JPH04318873A - Method and device for both side automatic document feeding - Google Patents

Abstract

PURPOSE:To shorten a first printing time and simultaneously, to make post processing easy at the time of carrying trouble, on a both side automatic document feeder composed together with an image forming device. CONSTITUTION:The number of documents Nm which can be lined up and stayed on a carrying path, is set from the size of the document G, and the length of the carrying path including a contact glass (b) and circulating paths (c), (d), and (e), and the documents are sequentially lined up and stayed from the document after being reversed, by the set number of the documents Nm. Then, in the documents lined up and stayed, the back surface of the document at the top position, and the surface of the document newly carried in from a paper feeding part, are alternately read.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a laser printer, L
A double-sided automatic document feeder that is used in combination with an image forming device such as a page printer such as an ED printer, a copier, or a facsimile machine, and is applicable to a double-sided image forming method, especially a device that continuously forms double-sided images on multiple sheets. METHODS AND APPARATUS.

[0002] Hereinafter, the automatic document feeder will be referred to as ADF.
(Auto-Document-Feeder).

0003

2. Description of the Related Art A document is sent from a paper feeder onto a contact glass, where the front side of the document is read.The document is then turned over and sent through a circulation path onto the contact glass, where the back side of the document is read. After reading,
There is a double-sided automatic document transport method for ejecting the document.

[0004] Such a double-sided automatic document conveying method is executed by a double-sided ADF used in combination with an image forming apparatus. As double-sided ADFs used in general image forming apparatuses, techniques disclosed in (1) Japanese Patent Application Laid-Open No. 63-295358 and (2) Japanese Patent Application Laid-Open No. 61-80144 are known.

[0005] The technique (■) is to scan the front surface of a document using a document reading device (hereinafter referred to as a scanner), and then
After the original is reversed in F, the back side of the original is read in the same manner, and then the original is sent out. This technique is called a through mode, in which each document is transported with its front and back sides reversed.

This method has the advantage that the time required to finish the first sheet, that is, the first print time is short. In addition, if a problem such as a jam occurs in the recording paper during the transportation of the recording paper within the image forming apparatus in synchronization with the transportation of the document in the double-sided ADF, the page alignment process of the recording paper after the problem occurs. This process also has the advantage of being relatively easy, as the printing process is completed one by one.

On the other hand, in the technique (2), after the front side of the original is read by a scanner, the double-sided originals are reversed and stacked on the paper feed section, and after the front side of all the originals has been read, the back side of the original is read. , transports the ejected paper. This technique is called a stack mode, in which the originals after being reversed are once placed in a stack.

[0008]

[Problem to be solved by the invention] Regarding through mode■
In the above technique, the next document is started from the paper feed unit after the previous document has been completely read, so that two or more documents do not exist on the conveyance path at the same time.

[0009] The same is true for recording paper in an image forming apparatus; the distance between the preceding recording paper and the following recording paper is maximum, and the paper transport time occupies most of the printing time. In the end, the total printing time becomes longer.

On the other hand, in the technique (2) related to the stack mode, the back side is not read until the front side of all originals has been read, so the first print time increases as the number of originals increases.

[0011] As described above, when the first printing time becomes long, there is a problem in that it is not possible to immediately check the image density of the recording paper and the image when changing the magnification.

In addition, in this stack mode, if the recording paper on the image forming apparatus side encounters trouble during transportation, for example, a so-called jam occurs, after removing the jammed paper, a new recording paper corresponding to the jammed paper is created. It is necessary to perform page alignment with the recorded paper, but the originals that are compatible with jammed paper may not have been ejected to the paper output unit yet, and this post-processing is difficult, especially when there are a large number of originals. There is a problem with becoming.

SUMMARY OF THE INVENTION An object of the present invention is to provide a double-sided automatic document conveying device that can shorten first printing time and easily perform post-processing in the event of conveyance trouble.

[0014]

[Means for Solving the Problem] In order to achieve the above object, in the invention of claim 1, based on the size of the document and the length of the conveyance path including the contact glass and the circulation path, the documents are kept in parallel on the conveyance path. The number Nm of originals to be obtained is set, and the set number Nm of originals are accumulated in parallel on the conveyance path sequentially starting from the inverted original, and then the back side of the original at the leading position among the originals accumulated in parallel is We decided to perform an interleave mode in which reading is alternately performed and reading of the front surface of the document newly fed from the paper feeding unit is performed.

Further, in the invention of claim 2, the number Nm of documents that can be held in parallel on this conveyance path is set based on the size of the document and the length of the conveyance path including the contact glass and the circulation path, and this setting Assuming that the number of sheets is one job, first, the set number Nm of sheets are accumulated in parallel from the original after the inversion, and then the back side is read from the original at the first position among the documents that are accumulated in parallel, Instead of ejecting the final document for one job after reading the back side of the document, a flying mode is used in which a new document is fed from the paper feed section and a process similar to the above is performed.

Further, in the invention according to claim 3, a document conveying belt rotatably stretched over the contact glass, a document feeding section provided at one end side of the contact glass, and a document conveying belt rotatably stretched over the contact glass; A document discharge section provided on one end side, a conveyance path from the paper feed section to the paper feed section via the contact glass, and a document conveyance path provided on the other end side of the contact glass to direct the document conveyance direction. and a document conveyance means provided on the conveyance path for conveying the document or stopping the document conveyance, and controlling these branching means and the document conveyance means to perform interleaving. mode or flying mode.

[0017]

[Operation] A set number of documents that can be arranged in parallel according to the size of the documents is stored in parallel on the conveyance path after front side reading has been completed. When reading the back side of such manuscripts, among these manuscripts stored in parallel,
The document closest to the reading position is sent out, and new documents are replenished at the same time. Alternatively, after all the set number of originals have been sent out, the set number of originals are replenished and sequentially read out.

[0018]

[Example] 1. Description of Modes Regarding the interleave mode, flying mode, through mode, and stack mode related to the present invention, FIG.
The outline will be explained with reference to FIGS. 4 to 4. Interleaved mode (see Figure 1). This mode corresponds to claim 1. In this example, the total number of original sheets is 6, making a total of 12 pages. The set number Nm of documents to be kept in parallel on the conveyance path including the circulation path and the contact glass is set to Nm=4.

In FIG. 1, reference numeral a indicates a paper feeding section, reference numeral b indicates an original reading section composed of a contact glass, reference numerals c, d, and e indicate circulation paths, and reference numeral f indicates a document discharge section after reading. are shown respectively. Note that the reading section and the circulation path are collectively referred to as the transport path. The code G indicates a manuscript.

In this mode, it is assumed that the document is reversed by the reversing means when it is sent out from the reading section b. In this example, reading of both sides is completed in 14 steps from step (1) to step (14).

Step (1): Six originals are placed in paper feed section a. Step (2): The first document is sent from the paper feed section a to the reading section b, and the front side is read. Step (3): The second document is sent to the reading section b, and the front side is read. At the same time, the first document is sent to the circulation path c. Step (4): The third document is sent to the reading section b, and the front side is read. At the same time, the second original is sent to the circulation path c. At the same time, the first document is sent out to the circulation path d.

Step (5): The fourth original is sent to the reading section b, and the front side is read. At the same time, the first one,
Each of the second and third originals is advanced one stage to the adjacent circulation path. From the above steps (1) to (5), reading of the front side (one side) of the four originals has been completed. At the end of this process, the circulation paths c, d, e,
The first, second, and third originals are stopped in this order, and the fourth original is stopped in the reading section b. Step (6): Each original on the transport path is moved to an adjacent position. As a result, the first document is placed in reading section b.
The back side is read. This means that both sides of the first document have been read.

Step (7): Since both sides of the first document have been read, it is turned over and sent to the paper discharge section f. Along with this, the fifth sheet of the original is fed into the reading section b from the paper feed section a, and the front side (single side) is read. There is no movement of documents in each circulation path. Step (8): The document on each conveyance path is moved to the adjacent conveyance path. As a result, the second document reaches reading section b,
The back side is read. This means that both sides of the second document have been read. Step (9): Since both sides of the second original have been read, the second original is reversed and sent onto the first original onto the paper discharge section f. Accordingly, from the paper feed section a to the reading section b,
The sixth original is fed in and the front side (single side) is read. There is no movement of documents in each circulation path.

In this manner, in steps (6) to (9), the reading of both sides and the reading of one side are alternately completed. Step (10): The original on each transport path is moved to the adjacent transport path. As a result, the third document reaches the reading section b, and the back side is read. This means that both sides of the third document have been read. Step (11): Since both sides of the third original have been read, the third original is reversed and sent onto the second original onto the paper discharge section f. Accordingly, the document in each circulation path moves to the adjacent conveyance path. Therefore, the fourth document is sent to the reading section b, and the back side is read.

Step (12): Since both sides of the fourth original have been read, the fourth original is reversed and sent onto the third original onto the paper discharge section f. Accordingly, the document in each circulation path moves to the adjacent conveyance path. Therefore, the fifth sheet of the original is sent to the reading section b, and the back side is read. Step (13): Since both sides of the fifth original have been read, the fifth original is reversed and sent onto the fourth original onto the paper discharge section f. Along with this, the sixth document in the circulation path e is sent to the reading section b, and the back side is read. Step (14): Since both sides of the sixth original have been read, the sixth original is reversed and sent onto the fifth original onto the paper discharge section f. This means that you have finished reading both sides of all manuscripts.

In this way, the manuscript has pages 1, 3, 5, 7, *(2nd page), *9th page, *(4th page).
page), *Page 11, (Page 6), (Page 8), (Page 10)
(page) and (12th) page are read in this order. here,(
) indicates that the back side, that is, an even numbered page, has been read, and means that reading of both sides has been completed. In addition, in the steps marked with *, reading of the back side and front side is performed alternately. In response to these readings, the image forming apparatus also forms an image on the recording paper.

Flying mode (see FIG. 2). This mode corresponds to claim 2. In this example, the total number of original sheets is 6, making a total of 12 pages. The set number Nm of documents to be stopped in parallel on the conveyance path including the circulation path and the contact glass is set to Nm=4.

In FIG. 2, reference numeral a indicates a paper feeding section, reference numeral b indicates an original reading section, reference numerals c, d, and e indicate circulation paths, and reference numeral f indicates a discharge section for the original after being read. Note that the reading section and the circulation path are collectively referred to as the transport path. In this mode, when the document is sent out from the reading section b, it is assumed that the document is reversed by the reversing means. In this example, reading of both sides is completed in 16 steps from step (1) to step (16). Steps (1) to (6) are exactly the same as in the interleaved mode.

Step (7): Since both sides of the first document have been read, it is turned over and sent to the paper discharge section f. Accordingly, the document in each circulation path moves to the adjacent conveyance path. Therefore, the second document is sent to the reading section b, and the back side is read. There is no original in circulation path c. Step (8): Since both sides of the second original have been read, the second original is reversed and sent onto the first original onto the paper discharge section f. Accordingly, the document in each circulation path moves to the adjacent conveyance path. Therefore, the third document is sent to the reading section b, and the back side thereof is read. Circulation path c, d
There is no manuscript.

Step (9): Since both sides of the third original have been read, the third original is reversed and sent onto the second original onto the paper discharge section f. Along with this, the fourth document in the circulation path c is sent to the reading section b, and the back side is read. There are no documents in circulation paths c, d, and e.

Step (10): Since both sides of the fourth original have been read, the fourth original is reversed and sent onto the third original onto the paper discharge section f. Along with this, the fifth sheet of the original is sent from the paper feed section a to the reading section b, and the front side is read. There are no documents in circulation paths c, d, and e. Step (11): The fourth document is moved to circulation path c. Along with this, the sixth document is fed from the paper feed section a to the reading section b, and the front side is read. There are no documents in circulation paths d and e.

Step (12): The fifth original and the sixth original are moved to circulation paths d and c. Step (13): The fifth original and the sixth original are moved to circulation paths e and d. Step (14): The fifth document is sent to reading section b,
The back side is read. The 6th document is in circulation path e.
Move to. Step (15): The sixth document is sent to reading section b,
The back side is read. There are no documents in circulation paths c, d, and e. Step (16): Now that we have finished reading the 6th manuscript,
The sheet is sent out onto the fifth sheet of the document on the sheet discharge section f. This means that you have finished reading both sides of all manuscripts.

[0033] In this way, the manuscript has pages 1, 3, 5, 7, (2nd page), (4th page), (6th page), (8th page). , 9th page, 11th page, 10th page, 12th page
The pages are read in order. Here, a page with parentheses indicates that the back side, that is, an even numbered page, has been read, and means that reading of both sides has been completed. Also, one job (4 sheets) for pages 1 to 8, and 1 job (4 sheets) for pages 9 to 12.
2 sheets). In response to this, an image is formed on the recording paper on the image forming apparatus side as well.

Stack mode (see FIG. 3). Although this mode is not an embodiment of the present invention, it will be described for convenience of comparison with the present invention. Note that this mode can be executed by the apparatus according to the embodiment of the present invention.

[0035] Here, the total number of manuscript sheets is 6, totaling 12 pages. In FIG. 3, reference numeral a indicates a paper feeding section, reference numeral b indicates an original reading section, reference numerals c and e indicate circulation paths, reference numeral d indicates an intermediate stacking section, and reference numeral f indicates a document discharge section after reading. Note that the reading section, the intermediate stack section, and the circulation path are collectively referred to as a transport path.

In this mode, it is assumed that the document is reversed by the reversing means when it is sent out from the reading section b. Here, reading of both sides is completed in 17 steps from step (1) to step (17). Steps (1) to (3) are exactly the same as in the interleaved mode.

Step (4): The first document whose front surface has already been read is sent to the intermediate stack section d. Along with this, the second document whose front side has been read is sent out from the reading section to the circulation path c, and the third document is sent to the reading section b.
A sheet of original is fed from paper feed section a. Step (5): The second document is sent to the intermediate stack section d below the first document. The third manuscript is in circulation path c
At the same time, the fourth document is sent from paper feed section a to reading section b, and its front side is read.

Steps (6) to (9): Step (5)
), new documents are sequentially fed into the reading section b from the paper feed section a, read, and then fed under the preceding document in the intermediate stack section d. Step (10): The first document is sent from the intermediate stack section d to the circulation path e. Step (11): The first document is sent to reading section b,
The back side is read. Also, the second document is sent to the circulation path e.

Step (12): 1 after reading both sides
The th original document is sent to the paper discharge section f. The back side of the second document is read by the reading section b, and the third document is sent to the circulation path e.

Step (13): After reading both sides 2
The th original document is sent out below the preceding original document in the paper discharge section f. The back side of the third original is read by the reading section b, and the fourth original is sent to the circulation path e. Steps (14) to (17): According to step (13) above, new documents are sequentially fed into the reading section b from the circulation path e, read, and then placed under the preceding document in the paper discharge section f. They are sent in. This means that you have finished reading both sides of all manuscripts. In this way, the manuscript has pages 1, 3,
Page 5, Page 7, Page 9, Page 11, (Page 2), (Page 4), (Page 6), (Page 8), (Page 10), (Page 12) The pages are read in order. Here, a page with parentheses indicates that the back side, that is, an even numbered page, has been read, and means that reading of both sides has been completed.

Through mode (see FIG. 4). Although this mode is not an embodiment of the present invention, it will be described for convenience of comparison with the present invention. Note that this mode can be executed by the apparatus according to the embodiment of the present invention. here,
The total number of manuscripts is 6, totaling 12 pages. In FIG. 4, symbol a is a paper feeding section, symbol b is a document reading section, and symbols c, d, and e.
, denotes a circulation path, and symbol f denotes a discharge section for the original after being read. Note that the reading section and the circulation path are collectively referred to as the transport path.

In this mode, it is assumed that the document is reversed by the reversing means when it is sent out from the reading section b. Here, reading of both sides is completed in 33 steps from step (1) to step (33). Process (1)
: Six originals are placed in paper feed section a. Step (2): The first document is sent from the paper feed section a to the reading section b, and the front side is read.

Steps (3) to (6): The first document is sent to the reading section b through the circulation path, and the front side is read. Step (7): The first document is sent to the paper discharge section f, and the second document is sent to the reading section b. Thereafter, the reading of each sheet is completed in the same manner, and the sheets are discharged below the preceding document in the sheet discharge section f. Note that only one document always exists on the conveyance path.

[0044] In this way, the manuscript is
page), page 3, page 4, page 5, page 6, page 7
Page, (page 8), page 9, (page 10), page 11, (
12) The pages are read in order. Here, a page with parentheses indicates that the back side, that is, an even numbered page, has been read, and means that reading of both sides has been completed.

In each of the above modes, the image forming apparatus forms an image in response to reading of a document. Therefore, the differences when comparing each mode with each other are as follows. In interleave mode, the first print time is constant and fast regardless of the number of originals, and the image density and magnification of the recording paper can be checked quickly. Also, recovery from a jam is relatively easy, and the total print time is faster than in stack mode. In flying mode, the first print time is as fast as in interleave mode, and recovery from a jam is relatively easy. The total printing time is slower than the interleave mode but comparable to the stack mode.

[0046] In the stack mode, the first print time is proportional to the number of originals; the larger the number of originals, the longer the time. The longer the first print time, the faster the image density, magnification, etc. on the recording paper can be checked. In addition, the number of sheets of recording paper retained in the machine is large, making it difficult to recover from a jam.

In the through mode, the first print time is fast and recovery from a jam is very easy. However, since two or more sheets of recording paper do not stay in the machine at the same time, the paper gap is large, that is, the number of sheets printed per unit time is small, and the total printing time becomes long.

2. Explanation of a device capable of performing each of the above modes In FIG. 1, the double-sided ADF is located at the top of the image forming apparatus, and is roughly divided into a document feeding section 2, a document transporting section 3, and an intermediate document stacking section 4. , and a document discharge section 5. The transport section 2 is provided above the contact glass 10, the paper feed section 2 is provided on the right side, the paper discharge section 5 is provided on the left side, and the intermediate stack section 4 is provided above the transport section 3.

The paper feed section 2 corresponds to the paper feed section a in the mode description above, and includes a paper feed tray 20 and a pickup roller 2.
1, pickup belt 22, feed roller 23, reverse roller 24, paper feed sensor 25, registration roller 2
6. Consists of a document length detection sensor 27 and the like. The intermediate stack section 4 corresponds to the intermediate stack section d in the description of the mode, and is composed of an intermediate tray 41, an intermediate pickup roller 42, an intermediate pickup belt 43, an intermediate tray sensor 44, an intermediate reverse roller 45, an intermediate feed roller 46, etc. has been done.

The conveying section 3 is composed of a conveying belt 31 stretched between rollers 30, a curved guide 33 connecting the conveying belt and an intermediate tray 41, a conveying roller 40 provided at an intermediate position of the curved guide, and the like. ing. Here, one end of the curved guide 33, a portion closer to the conveyor belt 31, branches into a straight guide 52 that heads toward the paper discharge section 5, as shown in FIG.

[0051] This linear guide 52 includes a paper discharge roller 53,
The paper ejection section 5 is configured together with the paper ejection tray 54 and the like. The branching section has a branching claw 51 as a branching means, and the destination of the document can be switched to the intermediate tray 41 or the discharge tray 54 depending on the inclination of this claw.

On the other hand, the intermediate feed roller 46 and the registration roller 26 are connected through a return path 36 consisting of a guide 34 and rollers 35. The curved guide 33, intermediate tray 41, return path 36, etc. correspond to the circulation path in the description of the mode. The path including the conveyor belt corresponding portion of the contact glass 10 in addition to this circulation path corresponds to the conveyance path in the mode.

In this conveyance path, the conveyance belt 31, conveyance roller 40, intermediate pickup belt 43, roller 35, etc. that contribute to the conveyance of the document serve as document conveyance means for conveying the document on the conveyance path or stopping the conveyance. Configure. As shown in FIG. 7, the originals G are held in parallel on the guide 34 under the control of the original transporting means.

In FIG. 7, the symbol Xo indicates the length of the conveyance path designated as the area in which the documents are held in parallel in this example. In this figure, the length is shown as the length from the intermediate feed roller 46 to the registration roller 26, but the length is not limited to this, and a longer range including the intermediate tray and contact glass may be specified if the document can be retained. can. If the length of the original is L, the distance between the sheets is LA, and the number of sheets staying in parallel on the conveyance path spanning the specified area is n, then
It is possible to hold in parallel up to the number of sheets that satisfies the condition of Xo>nL(n-1)LA.

[0055] An overview of the operation of this device will be explained. First, documents are stacked on the paper feed tray 20 with the first page facing down.

When there is a print command, the image reading section 3 is moved by the pickup roller 21 and the pickup belt 22.
The original is sent out to 2. The submitted manuscript is
The feed rollers 23 and reverse rollers 24 separate the sheets to prevent double feeding, and send them to the registration rollers 26.

The paper feed sensor 25 is provided to detect the presence or absence of a document on the registration rollers 26. When there is a document feed command, the registration roller 26 operates, and the contact glass 1 is moved by the conveyance roller 30 and conveyance belt 31.
The original is transported to 0.

At this time, if the transport mode is interleave mode or flying mode, the length of the original in the transport direction is counted by the original length detection sensor 27,
The number Nm of sheets retained in the conveyance path is set depending on the document length. If the document read at the image reading position 32 on the contact glass 10 is a double-sided document, the document can be moved to the curved guide 33 by moving the branch claw 51 to the broken line position (see FIG. 6) in order to refeed the document for reading the back side. , and is then reversed and sent to an intermediate tray 41 by a conveying roller 40 .

When the document is one-sided, the branch claw 51 is switched to the solid line position (see FIG. 6), and the document is conveyed toward the discharge tray 51 and stacked. The document headed for the intermediate tray 41 is sent out from the intermediate tray 41 if there is a command to feed the back side.

When refeeding paper from this intermediate tray 41, two
When transporting more than one double-sided original, the original to be read next is stopped on the transport path between the intermediate tray 41 and the registration rollers 26, and the number of originals corresponding to the paper size of the original is stopped, and from this stopping position, the contact By conveying the original on glass, the speed at which the original is read can be increased.

3. Description of Control Device In FIG. 8, which explains the control device according to the present invention, the main board 70 is composed of a CPU, RAM, ROM, etc., and various input/outputs are sent and received to and from the main board 70, as shown in FIGS. The control shown in 17 is executed.

Among the information input to the main board 70, there are information from the main sensors such as the paper feed sensor 25, document length detection sensor 27, paper ejection sensor 50, and intermediate tray sensor 44.

Furthermore, control information is outputted to the branch claw solenoid 51S that drives the branch claw 51, the pickup roller solenoid 21S and the intermediate pickup roller solenoid 42S that move the pickup roller 21 and intermediate pickup lower roller 42 up and down, respectively. It has become. Furthermore, a motor 71 serves as a drive source for the entire drive system of this device.
Control information is input to a motor drive board 72 that drives the motor.

In addition, a registration roller clutch 26C for the registration roller 26, and a low clutch 3 for the roller 30.
0C, conveyance roller clutch 40C for the conveyance roller 40,
Feed low clutch 23C for feed roller 23,
Control information is also output to the intermediate feed roller clutch 46C for the intermediate feed roller 46, etc.

The operation panel 73 is a command means for the operator, and is provided with a single-sided original/double-sided original selection button, various mode selection buttons, and print and original reading start command buttons. Power is input to the main board 70 via an AC connector, a noise filter, a power supply unit, etc.

4. Explanation of Control Procedure The control procedure performed by the main board 70 will be explained with reference to FIGS. 9 to 3. 9 and 10 show the main routine, and FIGS. 11 to 17 show the subroutines. First, each subroutine will be explained.

FIG. 11 shows the steps (S10
), if there is a document in the paper feed section, the count value g is incremented by 1 (S37), and the document is transported from the paper feed section to the image reading position 32 (S38). With the document placed at the image reading position, the scanner is driven from below the contact glass to read the document, that is, scan it.

FIG. 12 shows the subroutine of steps (S14), (S19), (S26), and (S36) in FIGS. 9 and 10, in which the branching claw is switched to the paper output tray side (
S44), and the document is ejected to the paper ejection tray (S45). FIG. 13 shows the step (S10) in FIGS. 9 and 10,
The subroutine of (S26) and (S33) is shown, the branching claw is switched to the intermediate tray side (S54), and the original is discharged to the intermediate tray (S55).

FIG. 14 shows the subroutine of steps (S13), (S29), and (S35) in FIGS. 9 and 10. In the flowchart of FIG. 14, first, step (
The subroutine of S40) is executed. This step (
The subroutine of S40) is shown in detail in FIG. 15, in which the count value n is set to zero (S46), and it is determined whether there is room to arrange the documents on the conveyance path (
S37).

[0070] Here, Xo is the conveyance path length, L is the document length,
La indicates the paper distance between the preceding original and the succeeding original remaining in parallel on the conveyance path, and n represents the count value of the sent original. Therefore, in the judgment in step (S47), if there is still room to hold the original, one more sheet of the original is fed and the count value n is incremented by 1 in step (S48); if there is no room to hold the original, Alternatively, the number Ns of documents staying in parallel on the conveyance path at the time when there is no longer room for them to stay there is set to Ns=n (S49).

Next, the process proceeds to (S41) in FIG. 14, and if Ns is zero, the process returns to the main flow, and if it is not zero, it is determined whether there is a document in the conveyance path, that is, if Ns is in the return path 36 as shown in FIG.
It is determined whether there are =n=2 originals (S42)
. If there is no original on the return path, the process advances to step (S39) and the subroutine shown in FIG. 16 is executed.

In FIG. 16, in step (S56), both the registration roller timer Tr and the count value Nt of the number of sheets to be fed are set to zero. Then, in step (S57), the rotation of the intermediate feed roller is started, the preceding document is sent out from the intermediate tray, and the number of sheets to be sent is counted and 1 is added to Nt.

[0073] When this document is sent out from the intermediate tray, the rotation of the intermediate feed roller is stopped (S58).
) (S59). Here, v indicates the document feeding speed. Here, there is room for one more sheet to stay in the return path, so in order to feed one more sheet with a space between sheets La, the rotation of the intermediate feed roller is stopped for the time corresponding to the space between sheets, and the rotation is subsequently carried out. The feeding of the original is stopped, and during that time, the rotation of the roller 35 continues to feed the preceding original.

After that, the rotation of the intermediate feed roller is started again (S60), (S61), and (S57), thereby feeding out the second sheet of the original, resulting in the second sheet as shown in FIG.
The state of document retention is obtained, and then the process returns to the main routine. On the other hand, if it is determined in step (S42) of FIG. 14 that there is a document on the conveyance path, the process moves to step 43,
The subroutine shown in FIG. 17 is executed.

That is, the preceding document in FIG. 7 is sent out onto the contact glass, and at the same time, a new document is sent into the return path from the intermediate tray, and eventually,
The state in which the two originals stay as shown in FIG. 7 is maintained. Next, the main routine will be explained.

If there is an image reading start signal (S2
), resets the counter g that counts the number of originals conveyed from the paper feed tray 20 to the image reading position 32 on the contact glass 10, and the counter h that counts the number of originals sent out from the intermediate tray 41 (S
3).

Next, it is determined whether the original is double-sided or single-sided by checking with the command information from the operation panel 73 (S4), and if it is a single-sided original, the originals in the paper feed tray 20 are sequentially conveyed to the image reading position 32. , eject the paper after reading the image ((S1
7) to (S19)). Explain stack mode.

In the case of the stack mode (S20) in this flow, the number Nm of stacked sheets in the conveyance path determined by the relationship with the image forming apparatus is set for the intermediate tray and the return path. Therefore, the total of the maximum number of sheets stacked on the intermediate tray plus the number of sheets held in parallel on the return path is Nm, and Nm
=Nmax (S21).

If the number of originals in the paper feed section is less than the maximum stack number Nmax of the intermediate tray, the paper feed section 2
0 documents are sequentially conveyed to the image reading position 32, and after the images are read, they are stacked on the intermediate tray 41, and then sent out one after another to read the back side of the documents, and then are discharged to the paper discharge tray 53 ((S8 ) to (S14)).

In this process, as shown in FIG. 15, the number Ns of originals to be retained on the return path from the intermediate tray 41 to the registration rollers is determined based on the original length L ((S
46) to (S49)), as shown in FIG.
A is opened and the document is stopped (S56) to (S61).

[0081] Until there are no originals left in the intermediate tray 41,
The originals of the number of retained originals Ns are transported while being stopped on the transport path (S50) to (S53). If the number of originals in the paper feed section is greater than Nmax, the number of originals is Nm.
The front surface of the document is sequentially read until g=Nm, and stacked on the intermediate tray and return path (S9) to (S11).

After that, the back sides of the documents on the intermediate tray 41 and the return path are sequentially read (S12) to (S14),
If h=Nm (S15), counters g and h are reset (S16) and the next new job is performed. This operation is repeated until there are no more originals in the paper feed tray 20 and intermediate tray 41.

[0083] Interleave mode will be explained. In the case of interleave mode (S22), the document length L is read by the document length detection sensor 27. Since the number of recording sheets retained in the image forming apparatus is set based on this document length, Nm is set accordingly (S23). Note that Nm here is Nm in the stack mode.
, it is the total value of one document retained in the intermediate tray, this retained amount plus the number of parallel retained documents in the return path. The same applies to the flying mode described later.

First, the documents in the paper feed tray 20 up to a=Nm are conveyed in order to the image reading position 32, and after the images are read, they are sent to the intermediate tray 41 and the return path (S24).
~(S27). Next, the originals stacked on the intermediate tray 41 and the return path are transported to the image reading position 32 (
(S28), (S29)), and after reading the back side, the paper is discharged to the paper discharge tray 54 (S30).

After that, the originals are alternately conveyed from the original feed tray 20 and the intermediate tray 41 to the image reading position 32, and the front and back sides of the originals are read alternately ((S28) to
(S30), (S31) to (S33)). This operation is repeated until there are no more originals in the original feed tray 20.

After the document feed tray 20 runs out of documents, the documents in the intermediate tray 41 are sequentially conveyed to the image reading position 32 on the return path, and after the back side of the document is read, the documents are discharged to the discharge tray 53. (S34) to (S36).

[0087] The flying mode will be explained. In the case of the flying mode (S6), first, Nm is set based on the length in the document conveyance direction as in the interleave mode (S7). After setting Nm, one job is performed for Nm originals and the operation is performed. The method of transporting documents is the same as when the number of documents is greater than Nmax in stack mode, and g=
The originals in the original feed tray 20 are held in parallel in the intermediate tray 41 and the return path until Nm (S11), and then,
No new paper is fed, and the originals on the return path and intermediate tray 41 are transported and ejected onto the paper ejection tray 53.

[0088] This operation is repeated until one job is completed and there are no more originals left. The through mode will be explained. In the case of through mode (S5), Nm is set to 1 (S1). The method of transporting documents is to carry out one job as one document in stack mode and flying mode.

The document on the paper feed tray 20 is conveyed to the image reading position 32 , and after the front side is read, it is sent to the intermediate tray 41 , the back side is read, and the document is discharged to the paper discharge tray 53 . This operation is repeated until there are no more originals in the paper feed tray.

[0090]

According to the present invention, first printing time can be shortened and post-processing can be easily performed in the event of transportation trouble.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a document conveyance mode in an interleave mode according to claim 1 of the present invention.

FIG. 2 is an explanatory diagram of a document conveyance mode in a flying mode according to claim 2 of the present invention.

FIG. 3 is an explanatory diagram of how documents are conveyed in stack mode.

FIG. 4 is an explanatory diagram of how a document is conveyed in the through mode.

FIG. 5 is a front view illustrating an embodiment of a double-sided automatic document feeder according to claim 3 of the present invention.

FIG. 6 is an explanatory diagram of branching means forming a part of FIG. 5;

FIG. 7 is a diagram illustrating an example in which two originals are retained in parallel on a conveyance path.

FIG. 8 is a block diagram of a control system capable of implementing a mode according to the method of the invention.

FIG. 9 is a flowchart of a main routine capable of implementing a mode according to the invention.

FIG. 10 is a flowchart of a main routine capable of implementing a mode according to the present invention.

FIG. 11 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

FIG. 12 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

FIG. 13 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

FIG. 14 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

FIG. 15 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

FIG. 16 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

FIG. 17 is a flowchart of a subroutine of a main routine capable of implementing a mode according to the present invention.

[Explanation of symbols]

2 Paper feed section 10 Contact glass 31 Conveyor belt 33 (as document conveyance means)
Curved guide 35 (as a circulation path, conveyance path)
Roller 36 (as document conveyance means) Intermediate tray 51 (as circulation path, conveyance path) Branch claw a (as circulation path, conveyance path) Paper feed section b Contact glass c (as document reading section) Circulation path d Circulation route e Circulation route

Claims (3)

[Claims] Claim 1: This is carried out in synchronization with image formation on recording paper, the document is sent from the paper feed section onto the contact glass, the surface of the document is read there, the document is then reversed, and then passed through a circulation path. In the double-sided automatic document conveyance method in which the document is sent onto the contact glass again, the back side of the document is read there, and then the document is discharged, the size of the document, the length of the conveyance path including the contact glass and the circulation path,
From this, the number of originals that can be kept in parallel on this transport path is N.
m is set, and the set number Nm of documents are accumulated in parallel on the conveyance path sequentially starting from the inverted document, and then the back side of the document at the leading position among the documents accumulated in parallel is read, and the document is fed. A double-sided automatic document conveying method characterized by alternately reading the front side of a document newly sent from a paper section. We decided to use interleave mode. Claim 2: This is carried out in synchronization with image formation on recording paper, the document is sent from the paper feed section onto the contact glass, the surface of the document is read there, the document is then reversed, and then passed through a circulation path. In the double-sided automatic document conveyance method in which the document is sent onto the contact glass again, the back side of the document is read there, and then the document is discharged, the size of the document, the length of the conveyance path including the contact glass and the circulation path,
From this, the number of originals that can be kept in parallel on this transport path is N.
m, and with this set number of sheets as one job, first, the set number Nm of sheets are accumulated in parallel sequentially starting from the original after being reversed, and then the original at the top position among the documents that are accumulated in parallel is The back side of the document is read from the paper feed section and a new document is sent from the paper feed section and a process similar to the above is performed in place of the final document that takes one job and is ejected after the back side of the document is read. Features a double-sided automatic document transport method. 3. An automatic document feeder configured in combination with an image forming apparatus, comprising: a document feed belt rotatably stretched over a contact glass; and a document feeder provided at one end of the contact glass. a document discharge section provided on the other end side of the contact glass; a conveyance path from the paper feed section to the paper feed section via the contact glass; and a document discharge section provided on the other end side of the contact glass. A branching means for switching the conveying direction of the document to either the conveyance path or the paper discharge section, and a document conveyance means provided on the conveyance path for conveying the document or stopping the conveyance, and these branching means, the document A double-sided automatic document conveying device characterized in that the document conveying method according to claim 1 or the document conveying method according to claim 2 is performed by controlling a conveying means.