Block and tackle window blind

A window blind, comprising:

• a headrail,
• a covering structure provided below the headrail, wherein the covering structure comprises a plurality of slats, which are adapted to be turned around a longitudinal direction thereof, and are adapted to be expanded downward or gathered upward relative to the headrail;
• a modulation assembly comprising at least two adjustment members and at least two adjustment cord assemblies which are correspondingly provided, wherein the at least two adjustment members are provided in the headrail;
• each of the at least one two adjustment cord assemblies is connected to the corresponding one of the at least two adjustment members with an end thereof, and has a segment suspended from the headrail to be passed through by the slats;
• the at least two adjustment members are adapted to be driven to rotate, whereby to drive the corresponding at least two adjustment cord assemblies to operate, turning the slats;
• a driving module, which is installed in the headrail and provided between any two of the at least two adjustment members, wherein the driving module comprises a power unit;
• a block and tackle system provided in the headrail, wherein the block and tackle system comprises a movable member which is concurrently operable along with the driving module, so that the movable member is adapted to be driven by the power unit of the driving module to optionally reciprocate in a longitudinal direction of the headrail;
• and
• a lifting cord assembly, which is connected to the block and tackle system with an end thereof, and extends out of the headrail, wherein another end thereof is fixedly connected to a bottom side of the covering structure;
• when the movable member reciprocates along the longitudinal direction of the headrail, the lifting cord assembly is driven to expand or gather the slats of the covering structure.