Storage case and hinge structure

A storage case comprising:

• a case body;
• and
• a cover body,
• the cover body comprising:
• a front cover disposed at a front side of the storage case;
• a top plate;
• and
• a hinge structure, an upper side of the front cover being rotatably connected to the top plate via the hinge structure, wherein
• an outwardly protruding locking convex part is formed on the upper side of the front cover,
• in a first opened state in which the front cover is turned upward about the upper side of the front cover as an axis, the locking convex part comes into contact with an engagement part formed on the top plate, and
• when the front cover is further turned upward from the first opened state and becomes in a second opened state in which the engagement part passes over the locking convex part, the locking convex part engages with the engagement part so that the front cover is locked in the second opened state,
• the locking convex part is recessed from a rear side of the front cover to be in a shell-shaped hollow body form,
• the locking convex part has a slope surface positioned at a side of the engagement part when the front cover is in a closed state, and a locking surface positioned at a side of the engagement part when the front cover is in the second opened state,
• the slope surface gently slopes toward a top portion of the locking convex part such that contact stress between the locking convex part and the engagement part gradually increases when the front cover is turned upward from the first opened state to the second opened state,
• the locking surface abruptly decreases the contact stress when the front cover is shifted from the first opened state to the second opened state, and, when a self-weight of the front cover acts on the front cover to turn the front cover toward the closed state in the second opened state, the locking surface comes into contact with the engagement part so that the front cover is held in the second opened state,
• the case body is formed in a substantially rectangular parallelepiped shape having an opening at an upper surface and an opening at a front surface,
• the cover body has the top plate and the front cover which are rotatably connected to each other via the hinge structure,
• the cover body is attached to the case body such that the top plate covers the upper surface opening of the case body and the front cover covers the front surface opening of the case body,
• in the storage case, by detaching the cover body from the case body, the upper surface and the front surface are opened and items to be stored can be taken in and out, and
• when the cover body is kept attached on the case body, by turning the front cover upward, an inside of the storage case can be opened and items can be taken in and out.