CA1100165A - Pushbutton switch assembly for telecommunications and other input apparatus - Google Patents
Pushbutton switch assembly for telecommunications and other input apparatusInfo
- Publication number
- CA1100165A CA1100165A CA320,732A CA320732A CA1100165A CA 1100165 A CA1100165 A CA 1100165A CA 320732 A CA320732 A CA 320732A CA 1100165 A CA1100165 A CA 1100165A
- Authority
- CA
- Canada
- Prior art keywords
- circuit
- assembly
- contact
- pushbutton
- porcelain layer
- 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
Links
Classifications
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/14—Structural association of two or more printed circuits
- H05K1/144—Stacked arrangements of planar printed circuit boards
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- 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
- H01H13/7013—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 in which the movable contacts of each switch site or of a row of switch sites are formed in a single plate
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/05—Insulated conductive substrates, e.g. insulated metal substrate
- H05K1/053—Insulated conductive substrates, e.g. insulated metal substrate the metal substrate being covered by an inorganic insulating layer
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Push-Button Switches (AREA)
- Telephone Set Structure (AREA)
- Input From Keyboards Or The Like (AREA)
- Telephonic Communication Services (AREA)
Abstract
Abstract of the Disclosure A push button switch assembly has at least one of the conventional PCB's replaced by a porcelain coated steel plate. The contact circuit for the pushbutton switches is formed on the top surface of the steel plate. It is also possible to replace both PCB's of a conventional switch by forming a second circuit on the under surface of the steel plate, with the electrical devices mounted thereon. Use of the steel plate enables the normal metal mounting plate to be omitted.
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Description
This invention relates to a pushbutton switch assembly for telecommunjcations and other input apparatus, and part~cularly though not exclusively to a pushbutton dial for a telephone.
A particular form of pushbutton assembly comprises a sandwich structure having, starting from the top or outer face, a bezel having a plurality of apertures therethrough, a plurality of pushbuttons, a pushbutton in each aperture; a thin flexible sheet or film~ an assembly of snap action spring switch members in an insulating holding member; a first printed circuit board (PCB) on the top surface of which is the contact circuit with contact positions contacted by contacts on the snap actlon switch members, a further PC~ spaced from the first PCe, the further PCB having on its rear surface a printed circuit and also carrying the various electrical devices of the electrical - circuit for the assembly; and a metal plate or bracket by which the assembly is mounted~
i PCB's are quite expensive items but have become standard items for carrying circuits and for mounting of devices.
A PCB is usually formed of glass fibre reinforced resin. Sheets of the basic~material are manufactured, and then the surface treated to accept and retain a layer of copper. This layer is then usually photolithographically etched to produce the desired circuit pattern. A number of PCB's may be formed 1rom a sheet, . , .
by shearing from the sheet.
The present invention provides for replacing oF
at least the first PCB, carrying the contact circuiit, by a ; porcelain coated steél plate carryiny the contact circuit. A
further feature of the present invention is to use the porcelain coated steel plate to also replace the further PCB by forming ~L~Lg~ ;5 the circuit normally on the further PCB on the rear surface of the porcelain/steel plate and mounting the electrical devices on the porcelain/steel plate. The porcelain coated steel plate is cons;derably cheaper to produce than a glass fibre reinforced resin PCB, the circuits being applied by thick film printing techniques followed by firing.
As an additional feature, the use of a porcelain coated steel plate to replace at least one of the PCB's enables the metal plate or bracket to be dispensed with. The porcelain/steel plate is rig;d and self supporting, whereas the PCB's are flexible and are not strong enough to use without the metal plate or bracket.
The invention will be readily understood by the Following description of certain embodiments, by way of example, in conjunction with the accompanying drawings, in which:-Figure 1 is an exploded perspective view of a pushbutton assembly for a telephone dial, with one PCB replacedi --Figure 2 is a view on the rear face of the remaining PCB, with devices mounted;
F;gure 3 is an exploded perspective view of a pushbutton assembly for a telephone dial with both PCB's replaced;
Figure 4 is an illustrative view on the rear face of the porcelain coated steel member of the assembly in Figure 3, with devices mounted;
Figure 5:is an exploded perspective view of the rear surface of the porcelain coated steel plate, for an i alternative embodiment, and illùstrating circuit menlbers for mounting on khe plate;
Figure ~ is an exploded perspectlve view of a further form of pushbutton assembly for a key strip, as ~or a telephone set or other apparatus.
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A particular form of pushbutton assembly comprises a sandwich structure having, starting from the top or outer face, a bezel having a plurality of apertures therethrough, a plurality of pushbuttons, a pushbutton in each aperture; a thin flexible sheet or film~ an assembly of snap action spring switch members in an insulating holding member; a first printed circuit board (PCB) on the top surface of which is the contact circuit with contact positions contacted by contacts on the snap actlon switch members, a further PC~ spaced from the first PCe, the further PCB having on its rear surface a printed circuit and also carrying the various electrical devices of the electrical - circuit for the assembly; and a metal plate or bracket by which the assembly is mounted~
i PCB's are quite expensive items but have become standard items for carrying circuits and for mounting of devices.
A PCB is usually formed of glass fibre reinforced resin. Sheets of the basic~material are manufactured, and then the surface treated to accept and retain a layer of copper. This layer is then usually photolithographically etched to produce the desired circuit pattern. A number of PCB's may be formed 1rom a sheet, . , .
by shearing from the sheet.
The present invention provides for replacing oF
at least the first PCB, carrying the contact circuiit, by a ; porcelain coated steél plate carryiny the contact circuit. A
further feature of the present invention is to use the porcelain coated steel plate to also replace the further PCB by forming ~L~Lg~ ;5 the circuit normally on the further PCB on the rear surface of the porcelain/steel plate and mounting the electrical devices on the porcelain/steel plate. The porcelain coated steel plate is cons;derably cheaper to produce than a glass fibre reinforced resin PCB, the circuits being applied by thick film printing techniques followed by firing.
As an additional feature, the use of a porcelain coated steel plate to replace at least one of the PCB's enables the metal plate or bracket to be dispensed with. The porcelain/steel plate is rig;d and self supporting, whereas the PCB's are flexible and are not strong enough to use without the metal plate or bracket.
The invention will be readily understood by the Following description of certain embodiments, by way of example, in conjunction with the accompanying drawings, in which:-Figure 1 is an exploded perspective view of a pushbutton assembly for a telephone dial, with one PCB replacedi --Figure 2 is a view on the rear face of the remaining PCB, with devices mounted;
F;gure 3 is an exploded perspective view of a pushbutton assembly for a telephone dial with both PCB's replaced;
Figure 4 is an illustrative view on the rear face of the porcelain coated steel member of the assembly in Figure 3, with devices mounted;
Figure 5:is an exploded perspective view of the rear surface of the porcelain coated steel plate, for an i alternative embodiment, and illùstrating circuit menlbers for mounting on khe plate;
Figure ~ is an exploded perspectlve view of a further form of pushbutton assembly for a key strip, as ~or a telephone set or other apparatus.
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- 2 -As ;llustrated in Figure l~ a pushbutton assembly comprises a molded plastic bezel lO having a plurality of apertures ll arranged in columns and rows. At each side of the bezel lO is a bracket 12, molded integrally with the bezel in the particular example, but can be separate members attached to the bezel.
Brackets 12 provide the attachment~ or mounting, means for the pushbutton assembly.
Extending next to the bezel lO and in contact with its underside is a molded button or key assembly 13. The key assembly 13 ccmprises a flat sheet 14 witK a plurality of keys or buttons 15 molded therewith. The keys are separated from the sheet on three sides3 indicated at 16 but hingedly attached at the fourth ; side - indicated at 17. The keys or buttons 15 extend up through the bezel, a key or button in each aperture 11.
Beneath the button or key assembly 13 is a thin flexible membrane 18 followed by a spring contact assembly l9.
In the particular arrangement illustrated ln Figure l, the spring contact assembly 19 comprises a support and spacer member ~0 having a plurality of apertures 21 therein, arranged 1n columns and rows corresponding to the apertures 11 in the bezel 10.
Supported on the support and spacér member 20 are a number of spring contact members 22. In the particular example the spring contact members 22 are in strips 23 and three such strips 23 are provitied, corresponding to the three columns of buttons or keys 15. A spring contact member 22 is positioned over each aperture 21 and beneath each button or key 15. To retain the strips in position they sit in slight recesses 24 in the member 20 and the ends of the strips flt in s1its cut in a key member 25 at each end.
The spring contact members are conveniently of the form having .. 3 ~, ..
a snap action when the centre portion of a contact member is depressed by pressure on a button or key 15. ~hen a contact member snaps down, contacts 27 move into contact with contact areas of a circuit.
Positioned beneath the support and spacer member 19 is a steel sheet circuit member wh;ch is coated with porcelain, at least on its upper surface, and indicated at 30. On the porcelain surface is formed the switch contact circuit 31, as by thick film techniques, to form a circuit board, the circuit having a plurality of switch positions, each position having a plurality of contact areas. In one such technique, a s~lver-containing frit is thick film printed or deposited on the porcelain/steel sheet which is then fired to form the conducting pattern. A particular way of forming the porcelain coated sheet is by electrodeposition of a frit on the steel sheet, followed by firing. The conductor pattern is then formed and again fired.
Prior to depositing or forming the porcelain coating, the steel sheet is perforated at various positions, as desired, for example as indicated, at 32. These per-foratiol~s may be provided for alignment of the various members, and,'or passage of studs, screws or rivets, or similar devices for fastening members together. To prevent a meniscus building up around these perforations during application of the porcelain to the steel sheet, the peripheral edges of the perforations are coined to give a sl;ghtly chamfered edge.
Beneath the porcelain/steel circuit board 30 is a conventional PCB 35. This is of a normal form, that is being a sheet of resin impregnated glass fibre with a circuit pattern 36 on the top surface. Only small sections of the circuit pattern are illustrated for clarity. Contact pads 37 are l'ormed as part of the circuit pattern and circuit devices are inserted, from the undersurface in Figure 1, and wave soldered to thQ contact pads.
Figure 2, which is a view on the undersurface of the PCB 35, illustrates some of the devices 38 inserted.
Conveniently, in the example illustrated in Figures 1 and 2, small cylindrical protrusions or studs are molded on the undersurface of the bezel 10, and which pass through holes 40 in the key assembly 13, the memb~ane 18, the spring contact assembly support plate 20, perforations 32 in the porcelain/steel circuit board 30 and holes 40 in the PCB 35. An insulati~g layer is formed on the rear or undersurface of the porcelain/steel circuit board 30. This is usually of porcelain as on the front or upper surface but can be of other material. Another alternative is to provide an intermediate member such as a flexible membrane similar to membrane 18. This prevents electrical contac~ between the PCB 35 and the rear surface of the board 30.
After assembly the protrusions or studs can be rivetted over~ as by heating or sonic fusion, to provide a - complete, unitary, assembly for easy handling and assembly into a 20 telephone set or other apparatus. The whole unit is normally mounted by means oF the brackets 12.
Figures 1 and 2 illustrate what can be considered as a first stage, eliminating the metal support member normally provided, the porcelain/steel circuit board 30 providing a rigid member in its place. Also one conventional form of resin impregnated glass fibre PCB has been replaced by t:he porcelain/
steel board. This provides two cost reductions; elimination of the metal support member and a cheaper form oF circuit boarcl.
Figures 3 and 4 illustrate a further stage in which the second PCB, board 35 in Figures 1 and 2, is eliminated. Figure
Brackets 12 provide the attachment~ or mounting, means for the pushbutton assembly.
Extending next to the bezel lO and in contact with its underside is a molded button or key assembly 13. The key assembly 13 ccmprises a flat sheet 14 witK a plurality of keys or buttons 15 molded therewith. The keys are separated from the sheet on three sides3 indicated at 16 but hingedly attached at the fourth ; side - indicated at 17. The keys or buttons 15 extend up through the bezel, a key or button in each aperture 11.
Beneath the button or key assembly 13 is a thin flexible membrane 18 followed by a spring contact assembly l9.
In the particular arrangement illustrated ln Figure l, the spring contact assembly 19 comprises a support and spacer member ~0 having a plurality of apertures 21 therein, arranged 1n columns and rows corresponding to the apertures 11 in the bezel 10.
Supported on the support and spacér member 20 are a number of spring contact members 22. In the particular example the spring contact members 22 are in strips 23 and three such strips 23 are provitied, corresponding to the three columns of buttons or keys 15. A spring contact member 22 is positioned over each aperture 21 and beneath each button or key 15. To retain the strips in position they sit in slight recesses 24 in the member 20 and the ends of the strips flt in s1its cut in a key member 25 at each end.
The spring contact members are conveniently of the form having .. 3 ~, ..
a snap action when the centre portion of a contact member is depressed by pressure on a button or key 15. ~hen a contact member snaps down, contacts 27 move into contact with contact areas of a circuit.
Positioned beneath the support and spacer member 19 is a steel sheet circuit member wh;ch is coated with porcelain, at least on its upper surface, and indicated at 30. On the porcelain surface is formed the switch contact circuit 31, as by thick film techniques, to form a circuit board, the circuit having a plurality of switch positions, each position having a plurality of contact areas. In one such technique, a s~lver-containing frit is thick film printed or deposited on the porcelain/steel sheet which is then fired to form the conducting pattern. A particular way of forming the porcelain coated sheet is by electrodeposition of a frit on the steel sheet, followed by firing. The conductor pattern is then formed and again fired.
Prior to depositing or forming the porcelain coating, the steel sheet is perforated at various positions, as desired, for example as indicated, at 32. These per-foratiol~s may be provided for alignment of the various members, and,'or passage of studs, screws or rivets, or similar devices for fastening members together. To prevent a meniscus building up around these perforations during application of the porcelain to the steel sheet, the peripheral edges of the perforations are coined to give a sl;ghtly chamfered edge.
Beneath the porcelain/steel circuit board 30 is a conventional PCB 35. This is of a normal form, that is being a sheet of resin impregnated glass fibre with a circuit pattern 36 on the top surface. Only small sections of the circuit pattern are illustrated for clarity. Contact pads 37 are l'ormed as part of the circuit pattern and circuit devices are inserted, from the undersurface in Figure 1, and wave soldered to thQ contact pads.
Figure 2, which is a view on the undersurface of the PCB 35, illustrates some of the devices 38 inserted.
Conveniently, in the example illustrated in Figures 1 and 2, small cylindrical protrusions or studs are molded on the undersurface of the bezel 10, and which pass through holes 40 in the key assembly 13, the memb~ane 18, the spring contact assembly support plate 20, perforations 32 in the porcelain/steel circuit board 30 and holes 40 in the PCB 35. An insulati~g layer is formed on the rear or undersurface of the porcelain/steel circuit board 30. This is usually of porcelain as on the front or upper surface but can be of other material. Another alternative is to provide an intermediate member such as a flexible membrane similar to membrane 18. This prevents electrical contac~ between the PCB 35 and the rear surface of the board 30.
After assembly the protrusions or studs can be rivetted over~ as by heating or sonic fusion, to provide a - complete, unitary, assembly for easy handling and assembly into a 20 telephone set or other apparatus. The whole unit is normally mounted by means oF the brackets 12.
Figures 1 and 2 illustrate what can be considered as a first stage, eliminating the metal support member normally provided, the porcelain/steel circuit board 30 providing a rigid member in its place. Also one conventional form of resin impregnated glass fibre PCB has been replaced by t:he porcelain/
steel board. This provides two cost reductions; elimination of the metal support member and a cheaper form oF circuit boarcl.
Figures 3 and 4 illustrate a further stage in which the second PCB, board 35 in Figures 1 and 2, is eliminated. Figure
3 is similar to Figure 1 insofar as the bezel 10, key assembly 13, membrane 18 and spring contact assembly 19 are concerned.
Thus, in Figure 2 there is the bezel 10 with apertures 11 and brackets 12. Below the bezel is the button assembly 13, comprising flat sheet 14, and buttons or keys 15.
Next to the button or key assembly 13 is the membrane 18 and then the spring contact assembly 19 comprising support and spacer member 20 and spring contact members 22. Then follows the porcelain coated steel plate 30.
In this embodiment, as seen in Figure 4, the porcelain coated steel plate 30 has a circuit pattern 50 on the undersurface, the plate having porcelain on both surfaces and the circuit pattern 50 again being formed, ~or example, by thick film techniques, using a silver frit which is then ~ired. For clarity, the circuit pattern 50 is shown dotted but is in face composed of continuous conductors. The various electrical and electronic components, indicated generally at 51, are attached to the circuit pattern, for example by heat bonding or soldering~
Figure 5 illustrates a modl~ication of the assembly of Figures 3 and 4 in which the conventional electrical and electronic components are replaced by hybrid circuit devices 55 and 56 which are connected to the circuit pattern 50, as by heat : bonding or soldering. Such an assembly provides a very compact and economic package which can be used in various telephone sets and similar devlces. The forming of the circuit 50 pattern is conveniently by the same method as is used For forming the circuit 31, that is thick Film deposition of a silver containing ~rit Followed by flring. However other metho~s of forming the circuits ; 31and 50 can be used, For example photolithographic etching.
Interconnection will, o~ course, be required between the two circuit boards 30 and 35 in the embodiment of Figures 1 and 2, and between the two sides of the circuit board 30 in the embod;ments of Figures 3 and 4 and Figure 5.
In the embodiment of Figures 1 and 2, a flexible tape or strip conductor member can extend between I:he board 30 and board 35 for example being connected at one endl to contact areas 60 on circuit board 30 at the other end to contact areas 61 on circuit board 35.
In the embodiment of Figures 3 and 4, and Figure 5, cross-connection or interconnection can be provided by conductor paths through the porcelain/steel circuit board. I'his can be obtained by making holes through the steel plate prior to coating, coating with porcelain and then forming the circuil; patterns.
The porcelain will also coat the interior surfaces of the holes and the circuit pattern can be caused to extend through the holes by applying suctionto the board when the circuit is applied.
Thus, for example, if a silver-containing frit is applied on one surface by thick film deposition, a suction is applied at the other surface to draw the frit through the hole. The same can be done when the circuit material is applied to the ot:her side, to ensure good interconnections. The holes are coinecl prior to coating the steel plate with porcelain.
The circuit board 30, both in Figures 1 and 2, and in Figures 3 and 4~and Figure 5~ can be connected to any further components in the apparatus by a further f'lexible conductor member, as illustrated at 62 in Figure 5.
In addition to the conventional form of pushbutton switch assembly as lllustrated in F~gures 1 to 5, l;he invention is applicable to other ~orms of pushbutton assembly and one example of such altternative forms is illusrated in Figure fi.
.
In Figure 6 sim~lar members or items are provided as in the embodiments of Figures 1 and 2, or 3 and 4, or Figure 5, but the shapes are different. There is an elongate bezel 10 with apertures 11. Beneath the be~el is an elongate molded button assembly 13 with buttons or keys 15, one for each aperture 11. The basic form of the button assembly is as in Figures 1 or 3.
Beneath the button assembly 13 is thin flexible membrane 18 and then spring assembly 19 comprising a strip of contact members 22 on a support and spacer member 20. Then there is an elongate circuit board 30.
In the embodiment of Figure 6, it is assumed that the circuit board 30 is as in Figures 3 and 5, that is porcelain coated steel with one circuit - 31 - on the top surface and the other circuit - circuit pattern 50 of Figure 4 - on the under-surface and the electronic components connected to the circuit on the undersurface. Hybrid devices, as in Figure 6, can be used.
Alternatively, the Pmbodiment of Figure 6 can bb modified to be generally as that of Figures 1 and 2, that is with the circuit board 30 of porcelain/steel and carrying the circuit 31, but with a separate circuit board carrying the second circuit and the associated electronic components.
The pushbutton, or key, assembly of Figure 6 is, .
for example, assembled in a sandwich structure and screws passed through the holes 65 in the various members~ These can also serve as mounting and/or attachment screws for the complete assembly.
~lternatively other mountiny means can be provided, or protrusions molded 4n the undersurface of the bezel 10 passing through suitable holes in the various members, used to assemble the members, as in Figures 1 and 2, or 3 and 4.
The pushbutton, or ~ey, assembly need not be s restricted to a telephone set style as in Figures 1 to 5, or in a strip form as in Figure 6,can be much larger wi~h many rows and columns, or other configurations. A very simple, economic and strong assembly is provided. Assemblies in accordance with the present invent;on can be used for telephones, and other telecommunications apparatus, keyboard terminals, calculators and other input apparatus.
SUPpLEMENTARY DISCLOSURE
Figure 7 is a cross-section throu!~h another form o~ pushbutton dial;
Figure 8 is a plan view of a contact member as used 1n the pushbu-tton dlal of Figure 7;
Figure 9 is a plan vie~ of one face of a porcelain or steel circuit member~ illustrat1ng the circult associated with the contact member of Figure 8.
The form of pushbutton assembly, or dial7 illustrated in Fiyures 7, 8 and 9 has the spring contact assembly 19 of Figures 1 to 6 replaced by a ~lexible electr~cally insulating contact member having a plural;ty of domed areas formed therein. A
suitable material is *Mylar. The assembly comprise$ a circuit member 70, which ;s of porcelain coated steel similar to the circuit member 30 of Figures 1 and 2~ in Figures 3, 4, and 5~ and also in Figure 6, an electrically insulating sheet 71, the flexible contact member 72 and a molded button or key member 73. The flexible contact member has thP
domed areas 74 arranged in columns and rows and t~le concave surfaces of the domed areas are metallized, at 75, the metallized areas connected to circuit conduc~ors 76.
; 20 The concave surfaces of the domed areas face towards the circuit member. On the surface of the circuil; member is a conductor pattern 77. The conductor pattern defines a plurality of contact areas, indicated at 78, a contact area aligned with each domed area 74. The contact areas are interconnected by conductors 79 which extend to an edge of the circuit member, at 80. The conductors 80 provide ~or connection to other electrical and electronlc components. Conductors 81 are also proYided to connect to the conductors 76 o~ the contact member. Electrical connection between conductors 76 and conductors 81 can be made by stapling the assemb1y together, metal staples passing through conductqrs 76 and 81.
:;J' Conductors 81 can also connect to electrical and electronic components? for example mounted on the back surface of the circuit member 72.
The pushbutton or key member 73 has a plurality of cantilevered pushbuttons 85 arranged in columns and rows, the buttons extending from the front or top s1de of the member 73.
The buttons 85 are molded integrally as parts of the member 73 but are separated on three sides and connected by a thin portion 86 which acts as a hinge. Projections 87 extend from the back of each button 85 and are in contact with the domed areas 74.
Pressure on a button 85 pushes down a domed area, which moves into contact with a contact area on the circuit member, with a snap actionO Pins 88 extending from the back of the member 73 pass through alignment holes 89 in the contact member and circuit member.
~i3j~
Thus, in Figure 2 there is the bezel 10 with apertures 11 and brackets 12. Below the bezel is the button assembly 13, comprising flat sheet 14, and buttons or keys 15.
Next to the button or key assembly 13 is the membrane 18 and then the spring contact assembly 19 comprising support and spacer member 20 and spring contact members 22. Then follows the porcelain coated steel plate 30.
In this embodiment, as seen in Figure 4, the porcelain coated steel plate 30 has a circuit pattern 50 on the undersurface, the plate having porcelain on both surfaces and the circuit pattern 50 again being formed, ~or example, by thick film techniques, using a silver frit which is then ~ired. For clarity, the circuit pattern 50 is shown dotted but is in face composed of continuous conductors. The various electrical and electronic components, indicated generally at 51, are attached to the circuit pattern, for example by heat bonding or soldering~
Figure 5 illustrates a modl~ication of the assembly of Figures 3 and 4 in which the conventional electrical and electronic components are replaced by hybrid circuit devices 55 and 56 which are connected to the circuit pattern 50, as by heat : bonding or soldering. Such an assembly provides a very compact and economic package which can be used in various telephone sets and similar devlces. The forming of the circuit 50 pattern is conveniently by the same method as is used For forming the circuit 31, that is thick Film deposition of a silver containing ~rit Followed by flring. However other metho~s of forming the circuits ; 31and 50 can be used, For example photolithographic etching.
Interconnection will, o~ course, be required between the two circuit boards 30 and 35 in the embodiment of Figures 1 and 2, and between the two sides of the circuit board 30 in the embod;ments of Figures 3 and 4 and Figure 5.
In the embodiment of Figures 1 and 2, a flexible tape or strip conductor member can extend between I:he board 30 and board 35 for example being connected at one endl to contact areas 60 on circuit board 30 at the other end to contact areas 61 on circuit board 35.
In the embodiment of Figures 3 and 4, and Figure 5, cross-connection or interconnection can be provided by conductor paths through the porcelain/steel circuit board. I'his can be obtained by making holes through the steel plate prior to coating, coating with porcelain and then forming the circuil; patterns.
The porcelain will also coat the interior surfaces of the holes and the circuit pattern can be caused to extend through the holes by applying suctionto the board when the circuit is applied.
Thus, for example, if a silver-containing frit is applied on one surface by thick film deposition, a suction is applied at the other surface to draw the frit through the hole. The same can be done when the circuit material is applied to the ot:her side, to ensure good interconnections. The holes are coinecl prior to coating the steel plate with porcelain.
The circuit board 30, both in Figures 1 and 2, and in Figures 3 and 4~and Figure 5~ can be connected to any further components in the apparatus by a further f'lexible conductor member, as illustrated at 62 in Figure 5.
In addition to the conventional form of pushbutton switch assembly as lllustrated in F~gures 1 to 5, l;he invention is applicable to other ~orms of pushbutton assembly and one example of such altternative forms is illusrated in Figure fi.
.
In Figure 6 sim~lar members or items are provided as in the embodiments of Figures 1 and 2, or 3 and 4, or Figure 5, but the shapes are different. There is an elongate bezel 10 with apertures 11. Beneath the be~el is an elongate molded button assembly 13 with buttons or keys 15, one for each aperture 11. The basic form of the button assembly is as in Figures 1 or 3.
Beneath the button assembly 13 is thin flexible membrane 18 and then spring assembly 19 comprising a strip of contact members 22 on a support and spacer member 20. Then there is an elongate circuit board 30.
In the embodiment of Figure 6, it is assumed that the circuit board 30 is as in Figures 3 and 5, that is porcelain coated steel with one circuit - 31 - on the top surface and the other circuit - circuit pattern 50 of Figure 4 - on the under-surface and the electronic components connected to the circuit on the undersurface. Hybrid devices, as in Figure 6, can be used.
Alternatively, the Pmbodiment of Figure 6 can bb modified to be generally as that of Figures 1 and 2, that is with the circuit board 30 of porcelain/steel and carrying the circuit 31, but with a separate circuit board carrying the second circuit and the associated electronic components.
The pushbutton, or key, assembly of Figure 6 is, .
for example, assembled in a sandwich structure and screws passed through the holes 65 in the various members~ These can also serve as mounting and/or attachment screws for the complete assembly.
~lternatively other mountiny means can be provided, or protrusions molded 4n the undersurface of the bezel 10 passing through suitable holes in the various members, used to assemble the members, as in Figures 1 and 2, or 3 and 4.
The pushbutton, or ~ey, assembly need not be s restricted to a telephone set style as in Figures 1 to 5, or in a strip form as in Figure 6,can be much larger wi~h many rows and columns, or other configurations. A very simple, economic and strong assembly is provided. Assemblies in accordance with the present invent;on can be used for telephones, and other telecommunications apparatus, keyboard terminals, calculators and other input apparatus.
SUPpLEMENTARY DISCLOSURE
Figure 7 is a cross-section throu!~h another form o~ pushbutton dial;
Figure 8 is a plan view of a contact member as used 1n the pushbu-tton dlal of Figure 7;
Figure 9 is a plan vie~ of one face of a porcelain or steel circuit member~ illustrat1ng the circult associated with the contact member of Figure 8.
The form of pushbutton assembly, or dial7 illustrated in Fiyures 7, 8 and 9 has the spring contact assembly 19 of Figures 1 to 6 replaced by a ~lexible electr~cally insulating contact member having a plural;ty of domed areas formed therein. A
suitable material is *Mylar. The assembly comprise$ a circuit member 70, which ;s of porcelain coated steel similar to the circuit member 30 of Figures 1 and 2~ in Figures 3, 4, and 5~ and also in Figure 6, an electrically insulating sheet 71, the flexible contact member 72 and a molded button or key member 73. The flexible contact member has thP
domed areas 74 arranged in columns and rows and t~le concave surfaces of the domed areas are metallized, at 75, the metallized areas connected to circuit conduc~ors 76.
; 20 The concave surfaces of the domed areas face towards the circuit member. On the surface of the circuil; member is a conductor pattern 77. The conductor pattern defines a plurality of contact areas, indicated at 78, a contact area aligned with each domed area 74. The contact areas are interconnected by conductors 79 which extend to an edge of the circuit member, at 80. The conductors 80 provide ~or connection to other electrical and electronlc components. Conductors 81 are also proYided to connect to the conductors 76 o~ the contact member. Electrical connection between conductors 76 and conductors 81 can be made by stapling the assemb1y together, metal staples passing through conductqrs 76 and 81.
:;J' Conductors 81 can also connect to electrical and electronic components? for example mounted on the back surface of the circuit member 72.
The pushbutton or key member 73 has a plurality of cantilevered pushbuttons 85 arranged in columns and rows, the buttons extending from the front or top s1de of the member 73.
The buttons 85 are molded integrally as parts of the member 73 but are separated on three sides and connected by a thin portion 86 which acts as a hinge. Projections 87 extend from the back of each button 85 and are in contact with the domed areas 74.
Pressure on a button 85 pushes down a domed area, which moves into contact with a contact area on the circuit member, with a snap actionO Pins 88 extending from the back of the member 73 pass through alignment holes 89 in the contact member and circuit member.
~i3j~
Claims (25)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-
1. A pushbutton switch assembly comprising:
a steel sheet member having upper and lower surfaces;
a porcelain layer on at least said upper surface;
a contact circuit on said porcelain layer, said circuit comprising a thick film pattern of electrically conductive material and including a plurality of switch positions, each position including a plurality of contact areas, a spring contact assembly mounted on said upper surface and including a plurality of contact members, each member aligned with a switch position of said contact circuit;
each contact member including a plurality of contacts, a contact for each contact area at the related switch position, a pushbutton assembly mounted on said spring contact assembly, said pushbutton assembly including a plurality of pushbuttons, a pushbutton for each contact area and switch position;
circuit means associated with said lower surface of said steel sheet circuit member, said circuit means comprising an electrical circuit pattern and electrical device; connected to said circuit pattern.
a steel sheet member having upper and lower surfaces;
a porcelain layer on at least said upper surface;
a contact circuit on said porcelain layer, said circuit comprising a thick film pattern of electrically conductive material and including a plurality of switch positions, each position including a plurality of contact areas, a spring contact assembly mounted on said upper surface and including a plurality of contact members, each member aligned with a switch position of said contact circuit;
each contact member including a plurality of contacts, a contact for each contact area at the related switch position, a pushbutton assembly mounted on said spring contact assembly, said pushbutton assembly including a plurality of pushbuttons, a pushbutton for each contact area and switch position;
circuit means associated with said lower surface of said steel sheet circuit member, said circuit means comprising an electrical circuit pattern and electrical device; connected to said circuit pattern.
2. An assembly as claimed in claim 1, including a bezel mounted on said pushbutton assembly and including a plurality of apertures therethrough, a pushbutton positioned in each aperture and extending through said bezel.
3. An assembly as claimed in claim 2, including means on said bezel for mounting the pushbutton switch assembly.
4. An assembly as claimed in claim 1 each contact member having a snap action for rapid making and breaking of contact between said contacts and said contact areas.
5. An assembly as claimed in claim 1, said circuit means comprising:
a printed circuit board mounted on said lower surface of said steel sheet circuit member and having upper and lower surfaces;
said circuit pattern on one of said surfaces.
a printed circuit board mounted on said lower surface of said steel sheet circuit member and having upper and lower surfaces;
said circuit pattern on one of said surfaces.
6. An assembly as claimed in claim 5, said circuit pattern on said upper surface of said printed circuit board and said electrical devices mounted on said lower surface of said printed circuit board and connected to said circuit pattern through said printed circuit board.
7. An assembly as claimed in claim 6, said electrical devices comprising hybrid circuit devices.
8. An assembly as claimed in claim 1, said steel sheet circuit member having a porcelain layer on said lower surface, said circuit means comprising said electrical circuit pattern on said porcelain layer on said lower surface and electrical devices mounted on and connected to said circuit pattern.
9. An assembly as claimed in claim 8, said electrical devices comprising hybrid circuit devices.
10. An assembly as claimed in claim 1, said pushbuttons arranged in columns and rows.
11. An assembly as claimed in claim 10, said assembly forming a telephone pushbutton dial.
12. An assembly as claimed in claim 1, said pushbutton arranged in a single column or row.
13. For use in a pushbutton switch assembly, a circuit member comprising:
a steel sheet member having upper and lower surfaces, a porcelain layer on at least one of said surfaces;
a contact circuit on said porcelain layer, said contact circuit comprising a thick film pattern of electrically conductive material.
a steel sheet member having upper and lower surfaces, a porcelain layer on at least one of said surfaces;
a contact circuit on said porcelain layer, said contact circuit comprising a thick film pattern of electrically conductive material.
14. A circuit member as claimed in claim 13, including a porcelain layer on both surfaces of said steel sheet member.
15. A circuit member as claimed in claim 14, including an electrical circuit on the porcelain layer on the other surface of said steel sheet member, said electrical circuit comprising a thick-film pattern of electrically conductive material in the form of a fused metal containing frit.
16. A circuit member as claimed in claim 13, said electrically conductive material being in the form of a fused metal containing frit.
17. A pushbutton switch assembly comprising:-a steel sheet member having upper and lower surfaces;
a porcelain layer on at least said upper surface;
a contact circuit on said porcelain layer, said circuit comprising a thick film pattern of electrically conductive material and including a plurality of switch positions, each position including at least one contact area;
a contact member extending over said contact circuit, said contact member including a plurality of a deformable contact portions, a contact portion aligned with each said switch position.
a porcelain layer on at least said upper surface;
a contact circuit on said porcelain layer, said circuit comprising a thick film pattern of electrically conductive material and including a plurality of switch positions, each position including at least one contact area;
a contact member extending over said contact circuit, said contact member including a plurality of a deformable contact portions, a contact portion aligned with each said switch position.
18. An assembly as claimed in claim 17, including a pushbutton assembly mounted on said contact member, said pushbutton assembly including a plurality of pushbuttons, a pushbutton for each deformable contact portion and switch position.
19. An assembly as claimed in claim 17, each deformable contact portion having a snap action for rapid making and breaking of contact between said contact portion and the related contact area.
20. An assembly as claimed in claim 17, including a porcelain layer on said lower surface and an electrical circuit on said porcelain layer on said lower surface.
21. An assembly as claimed in claim 17, said contact circuit comprising a thick film pattern of electrically conductive material in the form of a fused metal containing frit.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
22. An assembly as claimed in claim 18, the contact member being of flexible non-conducting material and having a plurality of domed areas extending towards the pushbuttons, a domed area aligned with each pushbutton and a related switch position on the contact circuit, an electrically conductive layer on a concave surface of each domed area, electrical conductors on the flexible contact member connected to the conductive layers, such that depression of a pushbutton deforms a domed area into contact with the contact area at the related switch positions on the contact circuit.
23. An assembly as claimed in claim 22, said domed areas having a snap-action on deformation.
24. An assembly as claimed in claim 22, including a porcelain layer on said lower surface and an electrical circuit on said porcelain layer on said lower surface.
25. An assembly as claimed in claim 22, said contact circuit comprising a thick film pattern of electrically conductive material in the form of a fused metal containing frit.
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA320,732A CA1100165A (en) | 1979-02-02 | 1979-02-02 | Pushbutton switch assembly for telecommunications and other input apparatus |
| NO80800228A NO153197C (en) | 1979-02-02 | 1980-01-30 | PRESSURE BUTTON SWITCH UNIT FOR TELECOMMUNICATIONS O.L. |
| GB8003336A GB2043352B (en) | 1979-02-02 | 1980-01-31 | Pushbutton switch assembly for telecommunications and other input apparatus |
| FR8002091A FR2448218A1 (en) | 1979-02-02 | 1980-01-31 | PUSH BUTTON SWITCHING ASSEMBLY FOR TELECOMMUNICATIONS AND OTHER INPUT DEVICES |
| SE8000792A SE440567B (en) | 1979-02-02 | 1980-01-31 | Pushbutton stellare |
| IT19650/80A IT1193911B (en) | 1979-02-02 | 1980-02-01 | BUTTON SWITCHING COMPLEX FOR TELECOMMUNICATION EQUIPMENT AND OTHER DATA INTRODUCTION APPARATUS |
| DE19803003715 DE3003715A1 (en) | 1979-02-02 | 1980-02-01 | PUSH BUTTON ARRANGEMENT |
| JP1013280A JPS55124914A (en) | 1979-02-02 | 1980-02-01 | Electric communication device and pushhbutton switch assembly for other input device |
| BE0/199230A BE881507A (en) | 1979-02-02 | 1980-02-01 | PUSH BUTTON SWITCHING ASSEMBLY FOR TELECOMMUNICATIONS AND OTHER INPUT DEVICES |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA320,732A CA1100165A (en) | 1979-02-02 | 1979-02-02 | Pushbutton switch assembly for telecommunications and other input apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1100165A true CA1100165A (en) | 1981-04-28 |
Family
ID=4113441
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA320,732A Expired CA1100165A (en) | 1979-02-02 | 1979-02-02 | Pushbutton switch assembly for telecommunications and other input apparatus |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS55124914A (en) |
| BE (1) | BE881507A (en) |
| CA (1) | CA1100165A (en) |
| DE (1) | DE3003715A1 (en) |
| FR (1) | FR2448218A1 (en) |
| GB (1) | GB2043352B (en) |
| IT (1) | IT1193911B (en) |
| NO (1) | NO153197C (en) |
| SE (1) | SE440567B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3130159A1 (en) * | 1981-07-30 | 1983-02-17 | Preh, Elektrofeinmechanische Werke, Jakob Preh, Nachf. Gmbh & Co, 8740 Bad Neustadt | "METHOD FOR PRODUCING BOARD" |
| JPH049706Y2 (en) * | 1984-09-13 | 1992-03-11 | ||
| GB2250380B (en) * | 1990-11-27 | 1995-01-04 | Ist Lab Ltd | Switch apparatus |
| GB2308499B (en) * | 1995-12-22 | 2000-03-15 | Nokia Mobile Phones Ltd | A contact membrane for a keypad assembly |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB990023A (en) * | 1961-03-13 | 1965-04-22 | Ass Elect Ind | Improvements relating to printed electrical circults |
| US3843851A (en) * | 1971-09-17 | 1974-10-22 | Canon Kk | A rigid compact electronic computer |
| US3898421A (en) * | 1972-08-18 | 1975-08-05 | Matsushita Electric Ind Co Ltd | Push button switch with elastic conductive sheet |
| AR204336A1 (en) * | 1973-12-17 | 1975-12-22 | Texas Instruments Inc | KEYBOARD PIECE |
| CA1019374A (en) * | 1975-04-16 | 1977-10-18 | Cornelis W. Reedyk | Multi-contact push-button switch |
| CA1034175A (en) * | 1975-04-16 | 1978-07-04 | Pak-Jong Chu | Multi-contact push-button switch |
| US3969600A (en) * | 1975-06-11 | 1976-07-13 | Burroughs Corporation | Tactile feedback keyboard switch assembly and actuator |
-
1979
- 1979-02-02 CA CA320,732A patent/CA1100165A/en not_active Expired
-
1980
- 1980-01-30 NO NO80800228A patent/NO153197C/en unknown
- 1980-01-31 FR FR8002091A patent/FR2448218A1/en active Granted
- 1980-01-31 GB GB8003336A patent/GB2043352B/en not_active Expired
- 1980-01-31 SE SE8000792A patent/SE440567B/en not_active IP Right Cessation
- 1980-02-01 IT IT19650/80A patent/IT1193911B/en active
- 1980-02-01 DE DE19803003715 patent/DE3003715A1/en not_active Withdrawn
- 1980-02-01 JP JP1013280A patent/JPS55124914A/en active Pending
- 1980-02-01 BE BE0/199230A patent/BE881507A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| NO153197C (en) | 1986-01-29 |
| FR2448218A1 (en) | 1980-08-29 |
| SE8000792L (en) | 1980-08-03 |
| FR2448218B1 (en) | 1984-02-24 |
| IT1193911B (en) | 1988-08-31 |
| GB2043352B (en) | 1983-04-13 |
| DE3003715A1 (en) | 1980-08-14 |
| BE881507A (en) | 1980-08-01 |
| NO153197B (en) | 1985-10-21 |
| SE440567B (en) | 1985-08-05 |
| JPS55124914A (en) | 1980-09-26 |
| GB2043352A (en) | 1980-10-01 |
| IT8019650A0 (en) | 1980-02-01 |
| NO800228L (en) | 1980-08-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |