EP0280491A2 - Contact-type keyboard for typewriters - Google Patents
Contact-type keyboard for typewriters Download PDFInfo
- Publication number
- EP0280491A2 EP0280491A2 EP88301485A EP88301485A EP0280491A2 EP 0280491 A2 EP0280491 A2 EP 0280491A2 EP 88301485 A EP88301485 A EP 88301485A EP 88301485 A EP88301485 A EP 88301485A EP 0280491 A2 EP0280491 A2 EP 0280491A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- dome portion
- diaphragm
- actuator
- internal
- stop element
- 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.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
- H01H13/70—Switches 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
- H01H13/702—Switches 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H2215/00—Tactile feedback
- H01H2215/004—Collapsible dome or bubble
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H2227/00—Dimensions; Characteristics
- H01H2227/022—Collapsable dome
Definitions
- the present invention relates to a contact-type keyboard for typewriters of the type set forth in the introductory part of claim 1.
- the dome portions are usually integrally formed in a rubber mat.
- each movable actuator comprises a shoulder co-operating with a stop portion of the mat to define the travel movement of the actuator, each stop portion being disposed adjacent to the respective dome portion. While this keyboard is functional, it does suffer from the disadvantage of being rather bulky precisely due to the fact that the actuator has its shoulder projecting laterally and the mat has the stop portion projecting from the surface, outside the respective dome portion, so that it is also rather expensive.
- a keyboard is also known in which the dome portion is of a rather complicated shape, having an external diaphragm of variable thickness and internal diaphragm having a shoulder capable of cooperating with the base of the movable actuator.
- the movable actuator comprises an external ring which, when the associated key is depressed, is capable of co-operating with the part of the external diaphragm at which the thickness thereof is at its smallest.
- That keyboard suffers from the disadvantage that the dome portion and the actuator are complicated in design and are thus very expensive, while in addition there is substantial wear of the external diaphragm due to the fact that, when it is deformed by virtue of the associated key being depressed, the portion of minimum thickness is continuously engaged by the respective external ring, and the internal diaphragm which is deformed by the base of the movable actuator.
- the object of the present invention is therefore to provide a contact-type keyboard which is of reduced dimensions, simple, reliable and which at the same time is very easy to use, practical and inexpensive.
- the contact-type keyboard according to the model is generally identified by reference numeral 11 and comprises a series of keys 12, each of which is mounted on an actuator 13 which is displaceable axially in known manner per se.
- the keys 12 and the actuators 13 are shown diagrammatically and are substantially similar to those described in our published European patent application EP 0 091 284.
- Each actuator 13 with the lower part thereof is capable of co-operating with an elastic element 14 formed by a dome portion of silicone rubber, of inverted cup shape.
- the elements or dome portions 14 may be produced individually or they may be provided in one or more rubber mats 16, by means of technologies known in themselves.
- Each dome portion 14 (see Figure 2) comprises a suitably shaped peripheral diaphragm 17 of limited and uniform thickness, an internal diaphragm 18 of limited and uniform thickness and a central part 19 to which a cylindrical conducting pellet or insert 21 is fixed.
- the central part 19 is of substantially the same size as the conducting pellet 21 which is capable of short-circuiting an element 22 of a printed ciruit 23 when the respective key 12 is depressed, thereby to generate a corresponding electrical signal in known manner per se.
- the internal diaphragm 18 defines an upper space 24 which in turn can define a circular external ring 26 against which the repective actuator 13 normally bears.
- a stop element 27 projects in the interior of the dome portion 14, is opposite to the circular external ring 26 and is coaxial and concentric with the central part 19 and the conducting pellet 21, being in the form of a circular ring.
- the internal diaphragm 18 is connected by one end to the central part 19 and by the other end to the opposite part of the circular external ring 26.
- the peripheral diaphragm 17 is connected by one end to the opposite part of the circular external ring 26 and by the other end to the mat 16.
- stop element 27 being disposed between the peripheral diaphragm 17 and the internal diaphragm 18 and therefore with the two diaphragms 17 and 18 being connected at the ends to the opposite part of the circular external ring 26, they are in the same horizontal plane adjacent to the stop element 27.
- the stop element 27 is capable of co-operating with the surface 28 on which the element 22 of the printed circuit 23 is normally disposed, as indicated in dash-dotted lines in Figure 2.
- the stop element 27 defines the travel movement of the respective actuator 13.
- the operator causes axial displacement of the respective actuator 13 which, always being in contact with the circular external ring 26, causes it to be depressed, deforming the external and internal diaphragms 17 and 18 and the conducting pellet 21 comes into engagement with the element 22, thereby to generate a corresponding electrical signal.
- the stop element 27 engages against the surface 28 whereby the travel movement of the actuator 13 is stopped.
- the stop element 27 is in the form of a circular ring, the arrangement always provides for a secure and stable condition of engagement and abutment as between the element 27 and the surface 28. In that way, even if the operator continues to apply a pressure to the depressed key 12, the travel movement of the actuator 13 is reliably stopped by the stop element 27 bearing against the surface 28. That therefore ensures that both the conducting pellet 21 and the element 22 of the printed circuit 23 do not suffer from rupture, damage or other drawbacks.
- peripheral diaphragm 17 and the internal diaphragm 18 are adjacent to the stop element 27 and, being of limited and uniform thickness, permit deformation of both thereof with a minimum amount of pressure when the respective key 12 is actuated, immediately returning to their initial position as soon as the pressure ceases to be applied without the smallest amount of wear among the various parts which make up the keyboard 11.
- the stop element 27 in the form of a circular ring disposed in the interior of each elastic element or dome portion 14 substantially reduces the overall external size, also simplifies the form of the actuator 13, and ensures a secure and stable stop action, thus avoiding wear as between the conducting pellet 21 and the element 22 of the printed circuit 23.
- the pressure of the actuator 13 goes from the circular external ring 26 directly and only to the stop element 27 whereby the peripheral and internal diaphragms 17 and 18 are always only subjected to simple bending stress, thus avoiding composite pressures, forces and stresses which would prejudice the function and integrity thereof.
Abstract
The contact-type keyboard (11) comprises a plurality of keys (12), each having an actuator (13) which is movable axially for co-operating with an elastic element (14) formed by a rubber dome portion in the form of an inverted cup. Fixed inside each dome portion (14) is a conducting pellet 21 for short-circuiting two corresponding elements (22) of a printed circuit (23). A stop element (27) which is housed within each dome portion (14) is in the form of a circular ring and is coaxial and concentric with the conducting pellet (21) and is capable of being stopped by the stop surface (28) on which the element (22) of the printed circuit (23) is fixed. The stop element (27) also projects within the dome portion (14), is opposite to a circular external ring (26) capable of co-operating with the respective actuator (13), and is disposed between a peripheral diaphragm (17) and a radially internal diaphragm (18) which are of limited and uniform thickness and which are adjacent to the stop element (27).
Description
- The present invention relates to a contact-type keyboard for typewriters of the type set forth in the introductory part of claim 1. The dome portions are usually integrally formed in a rubber mat.
- A keyboard of the above kind is known, in which each movable actuator comprises a shoulder co-operating with a stop portion of the mat to define the travel movement of the actuator, each stop portion being disposed adjacent to the respective dome portion. While this keyboard is functional, it does suffer from the disadvantage of being rather bulky precisely due to the fact that the actuator has its shoulder projecting laterally and the mat has the stop portion projecting from the surface, outside the respective dome portion, so that it is also rather expensive.
- A keyboard is also known in which the dome portion is of a rather complicated shape, having an external diaphragm of variable thickness and internal diaphragm having a shoulder capable of cooperating with the base of the movable actuator. In addition the movable actuator comprises an external ring which, when the associated key is depressed, is capable of co-operating with the part of the external diaphragm at which the thickness thereof is at its smallest. That keyboard suffers from the disadvantage that the dome portion and the actuator are complicated in design and are thus very expensive, while in addition there is substantial wear of the external diaphragm due to the fact that, when it is deformed by virtue of the associated key being depressed, the portion of minimum thickness is continuously engaged by the respective external ring, and the internal diaphragm which is deformed by the base of the movable actuator.
- The object of the present invention is therefore to provide a contact-type keyboard which is of reduced dimensions, simple, reliable and which at the same time is very easy to use, practical and inexpensive.
- To this end the contact-type keyboard according to the invention is characterised as set forth in claim 1.
- A preferred embodiment of the present invention is set forth in the following description which is given by way of non-limiting example with reference to the accompanying drawing in which:
- Figure 1 is a side view of part of the keyboard,
- Figure 2 is a view in partial section of some details from Figure 1 on an enlarged scale, and
- Figure 3 is a partial plan view of some details from Figure 1 on a different scale.
- Referring to Figure 1, the contact-type keyboard according to the model is generally identified by
reference numeral 11 and comprises a series ofkeys 12, each of which is mounted on anactuator 13 which is displaceable axially in known manner per se. Thekeys 12 and theactuators 13 are shown diagrammatically and are substantially similar to those described in our published European patent application EP 0 091 284. - Each
actuator 13 with the lower part thereof is capable of co-operating with anelastic element 14 formed by a dome portion of silicone rubber, of inverted cup shape. - The elements or
dome portions 14 may be produced individually or they may be provided in one ormore rubber mats 16, by means of technologies known in themselves. - Each dome portion 14 (see Figure 2) comprises a suitably shaped
peripheral diaphragm 17 of limited and uniform thickness, aninternal diaphragm 18 of limited and uniform thickness and acentral part 19 to which a cylindrical conducting pellet orinsert 21 is fixed. Thecentral part 19 is of substantially the same size as the conductingpellet 21 which is capable of short-circuiting anelement 22 of a printedciruit 23 when therespective key 12 is depressed, thereby to generate a corresponding electrical signal in known manner per se. - The
internal diaphragm 18 defines anupper space 24 which in turn can define a circularexternal ring 26 against which therepective actuator 13 normally bears. Astop element 27 projects in the interior of thedome portion 14, is opposite to the circularexternal ring 26 and is coaxial and concentric with thecentral part 19 and the conductingpellet 21, being in the form of a circular ring. Theinternal diaphragm 18 is connected by one end to thecentral part 19 and by the other end to the opposite part of the circularexternal ring 26. Theperipheral diaphragm 17 is connected by one end to the opposite part of the circularexternal ring 26 and by the other end to themat 16. With thestop element 27 being disposed between theperipheral diaphragm 17 and theinternal diaphragm 18 and therefore with the twodiaphragms external ring 26, they are in the same horizontal plane adjacent to thestop element 27. - The
stop element 27 is capable of co-operating with thesurface 28 on which theelement 22 of the printedcircuit 23 is normally disposed, as indicated in dash-dotted lines in Figure 2. When thestop element 27 bears against thesurface 28, it defines the travel movement of therespective actuator 13. In fact, by depressing akey 12, the operator causes axial displacement of therespective actuator 13 which, always being in contact with the circularexternal ring 26, causes it to be depressed, deforming the external andinternal diaphragms pellet 21 comes into engagement with theelement 22, thereby to generate a corresponding electrical signal. Thestop element 27 engages against thesurface 28 whereby the travel movement of theactuator 13 is stopped. Since thestop element 27 is in the form of a circular ring, the arrangement always provides for a secure and stable condition of engagement and abutment as between theelement 27 and thesurface 28. In that way, even if the operator continues to apply a pressure to thedepressed key 12, the travel movement of theactuator 13 is reliably stopped by thestop element 27 bearing against thesurface 28. That therefore ensures that both the conductingpellet 21 and theelement 22 of the printedcircuit 23 do not suffer from rupture, damage or other drawbacks. - It will be apparent therefore that the
peripheral diaphragm 17 and theinternal diaphragm 18 are adjacent to thestop element 27 and, being of limited and uniform thickness, permit deformation of both thereof with a minimum amount of pressure when therespective key 12 is actuated, immediately returning to their initial position as soon as the pressure ceases to be applied without the smallest amount of wear among the various parts which make up thekeyboard 11. Thestop element 27 in the form of a circular ring disposed in the interior of each elastic element ordome portion 14 substantially reduces the overall external size, also simplifies the form of theactuator 13, and ensures a secure and stable stop action, thus avoiding wear as between the conductingpellet 21 and theelement 22 of the printedcircuit 23. In addition, with thestop element 27 being opposite to the circularexternal ring 26, the pressure of theactuator 13 goes from the circularexternal ring 26 directly and only to thestop element 27 whereby the peripheral andinternal diaphragms
Claims (4)
1. A contact-type keyboard for typewriters comprising a plurality of keys (12) each having an axially movable actuator (13) capable of co-operating with an elastic element (14) formed by a rubber dome portion in the form of an inverted cup and a stop element (27) capable of stopping the travel movement of the respective actuator against a stop surface (28) a conducting pellet (21) for short-circuiting a corresponding element (22) of a printed circuit (23), and in which each dome portion comprises a peripheral diaphragm (17) of limited thickness and a circular external ring (26) capable of co-operating with the respective actuator, characterised in that each dome portion comprises a central internal part (19) of transverse dimensions which are substantially equal to those of the conducting pellet (21), and a radially internal diaphragm (18) of limited and uniform thickness which connects the central part to the circular external ring (26) and in that the stop element (27) projects in the interior of dome portion (14), is opposite to the circular external ring (26) and is disposed between the internal and peripheral diaphragms (18 and 17) of the dome portion.
2. A contact-type keyboard according to claim 1, characterised in that the stop element (27) comprises a circular internal ring disposed between the peripheral diaphragm (17) and the internal diaphragm (18).
3. A contact-type keyboard according to claim 2, characterised in that the peripheral diaphragm (17) and the internal diaphragm (18) are both capable of undergoing deformation under the pressure of the actuator (13), permitting engagement of the circular internal ring (27) against the stop surface (28), immediately resuming their initial position as soon as the pressure ceases, and in that the two circular rings (26, 27) are substantially aligned.
4. A contact-type keyboard according to any of the preceding claims, characterised in that the stop element (27) is opposite to the circular external ring (26) and aligned with this ring to transfer the pressure of the actuator (13) from the circular external ring (26) directly and only to the stop element (27) and to cause the two diaphragms (17, 18) to be subjected only to flexural stress.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT5306987U | 1987-02-26 | ||
IT5306987U IT210475Z2 (en) | 1987-02-26 | 1987-02-26 | CONTACT KEYBOARD FOR WRITING MACHINES |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0280491A2 true EP0280491A2 (en) | 1988-08-31 |
EP0280491A3 EP0280491A3 (en) | 1990-01-10 |
Family
ID=11279708
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP88301485A Withdrawn EP0280491A3 (en) | 1987-02-26 | 1988-02-22 | Contact-type keyboard for typewriters |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0280491A3 (en) |
IT (1) | IT210475Z2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4952761A (en) * | 1988-03-23 | 1990-08-28 | Preh-Werke Gmbh & Co. Kg | Touch contact switch |
WO2000036706A2 (en) * | 1998-12-17 | 2000-06-22 | Electronics For Imaging, Inc. | Silicon switch |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE7606008U1 (en) * | 1976-02-28 | 1976-08-26 | Preh, Elektrofeinmechanische Werke Jakob Preh Nachf., 8740 Bad Neustadt | Push button switch |
DE3227457A1 (en) * | 1982-07-22 | 1984-01-26 | Siemens AG, 1000 Berlin und 8000 München | Push-button unit |
US4518833A (en) * | 1983-07-18 | 1985-05-21 | Gates Data Products, Inc. | Conductive elastomeric ink composition |
US4604509A (en) * | 1985-02-01 | 1986-08-05 | Honeywell Inc. | Elastomeric push button return element for providing enhanced tactile feedback |
-
1987
- 1987-02-26 IT IT5306987U patent/IT210475Z2/en active
-
1988
- 1988-02-22 EP EP88301485A patent/EP0280491A3/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE7606008U1 (en) * | 1976-02-28 | 1976-08-26 | Preh, Elektrofeinmechanische Werke Jakob Preh Nachf., 8740 Bad Neustadt | Push button switch |
DE3227457A1 (en) * | 1982-07-22 | 1984-01-26 | Siemens AG, 1000 Berlin und 8000 München | Push-button unit |
US4518833A (en) * | 1983-07-18 | 1985-05-21 | Gates Data Products, Inc. | Conductive elastomeric ink composition |
US4604509A (en) * | 1985-02-01 | 1986-08-05 | Honeywell Inc. | Elastomeric push button return element for providing enhanced tactile feedback |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4952761A (en) * | 1988-03-23 | 1990-08-28 | Preh-Werke Gmbh & Co. Kg | Touch contact switch |
WO2000036706A2 (en) * | 1998-12-17 | 2000-06-22 | Electronics For Imaging, Inc. | Silicon switch |
WO2000036706A3 (en) * | 1998-12-17 | 2000-09-14 | Electronics For Imaging Inc | Silicon switch |
AU754394B2 (en) * | 1998-12-17 | 2002-11-14 | Electronics For Imaging, Inc. | Silicon switch |
Also Published As
Publication number | Publication date |
---|---|
IT8753069V0 (en) | 1987-02-26 |
EP0280491A3 (en) | 1990-01-10 |
IT210475Z2 (en) | 1988-12-30 |
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Effective date: 19900711 |