Patent Publication Number: US-2007097454-A1

Title: Scanning module, image reading apparatus using the same, and maintenance method of the scanning module

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION  
      This application claims the benefit of Korean Application No. 2005-103787, filed Nov. 1, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      Aspects of the present invention relate to a scanning module, an image reading apparatus using the scanning module, and a maintenance method of the scanning module, and, more particularly, to an integration type scanning module in which a light source, a mirror, a lens unit, and an image sensor are provided to read an image from a document, and an image reading apparatus using the scanning module and a maintenance method of the scanning module.  
      2. Description of the Related Art  
      A conventional image reading apparatus includes a scanning module that reads an image from a document by scanning the document with light to obtain an optical signal. The scanning module then converts the obtained optical signal into an electrical signal. Examples of such conventional image reading apparatuses include scanners, facsimiles, and multi-function apparatuses.  
      In conventional image reading apparatuses, the operation of reading an image from a document requires that either the scanning module or the document needs to be moved relative to the other. An image reading apparatus with a movable scanning module is called a flat-bed type image reading apparatus. On the contrary, an image reading apparatus configured to move a document is called a sheet-feed type image reading apparatus. The flat-bed type image reading apparatus and the sheet-feed type image reading apparatus may be combined by adding an auto document feeder (ADF) to the flat-bed type image reading apparatus.  
      A conventional image reading apparatus further includes a flat glass panel, on which documents are placed, with the scanning module being disposed underneath the flat glass panel to read the documents. The scanning module includes a light scanning unit to project light to a document, an image sensor unit to convert an optical signal obtained by scanning the document into an electrical signal, and a light reflecting unit to reflect light reflected from the document to the image sensor unit.  
      The light scanning unit includes a light source to project light to a document from an underside of the flat glass panel. The light source may be a halogen lamp that has a predetermined length in a main scanning direction of the document which is capable of projecting light across the main scanning direction at one time.  
      The image sensor unit includes an image sensor such as a charge-coupled device (CCD) sensor or a contact image sensor (CIS) sensor, a control board to control the operation of the image sensor, and a lens unit to focus optical signals onto the image sensor.  
      The light reflecting unit forms an optical path from the light source of the light scanning unit to the lens unit of the image sensor unit. The light reflecting unit includes a plurality of mirrors to reflect optical signals reflected from the document to the lens unit.  
      In conventional image reading apparatuses there are generally two types of scanning modules: an integration type scanning module and a separation type scanning module. The integration type scanning module includes a light scanning unit, an image sensor unit, and a light reflecting unit that are assembled into an enclosing frame together, and the frame, the light scanning unit, and the image sensor unit are moved together to read an image from a document. The separation type scanning module includes a light scanning unit, an image sensor unit, and a light reflecting unit that are separated to reduce the mass of inertia of the scanning module. The image sensor unit is fixed to a main body of an image reading apparatus. The light scanning unit and the light reflecting unit read an image from a document while they are moved in a subsidiary scanning direction at different speeds to keep the total length of an optical path constant.  
      Over the lifetime of the conventional image reading apparatuses, foreign substances tend to accumulate in the scanning module. As a result, components, such as the mirrors and the lens unit, are contaminated, with the image sensor considering the foreign substances as being image data. A combination of the foreign substances and movement of the scanning module results in an error data output in the form of a black line.  
      Particularly, in the integration type scanning module, in which the light scanning unit, the image sensor unit, and the light reflecting unit are assembled together, the foreign substances may be eliminated by a cleaning of the inside of the scanning module using, for example, an air gun only after disassembling the frame. However, since it is difficult for a user to perform such cleaning, professional cleaning services are required. Thus, maintenance cost and time are increased. However, if the foreign substances are not removed promptly and eventually become caked on the inside of the scanning module, removal of the caked foreign substances may become impossible.  
      Moreover, in the separation type scanning module having the light scanning unit, the image sensor unit, and the light reflecting unit that are separately installed, foreign substances may be easily removed by blowing air because components such as the mirrors and the lens unit are exposed to an exterior of the image reading apparatus. Thus, the integration type scanning module usually requires a much more complicated foreign substance eliminating unit and maintenance time and cost than the separation type scanning module.  
      Meanwhile, if the light source is turned on for a long time, the inside temperature of the scanning module increases. For example, various mechanisms making up the scanning module are formed of synthetic resin or the like, and the mirrors and lens unit are installed at a predetermined position and angle. Therefore, if the inside temperature of the scanning module increases, the mechanisms may be deformed, and the mirrors and the lens unit may deviate from the predetermined position and angle. This disturbs the focusing of the optical signal on a precise position of the image sensor, causing image reading errors.  
     SUMMARY OF THE INVENTION  
      Aspects of the present invention provide a scanning module preventing image reading errors caused by build-up of foreign substances and high temperature, an image reading apparatus using the scanning module, and a method of maintaining the scanning module.  
      According to an aspect of the present invention, there is provided a scanning module comprising a light source to project light onto a document to be read, a lens unit to focus an optical signal read from the document; a plurality of mirrors to form an optical path from the light source to the lens unit, an image sensor to convert the optical signal focused by the lens unit into an electrical signal, a frame to house the light source, the lens unit, the mirrors, and the image sensor, and a fan to circulate air inside the frame.  
      According to another aspect of the present invention, there is provided an image reading apparatus in which a scanning module reads an image from a document while moving in a subsidiary scanning direction thereof, the scanning module comprising a light source to project light onto a document to be read, a lens unit to focus an optical signal read from the document, a plurality of mirrors to form an optical path from the light source to the lens unit, an image sensor to convert the optical signal focused by the lens unit into an electrical signal, a frame to house the light source, the lens unit, the mirrors, and the image sensor, and a fan circulating air inside the frame.  
      According to a further another aspect of the present invention, there is provided a maintenance method of a scanning module provided with a frame and a light source, a lens unit, a mirror, and an image sensor that are mounted in the frame, the scanning module reading an image from a document while moving in a subsidiary scanning direction, the maintenance method comprising circulating air inside the frame to remove foreign substances attached to at least one of the light source, the lens unit, the mirror, and the image sensor and/or to control a temperature of an inside of the frame.  
      Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
       FIG. 1  is a perspective view of an image reading apparatus having a scanning module installed therein;  
       FIG. 2  is a perspective view of the scanning module and a driving module according to an embodiment of the present invention;  
       FIG. 3  is a side-sectional view of the scanning module of  FIG. 2 ; and  
       FIG. 4  is a cross-sectional perspective view taken along a line A-A′ of  FIG. 3 .  
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
      Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
       FIG. 1  is a perspective view of an image reading apparatus having a scanning module installed therein. As shown in  FIG. 1 , the image reading apparatus includes first and second flat glass panels  50  and  51 , an auto document feeder (ADF)  10 , and a scanning module  500 . The X-axis denotes a subsidiary scanning direction along which the scanning module  500  moves to read an image, and the Y-axis denotes a main scanning direction along which the scanning module  500  reads an image line at a time.  
      The first flat glass panel  50  contacts a document when the document is moved into scanning position by the ADF  10 , and the second flat glass panel  51  contacts the document (i.e., a recording medium, such as paper, transparency, etc.) when the document is stopped in position. The first and second flat glass panels  50  and  51  are separated from each other. A display panel  40  displays an operational state of the image reading apparatus and includes a plurality of control keys.  
      In the operational state of the image reading apparatus, a document stacked on a document feed tray  20  is moved to the first flat glass panel  50  by the ADF  10 . The scanning module  500  located at the back of the first flat glass panel  50  reads an image from the document. After that, the document is discharged to a document output tray  30 . A document guide member  70 , having a sloped surface, is provided between ends of the first and second flat glass panels  50  and  51 . The document guide member  70  guides a leading edge of the document to the document output tray  30  when the document passes the first flat glass panel  50 .  
      Of course, it is understood that a document may also be directly placed on a top surface of the second flat glass panel  51  without being fed by the ADF  10 . In this case, while moving in a scanning direction (hereinafter, in a positive direction of the X-axis) from the underside of the second flat glass panel  51 , the scanning module  500  reads an image from the stopped document.  
      When reading an image from a document fed from the ADF  10 , the scanning module  500  is stopped underneath the first flat glass panel  50 , and when reading an image from a stopped document, the scanning module  500  is moved underneath the second flat glass panel  51 . Of course, it is understood that the image reading apparatus, according to aspects of the present invention, is not limited to the image forming apparatus illustrated in  FIG. 1 . Various embodiments of the image reading apparatus may be used.  
       FIG. 2  is a perspective view of a scanning module and a driving module according to an embodiment of the present invention,  FIG. 3  is a side-sectional view of the scanning module, and  FIG. 4  is a cross-sectional perspective view taken along a line A-A′ of  FIG. 3 . As shown in  FIGS. 2 through 4 , the scanning module  500 , as it slides, reads an image from a document (P), and a driving module moves the scanning module  500  in a subsidiary scanning direction.  
      As shown in  FIG. 3 , the scanning module  500  includes a light source  510  to project light to the document (P), a light reflecting member  520  to concentrate light radiated from the light source  510  toward the document (P), a lens unit  560  to focus an optical signal read from the document (P) onto an image sensor  530 , a plurality of mirrors  580  to form an optical path from the light source  510  to the lens unit  560 , the image sensor  530  to convert the optical signal focused by the lens unit  560  into an electrical signal, a frame  501  to form the outside of the scanning module  500 , and a fan  570  (i.e., a blower fan) to move air inside the frame  501  so as to remove foreign substances from the inside of the frame  501  or so as to control the temperature inside the frame  501 .  
      The image sensor  530  included in the scanning module  500  may be a charge coupled device (CCD) sensor that converts the optical signal read from the document into an electrical signal. In a high-rank image reading apparatus capable of reading an image from a document equal to or larger than A4 size, a CCD sensor may be used because of a high resolution thereof and relatively strong depth of focus.  
      With reference to  FIG. 2 , the driving module includes a guide hole  540  defined in the scanning module  500  and a guide shaft  600  inserted through the guide hole  540 . The guide hole  540  allows the scanning module  500  to slide along the guide shaft  600  in the X-axis direction.  
      The scanning module  500 , as it slides, vibrates depending on the gap size between the guide hole  540  and the guide shaft  600 , a number of guide holes and guide shafts, if more than one of each is used, and the surface roughness of the guide shaft  600 . Since the vibration of the scanning module  500  causes image reading errors, the driving module is designed to reduce the vibration.  
      In fact, a sliding bearing (not shown) may be fitted into the guide hole  540  to provide lubrication. Also a single guide shaft  600  may be provided at a position adjacent to a first timing belt  400   a . Usually, however, the movement of the scanning module  500  is guided along a single shaft. This is due to the fact that, if two guide shafts  600  are used to guide both ends of the scanning module  500 , vibration of the scanning module  500  may increase due to tolerance accumulation or other reasons. Both ends of the guide shaft  600  are fixed to a main body (not shown) of the image reading apparatus using shaft holders  610   a  and  610   b . Though not shown, a sliding member is additionally provided on the main body of the image reading apparatus to support the weight of the scanning module  500  at both ends thereof. The sliding member is sufficiently lubricated to prevent a load from acting on the scanning module  500  in the sliding direction.  
      The driving module includes: the first timing belt  400   a  and a second timing belt  400   b  respectively coupled to both ends of the scanning module  500 ; a first belt pulley  170  and a second belt pulley  270 , including teeth on outer surfaces thereof, to drive the first and second timing belts  400   a  and  400   b , respectively; a connecting shaft  300  to coaxially couple the first and second belt pulleys  170  and  270 , respectively, to each other; a driving motor  110 ; and a gear train to act as a power transmitting member connecting the driving motor  110  and the first belt pulley  170 . The gear train may include a first gear  120  coaxially coupled to the driving motor  110 , and second to fifth gears  130 ,  140 ,  150 ,  160  that are sequentially connected to the first gear  120 . The gear train transmits driving power to the first pulley  170  at a reduced speed.  
      The first timing belt  400   a  and the first belt pulley  170 , which drives the first timing belt  400   a , and the second timing belt  400   b  and the second belt pulley  270 , which drives the second timing belt  400   b , are all respectively formed with teeth. This is advantageous because, as the size of the document (P) increases, the possibility of image reading errors increases since the size, weight, and sliding speed of the scanning module  500  increases in proportion to the increase of document size. The teeth of the first and second timing belts  400   a  and  400   b  mesh with the teeth of the first and second belt pulleys  170  and  270 , respectively, to prevent such slippage. Since the first and second belt pulleys  170  and  270  are coaxially connected to each other by the connecting shaft  300 , both ends of the scanning module  500  slide at the same speed.  
      Referring to  FIG. 2 , since driving power is transmitted directly to the scanning module  500  via the gear train, the first and second belt pulleys  170  and  270 , the first and second timing belts  400   a  and  400   b , and the connecting shaft  300 , the position and speed of the scanning module  500  may be precisely controlled without an occurrence of slipping. In fact, the illustrated scanning module  500  may read an image from an A3 document (297 mm×420 mm) without an image reading error.  
      The driving module may further include a first bracket  105  to join the first belt pulley  170 , the driving motor  110 , and the gear train to the main body of the image reading apparatus, and a second bracket  205  to join the second belt pulley  270  to the main body.  
      A third belt pulley  370  is coupled to the other end of the first timing belt  400   a , and a fourth belt pulley  470  is coupled to the other end of the second timing belt  400   b . The third and fourth belt pulleys  370  and  470  are also formed with teeth on inner circumferences thereof. The third belt pulley  370  is coupled to the main body of the image reading apparatus by a third bracket  305 , and the fourth belt pulley  470  is coupled to the main body by a fourth bracket  405 .  
      As is described above, the scanning module  500 , according to aspects of the present invention, includes the fan  570  (which may comprise, as noted above, a blower fan). Further, the image reading apparatus reads an image from the document (P) while moving the scanning module  500  with the fan  570  in the X-axis direction (the subsidiary scanning direction). The fan  570  circulates air inside the frame  501  in which the light source  510 , the lens unit  560 , the mirrors  580 , and the image sensor  530  are mounted, and thereby eliminates foreign substances from the inside of the frame  501 . The fan  570  also prevents the temperature of an inside of the frame  501  from rising, such that image reading errors due to thermal deformation may be reduced.  
      The fan  570  is disposed inside the frame  501  and blows air toward at least one of the light source  510 , the mirrors  580 , the lens unit  560 , and the image sensor  530  that are provided in the frame  501  in order to remove foreign substances therefrom. The frame  501 , the light source  510 , the mirrors  580 , and the lens unit  560  extend along the Y-axis (the main scanning direction), such that the fan  570  blows air in the main scanning direction. Since space inside the frame  501  is formed along the main scanning direction, the removal of foreign substances and the temperature control is efficiently performed by the blowing of air in the main scanning direction.  
      It is understood that additional fans  570  may be disposed along the main scanning direction of the frame  501 . Such additional fans  570  would provide additional air blowing power along the longitudinal length of the frame  501  and thereby increase the degree to which foreign substances are cleaned from the light source  510 , the mirrors  580 , and the lens unit  560  in this case, a first fan  570  would be disposed at a first longitudinal end of the frame  501 , as shown in  FIG. 4 , and the additional fans  570  would be placed at positions along the length of the frame  501  at which the blowing of air along the length of the frame  501  is maximized.  
      A control unit  900  is provided to control the operation of the fan  570 . In the embodiment illustrated in  FIG. 2 , the control unit  900  is provided at an exterior of the scanning module  500 , and, in the embodiment illustrated in  FIG. 3 , the control unit  900  is provided inside the scanning module  500 . The control unit  900  supplies power to the fan  570  and controls the operation of the fan  570 .  
      The control unit  900  may operate the fan  570  periodically when the scanning module  500  is in stand-by mode. In stand-by mode, the scanning module  500 , as it prepares image reading, waits at a stand-by position for a scanning command. Though scanning is not performed in the stand-by mode, foreign substances can permeate the frame  501  through a gap tolerance of the frame  501 , and can be accumulated on the mirrors  580  or the lens unit  560  if scanning module remains in the stand-by mode for a long time. Thus, the control unit  900  operates the fan  570  periodically to prevent caking of the foreign substances on the mirrors  580  or the lens unit  560 .  
      When an air blowing command is input, the control unit  900  operates the fan  570 . As is described above, since foreign substances, accumulated on the mirrors  580  or the lens unit  560 , block light from passing from the light source  510  to the image sensor  530 , the foreign substances are output as image data in the form of a black line according to the movement of the scanning module  500 . If a black line that is inconsistent with original image data appears in an output of the image reading apparatus, a user may input the air blowing command via the display panel  40  or an external computer to remove the foreign substances by an operation of the fan  570 . That is, the accumulation of foreign substances may be eliminated without the need for a service technician.  
      The scanning module  500  may further include a temperature sensor  950 . The temperature sensor  950  senses the temperature of the inside of the frame  501 . The control unit  900  may turn the fan  570  on and off according to the temperature measured by the temperature sensor  950 . A reference temperature to prevent thermal deformations of the mirrors  580  and the lens unit  560  is previously stored in the control unit  900 . If the temperature measured by the temperature sensor  950  is higher than the reference temperature, the control unit  900  operates the fan  570  to cool the inside of the frame  501 .  
      For a normal operation of the scanning module  500 , a method of conducting maintenance is required to remove foreign substances from the inside of the frame  501  or to prevent the temperature inside the frame  501  from rising excessively. In a method of conducting maintenance of the scanning module  500  according to an embodiment of the present invention, air is circulated in the frame  501  by the fan  570  to remove foreign substances attached to at least one of the light source  510 , the lens unit  560 , the mirrors  580 , and the image sensor  530  that are installed in the frame  501  or to control the temperature inside the frame  501 .  
      According to a method of maintaining the image reading apparatus according to the current embodiment of the present invention, when the scanning module  500  is in a stand-by mode, the fan may be periodically operated. Also, when an operation command is input, the fan  570  may be operated. Additionally, the temperature of the inside of the frame  501  may be measured by the temperature sensor  950 , and the fan  570  may be turned on/off according to the measured temperature.  
      As is described above, according to aspects of the present invention, the scanning module, the image reading apparatus using the scanning module, and the maintenance method of the scanning module are designed such that foreign substances may be removed from the inside of the frame using the fan or the temperature inside the frame is prevented from rising, thereby preventing image reading errors due to the foreign substances or a rise in temperature. Thus maintenance time and cost may be reduced, thereby improving customer satisfaction.  
      Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.