectric elements;
Figure 10 is a second schematic representation of the production of a keyboard according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The general construction of the flat keyboard will be explained first, with reference to Fig. 1. The use of the terms cover laminate and base laminate in the following description does not exclude that the keyboard can be used -depending on the application - in inverted position, i.e. with the base laminate forming the key area. Figure 1 shows a sec-tional view of two ad~acent keys 1, 2 of the keyboard. The keyboard i8 provided with a base laminate or base foil 3, respectively, and a cover laminate or cover foil 4, respec- -tively. These laminates enclose the piezoelectric elements 5 between them at each key 1, 2. The piezoelectric elements are platelet shaped ceramic or~crystal elements. When stressed méahanicaily, a voltage is generated between the upper and the lower surface o~ the platelet, which voltage can be picked off and can be detected as;key actuation signal by an interface circuit, as well known. Each piezoelectric element 5 is mounted on a~disc-like metal or~ceramic support 7, which support lends mechanical stability to the element and serves at the same time as the~lower contact surface for the element.
The piezoelectric elements are each provided with a `
:
:' ' ' ' ~ . " " . . . '' ' contact layer 10 of conducting material on their upper sur-faces. The lower contact surface 7 and the contact layer 10 each are in contact with conducting strips arranged on the inner surfaces of the laminates or foils, respectively, as will be described in detail below.
Either the cover laminate 4 or the base laminate 3 or both laminates can be bulged out at each key l, 2, so that chambers 6 between cover laminate and base laminate are formed, each for receiving a piezoelectric element. The dimensions of these chamberæ conform essentially to the piezoelectric element and its support 7 contained within the chamber. In the embodi-ment of Fig. l, only the cover laminate 4 is provided with the bulged out zones, so that the base laminate 3 is flat.
The base laminate 3 and the cover laminate 4 are attached to each other between chambers 6, e.g. by means of an adhesive layer 8 or by laminating or by lamination coating. The chambers 6 are therefore blisters between the two foils 3, 4 attached to each other, the blisters containing the piezo-electric elemQnts 5, 7. The actuation of the keys is neverthe-le~s possible since the actuation occurs almost without tra~el as will be described below.
Now, with reference to Fig. 2, the function of the keyboard will be described in detail. The flat keyboard as shown in Fig. 1 has been arranged on a support plate 9 by means of a transfer adhesive 19 which has openings 14 at the key locations. The transfer adhesive (e.g. the type no. 468 of the r~ ~
3M Company) may have a thickness of approximately only 1/10 millimeter. The openings 14 make sure that the piezoelectric elements S are bendingly stressed when the key is actuated. The elements stressed in the bending mode but almost without detectable travel generate a voltage signal that is used as the key actuation signal. In Figure 2, the actuation force K on the cover laminate 4 of key 2 is represented by an arrow. Since the cover laminate abuts on the base laminate 4 in the intermediate area between the keys and is attached to the base laminate, the actuation force K will be completely absorbed by this inter-mediate area, even if the cover laminate is a rather stiff material. Accordingly, no crosstalk occurs between adjacent keys 1, 2, even if these keys are located close together.
Since almost no travel occurs during actuation of the keys, the stress on the cover laminate 4 is minimal.
As mentioned before, the cover laminate 4 may be made of relatively stiff material. In such a case, the bulges 11 are permanently embossed in the cover laminate or foil 4, respectively. If a relatively elastic laminate is used, the bulges will form by elastic deformation of the laminate, as shown in the examples o~ Fig. 4 and Fig. 8. In both cases, a rounded, edgeless shape of the bulges 11 will reduce the mechanical stress in this area.
Figure 4 shows an embodiment of the invention where the element 5 and the metal support 7 have a convex shape. The metal support 7 abuts on the laminate 3 only with its periphery - . ~ '' '; ' ' .
. .
. . . ~
, .
~ ~ ~ 9 ~
and can be stressed to bend elastically in its center. Accord-ingly, the piezoelectric element S is stressed in the bending mode and generates a voltage signal. The signal is generated even if there is almost no travel and, therefore, essentially without a detectable depression of the bulge 11 of the cover foil 4. The base laminate 3 is supported by a support plate 9 as has been described before, with the exception that no openings 14 in a transfer adhesive layer are necessary with this embodiment. It is therefore possible to make the base laminate 3 itself in the form of a rigid support plate.
The same holds true for the embodiment of Figure 5.
In this embodiment the bending stress of the pie20electric element 5 on the support 7 is caused by a knob 13 on the cover laminate 4 and by a circular rest 12 on the base laminate 3.
To pick off the voltage generated across each piezoelectric element 5 upon actuation of the keys, the contact surfaces 7, 10 of the elements are connected by conducting strips with an interface circuit. The conducting strips are ~arranged on the inner surfaces of the base laminate and the cover laminate, as already mentioned. The conducting strips can be formed, e.g. by a printing process, as is well known.
Figure 6 shovs such an arrangement of conducting strips in the boundary plane of the base and the cover :
laminate. The conducting strips shown as black, filled out strips 15 are arranged on the cover laminate and the conducting strips shown as double line 16, forming a common contact, are ': '' . ' :' ::
' . ', ' ' .' ' , 2 ~
arranged on the base layer. As can be seen, the conducting strips 15 on the cover laminate intersect the conducting strips 16 on the base laminate only at the keys, so that no short circuit occurs, although all conducting strips are arranged in the same plane.
The upper and lower contact surfaces 10 and 7, respectively, of the piezoelectric elements are contacted at the intersections.
If an insulating adhesive layer 8 is used between laminates 3, 4, or if insulated strips 16 are used, an arrangement of conducting strips is possible which intersect in the boundary plane. The cover foil or the base foil can be a metal foil in this case and can perform as common ground con-tact 16 for all of the piezoelectric elements. In this case, the metal foil has to be provided with an insulating layer except at the key locations to avoid a short circuit with the ~conducting strips 15. The insulating layer may serve as adhesive 8 between foils 3, 4 at the same time.
The cover laminate and the~base laminate may be plastic foils ~or metal foils). The base laminate may have a thickness of approximately 0.4 milllmeters and the cover laminate of approximately 0.1 millimet~rs.
Figure 3 represents schematicalIy a first method for joinlng laminates 3, 4 together to form a flat keyboard.
This method is suitable for relatively rigid, platelike arrangements of limited size. First, the piezoelectric elements - - - - .-- .
., - .: , .
- - " . -- : . . - .
', ' '. : . . -:
, ~
2 ~ t~
5, already mounted on their supports 7, are arranged on the base laminate. To this end, areas 17 on the base laminate are left free of adhesive 8, if such adhesive is used. Afterwards, the cover laminate 4 is pressed against the base laminate 3 by means of a tool 18 (only represented schematically) which is provided with recesses 19 corresponding to the bulges 11.
The tool 18 may be heatable so that the cover laminate 4 and the base laminate 3 are laminated together by pressure and heat.
The cover laminate may have been provided before-hand with embossed bulges 11, or the bulges may be produced only during the joining of cover and base laminates. If an elastic cover laminate 4 is used, this element will elastically stretch over the piezoelectric element (see e.g. Fig. 4). In this way a small force acts permanently on the element which insures good electrical contact of the element.
If the production process shown in Figure 3 is carried out ln an atmosphere of inert gas, the blisters remain filled with this gas, preventing oxidation of the contact surfaces over a long time, insuring the faultless operation of the keys.
Figure 10 represents schematically another produc-tion process for producing flat keyboards continuously. The base laminate and the cover laminate, which have been provided with conductor strips by a printing process beforehand, are joined together continuously~between two rollers 22, 23.
2 ~
Beforehand, an adhesive 8 has been applied to the base laminate except at the areas 17. The piezoelectric elements 5 mounted on their supports 7 are placed at these areas before joining the laminates. The rollers 22, 23 are provided with corresponding recesses 24, avoiding that a high pressure is exerted on the elements 5 and that the elements 5 are damaged. Instead of glueing the laminates together, the laminates may be heat sealed.
By the described process a flat keyboard in the form of a band is produced. Single keyboards may be cut from the band. As can be seen in Figure 8, bulges 11 can be provided on the base laminate as well as on the cover laminate. The bulges 11 on the base laminate extend into the openings 14 of the transfer adhesive layer 19.
The cover laminate may constitute directly the top surface of the keyboard, especially if rather thick cover laminates 4 are used.
If the keyboard has to have an essentially flat top surface or an especially resistant top surface, a rigid front panel 20 is mounted atop of the laminate 4, as shown in Figure 7. The~front panel may be a metal panel or a plexiglass panel o 5 millimeter thickness, which is provided with recesses 21 at the keys 1, 2 receiving the bulges 11. The panel has thus a reduced thickness of approximately 2 millimeters at the key locations, providing weaker areas of the panel for transmitting the key actuation force to the construction below.
, , ~,. . , ., . . :
, 2 ~
The front panel abuts with the weakened zones on the bulges 11 and with the nonweakened zones on the cover laminate areas between the k~ys. In this way, cross talk between the keys is prevented in this embodiment as well. The front panel embodiment secures the keyboard against damage, especially against vandalism, but provides a keyboard with only a small increase of total thickness. Instead of the panel 20, a cover layer produced by using a sealing compound, e.g. resin, may be used. In this way, the locally weakened zones above each key are produced automatically when the compound is provided on the cover laminate.
The front panel may conætitute the cover laminate 4 at the same time as shown in Figure 9. Recesses 25 in the bot-tom surface of this front panel 4 are forming the chambers 6.
The flat keyboard as described is suitable for a multitude of uses, especially where keyboards are subject to high mechanical stresses and humidity. The sensitivity of the travelless keys can be adjusted by selecting the thickness of the cover laminates or front panels, respectively, and by the interface circuit.
While there are shown and described present pre-ferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims.
Claims (11)
1. Flat keyboard comprising a base laminate, a cover laminate and piezoelectric elements arranged between said laminates, and defining keys of said keyboard, which piezo-electric elements generate an electric signal upon mechanical actuation and almost without travel, wherein said base and said cover laminate are connected to each other and are forming blister-like chambers between each other, each of said chambers receiving one of said piezoelectric elements.
2. Flat keyboard according to claim 1, wherein said base laminate and said cover laminate are attached to each other at least around said chambers.
3. Flat keyboard according to claim 1 or 2, wherein said base laminate or said cover laminate, respectively, is provided with bulges forming said chambers for said piezo-electric elements.
4. Flat keyboard according to claim 3, wherein said cover laminate is embossed to form said bulges.
5. Flat keyboard according to one of the preceding claims, wherein each of said piezoelectric elements is con-nected with one of its surfaces to a rigid support plate, said element being in electrical contact with said plate, said plate serving as contact plate for said piezoelectric element, and wherein the other surface of said piezoelectric element is provided with a contact layer of conducting material.
6. Flat keyboard according to one of the preceding claims, wherein each of said elements is supported in such a way that it is subjected to bending stress upon actuation thereof.
7. Flat keyboard according to claim 6, wherein said base laminate is attached to a support plate by means of a transfer adhesive layer, and wherein said layer is provided with openings at the locations of said elements for providing a support for the edges of said piezoelectric elements.
8. Flat keyboard according to claims 1 to 6, wherein said cover laminate or said base laminate is a metal foil, and wherein said laminates are attached to each other by an insulating layer.
9. Flat keyboard according to one of the preceding claims, wherein said cover laminate is an essentially rigid plate.
10. Flat keyboard according to one of claims 1 to 8, wherein an essentially rigid front panel is provided which comprises a flat front face and a back comprising recesses for receiving said bulges of said cover laminate, such that essen-tially the whole back surface of said front panel is supported by said cover laminate.
11. Flat keyboard according to one of the preceding claims, wherein said base laminate is a support plate, or wherein said base laminate rests on an additional support plate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH2806/90A CH680890A5 (en) | 1990-08-29 | 1990-08-29 | |
| CH2806/90-6 | 1990-08-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2049150A1 true CA2049150A1 (en) | 1992-03-01 |
Family
ID=4242012
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002049150A Abandoned CA2049150A1 (en) | 1990-08-29 | 1991-08-15 | Flat piezoelectric keyboard |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP0472888B1 (en) |
| JP (1) | JPH04256008A (en) |
| AT (1) | ATE167767T1 (en) |
| BR (1) | BR9103703A (en) |
| CA (1) | CA2049150A1 (en) |
| CH (1) | CH680890A5 (en) |
| DE (1) | DE59109015D1 (en) |
| FI (1) | FI106229B (en) |
| NO (1) | NO305498B1 (en) |
| RU (1) | RU2025771C1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5391410A (en) * | 1992-06-03 | 1995-02-21 | Showa Shell Sekiku K.K. | Plasma CVD of amorphous silicon thin film |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT399406B (en) * | 1992-06-03 | 1995-05-26 | Frequentis Nachrichtentechnik Gmbh | TOUCH-SENSITIVE INPUT UNIT |
| ATE142375T1 (en) * | 1992-06-24 | 1996-09-15 | Algra Holding Ag | METHOD FOR PRODUCING A PIEZOELECTRIC PRESSURE-SENSITIVE BUTTON OR KEYPAD AND PRODUCT OBTAINED BY THIS METHOD |
| FI91686C (en) * | 1992-08-31 | 1994-07-25 | Kai Markus Martesuo | Instrument |
| FI97577C (en) * | 1994-12-28 | 1997-01-10 | Screentec Ky | Keyboard |
| RU2221268C2 (en) * | 1996-06-10 | 2004-01-10 | Теджик Коммьюникейшнз, Инк. | Reduced-keyboard ambiguity eliminating system |
| US5953541A (en) * | 1997-01-24 | 1999-09-14 | Tegic Communications, Inc. | Disambiguating system for disambiguating ambiguous input sequences by displaying objects associated with the generated input sequences in the order of decreasing frequency of use |
| DE19712137A1 (en) * | 1997-03-22 | 1998-09-24 | Aeg Hausgeraete Gmbh | Control of operation of household equipment |
| RU2134443C1 (en) * | 1997-07-08 | 1999-08-10 | Государственное научно-производственное предприятие "Рубин" | Film keyboard |
| KR20020040763A (en) * | 1999-08-06 | 2002-05-30 | 옴니보드, 인코포레이티드 | Multi-purpose keyboard |
| RU2267152C2 (en) * | 2004-04-14 | 2005-12-27 | Хабузов Василий Арсеньевич | Keyboard |
| ITTV20040158A1 (en) * | 2004-12-30 | 2005-03-30 | Nice Spa | REMOTE CONTROLLER. |
| SI22353A (en) * | 2006-08-28 | 2008-02-29 | Gorenje Gospodinjski Aparati, D.D. | Touch-sensitive oil and switch based thereof |
| DE102008011860B4 (en) | 2008-02-29 | 2013-01-10 | Seuffer Gmbh & Co.Kg | Flat keyboard with piezoelectric detection |
| JP2010146482A (en) * | 2008-12-22 | 2010-07-01 | Sony Corp | Electronic apparatus and method for manufacturing same |
| EP3282587A1 (en) | 2016-08-12 | 2018-02-14 | Big Kaiser Präzisionswerkzeuge Ag | Electronic appliance with a button device |
| FI20205029A1 (en) | 2020-01-14 | 2021-07-15 | Aito Bv | Haptic power device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4458173A (en) * | 1983-02-04 | 1984-07-03 | Essex-Tec Corporation | Pressure sensitive electric signal generator |
| US4618797A (en) * | 1984-12-24 | 1986-10-21 | Cline David J | Environmentally sealed piezoelectric sensing assembly for electrical switch |
| FR2576726B1 (en) * | 1985-01-29 | 1993-02-19 | Samokine Georges | TOUCH CONTROL KEYBOARD |
| CH667763A5 (en) * | 1985-07-23 | 1988-10-31 | Schenk & Co | FILM KEYBOARD. |
-
1990
- 1990-08-29 CH CH2806/90A patent/CH680890A5/de not_active IP Right Cessation
-
1991
- 1991-07-19 AT AT91112081T patent/ATE167767T1/en not_active IP Right Cessation
- 1991-07-19 EP EP91112081A patent/EP0472888B1/en not_active Expired - Lifetime
- 1991-07-19 DE DE59109015T patent/DE59109015D1/en not_active Expired - Fee Related
- 1991-08-13 NO NO913156A patent/NO305498B1/en not_active IP Right Cessation
- 1991-08-15 CA CA002049150A patent/CA2049150A1/en not_active Abandoned
- 1991-08-23 FI FI914006A patent/FI106229B/en active
- 1991-08-28 RU SU915001430A patent/RU2025771C1/en active
- 1991-08-28 BR BR919103703A patent/BR9103703A/en not_active IP Right Cessation
- 1991-08-28 JP JP3217289A patent/JPH04256008A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5391410A (en) * | 1992-06-03 | 1995-02-21 | Showa Shell Sekiku K.K. | Plasma CVD of amorphous silicon thin film |
Also Published As
| Publication number | Publication date |
|---|---|
| NO913156D0 (en) | 1991-08-13 |
| NO305498B1 (en) | 1999-06-07 |
| FI106229B (en) | 2000-12-15 |
| JPH04256008A (en) | 1992-09-10 |
| CH680890A5 (en) | 1992-11-30 |
| DE59109015D1 (en) | 1998-07-30 |
| NO913156L (en) | 1992-03-02 |
| FI914006L (en) | 1992-03-01 |
| RU2025771C1 (en) | 1994-12-30 |
| FI914006A0 (en) | 1991-08-23 |
| EP0472888B1 (en) | 1998-06-24 |
| EP0472888A1 (en) | 1992-03-04 |
| BR9103703A (en) | 1992-05-19 |
| ATE167767T1 (en) | 1998-07-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |