Patent ID: 7902445

Claim:
A housing structure of an electronic keyboard musical instrument having a housing comprised of lower and upper cases which are separate from each other, the upper case being adapted to be pivoted relative to the lower case between open and closed states and the housing being completed by fixing the upper case to the lower case with a keyboard open to above when the upper case is in the closed state and with a backward region of the keyboard open to above when the upper case is in the open state, comprising: at least one protrusion fixedly formed in one of rear end portions of the upper and lower cases; and at least one engagement hole formed in the other of the rear end portions of the upper and lower cases, wherein the upper and lower cases are adapted to be pivoted relative to each other in an opening and closing direction around an engagement portion between the engagement hole and the protrusion inserted into and engaged with the engagement hole, wherein the protrusion and the engagement hole are adapted to be relatively inserted into and removed from each other in a radial direction of the pivotal movement to thereby allow the upper case to be attached to or detached from the lower case, only when the upper case is at a predetermined pivotal angle in a pivotal movement in the opening and closing direction, wherein the protrusion includes a narrow-width portion and a wide-width portion, the wide-width portion being arranged on a side close to a tip end of the protrusion with respect to the narrow-width portion and having a length longer than that of the narrow-width portion as viewed in a key arrangement direction, the engagement hole includes a wide-width counterpart having a width permitting the wide-width portion of the protrusion to be inserted thereinto and a narrow-width counterpart formed adjacent to the wide-width counter part and having a width not permitting the wide-width portion to be inserted thereinto but permitting the narrow-width portion to be inserted thereinto, the wide-width portion is adapted to be insertable into and removable from the wide-width counterpart when the upper case having a posture corresponding to the predetermined pivotal angle and the lower case are relatively moved in a direction in which the protrusion is projectedly formed, and the protrusion and the engagement hole are prevented from being relatively inserted into and removed from each other in the direction in which the protrusion is projectedly formed due to engagement between the wide-width portion and the narrow-width counterpart when the upper case is in the open state.