JPH10221789A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly hold a thick original, to uniformly bring an original surface into contact with a platen glass, and to prevent a thin sheet original from being moved by wind pressure in the case of opening/closing an original cover plate. SOLUTION: In the case of closing the original cover plate 4, the plate 4 is turned with center at a specified fulcrum first and gradually approaches the platen glass 2. The original cover surface of the plate 4 moves perpendicularly to the surface of the platen glass 2 and approaches to the platen glass 2 from a specified position near the plate glass 2. Therefore, the excellent image reader 1 capable of obtaining a uniform image, preventing the original from being deviated and damaged and also preventing the original from being blown off by the wind pressure whatever kind of original it is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus for reading an image on a placed original.

[0002]

2. Description of the Related Art Conventionally, as an image reading apparatus for reading an image on a surface of a placed document, an image reading apparatus provided in an image forming apparatus such as an electrophotographic copying machine is widely known.

FIG. 5 shows a typical conventional image reading apparatus.

The image reading apparatus 100 illuminates an original surface of an original G placed on an original mounting table 101 such as a platen glass with an exposure lamp, and reflects the reflected light by a mirror, a lens, or the like to an image forming unit ( (CCD, photosensitive drum, etc.).

In this configuration, the original is pressed down from the back in order to uniformly adhere the original G to the platen glass 101, to prevent the original from shifting, or to prevent the illumination light of the exposure lamp from directly entering the eyes. Generally, an original pressing plate 102 to be covered is used.

The document pressing plate 102 has a pivot hinge 103 on the back side, and a pivot fulcrum 104 on the back side.
There is generally known a type which can be operated up and down while holding a handle portion 102a on the near side.

[0007]

However, the above-mentioned conventional document pressing plate has the following problems.

(1) The document pressing pressure plate 102 is located at the back fulcrum 10
4, the thick original G such as a book original cannot be pressed uniformly by hitting the original when pressing the original. That is, a uniform image cannot be obtained because the document surface cannot be uniformly adhered to the platen glass 101. Further, since a force is applied to one portion of the document, the document is easily damaged (the portion indicated by arrow A in FIG. 5).

(2) The document pressing pressure plate 102 is located at the back fulcrum 10
4, if the document pressing pressure plate 102 is closed in order to press a thin sheet document, the sheet document is pushed forward by wind pressure.

In order to cope with the above-described problem, there is a document in which the document pressing surface 105 of the document pressing pressure plate 102 is formed of an elastic body such as a soft sponge.

A rotating hinge portion 103 of the original pressing plate.
There has also been proposed a type in which the (fulcrum) is movable up and down so that when the document pressing plate 102 hits the thick document G, the hinge portion 103 escapes to disperse the force.

[0012] However, the above-mentioned improvement is insufficient, and the problems (1) and (2) cannot be effectively solved.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and when closing a document pressing plate, the document pressing plate first rotates around a predetermined fulcrum. The document pressing surface of the document pressing plate moves perpendicularly to the platen glass surface and approaches the platen glass from a predetermined position near the platen glass.

Therefore, regardless of the type of document, there is provided an excellent image reading apparatus in which the image is uniform, the document is not misaligned, the document is not damaged, and the document is not blown by the wind pressure. Can be provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. 1 to 4 are left side sectional views of an image reading unit according to an embodiment of the present invention.

1 is an image reading apparatus of the present invention. Reference numeral 2 denotes a platen glass as a document table. An image of the original placed on the platen glass 2 is provided with an exposure lamp (not shown), which is disposed substantially below the platen glass 2.
The image is read by a known image reading unit 3 including a mirror, a lens, a CCD, and the like.

Reference numeral 4 denotes a document pressing pressure plate for pressing a document placed on the platen glass 2. The document pressing pressure plate 4 includes a document pressing sheet 5 made of a flexible sponge and an operation handle 6.

Reference numeral 7 denotes a hinge base for enabling the original pressing plate 4 to be opened and closed. The hinge base 7 is provided with a pivot 8.

An opening / closing auxiliary table 9 that is rotatable about a rotation fulcrum shaft 8 is provided. The opening and closing auxiliary table 9 has a second
Fulcrum shaft 10 is provided. Reference numerals 11 and 12 denote first and second link plates rotatable around the fulcrum shafts 8 and 10, respectively. One of the first and second link plates 11 and 12 is rotatably engaged with pins 13 and 14 provided on the document pressing plate 4. As a result, the original pressing plate 4 can move vertically with respect to the opening / closing auxiliary table 9.

Reference numeral 15 denotes a first stopper which regulates an opening amount of the opening / closing auxiliary table 9 with respect to the hinge table 7. The first stopper 15 includes a pin 16 provided on the opening / closing auxiliary table 9,
By restricting the position of the pin 17 provided on the hinge base 7, the opening amount of the opening / closing auxiliary base 9 with respect to the hinge base 7 is controlled.

Reference numeral 18 denotes a second stopper for defining the opening amount of the document pressing plate 4 with respect to the platen glass 2.
A part 4a of the document pressing pressure plate 4 abuts against the second stopper 18, thereby defining an opening amount of the document pressing pressure plate 4 with respect to the platen glass 2.

Reference numeral 19 denotes a first spring for offsetting the weight of the original pressing plate 4 to improve the operability of the original pressing plate 4. One end of the spring 19 is fixed to the hinge base 7, and the other end urges the opening / closing auxiliary base 9. That is, the original pressing plate 4 is indirectly urged from below, and balances the weight of the original pressing plate 4 to reduce the operating force when operating the original pressing plate 4.

Reference numeral 20 denotes a second spring for holding the position of the document pressing plate 4. The second spring has one end fixed to a part 21 of the hinge base 7 and the other end fixed to a part 22 of the first link plate. The second spring 20 forms a toggle mechanism with respect to the fulcrum 8. When the straight line connecting the fixed points 21 and 22 of the second spring 20 is on the right side with respect to the fulcrum 8,
The first link plate 11 is urged in a clockwise direction (arrow B direction in FIG. 1) with respect to the fulcrum 8. That is, the document pressing pressure plate 4 moves clockwise with respect to the fulcrum 8 (arrow B in FIG. 1).
Direction).

The fixed points 21 and 2 of the second spring 20
When the straight line connecting 2 is on the left side of the fulcrum 8, the first
Is urged in the counterclockwise direction (the direction of arrow C in FIG. 3) with respect to the fulcrum 8. That is, the original pressing plate 4
Is urged counterclockwise with respect to the fulcrum 8 (the direction of arrow C in FIG. 3).

Next, the operation of the image reading apparatus of the present invention will be described.

FIG. 1 shows a state where the original pressing plate 4 is already closed. In this state, the second spring 2
Since the straight line connecting the 0 fixed points 21 and 22 is on the right side with respect to the fulcrum 8, the document pressing pressure plate 4 is urged in the clockwise direction (the direction of arrow B in FIG. 1) with respect to the fulcrum 8. .

In this state, the following operation is performed to place an original on the platen glass 2 and read an image.

First, the operation handle 6 is pushed upward. Then, the first link plate 11, the second link plate 12, the document pressing plate 4, and the opening / closing auxiliary table 9 gradually rotate integrally with the fulcrum 8 in the arrow C direction. Then, the first
Both ends of the stopper 15 contact the pins 16 and 17. That is, the first stopper 15 prevents the opening / closing auxiliary table 9 from further rotating in the arrow C direction (FIG. 2).

From this state, the operation handle 6 is further pushed up. Then, since the movement of the opening / closing auxiliary table 9 is prevented, the first link plate 11, the second link plate 12, and the document pressing plate 4 move. At this time, the first link plate 11 rotates about the fulcrum shaft 8, and the second link plate 12 rotates about the fulcrum shaft 10. The first link plate 11, the second link plate 12, the document pressing pressure plate 4, and the opening / closing auxiliary table 9 constitute a link mechanism with each other. Therefore, the original pressing plate 4 moves vertically in the direction away from the opening / closing auxiliary table 9 (the direction of arrow D in FIG. 3) by this series of operations. Then, the rear end portion 4a of the original pressing plate 4 abuts on the second stopper 18 and is prevented from moving (FIG. 3).

In this process, the fixed point 21 of the second spring 20
And the straight line connecting 22 moves to the left over the fulcrum 8. Therefore, when the rear end portion 4a of the document pressing pressure plate 4 abuts against the second stopper 18, the document pressing pressure plate 4 moves counterclockwise with respect to the fulcrum 8 (arrow C in FIG. 3).
Direction). That is, the document pressing pressure plate 4 is substantially fixed in a state where it hits the second stopper 18. In this state, an original is set on the platen glass 2.

Next, the operation when closing the original pressing plate 4 will be described.

The operating handle 6 is pushed down from the state shown in FIG. Then, the first link plate 11 and the second link plate 1
2. The document holding pressure plate 4 and the opening / closing auxiliary table 9 gradually rotate integrally with the fulcrum 8 in the arrow B direction. Then, a part 9a of the opening / closing auxiliary table 9 abuts against the stopper 7a of the hinge table 7 (FIG. 4).

From this state, the operating handle 6 is further depressed. Since the movement of the opening / closing auxiliary table 9 is prevented, the first
Link plate 11, second link plate 12, document pressing plate 4
Moves. At this time, the first link plate 11 is
The second link plate 12 rotates about the fulcrum shaft 10. 1st link board 11, 2nd link board 1
2. The document pressing pressure plate 4 and the opening / closing auxiliary table 9 constitute a link mechanism with each other. Therefore, by this series of operations,
The document pressing plate 4 moves vertically in the direction (arrow E direction) approaching the platen glass 2. Then, the original pressing sheet 5 of the original pressing plate 4 is prevented from moving by pressing the original from the back (FIG. 4).

In this process, the fixed point 21 of the second spring 20
And the straight line connecting 22 moves over the fulcrum 8 and moves to the right. Therefore, when the document pressing pressure plate 4 is closed, the document pressing pressure plate 4 is urged in the clockwise direction (direction of arrow B) with respect to the fulcrum 8. That is, the original pressing plate 4 is
The document is substantially fixed in a state where the document is urged from the back.

In the vicinity of the platen glass 2, the original pressing plate 4
May be set in any manner, but considering the thickness of a general book original, 3
About 0 to 80 mm is appropriate.

The present invention has been described with reference to the original pressing plate having a flexible sheet on its surface as the original pressing plate. However, the present invention is not limited thereto. For example, a document pressure plate integrally provided with a known document feeder may be used.

[0037]

As described above, according to the present invention, when the document pressing plate is closed, the document pressing plate first rotates around a predetermined fulcrum and gradually approaches the platen glass. From a nearby predetermined position, the original pressing surface of the original pressing plate moves perpendicular to the platen glass and approaches the platen glass.

Therefore, regardless of the type of the original, an excellent image reading apparatus which has a uniform image, has no misalignment of the original, does not damage the original, and is not blown by the wind pressure. Can be provided.

[Brief description of the drawings]

FIG. 1 is a left side sectional view illustrating an embodiment of the present invention.

FIG. 2 is a left side sectional view illustrating an embodiment of the present invention.

FIG. 3 is a left side sectional view illustrating an embodiment of the present invention.

FIG. 4 is a left side sectional view illustrating an embodiment of the present invention.

FIG. 5 is a left side sectional view showing a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Platen glass 3 Image reading part 4 Document pressing pressure plate 5 Document pressing sheet 6 Operation handle 7 Hinge table 8 Rotating fulcrum shaft 9 Opening and closing auxiliary pedestal 10 Support shaft 11 First link plate 12 Second link plate 13 , 14, 16, 17 Pin 15 First stopper 18 Second stopper 19 First spring 20 Second spring 21, 22 Fixed point

Claims (2)

[Claims] A platen glass serving as a document mounting table on which a document is mounted; an image reading unit for reading an image on the surface of the document placed on the platen glass; and a document placed on the platen glass substantially fixed. An original reading pressure plate, wherein when the original pressing plate is closed, the original pressing pressure plate first rotates around a predetermined fulcrum and gradually approaches the platen glass, An image reading apparatus wherein an original pressing surface of an original pressing plate moves perpendicular to a platen glass surface and approaches a platen glass from a predetermined position in the vicinity. 2. The image reading apparatus according to claim 1, wherein the document pressing plate also functions as a document feeder that conveys a document onto a platen glass.