Patent Publication Number: US-6213188-B1

Title: Cord control device for a venetian blind to control raising and lowering of the slats

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a control device, more particularly to a cord control device for a Venetian blind to control raising and lowering of the slats. 
     DESCRIPTION OF THE RELATED ART 
     Referring to FIG. 1, a conventional Venetian blind includes an elongated housing  1 , a horizontally disposed shaft  2  journalled in the housing  1 , a plurality of slats  5  suspended one above another from the housing  1 , a bottom rail  7  disposed below the slats  5 , a pair of pulleys  3  provided on two end portions of the shaft  2 , a cord control unit  8  provided at one end of the housing  1 , and two pairs of tilting cords  4 . Each of the tilting cords  4  is disposed at a longitudinal side of each of the slats  5 , and has a top end secured to one of the pulleys  3  and a bottom end secured to the bottom rail  7  so that rotation of the shaft  2  can cause the tilting cords  4  to move up and down in order to tilt the slats  5 . Each of the slats  5  has two end portions, each of which is formed with a through hole ( 5   a ). Each of two pull cords  6  has a first end passing through the vertically aligned through holes ( 5   a ) formed in the slats  5  and secured to the bottom rail  7 , and a second end passing through the housing  1  and the cord control unit  8  and extending out of the housing  1 . 
     Referring to FIG. 2, the cord control unit  8  is shown to include a stationary roller ( 8   a ) and a movable pinion ( 8   b ). The pull cords  6  pass between the stationary roller ( 8   a ) and the movable pinion ( 8   b ), and are operable to move the movable pinion ( 8   b ) toward the stationary roller ( 8   a ) so as to lock the pull cords  6  and so as to position the slats  5 , or away from the stationary roller ( 8   a ) so as to release the pull cords  6  and to permit raising or lowering of the slats  5 . 
     The aforesaid conventional Venetian blind achieves the purposes of raising and lowering the slats  5 . However, the cord control unit  8  has to be mounted at one end of the top housing  1 , thereby restricting the moving space of the pull cords  6  with respect to the side wall adjacent to said end of the top housing  1  and resulting in inconvenience when operating the pull cords  6 . 
     Furthermore, in case the horizontal length of the top housing  1  in the conventional Venetian blind is over sized and does not correspond to the size of a window to which the blind is applied, the top housing  1  has to be cut short. However, the top housing  1  cannot be cut short at two ends thereof in order to achieve the required length due to the presence of the cord control unit  8  at one of the ends thereof. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of this invention is to provide a cord control device which is adapted be mounted in a Venetian blind and which is clear of the aforesaid disadvantages that result from the use of the conventional Venetian blind. 
     Accordingly, the cord control device of the present invention is used in a Venetian blind which includes an elongated horizontal top housing, a plurality of horizontal slats suspended downwardly from the top housing one above another, a bottom rail disposed below the slats, a pair of pulleys disposed spacedly in the top housing, and at least one first control cord and at least one second control cord. Each of the control cords passes through the top housing and through the slats, and has a first end portion fastened to the bottom rail, and a second end portion which extends out of the top housing. The cord control device includes a hollow mounting seat adapted to be mounted removably in the top housing between the pulleys, and having a bottom end, a top end, a roller-mounting space between the top and bottom ends, and an elongated rack disposed in the roller-mounting space. A pair of stationary rollers are journalled in the roller-mounting space one above the other proximate to the elongated rack. The first control cord is adapted to pass slidably over a lower one of the stationary rollers while the second control cord is adapted to pass slidably over and between the stationary rollers. A movable pinion is disposed movably in the roller-mounting space, and is adapted to be passed slidably over by the second end portions of the first and second control cords. The pinion is movable to a first position by virtue of swinging action of the first and second control cords in a first direction, where the control cords can slide over the pinion to permit raising and lowering of the slats, and a second position by virtue of swinging action of the first and second control cords in a second direction opposite to the first direction, where the pinion is clamped between the rack and one of the stationary rollers so that the control cords are adapted to be clamped between the pinion and the respective one of the stationary rollers, thereby preventing raising and lowering of the slats. A stop unit is provided to prevent removal of the pinion from the roller-mounting space in the mounting seat. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of this invention will become more apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a conventional Venetian blind provided with a cord control device for raising and lowering of the slats; 
     FIG. 2 is a fragmentary sectional view of the conventional Venetian blind, illustrating how the cord control device is mounted therein; 
     FIG. 3 a perspective view of a Venetian blind provided with the preferred embodiment of a cord control device of the present invention for raising and lowering of the slats; 
     FIG. 4 is a fragmentary sectional view of the Venetian blind, illustrating how the preferred embodiment of the present invention is mounted therein; 
     FIG. 5 is a fragmentary sectional view of the Venetian blind, illustrating how the preferred embodiment of the present invention is actuated in order to move the slats vertically; and 
     FIG. 6 is a fragmentary sectional view of the Venetian blind, illustrating how a modified cord control device of the present invention is mounted therein. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiment of a cord control device  10  of the present invention is adapted to be mounted on a Venetian blind, as best shown in FIG.  3 . The Venetian blind generally includes an elongated horizontal top housing  100 , a plurality of horizontal slats  120  suspended from the top housing  100  one above another, a bottom rail  130  disposed below the slats  120 , a pair of pulleys  140  disposed spacedly in the top housing  100 , and first and second control cords  110 ′, 110 . Each of the control cords  110 ′, 110  passes through the top housing  100  and through the slats  120 , and has a first end portion fastened to the bottom rail  130 , and a second end portion which extends out of the top housing  100  in a conventional manner. 
     Referring to FIGS. 4 and 5, the cord control device  10  of the present invention includes a hollow mounting seat  11  adapted to be mounted removably in the top housing  100  (see FIG. 3) between the pulleys  140 , and having a bottom end, a top end, a roller-mounting space  111  between the top and bottom ends, and an elongated rack  112  disposed in the roller-mounting space  111 . As to the mounting of the pulleys  140  in the top housing  100  is not pertinent to the present invention, a detailed description thereof is omitted herein for the sake of brevity. 
     A pair of stationary rollers  12 ,  13  are journalled in the roller-mounting space  111  in the seat  11  one above the other proximate to the elongated rack  112  such that the second end portion of the first control cord  110 ′ is adapted to pass over a lower one of the stationary rollers  13 , 12 , and such that the second end portion of the second control cord  110  is adapted to pass slidably over and between the stationary rollers  12 ,  13 . 
     A movable pinion  14  is disposed movably in the roller-mounting space  111  of the seat  11 , and is adapted to be passed slidably over by the second end portions of the first and second control cords  110 ′,  110 . The pinion  14  is movable to a first position by virtue of swinging action of the control cords  110 ′,  110  in a first direction, as best shown in FIG. 5, where the control cords  110 ′,  110  can slide over the pinion  14  to permit raising and lowering of the slats  130  (see FIG.  3 ), and a second position by virtue of swinging action of the control cords  110 ′,  110  in a second direction opposite to the first direction, where the pinion  14  is clamped between the rack  112  and the lower one of the stationary rollers  12 ,  13  so that the first and second control cords  110 ′, 110  are adapted to be clamped between the pinion  14  and the respective stationary roller  13 , thereby preventing raising and lowering of the slats  130 . 
     A stop unit is provided to prevent removal of the pinion  14  from the roller-mounting space  111  of the mounting seat  11 . 
     In the preferred embodiment, the mounting seat  11  is press-fitted in the top housing  100 , and further has two mounting holes  113  that are formed therethrough adjacent to the bottom end of the seat  11  and that are located on two sides of the pinion  14 . The stop unit includes an elongated rigid stop bar  114  disposed directly under the pinion  14 , and has two opposite ends which extend through the mounting holes  113  in the mounting seat  11  and which extend to positions that are located directly over portions  102  of the top housing  100 , in which the mounting seat  1  is press-fitted. Under such a condition, the pinion  14  is confined within a space that is located between the rack  112  and the control cords  110 ′, 110  and over the stop bar  114 . The stop bar  114  prevents removal of the pinion  14  from the roller-mounting space  111 . 
     Referring to FIG. 6, a modified preferred embodiment is shown to be similar to that of the previous embodiment in structure, except that the mounting seat  11  is press-fitted at one end portion of the top housing  100 . Under such a condition, the control cords  110 ′,  110  are passed slidably over either one the stationary rollers  12 ,  13  prior to being passed slidably over the pinion  14 . 
     Since the cord control device  10  of the present invention is disposed in the top housing  100  between two pulleys  140 , in the case that the horizontal length of the top housing  100  is over sized and does not correspond to the size of a window to which the blind is applied, the top housing  100  can be shortened by cutting at two ends thereof in order to achieve the required length. 
     With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated in the appended claims.