Patent Publication Number: US-7223032-B2

Title: Fixing element capable of rotatably fixing a ribbon roller in a ribbon cartridge

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a fixing element, and more particularly, to a fixing element for rotatably fixing a ribbon roller in a ribbon cartridge. 
   2. Description of the Prior Art 
   Ribbons of thermal printers are typically rolled on two ribbon rollers, which are respectively positioned on each side of a ribbon cartridge. However, there is no fixing mechanism available for firmly fixing the ribbon rollers within the ribbon cartridge. This results in undesirable rotation of the ribbon roller due to external vibration or shock when transporting the ribbon cartridge, which can cause the ribbon to become wrinkled. Printing quality can be detrimentally affected if the ribbon is wrinkled. 
   Generally, the prior art prevents the ribbon roller from rotating via a friction force. Please refer to  FIG. 1 , which is a diagram of preventing a ribbon roller  12  from rotating according to the prior art. There is a block  14  positioned at an end of a ribbon-feeding bay in a ribbon cartridge  10 . The length of the ribbon roller  12  is longer than a distance between the block  14  and a base  16 , so that the ribbon roller  12  presses the block  14 . The pressed block  14  can provide a restoring force to the ribbon roller  12  towards the base  16 , resulting in generation of a friction force between the ribbon roller  12  and the base  16  that prevents the ribbon roller  12  from rotating. Additionally, the block  14  can be replaced by other flexible elements, which can provide a force to push the ribbon roller  12  towards the base  16 . 
   However, the block  14  is formed along with the ribbon cartridge  10 . When manufacturing the ribbon cartridge  10 , the distance between the block  14  and the base  16  has some tolerance, causing the restoring force to be inconsistent and thus the friction force to vary. If the friction force is too small, the ribbon might end up dangling out of the ribbon cartridge  10 . On the contrary, if the friction force is too large, a printer cannot make the ribbon rotate. Additionally, if the block  14  is replaced by a spring or a flexible element, the restoring force may vary due to elastic fatigue. 
   Please refer to  FIG. 2 , which shows an etched surface  17  engaging a protrusion  18  to prevent the ribbon roller  12  from rotating based on the prior art. In order to control the friction force, the etched surface  17  is placed at the end of the ribbon roller  12  contacting the base  16 , and the protrusion  18  is placed at the base  16  to engage the etched surface  17  so as to prevent the ribbon roller  12  from rotating. However, this method cannot absolutely solve the problem. If the restoration force provided by the block  14  is not large enough to make the etched surface  17  engage the protrusion  18 , the ribbon roller  12  might rotate. 
   SUMMARY OF THE INVENTION 
   It is therefore a primary objective of the claimed invention to provide a fixing element for rotatably fixing a ribbon roller in a ribbon cartridge to solve the above-mentioned problem. 
   The claimed invention discloses a fixing element comprising an accommodation means and a fastening element. The accommodation means can fix a first tab of the ribbon roller, and the fastening element can engage the ribbon cartridge. 
   These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram of preventing a ribbon roller from rotating according to the prior art. 
       FIG. 2  shows an etched surface engaging a protrusion to prevent a ribbon roller from rotating based on the prior art. 
       FIG. 3  is a diagram of a fixing element according to the present invention. 
       FIG. 4  shows a ribbon roller positioned in a ribbon cartridge according to the present invention. 
       FIG. 5  shows an assembly of the fixing element of  FIG. 3  and the part of  FIG. 4 . 
       FIG. 6  is another embodiment of the fixing element according to the present invention. 
   

   DETAILED DESCRIPTION 
   In order to solve the problem of the prior art, the present invention provides a fixing element for fixing a ribbon roller in a ribbon cartridge. 
   Please refer to  FIG. 3 , which is a diagram of a fixing element  30  according to the present invention. The fixing element  30  comprises an accommodation means  32 , a fastening element  34 , an opening  31 , a support  36 , and a pin  38 . Please also refer to  FIG. 4 , which shows the ribbon roller  12  positioned in the ribbon cartridge  10 . From  FIGS. 3 and 4 , it can be see how the fixing element  30  fixes the ribbon roller  12  in the ribbon cartridge  10 . 
   The pin  38  of the fixing element  30  is inserted into a hole  123  of the ribbon roller  12 . A first tab  121  of the ribbon roller  12  passes through the accommodation means  32  of the fixing element  30  while a second tab  122  passes through the opening  31 , so that the two tabs  121  and  122  cannot be rotated. Then, the fastening element  34  engages the ribbon cartridge  10 . After the assembly is complete, the support  36  of the fixing element  30  contacts a surface  11  of the ribbon cartridge  10  to locate the position of the ribbon roller  12  in the ribbon cartridge  10  and to prevent the part of the fixing element  30  contacting the ribbon roller  12  from vibrating. 
   The accommodation means  32  of the fixing element  30  of  FIG. 3  is a recess, and the fixing element  30  further comprises protrusions  33  positioned on both sides of the accommodation means  32  for assisting in fixing the first tab  121 . Please refer to  FIG. 6 , which is another embodiment of the fixing element  60  according to the present invention. The accommodation means  35  of the fixing element  60  of  FIG. 6  is an opening for accommodating the first tab  121 . 
   If the ribbon cartridge  10  is vibrated by an external force during transportation, a force generated by the fastening element  34  engaging the ribbon cartridge  10  is provided to the fixing element  30  to prevent the ribbon roller  12  from rotating, and the accommodation means  32  and the opening  31  can also assist in preventing the ribbon roller  12  from rotating. 
   In addition, the fixing element  30  is placed at the ribbon-feeding bay of the ribbon cartridge  10 . Since all ribbons of a new ribbon cartridge are rolled in the ribbon-feeding bay, there are only one or two layers of ribbons rolled in the ribbon-driving bay. If the new ribbon cartridge is transported and the ribbon-driving roller of such rotates a little because of external vibration or collision, the rolling force is not large enough to make the ribbon-feeding roller rotate. Thus, the fixing element  30  of the present invention placed in the ribbon-feeding bay can ensure that the ribbon will not dangle out of the ribbon cartridge. 
   Compared to the prior art, the present invention provides a method and a fixing element to fix the ribbon rollers in the ribbon cartridge. The present invention uses the fastening element to engage the ribbon cartridge, and the accommodation means and the opening to accommodate the tabs to prevent the ribbon roller from rotating. Moreover, the support can locate the position of the ribbon roller in the ribbon cartridge. Therefore, the fixing element of the present invention can prevent the ribbon roller from rotating when transporting the ribbon cartridge. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.