JP2004002024A - Sheet conveyer of image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveyer of an image reader for reading a sheet image while automatically reversing a sheet and flowing the sheet with a compact structure. <P>SOLUTION: This sheet conveyer is provided with a conveying path 53 for receiving the sheet fed out one by one from a sheet placing means 22 and guiding to a reading position along an outer periphery of a platen roller 50 of a large diameter, and further is provided with a switchback path 71 for guiding the sheet passing the reading position to an inlet side of the conveying path 23 by switchback conveyance in a space formed between a sheet pressing means and the sheet placing means 22 provided thereabove. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a sheet conveying device of an image forming apparatus such as an image reading device or an image printing device, and for example, separates a plurality of documents placed on a document tray into one sheet and supplies the document to an image forming device such as an image reading device. It relates to a device that can be used as an automatic document feeder.
[0002]
[Prior art]
As an example of a sheet conveying device of an image forming apparatus, there is known an automatic sheet feeding device for a book scanner in which a function of reading a sheet by flowing a sheet is added to a book scanner in which a document is fixedly read. This type of apparatus includes a document placement table, a paper discharge tray, and a document separation unit, a document conveyance unit, and a paper discharge unit arranged on one side of the scanner main body. And the document tray and the paper discharge tray are arranged in a vertical relationship with each other by being rotated by 180 °.
[0003]
In this conventional apparatus, the document placing table and the paper discharge tray are arranged in a vertical relationship with each other, so that the reading of the fixed document and the reading of the fed document are realized in a compact configuration.
[0004]
[Problems to be solved by the invention]
However, in such a reading apparatus, the image information carried by the document is not necessarily limited to one surface of the sheet, but is often a double-sided document.
[0005]
In the above-mentioned conventional apparatus, there is no mechanism for automatically processing a sheet having image information on both sides of the sheet. In each case, there is a problem that the two-sided document must be set upside down by hand by hand and the operability is lacking.
[0006]
The present invention has been made in view of the above-mentioned problems relating to the conventional apparatus, and has an enhanced performance with various feeding modes while having a compact configuration similar to the conventional apparatus. An object of the present invention is to obtain a sheet conveying device of an image reading device.
[0007]
[Means for Solving the Problems]
The above object is achieved by the following configurations.
[0008]
According to a first aspect of the present invention, there is provided a sheet conveying device for an image reading apparatus, comprising: a sheet pressing unit configured to press a sheet placed on a platen of the image reading device against the platen surface; and a sheet disposed above the sheet pressing unit. Carrying means for receiving a sheet from the sheet placing means from the entrance side, passing a reading position for reading a sheet image, and discharging the sheet from a paper discharge port. And a switchback path disposed between the sheet pressing means and the sheet placing means for guiding the sheet having passed the reading position to the entrance side of the transport path by switchback transport. A rotary platen roller that forms a transport path on the surface, and a first pin that is disposed upstream of the reading position in the sheet transport direction and rolls on the rotary platen roller to transport the sheet. A roller, in which and a second pinch roller for conveying the sheet in contact with rolling the rotation platen roller arranged downstream of the sheet conveyance direction of the reading position.
[0009]
According to a second aspect of the present invention, there is provided a sheet conveying device for an image reading apparatus, comprising: a sheet pressing unit configured to press a sheet placed on a platen of the image reading device against the platen surface; and a sheet pressing unit disposed above the sheet pressing unit. A sheet mounting means for stacking and storing, a rotary platen roller for conveying a sheet to a reading position for reading a sheet image, and a guide member provided around the rotary platen roller; From the entrance side to pass through the reading position, and discharge the sheet from the paper exit,
A switchback path disposed between the sheet pressing means and the sheet placing means, for switching back the sheet conveyed on the peripheral surface of the rotary platen roller and leading the sheet back to the peripheral surface of the rotary platen roller on the entrance side of the transport path; And is provided.
[0010]
Further, the back surface of the sheet pressing means in the first and second inventions constitutes a part of the switchback path.
[0011]
Further, a switchback roller pair provided in the switchback path according to the first and second aspects of the present invention, the switchback roller pair comprising a pair of rollers for switchback conveying the sheet having passed the reading position, and a roller separation for separating the switchback roller pair from each other. Means.
[0012]
[Action]
The sheets placed on the sheet placing means are sent one by one to a transport means having a transport path for guiding the sheet toward the sheet pressing means. Then, the sheet that has passed through the transport path is discharged by a discharge unit from a discharge port that opens toward the back of the sheet pressing unit. On the other hand, a switchback path is provided between the sheet pressing means and the sheet placing means. If necessary, the sheet is discharged by the sheet discharging means during switchback conveyance, and is again fed into the conveyance path. You. In addition, since the back surface of the sheet pressing means forms a part of the switchback path, the configuration is small and simple.
[0013]
Further, if necessary, the sheet is conveyed by switchback in the switchback roller pair of this switchback path, and is again fed into the conveying path. However, when the leading edge of the sheet reversely fed from the switchback path returns to the switchback roller pair again via the transport path, and the rear portion of the sheet and the switchback roller pair rub against each other, the switchback roller pair is separated from each other. Since the sheets do not rub against each other and the switchback roller pair also serves as the sheet discharging means, the configuration is simplified.
[0014]
The image information carried on the sheet being conveyed in the conveyance path is read by the image reading unit of the image forming apparatus.
[0015]
【Example】
Next, an embodiment of the present invention will be described with reference to the drawings.
[0016]
In this embodiment, an automatic document feeder 20 that feeds a document to an image reading device 10 (hereinafter also referred to as a reading device or a main body device) as an image forming device is taken as an embodiment of the sheet conveying device.
[0017]
The reader 10 has a frame 11 as shown in FIG. 1, and the upper surface thereof is a flat fixed platen 12.
[0018]
The fixed platen 12 is made of a transparent material such as glass, and a moving illumination device (not shown) for reading image information of a document placed on the upper surface of the fixed platen 12, a moving mirror, a plurality of fixed reflections in the frame 11. A well-known reading means such as a mirror and a CCD is housed.
[0019]
An automatic document feeder (to be simply referred to as a document device) 20 to which the present invention is applied is mounted above the fixed platen 12.
[0020]
The automatic document feeder 20 has a frame 21 as a whole, and the respective functional parts which will be sequentially described hereinafter are provided in relation to the frame 21 and are opened and closed with respect to the fixed platen 12 by a hinge (not shown). ing.
[0021]
That is, as shown in FIG. 1, a document device 20 is a document tray 22 as a sheet placing means for placing a document, and feeds documents stacked and stored in the document tray 22 and separates and supplies the documents into one sheet. Feeding means, for example, a paper feed unit 30, a first registration means 43 comprising a pair of rollers 41 and 42 arranged in a main path 40 for guiding the original, and a movable illumination device for rotating the fed original. A rotating platen 50 as a transporting means for reading image information by fixing a movable mirror or the like in one place, a discharging operation for discharging the read original, and switching the original back in the middle of the discharging operation. It comprises a switchback mechanism 70 also serving as a paper discharging means for supplying to the platen 50, and a paper discharging tray 80 for receiving processed documents.
[0022]
As shown in FIG. 1, the document tray 22 serving as a sheet placing means is attached with a gentle forward tilting posture, and in this embodiment, a sheet having a maximum size of A3 can be placed in the vertical direction.
[0023]
The paper feed unit 30 includes a feed roller 33 at a tip of a swing arm 31 whose base is rotatably supported on a shaft 32, and a feed roller 34 that feeds the fed document to the shaft 32, A separation pad 35 for blocking two or less sheets.
[0024]
At an intermediate position between the feed roller 33 and the feed roller 34, a stopper 36 having a base end coupled to a swing shaft 37 for preventing the leading end of the original when the original is placed on the original tray 22 is provided. I have. Then, as shown in FIG. 1, the shaft 32 of the swing arm 31 and the swing shaft 37 of the stopper 36 are both coupled to the DC motor M1, and the stopper 36 also descends in conjunction with the lowering of the feed roller 33, thereby opening the passage. It has become. At the position of the stopper 36, an empty sensor 38 for detecting the presence or absence of a document stored in the document tray 22 is provided. Note that the feed roller 33 is vertically swung by a keep solenoid (not shown), and is displaced to a pressing position and a separating position with respect to the document placed on the document tray 22. Usually, each time the feed roller 33 is fed in a mixed loading state. When the document is moved up and down, the document bundle is kept in contact with the document until all the documents are fed, taking into consideration that the document bundle is likely to be broken by an impact when the document is pressed.
[0025]
Further, the feed roller 33, the feed roller 34, and the first registration means 43 described below are all drivingly connected to the DC motor M2 via one-way clutches OW1, OW2, OW3. When the DC motor M2 rotates forward, the one-way clutches OW1 and OW2 are connected, the feeding roller 33 and the feeding roller 34 rotate in the document feeding direction, and the first registration unit 43 is stopped. I have. Conversely, when the DC motor M2 rotates in the reverse direction, the one-way clutch OW3 is connected, and OW1 and OW2 are not connected.
[0026]
A main path 40 for sending a document extends from the paper feeding unit 30. A first resist including a pair of rollers 41 and 42 for abutting the leading end of the original fed in the middle of the main path 40 to adjust the posture and to send the original toward the rotary platen 50. Means 43 are provided. Immediately before the first registration means 43, a first registration space 44 is provided for allowing the original to bend and correcting the posture.
[0027]
In front of the first registration space 44, a size sensor 45 for detecting the size of the document by detecting the leading and trailing edges of the document is provided. A width sensor 46 for detecting the width of the document is provided on the main path 40 passing through the first registration means 43.
[0028]
By the way, the size sensor 45 cannot detect the size unless the leading and trailing edges of the document are detected. However, since the document device 20 is compact, even if the leading edge of the document reaches a reading position described later, the trailing edge is There is a possibility that the reading operation is performed without passing the sensor 45 and the document size is unknown and the provision of information to the main device 10 is delayed. Therefore, in this embodiment, the size information of the document can be recognized by the control device (not shown) based on the document width information by the width sensor 46. However, for example, the width information of B5Y by the width sensor 46 (actually, the length information of the paper) is the same as the width information of B4T, but the true size information of B5Y is obtained immediately after by the size sensor 45. The size information obtained by the width sensor 46 is corrected at an early stage.
[0029]
At the end of the main path 40 past the first registration means 43, a rotary platen 50 as a conveyance means for forming a large-diameter annular body as shown in FIG. 1 is provided.
[0030]
As shown in FIG. 2, the rotating platen 50 is a set of a plurality of ring-shaped rotating bodies connected to the platen shaft 51 at appropriate intervals. Guides 52A, 52B, and 52C for guiding the document are provided so as to surround the rotary platen 50. The guides 52A, 52B, and 52C form a transport path 53 together with the rotary platen 50.
[0031]
As shown in FIG. 1, the guide 52A is provided with a registration means including a pair of rollers 54 and 55 which come into contact with each other, for example, a second registration means 56. As shown in FIG. 1, the second registration means 56 has rolling contact points of rollers 54 and 55 on the circumferential line of the rotary platen 50, which are used for the respective rollers of the rotary platen 50 divided as shown in FIG. A plurality of sets are distributed in the middle part. With such a configuration, the document can be held more reliably, and accurate feeding timing can be achieved.
[0032]
Here, the originals handled in this embodiment and the rollers from the feed roller 33 to the feed roller 34, the first registration unit 43, the rollers of the rotary platen 50, and the rollers 54 and 55 of the second registration unit 56, etc. The arrangement relationship will be described with reference to FIG.
[0033]
FIG. 2 shows a state in which a standard size document to be handled is advancing from B5 to A3 on the basis of the traveling right edge. In the drawing, T indicates the one placed vertically in the traveling direction, and Y indicates the one placed horizontally.
[0034]
In FIG. 2, the position of the center of gravity of each document is indicated by a small circle. Comparing the center of gravity with the positions of the rollers below the feed-out roller 33, it is known that the rollers 33 and the like are arranged so as to sandwich the center of gravity or to at least lie directly above the center of gravity. In other words, when each of the rollers 33 and the like feeds a document, the document is fed by sandwiching the center of gravity or directly in contact with the center of gravity. Is correctly retained.
[0035]
On the upstream side of the guide 52A with the second registration means 56 interposed therebetween, the leading end of the document is held by the pair of rollers 54 and 55 of the second registration means 56, and the rear portion is curved to correct the posture. A second resist space 57 is provided. A second registration sensor 58 is provided immediately before the second registration unit 56.
[0036]
A slit (not shown) is formed at a substantially intermediate position of the guide 52B, and a reading position is set, so that a document is read. A read sensor 61 for detecting the leading edge of the document and informing the main unit 10 is provided in front of the reading position as shown in FIG.
[0037]
As shown in FIG. 1, the guide 52C also serves as a paper discharge path as it is, and at its end end, paper discharge means also serving as a switchback roller pair, for example, rollers 73 and 74 forming a paper discharge roller pair 72 are arranged. . The paper discharge roller pair 72 is referred to as a paper discharge roller pair 72 when acting in the paper discharge direction in FIG. 1, and when acting as a switchback roller pair as described later, the switchback roller pair is used. It is referred to as a roller pair 72. The guide 52C is provided with a paper discharge sensor (hereinafter, referred to as an SBHS sensor) 62 for detecting the leading edge and the trailing edge of the document. The number of document transport pulses from the time when the SBHS sensor 62 detects the trailing edge of the document is provided. Are counted, and the number of pulses that the rear end of the document can reach the switchback branch point is conveyed, and is used as a timing reference for stopping the document during switchback conveyance.
[0038]
Note that pinch rollers 59 and 60 for bringing a document into close contact with the platen surface are in rolling contact with the rotating platen 50.
[0039]
A discharge tray 80 that receives the processed document is provided at the end of the discharge roller pair 72. As shown in FIG. 1, the lower surface of the paper discharge tray 80 also serves as pressing means for pressing a document placed on the fixed platen 12 by hand.
[0040]
As shown in FIG. 1, there is provided a switchback path 71 for re-supplying the original from the paper discharge roller pair (switchback roller pair) 72 to the second registration space 57 to the transport path 53. At the boundary between the switchback path 71 and the guide 52C, when the document is switched back, a switching piece 75 as a one-way valve that does not return the trailing end of the document (the leading end at the time of switchback) to the guide 52C direction. Are arranged. It is to be noted that a mylar can be provided in the path of the switchback branch point in place of the switching piece 75 and substituted.
[0041]
The switchback path 71, the pair of switchback rollers 72 (switchback rollers 73 and 74), and the switching piece 75 constitute a switchback mechanism 70.
[0042]
Here, the position where the switchback (discharge) roller pair 72 is provided will be described.
[0043]
First, although there is no particular restriction on the smaller size of the original to be processed by the original device 20, the standard size of the paper is B5Y (Y is the advancement) as shown in FIG. (T indicates the vertical position in the figure as well.) The position of the switchback roller pair 72 is substantially such that the leading end (the rear end before the switchback operation) of the B5Y size document passes through the switchback path 71 and the transport path 53 and the rear end of the document. It is made so that it is rubbed at 72. With this arrangement, the document transport distance is reduced, the processing speed is improved, the transport attitude is maintained, and the document device 20 is made more compact.
[0044]
Here, a general operation of the switchback roller pair (discharge roller pair) 72 except for a special configuration and operation described in the next stage will be described.
[0045]
When the leading end of the document is detected by the SBHS sensor 62 via the transport path 53, the sheet discharge roller pair 72 starts rotating in the forward direction (the direction in which the document is fed rightward in FIG. 1). When the original is discharged as it is, the SBHS sensor 62 detects the trailing end of the original, and then stops at a predetermined time T4. On the other hand, in the case of the switchback mode, the document temporarily stops after a predetermined time T5 after the SBHS sensor 62 detects the trailing edge of the document, and then starts rotating in the reverse direction. Then, after the leading edge of the document (the trailing edge so far) is detected by the second registration sensor 58, the document stops at a predetermined time T6. After that, the document is cut off from the pulse motor M3 and enters a free rotation state, and the document is sent by the second registration means 56, the rotating platen 50 and the like.
[0046]
The second registration means 56 and the rotary platen 50 are connected to a pulse motor M3 via a clutch CL1. Similarly, a paper discharge (switchback) roller pair 72 is connected to M3 via a clutch CL2. .
[0047]
Next, the characteristic structure of the switchback roller pair 72 will be described.
[0048]
If the SBHS sensor 62 detects the leading edge of the document during the switchback conveyance, and the document size information at that time is B5Y or more, the switchback roller pair 72 is moved while the document leading edge reaches the switchback roller pair 72. The constituting SB rollers 73 and 72 are separated from each other. That is, the roller 73 moves upward from the state shown by the solid line in FIG. 1 by the excitation of the DC solenoid 76 as the roller separating means, and comes to the position shown by the broken line. By separating the rollers 73 and 74 in this manner, the leading and trailing portions of the document that are rubbed at this position are smoothly fed without being strongly rubbed.
[0049]
The lower surface of the paper discharge tray 80 serves as pressing means for manually fed documents, and also serves as a part of a switchback path for holding most of the documents during a switchback operation.
[0050]
The document device 20 has a function of performing a normal document feeding operation by a control device (not shown) and obtaining the size information based on the width information of the document described above. Further, the following mode selection control can be performed.
[0051]
1. Single-sided reading mode (K mode): The original sent out from the original tray 22 as one sheet is sent to the transport path 53 via the first registration means 43, while being sent to the rotary platen 50 by the pulse motor M3. The image information is read, and is discharged onto the discharge tray 80 by the discharge roller pair 72 as it is. (Refer to the flowcharts of FIGS. 3 to 5)
2. Double-sided reading mode (R mode): There are the following two types of R mode.
[0052]
2-1. (R1 mode)... In this mode, the front side of the document is first read, then the switch back is performed and the back side is read, and then the document is discharged. That is, the surface priority mode. (See FIGS. 6 to 8)
2-2. (R2 mode)... In this mode, the original is read first after the back side of the original is read, then switched back and then read the front side, and then discharged. That is, it is the back side priority mode. (Refer to the flowcharts of FIGS. 9 to 12)
[0053]
Next, the operation will be described.
[0054]
FIGS. 3 to 5 are flowcharts focusing on the operation in the K mode (with some common parts).
[0055]
First, when the power is turned on and the automatic paper feed button is pressed before the mode is selected, initial settings are made. The initial setting also includes that the scanning unit moves to the reading position on the main body device 10 and is located. By placing a document on the document tray 22, the empty sensor 38 is turned on (step ST02).
[0056]
Therefore, the paper feed mode is selected as shown in FIGS. 3 to 5 (ST03). Up to this point, all modes are common.
[0057]
Then, when the K mode (single-sided reading) is selected (ST04) and the start button is pressed, the M1 and M2 motors are started, the swing arm 31 is lowered as indicated by the broken line in FIG. The paper is fed out by the feeding roller 34 while being separated into one sheet by the separation pad 35 (ST05, 06). Then, the size sensor 45 detects the leading edge of the document, and the size timer T1 starts (ST07).
[0058]
When the original separated and fed into one sheet is detected by the first registration sensor 47, the DC motor M2 stops after the time T2 (ST08, 09).
[0059]
After a predetermined time, the DC motor M2 starts reverse rotation (ST10), the first registration means 43 rotates, and the width of the original that has advanced along the main path 40 is detected by the width sensor 46 (ST11). Detected by the registration sensor 58 (ST12), the signal causes the pulse motor M3 to start rotating in the forward direction, at the same time the clutch CL1 is turned on, and the rotary platen 50 and the second registration means 56 rotate (ST13). .
[0060]
The original is sent along the conveying path 53 mainly by the conveying force of the second registration means 56, and the leading end thereof is detected by the lead sensor 61 (ST14), and reading is started in step ST18. The ON / OFF of the sensor 45 is verified (ST15). If it is OFF, information that the document is a small size document of B5Y or less is obtained (ST16), and if it is ON, information that it is a large size document of B5Y or more is obtained (ST17).
[0061]
When the document reaches the guide 52B even in the transport path 53, the document is sent by the rotation of the rotary platen 50 with the help of the pinch roller 59.
[0062]
The document is read and sent to a guide 52C also serving as a paper discharge path. The leading end is detected by the paper discharge (switchback) sensor 62 (SBHS) (ST19), and the clutch CL2 is turned on by this signal, and the paper discharge (switchback) roller pair 72 starts rotating in the forward direction (document discharge direction). (ST20). Eventually, the rear end of the document passes the SBHS sensor 62, the sensor is turned off, the clutch CL1 is turned off, the rotary platen 50 and the second registration means 56 stop, and at the same time, the timer T4 starts (ST21, ST22). Then, after the time T4, the pulse motor M3 stops, and during this time, the document is discharged to the discharge tray 80, and the reading process of the first document is completed (ST23, 24).
[0063]
Next, an operation mode of the R1 mode for reading the surface with priority will be described with reference to FIGS.
[0064]
After this mode is selected and the start button is pressed (ST105), the document is read (ST118), the leading and trailing edges of the document are detected by the SBHS sensor, the clutch CL1 is turned off, the rotary platen 50 and the second registration means 56 (ST119 to 122) is the same as in the K mode in FIGS. However, the difference between the two modes is that the timer T4 in the former in step ST121 is also T5. This is because, in the K mode, the original is discharged as it is, but in the R1 mode, it is necessary to hold the rear end of the original by the discharge (switchback) roller pair 72 to prepare for the next switchback operation. is there.
[0065]
When the timer T5 is turned off, the pulse motor M3 temporarily stops (ST123, 124). At this point, the rear end of the document has passed at least the switching piece 75. At this point, the reading operation on the front side of the document has been completed.
[0066]
Next, the motor M3 starts to rotate in the reverse direction, and the sheet discharge (switchback) roller pair 72 conveys the document along the switchback path 71 with the rear end of the original as the leading end (ST125). During this time, the clutch CL1 remains OFF, so that the rotary platen 50 and the second registration means 56 remain immobile.
[0067]
Eventually, the leading edge of the document (the trailing edge up to now, hereinafter the same) is detected by the second registration sensor 58 (ST126), and after a short time T6, the M3 stops, the clutch CL2 turns off, and the document is posture-corrected by the second registration means 56. And waits (ST127).
[0068]
After a predetermined timing, when the clutch CL1 is turned on and the M3 is started, the document is sent along the transport path 53 (ST128). Steps ST129 to ST131 from the read sensor ON to SBHSON are the same as ST118 to ST120, except that the original itself is now read on the back side compared to the previous front side read.
[0069]
Here, the size information (ST116, 117) obtained earlier is verified (ST132). If the document size is B5Y or more, the DC solenoid 76 is energized, the roller 73 is separated from the roller 74, and the paper discharge (switchback) roller pair 72 is placed in a state capable of simultaneously receiving the leading end and the rear of the document. (ST133), the solenoid 76 is turned off and the clutch CL2 is turned on at the same time by detecting the trailing end of the document by turning off the second registration means 56 (ST134 to 136), and the document is read by the rotating platen 50 and the paper discharge (switchback) roller pair 72. Then, the paper is discharged to the paper discharge tray 80 (ST137 to ST139).
[0070]
On the other hand, if the document size is a small document, steps ST133 to ST135 are skipped and the process proceeds to ST136.
[0071]
Next, the operation in the R2 mode (backside priority mode) will be described with reference to FIGS.
[0072]
After the start button is pressed, size information is obtained by turning off the size sensor 45 and the leading edge of the document is detected by the SBHS sensor (ST205 to 217). Is almost the same as The difference is that the R2 mode does not require the read sensor ON in ST114 or the reading step ST118 in the R1 mode.
[0073]
Since the leading edge of the document is detected by the SBHS sensor (ST217), the process is the same as that of step 119 and subsequent steps in the R1 mode. However, since it is necessary to read the front side this time at step ST236, the process returns to ST220, and the subsequent steps are executed again. The front / back reading is completed, and the operation ends.
[0074]
The present invention is not limited to the above embodiment, and for example, the following configuration is possible.
[0075]
(1) In the above-described embodiment, the embodiment of the sheet conveying device is the automatic document feeder for the image reading device. However, if the image forming device is a printing device, the automatic sheet feeding device feeds the sheet to the printing device. It may be a supply device.
[0076]
(2) Also, as shown in FIGS. 13 and 14, a schematic diagram of the transport path (the symbols in the drawings correspond to the reference numerals in the above embodiment and have the same functions), the order of the originals is placed on the discharge tray 80. In contrast to the above embodiment, switchback pass means 91 to 95 are newly provided in the embodiment of FIG. 13 and pass means 96a to 96d and 97a to 97d dedicated to both sides are provided in FIG. In the case of a double-sided original, the paper is conveyed three times in the paper ejection path in order to match the original order, and the conveyance of the next original must be prevented for the third conveyance. By using the switchback path means 91 to 95 provided in the printer or the pass means 96a to 96d and 97a to 97d dedicated to both sides, the conveyance of the next document can be prevented and the document exchange time can be reduced.
[0077]
(3) Further, in the above embodiment, based on information from the width sensor 46 for detecting the width of the sheet provided on the path from the sheet placing means to the transport path and the size sensor 45 for detecting the presence or absence of the sheet, By providing a means for estimating the size of the sheet, a compact conveyance in which the conveyance distance of the sheet is short, the rear end of the sheet cannot pass through the sensor, and the sheet size cannot be detected by the ON / OFF interval of the sensor. Also in the system, at least a sheet size of a standard size can be detected, which can contribute to, for example, a processing operation on an image forming apparatus side corresponding to a fed sheet. Document tray 22 (sheet mounting means) to be transported and sheets from the document tray 22 to the platen 12 of the image forming apparatus. In a sheet conveying apparatus of an image forming apparatus including a conveying means 50 having a conveying path 53, a width sensor 46 (sheet width detecting means) for detecting a sheet width is provided on a path leading to the conveying path 53; A lead sensor 61 for detecting the presence or absence of a sheet at a predetermined time is provided on the upstream side of the sheet feeding to the position, and ON / OFF of the lead sensor 61 and sheet width information by the width sensor 46 (sheet width detecting means). And a controller for estimating the size of the sheet being fed based on a single-sided document flow-reading device without a switchback path. The present invention can also be applied to a general document feeder that reads out a document.
[0078]
According to the above-described embodiment, the following effects can be obtained.
[0079]
(1) A switchback in which a sheet discharged from a transport path toward the back of the sheet pressing means is guided to the entrance side of the transport path by switchback transport in a limited space between the sheet pressing means and the sheet placing means. Since the path is provided, it is possible to convey a variety of sheets, such as front-side feeding and back-side feeding, to the conveying path in a compact configuration.
[0080]
(2) Since the back surface of the sheet pressing means is part of the switchback path, the configuration can be further simplified and made compact.
[0081]
(3) Even if the leading end of the sheet reversely fed from the switchback path returns to the pair of switchback rollers via the transport path, and the rear portion of the sheet and the pair of switchback rollers are so compactly rubbed, the roller separating means This prevents the front and rear of the sheet from rubbing each other.
[0082]
(4) Since the switchback roller pair is also used as the sheet discharging means, the structure can be further simplified and the device can be manufactured at low cost.
[0083]
(5) Since an image reading unit for reading the image information carried by the sheet by the image forming apparatus is provided in the middle of the conveyance path, the image reading apparatus can be used as an automatic document feeding apparatus for feeding a document to the image forming apparatus.
[0084]
(6) Since a printing section for performing printing by the image forming apparatus on the conveyance sheet is provided in the middle of the path of the conveyance path, the conveyance section can be used as an automatic sheet feeding apparatus for the printing apparatus.
[0085]
(7) Since the registration means is provided downstream of the converging point of the conveyance path with the switchback path, the registration means for setting the alignment and feeding timing of the sheets is provided. Can be held.
[0086]
(8) Since the registration means is constituted by a pair of rollers which come into contact with each other and the rolling contact points of this roller pair are provided on the circumferential line of the ring-shaped body, the sheet is transferred by the transport means at least in a part of the transport path. Instead, the sheet is sent by the resist means, is cheaper than the conveying means constituted by an expensive large-diameter annular body, is easy to replace, and can always maintain a constant sheet clamping force.
[0087]
(9) Since a mode selection control device capable of selecting in advance the front and back priorities of the sheets supplied to the transport path is provided, when the mode is selected, for example, when used in an automatic document feeder, a single-sided original or a double-sided original For example, one side or both sides of a sheet can be freely used in a printing apparatus.
[0088]
(10) Since means for estimating the size of a sheet is provided based on information from the width sensor and the lead sensor, even a compact configuration can detect at least a sheet size of a standard size. This can contribute to the processing operation of the image forming apparatus corresponding to the above.
[Brief description of the drawings]
FIG. 1 is a side view of a main part of an automatic document feeder (sheet conveying device).
FIG. 2 is a top view of the automatic document feeder (sheet conveying device).
FIG. 3 is a flowchart 1 of a one-sided reading operation (K mode).
FIG. 4 is a flowchart 2 of a one-sided reading operation (K mode).
FIG. 5 is a flowchart 3 of a one-sided reading operation (K mode).
FIG. 6 is a flowchart 1 of a front surface priority operation (R1 mode) in duplex reading.
FIG. 7 is a flowchart 2 of a front surface priority operation (R1 mode) in double-sided reading.
FIG. 8 is a flowchart 3 of a front surface priority operation (R1 mode) in double-sided reading.
FIG. 9 is a flowchart 1 of a back-side priority operation (R2 mode) in double-sided reading.
FIG. 10 is a flowchart 2 of a back-side priority operation (R2 mode) in double-sided reading.
FIG. 11 is a flowchart 3 of a back-side priority operation (R2 mode) in double-sided reading.
FIG. 12 is a flowchart 4 of a back-side priority operation (R2 mode) in double-sided reading.
FIG. 13 is a side view of a main part of the automatic document feeder (sheet conveying device).
FIG. 14 is a side view of a main part of the automatic document feeder (sheet conveying device).
[Explanation of symbols]
10. Image reading device (image forming device)
12 Fixed platen (platen)
20 Automatic Document Feeder (Sheet Conveyor)
22 Document tray (sheet mounting means)
30 Paper feeding unit (separation feeding means)
46 width sensor (sheet width detection means)
50 rotating platen (transportation means)
53 transport path
56 Second resist means (resist means)
61 Load sensor
70 Switchback mechanism (paper discharging means)
71 Switchback path
72 Paper discharge (switchback) roller pair (paper discharge means)
76 DC solenoid (roller separation means)
80 Discharge tray (sheet pressing means)

Claims (4)

Sheet pressing means for pressing a sheet placed on a platen of the image reading device against the platen surface,
A sheet mounting unit disposed above the sheet pressing unit and configured to store and stack sheets;
Conveying means having a conveying path for receiving a sheet from the sheet placing means from the entrance side, passing a reading position for reading a sheet image, and discharging the sheet from a paper discharge port,
A switchback path that is provided between the sheet pressing unit and the sheet placing unit and guides the sheet that has passed the reading position to the entrance side of the transport path by switchback transport;
The transport means includes a rotary platen roller that forms the transport path on the outer peripheral surface thereof, and a first pinch that is disposed upstream of the reading position in the sheet transport direction and rolls on the rotary platen roller to transport the sheet. A sheet conveying device for an image reading apparatus, comprising: a roller; and a second pinch roller disposed downstream of the reading position in the sheet conveying direction and rotatably contacting the rotating platen roller to convey the sheet. Sheet pressing means for pressing a sheet placed on a platen of the image reading device against the platen surface,
A sheet mounting unit disposed above the sheet pressing unit and configured to store and stack sheets;
The sheet reading device is formed by a rotating platen roller that conveys a sheet to a reading position for reading a sheet image and a guide member provided around the rotating platen roller. A conveying path for passing the sheet through the position and discharging the sheet from the paper discharge port;
The sheet, which is disposed between the sheet pressing means and the sheet placing means, switches back the sheet conveyed on the peripheral surface of the rotary platen roller, and returns to the peripheral surface of the rotary platen roller on the entrance side of the transport path. A switchback path to guide you,
A sheet conveying device for an image reading device, comprising: The sheet conveying device according to claim 1, wherein a back surface of the sheet pressing unit forms a part of the switchback path. A switchback roller pair provided in the switchback path and configured to switchback and convey the sheet that has passed the reading position, and a roller separating unit configured to separate the switchback roller pair from each other; The sheet conveying device of the image reading device according to claim 1 or 2, wherein

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