Escapement and watches. These are described individually below. Although the invention of the crystal oscillator and the quartz clock in the 1920s shifted technological research in timekeeping to electronic methods, major advances in the design of mechanical escapement are still happening. Coaxial escapement, invented by English watchmaker George Daniels around 1974 and patented in 1980 has rather dramatically increased the accuracy and durability of mechanical watches. Yoshikazu Akahane with teams of engineers at Seiko Epson developed the spring drive movement around 1977, and obtained not less than 230 patents between 1982 and the present. The reliability of an escapement depends on
Mechanical watch the watch from its time source, the balance spring, watches could be built without a fusee and still be accurate. In the 18th century the original verge escapement, which required a fusee, was gradually replaced in better French watches with the cylinder escapement, and in British watches with the duplex escapement. Then in the 19th century both were superseded by the lever escapement which has been used almost exclusively ever since. A cheaper version of the lever, the pin lever escapement, patented in 1867 by Georges Frederic Roskopf was used in inexpensive watches until the 1970s. As manual-wound mechanical watches