# US 7,609,975 B2 · Optical transmission apparatus

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- Number: US 7,609,975 B2
- Document ID: US7609975B2
- Status: Granted
- Kind: B2
- Application number: 11/646,565
- Filed: 2006-12-28
- Published: 2008-03-06
- Granted: 2009-10-27
- Earliest claimed: 2006-08-29
- Assignees: Fujitsu Limited
- Inventors: Chikashi Hashimoto; Yoshihisa Ikeda
- Web page: https://patentgrep.com/patent/US7609975B2

## CPC

- H04J 14/0279: {WDM point-to-point architectures}
- H04J 14/02216: {by gain equalization}
- H04J 14/0297: {Optical equipment protection}
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

In an optical transmission apparatus controlling an optical output portion by a working optical output controller and a protection optical output controller, the optical output controllers separately generate (inverted) preset value signals corresponding to a common output preset value provided from outside, and perform an analog addition of a common optical output monitoring signal and the preset value signal with an integrating circuit. An optical output portion generates an optical output signal which is an optical input signal controlled based on an output of the wired-OR of the optical output controllers, and generates the optical output monitoring signal corresponding to the optical output signal. When the optical output monitoring signal exceeds the preset value signals, the optical output controllers substantially control input terminals of the integrating circuits respectively to a ground potential by using control circuits.

## Claims

### Claim 1

An optical transmission apparatus comprising:
a first and second optical output controllers respectively including a preset value controller generating a preset value signal corresponding to a common output preset value provided from outside, and an integrating circuit having input terminals for performing an analog addition of a common optical output monitoring signal and the preset value signal; and
an optical output portion connecting output signals of the optical output controllers in form of a wired-OR, generating an optical output signal which is an optical input signal controlled based on an output of the wired-OR, and generating the optical output monitoring signal corresponding to the optical output signal;
each optical output controller further comprising a control circuit substantially controlling the input terminal of the integrating circuit to a ground potential when the optical output monitoring signal exceeds the preset value signal.

### Claim 2 (depends on 1)

The optical transmission apparatus as claimed in claim 1, wherein the integrating circuit is composed of a feedback circuit including a first resistor and a capacitance, and an operational amplifier having a second and third resistors respectively inputting the optical output monitoring signal and the preset value signal for performing the analog addition with the first resistor.

### Claim 3 (depends on 1)

The optical transmission apparatus as claimed in claim 1, wherein the optical output portion is composed of a wired-OR circuit comprising a first and second diodes which respectively input output signals of the first and second optical output controllers to be outputted to a common connection point, an optical variable attenuator generating the optical output signal which is the optical input signal attenuated corresponding to the output signal of the common connection point, and a monitoring portion generating the optical output monitoring signal from the optical output signal generated from the optical variable attenuator.

### Claim 4 (depends on 1)

The optical transmission apparatus as claimed in claim 1, wherein each control circuit is composed of a comparison controller comparing the optical output monitoring signal with the preset value signal, a switch closed by the comparison controller only when the optical output monitoring signal exceeds the preset value signal, and an impedance circuit which composes a series circuit with the switch and which compulsorily drops the input terminal of the integrating circuit to a ground potential when the switch is closed, and the series circuit of the switch and the impedance circuit is connected in parallel with the feedback circuit.

### Claim 5 (depends on 4)

The optical transmission apparatus as claimed in claim 4, wherein the impedance circuit comprises a resistance voltage-dividing circuit connected between an output terminal of the operational amplifier and the ground potential, and a voltage diving point thereof is connected to the switch and is set substantially close to the ground potential.

### Claim 6 (depends on 1)

The optical transmission apparatus as claimed in claim 1, wherein the preset value controller has functions of performing a D/A conversion of the output preset value and inverting the value.