Display support device

A display support device, comprising:

• a hollow hanging arm having a pivot end portion and a movable end portion opposite to said pivot end portion;
• a pressure cylinder movably disposed in said hanging arm, and including
• a cylinder body having a first end pivotally connected to said pivot end portion, and a second end opposite to said first end,
• a fixed rod axially extending through said second end of said cylinder body and having an open end opposite to said first end of said cylinder body, and
• a control pin axially and movably extending through said open end of said fixed rod for controlling pressure change inside said cylinder body and having an end surface;
• a control unit operable to control movement of said control pin between a locking position, in which said end surface of said control pin is flush with said open end of said fixed rod and said cylinder body is immovable relative to said fixed rod, and an unlocking position, in which said end surface of said control pin is spaced apart from said open end of said fixed rod and said cylinder body is movable relative to said fixed rod;
• a carrier unit pivotally connected to said movable end portion;
• and
• a positioning unit connected to said pivot end portion.