This application claims priority to Patent Application No. 2003-281029 filed in Japan on 28 Jul. 2003, the content of which is incorporated herein by reference in its entirety.
The present invention pertains to a magnetically coupled device in which insulator layer(s) intervene between mutually magnetically coupled transmitting coil(s) and receiving coil(s), input of signal(s) at transmitting coil(s) causing output at receiving coil(s) of signal(s) produced at least partially by induction due to magnetic coupling therebetween; and to electronic equipment employing same.
As is known, optically coupled devices, employed in a wide variety of electronic equipment, are provided with light-emitting element(s) at input side(s) thereof and light-receiving element(s) at output side(s) thereof, signal transmission taking place with input side(s) being electrically isolated from output side(s).
It so happens that in recent years magnetically coupled devices, with their faster communication rates, have drawn more attention than optically coupled devices due to increases in transmission speed (on the order of between 50 Mb/s and 100 Mb/s), representative of which is the situation existing with respect to fieldbus networks for factory automation equipment and the like.
Among such magnetically coupled devices is, for example, that disclosed at U.S. Pat. No. 6,376,933. In this magnetically coupled device, which comprises bridge circuitry including magnetoresistive sensor(s) for which resistance varies in correspondence to magnetic field strength, magnetoresistive sensor(s) is/are used to detect input magnetic field(s), output signal(s) from magnetoresistive sensor(s) is/are extracted from bridge circuitry, such output signal(s) is/are fed back thereinto, output magnetic field(s) is/are produced, and output signal(s) from magnetoresistive sensor(s) is/are extracted to the exterior while control is carried out so as to cause input magnetic field(s) and output magnetic field(s) to cancel out one another. Here, because output signal(s) is/are fed back thereinto, input magnetic field(s) and output magnetic field(s) being made to cancel out one another, internal noise generated at output-signal-side circuitry is canceled out.
However, the foregoing conventional magnetoresistive devices have had the problem that, even where it may have been possible to reduce internal noise, as no consideration had been made for reduction of geomagnetism and other such external noise, there has been occurrence of distortion of output signal waveform(s) and/or phenomena such as dropped bits during communication of output signal(s), preventing normal communication.
The present invention was therefore conceived in light of the foregoing conventional issues, it being an object thereof to provide a magnetically coupled device capable of reducing effects of external noise and of stably carrying out high-speed communication.