The led application of vehicle system has many advantage. in car led system, most vehicles employed that 6000K color temperature led. because the band of color temperature close to natural light, so it is comfortable for human’eyes. other words: in night , the capability of distinctions color of person are the best in natural light.
The life time of led is long that traditional light device(just like Tungsten lamp) ,and more stable & reliable.
The starting speed of led is fast that traditional lamp. example the break led light starting time was shot in 50ms, and the tungsten lamp starting time about 300ms.
The led is solid state light source, led would come under greater shock.
The new current limiter —- limiting capacitor
A few days ago, We are talking about LED indicator light, some one mentioned that capacitor limiting .i think this is good idea for reducing energy loses. it is low power that resister limiting .
In general , the indicator led of patch board adopt 1/4w 220k resister to limiting current . the electricity consumption of resister as 0.2W, it looks small. if the indicator led work long hour, for example: which also consumes 1.75 kilowatt hours a year.
in the moment, we think that implementation of capacitor to limiting current for led indicator. because the capacitor is reactive energy device in alternating current .
Detection method of uv led strip
In this paper, the various detection method of uv led strip was studied.
Red Dye Penetration Test (Dye&Pry): to verify that air tightness of uv led strip.
Temperature shock Test: comprehensive performance test and analysis of uv led strip with thermo-shock test and cold-shock test
Salt fog Test: Salt fog Test was applied to the test of corrosion resistance of uv led strip.
High Thermal Cycling Test: use the High Thermal Cycling Test to inspect that Anti-aging Performance of uv led strip.
led reverse voltage and reverse breakdown voltage
First we need to clear out of two concept— led reverse voltage and reverse breakdown voltage 。
*led reverse voltage: we will call it “reverse voltage” when just make reverse voltage for led, in general there are not have numerical definition for reverse voltage ,and no matter the input voltage how big.,only condition is opposite directed . this is led reverse voltage.
*led reverse breakdown voltage, the most character of led reverse breakdown voltage is that the led reverse breakdown voltage has numerical definition . the PN junction have been zener or avalanche breakdown emerged from led reverse breakdown voltage(when the reverse current meet specification value).this situation we will call it” led reverse breakdown voltage”.
PWM can’t damage LED
Many engineer ask me a question that use PWM to drive LED whether LED will be affected .
First LED is diode that it can achieve rapid switch(The application of quick switch technology in LED). which is incomparable to other component .
Hence, just only converted power supply to constant current source, then with adjust pulse width way to change the bright of LED. the way call PWM(pulse width modulation ). suppose the cycle of pulse as tpwm and width of pulse as ton, that duct cycle as ton/tpwm. adjust the duct cycle of constant current pulse can change the LED bright . so You trust to use the PWM.
BOOST and BUCK IC
We generally adopted led constant current ic to drive LED. the constant current ic is divided into three kind: BOOST , BUCK and BOOST & buck.
the engineer rarely use the BOOST & buck IC , because it’s much more expensive than others. now we are get a question that how to choose BUCK and BOOST for our project. base on the follow way to chose the appropriate DC-DC for your project.
Input voltage is big than load voltage, please chose the BUCK IC
contrary, the load voltage is big input voltage, please chose the BOOST IC.
Chromatogram offsets
The line of chromatogram curve offsets distinctly when adjust led currently. what the reason for that?
We are know that the white light come form blue led excite by yellow phosphor . when forward current is reduce , the blue led light actually increased and the yellow phosphor wasn’t given portion of reduce , and it will cause main wave length of spectrum is increased. so blue led light directly affect spectrum and color temperature . for example:
when the forward current at350mA, the color temperature as 5734K.
when the forward current current increase to 350mA, the color temperature will offset to 5636K. the color temperature will change to warm white when the current further reduce,
LED rendering index level(LED Ra)
Question one :what is rendering index for led chip? when led light fall on certain thing it represents the ability of rendering , we ‘ll call it ”rendering index” rendering index is import condition for evaluation of led quality . also is import method for evaluation of led source color rendering . which is widely applied right now . the higher the rendering index, the better the rendering . we can used the evaluation criteria to description the rending level:
Ra value < 50 as “bad”
Ra value >50 and <70 as “general”
Ra value >70 and <80 as “good”
Ra value >80 as “excellent”
At present , the led source of www.ledlightmake.com’ led can up to Ra≥97, can accept this personalized customization
LED infuse gum
LED can be used in the room displays , as well as the outside. it’s good value to consider led a proof water .there are has two kind of way to proof water.
1、assembly sleeve：first Select socket and spigot type. then put the led strip into sleeve final the two ends of sleeve are sealed.
2、infuse gum：led worker was given in was given on led strip.
let’s now discuss the simply of infuse gum process:
1、 Clean the surface of LED: clean the surface of led strip with friendship environment plate washer water .
2、 Put the led to infuse gum fixture: place the led strip on a flat fixture.
3、 Ruing the infuse gum machine: turn on infuse gum machine prepare to infuse gum. in here we should note that exhaust hole of infuse gum machine . Vents are formed on the edge of the depression of the plastic rubber body, which can play the ventilating function during the rubber injecting operation.
4、 dry by the fire :put the led strip in the oven and let them roast for six ~ eight hours. or dry naturally for twenty hour after infuse gum .
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