A center section of the upper edge of the rotation member which is rotatable with friction with respect to a first housing in an arrow direction A-A by using, as a rotation shaft, a first shaft which forms a rotation shaft in parallel with a rear edge of the first housing, and a center section of a lower edge of a second housing which is openable and closable with respect to the first housing in the arrow direction A-A and which is rotatable in an arrow direction B-B in an opened state, are connected to each other rotatably in the arrow direction B-B a the second shaft which is perpendicular to the first shaft, and which, when the second housing is in a vertically opened state, is inclined at 45° in a direction in which the second shaft is tilted forward.