Denys Fisher sale in Schofields department store in Leeds in 1965. A year later, Fisher licensed Spirograph to Kenner Products in the United States. In 1967 Spirograph was chosen as the UK Toy of the Year. Denys Fisher Toys, which also produced other toys and board games, was sold to Palitoy in 1970 and it was subsequently bought by Hasbro. Through the 1980s & 1990s Fisher continued to work with Hasbro in developing new toys and refining Spirograph. Denys Fisher Toys produced the following toys and games: Denys Fisher Denys Fisher (11 May 1918 – 17 September 2002) was an English engineer
Centered trochoid example following F. Morley) use "trochoid" to mean a roulette of a circle rolling along another circle, though this is inconsistent with the more common terminology. The term "Centered trochoid" as adopted by combines "epitrochoid" and "hypotrochoid" into a single concept to streamline mathematical exposition and remains consistent with the existing standard. The term "Trochoidal curve" describes epitrochoids, hypotrochoids, and trochoids (see ). A trochoidal curve can be defined as the path traced by the sum of two vectors, each moving at a uniform speed in a circle or in a straight line (but not both moving in a line).