The packaging of pharmaceutical products is regulated in most countries. Authorities expect that any printed information – such as product, use and storage data on the packaging material artwork or batch-specific data (e.g., expiration date) – is readable by the patient. Batch-specific data is commonly checked by vision systems using optical character verification. Pharmaceutical companies must be able to document traceability between what patients can read and understand, and how much of single characters can be ‘missing’ before they may be misread. While the term ‘readability’ in various regulations relates to the contrast between the background color and the text color (or to the font size), it does not consider how much that any missing parts of single characters may impact human interpretation of what is printed.
The purpose of the protocol is to use supporting data to establish how much of each single character can be missing before it is no longer perceived as the intended character. The report supplies the basis for defining acceptable character defects and supports setting up limits for vision systems to detect good/bad characters and minimize labeling errors. Also, so that a company knows what is sufficient for a patient to understand a printed character, the paper guides the definition of accept/reject settings so the production line will have a minimum number of false rejects (i.e., good items being rejected even if are deemed good).
The paper includes:
- A catalog of limit characters with parts of the character erased from the bottom, top, left and right – this provides knowledge about how much of a character can be erased before it becomes unreadable
- A table with corresponding scores for each limit character if parts of the character are erased and the maximum limit score for each character – this provides quantitative guidance for the limiting character
- Test sheets with the identified limit character value marked – this forms the basis for selecting the correct settings in vision systems so they can accept readable characters and reject unreadable ones.