Color sensor from ipf ensures perfect ambience

ipf electronic presents an intelligent sensor system for seamless testing of light guide rods for ambient lighting in cars.

Nowadays, more and more cars are being equipped with light guide rods in the interior, e.g. in the dashboard area or in the door trim, for so-called ambient lighting, which is also intended to emphasize the design of the interior. Such light guide rods consist of semi-transparent flat strips in which the light induced laterally via LEDs spreads out. However, production-related defects in the light guide rods can have a negative effect on the light emitted, so that it is perceived as brighter or darker in some places and therefore as inhomogeneous. To avoid this, both the local intensity and the color of the light must be checked via the entire light guide rod.

Short light pulses with low intensity

Two major challenges arise from this task. The light from the LEDs only has a low intensity, as the aim is to create diffuse illumination in the vehicle interior. In addition, the LEDs are not dimmed via the power supply voltage, but by means of pulse width modulation. For this purpose, the LEDs are pulsed at a frequency that is imperceptible to the human eye, resulting in individual and very short light pulses instead of a constant light signal. Both the low light intensity and the pulse width modulation have therefore made continuous testing of light guide rods difficult to date.

Evaluable measurement signals through software amplification

Until now, because these challenges can now be overcome with the color sensor system from ipf electronic. The system consists of an optical system that is connected to an evaluation unit via a fiber optic cable. The evaluation unit has specially adapted electronics which, when parameterized accordingly via the associated PC operating software, enable both the light intensity and the light color to be evaluated. To prevent the sensor from detecting the individual light pulses generated by pulse width modulation, an adjustable average value is formed from previously collected signals for each RGB color. The features now consist of being able to generate evaluable measurement signals for each light color by means of amplification before and after averaging, whereby the signal level can be optimally adjusted using both parameters in order to prevent saturation of the sensor, among other things.

Seamless proof of quality

With the intelligent solution from ipf electronic, it is now possible to consistently check the light intensity and color of light rods. All measurement results can be saved via the software and thus the quality of production can be fully documented. As fiber optic rods are not only used in the automotive sector, but also in many other areas, the system is also recommended for testing indicator lights, which are integrated into white goods, steam cleaners or other everyday devices, for example.