JPH0743841A - Image reader - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an image reading apparatus capable of preventing the image floating due to the deformation of the pressure plate or the curl of the document and the image defect due to the position shift. To do. A flexible sheet 15 is interposed between the contact glass and the pressure plate in the document pressing mechanism of the image reading apparatus including a pressure plate 4 for pressing the document 2 placed on the contact glass 1 from above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device,
More specifically, the present invention relates to an image reading apparatus capable of preventing deterioration of quality of a formed image caused by warpage of a document or a pressure plate on a contact glass on which a document is set.

[0002]

2. Description of the Related Art FIGS. 3 (a) and 3 (b) are a schematic explanatory view of a conventional image reading apparatus and a sectional view showing the configuration of a document setting portion. Contact glass 1 placed on the top of the case
The original 2 set on the upper side is pressed by the pressure plate 4 onto the contact glass while being positioned by the original guide 3 arranged along one side of the contact glass 1.
The pressure-contacted document is irradiated with light from a light source 5 located directly below the contact glass, and the reflected light of the document is reflected by mirrors 6, 7,
An image is formed on the photoelectric conversion element 10 through the lens 8 and the lens 9. In an image reading apparatus used in an electrophotographic image forming apparatus such as a copying machine or a printer, the optical image information input to the photoelectric conversion element 10 is converted into an electric signal, and A
After receiving the / D conversion, the image writing means irradiates the photosensitive member. In the pressure plate pressure contact mechanism shown in FIG. 2B, the pressure plate 4 has a structure in which the sponge portion 11 is supported by the frame 4a and a white sheet 12 is attached to the lower surface thereof, and the pressure plate 4 is closed on the original. Thus, the original 2 is pressed against the contact glass 1.

However, in the above prior art, the pressure plate 4
If there is any deformation such as warpage or bending, the white sheet 12
Since the sponge 11 and the sponge 11 are deformed following warpage and bending, respectively, when the originals pressed by the sponges 11 have curls as shown in the drawing, the warped portion may sufficiently adhere to the contact glass during reading. It becomes impossible and a blurred image can be obtained. Further, even when a document without curl is set in contact with the document guide 3, if the pressure plate having the above deformation is pressed, the document is likely to be displaced when the pressure plate is closed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and prevents floating of a document caused by deformation of a pressure plate or curling of a document, and image defects due to misalignment. It is an object of the present invention to provide an image reading device that can be used.

[0005]

In order to achieve the above object, the present invention is a document pressing mechanism of an image reading apparatus equipped with a pressure plate for pressing a document placed on a contact glass from above, and the mechanism is provided between the contact glass and the pressure plate. A flexible sheet is interposed, the flexible sheet is detachably supported by the image reading device, and the flexible sheet is transparent.

The present invention will be described below with reference to the preferred embodiments shown in the accompanying drawings. 1 (a) and 1 (b) are a perspective view and an explanatory view of an essential part of an image reading apparatus to which the present invention is applied, and FIG. 2 is a longitudinal sectional view showing the structure of a document pressing mechanism. is there. The internal structure of this image reading device is the same as that shown in FIG. Further, the structure of the document pressing mechanism centering on the pressure plate is such that the transparent flexible sheet 15
Since there is no difference from the above-mentioned conventional example except for the existence of the above, the same parts will be described with the same reference numerals.

As shown in FIGS. 1 (a) and 1 (b) and FIG. 2, one side of a transparent flexible sheet 15 is fixed along one side of the contact glass 1. It is configured to be openable and closable in the vertical direction with the fastening side 15a as the center, and is dimensioned so that the contact glass 1 can be completely closed when closed. In this drawing, the flexible sheet is configured to open and close in a direction intersecting with the pressure plate 4, but this is only one embodiment, and any side of the flexible sheet is fixed to the upper surface of the device. Good. However, the dimensions are set so as not to interfere with the document guide 3 when the flexible sheet is closed. As shown in FIG. 1B, for example, the flexible sheet 15 has a structure in which it is integrated with a supporting member 16 made of resin, metal, or the like by a double-sided tape or the like.
The support member 16 may be fixed to the upper surface of the housing with screws or the like. The flexible sheet is preferably attachable / detachable to / from the image reading device, and is configured so that it can be removed as necessary. Reference numeral 4b is a hinge portion that supports the pressure plate 4 with respect to the reader housing.

In the above arrangement, when setting the original, the original 2 is set on the contact glass 1 along the original guide 3 and then the flexible sheet 15 is covered so as to be in close contact with the original. Finally, the platen is closed and the image is read. Since the flexible sheet 15 is transparent, the position shift of the document can be visually confirmed when the flexible sheet 15 is closed on the document, so that the position can be corrected before closing the pressure plate. Further, even when the document is curled, the flexible sheet can force the pressure contact, so that the floating of the contact glass can be prevented.

[0009]

As described above, according to the present invention, a flexible sheet is interposed between the contact glass and the pressure plate so as to press the document, so that when the pressure plate is warped or bent. Also, it is possible to read an image while preventing the document from floating from the contact glass. Therefore, it is possible to prevent the occurrence of a blurred image due to the floating. Further, since the flexible sheet is transparent, it is possible to visually detect the positional deviation when the original is set and correct it in advance, so that it is possible to prevent erroneous copying.

[Brief description of drawings]

1A and 1B are a perspective view showing a configuration of an embodiment of the present invention and a perspective view of a main part.

2 is a longitudinal sectional view of the embodiment shown in FIG.

3A and 3B are a longitudinal sectional view of an image reading apparatus of a conventional example and a longitudinal sectional view of a document pressing mechanism.

[Explanation of symbols]

1 contact glass, 2 originals, 3 original guides, 4
Pressure plate, 4a frame, 5 light source, 11 sponge part, 12 white sheet, 15 flexible sheet,

Claims (3)

[Claims] 1. A document holding mechanism of an image reading apparatus comprising a pressure plate for pressing a document placed on a contact glass from above, wherein a flexible sheet is interposed between the contact glass and the pressure plate. Image reading device. 2. The image reading apparatus according to claim 1, wherein the flexible sheet is detachably supported by the image reading apparatus. 3. The image reading device according to claim 1, wherein the flexible sheet is transparent.