ฉันรักแปลInternal drum imagesetters Edit
In an internal drum image setter the plate is put into a cylinder, while the imaging head moves along the axis of the cylinder to expose the plate. The rotating mirror at the end of the imaging head rotates around its axis to beam the laser on the desired part of the fixed plate. The construction type makes it more difficult to use several lasers at the same time, but just using one laser also has advantages such as uniform beam intensity over the whole plate.[1]
External drum image setters Edit
The plate is wrapped around a drum that can rotate around its axis, while the imaging head that projects the image on the plate can move along this axis to focus the laser beam on the surface. The simple construction type makes it possible to arrange multiple image heads next to each other and use them simultaneously. This leads to a decrease of the imaging time needed to expose a whole printing plate.[1]
Flat-bed image setters Edit
The image is reproduced line by line on a fixed flat printing plate by a laser beam that is deflected by a rotating polygon mirror and then onto the printing plate. Because of the setup the laser beam becomes less accurate at the edges of the printing plate and is therefore mainly smaller formats or production with lower quality expectations.[1]