Abstract:
A light-guide module is used for guiding the incident light to a process device. The light-guide module includes an entrance and a plurality of reflected mirrors. The entrance is provided for entering the signal light. The reflected mirrors are arranged as a predetermined light route for guiding out the signal light. One of the reflected mirrors includes a light shielding structure for preventing the noise reflecting from the reflected mirror so as to prevent the noise light from entering the image sensing device and to prevent the image sensing device to process the noise.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The invention relates to a light shielding structure adopted for use on reflected mirrors, and more particularly to a light shielding structure for a light-guide module of an image scanning apparatus or a multi-functional peripheral to prevent redundant light reflection of reflected mirrors of the light-guide module or noise signals from projecting to an image sensing device. 
     (2) Description of the Prior Art 
     Under the present demand for improving image resolution and shrinking device size, there is a constant requirement for image process apparatus (such as scanners or MFPs) to adopt an advanced design in the optical processing mechanism that generates digital image signals. 
     Refer to  FIG. 1  for a conventional scanning device  10 . It includes a cover plate  101 , a light source  102 , a scanning deck  104 , a light-guide module  106 , a lens  108  and an image sensing device  110 . The cover plate  101  aims to cover a scanning object  30  located on the scanning deck  104 . The light source  102  emits light to the scanning object  30 . The light is reflected by the scanning object  30  and passes through an entrance  1066  to the light-guide module  106 . The light-guide module  106  has a reflected mirror set which includes reflected mirrors. Four reflected mirrors  1061 ,  1062 ,  1063  and  1064  are taken as an example shown in  FIG. 1 . The reflected mirrors  1061  through  1064  aim to transmit light according to a preset light route to the lens  108 . The lens  108  converges the light to become an image on the image sensing device  110  which transforms the receiving image light to digital signals. The light-guide module shown in  FIG. 1  may be used on scanning apparatus and other image process devices such as MFPs. 
     With proper calibration, an incident light can project accurately to the center area of the four reflected mirrors shown in  FIG. 1  and be precisely directed to the image sensing device. But the conventional reflected mirrors often are too big and light from other non-relevant light sources often occurs and projects to the light sensing device  110 , such as an external light  1023  shown in  FIG. 1 . As a result, the scan image generated by the conventional scanning device  10  often is blurred by black shadows or noise signals. 
     Moreover, the light reflected by the object  30  also has incident angle problem, such as the light reflected by the first reflected mirror  1061  might directly project to the fourth reflected mirror  1064  and be directed to the image sensing device  110  (indicated by lights  1021  and  1022  shown in  FIG. 1 ). Or some lights are directly projected to the fourth reflected mirror  1064  and form erratic reflection to the image sensing device  110  (many other erratic light reflections might also occur. They are not indicated in  FIG. 1  to smooth reading). All this erratic reflection will generate redundant scanning images on the conventional scanning device  10  and result in undesirable scanning quality. This becomes even more serious in the high resolution. 
     In addition, in the event of the calibration of the reflected mirrors is not properly done such as the one shown in  FIG. 1  (not accurate positioning of the reflected mirrors), even if the light is projected to the center area of the reflected mirror, the reflected light could deviate and cannot travel on the correct light route and project correctly to the reflected mirrors at the later stages. While the light might finally be reflected to the light sensing device, it is not a normal reflection and redundant scan images occur. 
     Therefore to design the reflected mirrors at a correct size to reflect light accurately without an extra reflecting area to reflect erratic light or noise signals is a goal pursued by scanner or MFP makers. However, due to fabrication technique and material constraints, there is a limitation for the dimension of the reflected mirrors. It is very difficult to produce reflected mirrors that fully meet the requirements. As the prevailing trend of product design demands compact size, to shrink the size of the reflected mirrors often result in mirror shattering and higher cost. Production and assembly become more complicated. Any damage of the reflected mirrors will increase the fabrication cost and time. When the reflected mirrors are too small, calibration of the reflected mirrors to form a correct light route also is more difficult. This is another concern of the design. 
     In view of the foregoing disadvantages, there is a need to provide a novel design for the reflected mirrors to overcome the problems of erratic reflection and noise signals occurred to the excessive size of the reflected mirrors, and the shattering and high cost occurred to the small size of the reflected mirrors. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a light shielding structure for reflected mirrors that can cover the excessive area of the reflected mirrors so that light reflected to the covered area is absorbed without directing to the image sensing device. 
     It is another object of the present invention to provide a light shielding structure that is easy to install on the excessive area of the reflected mirrors to reduce cost and increase assembly yield of the reflected mirrors. 
     It is yet another object of the present invention to maintain the original size of the reflected mirrors and provide a light shielding structure only on the excessive area to prevent erratic light reflection. As the dimension of the reflected mirrors is not altered, there is no need to change the configuration and calibration of the reflected mirrors, and redesign of the light-guide module is not necessary. 
     In one aspect, the invention provides a scanning apparatus to scan an image object. The scanning apparatus includes a light source, an image sensing device and a light-guide module. The light source aims to generate light to project to the image object and to be reflected thereof. The light-guide module includes at least one reflected mirror to transmit the reflecting light to the image sensing device. The image sensing device receives the light and generates corresponding digital signals. The reflected mirror includes a light shielding structure to prevent erratic light from occurring to the reflected mirror and directing to the image sensing device. 
     The present invention provides a simple design that couples a light shielding stricture on the excessive area of the original reflected mirror to absorb the erratic light or noise signals. It overcomes the conventional problems of adopting small reflected mirrors that results in a higher cost and difficult fabrication and assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which 
         FIG. 1  is a schematic view of a conventional scanning apparatus; 
         FIG. 2  is a schematic view of a scanning apparatus of the present invention; 
         FIG. 3  is a schematic view of a first embodiment of the reflected mirror and light shielding structure of the invention according to  FIG. 2 ; 
         FIG. 4  is a schematic view of a second embodiment of the reflected mirror and light shielding structure of the invention according to  FIG. 2 ; and 
         FIG. 5  is a schematic view of a third embodiment of the reflected mirror and light shielding structure of the invention according to  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The light-guide module of the invention is adopted for use on an image processing device that has to direct or change the light traveling route such as a scanning device or MFP. The light-guide module mainly aims to receive light from an entrance and reflect the light through reflected mirrors to an image sensing device. Namely, the reflected mirrors in the light-guide module can alter the traveling route of the light to reduce the size of the device. The following embodiment is based on adopting the invention to a scanning apparatus. 
     Referring to  FIG. 2 , the scanning apparatus  20  includes a cover plate  201 , a light source  202 , a scanning deck  204 , a light-guide module  206 , a lens  208  and an image sensing device  210 . The cover plate  201  aims to cover a scanning object  30  on the scanning deck  204 . The light source  202  emits, light to the scanning object  30 . The light is reflected by the scanning object  30 . The scanning deck is made of glass and can withstand the weight of the scanning object  30 , and is transparent to allow the light to pass through. The light passes through the scanning deck  202  and projects to the light-guide module  206 . 
     The light-guide module  206  includes an light entrance  212  and a reflected mirror assembly. In  FIG. 2 , the mirror assembly consists of four reflected mirrors  2141  through  2144 . The number of the reflected mirrors depends on the individual design of users. In general, the number of the reflected mirrors ranges from two to eight. Light enters the light-guide module  206  through the light entrance  212 , and is reflected by the reflected mirrors  2141 ,  2142 ,  2143  and finally  2144 . The light then is reflected by the reflected mirror  2144  to the lens  208  which converges the light to the image sensing device  210 . The image sensing device  210  transforms the light to digital signals which are processed by the scanning apparatus. At present the image sensing device  210  mainly includes two types, i.e. Charge-Coupled Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS). It is to be noted that, aside from adopted on the scanning apparatus, the light-guide module of the invention may also be used on other image processing devices such as MFPs to direct signal light for image processing. 
     In one aspect, the invention includes one light shielding structure on at least one of the reflected mirrors. As shown in  FIG. 2 , the reflected mirror  2141  has a light shielding structure  216  located thereon. As previously discussed, the reflected mirrors of the conventional techniques have excessively large reflected mirrors that result in erratic reflection or noise signals. The invention, by deploying the light shielding structure  216  on the excessive area, can absorb the unnecessary light (such as lights  2021 ,  2022  and  2023  shown in  FIG. 2 ) without reflecting to the image sensing device  210 . 
     Refer to  FIG. 3  for a first embodiment of the reflected mirror  2141  and the light shielding structure  216  of the invention shown in  FIG. 2 . In this embodiment, the light shielding structure  216  is a black covering sleeve  316  to cover the excessive area of the reflected mirror  2141 . The size and location of the excessive area and the corresponding size of the black covering sleeve  316  may be determined by a simple calculation by those skilled in the art. The black covering sleeve  316  can absorb the incident light, and the rest area other than the black covering sleeve serves as the normal reflecting area to reflect light. Thus erratic light reflection or noise signals may be prevented. To reduce the fabrication cost, the black covering sleeve may be made from rubber or the like. 
     Refer to  FIG. 4  for a second embodiment of the reflected mirror  2141  and the light shielding structure  216  of the invention shown in  FIG. 2 . In this embodiment, the light shielding structure  216  is a black printing zone  416  formed on the excessive area of the reflected mirror  2141 . It can produce the same effect as the black covering sleeve  316  set forth above.  FIG. 5  illustrates a third embodiment of the reflected mirror  2141  and the light shielding structure  216 . In this embodiment, the light shielding structure  216  is formed by bonding a piece of light shielding paper  516 . It also can absorb the erratic light and noise signals. 
     Simulation data are provided below to further elaborate the present invention. Assuming the dimension of the reflected mirror  2141  is 20 mm×200 mm×5 mm (width×length×thickness), to those skilled in the art, the center reflecting area may be calculated as 5 mm×200 mm (width×length). The excessive area on two sides of the reflected mirror is 7.5 mm×200 mm (width×length). The light shielding structure may be formed by a black covering sleeve at a size of 7.5 mm×200 mm×5 mm with a hollow interior to couple on the excessive area of the two sides of the reflected mirror. Another approach is to print a black zone on the surface of two sides of the reflected mirror at a dimension of 7.5 mm×200 mm. Still other approach is to bond two pieces of black paper at a dimension of 7.5 mm×200 mm to the two sides of the reflected mirror. All these embodiments can prevent unnecessary light from projecting to the image sensing device. As the reflected mirrors and their size may vary according to design requirements, the simulation data previously discussed serve only for illustrative purpose, and is not the limitation of the invention. 
     It is to be noted that, the light shielding structure may be adopted on one or more reflected mirror rather than the first reflected mirror set forth above. The correct reflecting area and the erratic reflecting zone of each reflected mirror may be calculated to design the corresponding light shielding structure. By adopting the invention, even if the configuration of the reflected mirrors is not in an optimal condition and deviation of light route occurs, the light shielding structure can mask the area caused by the erratic light route to absorb the erratic light and prevent the erratic light from projecting to the image sensing device. Hence the invention can make design of the reflected mirrors easier. 
     In another aspect, besides shielding the excessive area of the reflected mirror by the three types of light shielding structures previously discussed, many other types of light shielding designs may be adopted. Details are omitted. As long as they adopt the principle and spirit of the invention, they should be deemed within the scope of the present invention. 
     In summary, the present invention adds a light shielding structure to the reflected mirror to prevent unnecessary light from projecting to the image sensing device and eliminate noise signals. Signal processing quality is enhanced. Moreover, the light shielding structure of the invention is added to the reflected mirror. Fabrication is easy. Configuration and calibration of the reflected mirrors also are simple. And the original reflected mirrors may be used without the need to specially design smaller reflected mirrors. Fabrication and assembly are simpler, and the cost is lower. 
     While the preferred embodiments of the present invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the present invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the present invention.