Patent ID: 8677721

Claim:
An apparatus for marking individual filled plastic containers made of PET, comprising a marking device which applies a marking to the containers wherein the marking device heats a wall of the container to melt the material of the container locally at a surface thereof, and a checking device which checks for the presence of the marking on the containers, wherein the checking device comprises a temperature-sensitive sensor containing an infrared-sensitive semiconductor sensor which measures whether a temperature increase has taken place locally in a region in which the marking is to be applied and outputs measured values to a processor device, wherein the apparatus includes a transport device to transport the containers in a transport direction and wherein the apparatus further comprises a processor device which receives measured values output by the checking device and compares said values with stored values, taking into account an external temperature in the region of the containers and transport speed of the containers to ascertain whether a marking has been applied to a container, wherein the checking device is arranged immediately after the marking device in the transport direction of the containers.