Portable computer with a rotary positioning structure

A portable computer with a rotary positioning structure, comprising:

• a first body;
• a second body;
• a shaft, including a first part disposed on the first body and a second part disposed on the second body, wherein the second part is pivoted to the first part, and the second body movable with the second part relative to the first part to make a first rotary motion in a first rotary path;
• a seat disposed to the first body;
• a button coupled to the seat and movable between a first position and a second position;
• a first flexible member connected between the button and the seat and adapted to push the button from the second position to the first position when the second part is rotated to a first angle;
• and
• a pivot member fixedly provided at the seat, and a rotating member pivotally mounted on the pivot member, the rotating member including a first cam and a second cam, the first cam being pushed by the second part of the shaft to thereby rotate the second cam to move the button and to further force the at least one retaining portion of the button away from the at least one retaining portion of the seat for enabling the first flexible member to return the button to the first position when the second part of the shaft is rotated to the first angle;
• wherein the button has at least one part thereof set in the first rotary path to prohibit rotation of the second body in the first rotary path when the button is in the first position, the button being beyond the first rotary path for allowing rotation of the second body in the first rotary path when the button is in the second position.