Dual roll blind system

A dual roll blind system which is able to adjust degree of a light shading, a dual roll blind system, comprising:

• a winding roll which includes a roll casing rotatably supported between both side plates of a ceiling bracket;
• a driving winding roll, which includes a moving member disposed between both the side plates of the ceiling bracket, is disposed in parallel with the winding roll, and is thread-engaged with a screw shaft rotating by means of a blind winding device at one side, a straight moving member which is provided for left and right straight movements by restricting the rotation of the moving member, and a roll casing engaged with the moving member and the straight moving member;
• a first blind material whose upper end is fixed at the winding roll and in which a light transmission part and a light non-transmission part having constant widths are alternately formed in a width wise direction;
• a second blind material whose upper end is fixed at the driving winding roll and which has a light transmission part and a light non-transmission part corresponding to the first blind material and is movable left and right;
• and
• a counterweight bar, at which a lower end of the first blind material is fixed, and into which a lower end of the second blind material is slidably inserted in a parallel direction to the lower end of the first blind material,
• wherein said straight moving member of the driving winding roll comprises a spline shaft which is positioned opposite to the screw shaft and is coaxial with the screw shaft, and a running member which is slidably engaged at the spline shaft and moves straight along the screw shaft and the spline shaft as the roll casing is engaged at the running member.