1. Field of the Invention
The present invention relates to a panel opening and closing structure of an electric operation apparatus in which an apparatus main body is configured to be covered from above by control panels mounted with operating elements.
2. Description of the Related Art
Conventionally, there have been known an electric operation apparatus (e.g., mixer apparatus) having a main body thereof covered from above by a control panel mounted with a number of operating elements. The control panel is generally formed by a single panel that covers the entirety of an upper open surface of the apparatus main body, and is openable by being pivoted upward and rearward about a front end of the electric operation apparatus. At fabrication or maintenance of the electric operation apparatus, an open state of the control panel is maintained by, e.g., support rods, thereby permitting access to the interior of the main body for internal work.
Such workability has also been taken into account in the design of electronic keyboard instrument as disclosed in Japanese Laid-open Patent Publication No. 2005-99444. The keyboard instrument disclosed therein has a keyboard unit configured to be opened and closed about a rear end of an instrument main body such that a front end portion of the keyboard unit can be opened upward for easy maintenance of, e.g., a main circuit inside the instrument.
However, since the interior of an electric operation apparatus having a control panel formed by a single panel can be opened only toward the front or rear side, it is difficult to access from another side to the interior of the apparatus for internal work (e.g., assembly and maintenance).
In particular, in a large-sized electric operation apparatus having a control panel of single panel structure, the control panel per se is large in size and heavy in weight, thus making it laborious to open and close the control panel.
In addition, the apparatus becomes unstable in posture, if the control panel is opened by being pivoted about a pivot shaft at the front or rear end of the apparatus main body such that the position of the center of gravity of the panel is near or beyond the front or rear end of the main body in the front-rear direction. Accordingly, the control panel cannot be pivoted to be opened at a large angle and hence the open area of the apparatus becomes small, resulting in low workability. In addition, since a large load is concentrated to some part of the apparatus main body, the rigidity of the main body must be increased, resulting in the increase of apparatus weight and reduction of workability.