In my project, I am using USB camera modules to observe cell migration. In former experiments, I used Desktop PCs with ubuntu 14.04 LTS.
When i measured the temperature of the built in image processor chips of the camera modules, they developed heat only when I asked them to take a picture. After the camera module finished taking the picture and it was sent to the PC, it switched to a "stand by mode", and the image processor chip cooled down.
When i try the same with the raspberryPi 2 with Raspbian, the camera starts to develop heat as soon as I connect it, and stays hot until I disconnect it from the USB plug.
Does anyone know a reason for the different behaviour of the USB camera at the different systems?