Background technology
LED is expected to become lighting source of new generation as a kind of novel solid state light emitter with advantages such as its energy-saving and environmental protection, life-span length.As everyone knows, existing LED uses dc powered, and our productive life electricity consumption is alternating current.Therefore, in the LED product that uses at present, need a power supply changeover device, alternating current is converted to direct current.The introducing of power supply changeover device brings a lot of negative effects.One, the life-span of power supply changeover device makes shorten the useful life of lighting device well below the life-span of LED self; Its two, power supply changeover device can reduce the efficient of light-emitting device; Its three, in low-power applications, power supply changeover device can cause the decline of power factor and the increase of electric current total harmonic distortion.In order to give full play to the advantage of semiconductor lighting, can become current research focus with the LED light-emitting device that alternating current directly drives.
In existing AC LED public technology, be to use the plurality of LEDs assembly to be formed by connecting according to the circuit topological structure of reverse parallel connection or bridge rectifier mostly, to satisfy the driving requirement of alternating electromotive force.But alternating current is according to certain frequency period fluctuation, because the existence of LED self cut-in voltage, when instantaneous voltage surpassed cut-in voltage, LED just understood conducting and luminous.Otherwise LED is by non-luminous.Sort circuit makes that the luminous efficiency of LED is very low, and along with the light-emitting flash phenomenon appears in the alternating voltage fluctuation.
Among the international monopoly WO 2004/023568A1 " LIGHT-EMITTING DEVICE HAVING LIGHT-EMITTINGELEMENTS ", integrated LED chip array on Sapphire Substrate has been proposed, thereby a kind of alternating electromotive force driven light emitting device is provided, but does not solve the light-emitting flash problem of LED.
US Patent No. 7,489,086 B2 " AC LIGHT EITTING DIODE AND AC LED DRIVE METHODS ANDAPPARATUS " provide a kind of AC LED device, this invention is a kind of with the integrated packaged device of a plurality of LED, utilizes the visual persistence effect of human eye to remedy the LED light-emitting flash phenomenon that alternating current causes.This patent does not fundamentally solve the light-emitting flash phenomenon that the alternating voltage cyclic fluctuation causes.
As seen, in disclosing LED interchange Driving technique, all exist the drive current of shortcoming a: LED to fluctuate along with the fluctuation of alternating voltage, occur brightness when causing LED luminous and change, produce the phenomenon of light-emitting flash.Simultaneously, the core of LED device is a PN junction diode, and its I-V characteristic is approximate exponential function, and after the voltage at LED two ends was greater than cut-in voltage, the electric current that flows through PN junction was exponential increase.The AC driving method of prior art, owing to do not use constant-current circuit, when the LED junction temperature raises, its cut-in voltage can descend, because input voltage is constant, makes the forward current of LED sharply increase, can make the PN junction of LED cause thermal breakdown, permanent damages when serious.
Summary of the invention
Technical problem to be solved by this invention is exactly the problem at the direct driving LED light-emitting device of prior art alternating current, and a kind of alternating current LED light-emitting device that direct constant current drives is provided.
The present invention solve the technical problem, the technical scheme that adopts is, the LED light-emitting device that the direct constant current of alternating current drives, comprise ac input end, protected location and rectification unit, it is characterized in that, be parallel with first branch road between first output of described rectification unit and second output, second branch road, the n branch road, described first route the one LED module and the first constant current units in series constitute, described second route the 2nd LED module and the second constant current units in series constitute, described n props up route n LED module and n constant current units in series constitutes, each constant current unit is connected with sampling unit, n 〉=1 wherein, and be integer;
Described ac input end is used for connecting alternating current, for device provides operating current;
Described protected location is connected with ac input end, for device provides defencive function;
Described rectification unit is connected with protected location, and the alternating current that protected location is exported carries out rectification;
Described sampling unit is used for the output voltage of rectification unit is sampled, and outputs a control signal to each constant current unit;
Each constant current unit is connected with sampling unit, and the electric current of constant respective branch and the control signal of exporting according to sampling unit turn on and off respective branch.
In the light-emitting device technical scheme of the present invention, the parallel branch that the constant current unit of n bar LED module and series connection thereof constitutes is connected rectification circuit output end, current value by setting a branch road constant current unit and shutoff thereof, connection voltage can avoid alternating voltage to change the periodicity scintillation that produces.Because the electric current of every branch road is constant, the LED in the LED module can not cause the variation of electric current because of the variation of junction temperature, has improved the reliability of LED.Can know that by theory analysis it is sinusoidal wave that the increase of branch road quantity can make drive current waveform approach, improve power factor and the efficient of light-emitting device.
Concrete, described LED module is made up of led array.
Adopt led array can form the high-power LED module.
Further, described led array is made of 1 LED that is arranged on the same printed circuit board at least, and perhaps integrated at least 1 LED that is encapsulated on the same substrate constitutes, and perhaps is integrated in at least 1 LED on the semi-conductive substrate to constitute.
LED all in the LED module is arranged on the same printed circuit board, is method for packing simple, the most economic under the state-of-the-art; Be encapsulated on the same substrate LED all in the LED module is integrated, refer to LED all in the LED module is carried out the secondary encapsulation, be integrated on the same heat-radiating substrate; LED all in the LED module is integrated in on the semi-conductive substrate, and this is to adopt semiconductor integrated circuit technique, realizes that at same semiconductor chip LED's is integrated.These technology all are the integrated encapsulation technologies of the LED of current comparative maturity.
Concrete, LED is in parallel and/or be connected in series in each LED module.
The suitable connection combination of LED as parallel connection, series connection or series-parallel connection etc., more can adapt to the environment for use that alternating current directly drives in the LED module, adjusts electric current, the voltage parameter of each LED module easily.
Further, a LED module, the 2nd LED module ... the LED quantity that comprises in the n LED module is respectively 1
2, 2
2... n
2, corresponding constant current cell current be respectively I, 2I ... nI; I is the first constant current cell current.
This regularity of distribution of LED quantity in the LED module can realize that the multiple of a branch current concerns, it is sinusoidal wave that total current waveform is approached, and is conducive to improve power factor and the efficient of light-emitting device.
Further, when n 〉=2, same LED belongs to different LED modules simultaneously.
This scheme can be with the LED interlaced arrangement in each LED module, make same or several LED belong to different LED modules simultaneously, realize the multiplexing of LED, can reduce the LED quantity of light-emitting device, improve the uniformity of light-emitting device luminosity, be conducive to overcome scintillation.
Concrete, described protected location comprises fuse and/or piezo-resistance, and described fuse is connected on ac input end, and described piezo-resistance is connected in parallel on ac input end.
Fuse is the current-limiting protection element of using always, and piezo-resistance then is the voltage-limiting protection element of using always, and their combination can be finished the most basic current limliting and voltage-limiting protection, and cost is low, and is easy for installation, and it is integrated to be convenient to carry out secondary.
Further, described protected location also comprises common mode choke and/or gas discharge tube, and described common mode choke is connected on ac input end, and described gas discharge tube is connected in parallel on ac input end.
Increase common mode choke and gas discharge tube, common mode choke can suppress common mode disturbances, and gas discharge tube can protect lighting device not by injuries such as thunders and lightnings.
Concrete, full-wave rectifying circuit or half-wave rectifying circuit that described rectification unit is made up of rectifier diode constitute.
Adopt rectifier diode as rectifier cell, volume is little in light weight, is convenient to carry out the integrated encapsulation of secondary.
Concrete, described sampling unit is made of resistor network.
Resistor network is fit to gather dc parameter very much, is convenient to set the operating point that the constant current unit disconnects and connects.
The invention has the beneficial effects as follows that use the direct constant-current driving LED module of alternating electromotive force, circuit is simple, volume is little, in light weight, and cost is low.By suitably presetting each branch current and switching voltage, the LED light-emitting device periodically glimmers in the time of can alleviating the alternating current fluctuation, and when the alternating current instantaneous voltage is too high, the constant current unit turn-offs, the LED module is not luminous, has improved the utilization ratio of power supply, has reduced power consumption.Simultaneously, owing to adopt constant current control, avoided the LED module because of variations injunction temperature, the excessive and situation of burning of electric current has prolonged useful life of device.
Embodiment
Below in conjunction with drawings and Examples, describe technical scheme of the present invention in detail.
The LED light-emitting device that the direct constant current of alternating current of the present invention drives; structured flowchart as shown in Figure 1; comprise ac input end 1, protected location 2, rectification unit 3, and first branch road of parallel connection between first output 31 of rectification unit 3 (be generally anodal) and second output 32 (being generally negative pole), second branch road ... the n branch road.First route the one LED module 51 and 61 series connection of the first constant current unit constitute, described second route the 2nd LED module 52 and 62 series connection of the second constant current unit constitute, described n props up route n LED module 5n and n constant current unit 6n series connection constitutes, each constant current unit is connected with sampling unit, n 〉=1 wherein, and be integer.Ac input end 1 is used for connecting interchange, for device provides operating current; Protected location 2 is connected with ac input end, for device provides defencive function; Rectification unit 3 is connected with protected location 2, and the alternating current that protected location 2 is exported carries out rectification, sine wave output pulse current (shown in Fig. 5 a); Sampling unit 4 is used for the output voltage of rectification unit is sampled, and outputs a control signal to each constant current unit; Each constant current unit is connected with sampling unit 4, and the electric current of constant respective branch and the control signal of exporting according to sampling unit 4 turn on and off respective branch.
Below simple operation principle of the present invention described:
Electric main (being generally sine wave alternating current) enters protected location 2 by exchanging input interface 1, carries out rectification through rectification unit 3, becomes sinusoidal wave pulse voltage, and its voltage waveform is shown in Fig. 5 a.In an ac period T, raise with input voltage, reach a LED module 51 cut-in voltages, a LED module 51 enters operating state, and electric current increases gradually, reaches the first constant current unit, 61 predetermined current and is operated in constant current state with this predetermined current afterwards.Continue to raise with voltage, voltage reaches the first constant current unit, 61 default shutoff voltages, and the first constant current unit 61 turn-offs, and a LED module 51 is not luminous.This moment second, constant current unit 62 was connected, the 2nd LED module 52 is started working, the 2nd LED module 52 is kept the constant current operating state with the electric current of the second constant current unit, 62 settings after entering constant current state, along with voltage continues to rise, the second constant current unit 62 turn-offs, by that analogy, 5n starts working up to the nLED module, and the constant current unit of front all turn-offs.If setting the first constant current unit, 61 continuous currents is I, the second constant current unit, 62 continuous currents are 2I, n constant current unit continuous current is nI, and in theory, it is more many to divide into groups, current waveform is more near sine wave, shown in Fig. 5 b, power factor is also more high, and efficient is also more high, but circuit is also more complicated, and placement-and-routing is also more difficult.Therefore, in actual applications, the LED module of choosing limited constant current unit and respective amount constitutes limited branch road.
Embodiment 1
As shown in Figure 2, this routine protected location 2 is made of fuse F and piezo-resistance VR, and fuse F is connected on the phase line L of ac input end 1, and piezo-resistance VR is connected in parallel between the phase line L and zero line N of ac input end 1.Protected location 2 is connected with the rectification unit 3 that full-wave rectifying circuit D1 constitutes, rectification unit 3 outputs 4 branch roads in parallel.
First route the one LED module and the first constant current units in series constitute, and a LED module is made of a LED11, and its anode connects rectification circuit D1 positive pole, and negative terminal is connected to rectification circuit D1 negative pole by the first constant current unit.The sampling of this example is made of resistor network, comprises resistance R 1~R8.Resistance R 1 be connected in parallel between rectification circuit D1 positive pole and the negative pole after resistance R 2 is connected, the tie point of resistance R 1 and resistance R 2 is the sampled point of the first constant current unit, and is connected with the first constant current unit controls end.In this example second branch road, the 2nd LED module is made up of 2 * 2 the array that 4 LED constitute, and comprises LED21, LED22, LED31 and LED32, they with two LED series aiding connections after the mode of two groups of homopolarity parallel connections connect, as shown in Figure 2.The 2nd LED module anode connects rectification circuit D1 positive pole, and negative terminal is connected to rectification circuit D1 negative pole by the second constant current unit.Resistance R 3 be connected in parallel between rectification circuit D1 positive pole and the negative pole after resistance R 4 is connected, the tie point of resistance R 3 and resistance R 4 is the sampled point of the second constant current unit, and is connected with the second constant current unit controls end.The 3rd LED module in this example the 3rd branch road is made up of 3 * 3 the array that 9 LED constitute, and comprises LED41, LED42, LED43; LED51, LED52, LED53; LED61, LED62, LED63.These LED with three series aiding connections after the mode of three groups of homopolarity parallel connections connect, referring to Fig. 2.The 3rd LED module anode connects rectification circuit D1 positive pole, and negative terminal is connected to rectification circuit D1 negative pole by the 3rd constant current unit.Resistance R 5 be connected in parallel between rectification circuit D1 positive pole and the negative pole after resistance R 6 is connected, the tie point of resistance R 5 and resistance R 6 is the sampled point of the 3rd constant current unit, and is connected with the 3rd constant current unit controls end.In this example the 4th branch road, the 4th LED module is made up of 4 * 4 the array that 16 LED constitute, and comprises LED71, LED72, LED73, LED74; LED81, LED82, LED83, LED84; Rectification circuit D1 negative pole LED91, LED92, LED93, LED94; LED01, LED02, LED03, LED04.These LED with four series aiding connections after the mode of four groups of homopolarity parallel connections connect, referring to Fig. 2.The 4th LED module anode connects rectification circuit D1 positive pole, and negative terminal is connected to by the 4th constant current unit.Resistance R 7 be connected in parallel between rectification circuit D1 positive pole and the negative pole after resistance R 8 is connected, the tie point of resistance R 7 and resistance R 8 is the sampled point of the 4th constant current unit, and is connected with the 4th constant current unit controls end.This routine rectification circuit D1 negative pole is common.
Be connected with electrical network by plug; this routine light-emitting device obtains alternating electromotive force, alternating current process protected location, and by rectification unit; be rectified into direct current (be the sinusoidal wave pulse direct current strictly speaking, waveform is shown in Fig. 5 a) and offer voltage sample unit, constant current unit and LED module.In each ac cycle T, the rising of starting from scratch of rectification circuit D1 output voltage, when voltage raises when reaching the cut-in voltage of a LED module, the first constant current unit is connected, and a LED module begins luminous, enters operating state.Voltage continues to raise, and the constant current 20mA work of constant current unit 1 to set makes a LED module electric current reach the 20mA rated current.When voltage raises when reaching default shutoff voltage, the first constant current unit turn-offs, and a LED module quits work, and a LED module extinguishes, and the 2nd LED module begins luminous, enters operating state.Voltage raises, and the constant current 40mA work of the second constant current unit to set makes the 2nd LED module electric current reach the 40mA rated current.When voltage is elevated to the second constant current unit and reaches default shutoff voltage, the second constant current unit turn-offs, the 2nd LED module quits work, the 3rd LED module is started working, along with voltage raises, the constant current 60mA work of the 3rd constant current unit to set makes the 3rd LED module electric current reach the 60mA rated current.When voltage raises when reaching default shutoff voltage, the 3rd constant current unit turn-offs, and the 4th constant current unit is connected, the 4th LED module is started working, when voltage continuation rising, the 4th constant current unit makes the 4th LED module electric current reach the 80mA rated current with constant current 80mA work.Be depicted as this routine current waveform schematic diagram as Fig. 5 b, electric current was multiplied in the different stages as seen from the figure, its waveform convergence sine.Make this routine light-emitting device have very high efficient and power factor.Also there is defencive function the 4th constant current unit, and when voltage surpassed default shutoff voltage, the 4th constant current unit turn-offed.LED module in the whole light-emitting device all turn-offs, and the protection light-emitting device is unlikely to damage.
Led array in this example in each LED module (the LED module of this example first branch road also can be regarded 1 * 1 led array as), can be that the LED that is arranged on the same printed circuit board constitutes, perhaps adopt integrated encapsulation technology, their integrated being encapsulated on the same heat-radiating substrate constituted, also can utilize integrated circuit technology, they are integrated in constituting on the semi-conductive substrate.
Embodiment 2
Figure 3 shows that this routine circuit diagram, as can be seen, this example is except LED modular structure and connected mode thereof and embodiment 1 are different, and other structures are identical with embodiment 1.Only be described with regard to the LED modular structure of four branch roads below, other structures and the course of work thereof see also the description of embodiment 1, do not give unnecessary details for this reason herein.LED module in this example first branch road is made up of a LED31, and a LED module anode is connected with rectification circuit D1 is anodal, and a LED module negative terminal is connected to rectification circuit D1 negative pole by the first constant current unit.The 2nd LED module in this example second branch road comprises LED31, LED32, and LED21, LED22 be totally 4 LED.When the first constant current unit turn-offs, these 4 LED constitute 2 * 2 array, wherein LED31 and LED32 series aiding connection are one group, LED21 and LED22 series aiding connection are one group, these two groups of homopolarities formation in parallel the 2nd LED module, the 2nd LED module anode is connected with rectification circuit D1 is anodal, and negative terminal is connected to rectification circuit D1 negative pole by the second constant current unit.This example the 3rd LED module comprises LED31, LED32, LED33, and LED21, LED22, LED23, LED11, LED12, LED13 be totally 9 LED.When the first constant current unit and the second constant current unit all turn-off, these 9 LED constitute 3 * 3 array, wherein LED31, LED32, LED33 series aiding connection are one group, one group of LED21, LED22, LED23 series aiding connection, LED11, LED12, LED13 series aiding connection are one group, and these three groups of these examples of homopolarity constitute the 3rd LED module.The 3rd LED module anode is connected with rectification circuit D1 is anodal, and negative terminal is connected to rectification circuit D1 negative pole by the 3rd constant current unit.Same, when the first constant current unit, the second constant current unit and the 3rd constant current unit all turn-off among Fig. 3, the LED31 of four groups of series aiding connections, LED32, LED33, LED34, LED21, LED22, LED23, LED24, LED11, LED12, LED13, LED14,4 * 4 the led array that LED01, LED02, LED03, LED04 constitute is formed the 4th LED module of this example, the 4th LED module anode is connected with rectification circuit D1 is anodal, and negative terminal is connected to rectification circuit D1 negative pole by the 4th constant current unit.In this example, each subcircuits is the same with embodiment 1, also is into the multiple relation, if first branch current is I, other branch roads are followed successively by 2I, 3I and 4I.
LED in each LED module of this example has adopted the mode of series connection and combination in parallel, and partial L ED belongs to a plurality of LED modules simultaneously.In Fig. 3, LED31 belongs to all LED modules simultaneously, and LED22 and LED32 belong to second, third and the 4th LED module simultaneously, and LED33, LED23 and LED13 be the third and fourth LED module simultaneously.Adopt this multiplexing structure, reduced the quantity of luminescence unit greatly, reduced the light-emitting device cost, and be conducive to overcome scintillation.
Embodiment 3
As shown in Figure 4, this routine circuit diagram is compared with embodiment 2, and each LED module connected mode has been done further optimization, and four LED modules in four branch roads are made up of 16 LED, adopts 4 * 4 matrix topology structure.This example the one LED module by LED01, LED11, LED21 and LED31 1 * 4 array that constitutes of the LED of totally 4 parallel connections form.This example the 2nd LED module is by LED01, LED11, LED21, LED31, and LED02, LED12, LED22, LED32 2 * 4 arrays of the LED formation of totally 8 series and parallel combinations form.This example the 3rd LED module is by LED01, LED11, LED21, LED31, LED02, LED12, LED22, LED32, LED03, LED13, LED23, totally 12 LED series and parallels of LED33 forms in conjunction with 3 * 4 arrays that constitute, this example the 4th LED module is by LED01, LED11, LED21, LED31, LED02, LED12, LED22, LED32, LED03, LED13, LED23, LED33, LED04, LED14, LED24, totally 16 LED series and parallels of LED34 forms in conjunction with 4 * 4 arrays that constitute, and the annexation of other parts and operation principle see also the description of above-described embodiment.The maximum characteristics of this routine circuit are that each branch current is identical, and namely the electric current of all constant current unit settings is identical, are 4 times of a LED constant current drive current.
Through above-mentioned detailed explaination, as can be seen, voltage sample of the present invention unit monitoring input voltage also has the defencive function to the LED module simultaneously.When big fluctuation appearred in alternating voltage, the constant current unit also can in time disconnect, and protection LED module does not damage because electric current is excessive.Constant current of the present invention unit can adopt resolution element and/or integrated circuit to constitute, and requires to have switch control functions (can turn-off and connect control), because physical circuit belongs to this area mature technology, the present invention is not described in detail.
Need to prove; though above-described embodiment has been described structure of the present invention in detail; but the present invention is not limited to above-described embodiment, and the replacement structure that every those skilled in the art just can expect without creative work from above-described embodiment all belongs to protection scope of the present invention.