Document transport device, document reading device, and image forming device

Abstract

To reduce noise in a document conveying device in conveying a tough, small-sized document such as a business card.SOLUTION: A document conveying device is such that a first size document and a second size document having a width smaller than a first size in a direction orthogonal to a document conveyance direction are drawn out by a plurality of roller pairs, and are conveyed along a conveyance path formed by a guide member. At a portion of a first guide surface 511a of the guide member 511 with which the leading end of the first size document fed out by a paper feed roller 53 comes into contact, a second guide surface 513a where the leading end of the second size document approaches is formed behind the portion with which the leading end of the first size document comes into contact. The contact angle θ2 of the second size document relative to the second guide surface 513a is smaller than a contact angle θ1 generated between the document and the first guide surface 511a when the second guide surface 513a is not formed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a document transport device, and a document reading device and an image forming apparatus that are equipped with the document transport device. [Background technology]

[0002] In a sheet-through image reading device, a pickup roller contacts the top surface of the top document placed on a document tray of a document feeder, feeds it onto a conveyance path, and conveys it downstream in the conveyance direction, and reads the document image as it passes over a strip-shaped reading glass that is provided perpendicular to the conveyance direction. The read document is then discharged onto a paper output tray.

[0003] Recently, applications that read images of business cards, convert them into text data using OCR software, and then store and manage the business card information in a database have become popular, and document feeders capable of feeding such small documents are becoming more and more practical.

[0004] However, compared to standard A4 or B5 sized plain paper manuscripts, small sized manuscripts such as business cards have a relatively large basis weight and are therefore stronger.

[0005] In particular, there is a strong demand for space saving in office equipment, and in order to make document transport devices more compact, the transport path from the document tray to the paper discharge tray is formed in a bent shape, and there are many curved parts with a relatively large curvature inside.

[0006] As a result, the leading edge of the document may collide with the curved guide member during transport. In the case of plain paper documents, even if they collide with the guide member, they bend flexibly to absorb the impact force and continue to be transported along the guide surface of the guide member, so there is almost no collision noise. However, in the case of thick paper such as business cards, there is a considerable amount of noise caused by the leading edge of the document colliding with the guide member, which can significantly impair the quietness of the office, especially when scanning a large number of business cards in succession.

[0007] Therefore, for example, in Patent Document 1, in a sheet conveying device capable of conveying cardboard sheets, an impact absorbing member (flexible plate member) made of a flexible material is arranged across the nip portion of a pair of conveying rollers in front of a curved conveying path, thereby reducing the impact of the document on the guide member and achieving quieter operation. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-135188 Summary of the Invention [Problem to be solved by the invention]

[0009] However, according to the configuration of Patent Document 1, it is necessary to separately attach the impact absorbing member to the conveying path, which increases the material cost and the number of assembly steps, and is therefore undesirable from a cost perspective.

[0010] The present disclosure has been made in consideration of the above circumstances, and aims to provide a cost-effective document transport device that has a simple configuration and can suppress the generation of impact noise when transporting small-sized documents made of thick paper such as business cards, as well as a document reading device and image forming device that are equipped with the document transport device. [Means for solving the problem]

[0011] In one aspect of the present disclosure, a plurality of roller pairs are used to form a first size Plain paper The width of the original in the direction perpendicular to the original transport direction is smaller than that of the first size. It has a larger basis weight and is stronger than the plain paper manuscript. A document transport device in which a document of a second size is fed and transported along a transport path formed by a guide member, and the document is fed by a specific roller pair on a first guide surface of the guide member. The aforementioned The first size Plain paper The part where the leading edge of the document touches is The aforementioned The second guide surface into which the leading edge of the second size document enters is Plain paperThe second guide surface is formed so that the leading edge of the document is set back from the contact point, and the contact angle between the second size document and the second guide surface is smaller than the contact angle between the second size document and the first guide surface if the second guide surface is not formed.

[0012] In one aspect of the present disclosure, the guide member has a recessed portion at a portion where the leading edge of the second size document enters, and the second guide surface is formed on a bottom surface of the recessed portion.

[0013] In addition, in one aspect of the present disclosure, the recessed portion is integrally molded with the guide member.

[0014] In another aspect of the present disclosure, the specific roller pair is a roller pair immediately preceding the registration roller pair on the upstream side in the document transport direction.

[0015] Another aspect of the present disclosure is a document reading device that reads a document image while transporting the document using a document transport unit and passing the document through a document reading position in a document reading unit, characterized in that a document transport device according to any one of the above aspects is used as the document transport unit.

[0016] In another aspect of the present disclosure, a third guide surface of a post-reading guide member that guides a document that has passed through a document reading position of the document reading unit includes a roller pair that is located immediately before the third guide surface. The aforementioned The first size Plain paper The part where the leading edge of the document touches is The aforementioned The fourth guide surface into which the leading edge of the second size document enters is Plain paper The fourth guide surface is formed so that the leading edge of the document is set back from the contact point, and the contact angle between the second size document and the fourth guide surface is smaller than the contact angle between the document and the third guide surface if the fourth guide surface is not formed.

[0017] Furthermore, one aspect of the present disclosure is an image forming apparatus that includes a document reading unit that reads a document image and an image forming unit that forms an image on a recording sheet based on image data read and acquired by the document reading unit, and is characterized in that the document reading device of the above aspect is used as the document reading unit. [Effects of the Invention]

[0018] According to the document transport device of the present disclosure, the first guide surface of the guide member, which guides a first size (large size) document, contacts the leading edge of a first size document fed by a specific roller pair, and the second guide surface, into which the leading edge of a second size (small size) document enters, is formed by retreating from the portion where the leading edge of the first size document contacts, so that the contact angle between the second size document and the second guide surface is smaller than the contact angle that would occur between the second size document and the first guide surface if the second guide surface were not formed.As a result, even if the second size document is cardboard, the collision force with the guide member is more likely to escape along the second guide surface, thereby suppressing the generation of collision noise. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an external perspective view of an image forming apparatus including a document transport unit according to the present disclosure; [Figure 2] FIG. 2 is a cross-sectional view showing a configuration of the document transport unit. [Figure 3] 10 is a partial enlarged view for explaining a state in which a recessed portion is formed in a guide member located between a paper feed roller and a pair of registration rollers in the document transport section. FIG. [Figure 4] FIG. 4 is a perspective view showing the shape of a recess formed in the guide member. [Figure 5] FIG. 4 is a cross-sectional view of the guide member taken along line AA in FIG. 3. [Figure 6] This is a diagram to explain the relationship between the contact angle of a business card document on the guide surface (second guide surface) of the recessed portion formed in the above-mentioned guide member and the contact angle of a large-sized plain paper document on the guide surface other than the recessed portion (first guide surface). [Figure 7]FIG. 10 is a diagram showing a state in which a recessed portion for guiding a business card document is formed in a guide member (post-reading guide member) disposed immediately after passing through a first reading position R11 in the document reading unit. [Figure 8] (a) is an oblique view of the guide member immediately after the first reading position in Figure 7, and (b) is a diagram for explaining the relationship between the contact angles with the document at the guide surface (fourth guide surface) formed in the recessed portion and the other guide surface (third guide surface). DETAILED DESCRIPTION OF THE INVENTION

[0020] Below, as an embodiment of a document reading device equipped with a document transport device according to the present disclosure and an image forming device equipped with the document reading device, a multi-function peripheral (hereinafter referred to as "MFP") that combines multiple functions such as a scanner, copier, and printer will be described based on the drawings.

[0021] (1) MFP100 appearance FIG. 1 is a front perspective view showing the appearance of MFP100 according to the present embodiment, in which the left-right direction when MFP100 is viewed from the front side is indicated as the X-axis direction, the up-down direction is indicated as the Z-axis direction, and the depth direction perpendicular to both the X-axis and the Z-axis is indicated as the Y-axis direction.

[0022] As shown in the figure, MFP 100 includes a scanner 110 and a printer 120. MFP 100 has a so-called internal paper discharge configuration, with a paper discharge tray 46 installed in the gap (internal space) DSP between scanner 110 and printer 120, and configured to store sheets discharged from a paper discharge port 45 located at the rear right side of the device in the internal space DSP.

[0023] The scanner 110 has an automatic document feeder (ADF) 50 arranged above an image reading unit 60, and reads document images conveyed by the ADF 50 or document images placed on a platen glass 62 (see Figure 2) to obtain image data.

[0024] The printer 120 includes an image forming unit 10 that forms an image on a recording sheet, and a paper feeding unit 20 that feeds recording sheets to the image forming unit 10.

[0025] The image forming unit 10 uses an electrophotographic method to form a toner image on a recording sheet fed from paper feed tray 11a or 11b of the paper feed unit 20 based on image data obtained by reading an original image with the scanner 110 or image data in a print job received from an external terminal via a network, and after thermally fixing the image in the fixing unit 30 (Figure 7), discharges the image from the paper discharge outlet 45 onto the paper discharge tray 46.

[0026] (2) Scanner configuration FIG. 2 is a cross-sectional view illustrating the configuration of the scanner 110. As shown in FIG.

[0027] The scanner 110 is configured to be capable of reading an original image using both a sheet-through method, which is a type of fixed optical system, and a scanner head moving method, which is a type of moving optical system.

[0028] The sheet-through method is a method in which the document is read by moving the document while the document reading element (scanner head) is kept stationary, while the moving scanner head method is a method in which the document reading element is moved below the document placed on the platen glass to read the document image.

[0029] In the following description, the upstream side and downstream side of the ADF 50 in the document transport direction will be simply referred to as the "upstream side" and the "downstream side", respectively.

[0030] In this embodiment, as shown in FIG. 2, the scanner 110 is equipped with a first document reading element 63 for front side reading, which is installed at a first reading position R11 on the image reading unit 60 side, and a second document reading element 65 for back side reading, which is installed at a second reading position R12 downstream inside the ADF 50, so that the first and second sides of the document can be read in a single pass using the sheet-through method.

[0031] In this embodiment, a CIS (contact image sensor) is used as the first document reading element 63 and the second document reading element 65. A CIS is a type of line sensor, and is an integrated line sensor that is equipped with a fixed-focus lens focused at a fixed distance and a light source, making it possible to make the device more compact.

[0032] However, other optical reading elements may be used as the first document reading element 63 and the second document reading element 65. In particular, the first document reading element 63 may be configured as a so-called mirror scan type in which a carriage equipped with a light source and a mirror moves along below the platen glass 62, and reflected light from the document is focused on the sensor surface of a line sensor via a folding mirror and converted into an image signal. In this case, the carriage is stopped at the first reading position R11 during sheet-through reading.

[0033] In this embodiment, the ADF 50 is configured to be able to transport and read images of business card-sized documents (hereinafter referred to as "business card documents"; in this embodiment, business card documents are assumed to be transported lengthwise (in a direction in which the longitudinal direction is parallel to the transport direction)) in addition to ordinary paper documents such as A4 size and B5 size.

[0034] A stack of documents (not shown) set on the document feed tray 51 of the ADF 50 is aligned by the side guide plate 51a so that the widthwise center of the documents approximately coincides with the widthwise center of the transport path of the ADF 50 (center-based transport).

[0035] The topmost document of a stack of documents set on a document feed tray 51 is separated by a pickup roller 52, a paper feed roller 53, and a separation roller 531, and is transported to a pair of registration rollers .

[0036] A torque limiter (not shown) is attached to the separating roller 531, which applies a constant force to the recording sheet in the opposite direction to the conveying direction. The document is separated into single sheets by passing through a separation nip formed by pressure contact between the rotationally driven paper feed roller 53 and the separating roller 531 equipped with the torque limiter, and then passes through the conveying path between the opposing upper guide member 511 and lower guide member 512 and is conveyed to the downstream registration roller pair 54.

[0037] A recess 513 is formed in the middle of the upper guide member 511, and the business card document enters and is guided into the recess 513, thereby reducing the impact noise with the upper guide member 511. This will be described in more detail later.

[0038] The pair of registration rollers 54 sends the recording sheet downstream at a timing instructed by a document transport control unit (not shown) of the ADF 50.

[0039] The pair of resist rollers 54 is stopped when the leading edge of the document arrives, and a loop is formed in the document just before the upstream nip of the pair of resist rollers 54, correcting the tilt of the leading edge, and then the pair of resist rollers 54 rotates at a predetermined timing to send out the document, thereby performing skew correction.

[0040] The skew-corrected document is then transported to a transport roller pair 55 disposed downstream of the transport roller pair 55. The transport roller pair 55 is disposed immediately before the upstream side of the contact glass 61 at the first reading position R11.

[0041] The document sent out from the pair of registration rollers 54 passes through the pair of transport rollers 55 and is sent out so as to pass above the contact glass 61 at the first reading position R11.

[0042] As a result, the image on the front side of the document is read by the first document reading element 63.

[0043] Then, the document that has passed over the contact glass 61 passes through the pair of transport rollers 56 and below the second document reading element 65 located at the second reading position R12 downstream, and the image on the back side of the document is read by the second document reading element 65.

[0044] The document that has passed through the second reading position R12 is discharged onto a document discharge tray 58 via a pair of discharge rollers 57.

[0045] Note that the above describes a double-sided reading job in which both sides (first and second sides) of a document are read, but in a single-sided reading job in which only the first side of a document is read, only the first document reading element 63 is used.

[0046] 2, the ADF 50 can be opened upward, via a hinge (not shown) at the rear side in the Y-axis direction, and when reading an original image using the scanner head movement method, the original is placed on the platen glass 62 of the image reading unit 60, and the original image is read while moving the first original reading element 63 in the X-axis direction by a movement mechanism (not shown) driven by a drive motor 64. The movement mechanism for the first original reading element 63 can be, for example, a wire drive mechanism or a ball screw mechanism.

[0047] (3) Shape of the upper guide member 511 downstream of the paper feed roller 53 FIG. 3 is a partial enlarged view of the ADF 50 for explaining the shape of the conveyance path and guide members after passing through the nip between the paper feed roller 53 and the separation roller 531.

[0048] As shown in the figure, the document separated into one sheet by the paper feed roller 53 and the separating roller 531 is guided by the opposing upper guide member 511 and lower guide member 512 toward the nip of the pair of resist rollers 54, but because the transport path downstream is curved, the leading edge of the document sent out by the paper feed roller 53 comes into contact with the guide surface of the upper guide member 511, and in the case of a particularly stiff business card document, a relatively loud impact noise is generated compared to a plain paper document.

[0049] As described above, when the rotation of the resist roller pair 54 is temporarily stopped, the guide member in front of the resist roller pair 54 abuts the leading edge of the document in the nip portion, forming a loop in the document, and using its restoring force to make the leading edge of the document parallel to the nip portion, and then the resist roller pair 54 is rotated to perform skew correction.At this time, the upper guide member 511 has a slightly curved portion facing downward (hereinafter referred to as the ``downward curved portion 5111'') formed to make it easier for a loop that bulges downward to form in the document.

[0050] If the leading edge of the business card document directly collides with such a downward curved portion 5111, the contact angle (the angle between the document and the guide surface at the point where the leading edge of the document contacts the guide surface; see θ1 in Figure 6) becomes even larger, making it difficult for the collision force to escape along the guide surface, and increasing the impact noise.

[0051] Therefore, in this embodiment, a recess 513 is formed in the downward curved portion 5111 of the upper guide member 511 at the portion that intersects with the document entry path, thereby reducing the contact angle between the business card document and the guide surface.

[0052] FIG. 4 is an enlarged perspective view showing the downward curved portion 5111 of the upper guide member 511. As shown in FIG.

[0053] The surface of the upper guide member 511 is formed with a first guide surface 511a for guiding large-sized plain paper documents.

[0054] The width W1 of the upper guide member 511 is set to a width (e.g., 35 cm) that is sufficient to guide, for example, an A4-sized document horizontally (transporting the document with its longitudinal direction perpendicular to the transport direction).

[0055] In practice, in order to reduce contact resistance with the document and transport the document smoothly, multiple ribs are often formed parallel to the document transport direction on the guide side surface of guide member 511, and in this case, a flat or curved surface that commonly includes the ridge lines of the multiple ribs is conceptualized as the guide surface. In this specification, for ease of understanding, the ribs are omitted from the illustration and the guide surface is shown. The same applies to the illustrations of other guide surfaces.

[0056] As described above, in this embodiment, the side guide plate 51a provided on the document feed tray 51 of the ADF 50 is designed so that documents of each size are transported using the center reference such that the widthwise center of the document is approximately aligned with the widthwise center of the transport path of the ADF 50.Therefore, a recess 513 of width W2 is formed in approximately the center of the width of the upper guide member 511, and a second guide surface 513a for guiding business card documents is formed on the bottom surface of the recess 513.

[0057] The width W2 is set to a width that is approximately 5 mm wider on both sides than the width of a vertically-oriented business card document, taking into consideration some variation in the conveying position in the width direction.

[0058] Fig. 5 is a cross-sectional view of the upper guide member 511 and the lower guide member 512 taken along line AA in Fig. 3. As shown in the drawing, the bottom surface of a recess 513 formed in the upper guide member 511 forms a second guide surface 513a.

[0059] FIG. 6 is a schematic diagram showing how a business card document D that has passed through the nip N between the paper feed roller 53 and the separating roller 531 comes into contact with the guide surface of the upper guide member 511. As shown in FIG.

[0060] If there were no recess 513, the leading end of the business card document D would collide with the first guide surface 511a of the upper guide member 511 at a contact angle θ1, just like a large-sized plain paper document. However, if, as in this embodiment, a recess 513 is formed in the portion where the business card document D enters and a second guide surface 513a is formed that is set back from the first guide surface 511a, the contact angle θ2 between the leading end of the business card document D and the second guide surface 513a can be made sufficiently smaller than the above θ1, and the impact force at the time of contact is more likely to escape along the second guide surface 513a, thereby reducing the impact noise.

[0061] In addition, it is assumed that the direction in which the business card document D moves after passing through the nip N between the paper feed roller 53 and the separating roller 531 will be in a direction that passes through the nip N and is approximately perpendicular to the line connecting the axial centers 53c and 531c of each roller, if the conditions such as the elastic modulus and diameter of the paper feed roller 53 and the separating roller 531 are exactly the same.Specifically, by analysis such as experiments, the position where the recess 513 is formed and its bottom shape (the curved shape of the second guide surface 513a) can be designed so that the contact angle θ2 is as small as possible compared to the contact angle θ1.

[0062] Incidentally, in the case of business card documents, they are sufficiently stiff that they can be brought into contact with the nip portion of the pair of resist rollers 54 along the second guide surface 513a and skew corrected without forming a sufficient loop as in the case of large-sized plain paper documents.

[0063] Therefore, by forming a recess 513 in the downward curved portion 5111 of the upper guide member 511 upstream of the pair of resist rollers 54, which is sufficiently smaller than the width W1 and has a width W2 sufficient to guide the business card document lengthwise, the sound of the business card document hitting the guide member can be reduced without taking up too much space in the guide member and hindering the compactness of the ADF 50, and for large-sized plain paper documents, a sufficient loop can be formed by the first guide surface 511a to perform skew correction.

[0064] <Modification> The above describes a document transport device according to an embodiment of the present disclosure and an image forming apparatus equipped with the document transport device. However, the content of the present invention is not limited to the above embodiment, and the following modified examples can be implemented.

[0065] (1) Regarding the shape of the guide member 514 immediately downstream of the first reading position R11 In the above embodiment, a recess 513 is formed at the position where the leading end of the business card document abuts on the upper guide member 511 upstream of the pair of resist rollers 54 in the ADF 50, and the recess 513 is formed set back from the first guide surface 511a, with its bottom surface serving as the second guide surface 513a so as to reduce the contact angle of the business card document D; however, if it is necessary to form a recess in the guide member to reduce the contact angle between the business card document D and the guide surface for noise reduction, the recess may be formed in another location.

[0066] For example, as shown in Figure 7, a recess 515 may also be provided in the portion of the guide member (post-reading guide member) 514, which is arranged immediately downstream of the first reading position R11 in the image reading unit 60, where the leading edge of the business card document D abuts.

[0067] FIG. 8(a) is a perspective view of the guide member 514 in FIG. 7 as viewed from above on the front side.

[0068] As shown in the same figure, guide member 514 has a third guide surface 514a for guiding large-sized plain paper documents, and a recess 515 of width W2 is formed in approximately the center of its width direction (Y-axis direction), and a fourth guide surface 515a for guiding business card documents is formed on the bottom surface of recess 515.

[0069] FIG. 8(b) is a schematic diagram showing how the business card document D that has passed the first reading position R11 comes into contact with the guide surface of the guide member 514.

[0070] If there were no recessed portion 515, the leading end of the business card document D would collide with the third guide surface 514a of the guide member 514 at an abutment angle θ3; however, by forming a recessed portion 515 at the portion where the business card document D enters, as in this modified example, and forming a fourth guide surface 515a that is set back from the third guide surface 514a, the abutment angle θ4 between the leading end of the business card document D and the fourth guide surface 515a can be made smaller than the above θ3, making it easier for the impact to escape along the second guide surface 513a, which also contributes to reducing the impact noise.

[0071] As mentioned above, since the ADF 50 can be opened upward relative to the image reading unit 60, it is difficult from a design standpoint to make the guide surfaces of the guide member 514 arranged on the image reading unit 60 side and the guide member 516 arranged on the ADF 50 side (see Figure 7) completely continuous, and a slight gap exists between the two guide surfaces.

[0072] In the case of a plain paper document, there is a risk that the leading edge will droop and curl downward when passing through this gap, and in that case, it may come into contact with the upstream end of guide member 516 and cause a jam. Therefore, it is desirable to design the upstream position of the guide surface of guide member 516 to be slightly lower than the path that is a virtual extension of third guide surface 514a of guide member 514 downstream.

[0073] On the other hand, in the case of business card documents, there is no need to worry about the leading edge curling as with ordinary paper, so even if they are guided by fourth guide surface 515a, which is slightly set back from third guide surface 514a, as long as the extension line of the guide direction by fourth guide surface 515a matches the height of the guide surface on the upstream side of guide member 516, they will be guided continuously and no jam will occur.

[0074] (2) It is desirable that the recessed portion 513 (FIG. 4) in the above embodiment and the recessed portion 515 (FIG. 8(a)) in the modified example be integrally molded with the guide members 511 and 514, respectively, by injection molding or the like. This is because it enables the mass production of guide members with a certain degree of processing accuracy, which contributes to cost reduction.

[0075] (3) In the above embodiment, the small-sized document is described as a business card document, but this is not limited to this. For example, even if the document is slightly larger than a business card, if its basis weight is greater than that of a large-sized plain paper document, its collision with the guide member may cause noise. In this case, the width W2 of the recesses 513 and 515 is set larger accordingly.

[0076] (4) In the above embodiment, an MFP was used as an example of an image forming apparatus equipped with an image conveying device, but this is not limited to this and the present invention can also be applied to image forming apparatuses such as facsimiles and dedicated image reading devices.

[0077] The image forming apparatus may be an image forming apparatus that forms not only color images but also monochrome images, and is not limited to an electrophotographic image forming apparatus but may also be, for example, an inkjet printer.

[0078] <Supplementary information> While the document transport device, document reading device, and image forming device according to the present disclosure have been described above based on the embodiments and modifications, the present invention is not limited to the above-described embodiments and modifications. The present invention also includes forms obtained by applying various modifications to the above-described embodiments and modifications that would occur to a person skilled in the art, and forms realized by arbitrarily combining the components and functions of the embodiments and modifications within the scope of the present invention. [Industrial Applicability]

[0079] The present disclosure is suitable as a noise reduction technique for a document transport device that transports small documents with a large basis weight, such as business cards. [Explanation of symbols]

[0080] 50 ADF (Document Feeder) 51 Document feed tray 52 Pickup roller 53 Paper feed roller 54 Registration Roller Pair 58 Document output tray 60 Image reading unit 100 MFP 110 Scanner 120 printers 511 Upper guide member 511a First guide surface 512 Lower guide member 513 Otoribe 513a Second guide surface 514 Guide member (post-read guide member) 514a Third guide surface 515 Otoribe 515a 4th guide surface 531 Slicing Roller 5111 Downward curve

Claims

1. A document transport device in which a first size plain paper document and a second size document, which has a smaller width in a direction perpendicular to the document transport direction than the first size document and has a larger basis weight and is more rigid than the plain paper document, are fed by a plurality of roller pairs and transported along a transport path formed by a guide member, a second guide surface, into which the leading edge of the document of the second size enters, is formed at a position on the first guide surface of the guide member where the leading edge of the document of the first size plain paper fed by the specific roller pair comes into contact, the second guide surface being set back from the position where the leading edge of the document of the first size plain paper comes into contact; The contact angle of the second size document with the second guide surface is smaller than the contact angle that would occur between the second size document and the first guide surface if the second guide surface were not formed. A document transport device characterized by:

2. The guide member has a recessed portion at a portion where the leading edge of the second size document enters, and the second guide surface is formed on the bottom surface of the recessed portion.

2. The document transport device according to claim 1.

3. The recessed portion is integrally molded with the guide member.

3. The document transport device according to claim 2.

4. The specific roller pair is a roller pair immediately preceding the registration roller pair on the upstream side in the document transport direction.

4. The document transport device according to claim 1, wherein the document transport device is a document transport device.

5. A document reading device that reads a document image by conveying a document by a document conveying unit and passing the document through a document reading position in a document reading unit, The document transport unit is configured to transport a document according to any one of claims 1 to 4. A document reading device characterized by:

6. a third guide surface of a post-reading guide member that guides the document that has passed the document reading position of the document reading unit, the third guide surface being formed at a portion where the leading edge of the first-size plain paper document sent by the immediately preceding roller pair comes into contact, and a fourth guide surface into which the leading edge of the second-size document enters being formed at a position set back from the portion where the leading edge of the first-size plain paper document comes into contact; The contact angle of the second size document with the fourth guide surface is smaller than the contact angle that would occur between the document and the third guide surface if the fourth guide surface were not formed.

6. The document reading device according to claim 5, wherein:

7. An image forming apparatus including a document reading unit that reads a document image, and an image forming unit that forms an image on a recording sheet based on image data read and acquired by the document reading unit, 7. An image forming apparatus, wherein the document reading unit is the document reading device according to claim 5.

Images