CN2658891Y

CN2658891Y - Improved LED driving circuit structure

Info

Publication number: CN2658891Y
Application number: CNU032522835U
Authority: CN
Inventors: 徐永祥
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-09-28
Filing date: 2003-09-28
Publication date: 2004-11-24
Anticipated expiration: 2013-09-28

Abstract

The utility model relates to a structure improvement of LED driving circuit which is composed of a power supply, a rectifying circuit, a LED array and a current control circuit, wherein the output end of the rectifying circuit is communicated with the LED array. The utility model is characterized in that the current control circuit comprises two resistors and a capacitor, the two resistors are connected in the circuit in series, the capacitor is connected in parallel with one resistor among the two resistors; the LED array is connected with the capacitor in parallel, when power supply passes the current control circuit by utilizing the characteristics that the capacitor is charged and discharged, the capacitor and resistors are connected in parallel to form equivalent impedance for limiting current, and then alternating current is converted into direct current by the rectifying circuit and is outputted to the LED array, thereby providing a stable rated driving current compliance to the LED array.

Description

A kind of led drive circuit structural improvement

Technical field

The utility model relates to a kind of circuit, particularly a kind of led drive circuit structural improvement.

Background technology

Common led drive circuit by the alternating current of power supply input, needs earlier through behind the transformer buck or boost, see through rectification circuit, filtering circuit and mu balanced circuit after, alternating current is transferred in the direct current input led array, led array is switched on and luminous; Yet, not only volume is big for general transformer, Heavy Weight, add to coil combination and form, producing magnetic interference when being easy to use operates normally to other circuit, and the circuit that is used for driving LED, its output voltage size is all fixing, as 5 volts or 12 volts, and use a large amount of electronic circuits to come output DC, easily cause production cost to improve, increase manufacturing person's burden, be badly in need of being improved.

The utility model content

According to the purpose of this utility model, shortcoming at above-mentioned common led drive circuit existence, a kind of led drive circuit structural improvement is provided, it is made of power supply, rectification circuit, led array and current control circuit, the output terminal and the led array of rectification circuit link, it is characterized in that: current control circuit includes two resistance, an electric capacity, and two resistance string is associated in the circuit, and electric capacity is in parallel with one of them resistance; Described led array is parallel with an electric capacity.When power supply process current control circuit, utilize the characteristic of electric capacity charge and discharge and electric capacity equiva lent impedance current limliting in parallel with resistance, transfer alternating current to direct current via rectification circuit again and export in the led array, provide to meet the stable nominal drive current of led array; Wherein the effect of resistance has two kinds, a kind of is that collocation resistance, electric capacity are made the impedance microcall, so numerical value can be smaller, another kind of function is when supply socket is unstable, just voltage is opposite if electric capacity transient state is with input, transient flow may be flushed to very big through the electric current of electric capacity, this moment, resistance can be done a current limliting buffering of immediate current, avoided electric capacity to be damaged; Led array can be controlled luminosity difference in certain scope with the series system running, can not cause brightness disproportionation because of the different differences with impedance matching of forward bias voltage drop on its processing procedure;

Below divide alternating current and direct current to discuss respectively:

One, alternating current (50/60HZ)

Resistance, electric capacity are used as impedance matching at this, it is the working current of light emitting diode that control flows into the led array input current value, because the transient effect that the incision angle of civil power causes on electric capacity, this moment, electric capacity can be discharge loop through resistance, electric capacity can be discharge loop through led array, eliminates the influence of transient effect to circuit; Mains frequency is a half-wave behind the process bridge full-wave rectifier, if do not consider earlier the influence of electric capacity, the positive half cycle of conducting angle be θ≤positive half cycle conduction angle≤(180 °-θ), the conducting ratio of phase is (180 °-2 θ)/180 ° weekly, turn-on cycle (was considered rms voltage 110V with 90 ° of symmetries of half-wave in 1/120 second/time, 0 ° of θ=sin-1 (forward bias voltage drop total value/110)≤θ≤90 °, the total value of forward bias voltage drop equals the summation of the forward bias voltage drop of two diodes and led array).The charging and discharging effect that add electric capacity this moment again can increase conduction angle, and therefore the conducting ratio in each cycle increases, and can improve led array flicker problem, otherwise operate in negative half period also is;

Two, direct current

Can be linear power supply supply or switched power supply, can utilize superposition theorem, the power supply Composition Region is divided into flip-flop and the discussion of high-frequency harmonic composition, as impedance matching, control flows into the led array input current near the rated current of LED at this for flip-flop, resistance, electric capacity is treated as open circuit and is not considered when direct current, the current return diode of flowing through when just connecing, the current return diode of flowing through during reversal connection, direct supply is full-time conducting; The high-frequency harmonic composition, be frequency function because of electric capacity and condensance this moment, and to be higher than electric capacity too much in the impedance of resistance during high frequency, and difference will be calculated with lowest impedance more than ten times and ignore high impedance under parallel circuit, power supply is when positive loop at this moment, and loop stream is through electric capacity, diode; When bearing the loop, loop stream is through electric capacity, diode; This moment, loop load was the proportional distribution of electric capacity and electric capacity, apparent capacity value and deciding, according to the continuous i=C of voltage on the electric capacity (dvc/dt), on the electric capacity charging i when just discharging i for bearing, electric capacity can be discharge loop through resistance, electric capacity can be discharge loop through led array, and electric capacity can absorb a part of high-frequency harmonic composition energy, avoids the energy of high-frequency harmonic composition to be born by electric capacity entirely; More than two the effect addition equivalent result when being dc power supply; Wherein this power supply makes power supply directly input AC electricity or direct current owing to there is no communication elements such as using transformer in the circuit, increases the convenience when using.

Description of drawings

Fig. 1 is the circuit diagram of the utility model embodiment.

A is that power supply, B are that transformer, C are that rectification circuit, G are that led array, H are that current control circuit, I1 are that resistance, I2 are that resistance, J1 are that electric capacity, J2 are that electric capacity, K1, K2, K3 are that diode, L are light emitting diode.

Embodiment

As shown in Figure 1, the electric current of power supply A output, when positive half cycle, flow through resistance I1 and the electric capacity J2 of current control circuit H, resistance I2 again flows through, utilize series resistor I2 fine setting to reach the function that reduces electric current, among the rectification circuit C, since forward conducting of diode K1, the reverse not conducting of diode K3, and electric current is directly imported among the led array G and is flowed back to power supply A via diode K4, make the light emitting diode L energising of led array G and luminous, before led array G, connect an electric capacity J2 again, be beneficial to absorption power supply A side when power supply is unstable, pulse that is produced and protruding ripple; When negative half period, because forward conducting of diode K2, the reverse not conducting of diode K4, electric current directly flows among the led array G and flows back to power supply A through diode K2, makes light-emittingdiode L energising among the led array G and luminous; Before led array G, connect an electric capacity J2 again, be beneficial to absorption power supply A side when power supply is unstable, pulse that is produced and protruding ripple.

Advantage of the present utility model:

1, component is few, cost is low, easily manufactured;

2, must not make the communication elements such as transformer, directly input dc power;

3, transless electromagnetic interference.

Claims

1, a kind of led drive circuit structural improvement, constituted by power supply, rectification circuit, led array and current control circuit, wherein, the output terminal and the led array of rectification circuit link, it is characterized in that: current control circuit includes two resistance, an electric capacity, two resistance string is associated in the circuit, and electric capacity is in parallel with one of them resistance; Described led array is parallel with an electric capacity.

2, according to the described a kind of led drive circuit structural improvement of claim 1, it is characterized in that: said power supply is to comprise alternating current and direct current.