Optical communication apparatus and method

• US 5,040,242 A
• Filed: 06/28/1990
• Issued: 08/13/1991
• Est. Priority Date: 09/16/1987
• Status: Expired due to Fees

• Current Assignee: Totoku Electric Company Limited (Furukawa Electric Company Limited)
• Original Assignee: Totoku Electric Company Limited (Furukawa Electric Company Limited)
• Inventors: Tsuchiya, Yukinari, Saito, Tetsuo
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/546,690
• Time in Patent Office: 411 Days
• Field of Search: 455/600-603, 455/606-613, 455/617-619
• US Class Current: 398/116
• CPC Class Codes: H04B 10/808 Electrical power feeding of an optical transmission system
• CPC Class Codes: H04L 25/26 Circuits with optical sensing means , i.e. using opto-couplers for isolation

Abstract

Information processors are interconnected via an optical communication apparatus and an optical communication medium to perform data communication. Each information processor has a standard interface which operates based on electric signals, and input/output control is executed in accordance with the standard interface specifications. The optical communication apparatus is provided with an input electric signal from the information processor, converts the electric signal into a corresponding optical signal upon performing pulse-width modulation in such a manner that the pulse width differs at the leading and trailing edges of the electric signal, and outputs the optical signal to the optical communication medium. Conversely, the apparatus is provided with a pulse-width modulated input optical signal from the optical communication medium, discriminates the leading and trailing edges of an electric signal from the pulse width, demodulates the optical signal and converts it into a corresponding electric signal outputted to the information processor. The optical communication apparatus produces all of the required driving power from output electric signal lines from the information processor.

Claims

1. A bi-directional optical communication modulation/demodulation apparatus connected between a pair of optical communication media and a local information processor and capable of converting an electrical signal to an optical signal and vice versa for data communication via said optical media with a remote data information processor, comprising:

first conversion means for converting local data information signals to optical signals for sending to a remote information processor, said first conversion means having connector means for connection between said apparatus and said local information processor for receiving a local input electrical data signal from said local information processor via an electrical data signal line, and having pulse-width modulation means for conducting pulse-width modulation of the received input electrical data signal in synchronization with the leading edge of a clock signal from a clock circuit to thereby produce a pulse-width modulated input electrical data signal, and having electrical to optical converter means for converting the modulated input electrical signal to an optical signal and having external coupling sending means for delivering said optical signal to one of said optical communication media;

second conversion means for converting incoming remote origination signals, said second conversion means having external coupling receiving means for receiving, through the other of said optical information media, a pulse-width modulated input optical information media, a pulse-width modulated input optical signal originating from a remote information processor, and having opto-electrical converter means for converting the received optical signal into a corresponding electrical signal having substantially the same pulse width relating to said modulated input optical signal, and having receiving electrical demodulation means for demodulating said corresponding electrical signal, and having local processor connector means for delivering the demodulated corresponding electrical signal to said local information processor; and

power producing means for producing stable DC electrical power for said apparatus also being connected to said electrical data line from said local data processor for receipt of said local input electrical data signal from said local information processor and for delivering from said power producing means the produced electrical power to said first and second conversion means when said input electrical signal is transmitted to said apparatus from said local information processor.

2. A bi-directional optical communication modulation/demodulation apparatus according to claim 1, wherein said first conversion means modulates, immediately after a change in the voltage level of said input electrical signal, the said received input electrical data signal into a pulse-width modulated electrical signal corresponding to said input signal and wherein the input electrical data signal is modulated into a signal equivalent to more than "t" periods of the clock signal at the leading edge of the input electrical data signal and into a signal equivalent to "t" at the trailing edge of the clock signal during the time that the said input electrical signal is on so as to shorten the time of light-emitting time of an optical signal when the conversion means converts the modulated electrical signal into said optical signal and delivers said optical signal to said media, while said second conversion means converts said input optical signal into said electrical signal having substantially the same pulse width relation to said input optical signal which has been modulated upon origination and which is converted to an electrical signal by said opto-electrical conversion before the resulting converted signal is demodulated within the apparatus, the converted electrical signal being demodulated within a demodulating circuit which includes a timer circuit which has an output waveform signal less than 2"t" periods of a timer clock signal but not less than one period thereof and said output waveform starts at the leading edge of the received and converted electrical signal, and wherein the leading and trailing edges of the demodulated converted electrical signal are decided depending upon whether the modulated converted signal is "high" or "low" when the output waveform of the timer circuit represents the energized state.

3. A bi-directional optical communication modulation/demodulation apparatus according to claim 1, wherein said first conversion means modulates said input electrical data signal into a pulse width modulated signal representing the leading and trailing edges of the original signal such that different pulse widths are obtained at the rise and fall of said input electrical data signal, so as to discriminate the rise and fall of said input electrical signal before said electrical to optical converter means converts the electrical pulse signal obtained through the modulation into an optical pulse signal, while said second conversion means converts received input optical signal into electrical pulse signal, discriminating different pulse widths of said electrical pulse signal, and changes the voltage level of the output electrical signal.

4. A bi-directional optical communication modulation/demodulation apparatus according to claim 1, wherein said power producing means includes a DC-DC converter or a voltage regulator capable of producing, from the "+" level of the electrical input signal from said information processor, a stable "+" power for driving said optical communication modulation/demodulation apparatus, said power producing means also being connected such that it delivers said "+" power to an interface circuit including a receiver circuit and a driver circuit, to a transmission circuit including a modulating circuit, clock signal circuit and a drive circuit having alight-emitting element, and to a receiving circuit including a demodulating circuit and an amplifier circuit having a light-receiving element.

5. The apparatus according to claim 4, wherein the DC-DC converter is adapted to have small input-output potential difference.

6. A bi-directional optical communication modulation/demodulation apparatus according to claim 4, wherein said power producing means includes a DC-DC converter capable of producing, from the "-" level of the electrical input signal from said information processor, a stable "+" power required for driving said optical communication modulation/demodulation apparatus, said power producing means being connected such that it delivers said "+" power to an interface circuit including a receiver circuit and a driver circuit, to a transmission circuit including a modulating circuit, clock signal circuit and a drive circuit having a light emitting element, and to a receiving circuit including a demodulating circuit and an amplifier circuit having a light-receiving element.

7. A bi-directional optical transmission modulation/demodulation apparatus according to claim 1, wherein said power producing means includes a polarity-inversion DC-DC converter capable of producing from the "+" level of said input electrical signal from said information processor, a stable "-" electrical power required for driving said optical communication modulation/demodulation apparatus with the "-" power, said power producing means being connected such that it delivers said "-" electrical power to a driver circuit of an interface circuit.

8. An optical communication method for conducting data communication between local and remote information processors through a pair of optical communication media connected therebetween, comprising:

placing, between each of said information processors and said pair of optical communication media, a bi-directional optical communication modulation/demodulation apparatus which comprises;

first sending conversion means for receiving an input electrical signal including data signals from said local information processor, conducting pulse-width modulation of the received input electrical signal to form a modulated electrical signal having leading and trailing data pulse edge indicators of different width converting the modulated electrical signal to an optical signal and delivering said optical signal to one of said optical communication media;

second conversion means for receiving, through the other of said optical information media, a pulse-width-modulated input optical signal from one of said remote information processors, converting the received input optical signal into an electrical signal having substantially the same pulse width relation to said input optical signal, demodulating said electrical signal to form a demodulated electrical signal whose leading and trailing edges are decided depending upon whether the modulated electrical signal is high or low when a timer represents an energized state, and delivering the demodulated electrical signal to said information processor; and

power producing means for producing electrical power from said electrical signal including data signals received from said information processor and delivering the produced electrical power to said first and second conversion means;

whereby the data communication between said information processors is possible by pulse-width-modulated optical signal, while said information processors have standard interface constructions based on electrical signals and operate under input/output control in accordance with the standard electrical computer data interface specification.