(19) |
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(11) |
EP 0 470 558 A3 |
(12) |
EUROPEAN PATENT APPLICATION |
(88) |
Date of publication A3: |
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27.05.1992 Bulletin 1992/22 |
(43) |
Date of publication A2: |
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12.02.1992 Bulletin 1992/07 |
(22) |
Date of filing: 05.08.1991 |
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(51) |
International Patent Classification (IPC)5: G08C 19/46 |
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(84) |
Designated Contracting States: |
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DE FR GB IT |
(30) |
Priority: |
06.08.1990 US 583480
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(71) |
Applicant: CINCINNATI MILACRON INC. |
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Cincinnati
Ohio 45209 (US) |
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(72) |
Inventors: |
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- Morser, Harold, A.
Cincinnati, Ohio 45243 (US)
- Nead, Thomas, E.
Loveland, Ohio 45140 (US)
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(74) |
Representative: Lally, William et al |
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FORRESTER & BOEHMERT
Franz-Joseph-Strasse 38 80801 München 80801 München (DE) |
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(54) |
Apparatus for position measurement |
(57) Interface circuits for electromagnetic position transducers are provided to reduce
the effects of capacitive coupling occurring in the conductive cabling between the
position transducers and the associated interfaces located remotely therefrom. Capacitive
coupling of excitation signals to the transducer output signals result in error signals
appearing as cyclic error in measured positions. The magnitude of the coupled signals
are substantially reduced by providing excitation signals symmetrical with respect
to ground. The magnitude of the coupled signals are also reduced by presenting equal
impedances relative to ground to the output signal return and signal paths. By reducing
the effects of capacitively coupled signals, conducting cables for the excitation
signals and the transducer output signals may be incorporated in a single shielded
cable.