CN102098845A

CN102098845A - Method for driving array-type alternating current-light-emitting diode (AC-LED) chips

Info

Publication number: CN102098845A
Application number: CN2011100088199A
Authority: CN
Inventors: 张庆
Original assignee: DONGYING JIAWEN PHOTOELECTRIC Co Ltd
Current assignee: DONGYING JIAWEN PHOTOELECTRIC Co Ltd
Priority date: 2011-01-17
Filing date: 2011-01-17
Publication date: 2011-06-15

Abstract

The invention provides a method for driving array-type alternating current-light-emitting diode (AC-LED) chips. A driving voltage is provided; the driving voltage performs periodical pulsation change surrounding the corresponding average value within a certain range, and has a driving wave form; at any time, the driving voltage value is always not less than the voltage at an LED threshold opening terminal, and is not larger than the LED peak terminal voltage; and the driving voltage is utilized to drive an LED light-emitting unit to operate. The method provided by the invention has the beneficial effects of simple structure, less electronic components, small circuit volume and long service life; and the light source continuously emits light and the emitted light approaches to the natural light.

Description

A kind of driving method of array AC-LED chip

Technical field

The invention belongs to the AC-LED technical field, especially relate to a kind of driving method of array AC-LED chip.

Background technology

Up to the present, though the phase I of simple and easy constant current-non-isolation type and the second stage of constant current-isolated form have successively been experienced in the development of LED Constant Direct Current power supply, and entering phase III of PF correction-constant current constant voltage-isolated form, it is in the life-span, the power supply size, in price intrinsic shortcoming still can't be significantly improved.For this reason, a kind of technology of the novel array high voltage formula led chip (array AC-LED chip) that is named as AC driving is being suggested and is obtaining to develop rapidly over nearly 5 years.

The basic conception of array AC-LED is not use the AC-DC conversion and the rectification circuit of extra (beyond the chip), the mode that changes the collocation current-limiting resistance into is avoided loss in efficiency, large-size, labyrinth and the age limit of using the Constant Direct Current power supply to cause directly with the alternating current driving LED.The important breakthrough of AC-LED light source is that the LED device is as independent component or the integrated unit specific combination technology in encapsulation or chip array integrating process, utilize the diode characteristic double as rectification of LED PN junction or Schottky knot simultaneously, adopt staggered matrix form to arrange technology, and in chip design, add bridge circuit, two groups of reverse parallel connection LED devices or Schottky knot rearrange the structure of a similar rectifier bridge, the two ends of rectifier bridge directly connect AC power respectively, in addition two ends connect more can be shared the series LED device, and the positive half period of current-limiting resistance alternating current and two brachium pontis of negative half period and shared series LED device maintenance conducting, the last electric current of LED has unidirectional, the varied non-sinusoidal characteristic, 0 to cyclic variation between the peak current, its respective frequencies is 60 or 120Hz, because eyes have eye storage characteristic, the LED mode of operation that periodic intensity changes can be read as continuously luminous in human eye.

The LED number that series connection is used in AC-LED needs to determine according to concrete parameter, utility grid voltage (110V or 220V) and the required illuminance of light path, LED and Schottky knot, and carry out electric current by series resistance or electric capacity and limit, even as a key character of AC LED is that LED also is luminous continuously on the condition of forward bias voltage, this is because the LED terminal voltage always changes to peak period from 0 with sinusoidal form.When being lower than the cut-in voltage of LED, LED will keep off state, and no current passes through, also not luminous, only surpass after threshold value opens pressure the conducting of LED ability in the LED both end voltage, have light output, and optical output power will rise to peak value with the voltage increase always, as shown in Figure 1.

Therefore in AC-LED, the voltage at each LED device two ends is that sinusoidal period changes, the electric current of LED and optical output power then present the non-sine form from 0 to constantly changing between peak value, calculating shows that AC-LED is in one-period, there is time to be in off state near 40%, and in the time of conducting, the operating current of nearly 40% time LED surpasses the operating current of the constant current power supply LED with identical luminosity, and its peak current reaches more than four times of constant current LED.

Because constant voltage constant current power has traditionally been given up in the application of AC-LED, removed unnecessary electronic component, and reduced cost, the LED Design of Luminaires is oversimplified and volume can further reduce, and has avoided loss in efficiency and the age limit introduced in AC-to-DC conversion and the voltage stabilization and current stabilization circuit fully.Make the AC-LED technology in the miniaturization of LED light fixture, bigger success has been obtained in reliability and long service live field.At present, U.S. Link labs, III-N Technology, the Soul-semiconductors of Korea S, and the Industrial Technology Research Institute of Taiwan's electric light all applied for relevant patented technology, the application of AC-LED at lighting field also promoted in exploitation with all strength.

But AC-LED has a potential basic weakness: both since the operating current of AC-LED under the luminous state of device, most of times will be far above the DC-LED operating current of the same brightness of correspondence, reach four times of gaps at peak value, the internal quantum efficiency of AC-LED device itself is because the restriction of optical efficiency decline (droop effect) will be lower than the DC-LED with identical luminosity, the reason that Droop effect exists is comparatively complicated, depend on the polarity effect that comprises nitride material, auger recombination (Auger combination), the junction temperature of diode (junction temperature), the influence of the bunching effect of phosphide atom multiple materials such as (In-rich) and LED structure, the internal quantum efficiency of AC-LED is about the low 15-20% of Constant Direct Current LED with constant power output, and driving voltage is the cycle variation of trying to be the first in AC-LED, so drive current and light intensity present the pulse change feature, account for appearance and have only about 60% than (Duty cycle).

Summary of the invention

The driving method that the purpose of this invention is to provide a kind of AC-LED is simple, accounts for Rong Bigao, and its driving circuit structure is simple, number of electronic components is few, the circuit volume is little, the driving method of long array AC-LED of life-span chip.

Technical scheme of the present invention is:

A kind of driving method of array AC-LED chip, at least comprise: a driving voltage is provided, this driving voltage is done periodic pulsatile change within the specific limits round corresponding mean value, and this driving voltage has a drive waveforms, at any time, this driving voltage value is not less than LED threshold value opening end voltage all the time, is not more than LED peak value terminal voltage;

Use this driving voltage to come the driving LED luminescence unit to carry out work, make that the operating current and the Output optical power of each LED unit done periodic pulsatile change within the specific limits round corresponding mean value in the array, and be in channel status all the time.

Described drive waveforms presents approximate sawtooth waveforms, sine wave or triangular wave.

This driving method utilizes one drive circuit that this driving voltage is provided, and this drive circuit electrical connection one input power supply, and this input power supply is an AC power.

Advantage and good effect that the present invention has are:

1, changes the driving method of AC-LED, made the LED luminescence unit in whole periodic regime, keep continuing luminous.

2, LED luminescence unit of the present invention keeps non-zero status at input current and input light intensity in the whole cycle, and micropulsation changes near mean value, accounts for to hold than accounting for the appearance ratio far above 60% of existing AC-LED, equally with DC-LED has reached 100%.

3, because the change in voltage scope is little,, make LED intensity variations scope of the present invention, more approach continuous lighting technology much smaller than existing AC-LED so the electric current excursion is little.

4, obtained greatly in circuit design with on constituting and simplified, because accurately step-down and current stabilization, and reduced electronic component to the utmost, and reduced the circuit volume, reduced cost.

5, this circuit only need use the following solid ceramic condenser of 10UF; avoided the life problems (＜10000 hours) that the big capacity electrolyte electric capacity of use is brought in traditional Constant Direct Current power supply fully; the accelerated tests proof life-span of the present invention is at home (normal temperature; temperature) surpasses 50,000 hours under the condition, near the ultimate life of LED device.

Description of drawings

Fig. 1 is the schematic diagram of the drive waveforms of existing AC-LED;

Fig. 2 is the oscillogram of the operating current of each LED unit of the present invention;

Fig. 3 is first kind of drive circuit schematic diagram in the embodiments of the invention;

Fig. 4 is a drive circuit schematic diagram in another in the embodiments of the invention.

Embodiment

Propose a kind of mode of operation of array AC-LED chip: operating current of each LED unit (I) and Output optical power (P) are done periodic pulsatile change within the specific limits round corresponding mean value in the array chip, and be in channel status (I＞0 all the time, P＞0), as shown in Figure 2;

Propose the driving method of corresponding AC-LED, comprise at least:

One driving voltage is provided, this driving voltage is done periodic pulsatile change within the specific limits round corresponding mean value, and this driving voltage has a drive waveforms, at any time, this driving voltage value is not less than LED threshold value opening end voltage all the time, is not more than LED peak value terminal voltage;

Use this driving voltage to come the driving LED luminescence unit to carry out work.

Described drive waveforms presents near sinusoidal ripple, sawtooth waveforms or triangular wave.

As shown in Figure 3, be used to drive a kind of drive circuit of this chip, the drive circuit that has shown a kind of AC-LED can provide above-mentioned driving voltage, the LED luminescence unit 1 that driving is in series by one or more LED, described drive circuit comprises interchange input rectifying unit 2, protected location 3 and current stabilization unit 4, described interchange input rectifying unit 2 links to each other with described protected location 3, described LED luminescence unit 1 respectively, described protected location 3 links to each other with described current stabilization unit 4, and described LED luminescence unit 1 links to each other with described current stabilization unit 4; Q1 and Q2 are that two high voltage N PN triodes and amplification coefficient are about 100 in this circuit; C1/R1 and C2/R2 carry out current limliting and overvoltage protection as ceramic condenser to the LED electric current; make the work of LED not be subjected to surge high-pressure sharp pulse voltage sag; and the electric wire The noise, as the current stabilization unit LED Current Control is made pulsatile change by the mirror image power supply that triode and emitter resistance are formed near mean value at last.

Described interchange input rectifying unit 2 comprises the rectifier bridge that is made of the first diode D1, the second diode D2, the 3rd diode D3, the 4th diode D4; two inputs of described rectifier bridge connect the live wire and the zero line of power supply respectively; first output of described rectifier bridge connects the anode tap of described protected location and described LED luminescence unit respectively, second output head grounding of described rectifier bridge.

Described protected location 3 comprises first capacitor C 1, second capacitor C 2, first resistance R 1 and second resistance R 2; one end of described first resistance R 1 and first output of described rectifier bridge link to each other; its other end is by first capacitor C, 1 ground connection; one end of described second resistance R 2 and first output of described rectifier bridge link to each other, and its other end connects by second capacitor C, 2 ground connection.

Described current stabilization unit comprises the NPN type first triode Q1, NPN type second triode Q2 and the 3rd resistance R 3, the collector electrode of the base stage of the described first triode Q1 and the described second triode Q2 is connected in a common port, this common port and described second resistance R 2, common port between described second capacitor C 2 links to each other, the base stage of the emitter of the described first triode Q1 and the described second triode Q2 is connected in a common port, this common port is by the 3rd resistance R 3 ground connection, the grounded emitter of the described second triode Q2, the collector electrode of the described first triode Q1 connects the cathode terminal of described LED luminescence unit.

As shown in Figure 4; be used to drive the another kind of drive circuit of this chip; the drive circuit that has shown a kind of AC-LED can provide above-mentioned driving voltage; the LED luminescence unit 1 that driving is in series by one or more LED; described drive circuit comprises interchange input rectifying bridge circuit, current limliting (protection) resistance R and current stabilization capacitor C; described interchange input rectifying bridge circuit links to each other with current limliting (protection) resistance R, described LED luminescence unit 1 respectively; described current limliting (protection) resistance R links to each other with described current stabilization capacitor C, and described LED luminescence unit 1 links to each other with described current stabilization capacitor C.

More than two embodiment of the present invention are had been described in detail, but described content only is preferred embodiment of the present invention, can not be considered to be used to limit practical range of the present invention.All equalizations of doing according to the present patent application scope change and improve etc., all should still belong within the patent covering scope of the present invention.

Claims

1. the driving method of an array AC-LED chip, it is characterized in that, at least comprise: a driving voltage is provided, this driving voltage is done periodic pulsatile change within the specific limits round corresponding mean value, and this driving voltage has a drive waveforms, at any time, this driving voltage value is not less than LED threshold value opening end voltage all the time, is not more than LED peak value terminal voltage;

2. the driving method of a kind of array AC-LED chip according to claim 1 is characterized in that, described drive waveforms presents approximate sawtooth waveforms, sine wave or triangular wave.

3. the driving method of a kind of array AC-LED chip according to claim 1 is characterized in that, this driving method utilizes one drive circuit that this driving voltage is provided, and this drive circuit electrical connection one input power supply, and this input power supply is an AC power.