Image reading apparatus

An image reading apparatus configured to read images of both surfaces of a document is provided. The image reading apparatus may include a first image reading device configured to read an image of a first surface of a document, a second image reading device configured to read an image of a second surface of the document, and a document conveying mechanism configured to convey the document from the second image reading device to the first image reading device. The first image reading device has a first reading range, and the second image reading device has a second reading range, which is smaller than the first reading range.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2010-077123, filed on Mar. 30, 2010, the entire subject matter and contents of which is incorporated herein by reference.

TECHNICAL FIELD

Aspects of the invention relate to an image reading apparatus including a first image reading device and a second image reading device.

BACKGROUND

Some existing image reading apparatuses may be configured to read images of both surfaces of a document conveyed through a conveying path.

A known image reading apparatus may include a single image reading device configured to read images of both surfaces of a document conveyed through a conveying path.

Another known image reading apparatus may include a first image reading device configured to read an image formed on a first surface of a document conveyed through a conveying path and a second image reading device configured to read an image formed on a second surface formed on the document.

The image reading apparatus including the first image reading device and the second image reading device can quickly read images of both surfaces of a document.

SUMMARY

However, use of the first image reading device and the second image reading device may increase the manufacturing cost, the physical size, or the weight of the image reading apparatus.

Aspects of the invention may provide an image reading apparatus in which the need to increase the manufacturing cost, the physical size or the weight of the image reading apparatus may be reduced.

According to an aspect of the disclosure, an image reading apparatus includes a first image reading device configured to read an image of a first surface of a first document, a second image reading device configured to read an image of a second surface of the first document, and a document conveying mechanism configured to convey the first document from the second image reading device to the first image reading device. The first image reading device has a first reading range, and the second image reading device has a second reading range that is different from the first reading range.

DETAILED DESCRIPTION

A first illustrative embodiment of the invention will be described in detail with reference to the accompanying drawings.

The general structure of an illustrative image reading apparatus1as an example of an image reading apparatus according to illustrative aspects of the disclosure will be described with reference toFIGS. 1,2, and3.

For ease of discussion, in the following description, the top or upper side, the bottom or lower side, the left or left side, the right or right side, the front or front side, and the rear or rear side are used to define the various parts when the image reading apparatus1is disposed in an orientation in which it is intended to be used. InFIG. 1, the lower right side is referred to as the front or front side, the upper left side is referred to as the rear or the rear side, the up side is referred to as the top or upper side, the down side is referred to as the bottom or lower side, the lower left side is referred to as the left or left side, and the upper right side is referred to as the right or right side.

As shown inFIGS. 1,2, and3, the image reading apparatus1includes a main unit5including a first image reading device10, and a cover unit15including an automatic document feeder (ADF)20.

As shown inFIGS. 2 and 3, the main unit5includes a contact glass6on the top surface. The contact glass6includes a first glass7and a second glass8. The first glass7is used when the first image reading device10remains stationary at a predetermined position and reads an image of a document conveyed by the ADF20. When there are some documents to be read on the ADF20, the documents are serially conveyed to pass over the first glass7. As shown inFIG. 3, the first glass7has thickness T, and is shaped in a rectangle whose long side extends in the front and rear direction of the main unit5and is slightly greater than the short side of A3 size.

The second glass8is what is called a platen glass, and is shaped in a rectangle slightly greater than A3 size, in which the long side of the second glass8extends along the right and left direction of the main unit5. The second glass8is used when a first image sensor11of the first image reading device10moves to read an image of a document placed on the second glass8. As shown inFIG. 3, the second glass8also has the same thickness T as the first glass7.

As shown inFIGS. 2 and 3, the main unit5includes the first image reading device10below the contact glass6. The first image reading device10includes the first image sensor11and a slide shaft12. The first image sensor11is a so-called contact image sensor, CIS, and configured to read an image of a document on the contact glass6.

The first image sensor11has a reading range whose length corresponds to the short side of the A3 size in the main scanning direction (that is, the front-rear direction in the main unit5). The length corresponding to the short side of the A3 size is hereinafter referred to as a first dimension D. The slide shaft12extends in the right-left direction in the main unit5, and holds the first image sensor11such that the first image sensor11is slidable in the right-left direction. The first image sensor11can be slid along the slide shaft12by a motor and drive mechanism (e.g., a pulley and belt mechanism). The first image sensor11may be positioned at a stationary reading position under the first glass7. In addition, the first image sensor11may be slidable in a range between a left position along the left edge of the second glass8and a right position away from the left position for a distance corresponding to the long side of A3 size. Thus, the first image reading device10has the maximum reading range R corresponding to A3 size, and can read an image of a document of a size smaller than or equal to A3 size.

As shown inFIGS. 1 and 2, the cover unit15is disposed pivotally on the rear end of the top surface of the main unit5between a closed state shown inFIG. 1and an open state shown inFIG. 2. The cover unit15covers the top surface of the main unit5when in the closed state. Thus, the cover unit15is configured to fix a document set on the second glass8, in position. As shown inFIG. 3, the cover unit15includes a document tray16, an ejection tray17, and the ADF20. The document tray16is disposed on an upper right side of the cover unit15and configured to receive a stack of documents to be read. The ejection tray17is disposed on the right side of the cover unit15and below the document tray16, and configured to receive documents ejected from the ADF20. The document tray16and the ejection tray17are arranged vertically.

The ADF20is disposed on the left side of the cover unit15and configured to successively and singly at a time feed documents in the document tray16through a U-shaped conveying path30to the ejection tray17. In the first embodiment, a direction from the document tray16along the U-shaped conveying path30to the ejection tray17is referred to as a document conveying direction. The ADF20includes a second image reading device50in a specified position along the U-shaped conveying path30. The image reading apparatus1can read an image of a first surface (e.g. a back surface) of a document conveyed through the U-shaped conveying path30by the second image reading device50.

As shown inFIGS. 3 and 4, the ADF20includes an opening in a specified position on the left side of the bottom surface of the ADF20(that is the bottom surface of the cover unit15). The opening extends in the front-rear direction of the main unit5and faces the U-shaped conveying path30. When the cover unit15is in the closed state, the opening is located above the first glass7. Thus, a document to be conveyed through the U-shaped conveying path30is exposed at the opening in which a second surface (e.g. a front surface) of the document faces down. As a result, when the first image sensor11is located in the stationary reading position, the image reading apparatus1can read an image of the second surface of the document conveyed through the U-shaped conveying path30by the first image reading device10.

The structure of the ADF20according to the first embodiment will be described with reference toFIG. 3.

As shown inFIG. 3, the ADF20includes the U-shaped conveying path30, a supply unit35, a conveying unit40, an ejection unit45, and a second image reading device50. With this structure, a document is conveyed and an image of the document is read through the U-shaped conveying path30.

The ADF20further includes a main frame21, an upper guide22, a lower guide23, and an upper cover25. The main frame21constitutes a casing of the ADF20and is made of a synthetic resin, e.g. acrylonitrile butadiene styrene (ABS) resin.

The upper guide22is formed by extending a downstream end of the document tray16in the document conveying direction and configured to guide a document in the document tray16toward the supply unit35. The lower guide23extends from the opening to the ejection tray17, and is configured to guide the document conveyed through the U-shaped conveying path30to the ejection unit45and ejection tray17. That is, the upper guide22and the lower guide23are arranged vertically such that the upper guide is located above the lower guide23.

The upper cover25constitutes the top surface of the ADF20, and is pivotally supported on a rotation shaft positioned at the left end of the ADF20(that is, the left end of the cover unit15). The upper cover25is configured to move between a closed state shown inFIGS. 3 and 4and an open state shown inFIG. 5. When the upper cover25is in the closed state, the upper cover25covers the supply unit35, the conveying unit40, and the upper portion of the second image reading device50. Thus, the upper portion of the U-shaped conveying path30is covered. When the upper cover25is in the open state, the upper cover25is separated from the supply unit35, the conveying unit40and the second image reading device50, and the upper portion of the U-shaped conveying path30is exposed.

The structure of the U-shaped conveying path30in the ADF20will be described.

As shown inFIGS. 3 and 4, the U-shaped conveying path30is formed in a U-shape with respect to the right and left direction of the ADF20so as to connect the document tray16and the ejection tray17. In other words, the U-shaped conveying path30is not configured to convey a document in the front-rear direction of the ADF20. The U-shaped conveying path30is defined by a first conveying path31, a curved conveying path32, and a second conveying path33.

The first conveying path31extends from the downstream end of the document tray16in the document conveying direction to the left end of the ADF20(above a main roller42shown inFIG. 4). When the upper cover25is in the closed state, the upper cover25covers the first conveying path31from above. As shown inFIG. 5, the inside surface of the upper cover25is provided with a plurality of ribs, which protrude toward the first conveying path31when the upper cover25is in the closed state. These ribs are configured to guide an upper surface of a document to be conveyed in the first conveying path31. In other words, the inside surface of the upper cover25defines an upper surface of the first conveying path31, together with a pickup roller36and a separation roller36of the supply unit35, a conveying roller41of the conveying unit40, and a document pressing member70, which will be described later. The lower surface of the first conveying path31is defined by upper surfaces of the upper guide22, a separation pad38, and a glass member60that is positioned in the upper portion of the second image reading device50. These components defining the upper and lower surfaces of the first conveying path31comprise a first document conveying mechanism.

The curved conveying path32is curved downward from a downstream end of the first conveying path31in the document conveying direction to have a semicircular arc shape. As shown inFIG. 4, the curved conveying path32conforms to an outer surface of the main roller42and is connected to the second conveying path33on the left side of the ADF20(under the main roller42). The curved conveying path32is defined by the outer surface of the main roller42and the main frame21and the inside surfaces of the upper cover25. These components defining the curved conveying path32comprise a curved document conveying mechanism.

The second conveying path33generally straightly extends from the lower end of the curved conveying path32to the ejection unit45and the ejection tray17. The second conveying path33is defined mainly by the lower guide23and a wall surface21A of the main unit21of the cover unit15, which is disposed facing and away from the lower guide23. These components defining the second conveying path33comprise a second document conveying mechanism. The second conveying path33is located below the first conveying path31. The second conveying path33includes a part facing the first glass7in the proximity of the main roller42. When the document passes through the part facing the first glass7, the document passes over the opening formed in the bottom surface of the cover unit15. Thus, a document conveyed through the U-shaped conveying path30is conveyed via the opening to the ejection tray17. A known document pressing portion24is disposed at a position facing the opening in the second conveying path33. The document pressing portion24can bring the document closer to the first glass7when the document passes above the opening. Thus, the image reading apparatus1can improve the image reading accuracy by the first image reading device10at the first glass7.

The supply unit35of the ADF20will be described with reference toFIG. 4.

The supply unit35is disposed in the proximity of an end of the first conveying path31closer to the document tray16. The supply unit35is configured to separate documents placed on the document tray16and supply a document at one time toward the conveying unit40. As shown inFIG. 4, the supply unit35includes a pickup roller36, a separation roller37, a separation pad38, and an arm39.

The pickup roller36is rotatably supported in a position along the upper surface of the first conveying path31on an upstream side in the supply unit35in the document conveying direction. The pickup roller36is driven and rotated in a predetermine direction (e.g. clockwise inFIG. 4) by drive of a motor (not shown) via a known transmission mechanism. The pickup roller36is configured to convey a document placed in the document tray16to the separation roller37(toward the downstream side in the document conveying direction).

The separation roller37is rotatably supported to the main frame21on the downstream side from the pickup roller36in the document conveying direction. The separation roller37is driven and rotated in a predetermined direction (e.g. clockwise inFIG. 4) by drive of a motor (not shown). The separation pad38is disposed at a position facing the separation roller37on the lower surface of the first conveying path31. The separation pad38is urged toward the separation roller37. Thus, the separation roller37and the separation pad38operate together such as to separate a document directly contacting the separation roller37and convey the document only to the conveying unit40(to the downstream side in the document conveying direction).

The arm39is supported via bearings to the rotation shaft of the separation roller37. The arm39extends from the shaft of the separation roller37toward an upstream side in the document conveying direction, and rotatably supports both ends of the pickup roller36. The arm39is configured to rock on the rotation shaft of the separation roller37by drive from the motor.

The conveying unit40of the ADF20will be described with reference toFIG. 4.

The conveying unit40is disposed on a downstream side of the supply unit35in the document conveying direction, and configured to convey the document supplied by the supply unit35along the U-shaped conveying path30toward the ejection unit45. The conveying unit40includes a conveying roller41, the main roller42, and pinch rollers43A,43B, and43C.

The conveying roller41is disposed on a downstream side of the supply unit35in the document conveying direction and in a position conforming to the upper surface of the first conveying path31. The conveying roller41is driven by drive of a motor (not shown) and rotated. The pinch roller43A is disposed at a position facing the conveying roller41in the first conveying path31. Thus, the document supplied by the supply unit35is pinched by the conveying roller41and the pinch roller43A and conveyed in the first conveying path31toward the downstream side in the document conveying direction along with the rotation of the conveying roller41.

The main roller42is rotatably supported to the main frame21at the left end of the ADF20, and driven by drive of a motor (not shown) and rotated. As described above, the curved conveying path32is formed conforming to the outer surface of the main roller42. In other words, the outer surface of the main roller42constitutes a part of the curved conveying path32.

The pinch roller43B is disposed in the boundary between the first conveying path31and the curved conveying path32in an upper position of the main roller42and rotatably supported facing the main roller42. Thus, the main roller42pinches the document conveyed in the first conveying path31along with the pinch roller43B and rotates due to the drive of the motor such as to convey the document to the curved conveying path32.

The pinch roller43C is disposed in the boundary between the curved conveying path32and the second conveying path33in a lower position of the main roller42and rotatably supported facing the main roller42. Thus, the main roller42pinches the document conveyed in the curved conveying path32along with the pinch roller43C and rotates due to the drive of the motor so as to convey the document to the second conveying path33.

The ejection unit45of the ADF20will be described with reference toFIG. 4.

The ejection unit45is configured to eject the document conveyed through the U-shaped conveying path30to the ejection tray17. The ejection unit45includes an ejection roller46and the pinch roller43D. The ejection roller46is rotatably supported at a position along the upper surface of the second conveying path33in the vicinity of the downstream end of the second conveying path33in the document conveying direction (that is, in the vicinity of the termination of the U-shaped conveying path30). The ejection roller46is configured to rotate due to the drive of the motor. The pinch roller43D is rotatably supported facing the ejection roller46from below via the second conveying path33. Thus, the ejection roller46pinches the document conveyed through the second conveying path33along with the pinch roller43D and rotates due to the drive of the motor so as to eject the document to the ejection tray17.

The second image reading device50disposed in the ADF20will be described.

The second image reading device50is configured to read an image of a document conveyed in the first conveying path31. As shown inFIG. 4, the second image reading device50is disposed downstream from the conveying roller41and upstream from the main roller42in the document conveying direction, and facing the lower surface of the first conveying path31. The second image reading device50includes a second image sensor51, a sensor holder52, and the glass member60.

The second image sensor51is what is called a contact image sensor (CIS), and is disposed with its reading surface for reading an image, facing up (toward the first conveying path31). The second image sensor51has a reading range whose length corresponds to the short side of A4 size in the main scanning direction (that is, the front-rear direction in the main unit5). The length corresponding to the short side of A4 size is hereinafter referred to as a second dimension L. Thus, the second image sensor51is lighter than the first image sensor11. A document conveyed in the first conveying path31passes over the reading surface of the second image sensor51. Thus, the image reading apparatus1is configured to read an image formed on a first surface (e.g. back surface) of a document conveyed in the first conveying path31by the second image reading device50.

The sensor holder52has a box shape, is open toward the first conveying path31, and configured to hold the second image sensor51inside. As shown inFIGS. 3 and 4, the sensor holder52holds the second image sensor51in a predetermined position inside the sensor holder52(a position facing the first conveying path31and close to the glass member60).

The glass member60is made of a reinforced glass and performs the same function as the first glass7and the second glass8for the first image sensor11. The glass member60is disposed above the second image sensor51and along the lower surface of the first conveying path31, and constitutes a part of the first conveying path31. The glass member60is configured to cover the second image sensor51and guide a document conveyed in the first conveying path31.

The ADF20includes a document pressing member70and an urging member75. The document pressing member70and the urging member75are disposed facing the second image reading device50via the first conveying path31. Specifically, as shown inFIG. 5, the document pressing member70and the urging member75are disposed in position on an inner wall surface of the upper cover25. When the upper cover25is in the closed state, the document pressing member70and the urging member75face the second image reading device50via the first conveying path31. The urging member75is configured to urge the document holding member70toward the first conveying path31and the second image reading device50by its elastic force. Thus, the document pressing member70is configured to press the document conveyed in the first conveying path31toward the second image reading device50. With this arrangement, the image reading apparatus1can improve the image reading accuracy of the second image reading device50.

The following will describe automatic document reading operation for reading images on both surfaces (a first surface and a second surface) of a document in the image reading apparatus1according to the first embodiment. In the following description, it is assumed that documents to be read are set in the document tray16with their first surfaces facing up and the first image sensor11is located in the stationary reading position under the first glass7.

The uppermost document set in the document tray16contacts the pickup roller36of the supply unit35. Thus, the document is supplied from the document tray16by the rotation of the pickup roller36due to the drive of the motor, and is conveyed via the separation roller37along the first conveying path31to the conveying unit40. The document conveyed to the conveying unit40is conveyed by the conveying roller41and the pinch roller43A, and passes over the second image reading device50. At this time, as the second surface of the document faces the second image reading device50, the second image reading device50reads an image formed on the second surface of the document.

After passing over the second image reading device50, the document goes in the curved conveying path32, and is conveyed to the ejection unit45by the rotation of the main roller42. After passing through the curved conveying path32, the first surface of the document faces down. When going in the second conveying path33after the curved conveying path32, the document reaches the document pressing portion24and the first glass7. As described above, the opening is formed on the bottom surface of the cover unit15and in the vicinity of the document pressing portion24. The document is exposed from the opening. The first glass7is located in the position facing the opening, and the first image sensor11is located below the first glass7. Thus, the first surface of the document faces the first image reading device10. When the document passes in an area of the second conveying path33, which is formed by the document pressing portion24and the first glass7, the first image reading device10reads an image of the first surface of the document.

After the image is read by the first image reading device10, the document is conveyed along the second conveying path33to the ejection unit45. When reaching the ejection unit45, the document is conveyed to the ejection tray17by the rotation of the ejection roller46.

The second image reading device50and the glass member60according to the first embodiment will be described.

As described above, the glass member60constitutes the top surface of the second image reading device50and is disposed at the position facing the second image sensor51along the first conveying path31. As shown inFIG. 6, the glass member60is shaped in a rectangle whose long side extends in the front-rear direction (that is, in the main scanning direction of the second image reading device50). The long side of the glass member60is greater than the first dimension D and the second dimension L. As shown inFIG. 3, the glass member60also has the same thickness T as the contact glass6. Thus, in the image reading apparatus1, no difference occurs in the reading accuracy between the first image reading device10and the second image reading device50.

The glass member60is attached to the main frame21by inserting one end of the glass member60in its longitudinal direction into a hole formed in the inner wall surface of the main frame21on the front side of the ADF20and fixing the other end to the inner wall surface of the main frame21with a fixing portion65. As shown inFIGS. 6 and 7, the fixing portion65holds the other end of the glass member60and engages with an engaging portion formed in the inner wall surface of the main frame21. Thus, the glass member60can be removed from a predetermined position above the second image reading device50by disengaging the fixing portion65. When the glass member60is attached in the predetermined position in the upper portion of the second image reading device50, the fixing portion65is disposed at the other end of the glass member60outside the first dimension D.

Without the use of the second image reading device50, the image reading apparatus1can read an image of a document conveyed by the ADF20, by the first image reading device10. The U-shaped conveying path30has a width corresponding to the first dimension D (equivalent to the short side of the A3 size) in the front-rear direction (that is, the main scanning direction of the first image reading device10and the second image reading device50).

As described above, in the first embodiment, the long side of the glass member60extends in the main scanning direction and is greater than the first dimension D. Thus, as shown inFIG. 6, the short sides of the glass member60and any corner thereof are not located in the first conveying path31. With this arrangement, the image reading apparatus1can minimize irregularities of the surface around the glass member60and prevent the document conveyed in the first conveying path31from getting damaged due to the irregularity.

As the fixing portion65holds the end of the glass member60, the fixing portion65is also not located in the first conveying path31. Thus, the image reading apparatus1does not get the document damaged by contact with the fixing portion65.

The image reading apparatus1includes the second image sensor51and the sensor holder52under the glass member60. The sensor holder52is box-shaped and open toward the first conveying path31, and holds the second image sensor51inside. As shown inFIGS. 6,7A and7B, the sensor holder52includes ribs52A extending upward from all sidewalls of the sensor holder52(four sidewalls enclosing the sensor image sensor51), and contacting the undersurface of the glass member60as shown inFIGS. 7A and 7B. The second image sensor51is held in a position adjacent to the glass member60in a space defined by the ribs52A of the sensor holder52and the glass member60. Thus, dust produced in conveying of the document does not enter into the space defined by the ribs52A of the sensor holder52and the glass member60. The image reading apparatus1can reduce the potential for problems due to dust, such as the failure of the second image sensor51and the deterioration of the reading accuracy of the second image sensor51.

As described above, the glass member60is detachably attached to the main frame21via the fixing portion65in the image reading apparatus1. In the image reading apparatus1, the glass member60and the fixing portion65can be replaced with a covering member63shown inFIG. 8.

As shown inFIG. 8, the covering member63is formed of a rectangular plate identical in shape with the glass member60, and has a fixing portion64at one end. Thus, the long side of the rectangular plate of the covering member63is also greater than the first dimension D and the second dimension L. The rectangular plate of the covering member63has the same thickness as the thickness T. The covering member63and the fixing portion64are made of a synthetic resin, e.g. acrylonitrile butadiene styrene (ABS) resin.

The covering member63is attached to the main frame21by inserting one end of the rectangular plate into the hole formed in the inner wall surface of the main frame21located on the front side of the ADF20and then engaging the fixing portion64, which is formed on the other side, with an engaging portion formed in the inner wall surface of the main frame21. Thus, the covering member63can be removed from a predetermined position in the main frame21(that is, the same position where the glass member60is disposed) by disengaging the fixing portion64.

As described above, the long side of the rectangular plate of the covering member63is greater than the first dimension D. When the covering member63is attached to the main frame21, the short sides of the covering member63and any corner thereof are not located in the first conveying path31. Thus, the image reading apparatus1can minimize the irregularities of the surface in the first conveying path31and prevent the document conveyed in the first conveying path31from getting damaged due to the irregularity. In addition, the fixing portion64is disposed outside the first dimension D. Thus, the image reading apparatus1does not get the document damaged by contact with the fixing portion64even when the covering member63is attached.

The image reading apparatus1can be applicable as a model which does not have the second image sensor51, uses the covering member63instead of the glass member60and the fixing portion65, and performs image reading only by the first image reading device10. In this case, the image reading apparatus1can use parts common to models (e.g. the main frame21), which provides improved production efficiency of the image reading apparatus1. In addition, as the fixing portion64is integrally formed with the covering member63, the covering member63can be easily attached.

The image reading apparatus1according to the first embodiment includes the main unit5having the first image reading device10, and the cover unit15rotatably supported at the rear end of the main unit5. When in the closed state, the cover unit15covers the second glass8provided on the top surface of the main unit5and fixes a document set in the second glass8in position. The first image reading device10has the maximum reading range R. The maximum reading range corresponds to the size of the second glass8, and has the first dimension D in the main scanning direction. The first image reading device10is slidable along the slide shaft12to read an image of the document set in the second glass8. Thus, the image reading apparatus1is configured to read an image of a document set in the second glass8(or set within the maximum range R) by the first image reading device10.

The cover unit15includes the document tray16, the ejection tray17, the U-shaped conveying path30, and the second image reading device50. A document set in the document tray16is conveyed through the U-shaped conveying path30while an image of the document is read by the second image reading device50. The second image reading device50has the reading range having the second dimension L (FIG. 6) in the main scanning direction. The second dimension L is smaller than the first dimension D extending in the main scanning direction in the maximum reading range R. The second image reading device50is smaller and lighter than the first image reading device10. Thus, in the image reading apparatus1, the weight of the cover unit15comes down as the cover unit15is provided with the second image reading device50, which is smaller and lighter than the first image reading device10. The image reading apparatus1can reduce the burden on the user who handles with the cover unit15to set a document on the second glass8.

In the image reading apparatus1, the glass member60is located in the upper portion of the second image reading device50using the fixing portion65. The glass member60is made of a reinforced glass, rectangular in form with the long side, which extends in the main scanning direction of the second image sensor51and is greater than the first dimension D. The glass member60is disposed along the inner wall surface of the first conveying path31. Thus, the short sides of the glass member60and any corner thereof are not located in the first conveying path31. The image reading apparatus1can minimize the irregularities of the surface in the first conveying path31, contribute to smooth document conveying, and reduce the potential of problems such as paper jam and ripping due to the irregularities. In other words, as the second image reading device50has the second dimension L in the main scanning direction, which is smaller than the first dimension D, the size of the document to be read by the second image reading device50is assumed to be the size corresponding to the second dimension L. Thus, the size of the document to be conveyed over the glass member60which constitutes the conveying path is usually the size corresponding to the second dimension L. When the dimension of the glass member60in the main scanning direction is greater than the first dimension D, the irregularities of the surface in the first conveying path31caused when the glass member60is disposed can be eliminated, and thus the influence of the irregularities on a document to be conveyed in the first conveying path31whose size corresponds to the second dimension L can be reduced.

The fixing portion65is configured to detachably fix one end of the glass member60to the main frame21. Thus, the fixing portion65is also not located in the first conveying path31. As a result, when the document is conveyed in the first conveying path31, the document does not contact the fixing portion65. With this arrangement, the image reading apparatus1can reduce the potential of problems such as paper jam and ripping caused when the document contacts the fixing portion65. In other words, because the fixing portion65fixes the glass member60at a position outside the first dimension D, even when a document whose size corresponds to the first dimension D is conveyed in the first conveying path31, the document does not contact the fixing portion65.

The glass member60has the same thickness T as the contact glass6. Thus, the reading quality is not different between the second image reading device50and the first image reading device10. Thus, the image reading apparatus1can obtain uniform reading quality between the first image reading device10and the second image reading device50. For example, when a front surface and a back surface of a document are read by the first and second image reading devices10and50, respectively, the image reading apparatus1can uniform reading quality between the first and second image reading devices10and50and achieve favorable double-sided reading.

In the second image reading device50, the second image sensor51is held in position in the space defined by the ribs52A of the sensor holder52and the glass member60A. The ribs52A extend upward from all sidewalls of the sensor holder52(four sidewalls enclosing the sensor image sensor51until the ribs52A contact the undersurface of the glass member60A. Thus, dust produced in conveying of the document does not reach the second image sensor51. As a result, the image reading apparatus1can reduce the potential for the failure of the second image sensor51due to dust.

In the image reading apparatus1, the glass member60and the fixing portion65can be replaced with the covering member63having the fixing portion64. The image reading apparatus1can be applicable as an image reading apparatus having the first image reading device10only by removing the second image sensor51and replacing the glass member60and the fixing portion65with the covering member63. In this image reading apparatus, the first image reading device10is configured to read an image on one surface of a document conveyed through the U-shaped conveying path30, and to read an image of a document set on the second glass8. Even with the covering member63, the image reading apparatus1can minimize the irregularities of the surface in the first conveying path31. In addition, as the fixing portion64is not located in the first conveying path31, the image reading apparatus1can reduce the potential of problems such as ripping of a document due to the irregularities and contact with the fixing portion64.

A second embodiment of the invention will be described.

It is noted that the image reading apparatus1according to the second embodiment is identical in basic structure to that of the first embodiment, except for the structure of the glass member60.

In the first embodiment, the glass member60wholly made of reinforced glass is disposed facing the second image reading device50and along the first conveying path31. In the second embodiment, however, a glass member60A having a different structure is disposed at a position where the glass member60of the first embodiment is disposed. Thus, the following will describe the glass member60A according to the second embodiment with reference toFIGS. 9,10A, and10B, where parts substantially equivalent to those described above are denoted by the same reference numerals and descriptions thereof will be omitted for the sake of brevity.

As shown inFIG. 9, the glass member60A is identical in shape with the glass member60of the first embodiment but different in that the glass member60A includes a glass portion61and a glass holding frame62. Thus, the glass member60A is rectangularly shaped with its long side being greater than the first dimension D, as is the case with the first embodiment. The glass member60A is attached to the main frame21by inserting one end in its longitudinal direction into the hole formed in the inner wall surface of the main frame21on the front side of the ADF20and fixing the other end to the inner wall surface of the main frame21with the fixing portion65on the rear side of the ADF20. Thus, even in the second embodiment, the fixing portion65holds the other end of the glass member60A and engages with the engaging portion formed in the inner wall surface of the main frame21. When the glass member60A is attached in the predetermined position in the upper portion of the second image reading device50, the fixing portion65is disposed at the other end of the glass member60A outside the first dimension D.

As shown inFIG. 9, in the second embodiment, the glass portion61is made of a reinforced glass having the thickness T, and is located in a central portion of the glass holding frame62. As shown inFIGS. 10A and 10B, the glass portion61is shaped in a rectangle whose long side extends in the main scanning direction of the second image sensor51and is greater than the second dimension L, and the glass portion61is disposed facing the second image sensor51. Thus, even in the image reading apparatus1of the second embodiment, the second image reading device50is configured to read an image of a document conveyed in the first conveying path31. The glass portion61is disposed along the inner wall surface of the first conveying path31and constitutes a part of the first conveying path31.

The glass holding frame62is made of a synthetic resin and fixedly holds the glass portion61in its central portion. As described above, the glass holding frame62has the long side greater than the first dimension D and is disposed in the position along the inner wall surface of the first conveying path31together with the glass portion61. In the second embodiment also, the surface of the glass member60A (that is, the surface of the glass portion61and the surface of the glass holding frame62) constitutes a part of the first conveying path31, as shown inFIGS. 10A and 10B. The glass portion61and the glass holding frame62are configured to cover the second image sensor51and guide a document conveyed in the first conveying path31.

As the glass member60A has the long side greater than the first dimension D, the short sides of the glass member60A are not located in the first conveying path31. Thus, the image reading apparatus1according to the second embodiment can minimize the irregularities of the surface in the first conveying path31and prevent a document to be conveyed in the first conveying path31from getting damaged due to the irregularities.

The glass member60A is detachably attached in position in the upper portion of the second image reading device50by using the fixing portion65identical with that of the first embodiment. Thus, even in the second embodiment, the fixing portion65is not located in the first conveying path31. Accordingly, the image reading apparatus1does not get the document damaged by contact with the fixing portion65.

In the second embodiment, the glass portion61facing the second image sensor51has the same thickness T as the contact glass6. Thus, even in the image reading apparatus1according to the second embodiment, no difference occurs in the reading accuracy between the first image reading device10and the second image reading device50.

As shown inFIGS. 10A and 10B, the ribs52A extend upward from all sidewalls of the sensor holder52until they contact the undersurface of the glass member60A. Thus, the second image sensor51is held in position in the space defined by the ribs52A of the sensor holder52and the glass member60A. As a result, the image reading apparatus1according to the second embodiment can reduce the potential for the failure of the second image sensor51due to dust.

In the second embodiment, the glass member60A includes the glass portion61and the glass holding frame62but is identical in shape with the glass member60of the first embodiment. Thus, the image reading apparatus1according to the second embodiment can use the covering member63(FIG. 8) instead of the glass member60A and the fixing portion65and obtain the effects similar to those brought about by the first embodiment.

As described above, the image reading apparatus1according to the second embodiment includes the glass portion61having the length greater than the second dimension L in the main scanning direction at the position facing the second image sensor51. Thus, the image reading apparatus1can read an image of a document conveyed in the first conveying path31by the second image reading device50. The glass portion61and the glass holding frame62constitute a part of the first conveying path31and the glass member60A has the length greater than the first dimension D. Thus, the image reading apparatus1according to the second embodiment can minimize the irregularities of the surface in the first conveying path31, smoothly convey a document along the first conveying path31, and reduce the potential of problems such as paper jam and ripping due to the irregularities.

The glass member60A is detachably fixed to the main unit21outside of the first conveying path31by the fixing portion65as is the case with the first embodiment. Thus, the image reading apparatus1according to the second embodiment can reduce the potential of problems such as paper jam and ripping due to the existence of the fixing portion65.

The glass portion61has the same thickness T as the contact glass6. Thus, the image reading apparatus1according to the second embodiment can obtain uniform reading quality between the first image reading device10and the second image reading device50. In the second embodiment, the second image sensor51is held in position in the space defined by the ribs52A of the sensor holder52and the glass member60A. As a result, the image reading apparatus1according to the second embodiment can reduce the potential for the failure of the second image sensor51due to dust. The image reading apparatus1according to the second embodiment can use the covering member63instead of the glass member60A and the fixing portion65. In other words, the image reading apparatus1can be applicable as an image reading apparatus including the first image reading device10only. Even when the covering member63is disposed, the fixing portion64is located outside of the first conveying path31. Thus, the image reading apparatus1can minimize the irregularities of the surface in the first conveying path31and reduce the potential of problems such as ripping of a document due to the irregularities and contact with the fixing portion64.

The illustrative embodiments show, but the disclosure is not limited to that the ribs52A stand along all sidewalls of the sensor holder52so as to enclose the second image sensor51in all directions. The ribs52A may be formed in any shape as long as the sensor holder52(around the second image sensor51) can be kept away from dust.

The glass member60,60A may be located on an upstream side in the first conveying path31in the document conveying direction and may be chamfered on the sides and corners thereof facing the first conveying path31.

Although an illustrative embodiment and examples of modifications of the present invention have been described in detail herein, the scope of the invention is not limited thereto. It will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the invention. Accordingly, the embodiment and examples of modifications disclosed herein are merely illustrative. It is to be understood that the scope of the invention is not to be so limited thereby, but is to be determined by the claims which follow.