In a vehicle, bulbs called the P-group are responsible for warning other drivers or pedestrians and they are known as signal bulbs. Signal bulbs have been used to emit warning and hazard signs in parts such as brake lights, direction indicator, hazard lights (night vision) as well as tail bulbs and car park alarms. There has been limited researches on the photometric characteristics of these lamps, but a review of these studies revealed that no detailed research has yet been done on optimizing these characteristics, and there is a scientific gap. In this study, factors affecting the service life and luminous flux were evaluated by using Taguchi design of experiments method. The results showed that the two factors of weight percent composition of bubble filling neutral gases and the volumetric efficiency of gases injected into the bubble had the most influence on the target parameters. Experimental results showed that the optimum composition of neutral gases injected into the bulb bubble can extend the bulb service life to approximately 341 h, which is three times the service life of a bulb with the inappropriate composition of fill gases. Then the optimum state of the service life and the luminous flux were determined to meet the reference standards. Although the service life and luminous flux parameters were able to reach 341 h and 513 lumens in the maximized state, however, in the optimum state with satisfying reference standards, the service life and luminous flux were 330 h and 463 lumens, respectively. Then, the bulb bubble filling with inert neutral gases and its effect on the bulb service life was investigated. The results showed that if the volumetric efficiency of gas injection increased from the normal 75%–100%, the service life of the test lamps would be improved by about 10%.

在车辆中，称为P组的灯泡负责警告其他驾驶员或行人，它们被称为信号灯泡。信号灯泡已用于在诸如刹车灯，方向指示灯，危险信号灯（夜视）以及尾灯泡和停车场警报器等部件中发出警告和危险信号。关于这些灯的光度特性的研究有限，但是对这些研究的回顾表明，关于优化这些特性的详细研究尚未完成，并且存在科学空白。在这项研究中，使用田口设计的实验方法评估了影响使用寿命和光通量的因素。结果表明，气泡填充中性气体的重量百分比组成和注入气泡中的气体的体积效率这两个因素对目标参数的影响最大。实验结果表明，注入到灯泡泡中的中性气体的最佳组成可以将灯泡的使用寿命延长到大约341小时，这是填充气体成分不当的灯泡的使用寿命的三倍。然后确定使用寿命和光通量的最佳状态，以满足参考标准。尽管在最大状态下使用寿命和光通量参数能够达到341 h和513流明，但是，在满足参考标准的最佳状态下，使用寿命和光通量分别为330 h和463流明。然后，研究了用惰性中性气体填充的灯泡气泡及其对灯泡使用寿命的影响。结果表明，如果气体注入的体积效率从正常的75％–100％提高，则测试灯的使用寿命将提高约10％。