JP7743249B2 - Image reading device and image forming device - Google Patents

Description

The present invention relates to an image reading device that reads images on sheets such as originals, and an image forming apparatus that uses the same.

Conventionally, image reading devices have been used that can automatically feed documents (sheets) one by one from a document tray or the like, while reading the image information of the documents as they are fed. ADFs (Auto Document Feeders), which automatically feed documents, are commonly used as sheet feeders in image reading devices. When documents are read using an ADF, sudden speed fluctuations in the document being transported due to momentary shocks or vibrations occurring inside or outside the device can cause image blurring and degrade image quality. Image blurring here refers to the expansion or contraction of the image in the transport direction when viewing a scanned image over a small area. This image blurring can generally be evaluated using a chart with lines spaced at equal intervals in the document transport direction (sub-scanning direction), and is evaluated based on whether the scanned image reproduces the equal spacing of the lines on the chart.

The slack in a document when it is read is called a loop. It is known that image blurring is caused in part by changes in the document's posture, such as when a loose document becomes taut (loop decrease) or when a taut document becomes taut again (loop increase), and the resulting speed fluctuations. To prevent image blurring due to such reasons, a sheet feeding device has been developed that restricts document movement by providing a protrusion on the inner guide of the bent section downstream of the document reading unit (see Patent Document 1). In this sheet feeding device, the document is transported while abutting the protrusion, thereby suppressing changes in the document's posture, such as loop decrease or loop increase, and reducing image blurring due to sheet speed fluctuations.

Japanese Patent Application Laid-Open No. 2006-86957

In recent years, there has been a demand for image reading devices that can feed documents of various sizes. Among these, there is a demand for image reading devices that can read images of so-called small-sized documents, such as business cards and checks. These documents, such as business cards and checks, tend to have a high basis weight and therefore are stiff sheets.

However, the image reading device described in Patent Document 1 encounters the following problem when reading images on stiff sheets such as business cards or checks. Specifically, when a stiff sheet is conveyed from the pair of conveying rollers toward the reading unit, the leading edge of the sheet does not encounter significant sliding resistance when it reaches the reading unit, and the sheet is conveyed along the nip line of the pair of conveying rollers, floating above the guide member (see Figure 8(a)). In contrast, when the leading edge of the sheet reaches, for example, the scooping unit and begins to encounter sliding resistance, the sheet that was floating above the guide member between the pair of conveying rollers and the reading unit is pushed toward the guide member, potentially causing temporary loop growth (see Figure 8(b)). As a result, even though the sheet is being fed by the pair of conveying rollers, the amount of feed is used to grow the loop, causing the sheet to stagnate at the reading position, and fluctuations in the sheet speed can result in image blurring.

The present invention aims to provide an image reading device and image forming device that can suppress image blurring caused by loop growth and sheet speed fluctuations, even when using small, stiff sheets.

The image reading device of the present invention comprises a support section that supports a sheet, a discharge section that is disposed below the support section and from which the sheet is discharged, a transport guide that forms a curved transport path that transports the sheet supported on the support section to the discharge section, a reading section that is disposed facing the transport path and reads an image on the sheet transported along the transport path, and a pair of transport rollers that are disposed upstream of the reading section in the sheet transport direction and transport the sheet when the image on the sheet is read by the reading section, the transport guide having a first guide section that is provided outside the curve of the transport path between the reading section and the pair of transport rollers, the first guide section having a first guide surface formed in a first region that overlaps in a width direction that intersects with the transport direction with an area through which a sheet of the smallest width that can be transported passes, and a second guide surface formed in a second region other than the first region within the sheet transport area in which the sheet can be transported in the width direction, the first guide surface protruding toward the transport path beyond the second guide surface.

The image reading device of the present invention also includes a support section that supports a sheet, a discharge section that is disposed below the support section and from which the sheet is discharged, a transport guide that forms a curved transport path that transports the sheet supported by the support section to the discharge section, a reading section that is disposed facing the transport path and reads an image on the sheet transported along the transport path, and a pair of transport rollers that are disposed upstream of the reading section in the sheet transport direction and transport the sheet when the image on the sheet is read by the reading section, the transport guide having a first guide section that is provided outside the curve of the transport path between the reading section and the pair of transport rollers, the first guide section having a plurality of first ribs formed side by side in the width direction in a first region that overlaps in a width direction intersecting with an area through which a sheet of the smallest width that can be transported passes, and a plurality of second ribs formed side by side in the width direction in a second region other than the first region within the sheet transport area in which the sheet can be transported in the width direction, the tips of the plurality of first ribs protruding toward the transport path beyond the tips of the plurality of second ribs.

The image forming apparatus of the present invention is characterized by comprising the above-mentioned image reading device and an image forming unit that forms an image on a recording material based on the image read by the image reading device.

According to the present invention, image blurring caused by loop growth and fluctuations in sheet speed can be suppressed even with small, stiff sheets.

1 is a cross-sectional view showing an image forming apparatus according to a first embodiment. 1 is a perspective view showing a document reading device according to a first embodiment; FIG. 2 is a perspective view showing a first guide portion according to the first embodiment. 1A is a cross-sectional view showing the main parts of a document reading device according to a first embodiment, in which FIG. 1A shows the state before the leading edge of the document reaches the scooping section, and FIG. 1B shows the state when the leading edge of the document reaches the scooping section. FIG. 4 is a perspective view showing a second guide portion according to the first embodiment. FIG. 10 is a perspective view showing a document reading device according to a second embodiment. FIG. 10 is a perspective view showing a first guide portion according to a second embodiment. 1A and 1B are cross-sectional views showing the main parts of a document reading device according to a comparative example, in which (a) shows the state before the leading edge of the document reaches the scooping section, and (b) shows the state when the leading edge of the document reaches the scooping section.

First Embodiment
A first embodiment of the present invention will be described in detail below with reference to Figures 1 to 5. In this embodiment, a document reading device 1, which is an example of an image reading device, is mounted on an image forming device 200. The image forming device 200 includes an image forming unit 201 that forms an image on a recording material based on an image read by the document reading device 1.

[Document reading device]
Fig. 1 is a cross-sectional view of a document reading device 1 according to this embodiment, and Fig. 2 is a perspective view of the document reading device 1. In this embodiment, the front-rear direction is defined as a main scanning direction (width direction) that intersects (e.g., is perpendicular to) the document transport direction of the document reading device 1. The document reading device 1 has a document feeder 20 and a document table scanner 50.

[Platen Scanner]
As shown in FIG. 1 , the platen scanner 50 is a platen scanning type document reading device and includes a housing 51, a first reading unit 52, a platen glass 53, and a flow reading glass 54, which is an example of a glass plate. The first reading unit 52, which is an example of a reading unit, is composed of a CIS (Contact Image Sensor) that irradiates light from an LED array serving as a light source onto the image information surface of a document and focuses the light reflected from the image information surface onto a sensor element to read the image information. Here, the flow reading glass 54 is an example of a first glass plate and is located downstream of the first guide unit 43 (described later) in the document transport direction and is horizontally disposed to form part of the transport path. The first reading unit 52 is an example of a first reading unit that reads an image on the front side, which is the first side of the document, and is located below the flow reading glass 54 in a flow reading mode (described later).

[Original feeding device]
The document feeder 20 is an ADF and includes a document tray 3 on which documents, which are an example of sheets, are placed, a feed unit 21, a transport section 22, a second reading unit 18, a reading glass 19, which is an example of a glass plate, and a discharge tray 24, which is an example of a discharge section. The document feeder 20 is rotatably provided on the top of the document table scanner 50 by a hinge section (not shown). The feed unit 21 includes a liftable arm 10, a feed roller 17, a separation roller 8, and a separation pad 9. The feed roller 17 comes into contact with the topmost document supported (stacked) on the document tray 3, picks it up, and feeds it.

The transport unit 22 has a transport guide 40 that forms a transport path curved in a roughly U-shape. The transport path is curved so that documents supported in the document tray 3 are transported to the discharge tray 24. The transport guide 40 has an upper guide portion 41 that contacts the upper surface of the document to guide it, and a lower guide portion 42 that contacts the lower surface of the document to guide it. The transport unit 22 also has a first transport roller pair 13 that transports the document, a second transport roller pair 14, a discharge roller pair 15, and an edge sensor 16 that detects the leading and trailing edges of the document. The first transport roller pair 13 is located upstream of the first reading unit 52 in the document transport direction, and transports the document when the image on the document is read by the first reading unit 52.

The second reading unit 18, an example of a reading unit, is similar to the first reading unit 52 in that it is composed of a CIS that irradiates the image information surface of the document from an LED array as a light source, and focuses the light reflected from the image information surface onto a sensor element to read the image information. Here, the reading glass 19 is an example of a second glass plate, and is positioned opposite the flow reading glass 54, and is installed horizontally to form part of the transport path. The second reading unit 18 is an example of a second reading unit that reads the image on the back side, which is the second side of the document, and is positioned above the reading glass 19 facing the transport path.

The document feeder 20 also has a scooping unit 25, an example of a third guide unit that is part of the transport guide 40, located downstream of the first reading unit 52 in the transport direction and on the outside of the curve of the transport path. The scooping unit 25 is located downstream of the flow reading glass 54 in the transport direction and is inclined so that the downstream side is on the upper side. As a result, the document transported horizontally between the flow reading glass 54 and the reading glass 19 has its transport direction changed upward by the scooping unit 25 and is transported to the second transport roller pair 14.

The document tray 3 is an example of a support unit that supports documents. The discharge tray 24 is located below the document tray 3 and receives and stacks documents. As shown in FIG. 2 , the document tray 3 has a first restricting plate 31, an example of a first restricting unit, and a second restricting plate 32, an example of a second restricting unit, that can contact both sides of the document to restrict the position of the document in the main scanning direction (width direction) to the center of transport. The first restricting plate 31 and the second restricting plate 32 are connected by a gear train (not shown), and when one restricting plate is operated, the other also operates in conjunction. The first restricting plate 31 and the second restricting plate 32 always move the same distance, making it possible to restrict documents of any width to the center of transport. In other words, the first restricting plate 31 and the second restricting plate 32 are movable in conjunction with each other in the width direction and restrict the positions of both sides of the document in the width direction supported by the document tray 3.

A subtray 33 is provided upstream of the document tray 3. The subtray 33 has a pivoting section 34, allowing it to pivot relative to the document tray 3. The provision of the subtray 33 makes it possible to support documents that are long in the feeding direction. Furthermore, because the subtray 33 is pivotable, it can be closed so that it overlaps the document tray 3. This improves the visibility and ease of removal of documents discharged to the discharge tray 24, and by covering the document feed opening, it is possible to prevent dust and other foreign matter from accumulating on or entering the document tray 3 or the transport section 22 when not in use.

[Operation of Document Reading Device]
The document reading device 1 can read an image of a document in two modes: fixed reading and flow reading. Flow reading is a mode in which an image of a document is read while the document is being transported by the document feeder 20. Fixed reading is a mode in which an image of a document placed on a document table glass 53 provided on the top surface of the document table scanner 50 is read.

As shown in Figure 1, when skimming is performed, when the user issues a command to start reading from the operation panel, the feed unit 21 descends and the feed roller 17 feeds the document. As the feed roller 17 rotates, the document is fed to the separation section between the separation roller 8 and separation pad 9, where it is separated one sheet at a time, with the topmost document being separated and fed. The separated document is transported along the transport guide 40 by the first transport roller pair 13 and transported to the reading areas of the first reading unit 52 and second reading unit 18.

When the edge sensor 16 detects the leading edge of the document, the first reading unit 52 begins reading image information from the front side of the document as it passes over the flow-reading glass 54 of the document table scanner 50 a predetermined distance from that position. Furthermore, as the document passes over the reading glass 19, the second reading unit 18 begins reading image information from the back side of the document. Specifically, the first reading unit 52, an example of a first reading unit, is positioned facing the transport path and reads an image from the front side of the document as it is transported along the transport path. The second reading unit 18, an example of a second reading unit, is positioned facing the transport path and reads an image from the back side of the document as it is transported along the transport path. After reading begins, the document moves toward the second transport roller pair 14. When the edge sensor 16 detects the trailing edge of the document, the first reading unit 52 and the second reading unit 18 end reading image information as the document is transported a predetermined distance from that position. The document is then discharged to the discharge tray 24 by the discharge roller pair 15. In this way, the document feeder 20 repeats the above-described reading operation until all documents on the document tray 3 are gone.

[Transport guide]
In the configuration of an ADF, a configuration in which ribs are provided on the transport guide 40 to reduce the contact area with the document in order to reduce the sliding resistance of the transport guide 40. When these ribs are removed, the main scanning cross section of the transport path around the reading unit is generally designed to have the same shape no matter where the main scanning cross section is viewed.

The following describes the configuration of the transport guide around the reading unit as a comparative example, using Figures 8(a) and 8(b). Figure 8(a) shows the state when the leading edge of document D1 has reached the gap between the first reading unit 52 and the second reading unit 18, just before reaching the scooping section 25. As shown in Figure 8(a), transport guide 140 has a first guide section 141 located on the outside of the curve of the transport path, between the first reading unit 52 and the pair of transport rollers 13. If document D1 is a stiff document with a large basis weight, such as a business card, the guide surface 141a of first guide section 141 does not come into contact with the middle part of document D1, and the middle part of document D1 is raised.

As shown in FIG. 8(b), when the leading edge of document D1 reaches the scooping section 25, the transport resistance of the leading edge of the document pushes the middle of document D1 in the direction of arrow X, momentarily causing a loop to grow. In this state, even though the document is being fed by the pair of transport rollers 13, the transport amount is used to generate a loop, which can cause the document to stagnate at the reading position and result in image blur. Therefore, in this embodiment, the guide surface 141a of the first guide section 141 is raised only in the center of the width direction toward the inside of the bending center to prevent the formation of a loop during document transport. Note that, although this embodiment describes an increase in transport resistance at the leading edge of document D1 when the leading edge reaches the scooping section 25, this is not limited to this. For example, this embodiment can also be applied when transport resistance increases when the leading edge of document D1 is transported horizontally between the flow reading glass 54 and the reading glass 19.

The configuration of the transport guide 40 of this embodiment will be described in detail below with reference to Figures 3 to 5. As shown in Figure 4(a), the transport guide 40 has a first guide section 43 located on the outside of the curve of the transport path between the first reading unit 52 and the transport roller pair 13, and a second guide section 44 located opposite the first guide section 43 across the transport path. As shown in Figure 3, the first guide section 43 has a first region Ar1 that overlaps in the width direction with the region through which a document of the smallest width that can be transported passes, and a second region Ar2 that is outside the first region Ar1 of the sheet transport region Ar0 in which a document can be transported in the width direction.

In the first region Ar1, which includes the conveyance center in the main scanning direction, multiple first ribs 43a are formed in a row in the width direction. These ribs protrude significantly from the reference surface 43c. In the second region Ar2, which is located outboard of the first region Ar1 in the main scanning direction, multiple second ribs 43b are formed in a row in the width direction. This means that the first ribs 43a protrude more significantly from the reference surface 43c than the second ribs 43b. In this manner, the conveyance guide 40 of this embodiment is designed so that only the first rib 43a in the center of the main scanning direction and the two adjacent first ribs 43a rise toward the center of curvature of the bent portion on the guide surface of the transfer section to the scanning glass 54. In this embodiment, the heights of the first ribs 43a and second ribs 43b vary depending on the amount of protrusion from the reference surface 43c. This reduces the complexity of the manufacturing process compared to conventional methods where all ribs are the same height.

Here, the first guide surface S1 is an imaginary surface formed by connecting the tips of the multiple first ribs 43a in the width direction. The second guide surface S2 is an imaginary surface formed by connecting the tips of the multiple second ribs 43b in the width direction. That is, the first guide section 43 has a first guide surface S1 formed in the first region Ar1 and a second guide surface S2 formed in the second region Ar2. The first guide surface S1 protrudes toward the transport path more than the second guide surface S2. By having the first rib 43a protrude toward the transport path more than the second rib 43b, even if a small-sized document attempts to loop, it abuts against the first rib 43a, thereby suppressing the loop. While this embodiment describes a case where multiple first ribs 43a are provided, this is not limited to this, and a single first rib 43a may also be provided. In this case, the first guide surface S1 is an imaginary surface formed by extending the tips of the first rib 43a in the width direction.

As shown in Figure 4(a), the first rib 43a (first guide surface S1) is positioned so that it overlaps the nip line of the transport roller pair 13. As a result, when a stiff document is transported along the nip line of the transport roller pair 13, it is pressed against the second guide portion 44 to prevent it from floating above the first rib 43a. This makes it possible to suppress loop growth.

In this embodiment, as shown in FIG. 2, the first and second restricting plates 31 and 32 of the document tray 3 are arranged to move symmetrically with respect to the main scanning center plane of the document feeder 20. Specifically, when one of the first and second restricting plates 31 and 32 is moved forward or backward, the other moves in the opposite direction by the same amount, enabling the smallest size that can be accommodated to be business card size of 48 mm x 85 mm. In other words, when the first and second restricting plates 31 and 32 restrict a document of minimum width, the center of document transport overlaps with the first area Ar1 in the width direction. Due to this configuration, the document passes over the first rib 43a regardless of the size of the document being transported.

As shown in FIG. 5, the second guide portion 44 has, in the width direction, a third region Ar3 including an area facing the first region Ar1, and a fourth region Ar4 that is the portion of the sheet transport area Ar0 (see FIG. 3) other than the third region Ar3 (other than the third region). At a position facing the first rib 43a, the second guide portion 44 has a guide surface with a recess 44a in the third region Ar3, which is wider than the first region Ar1, the area where the first rib 43a is formed. That is, the third region Ar3 has a recess 44a that is recessed in a direction away from the first guide portion 43 more than the fourth region Ar4. This prevents the first rib 43a from narrowing the gap between the first guide portion 43 and the second guide portion 44 more than necessary, thereby preventing friction noise due to increased transport resistance and various problems with the scanned image.

Next, the operation of the document reading device 1 having the above-mentioned transport guide 40 will be described using Figures 4(a) and 4(b). As shown in Figure 4(a), when transport of a small, stiff document D1, such as a business card, begins, the middle of the document D1 already abuts against the first rib 43a before the leading edge of the document D1 reaches the guide's scooping section 25. As the document continues to be transported, as shown in Figure 4(b), even if resistance occurs at the leading edge of the document when it reaches the scooping section 25, the document's loop state does not change, thereby suppressing image blurring.

Here, because the first rib 43a protrudes, there is a steep drop in the transfer area between the first guide portion 43 and the flow reading glass 54. Therefore, when the rear end of the document D1 reaches this drop, there is a risk that the rear end of the document will hit the flow reading glass 54, causing a sudden sound. In contrast, in this embodiment, the first region Ar1, which has the first rib 43a, is limited to the center in the width direction, and in the second region Ar2 from the other ends, the drop to the flow reading glass 54 is gentler, as shown in Figure 8(a). This makes it possible to reduce the occurrence of sudden sounds when using documents wider than checks, etc.

Generally circulated business cards are 48-55 mm wide, and checks are often 75-85 mm wide. It is desirable to take thorough measures for these documents and minimize the occurrence of sudden noise when using other wider documents. Therefore, in this embodiment, the spacing between the first ribs 43a located at both ends in the width direction is set to 85 mm or less. On the other hand, if the spacing between the first ribs 43a located on the outermost sides in the width direction is too small, there is a risk of wrinkles forming in the document being transported. Therefore, it is preferable that the spacing between the first ribs 43a be 5 mm or more, and if it is 10 mm or more, the risk of wrinkles forming in the document can be further reduced.

As described above, in the document reading device 1 of this embodiment, the first rib 43a formed in the first region Ar1 protrudes more than the second rib 43b formed in the second region Ar2. This prevents loop growth during document reading and transport, even for small, stiff documents, suppressing image blurring due to document speed fluctuations. Furthermore, only the first region Ar1 is raised, while the transport surface of the remaining, non-raised second region Ar2 is located widthwise outboard of the first region Ar1. This provides a gentler connection from the first guide portion 43 to the flow reading glass 54 in the second region Ar2, mitigating the impact when the document passes through this area and suppressing sudden sounds caused by the impact. This suppresses image blurring for narrow documents such as business cards and checks, which have a large basis weight and are prone to loop growth and image blurring, while also suppressing adverse effects caused by impacts on the trailing edge of wider documents.

Note that while the document reading device 1 of this embodiment has been described above as having the first guide section 43 with the first rib 43a and the second rib 43b, this is not limited to this. For example, the first guide surface S1 and the second guide surface S2 may be formed by flat surfaces without ribs. In this case as well, by forming the first guide surface S1 to protrude more than the second guide surface S2, it is possible to prevent loop growth during document reading and transport, and suppress image blurring caused by fluctuations in the document speed.

Furthermore, while the document reading device 1 of this embodiment has been described as being applied to the image forming device 200, it is not limited to this and can be applied to image reading devices in general.

Second Embodiment
Next, a second embodiment of the present invention will be described in detail with reference to Figures 6 and 7. This embodiment differs from the first embodiment in that the document feeder 120's document feed center is not at the main scanning center of the device but is offset to one side. However, other components are the same as those of the first embodiment, so the same reference numerals are used and detailed description will be omitted.

As shown in FIG. 6 , the document tray 103 has a fixed portion 131, which is an example of a fixed first regulating portion, and a movable plate 132, which is an example of a movably provided second regulating portion. The fixed portion 131 is fixed in the width direction and regulates the position of one side of the width of the document supported on the document tray 103. The movable plate 132 is movable in the width direction and regulates the position of the other side of the width of the document supported on the document tray 103. The width direction position of the document supported on the document tray 103 is regulated between the fixed portion 131 and the movable plate 132 by moving the movable plate 132 towards the front.

In this case, the first guide section 43 of the first embodiment cannot be used because the first area Ar1 is located in the center in the width direction. Therefore, in this embodiment, the first guide section 143 shown in Figure 7 is applied. This first guide section 143 has a first area Ar11 that overlaps in the width direction with the area through which a document of the smallest width that can be transported passes, and a second area Ar12 that is outside the first area Ar11 of the sheet transport area Ar0 in which the document can be transported in the width direction. When the fixed section 131 and movable plate 132 restrict a document of the smallest width, the center of document transport overlaps with the first area Ar11 in the width direction.

In the first region Ar11, multiple first ribs 143a that protrude significantly from the reference surface 143c are aligned in the width direction. In the second region Ar12, which is located further back in the main scanning direction than the first region Ar11, multiple second ribs 143b that protrude less from the reference surface 143c are aligned in the width direction. The first guide surface S11 is an imaginary surface formed by connecting the tips of the multiple first ribs 143a in the width direction. The second guide surface S12 is an imaginary surface formed by connecting the tips of the multiple second ribs 143b in the width direction. In other words, the first guide portion 143 has a first guide surface S11 formed in the first region Ar11 and a second guide surface S12 formed in the second region Ar12, and the first guide surface S11 protrudes toward the transport path more than the second guide surface S12.

As described above, according to the document reading device 101 of this embodiment, the first rib 143a formed in the first area Ar11 protrudes more than the second rib 143b formed in the second area Ar12. Therefore, even for small, stiff documents, loop growth during document reading and transport can be prevented, suppressing image blurring caused by document speed fluctuations. Furthermore, the present invention can be applied even when only one of a pair of regulating sections provided on the document tray 103 moves.

Note that, while the document reading device 101 of the present embodiment described above is described as having a fixed portion 131 on the front side that is fixed and a movable plate 132 on the rear side that is movable, this is not limiting. For example, the first regulating portion on the front side may be movable and the second regulating portion on the rear side may be fixed. In this case, the first region of the first guide portion is positioned on the rear side. Alternatively, the transport center may be at any position, and in this case, the first region of the first guide portion should be aligned with the transport center.

Furthermore, while the above-described embodiments are particularly effective for narrow documents with large basis weights, the effects are not limited to these, and can be achieved with documents of any size and basis weight.

1,101...Document reading device (image reading device), 3,103...Document tray (support portion), 13...Pair of transport rollers, 18...Second reading unit (reading portion, second reading portion), 19...Reading glass (glass plate, second glass plate), 24...Discharge tray (discharge portion), 25...Scooping portion (third guide portion), 31...First regulating plate (first regulating portion), 32...Second regulating plate (second regulating portion), 40...Transport guide, 43,143...First guide portion, 43a,143a...First rib, 43b,143b...Second rib 44...second guide portion, 52...first reading unit (reading portion, first reading portion), 54...swivel glass (glass plate, first glass plate), 131...fixed portion (first restricting portion), 132...movable plate (second restricting portion), 200...image forming device, 201...image forming portion, Ar0...sheet transport area, Ar1, Ar11...first area, Ar2, Ar12...second area, Ar3...third area, Ar4...fourth area, D1...original (sheet), S1, S11...first guide surface, S2, S12...second guide surface

Claims (13)

a support portion that supports the seat;
a discharge section disposed below the support section and into which a sheet is discharged;
a conveyance guide that forms a curved conveyance path for conveying the sheet supported by the support portion to the discharge portion;
a reading unit disposed facing the conveying path and configured to read an image of a sheet conveyed along the conveying path;
a pair of conveying rollers that are arranged upstream of the reading unit in a sheet conveying direction and that convey the sheet when an image on the sheet is read by the reading unit;
the conveyance guide has a first guide portion provided between the reading unit and the pair of conveyance rollers on the outer side of the curve of the conveyance path,
the first guide portion has a first guide surface formed in a first region that overlaps an area through which a sheet of a minimum width that can be conveyed passes, in a width direction that intersects with the conveying direction, and a second guide surface formed in a second region other than the first region within a sheet conveying area that can convey a sheet in the width direction,
The first guide surface protrudes toward the transport path more than the second guide surface.
An image reading device characterized by: the first guide portion has a plurality of first ribs formed side by side in the width direction in the first region,
the first guide surface is formed by tip portions of the plurality of first ribs;
2. The image reading device according to claim 1, wherein: Among the plurality of first ribs, the interval between the first ribs arranged at both ends in the width direction is 5 mm or more and 85 mm or less.
3. The image reading device according to claim 2, wherein: the first guide portion has a plurality of second ribs formed side by side in the width direction in the second region,
the second guide surface is formed by tip portions of the plurality of second ribs;
4. The image reading device according to claim 2, wherein the image reading device is a scanning device. The first guide surface is disposed at a position overlapping a nip line of the pair of conveying rollers.
5. The image reading device according to claim 1, wherein the image reading device is a scanning device. a support portion that supports the seat;
a discharge section disposed below the support section and into which a sheet is discharged;
a conveyance guide that forms a curved conveyance path for conveying the sheet supported by the support portion to the discharge portion;
a reading unit disposed facing the conveying path and configured to read an image of a sheet conveyed along the conveying path;
a pair of conveying rollers that are arranged upstream of the reading unit in a sheet conveying direction and that convey the sheet when an image on the sheet is read by the reading unit;
the conveyance guide has a first guide portion provided between the reading unit and the pair of conveyance rollers on the outer side of the curve of the conveyance path,
the first guide portion has a plurality of first ribs formed side by side in the width direction in a first region overlapping in a width direction intersecting the conveying direction with an area through which a sheet of a minimum width that can be conveyed passes, and a plurality of second ribs formed side by side in the width direction in a second region other than the first region within a sheet conveying area capable of conveying a sheet in the width direction,
Tip ends of the plurality of first ribs protrude toward the conveying path further than tip ends of the plurality of second ribs.
An image reading device characterized by: the transport guide has a second guide portion provided between the reading portion and the pair of transport rollers, facing the first guide portion across the transport path;
the second guide portion has a third region including a region facing the first region, and a fourth region other than the third region in the sheet conveying region,
The third region has a recessed shape that is recessed in a direction away from the first guide portion more than the fourth region.
7. The image reading device according to claim 1, wherein the image reading device is a scanning device. the conveyance guide has a third guide portion located downstream of the reading unit in the conveyance direction and provided on the outer side of the curve of the conveyance path;
8. The image reading device according to claim 1, wherein the image reading device is a scanning device. a horizontal glass plate disposed downstream of the first guide portion in the conveying direction and forming a part of the conveying path;
the reading unit is disposed below the glass plate,
the third guide portion is disposed on the downstream side of the glass sheet in the conveying direction and has an inclined shape such that the downstream side is positioned upward.
9. The image reading device according to claim 8, wherein: the reading unit is a first reading unit that reads an image on a first surface of a sheet,
the glass plate is a first glass plate;
a horizontal second glass plate disposed opposite the first glass plate and forming a part of the transport path;
a second reading unit disposed above the second glass plate toward the conveying path and configured to read an image on a second surface of the sheet conveyed along the conveying path;
10. The image reading device according to claim 9, wherein: the support portion includes a first regulating portion and a second regulating portion that are provided to be movable in conjunction with each other in the width direction and that regulate positions on both sides of the sheet supported by the support portion in the width direction,
a conveyance center of the sheet when the first regulating portion and the second regulating portion regulate the sheet having the minimum width overlaps with the first region in the width direction;
11. The image reading device according to claim 1, wherein the image reading device is a scanning device. The support portion has a first regulating portion that is fixed in the width direction and regulates the position of one side of the width direction of the sheet supported by the support portion, and a second regulating portion that is movably provided in the width direction and regulates the position of the other side of the width direction of the sheet supported by the support portion and regulates the position of the width direction of the sheet supported by the support portion between itself and the first regulating portion,
a conveyance center of the sheet when the first regulating portion and the second regulating portion regulate the sheet having the minimum width overlaps with the first region in the width direction;
11. The image reading device according to claim 1, wherein the image reading device is a scanning device. An image reading device according to any one of claims 1 to 12;
an image forming unit that forms an image on a recording material based on the image read by the image reading device,
An image forming apparatus characterized by: