CN2426248Y - Optical coupling based light emission machine switch circuit - Google Patents

Abstract

The utility model provides a light emission machine switch circuit based on optical coupling. A control signal LDSW is connected with the negative end of an input pin of an optical coupling device D1, and the positive end of the input pin of the optical coupling device D1 is connected with a control end power supply Vc2 through a resistor R2. The output collecting electrode of the optical coupling device D1 is connected with a laser working site through a resistor R1, and the output emitter electrode of the optical coupling device D1 is connected with the base electrode of a transistor VT2; the emitter electrode of VT2 is connected with the bias power supply Vc1 of the laser LD, and the collecting electrode of VT2 is connected with the emitter electrode of a transistor VT1 or is connected with a bias input pin of the laser directly; a capacitor C1 and a resistor R3 are connected between the base electrode of the transistor VT2 and the bias supply Vc1. The circuit guarantees the safety of the laser during the switching process.

Description

A kind of optical sender laser switching circuit based on optocoupler

The utility model belongs to optical communication field.Specifically, relate to the switch control and the last electric protection of optical sender.

The optical transmission field uses LED (light-emitting diode) and LD (laser) as photoemissive light source device usually.When especially using laser,, eye-safe there is threat, needs in due course the luminous power of laser to be turned off because Output optical power is higher.And since laser be valuable device (in analogue transmission in addition its value account for equipment cost 80%), under some deadly conditions,, also need the laser bias power remove for protection device is not damaged; On the other hand, laser also is a tender and lovely device, is easy to damage, and the spike during Switching Power Supply is a potential threat for laser, so need rise slowly and descend the laser bias mains switch time, promptly opens slowly.

Though in more existing optical transport products, laser has been added switching circuit, these laser switching circuits mainly contain following a few class: (1) adopts mechanical switch directly to turn-off laser power supply, as on products panel, adding a lock-switch (present most products adopt this mode), can reach the purpose of Q-swith laser Q like this, can do a restriction to the authority of Q-swith laser Q again, but the shortcoming of this kind switch is tangible, present communication equipment all is to control by webmaster, monitoring, this on-off mode can't realize the control of webmaster, i.e. Long-distance Control.And mechanical switch is in switch stability, all exist defective aspect the protection of laser.(2) do electric-controlled switch with relay, this switch is actually a kind of automatically controlled mechanical switch, and its high failure rate, control signal all are its fatal shortcoming to interference, the switching pulse of communication path to the potential threat of laser.(3) with other device, as: the electric-controlled switch that triode, diode etc. are formed.Purpose for the protection laser; usually adopt the negative voltage power supply; form the laser switching circuit for this class device and brought very big trouble; so often have very complicated circuit conversion; cost and reliability all have been subjected to influence like this, and control circuit still exists crosstalking of communication path.

The purpose of this utility model overcomes above-mentioned defective of the prior art exactly, a kind of optical sender laser switching circuit based on optocoupler is proposed, with stable control, Long-distance Control, intelligent automatic control and the laser switch of realizing the laser switch and the fail safe that powers on.

Optical sender laser switching circuit based on optocoupler of the present utility model: control signal LDSW (LaserDiode Switch) links to each other with the input pin negative terminal of optocoupler D1, and the input pin anode of optocoupler D1 links to each other with control end power supply Vc2 by a resistance R 2.The output collector electrode of optocoupler D1 links to each other with laser works ground by resistance R 1; The output emitter of optocoupler D1 links to each other with the base stage of the triode VT2 that uses as switch; The emitter of triode VT2 meets the bias supply Vc1 (generally this power supply is a negative supply) of laser LD, between the base stage of triode VT2 and bias supply Vc1 and connect capacitor C 1 and resistance R 3, the collector electrode of VT2 then links to each other with the emitter of the triode VT1 that controls laser optical power, or directly links to each other with the biasing input pin of laser.

The utlity model has following advantage:

Adopt the laser switch of this scheme at first to realize automatically controlled switch, this is than the advanced part of mechanical switch; The input of automatically controlled signal comes from CPU, is easy to realize the control (can automatically shut down laser according to some abnormal conditions as CPU) of intelligence, long-range control like this, also is easy to realize the management of laser switch authority by software; Adopt optocoupler to make the main switching device of Q-swith laser Q power supply, with respect to triode or diode as for the switching device, the unlatching thresholding is broadened, as long as control voltage is higher or lower than certain value, and this value can be adjusted by the input current-limiting resistance, so be easy to realize stable switch, other automatically controlled device stability is then not as optocoupler; Adopting optocoupler to make switch also can suppress to crosstalk effectively: the control voltage of laser electric-controlled switch is generally all from digital circuit, and the ground of optocoupler input connects digitally, the ground of output connects the power supply ground of power supply, power control part branch and power suppling part branch can be separated fully, suppress to crosstalk mutually and the current potential influence.This is that relay and other switching device all can't be realized; Owing between the base stage of triode VT2 and bias supply Vc1, connect a capacitor C 1,, guarantee the safety of laser in the switching process by discharging and recharging of electric capacity to realize the startup slowly of laser.Therefore this circuit can further suppress the damage to laser of switch electricity spike and power surges.Safer, reliable than the on-off mode that does not open slowly.In a word, adopted after the switching circuit of the present utility model, not only overcome deficiency of the prior art, and the utility model has following characteristics than existing laser on-off mode: automatically controlled, reliable and stable, safety, inhibition are crosstalked, the control of intelligence, long-range control, and circuit is simple, be easy to realize, with low cost.

Below by specific embodiment and in conjunction with the accompanying drawings to the description in further detail of the utility model do:

The slow breakdown of optical sender laser that Fig. 1 is based on optocoupler closes circuit diagram.

As shown in the figure, LDBI is the biasing control voltage of laser LD, and this signal is bias current and the luminous power size that is used for controlling laser.LDSW is a laser LD switch control voltage.Control signal LDSW (Laser Diode Switch) links to each other with the input pin negative terminal of optocoupler D1, and the input pin anode of optocoupler D1 links to each other with control end power supply Vc2 by a resistance R 2.The output collector electrode of optocoupler D1 links to each other with laser works ground by resistance R 1; The output emitter of optocoupler D1 links to each other with the base stage of the triode VT2 that uses as switch, is combined as a switching system that is easy to control; The emitter of VT2 meets the bias supply Vc1 (generally this power supply is a negative supply) of laser LD, between the base stage of triode VT2 and bias supply Vc1 and meet capacitor C 1, R3.The collector electrode of VT2 then links to each other with the emitter of the triode VT1 that controls laser optical power, (to seek advice employing APC-automatic optical power control circuit in high simulated light transmission and the transmission of part digital light in luminous power, need VT1 in this case, the LDBI of VT1 base stage is the feedback signal of APC just.) to the less demanding occasion of optical power stability, need not the APC circuit, then shouldn't VT1, this moment, the collector electrode of VT2 directly linked to each other with the biasing input pin of laser.Only need very low electric current just can open optocoupler D1, the current drives triode VT2 that passes through by optical coupled switch.When LDSW=Vc2 (logic level 1), optocoupler D1 turn-offs, and triode VT2 ends, and laser bias current turn-offs; When LDSW=0 (logic level 0), optocoupler is opened, the VT2 saturation conduction, and laser bias current powers on.Optocoupler the effect here is: switch, the photoelectricity isolation of amplifying switching current, control access and communication path.The effect of triode VT2 is further amplified current, provides biasing required electric current for laser LD.R1, R2 play current limliting, protection optocoupler.In the process of switch,, guarantee the safety of laser in the switching process because the charge and discharge process of C1 has been realized opening slowly of laser power-on and power-off easily.Connect a resistance R 3 between the base stage of triode VT2 and the bias supply and be for VT2 turn-off reliable and stable, in order to avoid the VT2 base stage is interfered the reliability that influence is turn-offed.

LDSW is a control voltage, can directly connect the I/O mouth of CPU, because most of CPU I/O mouth before program is not moved all is a high level, so should be designed to the high level shutoff in the example, low level is opened, and makes transmitter guarantee laser shutdown when powering on.Also can be designed to low level conversely turn-offs, high level is opened, at this moment, control signal LDSW links to each other with the input pin anode of optocoupler D1, the input pin negative terminal of optocoupler D1 links to each other with control ground by resistance R 2, the output collector electrode of optocoupler D1 links to each other with laser works ground by resistance R 1, and other annexation is constant.Triode VT1, VT2 can adopt 9013, and optocoupler D1 adopts NEC PS2501, capacitor C 1=47 μ F, and resistance R 1=R2=1k Ω, R3=100k Ω, Vc1=-5V, Vc2=+5V can realize design performance well.

Claims (4)

1, a kind of optical sender laser switching circuit based on optocoupler comprises optocoupler (D1), resistance (R2), resistance (R1), electric capacity (C1), resistance (R3), triode (VT2); Control signal (LDSW) links to each other with the input pin negative terminal of optocoupler (D1), the input pin anode of optocoupler (D1) links to each other with control end power supply (Vc2) by resistance (R2), the output collector electrode of optocoupler (D1) links to each other with laser (LD) place of working by resistance (R1), the output emitter of optocoupler (D1) links to each other with the base stage of triode (VT2), the emitter of triode (VT2) connects the bias supply (Vc1) of laser (LD), the collector electrode of triode (VT2) links to each other or links to each other with the biasing input pin of laser (LD) with the emitter of the triode (VT1) of control laser optical power, between the base stage of triode (VT2) and bias supply (Vc1) and connect electric capacity (C1) and resistance (R3).

2, a kind of optical sender laser switching circuit based on optocoupler as claimed in claim 1 is characterized in that described bias supply (Vc1) generally is a negative supply.

3, a kind of optical sender laser switching circuit based on optocoupler comprises optocoupler (D1), resistance (R2), resistance (R1), electric capacity (C1), resistance (R3), triode (VT2); Control signal (LDSW) links to each other with the input pin anode of optocoupler (D1), the input pin negative terminal of optocoupler (D1) links to each other with control ground by resistance (R2), the output collector electrode of optocoupler (D1) links to each other with laser (LD) place of working by resistance (R1), the output emitter of optocoupler (D1) links to each other with the base stage of triode (VT2), the emitter of triode (VT2) connects the bias supply (Vc1) of laser (LD), the collector electrode of triode (VT2) links to each other or links to each other with the biasing input pin of laser (LD) with the emitter of the triode (VT1) of control laser optical power, between the base stage of triode (VT2) and bias supply (Vc1) and connect electric capacity (C1) and resistance (R3).

4, a kind of optical sender laser switching circuit based on optocoupler as claimed in claim 3 is characterized in that described bias supply (Vc1) generally is a negative supply.