JPH09325531A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the defective supply of an original such as bending, non-supplying or jam from occurring because the leading edge of the original is hung from a gap between the tip of a pressing plate and a stopper member and caught by the stopper member when the soft original of a thin paper and the like or the original having back-curling inclination is supplied. SOLUTION: This device is constituted so that the lower surface of the leading edge part of the bundle of the originals 2 set on an original table is supported by the pressing plate 3 which can be moved up and down and which is provided with a bent part bent downward at the tip part thereof. The leading edge part of the bundle of the originals 2 is raised by the plate 3 and called at the supply time. By interposing the leading edge part of the bundle of the originals 2 between a roller 4 and the plate 3, supply pressure is generated. Then, the originals 2 are supplied from the uppermost one by calling it in the interposing state and rotating the roller 4 in a supply direction. The upper surface of the plate 3 is provided with a plate-like elastic member 31. Besides, the tip part of the elastic member 31 is separated from the upper surf ace of the plate 3 and made to project forward at a front position over the top of the bent part at the non-supply time. Then, at least one part of the tip part of the elastic member 3 is made to project more forward than the abutting surface of the stopper member 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an automatic document feeder, and more particularly to an automatic document feeder capable of favorably feeding and conveying thin originals to thick originals.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus, originals are fed one by one to a reading position, and each read original image is formed on a recording sheet by an image forming unit. It has a structure for. An automatic document feeder is conventionally used as a means for feeding a document to a reading position.
A configuration is provided for taking out the originals one by one from the original bundle set on the original table and feeding the originals to the original reading position of the image forming apparatus main body. FIGS. 4 (a) and 4 (b) are schematic views of the main part (the leading end of the document set on the document table) of an example of a conventional automatic document feeder, and show the document table on the right side of this figure. The front end portion of the document stack D set on is placed on a pressure plate 101 that moves up and down around a shaft 100, and the front end edge of each document is the stopper member 1.
The position of the tip is regulated by 02. A calling roller 103 is arranged above the leading edge of the document,
At the time of paper feeding, as shown in (b), the pressure plate 101 rises to press the leading edge of the original stack with the calling roller 103 to generate a paper feeding pressure. In this state, the calling roller 103 is rotated in the paper feeding direction. By doing so, the document is fed. The fed originals are separated one by one by the separating means 104 and conveyed to a reading position (not shown). Pressure plate 101
The tip of the is a bent portion 101a that is bent downward. This is when the original is pushed up as shown in Fig. 4 (b).
This is a consideration for generating an appropriate pressing force between the calling roller 103. However, in this conventional example, the tip of the pressure plate 101 is in a bent state, and when the pressure plate 101 rises, the tip of the pressure plate 101 and the abutting surface (right side surface) of the stopper member 102 are Since a gap between the two is formed, when feeding a weak original such as a thin original, the leading edge of the last and near-last lower original will hang down from the gap as shown in (b). It becomes difficult to get over the upper end portion of the stopper member 102 and feed it to the front side, and it is easy to be bent, fail to feed, or jam. Such a problem also occurs when the document itself has a back curl (downward curl at the time of setting). Further, since the leading end of the document D easily enters the clearance y between the stopper member 102 and the leading end of the pressure plate 101, it becomes difficult to secure stable feeding.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and the lower surface of the leading end portion of a document stack set on a document table is supported by a vertically movable pressure plate and is applied at the time of sheet feeding. An automatic document feeder that feeds by raising the leading edge of the document stack by the pressure plate to generate a paper feed pressure between the calling roller and the pressure plate, and rotating the calling roller in the paper feeding direction in this state. In the case where a document having a stopper member that regulates the leading edge of the document stack is fed, when feeding a document such as thin paper having a weak stiffness or a document having a back curl tendency, the document leading edge and the stopper member To provide an automatic document feeder that can prevent a paper feed failure such as a fold, a non-feed, or a jam due to a hanging from a gap between the paper and a stopper member. It is an object.

[0004]

In order to achieve the above object, the invention of claim 1 is such that the lower surface of the front end portion of the original stack set on the original table is vertically movable and bent downward at the front end portion. It is supported by a pressure plate having a section, and when feeding, the leading edge of the document stack is raised by the pressure plate, and the leading edge of the document bundle is pinched between the calling roller and the pressure plate located above to increase the feeding pressure. An automatic document feeder that generates and feeds the uppermost original by rotating the calling roller in the paper feed direction in the pinched state, and a stopper member that regulates the leading edge of the original bundle with an abutting surface. A flat plate-shaped elastic member is attached to the upper surface of the pressure plate, and the tip end of the elastic member is located at the front position beyond the top of the bent portion when the sheet is not fed. Away from and project forward Cage, and at least a portion of the elastic member tip is characterized in that protrudes forward from the abutting surface of the stopper member.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the preferred embodiments shown in the drawings. FIG. 1 is a schematic diagram showing the overall configuration of the automatic document feeder of this embodiment. The automatic document feeder 1 is mounted on the upper surface of the image forming apparatus main body 29. The image forming apparatus main body 29 of this embodiment has two exposure units (original reading positions) on its upper surface. The first exposed portion is a portion of the slit glass 30, and the second exposed portion is a portion of the contact glass 19. The original 2 fed and conveyed by the automatic original feeder 1 has its original surface read by the reading optical system located immediately below it in the first exposure section. Next, the structure of the automatic document feeder 1 will be described. The automatic document feeder 1 is configured to be movable up and down around a document table 11 for setting a document 2 and a shaft 3a which is located in front of the front end of the document table 11, and is arranged in front of the document table 11. The pressure plate 3 that supports the protruding front end of the document, the calling roller 4 that is located above the document line tab on the pressure plate 3 and is driven to rotate in the paper feeding direction, and the front end of the document on the pressure plate 3 A stopper member 5 arranged to regulate the leading edge, a separation means composed of a separation belt 6 and a separation roller 7, and a first conveyance roller arranged on a conveyance path downstream of the separation means to convey the separated original document. 8 and an elastic guide plate 9 (polyester film, t
= 0.1 to 0.2 mm) and its support frame 10,
The original table 11, the reflection guide plate 12 which is arranged directly above the slit glass 30 to face each other with a predetermined gap, and the first mirror 13 and the light source 14 which constitute the reading optical system below the slit glass 13. The second transport roller 15 disposed on the downstream transport path of the slit glass 30, the paper discharge roller 16, the holding member 17 that holds the second transport roller, the contact glass 19, and the like.

As shown in FIGS. 2 and 3, etc., the characteristic structure of the present invention is that the bent portion (relief portion) 3 is retracted downward at the tip.
An elastic member 31 made of a flat elastic plate material is additionally provided on the upper surface of the pressing member 3 having b, and the tip end of the elastic member 31 is separated from the bent portion 3b at a portion corresponding to the bent portion 3b. It is configured so as to project as described above. Further, as shown in FIG. 3, the stopper member 5 is formed with a notch 5a for receiving the projecting portion 31a provided at the tip of the elastic member 31 and projecting it forward. In addition,
The reason why the bent portion 3b is provided is that, as described in the above-mentioned conventional example, the pressure member 3 rises to obtain an appropriate pressure when the leading edge of the document is pinched between the calling roller and the calling roller. . The length of the tip portion 31a of the elastic member 31 protruding from the front end edge of the main body of the elastic member 31 is l ₁ , and the length of the tip portion 31a protruding forward of the stopper member 5 is l ₂ . FIG.
As is clear from (a) and (b), of course when (a) is not feeding,
Even at the time of sheet feeding in (b), the tip end portion 31a of the elastic member projects further forward than the abutting surface of the stopper member 5.

Next, the paper feeding operation of the automatic document feeder 1 will be described. The original stack 2 is printed with the image side facing up.
The document stack 2 is set on the bull 11, and at this time, the front end of the document stack 2 projecting forward from the table 11 is set so as to abut against the abutting surface (right side) of the stopper member 5. When a print button (not shown) of the image forming apparatus main body 29 is pressed, the automatic document feeder 1 starts the feeding operation. As described above, the flat plate-shaped elastic member 31 is attached to the upper surface of the pressure plate 3, and the pressure plate 3 has the bent portion 3b. When the pressure plate 3 moves in the pressing direction indicated by the alternate long and short dash line in FIG. 2B by the operation of a solenoid (not shown), the original stack 2 is pressed by the calling roller 4. When the calling roller 4 is rotated clockwise in this state, the uppermost document from the document stack 2 is fed to the separating means 6 and 7. The separating means 6 and 7 are composed of a separating belt 6 which rotates clockwise and a separating roller 7. The original 2 separated into one sheet by the separating means is conveyed to the first exposure section by the first paper feed roller 8 and, after being read at the reading position formed by the slit glass 30, the roller 1
The sheet is discharged to the outside of the machine by 5 and 16. Image information of the manuscript is
The lamp 14 and the first mirror 13 in the fixed state read the document 2 conveyed on the slit glass 30.

FIG. 2A is a diagram showing the details of the paper feeding section.
The leading edge of the stack 2 of originals is as shown in FIG.
The flat attitude is maintained by being guided by the upper surface of the elastic member 31 protruding forward from the bent top 3A in a flat plate shape without being tilted downward along the upper surface of the tip end portion of the pressing member which is tilted downward. For this reason, the leading edge of the document stack 2 is set at a right angle to the right side surface of the stopper member 5, so that the leading ends of the documents are neatly aligned. In this way, since the leading edge of each original comes into contact with the abutting surface of the stopper 5 at right angles,
It is possible to obtain a straight conveyance locus. Further, the tip end portion 31a of the elastic member 31 having a length of l ₁ projects forward by a length l ₂ which is slightly smaller than the stopper member 5. As a result, the leading edge of the original 2 is placed at the stopper member 5.
There is no room for entering the gap y between the tip of the pressure plate 3 and the tip of the pressure plate 3, and stable feeding can be ensured.

At the time of pressurization (during paper feeding) shown in FIG. 2 (b), the tip of the elastic member 31 is pushed downward by the original 2 and becomes the shape of the tip of the pressure plate 3, The direction in which the document can be properly guided is directed toward the nip portion between the separation belt 6 and the separation roller 7. As a result, the uppermost original 2 is smoothly fed to the separating section. On the other hand, when the elastic member 31 does not bend downward along the shape at the tip of the pressure plate 3, the state shown by the dashed line in the figure is obtained, and a smooth conveying path cannot be obtained. In the present invention, since the length L of the pressure plate 3 can be reduced by adopting such a configuration, the device can be made compact and economical. Further, when a thick original is fed, the elastic member is deformed to have a shape along the upper surface of the front end portion of the pressure plate, so that good transportability can be obtained. In FIGS. 3 (a) and 3 (b), reference numeral 32 is a friction pad, and the friction pad 32 is an upper surface of the inclined tip portion of the pressure plate 3,
That is, it is provided at a portion in contact with the lower surface of the leading edge of the document stack to ensure stability during pressurization.

[0010]

According to the present invention, a thin original or a downward facing card
Even when setting a document on the document table and feeding it, the leading edge of the document does not hang down during pressure feeding, making it difficult to climb over the stopper member, and smoothly guides to the separating section. Therefore, good transportability can be obtained. Further, when a thick original is fed, the elastic member is deformed to have a shape along the pressure plate, so that good transportability can be obtained. Moreover, since the size of the pressure plate can be made small, the device becomes small, compact and inexpensive.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory diagram of an automatic document feeder according to an embodiment of the present invention.

2 (a) and (b) are configuration diagrams of main parts of FIG.

3 (a) and 3 (b) are a plan view and a side view of a main part of the apparatus shown in FIG.

4A and 4B are views for explaining the defects of the conventional example.

[Explanation of symbols]

1 ... Automatic document feeder, 2 ... Document, 3 ... Pressure plate,
4 ... Calling roller (calling member), 5 ... Stopper member, 6 ... Separation belt, 7 ... Separation roller, 8 ... First conveyance roller, 9 ... Elastic guide plate, 10 ... Frame, 11
... Table, 12 ... Reflection guide plate, 13 ... First mirror, 14 ... Lamp, 15 ... Second transport roller, 16 ...
-Ejection roller, 17 ... Second conveyance roller holding member (driven side), 18 ... Magnet, 19 ... Contact glass, 29 ... Image forming apparatus main body, 30 ... Slit glass, 31 ... Elastic member, 31a ... Tip part, 32 ... Friction pad

Claims (1)

[Claims] 1. A document stack set on a document table is supported by a pressure plate which is vertically movable and has a bent portion which is bent downward at the leading end, and the document stack is fed by the pressure plate at the time of sheet feeding. A sheet feeding pressure is generated by pressing the leading edge of the document stack between the pressure roller and the calling roller located above the pressure roller, and the calling roller is rotated in the sheet feeding direction with the pressure applied. An automatic document feeder that feeds from the uppermost document by means of a stopper member that regulates the leading edge of the document bundle by the abutting surface, wherein a flat elastic member is provided on the upper surface of the pressing plate. Is attached, and when not feeding, the tip end of the elastic member is spaced apart from the upper surface of the pressure plate and protrudes forward at a front position beyond the top of the bent portion, and at least the tip end of the elastic member is provided. Part of the strike Automatic document feeder, characterized in that protrudes forward from the abutment surface of the path member.