Patent Publication Number: US-2002008144-A1

Title: Focused light source of a scanner

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a light source, and more particularly, to a focused light source of a scanner.  
       [0003] 2. Description of the Prior Art  
       [0004] A light source of a scanner is used to illuminate a document so that the scanner can scan the document. The light source must be sufficiently bright so that the sensor of the scanner can detect the light reflected from the document. When scanning, the document is scanned a line at a time. Hence, it is of no use to illuminate other areas of the document outside of the immediate scanning area. If the light can be focused onto this immediate scanning line area, the exposure time of the sensor can be shortened, thus the scanning speed of the scanner can be improved.  
       [0005] Please refer to FIG. 1 and FIG. 2. FIG. 1 is a schematic diagram of a light source  40  of a scanner according to the prior art. FIG. 2 is a schematic diagram of the light source  40  shown in FIG. 1 illuminating a document  22 . The light source  40  of the scanner according to the prior art is a line-shaped light tube  42 . When scanning a document  22  by using the light source  40 , only a small portion of the light  44  emitted by the light tube  42  illuminates the scanning line area  24  on the document  22 . Most of the light is lost. In other words, the light emitted by the light tube  42  is not effectively utilized.  
       [0006] Please refer to FIG. 3 and FIG. 4. FIG. 3 is a schematic diagram of an alternative light source  50  of a scanner according to the prior art. FIG. 4 is a schematic diagram of the light source  50  shown in FIG. 2 illuminating a document  22 . The light source  50  comprises a light tube  42 , and a reflecting surface  52  installed around the light tube  42 . When scanning using the light source  50 , part of the light  44  emitted by the light tube  42  will be reflected onto the document  22  via the reflection of the reflecting surface  52 , but still a large portion of the light  44  is lost as it is not focused on the scanning line area  24 . Hence, the light  44  emitted by the light tube  42  also is not effectively utilized.  
       SUMMARY OF THE INVENTION  
       [0007] It is therefore a primary objective of the present invention to provide a light source of a scanner which can effectively utilize the emitted light to solve the above mentioned problem.  
       [0008] In a preferred embodiment, the present invention provides a light source of a scanner, the scanner comprising a housing and a scanning module installed in the housing for scanning a document, the light source being used to illuminate the document so that the scanning module can scan the document, the light source comprising:  
       [0009] a line-shaped light tube;  
       [0010] a mask having a line-shaped groove with a line-shaped opening and an arc-shaped cross section wherein the line-shaped light tube is fixed in the line-shaped groove in parallel and the inner surface of the line-shaped groove is reflective for reflecting the light emitted from the light tube toward the opening of the groove; and  
       [0011] a focusing device installed at the opening of the groove for focusing the light emitted from the light tube and the light reflected from the inner surface of the groove onto the document.  
       [0012] It is an advantage of the present invention that the light source of the present invention can effectively utilize the light emitted by the light tube, reduce the exposure time of the sensor and thus increase the scanning speed of the scanner.  
       [0013] This and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014]FIG. 1 is a schematic diagram of a light source of a scanner according to the prior art.  
     [0015]FIG. 2 is a schematic diagram of the light source shown in FIG. 1 illuminating a document.  
     [0016]FIG. 3 is a schematic diagram of an alternative light source of a scanner according to the prior art.  
     [0017]FIG. 4 is a schematic diagram of the light source shown in FIG. 2 illuminating a document.  
     [0018]FIG. 5 is a schematic diagram of a scanner utilizing a light source of the present invention.  
     [0019]FIG. 6 is a schematic diagram of a light source according to the present invention.  
     [0020]FIG. 7 is an exploded view of the light source shown in FIG. 6.  
     [0021]FIG. 8 is a schematic diagram of the light source shown in FIG. 6 illuminating a document. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0022] Please refer to FIG. 5 and FIG. 6. FIG. 5 is a schematic diagram of a scanner  30  utilizing a light source  10  of the present invention as part of a scanning module  34 . FIG. 6 is a schematic diagram of a light source  10  according to the present invention. The present invention provides a light source  10  of a scanner  30 , and the scanner  30  comprises a housing  32  and a scanning module  34  installed in the housing  32  for scanning a document  11 . The scanning module  34  can be moved forward and backward inside the housing  32  of the scanner  30  and the light source  10  is a fixed component of the scanning module  34  for illuminating the document  11  so as to enable the scanning module  34  to scan the document  11 . The scanning module  34  comprises a CCD (charge-coupled device) (not shown) or a CIS (contact image sensor) (not shown) for detecting the light transmitted from the document  11 .  
     [0023] Please refer to FIG. 7 and FIG. 8. FIG. 7 is an exploded view of the light source  10  shown in FIG. 6. FIG. 8 is a schematic diagram of the light source  10  shown in FIG. 6 illuminating a document  11 . The light source  10  comprises a line-shaped light tube  12 , a mask  14 , and a focusing lens  20 . The line-shaped light tube  12  can be a typical cathode-ray tube or a light emitting diode. The mask  14  is made of aluminum alloy, or can be made of some alternative alloy, plastic or reflective plastic film. The mask  14  has a line-shaped groove  18  with a line-shaped opening  16  and an arc-shaped cross section. The line-shaped light tube  12  is fixed in the line-shaped groove  18  in parallel and the inner surface of the line-shaped groove  18  is reflective so that light emitted from the light tube  12  will be reflected towards the opening  16  of the groove  18 . The focusing lens  20  is installed at the opening  16  of the groove  18  for focusing onto the document  11  the light  35  emitted from the light tube  12  and the light  36  reflected from the inner surface of the groove  18 . The focusing lens  20  can also be a focusing film like BEF (brightness enhancement film) of the 3M company.  
     [0024] When scanning module  34  is scanning, most of the light emitted by the line-shaped light tube  12  of the light source  10  will be reflected by the inner surface of the line-shaped groove  18  of the mask  14  and then pass through the focusing lens  20  at the line-shaped opening  16 . Then, the light  35 ,  36  transmitted from the light tube  12  and the inner surface of the line-shaped groove  18  is focused onto a line-shaped scanning area  13  on the document  11 . Consequently, the light source  10  of the present invention can effectively utilize the light emit ted by the light tube  12  to enhance the luminosity needed when scanning. This enhanced luminosity shortens the exposure time of the sensor and enhances the scanning speed and scanning quality.  
     [0025] Compared to the light sources  40 ,  50  according to the prior art, the light source  10  of the present invention has a mask  14  wherein the inner surface of the groove  18  can gather the light emitted by the light tube  12  and the focusing lens  20  can focus onto the document  11  the light transmitted from the light tube  12  and the inner surface of the groove  18 . Hence, the light source  10  of the present invention effectively utilizes the light emitted by the light tube  12 , and focuses the light so as to enhance the luminosity needed while scanning. With a greater luminosity at the scanning area, the exposure time of the sensors is shortened and the scanning speed and quality of the scanner is enhanced.  
     [0026] Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.