The present invention relates to grinding balls made of fritted ceramic comprising a compound of alumina silicate and in particular mullite, zirconia and alumina. An imaging apparatus 10 is configured including an optical system 12, an image pickup device 14, an image capture correction processing section 16, and an image processing section 18. A game engine program presents a game play scenario to a user via a user interface of the game. Half of the screen disks are provided with a cleaning device for cleaning the clearances between the screen disks. A second conductive layer is formed over a second temporary carrier having rounded indentations. Such source voltage variations can impair or even prevent proper operation of the electronic circuits within the portable device.