Patent Publication Number: US-2010122780-A1

Title: Screen rolling device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a screen rolling device, and more particularly to a screen rolling device capable of accurately positioning the screen. 
     2. Description of the Related Art 
       FIG. 1  shows a schematic view of a conventional screen rolling device. The device  1  includes a winding roller  11 , a transmission mechanism (not shown), a screen  12 , a first support frame  13 , a second support frame  14 , and a bottom cross bar  15 . The transmission mechanism is located in the winding roller  11 , and includes at least an elastic element and a catching element. 
     The screen  12  is wound around the winding roller  11 . The screen  12  has a first end (not shown) and a second end  122 . The first end is fixed to the winding roller  11 , and the second end  122  is a free end. The first support frame  13  and the second support frame  14  respectively support the two ends of the winding roller  11 . The bottom cross bar  15  is located at the second end  122  of the screen  12 . 
     The conventional screen rolling device  1  operates as follows. When a user intends to unroll the screen  12 , he/she only has to pull down the bottom cross bar  15  manually to cause the winding roller  11  to rotate, and thus the screen  12  is continuously unrolled. Then, the user just releases the bottom cross bar  15  when the screen  12  is unrolled to a desired length. Meanwhile, driven by the elastic element, the winding roller  11  starts to rotate inversely to wind up the screen  12 , and stops when kept by the catching element at a particular position, as shown in  FIG. 2 . 
     The conventional screen rolling device  1  has the following disadvantage. In the above process, after the bottom cross bar  15  is released, the winding roller  11  starts to rotate inversely to wind up the screen  12  by a length of D ( FIG. 2 ). Thus, at this time, the unrolled length of the screen  12  is no longer the length drawn down at the beginning. Generally, the bottom cross bar  15  must be drawn down again by a length greater than the length D, and then released to see if a desired unrolled length of the screen  12  is obtained when the winding roller  11  stops rotating. If not, the unrolled length of the screen  12  must be repeatedly adjusted. Therefore, it is quite inconvenient in use. 
     Therefore, it is necessary to provide a screen rolling device to solve the above problem. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a screen rolling device comprising a winding roller, an inner shaft, at least one metal strip roll and a screen. The inner shaft is located in the winding roller. The metal strip roll is wound around the inner shaft and has a first end and a second end. The first end is fixed to the inner shaft, and the second end drives the winding roller to rotate relative to the inner shaft. The screen is wound around the winding roller and has a first end and a second end. The first end is fixed to the winding roller, and the second end is a free end. Therefore, the length of the screen pulled down by a user is the desired length and does not need further adjustment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a conventional screen rolling device; 
         FIG. 2  is a schematic view showing the operation of the conventional screen rolling device; 
         FIG. 3  is a schematic perspective assembly view of a screen rolling device according to a preferred embodiment of the present invention; 
         FIG. 4  is a schematic perspective exploded view of a screen rolling device according to a preferred embodiment of the present invention; 
         FIG. 5  is a schematic perspective exploded views of a screen rolling device according to a preferred embodiment of the present invention, in which some of the elements are assembled; 
         FIG. 6  is a schematic perspective exploded view of an inner sleeve, a first metal strip roll, a second metal strip roll and an inner shaft according to the present invention; 
         FIG. 7  is a schematic view showing the operation of a screen rolling device according to the present invention; 
         FIG. 8  is a perspective exploded view of a tension adjustment device according to the present invention; and 
         FIGS. 9 and 10  are schematic views showing the operation of the tension adjustment device according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 3  shows a schematic perspective assembly view of a screen rolling device according to a preferred embodiment of the present invention.  FIGS. 4 and 5  show schematic perspective exploded views of a screen rolling device according to a preferred embodiment of the present invention.  FIG. 6  shows a schematic perspective exploded view of an inner sleeve, a first metal strip roll, a second metal strip roll and an inner shaft according to the present invention. 
     The screen rolling device  2  comprises a winding roller  21 , an inner shaft  22 , at least one metal strip roll (a first metal strip roll  23  and a second metal strip roll  24 ), an inner sleeve  25 , a screen  26 , a first support frame  27 , a second support frame  28  and a bottom cross bar  29 . The winding roller  21  has a first end  211 , a second end  212 , a third side cover  213  and a retaining slot  214 . The third side cover  213  has a short pin  2131 . The third side cover  213  is engaged with the second end  212  of the winding roller  21 , and the axis of the short pin  2311  is the same as that of the winding roller  21 . 
     The inner shaft  22  is located in the winding roller  21 . The inner shaft  22  comprises a first end  221 , a second end  222  and a first slot  223 . 
     The inner sleeve  25  accommodates the inner shaft  22  and the metal strip roll (the first metal strip roll  23  and the second metal strip roll  24 ). That is, the inner shaft  22  and the metal strip roll (the first metal strip roll  23  and the second metal strip roll  24 ) are located in the inner sleeve  25 . The inner sleeve  25  is engaged with the winding roller  21 , so as to rotate together with the winding roller  21 . 
     In this embodiment, the inner sleeve  25  comprises a first end  251 , a second end  252 , a first side cover  253 , a second side cover  254 , at least one second slot  255  and a protrusion  256 . The protrusion  256  is located on a surface of the inner sleeve  25 , and is engaged with the retaining slot  214  of the winding roller  21 . The first side cover  253  is engaged with the first end  251  of the inner sleeve  25 , and has a first through-hole  2531 . The second side cover  254  is engaged with the second end  252  of the inner sleeve  25 , and has a second through-hole  2541 . The first end  221  and the second end  222  of the inner shaft  22  pass through the first through-hole  2531  and the second through-hole  2541 , respectively. 
     This embodiment includes the first metal strip roll  23  and the second metal strip roll  24 . However, it is understood that the objective of the present invention can also be achieved with a single metal strip roll. The first metal strip roll  23  and the second metal strip roll  24  are wound around the inner shaft  22 . The first metal strip roll  23  has a first end  231  and a second end  232 . The second metal strip roll  24  has a first end  241  and a second end  242 . The first ends  231 ,  241  are fixed to the inner shaft  22 , and the second ends  232 ,  242  are used to drive the winding roller  21  to rotate relative to the inner shaft  22 . In this embodiment, the first end  231  of the first metal strip roll  23  and the first end  241  of the second metal strip roll  24  are inserted in the first slot  223  of the inner shaft  22 . The second end  232  of the first metal strip roll  23  and the second end  242  of the second metal strip roll  24  are fixed to the inner sleeve  25 . Preferably, the second end  232  of the first metal strip roll  23  and the second end  242  of the second metal strip roll  24  are inserted in the corresponding second slot  255  of the inner sleeve  25 . It is understood that the second end  232  of the first metal strip roll  23  and the second end  242  of the second metal strip roll  24  may be fixed to the winding roller  21  directly so that the inner sleeve  25  is omitted. 
     The screen  26  is wound around the winding roller  21 . In the present invention, the screen  26  may be a window curtain or a cloth screen for a projector. The screen  26  has a first end (not shown) and a second end  262 ; the first end is fixed to the winding roller  21 , and the second end  262  is a free end. The bottom cross bar  29  is located at the second end  262  of the screen  26 . 
     The first support frame  27  has a first receiving hole  271  and a cylinder  272 . The second support frame  28  has a second receiving hole  281 . The first receiving hole  271  receives and confines one end of the inner shaft  22 . The second receiving hole  281  receives the short pin  2131 . 
       FIG. 7  shows the operation of a screen rolling device according to the present invention. In this embodiment, the first end  231  of the first metal strip roll  23  and the first end  241  of the second metal strip roll  24  are inserted in the first slot  223  of the inner shaft  22 , the second end  232  of the first metal strip roll  23  and the second end  242  of the second metal strip roll  24  are inserted in the corresponding second slot  255  of the inner sleeve  25 , and the protrusion  256  of the inner sleeve  25  is engaged with the retaining slot  214  of the winding roller  21 . Therefore, when the user pulls down the bottom cross bar  29  manually to cause the winding roller  21  to rotate, the inner shaft  22  is stationary, so that the first metal strip roll  23  and the second metal strip roll  24  are tightly wound up to generate a restoring force. When the screen  26  is unrolled to a desired length, the restoring force in the first metal strip roll  23  and the second metal strip roll  24  is in equilibrium with the gravities of the unrolled screen  26  and the bottom cross bar  29 , so that after the user releases the bottom cross bar  29 , the bottom cross bar  29  immediately stops moving (i.e., the winding roller  21  does not rotate). Meanwhile, the unrolled length of the screen  26  is desirable and does not need further adjustment. 
     In the present invention, preferably, the first support frame  27  further has a tension adjustment device  30 . 
       FIG. 8  is a perspective exploded view of a tension adjustment device according to the present invention. The tension adjustment device  30  comprises a spring  31 , an adjustment swivel  32 , a receiving pillar  33 , a screw  34  and a fixed mount  35 . The spring  31  is wound around the cylinder  272 , and has a first end  311  and a second end  312  both extending radially. The adjustment swivel  32  covers the cylinder  272  and the spring  31 , and has at least one third slot  321 , a first abutting block  322  and a second abutting block  323 . The first abutting block  322  and the second abutting block  323  press against the first end  311  and the second end  312  of the spring  31 , respectively ( FIG. 9 ). 
     The receiving pillar  33  has at least one third abutting block  331  and a third receiving hole  332 . The third abutting block  331  extends into the third slot  321  of the adjustment swivel  32 , and is located between the first end  311  and second end  312  of the spring  31 . The third receiving hole  332 , corresponding to the first receiving hole  271 , receives and confines one end of the inner shaft  22 . In this embodiment, the third receiving hole  332  is hexagonal, and the first end  221  of the inner shaft  22  is in the shape of a hexagonal column, so that the first end  221  of the inner shaft  22  is inserted in and engaged with the third receiving hole  332 . It is understood that if the tension adjustment device  30  is omitted, the first end  221  of the inner shaft  22  is inserted in and engaged with the first receiving hole  271 . The screw  34  secures the receiving pillar  33 , the adjustment swivel  32 , and the spring  31  to the fixed mount  35 . 
       FIGS. 9 and 10  shows the operation of the tension adjustment device according to the present invention. As shown in  FIG. 9 , the first abutting block  322  and the second abutting block  323  of the adjustment swivel  32  press against the first end  311  and the second end  312  of the spring  31 , respectively. As shown in  FIG. 10 , when the adjustment swivel  32  rotates in the arrow direction, the second abutting block  323  presses against the second end  312  of the spring  31 , and the spring  31  is slightly loosened and becomes rotatable. Thus, when the adjustment swivel  32  continues to rotate, the second abutting block  323  and the second end  312  of the spring  31  may be in contact with the third abutting block  331  of the receiving pillar  33  and drive the receiving pillar  33  to rotate. Meanwhile, the third abutting block  331  of the receiving pillar  33  will be restricted between the first end  311  and the second end  312  of the spring  31 . Thus, if the receiving pillar  33  rotates clockwise, the third abutting block  331  will press against the second end  312  of the spring  31 , and the spring  31  will be tightened firmly on the cylinder  272  and stop rotating. If the receiving pillar  33  rotates counterclockwise, the third abutting block  331  will press against the first end  311  of the spring  31 , and the spring  31  will be tightened firmly on the cylinder  272  and stop rotating. Therefore, the angle of the inner shaft  22  can be changed by rotating the adjustment swivel  32 , so as to adjust the tension on the first metal strip roll  23  and the second metal strip roll  24 . 
     While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of the present invention are within the scope defined in the appended claims.