An expandable window covering

This invention relates to an expandable window covering.

US-A-4885190 describes a process and machine for making expandable honeycomb material, the contents of which patent are hereby incorporated by reference. The underlying concept is to feed a strip of material from a continuous supply, apply lines of adhesive to the material, cut the strips into desired widths, fold the strips into flat tubular form, and then wind the tubular strips on an annular rack. The adhesive lines are located such that those on top of each tube are located below the bottom of the superposed tube. The resultant assembly of tubes after further processing is heated to activate or soften the glue and compressed to cause the stacked tubes to permanently adhere to one another. With the provision of suitable creases and pleats, an expandable honeycomb structure results of a type that has proved very popular with the public as a window covering. US-A-4450027 and 4849039 describe other ways of making a similar structure. One aspect of the present invention is to provide an alternative method and apparatus that offers certain advantages.

The honeycomb structure described above offers a window covering with insulating properties if the material used will block or attenuate air flow. If the material is transparent, it will allow light passage; if opaque, it will block light. But the resultant structure cannot control the passage of light in the same sense that a conventional venetian blind allows a user by tilting the slats to control the passage of light through a window into a room.

US-A-3384519 describes a honeycomb structure that is capable of controlling the light passing through. It is made up of transparent cloth sheets interconnected by cloth strips functioning as slats. By making the cloth strips opaque, light will be blocked in one position of the cloth sheets when the strips lie flat and abut or overlap, and light can pass in another position of the cloth sheets when the strips extend in parallel planes. However, the method and apparatus described in this patent for making this structure have certain disadvantages.

FR-A-1364674 discloses a light control window covering comprising a first relatively translucent sheet material, a second relatively translucent sheet of material, disposed parallel to said first sheet, a plurality of strips of relatively opaque material, each having edge portions, said strips having their edge portions secured to said first sheet and said second sheet, respectively, whereby central portions of said strips, in a first closed position of said window covering, are substantially planar and extend substantially parallel to the first and second sheet, effective at least partially to block transmission of light and, in the second position of said window covering extend generally transverse to said first and second sheets, effective to transmit light between said strips.

According to the present invention, the edge portions of the strips are secured to the first and second sheets by adhesive bonding, preferably by means of a hot melt adhesive, at locations such that in said first positions adjacent strips substantially abut, but do not overlap.

This is in direct contrast to the window covering of FR-A-1364674, in which the edges of the strips are secured by welding. This welding must necessarily cause melting of the first and second sheets which produces unsightly lines in the sheets. With the structure of the invention, because the securing is by means of an adhesive, there is no melting of the sheets and an aesthetically attractive window covering can be produced.

Because the strips substantially abut, but do not overlap, they can be maintained parallel and in substantially the same plane by pulling on the outer sheets. Substantially all of the light incident on one of the outer sheets is thus blocked and the window covering can radially be rolled up for further processessing or in use.

In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings in which:-

• Figure 1 is a schematic side view of one form of apparatus for forming a window covering of the present invention;
• Figure 2 is a somewhat schematic cross-sectional view of one form of window covering according to the invention and formed by the apparatus of Figure 1;
• Figure 3 is a view of the window covering of Figure 2 shown in its expanded position; and
• Figure 4 is an end view of the middle web of Figure 1 showing the slitting lines.

Referring first to Figure 1, rolls (not shown) of first 50, second 51, and third 52 webs or sheets of material are fed from the left. The webs 50 and 51 are made from an optically transparent material, which expression is meant to cover a clear material or a translucent material which allows light directly or in diffused form to pass through, or a coarse mesh or other coarse material. Web 52 is made from an optically opaque material, by which is meant to include a material by which light is normally blocked or diffused such that objects on the outside are not imaged on the window and therefore are not identifiable unless the user knows the structure or its access. Thus, by appropriate choice of material for the third intermediate web, any degree of darkening can be achieved, and thus the invention is not limited to a particular material. The use of a mesh or coarse material for the outer webs will enhance air flow.

Suitable adhesive application means 55 provide longitudinal lines of quick-dried or other adhesive 57 to the first and second sheets 50,51 via a conventional heated or cooled roller 58. The middle or third sheet 52 is fed at an equal rate with sheets 50 and 51 through a conventional slitter 59, which divides the middle sheet into a plurality of longitudinal strips 60 along lines 61 extending parallel to the downstream direction of the webs. See Figure 4. Instead of applying glue lines to the outer webs, alternatively, glue lines can be applied to opposite sides of the long edges of the strips 60, or at appropriate places to opposite surfaces of the second sheet 52 before it is slitted. As still another alternative, the supply of the strips, instead of being a single sheet subsequently slitted, can be a plurality of spools each supplying one of the strips. Figure 4 illustrates the subdivision of the web or sheet 52 into discrete strips 60 by slitting along the dotted lines referenced 61. A slitter similar to that employed in US-A-4885190 can be used for this purpose. The slit strips 60 are maintained in their adjacent planar orientation by means of a conveyor belt system referenced 64. If desired, as is known, suitable reduced pressure can be applied to perforated belts of the conveyor system 64 to ensure that the cut strips maintain their original position. The outer webs 50,51 and the inner subdivided strips 60 are juxtaposed and joined at rollers 70, and then fed through heated rollers 71. The latter function to supply head and pressure to activate the continuous adhesive lines 57 to cause the outer edges of each of the strips 60 to bond respectively to the upper 50 and lower 51 webs. If non-heat-activated adhesives are used, the roller 71 need not be heated.

Figure 2 illustrates the arrangement. The adhesive lines 57 are applied continuously in the downstream direction such that each line 57 on the upper sheet 50 faces the left edge (as viewed in Figure 2) of each strip 60, and each line 57 on the lower sheet 51 faces the right edge of each strip 60. When the so arranged materials pass through the bonder rolls 71, each strip left edge is bonded to the upper sheet, and each strip right edge is bonded to the lower sheet. The resultant assembly, referenced 72, can then be wound up on a roll 73 for further processing.

The process, as will be noted, is continuous and uninterrupted. The resultant structure wound up on the roll 73 has strips 60 extending lengthwise in the structure. In comparison, the intermediate strips in the rolled up structure depicted in the referenced US-A-3384519 extend transverse to its longitudinal direction. The width of the outer sheets (the horizontal dimension in Figure 2) corresponds to the length of a window covering with horizontal slats. The structure resulting in the process of the invention depicted in Figure 2 can be used in the same manner as depicted in US-A-3384519. Assuming that the outer sheets 50,51 are light transparent, and the strips 60 are light opaque, in the window covering position shown in Figure 2, when the strips are maintained parallel and substantially in the same plane by pulling the outer sheets in the directions indicated by the arrows, substantially all of the light incident on one of the outer sheets is blocked. For clarity, spaces have been left between adjacent edges of the sheets, but in actual practice the sheet edges would abut for maximum light blocking. If the outer sheets now are displaced in the opposite direction, as indicated by the arrows in Figure 3, until the strips 60 extend in spaced parallel planes, as illustrated in Figure 3, it will be evident that minimum blockage of light incident on one of the outer sheets occurs. Intermediate positions of the outer sheets can thus vary the light transmission between the minimum and maximum values described above. Using outer sheets that are air transparent and inner strips that are air opaque would similarly control air flow between minimum and maximum values. In the embodiment illustrated in Figure 2, the middle sheet 52 has been slit into six individual strips. It is of course evident that the invention is not limited to this number. The principal restriction of the invention is the overall width of the sheets, which determines the length of a window covering with horizontal slats. But sheets of suitable material of a width length or height are readily obtainable from material suppliers.

Any of the materials and adhesives described in US-A-4450027, 4849039; 4885190 or 3384519 can be employed in this process.

Though now shown in Figure 1, with certain materials it may be desirable to score the strips 60 before they are assembled and adhered to the outer webs 50,51. The scoring preferably is provided at the strip locations where the strips bend when the finished shade is opened as shown in Figure 3. Score lines are readily formed in the strips 60 at such fold locations indicated by the arrows 80 in Figure 3 to assist in defining the strip shape, to simplify folding, or to enhance its appearance.

It will be understood from the description given that the invention is not limited to webs of the same colour. The front and back sheets can be of colours different from one another as well as different from the intermediate strips. Moreover, if the strips are supplied from separate spools, even they can be of different colours. Also, the invention is not limited to varying colours, but could also include other attributes of the material, such as texture and degree of transparency of porosity.

The typical sheet material or webs used for such structures are usually stretched in their long direction to improve their strength and reduce stretching during use. In the structures made according to the invention, if hung horizontally, depending upon the width of the window, some stretching may occur. This can be avoided by using blown sheets of material, which have uniform strength properties in all directions. Alternatively, the structure can be arranged so that the strips are hung vertically in the direction in which the material is normally stretched.