JP2006129253A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of reading an image on a whole side of an original at one and the same focal position and reading the image with less out of focus. <P>SOLUTION: The image reading apparatus is configured such that a carrying belt 16 is stretched between rollers 3a, 4a, the original 18 is carried by the carrying belt 16, motor fans 31, 32 closely adhere the original 18 to the carrying belt 16 by their wind pressure to prevent the original 18 from being floated thereby keeping a distance between a SELFOC lens 24 and the original 18 constant. Since an image forming position to an image sensor 25 can be made constant even when the SELFOC lens 24 with a shallow field depth is in use as a result, the image sensor 25 can read an image of the whole side of the original 18 at one and the same focal position and the image reading apparatus can read the image with less out of focus. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus, and relates to an image reading apparatus that conveys a document and reads an image using a photoelectric conversion element, such as a copying machine or a FAX.

  For example, an image forming apparatus such as a digital copying machine incorporates an image reading device. The image reading apparatus is configured to convey an original by a conveying roller, irradiate light on the surface of the original, and photoelectrically convert reflected light from the original surface by a photoelectric conversion element to read an image on the original.

  However, since originals having various thicknesses are used, the read image position may be shifted due to the change in thickness. In particular, when a CIS (Contact Image Sensor) is used as a photoelectric conversion element, a Selfoc lens is used to guide reflected light to the image sensor. Since the depth is shallow, an incident image is blurred and the resolution is lowered unless the focus position is adjusted precisely.

  For this reason, Japanese Patent Laid-Open No. 2003-32442 (Patent Document 1) detects the thickness of a document, and the imaging position of the image on the photoelectric conversion element by the lens is fixed according to the detected thickness. An image reading apparatus that controls the position of the conveyance roller is described.

In Japanese Patent Laid-Open No. 9-23304 (Patent Document 2), a document carrier sheet made of a translucent sheet member in contact with a read image surface of a document is placed on the document in order to reduce document shadow, and the translucent sheet member An image forming apparatus is described in which a document is read through the image forming apparatus to eliminate the floating of the document.
Japanese Patent Laying-Open No. 2003-32442 (paragraph number 0027, FIG. 8) JP-A-9-23304 (paragraph numbers 0011 to 0013, FIG. 1)

  However, in Patent Document 1, there are variations in the housing of the photoelectric conversion element, the glass surface on which the document is placed also warps, and in particular, there is variation in the position of the document at the leading and trailing edges of the document. Therefore, it is extremely difficult to pass the image on the entire surface of the document through the best focus position of the photoelectric conversion element.

  Also, as in Patent Document 2, placing a document carrier sheet, which is a translucent sheet member, on a document every time the document is read places a burden on the user and is inefficient.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading apparatus capable of reading an image on the entire surface of an original at the same focus position and enabling image reading with little focus blur.

  The present invention is an image reading apparatus for reading an image of a document, a transport belt for placing and transporting a document, a reading unit for reading an image of a document on the transport belt, and a proximity of the reading unit And a wind pressure means for bringing the document into close contact with the conveying belt by wind pressure.

  Further, a duct surrounding the reading unit is included, and the wind pressure unit sends wind into the duct so that the periphery of the document reading unit is in close contact with the conveying unit.

  Preferably, a substrate that generates heat is disposed in the duct, and the substrate is cooled by wind from the wind pressure means.

  In a specific embodiment, the conveying unit is a conveying belt in which a plurality of holes are formed, and the wind pressure unit sucks the document through the plurality of holes in the conveying belt.

  Preferably, the wind pressure applying means is a motor fan and a plurality of wind pressure applying means are provided.

  In the present invention, wind pressure is applied to the original conveyed by the conveying belt by the wind pressure means so that the original does not float, and the original is brought into close contact with the conveying means, and the distance between the original and the reading means is kept constant. Therefore, the image on the entire surface of the original can be read at the same focus position, and the image can be read with little out-of-focus.

  FIG. 1 is a schematic view showing a document conveyance path of an image reading apparatus according to an embodiment of the present invention, and FIG. 2 is a view showing an image reading apparatus according to an embodiment of the present invention.

  In FIG. 1 and FIG. 2, documents are placed on the document tray 1, and the documents are taken one by one by the paper feed roller 2. The taken document is conveyed by a conveyor belt 16 that is stretched between rollers 3 and 4, further conveyed by conveyor rollers 5 a and 5 b, 6 a and 6 b, 7 a and 7 b, and discharged to the discharge tray 8. The conveyor belt 16 has a width equal to or greater than that of the document 18. A reading unit 20 made of CIS or the like is disposed between the rollers 3 and 4. The reading unit 20 reads an image on the document 18.

  The reading unit 20 is provided with a glass 21 facing the document 18, lamps 22 and 23 are disposed on the glass 21, and a SELFOC lens 24 is provided between the lamps 22 and 23. It has been. An image sensor 25 is disposed on the optical axis of the Selfoc lens 24.

  Motor fans 31 and 32 as wind pressure means are provided on the upstream side and the downstream side in the conveyance direction of the reading unit 20. The motor fans 31 and 32 generate wind pressure in the direction indicated by the arrow, and the document 18 is blown onto the conveying belt 16 by this wind pressure. Since the conveyance belt 16 is selected so as to have a width equal to or greater than that of the document 18, the document 18 does not float and is in close contact with the conveyance belt 16. The lamps 22 and 23 irradiate the document 18, and the reflected light is incident on the image sensor 25 via the Selfoc lens 24 to read the image of the document 18.

  Therefore, according to this embodiment, since the original 18 is brought into close contact with the conveying belt 16 by the wind pressure by the motor fans 31 and 32 and the original 18 is prevented from being lifted, the distance between the original 18 and the Selfoc lens 24 is kept constant. be able to. As a result, the image formation position on the image sensor 25 can be made constant even when the Selfoc lens 24 having a shallow subject depth is used, so that the image on the entire surface of the document 18 is read by the image sensor 25 at the same focus position. Therefore, it is possible to read an image with little defocusing.

  FIG. 3 is a diagram showing an image reading apparatus according to another embodiment of the present invention. In this embodiment, a reading device 20 is surrounded from above, a duct 40 having an open bottom is provided, and a motor fan 31 is disposed on the top of the duct 40. The reading device 20 is configured by CIS as in FIG.

  In the embodiment shown in FIG. 2, since the motor fans 31 and 32 are not surrounded by a duct, it is difficult to bring the document 18 into close contact with the conveyance belt 16 with a constant and uniform wind pressure. On the other hand, in the embodiment shown in FIG. 3, the document 18 can be brought into close contact with the conveyance belt 16 by making the periphery of the reading unit 20 in the duct 40 constant air pressure by the motor fan 31. Lifting can be prevented.

  As a result, the distance between the document 18 and the SELFOC lens 24 can be maintained at a certain distance, and the image on the entire surface of the document 18 can be read by the image sensor 25 at the same focus position. It becomes possible. Furthermore, in this embodiment, the image sensor 25 can also be cooled by blowing air from the motor fan 31.

  FIG. 4 is a view showing an image reading apparatus in still another embodiment of the present invention. In this embodiment, the duct 41 is formed in an L shape including a horizontal portion and a vertical portion, the substrate 42 is disposed in the horizontal portion of the duct 41, and the reading unit 20 is disposed in the vertical portion of the duct 41. . Then, the motor fan 31 blows air into the horizontal portion of the duct 41 to cool the substrate 42, and the air around the reading unit 20 disposed in the vertical portion of the duct 41 is kept at a constant wind pressure to place the document 18 on the transport belt 16. Adhere closely. As the substrate 42, it is preferable to arrange a power supply substrate on which a heat generating component is mounted. Also in this example, the image sensor 25 is cooled by the air blown from the motor fan 31.

  In this embodiment, the substrate 42 and the image sensor 25 in the duct 41 are cooled by the motor fan 31, and a constant wind pressure is applied to the periphery of the reading unit 20 to bring the document 18 into close contact with the belt 16 to lift the document 18. Can be prevented.

  FIG. 5 is a diagram showing an image reading apparatus according to still another embodiment of the present invention. In this embodiment, a motor fan 31 is disposed on the conveyor belt 16 side, and a plurality of holes are formed in the conveyor belt 16 (not shown). When the motor fan 31 rotates, the conveying belt 16 side is sucked and wind pressure is generated in the direction of the arrow.

  Since the transport belt 16 has a plurality of holes, the document 18 is prevented from being attracted to the transport belt 16 and being lifted. As a result, the original 18 at the time of reading can be flattened, the distance between the original 18 and the SELFOC lens 24 can be kept constant, and the image on the entire surface of the original 18 can be kept at the same focus position by the image sensor 25. The image can be read with less focus blur.

  In the embodiment shown in FIG. 2, the plurality of motor fans 31 and 32 are provided. However, in the embodiments of FIGS. 3 to 5, a plurality of motor fans may be provided.

  Furthermore, if another roller is disposed below the belt 16 so as to face the reading unit 20, the belt 16 can be prevented from being pushed downward by wind pressure, and the document 18 can be more closely attached to the belt 16.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

FIG. 3 is a schematic diagram illustrating a document conveyance path of the image reading apparatus according to the embodiment of the present invention. 1 is a diagram illustrating an image reading apparatus according to an embodiment of the present invention. It is a figure which shows the image reading apparatus in other embodiment of this invention. It is a figure which shows the image reading apparatus in other embodiment of this invention. It is a figure which shows the image reading apparatus of further another embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Document tray, 2 Feed roller, 3 and 4 roller, 5a, 5b, 6a, 6b, 7a, 7b Transport roller, 8 Discharge tray, 16 Transport belt, 18 Document, 20 Reading part, 21 Glass, 22, 23 Lamp , 24 Selfoc lens, 25 Image sensor, 31, 32 Motor fan, 40, 41 Duct, 42 Substrate.

Claims (5)

An image reading apparatus for reading an image of a document,
A transport belt for placing and transporting the document;
Reading means for reading an image of a document placed on the conveyor belt;
An image reading apparatus, comprising: a wind pressure unit disposed in the vicinity of the reading unit and causing the document to be in close contact with the conveying unit by wind pressure. A duct surrounding the reading means;
The image reading apparatus according to claim 1, wherein the wind pressure unit sends wind into the duct to closely contact the periphery of the reading unit of the document with the conveying unit.   The image reading apparatus according to claim 2, wherein a substrate that generates heat is disposed in the duct, and the substrate is cooled by wind from the wind pressure unit. The transport means is a transport belt formed with a plurality of holes,
The image reading apparatus according to claim 1, wherein the wind pressure unit sucks the document through a plurality of holes of the conveyance belt.   The image reading apparatus according to claim 1, wherein the wind pressure applying unit is a motor fan and is provided in a plurality.

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