Patent ID: 7126049

Claim:
A method of improving repetitive striking performance of a piano comprising an action mechanism in which a substantially L-shaped jack pushes up a part of a striking member in response to key depression in order to cause the striking member to strike a string, the jack being composed of elongated portions comprising: a big jack portion for pushing up the striking member, and a small jack portion integrated almost perpendicular to the big jack portion, wherein the small jack portion is lightened by at least one of the following steps: forming the lightened small jack portion from a material with a higher strength versus weight ratio than a material from which the big jack portion is manufactured, incorporating voids into the small jack portion, providing the small jack portion with a thickness less than that of the big jack portion, manufacturing the small jack portion from a material less dense than a material from which the big jack portion is manufactured, and curving an upper side of the small jack portion into a concave shape.