Abstract:
A sheet-fed scanning device with cleaning mechanism is provided. The sheet-fed scanning device includes a housing, a scanning module for scanning a fed-in document, and a cleaning curtain whose one end is fixed on the sheet-fed scanning device. The cleaning curtain is disposed in a sheet-fed direction at the front end of the scanning module, and the edge of the other end of the cleaning curtain is elastically in contact with the fed-in document for cleaning a to-be-scanned surface of the fed-in document. The invention is simple in structure and effective in cleaning the fed-in document. The cleaning mechanism does not cost much, but avoids the scanning quality being affected due to the large friction of the cleaning element. The cleaning mechanism ensures long-term cleanness of the to-be-scanned surface of the fed-in document as well as the cleanness of the glass window of the scanning module and the scanning quality.

Description:
This application claims the benefit of Taiwan application Serial No. 200810021165.1, filed Aug. 15, 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 scanning device or auxiliary device of the scanning device, and more particularly to a sheet-fed scanning device with cleaning mechanism for cleaning the fed-in document in a sheet-fed scanning device. 
     2. Description of the Related Art 
     Scanner is a widely used electronic input device. Critical parts of a scanner include a scanning module and a mechanic transmission portion. A sheet-fed scanner whose mechanic transmission portion has simple structure embodies the design of a small-sized portable scanning input device. The sheet-fed scanner normally adopts a contact image sensor (CIS) being still with respect to the body of the scanner, and the fed-in document is scanned by way of being moved with respect to the scanner body. Such way of scanning is applicable to a small-sized portable scanner in scanning a small-sized document such as photo, receipt, business card and other types of cards. 
       FIG. 1  shows a cross-sectional structure of a generally known portable scanner  100  when scanning a fed-in document. The portable scanner performs scanning with a CIS scanning module  130  being still with respect to the scanner body  110 . A fed-in document  160  is placed on a document supporter  170  of a fed-in document entrance  120 . The fed-in document  160  is conveyed by a mechanic transmission portion in the direction of an arrow illustrated in  FIG. 1 . The CIS scanning module  130  fixed inside the scanner body  110  is located above the fed-in document  160 . The fed-in document  160  is driven by a sheet-feeding roller  140  of a document conveying mechanism. During the process of scanning, the fed-in document  160  enters the scanner via the fed-in document entrance  120  and is outputted from the fed-in document exit  150 . The CIS scanning module  130  obtains a scanned data of the fed-in document  160  through the glass window  131 . The portable scanner  100  is used for scanning many different types of documents, which inevitably have dust, liquid or other adhesive substances attached thereon. Let the scanned document be exemplified by a photo. Due to the adhesion characteristics of the surface of the scanned photo, it is very likely that the dust or the adhesive substances are carried to the surface of the glass window  131  of the CIS scanning module together with the fed-in photo during the scanning process. The dust or the adhesive substances that are attached or adhered onto the glass window  131  are hard to be removed. The glass window is a critical element with which the scanner obtains a scanned image. If the dust or the adhesive substances are attached or adhered onto the glass window, the scanning module will be beclouded, and the part of the fed-in document corresponding to the beclouded part will not be precisely scanned or will be scanned as a peculiar strip. As the scanning module is fixed on the scanner body, the glass window is hard to be cleaned. Meanwhile, the dust or the adhesive substances are also very likely to be attached or adhered on the feeding roller that drives the fed-in document, and further affect the normal operation of the rollers. 
     In order to remove the dust or the attached substances from the fed-in document, to improve scanning quality and to maintain the cleanness of the scanning module and the glass window, according to modern technology, a cleaning member parallel to the fed-in document is installed on the document supporter for cleaning the dust or the attached substances by means of surface friction which occurs between the cleaning member and the fed-in document. However, the above mechanism design has many defects. Firstly, the cleaning member is disposed at one side of the to-be-scanned surface and is hard to be fixed. Secondly, if the surface friction occurring between the cleaning member and the fed-in document is larger, the fed-in document will encounter a large resistance when the fed-in document is being fed in, and the scanning speed of the scanning module will lose its stability. As a result, problems such as extension and distortion in the scanned image will occur. Also, if the frictional resistance is too large, the surface of a dedicate fed-in document such as photo may be scratched. To the worse, if the pulling force between the feeding roller and the cleaning member is too large, the fed-in document may even be damaged or torn apart. On the other hand, as the cleaning member must be fixed, the dust and impurities once being attached or adhered onto the cleaning end of the cleaning member are hard to be cleaned. The dust and impurities may even be consolidated as big pellets. If the pellets come off the cleaning end and are carried to the glass window of the scanning element together with the fed-in document, severe scanning defects would occur. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a sheet-fed scanning device with cleaning mechanism for cleaning a to-be-scanned surface of the fed-in document. The sheet-fed scanning device with cleaning mechanism has reasonable design in the structure and is effective in cleaning the dust, which is carried by the fed-in document and affects the correct scanning of the glass window of the scanning module, to ensure long-term cleanness of the glass window of the scanning module and obtain a clear and correct scanned image. 
     The technology of the invention is disclosed below. 
     A sheet-fed scanning device with cleaning mechanism, including; 
     A housing; 
     A scanning module for scanning a fed-in document; 
     A cleaning curtain whose one end is fixed on the sheet-fed scanning device, wherein the cleaning curtain is disposed in a sheet-fed direction at the front end of the scanning module, and the edge of the other end of the cleaning curtain is elastically in contact with the fed-in document for cleaning a to-be-scanned surface of the fed-in document. 
     To put it in greater details, the cleaning curtain and the scanning module are located at the same side of the housing, the cleaning curtain is a flexible sheet, the upper end portion of the cleaning curtain is fixed on the inner wall of the housing, and the lower end portion of the cleaning curtain is located under the plane of the fed-in document, so that the lower end portion is bent and forms a linear contact with the fed-in document when the cleaning curtain is in contact with the fed-in document. 
     The cleaning curtain is perpendicular to the fed-in document or forms an obtuse angle with an out-going direction of the fed-in document. 
     The cleaning curtain is fixed at the inner side of the housing of the scanner document feeding entrance, wherein the width of the cleaning curtain is equal to or larger than that of the transparent window of the scanning module. 
     The cleaning curtain includes a flexible plastics sheet made from rubber or foam, wherein the upper end portion of the cleaning curtain and the inner wall of the housing are integrally formed in one piece. 
     The cleaning curtain is a dual-layered composite structure of a flexible sheet and a soft cleaning member. 
     The cleaning curtain includes a hard or a flexible sheet, wherein the hard sheet or the flexible sheet is located at the lower end of the cleaning curtain, the upper end of the hard or the flexible sheet has a connecting element elastically connecting the hard or the flexible sheet to the housing. 
     The sheet-fed scanning device includes a fed-in surface for carrying the fed-in document, wherein the height of the cleaning curtain is larger than the distance between the upper end portion of the cleaning curtain and the fed-in surface, so that after the lower end portion of the cleaning curtain is bent, the lower end portion is elastically in contact with the fed-in document. 
     The cleaning curtain is fixed on the inner wall of the housing or the scanner fixing component at the front end of the scanning module. 
     A fixing element is disposed on the upper end portion of the cleaning curtain, wherein the fixing element includes an embedding portion or an engaging portion for attaching to the inner wall of the housing. 
     The sheet-fed scanning device with cleaning mechanism has very small resistance during the cleaning process. The cleaning curtain, forming a linear contact or approximately linear contact with the to-be-scanned surface of the fed-in document, has excellent performance and small resistance during the cleaning process. The cleaning curtain can be disposed in a sheet-fed direction at the front end of the scanning module of the scanning device and can be fixed with the scanner body. The width of the cleaning curtain is equal to or slightly larger than the scan width, so that the to-be-scanned surface of the fed-in document can be completely cleaned. The cleaning curtain can adopt a single-layered structure made from rubber sheet, foam sheet or other plastics sheet with elasticity, adopt a dual-layered or multi-layered composite structure, or adopt a composite dual-layered structure constituted by a hard plastics sheet and a soft material layer. The hard plastics sheet supports the cleaning curtain structure, and the soft material layer contacts and cleans the surface of the fed-in document. The cleaning curtain can be formed by an elastic plastic cleaning sheet whose one end is rubber and the other end is a composite structure constituted by an elastic sheet and a hard fixing sheet. The cleaning curtain can be a rectangular sheet or a sheet of another shape convenient for cleaning (for example, the vertical cross-section shows that the lower end portion is a blade edge). The upper end portion of the cleaning curtain, being fixed on the inner wall of the housing of the scanning device, can be disposed vertically or tilt to an angle. If the cleaning curtain tilts to an angle, the tilting direction of the cleaning curtain preferably forms an obtuse angle with the fed-in document. Thus, the lower end portion of the cleaning curtain naturally bends towards the out-going direction of the fed-in document, and the linear contact between one edge of the lower end portion and the to-be-scanned surface of the fed-in document can effectively clean the attached substance off the to-be-scanned surface to protect the glass window of the scanning module from being affected by the attached substance and maintain the cleanness of the glass window. 
     The cleaning curtain can be fixed at any position in front of the glass window of the scanning module according to the structure of the scanning device as long as the to-be-scanned surface of the fed-in document can be cleaned. As the scanning module of the sheet-fed scanning device is normally disposed above the document supporter, the cleaning curtain is also fixed at the upper end of the inner wall of the housing for cleaning the to-be-scanned surface of the fed-in document. The cleaning curtain can be fixed by way of bonding or being integrally formed with the housing in one piece or other fixing methods. For example, when a composite cleaning curtain is adopted, the cleaning curtain is constituted by two different materials, wherein the upper end of the cleaning curtain is an elastic element such as a metal elastic sheet, and the lower end of the cleaning curtain is a soft cleaning sheet, so that the metal elastic sheet can be hot-melted on the housing or the metal elastic sheet can be embedded into the inner wall of the housing. 
     Before operating the cleaning curtain, the lower end portion of the cleaning curtain is located under the to-be-scanned surface of the fed-in document so that when the fed-in document is fed into the scanning device, a certain level of pressure occurs between the lower end of the cleaning curtain and the fed-in document, such that the scanning curtain is naturally bent and friction which occurs during the cleaning process is small Thus, the structure of the cleaning curtain is ideal for self-cleaning. 
     The sheet-fed scanning device with cleaning mechanism is simple in structure, and is effective in cleaning the fed-in document. The cleaning mechanism does not cost much but avoids the scanning quality being affected due to the large friction of the cleaning element. The cleaning mechanism is applicable to all kinds of sheet-fed scanning devices to ensure long-term cleanness of the to-be-scanned surface of the fed-in document as well as the cleanness of the glass window of the scanning module and the quality of the scanned image. 
     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  shows a cross-sectional structure of a generally known sheet-fed scanning device; 
         FIG. 2  shows the structural working principle of the invention; 
         FIG. 3  shows a cross-sectional structure of a preferred embodiment of the invention; 
         FIG. 4  shows a cross-sectional structure of the scanning device of  FIG. 3  in use; 
         FIG. 5  shows a partial cross-sectional structure of an embodiment of a cleaning curtain the invention 
         FIG. 6  shows a cross-sectional structure of another embodiment of the invention; 
         FIG. 7  shows a cross-sectional structure of yet another embodiment of the invention; and 
         FIG. 8  shows a cross-sectional structure of further another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The working principle of the sheet-fed scanning device with cleaning mechanism is illustrated in  FIG. 2 . A CIS scanning module  230  is still with respect to the body of the sheet-fed scanning device. The front end of the scanning module  230  used for scanning the fed-in document  260  is driven by a sheet-feeding roller  240  for enabling a glass window  231  to perform linear scanning on the upper end of the fed-in document  260  and to obtain a scanned image. The cleaning curtain  250  is disposed in a sheet-fed direction at the front end of the scanning module  230 . When the lower end portion  252  of the cleaning curtain  250  is elastically in contact with the to-be-scanned surface of the fed-in document  260 , the cleaning curtain  250  removes objects such as the dust attached on the fed-in document to assure that the to-be-scanned surface is clean for avoiding the attached substance being adhered onto the glass window and affecting the quality of the scanned image. The upper end portion  251  of the cleaning curtain  250  is fixed on the housing of the scanning device. 
       FIG. 3  shows a cross-sectional structure of a preferred embodiment of the sheet-fed scanning device  200  with cleaning mechanism. The sheet-fed scanning device  200  is a small-sized portable scanner. A CIS scanning module  230  of the scanning device  200  is still with respect to the scanner body  210 . A sheet-feeding roller  240  is disposed under the CIS scanning module  230  for controlling the feeding speed of the fed-in document. A scanner document fed-in entrance  220  is close to a glass window  231  of the scanning module  230 . One end of the sheet-fed scanning device  200  is a document fed-in entrance  220  with a document supporter  270 , and the other end of the sheet-fed scanning device  200  is a fed-in document exit. A cleaning curtain  250  made of a rectangular sheet is disposed vertically and fixed on the inner wall of the housing of the scanning device. The cleaning curtain  250  is made from an elastic rubber sheet, wherein the upper end portion  251  of the cleaning curtain  250  is adhered to the housing of the scanning device. The housing around the document fed-in entrance  220  has a blocking portion  280  which forms the document fed-in entrance. The cleaning curtain  250  stays close to the inner wall of the upper end of the blocking portion  280 , and there is an adhesion fixing portion between the upper end portion  251  of the cleaning curtain  250  and the inner wall of the upper end of the blocking portion  280  for fixing the cleaning curtain  250  firmly. The cleaning curtain  250  is perpendicular to the upper end of the document supporter  270 . The width of the cleaning curtain  250  is equivalent to the maximum span of scanning of the scanner glass window  231  so that the cleaning curtain  250  is able to clean the entire to-be-scanned surface of the fed-in document. The height of the cleaning curtain  250  is larger than the distance between the inner wall of the housing and the fed-in surface formed on the document supporter  270 . 
       FIG. 4  shows a cross-sectional structure of a sheet-fed scanning device in use. A fed-in document  260  is fed into a document fed-in entrance  220  of the scanning device through a document supporter  270 . A lower end surface of the scanning module  230  and a sheet-feeding roller  240  together retain and move the fed-in document  260  towards a fed-in document exit. The scanning module  230  obtains a scanned image data of the fed-in document through a glass window  231 . An upper end portion  251  of a cleaning curtain  250  and an inner housing of the scanning device are adhered and fixed onto the top of the inner wall of a blocking portion  280  of the document fed-in entrance. The height of the cleaning curtain  250  is larger than the distance between the part of the housing, in which the cleaning curtain  250  is fixed, and the fed-in surface formed on the document supporter  270 . A lower end portion  252  of the cleaning curtain  250  is bent in a sheet-fed direction due to friction. As the ridge at the right-hand side of the lower end portion  250  is in full contact with the to-be-scanned surface of the fed-in document  260 , the substances attached on the to-be-scanned surface can be effectively cleaned. Thus, the to-be-scanned surface of any document passing through the cleaning curtain  250  is cleaned, and the substances attached on the fed-in document can hardly be adhered onto the glass window  231 . The problems of scanning defects and image errors, which arise when there are substances, such as dust, being attached on the glass window  231 , will not occur. To clean the cleaning curtain, the user only needs to open the housing at the front of the scanning device. 
     As for the material of the sheet used in the cleaning curtain  250 , the elastic rubber sheet can be replaced by a dual-layered flexible sheet. For example, the cleaning curtain can adopt the dual-layered flexible sheet illustrated in  FIG. 5 . The cleaning curtain  250  of  FIG. 5  is made from a composite structure constituted by two materials. The first layer  254  is a tough polypropylene thin sheet with strong supporting strength. The second layer  253 , being a piece of soft cleaning cotton or cleaning sheet made from foam material, is mainly used for cleaning. The first layer  254  and the second layer  253  are combined together to form the cleaning curtain  250 . In  FIG. 4 , the cleaning curtain can be alternatively formed in the manner that the first layer  254  is disposed at the left and the second layer  253  is disposed at the right. During the cleaning process, after the lower end portion of the cleaning curtain  250  is bent to the left, the second layer  253  approximately forms a linear contact with the to-be-scanned surface so as to clean the attached substance off the to-be-scanned surface. Meanwhile, the first layer  254  provides the second layer  253  with sufficient support such that the second layer  253  has a certain level of elastic resistance to assure the cleaning effect and the overall stability of the cleaning curtain. 
       FIG. 6  shows a cross-sectional structure of another embodiment of the invention. The scanning device  300  is a small-sized portable scanner whose CIS scanning module  330  is still with respect to the scanner body  310 . The right-hand side of the scanning device  300  is a document fed-in entrance  320  with a document supporter  370 , and the left-hand side is a fed-in document exit. The CIS scanning module  330  is disposed above the left-hand side of the document supporter  370 , and a glass window  331  downwardly faces a to-be-scanned surface of a fed-in document fed in through the document fed-in entrance  320 . A cleaning curtain  350  is vertically disposed inside the blocking portion  380  which is disposed above the document fed-in entrance  320 . The cleaning curtain  350  is a composite elastic sheet made from a foam material. An upper end portion  351  of the cleaning curtain  350  has a swallow-tailed protrusion, and the inner wall of the housing of the scanning device has a slot corresponding to the swallow-tailed protrusion. The swallow-tailed protrusion of the cleaning curtain  350  is embedded into the slot. A lower end portion  352  is slightly lower than the fed-in surface of the document supporter  370 , so that the lower end portion  352  can be in contact with the fed-in document with suitable friction. 
       FIG. 7  shows a cross-sectional structure of yet another embodiment of the invention. The scanning device  400  is a small-sized portable scanner whose CIS scanning module  430  is still with respect to the scanner body  410 . The right-hand side of the scanning device  400  has a document fed-in entrance  420  with a document supporter  470 , and the left-hand side has a fed-in document exit. The CIS scanning module  430  is disposed above the left-hand side of the document supporter  470 , and a glass window  431  downwardly faces a to-be-scanned surface of a fed-in document fed in through the document fed-in entrance  420 . A cleaning curtain  450  tilting to an angle is disposed inside a blocking portion  480  which is disposed above the document fed-in entrance  420 . The cleaning curtain  450  is a flexible sheet which forms an obtuse angle of approximately 160 degrees with an out-going direction of the fed-in document. A lower end portion  452  of the cleaning curtain  450  is naturally bent by a force which occurs when the cleaning curtain  450  is in contact with the to-be-scanned surface of the fed-in document. An upper end portion  451  of the cleaning curtain  450  is embedded into a slot formed on the inner wall of the housing of the scanning device and is further adhered and fixed onto the housing. 
       FIG. 8  shows a cross-sectional structure of further another embodiment of the invention. The scanning device  500  is a small-sized portable scanner whose CIS scanning module  530  is still with respect to the scanner body  510 . The right-hand side of the scanning device  500  has a document fed-in entrance  520  with a document supporter  570 , and the left-hand side is a fed-in document exit. The CIS scanning module  530  is disposed above the left-hand side of the document supporter  570 , and a glass window  531  downwardly faces a to-be-scanned surface of a fed-in document fed in from the document fed-in entrance  520 . A cleaning curtain  550  is fixed on the inner wall of the scanning device to the right of the scanning module  530 . The cleaning curtain  550  includes an upper end portion  551  and a lower end portion  552 , wherein the upper end portion  551  is a connecting element constituted by a first elastic metal sheet  555  and a second elastic metal sheet  556 , and the lower end portion  552  is a flexible sheet. A first elastic metal sheet  555  and a second elastic metal sheet  556  are hot-melted and fixed on an inner wall of the housing of a blocking portion  580  near the scanner document fed-in entrance. The first elastic metal sheet  555  and the second elastic metal sheet  556 , which are disposed downwardly and vertically, retain the lower end portion  552 , which is a polypropylene flexible sheet. When the polypropylene flexible sheet is in contact with the to-be-scanned surface of the fed-in document, the upper end portion  551  constituted by the first elastic metal sheet  555  and the second elastic metal sheet  556  is bent to the left due to the friction force and provides the polypropylene flexible sheet of the lower end portion  552  with suitable friction for cleaning. 
     The sheet-fed scanning device with cleaning mechanism is applicable to small-sized sheet-fed scanning device as well as large-sized sheet-fed scanning device. The scanning module does not have to be disposed above the fed-in document. For example, the scanning module can be disposed under the fed-in document, and the cleaning curtain can be disposed at the opposite side of the scanning module. The cleaning curtain can adopt many different types of flexible sheets or general-purpose composite cleaning sheets. 
     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.