JP3239256B2 - Document separation and feeding mechanism of automatic document feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document separating and feeding mechanism of an automatic document feeder provided in a document processing machine such as an electrostatic copying machine or an image reader.

[0002]

2. Description of the Related Art In recent years, copiers have come to use an automatic document feeder which automatically and automatically supplies a plurality of documents to a document set position on the upper surface of a transparent plate with the speeding up and automation of copying processing. I have. Also, an automatic document feeder for automatically feeding a plurality of documents sequentially and automatically to a document processing machine such as a facsimile or an image reader has been widely put into practical use. This type of automatic document feeder is provided with a document separating and feeding mechanism for separating and feeding a plurality of documents placed on a document table while separating the lowest one. As this kind of document separating and feeding mechanism, a plurality of document separating / feeding mechanisms are provided below a guide plate provided in the forward direction of the document table and are projected upward through an opening formed in the guide plate. In general, a feed roller having a roller and a separation belt mechanism disposed above and opposed to the feed roller are used. However, such a document separating and feeding mechanism has a configuration in which a large frictional force acts between the lowermost document and the second document from the bottom when the lowermost document is separated from the lowermost document. In the case of writing with a writing instrument that easily falls off when it comes into frictional contact with a pencil or the like, there is a problem that the back surface of the second document from the bottom is stained by the lowest document.

As a document separating and feeding mechanism for solving the above problem, a document table having an opening at a front portion in a document conveying direction,
A vacuum chamber disposed below the opening of the document table and having an opening on the upper surface, a driving roller and a driven roller disposed parallel to each other on the front side and the rear side of the vacuum chamber in the document conveying direction, and the driving roller And a vacuum separating and feeding means comprising a driven roller and a feeding belt provided with a plurality of holes wound around the vacuum chamber, and the lowest one of the documents placed on the document table. The document separation and feeding mechanism of the automatic document feeder, which feeds paper while adsorbing it on the feeding belt,
For example, JP-A-56-56443 and JP-A-62
No. 93141.

The document separating / feeding mechanism of the automatic document feeder disclosed in the above-mentioned publication is for ensuring separation of the lowest document and the second and subsequent documents among the documents placed on the document table. Discloses a technique for feeding air between the lowest document and the second and subsequent documents. In this technique, an air knife for injecting air is provided at a front end of a document placed on a document table in a document conveying direction. In order to efficiently send the air jetted from the air knife between the lowest document and the second and subsequent documents, see Japanese Patent Application Laid-Open No. 62-93.
Japanese Patent Application Publication No. 141 discloses that an opening provided in an original table is provided with a rib extending in the transport direction, and the entire feeding belt is deformed in a wave shape along the rib by the suction force of the vacuum chamber. .

[0005]

Since the rib provided in the opening is formed linearly in the transport direction, the second document cannot be completely lifted by air.
The lowermost document to be conveyed and the second document are rubbed at the ribs, thereby causing document contamination. Further, since the feed belt and the rib contact only at a specific portion, it causes early wear of the feed belt.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its main technical problems are that a rib provided at an opening formed in a vacuum chamber and a feeding belt constituting vacuum separation feeding means are provided. An object of the present invention is to provide a document separating and feeding mechanism of an automatic document feeder configured to prevent contact at a specific portion.

[0007]

According to the present invention, in order to achieve the above technical object, a document table having an opening at a front portion in a document conveying direction, and an upper surface below an opening of the document table. A vacuum chamber disposed substantially flush with the upper surface of the document table and having an opening on the upper surface; a driving roller and a driven roller disposed parallel to each other on a front side and a rear side of the vacuum chamber in a document conveying direction; A document separating and feeding mechanism of an automatic document feeder, comprising: a driving roller, a driven roller, and a vacuum separating and feeding means having a feeding belt provided with a plurality of holes disposed by winding the vacuum chamber. Wherein an opening is provided in the opening of the vacuum chamber at a slant with respect to the document conveying direction, and a rib slightly protruding from an upper surface of the vacuum chamber is provided. Document separating and feeding mechanism of a draft transport apparatus is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a document separating / feeding mechanism of an automatic document feeder constructed according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an upper end portion of an electrostatic copying machine 2 and an automatic document feeder 4 mounted thereon. The electrostatic copying machine 2 has a housing 6, and a transparent plate 8, which may be a glass plate, is provided on an upper surface of the housing 6. On one side (left side in FIG. 1) of the transparent plate 8, a document regulating member 10 for determining a document set reference position is provided.
The automatic document feeder 4 provided with the document separating / feeding mechanism constructed according to the present invention is provided on the upper surface of the housing 6 of the electrostatic copying machine 2 with the center of the pivot axis extending along the rear side edge of the transparent plate 8 as the center. It is mounted so that it can turn freely. When a document is manually placed on the transparent plate 8 of the electrostatic copying machine 2, the automatic document feeder 4 is turned upward from the illustrated closed position to the open position to expose the transparent plate 8, The document is placed at a required position on the transparent plate 8, and the automatic document feeder 4 is set to the closed position shown to cover the transparent plate 8 and the document placed thereon. When placing the original on the transparent plate 8, the original is brought into a required position by bringing one edge of the original into contact with the leading edge of the original regulating member 10 and positioning the one edge of the original at the original setting reference position. Can be positioned. A document is automatically loaded onto the transparent plate 8 using the automatic document feeder 4,
When the document is to be automatically carried out from the transparent plate 8, the automatic document feeder 4 is used at the closed position.

Continuing the description with reference to FIGS. 1 and 2, the illustrated automatic document feeder 4 includes a document table 12 as document placing means. Document table 1
2 has a first portion which is large on the front side (the left side in FIGS. 1 and 2) in the document conveying direction on the back side (upper side in FIG. 2).
Opening 14 is provided, and the first opening 1
A second opening 16 smaller than the first opening 14 is formed at the front side (left side in FIG. 2) of the document conveying direction on the side of the front side of FIG. The document table 12 has the second
A pair of guide grooves 18 extending in the width direction is provided behind the opening 16 in the document conveying direction. A support leg of a width regulating member 20 for regulating the position in the width direction of the document placed on the document table 12 is fitted into the pair of guide grooves 18, 18. 18, 18
2 in FIG. 2 along the vertical direction. In the automatic document feeder 4 in the illustrated embodiment, the position of the document placed on the document table 12 is based on the back side (one side).
The widthwise position of the document placed on the document table 12 is regulated by the inner surface of the side plate 22 and the inner surface of the width regulating member 20 erected on the rear side of the document 2. In addition, a sensor hole 17 is provided at the back of the front end of the document table 12 in the document transport direction, and a reflective first document detection sensor 21 is provided below the sensor hole 17. . The first document detection sensor 21 detects a document placed on the document table 12 and sends a detection signal to control means (not shown). The original table 12 is provided with a sensor hole 18 at a position corresponding to the front side (the lower side in FIG. 2) of the second opening 16.
A reflection type second document detection sensor 23 is provided below the sensor hole 18. This second document detection sensor 23
When the width direction size of the document placed on the document table 12 is larger than the second opening 16 from the inner surface of the side plate 22, that is, the document placed on the document table 12 is placed on the second opening 16 It functions as document detection means for detecting whether or not the document is positioned, and sends a detection signal to control means (not shown). The document detecting means for detecting whether or not the document placed on the document table 12 is located on the second opening 16 includes a means for detecting the document size based on the moving position of the width regulating member 20. A detection signal may be used.

A vacuum separating and feeding means 24 is provided below the document table 12 so as to correspond to the first opening 14. The vacuum separating and feeding means 24 includes:
Vacuum chamber 26, and vacuum chamber 26
, A driven roller 28 and a driven roller 30 disposed in parallel with each other on the front side and the rear side in the document conveying direction, and the driving roller 28, the driven roller 30 and the vacuum chamber 26.
And four feeding belts 32 are provided. The vacuum chamber 26 is formed of a synthetic resin. On its upper wall, four openings 261 are provided on the front side in the document conveying direction, and four openings 262 are provided on the rear side of the four openings 261 in the document conveying direction. ing. The four openings 261 formed on the front side in the document conveying direction are provided with ribs 263 that diagonally connect the respective openings diagonally to the document conveying direction. The rib 263 is formed so as to protrude from the upper surface of the vacuum chamber 26 by about 2 mm.
The vacuum chamber 26 thus configured is attached to the lower surface of the document table 12 by a suitable supporting means (not shown) so that the upper surface thereof is substantially flush with the upper surface of the document table 12. The vacuum chamber 26
Is connected to a suction blower 36 via a duct 34 connected to a hole (not shown) formed in a wall on the back side of the suction port. The driving roller 28 is provided in the vacuum chamber 2.
6 are provided so as to penetrate through support walls 263 and 264 provided to protrude forward in the document conveyance direction from both side walls, and both end portions of the support walls 121 and 122 are provided to protrude downward from the lower surface of the document table 12. Shaft 281 rotatably supported by bearings 37 and 38 on the shaft, and the rotating shaft 281
And four rollers 282 arranged corresponding to the document conveying direction. A roller drive gear 39 is mounted on one end of the rotation shaft 281 of the drive roller 28 thus configured.
Reference numeral 9 is operatively connected to a drive mechanism (not shown), and is driven to rotate in a direction indicated by an arrow. The driven roller 30 includes a shaft 301 supported by support walls 265 and 266 provided to protrude rearward in the document conveying direction from both side walls of the vacuum chamber 26, and the four openings 262 on the shaft 301 and the document conveying device. It comprises four rollers 302 which are rotatably arranged corresponding to the directions. The four feed belts 32
Is provided with a plurality of holes 321 and wound around rollers 282 and rollers 302 corresponding to the document conveying direction of the driving roller 28 and the driven roller 30, respectively. The feeding belt 32 configured as described above is disposed such that the upper surface thereof is located slightly above the upper surface of the document table 12. Each of the feed belts 32 wound as described above is deformed in a wavy manner by the ribs 263 at the openings 261 provided in the vacuum chamber 26, and is thus attracted to the feed belts 32 as described later. It is easy for air to enter between the lowermost document and the second and subsequent documents.

On the lower side of the original table 12, as shown in FIG.
0 is provided. As shown in FIGS. 3 and 4, the feed drum 40 is formed of a synthetic resin and has a plurality of holes 401 around the feed drum. One end of the feeding drum 40 is open, and a duct 42 connected to the vacuum chamber 26 is inserted from the open end. The duct 42 includes a suction part 421 and a connection part 422. As shown in FIG.
23. The opening 423 is formed such that only the upper side of the suction part 421 is opened in the axial direction. The upper ends of the side walls 424 and 425 of the duct 42 forming the opening 423 are configured as close as possible to the inner peripheral surface of the feeding drum 40. Therefore, each of the plurality of holes 401 formed in the feeding drum 40 is opposed to the opening 423 of the duct 42 and communicates with the duct 42 only when positioned above. Connecting part 42 constituting duct 42
A bearing 44 is provided between one end of the second suction unit 421 and one end of the feeding drum 40, and the feeding drum 40 is rotatably supported by the duct 42. Between the duct 42 and the vacuum chamber 26, an opening / closing valve 46 constituting an opening / closing means for communicating or blocking the communication between the vacuum chamber 26 and the feeding drum 40 is provided. The opening / closing valve 46 includes a valve housing 461 and a butterfly valve 463 mounted on a valve shaft 462 mounted on the valve housing 461.
One end of the valve housing 461 is inserted and connected into the vacuum chamber 26 through a connection hole 267 formed in a side wall of the vacuum chamber 26. A flange 464 is provided on the outer periphery of one end of the valve housing 461, and insertion into the vacuum chamber 26 is restricted. The flange 464 is fixed to a side wall of the vacuum chamber 26 by a fixing means such as a screw. The other end of the valve housing 461 is connected to the duct 4
It is inserted and connected to the other end of the connection part 422 constituting the two ducts 42. A flange 465 is also provided on the outer periphery of the other end of the valve housing 461, and the
Insertion inside is regulated. The opening / closing valve 46 configured as described above has a lever 4 attached to its valve shaft 462.
The lever 466 is connected to a plunger of a solenoid 468 (see FIG. 1) via a link mechanism. The butterfly valve 463 operated by the solenoid 468 is closed when the solenoid 468 is deenergized, and the solenoid 468 is closed.
Is opened when it is energized. The solenoid 468 is deenergized when the second document detection sensor 23 does not detect a document, and is energized by control means (not shown) when the second document detection sensor 23 detects detection of a document. It has become so.

An end wall 402 is provided at the other end of the feeding drum 40.
Is provided. A boss 4 is provided at the center of the end wall 402.
03 is formed, and a shaft fitting hole 404 is formed in the boss 403.
And a pin fitting groove 405 are provided. Feeding drum 40
The one end of the rotating shaft 48 is fitted into a shaft fitting hole 404 provided in the boss 403 of the end wall 402 constituting the above. A pin insertion hole 481 penetrating through the shaft in the radial direction through the axis is formed in the rotating shaft 48, and the pin 50 fitted in the pin insertion hole 481 is formed in a pin fitting groove formed in the boss 403. The driving force of the rotating shaft 48 is transmitted to the feeding drum 40 by fitting with the feeding drum 40. A bearing 52 is provided between one end of the rotary shaft 48 inserted into the feeding drum 40 and one end of the suction part 421 constituting the duct 42, and the other end of the duct 42 is connected to the rotary shaft 48. Is rotatably supported at one end. This rotating shaft 48
Is rotatably supported via a bearing 54 on a support wall 123 having an intermediate portion projecting downward from the lower surface of the document table 12, and the other end of the electromagnetic clutch 5.
6 is connected to the output side. The input side of the electromagnetic clutch 56 is connected to a drive shaft 60 rotatably supported on a support wall 121 by a bearing 58. A feed drum drive gear 59 is mounted on the drive shaft 60. The feed drum drive gear 59 is operatively connected to the roller drive gear 39 via an intermediate gear 62 as shown in FIG. The number of teeth of the intermediate gear 62 as a driving means for transmitting power from the roller driving gear 39 to the driving shaft 60 of the feeding drum 40 and the number of teeth of the feeding drum driving gear 59 are the same as those of the driving roller of the vacuum separation feeding means 24. The moving speed of the feed belt 32 operated by the feed roller 28 and the peripheral speed of the feed drum 40 are set to be substantially the same. The electromagnetic clutch 56 is deenergized when the second document detection sensor 23 does not detect a document, and is attached by control means (not shown) when the second document detection sensor 23 detects the detection of a document. It is getting energized.

A set document stopper 64 and a discharged document stopper 66 are disposed above the front end of the vacuum separating and feeding means 24 in the document conveying direction. The set document stopper 64 is configured such that the lower end thereof is positioned at a set position where the lower end contacts the upper surface of the document table 12 and an operation position that is located several mm above the upper surface of the document table 12. The ejected original stopper 66 is provided with the set original stopper 6.
4, an operation piece 661 mounted on the original set on the original table 12 by its own weight on the rear side in the original conveyance direction.
It has. The action piece 661 is configured to descend by its own weight as the document set on the document table 12 is fed, and moves the discharged document fed from the document table 12 and discharged as described later. It works to regulate. The discharged original stopper 66 is configured to retract upward from the illustrated operation position when the original is set.

An air knife 68 is disposed above the front end of the vacuum separating / feeding means 24 in the document conveying direction, at a position downstream of the set document stopper 64 in the document conveying direction. The air knife 68 includes an air chamber 681 connected to a blower (not shown) and a nozzle 682 for jetting air in the air chamber 681 toward the lower end of the set document stopper 64. When air is jetted from the nozzle 682 of the air knife 68 configured as described above, air is blown between the lowest document placed on the document table 20 and the second and subsequent documents from the bottom to lower the lowest document. Separate the original.

Continuing the description with reference to FIG. 1, a sheet feeding roller pair 70 is provided downstream of the document table 20 in the document conveying direction.
Are arranged. The sheet feeding roller pair 70 includes a driving roller 701 and a driven roller 702, and the driving roller 701 is driven to rotate in a direction indicated by an arrow by a driving mechanism (not shown). On the downstream side of the sheet feeding roller pair 70, a document carrying path 72 for guiding the document fed by the sheet feeding roller pair 70 onto the transparent plate 8 is provided. A registration roller pair 74 is provided in the document carrying path 72. The registration roller pair 74 includes a driving roller 741 and a driven roller 742, and the driving roller 741 is driven to rotate in a direction indicated by an arrow by a driving mechanism (not shown).

A transport belt mechanism 7 is provided above the transparent plate 8.
6 are provided. The conveyance belt mechanism 76 constituting the document conveyance means includes a driving roller 761 and a driven roller 762 arranged at intervals in the conveyance direction of the transparent plate 8, and an endless loop wound around the driving roller 761 and the driven roller 762. Belt 763, drive roller 761, and driven roller 7
62 and rolling rollers 764a, 764
b, 764c, 764d, 764e. The lower running portion of the endless belt 763 is extended along the transparent plate 8 of the electrostatic copying machine 2, and a document conveying path 78 is defined between the two. In the transport belt mechanism 76 thus configured, the drive roller 761 is driven to rotate by a drive mechanism (not shown).

A document discharge path 80 is provided on the right side of the document conveyance path 78 in FIG. In the document discharge path 80, a pair of transport rollers 82 and 84 and a pair of discharge rollers 86 are provided. The transport roller pairs 82 and 84 include drive rollers 821 and 841 and driven rollers 822 and 842, respectively.
61 and a driven roller 862, and each of the driving rollers 821, 841, and 861 is rotationally driven in a direction indicated by an arrow by a driving mechanism (not shown). An extruding plate 88 configured to be movable in the left and right directions by a predetermined amount in FIG. The extruding plate 88 is provided with a pair of discharge rollers 8.
6 and has a function of supporting the trailing end of the original stopped by the discharged original stopper 66 and pushing the discharged original to the left in FIG. . Therefore, the moving amount of the pushing plate 88 is set to the distance between the set document stopper 64 and the discharged document stopper 66.
The discharge roller pair 86 and the push plate 88 constitute a discharge unit, and are configured to be movable in the left-right direction in FIG. 1 according to the size of the document placed on the document table 20. The discharge roller pair 86 and the pushing plate 88
The mechanism for moving the ejection unit and the mechanism for moving the push plate 88 are described in, for example, JP-A-3-9507.
The technology disclosed in Japanese Patent Publication No. 7 can be used. The moving mechanism of the ejection unit and the moving mechanism of the push-out plate 88 are not directly related to the present invention, and thus detailed descriptions thereof are omitted.

The document separating and feeding mechanism of the automatic document feeder according to the illustrated embodiment is configured as described above, and its operation will be described below. First, a case in which a document having a small width dimension such as A4 or B5 size is used will be described. The original to be copied is placed on the original table 12 by abutting the set original stopper 64 whose front end is at the set position, and the width regulating member 20 is moved upward in FIG. The position of the document in the width direction is regulated by the inner surface of the document 20. When a document having a small width dimension is set on the document table 12 as described above, the position of the front edge of the document, that is, the lower edge in FIG. 2 does not reach the second opening 16. . When a document is set on the document table 12 in this manner, the first
The document detection sensor 21 detects that a document is set on the document table 12 and sends a detection signal to control means (not shown). In this state, when a copy start switch (not shown) is turned on, the push plate 88 is moved from a position shown by a solid line to a position shown by a two-dot chain line by a moving mechanism (not shown), and a copying operation is started to start the suction blower 36. Is driven, and the air in the vacuum chamber 26 is sucked. Therefore, the lowermost document among the documents placed on the document table 12 is attracted to the feeding belt 32 of the vacuum separation feeding unit 24. At this time,
Since air is jetted from the nozzle 682 of the air knife 68 toward the front end placed on the document table 20, the space between the lowest document placed on the document table 20 and the second and subsequent documents from the bottom Air is blown. At this time, since the feeding belt 32 is deformed in a wavy manner by the rib 263 at the opening 261 provided in the vacuum chamber 26, the lowermost original placed on the original table 20 and the second and subsequent originals are placed. It becomes easier for air to enter between
Ensure separation of the bottom document. When the copy start switch is turned on, the set original stopper 64 is positioned at an operation position several mm above the upper surface of the original table 12, and the discharged original stopper 66 is placed on the original set on the original table 12. Is actuated to abut against. On the other hand, when the copy start switch is turned on, the roller drive gear 39 is driven by a drive mechanism (not shown).
, The driving roller 28 is driven to rotate in the direction shown by the arrow. When the drive roller 28 rotates, the feed belt 32 is operated in the direction shown by the arrow, and therefore, the lowermost document adsorbed on the feed belt 32 as described above is fed downstream in the transport direction. . When the lowermost document is fed downstream in the transport direction in this way, even if the second and subsequent documents cannot be completely floated by air, the rib provided at an angle to the document transport direction. Since the protrusion of each feed belt 32 by the H.263 is formed over the whole in the width direction, the rubbing between the lowermost document and the second and subsequent documents due to the protrusion of the feed belt does not concentrate on a specific portion. Since the originals are dispersed, dirt on the original is reduced. Further, since the rib 263 provided at the opening 261 of the vacuum chamber 26 is formed to be inclined in the document conveying direction, the feeding belt 32 contacts the rib 263 over the entire widthwise direction. Only wear is prevented. When a document having a small width dimension is used, the solenoid 468 is deenergized since the second document detection sensor 23 does not detect the document, so that the open / close valve 46 is closed and the vacuum chamber is closed. The communication between 26 and the feeding drum 40 is interrupted. When the second document detection sensor 23 does not detect a document, the electromagnetic clutch 56 is also in a deenergized state, and the feeding drum 40 is also stopped.

As described above, the document fed by the vacuum separation feeding means 24 is conveyed to the document carrying path 72 by the feed roller pair 70, and the front end of the register roller 74 is inactive. The state is brought into contact with the nip portion, and the primary sheet feeding is completed. Next, the document that has been fed to the nip portion by operating the registration roller pair 74 is conveyed to a document conveying path 78 extending along the transparent plate 8 of the electrostatic copying machine 2, and further, The sheet is conveyed from the left side to the right side in FIG. 2 on the transparent plate 8 by the conveying belt mechanism 76 constituting the conveying means,
The sheet is positioned at the predetermined position and the secondary sheet feeding is completed. The exposure operation is performed in this state.

When the exposure operation of the original positioned on the transparent plate 8 is completed as described above, the transport belt mechanism 76 operates to transport the original on the transparent plate 8 toward the original discharge path 80. . The document conveyed to the document discharge path 80 is conveyed by a pair of conveying rollers 82 and 84 toward a pair of discharge rollers 86, and the document table 1
The document is carried out onto the set document placed on the document 2. At this time, the leading end of the discharged original is in contact with the discharged original stopper 66 to be distinguished from the original set first. Also,
The trailing end of the document discharged onto the document table 12 is shown in FIG.
Is supported on an extruding plate 88 positioned at a position indicated by a two-dot chain line. In this way, if all the set originals placed on the original table 12 are fed and returned on the original table 12 after the exposure operation, the discharged original stopper 66 is retracted upward from the illustrated operation position. At the same time, the set document stopper 64 is moved from the illustrated operation position to a set position where the lower end thereof contacts the upper surface of the document table 12. On the other hand, the pushing plate 88 is moved from a position shown by a two-dot chain line to a position shown by a solid line in FIG. 1 by a moving mechanism (not shown). This extruded plate 88
To the position indicated by the solid line, the trailing end of the document discharged onto the document table 12 and supported on the push plate 88 is dropped onto the document table 12. When the original discharged onto the original table 12 is copied again, the pushing plate 88 is moved to a position shown by a two-dot chain line in FIG. The original is pushed leftward in the figure by an extruding plate 88, and the front end thereof is brought into contact with a set original stopper 64 to be set again.

Next, a case where a document having a large dimension in the width direction such as A3 or B4 size is used will be described. The width regulating member 20 is moved to the front side of the second opening 16, that is, downward in FIG.
The document is placed on the upper side, the width regulating member 20 is moved upward in FIG. 2, and the position in the width direction of the document is regulated by the inner surface of the side plate 22 and the inner surface of the width regulating member 20. As described above, when a document having a large dimension in the width direction is set on the document table 12 as described above, the document is placed in the first opening 14 and the second opening 14.
Is placed over the opening 16 of the second member. In this way,
When a document is set on the document table 12, the first document detection sensor 21 and the second document detection sensor 23 detect that the document has been set on the document table 12, and the detection signal is not shown. Send to control means. In this state, when a copy start switch (not shown) is turned on, the pushing plate 88 is moved from a position shown by a solid line to a position shown by a two-dot chain line by a moving mechanism (not shown), and a copy operation is started to start a suction blower. 36 is driven, and the air in the vacuum chamber 26 is sucked. Also, the second
When the document detection sensor 23 detects a document, the solenoid 468 is energized, so that the open / close valve 46 is opened, and the vacuum chamber 26 and the feeding drum 40 are communicated. Accordingly, the front end of the lowest document among the documents placed on the document table 12 is
Is attracted to the feeding belt 32 and the feeding drum 4
It can be adsorbed to zero. At this time, since air is jetted from the nozzle 682 of the air knife 68 toward the front end placed on the document table 20, the lowermost document placed on the document table 12 and the second and subsequent documents from the bottom Air is blown in between to ensure separation of the bottom document.
On the other hand, when the copy start switch is turned on, the driving roller 2 is driven by the driving mechanism (not shown) via the roller driving gear 39.
8 is driven to rotate in the direction indicated by the arrow. Drive roller 28
Is rotated, the feed belt 32 is operated in the direction indicated by the arrow. When the second document detection sensor 23 detects a document, the electromagnetic clutch 56 is urged, so that the feeding drum 40 is rotated. Accordingly, the lowermost document adsorbed on the feed belt 32 and the feed drum 40 as described above is fed downstream in the transport direction.
As described above, when a document having a large dimension in the width direction is placed on the document table 12, that is, the second document detection sensor 23
If the original is detected, the vacuum separation feeding means 2
The feed drum 40 disposed on the side of the vacuum cleaner 4 is operated, and the vacuum separation feeding means 24 and the feed drum 40 are operated.
As a result, the lowermost document is fed while being sucked over the entire width direction, so that the oblique feeding of the document is reliably prevented. In the illustrated embodiment, when a document having a small width dimension is placed on the document table 12, that is, when the second document detection sensor 23 does not detect the document, the solenoid 468 is de-energized. Since the opening / closing valve 46 is closed, the degree of vacuum in the vacuum chamber 26 of the vacuum separating / feeding means 24 does not decrease. Also,
In the illustrated embodiment, the second document detection sensor 23
Does not detect the original, the electromagnetic clutch 56 is deenergized and the feeding drum 40 stops, so that the feeding drum 4
Since 0 does not rotate in the state where the original does not exist above it, safety can be ensured.

[0023]

The document separating / feeding mechanism of the automatic document feeder according to the present invention is constructed as described above, and is disposed obliquely with respect to the document feeding direction in the opening of the vacuum chamber constituting the vacuum separating / feeding means. Provided, a rib slightly protruding from the upper surface of the vacuum chamber is provided, so that the feed belt wound through the upper surface of the vacuum chamber is deformed into a wavy shape by the rib, and is placed on the original table. Air easily enters between the lowermost document and the second and subsequent documents, and the lowermost document can be reliably separated. When the lowermost document is fed to the downstream side in the conveyance direction while being attracted to the feeding belt, even if the second and subsequent documents cannot be completely floated by air, the document is inclined with respect to the document conveyance direction. Since the protrusion of the feed belt by the provided rib is formed in the width direction, the rubbing between the lowermost document and the second and subsequent documents due to the protrusion of the feed belt does not concentrate on a specific portion. Since the originals are dispersed, dirt on the original is reduced. Further, since the rib provided at the opening of the vacuum chamber is formed to be inclined in the document conveying direction, the feeding belt contacts the rib in a wide range in the width direction, so that wear of only a specific portion is prevented. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an automatic document feeder equipped with a document separating and feeding mechanism configured according to the present invention.

FIG. 2 is a fragmentary plan view showing a part of the document separating and feeding mechanism shown in FIG. 1;

3 is a cross-sectional view of the document separating and feeding mechanism shown in FIG. 2 taken along line AA.

FIG. 4 is a cross-sectional view of the document separating and feeding mechanism shown in FIG.

[Explanation of symbols]

 2: electrostatic copying machine 4: automatic document feeder 6: housing of electrostatic copying machine 8: transparent plate 10: document regulating member 12: document table 14: first opening 16: second opening 18: pair of guides Groove 20: Width regulating member 21: First document detection sensor 23: Second document detection sensor 24: Vacuum separation feeding unit 26: Vacuum chamber 28: Drive roller 30: Follower roller 32: Feed belt 34: Duct 36 : Suction blower 39: Roller drive gear 40: Feeding drum 42: Duct 46: Open / close valve 56: Electromagnetic clutch 58: Feeding drum drive gear 60: Drive shaft 62: Intermediate gear 64: Set document stopper 66: Discharged document Stopper 68: Air knife 70: Paper feed roller pair 72: Document carrying path 74: Registration roller pair 76: Transport belt mechanism 80: Document carrying path 2: transport roller pair 84: conveying roller pair 86: the discharge roller pair 88: pushing plate 261: opening of the vacuum chamber 262: Vacuum chamber opening 263: rib 468: solenoid

Claims (1)

(57) [Claims] 1. A document table having an opening at a front part in a document conveying direction, and a vacuum having an upper surface disposed substantially flush with an upper surface of the document table below the opening of the document table and having an opening in the upper surface. A chamber, a driving roller and a driven roller disposed parallel to each other on the front side and the rear side in the document conveying direction of the vacuum chamber, and a plurality of holes disposed by winding the driving roller, the driven roller and the vacuum chamber. A document separating and feeding mechanism of an automatic document feeder, comprising: a feeding belt having a feeding belt provided with a feeding belt provided at a position oblique to a document feeding direction at an opening of the vacuum chamber. A document separating and feeding mechanism for an automatic document feeder, wherein a rib slightly protruding from an upper surface of the vacuum chamber is provided.