JPH1017219A - Circulation type document conveyance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of component parts, compared with the conventional arrangement where the necessary functions are executed from respective separate mechanisms, by equipping holder bars to hold document sheets which are thereby free from risk of dispersion and allowing the bars to serve for holding the trailing edge of each document sheet, partitioning the conveyed document sheets from those to be conveyed, and sensing the amount of prepared document sheets. SOLUTION: A stay 340 stretching parallel with the front plate 301 of a mobile unit is parallel fitted with three holder bars 313, 314, 315, which protrude from the front plate 301 when the stay 340 is moved in the direction of Arrow P5 and hold the trailing edge of the set document sheet. Therefore, the document sheet conveyed and returned will be exhausted onto the holder bars 313, 314, 315. In relation to the holder bar 314, a document height sensor 312 is installed which is to sense the condition of the bar 314.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus such as a copying machine, which sends an original to be read by an image reading apparatus from an original placing plate, and reads the original after the image is read. The present invention relates to a recirculating document feeder that is returned to a document placing plate.

[0002]

2. Description of the Related Art For example, originals mounted on a copying machine and set on an original placing plate are automatically supplied to a contact glass of the copying machine in order from the lowest original, and an image is formed by the copying machine. A recirculating document feeder is known in which the document is returned onto a document placing plate after being read. 2. Description of the Related Art Among conventional circulating document feeders, there is a so-called air-feed type circulating document feeder in which a document placed on a document placing plate is sent out using an air suction force. -139440).

In the device disclosed in the above publication,
The lowest document among the documents set on the document placing plate is attracted to the pull-in belt by air, and air is blown to the leading edge of the document, so that the lowest document is separated from the upper document. Then, the lowermost document is sequentially supplied. The supplied original is placed on the contact glass (platen glass) of the copier, and after the image is read, the original is placed on the original placing plate (when the original before reading remains on the original placing plate). , On the original).

[0004]

However, in the above-described prior art, the amount of the original set on the original placing plate cannot be detected. Therefore, it is not possible to adjust the air volume to the original size, and the original may vary. Also, not only in the air feed type, but also in a circulating type document feeder of another supply type such as a friction separation type, when the lowermost document is sent out from the document placing plate, there is a possibility that the upper document may vary. there were.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circulating document feeder capable of keeping a document set on a document placing plate from scattering.

[0006]

According to a first aspect of the present invention, there is provided a circulating document feeder, comprising: a document set at a predetermined position on a document placing plate; In a circulating document feeder that sequentially feeds and returns a document conveyed along a conveyance path to the predetermined position, a press bar that presses an upper surface of a rear end portion of the document set on a document placing plate, and a press bar And a sensor for detecting the state of the bar.

Further, according to a second aspect of the present invention, the sensor comprises:
2. The circulation type document feeder according to claim 1, wherein an amount of the set document is detected based on an initial state in which the press bar presses the set document.
The invention according to claim 3 is characterized in that the sensor detects that the set document has made one cycle when there is no document below the press bar and the press bar is in a predetermined state. A circulation type document feeder according to claim 1 or 2.

According to the above arrangement, the document does not vary since the pressing bar presses the upper surface of the rear end of the document during the document transport operation. Further, since the upper surface of the unconveyed document is pressed by the pressing bar, the document which has been transported and returned is discharged onto the pressing bar. That is, the pressing bar can separate the unconveyed document from the returned document. Further, by detecting the state of the pressing bar pressing the original by a sensor, for example, in the case of the configuration of claim 2, it is possible to detect the amount of the original set on the original placing plate. In the case of the configuration of claim 3, it is possible to detect that the document set on the document placing plate has been cycled. Therefore, it is not necessary to separately provide a sensor for detecting this.

As described above, the pressing bar can be used to press the trailing edge of the document, to separate the unconveyed document from the conveyed document, and to detect the amount of the document. Therefore, the number of components can be reduced as compared with a configuration in which each function is performed by an individual mechanism, so that the entire apparatus can be reduced in size and cost can be reduced. Also, in the case of an air-feed type circulating document feeder, the pressing bar prevents the entire document from being levitated by the air blown to the leading edge of the document, and the floating state of the leading edge of the document is improved. Thus, the effect of separating the document is improved. Further, it is possible to prevent the original from being varied due to the air blown to the leading end of the original.

According to a fourth aspect of the present invention, the pressing bar further includes a transfer means configured to be displaceable in a document conveying direction, and to transfer the document on the document placing plate to the predetermined position at the time of starting document conveyance. 4. The device according to claim 1, wherein said device is provided at a tip of said transfer means so as to be able to enter and exit.
Any one of the circulating-type document feeders. According to the configuration of the fourth aspect, the original on the original placing plate is transported by the transport means and set at a predetermined position on the original placing plate. At this time, since the original can be transported while pressing the rear end of the original by the pressing bar, the original does not vary. Also, since the holding bar is provided so as to be able to enter and exit at the tip of the transfer means, when the original is placed on the document placing plate, if the holding bar is stored in the transfer means,
The holding bar does not get in the way.

[0011]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an internal configuration of an air-feed type circulating document feeder according to an embodiment of the present invention. Referring to FIG. 1, an air-feed type circulating document feeder (hereinafter referred to as "RD
H ". ) 100 is mounted on the upper surface of the copying machine main body 50 and automatically supplies the original to the contact glass 51 provided on the upper surface of the copying machine main body 50. Also, the original that has been once supplied onto the contact glass 51 of the copying machine body 50 and returned to the original position can be automatically supplied again. That is, the document can be circulated and supplied.

The RDH 100 is rotatably attached to the copier main body 50, and can be displaced between a state of covering the upper surface of the copier main body 50 (a state shown in FIG. 1) and a state of opening. I have. The RDH 100 includes a document placement unit 200 for placing a document, a moving unit 300 for positioning and setting the placed document, and a document for supplying the set document to the copier main body 50. A feeding unit 400, a document separation mechanism 500 for separating the set documents in order to feed the documents one by one to the document feeding unit 400, and a document supplied to the copying machine main body 50 in the feeding direction or the reverse direction. The apparatus includes a transport belt unit 600 for moving in the supply direction, and a document discharge unit 700 for discharging a document from the copying machine main body 50 side.

Next, the function of each part of the RDH 100 will be described generally. First, an original is placed on the placing plate 210 of the original placing section 200. The RDH 100 according to the present embodiment is capable of setting an original of B5 size to A3 size. Then, the positioning plate 250 arranged opposite to the reference plate 230 is moved (moved in the direction perpendicular to the paper surface in the figure) according to the size of the document. As a result, the document of each size can be positioned between the reference plate 230 and the positioning plate 250 in the direction perpendicular to the plane of the drawing (the width direction of the document).
The mounting plate 210 is inclined so that the downstream side is higher than the upstream side in the document conveyance direction in order to enhance the document separation effect by air described later. Further, at a predetermined position below the mounting plate 210, the mounting plate 210
A document presence / absence sensor 295 for detecting the presence / absence of a document placed thereon is arranged.

When the copy start key provided on the copying machine main body 50 is pressed while the original is positioned in the width direction, a unit motor M1 (see FIG. 3) to be described later is driven, and the moving unit 300 is moved. In the direction of arrow P1. Thus, the original can be positioned in the left-right direction in the figure. Further, the moving unit 300 is provided with a document pressing mechanism 310, and the pressing bar 311 is once turned up in the direction of the arrow P3 and then falls down, thereby pressing the rear end of the document. The document pressing mechanism 310 is provided with a document height sensor 312 in association with the pressing bar 311, and the document height sensor 312 detects the position of the pressing bar 311.
As described above, the setting of the original is completed with the original positioned in two directions.

The original set on the original placing section 200 is
The sheet is guided to a document supply unit 400, is fed along a sheet feeding path 402 by a sheet feeding roller pair 401, and is conveyed by a conveyor belt unit 600 to a contact glass 51 of the copying machine main body 50.
It is arranged at a predetermined position above. Note that reference numeral 403 is
3 illustrates a pair of registration rollers. Registration roller pair 40
Reference numeral 3 is for adjusting the timing at which the document sent along the paper feed path 402 is temporarily stopped in the paper feed path 402 and fed onto the contact glass 51.

Reference numeral 404 indicates a pair of reversing rollers. The reversing roller pair 404 is for reversing the duplex document after copying. The double-sided document on the contact glass 51 on which copying on one side has been completed is returned to the reversing path 405 by the transport belt unit 600. The pulled back double-sided document is reversed by passing through the reversing path 405 with the rotation of the conveyor belt unit 600, the pair of reversing rollers 404, and the registration roller 403,
Contact glass 5 by conveyor belt unit 600
1 again.

The document separation mechanism 500 separates a document using air before the document is guided to the document supply unit 400. The lowermost document among the documents placed on the mounting plate 210 is sucked by the air suction unit 510 to the pull-in belt 571 by the air, and the document above the sucked document is a document. The air is levitated by air by the action of the levitating section 550. The document attracted to the pull-in belt 571 is drawn into the document supply unit 400 by the function of the document pull-in unit 570.

The original placed on the contact glass 51 by the conveyor belt unit 600 is sent to the original discharge unit 700 by the conveyor belt unit 600 after a predetermined copying operation is performed by the copying machine body 50. The transport belt unit 600 is arranged to face the contact glass 51 in the state shown in the figure, and is driven by a motor (not shown). When reversing the original, the original is sent to the reversing roller pair 404 by rotating the transport belt unit 600 in the reverse direction.

The document sent to the document discharge unit 700 is drawn into a paper discharge path 702 by a pair of paper discharge rollers 701. Thereafter, the original is sent along a paper discharge path 702 by a paper discharge roller pair 703, and the paper discharge roller pair 704, 705
To return to the original placing section 200.
The moving unit 300 moves forward and backward with respect to the document discharge unit 700, and a part of the paper discharge path 702 (downstream in the paper discharge direction) is connected between the document discharge unit 700 and the movable unit 300. It is constituted by a gap formed between them. Further, since the moving unit 300 advances and retreats with respect to the document discharge unit 700, the discharge roller pair 705 is
The moving unit 300 is provided on the side of the moving unit 300 and moves with the movement of the moving unit 300. Further, the document discharge unit 700 is provided with a home position sensor 302 for detecting that the moving unit 300 is located at a home position indicated by a solid line.

Next, the operation performed during document setting and the detailed configuration of the document separating mechanism 500 will be described with reference to FIGS. Referring to FIGS. 1 and 2, reference plate 230 and positioning plate 25
0 are arranged opposite to each other, and the original
It is arranged along the reference plate 230 fixed to 10. Positioning plate 2 according to the size of the placed document
The document is positioned in the width direction by sliding 50 along rail 251 in a direction P4 orthogonal to the document transport direction. A document size sensor (not shown) is provided below the placing plate 210 in relation to the positioning plate 250, and the document size sensor detects the document size based on the position of the positioning plate 250.

When the copy start key provided on the copying machine main body 50 is pressed while the document is positioned in the width direction in this manner, the document pressing mechanism 310 provided on the moving unit 300 is activated. When driven, three holding bars 313, 3 as the holding bar 311
14, 315 presses the rear end of the document. Therefore, the document does not vary due to the air blown out from an air outlet 552 described later or the inclination of the mounting plate 210.

Then, the unit motor M1 is driven to the home position (the position indicated by the solid line in FIG. 1).
Is moved in the P1 direction by a distance corresponding to the document size detected by the document size sensor (to the position shown by the two-dot chain line in FIG. 1). More specifically, the unit motor M1 is constituted by, for example, a stepping motor, and the unit motor M1 is rotationally driven by the number of steps corresponding to the document size, and is moved to the position indicated by the two-dot chain line.

By the movement of the mobile unit 300,
The original is pushed out to the position of the original D shown by a two-dot chain line in FIG. As a result, the original D has
0 is restricted by the front plate 301,
It is set in a state where it is regulated by the positioning plate 30 and the positioning plate 250. With reference to FIG. 1 and FIG.
In the direction orthogonal to the original transport direction of the document No. 0, six pull-in belts 572 to 577 are arranged in parallel as the pull-in belt 571, and four pull-in belts 572 to 5
75 is wound around rollers 513 and 514. The remaining two pull-in belts 576 and 577 are wound around a roller 513 and a roller (not shown). Roller 513
Is a drive roller to which the rotational force of the belt motor M2 is transmitted. Further, a plurality of through holes 578 are formed in the pull-in belts 572 to 577. The six draw-in belts 572 to 577 and the rollers 513 and 514 constitute a document draw-in section 570.

Between the rollers 513 and 514,
A suction duct 511 is provided. Suction duct 511
, A plurality of suction ports 512 are formed on a surface facing the four pull-in belts 572 to 575.
In addition, a suction fan 515 is connected to the suction duct 511, and four suction belts 572 to 575 are provided by the operation of the suction fan 515 as indicated by white arrows.
Air is sucked in through the through hole 578 and the suction port 512. The document suction unit 51 is formed by the suction duct 511, the suction fan 515, and the suction belts 572 to 575.
0 is configured.

The blower fan 5 is located adjacent to the suction fan 515.
53 is provided, and a blower duct 551 is connected to the blower fan 553. The air duct 551 is disposed downstream of the mounting plate 210 in the document transport direction. A plurality of air outlets 552 are formed in the air duct 551 at predetermined intervals in a direction orthogonal to the document conveying direction. The blower port 552 blows out the air sent from the blower fan 553 toward the leading end of the document D sucked by the pull-in belts 572 to 575, as indicated by the black arrow. Above air duct 5
The document floating unit 550 is driven by the air blower 51 and the blowing fan 553.
Is configured.

Therefore, when the document is started to be conveyed and air is sucked in from the suction port 512, the lowermost document is sucked into each through hole 578 to be pulled in by the pull-in belts 572-5.
75. On the other hand, the document above the lowermost document is levitated by the air blown out from the air blowing port 552. Therefore, the lowermost document is reliably separated from other documents. In this state, the roller 513 is driven by the belt motor M2 and the pull-in belts 572-5
As the document 75 travels, only the lowermost document is sent to the document supply unit 400 side.

FIG. 4 is a view showing the operation state of the moving unit 300 and the pressing bar 311. Document setting section 2
In a state where the original is not placed on the placing plate 210, the moving unit 300 is waiting at the home position, as shown in FIG. Also, the holding bar 31
1 is completely stored inside the mobile unit 300. Therefore, when setting the original,
The holding bar 311 does not interfere.

After the original is placed on the placing plate 210 and the positioning plate 250 is moved to match the width of the original and the copy start key of the copier main body 50 is pressed, the pressing bar 311 is moved to the position shown in FIG. It is moved in the direction of arrow P5 shown in a). Along with this movement, the tip side of the holding bar 311 is lifted up, and the state shown in FIG. Then, the holding bar 311 is rotated in the direction of arrow P8 from the state shown in FIG. 4B to hold the rear end portion of the document on the placing plate 210 (see FIG. 4C). When the document is pressed by the pressing bar 311, the moving unit 300 moves to the arrow P 1.
And the original is pushed out to the original setting position. At this time, the running of the pull-in belt 571 is started, and at the same time, air is blown out from the blower port 552, and the document is sent out from the placing plate 210 in order from the lowest document.

Since the rear end portion of the document is pressed by the pressing bar 311, the document does not slip and fluctuate due to the inclination of the mounting plate 210. Further, the upper document is not separated by the air blown out from the air blowing port 552 to separate the lowermost document from the document above the lowermost document. Further, the air from the air outlet 552 is less likely to leak from the rear end of the document, and the floating state of the front end of the document is improved. Note that the original is pressed by the pressing bar 311 to such an extent that it does not vary, and does not affect the loading into the original supply unit 400.

After the content is read for copying, the original is returned to the top of the set original, specifically, onto the holding bar 311 as shown in FIG. Therefore, the original before reading and the original that has already been read are separated by the pressing bar 311. The original returned to the mounting plate 210 is not pressed by the pressing bar 311, but the reference plate 230
Further, since the both ends are regulated by the positioning plate 250 (see FIG. 3) and the rear end is regulated by the moving unit 300, the air is not disturbed by the air from the air outlet 552.

When the reading of all the set originals is completed, the state shown in FIG. The mounting plate 210 is formed with a concave portion 211 which is one step lower than the upper surface of the mounting plate 210, and
Fits into the recess 211. The position of the pressing bar 311 at this time is detected by the document height sensor 312, and it is detected that there is no document whose content has never been read.

When a plurality of copies are required, FIG.
From the state shown in (e), the holding bar 311 is moved in the direction of the arrow P6, and the holding bar 311 is moved by the moving unit 30.
After being once stored in 0, it comes out of the mobile unit 300 again. With this movement, the holding bar 311 is raised and lowered, and holds down the rear end portion of the returned document. Thereafter, the above-described transport operation is repeated.

The required number of copies are made, and FIG.
When the state shown in (e) is reached and the document conveying operation is completed,
The holding bar 311 is moved in the direction of the arrow P <b> 6 and stored in the moving unit 300. Then, when the document is removed from the mounting plate 210, the moving unit 300 is returned to the home position from the predetermined position, and enters a standby state shown in FIG.

As described above, the pressing bar 311 suppresses the dispersion of the original by pressing the rear end of the original, and also serves to separate the original before the reading by the copying machine main body 50 from the original after the reading. Further, by detecting the state of the press bar 311 pressing the document by the document height sensor 312 shown in FIG. 1, the amount of the document on the placing plate 210 can be detected.
That is, the pressing bar 311 can be used to press the trailing edge of the original, detect the amount of the original, and separate the unconveyed original from the conveyed original. Therefore, the number of components can be reduced as compared with a configuration in which each function is performed by an individual mechanism, so that the entire apparatus can be reduced in size and cost can be reduced.

FIG. 5 is a plan view showing the structure of the document pressing mechanism 310. FIG. 6 is a rear perspective view showing the structure of the pressing bar 314 and the structure of the document amount detecting mechanism 320 for detecting the amount of set documents.
FIG. 7 is a diagram showing the operation state of the press bar. Referring to FIG. 5, the original pressing mechanism 310 includes an original amount detecting mechanism 320 provided in association with the three pressing bars 313, 314, 315 and the pressing bar 314.
And a stay 340 connecting the base ends of the holding bars 313, 314, 315, and the stay 340 in the advance direction P5.
And a driving mechanism 345 for driving the holding bars 313, 314, 315 by moving in the retreating direction P6.

The stay 340 is a rod extending in a direction parallel to the front plate 301 of the moving unit 300. The stay 340 has three holding bars 313, 314, 3
15 are attached in parallel at a predetermined interval from each other. Specifically, the holding bars 313, 314, 31
For example, when the original set on the mounting plate 210 (see FIG. 3) is B5 size, the original can be pressed by the two pressing bars 314 and 315.
In the case of 3 size, three holding bars 313, 31
4, 315 is provided so as to press the document.

The press bars 313, 314, 315 are all configured similarly except that the document height sensor 312 is provided in relation to the press bar 314. Therefore, the press bar 314 will be described below as an example. The configuration will be specifically described. Referring to FIG. 6, the holding bar 314 includes a bar main body 336 having a long and thin plate shape. A contact portion 316 made of, for example, rubber or resin and in contact with the upper surface of the document is provided on the lower surface of the tip of the bar body 336.
Is fixed. On the upper surface of the rear end of the bar body 336,
A vertically standing piece 317 is provided. A shaft 318 extending in a direction perpendicular to the bar body 336 penetrates the standing piece 317. The shaft 318 has an end face when viewed from above, which is received by a bearing hole formed at a predetermined position of a substantially L-shaped mounting member 319, and the holding bar 314 is attached to the mounting member 319 by the shaft 318. It is swingably supported. The surface perpendicular to the surface of the mounting member 319 where the bearing hole is formed is the stay 34.
0, so that the holding bar 314 is attached so as to extend in a direction perpendicular to the stay 340.

The lower surface of the holding bar 314 near the intermediate portion and the mounting member 319 are connected by a coil spring 335, and the holding bar 314 is urged in the direction of arrow P8 by the elastic force of the coil spring 335. I have. therefore,
The holding bar 314 is connected to the placing plate 210 regardless of the amount of the original.
(See FIG. 3.)
Can be suppressed with a pressing force that does not affect the taking in of the original.

Guide pins 321 are provided on both sides of the bar main body 336 near the intermediate portion thereof. One guide pin 321 is mounted on a guide base 322. The guide pins 321 may be provided only on the guide base 322 side, but by providing them on both sides as in this embodiment, it is not necessary to consider the front and back of the bar main body 336 in the manufacturing process.

The guide table 322 is for swinging the holding bar 314 about the shaft 318.
3, a base body 324 provided on the upper surface of the bottom plate 323,
The bottom plate 323 includes a support plate 326 that rises from the vicinity of the front end in FIG. 6 and a guide plate 325 that is rotatably attached to the tip of the support plate 326. Guide plate 32
5 is displaceable upward in FIG. 6 around a tip 327 attached to the support plate 326. Guide plate 32
5 is normally in contact with the upper part of the base body 324 at the rear end side, and the upper surface of the guide plate 325 is a guide surface for guiding the guide pins 321 from the upper surface of the base body 324 to the tip part 327. A guide surface 328 for guiding the guide pins 321 on the bottom plate 323 to the upper surface of the base body 324 is formed on the base body 324 so as to be continuous with the upper surface of the bottom plate 323.

The movement of the pressing bar 314 will be described in detail with reference to FIG. As shown in FIG. 7A, the state where the guide pin 321 of the holding bar 314 is located on the upper surface of the base body 324 of the guide base 322 is changed to the stay 3.
When 40 is moved to the arrow P5, the guide pin 321
It is guided by the upper surface of the guide plate 325 of the guide base 322 and moves toward the tip 327 of the guide plate 325. As a result, the holding bar 314 protrudes from the front plate 301 of the moving unit 300, and its tip end is lifted (see FIG. 7B).

When the stay 340 is further moved in the direction of arrow P5, the guide pin 321 comes off the guide plate 325,
The holding bar 314 is turned around the shaft 318 in the direction of the arrow P <b> 8 and falls down by the weight of the holding bar 314 and the elastic force of the coil spring 335. As a result, FIG.
As shown in (c), the contact portion 316 of the holding bar 314
Thus, the original on the placing plate 210 is pressed. Since the pressing bar 314 is elastically urged in the direction of arrow P8 by the coil spring 335, the original can be pressed with an appropriate force that does not affect the taking in of the original, regardless of the amount of the original set.

When the originals on the mounting plate 210 are successively sent out and the final original is sent out, as shown in FIG. 7D, the contact portion 316 of the pressing bar 314 is moved to the mounting plate 210.
Is fitted into the concave portion 211 formed at the bottom. At this time,
The guide pin 321 is located on the bottom plate 323 of the guide base 322. Then, when the stay 340 is moved in the direction of arrow P6, the guide pin 321 is guided by the guide surface 328 formed continuously on the upper surface of the bottom plate 323, and moves toward the upper surface of the base body 324. By the guide pin 321 being guided by the guide surface 328,
The tip side of the holding bar 314 gradually rises, and FIG.
As shown in (e), the holding bar 314 is in a substantially horizontal state. Then, the guide pin 321 rotates the guide plate 325, which is rotatably provided, upward, so that the guide surface 3
28 to the upper surface of the base body 324, and the moving unit 30
0 is retracted and returns to the original state.

As described above, the holding bar 314 is attached to the shaft 31.
8 and is supported so as to be swingable about
When the “0” is moved, the guide pin 321 is
By being guided by 22, it is displaced into a standing state and a lying state. Thus, the rear end portion of the document on the placing plate 210 can be pressed. Next, the document amount detection mechanism 320 will be described with reference to FIG. The document amount detection mechanism 320 includes a document height sensor 312 and a rocking plate 329 attached to a shaft 318 of a holding bar 314.
And

The document height sensor 312 is attached to the mounting member 304.
The housing 333 includes a housing 333, and a resistor (not shown) inside the housing 333. The resistor has a sensor actuator 33 whose tip projects outside the housing 333.
4 are in contact. Also, a predetermined constant voltage is constantly applied to the resistor, and the document height sensor 312 outputs a voltage corresponding to the position of the sensor actuator 334 on the resistor. The oscillating plate 329 has a semicircular portion 330 having a substantially semicircular planar shape through which the shaft 318 passes, and a long hole 3 at a predetermined position.
32, and swings about a shaft 318 in conjunction with the pressing bar 314. The sensor actuator 33 is provided in the long hole 332 of the swing portion 331.
4 are inserted.

From the state shown in FIG.
When the guide 14 is guided by the guide base 322 and its distal end is lifted around the shaft 318, the rocking plate 329 rotates about the shaft 318 in conjunction with the holding bar 314. Then, the sensor actuator 33 of the document height sensor 312
4 is slid upward by the rocking plate 329 (see FIG. 7B). Thereafter, when the guide pin 321 of the holding bar 314 separates from the upper surface of the guide plate 325 of the guide base 322 and the holding bar 314 is lowered, the swinging plate 329 causes the sensor actuator to move with the movement of the holding bar 314. 334 is slid down.

When the contact portion 316 of the pressing bar 314 contacts the upper surface of the original and the original is pressed (see FIG. 7C), a voltage corresponding to the position of the sensor actuator 334 at that time is applied to the original height sensor 312. Output from Based on the output voltage, the amount of the document on the placing plate 210 (document height) can be detected. Therefore, at this time, by controlling the drive of the blowing fan 553 (see FIG. 3) so that the amount of air matches the amount of the document detected by the document height sensor 312, the amount of air blown out from the blowing port 552 can be adjusted appropriately. It can be the air volume.

When the originals are successively sent out, the contact portions 316 of the holding bar 314 are gradually lowered, and the sensor actuator 334 is also gradually slid downward. When the final document is taken in from the placing plate 210, FIG.
As shown in (d), the contact portion 316 of the holding bar 314
Fits into the concave portion 211 of the mounting plate 210, and the sensor actuator 334 is slid further downward. Since the concave portion 211 is one step lower than the document placing surface, which is the upper surface of the placing plate 210, the position of the sensor actuator 334 at this time is apparently the position when the pressing bar 314 is pressing the document. Different. Therefore, based on the voltage output from the document height sensor 312, it can be detected that the final document has been sent out from the mounting plate 210.

As described above, since the document height sensor 312 outputs a voltage corresponding to the position of the pressing bar 314, for example, a plurality of transmission sensors are provided, and these sensors are turned on. The document amount can be finely detected as compared with a configuration in which the position of the press bar is detected based on / off (see Japanese Patent Application Laid-Open No. 61-291339). Therefore, when controlling the driving of the blower fan 553 in accordance with the document amount, the air volume of the air blown out from the air outlet 552 can be set to an appropriate air volume that matches the document amount. As a result, even if the amount of originals is small, variations in the originals due to air can be suppressed, and the originals set on the mounting plate 210 can be reliably separated and fed one by one.

The fact that the final document has been sent out from the placing plate 210 can be detected by the document height sensor 312, so that it is not necessary to separately provide a sensor for detecting this. Next, the configuration of the driving mechanism 345 will be described with reference to FIG. Slide members 338 and 339 are attached to both ends of the stay 340, respectively. The slide members 338 and 339 are a pair of guide rails 3 extending in a direction orthogonal to the stay 340.
41, 342 can be moved. When the stay 340 is reciprocated, the stay 340 is moved by the guide rails 341 and 342.
It is prevented from becoming oblique to. The slide members 338 and 339 have coil springs 343 and 3 respectively.
44 is connected to one end of each of the coil springs 343, 34.
The other ends of the guide rails 4 are connected to the rear ends of the guide rails 341 and 342, respectively. The stay 340 is urged in the retreating direction P6 by the elastic force of the coil springs 343 and 344, and the first cam 348 and the second cam 34 described later.
9 is always circumscribed. When the first cam 348 and the second cam 349 are rotated, the stay 340 is guided by the guide rails 341 and 342, so that the pressing bars 313, 314, and 315 advance in the forward direction P5.
And it reciprocates in the evacuation direction P6.

The first cam 348 and the second cam 349 are
The planar shape is substantially egg-shaped, and the stays 340 are arranged at positions spaced apart from each other by a predetermined distance in the longitudinal direction of the stays 340 in a state of being in contact with the stays 340. Thus, the two first
Since the cam 348 and the second cam 349 are provided, the stay 340 is not distorted when the stay 340 moves.

The first shaft 350 of the first cam 348 has the first
The first pulley 351 is attached above the cam 348, and the first cam 34 is further above the first pulley 351.
A position detection plate 355 for detecting the position 8 is attached. In connection with this position detection plate 355, for example, a rotation detection sensor 35 constituted by a transmission type sensor
6 are provided. A part of the peripheral surface of the position detection plate 355 is cut out, and the rotation detection sensor 356 changes from off to on when facing the notch, and stays 340.
Is pushed to the maximum in the direction of arrow P5. Further, when the rotation detection sensor 356 is changed from ON to OFF, it is detected that the stay 340 is fully retracted in the direction of arrow P6.

The rotation shaft 352 of the second cam 349 has the second shaft
A second pulley 353 is mounted above the cam 349. In this embodiment, a disk 337 having the same shape as the position detection plate 355 is provided on the rotation shaft 352 of the second cam 349.
Is attached, but it is not necessary that this notched portion be formed in the disk 337. However, by making the position detection plate 355 and the disk 337 have the same shape, the manufacturing process can be made the same.

On the other hand, the driving mechanism 345 includes the first cam 34
A pressing mechanism motor M3 that generates a driving force for rotating the second cam 8 and the second cam 349 is provided. The pressing mechanism motor M3 is driven and controlled based on the output of the rotation detection sensor 356. A worm 346 is attached to the rotation shaft of the pressing mechanism motor M3. The rotation of the worm 346 is transmitted to a worm gear (not shown), and the rotation of the worm gear causes the third pulley 347 attached coaxially to rotate. Third pulley 347, first
An endless timing belt 354 is routed between the pulley 351 and the second pulley 353, and the rotation of the third pulley 347 is controlled by the first belt 354 via the timing belt 354.
The cam 348 and the second cam 349 are rotated synchronously. Thus, the first cam 348 and the second cam 349 are also rotated synchronously. Therefore, the stay 340 is connected to the first cam 348.
And the second cam 349 is rotated synchronously,
The guide rails 342 and 343 are reciprocated at right angles to each other.

The first pulley 347 and the third pulley 35
3, the tension pulley 357 provided between
This is for applying a predetermined tension to the timing belt 354. FIG. 8 is a plan view of the first cam 348. FIG.
FIG. 9 is a graph showing the amount of movement of the stay 340. The horizontal axis indicates the distance from the rotation shaft 350 of the first cam 348 to the stay 3.
The distance to the peripheral surface in contact with 40 is taken, and the vertical axis is the amount of movement of the stay 340. The first cam 348
And the second cam 349 are formed in the same shape,
Hereinafter, only the first cam 348 will be described and its shape will be described.

Referring to FIG. 8, first cam 348 has a rotation axis 350 as a center of curvature, a center angle of angle U and a radius R1.
Are included. The radius R1 is equal to the rotation axis 3
It is the maximum radius when viewing around 50. Assuming that when the peripheral surface position 359 having the smallest distance from the rotation shaft 350 at R2 circumscribes the stay 340 is used as a reference for the amount of movement of the stay 340, as shown in FIG.
It can be seen that there is no displacement while the and the circumferential surface 358 are circumscribing.

Therefore, when the stay 340 is caused to reciprocate using the first cam 348 and the second cam 349, the stay 340 is pushed to the maximum even if there is a slight shift in the rotational phase of both. In the state (the state in which the stay 340 and the circumferential surface 358 are circumscribed), the stay 34
0 is orthogonal to the guide rails 342 and 343.

As a structure for reciprocating the stay 340, a structure as shown in FIG. 10 can be considered.
In this configuration, one pin 12, 13 is erected on the upper surface of each of the two disks 10, 11. Stay 34
0 has an elongated hole 14 penetrating from the upper surface to the lower surface, and pins 12 and 13 are inserted into the elongated hole 14.
By rotating the two disks 10, 11 synchronously,
The stay 340 is reciprocated in the arrow P direction.

However, in the configuration shown in FIG.
If the rotations of 0 and 11 are not completely synchronized, stay 3
40 is inclined with respect to the guide rails 342 and 343 (see FIG. 5). Then, for example, the holding bar 313
Guide pin 321 of guide table 322 of guide base 322
Although the guide pin 321 of the holding bar 315 is located on the guide plate 325 despite the fact that the stay 340 is removed from the guide bar 325 (see FIG. 6), the stay 340 may be caught and become immobile in severe cases. .

However, according to the configuration of this embodiment, the above-described problem does not occur, and even if the rotation phases of the first cam 348 and the second cam 349 are shifted, the mounting plate When pressing the original on 210, the movements of the holding bars 313, 314, 315 coincide. Therefore, the original can be reliably held by the holding bars 313, 314, and 315, and the original height sensor 3
Reference numeral 12 can accurately detect the amount of the document on the mounting plate 210.

As described above, even if the rotation phases of the first cam 348 and the second cam 349 are slightly shifted, the original is pressed by the pressing bars 313, 314, and 315 and the original height sensor 312 is used. Since there is no problem in detecting the document amount, the maintenance time for correcting the phase shift can be delayed as compared with the related art. In the above-described embodiment, the position of the first cam 348 is detected by detecting the cutout portion of the position detection plate 355 attached to the rotation shaft 350 of the first cam 348 by the rotation detection sensor 356. However, a position of the first cam 348 may be detected by disposing a reflection type photo sensor and directly detecting the rotation state of the first cam 348 by the photo sensor. Also, the first cam 34
Alternatively, a metal surface may be formed at a predetermined position on the peripheral surface of 8, and the position of the first cam 348 may be detected by a proximity sensor that detects the metal surface.

Although the description of this embodiment is as described above, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, three press bars are provided. However, for example, when only one type of document size can be conveyed, only two press bars may be provided. Of course, three or more holding bars may be provided.

In addition, various design changes can be made within the scope described in the claims.

[0064]

According to the first to third aspects of the present invention, the pressing of the trailing edge of the original, the detection of the amount of the original, and the separation between the unconveyed original and the conveyed original can be performed using the pressing bar. Further, it is possible to detect that the document set on the document placing plate has made one cycle. Therefore, the number of components can be reduced as compared with a configuration in which each function is performed by an individual mechanism, and the cost of the apparatus can be reduced. In the case of an air-feed type circulating document feeder, the pressing bar presses the rear end of the document, thereby improving the document separation effect.

According to the fourth aspect of the present invention, the original can be transferred to a predetermined position on the original placing plate while the rear end of the original is pressed by the pressing bar, so that the original does not vary. In addition, when the document is placed on the document placing plate, if the press bar is stored in the transfer means, the press bar does not interfere.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an internal configuration of an air-feed type circulating document feeder according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of the document separation mechanism with a part cut away, and shows a state in which a conveyance operation has not been started;

FIG. 3 is a plan view showing a configuration of the document separating mechanism with a part cut away, showing a state where a document is set.

FIG. 4 is a diagram illustrating an operation state of a moving unit and a document pressing mechanism.

FIG. 5 is a plan view illustrating a configuration of a document pressing mechanism.

FIG. 6 is a rear perspective view illustrating a configuration of a pressing bar and a configuration of a document amount detection mechanism.

FIG. 7 is a diagram for explaining the operation of the holding bar.

FIG. 8 is a plan view of a first cam provided in the drive mechanism.

FIG. 9 is a graph showing a moving amount of a stay.

FIG. 10 is a diagram showing a reference technique for explaining the function and effect of the drive mechanism.

[Explanation of symbols]

100 Air-feed circulation type document feeder (RD
H) 300 moving unit 310 document holding mechanism 311, 313, 314, 315 holding bar 312 document height sensor

Claims (4)

[Claims] A circulation type document feeder in which a document set at a predetermined position on a document mounting plate is sent out in order from the lowest document, and a document conveyed along a conveyance path is returned to the predetermined position. And a press bar for pressing the upper surface of the rear end of the document set on the document placing plate, and a sensor for detecting a state of the press bar. 2. The recirculating document feeder according to claim 1, wherein the sensor detects an amount of the set document based on an initial state in which the press bar presses the set document. . 3. The sensor according to claim 1, wherein the sensor detects that the set document has made one cycle when there is no document below the press bar and the press bar is in a predetermined state. Item 3. A circulation type document conveying device according to Item 2. 4. The apparatus is configured to be displaceable in a document conveying direction,
2. The image forming apparatus according to claim 1, further comprising: a transfer unit configured to transfer the original on the original placing plate to the predetermined position when the original is started to be transported, wherein the pressing bar is provided so as to be able to enter and exit at the tip of the transfer unit. A recirculating document feeder according to claim 3.