JP2008211445A - Original feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an original from floating at an original reading position, and to improve the bending strength of a guide plate for guiding the original conveyed to the original reading position in an original feeder of "an original scanning system". <P>SOLUTION: A protrusion 63 is formed in a direction crossing an original conveying direction so that it may protrude to an original reading side in an original conveying area at the original reading position of a guiding plate 6 and a flat surface 64 is formed in a non-original conveying area at the original reading position. In order to reliably prevent the original P from floating, it is preferable to make a cross section shape in an orthogonal direction to the longitudinal direction of the protrusion 63 a trapezoid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a document feeding device, and more particularly, by a fixed image reading mechanism that allows a document to pass through a gap between a document reading surface and a guide plate provided to face and separate from the document reading surface. The present invention relates to a document feeder for reading a document image.

  Many image reading devices built in image reading devices such as digital copying machines, facsimiles, and scanners irradiate a document with light emitted from a light source, and the reflected light is an image sensor such as a CCD (Charge Coupled Device). The document image is detected and detected.

  The image reading apparatus may be provided with a document feeder. As a document feeder, a device that reads a conveyed document with a fixed image reading mechanism (so-called document flow reading) has been generally used in recent years.

FIG. 5 is a schematic diagram of a document reading unit in a conventional document feeder. In this document feeder figures, guide plate 6 'is provided at a distance opposite to the upper surface of the contact glass C ₁ (document reading surface). The upper surface of the contact glass C ₁ and the guide plate 6 ′ are substantially parallel planes. In the document feeder having such a configuration, when the document P passes through the gap between the contact glass C ₁ and the guide plate 6 ′, the document image is read by an image reading device (not shown) such as an image sensor. Note is under the lower surface of the contact glass C ₁ is the image reading mechanism (not shown) is disposed.

In order to increase the resolution of the read image, it is only necessary to narrow the gap and bring the original P into close contact with the upper surface (original reading surface) of the contact glass C _1. However, the original P having various thicknesses can be read smoothly. Therefore, it is necessary to determine the gap in consideration of the maximum thickness of the document P to be conveyed. In addition, since the document transport path of the document feeder is generally U-shaped with the document reading position as the lowest point, when the gap is set to the maximum thickness of the document P to be transported, the U-shaped transport path There is a risk that the document P bent in step S will be rubbed by the guide plate 6 'and a large load will be applied to the document, causing abnormal images and document jams. For this reason, the gap is generally set to be equal to or greater than the maximum thickness of the document P to be conveyed.

  When a plain paper document is passed through a gap that is set wider than the maximum thickness of the conveyed document, a problem arises that the document floats. If the original floats at the original reading position, the resolution of the image is lowered and image blurring occurs. In the case of a color image, a color shift occurs.

Therefore, in Patent Document 1, for example, a protrusion having a mountain-shaped cross section is formed on the guide plate at the document reading position, and the document is pressed against the contact glass at the document reading position to prevent the document from being lifted. Techniques for improvement have been proposed.
JP-A-7-172618

  However, in the proposed technique, since the protrusion is formed over the entire width direction of the guide plate, the bending strength is low, and the guide plate may be deformed, for example, in the manufacturing process.

  The present invention has been made in view of such a conventional problem, and an object of the present invention is to prevent a document from being lifted at a document reading position in a so-called document-feeding-type document feeding device, and at the same time to convey the document. An object of the present invention is to provide a document feeder in which the bending strength of a guide plate for guiding a document that has been guided to a document reading position is increased.

  According to the present invention, a document that allows a document to pass through a gap between a document reading surface and a guide plate provided to face and separate from the document reading surface, and to read a document image by a fixed image reading mechanism. In the feeding device, a protrusion is formed in a direction intersecting with the document conveyance direction so as to protrude toward the document reading surface in the document conveyance area of the guide plate at the document reading position, and non-document conveyance at the document reading position. There is provided a document feeder characterized by forming a flat portion in a region. In the present specification, the “document transport area” means the maximum document width that can be transported by the document feeder.

  Here, from the viewpoint of more reliably preventing the document from floating, it is preferable that the cross-sectional shape in the direction orthogonal to the longitudinal direction of the protrusion is trapezoidal.

  Also, from the viewpoint of precisely controlling the gap between the document reading surface and the guide plate, it is desirable to form a protrusion that contacts the document reading surface on the flat surface portion so as to determine the gap interval.

  From the viewpoint of improving the reading accuracy of the document image and smoothly transporting the document, the gap between the document reading surface and the guide plate is the narrowest at the document reading position and goes upstream from the document reading position in the document transport direction. It is preferable that the width gradually increases in accordance with the position of the original, and further increases gradually toward the downstream side in the document transport direction from the document reading position.

  In the document feeder of the present invention, since the protrusion is formed in the document conveyance area of the guide plate at the document reading position so as to protrude toward the document reading surface, the protrusion is formed in a direction intersecting the document conveyance direction. This effectively prevents the document from floating. Further, since the flat portion is formed in the non-document conveying area at the document reading position, the bending strength of the guide plate is remarkably increased.

  If the cross-sectional shape in the direction orthogonal to the longitudinal direction of the protrusion is trapezoidal, the document can be more reliably prevented from floating.

  Further, by forming a protrusion that contacts the document reading surface on the flat surface portion and determining the gap interval, the gap between the document reading surface and the guide plate can be precisely controlled.

  The gap between the document reading surface and the guide plate is such that the document reading position is the narrowest and gradually increases from the document reading position toward the upstream side of the document transport direction, and further from the document reading position to the document transport direction. By gradually increasing the width toward the downstream side, the document image reading accuracy is improved, and at the same time, the document is conveyed more smoothly.

  Hereinafter, the document feeder according to the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

FIG. 1 is a schematic diagram showing an embodiment of a document feeder according to the present invention. 1 is a diagram illustrating a state in which the document feeding device in FIG. 1 is mounted on the upper surface of a copying machine that is an image forming apparatus. A first contact glass C ₁ and a second contact glass C ₂ are attached to the upper surface of the copying machine. The first contact glass C ₁ is used when reading a document using a document feeder, and the second contact glass C ₂ is used when reading a document without using a document feeder.

  On the other hand, a housing H of the document feeder has a paper feed tray 51 for loading a plurality of documents P, and a discharge tray for discharging the documents P fed from the paper feed tray 51 and whose contents are read by the document reading unit. 52 are juxtaposed in the vertical direction. On the other hand, the structure in the housing is roughly divided into a sheet feeding means 1, a transport unit 2, a switchback unit 3, and a discharge unit 4. The paper feeding means 1 includes a pickup roller 17 that pulls out the originals P stacked on the paper feeding tray 51, a paper feeding roller 11 that separates and sends out the drawn originals P, a separation pad 12, and a separation pad 12 And a pad holder 13 for holding A guide 16 is formed in the conveyance path downstream of the separation pad 12 in the conveyance direction.

The conveyance unit 2 includes a rotatable large-diameter feed roller 21, a registration roller 22 that presses against the outer peripheral surface, and a scooping roller 23. An image reading mechanism 7 is provided below the first contact glass C ₁ between the registration roller 22 and the scooping roller 23. The image reading mechanism 7 includes a light source 71, a plurality of mirrors 72, 73,..., And an image sensor (not shown). The light emitted from the light source passes through the first contact glass C ₁ and irradiates the image forming surface of the document. Of the light applied to the document, the light applied to the image portion is absorbed, and the light applied to the non-image portion is reflected. The reflected light passes through the first contact glass C ₁ again, is reflected by the mirrors 72 and 73, changes its traveling direction, enters a not-shown image sensor, and is read as a document image. The registration roller 22 and the scooping roller 23 are driven by the rotation of the feed roller 21 in the direction of the arrow.

  The switchback unit 3 includes a switching member 31 and a switchback roller pair 32. In the case of single-sided reading of a document, the switching member 31 is in the position of the solid line and closes the conveyance path in the direction of the switchback roller pair, while releasing the conveyance path in the paper discharge direction. As a result, the original P from which the image has been read is guided to the paper discharge roller pair 41 via the scooping roller 23. On the other hand, in the case of reading both sides of a document, the switching member 31 swings counterclockwise around the shaft 31a to the position indicated by the broken line in the figure to block the conveyance path in the direction of the discharge roller pair, while in the direction of the switchback roller pair. Release the transport path to. As a result, the original P from which the image on one side has been read is conveyed to the switchback roller pair 32. The document P is sent out to the right in the figure by the switchback roller pair 32. When the trailing edge of the document is sandwiched between the switchback roller pair 32, the switchback roller pair 32 rotates in the reverse direction, and the document P is sent out to the feed roller 21. The document P that is rotated and conveyed again in the direction of the arrow by the feed roller 21 passes through the document reading unit, and the document image on the opposite side to the previous one is read. Here, the original P may be discharged in this state. However, if the original P is discharged as it is, the front and back sides of the original are opposite to the original state. Therefore, the original is again fed by the feed roller 21 using the switchback roller pair 32. The document is rotated and conveyed, the document is returned to the original state, and then discharged.

  The discharge unit 4 includes a discharge roller pair 41. The document P that is nipped and conveyed between the feed roller 21 and the scooping roller 23 is guided to the conveyance path in the direction of the discharge roller pair by the switching member 31 at the solid line position in the figure, and is discharged to the discharge tray 52 by the discharge roller pair 41. The

FIG. 2 is an enlarged cross-sectional view of the document reading unit. A guide plate 6 is provided so as to face the upper surface (original reading surface) of the first contact glass C _{1 at} a distance. The guide plate 6 is formed by integrally forming a bottom surface portion 61 on which the ridge 63 is formed and inclined portions 62a and 62b extending at a predetermined angle from both sides of the bottom surface portion 61 upward. The gap between the first contact glass C ₁ and the guide plate 6 is the narrowest at the document reading position where the protrusion 63 is formed, and becomes wider from the document reading position to the upstream side and the downstream side in the document transport direction. As a result, the original conveyed to the original reading unit is smoothly carried into and out of the original reading position.

Then, when the document P passes through the gap between the first contact glass C ₁ and the guide plate 6, the document image formed on the surface of the document P is read by the image reading mechanism 7 (shown in FIG. 1). . One of the important components in the document feeder of the present invention is that the guide plate 6 is provided with a ridge 63 in the document conveyance area at the document reading position. This narrows the gap between the first contact glass C ₁ and the guide plate 6 at the document reading position, and effectively prevents the document P from being lifted when the document P is read.

  Although the protrusion 63 shown in FIG. 2 is formed integrally with the guide plate main body, the protrusion 63 may be formed separately and then fixed to the guide plate main body. In view of productivity and strength, the protrusion 63 is preferably formed integrally with the guide plate body. The height of the ridge 63 is not particularly limited, but when the gap between the document reading position before and after the document conveyance direction is set to 0.8 mm, for example, the height of the ridge 63 is about 0.3 mm, that is, the document. The gap at the reading position is practically about 0.5 mm.

  FIG. 3 shows a perspective view of the guide member 6 used in FIG. The guide plate 6 in this figure has a thin plate-like bottom surface portion 61 and inclined portions 62 a and 62 b extending upward at a predetermined angle from both longitudinal sides of the bottom surface portion 61. A plurality of notches 66 are formed in the inclined portions 62a and 62b at predetermined intervals in the longitudinal direction, and a plurality of protrusions 67 are formed in the inclined portions between the notches. These protrusions 67 are used to prevent the front and rear ends of the original P from fluttering when the original P is conveyed to the original reading position and when the original P is discharged from the original reading position. It is. The shape, number, height, and the like of these protrusions may be appropriately determined from the shape and width of the document conveyance path.

The above-described protrusion 63 is formed in the document conveyance area in the longitudinal direction of the bottom surface portion 61. In addition, flat portions 64 are formed in the non-document conveying areas on both sides in the longitudinal direction of the ridge 63. The guide plate 6 used in the present invention is provided with flat portions 64 on both sides in the longitudinal direction of the ridge 63 as compared with the conventional guide plate in which the ridge is formed over the entire length of the bottom surface portion 61. It can sufficiently withstand bending stress from the short direction. There is no particular limitation on the width of the flat portion 64, and a few cm ² is sufficient.

A pair of protrusions 65 a and 65 b are formed on the flat surface portion 64 provided on the bottom surface portion 61. The pair of projections 65a, 65b are in contact with the first contact glass C ₁ when the guide member 6 mounted on the document feeder those, width of the gap between the guide member 6 and the first contact glass C ₁ is determined. If the height of the protrusions 65a and 65b is set to 0.8 mm, for example, the gap interval can be set to 0.8 mm without being affected by an assembly error of the apparatus. Of course, the protrusion for forming the gap may be formed on the first contact glass C ₁ side, but it is desirable to form the protrusion on the guide member 6 from the viewpoint of ease of molding. The protrusions may be formed integrally with the guide plate 6 or may be fixed to the guide plate 6 after being formed separately.

  In addition to the trapezoidal shape shown in FIG. 2, the cross-sectional shape of the protrusion 63 formed on the guide plate 6 used in the present invention is a circular shape (FIG. 4A) or a triangular shape (FIG. b)).

It is a schematic diagram showing an example of a document feeder according to the present invention. FIG. 2 is an enlarged view of a document reading unit of the document feeder of FIG. 1. It is a perspective view which shows an example of the guide plate used by this invention. It is sectional drawing which shows the other example of the guide plate used by this invention. It is an enlarged view showing a document reading unit of a conventional document feeder.

Explanation of symbols

6 Guide plate 7 Image reading mechanism C ₁ First contact glass P Original 63 Projection 64 Plane portion 65a, 65b Projection

Claims (5)

In a document feeding device that allows a document to pass through a gap between a document reading surface and a guide plate provided to face and separate from the document reading surface, and reads a document image by a fixed image reading mechanism.
A protrusion is formed on the guide plate in the document conveyance area at the document reading position so as to protrude toward the document reading surface, and a flat portion is formed on the non-document conveyance area at the document reading position. A document feeder characterized by forming a document.   The document feeder according to claim 1, wherein a cross-sectional shape in a direction perpendicular to the longitudinal direction of the protrusion is a trapezoid.   3. A document feeding apparatus according to claim 1, wherein a protrusion that abuts on the document reading surface is formed on the flat portion so as to determine an interval between the document reading surface and the guide plate at the document reading position.   4. The document feed according to claim 1, wherein a gap between the document reading surface and the guide plate is narrowest at the document reading position and gradually increases toward the upstream side in the document transport direction from the document reading position. apparatus.   5. The document feed according to claim 1, wherein a gap between the document reading surface and the guide plate is the narrowest at the document reading position and gradually increases from the document reading position toward the downstream side in the document transport direction. apparatus.

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