Abstract:
An automatically focusing and multiple resolution scanning device which employs a final light path changing device to change the final light path of the image information. A scanning device scans the standard pattern and compares the scanned result with the image information so as to precisely focus and adjust the image information to be a correct image status. By this way, various types of resolutions can be achieved.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a multi-resolution scanning device having an auto-focus function, and a method for focusing for the device. In particular, the device employs changes of the light path to provide various magnifying features and resolution functions. A standard pattern is used to allow the device to automatically focus on an item.  
         BACKGROUND OF THE INVENTION  
         [0002]    There are different requirements for scanning document and films due to the scanning ranges and the requirements of resolution are different so that specific document scanner and specific film scanner are developed to meet the requirements.  
           [0003]    However, providing lower resolution and higher resolution is the trend of the modern scanners. Taiwanese patent publish number 342158 with the title of “transmission and reflection dual-resolution scanner device”, Taiwanese patent publish number 391604 with the title of “flatbed scanner having dual-resolution scanning module (1)” and Taiwanese patent publish number 368240 with the title of “flatbed scanner having dual-resolution scanning module (1)” are examples that disclosed the use of assembly of multiple sets of light sensors and lenses to obtain the function of dual-resolution. These Taiwanese patent references also disclosed the use of reflection mirror and lenses, and the masks to change the paths of the light so as to have dual-resolution features.  
           [0004]    The devices mentioned employ multiple sets of lenses and sensors and which increase manufacturing cost. The resolution is limited by the number of the sets of the sensors and the lenses so that the present scanners cannot meet the requirements of increase of the resolution for the needs of the market.  
           [0005]    Besides, the distance between the lenses module and the light sensors has to be micro-adjusted when using the change of the light paths to have multiple resolutions so as to obtain better focused images. It is not satisfied to drive the parts to adjust the distance simply by using a driving device and this way cannot focus precisely.  
         SUMMARY OF THE INVENTION  
         [0006]    The primary object of the present invention is to provide a multi-resolution scanning device having an auto-focus function. The device employs a light path changing device to change the paths of light of the images and the scanning device to scan a standard pattern. A precisely focused image is obtained by micro-adjusting the scanned image according the result of the scanning of the standard pattern.  
           [0007]    The other object of the present invention is to provide a method for automatically focusing an object by adjusting the image according a standard pattern.  
           [0008]    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, a preferred embodiment in accordance with the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is an illustrative view showing the principle for obtaining an image of the present invention;  
         [0010]    [0010]FIG. 2 is a perspective view showing the final light path changing device of the present invention;  
         [0011]    [0011]FIGS. 3A to  3 C are illustrative views showing the first light path of the final light path changing device of the present invention;  
         [0012]    [0012]FIG. 4 is an illustrative view showing the second light path of the final light path changing device of the present invention;  
         [0013]    [0013]FIG. 5 is a perspective view showing another embodiment of the final light path changing device of the present invention;  
         [0014]    [0014]FIGS. 6A and 6B are illustrative views showing the third light path of the final light path changing device of the present invention;  
         [0015]    [0015]FIGS. 7A and 7B are illustrative views showing the fourth light path of the final light path changing device of the present invention;  
         [0016]    [0016]FIGS. 8A to  8 C are illustrative views showing the fifth light path of the final light path changing device of the present invention;  
         [0017]    [0017]FIG. 9 is an illustrative view showing the sixth light path of the final light path changing device of the present invention;  
         [0018]    [0018]FIGS. 10A and 10B are illustrative views showing the seventh light path of the final light path changing device of the present invention;  
         [0019]    [0019]FIGS. 11A and 11B are illustrative views showing the eighth light path of the final light path changing device of the present invention;  
         [0020]    [0020]FIG. 12 is a perspective view showing a preferred embodiment of the scanning device;  
         [0021]    [0021]FIG. 13 shows an embodiment of the standard pattern of the marked area on the calibration sheet;  
         [0022]    [0022]FIG. 14 shows a flow chart of the auto-focusing method of the present invention; and  
         [0023]    [0023]FIG. 15 shows another flow chart of the auto-focusing method of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    Referring to FIG. 1, the images of the original document  1  is focused onto a sensor  2  by a lens  3 . The distance between an object a is designated by “p” which means a path of light between the original document  1  and the lens  3 . The distance between the image and the lens  3  is designated by “q” which means a path of light between the sensor  2  and the lens  3 . The focus of the lens  3  is designated by “f”. An equation for obtaining an image is expressed by 1/p+1/q=1/f. The definition of magnifying rate is M=q/p and the path of light is designated by T=p+q.  
         [0025]    Accordingly, the magnifying rate can be increased by shortening “p” or “T”.  
         [0026]    When “p” is shortened, the image of the original document  4  as shown by dotted lines is focused onto the sensor  2  by the lens  3  as shown by dotted lines. The magnifying rate is increased with the shortening of the distance between the original document  4  and the lens  3 . In order to meet the equation mentioned above, the distance “q” between the image and the lens 3 has to be adjusted to be “q′” so as to have a better focused result.  
         [0027]    The distance “p” is changed to be “q′”, and “p′” is less than “p”. The distance “q” between the image and the lens  3  is changed to be “q′” (the change between the q and q′ is obtained by changing the distance between the lens and the position of the final image, and q′ is close to q). The final M′(=q′/p′) is larger than the original M (=q/p).  
         [0028]    Briefly, if the original document  1  has an 8-inch width and the sensor  2  has 9600 sensing units, the image information of the 8-inch is recorded into the 9600 sensing units and has a resolution of 1200 dpi. If the original document  4  has a 4-inch width, the image information of the 4-inch width is recorded into the 9600 sensing units to have a resolution of 2400 dpi.  
         [0029]    The principle of the present invention is to adjust the light path to increase the magnifying rate M and the resolution, and will be described hereinafter.  
         [0030]    Device for Changing Light Path: Light Path Changing Device  
         [0031]    First Embodiment: To Change The Status of Light Folding Device  
         [0032]    Referring to FIG. 2, a light folding device  12  is pivotally connected to a base  11  and a final reflection mirror unit  13  which includes at least one reflection mirror is located beside the light folding device  12 . A lens module  14  and a sensor  15  are located in the light path of the final reflection mirror unit  13 .  
         [0033]    The light folding device  12  is snugly fixed to the base  11  by welding at one end. The light folding device  12  may also be pivotally connected to the base  11 . It is noted that the light folding device  12  can be rotated relative to the base  11  even though the light folding device  12  is welded to the base  11  at one end. The lens module  14  is driven along the arrow as shown by a driving device  16  which can be a motor or a solenoid valve. The light folding device  12  is driven an angle by an angular driving device  18  which can be an assembly of a motor, a worm gear and a worm screw, an solenoid valve, or other equivalent devices).  
         [0034]    As shown in FIGS. 2 and 3A, the light folding device  12  is composed of a first reflection mirror  21  and a second reflection mirror  22  which is located in opposite to the first reflection mirror  21 . The first reflection mirror  21  and the second reflection mirror  22  can be a single flat reflection mirror, and the two reflection mirrors  21 ,  22  face with each other.  
         [0035]    As shown in FIG. 3A, the optical image obtained by scanning a document is defined to be the image information  41  which is introduced into the light folding device  12  so that the image information  41  is reflected between the first reflection mirror  21  and the second reflection mirror  22  of the light folding device  12 .  
         [0036]    After the image information  41  passed through the light folding device  12 , it is reflected by the final reflection mirror unit  13  and received by the sensor  15  via the lens module  14 .  
         [0037]    As shown in FIGS. 2 and 3B, when the light folding device  12  is rotated by the angular driving device  18 , reflection paths of the image information  41  between the final reflection mirror unit  13  and the light folding device  12  will change so as to reduce the total light path of the image information  41 . The distance between the lens module  14  and the light sensor  15  has to be adjusted to have a precise focus.  
         [0038]    Referring to FIG. 3C, the light path of the image information  41  can also be changed simply by rotating the second reflection mirror  22  in the light folding device  12 .  
         [0039]    Referring to FIG. 4, the first reflection mirror  21  and the second reflection mirror  22  in the light folding device  12  can also be composed of a plurality of sub-reflection mirrors  42  and  43 . The light path is adjusted by rotating the sub-reflection mirrors  42  and  43 , or by rotating one of the sub-reflection mirrors  42  and  43 .  
         [0040]    The light path of the image information  41 , coming from the light folding device  12  and the final reflection mirror unit  13  and reaching the lens module  14 , cooperates with the distance between the lens module  14  and the sensor  15  to change the scanning resolution. This technique is familiar to one in the art and will not be described further.  
         [0041]    The following ways can change the distance between the lens module  14  and the sensor  15 :  
         [0042]    1. to adjust either one of the lens module  14  or the sensor  15 ;  
         [0043]    2. to adjust the lens module  14  and the sensor  15  simultaneously, and then to adjust either one of the lens module  14  or the sensor  15 .  
         [0044]    Second Embodiment: To Change the Status of the Final Reflection Mirror Unit  
         [0045]    Referring to FIG. 5, a light folding device  12  is pivotally connected to a base  11  and a final reflection mirror unit  13  which includes at least one reflection mirror is located beside the light folding device  12 . A lens module  14  and a sensor  15  are located in the light path from the final reflection mirror unit  13 .  
         [0046]    The light folding device  12  is snugly fixed to the base  11  by welding. The light folding device  12  may also be pivotally connected to the base  11 . It is noted that the light folding device  12  can be rotated relative to the base  11 . The lens module  14  is driven along the arrow as shown by a driving device  16  which can be a motor or a solenoid valve.  
         [0047]    Referring to FIGS. 5 and 6A, the light folding device  12  is composed by a first reflection mirror  21  and a second reflection mirror  22  which is located in opposite to the first reflection mirror  21 . The first reflection mirror  21  and the second reflection mirror  22  can be a single flat reflection mirror, and the reflection surface  23  of the first reflection mirror  21  faces the reflection surface  24  of the second reflection mirror  22 .  
         [0048]    The final reflection mirror unit  13  is composed of a first reflection mirror  25  and a second reflection mirror  26  (the first reflection mirror  25  and the second reflection mirror  26  are regarded as the final reflection mirror unit  13 ). The first reflection mirror  25  is driven by a solenoid valve, a motor, or other equivalent devices (not shown) to be movably installed beside the light folding device  12 . The reflection surface  27  of the first reflection mirror  25  faces the light folding device  12 . The second reflection mirror  26  is fixedly positioned beside the light folding device  12 . The reflection surface  28  of the second reflection mirror  26  faces to the light folding device  12  and the lens module  14  at a fixed angle.  
         [0049]    As shown in FIG. 6A, the optical image obtained by scanning a document is defined to be the image information  41  which is introduced into the light folding device  12  so that the image information  41  is reflected between the first reflection mirror  21  and the second reflection mirror  22  of the light folding device  12 .  
         [0050]    After the image information  41  passed through the light folding device  12 , it is reflected by the second reflection mirror  26  and received by the sensor  15  via the lens module  14 .  
         [0051]    As shown in FIGS.  6 B, when the first reflection mirror  25  of the final reflection mirror unit  13  is moved in front of the reflection surface of the second reflection mirror  26  as shown in the drawing, reflection paths of the image information  41  in the light folding device  12  will change so as to reduce the total light path of the image information  41 . The distance between the lens module  14  and the light sensor  15  has to be adjusted to have a precise focus.  
         [0052]    Referring to FIGS. 7A and 7B, the first reflection mirror  21  in the light folding device  12  is composed of a plurality of sub-reflection mirrors  31 . The second reflection mirror  22  in the light folding device  12  is composed of a plurality of sub-reflection mirrors  32 . The sub-reflection mirrors  31  and  32  are located in opposite to the reflection surfaces  33  and  34 . The final reflection mirror unit  13  is composed of a sub-reflection mirror  31  and reflection mirror  35 . When the status of the final reflection mirror unit  13  is changed, the sub-reflection mirror  31  of the final reflection mirror unit  13  is moved to the position as shown in FIG. 7B so as to change the light path of the image information  41 .  
         [0053]    As shown in FIGS. 8A, 8B and  8 C, the final reflection mirror unit  13  is composed of a first reflection mirror  25  and a second reflection mirror  26 . The change of the relative positions between the two reflection mirrors  25  and  26  can adjust the light path of the image information  41 .  
         [0054]    [0054]FIG. 9 shows that the final reflection mirror unit  13  is composed of a reflection mirror  25  and the image information  41  is reflected from the reflection surface  36  to the lens module  14  by rotating the reflection mirror  35  to adjust the light path of the image information  41 .  
         [0055]    [0055]FIGS. 10A and 10B show that the final reflection mirror unit  13  is composed of a movable first reflection mirror  25  and a fixed second reflection mirror  26 . The first reflection mirror  25  is located between the first reflection mirror  21  and the second reflection mirror  22 . When the light path is adjusted, the first reflection mirror  25  is rotated to the position shown in FIG. 10B to let the image information  41  be reflected from the reflection surface  27  to the lens module  14 .  
         [0056]    Referring to FIGS. 11A and 11B, the final reflection mirror unit  13  can be composed of a movable reflection mirror  35  so that the final reflection mirror  35  may be moved to adjust the light path of the image information  41 .  
         [0057]    Besides, the following ways can be employed to adjust the distance between the lens module  14  and the sensor  15 :  
         [0058]    1. to adjust either one of the lens module  14  or the sensor  15 ;  
         [0059]    2. to adjust the lens module  14  and the sensor  15  simultaneously, and then to adjust either one of the lens module  14  or the sensor  15 .  
         [0060]    Furthermore, in addition to adjusting the distance between the lens module  14  and the sensor  15 , using a lens module having variable focus can also achieve the same function.  
         [0061]    Structure and Method to Automatically Focus  
         [0062]    1. Structure:  
         [0063]    Referring to FIG. 12, the scanner is a preferred embodiment of the present invention. The scanner includes a casing  51 , a scanning platform  52 , a top cover  53 , a calibration sheet  54 , and a marked area  55 . The calibration sheet  54  is received in the casing  51  and, for those who familiar to the related knowledge, the calibration sheet  54  is used to correct or compensate for the color and brightness of the scanning light source (not shown) in the scanner. There is a specific pattern on the calibration sheet  54  and which is used to judge the start point of the scanning.  
         [0064]    Nevertheless, besides the purposes mentioned above, the calibration sheet  54  of the present invention has the marked area  55  for convenience of automatically focusing.  
         [0065]    [0065]FIG. 13 shows the embodiment of the standard pattern  56  in the marked area  55  on the calibration sheet  54 . However, it is not the limitation of the scope of the present invention, any known pattern, even the colorful pattern is located in the scope of the pattern  56  of the present invention.  
         [0066]    In addition to the standard pattern  56  as mentioned above, the database can be established in which the physical characters of the standard pattern  56  such as color, brightness, contrast and sizes, and the extreme acceptable values (pre-set range) of the physical characters are received.  
         [0067]    2. Method for Automatically Focusing  
         [0068]    [0068]FIG. 14 shows the flow chart of the method for automatically focusing of the present invention.  
         [0069]    Step S 61 : Starting to scan.  
         [0070]    Step S 62 : Adjusting the light path by adjusting the positions or the angles of the light folding device  12  or the final reflection mirror unit  13 . In other words, to change the number of reflection times of the image information  41  in the light folding device  12  and the final reflection mirror unit  13 .  
         [0071]    Step S 63 : Responsive to the adjustment in the step  62 , the distance between the sensor  15  and the lens module  14  is roughly adjusted.  
         [0072]    Step S 64 : Scanning the standard pattern  56  to obtain the physical characters of the standard pattern  56 .  
         [0073]    Step S 65 : Judging the physical characters (such as width, color, brightness) of the scanned standard pattern to be located in the pre-set range.  
         [0074]    Step S 66 : if the result from step S 65  is NO, adjusting the distance between the sensor  15  and the lens module  14  according to the physical characters and the information in the database.  
         [0075]    Step S 67 : if the result from step S 65  is YES, the action of focusing is finished.  
         [0076]    It is to be noted that the route can be returned to step S 65  as shown in the solid route line after the step S 66  is finished so as to proceed even more precise adjustment, or directly skip to step S 67  as shown in dotted route line so as to save time.  
         [0077]    For instance, the following is a description for proceeding the step S 65  for the physical characters (such as color, brightness, contrast) of the standard pattern.  
         [0078]    Referring to FIG. 13 again, the standard pattern  56  has multiple lines and if the standard pattern  56  is not properly focused, the physical characters between the two lines on the sensor  15  will not the same as the experimental or theoretical value. The experimental or theoretical value can be set by the manufacturers and memorized as a database. The range around the experimental value can also be set by the manufacturers and is memorized as a database. Therefore, it is convenient for the scanner to adjust the parts by using the database.  
         [0079]    In addition, the database may have the distance (or the reference for adjusting the zoom lens) between the lens module  14  and the sensor  15  corresponding to the physical characters of the result scanned by the sensor  15 . An example is provided in Table 1: 
                   TABLE 1                       The physical characters of the result   the distance between the lens       scanned by the sensor   module and the sensor                   A1   B1       A2   B2       A3   B3       . . .   . . .       An   Bn                  
 
         [0080]    By this way, the focusing process can be easily finished.  
         [0081]    It is noted that the marked area  55  is not necessarily located on the center of the calibration sheet  54 , the marked area  55  can also be located on two sides or any position. The standard pattern  56  is not necessarily straight lines, any known algebra pattern can also be acceptable.  
         [0082]    It is noted that the marked area  55  is not necessarily located on the center of the calibration sheet  54 , it can also be located in the casing or on the glass plate.  
         [0083]    Referring to FIG. 15, another focus method is provided in the flowing chart. In the embodiment, a zoom lens module is employed so that the step S 63  and step S 66  are different from those in FIG. 14. This embodiment uses the adjustment of the focus distance of the lens module to replace the adjustment of the distance between the lens module and the sensor. It is understandable for those skilled persons in the art. The rest of the steps are the same as shown in FIG. 14.  
         [0084]    The structure and the method employ a standard pattern on the scanner to proceed the function of automatically focusing. The function of the automatically focusing is not necessarily limited in increasing resolution and can be used in reducing resolution.  
         [0085]    In order to define clearly in the following claims, the light folding device  12  and the final reflection mirror unit  13  are termed as a final light path changing device. The final light path can be changed by changing the light folding device  12  and the final reflection mirror unit  13 . For those skilled persons in the art, other final light path changing device can be used besides the light folding device  12  and the final reflection mirror unit  13 .  
         [0086]    While we have shown and described the embodiment 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.