Having recently been through all the standards for a patient monitor, I am not aware of any strict limits for the size of information, except as already mentioned in relation to alarms (IEC 60601-1-8).
The alarm standard (-1-8) requires that the user must be able to tell the type of alarm (e.g. which parameter, physiological or technical, etc) from a distance of 1m (the 4m requirement is only for the main alarm signal). Since the alarm information is often the same size as the normal information, this would appear to set a defacto minimum of 1m as derived from a technical standard. That said, the 1m requirement allows for fonts down to 2-3mm which is well below the typical size most patient monitors use for key data like heart rate and so on.
Although it seems to make sense to derive a size from the intended purpose, in practice this is one area where many trade-offs have to be made (cramming lots of stuff in a small display that has to be small to be portable) and also is impacted by available technology (e.g. viewing angle, brightness, contrast etc). Realistically it's a case of just doing the best you can, since it is unlikely to be able to meet all needs at the same time.
The alarm standard (-1-8) requires that the user must be able to tell the type of alarm (e.g. which parameter, physiological or technical, etc) from a distance of 1m (the 4m requirement is only for the main alarm signal). Since the alarm information is often the same size as the normal information, this would appear to set a defacto minimum of 1m as derived from a technical standard. That said, the 1m requirement allows for fonts down to 2-3mm which is well below the typical size most patient monitors use for key data like heart rate and so on.
Although it seems to make sense to derive a size from the intended purpose, in practice this is one area where many trade-offs have to be made (cramming lots of stuff in a small display that has to be small to be portable) and also is impacted by available technology (e.g. viewing angle, brightness, contrast etc). Realistically it's a case of just doing the best you can, since it is unlikely to be able to meet all needs at the same time.