AC direct drive LED filament lamp

LED lamp must be driven by a constant DC light, so the LED lamps are inseparable from the AC/DC constant current power supply, most of the current use of switching power supply or constant current constant voltage linear current. Generally speaking, a LED lamp, LED lamp bead about the total cost accounted for LED of the lamp 60%, and the driving power of about 15-25%. In order to reduce the cost of LED lights, reduce the use of power parts, reduce the whole lamp accessories, and reduce labor has become the main work of designers and entrepreneurs.

LED lights can be omitted AC/DC driver power supply? Direct use of AC to drive it? LED lighting is also a beautiful dream of development!

LED lamp is a PN junction diode, which can emit light, but also have the function of rectification. The reason is because of the technology, after years of development and promote the function of lighting LED lamp while neglecting the function of rectification.

AC LED applications without power supply have produced at the beginning of 2008, limited to LED lamp VF discrete flow is too big, did not find the active electronic devices, low power consumption and practical solutions on LED. So shelve.

The feasibility of AC LED light source

The feasibility study of the AC LED light source has been initiated in 2008. LED is a typical PN diode, so it is not only able to power the light, of course, can also be rectified AC.

The working principle of the AC LED light source is shown in Figure 1, the VF value is basically the same as the LED tiny grains bound on sapphire, ceramic or metal substrate, and the LED grain is connected in series with gold wire. The same five series of LED grains are composed of a rectifier bridge (Fig. 1), and the two ends of the rectifier bridge are respectively connected with an AC power supply, and the other ends are connected with a series of LED grains. The four LED series of the bridge arm are connected to alternating current, which can not only rectify alternating current, but also emit light.

Communication is half blue along the pathway flow, 3 series of LED grain light; the negative half cycle along the green channel flow, and 3 on the LED grain light; four bridge arm LED on grain turns light, relative to the LED grain bridge arm, on a string of LED light, middle grain by sharing a string straight in the light. In 50Hz or 60Hz alternating current to frequency rotation light 50 or 60 times per second. The DC of the rectifier bridge is pulsating DC (Fig. 1), and the LED light is flashing.

The long afterglow LED power has the characteristics of light afterglow afterglow continued, can maintain several tens of microseconds. The human eye is inert to the flow of light memory, interpretation of the results of working mode of the human eye light afterglow + LED light source is in continuous light. LED is half the time at work, half of the time in the rest, thus reducing the fever 40% ~ ~ 20%. Therefore, the service life of AC LED longer than DC LED. But the whole bridge AC LED light source luminous efficiency will be reduced by about 30%.

Figure 1 AC LED light source principle

Constant current IC filament

LED filament lamp after several years of development, today has been the birth of a technological innovation "IC filament"! It might be the LED constant current filament lamp changes IC filament revolutionary can simple and effective current of each filament in the bulb, solve a few LED filament by VF slightly difference caused by the current filament ranging.

In a light bulb, the application of parallel N LED filament, VF small filament will bear larger current day long long filament, large working current will decay! IC filament is a low cost effective solution! IC filament due to the need for heat dissipation of various metal substrate filament.

The IC filament is shown in figure 2. IC filament is directly two port linear constant current IC bare chip in substrate binding filament, constant current IC bare chip in the filament substrate with N LED chip chip direct series as a whole, become the new electronic control LED filament filament current. IC filament self constant current, self rectification.

Fig. 2 Schematic diagram of the internal structure of the metal IC filament

The LED lamp grain mass production of its parameters have great dispersion, even if we use the original LED grain after screening tablets in LED filament production, followed by hard pairing, still can not guarantee LED filament production, each of the same VF.

The root LED filament VF some differences in a light bulb, by a constant current power supply, current VF small filament will get more, for a long time, the root VF small LED filament will happen first light. This is the LED filament lamp of a recessive cancer, but also a difficult to overcome the technical difficulties of COB filament. IC filament in the N root LED filament can be used in parallel to achieve N root LED filament current, improve the VF tolerance difference caused by defects.

The constant current IC bare chip directly to composite filament, and LED chip beads bound into a new generation of IC COB. LED was originally just a filament produced by LED packaging factory passive COB devices, after joining the IC constant current control chip, IC and LED for electronic filament filament from passive devices into step into a new generation of active electronic devices!

Therefore, the LED filament can control the electric current to achieve constant current sharing! The VF of the filament is no longer demanding! Perhaps the LED filament lamp thus eliminates the AC/DC constant current power supply, with the IC LED filament can make the LED filament lamp become a real electronic incandescent lamp!

Single channel two port linear constant current control IC

Single channel two port linear constant current control IC chip is a highly integrated constant current power supply chip, which consists of fine tuning, reference voltage, regulated power supply, temperature compensation, over temperature protection,