Image scanner using low-pixel-density CCD to achieve high-pixel-density scanning quality by pixel-level shift of CCD

Abstract

An image scanner performing multiple scanning operations for a single scan line is disclosed. The additional scanning operations are performed between two adjacent pixels. For a double scanning mode, the CCD performs one scanning operation for a scan line at a first position. Then, the CCD is moved from the first position to a second position along the X-direction to perform the other scanning operation at the second position. The distance between the first and the second positions is a half of the distance between two adjacent pixels. The scanning data of the two scanning operations are alternatively arranged and converted into final image data. By this way, a low-pixel-density CCD can be used to obtain a high-pixel-density scanning quality.

1. An image scanner for reading and converting an image of an object into digital image data, the image scanner comprising:
 a photoelectric sensing device including a plurality of sensing pixels arranged at equal spaces for converting an optical signal from said the object into an electric signal; 
 a shifting device connected to said the photoelectric sensing device for driving said the photoelectric sensing device from a first position to a second position along an X-direction to obtain a first electric signal and a second electric signal, respectively, wherein a distance between said the first and said the second positions is less than a distance between two adjacent sensing pixels, and said the first and said the second electric signals are alternately arranged and converted to form said the digital image data; 
 a mirror set arranged upstream of said the lens device for transmitting said the optical signal from said the object to said the lens device; and 
 a carriage housing mounting therein said carrying the mirror set, said the photoelectric sensing device and said the shifting device, and moved wherein the carriage housing is configured to move along a Y-direction to scan said the object. 
 
     
     
       2. The image scanner according to  claim 1  wherein said the photoelectric sensing device includes:
 a lens device for focusing and contracting said the optical signal; 
 a linear charge coupled device consisting of said comprising the plurality of sensing pixels which senses said that sense the focused and contracted optical signal to generate said the electric signal; and 
 a holder for mounting thereon said the lens device and said the linear charge coupled device, said the holder being driven by said the shifting device to allow said the lens device and said the linear charge coupled device to be moved together from said the first position to said the second position. 
 
     
     
       3. The image scanner according to  claim 1  wherein said the shifting device includes:
 a guiding track secured on said the carriage housing for guiding said the holder along said the X-direction; 
 a first magnetic element secured on said the holder; and 
 a second magnetic element secured on said the carriage housing, and cooperating with said the first magnetic element to generate a magnetic force which reciprocates said the holder between said the first and said the second positions along said the guiding track. 
 
     
     
       4. The image scanner according to  claim 3  wherein said the shifting device further includes two stoppers located by on two opposite sides of said the holder in order to further assure that said assist the holder reciprocates in reciprocating between said the first and said the second positions. 
     
     
       5. The image scanner according to  claim 3  wherein said the magnetic force includes alternate attracting and repelling forces between said the first and said the second magnetic elements. 
     
     
       6. The image scanner according to  claim 5  wherein said the first magnetic element is a first permanent magnet, and said the second magnetic element includes:
 an electric motor; and 
 a second permanent magnet coupled to and driven by said the electric motor to rotate relative to said the first permanent magnet to switch said the magnetic force between said the attracting and repelling forces so as to reciprocate said the holder. 
 
     
     
       7. The image scanner according to  claim 5  wherein said the first magnetic element is a permanent magnet, said the second magnetic element is an electromagnet aligned with said the permanent magnet, and said the magnetic force is switched between said the attracting and repelling forces by changing a current direction passing around said the electromagnet so as to reciprocate said the holder. 
     
     
       8. The image scanner according to  claim 5  wherein said the first magnetic element includes two permanent magnets mounted on two opposite sides of said the holder, respectively, said the second magnetic element includes two electromagnets located by said the two opposite sides of said the holder and aligned with said the two permanent magnets, respectively, and said the magnetic force is switched between said the attracting and repelling forces by changing current directions passing around said the electromagnets so as to reciprocate said the holder. 
     
     
       9. The image scanner according to  claim 5  wherein said the first magnetic element is a permanent magnet, said the second magnetic element is an electromagnet aligned with said the permanent magnet, and said the magnetic force is switched between said the attracting and repelling forces by controlling whether a current passes around said the electromagnet so as to reciprocate said the holder. 
     
     
       10. The image scanner according to  claim 1  wherein said the distance between said the first and said the second positions is equal to a half of said the distance between two adjacent sensing pixels. 
     
     
       11. An image scanner for reading and converting an image of an object into digital image data, the image scanner comprising:
 a photoelectric sensing device including a plurality of sensing pixels arranged at equal spaces for converting an optical signal from said the object into an electric signal; 
 a carriage housing for mounting therein said carrying the photoelectric sensing device; and 
 a shifting device connected to said the carriage housing for driving said the carriage housing to move said the photoelectric sensing device from a first position to a second position along an X-direction; 
 wherein said the shifting device further includes two stoppers located by two opposite sides of said the photoelectric sensing device in order to further assure that said the photoelectric sensing device reciprocates between said the first and said the second positions; and 
 wherein said the photoelectric sensing device is actuated at said the first and said the second positions to obtain a first electric signal and a second electric signal, respectively, a distance between said the first and said the second positions is less than a distance between two adjacent sensing pixels, and said the first and said the second electric signals are alternately arranged and converted to form said the digital image data. 
 
     
     
       12. The image scanner according to  claim 11  wherein said the photoelectric sensing device includes:
 a lens device for focusing and contracting said the optical signal; 
 a mirror set arranged upstream of said the lens device for transmitting said the optical signal from said the object to said the lens device; and 
 a linear charge coupled device consisting of said comprising the plurality of sensing pixels which senses said that sense the focused and contracted optical signal to generate said the electric signal. 
 
     
     
       13. The image scanner according to  claim 11  wherein said the carriage housing is further moved configured to move along a Y-direction to scan said the object. 
     
     
       14. The image scanner according to  claim 11  wherein said the distance between said the first and said the second positions is equal to a half of said the distance between two adjacent sensing pixels. 
     
     
       15. A method of obtaining image data from an image scanner, comprising:
 transmitting an optical signal from a scanned object to a lens device with a mirror set wherein the mirror set is coupled to a carriage housing;   transmitting the optical signal from the lens device to a photoelectric sensing device coupled to the carriage housing;   obtaining a first signal from the photoelectric sensing device, the photoelectric sensing device comprising a plurality of sensing pixels arranged with approximately equal spacing with respect to each other;   moving the photoelectric sensing device from a first position to a second position, wherein the distance between the first position and the second position is less than the distance between two adjacent sensing pixels; and   obtaining a second signal from the photoelectric sensing device.   
     
     
       16. The method of claim 15, further comprising:
 generating a magnetic force in a magnetic element disposed on the carriage housing to cooperate with a magnet coupled to the photoelectric sensing device to move the photoelectric sensing device from the first position to the second position along a guiding track disposed on the carriage housing.   
     
     
       17. The method of claim 16, wherein the magnetic force includes alternate attracting and repelling forces. 
     
     
       18. The method of claim 15, wherein the distance between the first and the second positions is equal to half of the distance between two adjacent sensing pixels. 
     
     
       19. The method of claim 15, wherein the shifting device further includes two stoppers located by two opposite sides of the photoelectric sensing device to enable the photoelectric sensing device to move between the first and the second positions. 
     
     
       20. An image scanner, comprising:
 a photoelectric sensing device having a plurality of sensing pixels configured to convert an optical signal into an image signal, wherein at least a portion of the plurality of sensing pixels are arranged with approximately equal spacing;   a carriage housing for mounting the photoelectric sensing device;   a shifting device coupled to the carriage housing and configured to move the photoelectric sensing device between a first position and a second position along an X-direction;   wherein the shifting device further includes two stoppers located on two opposite sides of the photoelectric sensing device to assist the photoelectric sensing device in moving between the first and the second positions; and   wherein the photoelectric sensing device is adapted to be moved between the first and the second positions to obtain a first image signal and a second image signal, respectively, wherein a distance between the first and the second positions is less than a distance between two adjacent sensing pixels.   
     
     
       21. The image scanner of claim 20, further comprising:
 a lens device coupled to the carriage housing; and   a mirror set coupled to the carriage housing.   
     
     
       22. The image scanner of claim 20, wherein the carriage housing is configured to move along a Y-direction to scan an obiect. 
     
     
       23. The image scanner of claim 20, wherein the distance between the first and the second positions is equal to a half of the distance between two adjacent sensing pixels. 
     
     
       24. The image scanner of claim 20, further comprising:
 a guiding track disposed on the carriage housing for guiding the photoelectric sensing device along the X-direction;   a first magnetic element coupled to the photoelectric sensing device; and   a second magnetic element coupled to the carriage housing and cooperating with the first magnetic element to generate a magnetic force which moves the holder between the first and the second positions along the guiding track.   
     
     
       25. The image scanner of claim 24, wherein the magnetic force includes alternate attracting and repelling forces between the first and the second magnetic elements. 
     
     
       26. The image scanner of claim 24, wherein one of the first and second magnetic elements comprises a permanent magnet.