JP2008070593A - Document pressing device and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document pressing device for obtaining a satisfactory image by improving the pressing performance of a folded document or curled document onto a platen glass without raising cost and to provide an image forming apparatus provided with the document pressing device. <P>SOLUTION: The document pressing device includes a sheet member disposed in contact with a document, a document pressing plate holding the sheet member, and an elastic member joined between them. In the document pressing device, the document pressing plate is provided with a projection which projects from the elastic member adhesion face of the document pressing plate and elastically deforms the elastic member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a document pressing device that presses a document against a contact glass in an image reading apparatus such as a copying machine or an image scanner, and an image forming apparatus including the document pressing device, and more particularly to prevention of floating of a document and improvement of image clarity.

An image reading device such as a copying machine or an image scanner scans an original placed on a contact glass by an image reading means and optically reads information described on the original. In this image reading apparatus, when the document is lifted from the contact glass, the image reading means is not focused and a clear image cannot be read. Therefore, a document pressing device for pressing the document against the contact glass is used. .
This document pressing device generally has a basic structure, generally a document crimping plate, a sheet member that contacts the document and presses the document against the contact glass, and connects the document crimping plate and the sheet member by bonding, and presses the sheet member against the contact glass. For example, Japanese Patent Application Laid-Open No. 11-202425 and Japanese Patent Application Laid-Open No. 2001-92044 are known as specific structures. ing.

However, in the document pressing device having a conventional configuration shown in Japanese Patent Laid-Open No. 11-202425, even when the document pressing plate itself to which the sheet member is attached is warped, the central portion of the sheet member is not adhered to the document pressing plate. Although the original is pressed against the contact glass by the weight of the sheet member and the elastic member, if the mass becomes light due to the thickness of the sheet member and the elastic member being reduced, the folded original or the curled original is a sheet. The original weight of the member and the elastic member floats without being able to press the original against the contact glass, and a clear image can be obtained especially with a reading device having a shallow depth of field such as a CIS (contact image sensor). There was a case of disappearing.

  In order to solve this problem, as shown in Japanese Patent Laid-Open No. 2001-92044, a magnet is provided on the side opposite to the rotation fulcrum of the original cover, and the elastic member of the original cover is attached by the force of the magnet when the original cover is closed. A configuration has been devised in which a folded or curled document is strongly pressed against a platen glass by pressing an elastic member provided on the surface side.

Alternatively, as disclosed in Japanese Patent Laid-Open No. 2001-22010, there is a configuration in which an elastic member is adhered only to the periphery of the end portion, and a folded document or a curled document is pressed strongly against the platen glass by pressing the document pressing plate from above.
However, in the former method, it is necessary to separately provide an attracting member such as a magnet, so that the cost increase cannot be avoided. In the latter method, it is necessary to hold the original pressing plate with a strong force from above.

JP-A-11-202425 JP 2001-92044 A SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its purpose is to improve the pressing property of a folded original or a curled original to a platen glass without increasing the cost, thereby producing a good image. The present invention provides a document pressing device and an image forming apparatus provided with the document pressing device.

  In order to achieve the above object, a document pressing device according to the present invention and an image forming apparatus including the document pressing device include a sheet member that contacts the document, a document pressing plate that holds the sheet member, and a space between the document pressing plate and the sheet member. A document pressing plate that is rotatable, and protrudes from an elastic member bonding surface of the document pressing plate in a document pressing device that presses the document at a closed position of the document pressing plate, A convex portion for elastically deforming the elastic member is provided on the original cover.

  According to the present invention having such a configuration, the force for pressing the original when the original pressing plate warps upward is not only the self-weight pressing force of the elastic member and the sheet member, but also the elastic member due to the convex portion of the original pressing plate. The document can be pressed with a pressing force applied with a repulsive force.

As described above, in the document pressing device according to the present invention and the image forming apparatus including the same,
By providing the original pressure plate with a convex portion that protrudes from the adhesive surface of the original pressure plate and elastically deforms the elastic member, the force that holds the original when the original pressure plate is warped upward is elastic member and sheet member. The force that presses a curled document or a folded document is configured so that the document can be pressed not only by its own weight pressing force but also by a pressing force that includes the repulsive force of the elastic member due to the convex portion of the document crimping plate. And more stable document pressing performance can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an image reading apparatus. The original 11 placed with the reading surface facing the contact glass 10 is pressed by the elastic member 21 attached to the original pressure plate 20 to press the sheet member 23 against the original 11 and the contact glass 10 so that the original 11 becomes the contact glass. Adhere closely. The document 11 pressed against the contact glass surface is read by document reading information such as a document image by reading means 12 such as a contact image sensor (CIS).
Specifically, as shown in the partial schematic diagram of the image reading unit in FIG. 2, the document 11 is irradiated linearly by a light source 13 such as an LED, and the reflected light of the document is imaged on the photoelectric conversion element 15 through the lens 14. . The light source 13, the lens 14, and the photoelectric conversion element 15 constitute a reading unit 12 as a unit. By driving the motor 17 in FIG. 1, the reading unit 12 is connected to the reading unit 12 via a driving belt 16 fixed to the reading unit 12. A configuration in which driving force is transmitted and the image of the document 11 on the contact glass 10 is optically read by moving (scanning) relative to the document in the direction orthogonal to the longitudinal direction of the photoelectric conversion element 15 along the guide rail 18. It has become.

Next, the configuration of the document pressing device will be specifically described with reference to FIG. The original cover 20 is closed with respect to the reading apparatus main body 1 via the rotation fulcrum 24, and is in a closed position (dashed line in FIG. 3) for pressing the original 11 placed on the surface of the contact glass 10, and an open position (in FIG. 3). (Solid line in FIG. 3). The original cover 20 in this embodiment is formed of ABS resin, and a sponge member such as maltoprene is used as the elastic member 21. The sheet member 23 is a white sheet, and a thin sheet having a thickness of 1.0 mm or less is used.
The elastic member 21 is disposed between the original crimping plate 20 and the sheet member 23, and the respective joints are pasted around the four sides of the elastic member as shown in FIG. The double-sided tape 30 is used, and the elastic member 21 and the sheet member 23 are joined by the double-sided tape 31. As a result, the original pressure plate 20, the elastic member 21, and the central portion of the sheet member 23 are not fixed to the original pressure plate 20, and are flexible with respect to the thickness direction of the elastic member 21.
Here, it is difficult to ensure flatness of a large flat plate such as the original pressing plate 20, and at least it is often warped in a convex or concave direction from a state without warping. As shown in FIG. 5, the document pressing device having the above-described configuration is generally formed so as to warp at least upward (warping in the direction in which the central portion of the document pressing plate 20 is separated from the elastic member 21). However, when an upward warp occurs in the original pressure plate 20 to which the elastic member 21 is attached, the force for pressing the original 11 against the contact glass 10 is only the weight of the elastic member 21 and the sheet member 23. Here, if the document 11 pressed against the contact glass 10 is a curled or folded document, the force for pressing the document 11 against the contact glass 10 is only the weight of the elastic member 21 and the sheet member 23. When the member 21 or the sheet member 23 is light, it may be difficult to press only with its own weight, and the document 11 may be separated from the contact glass 10 as shown in the broken line portion of the Z portion in FIG. In a reading means (not shown) with a short depth of field represented by a contact image sensor, a clear image cannot be obtained if the original 11 is separated from the contact glass 10 even a little.
Therefore, in the embodiment of the present invention, as shown in FIG. 6, a configuration in which the document 11 is prevented from floating from the contact glass 10 even when the document crimping plate 20 is warped and the document 11 to be pressed is curled or folded. Further, the original cover 20 and the elastic member 21 are bonded with the double-sided tape 30 affixed to the aforementioned four sides of the elastic member 21, and the other areas where the original cover 20 and the elastic member 21 are not bonded. Is protruded from the surface to which the elastic member is attached, and the height is the amount of warpage of the original pressure plate 20, that is, the central portion of the elastic member 21 when the original pressure plate 20 is closed with respect to the contact glass 10. And a convex portion d having a projection height equal to or greater than the gap formed between the document pressing plate 20 and the original document pressing plate 20.
With such a configuration, even when the original cover 20 is warped upward and the original to be pressed against the contact glass 10 is curled or folded, it is adhered to the original cover 20 of the elastic member 21. Since the non-exposed portion is always compressed and elastically deformed by the convex portion d provided on the original pressure plate 20, the force for pressing the original is (self-weight) + (elastic member repulsive force at the protrusion d). Therefore, it is possible to improve the pressability of the curled or bent original document 11 to the contact glass 10 and to prevent the original document 11 from floating from the contact glass 10 and to obtain a clearer image.
Further, the number of convex portions provided on the original cover 20 is not limited to one, and by providing at a plurality of locations as shown in FIG. 7, it is possible to similarly improve the document pressing performance at each portion provided with the convex portions. It becomes.
On the other hand, in the state in which the original cover 20 is not warped, the convex portion d shown in FIG. 8 elastically deforms the elastic member 21 a lot. In this case, the elastic force of the elastic member 21 is applied to the original cover 20. Although it is compressed by its own weight, the repulsive force increases, but this repulsive force generates only a repulsive force for pressing the curl or fold of one document against the contact glass 10, which is sufficient compared to the self-weight of the original pressure plate 20. It is small and is always pushed to a position where the elastic member 21 comes into contact with a surface having the same height as the adhesion surface of the original pressure plate 20, and the original pressure plate due to an increase in the repulsive force accompanying an increase in the pushing amount of the elastic member 21 by the convex portion. The sheet member 23 and the elastic member 21 are not separated from the contact glass 10 and the document 11.

  FIG. 9 is an explanatory diagram of the configuration of the image forming apparatus equipped with the image reading device, and FIG. 10 is an explanatory diagram of the configuration of the image reading device including the document conveying device (ADF). The copier C of the present embodiment is an example of an image forming apparatus that includes, for example, an image reading apparatus A that is an image reading unit and an apparatus main body B that is an image forming unit.

  As shown in FIG. 9, the copying machine C of the present embodiment has an image reading device A mounted on the upper part of the apparatus main body B, and an image of the document 11 read by the image reading apparatus A is imaged on a sheet P by the apparatus main body B. Form. The apparatus main body B operates the exposure unit 123 based on the electrical signal and image data of the image to form an electrostatic latent image on the surface of the rotating photosensitive drum 121. The electrostatic latent image is developed (supplied with toner) by the developing device 124 to become a toner image. Thereafter, the sheet P is supplied between the photosensitive drum 121 and the transfer charger 125 at the same timing by the conveying roller 131, and the sheet P contacts the photosensitive drum 121 and passes through the separation charger 126, so that The toner image is transferred from the body drum 121 to the sheet P. The cleaner 127 cleans the surface of the photosensitive drum 121 to which the toner image has been transferred, and the charger 122 charges the surface of the photosensitive drum 121 in preparation for the next exposure. On the other hand, the sheet P to which the toner image has been transferred is conveyed to the fixing device 129 by the conveying unit 128, and the toner image is fixed on the surface of the sheet P by being heated and pressurized by the fixing device 129. Then, the sheet P on which the toner image is fixed is discharged to the discharge tray 130.

  Under the image forming apparatus B, sheet storage portions 119a, 119b, 119c, and 119d loaded with sheets P of various sizes are arranged. The sheets P in the sheet storage portions 119a, 119b, 119c, and 119d are taken out one by one by the feeding rollers 120a, 120b, 120c, and 120d, and are transferred to the conveying roller 131.

  As shown in FIG. 10, the image reading apparatus A has a document conveying device (ADF) 102 mounted on the upper portion of the image reading unit 1, and can read an image of a document by both a flow reading method and a book reading method. The book reading method has an advantage that the degree of freedom of the form of the original is high and a book-like original or a three-dimensional object can be read. On the other hand, the flow reading method has an advantage that a large amount of sheet-like documents can be automatically processed in a short time.

  On the upper surface of the image reading unit 1, a book reading platen glass 103 on which a document of the maximum size can be placed is provided, and a sink for supporting a document surface of a document for flow reading adjacent to the platen glass 103. A reading glass 104 is provided. Below the flow reading glass 104, a reading unit 105 for reading an image on the document surface is arranged. The reading unit 105 moves below the document table glass 103 and scans the document placed on the document table glass 103. Is possible.

  The document conveying device 102 is attached to the upper part of the image reading unit 101 with a hinge or the like, and can be rotated up and down with respect to the image reading unit 101. The document conveying device 102 takes in the documents stacked on the document placing unit 110 one by one with the conveying rollers 111 a, conveys them with the conveying rollers 111 b, 111 c, 111 d, and 111 e, and passes them above the reading unit 105. Then, the document whose image has been read is discharged from the conveying roller 111f to the document discharge unit 113.

  On the other hand, when reading an image by the book reading method, an original is placed on an original table glass 103 arranged in the same manner as the contact glass 10 shown in FIG. 1 with the original conveying device 102 lifted upward. Then, the document feeder 102 is lowered to the original position, and the document is pressed against the document table glass 103. Thereafter, when the start switch is operated, the reading unit 105 moves under the platen glass 103 and scans and reads an image on the document surface.

  A sheet member (not shown) having substantially the same size as that of the document table glass 103 is attached to the bottom surface of the document conveying device 102 in the same manner as the document pressing plate 20 shown in FIG. Similar to the sheet member 23 shown in FIG. 1, the sheet member is attached to an elastic member attached to the bottom surface of the document conveying device 102.

  Therefore, the same effect as that of the document pressing device described with reference to FIGS.

  As described above, the present invention relates to a document pressing device used in an image reading device such as an image scanner, an automatic document feeding / discharging device that automatically conveys a document, an image forming device such as a copying machine, and various other devices. Can be widely applied.

1 is an external view of an image reading apparatus including a document pressing device according to the present invention. It is a partial schematic diagram of an image reading unit. It is explanatory drawing of a document pressing state and an open state. It is explanatory drawing regarding each part assembly | attachment of a document pressing device. It is explanatory drawing of the state which the original leaves | separates from contact glass by the curl of an original. FIG. 6 is an explanatory diagram of a state in which a curled document is pressed by a convex portion of a document crimping plate. It is explanatory drawing of the original document pressing apparatus of another embodiment. It is explanatory drawing of the state which hold | suppressed the original in the state without a curvature in an original crimping plate. It is explanatory drawing of a structure of the image forming apparatus carrying an image reading apparatus. FIG. 3 is an explanatory diagram of a configuration of an image reading apparatus including a document conveying device (ADF).

Explanation of symbols

A, G Image reading device B Device main body (image forming means)
1 Device body 10 Contact glass (transparent member)
11 Document 12 Reading unit (reading means)
20 Document pressure plate (support member)
21 Elastic member 23 Sheet member (contact member)
24 fulcrum (axis of rotation)
d Convex part with different height from the surface where the original cover is attached

Claims (6)

A sheet member that contacts the document; a document crimping plate that holds the sheet member; and an elastic member that is bonded between the document crimping plate and the sheet member. In the document pressing device that presses the document at the closed position of the document crimping plate,
2. A document pressing device according to claim 1, wherein said document pressing plate is provided with a protrusion that protrudes from an elastic member bonding surface of said document pressing plate and elastically deforms said elastic member.
2. The document pressing device according to claim 1, wherein the convex portion of the document pressing plate elastically deforms the elastic member when the document pressing plate is closed.
3. The document pressing device according to claim 1, wherein a region around the convex portion of the document pressing plate is not bonded to the elastic member.
4. The document pressing device according to claim 1, wherein a protruding height of the convex portion of the document crimping plate from a bonding surface is higher than a warp amount of the document crimping plate.
5. The document pressing device according to claim 1, wherein the document pressing plate has a plurality of convex portions.
An image forming apparatus comprising the document pressing device according to claim 1.

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