After the chanting of the filament lamp, the LED minority sent this time without hesitation to extend the claws -
Are other manufacturers relieved? Well, on our blacklist, there is a long string...
For the filament lamp, COB is also good, compared with the problem of the product, the minority is more worried about the attitude of the company. We have considered "COB's Truth or Dare" as the title of this issue, but it seems a bit of joy, it is easy to make people think that it is the soul of the soul chicken, and finally give up. But looking at the state of China, is the playful attitude of "truthfulness and big adventures" not filled in the LED lighting industry?
Enterprises never dare to face up to the root of the problem, but they can skip it and skip it. Anyway, the technology is not enough to get the money together. Last week, the price butcher "Mullin Xiansen" bought 80% of the ultra-light source with 300 million yuan and excited the group of people who are not enterprising. I still remember last week, the filament lamp was greatly Touching a hand, the group is like playing the chicken blood, anyway, this virtue. Because they never tell the truth, companies can only choose to take risks -
Oh, yes, don't forget to bring your customers!
There is a saying in the market that LED spotlights are still non-COB. But you can ask one more question, why must it be COB? The answer is not enough. It is said that the COB light angle is small, the COB light color is good, and the customer just likes it.
To find out if COB is right or not, you have to look at what COB is. COB is Chip-On-Board, which originally refers to the packaging technology that integrates multiple semiconductor chips into one circuit board. In the LED industry, a plurality of LED chips are specifically packaged on a substrate to form a form of an illuminating light source (Fig. 1).
It is this product form that determines the technical characteristics of COB. The so-called "structural determining characteristics" in materials science also applies to products. Only by knowing this, can we carry out the following analysis.
COB rumors - small angle of illumination
We first to get rid of a rumor that the COB is widely spread - the angle of illumination is small. The illumination angle of the LED lamp bead is determined by the chip package. From the perspective of product structure, the COB package is nothing more than integrating multiple chips onto a single substrate, which is not fundamentally different from the package of a single chip, so the general COB and single package LED lights are the same - all are 120° light. It is considered that the COB illumination angle is small and it is inferred that the COB is more suitable for the spotlight source. For COB spotlights, the beam angle that defines the beam angle is the deep, light-influenced headlight cup.
COB rumors - better color temperature control and color rendering
The second rumor is that COB's color temperature and color rendering are better than the average single-chip package LED lamp beads. Don't forget, there is no essential difference between the COB and the package material used for a single LED bead. If it is necessary to say that it is also determined by the quality of the materials and production processes, it has nothing to do with the product form. So there is no basis for this argument.
COB's big adventure - heat dissipation, luminous efficiency and glare
Speaking of the shortcomings of COB, there are three words that must not be passed. That is, heat dissipation, luminous efficiency and glare. All issues are determined by the COB's own product structure.
For COB, heat dissipation is the first "Achilles' heel." Generally, the size of the 9W COB is a circle with a diameter of about 10 mm, which determines that it can only directly act on the heat source in this area, and the range outside the area is only used as an auxiliary for heat dissipation. For the same 9W SMD, the substrate diameter is generally about 100mm. For heat dissipation, the situation of low heat generation and large area heat dissipation is much better than that of high heat generation and small area heat dissipation.
As for the low thermal resistance that COB manufacturers have been advertised, it is actually said that the thermal conductivity is good. However, please note that the so-called "good thermal conductivity" is only able to derive the heat generated by the COB, and the subsequent treatment of the COB is completely passive. Just like a highway, the car is running very fast on the road, but it can be blocked at the toll station. This is similar to the situation of COB.
The second drawback of COB is light efficiency. Since a plurality of LED chips are closely arranged in a small area, the light emitted by the single chip in the horizontal direction encounters the adjacent chips and continuously forms a total reflection, and is finally absorbed by the packaging material and cannot be emitted. For SMD, as long as the spacing is reasonable, there is no such problem (see Figure 2). It is this total reflection that makes the COB's luminous efficiency 10% lower than the surface mounting of the LED lamp bead from the beginning. At the same time, the encapsulation material absorbs the heat caused by the horizontal light and the heat generated by the dense arrangement of the chip itself, resulting in a high COB operating temperature, which again affects the chip light effect. Even with the same chip, the COB is about 20 lm/W less than the surface mount.
The third drawback is glare. Also based on the small area and high power of COB, there is inevitably a problem of glare. Basically, the spotlights using COB must be equipped with a very deep lamp cup, in addition to the need to distribute light to prevent excessive glare.
Since COB has so many problems, it has become the main source of spotlights. It is very simple. Because COB's product form is closest to traditional light sources, the original lamp cups, lamps, and design methods can be copied (noticing, This is similar to the logic of the filament lamp).
As for the shortcomings... Who cares? Anyway, "customers like it"!
But this customer is not an end user on the market, but a lighting designer. Why is an emerging industry still so obsessively paying for the old design without distinction? Let's review the history of COB development.
The emergence of COB light sources was around 2008. At that time, it was to solve the problem of "ghosting" of LED lamps. Under the illumination of LED lamps, the object will produce several shadows that do not completely overlap, which makes the eyes feel dizzy. There were two solutions at the time:
1) Add a film (light-emitting plate) that is not completely transparent before the LED light source. This solution has a big problem. At that time, the luminous efficiency of the LED is not high, and the light-emitting panel makes the overall light effect lower. Based on this concern, the second solution came into being...
2) Start with the improvement of the light source and eliminate the “ghost†on the light source. This is the original motivation for COB development, but it was quickly abandoned. The reason is very simple. The COB belongs to the secondary package. The technology and process are relatively complicated. With the technology of a single piece of COB at that time, as long as it exceeds 35W, there is no way to maintain the quality stability in mass production, and its light efficiency and heat dissipation are not comparable to surface mounting. The first show of COB in the market quietly ended.
In the current environment, the development of COB has its rationality, which is essentially different from the subsequent redevelopment of COB. The second spring of COB was re-invented in 2012 as a new light source. The motivation is the market's disappointment over the long-term stagnation of LED products. However, the technical problems that lie ahead of the COB have not improved over time, and are still hindered by the encapsulation and high-power quality stability.
In 2015, the COB was "fired" again. If the first two developments of COB promoted the LED industry, then this time is purely to "connect with the old tradition", which is essentially a retrogression. It is true that COB solves the problem of “ghostingâ€, but previous developments have proved that COB is more harmful than good in this respect. Although the significant improvement in lamp performance has created a good technical foundation for COB packaging, it has finally met the application needs of the market. All of this looks good, but the underlying logic of the COB product form makes it impossible for the best technology to make up for its own flaws. And it is precisely based on the objective temptation of good technology that designers who are unfamiliar with LED characteristics are rolling further and further on the wrong road.
How the product is understood, how it is designed;
How products are designed and treated.
So the industry is not down for no reason!
The minority has said more than once that a good product is a humanity appeal, while a bad product attempts to impose some inappropriate features on the user to make a profit. These two points are reflected in the COB spotlights.
First, the current system design of LED luminaires is generally unfamiliar or even unintelligible (presumably only staying on energy saving), resulting in a trend toward traditional “reaction†in the whole lamp design, rather than actively seeking forward solutions. Program. Whether it is a virtual fire filament lamp or a widely used COB spotlight, this problem is deeply reflected. Get rid of the confusion of new things, return to the embrace of the old tradition - this is the urgent and certain psychological appeal of the "customers" whole lamp manufacturers of the packaging factory. How long can this anti-progressive appeal last?
Secondly, from the market reaction, users obviously do not agree with the old product form to carry the new light source technology, such as the "old bottled new wine" approach, from the overall cold reception of the filament lamp in the application market, to the COB spotlight after a short price The rapid price cut back to the "winning by price" can be seen in the market's thirst for new forms of lighting products and disappointment with current products.
Only by facing the problem can you break through the limits and go beyond the ordinary! From the origin of the problem, your adventure is a worthwhile adventure, and it will eventually lead you to discover a new continent, rather than falling into a more vast unknown.
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