Method and system for simultaneous loading and unloading of substrates in platestter

An external drum imaging engine, comprising

• a drum on which substrates are installed;
• an scanner for exposing the substrates that are installed on the drum;
• two fixed header clamps positioned to at different locations around the circumference of the drum for clamping headers of different substrates to the drum;
• and
• at least one trailing edge clamp for clamping trailing edges of substrates on the drum, the at least one trailing edge clamp being a magnetic clamp.

An external drum imaging engine, comprising

• a drum on which substrates are installed;
• an scanner for exposing the substrates that are installed on the drum;
• two fixed header clamps positioned to at different locations around the circumference of the drum for clamping headers of different substrates to the drum;
• and
• at least one trailing edge clamp for clamping trailing edges of substrates on the drum;
• wherein the header clamps are only operational on alternative substrate exposing steps.

An external drum imaging engine, comprising

• a drum on which substrates are installed;
• an scanner for exposing the substrates that are installed on the drum;
• two fixed header clamps positioned to at different locations around the circumference of the drum for clamping headers of different substrates to the drum;
• and
• at least one trailing edge clamp for clamping trailing edges of substrates on the drum;
• two input/output ports, each port either supplying or receiving a substrate while the other port receives or supplies, respectively, a substrate.

An external drum imaging engine, comprising

• a drum on which substrates are installed;
• an scanner for exposing the substrates that are installed on the drum;
• two fixed header clamps positioned to at different locations around the circumference of the drum for clamping headers of different substrates to the drum;
• and
• two trailing edge clamps for clamping trailing edges of different substrates on the drum;
• wherein the two trailing edge clamps are never clamping substrates to the drum at the same time.