CN102387624B - Warm white light LED lamp with mixed three primary colors - Google Patents

Abstract

The invention belongs to the field of semiconductor illumination, and relates to a warm white light LED lamp with mixed three primary colors. The warm white light LED lamp comprises a blue light LED, a red light LED, and a circuit used for stabilizing color temperature, wherein yellow phosphor powder is coated in the tube core of the blue light LED; the blue light LED and the red light LED are serially connected and then connected between the positive electrode and the earthing terminal of a power supply; the circuit for stabilizing color temperature comprises a first triode and a second triode; the emitting electrode and the collecting electrode of the first triode are connected between the negative electrode and the earthing terminal of the red light LED; a negative temperature coefficient thermistor R4 is connected between the base electrode of the first triode and the negative electrode of the red light LED; the emitting electrode and the collecting electrode of the second triode are serially connected with a bypass resistor R1 and then connected between the negative electrode and the earthing terminal of the blue light LED; a positive temperature coefficient thermistor R5 is connected between the negative electrode of the red light LED and the base electrode of the second triode; and a negative temperature coefficient thermistor R7 is connected between the base electrode and the earthing terminal of the second triode. The invention can ensure the stable color temperature of the warm white light LED illumination product from the starting to the stable state.

Description

A kind of Warm white light LED lamp with mixed three primary colors

Affiliated technical field

The present invention relates to field of semiconductor illumination, relate in particular to a kind of three primary colors and mix warm white LED.

Background technology

Along with the continuous progress of GaN sill epitaxy technology, the ruddiness of high brightness, blue light and more the performance of short wavelength's light-emitting diode (LED) obtained significant progress, commercial LED has covered the whole wave band from ruddiness to the ultraviolet light.The present the most conventional solution of realization white-light emitting LED that is used for is that the GaN base blue-ray LED tube core that utilizes of being realized by people such as Nakamura in 1997 adds the yellow fluorescent powder that a small amount of yttrium-aluminium-garnet is the master, makes the blue light part excitated fluorescent powder of emission send gold-tinted and blue light generation white light.The advantage of the method is technology maturation, and electrology characteristic, optical characteristics are stablized, and cost is lower than other solution.So almost used commercialization LED illuminating product all is to use this kind LED luminescence chip.(blue-ray LED described in the following content of specification all refer to this type of scribbles fluorescent material, the blue-ray LED of the white light that feels cold)

White light can be divided into warm white (colour temperature 2700K CCT) LED and cold white light (colour temperature 6000K CCT) LED.This Advanced Idea of warm white is taken the lead in proposing by world-renowned Illumination Enterprise PHILIPS Co., and is widely applied in states such as the U.S., Britain, Belgium, Norway.With respect to gold-tinted, cold white light, warm white has higher colour temperature, and better color rendering closer to the expression effect of sunlight, gives warm impression at heart.Warm white is all abundanter in green spectral and blue portion spectrum, and warm white is along with the increase of distance, and Color discrimination is clearer.Under equal vertical illumination level, people are easy to distinguish the characteristics of object and surrounding enviroment color under warm white.From 2009, the Philip began to widely popularize the warm white LED illumination.General Electric, Ou Silang begin to promote subsequently in succession, and the warm white LED illumination will become the inexorable trend of semiconductor lighting development.The research and development of warm white illumination also are the only way which must be passed that domestic Illumination Enterprise goes to the world.

Utilize suitable ratio mixing blue light, gold-tinted, ruddiness three primary colors can allot the warm white of 2700K CCT, the adding of ruddiness can make cold white light partially warm, and colour temperature reduces.So connect use with red-light LED in the LED lighting with the above-mentioned blue-ray LED that scribbles yellow fluorescent powder, can reach the purpose of sending warm white.This kind warm white has higher lumen output and luminous efficiency.But blue-ray LED is different because of material with red-light LED, and energy gap is different, so luminous color is different, institute's energy requirement is just different certainly, and namely their forward conduction voltage drop is different.Blue light wavelength is shorter than ruddiness, and the energy that light needs is large, so the blue-ray LED cut-in voltage is large.Under same forward conduction electric current, the colour temperature of blue-ray LED and red-light LED becomes different functional relations from temperature in the light fixture.Because red-light LED changes more obvious in the different temperatures colour temperature, after the warm white LED light fixture starts, temperature is risen to about 90 degree by 25 degree, colour temperature is from the 2100K climbed to 2700K, and need 25 to 30 minutes, this time is decided by the heat radiation level of light fixture, and colour temperature changes so for a long time, understand lighting quality, particularly room lighting and special lighting mass formation adverse influence.How to allow the warm white LED illuminating product start in the stable time, colour temperature is less with respect to the 2700K amplitude of variation, is in the future high-quality LED illumination institute problem needing to overcome.

Summary of the invention

The object of the present invention is to provide a kind of warm white LED illuminating product that can make starting to the stable circuit of colour temperature in the time of stable state.The technical solution adopted in the present invention is:

A kind of Warm white light LED lamp with mixed three primary colors, comprise blue-ray LED and red-light LED and the circuit that is used for stable color temperature, scribble yellow fluorescent powder in the tube core of described blue-ray LED, be connected between positive source and earth terminal after blue-ray LED and the red-light LED series connection, the circuit of described stable color temperature comprises the first triode and the second triode, the emitter and collector of the first triode is connected between the negative pole and earth terminal of red-light LED, is connected to negative tempperature coefficient thermistor (R4) between its base stage and the red-light LED negative pole; The emitter and collector of the second triode be connected between the negative pole and earth terminal of blue-ray LED after bypass resistance (R1) is connected, between the negative pole of red-light LED and the second transistor base, be connected to semistor (R5), between the base stage of the second triode and earth terminal, be connected to negative tempperature coefficient thermistor (R7).

As preferred implementation, the current gain of described two triodes is identical with base-emitter voltage.

In the process of stable state, by the effect of by-pass current, the electric current that makes red-light LED is to rise gradually from small to large until thermally-stabilised after LED lights in the present invention, reaches the whole lamp color temperature of LED and changes very little purpose.

Description of drawings

Fig. 1 is circuit theory diagrams of the present invention.

Fig. 2 is the actual colour temperature variation diagram that the warm white LED illumination starts after this employing invention.

Embodiment

Below in conjunction with accompanying drawing, further describe the present invention by embodiment.

As shown in Figure 1, Warm white light LED lamp with mixed three primary colors of the present invention, comprise blue-ray LED and red-light LED and drive circuit thereof. triode Q1 grounded emitter in the drive circuit, base stage is divided into two-way behind R4NTC: the one tunnel connects the collector electrode of triode Q1, two-way is divided again in another road after resistance R 6 and R5PTC series connection, one the tunnel connects the base stage of triode Q2, and another road is through resistance R 7NTC ground connection; The collector electrode of triode Q1 divides two-way: the one tunnel connects the base stage of triode Q1 through resistance R 4NTC, and another road connects the negative pole of red-light LED 2.The grounded emitter of triode Q2, its base stage is through R7NTC ground connection; The collector electrode of triode Q2 divides two-way again after resistance R 2, R3 and R1 series connection, the one tunnel connects the positive pole of red-light LED 2, and another road connects the negative pole of the blue-ray LED 1 that scribbles yellow fluorescent powder and feel cold white light.The positive pole of blue-ray LED 1 connects the output plus terminal of drive circuit.In order to ensure the accuracy of current mirror, Q1 and Q2 adopt and are integrated in a pair transistor device in the encapsulation, such as SO8.The currentgainβ of Q1 and Q2, V _BeConsistent Deng electrical parameter.

Operation principle of the present invention is as follows:

The basic current-mirror structure that connects and composes of Q1 as shown in Figure 1, Q2, the parameter of Q1, Q2 is identical, β 1=β 2=β, and two or three utmost point pipe has identical base-emitter voltage Vbe.The total output current (Iin) of drive circuit all flows through blue-ray LED 1, and (size is I _Blue) after, be divided into two-way: the one tunnel flows through red-light LED 2, and size of current is Ired; Another road is through R1, R3, and R2 flows into the collector electrode of Q2, is called as by-pass current, and size is Ibypass.The relation of Ired and Ibypass is shown in (1) formula.For triode Q1, emitter current Ired equals β times of its base current, shown in (2) formula.For triode Q2, emitter current Ibypass equals β times of its base current, shown in (3) formula.Because β is identical, comprehensive (2), (3) formula can draw respectively the electric current I red, the by-pass current Ibypass that flow through red-light LED 2 and the relation of driver output electric current I in, shown in (4) formula, (5) formula.Can find out, after the LED lighting started, the output current Iin of drive circuit had all flow through blue-ray LED 1, does not but all flow through red-light LED 2, but red-light LED 2, i.e. Ired＜Iblue=Iin have partly been flowed into through the residual current after the by-pass current Ibypss shunting.This moment red-light LED 2 the secretly brightness after stable of brightness, to the contribution of colour temperature less than 50%.Rising along with the temperature of lamp interior environment, the resistance value of negative tempperature coefficient thermistor R4 reduces gradually, the resistance of the thermistor R5 of positive temperature coefficient increases gradually, then can be found out by (4) formula, (5) formula, the electric current I red that flows through red-light LED 2 increases gradually, and by-pass current Ibypass reduces gradually.The brightness of red-light LED 2 reaches the brightness after stable gradually, and the contribution of colour temperature is tending towards 50%.In stable 25 minutes of light fixture, the process that red-light LED 2 brightens has gradually been stablized and the mixed light fixture light of blue-ray LED output colour temperature, the colour temperature variation diagram as shown in Figure 2, rate of change only is 1.22%.

I _red+I _bypass＝I _in＝I _blue (1)

$\mathrm{\β}\·\frac{V_1-V_{\mathrm{be}}}{R_{4\left(\mathrm{NTC}\right)}}=I_{\mathrm{red}}---\left(2\right)$

$\mathrm{\β}\·\frac{V_1-V_{\mathrm{be}}}{R_{5\left(\mathrm{PTC}\right)}+R_6}=I_{\mathrm{bypass}}---\left(3\right)$

$I_{\mathrm{bypass}}=\frac{R_{4\left(\mathrm{NTC}\right)}}{R_{4\left(\mathrm{NTC}\right)}+R_{5\left(\mathrm{PTC}\right)}+R_6}\·I_{\mathrm{in}}---\left(4\right)$

$I_{\mathrm{red}}=\frac{R_{5\left(\mathrm{PTC}\right)}+R_6}{R_{4\left(\mathrm{NTC}\right)}+R_{5\left(\mathrm{PTC}\right)}+R_6}\·I_{\mathrm{in}}---\left(5\right)$

Claims (2)

1. Warm white light LED lamp with mixed three primary colors, comprise blue-ray LED and red-light LED and the circuit that is used for stable color temperature, scribble yellow fluorescent powder in the tube core of described blue-ray LED, be connected between positive source and the earth terminal after blue-ray LED and the red-light LED series connection, it is characterized in that, the circuit of described stable color temperature comprises the first triode and the second triode, the emitter and collector of the first triode is connected between the negative pole and earth terminal of red-light LED, is connected to negative tempperature coefficient thermistor (R4) between its base stage and the red-light LED negative pole; The emitter and collector of the second triode be connected between the negative pole and earth terminal of blue-ray LED after bypass resistance (R1) is connected, between the negative pole of red-light LED and the second transistor base, be connected to semistor (R5) and resistance (R6), between the base stage of the second triode and earth terminal, be connected to negative tempperature coefficient thermistor (R7).

2. Warm white light LED lamp with mixed three primary colors according to claim 1 is characterized in that, the current gain of described two triodes is identical with base-emitter voltage.

Images