CA1154810A - Tactile element and keyboard including the tactile element - Google Patents

Tactile element and keyboard including the tactile element

Info

Publication number
CA1154810A
CA1154810A CA000368873A CA368873A CA1154810A CA 1154810 A CA1154810 A CA 1154810A CA 000368873 A CA000368873 A CA 000368873A CA 368873 A CA368873 A CA 368873A CA 1154810 A CA1154810 A CA 1154810A
Authority
CA
Canada
Prior art keywords
dome
sheet
inches
range
radius
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.)
Expired
Application number
CA000368873A
Other languages
French (fr)
Inventor
William P. Harper
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rogers Corp
Original Assignee
Rogers Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Rogers Corp filed Critical Rogers Corp
Application granted granted Critical
Publication of CA1154810A publication Critical patent/CA1154810A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/70Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
    • H01H13/78Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard characterised by the contacts or the contact sites
    • H01H13/785Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard characterised by the contacts or the contact sites characterised by the material of the contacts, e.g. conductive polymers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J5/00Devices or arrangements for controlling character selection
    • B41J5/08Character or syllable selected by means of keys or keyboards of the typewriter type
    • B41J5/12Construction of key buttons
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/02Input arrangements using manually operated switches, e.g. using keyboards or dials
    • G06F3/0202Constructional details or processes of manufacture of the input device
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/70Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
    • H01H13/702Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/70Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
    • H01H13/702Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
    • H01H13/703Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches characterised by spacers between contact carrying layers
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2201/00Contacts
    • H01H2201/022Material
    • H01H2201/026Material non precious
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2209/00Layers
    • H01H2209/024Properties of the substrate
    • H01H2209/026Properties of the substrate metallic
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2211/00Spacers
    • H01H2211/004Adhesive
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2215/00Tactile feedback
    • H01H2215/004Collapsible dome or bubble
    • H01H2215/008Part of substrate or membrane
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2215/00Tactile feedback
    • H01H2215/004Collapsible dome or bubble
    • H01H2215/02Reversed domes
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2217/00Facilitation of operation; Human engineering
    • H01H2217/01Off centre actuation
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2221/00Actuators
    • H01H2221/05Force concentrator; Actuating dimple
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2227/00Dimensions; Characteristics
    • H01H2227/022Collapsable dome
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2229/00Manufacturing
    • H01H2229/008Die stamping

Abstract

TACTILE ELEMENT AND KEYBOARD INCLUDING
THE TACTILE ELEMENT
Abstract of the Disclosure A tactile snap-action element for use in keyboards, the element comprising an arcuately shaped invertible first dome and a second dome shaped actuating protrusion extending from the invertible second dome, the actuating dome protrusion being integral with the invertible dome and being non-invertible. The element is operated by an actuation force which acts directly or indirectly through the non-inverting second dome to invert the first dome and to provide tactile feedback. The keyboard includes a plurality of keys, each key comprising an element, a conductive circuit associated with the first dome and movable with the inversion of the first dome to electrically contact a second conductive circuit associated with the element.

Description

The present application is related to Applicant's Canadian Patent 1,12~,294, issued May 25, 1982.
The present invention relates to keyboards in-cluding keys which provide tactile ~eedback to a person operating the keys. More particularly, the present invention relates to a snap-action element which provides tactile feedback. m e element may be incorporated within each key of a keyboard having a plurality of keys. By way of example only, the keyboard has utility in retail outlets, airline terminals, fast-food restaurant termin-als, data terminals and calculators.
Prior art keyboards are of two basic types. One type of keyboard is an array of independent or discrete keys which are actuated to connect a circuit positioned lS beneath the keys, Typical uses for keyboards having dis~
crete keys include hand held electronic calculators, The second type is a keyboard wherein a flat sheet of pIastic has a legend printed thereon, the legend defining areas to be pushed to actuate keys positioned beneath the flat sheet of plastic.
In the keyboard of the type having a flat legend sheet, the legend sheet defines a plurality of points or areas on the sheet which the operator may press to actuate the key associated with the parti-cular area or point, It is highly desirable that each key of the keyboard provide the operator of the ~ey with tactile feedback when . ,-. : ,, : .
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electrical connection is made by actuation of a key.
The key which is positioned beneath the flat legend sheet provides for the connection of an electrical circuit and provides the operator of the key with tactile feed-back when the electrical circuit is made.
One problem with prior art keyboards having flatlegend sheets is that the keys positioned beneath the legend sheet have a complicated structure which requires many separa-te parts and which requires a large amount of time to assemble. The relatively large amount of time to assemble the keys is related not only to the large number of parts in the key, but also to the necessary alignment of the parts to insure proper actuation of the key. A
typical keyboard includes a legend sheet which defines a plurality of points which the operator of the keyboard may push to actuate the keys located beneath the legend sheet. Typically, beneath the legend sheet is a second sheet having a plurality of small projections, the second sheet being aligned with the legend sheet to provide one projection for each legend point or area on the legend sheet. The projections face downwardly into the keyboard and provide for the actuation of an arcuately shaped dis-crete invertible metal dome. The keyboard includes a discrete or individual metal dome for each key. The domes 25 are positloned on a printed circuit board which provides ~-a first circuit which is connected to the periphery of the dome and a second circuit which is positioned beneath the center of the dome so that when the dome inverts, a connection is made between the two circuits. The individual metal domes are retained on the circuit board by adhesive tape having holes through which the upper portions of the domes protrude. The cost of such a key-board is quite high due to the relatively high number of components, and the formidable assembly task. It should be understood that in the assembly of the prior art key-board, the center of the domes had to be aligned precisely . , ' .

.
, with the small projections in order for each key to provide for electrical connection and tactile feedback.
Thus, a high level of precision is necessary in the method of assembly. Moreover, because of the numerous components, I
the keyboard is relatively thick and presents a cluttered appearance to the user of the keyboard. A thick keyboard requires a greater space to be provided on the surface on which the keyboard is to be mounted. Furthermore, this prior art keyboard has a tendency to register a double entry when the key is pressed. Double entry often results from misalignment of the dome with the small projections. Another reason Eor the double entry is that the domes of the prior art tend to oscillate or bounce when actuated thereby providing for double actuation of the key. The prior art key also tended to close without tactile feedback. Closing of the key without tactile feedback is often a result of misalignment of the small projection with respect to the dome. For example, if the small projection were positioned away from the center of the dome, the projection could actuate the key without providing the user with tactile feeaback.
It should be understood that the keys are actuated by the operator pressing his finger against a point on the flat flexible legend sheet. The prior art switches had the disadvantage that the sheet had to be pressed at a point very close to the underlying projection which actuates the metal dome. With prior art keyboards, if the operator pressed his finger at a point removed ~rom the underlying projection, not only was the desired key not actuated, but there was a significant possibility that an adjacent key would be actuated.
A second type of keyboard is of the type that includes many discrete keys. Such a keyboard is disclosed in U.S.
Patent No. 3,898,421. This patent discloses a keyboard wherein discrete keys may be pushed to invert an element comprising a spherical protuberance including an annular shoulder separated from a central portion by a flexural .

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node to provide a double snap-action element. When the element is depressed by a force exerted on the central portion, the annular shoulder is moved and makes contact with a pair of fixed electrodes to make electrical contact and provide a first snap action. Thereafter, the central portion undergoes a second snap action whereby the central portion is positioned between the electrodes. It is a significant drawback of the element disclosed in this patent that the element undergoes two snap-actions. An operator using the key by having to press the key through two snap actions may be confused as to whether electrical contact was made once or whether electrical contact was made twice. Thus, it is undesirable to provide a central portion which is capable of inversion.
It is an object of the present invention to provide a keyboard having simplified and fewer components thereby allowing for simplified methods of assembly.
It is an object of the present invention to provide a keyboard wherein the domed actuators are not required to be aligned with actuating protrusions.
It is a further object of the present invention to provide a keyboard having keys wherein the tendency for double entry is reduced. It is another object of the present "
invention to reduce the possibility of the key closing without tactile feedback.
It is a further object of the present invention to provide keys which are less sensitive to the imposition of forces disposed from the center of the key. Restated, it is an object of the present invention to provide a key which may be actuated by a force imposed at an area of the legend sheet removed from the center of the actuator.
It is another object of the present invention to provide a keyboard whereby the legend sheet has a dual purpose in that the legend sheet defines actuating areas and also provides a conductive circuit.

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_ 5 It is a further object of the present invention to provide a keyboard having a reduced number of compon-ents thereby reducing material cost and assembly cost.
Summar~ of the Invention-In accordance with a particular embodiment of the invention, a tactile snap action electrical switch element consists of a sheet of base material and at least one snap action pro-trusion formed in and extending from the sheet of base material~
The protrusion has first and second arcuately shaped domes of different radii, the surface of the second dome being smooth and uninterrupted and the sur$ace of the first dome being smooth and interrupted only at the circular junctions with the sheet of base material~and the second dome. The first dome extends from and is integral with the sheet of base material while the second dome extends from and is integral with the first aome.
The first dome is at least partly inverted by applying a pressure against the second dome. The second dome has a smaller radius than the first dome, the ratio of the radius of the second dome to that of the first dome being selected such that the second dome will not be inverted by the applied pressure. The second dome is a non-invertible actuator for the first dome.
In accordance with a further em~odiment of the inven-tion, there is provided a tactile snap action key which is movable between an opened and closed position to open and close an electric circuit. The key includes a sheet of base material and a tactile element formed in the sheet of the base material and including a first arcuately shaped invertible dome - and a dome actuating protrusion means. The dome actuating pro-trusion means is a second arcuately shaped dome which is in-tegral with and extending from the first dome. m e first dome is inverted by applying pressure against the second dome. The second dome has a smaller radius than the first dome, the ratio of the radius of the second dome to the radius of the first dome being selected such that the second dome will not be in-verted by the applied pressure. The first dome provides for tactile feedback when it is inverted. ~he surface of the second dome is smooth and uninterrupted and the surface of the first dome is smooth and interrupted only by the circular junctions .

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- 5a -with the sheet of base material and the second dome. A first conductive means is associated with the first dome. There is also provided second conductive means, the second conductive means being aligned with and facing the first conductive means.
The actuation of the key provides the applied pressure against the second dome which at least partly inverts the first dome establishing electrical contact between the first conductive means and the second conductive means.
In accordance with a still further embodiment of the invention, a keyboard includes a flexible first sheet of printed circuitry having a plurality of tactile elements. Each element includes a first arcuately shaped aome which is integral with and extends outwardly from the first sheet, and a dome actuating protrusion means which is integral with and extends from the first dome. The dome actuating protrusion means is a second arcuately shaped dome, the first and second domes meet-ing at a circular junction and having smooth uninterrupted surface contours. The first dome is at least partly inverted by applying a pressure against the second dome. The second dome has a smaller radius than the first dome, the radius of the second dome being sufficiently less than the radius of the first dome to prevent inversion of the second ~lome by the applied pressure. A portion of the printed circuitry is carried by each of the first domes, and circuit means are aligned with the tactile elements and retained with respect to the first sheet, the printed circuit portions carried by the first domes contacting the circuit means when each of the first domes is partly inverted.
The present invention provides a keyboard including a plurality of keys, each key including a snap-action tactile actuator comprising a first arcuately shaped invertible dome wherein the dome includes a dome actuating protrusion which is integral with said dome and which is non-invertible. The actuating protrusion is relatively rigid in comparison to the dome and resists inversion under normal loading while the dome inverts under normal loading. In the preferred embodiment , ' LlS~8-1~
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of the invention set forth herein, the dome actuating pro-trusion comprises a second arcuate or domed protrusion which - is integral with the first dome and which extends from the cen-ter of the first dome. The sécond dome protrusion has a geometry which resists inversion under normal loading while the first dome has a geometry which inverts under normal loading.
; It should be understood that the above described actuator is capable of being used in many conventional key applications known in the prior art. Although the actuator of the present invention is capable of being used in devices having independent or discrete keys such as hand held cal-culators and the like, the actuator of the present invention is particularly adapted for use in keyboards of the type having a legend sheet which is relatively flat and which has a legend printed thereon.
In a legend sheet type k~yboard, the present inven-tion provides a particularly novel keyboard. The keyboard includes first flexible sheet having a circuit pattern disposed on one surface thereof, the sheet further in-cluding a plurality of domed actuators which may be molded in and integral with the sheet. The first sheet ! ' ~ ' ' :
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having domed actuators thereon is aligned with a second sheet including printed cixcuitry, the circuitry on the first sheet facing and being aligned with the circuitry on the second sheet to provide for connection of the circuitry when the domed actuator is actuated. The second sheet may be ~lexible or stiff. Preferably, the two sheets are spaced apart and held in position by an lnsulating separator or adhesive which functions to insulate the circuits on the first sheet from the circuits on the second sheet except at points where the domed actuator will contact the second sheet when the domed actuator is actuated.
The keyboard is positioned so that the domed actuator protrudes toward the person operating the keyboard. In this instance/ a legend sheet having a legend printed thereon is positioned above the dome actuators and the points on the printed legend are aligned with the actuators so that a person pressing the legend board deforms the actuator downwardly.
The method of assembling the keyboard of the present invention is particularly simple: the first flexible sheet of printed circuitry having the domes formed therein need only be aligned with a second sheet of printed circuitry with an insulating spacer therebetween, and the parts may be adhered together if desired.
.

~rief Description of the Drawings:
- FIGURE 1 shows a perspective view of an individual tactile element having one quarter of the element sectioned away;
FIGURE 2 shows a side sectional view of a key including the domed actuator shown in FIGURE l;
FIGURE 3 shows a side sectional view of the key shown in FIGURE 2, the key having been actuated;
FIGURE 4 is an exploded perspective view o~ a key-board including the key shown in FIGURES 2 and 3;

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FIGURE 5 is a side sectional view of another emboaiment of a key, FIGURE 6 is a schematic sectional view of the actuator shown in FIGURE l;
FIGURE 7 is a sectional elevation view of a keyboard incorporating the new subject ma-tter set forth herein over U. S. Patent 4,245,138, issued January 13, 1981, and FIGURE 8 is a view of a detail of FIGURE 7.
Referring to FIGURE l, the snap-action tactile element 10 includes an arcuately shaped invertible dome 11 and a dome actuating protrusion 12 which is integral with the dome and which is noninvertible. Dome actuating pro~
trusion 12 is rigid in comparison to dome 11 and resists inversion under normal loading while dome 11 inverts under normal loading, Protrusion 12 has a generally cylindrical shape which terminates in a flat circular surface 13. The cylindrical walls of the dome actuating protrusion 12 pro-vide a geometry which resists inversion when an actuation force is directed along the longitudinal axis of the cyl-indrical walls. The dome has a geometry which inverts under normal loading. However, it should be noted that other shapes of dome actuating protrusions may be used pro-vided the aome actuating protrusions do not invert when the actuator is operated. Actuator 10 is preferably molded by conventional means from a sheet of insulating material having conductive circuitry 16 formed thereon. ~he con-ductive circuitry will be referred to as ~printed circuit-ry~. It should be understood that the circuitry may be of a conventional type and may be formed by printed circuit techniques or other techni~ues known in the art such as, for example, conductive inking or die stamping. Printed circuitry 16 may cover all or a portion of the interior surface of actuator 10. Sheet 15 is preferably made from an insulating plastic material which is flexible and resilient. Sheet 15 is preferably made of polyester ~..
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material sold by DuPont undex the trademark MYLAR.
Examples of other materials are: CELENARTM (Celanese, Inc ), POLYSULFONE (Union Carbide), POLYETHER SULEONE
(ICI, Inc ); and LEXANTM (General Electric ~o.).
Referring simultaneously to FIGURES 2, 3 and 4, a keyboard including a plurality of keys is shown. Key-I board 17 includes a plurality of snap-action tactile ele-¦ ments 10 as previously described. Keyboard 17 includes a flexible sheet 18 having printed circuitry 19 on one side thereof. Adhesive 20 insulates circuit ]6 from circuit 19 - and retains the sheets 15 and 1~3 in position with respect to each other. Adhesive 20 includes a p]urality of aper-tures 21 which allow for movement of actuator 10 there-through to contact sheet 15 with sheet 1~, thereby connect-ing printed circuit 16 with printed circuit lg.
The adhesive may be a film with appropriate die cut apertures 21. The film is adherent on both sides one side of the film is placed in contact wit:h one of the sheets 15 or 18 and then the other sheet is brought into contact with the other side of the film. Preferably, the film may be any one of the following, depending on the particular applications: synthetic rubber base pressure sensitive;
acrylic polymer base pressure sensitive: and silicone polymer base pressure sensitive. It shou:Ld be understood that the adhesive may also be applied in :Liquid form to the surface of sheet 18 with appropriate masking for aper-tures 21, and subsequently, sheet 15 is positioned in con-tact with adhesive 20 Keyboard 17 is positioned on and secured relative to a supporting surface 22. Supporting surface 22 may represent a surface of a cash register with which the keyboard may be used; or surface 22 may be an integral part of the keyboard.
FIGURES 2 and 3 show respecitvely a key in the non-actuated position and the actuated position. When a downward force, F, is imposed on sheet 18, sheet 18 deforms r downwardly. It should be understood that sheet 18 may include a legend printed on the surface of sheet 18 which indicates an actuation area. A person operating the keyboard applies an actuation force to this actuation area. It should be understood that the Eorce may be applied off center from the tactile element lO and still actuate the key. When an off center actuation force is applied to the key, the flat surface area 13 allows for the force to be relatively evenly distributed over the ac~uator area, pr~v~;~ 5~ c~
i~ ~ 10 thereby ~ ~or actuation of the key (S~ee area 13 is best shown in FIGURE 1). As shown in FIGURE 3, the arcuately shaped dome portion ll inverts while the dome actuating protrusion 12 does not invert. The reason !
protrusion 12 does not invert is that the walls o~ a cylinder will support heavy loads without collapse.
However, it should be understood that protrusion 12, as shown in FIGURE 3, may deform to a slight degree to accommodate the inversion of dome portion ll. By inversion, it is meant that the direction of the curvature of at least part of the wall of dome ll is subject to rapid change. That is, the curvature of at least part of the wall of dome ll undergoes a reversal in the direction of slope, and the reversal occurs suddenly to provide tactile ~eedback. Dome portion ll travels downwardly for a very short distance before dome inversion occurs. As shown in FIGURE 3, the direction of curvature of a part o~ arcuately shaped dome portion ll changes, i.e., reverses. However, the dome actuating protrusion 12 does not invert.
As shown in FIGURES 2, 3 and 4, sheet 18 functions both as a printed circuit and as a legend sheet. It should be understood, that in r~ome applications, it may be desirable to include an additional legend sheet 18(a) positioned above sheet 18. A separate legend sheet is desirable in the circumstance where the user desires to change the legend but does not desire to change the hardware beneath the legend.

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FIGURE 5 shows a side sectioned view of an actuator 10 positioned with dome 11 convex relative to the user, that is, protruding toward the user of the keyboard. It should be understood that the force, F, can be imposed by either a discrete key as is often done in calculators or by a legend sheet 18(a) as previously discussed. The keyboard shown in FIGURE 5, is fllpped 180 from that shown in FIG~RE 2 but is identical to the keyboard shown in FIGURE 2 except that it is no longer necessary to print a legend on sheet 18. The dash lines show the actuator in the unactuated posi-tion with an optional legend sheet 18(a), 1:
and the solid lines show -the actuator in the actuated posi-tion.
Research has determined that there is a range of preferred dimensions for the ac-tuator of FIGURES 1-6.
Referring to FIG~RE 6, the arcuately shaped dome preferably has the shape of a sphere having a radius R, which should be within the range of about .2 to about 1.0 inches. The sphere should protrude from the sheet a height H, of between about .010 and about .100 inches. The -thickness ..
of the sheet, t, should be hetween about .002 and about .007. The cylindrical protrusion should have a diameter, d, in the range of between about .060 to about .250 and a height, h, in the range of about .010 to about .060.
The dimension D, is determined as a function of R and H.
An illustrative construction at the present time is:
R = .750, H = .030, d = .125, h = .020.
In general, an increase in the diarneter, d, of the protrusion provides for actuation of the tacti:Le element with a force applied further from the center o:E the tactile element. An increase in "d" should be accompanied by an increase in R and/or H to provide for tactile feedback. Generally speaking the height, h, o:~ the protrusion is not critical to the tactility of the tactile element, but, h must be sufficiently large so that the cylindrical protrusion exists as a separate ge-~metry : i .

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, ' ~ ; ' "' ~ ~5~8~3 Maximum values of h are determined by the elon~ation characteristics of the plastie filmO In general, if the thickness, t, is increased, R, H and/or d should be in~
creased, A decrease in the required actuation force may be accomplished by decreasing t (with attendant decreases in R, H and/or d) or may be accomplished by decreasing the ratio of d/R.
Referring now to FIGU~ES 7 and 8, the new key-board component and keyboard assembly are shown. m e keyboard assembly in FIGURE 7 has a rigid backer or re-inforcing board 110 which may be metal, hard plastic such as Bakelite, fiberboard, or other suitable support material. A layer of flexible plastie insulating material 112, such as MylarTM or other suitable insulating material, is positioned on one side of backing board 110 and, prefer-ably, is adhered to the backing board. Conductive printed circuit patterns 114, such as copper or conductive ink, are on the top side of insulating layer 112, plastic sheet 112 and conductive patterns 114 being, in effect, a unitary layer of printed cireuitry~ A plastic spacer 116 is posi-tioned on top of sheet 112, and spacer 116 may be adhe..ed to sheet 112. Plastie spacer 116 (which may also be MylarTM) has a series of circular openings 118 each of whieh is aligned with a circuit pattern 114 and with an associated domed key element 120. The domed key elements 120 are protrusions formecl in a sheet of unitary plastic (e,g., Mylar ) material 122, and printed eircuit patterns 124 of copper, ink or other suitable conductive material which extend along the underside of sheet 122 and extend into at least part of the underside of each dome. Sheet 122 is initially a flat piece of flexible printed circuitry having the circuit patterns 1~. The domes may be formed with shaped tooling under heat and pressure by techniques known in the art. Flat (i.e., undomed) portions of sheet 122 may be aclhered to spacer sheet 116.

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Each dome 120 has a first arcuate or spherical dome portion lZ6 and a second dome shaped arcuate or spherical portion 128 extending from the top center of the first dome portion 126 Dome portion 126 constitutes an invertible dome portion, and dome portion 128 is a non-invertible dome shaped actuator for the invertible dome portion 126.
A flat cover sheet 130 of plastic (e g., MylarTM) is located and positioned to be in contact with the dome actuator 128 on top of each dome 120, and the upper portion of sheet 130 (i e , the side not in contact with the domes) may have number, letters, or other key identifying indicia thereon to be read by the user of the keyboard.
A protrusion 120 and its associated circuitry on sheet 112 constitutes, in effect, a key station. In oper-ation of the keyboard of FIG~RE 7, the user locates the particular key station which is desired to be actuated (such as by reading the indicia on the top of sheet 130).
~he user then pushes downwardly on that key to bring con-ductor pattern 124 in contact with conductor pattern 114 to complete a circuit and generate an electrical sig~al from the keyboard. The delivery of an actuatin~ force to the top of sheet 130 to a specific key results in the transmission of that force through the dome shaped actuator 128 to dome segment 126 to move dome se~ment 126 downward to brin~ part of the conductor 124 into contact with the conductor 114 to complete the electrical circuit.
In this downward movement, at least a portion of dome 126 is inverted, as shown by the dotted lines in FIGURE 8 which correspond to the downward or actuated position of dome 120.
That is, while dome portion 126 in its unactuated position has a convex curvature as viewed from above, at least a part of the dome portion 126 is inverted in the actùated position so that the curvature is reversed, i.e., concave when viewed from above. Stated in another way, the slope of the curve of dome 126 is positive in the unactuated r.l` ~

` ` ~ .
'~

condition, whereas -the slope of at least part of the dome portion 126 is negative in the actuated position. The inversion occurs with a snap action so the user experiences a tactile feedback as the dome segment 126 is moved downward -to complete electrical contact between conductors 124 and 114. The upper dome segment 128 does not invert during actuation of the dome. ~a-ther, the upper dome segment 128 acts as an actuator for the key and functions to transmit the actuating force to the lower dome segment 126.
This result wherein the upper dome segment 128 is non-invertible (under normal actuating loads) while the lower dome segment 126 is at least partially inverted is the result of the relative dimensioning of the tw~ dome segments. This relative dimensioning is shown in detail ,~ in FIGURE 8 wherein a preferred dome configuration is shown. ~ the dome configuration of FIGURE 8; the radius "R" of the major dome section 126 is in a range between .200 inches and 1.0 inches (with one illustrative embodi-ment being 0.750 inches); the height "H" of the major dome segment 126 is in a range between .010 inches and .100 inches (with one illustrative embodiment being .030 inches); the radius "r" of the minor domed segment 128 is in a range be-tween .030 inches and .125 inches (with one illustrative embodiment being .0625 inches); and the height "h" of the minor upper dome segment 128 is in a range between .010 inches and .060 inches (with one illustrative embodiment being .020 inches). The thickness of sheet 122 is between 0.002 and 0.007 inches. The dimension "D" of the major dome segment 126 is determined as a function of R and H, and the dimension "d" of -the minor dome segment 128 is determined as a function of r and h.
While the thickness t of the sheet may vary, it is a critical requirement that the dimensions of the major dome segment 126 and the minor dome segment 128 remain . , , ~

.
.

~5 in the ratio of the ranges set forth above, or with appropriate adju~stment for changes in thickness t beyond ~ re. I rl Qb~v e.
that set forth he~4~ T~ithin -those ranges, the key configuration of this invention will function so -that under normal operating forces at least a part of major dome segment 126 will invert under normal actuating forces while minor dome segment 128 will serve as a force transmitter and will not invert.
An important aspect of all configurations of this invention is that it achieves appropriate key action with tactile response even though the actuating force may be off center. Thus, for example, even if the actuating force applied to a particular dome is somewhat ofE cen-ter of the dome, i.e., not applied to sheet 130 directly above the dome to be actuated and not directly in the downward direction with respect -to that dome, the actuator dome 128 translates enough of the actuating force into -the downward direction to actuate the major dome portion 126 and achieve the desired tactile response. This is a significant advantage over many prior art configura-tions wherein tactile response may be poor or not be experienced at all if a plastic spherical dome key is actuated off center.
While p~eferred embodiments have been shown and described, various modifications and substitut:ions may be made thereto without departing from the spirLit and scope of the present invention. ~ccordingly, :it should be understood that the present invention has been described by way of illustration and not limitation.

: -, ` ~ ! .
..
' ~ :

Claims (23)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-
1. A tactile snap action electrical switch element comprising:
a sheet of base material, and at least one snap action protrusion formed in and extending from said sheet of base material, said protrusion having first and second arcuately shaped domes of different radii, the surface of said second dome being smooth and un-interrupted and the surface of said first dome being smooth and interrupted only at the circular junctions with the sheet of base material and the second dome, said first dome extending from and being integral with said sheet of base material, said second dome extending from and being integral with said first dome, said first dome being at least partly inverted by applying a pressure against said second dome, said second dome having a smaller radius than said first dome, the ratio of the radius of said second dome to that of the first dome being selected such that said second dome will not be inverted by said applied pressure, said second dome being a noninvertible actuator for said first dome.
2. A tactile switch element as in claim 1 wherein:
said second dome extends from the center of said first dome.
3. A tactile switch element as in claim 2 wherein:
each of said first and second domes is a portion of a sphere.
4. A tactile switch element as in claim 3 wherein:
said first dome is a portion of a sphere of larger radius than said second dome.
5. A tactile switch element according to claim 4 wherein:

the radius, R, of the first dome is in the range of between 0.2 and 1.0 inches, the height, H, of the first dome is in the range of between 0.010 and 0.100 inches, the radius, r, of the second dome is in the range of between 0.030 and 0.125 inches;
The height, h, of the second dome is in the range of between 0.010 and 0.060 inches, and the thickness, t, of the element is in the range of between 0.002 and 0.007 inches.
6. A snap action electrical switch element which is capable of being inverted by an actuation force to provide tactile feedback, the element having a sheet of base material, and at least one snap action protrusion formed in said base material, said protrusion having a first domed contour and a second domed contour, said first domed contour being invertible to provide tactile feedback and said second domed contour re-sisting inversion when the actuation force is imposed upon the element.
7. A switch element according to claim 6 wherein said second domed contour extends from the center of said first domed contour.
8. A switch element as in claim 7 wherein:
each of said domed contours is a portion of a sphere.
9. A switch element as in claim 8 wherein:
said first domed contour is a portion of a sphere of larger radius than said second domed contour.
10. A switch element according to claim 8 wherein:
the radius, R, of the first dome is in the range of between 0.2 and 1.0 inches, the height, H, of the first dome is in the range of between 0.010 and 0.100 inches, he radius, r, of the second dome is in the range of between 0.030 and 0.125 inches, the height, h, of the second dome is in the range of between 0.010 and 0.060 inches, and the thickness, t, of the element is in the range of between 0.002 and 0.007 inches.
11. A tactile snap-action key which is movable between an opened and closed position to open and close an electrical circuit, said key comprising:
a sheet of base material, a tactile element formed in said sheet of said base material and including a first arcuately shaped invertible dome and a dome actuating protrusion means, said dome actuating protrusion means being a second arcuately shaped dome which is integral with and extending from said first dome, said first dome being inverted by applying a pressure against said second dome, said second dome having a smaller radius than said first dome, the ratio of the radius of said second dome to the radius of the first dome being selected such that said second dome will not be inverted by said applied pressure, said first dome providing for tactile feedback when it is inverted, the surface of said second dome being smooth and uninterrupted and the surface of said first dome being smooth and interrupted only by the circular junctions with said sheet of base material and the second dome, first conductive means being associated with said first dome, and second conductive means, said second conductive means being aligned with and facing said first conductive means, the actuation of the key providing said applied pressure against said second dome which at least partly inverts said first dome establishing electrical contact between said first conductive means and said second conductive means.
12. A key according to claim 11 wherein said first conductive means comprises a printed circuit formed on the surface of said first dome and said second conductive means comprises a printed circuit positioned in alignment with said first conductive means to provide for electrical contact be-tween the first and second printed circuits when said first dome is inverted.
13. A tactile key as in claim 11 wherein:
said second dome extends from the center of said first dome.
14. A tactile key as in claim 13 wherein:
each of said first and second domes is a portion of a sphere.
15. A tactile key as in claim 14 wherein:
said first dome is a portion of a sphere of larger radius than said second dome.
16. A tactile key as in claim 15 wherein:
the radius, R, of the first dome is in the range of between 0.2 and 1.0 inches, the height, H, of the first dome is in the range of between 0.010 and 0.100 inches, the radius, r, of the second dome is in the range of between 0.030 and 0.125 inches, the height, h, of the second dome is in the range of between 0.010 and 0.060 inches, and the thickness, t, of the element is in the range of between 0.002 and 0.007 inches.
17. A keyboard comprising:
a flexible first sheet of printed circuitry having a plurality of tactile elements, each element including a first arcuately shaped dome which is integral with and ex-tends outwardly from said first sheet and a dome actuating protrusion means which is integral with and extends from said first dome, said dome actuating protrusion means being a second arcuately shaped dome, said first and second domes meeting at a circular junction and having smooth uninterrupted sur-face contours, said first dome being at least partly inverted by applying a pressure against said second dome, said second dome having a smaller radius than said first dome, said radius of said second dome being sufficiently less than the radius of said first dome to prevent inversion of said second dome by said applied pressure, a portion of printed circuitry carried by each of said first domes, and circuit means aligned with said tactile elements and retained with respect to said first sheet, the printed circuit portions carried by said first domes contacting the circuit means when each of said first domes is partly inverted.
18. A keyboard according to claim 17 wherein the circuit means comprises a second sheet of printed circuitry, the printed circuitry on the first sheet being selectively insulated from the printed circuitry of the second sheet to allow connection of the printed circuitry only when the domes are inverted.
19. A keyboard according to claim 18 wherein said first sheet of printed circuitry comprises a sheet having printed circuitry on one surface thereof and said second sheet comprises a sheet of printed circuitry having printed circuitry on one surface thereof, said first and second sheets being aligned so that the printed circuitry of the first sheet faces the printed circuitry of the second sheet, said printed circuitry of the first sheet being separated from the printed circuitry of the second sheet by insulating means, said insulating means including a plurality of apertures aligned with said first domes to allow for contact of the first printed circuitry with the second printed circuitry when said first domes are inverted.
20. A keyboard as in claim 17 wherein:
said second dome extends from the center of said first dome.
21. A keyboard as in claim 20 wherein:
each of said first and second domes is a portion of a sphere.
22. A keyboard as in claim 21 wherein:
said first dome is a portion of a sphere of larger radius than said second dome.
23. A keyboard as in claim 22 wherein:
the radius, R, of the first dome is in the range of between 0.2 and 1.0 inches:
the height, H, of the first dome is in the range of between 0.010 and 0.100 inches, the radius, r, of the second dome is in the range of between 0.030 and 0.125 inches, the height, h, of the second dome is in the range of between 0.010 and 0.060 inches, and the thickness, t, of the element is in the range of between 0.002 and 0.007 inches.
CA000368873A 1980-01-31 1981-01-20 Tactile element and keyboard including the tactile element Expired CA1154810A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US117,063 1980-01-31
US06/117,063 US4307268A (en) 1978-11-17 1980-01-31 Tactile element and keyboard including the tactile element

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CA1154810A true CA1154810A (en) 1983-10-04

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US (1) US4307268A (en)
JP (2) JPS56121224A (en)
BE (1) BE887274A (en)
CA (1) CA1154810A (en)
DE (1) DE3103127A1 (en)
FR (1) FR2475287B1 (en)
GB (1) GB2068841B (en)

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Also Published As

Publication number Publication date
JPS56121224A (en) 1981-09-24
FR2475287A1 (en) 1981-08-07
US4307268A (en) 1981-12-22
GB2068841A (en) 1981-08-19
GB2068841B (en) 1984-05-02
FR2475287B1 (en) 1985-12-13
JPH02197025A (en) 1990-08-03
BE887274A (en) 1981-05-14
JPH0216526B2 (en) 1990-04-17
DE3103127A1 (en) 1982-01-07

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