CN101360371A - Power supply circuit of light emitting diode - Google Patents

Abstract

The invention relates to a power supply circuit of a light emitting diode, which comprises a stabilizer, a voltage doubling circuit and a constant current circuit, wherein the stabilizer is used for converting the frequency of an alternating current power supply and generating an alternating current voltage, the voltage doubling circuit is used for receiving the alternating current voltage and rectifying the alternating current voltage to output a direct current voltage, the constant current circuit is used for receiving the direct current voltage and outputting a stable current to the light emitting diode, the alternating current voltage can be rectified through the voltage doubling circuit, a larger direct current voltage can be generated at the same time, the output quality of the alternating current voltage generated by the stabilizer is improved, and the light emitting diode is favorably driven.

Description

LED power supply circuit

technical field

The invention relates to a power supply circuit of a light-emitting diode, which provides better power quality to the light-emitting diode through the connection of a ballast, a voltage doubler circuit and a constant current circuit.

Background technique

Light Emitting Diode (LED) is considered to be the best light source in the new era due to its characteristics and advantages of long life, small size, low heat generation, low power consumption, fast response and continuous improvement of luminous efficiency. The best choice, light-emitting diodes have become a new generation of lighting and display light sources. However, since the light-emitting principle of light-emitting diodes is different from that of traditional lighting sources, when light-emitting diodes are applied to power supply devices for traditional lighting sources, it is necessary to change the power supply circuit on the power supply device. The output power is suitable for driving the light-emitting diode, and is conducive to the improvement of the luminous efficiency and wattage of the light-emitting diode.

Traditional lighting sources, such as sight lamps or halogen lamps, are mostly driven by AC voltage. Therefore, the main purpose of the power supply circuit inside the power supply device for driving these traditional lighting sources is to generate a stable AC voltage. When these power supply devices are used to provide the power supply of light-emitting diodes, the power supply circuit inside the power supply device 101 is often further replaced. As shown in Figure 1, the power supply circuit inside the power supply device 101 of the halogen lamp (such as MR 16) can be replaced with a light The diode power supply circuit 11 , whereby the power supply device 101 can stably drive the light emitting device 20 composed of light emitting diodes 21 . Although the purpose of providing stable current to the lighting device 20 can be achieved by replacing the power supply circuit 11 inside the power supply device 101 , however, replacing the power supply circuit 11 inside the power supply device 101 will inevitably cause troubles for consumers in use.

Of course, some manufacturers also integrate part of the power supply circuit inside the light-emitting device composed of light-emitting diodes, and further convert the power supply voltage generated by the traditional power supply device 102 . As shown in Figure 2, the rectifier circuit 13 and the constant current circuit 15 are arranged inside the light emitting device 20, and the AC voltage generated by the power supply device 102 of the halogen lamp is rectified by the rectifier circuit 13 to output a DC voltage to a constant current. circuit 15 , and the constant current circuit 15 will output a corresponding current to the light emitting diode 21 , so as to achieve the purpose of driving the light emitting diode 21 .

The rectifier circuit 13 is mainly used to rectify the AC voltage output by the ballast 19 of the power supply device 102 and output a DC voltage. However, the ballast 19 is a high-frequency device and has a load effect, so the DC output of the rectifier circuit 13 If the voltage cannot stably provide sufficient voltage to the constant current circuit 15 , the LED 21 will not be able to obtain sufficient and stable current and/or voltage, thereby affecting the luminous performance of the LED 21 .

Contents of the invention

The technical problem solved by the present invention is to provide a power supply circuit for light-emitting diodes, in which the voltage doubler circuit is used to receive an AC voltage and output a DC voltage, and the DC voltage is greater than the peak voltage of the AC voltage, thereby providing sufficient DC voltage to the constant current circuit.

The secondary purpose of the present invention is to provide a power supply circuit for light emitting diodes, wherein the voltage doubler circuit is used to rectify and amplify the received AC voltage, so that the voltage doubler circuit can provide a DC voltage with better output quality to the Constant current circuit.

Another object of the present invention is to provide a power supply circuit for LEDs, wherein the voltage doubler circuit can provide sufficient DC voltage to the constant current circuit, whereby the LEDs can obtain sufficient current and/or voltage from the constant current circuit.

Another object of the present invention is to provide a power supply circuit for light-emitting diodes, in which the constant current circuit can output relatively large current and/or voltage, so that more light-emitting diodes can be connected in series at the output end of the constant current circuit , which is beneficial to improve the overall brightness of the light-emitting device.

Another object of the present invention is to provide a power supply circuit for light emitting diodes, wherein the constant current circuit and/or voltage doubler circuit can be integrated inside the light emitting device, so that the light emitting diodes can be powered by conventional power supply devices.

To achieve the above object, the present invention provides a power supply circuit for light emitting diodes, including: a ballast, used to generate an AC voltage; a voltage doubler circuit, used to receive the AC voltage generated by the ballast and output a DC voltage , and the DC voltage is greater than the peak voltage of the AC voltage; and a constant current circuit is used to receive the DC voltage generated by the voltage doubler circuit and output a current.

In order to further understand the features and technical contents of the present invention, please refer to the following detailed description and accompanying drawings of the present invention. However, the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present invention.

Description of drawings

Fig. 1 is a structural schematic diagram of a commonly used light emitting device and a power supply device;

Fig. 2 is a structural schematic diagram of a commonly used light emitting device and a power supply device;

Fig. 3 is a block connection diagram of a preferred embodiment of the power supply circuit of the light-emitting diode of the present invention;

Fig. 4 is the schematic circuit diagram of the ballast of the power supply circuit of the present invention;

Fig. 5 is the schematic circuit diagram of the voltage doubler circuit of the power supply circuit of the present invention;

Fig. 6 is the waveform diagram of the DC voltage output by the voltage doubler circuit of the present invention;

7 is a schematic diagram of the circuit connection of the constant current circuit of the power supply circuit of the present invention;

Fig. 8 is a schematic structural view of the light emitting device and the power supply device of the present invention.

Among them, reference signs:

101 Power supply device 102 Power supply device

11 Power supply circuit 13 Rectifier circuit

15 Constant current circuit 20 Lighting device

21 LEDs

30 Power supply circuit 31 Ballast

311 bridge rectifier circuit 313 start circuit

315 Inductor 33 Voltage doubler circuit

35 Constant current circuit 351 Constant current integrated circuit components

37 AC power supply

40 Light-emitting device 41 Light-emitting diode

50 power supply unit

Detailed ways

Please refer to FIG. 3 , which is a block connection schematic diagram of a preferred embodiment of a power supply circuit for light emitting diodes of the present invention. As shown in the figure, the power supply circuit 30 of the present invention includes a ballast 31, a voltage doubler circuit 33 and a constant current circuit 35, wherein the ballast 31 is used to generate an AC voltage V1, and the voltage doubler circuit 33 is used to The AC voltage V1 is received, and the AC voltage V1 is rectified and amplified to output a DC voltage V2 to the constant current circuit 35 .

In actual application, the ballast 31 may be a ballast used by a general traditional lighting source, for example, in an embodiment of the present invention, the ballast is a ballast used by a halogen lamp (MR 16). The ballast 31 is mainly used to receive the AC power 37 supplied by the power company, and convert the AC power 37 to output an AC voltage V1. Compared with the AC power supply 37, the output AC voltage V1 after conversion by the ballast 31 has a different frequency and a more stable output, and can be applied to general lighting sources, for example, the frequency of the AC voltage V1 is higher than that of the AC power supply. 37, and the AC voltage V1 can drive the halogen lamp MR 16.

The power supply circuit 30 of the present invention is mainly used to drive the light emitting diodes 41 , generally speaking, the light emitting diodes 41 are mostly driven by a DC current source. Therefore, other circuits must be added during application, and the AC voltage V1 is rectified and converted to drive the light emitting diode 41 .

In the present invention, the voltage doubler circuit 33 is mainly used to rectify the AC voltage V1 generated by the ballast 31 , and the voltage doubler circuit 33 will output a DC voltage V2 after the rectification is completed. The voltage doubler circuit 33 can not only rectify the AC voltage V1 to output a DC voltage V2, but also the DC voltage V2 output by the voltage doubler circuit 33 will be greater than the peak voltage of the AC voltage V1. The DC voltage V2 will be a multiple of the peak voltage of the AC voltage V1, such as 1 times, 2 times, etc.

After the voltage doubler circuit 33 converts the AC voltage V1 into a DC voltage V2, the DC voltage V2 can be further transmitted to the constant current circuit 35, and the constant current circuit 35 will output the corresponding DC voltage V3 and current according to the received DC voltage V2 I, and provide current I to the light emitting diode 41 connected with the constant current circuit 35, so as to achieve the purpose of driving the light emitting diode 41.

In application, if the constant current circuit 35 can provide a larger DC voltage V3, a larger number of LEDs 41 can be connected in series at the output end of the constant current circuit 35, and the overall luminance can be effectively improved. In the present invention, the voltage doubler circuit 33 is mainly used to rectify and amplify the AC voltage V1 provided by the ballast 31. Compared with the conventional structure, a higher DC voltage V2 can be provided to the constant current circuit 35, and This enables the constant current circuit 35 to generate a larger DC voltage V3 to output to the LED 41 .

For commonly used power supply circuits, the AC voltage V1 generated by the ballast 31 is mainly rectified by the rectifier circuit 13. If the power supply quality of the ballast 31 is unstable or cannot generate sufficient voltage, it will cause the LED 41 to fail. Produces the brightness it should have. For example, in practical applications, due to the uneven production quality of the ballasts 31, some ballasts 31 can only provide insufficient voltage, so that the constant current circuit 35 cannot obtain enough voltage to drive the series-connected light-emitting diodes 41. When the constant current circuit 35 cannot provide enough current I and/or voltage to the LED 41, the brightness of the LED 41 will be affected.

For the present invention, since the voltage doubler circuit 33 can be used to rectify and amplify the AC voltage V1 output by the ballast 31, there will be no problem that the LED 41 cannot obtain sufficient voltage during use. In other words, the connection of the ballast 31 and the voltage doubler circuit 33 can effectively increase the voltage that the ballast 33 can provide, provide enough voltage for the constant current circuit 35, and more light-emitting diodes 41 can be set at the load end, not only The number of light-emitting diodes 41 can be increased, and it is also conducive to the improvement of luminous brightness.

Please refer to FIG. 4 and FIG. 5 , which are schematic circuit diagrams of the ballast and the voltage doubler circuit of the power supply circuit of the present invention, respectively. As shown in the figure, the ballast 31 mainly includes a bridge rectifier circuit 311 and a start-up circuit 313, wherein the bridge rectifier circuit 311 is used to rectify the AC power 37, and the start-up circuit 313 is composed of transistors Q1/Q2, And an AC voltage V1 can be formed on the inductor 315 .

In this embodiment, the voltage doubler circuit 33 is a full-wave double voltage circuit. The inductor L1 can induce the AC voltage V1 output by the ballast 31 to generate an induced voltage Vs, and then rectify the induced voltage Vs to output A DC voltage V2, wherein the DC voltage V2 is twice the peak voltage of the AC voltage V1. As shown in Figure 6, when the induced voltage Vs is in the positive half cycle, the diode D1 will conduct and charge the capacitor C1 at the same time; and when the induced voltage Vs is in the negative half cycle, the diode D2 will conduct and charge the capacitor C2 at the same time . In other words, when the induced voltage Vs is in the positive half cycle, the capacitor C1 will be charged, and a voltage Vc1 will be formed on the capacitor C1, and the voltage Vc1=the peak voltage Vs1 of Vs; when the induced voltage Vs is in the negative half cycle, the capacitor C2 will be charged Charge, and form a voltage Vc2 on the capacitor C2, and the peak voltage Vs1 of the voltage Vc2=Vs will form a DC voltage V2 between the terminals a1 and b1 of the voltage doubler circuit 33, and the DC voltage V2 will be Twice the peak voltage Vs1 of the induced voltage Vs, or twice the peak voltage of the AC voltage V1. Of course, in actual application, the voltage doubler circuit 33 can be a double voltage circuit, a multiple voltage doubler circuit, a half-wave voltage doubler circuit or a full-wave voltage doubler circuit.

The voltage doubler circuit 33 can be connected with the constant current circuit 35, as shown in Figure 7, the terminal a1/b1 of the voltage doubler circuit 33 is connected with the terminal a2/b2 of the constant current circuit 35 respectively, and is received by the constant current circuit 35 The DC voltage V2 thereby outputs a DC voltage V3 and a current I, and the current I can be used to drive the LED 41 . For example, in this embodiment, the constant current circuit 35 includes a constant current integrated circuit element (constant current IC) 351 and external circuits such as capacitors, resistors, inductors and/or diodes. Of course, the circuit diagram of the ballast 31 described in Fig. 4 is only an embodiment of the present invention, and the voltage doubler circuit 33 can be connected with different types of ballasts in practical application, and the AC voltage produced by the ballast can be rectified and expand. In addition, the connection method between the voltage doubler circuit 33 and the constant current circuit 35 is not limited to the connection method shown in FIG. 7 .

Please refer to FIG. 8 , which is a structural diagram of the light emitting device and the power supply device of the present invention. As shown in the figure, the light emitting device 40 is mainly composed of a plurality of light emitting diodes 41. In one embodiment of the present invention, the voltage doubler circuit 33 and the constant current circuit 35 can be integrated inside the light emitting device 40, so that the light emitting device 40 includes The LED 41, the constant current circuit 35 and the voltage doubler circuit 33, and the ballast 31 are arranged in the power supply device 50, so that the voltage doubler circuit 33 can perform rectification, and the constant current circuit 35 can supply power to the LED 41. Of course, in different embodiments, the voltage doubler circuit 33 and/or the constant current circuit 35 can also be arranged inside the power supply device 50 , so that the voltage doubler circuit 33 is not provided inside the light emitting device 40 .

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention. All changes and deformations should belong to the protection scope of the appended claims of the present invention.

Claims (16)

1. the power supply circuits of a light-emitting diode is characterized in that, include:

One stabilizer is in order to produce an alternating voltage;

One voltage-multiplying circuit, in order to receiving the alternating voltage that this stabilizer produces and to export a direct current voltage, and this direct voltage is greater than the crest voltage of this alternating voltage; And

One constant-current circuit is in order to receive the direct voltage that this voltage-multiplying circuit produces and to export an electric current.

2. according to the power supply circuits shown in the claim 1, it is characterized in that, include at least one light-emitting diode and be connected with this constant-current circuit and receive this electric current.

3. according to the power supply circuits shown in the claim 1, it is characterized in that, include a light-emitting device, and this light-emitting device includes at least one light-emitting diode and this constant-current circuit.

4. according to the power supply circuits shown in the claim 3, it is characterized in that this light-emitting device includes this voltage-multiplying circuit.

5. according to the power supply circuits shown in the claim 2, it is characterized in that this voltage-multiplying circuit is arranged on this light-emitting device outside.

6. according to the power supply circuits shown in the claim 1, it is characterized in that this stabilizer includes a bridge rectifier.

7. according to the power supply circuits shown in the claim 1, it is characterized in that voltage-multiplying circuit is one or two voltage-multiplying circuit or many voltage-multiplying circuits.

8. according to the power supply circuits shown in the claim 1, it is characterized in that this voltage-multiplying circuit is half-wave voltage-multiplying circuit or full-wave voltage multiplier circuit.

9. according to the power supply circuits shown in the claim 1, it is characterized in that this voltage-multiplying circuit is in order to respond to this alternating voltage and to produce an induced voltage.

10. according to the power supply circuits shown in the claim 9, it is characterized in that voltage-multiplying circuit is in order to carry out rectification and to export this direct voltage to this induced voltage.

11. the power supply circuits according to shown in the claim 9 is characterized in that, this direct voltage is the multiple of the crest voltage of this induced voltage.

12. the power supply circuits according to shown in the claim 1 is characterized in that, this direct voltage is the multiple of the crest voltage of this alternating voltage.

13. the power supply circuits according to shown in the claim 1 is characterized in that, this stabilizer is in order to receiving an AC power, and this AC power is converted into this alternating voltage.

14. the power supply circuits according to shown in the claim 13 is characterized in that, this AC power and this alternating voltage have different frequencies.

15. the power supply circuits according to shown in the claim 1 is characterized in that, this constant-current circuit comprises a constant current integrated circuit component.

16. the power supply circuits according to shown in the claim 15 is characterized in that, this constant-current circuit comprises an external circuit.

Images