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KYOCERA Introduces New KC-91 Protective Overcoat for Thermal Printheads Used in Digital Photo Printing

Contributing to improvements in print speed and print quality of dye-sublimation printers

February 6, 2012
Kyocera Corporation (President: Tetsuo Kuba) today announced the KC-91, a new protective overcoat that can be applied to Kyocera's thin-film thermal printheads commonly used in dye-sublimation printing applications such as the self-service digital photo printing machines increasingly found in public locations. Kyocera thermal printheads (up to a maximum A4-size) featuring the KC-91 protective overcoat will be sold starting Tuesday, February 7, 2012.

Picture: Kyocera thermal printhead with new KC-91 protective overcoat
Kyocera thermal printhead with new KC-91 protective overcoat

Name KC-91 Protective Overcoat for Thermal Printheads
Production facility Kagoshima Hayato Plant (Japan)
Availability Tuesday, February 7, 2012
Applicable products Can accommodate flat-type thermal printheads manufactured by Kyocera (up to a maximum A4-size)

New KC-91 Protective Overcoat

The newly-developed KC-91 overcoat provides an approximately 50% reduction in frictional resistance over Kyocera's conventional overcoat*1 which is made possible through Kyocera's proprietary assessment technology as well as improvements in the overcoat materials and film-formation conditions. The result is a reduction in the occurrence of 'wrinkles' in the dye-sub ink ribbon, even if the applied energy is increased by 20%, compared to conventional overcoats.

The absolute value of the frictional resistance between the printhead and ink ribbon is also reduced by a maximum of 30%*1. Furthermore, resistance to adhesion of residues (burnt deposits of ink or ink ribbon back-coated agents) has been increased by approximately six-fold, contributing to improvements in both print speed and print quality.

Development Background

With the increasing proliferation of high-quality digital cameras and camera-equipped smartphones in recent years, more people are taking and printing digital pictures themselves, and to service the demand to print those digital pictures, an increasing number of self-service photo printing equipment is being installed at department stores and home electronics stores. More dye-sublimation printers are employed in this application than other photo-printing technologies because they offer high print quality and compact size, allowing them to be located almost anywhere.

The dye-sublimation printer, a type of thermal printer, works via a process where the thermal printhead (hereinafter “head”) comes into contact with the ink ribbon and sublimates the ink with the heat of the head to print images on the paper. The color density is adjusted by varying the level of applied heat (applied energy), and increased frictional resistance is created between the head and ribbon as the applied energy increases. Differences in energy applied simultaneously in different locations on the head can result in differences in frictional resistance, causing the ink ribbon to move at different speeds and subsequently wrinkle, which in turn affects print speed and print quality.

Addressing the demand for equipment capable of printing higher-quality photos faster, Kyocera has developed the new KC-91 protective overcoat to significantly reduce the likelihood of ribbon wrinkles caused by differences in frictional resistances and to improve print speed and quality.

With the world's No. 1 market share*2 for thermal printheads, Kyocera strives to develop products that meet diverse customer needs and prove useful in everyday life.

Product Outline

1. Approximately 50% reduction in differences in frictional resistance resulting from differences in applied energy
The new KC-91 protective overcoat was developed by pursuing materials and thin-film formation conditions on the basis of Kyocera's proprietary technologies including film formation, photo-lithography and surface treatments.

The KC-91 provides an approximately 50% reduction in frictional resistance over Kyocera's conventional overcoat. This reduces the likelihood of wrinkles even if the applied energy is approximately 20% higher than that applied to conventional models, and contributes to improvements in the print speed and print quality.
image: Structural profile of a thermal printhead

2. Approximately 30% reduction in absolute value of frictional resistance
The absolute value of frictional resistance between the thermal printhead and ink ribbon is reduced by approximately 30%. The lower resistance allows the applied energy to be smoothly transferred to the ink ribbon, which contributes to improvements in print speed and print quality.

3. Approximately six-times greater resistance to adhesion of residues
A dye-sublimation printer generally may have residues (burnt deposits of ink or ink ribbon back-coated agents) adhered to the head.

The KC-91 overcoat offers anti-adhesive properties against residues that are approximately 6-times greater than Kyocera's conventional overcoat. This reduces the formation of obstacles between the heat-producing portion and the ink ribbon, which allows even higher print speeds and print quality.

4. Approximately four-times*1 greater durability against thermo-chemical wear, contributing to increased printhead service life
When a dye-sublimation printer operates, deterioration known as thermo-chemical wear occurs on the protective overcoat. Thermo-chemical wear is a specific phenomenon where the protective overcoat on the heater element wears in a mortar shape. This is caused by the heat of the thermal printhead and the chemical material applied on the back of the ink ribbon, which affects the service life of the head.

KC-91 increases durability against thermo-chemical wear by approximately four times, contributing to increased service life for thermal printheads.
image: Comparison of thermo-chemical wear

*1 Kyocera's conventional KC-14 protective overcoat and the new KC-91 protective overcoat were compared through continuous printing by commercial printers; based on research by Kyocera.
*2 As of January 31, 2012; based on research by Kyocera.