Patent Publication Number: US-2009219587-A1

Title: Scanner and homing method of scanning module thereof

Description:
This application claims the benefit of Taiwan application Serial No. 97107194, filed Feb. 29, 2008, the subject matter of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to a scanner and a homing method of a scanning module thereof, and more particularly to a scanner capable of homing and a homing method of a scanning module thereof. 
     2. Description of the Related Art 
     Along with the rapid advance in technology, the scanner application has become popular. The scanner includes a scanning platform and a scanning module. The scanning module is disposed under the scanning platform. When a user would like to scan a document, the document is placed on the scanning platform. Then, the scanning module is moved along a direction to capture the image of the document. 
     Generally speaking, the scanning module is homed to a specific position firstly before scanning begins so as to scan the document from a start line. Therefore, the complete contents of the document are captured by the scanning module. However, the scanning module is not always precisely homed to the specific position, so that the scanning module may only capture a partial image of the document or even capture the image of other object. Accordingly, the scanning quality of the scanner is reduced to lower the convenience in use. 
     Conventionally, a homing structure is used as a basis for homing a scanning module. Referring to  FIG. 1 , a conventional homing structure is shown. The homing structure  70  is used for being disposed on a casing (not illustrated) of a scanner (not illustrated). The homing structure  70  includes a white plate  71  and a black pattern  72  (the portion in  FIG. 1  with slanting lines). The black pattern  72  covers the white plate  71  by a printing process. After a scanning module (not illustrated) of the scanner captures an image of the homing structure  70 , the boundary between the black pattern  72  and the white plate  71  is used as a basis for homing the scanning module. 
     However, as the black pattern  72  covers the white plate  71  by the printing process which is complicated and costly, the disposition of black pattern  72  usually increases the cost and complexity in manufacturing the homing structure  70 . Therefore, how to design a scanner capable of precisely homing to lower the cost and complexity in manufacturing and increase the scanning quality has become an imminent issue to the manufacturers. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a scanner and a homing method of a scanning module thereof. A positioning plate cooperates with a casing of the scanner to be used as a basis for homing the scanning module. Thus, the scanning module can be precisely homed, so that an image of a to-be-scanned document can be completely captured and the scanning quality is improved correspondingly. In addition, compared with a conventional homing structure, the positioning plate of the invention does not need to form any patterns thereon by a printing process. Therefore, the cost and complexity of the positioning plate of the invention in manufacturing are less than those of the conventional homing structure. 
     According to a first aspect of the present invention, a scanner including a casing, a scanning platform, a scanning module and a positioning plate is provided. The scanning platform is embedded in the casing and exposes a surface to carry a to-be-scanned document. The scanning platform includes a top side. The scanning module is disposed under the scanning platform. The positioning plate is disposed on an inner wall of the casing and is adjacent to the top side of the scanning platform. The scanning module is used for capturing images of the positioning plate and the inner wall and for identifying the image corresponding to at least one x-axis side of the positioning plate. A scanning start line is defined by the scanner according to the image corresponding to the x-axis side. The scanning module is moved from the scanning start line along a y-axis direction and captures an image of the to-be-scanned document. The x-axis side and the scanning start line are substantially perpendicular to the y-axis direction. The y-axis direction is substantially perpendicular to the top side. 
     According to a second aspect of the present invention, a homing method of a scanning module of a scanner is provided. The method includes the following steps. Firstly, images of a positioning plate and an inner wall of a casing of the scanner are captured. The positioning plate is disposed on the inner wall of the casing and is adjacent to a top side of the scanning platform of the scanner. Next, the image corresponding to at least one x-axis side of the positioning plate is identified. Then, a scanning start line is defined according to the image corresponding to the x-axis side. The scanning module is moved from the scanning start line along a y-axis direction and captures an image of a to-be-scanned document. The x-axis side and the scanning start line are substantially perpendicular to the y-axis direction. The y-axis direction is substantially perpendicular to the top side. 
     The invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  (Prior Art) shows a conventional homing structure; 
         FIG. 2A  shows a top view of a scanner according to a preferred embodiment of the invention; 
         FIG. 2B  shows a cross-sectional view of the scanner taken along line  2 B- 2 B in  FIG. 2A ; 
         FIG. 3A  shows another positioning plate disposed in a recess of a casing; 
         FIG. 3B  shows a cross-sectional view of the scanner taken along line  3 B- 3 B in  FIG. 3A ; 
         FIG. 4A  shows a top view of yet another positioning plate disposed on a casing of a scanner; 
         FIG. 4B  shows a cross-sectional view of the scanner taken along line  4 B- 4 B in  FIG. 4A ; and 
         FIG. 5  shows an example of a flowchart of a homing method of the scanning module in  FIG. 2A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 2A  and  FIG. 2B , a top view of a scanner according to a preferred embodiment of the invention is shown in  FIG. 2A , and a cross-sectional view of the scanner taken along line  2 B- 2 B in  FIG. 2A  is shown in  FIG. 2B . The scanner  100  includes a casing  110 , a scanning platform  130 , a scanning module  150  and a positioning plate  170 . The scanning module  150  is, for example, a device including a charge-coupled device (CCD) or a device including a contact image sensor (CIS). 
     The scanning platform  130  is embedded in the casing  110  and exposes a surface  133  to carry a to-be-scanned document (not illustrated). The scanning platform  130  includes a top side  131 . The scanning module  150  is disposed under the scanning platform  130 . The positioning plate  170  is disposed on an inner wall  111  of the casing  110  and is adjacent to the top side  131  of the scanning platform  130 . The scanning module  150  is used for capturing images of the positioning plate  170  and the inner wall  111  of the casing  110  and for identifying the image corresponding to at least one x-axis side of the positioning plate  170 . It is illustrated in the following embodiment of the invention that the images identified by the scanning module  150  correspond to x-axis sides sx 1  and sx 2 . A scanning start line P is defined by the scanner  100  according to the images corresponding to the x-axis sides sx 1  and sx 2 . The scanning module  150  is moved from the scanning start line P along a y-axis direction and captures an image of the to-be-scanned document. 
     The relationships among the x-axis sides sx 1  and sx 2 , the y-axis direction, the scanning start line P and the top side  131  are disclosed below. The x-axis sides sx 1  and sx 2  and the scanning start line P are substantially perpendicular to the y-axis direction. The y-axis direction is substantially perpendicular to the top side  131 . In addition, the exemplified x-axis sides sx 1  and sx 2  are spaced at an interval d in the y-axis direction, but the invention is not limited thereto. The two x-axis sides used for defining the scanning start line P do not have to be separated in the y-axis direction. 
     Thus, through the cooperation of the positioning plate  170  and the inner wall  111  of the casing  110 , the scanning module  150  of the scanner  100  can be homed precisely to be moved from the scanning start line P along the y-axis direction and completely capture the image of the to-be-scanned document. 
     The scanner  100  of the present embodiment of the invention is further elaborated below. As indicated in  FIG. 2A , the positioning plate  170  has a body  171  and several rectangular structures  173  (only one of the rectangular structures is numbered in  FIG. 2A ). The rectangular structure  173  protrudes from the body  171  in the direction which is substantially parallel to the y-axis direction. The x-axis sides sx 1  and sx 2  are one side of the body  171  and one side of the rectangular structure  173 , respectively. As the rectangular structure  173  protrudes from the body  171 , the x-axis sides sx 1  and sx 2  are spaced at the interval d. Despite the x-axis sides sx 1  and sx 2  separated at the interval d are used as bases for homing the scanning module  150 , the basis for homing the scanning module  150  in the present invention is not limited thereto. At least one x-axis side which is substantially perpendicular to the y-axis direction can be used as a basis for homing the scanning module  150 . 
     In order to clearly identify the images corresponding to the x-axis sides sx 1  and sx 2  of the positioning plate  170 , the color of the positioning plate  170  is different from that of the inner wall  111  of the casing  110 . Thus, the scanning module  150  identifies the images corresponding to the x-axis sides sx 1  and sx 2  of the positioning plate  170  to be bases for homing according to the different colors between the positioning plate  170  and the inner wall  111 . The color of the inner wall  111  of the casing  110  is, for example, gray or black, and the color of the positioning plate  170  is, for example, white. However, the invention is not limited thereto. Any colors enabling the scanning module  150  to clearly identify the image corresponding to the x-axis side of the positioning plate  170  can be used as the colors of the positioning plate  170  and the inner wall  111  of the casing  110 . 
     Moreover, black calibration can be performed to the scanning module  150  according to the color characteristics of the inner wall  111  of the casing  110 . Generally speaking, when black calibration is performed to a scanning module of a scanner, a light source of the scanner needs to be turned on or turned off. When black calibration is performed to the scanner  100  by way of turning on the light source, a luminosity of the inner wall  111  of the casing  110  needs to be smaller than a black default value (such as value 100 defined by firmware). Thus, when the color of the inner wall  111  of the casing  110  is selected, apart from enabling the scanning module  150  to identify the image corresponding to the x-axis side of the positioning plate  170 , the condition that the inner wall  111  is applied to black calibration can also be taken into consideration. Accordingly, when the light source of the scanner  100  is turned on, black calibration can be performed to the scanning module  150  according to the luminosity of the inner wall  111 . 
     According to the images of the positioning plate  170  and the inner wall  111  of the casing  110  captured by the scanning module  150 , the scanning module  150  further identifies the images corresponding to the y-axis sides (such as the y-axis sides sy 1  and sy 2 ) of the positioning plate  170 . The y-axis sides sy 1  and sy 2  are substantially perpendicular to the x-axis sides sx 1  and sx 2  and are respectively located at two sides of the positioning plate  170 . The scanning module  150  is homed according to the images corresponding to the y-axis sides sy 1  and sy 2  so as to capture the image of the to-be-scanned document located between two boundaries such as boundaries B 1  and B 2 . Thus, the condition that unnecessary images or only a portion of the contents of the to-be-scanned document are captured can be avoided. 
     Despite the present embodiment is exemplified by the positioning plate  170  in  FIG. 2A , anyone who is skilled in the art will understand that the disposition or the shape of the positioning plate is not limited thereto. Any positioning plate enabling the scanning module to capture the image of the positioning plate as a basis for homing would do. 
     Referring to  FIG. 3A  and  FIG. 3B , another positioning plate disposed in a recess of a casing is shown in  FIG. 3A , and a cross-sectional view of the scanner taken along line  3 B- 3 B in  FIG. 3A  is shown in  FIG. 3B . The inner wall  111 ′ of the casing  110 ′ of the scanner  100 ′ has a recess  113 ′. Through the indentation design of the recess  113 ′, the positioning plate  170 ′ is precisely disposed in the recess  113 ′. Thus, the error in the homing of the scanning module  150 ′ caused by the position of the positioning plate  170 ′ can be reduced. Furthermore, the positioning plate  170 ′ can be disposed as indicated in  FIG. 3A . That is, the direction that the rectangular structure  173 ′ protrudes from the body  171 ′ is different from the direction that the rectangular structure  173  (illustrated in  FIG. 2A ) protrudes from the body  171  (illustrated in  FIG. 2A ). 
     Referring to  FIG. 4A  and  FIG. 4B , a top view of yet another positioning plate disposed on a casing of a scanner is shown in  FIG. 4A , and a cross-sectional view of the scanner taken along line  4 B- 4 B in  FIG. 4A  is shown in  FIG. 4B . The positioning plate  170 ″ of the scanner  100 ″ has several square holes  175 ″ (only one of the square holes is numbered in  FIG. 4A ). The square hole  175 ″ penetrates the positioning plate  170 ″ so as to expose the inner wall  111 ″ of the casing  110 ″. The positioning plate  170 ″ further has four inner sides. At least one of the inner sides, such as the x-axis side sx 1 ″ or the x-axis side sx 2 ″, can be used as a basis for homing the scanning module  150 ″. 
     Apart from using the x-axis sides and the y-axis sides of the positioning plate as bases for homing, the scanning module can further use the ordinal number of the pixels of the captured image as a basis for homing. Thus, the homing of the scanning module is more precise so as to improve the homing precision. 
     Please refer to  FIG. 2A ,  FIG. 2B  and  FIG. 5  at the same time.  FIG. 5  shows an example of a flowchart of a homing method of the scanning module in  FIG. 2A . Despite the homing method of a scanning module of a scanner of the invention is exemplified by the scanner  100  in  FIG. 2A  and  FIG. 2B  and the flowchart in  FIG. 5 , anyone who is skilled in the art will understand that the steps and the sequence of the homing method of a scanning module of a scanner of the invention are not limited to that illustrated in the flowchart in  FIG. 5 . 
     In the following example of homing the scanning module  150 , the scanning module  150  is moved from the scanning start line P along the y-axis direction and captures the image of the to-be-scanned document located between the two boundaries B 1  and B 2 . 
     Firstly, in the step  301 , the images of the positioning plate  170  and the inner wall  111  of the casing  110  of the scanner  100  are captured. As indicated in  FIG. 2A , the positioning plate  170  has the body  171  and several rectangular structures  173 . Thus, in the step  301 , the images of the inner wall  111  of the casing  110  and the body  171  and the rectangular structure  173  of the positioning plate  170  are captured concurrently. 
     Next, in the step  303 , the images corresponding to at least one x-axis side (such as the x-axis sides sx 1  and sx 2 ) and two y-axis sides (such as the y-axis sides sy 1  and sy 2 ) of the positioning plate  170  are identified. In the step  303 , the images corresponding to the x-axis sides sx 1  and sx 2  and the y-axis sides sy 1  and sy 2  of the positioning plate  170  are identified according to the different colors of the positioning plate  170  and the inner wall  111  of the casing  110 . The y-axis sides sy 1  and sy 2  are substantially perpendicular to the x-axis sides sx 1  and sx 2 . 
     Then, in the step  305 , the scanning module  150  is homed according to the images corresponding to the x-axis sides sx 1  or sx 2  and the y-axis sides sy 1  and sy 2  so as to move from the scanning start line P along the y-axis direction and capture the image of the to-be-scanned document located between the two boundaries B 1  and B 2 . 
     The flowchart in  FIG. 5  is merely an example of the homing method of the scanning module of the invention, and the invention is not limited thereto. The homing method of the scanning module of the invention can also be applied to the scanner in  FIG. 3A  or  FIG. 4A  for homing the scanning module. 
     According to the scanner and the homing method of the scanning module thereof disclosed in the above embodiment of the invention, the positioning plate cooperates with the inner wall of the casing so as to use the image corresponding to the side of positioning plate as a basis for homing the scanning module. Thus, the scanning module can be precisely homed, so that the image of a to-be-scanned document can be completely captured to improve the scanning quality correspondingly. Compared with conventional homing structure, the positioning plate of the embodiment does not need to form any patterns thereon by a printing process. Thus, the positioning plate of the embodiment has lower cost and complexity in manufacturing. 
     While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.