JP4753747B2 - Document holding means of image reading apparatus - Google Patents

Description

  The present invention relates to a document pressing unit of an image reading apparatus used in a copying machine, an image scanner, or the like.

  In various image forming apparatuses and the like, image reading apparatuses for reading the contents of documents are widely used. In a general image reading apparatus, for example, as shown in FIG. 9, the document pressing plate 2a of the document pressing means 2 is attached to the apparatus main body 1 so as to be openable and closable so as to be lifted in a cantilevered manner. The entire document pressing means 2 is opened by lifting one side edge of the document pressure plate 2a.

  A document P to be read is placed on the upper surface side of the contact glass (document placing glass) 3 exposed when the document pressure plate 2a of the document pressing means 2 is opened. The document pressure plate 2a of the document pressing means 2 is closed again so as to cover the document. A pressure contact sheet member 2b is adhered to the inner surface side (rear surface side) of the original pressure plate 2a, and the original pressure P is placed on the contact glass 3 by the pressure contact sheet member 2b coming into contact with the original P from above. It comes to be in close contact.

  As shown in FIG. 10, the document P set in this way is irradiated linearly by a light source 4 such as a lamp disposed in the lower region of the contact glass 3 described above, and the reflected light is mirrored. An image is formed on the photoelectric conversion element 7 via 5 and the lens 6. The light source 4, mirror 5, lens 6 and photoelectric conversion element 7 are integrated into a unit, and the unit portion is moved relative to the original P to read an image.

  Here, the document pressing plate 2a constituting the document pressing means 2 is generally a structure made of a hard resin material or the like, but is a pressure contact sheet member adhered to the document pressing plate 2a. As the sheet 2b, a sheet-like resin material or the like is used, and the sheet 2b is bonded to the document pressure plate 2a through an elastic member 2c made of a foamed material such as sponge. The original pressure plate 2a, the elastic member 2c, and the pressure contact sheet member 2b are bonded to each other via a double-sided adhesive tape or the like. After the pressure contact sheet member 2b is first bonded to one side of the elastic member 2c, the pressure plate The elastic member 2c integrated with the sheet member 2b is attached to the inner surface side (rear surface side) of the document pressure plate 2a to form the document pressing means 2.

JP 2001-92044 A

  However, in the document pressing means 2 having such a configuration, the press-contact sheet member 2b is disposed on the contact glass 3 particularly when the document P is not placed on the contact glass 3 or when the document P is extremely small. If the document pressing means 2 is to be opened quickly because it is in close contact with the gap, the pressure contact sheet member 2b is attracted to the contact glass 3 like a suction cup, and the operability of the entire document pressing means 2 may be deteriorated. is there. When the suctioned document pressing means 2 is forcibly opened, there may be a problem that the double-sided adhesive tape fixing the pressure contact sheet member 2b or the elastic member 2c is peeled off.

  Therefore, conventionally, in order to suppress the adsorption phenomenon at the time of the opening operation as described above, for example, as shown in FIG. 11 or FIG. What has arrange | positioned the adhesive double-sided tape as S1 is known. With such a configuration, the document pressing plate 2a of the document pressing unit 2 is gradually lifted from the adhesion areas S1 and S1 where the adhesive double-sided tape is disposed, and the entire document pressing unit 2 is bent in a U shape. It will lift up smoothly.

  However, in the document pressing means 2 having such a structure, there is a tendency that the area of the adhesive regions S1 and S1 where the adhesive double-sided tape is disposed, that is, the adhesive area of the pressure contact sheet member 2b and the elastic member 2c is insufficient. 2b and the elastic member 2c are easily peeled off, and the press-contact sheet member 2b and the elastic member 2c may hang down to deteriorate the appearance quality.

  On the other hand, as shown in FIG. 13, it is conceivable to fix the entire area of the pressure contact sheet member 2b and the elastic member 2c as the adhesion region S2. In this case, for example, FIG. 14 and FIG. It is necessary to form an air vent passage 9 between the projection glass 8 and the contact glass 3 by providing a protrusion 8 as shown in FIG. However, when such an air vent passage 9 is formed, the pressing force against the document on the contact glass 3 is reduced. For example, when a curl or a wrinkle exists on the document, it is shown in FIG. As described above, a gap corresponding to the height of the protrusion 8 described above, that is, a floating phenomenon is likely to occur, and there is a possibility that the document P cannot be brought into close contact with the upper surface of the contact glass 3.

  If a floating phenomenon occurs in the original P, it may cause image deterioration such as a blurred image of the read image or density unevenness due to a change in the reflection angle of the original. In particular, when a contact type image sensor is used, such reading is performed. This problem will appear remarkably.

  Therefore, the present invention has been made in view of the above problems, and can prevent the pressure-contact sheet member from peeling off, and can always keep the entire surface of the document in close contact with the document placement surface, thereby obtaining an optimal read image. An object of the present invention is to provide a document pressing means of an image reading apparatus which can be used.

  In order to achieve the above object, in the document pressing means of the image reading apparatus according to the present invention, one side edge portion is rotatably attached to the apparatus body, and an open side edge portion facing the rotation side edge portion is provided. A document pressure plate that is lifted and rotated, and a pressure contact sheet that is attached to the inner surface side of the document pressure plate and that contacts and presses the document placed on the document placement surface when the document pressure plate is closed. In the document pressing means of the image reading apparatus provided with a member, the adhesion region where the pressure contact sheet member is adhered to the document pressure plate extends so as to form a substantially U-shaped plane with the open side edge as one side. It is formed so as to have a shape that is open toward the rotating side edge.

  According to the present invention having such a configuration, the pressure contact sheet member is fixed relatively firmly via the relatively wide area of the adhesive region having a substantially U-shape on the outer periphery side of the original pressure plate. Further, when the document pressing means is lifted to be opened, the portion fixed in the substantially U-shaped bonding area on the outer periphery side of the pressure contact sheet member is first lifted, and the document pressing means is rotated. A sudden lifting force does not work in the region from the fulcrum side to the central region. Then, the pressure contact sheet member is sequentially peeled off from the document placing surface from the outer peripheral area having a substantially U-shape in the plane toward the central area, and air enters smoothly there. Even if no projection is provided, the entire document pressing means can be lifted well.

  As described above, the document pressing means of the image reading apparatus according to the present invention has a pressure contact sheet in a substantially U-shaped adhesive region that is open to the rotating side edge with the open side edge of the document pressure plate as one side. By adhering the members, the pressure contact sheet member is firmly fixed in the outer peripheral area of a relatively large area, and when the document pressing means is opened, the pressure contact sheet member has the above-described substantially plane U-shape. Since the structure is such that air is introduced by sequentially peeling from the outer peripheral side adhesion area toward the center area, and the entire document pressing means is smoothly lifted, so that the pressure contact sheet member member is firmly While fixing, the entire surface of the document can always be brought into close contact with the document placement surface, and an optimum image reading state can be stably obtained over a long period of time.

  Hereinafter, an embodiment in which the present invention is applied to an image reading apparatus of a composite copying machine will be described in detail with reference to the drawings. First, as shown in FIGS. The overall structure of the composite copying machine will be described.

  In FIG. 1, a scanner unit 11 as an image reading device that reads a document is disposed at the upper end position of the apparatus body 10. The configuration of the scanner unit 11 is basically the same as the conventional configuration described above, but the structure of the document pressing means provided in the scanner unit 11 is a main part of the present invention and will be described in detail later. .

  The multi-manual feed unit 12 disposed on the front side of the apparatus main body 10 is configured to be able to set a sheet-like recording medium such as paper by being tilted so as to be opened as necessary. Further, reference numeral 13 in FIG. 1 denotes a copy operation panel device, which is configured to perform various operations necessary for the printing operation, and is arranged so as to be adjacent to the copy operation panel device 13. A device 14 is arranged.

  The paper feed cassette 15 is detachably disposed on the lower side of the apparatus main body 10, and is configured to be able to set recording media such as paper in the same manner as the manual feed unit 12 described above. A toner image is formed on the recording medium sent out from the paper feed cassette 15 or the manual feed unit 12 based on a known electrophotographic technique, heat-fixed, and printed out.

  That is, as shown in FIG. 2 in particular, the photosensitive drum 20 as an image carrier that is rotatably supported in the process unit PU is rotationally driven in the direction of arrow A by the main motor 21 at an appropriate process speed. Around the photosensitive drum 20, a charging roller 22 as a charging device for uniformly charging the surface of the photosensitive drum 20 along the rotational direction, and an electrostatic latent image are formed. A laser scanner 23 serving as an exposure unit, a developing device 24 for developing and developing the electrostatic latent image, and a transfer device for transferring the toner image on the photosensitive drum 20 to the recording medium side. A transfer roller 25 and the like are sequentially arranged.

  Further, the conveyance guide 26 extending substantially horizontally from the process unit PU is connected to a fixing device 27 that heats and pressurizes the recording medium to which the toner image is transferred. Further, although not shown, a control board containing a CPU and the like for controlling various image forming operations is disposed on the back side of the apparatus main body 10.

  When the outer peripheral surface of the photosensitive drum 20 that is rotationally driven in the direction of arrow A by the main motor 21 described above is uniformly charged to a predetermined polarity and potential by the charging roller 22, the charged photosensitive drum 20 is charged. An image exposure based on the image information is performed on the outer peripheral surface of the laser beam by the laser scanner 23 serving as an exposure unit, and the charge in the exposed portion is removed to form an electrostatic latent image. The electrostatic latent image on the photosensitive drum 20 is visualized by toner attached based on a predetermined developing bias applied to a developing sleeve 24b provided in the developing device 24, and a toner image is formed. Is called.

  On the other hand, a sheet-like recording medium P made of paper or the like is conveyed from, for example, the sheet feeding cassette 15 by a sheet feeding roller or a conveying roller (not shown), and a transfer nip portion between the photosensitive drum 20 and the transfer roller 25. The toner image is transferred to the recording medium side. The recording medium P carrying the unfixed toner image on the surface by transfer is transported to the fixing device 27 along the transport guide 26, where the unfixed toner image is heated and pressurized to melt the toner, thereby recording. A toner image is fixed on the surface of the medium. By repeating the above operation, image formation is executed one after another.

  As described above, the scanner unit 11 as an image reading apparatus is disposed on the upper side of the apparatus main body 10 of the copying machine having such a configuration. The basic structure of the scanner unit 11 is the same as that shown in FIGS. 10 and 11 described as the prior art, and in the first embodiment of the invention shown in FIGS. 3 and 4. Also in the document pressing means 30, the document pressure plate 31 is formed from a relatively hard resin material, and a rotation support shaft 32 provided at the edge on the back side (left end side in the drawing) of the document pressure plate 31. , And is rotatably fitted in a bearing portion 10a provided on the apparatus main body 10 side. As a result, the entire document pressing means 30 can be rotated so as to be cantilevered with respect to the apparatus main body 10, and is gripped by one side edge portion of the document pressure plate 31 on the front side (right end side in the drawing). Then, the whole document pressing means 30 is opened by being lifted in the left rotation direction in the figure.

  The document pressure plate 31 has a structure in which a plurality of lattice ribs 31a are arranged in an intersecting manner. The inner surface side (back surface side) of the document pressure plate 31 formed by the lattice ribs 31a is contact glass ( The original glass 3 is configured to extend so as to be substantially parallel to the upper surface of the original glass 3, and a pressure contact sheet member 33 is attached to the inner surface side (rear surface side) of the original pressure plate 31. In particular, as shown in FIG. 5, the pressure contact sheet member 33 is composed of a resin sheet material 33a having sufficient flatness and rigidity and an elastic member 33b such as maltoprene bonded to a double-sided adhesive tape material or the like. The elastic members 33b constituting the pressure contact sheet member 33 are fixed to each other by an agent, and both surfaces having a width of 15 to 25 mm with respect to the inner surface side (rear surface side) of the document pressure plate 31 described above. It is stuck using adhesives, such as sticking tape material.

  Here, the adhesion region of the pressure contact sheet member 33 to the original pressure plate 31 described above is formed by continuous ribs so as to form a substantially U-shaped plane as shown by a hatching region T1 in FIG. ing. The adhesion region T1 of the pressure contact sheet member 33 is a planar region that extends from the both ends of the original pressure plate 31 so as to bend at a substantially right angle with the open side edge (right edge side in FIG. 3) as one side. And has a shape that is open toward the edge of the rotation support shaft 32 (the left end side edge in FIG. 3).

  When the image of the document P placed on the contact glass 3 is read using the document pressing unit 30 as described above, curl or wrinkle as shown in FIG. However, by closing the document pressure plate 31 of the document pressing means 30, the pressure contact sheet member 33 adhered to the document pressure plate 31 brings the document P into close contact with the contact glass 3 as described above.

  At this time, the central area of the original pressure plate 31 tends to escape in the direction away from the contact glass 3 due to the reaction force from the original P, so that the pressing force against the original P is slightly reduced, but the conventional protrusion is not Since it is not provided, the entire area of the document P is pressed against the contact glass 3 without a gap. Therefore, the curled portion or the wrinkled portion of the document P can be obtained with a pressing force sufficient to bring it into close contact with the contact glass 3, and an optimum image can be read.

  Further, the pressure contact sheet member 33 is relatively firmly fixed to the original pressure plate 31 in the adhesion region T1 on the outer peripheral side having a relatively wide area having a substantially U-shaped plane, and the pressure contact sheet member 33 is peeled off. Looseness is prevented well.

  On the other hand, the above-mentioned pressure contact sheet member 33 is fixed through a substantially U-shaped bonding region T1 in a plane and is not fixed from the rotation support shaft 32 side to the central region. When lifted so as to be opened, the outer peripheral side of the pressure-contact sheet member 33, that is, the portion fixed in the bonding area T1 having a substantially U-shape in the plane is first lifted, and the rotation support of the document pressing means 30 is performed. A sudden lifting force does not work in the region from the shaft 32 side to the central region. Then, the pressure contact sheet member 33 is sequentially peeled from the surface of the contact glass 3 like a region T1 ′ represented by the lattice pattern in FIG. 6 from the outer peripheral region having a substantially U-shape in a plane toward the central region. Air will smoothly enter the peeled area. As a result, the entire document pressing means 30 is lifted satisfactorily without providing a conventional protrusion.

  Further, in the second embodiment according to FIG. 7 in which the same reference numerals are assigned to the same components as those in the first embodiment described above, the inner surface side (rear surface side) of the document pressing plate 31 of the document pressing means 30, that is, the pressure contact sheet. The sticking surface of the member 33 is formed so as to form a substantially flat surface.

  Then, the adhesion region T2 of the pressure contact sheet member 33 to the substantially flat sticking surface of the original pressure plate 31 is on one side of the open side (right side in the drawing) of the original pressure plate 31 on both sides. It is formed from a planar area extending in a substantially U-shaped plane, and the open side of the approximately U-shaped plane in the bonding area T2 of the press-contacting sheet member 33 is the back side of the original pressure plate 31 (see FIG. 7). It is composed of an outer peripheral side continuous surface directed to the rotation support shaft 32 side on the left end side. In such a second embodiment, substantially the same operations and effects as in the first embodiment described above can be obtained.

  In this case, the flat surface region that has a unique sticking surface in the original pressure plate 31 may be a flat surface on the entire inner surface of the pressure plate, or only a substantially U-shaped region may be a flat surface. It may be. Moreover, the area | region should just be about 20 mm which is the width of a double-sided tape at least.

  Next, in the document pressing means 40 according to the third embodiment 3 of the present invention shown in FIG. 8, the adhesion region T3 of the pressure contact sheet member 42 is formed from a plurality of dot-like regions (partial regions). In addition, the plurality of dotted adhesion regions T3 are distributed and arranged so as to follow a plane substantially U-shape similar to each of the above-described embodiments. In the third embodiment as described above, substantially the same operations and effects as those of the above-described embodiments can be obtained. In the embodiment according to FIG. 8 as well, it is also possible to form the application surface of the pressure contact sheet member 42 on the original pressure plate 41 in a flat surface.

  As mentioned above, although the embodiment of the invention made by the present inventor has been specifically described, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention. Nor.

  For example, each of the embodiments described above applies the present invention to an image reading apparatus in a composite copying machine, but the present invention is not limited thereto, and is similarly applied to other image forming apparatuses. Is possible.

  As described above, the present invention can be widely applied to a wide variety of image forming apparatuses including a facsimile and a copying machine according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view illustrating an overall structure of a composite copying machine as an example of an image forming apparatus to which the present invention is applied. FIG. 2 is a longitudinal sectional view illustrating an internal structure of the composite copying machine illustrated in FIG. 1. FIG. 3 is an explanatory plan view showing the structure of the document pressing unit used in the image reading apparatus according to the first embodiment of the present invention. FIG. 4 is a cross-sectional explanatory diagram showing the structure of the document pressing unit shown in FIG. 3. FIG. 5 is an exploded perspective view showing the structure of a press-contact sheet member of the document pressing means shown in FIGS. 3 and 4. It is a plane explanatory view showing a state where the pressure contact sheet member is peeled off when the document pressing means is lifted. FIG. 6 is an explanatory plan view showing the structure of a document pressing unit used in an image reading apparatus according to a second embodiment of the present invention. FIG. 10 is an explanatory plan view showing the structure of a document pressing unit used in an image reading apparatus according to a third embodiment of the present invention. 1 is an external perspective view illustrating an overall schematic structure of an image reading apparatus to which the present invention is applied. FIG. 10 is a longitudinal cross-sectional explanatory diagram illustrating a main part of the image reading apparatus illustrated in FIG. 9. It is a plane explanatory view showing an example of the structure of a document pressing means used in a conventional image reading apparatus. It is a plane explanatory view showing another structural example of the document pressing means used in the conventional image reading apparatus. FIG. 10 is a plan view illustrating still another example of the structure of the document pressing unit used in the conventional image reading apparatus. FIG. 15 is a cross-sectional explanatory view showing the structure of the document pressing means of the conventional image reading apparatus shown in FIG. 14. It is transverse cross-sectional explanatory drawing which expanded and represented the X section enclosed by the ellipse shape in FIG. FIG. 6 is a longitudinal cross-sectional explanatory view showing a document pressing unit in a state where curling or wrinkling has occurred in the document.

Explanation of symbols

3 Contact glass (original glass)
DESCRIPTION OF SYMBOLS 10 Apparatus main body 10a Bearing part 11 Scanner unit (image reading apparatus)
30 Document pressing means 31 Document pressure plate 31a Lattice rib 32 Rotating support shaft 33 Pressure contact sheet member 33a Resin sheet material 33b Elastic member T1 Adhesion area P Document T2 Adhesion area 40 Document pressing means 41 Document pressure plate 42 Pressure contact sheet member 43 Reinforcing sticking Part T3 Bonding area

Claims (3)

An original pressure plate that is pivotably attached to one side edge with respect to the apparatus main body, and an open side edge facing the rotation side edge is lifted and rotated;
A pressure contact sheet member that is attached to the inner surface side of the document pressure plate and that contacts and presses the document placed on the document placement surface when the document pressure plate is closed;
In the document pressing means of the image reading apparatus provided with
The adhesive region where the pressure contact sheet member is adhered to the original pressure plate extends so as to form a substantially U-shaped plane with the open side edge as one side, and is open toward the rotating side edge. A document pressing unit of an image reading apparatus, wherein the document pressing unit is formed to have a shape.   2. The document pressing means of an image reading apparatus according to claim 1, wherein the adhesion area is a planar area that is continuous in a substantially U-shape on a plane. 2. The document pressing means of an image reading apparatus according to claim 1, wherein the adhesion area is composed of dot-like areas distributed in a plurality of locations along a substantially U-shape on a plane.

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