1. Field of the Invention
The present invention relates to a keyboard lid opening and closing apparatus that are used in keyboard instruments such as pianos and organs, and a keyboard instrument provided with the keyboard lid opening and closing apparatus.
2. Description of the Related Art
A keyboard lid opening and closing apparatus in a keyboard instrument such as an electric piano is known in which a keyboard lid that openably and closably covers a keyboard section provided in an instrument case is constituted by a plurality of plates sequentially connected to one another to be foldable, as shown in, for example, Japanese Patent Application Laid-Open (Kokai) Publication No. 2007-133249.
This type of keyboard lid opening and closing apparatus is structured such that, when the keyboard section of the keyboard instrument is to be covered by the keyboard lid, the plurality of plates are sequentially unfolded in a front-rear direction and thereby sequentially arranged above the keyboard section so as to cover this keyboard section. When the keyboard lid is to be opened to expose the keyboard section, the plates are sequentially folded and accommodated in the instrument case so as to expose the keyboard section.
However, this keyboard lid opening and closing apparatus for a keyboard instrument has problems in that the plurality of plates are not smoothly folded unless they are all formed in the same size, and do not stand upright stably when they are folded by being held upright, due to which their upper portions easily tilt in the front-rear direction. Accordingly, the folding of the plates of this keyboard lid opening and closing apparatus is bothersome.