Document pressing device for a copier

A document pressing device for a copier, comprising:

• a cover disposed above a document table of said copier, and for pressing a document laid on said document table;
• at least one hinge mechanism provided at a base end of said cover, and openably supporting said cover on a housing of said copier, said hinge mechanism comprising:
• a holder member pivotally engaged at a base end with a base member mounted on said housing;
• a bracket pivotally connected to the other end of said holder member;
• a first hollow cylindrical sleeve member having a bottom, and pivotally engaged at said bottom with a portion of said base member closer to said document table than said base end of said holder member;
• a second hollow cylindrical sleeve member having a bottom, and telescopically coupled over said first sleeve member, and pivotally engaged with or connected to a free end of said bracket such that said second sleeve member is positioned closer to said document table than a point about which said bracket is pivotable;
• a plurality of lugs formed at an open end of an outer periphery of one of said first and second sleeve members, and slidably contacting an inner periphery of the other of said first and second sleeve members;
• a notch formed in one of said first and second sleeve members from said open end toward said bottom over a predetermined length;
• first biasing means loaded between said bottoms of said first and second sleeve members, and for constantly biasing said first and second sleeves away from each other;
• second biasing means loaded between said bracket and said holder member, and for constantly biasing said bracket toward said holder member such that when said cover is moved toward or away from said document table, said bracket does not pivotally move about said point relative to said holder member;
• and
• engaging and disengaging means constituted by a part of said bracket and a part of said holder member, and for causing said bracket to engage with said holder member such that said bracket is movable together with said holder member, and for causing, when a relatively thick document is laid on said document table, said bracket to disengage from said holder member when said bracket is pivotally moved about said point in interlocked relation to a closing movement of said cover and then released from said holder to cause said cover to be lifted up in accordance with a thickness of said document.