JP2020195112A - Image reading device and image forming apparatus - Google Patents

Abstract

To make it possible to remove a foreign substance attached to a transparent member without increasing the size of the device.SOLUTION: An image reading device comprises: a first transparent member 202 that is arranged on one side across a sheet conveyance path; a first image reading unit 201 that reads an image on one side of a sheet through the first transparent member; a second transparent member 222 that is arranged on the other side opposite to the one side across the sheet conveyance path; a second image reading unit 221 that reads an image on the other side of the sheet through the second transparent member; a first guide member 500 that is arranged downstream of the first transparent member in the sheet conveyance direction and guides the sheet to be conveyed; and a second guide member 401 that is arranged downstream of the second transparent member in the sheet conveyance direction and guides the sheet to be conveyed. The second guide member has a projection 401a that projects toward the one side beyond a sheet guide surface of the first transparent member 202.SELECTED DRAWING: Figure 3

Description

The present invention is an image reading device used in, for example, a scanner, a copying machine, a printer, a facsimile machine, or the like, which is an image reading device capable of reading images on both sides of a conveyed sheet and an image forming device including the same. Regarding.

Some image readers used in image forming devices such as digital copiers are equipped with a document transfer device (hereinafter, ADF "Auto Document Feeder") such as a double-sided automatic document transfer device. When the image reader equipped with this type of ADF reads the sheet-shaped document D in the ADF, as shown in FIG. 10, a motor (not shown) is driven between the platen roller 700 and the reading glass 701. The document is read by the reading unit 702 while the document is being conveyed.

In the scanning configuration, the document D is conveyed by rubbing the surface of the scanning glass 701 composed of a transparent glass plate that supports the document. At this time, as shown in FIG. 10, dust g such as toner powder, paper dust, and rubber residue generated during document transportation may adhere to the reading glass 701, but in the case of the reading glass 701 that supports the lower surface of the document. Dust g is often scraped off by the rubbing original and removed as it is.

However, some image readers not only read one side of the original, but also read both sides. Among them, image readers are arranged one above the other across the original transfer path, and both sides of the conveyed document are read once. Some are designed to be read by document transport. In this case, the dust adhering to the lower reading glass (first reading glass) is removed by being rubbed by the document conveyed as described above, but on the upper reading glass (second reading glass). Since the original is not rubbed, the dust adhering to the second reading glass is not removed and remains. If this dust remains attached to the reading position, it will remain as streaks in the read image.

Therefore, a guide member is provided between the first reading glass and the second reading glass in the document transporting direction, and the document transported on the first reading glass by this guide member is conveyed toward the second reading glass. An image reading device configured to be used has been proposed (Patent Document 1).

As described above, the original document that has passed through the first reading glass is conveyed toward the second reading glass, so that even if dust adheres to the second reading glass, the dust is conveyed. It is scraped off by the tip of the document. Therefore, it is possible to suppress the occurrence of streaks in the read image due to the adhesion of dust without specially cleaning the reading glass.

JP-A-2017-00569

However, in the configuration for guiding the document toward the second reading glass as described above, in order to provide the guide member between the first reading glass and the second reading glass, the document is first conveyed in the document transport direction. It is necessary to arrange the reading glass 1, the guide member, and the second reading glass in this order, and the first reading glass and the second reading glass cannot be arranged at positions facing each other with the document transport path in between.

Therefore, a wide area for arranging the reading glass is required, and there is a problem that the apparatus becomes large.

The present invention solves the above problems, and an object of the present invention is to remove foreign matter adhering to a transparent member in an image reading device capable of reading a double-sided image of a sheet-shaped original without increasing the size of the device. An image reading device and an image forming device equipped with the same are provided.

A typical configuration according to the present invention for achieving the above object is a first image reading device for reading an image described on both sides of a sheet to be conveyed, which is arranged on one side of the sheet transfer path. A transparent member, a first image reading unit that reads an image of one side surface of the sheet via the first transparent member, and a first image reading unit arranged on the other side opposite to the one side with the sheet transport path interposed therebetween. The second transparent member, the second image reading unit that reads an image of the other side surface of the sheet via the second transparent member, and the first transparent member are arranged and transported downstream in the sheet transport direction. The second guide member has a first guide member that guides the sheet and a second guide member that is arranged downstream of the second transparent member in the sheet transport direction and guides the sheet to be transported. Is characterized by having a protruding portion protruding to one side of the seat guide surface of the first transparent member.

In the present invention, in an image forming apparatus capable of reading a double-sided image of a sheet, dust and the like adhering to the transparent member can be removed with a simple configuration, and the first transparent member and the second transparent member can be removed. Since the transparent members of the above can be arranged facing each other across the sheet transport path, it is possible to suppress the increase in size of the device.

It is a block diagram of an image forming apparatus. It is a block diagram of an image reader. It is a block diagram of the reading part of an image reader. It is explanatory drawing of scraping dust by the tip of a document. It is explanatory drawing of the document contact position in a transparent member. It is explanatory drawing of scraping dust by the rear end of a document. It is explanatory drawing of the image reading part which concerns on 2nd Embodiment. It is explanatory drawing of the image reading part which concerns on the modification of 2nd Embodiment. It is explanatory drawing which made up the protruding part by a rotating body. It is explanatory drawing of the document reading glass to which dust adhered.

Hereinafter, preferred embodiments of the present invention will be described in detail, exemplary, with reference to the drawings. These image reading devices are suitable for being used as an image reading unit in an image forming device such as a copier or a facsimile, in addition to a case where the device is configured as a single device such as a flatbed scanner equipped with an ADF which is a document transporting device. It is a thing.

It should be noted that the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments are not intended to limit the scope of the present invention to those, unless otherwise specified. Absent.

[First Embodiment]
<Overall configuration of image forming device>
FIG. 1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. In the present embodiment, a copying machine capable of double-sided copying as an image forming apparatus will be described as an example. The image forming apparatus 100 of the present embodiment includes an apparatus main body 101 in which an image forming portion is arranged, an image reading device 200 provided on the upper portion of the apparatus main body 101, and an ADF 300 provided on the image reading device 200. It is configured.

The ADF 300 is designed to automatically convey the sheet-shaped document D placed on the document feeding tray 301 by the user to the image reading device 200. The image reading device 200 receives the reflected light of the light applied to the document conveyed at the scanning position, optically reads the document, converts it into an electric signal, and creates image data based on the electric signal. It has become.

The apparatus main body 101 is provided with an image forming unit 133 that operates an exposure unit 123 based on an electric signal or image data of an image of a document to form an electrostatic latent image on the surface of a rotating photoconductor drum 121. There is. The electrostatic latent image is developed by the developing device 124 to become a toner image.

On the other hand, recording material mounting portions 137a, 137b, 137c, and 137d loaded with recording materials S of various sizes are arranged in the lower portion of the apparatus main body 101. The recording materials S of the recording material mounting portions 137a, 137b, 137c, and 137d are taken out one by one by the feeding rollers 138a, 138b, 138c, and 138d, respectively, and delivered to the transport roller 131. The recording material is also delivered from the manual feed tray 137e to the feeding roller 138e.

After that, the recording material S is straightened by the registration roller pair 136, aligned with the toner image on the photoconductor drum 121, and supplied to the nip portion between the photoconductor drum 121 and the transfer roller 125. .. The recording material S transfers the toner image on the photoconductor drum by applying a bias to the transfer roller 125. The cleaner 127 cleans the surface of the photoconductor drum 121 on which the toner image is transferred. Then, the charging roller 122 charges the surface of the photoconductor drum 121 in preparation for the next exposure.

On the other hand, the recording material S to which the toner image is transferred is conveyed to the fixing device 129 by the conveying unit 128, and is heated and pressurized by the fixing device 129 to fix the toner image on the surface. Then, the recording material S on which the toner image is fixed is discharged to the discharge tray 130.

The image forming apparatus 100 described above is controlled by a control unit 132 having a CPU. Further, the photoconductor drum 121, the charging roller 122, the developing device 124 and the like form the image forming unit 133.

<Image reader>
Next, the configuration of the image reading device 200 will be specifically described with reference to FIGS. 2 and 3. Note that FIG. 2 is a schematic cross-sectional view of the image reading device 200 according to the present embodiment. Further, FIG. 3 shows an enlarged view of the reading unit in FIG.

(ADF)
The image reading device 200 of the present embodiment is provided with an ADF 300 on the upper part of the main body of the device, and the first side of the document automatically transported from the ADF 300 is arranged on one side of the document transport path (sheet transport path). The image reading unit and the second image reading unit arranged on the other side, which is the opposite side of the one side, can read both one side surface and the other side surface of the document.

In the ADF 300, the document feeding tray 301 on which the documents D are stacked and placed is mounted substantially horizontally. Further, below the document feeding tray 301, a document ejection tray 302 for receiving a document whose image is read and sent out at a reading position described later is arranged. These document feeding trays 301 and document ejection trays 3 are arranged so as to face each other vertically at appropriate intervals in the vertical direction, and are arranged so as to be substantially overlapped in a plan view. A document feeding roller 303, a separation roller 304, a retard roller 305, a registration roller pair 306, a transport roller pair 307, 308, and a discharge roller pair 309 are arranged in the ADF 300.

(Original reading operation)
When scanning a document, there is a "sink scanning mode" for scanning the conveyed document as a document scanning mode, and a "fixed scanning mode" for placing the document on the platen glass 240 and scanning while moving the first scanning unit 201. It has.

When the user selects the sink scanning mode and instructs to start scanning, the documents stacked and placed on the document feeding tray 301 by the placement document detection sensor S1 arranged upstream in the document transport direction from the document feeding roller 303. The presence or absence of D is determined. When the document D is detected, the first image reading unit 201 at the standby position P1 of the image reading device 200 is guided to a shaft unit (not shown) while being mounted on the carriage C and moves to the scanning position P2. To do. After that, the document feeding roller 303 descends from the position of the broken line in FIG. 2 to the position of the solid line, and feeds the document D into the inlet-side transport path space in the automatic document transport section. Then, the document conveyed by the rotational driving force of the document feeding roller 303 to the separation roller 304 provided in the inlet side transfer path space is placed between the document and the retard roller 305 spring-loaded on the lower side of the separation roller 304. Separated one by one by frictional force.

The tip of the separated document D is abutted against the registration roller pair 306 that has stopped rotating. The tip of the document D transported to the registration roller pair 306 is detected by a flag (not shown) of the first document detection sensor S2 installed upstream in the document transport direction of the registration roller pair 306.

Then, the drive transmission of the registration roller pair 306 is interrupted by the electromagnetic clutch CL or the like provided in the drive motor M that rotates the registration roller pair 306, and the rotation is stopped for a certain period of time. Since the original is continuously conveyed by the separation roller 304 while the registration roller pair 306 is stopped, a loop is formed at the tip of the original and the skew of the original is removed.

A third document detection sensor S3 is provided in the transport path between the registration roller pair 306 and the upstream transport roller pair 307. The first reading position R1 and the second reading position R2 are located in the transport path between the upstream transport roller pair 307 and the downstream transport roller pair 308. The first reading position R1 is a position for the first image reading unit 201 arranged in the apparatus main body 101 to read the surface of the document, and the second reading position R2 is the second reading position R2 arranged in the ADF 300. This is the position for the image reading unit 221 to read the back surface of the document. At each reading position, a first transparent member 202 that is transparent and guides the document D, for example, plate-shaped glass, and a transparent second transparent member 222, such as plate-shaped glass, are placed in the transport path P. Are arranged on one side and the other side so as to sandwich each other.

The skewed document is conveyed to the upstream transfer roller pair 307 by the registration roller pair 306. The document D is fed to the reading position R1 by the upstream transfer roller pair 307 after the reading timing between the tip of the document and the reading position R1 is taken by the third document detection sensor S3.

The document D has the front surface image read at the first reading position R1, the back surface image is read at the second reading position R2, is conveyed by the transfer rollers 308, and then the document D is conveyed by the discharge rollers 309. It is sequentially discharged and stacked on the mounting surface of the discharge tray 3.

When the fixed reading mode in which the original is placed on the platen glass 240 and read is selected, the rotatable ADF 300 is rotated and opened with respect to the apparatus main body 101 by a hinge mechanism (not shown) to open the original. Is placed on the platen glass 240. Then, when the ADF 300 is closed and the user instructs the copying operation, the first image reading unit 201 waiting at the standby position P1 is guided by the carriage C and moves to the terminal position P3 while reading the image. As a result, the image of the original on the platen glass 240 is read.

(Reading unit)
In the reading unit of the present embodiment, both the first image reading unit 201 and the second image reading unit 221 line the light source using the LED and the photoelectric conversion element in the main scanning direction (direction orthogonal to the document conveying direction). A contact image sensor including a sensor array formed by arranging and a lens array that forms an optical image of a document on the sensor array is used.

The first image reading unit 201 is arranged in the apparatus main body 101, the second image reading unit 221 is arranged in the ADF 300, and the first image reading unit 201 and the second image reading unit 221 are arranged. Are arranged so as to face each other with the document transport path P in between.

A first transparent member 202 is provided between the first image reading unit 201 and the document transport path P, and a second transparent member 222 is also provided between the second reading unit 221 and the document transport path P. Is provided. Then, as shown in FIG. 3, the first transparent member 202 and the second transparent member 222 are arranged in the document transport direction in accordance with the arrangement of the first image reading unit 201 and the second image reading unit 221. , All or part of the document transport path is arranged so as to face each other.

Further, as shown in FIG. 3, a downstream transport lower guide (first guide member) 500 is provided adjacent to the first transparent member 202 downstream of the first transparent member 202 in the document transport direction. There is. The downstream transport lower guide 500 has an inclined guide surface that guides the document diagonally upward in the transport direction.

In the second image reading unit 221, paper dust generated inside the transport path due to the transport of the document does not invade the reading unit of the second image reading unit 221 and the back surface of the second transparent member 222. As shown in FIG. 2, the cover module sealed by the sealing guide G and the second transparent member 222 is configured. The sealing guide G and the second transparent member 222 are fixed with, for example, an adhesive in order to fill a gap in which they overlap each other.

Further, the signal line cable from the second image reading unit 221 is provided with an opening (not shown) in a part of the sealed guide G, and the signal cable is provided in the apparatus main body 101 via the opening. It is connected to the image processing unit. At this time, the periphery of the opening is covered with a sponge-like elastic member so as to surround the signal cable to prevent paper dust from entering. Further, a frame frame (not shown) for supporting the cover module is provided in the vicinity of the sealed guide G, and a part of the frame frame is formed on the upstream side transporting guide 400 and is transported to the first transparent member 202. The tip of the incoming document is guided to the first reading position R1.

Further, on the downstream side in the document transporting direction sandwiching the sealed guide G, a downstream transport upper guide (second guide member) 401 similarly formed from a part of a frame frame (not shown) is provided.

A pressing spring 223 for pressing the second image reading unit 221 against the second transparent member 222 is provided inside the sealing guide G. The second image reading unit 221 is in contact with the back side of the second transparent member 222 by a spacer (not shown). Further, the cover module is pressed in the direction of the first transparent member 202 by a pressing spring 224 connected to the inside of a frame frame (not shown) of the ADF 300.

At this time, a protrusion is provided on a part of the sealing guide G and abutted against the first transparent member 202 to guarantee a gap between the transport path P formed by the first transparent member 202 and the second transparent member 222. .. Further, when the surface of the original is read by the first image reading unit 201, the first reading position of the first image reading unit 201 is placed on the back side of the second transparent member 222 in order to prevent show-through of the thin paper. A white sheet member 225 is provided on the opposite side of R1.

As described above, when reading a document, the first image reading unit 201 provided in the image reading device moves to the first reading position R1. Further, the second image reading unit 221 provided in the ADF 300 reads an image at the second reading position R2. The distance L between the first reading position R1 and the second reading position R2 is determined with an appropriate distance that is not affected by the illumination provided in each image reading unit. In this embodiment, L = 13.5 mm is set.

The document D is conveyed by the transfer roller pairs 307 and 308 and is conveyed onto the first transparent member 202 while being guided by the upstream side lower guide 403 (see FIG. 2) and the upstream side transfer upper guide 400, and is further conveyed to the second transparent member 202. The image is read by the first image reading unit 201 and the second image reading unit 221 while passing through the gap formed by the transparent member 222, the downstream side transport upper guide 401, and the downstream side transport lower guide 500.

In the embodiment, the gap between the first transparent member 202 and the second transparent member 222 is set to 0.6 mm.

The first image reading unit 201 is pressed in the direction of the first transparent member 202 by the pressing spring 203 provided on the carriage C, and spacer members (not shown) attached to both ends of the first image reading unit 201 are the first. By contacting the transparent member 202 of No. 1, an appropriate focal length with the first surface of the document passing through the carriage path is guaranteed.

Similarly, the second image reading unit 221 is pressed in the direction of the second transparent member 222 by the pressing spring 223 provided in the sealing guide G, and is attached to both ends of the second image reading unit 221. A spacer member (not shown) is in contact with the second transparent member 222 to ensure an appropriate focal length with the second surface of the document passing through the transport path.

Further, the surface of the first transparent member 202 is subjected to a conductive coating treatment (ITO treatment), and the surface resistivity is 200 to 500 Ω / cm. Then, as shown in FIG. 3, an aluminum sheet 204, which is a conductive member, is attached to the edge of the first transparent member 202 on the upstream side in the document transport direction from the front surface to the back surface of the first transparent member 202 with a conductive double-sided tape. It is pasted together. The aluminum sheet 204 is electrically conductive with the surface of the first transparent member 202, and is coupled to a conductive device housing 205 such as a sheet metal of an image reading device. The housing 205 is electrically coupled to the image forming apparatus so that the entire apparatus is electrically connected.

Similarly, the surface of the second transparent member 222 is also subjected to a conductive coating treatment (ITO treatment), and the surface resistivity is 200 to 500 Ω / cm. Then, like the first transparent member 202, an aluminum sheet 226 is integrally attached to the vicinity of the edge of the second transparent member 222 via a conductive double-sided tape. Further, like the first transparent member 202, a conductive member (not shown) is electrically coupled to the image forming apparatus to provide conduction.

<Foreign matter scraping configuration>
In the image reading device of the present embodiment, dust such as paper dust adhering to the first transparent member 202 and the second transparent member 222 can be removed during the document reading operation. Next, the configuration for that purpose will be described with reference to FIGS. 4 to 6.

(Scraping configuration of the first transparent member)
First, a configuration for scraping off the dust g1 adhering to the first transparent member 202 will be described. In the feeding operation described above, when the document D is conveyed by the upstream transfer roller pair 307, it is guided by the upstream transfer upper guide 400 coupled with the second transparent member 222, and is guided by the first transparent member 202 and the first transparent member 202. The tip Dt of the document enters in the substantially horizontal direction between the document transport paths P formed between the transparent members 222 of 2. When the document tip Dt reaches the first transparent member 202, the angle formed by the document D with the first transparent member 202 enters an acute angle, and the document tip Dt comes into contact with the first transparent member 202. The document is conveyed by rubbing the surface of the first transparent member 202. Therefore, as shown in FIG. 4A, even if dust g1 adheres to the surface of the first transparent member 202, the dust g1 remains in the original as shown in FIGS. 4B and 4C. It is scraped off by the tip Dt.

Here, the contact position of the tip of the document in the first transparent member 202 whose tip Dt of the document guided to the first transparent member 202 along the upstream transport upper guide 400 by the upstream transport roller pair 307 is shown in FIG. As shown in (a), the document transport path, the upstream transport top guide 400, and the like are set so that the distance from the first reading position R1 is Δa (about 5 mm in this embodiment) so as to make contact upstream in the transport direction. There is. Therefore, even if the dust g1 is attached to the first reading position R1, it can be scraped off by the conveyed document D.

(Scraping configuration of the second transparent member)
Next, a configuration for scraping off the dust g2 adhering to the reading position R2 of the second transparent member 222 will be described.

As described above, the downstream side transport lower guide 500 is provided on the downstream side of the first transparent member 202. As shown in FIG. 6, the downstream side transport lower guide 500 is located below the document guide surface (transport surface) of the first transparent member 202 (second transparent) at the connection portion adjacent to the first transparent member 202. A recess 501 is formed that is recessed in the direction away from the member 222). The downstream transport lower guide 500 is formed with an inclined guide surface 502 inclined so as to guide the document diagonally upward from the downstream of the recess 501 toward the nip of the transport roller pair 308. The inclined guide surface 502 is configured as an inclined surface that guides the document upward from the extension line of the document guide surface of the second transparent member 222.

Further, in the downstream side transport upper guide 401 continuously arranged downstream of the second transparent member 222, a document to be conveyed along the transport surface of the second transparent member 222 is transferred to the first transparent member 202. In order to guide the first transparent member 202 to the side (downward), a protruding portion 401a projecting downward by δ1 from the extension virtual line E of the document transport surface of the first transparent member 202 is formed. The protrusion 401a is provided at a position facing the recess 501 of the downstream transport lower guide 500.

Since the protrusion 401a is provided on the downstream transfer upper guide 401 as described above, the tip of the document that has passed through the second reading position R2 is guided by the protrusion 401a and is below the first image reading unit 201. Will be transported to. At this time, the rear end of the document is lifted upward with the portion in contact with the first image reading unit 201, that is, the downstream end portion 202a of the first transparent member 202 as a fulcrum (see FIG. 6A). Further, since the document is conveyed above the document guide surface of the second transparent member 222 along the inclined guide surface 502, the document is bent into a U shape centering on the protrusion 401a in FIG. 6, and the document rear end De Is conveyed while being in contact with the second transparent member 222 (see FIGS. 6 (b) and 6 (c)). At this time, the rear end De of the document is conveyed in a state where a reaction force F is generated because it is prevented from being bent into a U shape by the second transparent member 222.

Then, when the document D is conveyed as described above, as shown in FIG. 5B, the distance of the document rear end De from the second reading position R2 is Δb (about 3.5 mm in this embodiment). ) The amount of protrusion of the downstream end 202a and the protrusion 401a of the first transparent member 202 and the inclination angle of the tilt guide surface 502 are configured so as to come into contact with the second transparent member 222 on the upstream side in the transport direction. ..

As described above, since the rear end De of the document is conveyed while receiving the reaction force F along the second transparent member 222 until it passes through the downstream end portion 202a, the second transparent member 222 of the second transparent member 222 is conveyed. If dust g2 is attached to the reading position R2, it is transported while being scraped off.

Since the document from which the dust g2 has been scraped off is conveyed as it is along the surface of the second transparent member 222, the dust g2 adhering to the second transparent member 222 is removed from the reading position R2 (see FIG. 6C). ).

The force at which the rear end De of the document abuts on the second transparent member 222 (the reaction force F) depends on the position of the downstream end of the first transparent member 202, the amount of protrusion of the protruding portion 401a, and the like. If the force with which the rear end De comes into contact with the second transparent member 222 is about 0.2 g per unit length, it is sufficient to remove dust such as paper dust, and positively to the second transparent member 222. Since no force is applied, wear of the conductive coating process can be prevented.

Further, the first image reading unit 201 and the second reading unit 221 used in the present embodiment use the contact image sensor as described above. Generally, the contact image sensor has a shallow depth of focus, which is about 0.3 mm to 0.4 mm. Therefore, if the document is separated from the focal direction at the reading positions R1 and R2 during the transfer of the document, the image to be read becomes out of focus.

However, in the present embodiment, since the document is conveyed while being in contact with the protruding portion 400a of the upstream transport upper guide 400 and the protruding portion 401a of the downstream transport upper guide 401, the focus of the first image reading unit 201 It does not deviate significantly from the position. By the same action as this, a good image can be obtained without being significantly deviated from the focal position of the second reading unit 221.

[Second Embodiment]
FIG. 7 is a configuration diagram of a reading unit of the image reading device according to the second embodiment. In the first embodiment described above, the document D that has passed through the first transparent member 202 is guided by the protrusion 401a and bent downward from the extension virtual line E of the document transport surface of the first transparent member 202. As a result, the rear end of the document is curved upward with the downstream end 202a as a fulcrum.

On the other hand, in the present embodiment, the document D is provided with a downstream document guide portion 601 adjacent to the downstream of the first transparent member 202. The downstream document guide portion 601 has a configuration in which the downstream end portion 222a of the second transparent member 222 is located downstream of the downstream end portion 202a of the first transparent member, and the first transparent member 202 is provided. This is to prevent reading defects due to the passing document being separated from the second transparent member 222 and the focal length of the second image reading unit 221 being deviated.

In the configuration in which the downstream document guide portion 601 is provided as described above, the protrusion 401a formed on the downstream transport upper guide 401 is δ2 more than the extension virtual line F of the document guide surface of the downstream document guide portion 601. It is configured to protrude downward. As a result, the tip of the document that has passed through the second reading position R2 is guided by the protrusion 401a and is curved and conveyed downward from the document guide surface of the downstream document guide unit 601. At this time, the rear end of the document is lifted upward with the downstream end 601a of the downstream document guide portion 601 as a fulcrum, and the rear end of the document is conveyed while being in contact with the second transparent member 222, and is conveyed while being in contact with the second transparent member 222. It is transported while scraping off the dust adhering to the.

As shown in FIG. 8, the downstream document guide unit 601 adjacent to the first transparent member 202 moves the document passing through the first transparent member 202 diagonally upward, that is, toward the second transparent member 222. It may be shaped to guide. Also in this case, the projecting portion 401a formed on the downstream transport upper guide 401 is configured to project downward from the downstream end portion 601a of the downstream document guide portion 601 so that the rear end of the document is a second transparent member. It comes into contact with 222.

Further, the downstream document guide unit 601 and the downstream side transport lower guide 500 may be integrally configured or may be configured separately.

[Other Embodiments]

In the above-described embodiment, the projecting portion 401a is formed on the downstream transfer upper guide 401 so that the rear end of the document to be transported comes into contact with the second transparent member 222. At this time, it is preferable that the protruding portion 401a is formed in a curved shape because the document is smoothly guided. In addition to the curved surface shape, as shown in FIG. 9, a rotating body 402, which is a small rotatable roller, may be provided as the protruding portion.

Even if the protruding portion is formed by the rotating body 402 as described above, the document D is conveyed while being bent in a substantially U shape toward the recess 501 by the rotating body 402, and is conveyed to the rear end of the document, as in the above-described embodiment. Is conveyed while being in contact with the second transparent member 222, so that dust adhering to the second transparent member 222 can be scraped off. Further, since the rotating body 402 is provided at the portion where the document to be conveyed by being bent into a U shape comes into contact with the document, the transfer load of the document is reduced.

Further, it is sufficient that at least one protrusion 401a or a rotating body 402 in the above-described embodiment is provided in the main scanning direction, and a plurality of protrusions 401a or rotations are appropriately provided according to the width of the document D supported by the image reader. A body 402 may be provided.

Further, the protruding portion 401a or the rotating body 402 may be configured to protrude over the entire area in the main scanning direction.

Further, the rotating body 402 may be one that is driven and rotated by a driving force from a driving source, in addition to one that is driven to rotate when the document is conveyed.

D ... Original De ... Rear end Dt ... Original tip E ... Virtual line P ... Transport path R1 ... First reading position R2 ... Second reading position g1 ... Dust g2 ... Dust 100 ... Image forming device 133 ... Image forming unit 200 ... Image reading device 201 ... First image reading unit 202 ... First transparent member 202a ... Downstream end portion 221 ... Second image reading unit 222 ... Second transparent member 240 ... Document base glass 300 ... ADF
307… Upstream transport roller pair 308… Downstream transport roller pair 309… Discharge roller pair 400… Upstream transport upper guide 401… Downstream transport upper guide 401a… Protruding part 402… Rotating body 403… Upstream side lower guide 500… Downstream Side transport lower guide 501 ... Recessed 502 ... Inclined guide surface

Claims (8)

In an image reader that reads an image written on both sides of a sheet to be conveyed,
The first transparent member arranged on one side of the sheet transport path,
A first image reading unit that reads an image of one side surface of the sheet via the first transparent member,
A second transparent member arranged on the other side opposite to the one side across the sheet transport path, and
A second image reading unit that reads an image of the other side surface of the sheet via the second transparent member,
A first guide member, which is arranged downstream in the sheet transport direction of the first transparent member and guides the sheet to be transported,
A second guide member, which is arranged downstream in the sheet transport direction of the second transparent member and guides the sheet to be transported,
Have,
The sheet reading device is characterized in that the second guide member has a protruding portion protruding to one side of the sheet guide surface of the first transparent member. The sheet reading device according to claim 1, wherein the first guide member guides a sheet that has passed through the protruding portion to the other side of the sheet guide surface of the second transparent member. In an image reader that reads an image written on both sides of a sheet to be conveyed,
The first transparent member arranged on one side of the sheet transport path,
A first image reading unit that reads an image of one side surface of the sheet via the first transparent member,
A second transparent member arranged on the other side opposite to the one side across the sheet transport path, and
A second image reading unit that reads an image of the other side surface of the sheet via the second transparent member,
A first guide member, which is arranged downstream in the sheet transport direction of the first transparent member and guides the sheet to be transported,
A second guide member which is arranged downstream in the sheet transport direction of the second transparent member and guides the sheet to be transported, and has a protruding portion protruding toward the first transparent member. Members and
Have,
The downstream end of the first guide member in the sheet transport direction is located upstream of the protrusion in the sheet transport direction.
A sheet reading device characterized in that the protruding portion protrudes to one side of the seat guide surface of the first guide member. The invention according to any one of claims 1 to 3, wherein at least a part of the first transparent member and the second transparent member face each other with the sheet transport path interposed therebetween. Sheet reader. The sheet reading device according to any one of claims 1 to 4, wherein the protruding portion is composed of a rotating body. The method according to any one of claims 1 to 5, wherein the reading position by the second image reading unit is located downstream of the reading position of the first image reading unit in the sheet transport direction. Sheet reader. The sheet reading device according to any one of claims 1 to 6, wherein the first transparent member and the second transparent member are electrically conductive with the device housing. The sheet reading device according to any one of claims 1 to 7.
An image forming part that forms an image on the sheet,
An image forming apparatus characterized by having.

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