Problem: In order to compile a production control history, data such as the lot number, serial number, and production date has to be documented for each panel. Using a paper-based system, though, makes it difficult to achieve complete production control starting at the initial stages of the process. It would be helpful if the panels could be controlled individually instead of in lots. Use an exposure device to directly mark each panel with a 2-dimensional code containing the production data for the glass substrate and the process history data. Read the 2-dimensional codes with a 2-dimensional Code Reader, and control the entire production process over a network.