Abstract:
The present invention relates to a belt tension adjustment mechanism for use with a device including a main body and a belt pulley set. The belt pulley set includes a belt. The belt tension adjustment mechanism includes a slab, at least two tension pulleys and a fixing element. A tight tension force and a slack tension force are exerted on the opposite sides of the belt to define a tight side and a slack side of the belt when the belt pulley set runs. A counterforce is generated from the tight side of the belt to exert on the tension pulley contacting with the tight side, the slab is moved in response to the counterforce. The slack side of the belt is suppressed by the tension pulley contacting with the slack side such that the slack tension force is adjustable.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a belt tension adjustment mechanism, and more particularly to a belt tension adjustment mechanism for use in an office machine. 
       BACKGROUND OF THE INVENTION 
       [0002]    Nowadays, a belt pulley set is widely used in modern office automation equipment, industrial equipment or measurement equipment for transmitting the inner mechanical components. For example, a multifunction peripheral with multiple functions in one structural unit includes a belt pulley set to drive corresponding components for performing the printing, faxing or scanning operation. 
         [0003]    Referring to  FIG. 1 , a schematic cross-sectional view of a conventional multifunction peripheral is illustrated. The multifunction peripheral  1  principally includes a main body  11  and a belt pulley set  12 . The belt pulley set  12  is disposed inside the main body  11 . The belt pulley set  12  includes a driving pulley  121 , a follower pulley  122 , a belt  123  and a tension pulley  124 . The belt  123  is made cyclic and encloses around the driving roller  121  and the follower roller  122 . The driving pulley  121  is driven by a power source (e.g. a motor) to rotate. By means of the belt  123 , the follower pulley  122  is synchronously rotated with the driving roller  121 . 
         [0004]    As known, for steadily running the belt pulley set  12 , it is necessary to provide sufficient tension force to confine the belt  123  of the tension pulley  124 . During the process of inverting the driving roller  121 , tension forces are differentially exerted on the sides A and B of the belt  123 . Please refer to  FIG. 1  again. When the driving roller  121  is rotated in an anti-clockwise direction, a tight-side tension and a slack-side tension are exerted on the sides A and B, respectively. Under this circumstance, a length change is resulted on the side B of the belt  123  and thus the tension force of the belt  123  is insufficient. As a consequence, the precision of feeding the document is reduced and the scanning quality is deteriorated. For providing sufficient tension force to confine the belt  123  and adjusting the length change, the tension pulley  124  is usually arranged on the slack side B of the belt  123 . 
         [0005]    Since only one tension pulley  124  is arranged on the slack side B of the belt  123 , single-side tension adjustment is allowable when the belt pulley set  12  is rotated in a single direction. Nowadays, as the multifunction peripheral has duplex scanning capability to scan or print both sides of the document, the belt pulley set  12  needs to rotate in either the anti-clockwise direction or the clockwise direction. In other words, the slack-side tension is exerted on the side B of the belt  123  when the driving roller  121  is rotated in the anti-clockwise direction, but the slack-side tension is exerted on the side A of the belt  123  when the driving roller  121  is rotated in the clockwise direction. The belt tension adjustment mechanism with the single tension pulley  124  fails to effectively adjust the tension force of the belt  123  in both of the anti-clockwise direction and the clockwise direction. Therefore, the problems of causing low document-feeding precision and deteriorated scanning quality still exist when the multifunction peripheral  1  performs the duplex scanning operation. 
         [0006]    In views of the above-described disadvantages resulted from the prior art, the applicant keeps on carving unflaggingly to develop a belt tension adjustment mechanism according to the present invention through wholehearted experience and research. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide a belt tension adjustment mechanism for offering sufficient tension to confine the belt. Therefore, the problems of causing low document-feeding precision and deteriorated scanning quality when the multifunction peripheral performs the duplex scanning operation will be overcome. 
         [0008]    In accordance with an aspect of the present invention, there is provided a belt tension adjustment mechanism for use with a device including a main body and a belt pulley set. The belt pulley set includes a belt. The belt tension adjustment mechanism includes a slab, at least two tension pulleys and a fixing element. The slab is mounted on the main body. The tension pulleys are disposed on the slab and contacted with opposite sides of the belt. The fixing element is disposed between the tension pulleys for facilitating the slab to be movably fixed on the main body. A tight tension force and a slack tension force are exerted on the opposite sides of the belt to define a tight side and a slack side of the belt when the belt pulley set runs. A counterforce is generated from the tight side of the belt to exert on the tension pulley contacting with the tight side, the slab is moved in response to the counterforce. The slack side of the belt is suppressed by the tension pulley contacting with the slack side such that the slack tension force is adjustable. 
         [0009]    In accordance with an aspect of the present invention, there is provided a belt tension adjustment mechanism for use with a device including a main body and a belt pulley set. The belt pulley set includes a belt. The belt tension adjustment mechanism includes a slab, at least two tension pulleys, a fixing element and a confining element. The slab is mounted on the main body, and includes a gliding slot. The tension pulleys are disposed on the slab and contacted with opposite sides of the belt. The fixing element is disposed between the tension pulleys for facilitating the slab to be movably fixed on the main body. The confining element is movable along the gliding slot for restraining the movable range of the slab. A tight tension force and a slack tension force are exerted on the opposite sides of the belt to define a tight side and a slack side of the belt when the belt pulley set runs. A counterforce is generated from the tight side of the belt to exert on the tension pulley contacting with the tight side. The confining element is moved in response to the counterforce to drive movement of the slab. The slack side of the belt is suppressed by the tension pulley contacting with the slack side so as to perform tension adjustment of the belt. 
         [0010]    The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic cross-sectional view of a conventional multifunction peripheral; 
           [0012]      FIG. 2(   a ) is a schematic cross-sectional view illustrating an office machine having a belt tension adjustment mechanism according to a preferred embodiment of the present invention; 
           [0013]      FIG. 2(   b ) is a schematic perspective view of the belt tension adjustment mechanism according to a first preferred embodiment of the present invention; 
           [0014]      FIGS. 3(   a ),  3 ( b ) and  3 ( c ) are schematic cross-sectional views illustrating operations of the belt pulley set and the belt tension adjustment mechanism according to the first preferred embodiment; 
           [0015]      FIG. 4  is a schematic perspective view of a belt tension adjustment mechanism according to a second preferred embodiment of the present invention; and 
           [0016]      FIGS. 5(   a ),  5 ( b ) and  5 ( c ) are schematic cross-sectional views illustrating operations of the belt pulley set and the belt tension adjustment mechanism according to the second preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
         [0018]      FIG. 2(   a ) is a schematic cross-sectional view illustrating an office machine having a belt tension adjustment mechanism according to a preferred embodiment of the present invention. The office machine  2  is for example a multifunction peripheral. The multifunction peripheral  2  principally includes a main body  20 , a belt pulley set  21  and a belt tension adjustment mechanism  22 . The belt pulley set  21  is disposed inside the main body  20 . The belt pulley set  21  is controlled by a computer system to drive movement of the components responsible for performing the scanning or printing operations. The belt pulley set  21  includes a driving pulley  211 , a follower pulley  212  and a belt  213 . The belt  213  is made cyclic and encloses around the driving roller  211  and the follower roller  212 . The driving pulley  211  is driven by a power source (e.g. a motor) to rotate. By means of the belt  213 , the follower pulley  212  is synchronously rotated with the driving roller  211 . 
         [0019]    Referring to  FIG. 2(   b ), a schematic perspective view of the belt tension adjustment mechanism according to a first preferred embodiment of the present invention is illustrated. Please refer to  FIGS. 2(   a ) and  2 ( b ). The belt tension adjustment mechanism  22  is pivotally mounted on the main body  20  of the office machine  2 . The belt tension adjustment mechanism  22  principally includes a slab  221 , a first tension pulley  222 , a second tension pulley  223  and a fixing element  224 . The first tension pulley  222  and the second tension pulley  223  are disposed on the upper side and the lower side of the slab  221 , respectively. The first tension pulley  222  and the second tension pulley  223  are sustained against both sides A and B of the belt  213 , respectively. The slab  221  further includes a pivotal hole  221   a  between the first tension pulley  222  and the second tension pulley  223 . After the fixing element  224  penetrates through the pivotal hole  221   a  and is fixed on the main body  20 , the slab  221  is pivotally fixed on the main body  20  with the fixing element  224  serving as the pivotal center. 
         [0020]    In some embodiments, the slab  221  has a gliding slot  221   b  near the upper edge thereof such that the first tension pulley  222  is arranged between the gliding slot  221   b  and the pivotal hole  221   a . Corresponding to the gliding slot  221   b , the belt tension adjustment mechanism  22  has a confining element  225  (e.g. a screw). After penetrating through the gliding slot  221   b , the confining element  225  is fixed on the main body  20 . As the slab  221  is swung, the confining element  225  is movable along the gliding slot  221   b . Consequently, the swing range of the slab  221  is restrained by the confining element  225  and both ends of the gliding slot  221   b.    
         [0021]    Please refer to  FIG. 2(   b ) again. An extension part  221   c  is protruded from and perpendicular to the upper edge of the slab  221 . The extension part  221   c  has an engaging notch  221   d . In some embodiments, the belt tension adjustment mechanism  22  further includes a restoring element  226  such as an elastic element (e.g. a spring). A first terminal of the restoring element  226  is coupled with the engaging notch  221   d . A second terminal of the restoring element  226  is fixed on the main body  20 . In a case that the belt pulley set  21  stops running, the slab  221  will be returned to its initial position (as shown in  FIG. 3(   a )) due to the elastic restoring force of the restoring element  226 . 
         [0022]    In some embodiments, the first tension pulley  222  includes a first wheel axle  222   a  and a first partition plate  222   b , and the second tension pulley  223  includes a second wheel axle  223   a  and a second partition plate  223   b . The first wheel axle  222   a  is arranged at the center of the first tension pulley  222  and pivotally coupled to the slab  221 . Likewise, the second wheel axle  223   a  is arranged at the center of the second tension pulley  223  and pivotally coupled to the slab  221 . The first partition plate  222   b  and the second partition plate  223   b  are sheathed around the outer peripheries of the first tension pulley  222  and the second tension pulley  223 , respectively. In this embodiment, the first partition plate  222   b  and the second partition plate  223   b  are arranged in a staggered form. That is, the first partition plate  222   b  and the second partition plate  223   b  are not aligned with each other. As a consequence, after the belt  213  is sheathed around the first tension pulley  222  and the second tension pulley  223 , the belt  213  will be easily detached from the first tension pulley  222  and the second tension pulley  223 . 
         [0023]      FIGS. 3(   a ),  3 ( b ) and  3 ( c ) are schematic cross-sectional views illustrating operations of the belt pulley set and the belt tension adjustment mechanism according to the first preferred embodiment. Please refer to  FIGS. 3(   a ),  3 ( b ) and  3 ( c ) and also  FIG. 2(   a ). As shown in  FIG. 3(   a ), before the office machine  2  performs the scanning or printing operation, both sides A and B of the belt  213  are slightly contacted with the first tension pulley  222  and the second tension pulley  223 , respectively. Meanwhile, the tension forces exerted on the sides A and B are balanced. 
         [0024]    Next, for performing the scanning or printing operation by the office machine  2 , the driving roller  211  is driven by the power source (e.g. a motor) to rotate in an anti-clockwise direction. A tight-side tension and a slack-side tension are exerted on the sides A and B of the belt  213 , respectively. Under this circumstance, a counterforce generated from the tight side A of the belt  213  is exerted on the first tension pulley  222 . Due to the counterforce, the slab  221  is rotated in the anti-clockwise direction with the fixing element  224  serving as the pivotal center. As a consequence, the side B of the belt  213  is suppressed by the second tension pulley  223 , so that the tension force exerted on the side B of the belt  213  is adjusted, as can be seen in  FIG. 3(   b ). 
         [0025]    On the contrary, in a case that the driving roller  211  is driven by the power source (e.g. a motor) to rotate in a clockwise direction, a slack-side tension and a tight-side tension are exerted on the sides A and B of the belt  213 , respectively. Under this circumstance, a counterforce generated from the tight side B of the belt  213  is exerted on the second tension pulley  223 . Due to the counterforce, the slab  221  is rotated in the clockwise direction with the fixing element  224  serving as the pivotal center. As the slab  221  is rotated in the clockwise direction, the side A of the belt  213  is suppressed by the first tension pulley  222 , so that the tension force exerted on the side A of the belt  213  is adjusted, as can be seen in  FIG. 3(   c ). 
         [0026]    In a case that the scanning or printing operation is terminated, the slab  221  will be returned to its initial position (as shown in  FIG. 3(   a )) due to the elastic restoring force of the restoring element  226 . Regardless of whether the slab  221  is swung in the anti-clockwise or clockwise direction, the swing range of the slab  221  is restrained by the confining element  225  and both ends of the gliding slot  221   b.    
         [0027]    In some embodiments, after the slab  221  is moved to a proper position (as shown in  FIG. 3(   b ) or  3 ( c )) to achieve desired tension forces exerted on both sides A and B of the belt  213  by the first tension pulley  222  and the second tension pulley  223 , the slab  221  may be securely fixed on the main body  20  of the office machine  2  by the confining element  225 . As a consequence, desired tension forces exerted on both sides A and B of the belt  213  by the first tension pulley  222  and the second tension pulley  223  even if the office machine performs the singlet or duplex scanning operation to scan or print one or both sides of the document. 
         [0028]    Referring to  FIG. 4 , a schematic perspective view of a belt tension adjustment mechanism according to a second preferred embodiment of the present invention is illustrated. Please refer to  FIG. 4  and also  FIG. 2(   a ). The belt tension adjustment mechanism  40  principally includes a slab  401 , a first tension pulley  402 , a second tension pulley  403  and a fixing element  404 . The first tension pulley  402  and the second tension pulley  403  are disposed on the upper side and the lower side of the slab  401 , respectively. The slab  401  has a gliding slot  401   a  between the first tension pulley  402  and the second tension pulley  403 . The first tension pulley  402  and the second tension pulley  403  are sustained against both sides A and B of the belt  403 , respectively. A first end of the fixing element  404  penetrates through the gliding slot  401   a  of the slab  401  and is fixed on the main body  20 . A second end of the fixing element  404  is contacted with the slab  401 . As a consequence, the slab  401  is movable upwardly or downwardly along the gliding slot  401   a  such that the movable range of the slab  221  is restrained by the fixing element  404  and both ends of the gliding slot  401   a.    
         [0029]    Please refer to  FIG. 4  again. Two extension parts  401   b  are protruded from and perpendicular to the upper and lower edged of the slab  401 . The extension parts  401   b  have respective engaging notches  401   c . In some embodiments, the belt tension adjustment mechanism  40  further includes two restoring elements  405  such as elastic elements (e.g. springs). A first terminal of each restoring element  405  is coupled with a corresponding engaging notch  401   c . A second terminal of the restoring element  405  is fixed on the main body  20 . In a case that the scanning or printing operation by the office machine is terminated, the slab  401  will be returned to its initial position (as shown in  FIG. 5(   a )) due to the elastic restoring forces of the restoring elements  405 . 
         [0030]      FIGS. 5(   a ),  5 ( b ) and  5 ( c ) are schematic cross-sectional views illustrating operations of the belt pulley set and the belt tension adjustment mechanism according to the second preferred embodiment. Please refer to  FIGS. 5(   a ),  5 ( b ) and  5 ( c ) and also  FIG. 2(   a ). As shown in  FIG. 5(   a ), before the office machine  2  performs the scanning or printing operation, both sides A and B of the belt  213  are slightly contacted with the first tension pulley  412  and the second tension pulley  413 , respectively. Meanwhile, the tension forces exerted on the sides A and B are balanced. 
         [0031]    Next, for performing the scanning or printing operation by the office machine  2 , the driving roller  211  is driven by the power source (e.g. a motor) to rotate in an anti-clockwise direction. A tight-side tension and a slack-side tension are exerted on the sides A and B of the belt  213 , respectively. Under this circumstance, a counterforce generated from the tight side A of the belt  213  is exerted on the first tension pulley  402 . Due to the counterforce, the slab  401  is moved upwardly. As a consequence, the side B of the belt  213  is suppressed by the second tension pulley  403 , so that the tension force exerted on the side B of the belt  213  is adjusted, as can be seen in  FIG. 5(   b ). Meanwhile, the restoring element  405  above the slab  401  is compressed but the restoring element  405  under the slab  401  is stretched. 
         [0032]    On the contrary, in a case that the driving roller  211  is driven by the power source (e.g. a motor) to rotate in a clockwise direction, a slack-side tension and a tight-side tension are exerted on the sides A and B of the belt  213 , respectively. Under this circumstance, a counterforce generated from the tight side B of the belt  213  is exerted on the second tension pulley  403 . Due to the counterforce, the slab  401  is moved downwardly. As a consequence, the side A of the belt  213  is suppressed by the first tension pulley  402 , so that the tension force exerted on the side B of the belt  213  is adjusted, as can be seen in  FIG. 5(   c ). Meanwhile, the restoring element  405  under the slab  401  is compressed but the restoring element  405  above the slab  401  is stretched. In a case that the scanning or printing operation is terminated, the slab  401  will be returned to its initial position (as shown in  FIG. 5(   a )) due to the elastic restoring force of the restoring element  405  above or under the slab  401 . 
         [0033]    From the above description, the belt tension adjustment mechanism of the present invention is capable of providing sufficient tension to confine the belt. When the driving pulley of the belt pulley set is rotated, the slab is movable due to the counterforce generated from the tight side of the belt. Meanwhile, the slack side of the belt is suppressed by the tension pulley contacted with the slack side, so that the tension force exerted on the slack side of the belt is adjustable. Optionally, after the slab is moved to a proper position to achieve desired tension forces on both sides of the belt, the slab may be securely fixed on the main body of the office machine by the confining element. Therefore, the problems of causing low document-feeding precision and deteriorated scanning quality when the multifunction peripheral performs the duplex scanning operation will be overcome. 
         [0034]    While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.