WO2006005239A1

WO2006005239A1 - A lighting circuit of light emitting diodes

Info

Publication number: WO2006005239A1
Application number: PCT/CN2005/000219
Authority: WO
Inventors: Daming Lv; Zhou Lv
Original assignee: Daming Lv; Zhou Lv
Priority date: 2004-07-15
Filing date: 2005-01-11
Publication date: 2006-01-19

Abstract

A lighting circuit of light emitting diodes powered by AC current is disclosed. The basic configuration of the lighting circuit is composed of a light emitting diode array and an AC-DC rectifier circuit, and the DC output of the AC-DC rectifier circuit is connected to the light emitting diode array. According to physical circumstances, the basic circuit can be changed to include a constant current source circuit, a filter circuit, a power factor correction circuit and so on all of which can be implemented by simple discrete elements.

Description

LED lighting circuit

[Technical Field]

The present invention relates to an illumination circuit that uses AC power, and more particularly to an LED illumination circuit that uses AC power. 【Background technique】

At present, the illuminating devices commonly used in the field of commercial lighting mainly include incandescent lamps and fluorescent lamps. Incandescent lamps have been gradually eliminated due to high heat generation, and fluorescent lamps have short lifespans and complicated structures, so the cost of use is high. Light-emitting diodes (LEDs) are gaining more and more attention in this field due to their high efficiency, energy saving and long life.

Existing drive circuits that use ordinary AC power (such as AC 220V power grid, AC 120V power grid, etc.) to supply LEDs can be roughly divided into two cases: One is through traditional AC voltage transformation, rectification, and series voltage regulation. The other part is to obtain DC drive; the other is to use the more advanced switching power supply to directly generate the required DC regulated power supply. The former has disadvantages such as high cost, high energy consumption, and heavy weight because of the use of transformers and the like. The latter is more common, and although it has low energy consumption, the structure is complicated and the cost is high.

At present, research on LED lighting applications mainly focuses on two aspects. One is a high-stability switching circuit, which aims to provide a stable and pure current for LEDs. Judging from the results achieved, the results in this area have been quite rich and excellent. At the beginning of the application of LEDs, due to its high cost and the small amount of use (generally single or several LEDs are used at the same time), it is almost necessary to use a power supply to provide a stable current. Put a lot of manpower and resources into the cause of this research. However, in reality, as the cost of manufacturing LEDs rapidly decreases, the high cost of using switching circuits is becoming the biggest obstacle to the popularity and promotion of LEDs in the field of lighting. It is no exaggeration to say that the pursuit of switching power supply has become a misunderstanding of LED lighting research.

Another aspect is to increase the amount of illumination of a single LED. Conventionally produced LED tubes are generally "single-die" products. Single-die LEDs come in a variety of configurations, usually in-line, patch, etc., and the positive and negative poles of the die on the substrate are respectively passed. The pure gold wire is connected to the protruding pin on the bracket. There are generally at least two lead pins on the electrical connection of the LED, one being the positive pole of the LED and the other being the negative pole. Increasing the amount of LED illumination is a common pursuit in the industry. There are two options: First, to improve the luminous efficiency of the die material, to achieve greater luminous flux under the condition of constant current I _F. This is the main direction of current research and development. However, it is still a arduous road, and has a long way to go; the second is to expand the area of a single LED die, and through more I _F , to achieve more lighting. However, this solution brings a lot of technical problems. In addition to heat dissipation, it will also lead to: 1. Light efficiency is reduced. At present, the single-power efficiency of small-power LED can reach 40 lm/W or more, and the area of the die is enlarged. _{After F} , the light efficiency drops to 25 1m W or even less than 15 1m W! And the light effect will increase the heat, which makes the heat dissipation problem more prominent. 2. The area of the die is increased, the current density is more difficult, and the die is easily caused. The current is too large and too hot to decay early, which greatly reduces the overall life of the LED. At present, there are also "multi-die" LED products, which are loaded with two or more LED dies in an LED tube equivalent to parallel connection. This type of product is mainly used for "one tube multi-color". The occasion. The multi-die LED and the single-core tube are not substantially different in structure, and each of the individual dies is connected to the lead of the bracket through the gold wire, and the individual dies are independent of each other. Such tubes typically have more than two legs that can be individually controlled for each die. This kind of circuit structure can't really be integrated, and because it is a parallel connection, its working voltage is no different from single-core tube, and the more the number of cores, the higher the current requirement, and the other control pins. The increase will also bring difficulties to the process and design.

[Summary of the Invention]

The technical problem to be solved by the present invention is to provide an LED lighting circuit which is low in energy consumption, simple in structure, low in cost, long in service life, and suitable for being powered by an AC power source, compared with the existing lighting technology.

In order to solve the above technical problem, the first technical solution of the present invention is: A light-emitting diode lighting circuit comprising an LED array and an AC-DC rectifier circuit, wherein the DC output of the AC-DC rectifier circuit is connected in series with the LED array. The term "light-emitting diode array" as used in the present invention means: a basic column is formed by one or more LED units connected in series, and one such basic column or more than one such basic column is connected in parallel to form an array of light-emitting diodes. At the same time, the LED units in the different columns can also be laterally connected to make the LED array have a grid-like junction. Structure. The light emitting diode unit may be a single LED or a combination of several LEDs having the above array structure. In a light-emitting diode array, different structural forms of different light-emitting diode units can be used as needed.

The technical solution of the present invention is: an LED lighting circuit comprising an LED array, an AC-DC rectifier circuit and a constant current source circuit, a DC output series constant current source circuit and an LED array of the AC-DC rectifier circuit.

The third technical solution of the present invention is: A light-emitting diode lighting circuit comprising an LED array, an AC-DC rectifier circuit and a filter circuit, a DC output parallel filter circuit and an LED array of the AC-DC rectifier circuit.

The fourth technical scheme of the present invention is: a light-emitting diode lighting circuit, which is composed of an LED array, an AC-DC rectifier circuit, a constant current source circuit and a filter circuit, and a DC output parallel filter circuit of the AC-DC rectifier circuit and a series constant current source circuit. And an array of light emitting diodes.

The fifth technical scheme of the present invention is: an LED lighting circuit, which is composed of an LED array, an AC-DC rectifier circuit, a power factor correction circuit and a filter circuit, and the power factor correction circuit is connected to the AC input of the DC rectifier circuit, and the AC-DC rectifier The circuit's DC output parallel filter circuit and LED array.

The sixth technical solution of the present invention is: an LED lighting circuit, which is composed of an LED array, an AC-DC rectifier circuit, a power factor correction circuit, a constant current source circuit and a filter circuit, and the power factor correction circuit is connected to the DC rectifier circuit for communication. Input, the DC output parallel filter circuit of the AC-DC rectifier circuit is connected in series with the constant current source circuit and the LED array.

The AC-DC rectifier circuit in the foregoing scheme may preferably be a rectifier bridge composed of a crystal diode.

The constant current source circuit in the foregoing solution may preferably have such a structure: including a triode serving as a driving current adjusting tube, the emitter is connected in series with a current limiting feedback resistor, and is connected in parallel with the base series Zener diode as a terminal of the constant current source circuit. The collector is used as the other end of the constant current source circuit, and the base series base bias resistor is connected between any two adjacent light emitting diodes in any column of the LED array. Among them, the Zener diode can be replaced by one or more diodes connected in series.

The power factor correction circuit of the foregoing scheme may preferably include an inductance in series with the AC input of the AC and DC rectifier circuit. The filter circuit in the foregoing scheme may preferably filter the capacitor. The light-emitting diodes in the LED array of the foregoing solution preferably use an integrated die, that is, to integrate at least two-stage dies in series on one LED substrate, the dies of the stages being single dies or by multiple The individual dies are constructed by series or parallel connection or series-parallel hybrid connection. The series connection of the dies of the stages preferably has a structure in which the surface contacts of the positive and negative levels are closely arranged.

The beneficial technical effects of the present invention are as follows: 1) A scheme of directly illuminating a direct current light emitting diode array by using an alternating current power source, and fully utilizing the advantages that the series light emitting diode unit can adapt to a certain voltage variation range and the city network is relatively stable, The ability to generate sufficient brightness for illumination eliminates the need for complex and expensive switching power supplies, greatly simplifies the circuit and reduces cost; 2) uses a grid-like structure with horizontal connections between the columns in the LED array to improve The stability of the circuit; 3) using a constant current source to further reduce the stability requirements of the power supply, in the poor power supply area can ensure the relative stability of the LED operating current, so that the LED has a longer service life; 4) The power factor correction circuit can improve the current quality and reduce the loss at high power output. 5) The rectifier circuit, the constant current source circuit, the power factor correction circuit and the filter circuit can be realized by a simple structure with inexpensive discrete components. The invention has the advantages of simple structure and low cost; 6) The integrated form of LED dies can be easily standardized by the selection of the number and type of integrated dies to suit different applications; 7) using closely arranged surface contacts In series, omitting the connection line, not only simplifies the process and design, but also makes the wire connection more reliable, less lossy and more stable; 8) The integrated color of each die can be properly proportioned, that is, in an extremely economical way Obtaining "white LED" not only bypasses the patented technology blockade of other countries but also avoids the disadvantages of low lifetime and easy attenuation of phosphors. At the same time, because the monochromatic cores are closely connected in series, they can stay away from the observation surface. The light source quickly achieves a good white light effect, which is economical and practical; 9) Due to the extremely high reliability of semiconductors (over one million hours), the service life is long (more than 10 times that of existing light sources). The invention completely jumps out of the application field of the LED in the field of light-emitting diodes, and opens up a brand-new development idea, which has broad application prospects and has significant advantages compared with the existing lighting solutions.

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. 1(a) to (f) are schematic diagrams of basic circuits of the present invention;

Figure 2 is a preferred embodiment of Figure 1 (a);

Figure 3 is a preferred embodiment of Figure 1 (b);

Figure 4 is a preferred embodiment of Figure 1 (c);

Figure 5 is a preferred embodiment of Figure 1 (d);

Figure 6 is a diagram of a preferred embodiment of e;

Figure 7 is a preferred embodiment of Figure 1 (f);

Figure 8 is a schematic diagram of the structure of a three-stage series LED integrated die.

Fig. 9 is a schematic view showing the structure of an integrated multi-stage series LED integrated die.

Figure 10 is a schematic diagram of the structure of a multi-stage series LED integrated die.

Figure 11 is a schematic diagram showing the structure of a multi-stage series-stage parallel LED integrated die.

【detailed description】

Embodiment 1 LED light-emitting circuit 1 , in combination with FIG. 1( a ) and FIG. 2 , the m columns are connected in parallel by a series of n light-emitting diodes LED-ji ( l ^j^m, l ^i^n) The array of light emitting diodes is formed, while the lateral connection between the light emitting diodes in different columns allows the array of light emitting diodes to have a grid-like structure. The array of light emitting diodes is connected in series between the DC output terminals of the AC/DC rectifier circuit Q. The AC-DC rectifier circuit is a rectifier bridge composed of four crystal diodes, and a pair of non-adjacent connection points are input ends, respectively connected to two ends of the AC power source AC, and the other pair of connection points are DC output ends.

In this example, since the array of light-emitting diodes has a grid-like structure, the circuit has better stability, and when a single light-emitting diode is damaged, it does not have a large influence on the entire array.

Embodiment 2: LED lighting circuit 2, in combination with FIG. 1(b) and FIG. 3, the m columns are composed of n LEDs connected in series by LED-ji (l^j^m, l^i^n) LED array. The DC output end of the AC-DC rectifier circuit Q is connected in series with the LED array and the constant current source circuit. The specific structure is: AC power supply AC is connected to a pair of connection points of the rectifier bridge Q composed of four diodes, and the other pair of connection points of Q is used as a DC output; One end of the array is connected to one DC output end of the Q, and the other end is connected to the collector of the triode T. The emitter of the T is connected in series with a current limiting feedback resistor Re, and the two diodes D1 and D2 are connected in series with the base of the T, and the Q is connected. Another DC output terminal; the base of T is connected in series with a base bias resistor Rb and is connected between two adjacent LEDs in the LED column.

In this example, the constant current source circuit can be used in the circuit when the power supply is unstable (for example, in rural areas where the grid stability is poor, and the instantaneous fluctuations caused by the switching of high-power electrical equipment in the power grid). Current stability. The applicant found through experiments that in the case that the voltage of the city grid is relatively stable (the fluctuation is less than 10%), the voltage fluctuation in the LED array circuit adjusted by the constant current source circuit is only between 0.3~1V, in the light-emitting diode In the case where the array uses a considerable number of light-emitting diodes, such a range of voltage fluctuations does not have a substantial impact at all, so in practice the use of a constant current source is not necessary, and a circuit scheme implementing one can achieve good results.

Embodiment 3, LED lighting circuit 3, in combination with FIG. 1 (c) and FIG. 4, the structure is compared with the first embodiment, n high-brightness white LEDs LED-i ( l ^ n) are connected in series to replace the implementation The grid-like LED array in Example 1 adds a filter capacitor C connected in parallel between the DC output terminals of the rectifier circuit Q.

In this example, a filter capacitor is used as the filter circuit to compensate the phase difference of the rectifier bridge and obtain a better output waveform. The number of series LEDs in the LED array is 1~260, and the specific number N can be determined by the following method.

N=Int (DCV/Vf)

Int indicates that the result is rounded, Vf is the nominal voltage value of the light-emitting diode, 1.8-2.2V for yellow and red light-emitting diodes, and 3.0 3.4V for green and white light-emitting diodes.

DCV=ACV* V 2~*K

Among them, ACV is the nominal central value of the national (local) city power grid, for example, 220V for China and 110V for the United States; K is an empirical parameter, generally 0.8, can also pass experiments, such as increasing or decreasing the actual series of LEDs The number makes it glow normally, and then the experimental result and the specific voltage value are determined by the above formula.

The fourth embodiment, the light emitting diode lighting circuit is four, in conjunction with FIG. 1 (d) and FIG. 5, the structure of the second embodiment compared to, _n-th light emitting diode LED-i (lin) in series into one substituent multiple second embodiment of the Column parallel LED array, will be two The poles D1 and Ό2 are replaced by a Zener diode D, and the filter capacitor connected in parallel between the DC output terminals of the rectifier circuit Q is added. .

In this example, the Zener diode D is used instead of the diodes D1 and D2 connected in series to provide a very stable reference voltage for better constant current effect. However, a common diode can be used to select a wide reference voltage. Range, lower voltage and larger control range than Zener diodes. Both methods have their own advantages and can be selected according to actual conditions.

Embodiment 5, LED lighting circuit 5, in combination with FIG. 1 (e) and FIG. 6, the structure is compared with the third embodiment, and an inductance input as a power factor correction circuit is also connected in series at an AC input end of the AC/DC rectification circuit Q. Coil L1.

In this example, an inductive coil is used as a Power Factor Correctors (PFC) circuit. This method is called passive or called "passive" power factor correction, and the power is not very large (about less than 400W). There are good results. Other types and structures of power factor correction circuits can be selected as needed, such as power factor correction chips that are active or called "active".

Embodiment 6 LED light-emitting circuit 5, in combination with FIG. 1 and FIG. 7, the structure is compared with the fourth embodiment, and the two-input input terminals of the AC-DC rectifier circuit Q are respectively connected in series with the inductor L1 as a power factor correction circuit. And L2.

In this example, the inductors are connected to the two AC inputs of the rectifier circuit Q, respectively, for better power factor correction.

Embodiment 7 The LED lighting circuit using the integrated die, in combination with FIG. 7 and FIG. 8, has the same circuit structure as that of Embodiment 6, and the LED in the array has the integrated die shown in FIG. The structure is: on the substrate substrate 1, the three LED dies 2, 3, 4 are closely arranged in a positive and negative connection with each other, a is the anode of a single dies, b is a negative electrode, and c is illuminating Body part. Each of the individual dies is individually connected in series, and the positive and negative ends of the dies 4 and 2 are electrically connected to the positive and negative electrodes B of the substrate, respectively.

According to such a structure, more single dies can be connected in a multi-stage series of in a shape or a wrap, as shown in FIG. 9 and FIG. 10 (5 is an electrical connecting substance in FIG. 10), and of course other can be performed. The arrangement of shapes. Multi-level tandem junction The dies in each stage of the structure are single dies, and the stages in series can also be connected in parallel. For example, the stages are composed of two single dies in parallel, as shown in Fig. 11, of course, partial stages can also be used. It is constructed in a parallel configuration, while the partial stage still uses the structure of a single die. This structure in which a plurality of LED dies are mounted/manufactured in a multi-stage series on a common substrate can obtain a required higher forward voltage V _F , so that in the case of equivalent power, A small forward current I _F , at the same time, can also achieve a good white LED effect by matching the color of the integrated single die.

The integrated implementation can be arranged to integrate several required individual LED dies in a multi-stage series structure after the individual LED dies are produced to produce an equivalent high V _F LED integrated die; the process can also be advanced into the production process of a single LED die, for example for a single type of LED or for LEDs using the same semiconductor base material, the implementation of the invention can be in doping, masking, etc. This is done in the early stages of the process, which simplifies the subsequent processes and costs.

The number of integrated dies can be determined according to the standardization requirements of the operating voltage. For example, when used for train illumination, the supply voltage is 24V, then a white-light nine-stage series LED integrated dies can be selected, and the nine dies are respectively Repeat the order of "red (R), green (G), blue (B)", because the operating voltage of each color die is V _FR =1.6~2.4V, V _FG =2.8~4.0V, V _FB = 2.8~4.0V, so an integrated LED of this structure can be easily connected directly to the train's power supply like the commonly used train lighting, providing stable and economical white light illumination. When there is individual damage in the die, if it is short-circuit damaged, it will not affect the normal operation of other dies. Only the open circuit damage will lead to the overall failure, and the high reliability and long life based on LED, even if there is considerable In the case of high integration, the probability of failure is also small.

Claims

Rights request

1. A light-emitting diode lighting circuit, characterized in that: the light-emitting diode array and the AC-DC rectifier circuit are formed, and the DC output of the AC-DC rectifier circuit is connected to the LED array.

2. An LED lighting circuit, characterized by: an LED array, an AC-DC rectifier circuit and a constant current source circuit, a DC output series constant current source circuit and an LED array of the AC-DC rectifier circuit.

3. An LED lighting circuit, characterized by: an LED array, an AC-DC rectifier circuit and a filter circuit, a DC output parallel filter circuit and an LED array of the AC-DC rectifier circuit.

4. A light-emitting diode lighting circuit, characterized in that: the light-emitting diode array, the AC-DC rectifier circuit, the constant current source circuit and the filter circuit, the DC output parallel filter circuit of the AC-DC rectifier circuit, the series constant current source circuit and the light-emitting Diode array.

5. An LED lighting circuit, characterized in that: the LED array, the AC-DC rectifier circuit, the power factor correction circuit and the filter circuit are formed, the power factor correction circuit is connected to the AC input of the DC rectifier circuit, and the AC-DC rectifier circuit is DC output parallel filter circuit and LED array.

6. An LED lighting circuit, characterized in that: the LED array, the AC-DC rectifier circuit, the power factor correction circuit, the constant current source circuit and the filter circuit are formed, and the power factor correction circuit is connected to the AC input of the DC rectifier circuit. The DC output parallel filter circuit of the AC-DC rectifier circuit is connected in series with the constant current source circuit and the LED array.

The LED lighting circuit according to any one of claims 1 to 6, wherein the AC/DC rectification circuit is a bridge rectifier circuit composed of a diode.

The LED lighting circuit according to any one of claims 2, 4 or 6, wherein: said constant current source circuit comprises a triode for driving a current regulating tube, and an emitter series current limiting feedback resistor After being connected in series with the base diode, the diode is connected in parallel as one end of the constant current source circuit, and the collector is used as the other end of the constant current source circuit, and the base series base bias resistor is connected to any column of the LED array. Between two adjacent light emitting diodes.

9. The LED lighting circuit of claim 8, wherein: said Zener diode is replaced by one or more diodes connected in series.

10. The LED lighting circuit of claim 5 or 6, wherein: said power factor correction circuit comprises an inductor in series with an AC input of the AC to DC rectifier circuit.

The LED lighting circuit according to any one of claims 3 to 6, wherein the filter circuit is a filter capacitor.

The LED lighting circuit according to any one of claims 1 to 6, wherein: the LED in the LED array adopts an integrated die, that is, integrated in series on at least one LED substrate. The two-stage dies are formed by a single dies or by a plurality of single dies connected in series or in parallel or in series and parallel.