JPS60113545A - Two-line-type transmitter - Google Patents

Abstract

PURPOSE:To save power consumption quantity by providing a photodiode which receives the light emitted by a regular-direction LED which is provided at the two-line-type transmission route whose load current flows, and by feed-backing negatively the output to a voltage response means. CONSTITUTION:A signal ei to be transmitted is inputted to one side of a voltage amplifier 2, and is inputted to a current adjuster 1 by amplifying. The current adjust 1 is connected to a load L in serial through a two-line transmission route LN, and adjusts a load current IL by corresponding to the input signal ei. The current IL is also flown to an LED5 which is connected to the line LN, and it emits light in correspondence to the current IL. A photodiode 6 generates a current i1 which corresponds to the emitted light, that is, the load current IL. Resistances 31 and 32, and a linearizer 61 are connected in serial, a voltage VZ of Zener diode is impressed as a bias, and a voltage ef of the resistance 32 is in proportion to the load current IL. The voltages ef and ei operate so that they will be equal. Thus, a voltage detection resistance is not needed, and the power consumption quantity can be saved.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a two-wire system that transmits signals from a transmission end 11111 and supplies power consumed on the transmission side via a common 26 transmission path. It is related to transmitters.

[Prior art]

As a conventionally known transmitter of this kind, for example,
There is one described in Japanese Patent No. 42956.

FIG. 1 is a block diagram of the configuration of this transmitter, which includes means 1 for adjusting the current flowing through the load, and a signal e to be transmitted.
, a resistance means 3 that provides a voltage according to the load voltage, and a loop 4 that negatively feeds back the voltage generated in this resistance means to the voltage response means 2. .

This device has the feature that it can accurately correspond to the signal ei to be transmitted and transmit the electric power jlU to the load.
Since the configuration is such that the resistance means 5 is connected to the line transmission line,
There is power consumption (L.1<f) here, which poses a problem of increasing power consumption at the transmission end. Specifically, when the load current is 4 to 20 mA, the value of the resistance means 5 is usually about 50 to 2000, and the maximum power consumption here is about several watts.

[Object of the present invention]

The present invention has been made in view of these problems in the prior art, and is intended to realize a two-wire transmitter that can reduce power consumption on the transmission end side.

[Summary of the invention]

In the device according to the present invention, a light emitting diode is connected in the forward direction to a two-wire transmission line through which a load current IL flows, and a photodiode is provided to receive light from the light emitting diode. The feature is that the output signal is negatively fed back to the voltage response means.

〔Example〕

FIG. 2 is a block diagram showing an example of a device according to the present invention. In this figure, L is a load, BT is a DC power supply connected in series with the load, and these are installed on the receiving side. Reference numeral 1 denotes a current adjusting means for adjusting the load current flowing to the load, and here a transistor inserted and connected to the -2 line transmission line LN is used. Reference numeral 2 denotes a voltage response means to which a signal to be transmitted and a pressure e are applied to one input terminal, and a differential amplifier is used here. This differential amplifier is operated by power from the DC power supply IJT supplied via the two-wire transmission line LN. Note that the voltage applied to the power supply terminals 21 and 22 of the differential amplifier 2 is maintained at a constant voltage by a Zener diode 23 and a constant current circuit 24 that supplies a constant current to the Zener diode.

5 is the transmission end side, where load power is installed on the 2M transmission line LN;
A light emitting diode inserted and connected in the forward direction of the load emits light with an intensity corresponding to the size of the load. 6 is a photodiode that receives light from this light emitting diode 5;
For example, a PIN photodiode is used, producing an electrical signal 11 corresponding to the intensity of the light received. 61 is a linearizer connected to photodiode 6, and resistor 31
, 52 and the load current IL are in a proportional relationship, and is unnecessary if the output signal 11 of the photodiode is in a proportional relationship with the load current.

The operation of the apparatus configured in this way will be explained next.

The signal e to be transmitted is applied to one input of the voltage response means 2, amplified there and then applied to the current adjustment means 1. This current adjusting means 1 is connected in series with a load via a two-wire transmission line LN, and adjusts the load current with respect to the signal e to be transmitted. The load current piece is 2
A similar flow also flows to the light emitting diode 5 inserted and connected to the gland transmission line LNK, so that the light emitting diode 5 emits light with a light intensity corresponding to the load 1u flow I.

FIG. 3 is a diagram showing the voltage-current characteristics of the light emitting diode 5. As is clear from this characteristic, the forward voltage drop Vd is small regardless of the increase in the load current IL, and there is almost no power consumption in the light emitting diode 5 portion.

The light from the light emitting diode 5 is incident on the four diode 6 and produces an output signal 11 corresponding to the light intensity, ie the load current component. In this embodiment, the photodimate 6 is a resistor. +1, 32 are connected in series via a linearizer 61, and a soyer diode 23 is connected to this series circuit.
A constant voltage Vz that has been made constant at 1° is applied as a bias (1°
)L pressure e is for load electric construction. It becomes a proportional relationship.

The voltage e developed at one end of the resistor 32 is applied to the other input end of the voltage responsive stage 2. Therefore, the circuit including the voltage response means and the photodiode 6 operates so that the two input terminal voltages of the voltage response means 2 are equal (e, -e, ). Therefore, the load current IL is exactly proportional to the signal e to be transmitted.

In the above embodiment, a photodiode receives light from a light emitting diode, but the present invention is not limited to this as long as it is an element that outputs an electrical signal corresponding to the amount of light received, such as a solar cell.

[Effects of the present invention]

As described above, according to the present invention, there is no resistance means that increases power consumption in the transmission line on the transmission end side, so it is possible to realize a two-way transmitter that can reduce power consumption. Incidentally, as the light emitting diode 5, an IJD with a forward voltage drop of 1.5 is used, and the load current 5 is 4.
~20. When changing by mA, the power consumption in this part is about 50 mW at maximum, which can significantly reduce the power consumption.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing an example of a conventional device, FIG. 2 is a configuration block diagram showing an example of a device according to the present invention, and FIG.
The figure is a voltage-current characteristic diagram of six light-emitting diodes used in the device shown in Figure 2. DESCRIPTION OF SYMBOLS 1... Current adjustment means, 2... IL pressure response means, 5.
・Light-emitting diode, 6... Fumetodimade, L...
・Load, IIT...DC'7h, source, LN...2-wire transmission line.

Claims (1)

[Claims] (1) Voltage response means to which a signal to be transmitted is applied; current adjustment means for adjusting the load current flowing through the two-wire transmission line according to the signal from the voltage response means; current flowing through the two-wire transmission line; a light-emitting diode inserted and connected in a forward direction to the light-emitting diode, a light-receiving element for receiving light from the light-emitting diode, and circuit means for negatively feeding back a signal obtained by the light-receiving element to the input side of the voltage response means. Equipped with 2# type transmitter.