1. Field of the Invention
This invention lies in the field of those devices intended to provide window insulation against heat transmission in the glass areas, whether it be radiant transmission, convective transmission or conductive transmission.
2. Description of the Prior Art
Window insulating devices have been provided heretofore utilizing a plurality of films to be mounted at the inner side of a window and some of these have been roller mounted so that they could be pulled down at the inner side of a window to provide multiple air spaces to reduce heat flow in the window area and thus, depending upon the effectiveness of the unit, to cut down on the heat loss. However, many of these devices were not effectively sealed at the side edges and consequently air circulation occurred at these locations and adversely affected the efficiency of the insulating quality of such devices.
Some such devices did have sealing members at the side edges but these seals were fixed in position along the vertical edges of the window to engage the vertically movable films at all times and thus were subject to abrasion, especially where such seals were made from plastic materials. The seals were flexible and supposedly having a high elastic memory but with use and age, the seals lost their recuperative elastic properties and became ineffective so that the installation leaked at these side edges and permitted air circulation into the dead air space between the films and thus reduced the insulating effectiveness of the entire installation.
Prior patent art disclosing various window insulating arrangements comprise U.S. Pat. Nos. 2,306,086, Smith; 2,140,049, Granel; 2,328,257, Butts; 2,865,446, Cole; 2,247,634, Hornston; 2,361,762, Glenn et al.; 4,039,019, Hopper and 4,194,550, Hopper.
The present device does not require film separators as in the arrangement of Hopper patent 4,194,550 and therefore reduces the diameter of the curtain in the rolled-up condition.
This arrangement also will cause the film to reengage with the tracks at the sides if by some chance the film may accidentally become disengaged from one or both tracks. By actuating the curtain to the rolled-up condition and then pulling it down, the film engagement operation starts over with the film properly engaging the tracks.