US3870840A - Switch pushbutton-type digit keyboard switch with leaf spring contract and actuator biasing means on common conductive frame - Google Patents
Switch pushbutton-type digit keyboard switch with leaf spring contract and actuator biasing means on common conductive frame Download PDFInfo
- Publication number
- US3870840A US3870840A US406220A US40622073A US3870840A US 3870840 A US3870840 A US 3870840A US 406220 A US406220 A US 406220A US 40622073 A US40622073 A US 40622073A US 3870840 A US3870840 A US 3870840A
- Authority
- US
- United States
- Prior art keywords
- prong
- pushbutton
- board
- keyboard switch
- support
- 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 - Lifetime
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/02—Constructional features of telephone sets
- H04M1/23—Construction or mounting of dials or of equivalent devices; Means for facilitating the use thereof
Definitions
- An array of pushbuttons e.g., as used for digit selection in a telescommunication system, are recived in apertures of a cylindrical housing above a printedcircuit board.
- Each contact has a relatively broad prong with an upbent extremity, bear ing from below under pressure upon a lug of the associated pushbutton, and a pair of narrow parallel tongues bent down with reference to that prong and terminating in hooked extremities which engage a corresponding contact area on the printed-circuit board upon depression of the contact by the pushbutton.
- Conventional keyboard switches of this description generally employ two sets of springs, Le, a set of restoring springs tending to hold the pushbuttons in their unactuated or elevated positions and a set of leaf-spring contacts which act as circuit closers upon the depression of the associated pushbuttons against the force of their respective restoring springs. It is usually also necessary to provide fixed abutments for limiting the depression strokes of the pushbuttons.
- the general object of our present invention is to provide a simplified keyboard construction which eliminates the need for two separate spring sets as described above.
- a more particular object is to provide a set of elements combining the functions of restoring and contact springs as well as of the abutments referred to.
- a keyboard according to our invention comprises a printed-circuitboard on a support, e.g., on the bottom of a substantially cylindrical housing, one of whose faces (referred to hereinafter as the upper face) is provided with a multiplicity of contact areas which are respectively included in the circuits to be selectively closed.
- An array of resilient contact elements are interposed between this board and respective pushbuttons movably mounted on the support, e.g., in apertures formed in the top of the housing, each of these contact elements being a leaf spring with a fixed end and a movable end.
- each leaf spring is split into an upbent prong and one or more relatively downwardly bent tongues, the prong bearing under pressure (i.e., with a certain bias) upon the overlying pushbutton; the tongue or tongues are normally spaced from the corresponding contact area but are engageable therewith upon depression of the pushbutton to displace the prong toward the printed-circuit board (PCB).
- PCB printed-circuit board
- the leaf springs are integral with a conductive frame in the shape of a disk overlying the PCB, the disk being partly cut away around the leaf springs in the region of the contact areas in order to prevent possible short circuits.
- the prong engaging the pushbutton should be considerably wider than any of the associated tongues acting as circuit closers, its width preferably exceeding the combined width of the tongues.
- any depression of a pushbutton against the biasing force of the contacting prong entrains the associated tongue or tongues into engagement of the corresponding contact area during the downstroke; with the aforedescribed relative dimensioning of the tongues and the prong, the reaction force of the tongues is small compared with the biasing force exerted by the prong upon the descending pushbutton and may be chosen independently of that reaction force to exert the right contact pressure for closure of the circuit.
- each pushbutton is provided with a lug engaging an angled tip of the coacting prong in line with the working extremity of the adjoining tongue, this tip being pressed flat against the PCB in a fully depressed position of the pushbutton with the leaf spring curving away from the board surface between its fixed end and the tip.
- the tip of the prong thus acts as a positive stop preventing any further depression of the pushbutton and'limiting the deformation of the leaf spring as well as the contact pressure exerted by the tongue extremity upon the printed face.
- FIG. 1 is an exploded perspective view (with parts broken away) of a keyboard switch according to our invention
- FIG. 2 is a top plan view of the keyboard switch of FIG. 1;
- FIG. 3 is a cross-sectional view taken on the line III- -III of FIG. 2;
- FIG. 4 is a plan view of a spring assembly forming part of the keyboard switch of FIGS. 1 3.
- the keyboard switch shown in the drawing comprises a cylindrical housing 1 of insulating material provided at its top with a multiplicity (here 12) of generally rectangular apertures 26, surrounded by tubular bosses 25, accommodating respective pushbuttons 2.
- the pushbuttons are of upwardly tapering configuration and are provided at their lower ends with shoulders 12 limiting their upward displacement.
- Housing 1 is closed at its bottom by a lid 10, which may be metallic, whose raised rim 10 supports a printed-circuit board 8 seated in a rabbet 16 at the lower edge of the inner housing wall.
- a disk 3 of resilient metal of good electrical conductivity, such as beryllium copper, is clamped in position between the rabbet l6 and the board 8.
- the assembly is completed by nonillustrated screws traversing holes 11 in the lid 10 and engaging inner threads of several posts 13 which integrally depend from the top of the housing and having reduced lower extremities passing through holes 14 and 14 in board 8 and disk 3.
- the central part of disk 3 is cut away or stamped out to expose an underlying portion of the upper face of board 8 provided with a multiplicity of contact areas 7, one for each pushbutton 2. Extensions 7 of these contact areas are connected to leads passing through the dielectric board 8 and continuing on its underside torespective loads not shown; voltage to energize these loads is applied to the rim of disk 3 through a nonillustrated connection.
- each spring 21 comprises a relatively wide I prong 4 and a pair of substantially narrower tongues 5 parallel thereto, the tongues and the prong branching off the body of the spring along a transverse line indicated at 22 in FIG. 4. This body decreases in width from the line 22 to its end 23 at which it is fixed to the remaining stationary disk structure. As best seen in FIG.
- the spring body is bent upwardly (out of the plane of the disk) at the end 23 and arches past the branching point to a line,24 near the free end of the spring at which the prong 4 is upwardly angled to form a flat tip 20.
- This tip bears from below upon a lug 9 on the underside of theassociated pushbutton 2 which is thereby biased into its top position in which its shoulder 12 abuts the underside of the boss 25 guiding this pushbutton.
- FIG. 3 also clearly shows that the free extremity of each tongue 5 is formed into a generally V-shaped hook 6 lying at a level below that of tip 20 in the unoperated (open-circuit) position of the pushbutton; in this position the tongues 5 diverge downwardly from the prong 4 so that hooks 6 engage the associated contact area 7 early in the downstroke of the actuated pushbutton.
- the final contact pressure between hooks 6 and area 7 is constant and independent of the pressure exerted by the finger of the user upon the associated pushbutton.
- the width of prong 4 exceeds the combined width of tongues 5 (naturally, the number ofthese tongues is not limited to two) and is nearly equal to the'width of the spring body at its junction 23 with the framework of disk 3.
- the tongues 5 are laterally offset from this junction 2'3whereas the tip 20 is in line with that junction so that its engagement with the surface of PCB 8 does not cause any twisting of the leaf spring 21 about its longitudinal axis. Owing to the absence of such-twisting, the tongues 5 act with equal pressures upon the associated contact area 7.
- its body 27 is advantageously provided with a cutout 19 in the form of a longitudinal slot terminating in the vicinity of the line 22, the width of this slot increasing progressively in the direction toward that line.
- disk 3 is integrally formed with a pair of tangs l8 receivable in holes 17 of PCB 8. Holes 15 (only one shown) in lid 10 accommodate nonillustrated conductors serving as extensions of the leads which traverse the board 8.
- a keyboard switch for the selective closure of a multiplicity of circuits comprising:
- each of said contact elements being provided with v a fixed end and a movable endrsaid movable end being split into an upbent prong bearing under pressure upon the associated pushbutton and-relatively downwardly bent tongue means alongside said prong normally spaced from the corresponding contact area but engageable therewith upon displacement of said prong toward said board by depression of said associated pushbutton.
- a keyboard switch as defined in claim 1 wherein said support comprises a housing with apertures in its top for the guidance of said pushbuttons and with a detachable lid at its bottom carrying said board.
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Push-Button Switches (AREA)
- Telephone Set Structure (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT30518/72A IT972200B (it) | 1972-10-16 | 1972-10-16 | Tastiera per un dispositivo di se lezione per sistemi di telecomuni cazioni |
Publications (1)
Publication Number | Publication Date |
---|---|
US3870840A true US3870840A (en) | 1975-03-11 |
Family
ID=11229895
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US406220A Expired - Lifetime US3870840A (en) | 1972-10-16 | 1973-10-15 | Switch pushbutton-type digit keyboard switch with leaf spring contract and actuator biasing means on common conductive frame |
Country Status (13)
Cited By (30)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3971902A (en) * | 1975-03-21 | 1976-07-27 | Amp Incorporated | Keyboard switch assembly having one piece plural pushbutton actuator and resilient mounting structure for plural cantilever beam contacts |
US3996429A (en) * | 1975-04-18 | 1976-12-07 | Northern Electric Company Limited | Multi-contact push-button switch having plural prestressed contact members designed to provide plural circuit simultaneous switching inputs |
US3996430A (en) * | 1974-05-07 | 1976-12-07 | Preh Elektrofeinmechanische Werke | Keyboard switch assembly having multilayer printed circuit structure |
US3999025A (en) * | 1975-07-30 | 1976-12-21 | Burroughs Corporation | Low profile tactile feedback keyboard switch assembly |
US4024368A (en) * | 1975-10-02 | 1977-05-17 | Litton Systems, Inc. | Switch assembly having selective actuation sensitivity |
US4029916A (en) * | 1975-04-18 | 1977-06-14 | Northern Electric Company Limited | Multi-contact push-button switch and plural embodiment for keyboard switch assembly |
US4032728A (en) * | 1974-12-20 | 1977-06-28 | Olympia Werke Ag | Push button switch |
US4062181A (en) * | 1976-01-16 | 1977-12-13 | Hughes Aircraft Company | Combination watch-calculator construction |
US4063054A (en) * | 1974-11-22 | 1977-12-13 | Canon Kabushiki Kaisha | Key switch |
US4071715A (en) * | 1975-12-17 | 1978-01-31 | Societe Des Telephones Picart Lebas | Push-button switch for a multifrequency dialling telephone set |
US4081513A (en) * | 1974-12-11 | 1978-03-28 | The United States of America as represented by Administrator U.S. Environmental Protection Agency | Disposal of sulfur oxide pollutant-containing gas |
US4099037A (en) * | 1976-06-21 | 1978-07-04 | National Semiconductor Corporation | Key board switch assembly having canti-levered leaf spring contact assembly on common conductive frame |
US4120044A (en) * | 1976-09-16 | 1978-10-10 | Rca Corporation | Data encoding keyboard |
US4146767A (en) * | 1976-09-10 | 1979-03-27 | Alps Electric Co., Ltd. | Push-button switch |
US4150272A (en) * | 1976-12-21 | 1979-04-17 | Telefonaktiebolaget L M Ericsson | Push button contact mechanism for use at printed circuit cards |
US4192976A (en) * | 1978-12-29 | 1980-03-11 | Gte Automatic Electric Laboratories Incorporated | Pushbutton call transmitter |
US4251697A (en) * | 1978-01-27 | 1981-02-17 | Amper, S.A. | Keypad for telephones |
US4371760A (en) * | 1981-03-05 | 1983-02-01 | Apple Computer, Inc. | Keyboard switch having combined actuator and jumper contact structure |
US4386240A (en) * | 1979-12-15 | 1983-05-31 | International Standard Electric Corporation | Push-button unit for telephone sets |
US4415983A (en) * | 1980-03-04 | 1983-11-15 | Texas Instruments Incorporated | System and method for aligning a display device |
US4496929A (en) * | 1983-04-11 | 1985-01-29 | Mcgraw-Edison Company | Low current indicating fuse |
US4707578A (en) * | 1985-02-14 | 1987-11-17 | Triumph-Adler A.G. | Key operated printed circuit switch |
US5422447A (en) * | 1992-09-01 | 1995-06-06 | Key Tronic Corporation | Keyboard with full-travel, self-leveling keyswitches and return mechanism keyswitch |
US6350970B1 (en) * | 1999-05-07 | 2002-02-26 | Salton, Inc. | Appliance switching mechanism and method |
US20020025837A1 (en) * | 2000-05-22 | 2002-02-28 | Levy David H. | Input devices and their use |
US20030160712A1 (en) * | 2002-02-27 | 2003-08-28 | Digit Wireless, Llc, A Delaware Corporation | Keypad construction |
US20040031673A1 (en) * | 2002-05-23 | 2004-02-19 | Levy David H. | Keypads and key switches |
US20060250370A1 (en) * | 2005-05-03 | 2006-11-09 | Ya-Ping Ko | Method and related apparatus for inputting characters |
US20090038919A1 (en) * | 2007-08-10 | 2009-02-12 | Canon Kabushiki Kaisha | Electronic apparatus |
US20220157153A1 (en) * | 2019-03-18 | 2022-05-19 | Minimax Viking Research & Development Gmbh | Support component of a housing of a hazard alert centre and a hazard alert centre, preferably an intruder alert, fire alarm and/or extinguishing control centre |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5355412U (US08080257-20111220-C00005.png) * | 1976-10-12 | 1978-05-12 | ||
DE102017114189A1 (de) * | 2017-06-27 | 2018-12-27 | Cherry Gmbh | Trägerelement für eine Tastatur, Tastatur und Verfahren zum Herstellen einer Tastatur |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3109071A (en) * | 1959-12-18 | 1963-10-29 | Bell Telephone Labor Inc | Telephone call transmitter |
US3131265A (en) * | 1960-12-30 | 1964-04-28 | Gen Motors Corp | Electric switch having a plurality of pivotally mounted switch actuators |
US3600528A (en) * | 1969-09-25 | 1971-08-17 | Lematex Corp | Multiple switch construction |
US3786205A (en) * | 1972-05-11 | 1974-01-15 | Becton Dickinson Co | Keyboard switch assembly with movable, multi-contact means and associated swinger portions |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1168496B (de) * | 1963-02-01 | 1964-04-23 | Siemens Ag | Tastengesteuerte Einrichtung fuer elektrische Kodierung fuer Fernmeldeanlagen, insbesondere Waehleinrichtung fuer kodierte Wahl |
DE1562149A1 (de) * | 1968-01-31 | 1970-03-12 | Telefonbau & Normalzeit Gmbh | Waehltastatur fuer Fernmeldeanlagen |
DE1807559A1 (de) * | 1968-11-07 | 1970-05-27 | Standard Elek K Lorenz Ag | Tastensatz fuer Fernmeldeanlagen |
DE2120121A1 (de) * | 1970-06-12 | 1971-12-30 | Inst Fuer Nachrichtentechnik | Wahltastatur zum Aussenden von Codesignalen für Endgeräte in Informationsverarbeitungsanlagen, insbesondere für Fernsprechapparate in Fernsprechanlagen |
FR2152115A5 (US08080257-20111220-C00005.png) * | 1971-09-06 | 1973-04-20 | Olivetti & Co Spa |
-
1972
- 1972-10-16 IT IT30518/72A patent/IT972200B/it active
-
1973
- 1973-09-05 ZA ZA737102A patent/ZA737102B/xx unknown
- 1973-09-12 ES ES418704A patent/ES418704A1/es not_active Expired
- 1973-09-24 BR BR7405/73A patent/BR7307405D0/pt unknown
- 1973-09-26 CH CH1380973A patent/CH570029A5/xx not_active IP Right Cessation
- 1973-10-04 FR FR7335556A patent/FR2203238B1/fr not_active Expired
- 1973-10-10 NL NL7313976A patent/NL7313976A/xx not_active Application Discontinuation
- 1973-10-12 DE DE2351367A patent/DE2351367C2/de not_active Expired
- 1973-10-12 GB GB4778673A patent/GB1433184A/en not_active Expired
- 1973-10-12 BE BE136625A patent/BE806007A/xx unknown
- 1973-10-13 JP JP11527573A patent/JPS5619146B2/ja not_active Expired
- 1973-10-15 CA CA183,320A patent/CA994021A/en not_active Expired
- 1973-10-15 US US406220A patent/US3870840A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3109071A (en) * | 1959-12-18 | 1963-10-29 | Bell Telephone Labor Inc | Telephone call transmitter |
US3131265A (en) * | 1960-12-30 | 1964-04-28 | Gen Motors Corp | Electric switch having a plurality of pivotally mounted switch actuators |
US3600528A (en) * | 1969-09-25 | 1971-08-17 | Lematex Corp | Multiple switch construction |
US3786205A (en) * | 1972-05-11 | 1974-01-15 | Becton Dickinson Co | Keyboard switch assembly with movable, multi-contact means and associated swinger portions |
Cited By (38)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3996430A (en) * | 1974-05-07 | 1976-12-07 | Preh Elektrofeinmechanische Werke | Keyboard switch assembly having multilayer printed circuit structure |
US4063054A (en) * | 1974-11-22 | 1977-12-13 | Canon Kabushiki Kaisha | Key switch |
US4081513A (en) * | 1974-12-11 | 1978-03-28 | The United States of America as represented by Administrator U.S. Environmental Protection Agency | Disposal of sulfur oxide pollutant-containing gas |
US4032728A (en) * | 1974-12-20 | 1977-06-28 | Olympia Werke Ag | Push button switch |
US3971902A (en) * | 1975-03-21 | 1976-07-27 | Amp Incorporated | Keyboard switch assembly having one piece plural pushbutton actuator and resilient mounting structure for plural cantilever beam contacts |
US3996429A (en) * | 1975-04-18 | 1976-12-07 | Northern Electric Company Limited | Multi-contact push-button switch having plural prestressed contact members designed to provide plural circuit simultaneous switching inputs |
US4029916A (en) * | 1975-04-18 | 1977-06-14 | Northern Electric Company Limited | Multi-contact push-button switch and plural embodiment for keyboard switch assembly |
US3999025A (en) * | 1975-07-30 | 1976-12-21 | Burroughs Corporation | Low profile tactile feedback keyboard switch assembly |
US4024368A (en) * | 1975-10-02 | 1977-05-17 | Litton Systems, Inc. | Switch assembly having selective actuation sensitivity |
US4071715A (en) * | 1975-12-17 | 1978-01-31 | Societe Des Telephones Picart Lebas | Push-button switch for a multifrequency dialling telephone set |
US4062181A (en) * | 1976-01-16 | 1977-12-13 | Hughes Aircraft Company | Combination watch-calculator construction |
US4099037A (en) * | 1976-06-21 | 1978-07-04 | National Semiconductor Corporation | Key board switch assembly having canti-levered leaf spring contact assembly on common conductive frame |
US4146767A (en) * | 1976-09-10 | 1979-03-27 | Alps Electric Co., Ltd. | Push-button switch |
US4120044A (en) * | 1976-09-16 | 1978-10-10 | Rca Corporation | Data encoding keyboard |
US4150272A (en) * | 1976-12-21 | 1979-04-17 | Telefonaktiebolaget L M Ericsson | Push button contact mechanism for use at printed circuit cards |
US4251697A (en) * | 1978-01-27 | 1981-02-17 | Amper, S.A. | Keypad for telephones |
US4192976A (en) * | 1978-12-29 | 1980-03-11 | Gte Automatic Electric Laboratories Incorporated | Pushbutton call transmitter |
US4386240A (en) * | 1979-12-15 | 1983-05-31 | International Standard Electric Corporation | Push-button unit for telephone sets |
US4415983A (en) * | 1980-03-04 | 1983-11-15 | Texas Instruments Incorporated | System and method for aligning a display device |
US4371760A (en) * | 1981-03-05 | 1983-02-01 | Apple Computer, Inc. | Keyboard switch having combined actuator and jumper contact structure |
US4496929A (en) * | 1983-04-11 | 1985-01-29 | Mcgraw-Edison Company | Low current indicating fuse |
US4707578A (en) * | 1985-02-14 | 1987-11-17 | Triumph-Adler A.G. | Key operated printed circuit switch |
US5422447A (en) * | 1992-09-01 | 1995-06-06 | Key Tronic Corporation | Keyboard with full-travel, self-leveling keyswitches and return mechanism keyswitch |
WO1995028727A1 (en) * | 1994-04-14 | 1995-10-26 | Key Tronic Corporation | Improved keyboard with full-travel, self-leveling keyswitches and return mechanism keyswitch |
US6350970B1 (en) * | 1999-05-07 | 2002-02-26 | Salton, Inc. | Appliance switching mechanism and method |
US20020025837A1 (en) * | 2000-05-22 | 2002-02-28 | Levy David H. | Input devices and their use |
US8094806B2 (en) | 2000-05-22 | 2012-01-10 | Nuance Communications, Inc. | Input devices and their use |
US20070256915A1 (en) * | 2000-05-22 | 2007-11-08 | Digit Wireless, Inc. | Input Devices And Their Use |
US7391861B2 (en) | 2000-05-22 | 2008-06-24 | Digit Wireless, Llc | Input devices and their use |
US20030160712A1 (en) * | 2002-02-27 | 2003-08-28 | Digit Wireless, Llc, A Delaware Corporation | Keypad construction |
US7126498B2 (en) | 2002-02-27 | 2006-10-24 | Digit Wireless, Llc | Keypad construction |
US6911608B2 (en) | 2002-05-23 | 2005-06-28 | Digit Wireless, Llc | Keypads and key switches |
US20040031673A1 (en) * | 2002-05-23 | 2004-02-19 | Levy David H. | Keypads and key switches |
US20060250370A1 (en) * | 2005-05-03 | 2006-11-09 | Ya-Ping Ko | Method and related apparatus for inputting characters |
US20090038919A1 (en) * | 2007-08-10 | 2009-02-12 | Canon Kabushiki Kaisha | Electronic apparatus |
US7875817B2 (en) * | 2007-08-10 | 2011-01-25 | Canon Kabushiki Kaisha | Electronic apparatus |
US20220157153A1 (en) * | 2019-03-18 | 2022-05-19 | Minimax Viking Research & Development Gmbh | Support component of a housing of a hazard alert centre and a hazard alert centre, preferably an intruder alert, fire alarm and/or extinguishing control centre |
US11922795B2 (en) * | 2019-03-18 | 2024-03-05 | Minimax Viking Research & Development Gmbh | Support component of a housing of a hazard alert center and a hazard alert center, preferably an intruder alert, fire alarm and/or extinguishing control center |
Also Published As
Publication number | Publication date |
---|---|
FR2203238A1 (US08080257-20111220-C00005.png) | 1974-05-10 |
IT972200B (it) | 1974-05-20 |
ZA737102B (en) | 1974-11-27 |
FR2203238B1 (US08080257-20111220-C00005.png) | 1978-09-22 |
JPS4974806A (US08080257-20111220-C00005.png) | 1974-07-19 |
CH570029A5 (US08080257-20111220-C00005.png) | 1975-11-28 |
DE2351367A1 (de) | 1974-05-09 |
BE806007A (fr) | 1974-02-01 |
GB1433184A (en) | 1976-04-22 |
BR7307405D0 (pt) | 1974-08-29 |
DE2351367C2 (de) | 1983-01-13 |
JPS5619146B2 (US08080257-20111220-C00005.png) | 1981-05-06 |
AU6125373A (en) | 1975-04-17 |
ES418704A1 (es) | 1976-02-16 |
CA994021A (en) | 1976-07-27 |
NL7313976A (US08080257-20111220-C00005.png) | 1974-04-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ITALTEL S.P.A. Free format text: CHANGE OF NAME;ASSIGNOR:SOCIETA ITALIANA TELECOMUNICAZIONI SIEMENS S.P.A.;REEL/FRAME:003962/0911 Effective date: 19810205 |