Abstract:
A high-resolution sensing method for a scanner having a motor and a charge coupled device. The charge coupled device further has m rows of sensors spaced a distance from each other. A motor with a moving speed equal to the width of one row of the sensors divided by an exposure time moves a distance equal to the width of one row of the sensors. During the exposure time, rows of the sensors are used to scan and to obtain image signals that have portions overlapped with each other. Therefore, by simply adding the number of rows of the sensors, the scanner has m times of resolution without changing the speed of the motor.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to a sensing method of a scanner, and more particularly, to a high-resolution sensing method for a scanner. 
     2. Description of the Related Art 
     A scanner scans a document by incorporating a charge coupled device that detects the light intensity reflected from the document. The charge coupled device may perform a gray-scale scan or a color scan by using a whole row of sensors to scan the light intensity reflected from the document.  FIG. 1  shows a schematic drawing of a conventional scanner. 
     In  FIG. 1 , a step motor  102  moves a chassis  108  to an optical resolution distance (that is, the width of one row of sensors in the charge coupled device  104 ). The light emitted from the lamp  106  projects on the document  110 , and is then reflected thereby and travels through a mirror  112 , a lens  114  to the sensors  116 ,  118 ,  120  (R, G, B sensors) in the charge coupled device  104 . The detected image signal is then sent to a subsequent circuit (not shown) for signal processing. The step motor  102  then shifts the chassis with an optical resolution distance along the scan direction. According to the above steps, the image signal detected from the next row of the document  110  is sent to the subsequent circuit for signal processing by the charge coupled device  104 . Thereby, the image data for the whole document  110  can be obtained. 
     While scanning the document  110 , the optical resolution of the step motor  102 , that is, the distance that the chassis  108  is moved by the step motor  102  each time, is reduced to enhance the scan resolution. For example, the motor moves one step in 10 ms with a rotating speed of 100 pps for one time of the optical resolution. If 16 times of the optical resolutions is required, the step motor  102  moves 16 steps in 10 ms with a rotating speed of 1600 pps. Therefore, the higher the resolution of the scanner  100  is, the more the speed of the step motor  102  varies. It is difficult to design a step motor with a large speed variation. The cost thereof is greatly increased. 
     SUMMARY OF THE INVENTION 
     The present invention provides a high-resolution sensing method for a scanner that increases the rows of the sensors to obtain the high-resolution function without changing, or greatly increasing speed variation of the step motor. The design difficulty is thus resolved, while the fabrication cost is not greatly increased. 
     In the high-resolution sensing method for a scanner provided by the present invention, the scanner has m times of resolutions. The scanner has a motor and a charge coupled device. The charge coupled device further has m rows of spaced sensors. Each of the m rows of sensors is spaced a distance from the other. The motor moves a distance equal to the width of one row of sensors with a moving speed equal to the width of one row of sensor divided by an exposure time. During the exposure time, staggered rows of the sensors are scanned to obtain the image signals. 
     The present invention further provides a high-resolution sensing method to allow a scanner to have m+1 times of resolution. The scanner has a motor and a charge coupled device. The charge coupled device further has m rows of sensors spaced a distance from each other. The high-resolution sensing method for the scanner includes moving the motor a distance m/(m+1) times the width of one row of the sensors, while the moving speed of the motor is equal to m/(m+1) the width of one row of the sensors divided by an exposure time. During the exposure time, alternate rows of the sensors are scanned to obtain an image signal. Thereby, a high-resolution function of the scanner is obtained without increasing the moving speed of the motor. 
     Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic drawing of a conventional scanner; 
         FIG. 2  is a schematic drawing showing a scanner in one embodiment of the present invention; 
         FIG. 3  shows a method of doubling the resolution according to the present invention; 
         FIG. 4  shows a method of tripling the resolution according to the present invention; 
         FIG. 5  shows another method of tripling the resolution according to the present invention; and 
         FIG. 6  shows another method tripling the resolution according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 2 , a schematic drawing of a scanner provided in the present invention is shown. In  FIG. 2 , the step motor  202  moves the chassis  208  an optical resolution distance (that is, the width of one row of sensors of the charge coupled device  204 ). The lamp  206  projects a light on the document  210 . The light incident on the document  210  is reflected through the mirror  212  and the lens  214  to reach the sensors  216 ,  218  and  220  of the charge coupled device  204 . The sensors  216 ,  218  and  220  include rows of sensors to detect three primary colors R, G, B. The charge coupled device  204  sends the detected image signal to the subsequent circuit (not shown) for signal processing. The step motor  202  then moves the chassis  208  an optical resolution distance along the scan direction. Accordingly, a next image signal corresponding to a next row of the document  210  is sent to the subsequent circuit for signal processing by the charge coupled device  204 . Thereby, the image data for the whole document  210  can be scanned and obtained by the scanner  200 . 
       FIG. 3  shows a method of obtaining twice the resolution. In  FIG. 3  (also referring to  FIG. 2 ), the step motor  202  moves along the scan direction with a speed of one optical resolution (that is, the moving speed of the step motor  202  V=D/T, where D is the width of one row of sensors and T is the exposure time). The scanner scans the document  210  with double the resolution. Block A indicates the A row of sensors  302 , block B indicates the B row of sensors  304 , where the B row of sensors  302  and A row of sensors  304  are spaced from each other by a distance ΔL equal to ½D, or alternatively equal to ½D+nD, n is an integer equal to or larger than zero. Again, D is the width of one row of the sensors. 
     At T=t, the step motor  202  moves along the scan direction the width of one row of the sensors, the A row of sensors  302  scans the first and second regions of the document  210  (the width of scanned two regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 1 . 
     At T=2t, the step motor  202  moves further along the scan direction the width of one row of the sensors, the A row of sensors  302  scans the third and fourth regions of the document  210  to obtain an image signal of row A 2 . 
     At T=3 t, the step motor  202  moves along the scan direction the width of one row of the sensors, the A row of sensors  302  scans the fifth and sixth regions of the document  210  (the width of two scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 3 . Meanwhile, the B row of sensors  304 , spaced a half width of one row of the sensors (equivalent to the width of one scanned region) from the A row of sensors  302 , scans the second and the third regions of the document to obtain the image signal of the row B 3 . 
     At T=4 t, the step motor  202  moves along the scan direction the width of one row of the sensors, and the A row of sensors  302  scans the seventh and eighth regions of the document  210  (the width of two scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 4 . Meanwhile, the B row of sensors  304 , spaced a half width of one row of the sensors from the A row of sensors  302 , scans the fourth and the fifth regions of the document to obtain the image signal of the row B 4 . 
     Accordingly, when the step motor  202  moves with the speed of one optical resolution to scan the document  210 , image signals scanned by the A row of sensors  302  and the B row of sensors  304  are obtained from regions spaced a distance equal to one-half the width of one row of the sensors from each other. For example, the image signal of row A 1  is obtained by scanning the first and the second regions. The image signal of row B 3  is obtained by scanning the second and the third regions, and the image signal of row A 2  is obtained by scanning the third and the fourth regions. The image signals are staggered with each other. The image signal of row B 4  is obtained by scanning the fourth and the fifth regions, while the image signal of row A 3  is obtained by scanning the fifth and the sixth regions, and so on. 
     All the image signals with overlapped scanned regions detected by row A of sensors  302  and row B of sensors  304  are sent to the subsequent circuit for image processing and data sorting and recording, and a complete image data can be obtained. Therefore, by simply doubling the rows of sensors, the resolution of the scanner is doubled without increasing the optical resolution speed of the step motor  202 . 
       FIG. 4  shows a schematic drawing of the method to triple the resolution. In  FIG. 4  (also referring to  FIG. 2 ), the step motor  202  moves along the scan direction with a speed of one optical resolution (that is, the moving speed of the step motor  202  V=D/T, where D is the width of one row of sensors and T is the exposure time). The scanner scans the document  210  with triple resolution. Block A indicates the A row of sensors  402 , block B indicates the B row of sensors  404 , and block C indicates the C row of sensors  406 , where the A row of sensors  402 , the B row of sensors  404  and the C row of sensors  406  are spaced from each other by a distance ΔL equal to ⅔D, or alternatively equal to ⅔D+nD, n is an integer equal to and larger than zero. Again, D is the width of one row of the sensors. 
     At T=t, the step motor  202  moves along the scan direction the width of one row of the sensors, so that the A row of sensors  402  scans the first, the second and the third regions of the document  210  (the width the three scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 1 . 
     At T=2 t, the step motor  202  moves further along the scan direction the width of one row of the sensors, the A row of sensors  402  scans the fourth, the fifth, and sixth regions of the document  210  to obtain an image signal of row A 2 . 
     At T=3 t, the step motor  202  moves the width of one row of the sensors along the scan direction, and the A row of sensors  402  scans the seventh, eighth and ninth regions of the document  210  (the width of the scanned three regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 3 . Meanwhile, the B row of sensors  404 , spaced two-thirds the width of one row of the sensors (equivalent to the width of two scanned region) from the A row of sensors  402 , scans the second, the third and the fourth regions of the document to obtain the image signal of the row B 3 . 
     At T=4 t, the step motor  202  moves the width of one row of the sensors along the scan direction, and the A row of sensors  402  scans the tenth, eleventh and twelfth regions of the document  210  (the width of the scanned three regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 4 . Meanwhile, the B row of sensors  404 , spaced two-thirds the width of one row of the sensors from the A row of sensors  302 , scans the fifth, the sixth and the seventh regions of the document to obtain the image signal of the row B 4 . 
     At T=5 t, the step motor  202  moves the width of one row of the sensors along the scan direction, and the A row of sensors  402  scans the thirteenth, fourteenth, and fifteenth regions of the document  210  (the width of three scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 5 . Meanwhile, the B row of sensors  404 , spaced two-thirds the width of one row of the sensors from the A row of sensors  402 , scans the eighth, the ninth and the tenth regions of the document to obtain the image signal of the row B 4 . The C row of sensors  406 , spaced two-thirds the width of one row of the sensors from the B row of sensors  404 , also scans the third, the fourth and the fifth regions of the document to obtain the image signal of the row C 5 . 
     Accordingly, when the step motor  202  moves with the speed of one optical resolution to scan the document  210 , the A, B and C rows of sensors  402 ,  404  and  406  scan the regions of the document  210  spaced a distance equal to two-thirds the width of one row of the sensors from each other. The image signals obtained are staggered by one region, for example, the image signal of row A 1  from the first, second, third regions, the image signal of row B 2  from the second, the third and the fourth regions, and the image signal of row C 3  from the third, fourth and the fifth regions. 
     All the image signals detected by row A of sensors  402 , row B of sensors  404 , and the row C of sensors  406  are sent to the subsequent circuit for image processing and data sorting and recording, and a complete image data can be obtained. Therefore, by simply tripling the rows of sensors, the resolution of the scanner is tripled without increasing the optical resolution speed of the step motor  202 . 
       FIG. 5  shows a schematic drawing of another method to triple the resolution. In  FIG. 5  (also referring to  FIG. 2 ), the step motor  202  moves along the scan direction with a speed of one optical resolution (that is, the moving speed of the step motor  202  V=D/T, where D is the width of one row of sensors and T is the exposure time). The scanner scans the document  210  with triple resolution. Block A indicates the A row of sensors  502 , block B indicates the B row of sensors  504 , and block C indicates the C row of sensors  506 , where the A row of sensors  502 , the B row of sensors  504  and the C row of sensors  506  are spaced from each other by a distance ΔL equal to 4/3D, or alternatively equal to ⅓D+nD, n is an integer equal to or larger than zero. Again, D is the width of one row of the sensors. 
     At T=t, the step motor  202  moves the width of one row of the sensors along the scan direction, so that the A row of sensors  502  scans the first, the second and the third regions of the document  210  (the width of three scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 1 . 
     At T=2 t, the step motor  202  moves the width of one row of the sensors further along the scan direction, the A row of sensors  502  scans the fourth, the fifth, and sixth regions of the document  210  to obtain an image signal of row A 2 . 
     At T=3 t, the step motor  202  moves the width of one row of the sensors along the scan direction, the A row of sensors  502  scans the seventh, eighth and ninth regions of the document  210  (the width of the scanned three regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 3 . 
     At T=4 t, the step motor  202  moves the width of one row of the sensors along the scan direction, the A row of sensors  502  scans the tenth, eleventh and twelfth regions of the document  210  (the width of the three scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 4 . Meanwhile, the B row of sensors  504  spaced from the A row of sensors  502  by four-thirds the width of one row of the sensors (equivalent to the width of four scanned regions) scans the third, the fourth and the fifth regions of the document to obtain the image signal of the row B 4 . 
     At T=5 t, the step motor  202  moves the width of one row of the sensors along the scan direction, the A row of sensors  502  scans the thirteenth, fourteenth and fifteenth regions of the document  210  to obtain an image signal of row A 5 . Meanwhile, the B row of sensors  504 , spaced four-thirds the width of one row of the sensors from the A row of sensors  502 , scans the sixth, the seventh and the eighth regions of the document to obtain the image signal of the row B 5 . 
     At T=6 t, the step motor  202  moves the width of one row of the sensors along the scan direction, the A row of sensors  502  scans the sixteenth, seventeenth, and eighteenth regions of the document  210  to obtain an image signal of row A 6 . Meanwhile, the B row of sensors  504 , spaced four-thirds the width of one row of the sensors from the A row of sensors  502 , scans the ninth, the tenth and the eleventh regions of the document to obtain the image signal of the row B 6 . The C row of sensors  506 , spaced four-thirds of the width of one row of the sensors from the B row of sensors  504 , also scans the second, the third and the fourth regions of the document  210  to obtain the image signal of the row C 6 . 
     Accordingly, when the step motor  202  moves with the speed of one optical resolution to scan the document  210 , the A, B and C rows of sensors  502 ,  504  and  506  scan the regions of the document  210  spaced from each other by a distance equal to four-thirds the width of one row of the sensors. The image signals obtained from the regions are spaced the width of one region from each other. For example, the image signal of row A 1  from the first, second, third regions, the image signal of row C 6  from the second, the third and the fourth regions, and the image signal of row B 4  from the third, fourth and the fifth regions are staggered with each other. 
     All the image signals detected by the row A of sensors  502 , the row B of sensors  504 , and the row C of sensors  506  are sent to the subsequent circuit for image processing and data sorting and recording, and a complete image data can be obtained. Therefore, by simply tripling the rows of sensors, the resolution of the scanner is tripled without increasing the optical resolution speed of the step motor  202 . 
       FIG. 6  shows a schematic drawing of another method to triple the resolution. In  FIG. 6  (also referring to  FIG. 2 ), the step motor  202  moves along the scan direction with a speed of one optical resolution (that is, the moving speed of the step motor  202  V=(⅔)D/T, where D is the width of one row of sensors and T is the exposure time). The scanner  200  scans the document  210  with triple resolution. Block A indicates the A row of sensors  602 , and block B indicates the B row of sensors  604 , where the A row of sensors  602  and the B row of sensors  604  are spaced from each other by a distance ΔL equal to 2 D, or alternatively equal to 2 nD, where n is an integer equal to or larger than zero. Again, D is the width of one row of the sensors. 
     At T=t, the step motor  202  moves two-thirds the width of one row of the sensors along the scan direction, so that the A row of sensors  602  scans the first, the second and the third regions of the document  210  (the width the three scanned regions of the document  210  is equal to the width of one row of sensors) to obtain an image signal of row A 1 . 
     At T=2 t, the step motor  202  moves two-thirds the width of one row of the sensors further along the scan direction, the A row of sensors  602  scans the third, the fourth and the fifth regions of the document  210  to obtain an image signal of row A 2 . 
     At T=3 t, the step motor  202  moves two-thirds the width of one row of the sensors along the scan direction, the A row of sensors  602  scans the fifth, sixth and seventh regions of the document  210  to obtain an image signal of row A 3 . 
     At T=4 t, the step motor  202  moves two-thirds the width of one row of the sensors along the scan direction, the A row of sensors  602  scans the seventh, eighth and ninth regions of the document  210  to obtain an image signal of row A 4 . 
     At T=5 t, the step motor  202  moves two-thirds the width of one row of the sensors along the scan direction, the A row of sensors  602  scans the ninth, tenth and eleventh regions of the document  210  to obtain an image signal of row A 5 . 
     At T=6 t, the step motor  202  moves two-thirds the width of one row of the sensors along the scan direction, the A row of sensors  602  scans the eleventh, twelfth and thirteenth regions of the document  210  to obtain an image signal of row A 6 . Meanwhile, the B row of sensors  604 , spaced the width of two rows of the sensors (equivalent to the width of six scanned regions) from the A row of sensors  602 , scans the second, the third and the fourth regions of the document to obtain the image signal of the row B 6 . 
     Accordingly, when the step motor  202  moves with the speed of two-thirds the optical resolution to scan the document  210 , the A and B rows of sensors  602 ,  604  scan the regions of the document  210  spaced from each other by the width of one region. For example, the image signal of row A 1  is obtained from the first, second, and third regions, the image signal of row B 6  is obtained from the second, the third and the fourth regions, and the image signal of row A 2  is obtained from the third, fourth and the fifth regions. 
     All the image signals detected by the row A of sensors  602  and the row B of sensors  604  are sent to the subsequent circuit for image processing and data sorting and recording, and a complete image data can be obtained. Therefore, by changing the optical resolution speed of the step motor to two-thirds of the original speed and increasing the number of rows of the sensors from one to two, the resolution of the scanner  200  is tripled. 
     Accordingly, one can further increase the resolution of the scanner (more than triple) by increasing the rows of the sensors, or by changing speed of the step motor into m/(m+1) of the original speed, and increasing the rows of sensors to m rows. Consequently, the resolution is m+1 times multiplied. 
     Therefore, the present invention increases the resolution of the scanner without increasing the design difficulty of the step motor and raising the cost issue. 
     Other embodiments of the invention will appear to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.