Bottom up roller blinds are designed to allow in light while increasing the privacy of the room.
The design of these blinds is 'upside down' to put it in it's simplist form. With the main structure of the blind located at the bottom of the frame and the blind being pulled upward to perform the required function.
The largest advantage of this form of blind is the varying levels of privacy it offers whilst still letting in sunlight. Lifting upward allows you to set the height of the blind like a regualr roller blind but also to stop outsiders from looking into the room by providing a adjustable barrier.