Roman shade and method of fabricating a roman shade

Abstract: An expandable and contractible window covering comprising a series of elongated cells (2). Each cell is formed by joining two pleated sheets (18, 19) of material in the area of opposing creases (20, 22). The rear wall (8) of the cell is of less height than the front wall (11) of the cell, and the material of the cell is chosen to be relatively soft and flexible, so that the front wall (11) of each cell droops downwardly and outwardly away from the rear wall at least to the juncture of the directly adjacent lower cell.

Description: This invention relates to an improved window covering. Several publications show cellular shades, wherein a fabric material is formed to define parallel tubular cells extending horizontally across the width of the shade. Air within each of the cells only circulates minimally, such that when expanded the shades provide good thermal insulation. It is, of course, desirable to make the physical appearance of the shade as attractive and as economically as possible, which requires both that a minimal amount of material be used to form each cell and that the manufacturing process be as expeditious as possible. Prior disclosures include the following: US-A-2201356 discloses a window shade made by joining two folded sheets having interior and exterior folds. Figures 4 and 5 show an asymmetrical embodiment where the interior folds of one sheet are joined to the exterior folds of one sheet are joined to the exterior folds of the other sheet. US-A-3892898 relates to a honeycomb panel core having interlocking expandable and contractible W-shaped and V-shaped components disposed between partition plates. US-A-4347887 shows a "thermal shutter". A wide band of material is folded transversely to form a double row column of adjacent cells, which may have rounded visible contours. The cells are adhesively bonded to one another and are symmetrical, so that both sides of the shade thus formed have essentially the same appearance. US-A-4631217, 4676855 and 4677013 show in Figure 3 a shade of asymmetrical construction. A rear wall section of each cell is essentially straight or linear when the shade is in its expanded position. The width of these rear wall sections thus defines the spacing of the adjacent cells, while the front of each cell, containing more material, maintains a non-linear shape. US-A-4685986 shows in Figures 1 and 3 shades of nearly symmetrical construction and symmetrical construction, respectively. The cellular shade is formed by joining two pleated lengths of material along opposing pleats. Figure 6 shows an asymmetrical embodiment of the invention, in which the rear wall is essentially straight when the shade is in its expanded position. US-A-4846243 shows a foldable window covering formed of a wide relatively soft material folded transversely, to yield a collapsible shade. The front surface of the shade consists of a material doubled back on itself. The successive cells are spaced in the expanded position of the shade by a relatively vertical rear wall section of each cell. US-A-4861404 shows a method of making a honeycomb product from two sheets of pleated material. Alternating pleats are formed of large and small dimensions, and end parts of the large pleats are then bonded together to form leg portions. These leg portions are then joined to opposing pleats of another sheet. According to the present invention there is provided an expandable roman shade member having a width and a series of parallely arranged elongated general tubular cells extending across said width, said shade member comprising a first single piece of flexible sheet material defining a rear wall of each of said cells, said first piece of sheet material having a length, a second single piece of flexible sheet material defining a front wall of each said cells, said second piece of sheet material having a length longer than the length of said first piece of material, means joining together transversely extending surface areas spaced along the length of said second piece of material to transversely extending surface portions spaced along the length of said first piece of material, the intervals between the spaced apart surface areas of said second piece of material being greater than the intervals between the confronting spaced apart surface portions of said first piece of material thereby forming said cells with said second piece of material defining a set of transverse folds spaced along the length of said second piece of material so as to allow the front wall of each cell to project outwardly and away from the rear wall of each cell when the rear wall defines a substantially planar surface in the expanded state of the shade, said front wall of each said cell defining a curved surface forming a loop drooping downwardly to extend over the juncture with the directly adjacent lower cell. The invention also provides a method of fabricating an expandable roman shade member having a plurality of superimposed cells parallel to a main surface thereof in the expanded condition of the shade member comprising the steps of:- a) progressively feeding a length of a first foldable sheet material longitudinally of its length; b) progressively feeding a length of a second sheet material longitudinally of its length and towards said first material; c) providing a first set of transverse creases spaced along the length of said second material; d) joining the two materials together by connecting each crease of said second material to surface portions of said first material which extend transversely thereof at locations spaced along the length of said first material at intervals less than the intervals between the creases of said first set; e) collecting joined portions of the two materials in a common direction; and f) as the two lengths of joined material are collected maintaining the length of second sheet material free of permanent creases. The structure of the invention, which may be produced by the above method, provides an inexpensive shade with a pleasing appearance. 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:- drawings, in which:- Fig. 1 is a perspective view of a first embodiment of the shade of the invention in its nearly collapsed state; Fig. 2 is a similar view of the shade in its expanded state; Fig. 3 is an enlarged cross-sectional view of the shade of Fig. 1 in the expanded state showing the individual cell structure of the shade; Fig. 4 is a similar view to Fig. 3 of a second embodiment; Fig. 5 is a view similar to Fig. 3, but of the shade of Fig. 3 in the nearly collapsed state; Fig. 6 is a schematic view showing one manufacturing method employed in producing the cellular structure of Fig. 3; Fig. 7 is a similar view showing the manufacturing process employed in producing the cellular structure of Fig. 4; Fig. 8 is a schematic view showing a first alternative pleating and joining process according to the present invention; and Fig. 9 is a schematic view showing a second alternative pleating and joining process according to the present invention. The shade shown in Figs. 1 and 2 comprises a series 1 of parallelly arranged cells 2 extending horizontally and fitted with a bottom rail 3 and a head rail 4 (omitted from Fig. 2 for clarity). The series is adapted to be fitted into a window opening, for example, with the longitudinal cell axis transverse to the direction of expansion and contraction of the assembly. The motion of the shade between the collapsed state of Fig. 1 and the expanded state of Fig. 2 is controlled by lift cords 5 extending from the bottom rail 3 upwardly across the cells 2, and into the head rail 4. The cords are directed by generally conventional control pulleys, guides and the like, and are engaged by a conventional locking dog engaging mechanism (not shown). As indicated in Figs. 3-7, the open ended tubular cells 2 are formed by first and second sheets 18, 19 of flexible fabric material, each having a set of transverse creases defining pleats, and the sheets are joined to one another in the area of confronting, inwardly-directed first creases 20, 22 (i.e. the creases which point toward the center of the shade when complete). First sheet 18 defines back faces of the cells, and second sheet 19 defines front faces of the cells, the faces being those portions which are visible when the shade is in use. Preferably, the sheet which makes up the back of the shade has a second set of outwardly-directed creases 21 to aid in the manufacture and operation of the shade. Each cell 2 has a cross-sectional shape including a drooping front wall 11 extending downwardly from the top portion of each cell at least as far as the juncture between the cell and the directly adjacent lower cell when the shade is in the expanded state and projecting outwardly and away from its back face, so that each cell is wider toward its bottom. Accordingly, when the shade is in its collapsed state as shown in Fig. 1, the drooping loop formed by each cell extends well below the juncture with the adjacent lower cell. As typically used, these shades are disposed between opposed surfaces of the casing of a window. The width of the shade is preferably chosen so that the ends of the cells approach the casing closely, such that little air flow takes place through the cells. In this way, the air mass in each cell is essentially static, whereby the cells of air form very effective thermal insulation. According to the embodiment of the invention shown in Fig. 3, the pleated sheets of material are joined by beads 6 of adhesive at confronting first creases 20, 22 which partially overlap each other. One of these sheets 18 defines a rear wall portion 8 extending downwardly from a top rear portion 7, and a bottom rear portion 9 extending forwardly from the rear wall portion. The second sheet of pleated material 19 defines a front wall portion 11 extending downwardly from a top front portion 12, and a bottom front portion 10 extending rearwardly from the front wall. The top front portion 12 of one cell is bonded by the bead 6 of adhesive to the bottom rear portion 9 of the adjacent upper cell. The formed cells in cross-section effectively define continuous closed loops of material. According to the preferred embodiment of the invention, it is desirable that the cell be asymmetrical such that the rear wall portion 8 is of substantially less height (as measured in the vertical direction of the final window covering, transverse to the longitudinal axis of the cell) than the front wall portion 11. Thus, the rear wall portion would determine the amount of cell expansion which is possible. In this way, each cell can be arranged to be of predetermined height from the top to the bottom of the shade, for effecting the desired appearance. The extent of cell expansion of the assembly is thus controlled by the height of the rear wall portion 8 of each cell; this, together with the amount of material in the front wall portion, determines the curvature of the generally curved surface of the front wall portion 11 of the cell. It is also preferred that the entire sheet be formed of a relatively soft and flexible fabric material so that in the expanded position shown in Fig. 3, the front wall portion 11 droops downwardly and outwardly away from the rear wall 8, forming a smoothly rounded curve. Typically, the lowest part of the front wall portion is level or beneath the juncture of the cell with the directly adjacent lower cell. This provides an extremely attractive appearance. It is further preferred that the front wall portion not be creased perceptibly when the shade is in use, principally for aesthetic reasons. It is not necessary that both sheets be pleated. One sheet may be provided with a first set of pleats, which are joined at intervals along the length of a second, unplated material. Among the alternative embodiments of the invention, a minimum of one set of pleats on one sheet is therefore required. A temporary crease to assist in manufacture of the shade of the invention can be provided in a number of ways. For example, in order to form a permanent crease in a polyester film material, it is necessary to heat the material to a given temperature while folding it and to press it against a hard surface to form a sharply set crease. However, a temporary crease can be formed during the manufacturing process by pressure with a limited amount of heating. If the shade is then hung and allowed to expand, and the crease is heated above a transition temperature, the polyester material will tend to return to its original shape, so that the temporary crease will effectively disappear. Similarly, a cotton fabric with a water soluble sizing such as starch can be used to form the shade of the invention. Such a sized cotton fabric can be creased as if it were paper. However, the starch can be dissolved if the shade is subsequently hung out and wetted, removing the creases. Similar techniques may be useful with polyester and synthetic materials. The basic method of forming the series of cells of the embodiment of Fig. 3 includes an initial step of folding the sheets of material into a pleated form as shown in Fig. 6. The basic method is fully disclosed, most particularly at column 4, line 15 through column 6, line 50, in US-A-4685986, the disclosures of which is incorporated herein by reference. The basic method of forming the series of cells of the embodiment of Fig. 4 as shown in Fig. 7 is similar to that of Fig. 6 but employs separate strip material 28 between opposing, inwardly-directed creases 20, 22 to join the two sheets. This method is also disclosed in US-A-4685986. As indicated above, it is an object of the preferred embodiment of the invention to provide a shade having cells each with the appearance of a smooth and uncreased curved front wall portion 11, and in which permanent creases are avoided during assembly. In the process shown in US-A-4685986, an expandable-collapsible honeycomb structure is provided from two pleated lengths of material; one of these materials will form one side of the honeycomb structure, while the other will form the other side. Thus, they can be made of the same or different material. Also, the creases in the material can be formed as part of the honeycomb forming process or can be preformed. In any event, the pleated materials are joined together along their creased areas. Permanently creasing the front wall portions in the same manner as in US-A-4685986 is avoided, to provide smooth front wall portions for the sake of appearance. Figs. 6 and 7 of the present application partially show the apparatus of the US-A-4685986, as used in accordance with the teachings of the present invention. In both figures, the two sheets of material are attached in the area of confronting, inwardly-directed creases. As shown in Fig. 6, the honeycomb structure 17 is formed by continuously feeding a continuous length of each of the materials 18 and 19 longitudinally of their length and in directions extending toward each other. The first material 18 has a first set of transverse creases 20, and a second et of transverse creases 21 spaced along the length of the material in alternating fashion. The second piece of material 19 has only a first set of transverse creases 22. The first sets of creases on both materials permit the materials to collapse in the accordion fashion shown in Fig. 6 where the creases define the points at which the material folds for the shade to collapse. As the first and second materials are fed in opposite directions, they are fed along a first path in partially collapsed condition. As they near each other, they are progressively brought into and fed along a common second path. The successive confronting and inwardly-directed creases 20 and 22 of the two pieces of material are brought into partially overlapping relationship as they are turned from their first path into the common second path and they are then directly attached together in this overlapping relationship. For this purpose, adhesive may be applied to one or both of the materials adjacent the creases 20 and 22. Fig. 6 shows schematically an adhesive applicator at 24 for applying a bead of adhesive 25 to one side of each of the creases 20. This adhesive may extend the full length of the crease or may be applied intermittently. As the successive confronting creases 20, 22 are brought into overlapping relationship, they are supported by suitable backup structure 26 while a pressure member 27 moves down onto the overlapped creases to press them into adhering relationship. The backup structure 26 can be intermittently moved into and out of supporting relationship and can also be used to move the combined cell structure downwardly along the second common path after each set of creases is secured together. After the materials are joined together, they are collected in their common path. Throughout the process, formation of permanent creases in the front faces of the cells is avoided. Details of this process are found in US-A-4685986. The confronting, inwardly-directed creases 20, 22 aid in the folding of the two materials in accordion pleated fashion as the cells are moved to and from collapsed and expanded condition. The first material 18 has an additional set of outwardly-directed creases 21, in alternating relation with creases 20, which will also aid in the folding of the two materials and will give the shade a pleated appearance on one side. The other material does not have outwardly-directed creases, but rather is allowed to fold up in accordion-like fashion while providing a smoothly-curved drooping surface when the window covering is completed. Temporary creases or smooth folds may be formed at 23 to aid in the manufacturing process. The distance between creases 22 is greater than the distance between creases 20, in order that material 18 provides a rear wall of the shade which determines the maximum possible expansion of the shade. Material 19 therefore will provide the drooping appearance desired for the shade even in the fully expanded state. Further, as seen from Fig. 6, the connecting of the adjacent cells together is effected while the two materials 18 and 19 are maintained in partially expanded condition. Thus, any bleeding of adhesive through the materials during he adhesive application or pressing operation will not cause any severe manufacturing problems. With the present invention, it is only desirable that the cells remain in their partially expanded condition until the adhesive is set, but the thickness of material in the area of attachment should prevent manufacturing difficulty. With reference to Fig. 7 showing schematically the method of manufacture used in producing the honeycomb structures of Fig. 4, the two pieces of pleated material are fed along a first path, and as they are turned into a second common path, the creases 20, 22 are brought into laterally spaced relationship with each other. As each pair of associated creases attains this relationship, a piece of strip material 28 is brought into overlaying relationship with the creased areas and joined thereto. For this purpose, suitable support means 26' and a cooperating pressure member 27' are used, similar in construction and operation to corresponding means shown in Fig. 6. Details of this method may be found in US-A-4685986. An alternative manufacturing process, shown in Fig. 8, both pleats and joins the materials to form a shade similar to that shown in Fig. 7. The additional step of pleating materials 18 and 19 is carried out respectively, by first reciprocating forming knife 31 and second reciprocating forming knife 32. Second forming knife 32 has a curved surface 33 on one side to avoid creasing material 19 on its surface over what will be the front faces of the cells. Support structures 34 provide the surface against which the forming knives press the materials during pleat formation. Surface 35 further assists the first forming knife 31 by providing a surface against which outside pleats 20 can be formed on material 18. The remainder of the process shown in Fig. 8 is substantially the same as shown in Fig. 7. Another alternative manufacturing process is shown in Fig. 9, which may be used to form the shade of the invention where only one set of pleats is formed on one sheet of material. As Fig. 9 shows, material 18 is fed between first forming conveyor 41 and second forming conveyor 42. First forming conveyor 41 has knife portions 43 which, in cooperation with support portions 44 of second forming conveyor 42, create creases 22 in material 19. Material 19 is provided uncreased, with beads of adhesive 25 at intervals along its length. Material 19 is joined at creases 22 to material 18 by these beads of adhesive. The resulting shade structure will have no outwardly-pointing creases, and will have a smoothly drooping front wall portion.

Claims: An expandable roman shade member having a width and a series of parallely arranged elongated general tubular cells (12) extending across said width, said shade member comprising a first single piece of flexible sheet material (18) defining a rear wall (8) of each of said cells, said first piece of sheet material having a length, a second single piece of flexible sheet material (19) defining a front wall (11) of each said cells, said second piece of sheet material having a length longer than the length of said first piece of material, means (6,5,28) joining together transversely extending surface areas (22) spaced along the length of said second piece of material to transversely extending surface portions (20) spaced along the length of said first piece of material, the intervals between the spaced apart surface areas of said second piece of material being greater than the intervals between the confronting spaced apart surface portions of said first piece of material thereby forming said cells with said second piece of material defining a set of transverse folds (22) spaced along the length of said second piece of material so as to allow the front wall of each cell to project outwardly and away from the rear wall of each cell when the rear wall defines a substantially planar surface in the expanded state of the shade, said front wall of each said cell defining a curved surface forming a loop drooping downwardly to extend over the juncture with the directly adjacent lower cell. A roman shade member as defined in claim 1, wherein the spaced apart surface areas on said second piece of material are preformed creases (22). A roman shade member as defined in claim 2, wherein the spaced apart surface portions on said first piece of material are preformed creases (20). A roman shade member as defined in claim 3, wherein the first and the second piece of materials are connected together by direct attachment of the material of confronting creases (20,22) in overlapped relation. A roman shade member as defined in claim 1, including separate lengths of elongate strip material (28) joining surface areas (22) on said second piece of material (19) to confronting surface portions (20) on said first piece of material (18), whereby the first and second pieces of materials are attached together between adjacent overlying cells. A roman shade member according to any preceding claim, characterised in that the curved appearing surface of said front wall portion (11) in the expanded state of the window shade defines a loop that extends in front of at least part of the front wall portion of the directly adjacent lower cell (2). An expandable roman shade assembly including a roman shade member according to any preceding claim, and further comprising:- a) a head rail (4) to which a top portion of the uppermost cell (2) is connected; b) a bottom rail (3) to which a bottom portion of the lowermost cell (2) is connected; and c) two or more guide cords (5) extending from the bottom rail (3) upwardly through each of the cells and into the head rail (4). A method of fabricating an expandable roman shade member having a plurality of superimposed cells (2) parallel to a main surface thereof in the expanded condition of the shade member comprising the steps of:- a) progressively feeding a length of a first foldable sheet material (18) longitudinally of its length; b) progressively feeding a length of a second sheet material (19) longitudinally of its length and towards said first material; c) providing a first set of transverse creases (22) spaced along the length of said second material (19); d) joining the two materials (18,19) together by connecting each crease (22) of said second material (19) to surface portions of said first material which extend transversely thereof at locations spaced along the length of said first material at intervals less than the intervals between the creases of said first set; e) collecting joined portions of the two materials in a common direction; and f) as the two lengths of joined material are collected maintaining the length of second sheet material (19) free of permanent creases. A method according to claim 8, characterised in that said first material (18) is creased to form a first set (20) of transverse creases spaced along the length thereof in alternating fashion with said first set of creases (22) of the second material (19). A method according to claim 9, characterised in that said first and second materials are brought into partially overlapping relationship at confronting creases (20,22) of said first sets of creases and joined together in said overlapping relationship. A method according to claim 9, further comprising the steps of:- a) feeding a piece of strip material (28) successively into overlying relationship with a respective crease associated with each first set of creases (20,22) of the first and second materials as the materials are being brought into said common path; and b) joining said strip material to each respective crease of said first set of creases.

Inventors: COLSON WENDELL B, COLSON, WENDELL B.
Applicants: HUNTER DOUGLAS INTERNATIONAL, HUNTER DOUGLAS INTERNATIONAL NV
Application year: 1990
Main classification: E06B9
IPC codes: B31D3, E06B9, B29C53