Patent ID: 8105169

Claim:
A portable electronic device, comprising: a horizontally long casing, both ends of which are capable of being gripped by a user's both hands, respectively; a display unit fit into a front face of the casing; and an optical disk drive unit which is installed on a rear face of the casing and on which a detachable disk is loaded, the disk drive unit having a lid opening backwards on at least a part of a planar region formed at substantially a center of the rear face of the casing; operation means installed on each side of the front face of the casing, the operation means being configured to be operated by a thumb of the user gripping the casing; and a button installed on a side face of the casing and upper side of the operation means, the button being configured to be operated by an index finger and/or a middle finger of the user, wherein first curved shapes are formed symmetrically on both side faces of the casing, the first curved faces being configured to guide the tips of the index and/or middle finger naturally onto the button by placing the stretched finger for operating the button along the first curved shape, when the user grips the casing with his/her thumb on the operation means, so that tips of the rest of the fingers are away from the lid of the disk drive unit on the rear face, and wherein a horizontally longitudinal cross section of the casing substantially perpendicular to the rear face comprises a second curved shape having gentle curves slanted such that a width of the cross section of the area, on which the operating means are placed, gradually becomes narrower from a nearer side to the center to the left and right sides of the casing at both the front face and the rear face.