CN201797620U

CN201797620U - Driving circuit for long-life LED electric torch

Info

Publication number: CN201797620U
Application number: CN2010201673966U
Authority: CN
Inventors: 李建
Original assignee: CHENGDU SURESUN TECHNOLOGY Co Ltd
Current assignee: CHENGDU SURESUN TECHNOLOGY Co Ltd
Priority date: 2010-04-20
Filing date: 2010-04-20
Publication date: 2011-04-13
Anticipated expiration: 2020-04-20

Abstract

The utility model relates to an LED electric torch, in particular to a driving circuit for a long-life LED electric torch. One thermistor or a plurality of thermistors with positive temperature coefficients, a plurality of triodes and a plurality of parallel LEDs are connected in series into an LED loop to form a standard unit. Compared with an original LED loop, after the thermistors with positive temperature coefficients are connected in series into the LED loop, current of the LED loop tends to be constant along with rise of temperature, the driving circuit solves the problems that resistance of each LED is gradually reduced and the current is gradually increased as the temperature of the LED rises, integral service life of the LED electric torch is prolonged, and the circuit is concise, is low in cost, is suitable for industrial production in large scale, and can be manufactured into a standard module.

Description

A kind of drive circuit of long-lived LED flashlight

Technical field

The utility model relates to a kind of LED flashlight, especially a kind of drive circuit of LED flashlight of longevity.

Background technology

The LED flashlight all is a direct driving LED after cell voltage is boosted at present, and this circuit has simple in structure, low cost and other advantages.But since LED at work temperature raise gradually, resistance diminishes gradually, electric current increases gradually, the speed that LED heats up has been accelerated in the increase of electric current again, LED just is in the operational environment of a vicious circle like this, significantly reduced the useful life of LED flashlight, the advantage of LED flashlight longevity is not in full use.

Summary of the invention

Raise in order to overcome temperature, resistance diminishes gradually, and electric current increases gradually, influence to the existing LED flashlight life-span, the utility model provides a kind of constant improvement circuit of circuital current that makes, and the operating current of LED flashlight is stablized, and increases the useful life of LED flashlight greatly.This LED flashlight circuit is simple and easy, the small and exquisite saving cost of volume, and dependability but greatly improves.

The technical scheme that its technical problem that solves the utility model adopts is: the resistance at LED can reduce along with the rising of ambient temperature, cause that the LED current in loop becomes big, influenced the shortcoming in LED flashlight life-span greatly, we adopt the LED series connection of or the thermistor of many positive temperature coefficients, several triodes, several parallel connections, form an element loop.Behind the one or more semistors of series connection, it is constant that the all-in resistance of led circuit is trended towards, and the electric current in LED loop is almost remained unchanged, and increases the useful life of LED flashlight greatly in the LED loop.

As shown in Figure 1: its continuous current 100mA, operating voltage U=VR+VF=0.65V+3.4V=4.05V, 0.65V the pressure drop when being 25 ℃ of MZD-5B100 resistance, 3.4V be the forward conduction voltage (or 2.8V-4.2V) of LED, when 1 ℃ of the every rising of ambient temperature, the VF decline 2mV of LED, 5B100 pressure drop rising 2mV has kept the total current in the series loop constant.

Concrete technical measures as shown in Figure 1, the positive pole of this drive circuit power supply E connects an end of K switch, the e end of another termination triode VT1 of described K switch and the left end of inductance L, the right-hand member of described inductance L connects an end of capacitor C 1, the c end of triode VT2 and the end of semistor R3, the thermistor R3 of described positive temperature coefficient connects the anode by the LED of many parallel connections, the negative terminal of described parallel connection LED circuit connects the e end of triode VT2, one end of described resistance R 1 and the negative pole of power supply E, the other end of another termination capacitor C 1 of described resistance R 1 and the b of triode VT1 end, the end of the c terminating resistor R2 of described triode, the b end of another termination triode VT2 of described resistance R 2.

The beneficial effects of the utility model are: the thermistor good stability of positive temperature coefficient, and highly sensitive, solved the LED temperature and raise, the LED resistance diminishes gradually, and electric current increases gradually, the harmful effect that the LED flashlight life-span is caused; Improve the operational environment of LED, improved the bulk life time of LED flashlight.The utility model circuit is succinct, with low cost, and suitability for mass industrialized production can be made standard module.

Description of drawings:

Below in conjunction with drawings and Examples the utility model is further specified.

Fig. 1 is circuit theory diagrams of the present utility model.

Fig. 2 is embodiment of the present utility model and the LED flashlight experimental data comparison diagram that does not add semistor.

Embodiment:

Supply voltage E=1.5V, inductance L=0.1mH, C1=1 μ F, R1=10K ohm, R2=100 ohm, R3 are the thermistor (as MZD-5b100) of positive temperature coefficient, VT1 is PNP triode (as 9015 triodes), and VT2 is NPN triode (as 9014 triodes).Repeatedly after the experiment, can draw experimental data T---the I comparison diagram, as shown in Figure 2, compare with original circuit after in circuit, adding just warm quick resistance, along with its electric current of rising of temperature is tending towards constant, LED is in more works in the stable status, increased the useful life of LED so greatly.

The thermistor of the positive temperature coefficient in the present embodiment also can be selected the thermistor of the positive temperature coefficient of other models for use.

Triode in the present embodiment also can be selected other NPN types and positive-negative-positive triode for use.

Claims

1. the drive circuit of a long-lived LED flashlight, the thermistor of the positive temperature coefficient that it is characterized in that in the LED loop, having connected.

2. the LED flashlight drive circuit of a kind of longevity according to claim 1, it is characterized in that the positive pole of power supply E connects an end of K switch, the e end of another termination triode VT1 of described K switch and the left end of inductance L, the right-hand member of described inductance L connects an end of electric capacity ℃ 1, the c end of triode VT2 and the end of semistor R3, the thermistor R3 of described positive temperature coefficient connects the anode by the LED of many parallel connections, the negative terminal of described parallel connection LED circuit connects the e end of triode VT2, one end of described resistance R 1 and the negative pole of power supply E, the other end of another termination capacitor C 1 of described resistance R 1 and the b of triode VT1 end, the end of the c terminating resistor R2 of described triode, the b end of another termination triode VT2 of described resistance R 2.