CN201114905Y

CN201114905Y - LED driving circuit

Info

Publication number: CN201114905Y
Application number: CNU2007201286514U
Authority: CN
Inventors: 郑英彰; 刘士弘
Original assignee: Xinju Enterprise Co Ltd
Current assignee: Zippy Technology Corp
Priority date: 2007-09-07
Filing date: 2007-09-07
Publication date: 2008-09-10
Anticipated expiration: 2017-09-07

Abstract

The utility model relates to a drive circuit of a light-emitting diode, which essentially comprises a rectification unit that transfers AC input periodic signal into DC input periodic signal, a switchover unit that cuts drive power signal output to the light-emitting diode and has working voltage value, a valley-filling type power factor correction circuit that obtains the AC input periodic signal, cuts off and breaks over the rectification unit when the voltage value of the AC input periodic signal is lower than a stopping voltage value which is higher than the working voltage value of the switchover unit, and a piezoelectricity inverter that obtains drive power signal of the switchover unit and then is modulated to AC modulation power signal within the working range of the light-emitting diode to drive the light-emitting diode to give out light.

Description

LED driving circuit

Technical field

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

Background technology

Because the appearance of ultra-high brightness LED, and the reaching its maturity of white light LEDs technology, be applied to products such as desk lamp, projecting lamp and develop out gradually, the LED illumination epoch have arrived, and are following even can replace present incandescent osram lamp, become the main light source of room lighting.And in the drive circuit of LED, most circuit-mode that adopts charge pump (Charge-Pump) or liter-step-down (Boost-Buck), but the efficient of these two kinds of drive circuits is not good.

Circuit-mode with charge pump is an example, its efficiency curve on average is about 60～70%, minimum even reach 50%, and limited output voltage range (output voltage is limited in the twice of input voltage) only can be provided, if need to drive plurality of LEDs, then only can be with parallel form winding LED, and need to increase current-limiting resistance and cause uneven bright situation to produce to prevent current unevenness, thus, not only need raise the cost, also waste energy in setting up on the element, cause inefficiency.And rise-circuit-mode of step-down makes circuit design comparatively complicated because of adopting inductance, and under the situation that drives plurality of LEDs, big electric current when needing to use expensive inductance to bear energy conversion, to those skilled in the art, also not preferred led drive circuit, therefore, how to provide more efficient drive circuit to become the general objective that LED those skilled in the art do one's utmost to reach.

The utility model content

Main purpose of the present utility model is that the mode of the direct driven for emitting lights diode of utilization AC signal is to improve electricity usage efficient.

Of the present utility model time a purpose is, with drives light-emitting diode low-cost and Simple Design.

Another purpose of the present utility model is, avoids switch unit input cumulative power and punctures or damage switch unit.

A purpose more of the present utility model is, overcomes the electromagnetic interference (EMI) problem.

For achieving the above object, the utility model provides a kind of LED driving circuit, mainly comprises: one imports the rectification unit that periodic signal is converted to the direct current periodic signal with alternating current; The switch unit that one cutting exports this light-emitting diode driving electric signal to and has operational voltage value; Reach one and obtain alternating current input periodic signal and the valley fill type circuit of power factor correction of this rectification unit of conducting of when the magnitude of voltage of this alternating current input periodic signal is lower than a cut-ff voltage value, stopping, wherein, this cut-ff voltage value is higher than this switch unit operational voltage value; Reaching one obtains the driving electric signal of this switch unit and is tuned as the interior modulation electric power signal that exchanges of this light-emitting diode working range to drive the piezoelectricity inverter of this lumination of light emitting diode.

Another purpose of the present utility model is, suppresses the infringement that the arc discharge effect is caused.

For reaching above-mentioned purpose, the utility model in rectification unit to the formed reaction under high pressure of piezoelectricity inverter interval in configuration one detect the arc discharge protected location of arc discharge effect with this light-emitting diode driving electric signal of stopping.

By technique scheme, the utility model LED driving circuit has following advantage at least:

1. the cost in the reduction LED driving circuit

2. simplify the LED driving circuit design

3. avoid switch unit input cumulative power and puncture or damage switch unit

4. overcome the electromagnetic interference (EMI) problem

Description of drawings

Fig. 1 is the block schematic diagram of preferred embodiment of the present utility model,

Fig. 2 is the circuit diagram of preferred embodiment rectification unit of the present utility model and valley fill type circuit of power factor correction,

Fig. 3-1 is the mode of operation I schematic equivalent circuit of preferred embodiment rectification unit of the present utility model and valley fill type circuit of power factor correction,

Fig. 3-2 is the mode of operation II schematic equivalent circuit of preferred embodiment rectification unit of the present utility model and valley fill type circuit of power factor correction,

Fig. 3-3 is the mode of operation III schematic equivalent circuit of preferred embodiment rectification unit of the present utility model and valley fill type circuit of power factor correction,

Fig. 4 is the mode of operation oscillogram of preferred embodiment rectification unit of the present utility model and valley fill type circuit of power factor correction,

Fig. 5 is the interchange input periodic signal filter state oscillogram of preferred embodiment of the present utility model,

Fig. 6 is the drive signal waveform figure of preferred embodiment of the present utility model,

Fig. 7 is the interchange string ripple signal waveforms of preferred embodiment of the present utility model,

Fig. 8 is that the light-emitting diode series connection of another preferred embodiment of the present utility model drives schematic diagram,

Fig. 9 is the light-emitting diode of the another preferred embodiment of the present utility model schematic diagram that drives in parallel,

Figure 10,11,12 is the rectification unit of multiple preferred embodiment of the present utility model and the circuit diagram of valley fill type circuit of power factor correction.

Embodiment

Relevant detailed description of the present utility model and technology contents, as follows referring now to description of drawings:

Please refer to Figure 1 and Figure 2, be the block schematic diagram of the utility model one preferred embodiment and the circuit diagram of rectification unit and valley fill type circuit of power factor correction, as shown in the figure:

The utility model provides a kind of LED driving circuit, mainly comprises:

One rectification unit 1, its interchange input periodic signal Vin with AC power is converted to the direct current periodic signal, and in present embodiment, rectification unit 1 is that a full-bridge rectifier D1～D4 and rectification unit 1 have one first output B1 and one second output B2;

Please refer to shown in the table 1, be the circuit state signal table of filling out paddy filter mode of operation of preferred embodiment of the present utility model:

Table 1

The utility model comprises a valley fill type circuit of power factor correction 2, it obtains the direct current periodic signal of rectification unit 1, and has a cut-ff voltage value V1, cut-ff voltage value V1 makes rectification unit 1 in the magnitude of voltage that the exchanges input periodic signal Vin conducting of stopping during less than cut-ff voltage value V1, and in the magnitude of voltage that exchanges input periodic signal Vin conducting during more than or equal to cut-ff voltage value V1, and then formation filter state, in present embodiment, valley fill type circuit of power factor correction 2 is a passive type circuit of power factor correction, comprise the first loop (not shown) that constitutes by capacitor C 1 and diode D5, the second loop (not shown) that capacitor C 2 and diode D6 constitute, an and diode D7 who is located between first loop and second loop, wherein first loop and second loop are located between the first output B1 and the second output B2, valley fill type circuit of power factor correction 2 has three mode of operation I, II, III (please refer to Fig. 3-1～3-3, shown in Fig. 4 and the above-mentioned table 1), its principle is because of capacitor C 1, the C2 charge path is different with discharge path, and the ON time that prolongs rectification unit 1, and thus more than the bring to power factor to 0.95, in addition, cut-ff voltage value V1 is the half-wave peak magnitude of voltage of rectification unit 1 obtained interchange input periodic signal Vin, so that make waveform be adjusted into filter state S2 (please refer to shown in Figure 5);

One switches unit 3, having operational voltage value and cutting exports the driving electric of light-emitting diode 4 to and exports a drive signal S3 (please refer to shown in Figure 6), and light-emitting diode 4 is obtained exchange the electric power of string ripple signal S4 (please refer to shown in Figure 7) and luminous, wherein, operational voltage value is the minimum voltage value of switch unit 3 required electric power when work, and the half-peak threshold voltage is higher than operational voltage value, so utilization valley fill type circuit of power factor correction 2 can will be lower than alternating current input periodic signal filtering before rectification unit 1 of cut-ff voltage value V1, therefore switch unit 3 obtained voltage of signals values in rear end all are enough to make switch unit 3 to enter operating state, puncture switch unit 3 so that avoid switch unit 3 input cumulative powers, in the present embodiment, switch unit 3 is two transistors; And

One piezoelectricity inverter 5, this piezoelectricity inverter 5 is obtained the driving electric signal of this switch unit 3 and is tuned as interchange modulation electric power signal in these light-emitting diode 4 working ranges to drive the luminous piezoelectricity inverter 5 of this light-emitting diode 4, wherein, this piezoelectricity inverter 5 can be the piezoelectric ceramics inverter; Because the resistance value of this light-emitting diode 4 is lower, so this piezoelectricity inverter 5 needs the driving electric of this switch unit 3 is downgraded to meet the power for operation scope of this light-emitting diode 4, excessive and the influence of the electric power of avoiding this piezoelectricity inverter 5 even damage this light-emitting diode 4, wherein, for reaching preferable electricity usage efficient, this light-emitting diode 4 comprises the identical light-emitting diode of a plurality of conducting directions 4, Fig. 8 represents that this light-emitting diode 4 connects mutually, Fig. 9 represents that this light-emitting diode 4 is parallel with one another, in the practical operation, it is also passable to merge above-mentioned connection in series-parallel form.

In addition; form a reaction under high pressure interval 6 in this rectification unit 1 to this piezoelectricity inverter 5; and in the arc discharge protected location (not shown) of interval 6 configurations of this reaction under high pressure one detection arc discharge effect with these light-emitting diode 4 driving electric signals of stopping; by the variation that detects arc discharge temperature that effect produces, electric current, voltage or its resistance value this light-emitting diode 4 driving electric signals of stopping; and then prevent that electronic component is impaired, more can further avoid producing the incident that endangers safety that high temperature caused by the arc discharge effect.

It is noted that rectification unit 1 of the present utility model and valley fill type circuit of power factor correction 2 except circuit design as shown in Figure 2, also can carry out elasticity and change that as Figure 10, the circuit design shown in 11,12 also can according to different electricity characteristic demands.

In sum, because the utility model utilization valley fill type circuit of power factor correction 2 forms LED driving circuit with piezoelectricity inverter 5, so can not only reduce the cost that needs to set up element in the known drive circuit, and simplify circuit design simultaneously, more energy more effectively can be utilized; In addition, the part that is lower than operational voltage value by rectification unit 1 and valley fill type circuit of power factor correction 2 and then filtering magnitude of voltage exchanges input periodic signal Vin, be lower than the operating voltage of switch unit 3 so that prevent the magnitude of voltage of switch unit 3 input signals, puncture so can avoid switch unit 3 input cumulative powers or damage switch unit 3; In addition, more can overcome the electromagnetic interference (EMI) problem by the piezoelectricity inverter.

The above is a preferred embodiment of the present utility model only, is not limited to the utility model.In the above-described embodiments, the utility model can have various changes and variation.All within spirit of the present utility model and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within the protection range of the present utility model.

Claims

1. a LED driving circuit is characterized in that, described LED driving circuit mainly comprises:

Alternating current is imported the rectification unit (1) that periodic signal is converted to the direct current periodic signal;

The switch unit (3) that cutting exports described light-emitting diode (4) driving electric signal to and has operational voltage value; And

Obtain alternating current input periodic signal and the valley fill type circuit of power factor correction (2) of the described rectification unit of conducting (1) of when the magnitude of voltage of described alternating current input periodic signal is lower than the cut-ff voltage value, stopping, wherein, described cut-ff voltage value is higher than described switch unit (3) operational voltage value; And

Obtain the driving electric signal of described switch unit (3) and be tuned as the interior interchange modulation electric power signal of described light-emitting diode (4) working range to drive the luminous piezoelectricity inverter (5) of described light-emitting diode (4).

2. LED driving circuit according to claim 1 is characterized in that, described light-emitting diode (4) comprises a plurality of mutual series connection and the identical light-emitting diode of conducting direction.

3. LED driving circuit according to claim 1 is characterized in that, described light-emitting diode (4) comprises a plurality of parallel with one another and light-emitting diodes that conducting direction is identical.

4. LED driving circuit according to claim 1 is characterized in that, the half-wave peak magnitude of voltage that described cut-ff voltage value is described AC driving signal.

5. LED driving circuit according to claim 1, it is characterized in that, described rectification unit (1) has first output (B1) and second output (B2), described valley fill type circuit of power factor correction (2) comprises to be located at described first output (B1) and described second output (B2) and to have electric capacity (C1, C2) and first loop and second loop of diode (D5, D6), and is located at the diode (D7) between described first loop and described second loop.

6. LED driving circuit according to claim 1; it is characterized in that; described rectification unit (1) to described piezoelectricity inverter (5) forms reaction under high pressure interval (6), and in the arc discharge protected location of configuration detection arc discharge effect in described reaction under high pressure interval (6) with described light-emitting diode (4) the driving electric signal of stopping.