LED 的使用寿命
LED 制造商声称，其产品的使用寿命约为 50,000 至 100,000 小时，亮度才会下降到原始值的 50%。要做到这一点，使用时的工作温度和环境温度必须达到最佳状态。在实际条件下，使用最好的 LED，使用寿命可达到约 25,000 小时；在运行 10,000 小时后，亮度会略有下降。
闪光操作（与图像采集精确同步）大大延长了使用寿命。只有在需要采集图像时才打开 LED。所使用的控制不允许有任何明显的延迟，以便 LED 立即达到最大亮度。典型的占空比为 1:10；但如果使用高效 LED 和精确同步，在许多应用中，占空比甚至可以大于 1:1000。
典型照明应用示例：占空比 1:100，500 µs 光脉冲和 50 ms 暂停。与恒定照明的比较见下图。
在此示例中，假定工作时间为 10,000 小时，只有在使用 720 亿次后（相当于全天候工作 115 年），亮度才会首次降低。
超控
可以通过超控来增加灯光强度。但是，LED 的发热速度高于平均水平，因此必须有足够的时间冷却，以免造成不可修复的损坏。因此，为避免过热，灯光必须闪烁（最多占空比的 10%）。
B&R 照明系统
B&R 照明系统通过 POWERLINK 与智能摄像机或传感器实时同步。这意味着外部照明的闪烁也与摄像机传感器的快门时间精确同步到 µs。在机器视觉行业中，外部照明灯通常要么完全不闪，要么在没有图像采集时亮起。即使这样做 4 年后灯的亮度仍能保持 50%，图像处理也必须因这一变化而更快地进行调整。通过数字输入与图像采集同步的外置闪光灯控制器来控制灯光的效果要好得多。但即使是这种控制方式，也会导致闪光灯的闪烁时间超过所需的时间，因为由于延迟（在某些情况下甚至与温度有关），灯光会在实际图像采集前后开启。例如，如果只需要 500 µs 的闪烁时间，那么灯的开关时间前后相差无几是很正常的。这将导致占空比延长 3 倍，从而大大缩短使用寿命。许多闪光灯控制器的上升时间（直到达到最大电流和最大亮度）也在 2 位数 µs 范围内。特别是在曝光时间很短的情况下，必须考虑到这一点。
带有内置闪光控制器的 B&R 灯只在实际需要时才会亮起，亮度上升时间大大低于 1 µs。
Service life of LEDs
LED manufacturers claim that their products have a service life of around 50,000 to 100,000 hours before the brightness falls to 50% of the original value. For this to be possible, the operating and ambient temperatures during use must be optimal. Under realistic conditions and using the best LEDs, a service life of approx. 25,000 hrs can be assumed; a slight reduction in brightness can already be observed after 10,000 operation hours.
Flash operation (together with precise synchronization with image acquisition) significantly extends the service life. The LED is only switched on if it is necessary for image acquisition. The control used is not permitted to have any significant delay so that the LED reaches its full brightness immediately. The typical duty cycle is 1:10; however, with efficient LEDs and precise synchronization, it can even be greater than 1:1000 in many applications.
An example of a typical lighting application: Duty cycle 1:100, 500 µs light pulse and 50 ms pause. See the following figure for a comparison with constant lighting.
In this example, for 10,000 assumed operating hours, the first reduction in brightness is only expected after a period of use of 72 billion cycles (corresponds to 24/7 operation over 115 years).
Override
The lights can be overridden to increase the light intensity. However, the LED heats up at an above-average rate, and must therefore have enough time to cool down in order not to be irreparably damaged. To avoid overheating, the lights must therefore be flashed (max. 10% of the duty cycle).
B&R lighting systems
B&R lighting systems are synchronized in real time via POWERLINK using smart cameras or sensors. This means that the flashing of external lighting is also exactly synchronized to the µs with the camera sensor's shutter time. In the machine vision industry, it is still the norm for external lights to either not flash at all or to light up when no image acquisition is taking place. Even if the light still retains 50% of its brightness after 4 years of this, the image processing must still be adjusted much sooner due to this change. It is far better to control a light with an external flash controller that is synchronized with image acquisition via a digital input. But even this control results in longer flashes than necessary since, due to the latencies, which in some cases are even dependent on temperature, the light is switched on before and after the actual image acquisition. If a flash of only 500 µs is needed, for example, it is not uncommon for the light to be switched on and off for around the same time before and after. That results in a duty cycle that is 3 times longer and thus to a significant reduction in service life. The rise time (until the maximum current and thus the maximum brightness is reached) is also in the 2-digit µs range for many flash controllers. That must be taken into account for very short exposure times in particular.
B&R lights with built-in flash controllers only light up when they are actually needed, with a brightness rise time of significantly less than 1 µs.