1. INTRODUCTION:
: Printing is the widest and fastest form of usual
communication. The word “CtP” defines -The Master of Image Transferring
Techniques.
Necessity is the mother of Invention
-Proverb
In this technological world “CtP” has become a buzzword for the Image Quality
in Printing Due to the necessary aspects such as
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Short turn around time
High image
quality
Easy access in Image transferring techniques
The full form of CtP is COMPUTER TO PLATE.
2. DEFINITION OF CTPDEFINITION OF CTP
In the graphic arts industry, the computer-to-plate (CtP) has digitalized the
process of plate making and the new platesetting systems use laser beams to
directly write images onto printing plates rather than first exposing a film
then transferring the image to the plate. The digital direct plate imaging
method eliminates troublesome film processes.
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Computer to plate system for automatically imaging and developing Printing plates
(Platesetter 3244, Heidelberg/Creo)
3. CTP TECHNOLOGYCTP TECHNOLOGY
There are many different types of Plate setters used for Offset Printing in CtP
systems and there are three basic designs namely Flatbed, Internal drum,
External
drum. Each design has its advantage and each one is accurate in its imaging
capabilities.
A Typical View of a Flatbed CtP System - working mechanism
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4. Internal Drum CtPInternal Drum CtP
The internal drum plate setter design resembles the letter "C" because of
its open concave design.
A single laser beam write the digital image onto the plate. The laser beam
is projected onto a spinning mirror that rotates at a very high speed.
In order to change the resolution of the image on the plate, the diameter of
the laser beam is changed.
A Typical View of a Internal Drum CtP System - working mechanism
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5. External Drum CtPExternal Drum CtP
External drum plate setters are designed to have the plate mounted on the
outside of the drum.
As the drum rotates on its axis, a multiple beam laser head moves parallel to
the drum and burns the image on the plate.
To achieve high quality results, the drum must spin accurately in order for the
imaging head to maintain optimum beam intensity.
A Typical View of a External Drum CtP System - working mechanism
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6. CTP eliminates the steps required for conventional plate making, which
requires a film workflow and stripping operations and thus saves a
considerable amount of time.
Human error is reduced with the elimination
of manual stripping and plate making.
Storing digital images is easier, safer and more efficient than storing film and
flats which can be damaged by storage or handling and they also require large
amounts of physical space where else digital images where look consistent,
clear, and sharp and space saving
Print quality is improved because the dot gain associated with imaging plates
from film is eliminated. In fact, with a film workflow, dot gain may be as much
as 5 or 6 percent.
The reduction in potential dot gain allows denser inks to be used at the press,
this provides improved color saturation and print quality.
Copy changes are much easier with CTP because changes are made to a digital
file, which is imaged onto a plate rather than having to produce new films and
strip them into a flat for burning onto the plate.
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ADVANTAGES OF CTP IN PRINTING PROCESSADVANTAGES OF CTP IN PRINTING PROCESS
7. EXPOSING EFFECT IN CTP TECHNOLOGYEXPOSING EFFECT IN CTP TECHNOLOGY
Laser:
LASER – “Light Amplification by Stimulated Emission of Radiation” is the
concept of stimulated emission first postulated by Albert Einstein in 1947where
light is produced by atomic process. There are different types of lasers used in
CtP
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8. COMMONLY USED LASERS IN CTP SYSTEMSCOMMONLY USED LASERS IN CTP SYSTEMS
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9. GLV TECHNOLOGYGLV TECHNOLOGY
When GLV (Grating Light Valve) technology is used in CTP
systems, it allows for the best image quality and speed in
production. The technology is often used in external drum
plate setters for CTP systems as well as in high definition
television.
GLV technology uses Micro Electro Mechanical
Systems (MEMS), which allows for microscopic structures to form on
silicon chips.
The structures are reflective and are constructed of
several ribbon-like elements that can be moved up and down through the
control of electrostatic forces. The motion of the ribbons covers only a
small distance, which is equal to a fraction of the wavelength of light. The
different ribbon elements are configured in a pattern that allows the
structures to reflect and diffract light waves, which varies the level of light
reflected from the surface of the silicon chip.
Imaging optics for GLV based
CTP systems provides a larger quantity of writing beams, which means
that the imaging drum rotation speed can be reduced while still providing a
greater degree of productivity. GLV technology is most often used in
conjunction with several thermal (infrared) CTP systems.
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10. DIFFERENT TYPES OF PLATES IN CTPDIFFERENT TYPES OF PLATES IN CTP
Some of the major Printing Plate varieties used In CtP systems are
Aluminum-based Printing Plates
Thermal-sensitive Aluminum Plates
Photopolymer Plates
Hybrid CtP Plates
Silver halide Plates.
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11. WORKFLOW OF CTP TECHNOLOGYWORKFLOW OF CTP TECHNOLOGY
The most common workflow is shown in this assumes that there is a print shop
that receives digitally printing data from outside and first of all checks it for
completeness, correctness, and printability in the so-called “preflight check.”
and then imposition is done and the file was send to raster image processor
(RIP) and checked and agreed by the proffer and then the file is returned and
ready to expose the command was given and the Plate was kept in the
Platesetter and first it will be punched and then exposed with a laser light the
exposed plate was immediately Processed in Automatic Plate Processor.
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12. PROCESSLESS PLATES IN CTP TECHNOLOGYPROCESSLESS PLATES IN CTP TECHNOLOGY
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Process less CTP plates have several advantages over chemically
processed plates. Some of them are listed below.
Process less CTP plate systems require a lower initial
investment
the plates are daylight safe, and because the system requires
fewer steps than chemically processed CTP plate systems
process less plates are less labor intensive.
Less equipment is necessary because there is no need for
large processing units.
There are no chemicals needed for development of the plates and so there are no
environmental issues with the proper disposal of chemicals
Process less plates are ideal for smaller print providers that often produce jobs
under 100,000 impressions.
All of these advantages add up to a significant long term cost savings, a
process that is environmentally friendly and a system that is easier, safer, and less
time consuming for people to use.
13. ADVANCE TECHNOLOGY IN PRINTINGADVANCE TECHNOLOGY IN PRINTING
Offset printing systems have been developed that not only eliminate film
From the workflow, but also eliminate the plate as well.
These systems are known as computer-to-press
offset printing systems. The Man-Roland DICO web (DICO
stands for "Digital Changeover") is one such system. The DICO web uses
lasers and a thermal ribbon to create images on removable cylinders.
A thermal material, which becomes the image area, is transferred to the plate
A wetting agent keeps the non-image areas clean during the print run.
A short run of 500 impressions can be produced immediately after imaging.
When a longer run is required, the thermal material must be baked onto the cylinder, but
this additional step requires only two minutes.
When the printing is complete, the thermal image material is automatically cleaned from the
plate cylinder so that the cylinder can be ready for reimaging for the next job.
The entire process of imaging and cleaning requires less than 12 minutes to complete and a
resolution of 3200 dpi can be achieved.
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WORKING MECHANISM OF NEW TECHNOLOGY
14. Bibliography
Computer to Plate Technology
Books Referred - Latest Trends in Printing, Basics of Computer
to plate Technology.
Websites Referred - WWW.ModernCtpTechnology.com,
WWW.Project Gutenberg. COM, WWW.Graphic Brain.com
Conclusion
Printing Industry is a vast industry in which inventions blooms
day by day, in that CTP Technology is a wonder and we Printers
should use it in an efficient and brilliant way. Though computer to
printing has a rise, Computer to plate ever has its own market in
all classes of business.
Acknowledgement
I thank my college -Institute of Printing Technology for
encouraging and supporting to participate in this “State Level
Technical Symposium”. And I also thank C.S.I Polytechnic
College for giving me this marvelous opportunity.
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Technology000
