when there is no use of a friction ring of the type used in the balancer of this invention in other words a characteristic curve of the compression coil spring j is a characteristic curve of the properties of the moment of revolution of the lid d and k is a characteristic curve of the properties of the balancer s of this invention as is easily understood from curve h in fig4 it is impossible to make the characteristic curve of the compression ring agree with the moment of revolution j of the lid d by only using the compression coil spring however the spring constant may be designed this invention is made to obtain properties which agree with the moment of revolution j of the lid d by the overall properties of the spring properties and the friction ring further with the spring balancer s according to this invention a characteristic curve can be obtained that has properties which agree with the moment of revolution j of the lid d during a portion of the lid movement and also slightly exceed the moment of the revolution of the lid d near the terminal point of closing of the lid d as shown with curve k in fig4 when the spring balancer s is designed to have a characteristic curve that agrees with the moment of the revolution j of the lid d said lid d can be operated not only with a small force but also can be stopped at any position through the whole process of the opening and closing of the lid d further in case that.