JPS60149231A - Signal transmitter - Google Patents

Abstract

PURPOSE:To improve the quality of an output transmission signal by correcting the current which drives a light emitting element with use of a partial output signal of an operational amplifier and also correcting the current produced by a photoelectric transducer. CONSTITUTION:A power supply +Bis connected to the emitter of a current control transistor TRTr1, and the collector of the Tr1 is connected to the cathode of a diode D1 for photodetecting element. The output terminal of the D1 is connected to a reverse input terminal of an operational amplifier 4, and a variable resistance terminal connected to the power supply +B is connected to a non- reverse input terminal of the amplifier 4. The output terminal of the amplifier 4 is led to the inverse input terminal of an operational amplifier 6, and the variable resistance terminal connected to the +B is connected to the non-inverse terminal of the amplifier 6. The output of the amplifier 6 is applied to the base of the Tr1 as well as to an LEDD2 via a TRTr2. Then the digital signal is applied to the base of a TRTr3 having its collector connected to the collector of the Tr2. Thus an LED is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention converts optical fiber signals into electrical signals, supplies digital signals transmitted through optical fibers to electrical equipment, and converts predetermined electricity from within the electrical equipment. The present invention relates to a signal transmission device suitable for use in a plug that converts a signal into an optical signal and supplies it to an optical fiber, thereby transmitting a digital signal in both directions.

BACKGROUND TECHNOLOGY AND PROBLEMS Signal transmission between electrical devices is performed by optical fibers as necessary. Therefore, in addition to converting the optical signal transmitted through the optical fiber into an electrical signal and supplying the digital signal transmitted through the optical fiber to the electrical equipment, a predetermined electrical signal from within the electrical equipment is converted into an optical signal. Plugs that transmit digital signals in both directions have been proposed. However, since signal attenuation is likely to occur during transmission through optical fibers, there is a problem in that the electrical signal obtained at a predetermined input terminal on the jack side of the electrical device deteriorates. At the same time, it was also desired to supply good optical signals from electrical equipment to optical fibers.

OBJECTS OF THE INVENTION In view of the above, an object of the present invention is to provide a signal transmission device that can effectively transmit digital signals in both directions.

1III Essentials of the Invention The signal transmission device of the present invention includes a light receiving element that receives an optically transmitted digital signal, an amplifier that amplifies the output signal of the light receiving element, and a light emitting element that emits the optically transmitted digital signal. and a drive circuit that drives the light emitting element with a digital signal, and a part of the output signal of the amplifier is supplied to the drive circuit, so that the transmission signal can be transmitted effectively in both directions. It is.

Embodiment Hereinafter, an embodiment of the signal transmission system (β) of the present invention will be explained with reference to FIGS. 1, 2, and 3.

In Figure 1, (1) is the signal transmission device used in the bidirectional transmitting and receiving circuit, and (2) is the optical fiber that transmits the optical signal, (3) is the bidirectional signal transmission plug. Photoelectric conversion circuit used in the transmitter/receiver circuit, (4)
is the ground terminal, (5) is the signal terminal, and (6) 4.1 is the power supply terminal. This signal transmission device (1) converts the digital signal (optical signal) transmitted through the optical fiber into an electrical signal and generates electricity. In addition to being supplied to equipment, the electrical signals that have been subjected to predetermined signal processing within the electrical equipment are converted into optical signals, and the digital signals are transmitted bidirectionally.

This plug (1) has a structure that allows it to be inserted directly into the shank of conventional electrical equipment, so that signals can be transmitted between electrical equipment using optical fibers. In addition to being able to supply electrical signals to a jack, it is also possible to transmit electrical signals from an electrical device to other electrical devices.

Next, the photoelectric conversion circuit (3) will be described with reference to FIG. PNP type transistor for current control 1゛r
Connect the power supply terminal to the emitter of transistor Trt
The collector of this photodiode D1 is used as a light receiving element.
Connect to the cathode of In addition, the anode side of the photodiode D1 is connected to an operational amplifier ('ζ) via a 1lli resistor R1.
4) is connected to the inverting input terminal O of the photodiode D1.
and Jl (the connection point with the anti-resistance layer R1 is grounded via the resistor R2. Also, the non-inverting input terminal ω of the operational amplifier (4) is connected to the movable terminal of the variable IW anti-resistance layer 3, and the variable ILt Power is supplied from the m source terminal +B to one end of the resistor layer, and the other end of the variable resistor R3 is grounded.In addition, a capacitor C1 is connected between the output terminal of the operational amplifier (4) and the inverting input terminal θ. and resistor R4 are connected in parallel, and the overall increase is 1.
ft, i, and a low-pass filter circuit to remove noise at lower frequencies. Here, it becomes an operational amplifier (ω two frequencies), and if the cutoff frequency fc1 is the width ′
a (41 output terminal) to obtain a predetermined digital signal to the electrical equipment without any interruption. Also, the operational amplifier (
4) is fed via a resistor R5 to the inverting input O of an operational amplifier (6) forming a second low-pass filter circuit. Also, the non-inverting input terminal (2) of the operational amplifier (6) is connected to the movable contact of the variable resistor Rs. This r1
1 transformer 11 (one end of resistive layer R6 is connected to the mold pigtail terminal, and this 1+J transformer 11 (other than resistive layer R6) 1! is grounded. Also, the output terminal of the operational amplifier (6) is connected to resistor R7. ζ to the base of the current control transistor Trx. Also, a Jlj series circuit of a capacitor C2 and a resistor R5 is provided between the output terminal of the operational amplifier and the inverting input terminal θ, and the inverting amplifier and low frequency A filter circuit is formed.Here, the amplification of the input optical signal is set constant as the cutoff frequency.

In addition, a power supply type low is supplied to the emitter of the P N l) type transistor Tr2, and a
It supplies a signal at the connection point between the t-resistance layer 7 and the transistor Trs. Further, the collector of the transistor Tr2 is connected to the collector of the transistor Tr3 via a resistor R8. Further, a digital signal representing the issue of the electrical equipment is supplied to the base of the transistor Tr3 from the input terminal (8). Further, the emitter of the transistor Tr3 is grounded, and the resistor R8 and the transistor Tr3 are connected to each other at λ1.
The η connection point is connected to the anode of the light emitting element D2, and a digital signal corresponding to the No. 14 level of this common connection point is output as an optical signal.

Further, the cathode of the light emitting element D2 is grounded. The digital signal transmitted through the optical fiber is received by the light receiving element D1 as shown in the figure, and is led out to the output terminal (5), and is transmitted into the electrical equipment (g) and the output signal of the light receiving element is amplified. The light M of the light emitting element D2 is corrected using the signal thus obtained, and the light emitting element 1)2 outputs an optical signal to be transmitted through the optical fiber (2).

Next, an example of a processing device for a digital signal supplied into an electrical device by this plug l) will be explained with reference to FIGS. 3 and 4. In FIG. 3, (9) connects the signal input terminal of digital data DI, and this input terminal (9)
) signal to J −K Frisopf l':l Tsubu circuit 00
), and a clock pulse (FIG. 4C) is supplied from the clock pulse input terminal (11) to the clock pulse input terminal of the flip-flop circuit 00). In addition, the synchronized and modulated digital data DII (D in Figure 4) is output from the Q output terminal, and the serial input terminal S of the ζ shift I register (12) is output.
Supply to T. In this shift register (12), first (I11(
An 8-bit signal of 11000) is input from the ~1 terminal of the shift register (12), that is, to column 1111, and then input to the serial input f+Ii! of the shift register (12). Digital data D (I) or λ1 is input to the output terminal of the shift register (12), synchronized with clock pulses, and output from the output terminal of the shift register (12). (Fig. 4E) will be output. Digital signals can be transmitted bidirectionally through a predetermined jack using the above-mentioned plug (1) as a transmitting/receiving circuit for an electrical device having such a digital signal processing device.

Even if optical signals are transmitted through the front plate (1), the jack side can have the same configuration as conventional electrical signals are transmitted, so even if optical transmission is used, the configuration of the electrical equipment is the same as before. That's fine. Further, other parts are configured in the same manner as the conventional signal transmission device.

In this embodiment configured in this manner, the optical signal from the optical soiber (2) is photoelectrically converted by the photodiode F'D1, amplified by 1+ll via the operational amplifier (4), and then sent to the plug (11). A digital signal for a predetermined electrical device is derived from the output terminal (5).In this case, the level of this derived signal is determined by the transistor T that controls the current flowing through the photodiode D1 via the operational amplifier (6).
rt and is photoelectrically converted (even if the current obtained is corrected by negative feedback and the optical signal is attenuated, the output terminal (
5) Good electrical signals can be obtained.

Therefore, digital signals transmitted as optical signals through optical fibers can be efficiently transmitted as electrical signals into electrical equipment. In addition, in such electrical equipment, for example, a third
As shown in the figure, digital signal processing (DI-DTI→DI
[l) is performed, and its output signal (Fig. 4E) is sent to the terminal (
8) to the base of the transistor Tr3.
When the transistor Tr3 is non-conducting, a current flows through the light emitting diode D2 to emit light, and this optical signal is transmitted through the optical fiber. Here, in this embodiment, the output signal of the operational amplifier (6) is supplied to the base of the transistor Tr2 to compensate for the current flowing through the light emitting diode D2, and the optical signal fd without good signal attenuation is transmitted through the optical fiber. That will happen.

As described above, according to this embodiment, in the signal transmission device', part of the output signal of the operational amplifier is used to correct the current that drives the light emitting element D2, and the current generated by the photoelectric conversion element is corrected. Since the correction is made, the signal level transmitted in the bidirectional signal transmission device is corrected, and the transmission signal obtained at the output terminal (5) and the transmission signal as the amount of light emitted from the light emitting element D2 are made good. In addition, according to this embodiment, since it can be inserted directly into the jack of conventional electrical equipment, it is possible to transmit signals between electrical equipment using optical fibers as easily as signal transmission using electrical cords. There is profit.

Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations may be adopted without departing from the gist of the present invention.

Effects of the Invention The signal transmission device of the present invention includes a light receiving element that receives an optically transmitted digital signal (No. 74), an amplifier that amplifies the output signal of the light receiving element, and a light emitting element that emits the digital signal. Since the negative part of the output signal is used to control the current that drives the light emitting element that emits the ζ optical signal, there is an advantage that bidirectional digital signal transmission can be performed well.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the signal transmission device of the present invention.
Figure 2 is a connection diagram showing the main parts of the example shown in Figure 1.
3 and 4 are diagrams for explaining the example shown in FIG. 1. FIG. (4) and (6) are operational amplifiers, DI number: 1 light receiving element,
D2 is a light emitting element, Trl, Tr2 and Tr3 are transistors. Figure 2

Claims (1)

[Claims] A light receiving element that receives the optically transmitted digital signal No. 1r, an amplifier that amplifies the output signal of the light receiving element, and a light emitting element that emits the optically transmitted digital signal.
1. A signal transmission device comprising: a drive circuit for driving said light emitting element with a digital signal;