The optimization of a non-contact type Electric-Potential Sensor was conducted using the Quality Engineering approach. This type of sensor is used for the electronic photographic devices such as copy machines. The electric potential of the drum surface varies due to environmental conditions such as temperature, humidity or endurance. The sensor measures electric potential and gives feedback to the image formation process. A 6 db gain was confirmed after the optimization, which is equivalent to an annual gain of 7.5 million yen.
