JPS58181343A - Optical signal transmission circuit - Google Patents

Abstract

PURPOSE:To restore original signals accurately, by equalizing the atenuation factor of red and green light even if the optical fiber length is changed and making the change in the output amlitude of an amlifier due to the change in the optical fiber length equal to each other. CONSTITUTION:A signal to be transmitted from a terminal 20 in a transmission circuit is formed into signals of opposite phase at a non-inverting amplifier 21 and an inverting amplifier 22, red LED 1a and a green LED 1b connected to the output of each amplifier are lighted alternately when the polarity of the signal inputted to the terminal 20 is changed as positive and negative polarities, and an optical signal caused by light emission of each LED is transmitted to a reception circuit via an optical fiber 2. The reception light is separated at red and green filters 3a, 4b and received on photodiodes 3, 4. An output signal of the diodes 3, 4 is amplified by amplifiers 5, 6, and converted into a reception signal by a differential amplifier consisting of an amplifier 7 and resistors 8, 9, and 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical signal transmission circuit for transmitting signals using optical fibers.

Conventionally, when transmitting signals using optical fibers, light from a light emitting element generated on the transmitting side is transmitted via the original fiber, and the light is converted into an electrical signal by a light receiving element on the receiving side. was converting. In addition, in the case of digital signal transmission, the output signal of the light receiving element is amplified on the Ka receiving side, the amplified signal is compared with a certain threshold voltage, and converted into a digital signal.9. However, the length of the optical fiber K
Since the attenuation rate of the emitted light changes, it is necessary to adjust the amplification rate of the light receiving element output amplification and the threshold voltage in accordance with the length of the optical fiber in the receiver 11.

The present invention is intended to solve the above-mentioned problems in the prior art, and an object thereof is to provide an optical signal transmission circuit that is not affected by Ton, the length of an optical fiber, and does not require adjustment of a threshold voltage.

Next, the invention! J! This will be explained with reference to examples.

FIG. xi shows a first embodiment of the optical signal transmission circuit according to the present invention, and FIG. Indicates the connection relationship with Dymede, 1 is red,
This is a light emitting diode package in which light emitting diodes of each color of green are housed in the same package, and 3.4 is a photodiode Y for receiving light, with a red filter 3 & a green filter 4 respectively.
B is shifted to the front. FIG. 1(b)a shows the configuration of the transmitting circuit and the receiving circuit in the optical signal transmission circuit. The red LED 1a and green LED I b connected to the output of each amplifier are turned on alternately as the sign of the signal input to terminal 2G changes from positive to negative. The optical signal generated by the light emission of each LED is transmitted to the receiving circuit via the optical fiber 2. In the receiving circuit, the light from the expansion fiber 2 is received by a red filter 3a and a green filter 4b by photodiodes 3.4, respectively.

Each signal outputted from the photodiode 3.4 in response to light reception is amplified by an amplifier 5.6, and the amplifier 7 and the resistor [
The received signal is converted into a received signal by a differential amplifier composed of 9, 10, and 11, and the received signal is outputted from a terminal 12. In this way, even if the optical fiber length changes, the attenuation rate of red light and green light is the same.
Since the output amplitude changes are also the same, the differential amplifier can accurately restore the original signal. In other words, no adjustment can be achieved.

Further, when using plastic fibers with a large attenuation factor, the present invention brings about a very large effect.

A second embodiment of the invention is shown in FIG. FIG. 2 shows an example in which the present invention is applied to air conditioning equipment for a building. In FIG. 2, 31 is a controller for air conditioning equipment installed indoors;
32 is an optical fiber, 33 is an air conditioner indoor unit, 34
is the duct, 35 is the outdoor unit, the transmitting circuit of the p11 signal circuit is installed in the controller 231, and the receiving circuit is installed in the indoor unit 3.
The controller 231 converts the control signal from the controller 231 into an optical signal by the transmitting circuit and sends it to the indoor unit 33 via the optical fiber 32.The indoor unit 33 regenerates the original control signal from the received optical signal. to control the air conditioning. Normally, in an air conditioning system as shown in FIG. 2, the distance between the indoor unit and the controller varies greatly depending on the size and structure of the chicken.

In equipment where the actual wiring distance is not constant, it becomes troublesome to adjust the transmission and reception level of data transfer depending on the distance. Furthermore, in order to prevent noise from being superimposed on the control signal, it is necessary to prevent the wiring between the controller 31 and the indoor unit 330 from being wired in parallel with other power lines.

In such cases, if the optical transmission signal circuit according to the present invention is used, there is no need to adjust the wiring length, and since the control signal is an optical signal, the control line (optical fiber) can be used without interference due to electromagnetic induction. ), which poses a problem even if wired parallel to the power line, the installation work can be simplified. In addition, plastic fiber is used as a low-cost optical fiber, and its light transmittance is considerably lower than that of glass fiber, as shown in Figure 6, but the use of the optical signal transmission circuit tube according to the present invention reduces the attenuation of light. Even if the rate is large, the original signal can be reproduced accurately, so there is no problem, and signal transmission can be performed at extremely low cost.

As described above, according to the present invention, the original signal can be accurately reproduced on the receiving side regardless of the magnitude of the optical attenuation rate in optical signal transmission using an optical fiber, and the There is no need for level adjustment, and an inexpensive Silasnac fiber can be used without considering its poor light transmittance, making it possible to construct an inexpensive optical signal transmission circuit. The present invention can also be applied to signal transmission within an automobile.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of one embodiment of the optical signal transmission circuit according to the present invention, FIG. 2 is a block diagram showing another embodiment of the optical signal transmission circuit according to the present invention, and FIG. It is a characteristic diagram of a fiber. 1...Light emitting diode package, la*1b...
Light emitting diode, 2.32-...Optical fiber, 3,4-
...Photodiode, 3a+4b...Filter, 5
゜6.7... Amplifier, 21... Non-inverting amplifier, 22
...Reversing amplifier, 31... Controller, 33...
- Indoor unit, 34... duct, 35... outdoor unit. Agent: 4 people from Kogai

Claims (1)

[Scope of Claims] (1) A rounded optical signal transmission circuit that transmits signals using optical fibers, in which the transmission circuit uses light of different colors to indicate the sign and the opposite sign of the signal to be transmitted. The wrinkled optical signal is converted into a station code and transmitted via an optical fiber, and in a receiving circuit, the optical signal received via the optical fiber is converted into an electric signal for each party signal of a different color. An optical transmission circuit in which a round can electric signal is input to a differential amplifier, and the output of the wrinkled differential amplifier is the regenerated original signal. (2. The optical signal transmission circuit according to claim j11, in which the transmitting circuit uses light emitting diodes each emitting a different color so that the sign and the opposite sign of the signal are different from each other. (3) An optical signal transmission circuit according to claim 1, wherein the receiving circuit converts an optical signal received via an optical fiber into an optical signal of a different color. An optical transmission circuit that uses filters to separate optical signals into different colors.