Vertical Blind Mechanism

The present invention relates to a vertical blind mechanism in which the vanes are mounted for traversing movement on a header across a window opening between an open and a closed position, and also for angular rotation about an upright axis for light control. Some prior vertical blind mechanisms, for example, as disclosed in U.S. Pat. Nos. 2,755,854; 4,006,769 and 4,257,470, mount the vertical vanes on rotary vane supports for traversing movement along the horizontal header and directly connect the vane supports to a pair of flexible cords or bead chains at fixed locations therealong so that the cords or bead chains control the spacing between adjacent vane supports when the vanes are drawn along the header to a closed position, and the cords or bead chains are also manipulatable to control rotation of the vane supports. In these prior vertical blind mechanisms, the cords or bead chain were connected to the vane supports at locations outside the header and the exposed cords or chains not only adversely affected the appearance of the blind mechanism when it was drawn to a closed position, but also drooped or sagged between the vanes when the blind mechanism was drawn to an open position. Further, direct connecting of the cord or bead chain to the vanes also limited the maximum possible angular rotation of the vanes so that it was difficult to rotate the vanes through a full 180.degree. as is desirable for complete light control by the vanes.

Prior vertical blind mechanisms have utilized a header having a slot along the bottom of the header with the vane supports mounted in the slot for movement along the header. However, when the slot is at the bottom of the header, the slot and some of the blind operating mechanism as well as the undecorated interior of the header is exposed to view from the room side of the blind mechanism. In addition, the operating cords for the traverse mechanism sometime droop into and through the downwardly opening slot in the header.

It is an object of the present invention to provide a vertical venetian blind mechanism in which the vanes are mounted for traversing movement along a header and for rotary movement about an upright axis for light control, and which has an improved blind operating mechanism for rotating the vanes and controlling the spacing between adjacent vanes.

Another object of this invention is to provide a vertical venetian blind in accordance with the foregoing object in which rotation of all of the vanes can be readily synchronized and which effectively avoids damage to the blind operating mechanism in the event one or more vanes are obstructed during rotation of the vanes.

Another object of this invention is to provide a vertical blind mechanism which can be adjusted in length to accommodate windows of different widths.

A further object of this invention is to provide a vertical blind mechanism in which the operating slot for the vane carriers and the operating mechanism for the blind is effectively concealed from view from the room side of the blind.

Yet another object of this invention is to provide a vertical blind mechanism in which the vanes are mounted on vane carriers for traversing movement along a header and also for rotary movement about an upright axis for light control, and in which the spacing of at least one vane carrier relative to an adjacent vane carrier can be readily adjusted after the vane carriers and operating mechanism are assembled on the header.

Still another object of this invention is to provide a vertical blind assembly in which the vanes are mounted on vane carriers for rotary movement about an upright axis and for traversing movement along a header between a folded condition adjacent one end of the header and an extended position spaced apart along the header, and which has an improved arrangement for releasably latching the vane carriers in extended position on the header.

These, together with other objects and advantages of this invention, will be more readily understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary exploded perspective view of a vertical blind mechanism, arranged for left-hand operation (as viewed from the front of the rod);

FIG. 2 is a horizontal sectional view through the vertical blind mechanism, with the traverse and operating cords arranged for right-hand operation (as viewed from the front of the rod);

FIG. 3 is a rear elevational view of the vertical blind mechanism of FIG. 2;

FIG. 4 is a longitudinal sectional view taken on the plane 4--4 of FIG. 2;

FIG. 5 is a fragmentary longitudinal sectional view taken on the plane 5--5 of FIG. 2 and showing parts of the lead carrier in a moved position and on a larger scale than FIG. 2;

FIG. 6 is a fragmentary longitudinal sectional view taken on the plane 6--6 of FIG. 2 and illustrating parts of the lead carrier in still another moved position and on a larger scale than FIG. 2;

FIG. 7 is a transverse sectional view taken on the plane 7--7 of the FIG. 2;

FIG. 8 is a transverse sectional view taken on the plane 8--8 of FIG. 2 and illustrating the parts on a larger scale than FIG. 2;

FIG. 9 is a fragmentary horizontal sectional view taken on the plane 9--9 of FIG. 8;

FIG. 10 is an exploded perspective view of one of the vane carriers;

FIG. 11 is a transverse sectional view taken on the plane 11--11 of FIG. 2 and showing the parts on a larger scale than FIG. 2; and

FIG. 12 is a fragmentary vertical sectional view taken on the plane 12--12 of FIG. 2 and illustrating parts in a moved position and on a larger scale than FIG. 2.

The vertical blind mechanism includes a header rod H adapted to be mounted as by brackets (not shown) on a support surface to extend horizontally across a window opening and rod end caps C.sub.1 and C.sub.2 at opposite ends of the header rod. A plurality of auxiliary carriers AC are mounted on the rod for traversing movement therealong and a vane support VS is mounted on each auxiliary carrier for turning movement about an upright axis to rotate a vane V supported by each vane support. A lead carrier LC is also mounted on the rod for traversing movement therealong and is extended and retracted by means of a traverse cord TC that extends lengthwise of the rod. A flexible operating chain OC is operatively connected to a lead carrier LC and has first and second chain portions OC.sub.1 and OC.sub.2 extending lengthwise of the rod and engaging vane drive sprockets on each of the auxiliary carriers to control spacing between the auxiliary carriers when the lead carriage is extended to close the blind, and to control rotation of the vane supports when the first and second chain sections are moved relative to each other. The traverse cord TC and operating chain OC are operated from adjacent one end of the rod and a latch mechanism LM is provided for releasably latching the lead carrier to the other end of the rod to releasably hold the blind in its closed position.

It is sometimes desirable to be able to adjust the length of the header rod at the time of installation to accommodate windows of different widths and, for this purpose the rod H is advantageously formed in inner and outer telescopically adjustable rod sections H.sub.1 and H.sub.2. In the preferred embodiment illustrated, the trackway is formed at the rear side of the rod so as to be concealed from view at the front and bottom of the rod. The inner and outer rod sections H.sub.1 and H.sub.2 have a like configuration except that the inner rod section has a slightly smaller cross-section than the outer rod section to be telescopically receivable therein, and like numerals are used to designate corresponding parts of the inner and outer rod sections. More specifically, the outer and inner rod sections each include a top wall 21, a front wall 22, a bottom wall 23, and upper and lower rear wall portions 24 and 25 that are spaced apart to define a slot S. The auxiliary carriers AC each include a slide body 31 that extends through the slot S in the rod sections. The slide bodies are formed of a resilient wear resisting synthetic resin material and may, for example, be formed of an acetal resin. As best shown in FIG. 8, each slide body has an upper groove with laterally spaced inner and outer upper guide walls 32a 32b and a lower groove with laterally spaced inner and outer lower guide walls 33a and 33b arranged to guide the auxiliary carrier along the upper and lower rear rod wall portions 24 and 25. A vane support VS is rotatably supported on each of the slide bodies 31 rearwardly of the header rod for rotation about an upright axis and has a shaft portion 38a and a lower vane engaging portion 38b. The vane supports VS are of a synthetic resin material which is preferably transparent and may, for example, be formed of a transparent polycarbonate resin. In order to facilitate assembly and also disassembly for replacement of the vane supports, the slide bodies 31 are formed with a semicylindrical sleeve portion 31a that extends through slightly greater than 180.degree. and adapted to rotatably receive the generally upright shaft portion 38a of a vane support with a snap fit.

A drive shaft 41 is mounted in a bore 31b in each slide body for rotation about a generally horizontal axis transverse to the rear wall of the rod and a right angle gear drive connects the outer end portion of the drive shaft to the vane support. The drive shaft is conveniently formed of a synthetic resin material which may, for example be an acetal resin. As best shown in FIGS. 8 and 9, the right angle drive shaft includes a worm gear 42 formed integrally with the outer end of the drive shaft 41 and which meshes with a worm wheel 43 conveniently formed integrally with the upper end of the shaft 38a on the vane support. The gear drive is advantageously arranged to effect a speed reduction between shaft 41 and vane support VS to enable more accurate control of the angular position of the vane support and to also reduce the tension on the operating chain OC required to rotate the vane supports on all of the auxiliary carriers. For example, the worm and worm wheel drive shown provides about an eight to one speed reduction, so that four revolutions of the shaft 41 turn the vane support through 180.degree.. A sprocket 45 is provided on the inner end of the drive shaft on each auxiliary carrier for rotating the drive shaft and chain retainer guides 31c and 31d are provided on the slide body to guidably retain the first and second runs OC.sub.1 and OC.sub.2 of the operating chain in meshing engagement with the associated sprocket at diametrically opposite sides of the sprocket. The sprocket has a flange 45b at one side and the chain retainer guides 31c and 31d have a portion extending along the side of the sprocket opposite the flange 45b and a portion spaced outwardly from the periphery of the sprocket at diametrically opposite sides thereof for retaining the bead chain in meshing engagement with the sprocket. A slip clutch is advantageously provided in the drive between the sprocket and the vane support to prevent damage to parts in the event one or more of the vanes engages an obstruction during rotation and to also enable synchronization of the vanes on the several auxiliary carriers. The slip clutch is provided between the sprocket 45 and the drive shaft 41 and, as best shown in FIG. 10, the sprocket is provided with a non-circular opening 45c, conveniently square in cross-section, and the drive shaft 41 is provided with a radially compressible portion 41b that extends into the opening 45c in the sprocket and which has a protrusion 41c engageable with the noncircular opening 45c in the sprocket. The shaft 41 is formed of a resilient plastic material and the radially compressible portion 41b is provided by a diametrical slot 41d in the shaft. The protuberance 41c is provided on the outer periphery of the shaft at a location intermediate the ends of the slot and normally extends into a corner of the non-circular opening 45c so that the shaft normally rotates with the sprocket, but can yield in the event rotation of the shaft is restricted. Locating lugs 41e and 41f are also provided on the outer periphery shaft in the diametrically compressible portion of the shaft and, as best shown in FIG. 8, one end of each of the lugs is beveled or inclined to facilitate insertion of the shaft through the bore 31b in the slide and through the opening 45c in the sprocket. The lug 41e is provided at a location on the shaft to engage the inner side of the slide body 31 to inhibit axial withdrawal of the shaft, and the lug 41f is provided at a location to engage the inner side of the sprocket to axially retain the sprocket on the shaft. With this arrangement, the shaft can be pressed through the bore 31b in the slide body 31 and through the non-circular opening 45c in the sprocket to assemble the drive gear worm and sprocket on the slide body. A lug 38c is provided on the shaft portion 38a of the vane support VS and arranged to engage stops 31f and 31g on the sleeve 31a to limit angular movement of the vane support. These stops are angularly spaced apart with relation to the lug 38c so that the vane can rotate through slightly greater 180.degree. to assure full closing of the vanes in either of two oppositely rotated positions.

The chain retainer guides 31c and 31d on each carrier normally maintain the first and second portions of the chains in meshing engagement with the respective sprockets at diametrically opposite sides and maintain a preset spacing of the auxiliary carriers along the chains. There are some occasions, for example when adjusting the length of the rod, that it is desirable to adjust the spacing between one or more auxiliary carriers. For this purpose, provision is made for disengaging the sprocket on one or more of the auxiliary carriers from the bead chains to allow adjustment of the spacing between the auxiliary carriers after the rod is assembled. As best shown in FIGS. 8 and 9, the slide body is formed with a bore 31h arranged to permit limited axial movement of the shaft 41 and worm 42 in a direction inwardly of the rod, that is to the left as viewed in FIGS. 8 and 9. A means is provided to releasably retain the shaft in the position shown in FIGS. 8 and 9, in which the sprocket is in meshing engagement with the chain. In the preferred embodiment shown, rounded protuberances 41 g are provided on the shaft 41 at a location to engage the inner end of the bore 31h and normally maintain the shaft and sprocket to the position shown in FIGS. 8 and 9. The shaft 41 is formed with a diametrically extending slot 41h so as to be radially compressible in the region adjacent the protuberances 41g. With this arrangement, the shaft can be pressed axially inwardly from the position shown in FIGS. 8 and 9 to disengage a sprocket from the bead chain, for example by either pressing on the outer end of the worm gear or by manually turning the vane carrier in a counterclockwise direction as viewed in FIG. 9. Thus, the sprocket can be shifted axially inwardly relative to the chain retainer guides 31c and 31d to allow the bead chain to disengage from the sprocket so that the auxiliary carrier can be manually moved axially along the rod until the desired spacing relative to an adjacent auxiliary carrier is achieved. The sprocket is thereafter moved axially outwardly, as by applying torque on the vane support in a clockwise direction as viewed in FIG. 9, to re-engage the sprocket with the portions OC.sub.1 and OC.sub.2 of the bead chain.

In the adjustable rod using telescoping rod sections, the slide bodies must not only be adapted for sliding on the inner rod section or the outer rod section, but also where the two rod sections overlap as shown in FIG. 8. The guide walls 32a, 32b and 33a, 33b diverge outwardly from their bases at a shallow angle of the order of 5.degree. and, in order to allow free movement of the slide bodies along the overlapping portions of the inner and outer rods, the spacing between the guide walls 32a, 32b and 33a, 33b is made substantially greater than the combined thickness of the upper and rear wall portions of the rod along opposite sides of the slot. In order to maintain the axis of the vane supports substantially vertical when the slides are in the overlapping portions of the rod sections H.sub.1 and H.sub.2, the upper inner guide wall 32a that engages the inside of the upper rear wall portion 24 is offset from the lower outer guide wall 33b that engages the outside of the lower rear wall portion 25 a distance slightly greater than twice the combined thickness of the overlapping rear wall portion of the rod. In order to maintain the vane support axis generally upright when the slides are supported on a single rod section such as an inner rod section H.sub.1 or the outer rod section H.sub.2, a lengthwise extending recess 33c (FIG. 8) is provided in the base of the lower groove in the slide body. The recess 33c has a width less than the combined thickness of overlapping lower rear wall portions of rod sections H.sub.1 and H.sub.2 to receive and ride on the upper edge of only a single rear wall portion. The lower recess is located laterally on the slide in relation to the upper guide edge 32a that engages the inner side of the upper rod wall portion to support the slide body on a single rod section H.sub.1 or H.sub.2 with the vane axis substantially vertical. Since the transverse width of the groove 33c is less than the combined thickness of the lower rear wall portions of the overlapping rod sections, the lower rear wall portions of the overlapping rod sections do not extend into the recess but instead ride on the base of the lower guide groove.

The master carrier LC comprises a slide body 55 having upper and lower grooves 55a and 55b for receiving the upper and lower rear wall portions 24 and 25 of the rod sections, to guide the lead carrier for movement along the rod. The lead carrier is moved along the rod by the traverse cord TC and the end caps C.sub.1 and C.sub.2 are constructed and arranged to provide cord guides for the traverse cord. The end caps C.sub.1 and C.sub.2 are of like construction, except that the end cap C.sub.1 is dimensioned for reception in the end of the inner rod section H.sub.1 and the end cap C.sub.2 is dimensioned for reception in the end of the outer rod section H.sub.2, and the like numerals are used to designate corresponding parts of the end caps C.sub.1 and C.sub.2. The end caps are conveniently molded in one piece of a synthetic resin material and each include an end wall 61 adapted to overlie the end of the respective rod section and rear wall portions 62 a and 62b adapted to overlie the inside of the rear wall portions 24, 25 at the respective rod section. The rear wall portions 62a and 62b are spaced apart to define a notch 62c therebetween having a width corresponding to the width of the slot S in the rod sections and adapted to be aligned therewith to allow a carrier such as the lead carrier LC to slide from the rod section into the notch 62c, to positively locate the lead carrier in the end cap. In order to accurately locate the upper and lower rear wall portions 24 and 25 of the rod section relative to the rear wall portion 62a and 62b of the end cap, the rear wall portions 24 and 25 of the rod sections are formed with notches 24a and 25a respectively (FIG. 1) that open at one end of the rear wall portions and the wall portions 62a and 62b of the end caps are formed with generally T-shaped ribs 62d and 62e that are adapted to extend into the notches 24a and 25a to control the vertical spacing of the rear wall portion, and to overlie the rear sides of the rear wall portions of the rod adjacent the notches to laterally position the rear wall portions of the rod relative to the rear wall portions of the end cap. A latch 64 is formed on the end of a resilient arm integral with the end wall of the end cap and arranged to project into an opening 21a in the top wall of the respective rod section, to lock the end cap to the respective rod section.

The traverse cord guides on the end caps C.sub.1 and C.sub.2 are best shown in FIGS. 2 and 4 and comprise a pair of rollers 65 and 66 supported for rotation about axes that are vertically and horizontally offset to enable the traverse to be arranged for either right-hand or left-hand draw. The traverse cord TC has one end portion TC.sub.1 connected to the lead carrier LC and arranged to extend therefrom lengthwise of the rod and over the cord guide pulley 65 on the end cap on one end of the rod, and then downwardly to provide a first traverse cord operating portion TC.sub.1a. The traverse cord also has a second portion TC.sub.2 which is also connected to the lead carrier and which extends from the lead carrier lengthwise of the rod over a cord guide pulley 65 at the other end of the rod then in a return run TC.sub.2a lengthwise of the rod and over a cord guide pulley 66 at the first mentioned head of the rod and downwardly to provide a second traverse cord operating portion TC.sub.2b. The operation portions TC.sub.1a and TC.sub.2b of the traverse cord are tensioned as by cord guides and, as will be seen, pulling on one of the traverse cord operating portions TC.sub.1a will move the lead carrier LC in one direction along the rod to an open position, and pulling on the other traverse cord operating portion TC.sub.2b will move the lead carrier in the opposite direction along the rod to a closed position.

An improved cord lock arrangement is provided for adjustably securing one end of the traverse cord to the lead carrier to facilitate adjustment of the length of the traverse cord with adjustments in the length of the header. As best shown in FIGS. 2, 3 and 7, the lead carrier has upper and lower inner cord retainers 55d and 55e on the slide body 55 inside the rod which define a notch 55f therebetween, and a second pair of upper and lower cord retainers 55g and 55h on the slide body outside the rod which define a notch 55j therebetween. The inner and outer upper cord retainers 55d and 55g have upwardly opening generally keyhole shaped notches, and the inner and outer lower cord retainers 55e and 55h have downwardly opening generally keyhole shaped notches. As will be seen from FIG. 7, the keyhole shaped notches have a generally circular base portion dimensioned to snugly receive the traverse cord and a V-shaped outer portion that intersects the circular base portion on a constricted area to allow the traverse cords to be pressed laterally into the notches and retained therein. The end of one of the traverse cord portions TC.sub.1 is connected to the inner retainers and as best shown in FIG. 7, is snapped into the notch in the upper inner cord retainer 55d and then passed downwardly and snapped into the notch on the lower inner cord retainer 55e, with a knot K.sub.1 provided at the end of the traverse cord portion TC.sub.1. The end of the other traverse cord portion TC.sub.2 is passed through the notch 55f between the upper and lower inner cord retainers and laterally outwardly across one end of the slide body 55 and through the notch 55j between the outer cord retainers, and is then looped around the upper and lower outer cord retainers 55g and 55h as shown in FIG. 3 and pressed into the notches therein. As will be seen from FIG. 3, the portion of the end of the traverse cord that passes between the upper and lower outer cord retainers crosses the portion of the traverse cord that passes through the notch 55j, to aid in retaining the traverse cord against detachment from the lead carrier. With this arrangement, the length of the traverse cord can be readily adjusted by merely pulling the end of the traverse cord TC.sub.2 out of the outer cord retainers 55g and 55h and then pulling outwardly on the traverse cord until it is adjusted to the desired length, after which the end is again looped around the upper and lower outer cord retainers and pressed into the notches therein.

The lead carrier LC is also connected to the operating chain OC to draw the auxiliary carriers therewith when the lead carrier is extended to close the blind, and the latch mechanism LM is provided to releasably latch the lead carrier to one of the end caps. The latch mechanism LM comprises a latch member 81 mounted on the lead carrier and a keeper 82 on the end caps. The latch member 81 comprises a latch body that is slidably mounted on the inner side of the lead carrier body 55 for limited movement relative thereto in a direction paralleling the length of the rod. The latch body 81 has an elongated opening extending therethrough defining the laterally spaced side walls 81a, first and second end walls 81b, 81c, as best shown in FIG. 6 and inwardly opening recesses 81d (FIG. 11) in the opposite side walls 81a. The lead carrier 55 has resilient latch retaining lugs 55m extending laterally of the front side of the lead carrier body adapted to be received between the side walls 81a of the opening in the latch body, and flanges 55n on the outer ends of the lugs adapted to extend into the recesses 81d in the latch body as shown in FIG. 11. The lugs 55m have a length in a direction parallel to the length of the header which is short as compared to the length of the opening 81a so that the latch body can slide relative to the lead carrier body in a direction paralleling the length of the rod between a first position in which the first end 81b of the opening engages the lugs 55m as shown in FIG. 5 and a second position in which the second end 81c of the opening engages the lugs 81m as shown in FIG. 6. A guide rib 55p (FIG. 6) is also provided on the forward face of the lead carrier body and arranged to guidably engage the side walls 81a on the latch body, and the end 81c of the latch body is recessed to pass over the rib 55e during movement of the latch body from its first position to its second position. The rib 55p has a length which is long as compared with the transverse width of the slot and guides the latch body for sliding movement and effectively prevents tilting movement of the latch body relative to the slide body until the latch body reaches its second position. The lugs 55m are laterally resilient and, when the body reaches its second position, it can tilt a limited amount relative to the slide body in a direction crosswise of the header, the lugs 55m being laterally compressed during such tilting to resiliently urge the latch member back to a position in which the elongated slot is aligned with the rib 55p.

The latch body is connected to the operating chains in a manner such that tension on the operating chain normally urges the latch body to its first position relative to the lead carrier. As best shown in FIGS. 1 and 11, the latch body has semi-circular inner and outer wall portions 81f and 81g that define an arcuate chain guide groove therebetween for receiving an end loop OCL of the operating chain OC. Latch noses 81h are formed on the ends of the outer wall portion 81g for engagement with the aforementioned keeper 82 on the end cap. The keeper 82 comprises a resilient blade like member having one end formed integrally with the end wall 61 of the end cap. The blade extends generally lengthwise of the rod and has an opening 82a adjacent at the free end adapted to receive a latch nose 81h on the latch body. The blade portion 82 is positioned in the path of travel of the nose portion 81h on the latch body and, when the lead carrier moves into the notch 62c on the end cap, the latch member is in its first position on the lead carrier and the arcuate lead face on the outer wall 81g of the latch member cams the keeper member upwardly until it passes over the nose portion 81h. The tension on the operating chain normally urges the latch body to its first position on the lead carrier and the keeper 82 normally operates to retain the lead carrier in its extended position. However, when the lead carrier is retracted by the traverse cords, the lead carrier moves relative to the latch member until the latch member reaches its second position. At that time, latch member can tilt relative to the lead carrier as shown in FIG. 6 and release engagement with the keeper.

The operating chain has portions OC.sub.1 and OC.sub.2 that extend from the looped end OCL lengthwise of the header to the other end thereof, and provision is made for moving the chain portions OC.sub.1 and OC.sub.2 longitudinally relative to each other to effect rotation of the vane supports. As best shown in FIG. 12, the chain portions OC.sub.1 and OC.sub.2 extend over chain guides 85a and 85b on the end cap to downwardly extending operating portions OC.sub.1a and OC.sub.2a respectively. The chain guides 85a and 85b are vertically and horizontally offset from each other to vertically separate the chain portions OC.sub.1 and OC.sub.2 and to horizontally separate the chain portions OC.sub.1a and OC.sub.2a. The operating portions OC.sub.1a and OC.sub.2a are conveniently connected in a loop by a bead chain connect to prevent pulling of one end of the operating chain out of the rod. As previously described, the auxiliary carriers are connected to the chain portions OC.sub.1 and OC.sub.2 at spaced locations therealong corresponding to the desired spacing between the centers of adjacent vane and, when the lead carrier LC is moved from an open position adjacent one end of the rod to a closed position adjacent the opposite end of the rod, it draws the looped end OCL of the bead chain therewith and pulls the auxiliary carriers along the rod while controlling the maximum spacing between adjacent auxiliary carriers. When the lead carrier is latched to the end cap in the closed position of the blind, pulling on one or the other operating portions OC.sub.1a or OC.sub.2a of the chain will move the chain portions OC.sub.1 and OC.sub.2 in relatively opposite directions and rotate the vane supports accordingly.

When the blind is in an open condition, the operating portions OC.sub.1 and OC.sub.2 of the bead chain form loops between adjacent carriers. If the operating portions of the bead chain OC.sub.1a or OC.sub.2a are pulled when the blind is in a partially or fully opened condition, the slack loops in the chain portions OC.sub.1 and OC.sub.2 sometimes become entangled or looped around other parts.

In accordance with the invention of Mark J. Terlecke, claimed in the copending application Ser. No. 061,380,033, filed May 20, 1982, and assigned to the assignee of the present application, a chain locking device 91 is provided for locking the chain portions OC.sub.1 and OC.sub.2 against longitudinal movement when the carriers are retracted to open the blind. The locking device 91 comprises a body having a chain guide passage means 91a therein for guidably engaging the first and second chain portions for movement in relatively opposite directions. In the embodiment illustrated, the locking device is in the form of a sleeve having a single guide passage for both the first and second chain portions, with the internal opening in the sleeve sufficiently greater than twice the cross-section of the bead chain to allow the chain portions OC.sub.1 and OC.sub.2 to pass in relatively opposite directions therethrough. The sleeve can have a circular cross-section as shown or an oblate cross-section, if desired. It is also contemplated, that separate guide passages could be provided in the device 91 for the chain portions OC.sub.1 and OC.sub.2. In order to facilitate guiding of the chain portions longitudinally therethrough, the guide passage means has a length somewhat greater than the pitch of the beads along the chain. The chain guide passage means is arranged to maintain the first and second chain portions passing therethrough spaced apart a distance substantially less than the pitch diameter of the sprockets on the auxiliary carriers to lock the first and second chain portions to the sprocket on an auxiliary carrier, when that carrier is retracted into engagement with the chain locking device. The chain locking device is preferably arranged to engage the chain portions OC.sub.1 and OC.sub.2 at a location adjacent one end cap such as to engage the sprocket on the adjacent end auxiliary carrier. However, it is contemplated that the chain locking device could also be arranged to engage the chain portions OC.sub.1 and OC.sub.2 at other locations intermediate adjacent ones of the auxiliary carriers. The locking device is conveniently arranged so that it is supported solely by the chain portions OC.sub. 1 and OC.sub.2. However, it is also contemplated that the locking device could be supported on the end cap, provided it guides the chain portions OC.sub.1 and OC.sub.2 in the manner described above. When the locking device is located adjacent one end cap, a stop or shoulder 95 on the end cap engages one end of the locking device and limits movement of the locking device during retraction of the carriers. Thus, as the carriers are retracted, the sprocket on the adjacent end carrier in the rod moves to a position adjacent the other end of the locking device. If one or the other of the operation portions OC.sub.1a or OC.sub.2a of the chain is pulled while the carriers are retracted, the locking device 91 draws the chain portions OC.sub.1 and OC.sub.2 part way around the periphery of the sprocket on the adjacent auxiliary carrier to lock the chain portions to that sprocket and lock that sprocket against rotation. As will be seen from FIG. 12, the end 91b of the chain locking device adjacent the sprocket is preferably sufficiently thin to extend into the space between adjacent beads when the chain portions extend transverse to the end 91b, as occurs when a sprocket is closely adjacent the end 91b.

The chain locking device not only operates to lock the chain portions OC.sub.1 and OC.sub.2 when the auxiliary carriers are fully retracted, but it also provides a chain locking function when the lead carrier is not locked in its extended position. If the lead carrier is not locked in its extended position, a pull on one or other of the chain operating portions OC.sub.1a or OC.sub.2a will tend to retract the auxiliary carriers until the end auxiliary carrier engages the locking device. When the lead carrier is locked in its extended position on the rod, the chain portions OC.sub.1 and OC.sub.2 pull the end auxiliary carrier away from the locking device and the chain portions can then pass relatively free through the chain guide passages.

From the foregoing it is thought that the construction and operation of the vertical blind mechanism would be readily understood. The sprocket on one auxiliary carrier is assembled onto the drive shaft and onto the portions OC.sub.1 and OC.sub.2 of the operating chain at a location spaced from the loop portion OCL of the chain to provide the desired spacing of that auxiliary carrier and the vane supported thereby from one end of the rod, when the lead carrier is latched to the end cap on that end of the rod, and the sprockets are assembled on the other auxiliary carriers and on the portions OC.sub.1 and OC.sub.2 of the bead chain at spaced locations therealong corresponding to the desired spacing of adjacent vanes along the rod. The number of auxiliary carriers varies with the overall length of the rod and in the adjustable header construction shown, it is contemplated that auxiliary carriers can be removed from the bead chain if the header is shortened. In some installations, for example if the header is shortened a distance less than the spacing between the auxiliary carriers or a multiple thereof, then one or more of the auxiliary carriers can be adjusted along the bead chain while the carrier is assembled on the rod. This is achieved by shifting the drive shaft 41 on the auxiliary carrier axially to disengage the sprocket from the bead chain, followed by shifting of the carrier along the rod and re-engagement with the sprocket with the bead chain. The blind mechanism can be opened and closed by operating the traverse cords TC which moves the lead carrier along the rod between an open position adjacent one end of the rod to a closed position adjacent the other end of of the rod. The latch mechanism LM on the lead carrier engages a keeper on the end housing to releasably latch the lead carrier in a closed position. When the lead carrier is moved along the rod to a closed position, the looped end OC.sub.1 of the operating chain is drawn with the lead carrier and this pulls the auxiliary carriers along the rod and controls the spacing between adjacent ones of the auxiliary carriers. When the lead carrier is in its closed position latched to the end cap on one end of the rod, the operating portions OC.sub.1a and OC.sub.2a of the operating chain can be drawn to move the chain portions OC.sub.1 and OC.sub.2 longitudinally in relatively opposite directions to drive the sprockets and rotate the vane supports. The slip clutch between the sprocket and the drive shaft in conjunction with the rotation stops on the vane supports, enables rotation of all of the vane supports on the rod to be synchronized by pulling the operating chain in one direction until all of the vane supports engage the rotation stop. The speed reducing drive between the sprocket and vane supports provides a very accurate angular adjustment of the vane supports and further reduces the force required to pull the operating chain. Opening of the blind is effected by pulling on the draw cord in a direction to move the lead carrier away from the end of the rod. The latch member remains in engagement with the keeper 82 until the lead carrier moves relative to the latch member to its second position relative to the lead carrier at which time the latch member can tilt relative to the lead carrier and disengage the keeper. Continued movement of the lead carrier along the rod causes the head carrier to push the auxiliary carriers together and toward the other end of the rod to an open position. When the blind is in an open condition, operation of the operating chain is effectively prevented by the locking device 91. Location of the slot at the rear side of the rod conceals the slot and the internal blind operating mechanism from view from the front or under side of the rod. Further, with the slot located at the rear of the rod, the bottom wall of the rod underlies and supports the operating chain and traverse cord, even when there are slack loops in the chain as occurs when the blind is open.