Optical Bonding /Optical Filters|KOTO Electric Co., Ltd.


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Optical Bonding /Optical Filters

Optical Bonding

KOTO Optical Bonding Using UV-LOCA

We provide high quality optical bonding services using UV-curable Liquid Optically Clear Adhesive (LOCA) (Optical Clear Resin (UV-OCR)). The direct bonding which directly bond the cover material to the LCD to eliminate the air gap has become mainstream in optical bonding in order to enhance readability and durability of the display. With superior optical properties, UV-LOCA (UV-OCR) is suitable for the displays with uneven surfaces such as bezels because it is liquid.

The cover glass or touch panel is bonded on Liquid Crystal Module (LCM) using UV-LOCA. The gap between the bezel and liquid crystal surface of the LCM can be sealed with high viscosity UV-LOCA. Using our original dispensing system and lamination mechanism, we can prevent the inclusion of bubbles that largely affect the bonding yield without vacuum processing. As a result, we don't waste expensive LCM, etc. supplied by customers.

Effects of Optical Bonding


Optically Bonded Applications


Optically Bonded Applications


Optical Bonding Specifications

Items Achievements
LCM size 4. 3"、4. 8"、5. 7"、7. 0"、8. 4"、10. 4"、12. 1"、15. 0"
LOCA thickness (Between bezel and cover glass) Std. 0.5mm, Max. 1.0mm
Cover glass thickness 1mmt, 2mmt, 3mmt (Other size available)
Cover glass surface coating (Outsource) Anti-reflective (AR) coating, Anti-smudge coating, etc.

Final Yield of Optical Bonding 99.95%

Failed bonding wastes expensive LCM or touch panel supplied by customers. However, our original bonding technique and strict quality control enable high yield and minimization of loss of material.

Curing under Black Masking and Other Shaded Areas

The black printed area of the front cover bonded with a touch panel blocks light, which means the UV light of the UV cure equip. cannot be transmitted through the black printed area to cure the area underneath.
However, we can provide the bonding with LOCA that is also curable in shaded area. It is effective in preventing the quality degradation due to insufficient curing of the adhesive under the black printed area.

Optical Filters

NVIS Optical Filter

We have more than 30 years of history as a manufacturer of optical filters for Night Vision Imaging Systems (NVIS). We started with the investigation of the NVIS market in the US in 1982 and since then, we have provided high functional NVIS optical filters by combining our self-developed heat absorbing glass and organic films. They are used in Japan as well, such as for the Japan Self-Defense Forces aircrafts for night flight and disaster-prevention helicopters.

Examples of Uses in Japan


Mechanism of NVIS

Pilots wear night vision goggles (NVG) during night operations as relative luminosity for unaided eyes and goggles are different. Typically, goggles convert the infrared (IR) wavelength into visible wavelength (Things look green through NVG). Since goggles react to even a small amount of IR energy, then if they are exposed to a large amount of energy, it affects the performance of the goggles. In fact, if the light source contains a large amount of IR energy, it will damage and break the goggles. Therefore, indicating lamps need to be filtered to only pass spectral energy in visible light region and cut the energy in IR region. We use heat-absorbing glass in our NVIS optical filters.

NVIS Optical Filter Applications



Coat type Purpose
AR coat Surface anti-reflection coating
ITO coat Transparent conductive film
Electromagnetic wave shielding film
Heat ray shielding
Anti-reflection film
Silica coat Anti-reflection and slight light diffusion

Koto NVIS Optical Filter Evaluation Method