Computer To Plate

Computer to Plate(CTP) : is an imaging technology used in a modern printing process. An image created in Desktop Publishing (DTP) is outputted directly to a printing plate.

Technology

Internal Drum Imagesetters
An imaging head rotates around the axis to a laser on the desired part of the plate. The construction type makes it more difficult to use several lasers at the same time, but just using one laser also has advantages like uniform beam intensity over the whole plate.

External Drum Imagesetters
The simple set up of this makes it easy to arrange multiple image heads next to each other. This decreases the amount of time it takes to finalize the plate.

Flat Bed Image Setters
The image is conducted line by line on a printing plate. Because of this setup the beam is less accurate at the edges on the printing plate, therefore the plate may have lower quality expectations.


Types of CTP

The types of plates used in this printing process are:

Photopolymer Plates
These plates have a photosensitivity between 400 and 500 nm and can run prints up to as man as 200,000 at a time.

Silverhalogen plates
These plates are aluminum printing plates, and have a photosensitivity of 400 and 700 nm. They can run prints up to as many as 150,000 at a time and have a dot reproduction of 1-99%.

Thermal plates
Processing with these plates in the day light is possible. They also have a dot reproduction of 1-99%. This printing process, lower than the silverhalogen and photopolymer plates, can run up to 100,000 prints and it’s photosensitivity is between 830 – 1.070 nm.


direct_to_plate
Direct to plate
CTP_1
CTP




Pros and Cons of Computer to Plate Printing

The Advantages of CTP printing compaired to conventional plate making is that the detail is increased and sharper. This processes avoids loss in quality and scratches in the finished product. This way of printing is also more time and cost effective

The dis-advantages of CTP printing are it is restricted to only digital format, and if an error is made, the whole process has to be started over again.
CTP
http://www.youtube.com/watch?v=M7a5UZoovC4