Hinge for a portable computer

A hinge to be attached to a portable computer, said portable computer including a lower housing and an upper housing which is pivoted to said lower housing by said hinge, said hinge comprising:

• a first hinge leaf unit including a first elongated positioning plate portion adapted to be mounted securely on said upper housing, and a pair of pivot plate portions secured respectively to two ends of said first elongated positioning plate portion at upper portions thereof, each of said pivot plate portions having a pivot hole formed in a lower portion thereof;
• a second hinge leaf unit including a second elongated positioning plate portion which is adapted to be mounted securely on said lower housing, and a pivot pin which is connected securely to an end surface of said second elongated positioning plate portion and which extends through said pivot holes of said pivot plate portions of said first hinge leaf unit so as to allow said first hinge leaf unit to be mounted rotatably on said second hinge leaf unit;
• a sleeve being sleeved tightly on said pivot pin of said second hinge leaf unit between said pivot plate portions of said first hinge leaf unit so as to provide friction between an inner surface of said sleeve and an outer surface of said pivot pin, thus locating said upper housing at a selected position relative to said lower housing;
• and
• a resisting unit including a first torsion spring which is sleeved tightly on a portion of an outer surface of said sleeve and which has an end portion that is retained on one of said pivot plate portions so as to fasten said sleeve to said first hinge leaf unit in such a manner that said sleeve can rotate with said first hinge leaf unit, and a second torsion spring which is sleeved tightly on another portion of said outer surface of said sleeve and which has an end portion that is retained on the other one of said pivot plate portions, said second torsion spring having a retaining force capable of arresting upward movement of said upper housing relative to said lower housing, said second torsion spring being tightened on said sleeve when said first hinge leaf unit is turned upward so as to allow said sleeve to rotate synchronously with said first hinge leaf unit, synchronous rotation of said sleeve and said first hinge leaf unit loosening said first torsion spring, said first torsion spring having a returning force capable of arresting downward movement of said upper housing relative to said lower housing, said first torsion spring being tightened on said sleeve when said first hinge leaf unit is turned downward so as to allow said sleeve to rotate synchronously with said first hinge leaf unit, synchronous rotation of said sleeve and said first hinge leaf unit loosening said second torsion spring, said first and second torsion springs cooperatively facilitating retaining of said upper housing in said selected position relative to said lower housing.