Visibility evaluation of invisible information display lighting device

In the modern information society, applications of smartphone expand with the advance and integration of semiconductor technology. Many of these smartphones are equipped with camera functions. Due to performance improvements of CMOS image sensors, it has become possible to easily take pictures with high quality. Furthermore, advanced semiconductor technology can promote widespread dissemination of many types of LED lighting. We have developed an invisible information display lighting device. In the present study, an information recognition application is developed to adjust the camera function on a smartphone with the aim of practical application of the invisible information display lighting device. Several experiments are carried out to evaluate the readability qualitatively. This device shows several types of information, which can be recognized via the camera function on a smartphone and cannot be seen by the naked eye.