Window blind assembly having a detachable control system

A window blind assembly comprising:

• a headrail;
• a blind unit suspended from said headrail;
• a control system for controlling status of said blind unit, said control system comprising:
• a transmission mechanism mounted in said headrail and including a force receiving member having a receiving portion extended outside, and actuating means rotatable by said force receiving member to change a light shading status of said blind unit;
• and
• a driving device having a handle disposed at one end thereof for operation by the user, and a force output member disposed at an opposite end thereof and detachably connected to the receiving portion of said force receiving member of said transmission mechanism;
• wherein said receiving portion of said force receiving member is a rod member having a coupling groove extended around a periphery close to a bottom end thereof;
• said force output member of said driving device has a non-circular receptacle connectable to the bottom end of said receiving portion of said force receiving member, said receptacle having at least one spring arm, said at least one spring arm each having a protruding engagement portion projecting in direction toward a central axis of said receptacle for engaging the coupling groove of said receiving portion of said force receiving member upon connection of said receptacle to said receiving portion of said force receiving member.