EP1447516A2 - Cord tensioner - Google Patents

Abstract

A cord tensioner (19,21) for a guide cord (15,17) of a cord-guided blind (1) which has an upper rail (3),a lower rail (5) and a blind material (7) extending between the upper and lower rails (3,5) andin which the upper rail (3), the lower rail (5) or both is movable; the cord tensioner (19,21) beingattached to the upper or lower rail (3,5); and wherein the cord tensioner (19,21) includes acompression spring and the guide cord engages the spring so that a pullingforce on the guide cord compresses the spring.

Description

• This invention relates to a cord tensioner for a cord-guided covering for anarchitectural opening.
• Such a cord-guided covering can be a roller blind, a pleated blind, aVenetian blind, or a combination of such blinds. And such a blind or combinationof blinds can be mounted in an architectural opening such as e.g. a window or ina slanted window, such as a roof window.
• Cord tensioners for cord-guided coverings have been conventionally usedto keep the guide cords of the window coverings taut. One of the effects of thecord tensioners is that a movable rail such as a head, intermeditate or bottomrail, which slide along the cords, will be kept in place when they are not beingoperated. The movable rails are particularly kept from sliding down along thecords, under their own weight by the tension of the cords and the friction betweenthe cords and the movable rails. In slanted windows, the taut cords prevent thefabrics and slats of window coverings from sagging downwardly away from thewindows.
• Cord tensioners traditionally are common type tension springs. Suchtension spring type cord tensioners for guide cords of window coverings aredescribed in US 4,733,711 and US 4,557,309. However, tension springs have theinherent problem that they can be over-stretched, particularly when movable railsof their window coverings are moved up or down abruptly, so as to stretch theguide cords. Such springs can then be over-tensioned before the movable railstarts to slide along the guide cords, since the springs will bear the sudden,though temporary, force. Also when in the life-time of a blind, the guide cordsextend in length by wear and tear, and the cords have to be re-tensioned,generally the tension spring is pulled out further.
• It has been known to protect a tension spring against over-tension bymounting a cord between the two spring ends, the cord having a length that isshorter than the maximum expanding length of the spring. A problem with this solution is that the cord must always too long for the spring in normal use, andthe excess length can get easily snagged between the coils of the spring.
• Another solution, described in EP 0,699,268, is to provide two loopedcords that are slidably attached to opposite ends of a tension spring and twostops that are spaced apart from opposite ends of the tension spring to preventthe spring from being over-tensioned. A drawback of this section is the need ofproviding extra space where the tension spring is placed. Also, since a singletension spring is generally used, the guide cords must be made as looped cords.
• In accordance with this invention, a cord tensioner is provided fortensioning a guide cord of a cord-guided blind which has an upper rail, a lowerrail and a blind material extending between the extending between the upper andlower rails and in which the upper rail, the lower rail or both is movable; the cordtensioner being attached to the upper or lower rail; wherein the cord tensionerincludes a compression spring and the guide cord engages the spring so that apulling force on the guide cord compresses the spring.
• Advantageously, the cord tensioner also includes a housing containing thespring. It is especially advantageous that the housing include an abutmentmember, against which the spring can be compressed by the cord, when it ispulled. It is also especially advantageous that the housing also include a hollowlongitudinally-extending interior space, in which the spring can expandlongitudinally when not being pulled by the guide cord, and an opening, throughwhich the cord can enter the interior space longitudinally, the abutment memberbeing located within the opening.
• Further aspects of the invention will be apparent from the detaileddescription below of particular embodiments and the drawings thereof, in which:
• Figure 1 is a schematic perspective view of a cord-guidedpleated blind with two movable rails and two guide cords; shownin cross-section are two cord tensioners of a first embodiment ofthis invention, mounted in the lower rail;
• Figure 2 is an exploded view of one of the cord tensioners ofFigure 1;
• Figure 3 is a cross-section of the cord tensioner of Figure 2,showing its attachment to one of the guide cords and itscompression spring in a relaxed state;
• Figure 4 is a cross-section of the cord tensioner of Figure 2.with its compression spring partially compressed;
• Figure 5 is a schematic perspective view of a cord-guidedblind with two guide cords, a fixed head rail and a movablebottom rail; shown in cross-section are two cord tensioners of asecond embodiment of the cord tensioner of the invention,mounted in the head rail;
• Figure 6 is an exploded view of one of the cord tensioners ofFigure 5;
• Figure 7 is a cross-section of the cord tensioner of Figure 6,showing its attachment to one of the guide cords and itscompression spring in a partially compressed state; and
• Figure 8 is a cross-section, similar to Figure 7, showing athird embodiment of the cord tensioner of the invention.
• Figure 1 shows a cord-guided pleated blind 1 of the inventionhaving a movable, longitudinally-extending hollow upper rail orbar 3, amovable, longitudinally-extending hollow lower rail orbar 5, and a pleatedblind material 7 extending between therails 3, 5. The blind 1 also has leftand right,elongated side guides 9, 11 which are perpendicular to, and infront of, therails 3, 5 and are also in front of left and right marginalportions of theblind material 7. Theside guides 9, 11 are mounted in awindow frame 13 which can be for a slanted roof window. The blind 1 hasleft and right,guide cords 15, 17 which are tensioned with left and right,cord tensioners 19, 21 and thereby hold therails 3,5 in different vertical positions in the blind. Theblind material 7 can be opened and closed bymoving the upper andlower rails 3,5 vertically along theside guides 9, 11.
• Thecord tensioners 19,21 are mounted in thelower rail 5. Theleft guidecord 15 is routed from the top of theleft side guide 9 to the bottom of therightside guide 11. Theright guide cord 17 is routed as a mirror image of the left cord,from the top of theright side guide 9 to the bottom of theleft side guide 11.
• Atop end 23 of theleft guide cord 15 is attached to the top of theleft sideguide 9, and from there, the left guide cord extends downwardly along, and to therear of, an upper part of theleft side guide 11 and then extends to the right intothe open left end of theupper rail 3. Inside theupper rail 3, theleft guide cord 15extends to the right, along aleft part 25 of the length of the inside of theupper rail3, towards theright side guide 11 and then extends downwardly through a firstleft opening 27 in the bottom of the upper rail. From the opening 27, theleft guidecord 15 extends downwardly through or along the pleatedblind material 7 andthrough a second left opening 29 in the top of thelower rail 5. Inside thelower rail5, theleft guide cord 15 extends to the left into theleft cord tensioner 19 where itforms a leftward-extendingloop 31, and then, the left guide cord extends to theright out of theright cord tensioner 21 and along aright part 33 of the inside ofthelower rail 5, towards theright side guide 11. From the open right end of thelower rail 5, theleft guide cord 15 extends downwardly along, and to the rear of,a lower part of theright side guide 11 to the bottom thereof, where the left guidecord is attached by itsbottom end 35.
• Theright guide cord 17 is similarly routed through the blind 1 but in amirror image. In this regard, a knotted top end 23' of theright guide cord 17 isattached to the top ofright side guide 11, then the right guide cord extendsdownwardly along, and to the rear of, an upper part of the right side guide andthen to the left into the open right end of theupper rail 3. Inside theupper rail 3,theright guide cord 17 extends to the left, along a right part 25' of the upper rail,towards theleft side guide 9, until the right guide cord extends downwardlythrough a first right opening 27' in the bottom of the upper rail. Thereafter, theright guide cord 17 extends downwardly through or along the pleatedblindmaterial 7 and then into a second right opening 29' in the top of thelower rail 5.Inside thelower rail 5, theright guide cord 17 extends to the right into therightcord tensioner 21 where it forms a rightward-extending loop 31', and then, theright guide cord extends to the left out of theright cord tensioner 21 and along aleft part 33' of the inside of the lower rail, towards theleft side guide 19. From theopen left end of thelower rail 5, theright guide cord 17 extends downwardlyalong, and to the rear of, a lower part of theleft side guide 11 and to the bottomthereof, where the right guide cord is attached by its bottom end 35'.
• Eachcord tensioner 19,21 of the invention includes acompression spring37, 37' which is put under tension when theends 23, 35, 23', 35' of theguidecords 15, 17 are attached to the top and bottom of theside guides 9,11. Thespring 37, 37' of eachcord tensioner 19, 21 is adapted to maintain tension in theguide cord 15,17, which is looped within it, as therails 3, 5 of the blind 1 aremoved vertically. When arail 3, 5 is moved upwardly or downwardly, it slides,together with thecord tensioners 19, 21 within it, along theguide cords 15, 17.As a result, theguide cords 15,17 move through thecord tensioners 19,21 andalong theloops 31, 31' which the guide cords form within the cord tensioners.
• Since the left and right cord,tensioners 19,21 are identical and aremounted as mirror images in thelower rail 5 of the blind 1, Figures 2-4 show onlythe details of theleft cord tensioner 19. Theleft cord tensioner 19 includes alongitudinally-extendingspring 37, a generally cylindrical,spring housing 39 andacord returner 41. Thespring 37 is a common type compression spring,preferably of a helically-wound spring steel, having a first orright spring end 43, asecond orleft spring end 45, and a plurality ofspring windings 47 extendinglongitudinally between the twospring ends 43,45. Thespring housing 39 has anelongated, longitudinally-extending hollow interior space suited for containing thespring 37 and allowing it to be compressed and expand longitudinally. The hollowinterior space 49 of thehousing 39 is preferably a longitudinally-extendingcylindrical space having an inner diameter (d) that is slightly larger than the diameter (D) of thecompression spring 37 and of thecord returner 41 and alength (I) that is preferably somewhat larger than the length (L) of thespring 37 inits relaxed state plus the length of thecord returner 41.
• Thespring housing 39 of theleft cord tensioner 19 includes anabutmentmember 51 which is perpendicular to the central longitudinal axis of the hollowinterior space 49 and coaxial to it. Theabutment member 51 is preferably shapedas an inturnedrim 53 on an openright end 55 of thespring housing 39. Theintumed rim 53 surrounds anopening 57 on the openright end 55, throughwhich the left guide cord 15 (as shown in Figure 1) move into and out of thehollowinterior space 49 of thespring housing 39. The diameter of theopening 57is smaller than the diameter of thespring 37. Theabutment member 51 has aninner surface 51A which faces into the hollowinterior space 49 of thehousing 39and against which the abuttingright spring end 43 can abut when thespring 37 isbeing compressed.
• Thespring housing 39 also includes aleft end 59 which preferably has adiameter equal to or larger than the diameter of the hollowinterior space 49 ofthehousing 39, so as to allow thespring 37 to be inserted into the housingthrough theleft end 59. Optionally, a closure cap (not shown) can be providedon theleft end 59 after thespring 37 and theleft guide cord 15 andcord returner41 have been assembled within the hollowinterior space 49 of thespring housing39.
• Thecord returner 41 of theleft cord tensioner 19, as shown in Figures 2-4,is preferably a longitudinally-extending, generally cylindrical member that canfit slidably in the hollowinterior space 49 of thespring housing 39 to the left of thespring 37. Thecord returner 41 has a first orleft end 61, a longitudinally-elongatebody 63, a second orright end 65, and acord groove 67 which extendsabout the top, bottom and left sides of the cord returner. Theright end 65 of thecord retainer 41 rests against theleft spring end 45. To this end, the diameter oftheright end 65 ofcord retainer 41 is bigger than the diameter of thespring 37.This means that when theleft guide cord 15 is pulled, causing it to be pulled to the right -- outwardly of thespring housing 39 ― it pulls theleft end 61 of thecordretainer 41 to the right, which causes theright end 65 of thecord retainer 41 tourge theleft spring end 45 to the right, thereby compressing thespring 37 to theright against theinner surface 51A of theabutment member 51 of the housing 39- without the left guide cord pulling thecord retainer 41 into thespring windings47.
• The cord groove 67 (shown in cross-section in Figures 3 and 4) of thecordreturner 41 has a smooth, generally aerodynamic shape such as that of anaircraft wing. Thecord groove 67 includes upper and lower, longitudinally-extendingsegments 69, 71 on its top and bottom. The upper andlower segments69,71 are joined by a curved, concave-right, connectingsegment 73 on theleftend 63 of thecord returner 41. The upper andlower segments 69,71 extendgradually closer towards each other as they get closer to theright end 65 of thecord returner, and preferably the upper and lower segments converge at therightend 65. The surface of thecord groove 67 is sufficiently smooth and its diameteris sufficiently large, relative to theleft guide cord 15, to allow the left guide cord toslide smoothly along it when the left guide cord is pulled by moving the upper orlower rail 3,5 vertically.
• As seen particularly from Figures 3 and 4, theleft guide cord 15 in theleftcord tensioner 19 is slung around thecord returner 41 in acord loop 31. The leftside of thecord loop 31 is located in the connectingsegment 73 of thecordreturner 41, and adjacent leftward top andbottom portions 75,77 of the cord loopare located in the in upper andlower segments 69,71 of the cord returner.Rightward top andbottom portions 75,77 of thecord loop 31 extend longitudinallythrough the center of thecompression spring 37 and to the right, out of thespringhousing 39, through itscord opening 57. As seen from Figure 1, thetop loopportion 75 can be traced to thetop end 23 of the left guide cord and thebottomlop portion 77 can easily be followed to thebottom end 35 of the left guide cord.
• When the blind 1 is to be installed in a slanted roof window or the like, itsguide cords 15, 17 are preferably routed already through its upper andlower rails 3, 5, itscord tensioners 19, 21 and itsblind material 7. The top and bottom ends23, 23', 35, 35' of the guide cords can then be attached to the top and bottom ofthe left and right side guides 9, 11 to put the guide cords under suitable tensionduring installation. For example, when the top ends 23,23' of the guide cords areattached first to the side guides and then the bottom ends 35, 35' are pulleddownwardly in order to attach them to the side guides, thesprings 37,37' of thecord tensioners are compressed. This is because, with reference to theleft guidecord 15, such pulling forces act through itscord loop 31 on thecord returner 41of theleft cord tensioner 19. Since thecord returner 41 abuts against the left endof thespring 37 of the left cord tensioner and cannot slide into this spring, suchpulling forces also act on the spring and compress it in itsspring housings 39.Once a desired tension is reached in theguide cords 15, 17, the bottom cordends 35, 35' are attached to the side guides. Thereby, thecompression spring37, 37' in eachcord tensioner 19, 21 will be partially compressed. With referenceto theleft cord tensioner 19, since itsspring 37 is biased to a relaxed state, thebiasing force of the spring will push itscord returner 41 towards theleft end 59 ofthespring housing 39 and thus keep the left guide cord under tension. When theupper and/orlower rail 3,5 is subsequently moved up or down along the rear ofthe side guides 9, 11 under normal operating conditions, thesprings 37, 37' ofthecord tensioners 19, 21 will not be compressed further significantly. Also therelative position of the springs will reduce the possibilities of a skewed bottom railwhen the rail is operated away from the center of the movable rail.
• If, during the life of the blind 1, theguide cords 15, 17 stretch and becomesomewhat longer, thesprings 37, 37' of thecord tensioners 19, 21 will also relaxsomewhat and therails 3, 5 may tend to sag. However, the tension in the guidecords can be easily restored, simply by detaching one end of each guide cord,pulling the guide cord tighter, and then reattaching it so that its length issomewhat reduced. Thereby, each guide cord will be slightly shortened to aboutits original length and its spring will be compressed to its original partiallycompressed state.
• Figures 5-7 show asecond embodiment 101 of a cord-guided pleatedblind of the invention which is similar to the blind 1 of Figures 1-4 and forwhich corresponding reference numerals (greater by 100) are used below fordescribing the same or corresponding parts.
• The blind 101 has a fixed longitudinally-extending hollow head rail orupper rail 103, a movable longitudinally-extending hollowlower rail 105 andaroller blind material 107 extending between the rails. The blind also has leftand right side guides 109, 111 which are mounted in awindow frame 113,such as for a slanted roof window, left and right, guidecords 115, 117which are tensioned with left andright cord tensioners 119, 121 in theheadrail 103, and a roller mechanism (not shown) in thehead rail 103 for raisingand lowering theblind material 107 and thereby moving thelower rail 105along the side guides 109, 111.
• The routing of theleft guide cord 115 is as follows: from theattachment of itstop end 123 to theleft cord tensioner 119 in thehead rail103, the left guide cord extends to the left towards theleft side guide 109;then it extends downwardly along, and to the rear of, theleft side guide 109and downwardly through or along the left marginal portions of theblindmaterial 107, which is also to the rear of the left side guide; then it extendsto the right into the open right end of thelower rail 105; and then it extendsto the right along the entire length of thelower rail 105. From the open rightend of thelower rail 105, theleft guide cord 115 extends downwardly along, andto the rear of, theright side guide 111, to the bottom thereof, where the leftguide cord is attached by its knottedbottom end 135.
• Theright guide cord 117 is similarly routed through the blind 101 but in amirror image. From the attachment of its top end 123' to theright cordtensioner 121 in thehead rail 103, the right guide cord extends to the righttowards theright side guide 111; then it extends downwardly along, and tothe rear of, the right side guide and downwardly through or along the right marginal portions of theblind material 107, which is also to the rear of theright side guide; then it extends to the left into the open left end of thelowerrail 105; and then it extends to the left along the entire length of thelowerrail 105 where it crosses theleft guide cord 115. From the open left end of thelower rail 105, theright guide cord 117 extends downwardly along, and to therear of, theleft side guide 109, to the bottom thereof, where the right guidecord is attached by its bottom end 135'.
• Since the left andright cord tensioners 119, 121 are identical and aremounted as mirror images in thelower rail 105 of the blind 101, Figures 6-7 showonly theleft cord tensioner 119. Theleft cord tensioner 119 has a longitudinally-extendingcompression spring 137 within aspring housing 139. Anabutmentmember 151, preferably shaped as an inturned rim 153, is provided on an openright end 155 of thespring housing 139. Instead of a cord returner, acord keeper179 is provided which is a longitudinally-extending, generally cylindrical memberthat can fit slidably in the hollow longitudinally-extendinginterior space 149 of thespring housing 139 to the left of thespring 137. Thecord keeper 179 can suitablybe of metal so that one longtiudinal end of it can be crimped to thetop cord end123 of theleft guide cord 115, or it can be of plastic with a longitudinally-extendingcentral hole, through which thetop cord end 123 can be threaded andthen held in place with a knot. The diameter of thecord keeper 179 is larger thanthe diameter of thespring 137, so that the cord keeper abuts against thespringend 145 and cannot be pulled in to the spring by the left guide cord.
• When the blind 101 of Figure 5 is to be installed in a slanted roof windowor the like, itsguide cords 115, 117 are preferably already attached to thecordtensioners 119, 121 in thehead rail 103 and are already routed along the sideguides 109, 111, theblind material 107 and through thebottom rail 105 to itsopen ends. When subsequently attaching the free bottom ends 135, 135' of theguide cords to the bottom of the left and right side guides 109, 111, the guidecords can be put under tension.
• Pulling the free bottom ends 135, 135' of theguide cords 115, 117, inorder to attach them to the side guides, compresses thesprings 137, 137' of thecord tensioners 119, 121 inhead rail 103. This is because, with reference to theleft cord tensioner 119, the pulling force acting on theleft guide cord 115 actsthrough itstop end 123 on itscord holder 179 and thereby on itsspring 137.Since thecord keeper 179 abuts against itscompression spring 137 and cannotslide into it, the force exerted on the left guide cord acts on the spring andcompresses the spring.
• Once the desired tension is reached in the bottom ends 135, 135' of theguide cords, they are attached to the bottom of the side guides 109, 111. Withreference to theleft cord tensioner 119, thecompression spring 137 of eachcord tensioner will then be partially compressed. Since thespring 137 is biasedto a relaxed state, its biasing force will push itscord keeper 179 towards the openend of itsspring housing 139 and thus keep the left guide cord under tension.When thebottom rail 105 is moved up or down, along the side guides 109, 111,under normal operating conditions, the spring will not be compressed significantlyfurther.
• If needed during the life of the blind 101, itsguide cords 115, 117 can beconveniently retensioned if they have become longer.
• Figure 8 shows athird embodiment 219 of a left cord tensioner of theinvention for a cord-guided pleated blind which is similar to theleft cordtensioner 19 of Figures 1-4 and for which corresponding reference numerals(greater by 200) are used below for describing the same or correspondingparts.
• Theleft cord tensioner 219 has aspring housing 239 with a hollowlongitudinally-extending interior space 249 that contains a longitudinally-extendingcompression spring 237 and acord returner 241 to the left of thespring. Anabutment surface 251 is provided on the open left end of thespringhousing 239. Thecord returner 241 has apulley 281 around which is a loop of aleft guide cord 215 . The diameter of the hollow interior space 249 is larger than the diameter of the compression spring and thecord returner 241, so that springand the cord returner can move freely therein in a longitudinal direction. Thediameter of thecord retumer 241 is also larger than the diameter of the spring, sothat the cord returner abuts against the adjacent end of the spring when the cordreturner is pulled longitudinally by theleft guide cord 215. Thecord pulley 281facilitates the sliding of theleft guide cord 215 around thecord returner 241when theleft guide cord 215 is pulled.
• The cord tensioners 19, 21, 119, 121 and 219 of the invention can beused in any conventional cord-guided blinds for many different types of windows,without having to be redesigned. It may be necessary, for windows that areexceptionally steeply slanted and/or with bigger surfaces and/or for heavierblinds, to use acompression spring 37, 137, 237 that is bigger and stronger. It isof course well known that changes in diameter, number of windings, materialused etc will result in different spring characteristics.
• This invention is, of course, not limited to the above-describedembodiments which may be modified without departing from the scope of theinvention or sacrificing all of its advantages. In this regard, the terms in theforegoing description and the following claims, such as "vertical", "longitudinal","perpendicular", "upwardly", "downwardly", "inner", "outer", "right", "left", "front","rear", "top", "bottom", "upper" and "lower", have been used only as relativeterms to describe the relationships of the various elements of the cord tensionerfor a cord-guided window covering of the invention as shown in the Figures.
• For example, kinematic inversions of the elements of the cord-guidedwindows, described above, are to be considered within the scope of theinvention.
• Also, theblinds 1, 101 can be provided with one or more additionalmovable longitudinally-extending rails and additionalblind materials 7, 107,between the additional rails, and theguide cords 15, 17, 115, 117, 215 can passlongitudinally through the additional rails to guide vertical movement of theadditional rails within the blinds. So that for example a roller blind can be combined with a pleated blind in the same window. Having a mutual intermediatebar. The pleated blind of such a composite blind can be cord guided, while theroller blind can be guided by side guides. The side guides for such a blind wouldpreferably have a channel portion, and the free rims of the roller blind that areguided in the channel portion of the side guides can have side guiding pipspreventing the roller blind material from escaping from the channel portions of theside guides. The roller blind can be at the top portion of the window and thepleated blind at the bottom. The blind at the top portion can also be a roller blindtype insect screen.
• Also therails 3, 5, 103, 105 and any additional rails are not necessarilyhollow, but can be longitudinally extending profiles that are open to front andback like e.g. a U-shaped profile or an I-shaped profile. The guide cords will thanbe routed along the open back of the rail profile, and the cord tensioner can beattached to the back of the profile. For example when the cord tensioner includesa cylindrical housing, the housing can be crimped in a longitudinally extendingrim of the rail profile. The crimping entails that the rim or a portion thereof isfolded over the cord tensioners housing using a special tool, keeping the cordtensioner in place.
• Also the cord-guided blind in which the cord-tensioners of the inventionare used, is not necessarily in a rectangular form. A blind for a triangular or apentagonal shaped window can be used, as long as the blind is a cord guidedblind.
• Moreover, instead of attaching theends 23, 23', 35, 35', 123, 123', 135,135' of theguide cords 15, 17, 115, 117 to the side guides 9, 11, 109, 111, theycan also be attached to the window frame. Also the cords can be attached to theside guides or to the window by using knots (pulling cord through a hole or aneyed pin and knotting it). Other cord attachment means, besides knots, can beused for attaching the ends of the guide cords to the side guides or to the windowframe. Such as e.g. a cord plate on to the end of a cord, that co-operates with apart of the side guide, that is of course relatively easy the detach and re-attach.
• Also, theabutment members 51, 151, 251 are preferably integrally formedwith thespring housings 39, 139, 239 as inturned rims on open ends of thehousings, but alternatively, an abutment cap member could be inserted in theopen end of a spring housing. Of course, such an abutment cap would have to besecurely fastened to the spring housing to prevent it from being pushed off of thespring housing by pulling forces on the guide cords.
• The outer shape of thespring housing 39, 139, 239 is of no consequenceto the operation of thecord tensioners 19, 21, 119, 121 and 219 of the invention.Thus any convenient shape can be chosen. Indeed, the spring housings can beintegrally formed, wholly or partly, with therails 3,5, 103, 105, in which the springhousings are located. A partly integrally-formed the spring housing could have abase cradle-like member shaped in the head rail and a counter-shaped cradlelike cap member to be snapped to it, together forming the hollowinterior space49, 149, 249 andabutment surface 51, 151, 251 needed to for thecompressionspring 37, 137, 237. Alternatively, an integrally-formed spring housing can be assimple as a first hollow cylinder of a first diameter that convenientlyaccommodates the spring and an adjacent second hollow cylinder for leading theguide cord in and out of the housing and a spring abutment surface beingprovided between the two cylinders. Alternatively, a spring housing can beshaped by a trellises, possibly no more than two parralel, longitudinally extendingtrellises that are connected to circular end rings, one of the end rings having aninturned rim and thus forming an abutment surface. The opening between thetrellises being such that the spring cannot pass between them.

Claims (14)

1. A cord tensioner (19, 21, 119, 121, 219) for a guide cord (15, 17, 115, 117,215) of a cord-guided blind (1, 101) which has an upper rail (3, 103), alower rail (5, 105) and a blind material (7, 107) extending between theupper and lower rails and in which the upper rail, the lower rail or both ismovable; the cord tensioner being attached to the upper or lower rail; andwherein the cord tensioner includes a compression spring (37, 137, 237)and the guide cord engages the spring so that a pulling force on the guidecord compresses the spring.
2. The cord tensioner of claim 1, wherein the cord tensioner further includesa housing (39, 139, 239) containing the spring.
3. The cord tensioner of claim 2, wherein the housing includes an abutmentmember (51, 151, 251), against which the spring (37, 137, 237) can becompressed by the cord, when it is pulled.
4. The cord tensioner of claim 3, wherein the housing (39, 139, 239) furtherincludes a hollow longitudinally-extending interior space (49, 149, 249), inwhich the spring (37, 137, 237) can expand longitudinally when not beingpulled by the guide cord, and an opening (55, 155, 255), through which thecord can enter the interior space longitudinally, the abutment memberbeing located within the opening.
5. The cord tensioner of any one of claims 2-4, wherein the housing isintegrally or partly integrally formed with the upper and/or lower rail (3,103, 5, 105).
6. The cord tensioner of claim 4 or 5 wherein the interior space (49, 149,249) of the housing is cylindrical with a diameter greater than the diameterof the spring (37, 137, 237) and a length that is at least equal to the lengthof the spring.
7. The cord tensioner of claim 6, wherein the housing is an elongated cradlelike member formed integrally with the upper and/or lower rail and has anelongated lid like member for closing the cradle and containing the spring.
8. The cord tensioner of any one of claims 3-7 wherein the abutmentmember is an inturned rim of the housing at a longitudinal end thereof.
9. The cord tensioner of any of claims 1-8, wherein the cord tensioner (119,121) is within a fixed rail (103) of the blind and the guide cord (115, 117)includes a top and a bottom cord end, one of which engages the spring.
10. The cord tensioner of any of claims 1-9, wherein the cord tensioner (19,219) is within a movable upper or lower rail of the blind and the guide cord(15, 215) has a loop (31, 231), between its ends, which engages thespring, so that there is a slidable connection between the cord tensionerand the guide cord.
11. The cord tensioner of any of claims 1-10, wherein the cord tensionerincludes an attachment member (41, 179, 241) for engaging the guidecord to the spring (37, 137, 237); the attachment member being mountedinside the housing in engagement with the spring and having a diameterlarger than the diameter of the spring.
12. The cord tensioner of claim 11 or 12, wherein the attachment member (41 )includes longitudinally-extending cord grooves (69, 71), along which theguide cord can slide longitudinally.
13. The cord tensioner of claim 11 or 12, wherein the attachment member(241) includes a rotatable cord pulley (281).
14. The cord tensioner of any one of claims 1-13, wherein the blind contains apair of the cord tensioners in the same upper or lower rail, arranged asmirror images in the blind and attached to different guide cords.

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