JP3751604B2 - Sheet conveying device for image reading apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a sheet conveying device of an image forming apparatus such as an image reading apparatus or an image printing apparatus, and, for example, separates a plurality of documents placed on a document tray into a single sheet and supplies the same to an image forming apparatus such as an image reading apparatus. The present invention relates to an apparatus 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 paper feeder for a book scanner in which a sheet flow reading function is added to a book scanner of a type in which a document is fixedly read. This type of apparatus includes a document placing table, a paper discharge tray, a document separation unit disposed on one side of the scanner main body, a document transport unit, and a paper discharge unit. The original document placing table and the paper discharge tray are arranged in a vertical relationship by being rotated 180 °.
[0003]
In this conventional apparatus, the document placing table and the paper discharge tray are arranged in a vertical relationship with each other, and reading of a fixed document and reading of a fed document are realized with 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 sheet, and is often a double-sided document.
[0005]
The above-described conventional apparatus does not have a mechanism for automatically processing such a sheet having image information on both sides of the sheet, and for processing such a double-sided document, an automatic sheet feeding device is not useful. Each time, each side of the document must be turned over by hand, and there is a problem of lack of operability.
[0006]
The present invention has been made paying attention to the above-mentioned problems associated with the conventional apparatus, and has a performance that is enhanced by having various feeding modes while having a compact configuration that is the same as that of the conventional apparatus. The object is to obtain a sheet conveying device of an image reading apparatus.
[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 conveyance device for an image reading apparatus, the sheet pressing unit pressing a sheet placed on the platen of the image reading device against the platen surface, the sheet pressing unit disposed above the sheet pressing unit, A sheet placement means for stacking and storing the sheet, and a conveyance means having a conveyance path for receiving the sheet from the sheet placement means from the entrance side, passing the reading position for reading the sheet image, and discharging the sheet from the sheet discharge port. And a switchback path that is disposed between the sheet pressing unit and the sheet placing unit and guides the sheet that has passed through the reading position to the entrance side of the conveyance path by switchback conveyance. A rotary platen roller that forms a conveyance path on the surface, and a first pin that is arranged upstream of the reading position in the sheet conveyance direction and rolls against the rotation platen roller to convey 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]
A sheet conveying device of an image reading apparatus according to a second aspect of the invention is provided with a sheet pressing means for pressing a sheet placed on a platen of the image reading apparatus against the platen surface, and disposed above the sheet pressing means. A sheet placing unit for stacking and storing, 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, and a sheet from the sheet placing unit A conveyance path for receiving the sheet from the entrance side, passing the reading position, and discharging the sheet from the sheet discharge port;
A switchback path disposed between the sheet pressing means and the sheet placing means and switching back the sheet transported on the peripheral surface of the rotating platen roller to guide it back to the rotating platen roller peripheral surface on the entrance side of the transport path And are 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, the switchback roller pair that is provided in the switchback path in the first and second inventions and that is configured to switchback and convey the sheet that has passed through the reading position, and the roller separation that separates 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 conveying means having a conveying path for guiding them in the direction of the sheet pressing means. Then, the sheet that has passed through the transport path is discharged by a paper discharge unit from a paper discharge port that opens toward the back of the sheet pressing unit. On the other hand, a switchback path is disposed between the sheet pressing unit and the sheet placing unit, and is switched back and conveyed by the sheet discharge unit as needed during the discharge, and is again fed into the conveyance path. The Further, since the back surface of the sheet pressing means constitutes a part of the switchback path, the configuration is small and simple.
[0013]
If necessary, the sheet is switchback conveyed by the switchback roller pair of the switchback path, and sent again to the conveyance path. Thus, when the leading edge of the sheet that has been fed back from the switchback path returns to the switchback roller pair again via the conveyance path, and the back of the sheet and the switchback roller pair rub against each other, the switchback roller pair is separated from each other. Thus, the sheets do not rub against each other, and the switchback roller pair also serves as the paper discharge means, so that the configuration is simplified.
[0014]
Further, the image information carried on the sheet being conveyed on 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 apparatus 10 (hereinafter also referred to as a reading apparatus or a main body apparatus) as an image forming apparatus is taken up as an embodiment of the sheet conveying apparatus.
[0017]
As shown in FIG. 1, the reader 10 has a frame 11, 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), a moving mirror, and a plurality of fixed reflections for reading image information of a document placed on the upper surface of the fixed platen 12 are provided in the frame 11. A well-known reading means including a mirror and a CCD is accommodated.
[0019]
Above the fixed platen 12, an automatic document feeder (simply referred to as a document device) 20 to which the present invention is applied is placed.
[0020]
The automatic document feeder 20 has a frame body 21 as a whole, and each functional part to be described in sequence will be provided in association with the frame body 21 and can be opened and closed with respect to the fixed platen 12 by a hinge (not shown). ing.
[0021]
That is, as shown in FIG. 1, the manuscript device 20 feeds out a manuscript tray 22 as a sheet placing unit for placing manuscripts, and feeds the manuscripts stacked and accommodated in the manuscript tray 22 and supplies them separately. Feeding means, for example, a sheet feeding unit 30, a first registration means 43 comprising a pair of rollers 41, 42 disposed in a main path 40 for guiding the document, the fed document being rotated, and the moving illumination device , A rotating platen 50 as a conveying means for reading the image information by fixing a moving mirror or the like in one place, a paper discharge operation for discharging the read original, and a switchback of the original in the middle of the paper discharge operation, and the rotation again It comprises a switchback mechanism 70 serving also as a paper discharge means for supplying to the platen 50, and a paper discharge tray 80 for receiving processed documents.
[0022]
As shown in FIG. 1, the document tray 22 serving as a sheet placing means is attached in a gentle forward tilt posture, and in this embodiment, a maximum A3 size sheet can be placed in the vertical direction.
[0023]
The paper feeding unit 30 includes a feeding roller 33 at the tip of a swing arm 31 pivotally supported by a shaft 32 at a base, and a feeding roller 34 for feeding the fed document to the shaft 32, and a first roller. And a separation pad 35 for blocking two or less sheets.
[0024]
A stopper 36 having a base end coupled to a swing shaft 37 is disposed at an intermediate position between the feeding roller 33 and the feeding roller 34 to prevent the leading edge of the document when the document is placed on the document tray 22. Yes. 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 is also lowered in conjunction with the lowering of the feeding roller 33, thereby opening the passage. It is like that. Note that an empty sensor 38 is provided at the position of the stopper 36 to detect the presence or absence of documents stored in the document tray 22. The feeding roller 33 is swung up and down by a keep solenoid (not shown) and is displaced to a press-contact position and a separation position with respect to the document placed on the document tray 22. Normally, each time the feeding roller 33 is fed out in the mixed loading state. In consideration of the fact that the original bundle is likely to be broken due to the impact of pressing against the original, it keeps pressing against the original until all the originals are fed.
[0025]
Further, the feeding roller 33, the feeding 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, and OW3. Thus, when the DC motor M2 is rotating forward, the one-way clutches OW1 and OW2 are in a connected state, the feeding roller 33 and the feeding roller 34 are rotated in the document feeding direction, and the first registration unit 43 is stopped. Yes. On the contrary, when the DC motor M2 rotates in reverse, the one-way clutch OW3 is connected and OW1 and OW2 are not connected.
[0026]
A main path 40 for sending a document extends beyond the paper supply unit 30. Then, a first resist composed of a pair of rollers 41 and 42 that abuts the leading edge of the document fed to the middle of the main path 40 to adjust the posture of the document and to send the document toward the rotating platen 50. Means 43 are provided. Immediately before the first registration means 43, a first registration space 44 is provided for correcting the posture while allowing the document to be curved.
[0027]
In front of the first resist space 44, a size sensor 45 for detecting the document size by detecting the leading edge and the trailing edge of the document is disposed. A width sensor 46 for detecting the width of the document is disposed on the main path 40 that has passed through the first registration means 43.
[0028]
By the way, the size sensor 45 cannot detect the size unless it detects the leading and trailing edges of the document. However, since the document device 20 is configured compactly, the trailing edge is not sized even when the leading edge of the document reaches a reading position described later. There is a possibility that the reading operation is performed without passing through the sensor 45 and the document size is unknown, and the provision of information to the main device 10 side may be delayed. Therefore, in this embodiment, the size information of the original can be recognized by the control device (not shown) based on the original width information by the width sensor 46. However, for example, the width information of B5Y (actually, the length information of the paper) by the width sensor 46 and the width information of B4T are the same, but since B5Y can obtain true size information immediately after by the size sensor 45. The size information obtained by the width sensor 46 is corrected early.
[0029]
At the end of the main path 40 past the first registration means 43, a rotating platen 50 is disposed as a conveying means having a large-diameter ring shape as shown in FIG.
[0030]
As shown in FIG. 2, the rotating platen 50 is a set of a plurality of ring-shaped rotating bodies coupled to the platen shaft 51 at an appropriate interval. Guides 52A, 52B, and 52C for guiding the document are disposed 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 resist means comprising a pair of rollers 54 and 55 that are in rolling contact with each other, for example, a second resist means 56. As shown in FIG. 1, the second resist means 56 has rolling contact points of rollers 54 and 55 on the circumferential line of the rotary platen 50. This is because each roller of the rotary platen 50 divided as shown in FIG. A plurality of sets are distributed in the middle portion. With such a configuration, it is possible to more reliably hold the document and to accurately feed the sheet.
[0032]
Here, the document handled in the present embodiment, the feeding roller 33 to the feeding roller 34, the first registration unit 43, the rollers of the rotating platen 50, the rollers 54 and 55 of the second registration unit 56, and the like. 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 advances from B5 to A3 with reference to the right side edge. In the figure, T indicates a vertical installation in the traveling direction, and Y indicates a horizontal installation.
[0034]
FIG. 2 shows the center of gravity of each document in a small circle. When these gravity centers are compared with the positions of the rollers below the feeding roller 33, it is known that the rollers 33 and the like are arranged so as to sandwich these gravity centers or at least directly above them. In other words, when each of the rollers 33 or the like feeds a document, it feeds the center of gravity of the roller 33 or directly in contact with the center of gravity. Is held correctly.
[0035]
An upstream end of the guide 52A sandwiching the second registration means 56 is used to hold the leading edge of the document by the roller pairs 54 and 55 of the second registration means 56 and to bend the rear part to correct the posture. A second resist space 57 is provided. In addition, a second registration sensor 58 is disposed immediately before the second registration means 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 the document can be read. Further, a lead sensor 61 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 final end, paper discharge means that also serves as a switchback roller pair, for example, rollers 73 and 74 constituting a paper discharge roller pair 72 are disposed. . Thus, when the paper discharge roller pair 72 acts in the paper discharge direction in FIG. 1, it is referred to as a paper discharge roller pair 72. It will be 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, and the number of document conveyance pulses from the time when the trailing edge of the document is detected by the SBHS sensor 62. And the number of pulses that can be reached by the trailing edge of the document at the switchback branch point is conveyed, and this is used as a timing reference for document stopping during switchback conveyance.
[0038]
It should be noted that pinch rollers 59 and 60 for bringing the document into close contact with the platen surface are in rolling contact with the rotating platen 50.
[0039]
A paper discharge tray 80 for receiving processed documents is provided at the end of the paper discharge roller pair 72. As shown in FIG. 1, the lower surface of the paper discharge tray 80 also serves as a pressing unit that presses the document manually placed on the fixed platen 12.
[0040]
As shown in FIG. 1, a switchback path 71 is provided that supplies a document to the transport path 53 again from the paper discharge roller pair (switchback roller pair) 72 toward the second registration space 57. 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 edge of the document (the leading edge during switchback) to the guide 52C direction. Is arranged. In place of the switching piece 75, a mylar may be provided in the path of the switchback branch point.
[0041]
The switchback mechanism 70 is configured by the switchback path 71, the switchback roller pair 72 (switchback rollers 73 and 74), and the switching piece 75.
[0042]
Here, the position where the switchback (paper discharge) roller pair 72 is disposed will be described.
[0043]
First, there is no particular restriction on the smaller size of the document processed by the document device 20, but the standard paper size is B5Y (Y is the progression) as shown in FIG. (T in the figure indicates vertical placement in the same manner.) The switchback roller pair 72 is disposed at almost the same position as the B5Y size document from the switchback path 71 through the transport path 53 and the leading edge (the trailing edge before the switchback operation) is the rear edge of the document. It is made to rub at 72. With this arrangement, the transport distance of the original is shortened, the processing speed is improved and the transport posture is maintained, and the original device 20 is made compact.
[0044]
Here, a general operation excluding a special configuration and operation as described in the next stage regarding the switchback roller pair (discharge roller pair) 72 will be described.
[0045]
When the leading edge of the original is detected by the SBHS sensor 62 via the conveyance path 53, the paper discharge roller pair 72 starts to rotate in the forward direction (the direction in which the original is fed to the right in FIG. 1). When the document is discharged as it is, the trailing edge of the document is detected by the SBHS sensor 62 and then stopped at a predetermined time T4. On the other hand, in the switchback mode, after the trailing edge of the document is detected by the SBHS sensor 62, it temporarily stops after a predetermined time T5 and then starts to rotate 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, it stops at a predetermined time T6. Thereafter, it is cut off from the pulse motor M3 and is in a freely rotating state, and the document is fed 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 the pulse motor M3 via the clutch CL1, and the discharge (switchback) roller pair 72 is also connected to M3 via the clutch CL2. .
[0047]
Next, a characteristic structure of the switchback roller pair 72 will be described.
[0048]
If the leading edge of the document being switched back is detected by the SBHS sensor 62 and the document size information at that time is B5Y or more, the switchback roller pair 72 is moved while the leading edge of the document 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 indicated by the solid line in FIG. 1 by the excitation of the DC solenoid 76 as the roller separation means, and is indicated by the broken line position. As the rollers 73 and 74 are separated from each other in this way, the leading edge and the trailing edge of the document that rub against each other at this position are smoothly fed without being rubbed strongly.
[0049]
The lower surface of the paper discharge tray 80 serves as a manual document pressing unit, and also serves as a part of a switchback path that holds most of the document during a switchback operation.
[0050]
The document device 20 has a function of performing normal document feeding operation by a control device (not shown) and obtaining size information based on the document width information already described. Further, the following mode selection control is possible.
[0051]
1. Single-sided reading mode (K mode): A document sent out from the document tray 22 as a single 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 discharged to 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)...
[0052]
2-1. (R1 mode)... In this mode, the document is first read on the front side, then switched back to read the back side, and then discharged. That is, the surface priority mode. (See FIGS. 6 to 8)
2-2. (R2 mode)... In this mode, the original is first read on the back side of the original, then switched back and then read on the front side, and then discharged. That is, the back side priority mode. (Refer to the flowcharts of FIGS. 9 to 12)
[0053]
Next, the operation will be described.
[0054]
3 to 5 are flowcharts centering on the operation in the K mode (some parts are common).
[0055]
First, when the power is turned on before the mode is selected and the automatic paper feed button is pressed, the initial setting is made. The initial setting includes the movement of the scanning unit to the reading position on the main body 10 side and the localization. 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). So far, it is common to each mode.
[0057]
Therefore, 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 shown by the broken line in FIG. This is fed out and is fed by the feed 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 document separated and fed is eventually detected by the first registration sensor 47, the DC motor M2 stops after T2 time (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 document that has traveled through the main path 40 is detected by the width sensor 46 (ST11). Detected by the registration sensor 58 (ST12), the pulse motor M3 starts to rotate in the forward direction by this signal, and 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 fed along the conveyance path 53 mainly by the conveyance force of the second registration means 56, and the leading edge is eventually detected by the lead sensor 61 (ST14), and reading is started in step ST18. ON / OFF of the sensor 45 is verified (ST15). If the document is OFF, the information is obtained as a small document of B5Y or smaller (ST16), and if it is ON, information that the document is a large document of B5Y or larger is obtained (ST17).
[0061]
When the document reaches the guide 52B even in the conveyance path 53, the document is fed by the rotation of the rotary platen 50 with the assistance of the pinch roller 59.
[0062]
The document is read and sent to a guide 52C that also serves as a paper discharge path. The leading end is detected by a paper discharge (switchback) sensor 62 (SBHS) (ST19), the clutch CL2 is turned on by this signal, and the paper discharge (switchback) roller pair 72 starts to rotate in the forward direction (original discharge direction). (ST20). Eventually, the trailing edge of the document passes through the SBHS sensor 62, and when the sensor is turned off, the clutch platen 50 and the second registration means 56 are stopped when the clutch CL1 is turned off. At the same time, the timer T4 is started (ST21, 22). Then, the pulse motor M3 stops after T4 time, and the document is discharged to the discharge tray 80 during this time, and the reading process of the first document ends (ST23, 24).
[0063]
Next, an operation mode in the R1 mode in which the surface is preferentially read 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. Until ST and ST are stopped (ST119-122), it is the same as in the case of the K mode in FIGS. However, the difference between the two modes is that the timer T4 in the former is also T5 in step ST121. 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 trailing edge of the original with a pair of discharge (switchback) rollers 72 and to prepare for the next switchback operation. is there.
[0065]
The pulse motor M3 temporarily stops when the timer T5 is turned off (ST123, 124). At this time, the trailing edge of the document has passed at least the switching piece 75. Up to 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 opposite direction, and the paper discharge (switchback) roller pair 72 conveys the document along the switchback path 71 with the rear end so far as the leading edge (ST125). During this time, since the clutch CL1 remains OFF, the rotary platen 50 and the second registration means 56 remain stationary.
[0067]
Eventually, the leading edge of the original (the rear end so far, the same applies hereinafter) is detected by the second registration sensor 58 (ST126), and after a short time T6, M3 is stopped and the clutch CL2 is turned off, and the original is corrected by the second registration means 56. And waits (ST127).
[0068]
After a predetermined timing, the original is sent along the conveyance path 53 by starting the clutch CL1ON and M3 (ST128). Steps ST129 to 131 from the lead sensor ON to SBHSON are the same as ST118 to 120, except that the document itself is the back side reading this time compared to the previous front side reading.
[0069]
Here, the size information (ST116, 117) obtained previously is verified (ST132). If the document size is equal to or larger than B5Y, the DC solenoid 76 is energized, the roller 73 is separated from the roller 74, and the paper discharge (switchback) roller pair 72 is in a state where it can receive the leading edge and the trailing edge of the document simultaneously. (ST133), when the trailing edge of the original is detected by turning off the second registration means 56, the solenoid 76 is turned off and simultaneously the clutch CL2 is turned on (ST134 to 136), and the original is read by the rotary platen 50 and the discharge (switchback) roller pair 72. Then, the paper is discharged to the paper discharge tray 80 (ST137 to 139).
[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 (back surface priority mode) will be described with reference to FIGS.
[0072]
After the start button is pressed, the size information is obtained by the size sensor 45 OFF, and until the leading edge of the document is detected by the SBHS sensor (ST205 to 217), the steps from ST105 to ST119 in the R1 mode and ST05 from the K mode to ST19 are also described. Is almost the same. However, this R2 mode is different in that there is no need to turn on the read sensor ST114 or read step ST118 in the R1 mode.
[0073]
Thus, the processing after the leading edge of the document is detected by the SBHS sensor (ST217) is the same as the processing after step 119 in the R1 mode, and the description thereof is omitted. However, since it is necessary to read the surface side this time after reaching step ST236, the process returns to ST220, the subsequent steps are executed again, and the front and back reading is completed, and the operation ends.
[0074]
The present invention is not limited to the above-described embodiments. For example, the following configurations are possible.
[0075]
(1) In the above-described embodiment, the embodiment of the sheet conveying apparatus is the automatic document feeder for the image reading apparatus. However, when the image forming apparatus is a printing apparatus, the automatic sheet feeding apparatus supplies sheets to the printing apparatus. It is good also as a supply apparatus.
[0076]
(2) Further, as shown in FIGS. 13 and 14, a schematic diagram of the conveyance path (the symbols in the drawings correspond to the symbols in the above embodiment and have the same functions), the document order is placed on the discharge tray 80. As compared with the above-described embodiment, switchback path 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 document, the conveyance of the paper discharge path is repeated three times in order to adjust the document order, and for this third conveyance, the next document must be prevented from being conveyed. The switch-back path means 91 to 95 provided in the above, or the path means 96a to 96d and 97a to 97d dedicated to both sides can prevent the next document from being transported and shorten the document replacement time.
[0077]
(3) Furthermore, in the above embodiment, based on information from the width sensor 46 that detects the width of the sheet provided in the path from the sheet placing unit to the conveyance path, and the size sensor 45 that detects the presence or absence of the sheet, By providing a means to estimate the sheet size, the sheet conveyance distance is short and the trailing edge of the sheet cannot pass through the sensor, so that the sheet size cannot be detected by the sensor ON / OFF interval. Even in the system, at least a standard size sheet size can be detected. For example, it can contribute to the processing operation on the image forming apparatus side corresponding to the feeding sheet. A document tray 22 (sheet placing means) to be conveyed, and a sheet from the document tray 22 is conveyed toward the platen 12 of the image forming apparatus. In the sheet conveying apparatus of the image forming apparatus including the conveying unit 50 including the conveying path 53, a width sensor 46 (sheet width detecting unit) for detecting the width of the sheet in the path to the conveying path 53, and the image reading. 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). In addition to a single-sided document scanning device without a switchback path, or other than document scanning, the document is fixed on the platen by a control device that estimates the size of the sheet being fed. The present invention can also be applied to a general document conveying device that reads in this manner.
[0078]
According to the above embodiment, the following effects can be obtained.
[0079]
(1) A switchback for guiding a sheet discharged from the conveyance path toward the back surface of the sheet pressing means to the entrance side of the conveyance path by switchback conveyance in a limited space between the sheet pressing unit and the sheet placing unit. Since the path is provided, it is possible to carry various sheets such as front-side feeding and back-side feeding to the conveyance path while having a compact configuration.
[0080]
(2) Since the back surface of the sheet pressing means is a 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 switchback roller pair through the conveyance path and is rubbed between the rear portion of the sheet and the switchback roller pair, the roller separation means The front and back of the sheet do not rub against each other.
[0082]
(4) Since the switchback roller pair is also used as a sheet discharge means, the structure can be further simplified and manufactured at low cost.
[0083]
(5) Since an image reading unit for reading image information carried on the sheet by the image forming apparatus is provided in the course of the conveyance path, the image forming apparatus can be used as an automatic document feeder for feeding a document to the image forming apparatus.
[0084]
(6) Since a printing unit for performing printing by the image forming apparatus on the conveyance sheet is provided in the middle of the conveyance path, it can be used as an automatic sheet feeding apparatus for the printing apparatus.
[0085]
(7) Since the registration means for aligning the sheet and feeding timing is provided downstream of the junction point of the conveyance path and the switchback path, the sheet feeding timing is accurately adjusted to improve the conveyance posture. Can be held.
[0086]
(8) Since the registration means is constituted by a pair of rollers that are in rolling contact with each other, and the rolling contact points of the roller pairs are provided on the circumference of the ring-shaped body, the sheet is at least partially in the conveyance path according to the conveyance means. In addition, it is cheaper than the conveying means that is sent by the registration means and is constituted by an expensive large-diameter ring-shaped body, can be easily replaced, and can always maintain a constant sheet clamping force.
[0087]
(9) Since a mode selection control device that can select in advance the priority order of the front and back sides of the sheets supplied to the conveyance path is provided, when used in an automatic document feeder by mode selection, for example, a single-sided original or a double-sided original In addition, the printing apparatus can freely use one side or both sides of the sheet.
[0088]
(10) Since the means for estimating the sheet size is provided based on the information from the width sensor and the lead sensor, at least the standard size sheet size can be detected even in a compact configuration, for example, a feeding sheet This can contribute to the processing operation on the image forming apparatus side 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 an automatic document feeder (sheet conveying device).
FIG. 3 is a flowchart 1 of a single-sided reading operation (K mode).
FIG. 4 is a flowchart 2 of a single-sided reading operation (K mode).
FIG. 5 is a flowchart 3 of a single-sided reading operation (K mode).
FIG. 6 is a flowchart 1 of a surface priority operation (R1 mode) in duplex reading.
FIG. 7 is a flowchart 2 of a surface priority operation (R1 mode) in duplex reading.
FIG. 8 is a flowchart 3 of a surface priority operation (R1 mode) in duplex reading.
FIG. 9 is a flowchart 1 of a back side priority operation (R2 mode) in duplex reading.
FIG. 10 is a flowchart 2 of a back side priority operation (R2 mode) in duplex reading.
FIG. 11 is a flowchart 3 of a back side priority operation (R2 mode) in duplex reading.
FIG. 12 is a flowchart 4 of a back side priority operation (R2 mode) in duplex reading.
FIG. 13 is a side view of a main part of an automatic document feeder (sheet conveying device).
FIG. 14 is a side view of a main part of an 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 transport device)
22 Document tray (sheet placement means)
30 Paper feeding unit (separate feeding means)
46 Width sensor (sheet width detection means)
50 Rotating platen (conveying means)
53 Transport pass
56 Second resist means (resist means)
61 Load sensor
70 Switchback mechanism (paper discharge means)
71 Switchback path
72 Paper discharge (switchback) roller pair (paper output means)
76 DC solenoid (roller separation means)
80 Paper discharge tray (sheet pressing means)

Claims (4)

Sheet pressing means for pressing a sheet placed on the platen of the image reading device against the platen surface;
A sheet placing unit disposed above the sheet pressing unit and configured to stack and receive sheets;
A conveying unit having a conveying path for receiving a sheet from the sheet placing unit from an entrance side, passing a reading position for reading a sheet image, and discharging the sheet from a sheet discharge port;
A switchback path disposed between the sheet pressing unit and the sheet placing unit and guiding the sheet that has passed through the reading position to the entrance side of the conveyance path by switchback conveyance; and
The conveying means includes a rotating platen roller that forms the conveying path on an outer peripheral surface thereof, and a first pinch that is arranged on the upstream side of the reading position in the sheet conveying direction and rolls against the rotating platen roller to convey the sheet. A sheet conveying apparatus of an image reading apparatus, comprising: a roller; and a second pinch roller that is disposed downstream of the reading position in the sheet conveying direction and rolls in contact with the rotating platen roller to convey the sheet. Sheet pressing means for pressing a sheet placed on the platen of the image reading device against the platen surface;
A sheet placing unit disposed above the sheet pressing unit and configured to stack and receive sheets;
The reading plate 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 transport path that passes the position and discharges the sheet from the discharge port;
The sheet that is disposed between the sheet pressing unit and the sheet placing unit and that has conveyed the peripheral surface of the rotating platen roller is switched back to the rotating platen roller peripheral surface on the entrance side of the transport path again. A switchback path to guide,
A sheet conveying apparatus for an image reading apparatus, comprising: The sheet conveying device of the image reading apparatus according to claim 1, wherein a back surface of the sheet pressing unit constitutes a part of the switchback path. A switchback roller pair that is provided in the switchback path and includes a pair of rollers that switchback-convey the sheet that has passed through the reading position; and a roller separation unit that separates the switchback roller pair from each other. The sheet conveying apparatus of the image reading apparatus according to claim 1, wherein the sheet conveying apparatus is an image reading apparatus.

Images