Abstract:
A scanning module includes a contact image sensor, a movable base and an elasticity unit that is assembled between the contact image sensor and the base. When the assembly of the contact image sensor and the elasticity unit is placed under a glass window of a scanner, the contact image sensor and elasticity unit can be moved relatively. Thus, the scanning module can be easily assembled and decided a reduced volume to satisfy the miniaturized requirement.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a scanning module, and in particular to a scanning module used in a CIS type scanner and composed of a contact image sensor, a movable base and an elasticity unit. 
   BACKGROUND OF THE INVENTION 
   For a CIS type scanner, the assembly of a contact image sensor and a carrying base can be defined as a scanning module. Conventionally, the contact image sensor is fixed to the carrying base, and a top of the contact image sensor is engaged to an underside of a glass window. The carrying base is movable along a guide rod so as to scan and receive images during the movement of the scanning module. 
   U.S. Pat. No. 5,801,851 discloses an improvement of a CIS type scanning module and the contact image sensor is installed in a nest and a spring is biased between the contact image sensor and the nest. The spring urges the contact image sensor against an underside of a glass window. 
   In volume perspective, the nest in the above U.S. patent can receive the contact image sensor so that the volume of the contact image sensor and the nest occupy a large space. 
     FIG. 1  shows a Taiwanese Publication Patent No. 470276 which discloses a mechanism that maintains a fixed gap between the contact image sensor and the underside of the glass window. A carrying base  11  has an underside  12  which has two sleeves  13  for engaging with a guide rod (not shown). Two support portions  14  extend from two sides of the underside  12  and each of which has a flange  15  which are higher than the contact image sensor  16 . A pad  17  is located on a top of each of the flanges  15 . 
   In design perspective, because the flanges  15  of the carrying base  11  contacts the underside of the glass window  18 , a downward force is applied on the carrying base  11 . So, when every part of the carrying base  11  is made as a one-piece member by the same material, and the contact image sensor  16  is fixed to the carrying base  11 , the flanges  15  and the carrying base  11  have complicated deformation under force and the deformation is difficult to be calculated and predicted. For the designers, they cannot calculate and choose correct features of the material to be used so that a try-and-error method is used to choose the factors. However, the method does not meet the requirements of design. 
   In the transmitting perspective, because the gap has to be maintained between the carrying base  11  and the glass window  18 , the contact image sensor  16  has to be fixed on the carrying base  11  such that the elasticity efficient of the carrying base  11  becomes large. Therefore, when the carrying base  11  deforms slightly, a huge bounce force is generated and pushes the carrying base  11  to firmly contact the glass window  18 . This increases the friction between the glass window  18  and the carrying base  11  and a larger transmit force is required. This will waste too much energy and the carrying base  11  is difficult to move. 
   In the perspective of getting material, the flanges  15  need a material that has low elasticity efficient so that it is easily to be deformed and the pads  17  should be made by the material that has low friction efficient so that the pads  17  may move smoothly. However, in practical situation, the pads  17  and the flanges  15  are made by the same material and there is no proper material with low price existed. 
   In the perspective of the whole volume, the length of the carrying base  11  is roughly the same as that of the contact image sensor  16 , so that both of which occupy a large space which does not meet the miniaturized requirement of the trend of design. 
   Besides, if the contact image sensor  16  is not fixed on the carrying base  11 , or it is positioned by force-fitted arrangement, after the carrying base  11  is deformed, it cannot firmly contact the contact image sensor  16 . The contact image sensor  16  will move downward and away from the glass window  18 . In this situation, the gap between the glass window  18  and the contact image sensor  16  cannot be fixed and results in poor scanning feature. 
   SUMMARY OF THE INVENTION 
   The main object of the present invention is to provide a scanning module that is composed of a base and a contact image sensor, and both of which are easily to be designed and assembled. 
   Another object of the present invention is to provide a scanning module that includes a base and a contact image sensor and occupies less space. 
   Yet another object of the present invention is to provide a scanning module wherein the gap between the base and the contact image sensor is fixed. 
   In order to achieve the objects mentioned above, the present invention provides an elasticity unit between the base and the contact image sensor, and the contact image sensor is engaged with the elasticity unit so that the base and the contact image sensor can be moved relatively. By this way, the contact image sensor can be easily assembled and the gap between the base and the contact image sensor can be fixed. 
   Furthermore, by reducing the volume of the base and extending outward the elasticity unit from the two sides of the base to contact the contact image sensor, a compact assembly is obtained. 
   The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, preferred embodiments in accordance with the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a conventional scanning module. 
       FIG. 2  is an exploded view to show the scanning module of the present invention. 
       FIG. 3  shows the scanning module of the present invention. 
       FIG. 4  shows a bottom view of the scanning module of the present invention. 
       FIG. 5  shows the position of the contact image sensor after it is moved relatively. 
       FIG. 6  is another embodiment of the present invention. 
       FIG. 7  is yet another embodiment of the present invention. 
       FIG. 8  shows an equivalent structure corresponding to that shown in  FIG. 7 . 
       FIG. 9  shows yet another equivalent structure corresponding to that shown in  FIG. 7 . 
       FIG. 10  is another embodiment of the present invention. 
       FIG. 11  is yet another embodiment of the present invention. 
       FIG. 12  shows another embodiment of the elasticity unit of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2  shows an exploded view of the present invention and discloses a contact image sensor  21 , a base  31 , two elasticity units  41 , and two slidable units  51 . For description purpose, two elasticity units  41  are used as an example. Nevertheless, the two elasticity units  41  may also be made as a single piece which does not affect the feature of the present invention. 
   The contact image sensor  21  has a top surface  22  and a bottom surface  23  which has protrusions  24 ,  25  at two ends thereof. 
   The base  31  has a guide portion  32  which can be a sleeve as shown. 
   The two elasticity units  41  are located at two opposite sides of the base  31 . In particular, each elasticity unit  41  has a fixed end  42  for being fixed to the base  31 , and a free end  43  which is located away from the base  31 . The free ends  43  have grooves  44  defined therein and each groove  44  has an open end. 
   The slidable units  51  have a lower friction efficient and may be made of plates such as Teflon plates. It is to be noted that the slidable units  51  can be omitted if the contact image sensor  21  can be moved along the glass window. 
   The assembly of the above-mentioned parts is called a scanning module, and especially a scanning module of the CIS type scanner. 
     FIG. 3  shows the assembly of the present invention. A guide rod  61  of the scanner extends in the guide portion  32  of the base  31 , and the free ends  43  of the elasticity units  41  on the two sides of the base  31  are close to the glass window  62  of the scanner. 
   The bottom surface  23  of the contact image sensor  21  is located corresponding to the free ends  43  of the elasticity units  41 , and the top surface  22  is located corresponding to the glass window  62  so that the slidable unit  51  is attached to the glass window  62 . 
     FIG. 4  is a bottom view of the assembly. The contact image sensor  21  is engaged with the elasticity units  41  so that the protrusions  24 ,  25  of the bottom surface  23  are engaged with the grooves  44  of the free ends  43  of the elasticity units  41 . 
     FIG. 5  shows the position of the contact image sensor after it is moved relatively. When the contact image sensor  21  is installed between the elasticity units  41  and the glass window (not shown), the contact image sensor  21  urges the elasticity units  41 . 
   The grooves  44  of the elasticity units  41  are opened and the protrusions  24 ,  25  of the contact image sensor  21  are engaged with the grooves  44 . So, when the contact image sensor  21  urges the elasticity units  41 , the free ends  43  move toward the two ends of the contact image sensor  21 . 
   By this arrangement, the contact image sensor  21  can be assembled with the elasticity units  41  which generate a bounce force to urge the contact image sensor  21  onto the glass window  62 . 
   Along with the movement of the base  31  on the guide rod  61 , the elasticity units  41  and the contact image sensor  21  move along the guide rod  61  so as to scan objects. 
     FIG. 6  is another embodiment of the present invention. The grooves  44  of the free ends  43  of the elasticity units  41  are closed. The grooves  44  are made to be elongate so that the contact image sensor  21  and the elasticity units  41  are moved relatively. The protrusions  24 ,  25  are able to move in the grooves  44  so that the contact image sensor  21  and the elasticity units  41  are moved relatively. 
     FIG. 7  shows yet another embodiment of the present invention wherein the free end  43  of the elasticity unit  41  as shown in the right side of the drawing has a hole  45  which is sized to receive the protrusion  24  so that when the protrusion  24  is engaged with the hole  45 , the contact image sensor  21  and the elasticity units  41  are not able to move relatively. 
   The free end  43  of the other elasticity unit  41  as shown in the left side of the figure has two grooves  44  which has an open end and the protrusions  25  are inserted in the grooves  44 . 
   The contact image sensor  21  and the elasticity units  41  having the grooves  44  are able to move relatively. 
     FIG. 8  shows an equivalent structure corresponding to that shown in  FIG. 7 . The elasticity unit  41  on the right side is fixed to the bottom surface  23  of the contact image sensor  21  by a bolt  46  so that the contact image sensor  21  and the elasticity unit  41  do not have relative movement. The free end  43  on the left side has grooves  44  to receive the protrusions  25  of the contact image sensor  21  so that these two items are able to move relatively. 
     FIG. 9  shows another equivalent structure corresponding to that shown in  FIG. 7 . The elasticity unit  41  on the right side is fixed to the bottom surface  23  of the contact image sensor  21  by a bolt  46 . A bead  47  (small roller or rail) is connected between the contact image sensor  21  and the elasticity unit  41  on the left side. Therefore, the contact image sensor  21  and the free end  43  on the left side is able to move relatively. 
   Although there are two free ends  43  on the two elasticity units so as to evenly support the contact image sensor  21 , only one free end can be made and functions the same. In this situation, the elasticity unit  41  on the left side in  FIG. 9  is maintained. In order to get balance, the free end  43  of the elasticity unit  41  is preferably supported at the center of weight of the contact image sensor  21 . 
     FIG. 10  shows another embodiment. In this embodiment, the contact image sensor  21  is put on the elasticity unit  41  which can be made by metal, plastic or other material and has a fixed end  42  and a free end  43 . At least one free end  43  can move along the bottom surface of the contact image sensor  21 . The elasticity units  41  are fixed to a base  31  which is used as a guide portion  32  to guide itself along the guide rod  61 . The opening of the guide portion  32  can be any shape that engages with the shape of the guide rod  61  such as a V-shaped opening and is not limited to the rectangular opening as shown in this embodiment. 
     FIG. 11  shows yet another embodiment. In this embodiment, the contact image sensor  21  is put on an elasticity unit  41  which has a fixed end  42  and a free end  43 . The free end  43  can move along the bottom surface of the contact image sensor  21 . The elasticity unit  41  is fixed to a base  31  which is used as a guide portion  32  to guide itself along the guide rod  61 . The opening of the guide portion  32  can be any shape that engages with the shape of the guide rod  61  such as a V-shaped opening and is not limited to the rectangular opening as shown in this embodiment. 
   It is to be noted that the elasticity units  41 , the base  31  and the guide portion  32  can be made as a one-piece member. In this situation, cheap items can be easily made by the method of plastic ejection molding. The elasticity unit  41  as shown in  FIG. 12  can also be made by bending a metal plate. 
   In the above mentioned embodiments, the contact image sensor  21  can be connected to the elasticity units  41  by bolts or by way of engagement, and the contact image sensor  21  can be moved relatively to at least one elasticity unit  41  so that a less friction is obtained between the contact image sensor  21  and the glass window  62 . Accordingly, the present invention is easily assembled and designed, and a fixed gap is maintained between the contact image sensor  21  and the glass window  62 . 
   The base  31  is used to let the guide rod  61  extend and the elasticity unit be fixed thereto. The area between the two sides of the base  31  to the contact image sensor  21  is not used so as to reduce the volume. 
   While we have shown and described the embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.