JP2007312160A - Image reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader and an image forming apparatus stably conveying sheet originals with different thickness and reading an image with excellent quality. <P>SOLUTION: The image reader provided with an interlocking arm 1 which varies pressure force of a white spring 2 in association with a separation pad 9 includes: a pickup roller 6 which conveys the sheet originals; the separation pad 9 which is arranged opposite to the pickup roller 6 and gives frictional force to the sheet original conveyed by the pickup roller 6; a separation spring 8 which pressurizes the separation pad 9 to the pickup roller 6; a sensor 5 which reads images of the conveyed sheet originals; a white board 7 which is arranged opposite to the sensor 5, pressurizes and adheres the sheet originals to the sensor 5 and the white board spring 2 which pressurizes the white board 7 to the sensor 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and an image forming apparatus such as a copying machine, a printer, and a facsimile machine including the image reading apparatus.

  2. Description of the Related Art Conventionally, there are image forming apparatuses in which an image reading unit and an image forming unit are integrally configured and have a plurality of functions such as a copy function, a scanner function, a printer function, and a facsimile function. Hereinafter, such an image forming apparatus will be described.

  FIG. 7 is a cross-sectional view of an image forming apparatus provided with a conventional image reading apparatus. 8 and 9 are detailed views of the sheet document conveying unit of the conventional image reading apparatus.

  As shown in FIG. 7, the recording sheets S as sheet-like recording media stacked on the feeding tray 11 are fed one by one by the feeding roller 12. The fed recording sheet S passes through the transport path X and is transported to the transport roller 14.

  On the other hand, a toner image is formed on the photosensitive drum 16 which is an image carrier, and this toner image reaches the position of the transfer nip portion where the photosensitive drum 16 and the transfer roller 15 come into contact. At this timing, the recording sheet S is conveyed to the transfer nip portion, and the toner image on the photosensitive drum 16 is transferred to the recording sheet S.

  The recording sheet S to which the toner image has been transferred is separated from the photosensitive drum 16 and conveyed to the fixing device 17. The recording sheet S conveyed to the fixing device 17 is nipped between the heating member and the pressure roller to fix the toner image. The recording sheet S on which the toner image is fixed passes through the conveyance path Y and is discharged to the recording sheet discharge portion 19 of the image forming apparatus main body 20 by the discharge roller pair 18.

  An image reading device 30 is disposed on the upper part of the image forming apparatus main body 20. The image reading device 30 has a configuration in which a document placement tray 31 and a document discharge tray 32 are provided on the upstream and downstream of the contact image sensor 5 serving as a reading unit.

  As shown in FIGS. 8 and 9, the sheet document P is set on the document placing tray 31 with the document surface facing downward. Here, in order to separate and feed the sheet document P one by one, the separation pad 9 presses the sheet document P against the pickup roller 6 by the separation spring 8. Then, according to the thickness of the sheet original P, the contact surface between the pickup roller 6 and the separation pad 9 is separated by ΔT by the switching operation of the pressure switching lever 3 (see Patent Document 1). Note that the separation distance ΔT is variable according to the thickness of the sheet document P.

  The lowermost sheet document P is separated and fed by a pickup roller 6 which is a sheet document conveying unit. Other than the lowermost sheet document P, the document is placed on the document placement tray 31 by the separation pad 9 that is a friction means.

  When the sheet original P is separated and fed to the sensor 5, the white background plate 7 is lifted from the sensor 5 by the thickness Δt of the sheet original P. As a result, the spring length of the white background spring 2 is reduced to T−Δt, and the white background plate 7 presses the sheet document P against the sensor 5 and is brought into close contact with the elastic force of the white background spring 2. The spring length of the white background spring 2 before the sheet original P enters between the sensor 5 and the white background plate 7 is T.

  In this state, the sheet original P is photoelectrically read from the image on the original by the sensor 5. The read sheet document P is discharged to the document discharge tray 32 of the image reading device 30 while the document surface faces downward.

Japanese Patent Laid-Open No. 2004-026470

  In the conventional image reading apparatus and image forming apparatus, the sheet original to be read includes sheet originals having various thicknesses from thin paper to thick paper. When reading, the sensor 5 and the sheet original P need to be in close contact with each other. .

  When a white background spring having a strong spring pressure is used to bring the sensor 5 and the sheet document P into close contact with each other, when the thin paper is conveyed and read, the sheet document is placed between the pressing surface disposed facing the sensor 5. P may not be able to penetrate. In such a case, there is a problem that a conveyance failure occurs.

  In order to improve the transportability of thin paper, when a white spring having a weak spring pressure is used, when the thick paper is transported and read, the pressure on the pressing surface disposed facing the sensor 5 becomes weak, and the sensor 5 cannot sufficiently adhere the sheet document.

  In order to cope with the change in the thickness of the document, it is conceivable to switch the pressing force of the white background plate 7 against the sensor 5 with, for example, a pressure switching lever. However, if one of the press switching operations for switching the pressing force by the separation pad 9 and the white background plate 7 is forgotten, a conveyance failure or a reading failure occurs.

  An object of the present invention is to provide an image reading apparatus and an image forming apparatus capable of stably conveying sheet originals having different thicknesses and performing high-quality image reading.

  In order to solve the above problems, a typical configuration of an image reading apparatus and an image forming apparatus according to the present invention includes a sheet document conveying unit that conveys a sheet document, and a sheet document conveying unit that is disposed to face the sheet document conveying unit. Friction means for applying a frictional force to the sheet original conveyed by the original conveyance means, first pressing means for pressing the friction means against the sheet original conveyance means, and image reading for reading an image of the conveyed sheet original Means, a sheet original pressing member that is disposed opposite to the image reading means and presses the sheet original against the image reading means, and a second pressing means that presses the sheet original pressing member against the image reading means An interlocking member that fluctuates the pressing force of the second pressing means in conjunction with the friction means. And butterflies.

  According to the present invention, it is possible to perform stable conveyance of sheet originals having different thicknesses and high-quality image reading.

[First embodiment]
A first embodiment of an image reading apparatus and an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an image forming apparatus including an image reading apparatus according to the present embodiment. 2 and 3 are detailed views of the image reading unit according to the present embodiment.

(Image forming device)
As shown in FIG. 1, the image forming apparatus includes an image forming apparatus main body 20 and an image reading apparatus 30. The image forming apparatus main body 20 includes a feed tray 11, a feed roller 12, a transport roller 14, a transfer roller 15, a photosensitive drum 16, a fixing device 17, a discharge roller pair 18, and a recording sheet discharge unit 19. The transfer roller 15 and the photosensitive drum 16 constitute an image forming unit that forms an image on a recording sheet.

  The recording sheets S as sheet-like recording media stacked on the feeding tray 11 are fed one by one by the feeding roller 12. The fed recording sheet S passes through the transport path X and is transported to the transport roller 14.

  On the other hand, a toner image based on image information read by the image reading device 30 is formed on the photosensitive drum 16 that is an image carrier. This toner image reaches the position of the transfer nip where the photosensitive drum 16 and the transfer roller 15 come into contact. At this timing, the recording sheet S is conveyed to the transfer nip portion, and the toner image on the photosensitive drum 16 is transferred to the recording sheet S.

  The recording sheet S to which the toner image has been transferred is separated from the photosensitive drum 16 and conveyed to the fixing device 17. The recording sheet S conveyed to the fixing device 17 is nipped between the heating member and the pressure roller to fix the toner image. The recording sheet S on which the toner image is fixed passes through the conveyance path Y and is discharged to the recording sheet discharge portion 19 of the image forming apparatus main body 20 by the discharge roller pair 18.

(Image reading device)
An image reading device 30 is disposed on the upper part of the image forming apparatus main body 20. As shown in FIGS. 1 to 3, the image reading apparatus 30 includes an interlocking arm 1, a white background spring 2, a separation unit 4, a contact image sensor 5, a pickup roller 6, and a white background plate 7. The separation unit 4 has a separation spring 8 and a separation pad 9. Further, the image reading device 30 has a document placing tray 31 and a document discharge tray 32 on the upstream and downstream sides of the contact image sensor 5 as a reading unit. In addition, the image reading device 30 is provided on the downstream side of the contact image sensor 5 and the document conveying roller pair H provided between the separation unit 4 and the contact image sensor 5, and discharges the document to the document discharge tray 32. A document discharge roller pair D is provided.

  2 and 3 are diagrams for explaining a configuration related to the interlocking between the separation unit 4 and the white background plate 7. The interlocking arm 1 is an interlocking member that varies the pressing force of the white background spring 2 in conjunction with the separation pad 9. The interlocking arm 1 has a pivotable arm 1b, is a pivoting member that rotates by rotating one end of the arm 1b in conjunction with the separation pad 9, and compresses the white spring 2 at the other end of the arm 1b. is there.

  The interlocking arm 1 has a pivot shaft 1a at the center and an arm 1b that can pivot about the pivot shaft 1a. The rotating shaft 1 a is disposed between the separation pad 9 and the white background plate 7. The arm 1b has one end in contact with the separation unit 4 and the other end in contact with the white spring 2. With the pivot shaft 1a as the center, the arm length on one end side (arm length) of the arm 1b: the arm length on the other end side (arm length) is 1: 1.

  The white background spring 2 is a second pressing means (elastic spring) that presses the white background plate 7 against the sensor 5. As the white background spring 2, a spring having a strong spring pressure is used in order to bring the sensor 5 and the sheet original P into close contact with each other. The sensor 5 is an image reading unit that reads an image of the conveyed sheet original P. The pickup roller 6 is a sheet document conveying unit (rotating body) that conveys the sheet document P. The white background plate 7 is a sheet document pressing member that is disposed to face the sensor 5 and presses and closely contacts the sheet document P against the sensor 5. A white background sheet is attached to the pressing surface of the white background plate 7 facing the reading surface of the sensor 5 by double-sided tape or adhesion.

  The separation spring 8 is a first pressing means (elastic spring) that presses the separation pad 9 against the pickup roller 6. The separation pad 9 is a friction unit that is disposed to face the pickup roller 6 and applies a frictional force to the sheet document P conveyed by the pickup roller 6. The separation pad 9 is formed of a rubber member.

  The sheet original P is set on the original placement tray 31 with the original surface facing downward. In order to separate and feed the sheet original P one by one, the separation pad 9 presses the sheet original P against the pickup roller 6 by the separation spring 8.

  When the sheet document P is separated and fed, the separation pad 9 is separated from the pickup roller 6 by the thickness Δt of the sheet document P. In conjunction with this operation, one end of the arm 1b is lifted, the interlocking arm 1 rotates about the rotation shaft 1a, and the other end of the arm 1b descends to compress the white spring 2. Since the arm 1b is configured with an arm length of 1: 1, the spring length of the white background spring 2 becomes T-Δt (compression Δt by the T-linked arm 1), and the pressing force to the white background plate 7 increases. .

  As the sheet original P is thicker, the separation pad 9 is moved away from the pickup roller 6 and the upper end of the white background spring 2 is moved by the interlocking arm 1 so that the pressing force of the white background spring 2 is increased. That is, the pressing force of the white spring 2 is maximized at the position where the separation pad 9 is farthest from the pickup roller 6.

  When the feeding of the sheet document P is started, the lowermost sheet document P is separated and fed by the pickup roller 6. Other than the lowermost sheet document P, the document is placed on the document placement tray 31 by the separation pad 9 that is a friction means.

  The sheet original P separated and fed by the pickup roller 6 and the separation pad 9 is conveyed to the contact image sensor 5 by the original conveying roller pair H. When the sheet document P is separated and fed to the sensor 5, the white background spring 2 further shrinks by the thickness Δt of the sheet document P, and the spring length becomes T-2Δt. Due to the elastic force of the white background spring 2, the white background plate 7 presses and contacts the sheet original P against the sensor 5.

  In this state, the sheet original P is photoelectrically read from the image on the original by the sensor 5. The read sheet document P is discharged to the document discharge tray 32 of the image reading device 30 with the document discharge roller pair D with the document surface facing downward.

  According to the present embodiment, the pressing force of the white background plate 7 increases in proportion to the thickness of the sheet document P. For this reason, even when the white background spring 2 having a strong spring pressure is used, when the thin paper (thin sheet original P) is conveyed and read, the pressing force of the white background spring 2 conveys the thick paper (thick sheet original P). It becomes weaker than the case. The thin paper can enter between the pressing surface disposed opposite to the sensor 5 against the pressing force.

  On the other hand, when carrying thick paper and performing reading, the pressing force of the white background spring 2 becomes stronger than when carrying thin paper. The pressing force of the pressing surface disposed facing the sensor 5 becomes strong, and the sheet original P can be sufficiently adhered to the sensor 5.

  In this way, it is possible to always stably convey sheet documents having different thicknesses and perform high-quality image reading without performing a pressure switching operation.

  Note that by changing the ratio of the arm length from the rotation center of the interlocking arm 1 to 1: 2, 1: 4, etc., the amount of change in the spring length of the white spring 2 can be changed to T-3Δt, T-5Δt, or the like. Is possible. By changing the combination of the ratio of the arm length of the interlocking arm 1 and the spring pressure of the white background spring 2, sheet originals having different thicknesses can be conveyed more stably, and image reading with higher quality can be performed. be able to.

[Second Embodiment]
Next, a second embodiment of the image reading apparatus and the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view of an image forming apparatus including the image reading apparatus according to the present embodiment. 5 and 6 are detailed views of the image reading unit according to the present embodiment. About the part which overlaps with said 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIGS. 4 to 6, the image reading apparatus and the image forming apparatus of the present embodiment are obtained by adding a press switching lever 3 to the image reading apparatus and the image forming apparatus of the first embodiment.

  The pressure switching lever 3 is a separating unit that separates the separation pad 9 from the pickup roller 6. By the switching operation, the pressure switching lever 3 separates the separation pad 9 from the pickup roller 6 according to the thickness of the sheet original P, and separates the contact surface between the pickup roller 6 and the separation pad 9 by ΔT.

  The interlocking arm 1 operates in conjunction with the switching operation of the press switching lever 3, and the spring length of the white background spring 2 is T−2Δt−ΔT, and the pressing force to the white background plate 7 does not use the press switching lever 3. It becomes stronger than (first embodiment above).

  When transporting thick paper, the pressure switching lever 3 is operated to separate the separation pad 9 by ΔT. In conjunction with this operation, the interlock arm 1 rotates to compress the white spring 2 by ΔT. Thereby, the pressing force of the white base plate 7 to the sensor 5 becomes strong, and the thick paper can be sufficiently adhered to the sensor 5.

  On the other hand, when the thin paper is conveyed, the pressing switch lever 3 is not operated, the pressing force to the white background plate 7 is reduced, and poor conveyance of the thin paper can be suppressed.

1 is a cross-sectional view of an image forming apparatus including an image reading apparatus according to a first embodiment. FIG. 2 is a detailed view of an image reading unit according to the first embodiment. FIG. 2 is a detailed view of an image reading unit according to the first embodiment. It is sectional drawing of the image forming apparatus provided with the image reading apparatus which concerns on 2nd embodiment. It is a detail drawing of the image reading part which concerns on 2nd embodiment. It is a detail drawing of the image reading part which concerns on 2nd embodiment. It is sectional drawing of the image forming apparatus provided with the conventional image reading apparatus. FIG. 10 is a detailed view of a sheet document conveying unit of a conventional image reading apparatus. FIG. 10 is a detailed view of a sheet document conveying unit of a conventional image reading apparatus.

Explanation of symbols

P ... sheet document, S ... recording sheet, X, Y ... conveying path, 1 ... interlocking arm (interlocking member), 1a ... rotating shaft, 1b ... arm, 2 ... white spring (second pressing means), 3 ... Press switching lever, 4... Separation unit, 5... Contact image sensor (image reading means), 6... Pickup roller (sheet document conveying means), 7 .. White plate (sheet document pressing member), 8. (Pressing means), 9 ... Separation pad (friction means), 11 ... Feeding tray, 12 ... Feeding roller, 14 ... Conveying roller, 15 ... Transfer roller, 16 ... Photosensitive drum, 17 ... Fixing device, 18 ... Discharge roller pair , 19 ... recording sheet discharge unit, 20 ... image forming apparatus main body, 30 ... image reading apparatus, 31 ... document placement tray, 32 ... document discharge tray

Claims (10)

A sheet document conveying unit configured to convey a sheet document; a friction unit disposed opposite to the sheet document conveying unit and imparting a frictional force to the sheet document conveyed by the sheet document conveying unit; and the friction unit configured as the sheet document A first pressing unit that presses against the conveying unit; an image reading unit that reads an image of the conveyed sheet document; and a sheet that is disposed opposite to the image reading unit and presses the sheet document against the image reading unit. In an image reading apparatus comprising: an original pressing member; and a second pressing unit that presses the sheet original pressing member against the image reading unit.
An image reading apparatus comprising an interlocking member that varies the pressing force of the second pressing means in conjunction with the friction means. The second pressing means is an elastic spring,
The interlocking member is a rotating member having a rotatable arm, one end of the arm is lifted and rotated in conjunction with the friction means, and the elastic spring is compressed at the other end of the arm. The image reading apparatus according to claim 1. 3. The image reading apparatus according to claim 1, further comprising a separating unit that separates the friction unit from the sheet original conveying unit. The image reading apparatus according to claim 1, wherein the sheet document conveying unit includes a rotating body. The image reading apparatus according to claim 1, wherein the first pressing unit includes an elastic spring. The image reading apparatus according to claim 1, wherein the friction unit is made of a rubber member. The image reading apparatus according to claim 1, wherein the document pressing member is formed by attaching a white background sheet to a pressing surface facing the reading surface of the image reading unit. . The image reading apparatus according to claim 1, wherein the white background sheet is attached by double-sided tape or adhesion. 2. The second pressing unit is interlocked by the interlocking member so that the pressing force of the second pressing unit increases as the friction unit moves away from the sheet document conveying unit. Item 9. The image reading apparatus according to any one of Items 8 to 9. An image reading apparatus according to any one of claims 1 to 9,
An image forming apparatus comprising: an image forming unit that forms an image on a recording sheet based on image information read by the image reading apparatus.

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