Patent Publication Number: US-7216688-B2

Title: Reverse-stop mechanism of curtain

Description:
BACKGROUND OF THE INVENTION 
   (a) Field of the Invention 
   The present invention relates to a reverse-stop mechanism of a curtain, and more particularly to an application to a vertical or horizontal type curtain that stops transmitting a reverse force, caused by gravitation or an external force, and also outputs varied powers through differential speeds formed by different pitch circle diameters of gears. 
   (b) Description of the Prior Art 
   Referring to  FIG. 1 . To enable a reverse-stop mechanism, a drive assembly  12  is formed in a conventional curtain  1 . 
   Referring to  FIG. 2 . The drive assembly  12  is driven by operating a bead-chain  121  to rotate a chain wheel  126 , which enabling a worm  125  to drive a worm wheel  124 . Besides manual operation to provide a rotation force, an electric motor can be used to replace the chain wheel  126 . 
   Referring to  FIGS. 1 and 2 . Through a transmission stick  122 , the drive assembly  12  drives wire-collecting tubes  123 , which wind up or down curtain sheets  14  through wires  141 . Adjustment of angles of curtain sheets  14  is made by overturn plates  13  to move wires  142 . 
   When blowing by wind, the curtain sheet  14  may slip downwards, transmitting a power through wire-collecting tubes  123  and the transmission stick  122  to slip the drive assembly  12 . 
   The structure shown in  FIG. 2  can be a better design till now. While the worm wheel  124 , being formed inside the upper horizontal block  11 , is slim and small and while the engaging force on the worm wheel  124  is limited to a face of a cog, damages can easily occur on the cog of the worm wheel  124  or the worm  125 , thereby causing a slip and even losing locking capability. 
   The drive assembly  12  can also be applied to a cloth-curtain, which suffers similar wind pressure and self-weight effect, thereby necessitating a reverse-stop function to stop slipping. 
   Referring to  FIGS. 3 and 3A . A horizontal type curtain includes a wire  140 , an adjustment stick  120 , and an upper horizontal block  11  connecting with a curtain sheet  14 , which can be wound up or down by operating the wire  140 . By operating the adjustment stick  120  to rotate a worm  125 , a worm wheel  124 , and a transmission stick  122 , an angle of the curtain sheet  14  thereby being adjusted. With the worm  125  gearing the worm wheel  124 , the transmission stick  122  thereby being able to resist an external or a self-weight force. 
   While the curtain can be as high as 30 meters, the adjustment stick  120  can&#39;t be that long, due to a packing size constraint, thereby, instead of using the adjustment stick  120 , a chain wheel is used. 
   Referring to  FIG. 4 . As far as the chain wheel is concerned, a conventional design is to operate a bead-chain  121  to rotate a chain wheel  126  and other drive elements in a direction of the transmission stick  122  through a planet gear set  18 . Driving by the chain wheel  126 , a sun gear  181  will rotate to drive a planet gear  182  rotating round a fixed annular gear  183 , which rotates a wheel disk  180  to drive a shaft  190  connecting to a main thrust shaft  191  through a stop spring  192 , thereby enabling the main thrust shaft  191  to drive the transmission stick  122 . The stop spring  192  can be de-compressed, when a force from the shaft  190 , or compressed to stop transmitting a rotation when a force from the main thrust shaft  191 , thereby forming a reverse-stop function. 
   The stop spring  192  is locked on an end and the de-compression is achieved when a shrinking of the diameter of the spring  192  is made by an external twisting force from the main thrust shaft  191 . The design of the stop spring  192  is common in conventional curtains, thereby no further discussion regarding this subject. 
   The design in  FIG. 4  can also be applied to drive structures in  FIG. 1  such that by pulling the bead-chain  121  to enable the curtain sheet to wind up or down and also adjust incoming light angles. 
   With a force by pulling the bead-chain  121  or by wind pressure or self-weight effect in an opposite direction, the stop spring  192  will be de-compressed or compressed, thereby enabling the curtain being wound up or down or adjusted for different light incoming angles or enabling a reverse-stop mechanism. While the compression force and the outer perimeter of the shaft  190  exceeds limits, slipping and losing the reverse-stop capability can be happened. 
   Referring to  FIG. 5 . A conventional vertical type curtain includes a drive assembly  12 , driven manually by a wire  16 , formed on an upper horizontal block  11 , wherein curtain sheets  14  suspended through suspension shafts  15 . 
   Referring to  FIG. 6 . Curtain sheets  14  can be operated through a suspension shaft  15  connecting with a bevel wedge gear  17 , to be driven by the drive assembly  12  in order to rotate a transmission stick  171 . 
   When driven by the drive assembly  12 , the bevel wedge gear  17  rotates suspension shafts  15  to alter different incoming light angles of curtain sheets. To prevent a wind pressure from causing a reverse driven force transmitting to the drive assembly  12 , a structure similar to that in  FIG. 2  is formed. As a result, cogs of the worm gear can be damaged, causing a slip and losing reverse-stop capability. 
   In recent years, other reverse-stop designs were developed, such as using an electromagnetic control switch or other electric automatic devices. As a result, defects can be relaying upon a power supply and also complex in structure. 
   SUMMARY OF THE INVENTION 
   It is an objective of the present invention to form a reverse-stop mechanism by connecting a fastened first annular gear with a secondary annular gear of a larger pitch circle diameter, wherein a compound gear set formed in the middle gearing both annular gears thereof, thereby a backwards rotation of the secondary annular gear will be transmitted, through the compound gear set, to the first annular gear, which stops the rotation. With different pitch circle diameters of the first and the secondary annular gear, power outputs will be transferred to varied speeds. 
   It is another objective of the present invention to enable the drive assembly to drive directly the compound gear set through a rotary disk. 
   It is yet another objective of the present invention to enable the secondary annular gear being fitted in a fixing disk formed on a base. 
   To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  shows a perspective view of a conventional horizontal type curtain. 
       FIG. 2  shows a perspective view of a conventional drive assembly. 
       FIG. 3  shows a perspective view of another conventional horizontal type curtain. 
       FIG. 3A  shows an enlarged view of  FIG. 3 . 
       FIG. 4  shows a perspective view of a conventional curtain being driven by pulling a bead-chain. 
       FIG. 5  shows a perspective view of a conventional vertical type curtain. 
       FIG. 6  shows a perspective view of an angle adjustment structure of a conventional vertical type curtain. 
       FIG. 7  shows a perspective view of a driving mechanism of the present invention. 
       FIG. 8  shows a perspective view of the driving mechanism of anther application of the present invention. 
       FIG. 9  shows a perspective view of an electric driven mechanism of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 7 . The present invention is to use a drive assembly  2  through a differential gear set to drive a transmission shaft  7  and also form a reverse-stop mechanism when having a reverse force from the transmission shaft  7 , thereby preventing curtain sheets from slipping or altering incoming light angles. 
   The present invention is to utilize the drive assembly  2  to drive a compound gear set  3 , a secondary annular gear  5 , a shaft connector  51 , and the transmission shaft  7  inserted in a plug-in hole  53 , thereby enabling curtain sheets to be wound up or down or to be adjusted angles of the curtain sheet. On the contrary, a reverse force from a transmission shaft  7  will be transmitted through the compound gear set  3  to a first annular gear  4 , which stops the rotation, thereby achieving a rigid reverse-stop mechanism. 
   The compound gear set can be a planet gear set such as an eccentric planet gear set in this example, which includes the first annular gear  4  fastened by a fixture  61  fixed on a case  6 , the secondary annular gear  5  fitted in the case  6  in any feasible way, and the compound gear set  3  formed in the middle, wherein the compound gear set  3  includes a first planet gear  32  connecting with a secondary planet gear  33  by a shaft  30  to form an united body eccentrically connecting with a rotary disk  31 . 
   A structure of planet gear set as recited above, wherein the secondary annular gear  5  connects through a fixing disk  52 , being restrained in X-, Y-, and Z-direction movements by a base  62 , to the shaft connector  51  engaging with the shaft  7 , thereby an axial force from the shaft  7 , which is common in conventional curtains, will be blocked at the fixing disk  52  without being able to transmit further. 
   With the compound gear set  3  comprising of the first planet gear  32  co-axially connecting with the secondary planet gear  33  of a larger pitch circle diameter, and with a pitch circle diameter of the first annular gear  4  equaling to a diameter of the compound gear set  3 , as well as with a pitch circle diameter of the secondary annular gear  5  larger than that of the secondary planet gear  33 , number of cogs will be formed differently for gears thereof gearing together when having an equal gear module. 
   When the drive assembly  2  rotates, the compound gear set  3  rotates accordingly round the first annular gear  4 , which drives the first planet gear  32  co-axially revolving and the secondary planet gear  33  round the shaft  30 , wherein the secondary planet gear  33  has a larger circumference speed for having a larger pitch circle diameter. When the drive assembly  2  rotates, a revolution of the rotary disk  31  is formed to rotate the compound gear set  3 . With the secondary planet gear  33  revolving driven by the shaft  30  and also by the rotary disk  31 , the secondary planet gear  33  thereby being able to drive the secondary annular gear  5 , which drives the shaft  7 . 
   Backwards, a rotation of the shaft  7  drives the secondary annular gear  5 , the compound gear set  3 , and, finally, the first annular gear  4 , which is fastened by a fixture  61  fixed on a case  6 , thereby stopping the rotation of the shaft  7 . 
   When having a manual design, the drive assembly  2  can be connected directly with the rotary disk  31  to obtain a higher rotating speed. To enhance a driving speed between the rotary disk  31  and a chain wheel  21 , a speed-increasing gear set can be formed within. 
   The chain wheel  21  as recited above for a manual design is driven by pulling the bead-chain  22 . 
   Referring to  FIG. 8 . When having a manual design, a rotary disk  31  can be connected with the bevel wedge gear  23 , wherein a handle  24  formed on an end for rotating manually. By swapping gears or changing gears&#39; size of the bevel wedge gear  23 , or by incorporating any design in augmenting gear revolution, a varied rotation speed of the rotary disk  31  can be obtained. 
   Referring to  FIG. 9 . Other than manually operating the drive assembly  2 , an electric motor  26  can be used to drive the rotary disk  31 , with a reduction gear forming in the middle to adjust for a different speed requirement. 
   It is of course to be understood that the embodiment described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.