Abstract: A hollow built-in blind includes two glass plates, an annular spacer cooperating with the glass plates to define a receiving space, and a blind disposed in the receiving space and including a lower rail, a plurality of slats, and two pull cords connected to the lower rail. A transmission unit includes a transmission shaft, a winding mechanism disposed on the shaft, and a belt pulley fixed to one end of the shaft. A drive unit is located at one lateral end of the blind and includes a guide wheel spaced apart from the belt pulley, an internal control device operable to move upward and downward in the receiving space, and a timing belt looped over the belt pulley and the guide wheel and having two opposite ends connected to the internal control device to form a closed loop.

Abstract: A hollow built-in window blind is provided. The window blind includes an outer glass (13a), an inner glass (13b), a spacing strip (14), a curtain (12), and a fixing device for the curtain. The curtain (12) is installed in a closed space enclosed by the outer glass (13a), the inner glass (13b), and the spacing strip (14). Furthermore, the spacing strip (14) has a step part to be connected with the curtain (12), and the fixing device includes an upper beam (1) with a projection, left and right frames (10a, 10b) with a projection respectively. The upper beam (1), left and the right frames (10a, 10b) are connected to the spacing strip (14) by the projections set on the step part of the spacing strip (14).