LED的效率如何？

通常，我看到的效率与每瓦流明相关，但是从电能输入到光能输出方面，LED的实际典型效率是多少？什么样的转换适用？

To make things clear let's define what we are talking about.

There are two terms which are mixed up pretty often:

• Luminous efficiency:

发光效率是无量纲的量，其是从发光效率得出的。它只是光源的发光效率与辐射的最大可能发光效率的商。

• 发光功效：

这是您经常看到的值。通常以每瓦流明为单位。并给出每功率的光通量，这对于查看给定功率下我们将得到多少光是有用的量。

与此同时，我们也必须小心一点。因为功率可以是源的辐射通量，也可以是电能。因此前者可以称为辐射的发光功效，而后者可以称为光源的发光功效或总体发光功效。

现在出现了问题，我们不能平等地看到所有颜色。流明实际上是根据我们眼睛的反应加权的：

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因此，您可以创建一些上限值（基于单位candela的重新定义）。这就是辐射的发光功效。

哪个是：

• 555 nm处的绿光：683 lm / W
• 在5800K时CRI = 95的最大值：310 lm / W（基于截短的黑体辐射器）
• 2800 K时CRI = 95的最大值：370 lm / W

有关更多信息，请参见此处。

如果降低显色指数（CRI），则可以实现更高的值。但不高于683 lm / W。

那么，LED的效率如何？

在这里，我们具有光源的发光效率值。

好吧，这是一场效率竞赛。克里发布了新闻稿，其5150K时的303 lm / W实验室LED灯。没有提到CRI，我猜它低于95，但是根据上面的数据，它的发光效率似乎在80％到90％之间。

当然，您的平均可用LED更少。100 lm / W约为25％至30％，而最近宣布的新200 lm / W芯片（截至2017年8月）达到50％至60％。

请注意，以上内容仅适用于明视觉（日视），随暗视而变化的事物通常并不那么有趣。

如果您真的想深入了解它，则必须获取LED的光谱，并找出该光谱的最高理论最大值（基于权重曲线），然后才能计算出该值。

As each and every LED has a different spectrum it is hard to get this data easily.

_{^{I hope I haven't made a mistake here, because I always find the topic a bit confusing no matter how many times I revisit it.}}

As noted in the comments, it depends.

Older LEDs often have a lower efficiency than newer types.

Some bulbs have more efficient electronics to convert the mains voltage to the DC voltage needed for the LEDs.

But for a given LED light bulb you could make an estimate as often the amount of power needed by an incandescent light (with a similar amount of light output) is printed on the box. According to Wikipedia the average efficiency of an incandescent light bulb is 2.2 %.

Lets take the Ikea "LEDARE" E-27 600 lumen light bulb as an example:

Equivalent power for incandescent bulb: 48 W Actual power used: 8.6 W

So that means this bulb claims to be 48 / 8.6 = 5.6

times more efficient than an incandescent bulb so that would result in:

5.6 * 2.2 % = 12.3 % efficiency.

For this Ikea Ledare lamp.

Note that this is the total efficiency so the efficiency of the electronics times the efficiency of the LEDs themselves.

Proper LED driver electronics should have an efficiency of 85 - 99 % (that is my personal guess !) So the actual efficiency of the LEDs will be slightly higher than the 12.3 % I just calculated.

That's assuming all numbers given by Ikea are true of course.

You need 1/683W of power to generate 1 lumen of light. It means that efficiency is somewhere around 12%. This is how it goes:

Firstly, let's assume that we have a light that radiates equally to all directions. By definition, 1 candela is 1/683W (550nm monochromatic light). 1 candela radiates to 1 steradian angle, which is 1/4π (8%) of the full sphere surface area. So, you need 4π/683W to produce 1 candela to all directions and the total luminous flux is 4π = 12,6 lm.

Which power is equal to 1 lm? You get it by dividing 4π/683W by 4π and the end result is (4π/683W) / 4π = 1/683W. Essentially, you need 1/683W of power to create 1 lumen luminous flux (1/4π = 0,08 candela to all 1 steradian angles).

Using above figure you need 900 times 1/683W = 1,32W to produce 900 lumen luminous flux.

My real light bulb, procured from a local store, state 900 lm and 11W of electric power. I assume that it radiates light equally to all directions. Using previous figures, electrical efficiency of the bulb is 1,32 W / 11 W = 0,12 which is equivalent to 12% efficiency.