It has been 17 years that we developed the watch lubricant “AO-oil” which resolves the problems of existing watch lubricant, i.e. “gelation”, “metal corrosion”, and “temperature dependence of watch lubricant's viscosity”, caused by time decay. AO-oil has been developed especially with focusing on base oil and viscosity modifier, which extends the life of timepieces and enhances reliability. Furthermore, by enforcing higher lubrication and stability I found that the lifetime can be extended much longer. As to this development, an optimal additive has to be selected by focusing on antiwear/extreme-pressure agent and antioxidation agent. Hence, now I report on this new watch lubricant “AO-oil”.

  By applying anti-reflection coating on both sides (front and back) of the sapphire windshield of the wristwatch, we prevent degradation of visibility, color tone and contrast of the dial and hand due to reflection. However, in achieving this coating, there were some problems, especially on the front side coating of the windshield. In this thesis, we will introduce what we have done to solve this problem.