978,316. Electrically operated louvre screens. E. C. STREETER. Jan. 10, 1962, No. 907/62. Headings E1J and E1R. In a louvre-type screen the laths are of electrically conducting material such as plastic containing metallic powder; stainless steel; aluminium foil or Bronze foil and reflect and/or absorb electromagnetic light and heat radiation and are rotatably controlled about their longitudinal axes by an electrostatic field, the laths being individually subjected to a restoring (gravity) torque to maintain them in a common angle of repose. As shown in Fig. 2 laths 17 are enclosed in an air-tight space 16 formed by two glass panes 12, 13, embedded in which are electrode wires 39, 40 opposite to the vane support-wires 18 of the laths 17. All these wires 39, 40 and wires 39<SP>1</SP>, 40<SP>1</SP> (which diminish distortion of the electric field between the laths and the electrode wires 39, 40) are connected together at ground potential by conductive coating 43, Fig. 4 e.g. carbon particles in a volatile carrier liquid, on the opposite vertical edges 41, 41<SP>1</SP> of the plates 12, 13 where the ends of the electrodes 39, 40 appear; which in turn is connected to the grounded metal frame 14 by a flexible conductor 44, and the laths are connected to a source of different potential by an electric cable 37 connected by terminal 38 sealed in the sealing member 15 attached to the side 29 of the housing enclosing the angle members 24, 24<SP>1</SP>, Fig. 2 between which the ends of the support wires 18 are clamped in slight tension. The cylindrical bearings 51, Fig. 5, secured to the lath 17, is biased by a flange 52 into a vertical position. The vanes 17 may be S-shaped and have a spiral bearing-continuous or interrupted. The electrodes 39, 40, may be replaced by a substantially transparent, electrically-conductive coating on the incident plate 12, or 13 for the radiation. Silica gel may be contained within the space formed by the peripheral channel shaped members such as 31 Fig. 2, 29 Fig. 4 and the angle members 24, 24<SP>1</SP> and this space is in communication with the space 16 through the narrow slits created by the support wires 18.