More than seventy years ago, F. A. Votta, Jr., developed both the constant force springs and constant torque springs, characteristics of which are quite different from conventional ones. Those springs have been utilized still widely in fields of engineering over the world as useful mechanical elements being able to keep forces or torques constant, regardless of its extension. Thanks to its peculiarity springs have, retention of some objects at arbitrary point can be achieved. The authors can not deny that there are no experimental proof and that theoretical explanations are insufficient in his paper. In fact, there exist always certain amount of differences between our experiments and his analysis. Then authors tried to derive an appropriate equation representing the spring force, using their own ideas. However, the result authors obtained turned out, contrary to the author’s expectation, to be just the same to Votta’s, leading to verifying the validity of Votta’s expression. In addition to the above, the authors also discussed theoretically and experimentally the difference of spring forces between normal winding and reverse winding of springs around a drum. It is made clear that the spring force produced by reverse winding becomes twice that by normal one. These results are very useful to know both the spring force and torque produced in constant torque spring system, which may be introduced in a paper concerned.

  F. A. Votta, Jr., a design engineer, developed both the constant force springs and the constant torque springs. He made public the materials, which he was concerned with, on a bulletin of ASME, American Society of Mechanical Engineering on May 1952. We appreciate his simple analytical methods and its useful results. Those springs have been utilized still widely in fields of engineering over the world. By the author’s works so far, however, it became obvious that analytical explanations are in part insufficient and no experimental results are shown in his both papers related to the constant force and torque springs. Of the two papers above, the authors confirmed finally the validity of the expression he obtained in his paper, by using their own ideas and experiments. The authors also tried to apply the equations obtained in the constant spring force to those in constant torque springs. As the results obtained, the authors may conclude that their new analytical methods introduced in this paper are useful to know the torques to be produced in the constant torque springs. Furthermore, the authors propose ideas to reduce changes of torques, which should be primarily constant regardless of extension of springs.

  At the 60th anniversary of Grand Seiko's birth, we announced a commemorative model equipped with a new Spring Drive caliber. The Cal. 9RA5 600m diver developed this time is a professional diver with 600m saturated diving specifications compliant with ISO6425 (2018 version), and we will explain the contents of the strength improvement in compliance with the standard.

  CASIO Computer Corporation have developed products “G-SQUAD:GBD-H1000”, a brand of shock-proof watch “G-SHOCK”. This paper explains the technical summary of the development of GBD-H1000. By increasing the efficiency of the solar cell and reducing the current of Silicon On Thin Buried Oxide (SOTB), etc., the area of the solar cell and the battery have been reduced, resulting in a size reduction (about 20% reduction in volume) and improved wearability. In addition, visibility of high-definition display was improved (transmittance improved by about 20%) by laminating windshield and solar cells and adopting Moth-eye Film. In addition, while downsizing, it has become a product with improved usability due to its enhanced functions (pulse measurement function and incoming call notification by vibration).