Flexion-extension joint and screen bracket having the same

A flexion-extension joint for a screen bracket, comprising:

• a connection head unit including
• a connection seat that has an accommodation hole extending along an axis,
• a connection block that is disposed in said accommodation hole along the axis, and that has a circular portion and two extension portions respectively connected to two opposite sides of said circular portion in a left-right direction, the axis extending in the left-right direction, each of said extension portions having a non-circular cross-section,
• a one-way rotation member that is mounted between said connection seat and said connection block, and that is sleeved on said circular portion of said connection block, and
• two damper seats that are respectively secured to said extension portions and that are adjacent to said one-way rotation member, each of said damper seats having a first contact surface that surrounds and extends along the axis;
• and
• a movement unit, said connection head unit being mounted to said movement unit, said movement unit being rotatable relative to said connection seat in a top-bottom direction perpendicular to the left-right direction, and including a movement seat that is rotatable relative to said connection seat, two end covers that are spaced apart from each other in the left-right direction, that are disposed on said movement seat and that are respectively in frictional contact with said damper seats, and a rotation rod that extends through said end covers, said movement seat and said connection head unit along the axis, each of said end covers and said respective one of said damper seats having static friction generated therebetween;
• wherein each of said end covers has a first friction surface that extends along the axis, and that is in contact with said first contact surface of said respective one of said damper seats, so that said first friction surface of each of said end covers and said first contact surface of said respective one of said damper seats have kinetic friction generated therebetween when said movement unit rotates upwards;
• and
• wherein resistance generated when said movement unit rotates upwards relative to said connection seat is smaller than resistance generated when said movement unit rotates downwards relative to said connection seat.