Assembly comprising: two panels (10, 12) hinged to each other on an edge thereof and mounted to vertically fold book-like one on the other in front of an opening to be obscured; a device for moving the two panels (10, 12) comprising: - a rack mounted to the sides of the opening inside vertical uprights on both sides; - an electric motor located on the bottom panel; - a rotatable pinion driven by the motor and engageable on the rack to translate on the rack and thereby vertically lifting the bottom panel; the rack being mounted to be able to move linearly along its longitudinal axis, so that as a reaction to the momentum imparted to it by the pinion the rack can move as a function of the position of the panels and/or of the force imparted by the pinion, the assembly also comprising - a mechanism for locking and unlocking of the rack with respect to the sides of the opening, the locking and unlocking mechanism being destined to prevent or allow the movement of the rack, and - an element which is integral with a panel and destined to trigger the mechanism for locking and unlocking, the assembly being characterised in that the rack is vertical and able to move vertically along its longitudinal axis, and in that said integral element comprises or consists of a carriage on which the pinion is rotatably mounted. two panels (10, 12) hinged to each other on an edge thereof and mounted to vertically fold book-like one on the other in front of an opening to be obscured; a device for moving the two panels (10, 12) comprising: - a rack mounted to the sides of the opening inside vertical uprights on both sides; - an electric motor located on the bottom panel; - a rotatable pinion driven by the motor and engageable on the rack to translate on the rack and thereby vertically lifting the bottom panel; - a rack mounted to the sides of the opening inside vertical uprights on both sides; - an electric motor located on the bottom panel; - a rotatable pinion driven by the motor and engageable on the rack to translate on the rack and thereby vertically lifting the bottom panel; the rack being mounted to be able to move linearly along its longitudinal axis, so that as a reaction to the momentum imparted to it by the pinion the rack can move as a function of the position of the panels and/or of the force imparted by the pinion, the assembly also comprising - a mechanism for locking and unlocking of the rack with respect to the sides of the opening, the locking and unlocking mechanism being destined to prevent or allow the movement of the rack, and - an element which is integral with a panel and destined to trigger the mechanism for locking and unlocking, - a mechanism for locking and unlocking of the rack with respect to the sides of the opening, the locking and unlocking mechanism being destined to prevent or allow the movement of the rack, and - an element which is integral with a panel and destined to trigger the mechanism for locking and unlocking, the assembly being characterised in that the rack is vertical and able to move vertically along its longitudinal axis, and in that said integral element comprises or consists of a carriage on which the pinion is rotatably mounted.