EP0044138A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Electrical circuit on porcelain coated metal substrate
Assignee: Nortel Networks Ltd
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Filing: 1981-06-12
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Granted: —
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Expires: 2001-06-12
Abstract
Abstract A porcelain (14, 27, 35, 58) coated metal substrate (13, 26, 57) bearing a printed circuit (11, 28, 31, 32, 33, 36, 62) and in which a capacitance effect is created between the substrate (13, 26, 57) and the circuit to eliminate unwanted frequencies. The capacitor may be formed by having a ground connection (15, 40, 64) to the metal substrate or by providing a further capacitance from the substrate to another conductive member which is itself ground. The invention is of particular use for audio equipment, e.g. a pushbutton switch for telecommunications equipment in which high frequency signals are to be eliminated.
Inventors
- 👤 Guy John Chaput
- 👤 Edward Matthew Sich
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 13:11
CPC Classifications
H; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/05; H05K1/053; H05K1/0213; H05K1/0215; H05K1/16; H05K1/162
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
98 words
A circuit board comprising an electrically conductive metal substrate having a porcelain layer on at least one of its surface and a printed electrical circuit on said porcelain layer, characterized by the board (10, 24, 34, 56) also having means (15, 40, 64) to produce a capacitance effect from the printed circuit (11, 28. 31, 32. 36. 62) to the metal substrate (13, 26, 57). the value of the capacitor effect being determined by the area of contact between the printed circuit and the porcelain layer (14, 27, 35, 58) and by the thickness of the porcelain layer.
Claim 2
Dependent Claim
98 words
A circuit board comprising an electrically conductive metal substrate having a porcelain layer on at least one of its surface and a printed electrical circuit on said porcelain layer, characterized by the board (10, 24, 34, 56) also having means (15, 40, 64) to produce a capacitance effect from the printed circuit (11, 28. 31, 32. 36. 62) to the metal substrate (13, 26, 57). the value of the capacitor effect being determined by the area of contact between the printed circuit and the porcelain layer (14, 27, 35, 58) and by the thickness of the porcelain layer.
Claim 3
Dependent Claim
32 words
A circuit board according to claim 1 . characterized in that the capacitance effect is created by the provision of grounding means (15, 40, 64) to connect the metal substrate to ground.
Claim 4
Dependent Claim
69 words
A circuit board according to claim 1 characterized in that a further conductive element (39) is provided which is spaced from the metal substrate by the porcelain layer (35), and means (40) are provided for connecting said further element to ground, to form the capacitance effect from the printed circuit (36), to the metal substrate and another capacitance effect from the metal substrate to said further conductive element (39).
Claim 5
Dependent Claim
46 words
A circuit board according to claim 1 characterized in that the printed circuit has at least one conductor (18, 28, 36) which is printed with large and small width portions (20, 21, 23, 31, 32) to give the desired area of contact with the porcelain layer.
Claim 6
Dependent Claim
40 words
A circuit board according to claim 1 characterized bv at least one resistor (33) connecting portions (31, 32) of the conductor (28) in series, the resistor formed by printing techniques and providing a capacitance effect with the metal substrate (26).
Claim 7
Dependent Claim
36 words
A circuit board according to claim 1 characterized by having an integrated circuit (16, 30, 63) carried upon the porcelain (14, 27, 58) and electrically connected to the printed circuit (11. 28. 31. 32. 36. 62).
Claim 8
Dependent Claim
72 words
A pushbutton switch assembly for telecommunications apparatus comprising pushbutton means and a switch contact circuit associated with the pushbutton means so as to have contact areas connected by.operation of the pushbutton means, characterized in that it includes a circuit board (56) according to claim 1, the printed circuit (62) being connected to the switch contact circuit (59) to transmit an audio signal to a desired destination upon connection of said contact areas.
Claim 9
Dependent Claim
29 words
An assembly according to claim 7 characterized in that the switch contact circuit is also a printed circuit and is disposed upon the porcelain (58) of the circuit board.
Claim 10
Dependent Claim
37 words
An assembly according to claim 8 characterized in that the switch contact circuit is on one side of the circuit board (57) and the printed circuit (62) to provide the capacitance effect is on the other side.
Claim 11
Dependent Claim
21 words
An assembly according to claim 8 characterized in that it also includes an integrated circuit (63) located upon the circuit board.
References Cited (Backward Citations)
No citation records indexed.
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