JP3629975B2 - Automatic document feeder, image reading apparatus, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic document feeder, an image reading apparatus, and an image forming apparatus that sequentially and automatically conveys a plurality of documents so that both sides of an image are read.
[0002]
[Prior art]
In recent digital copying machines and the like, an automatic document feeder for automatically conveying a document in order to sequentially read a plurality of documents is provided. Among such automatic document feeders, there is known an automatic document feeder that automatically conveys a document so as to sequentially read the front side and the back side of the document in correspondence with so-called double-sided copying.
[0003]
[Problems to be solved by the invention]
By the way, when reading the front side and the back side of a document as in double-sided copying, it is conceivable to start reading the next document before the previous document is completely read in order to increase productivity. . However, if this is done, the previous document and the next document come into contact with each other or collide with each other, causing interference and causing paper jams.
On the other hand, in order to avoid this, if the reading of the next original is started with a margin after the reading of the previous original is completed, the productivity is lowered and the user cannot be satisfied.
[0004]
The present invention has been made under such a background, and improves the productivity of image reading while avoiding problems due to contact and collision between originals when reading both sides of a plurality of originals. It is an object of the present invention to provide an automatic document feeder, an image reading apparatus, and an image forming apparatus that can perform image processing.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention sends a plurality of originals one by one to the image reading means, sequentially reads the front side and the back side of each original, and discharges the finished originals to the discharge tray. In an automatic document feeder,
First conveying means for conveying the original so as to cause the image reading means to read the original;
First discharge means for retracting a document whose surface has been read by the image reading means into the discharge tray;
A second conveying unit that reversely conveys the document saved in the discharge tray by the first discharging unit to read the back side, and sends the original to the first conveying unit;
A second discharge unit that reversely conveys the document that has been read on the back surface and discharges the original into the discharge tray from above the first discharge unit;
The first transport unit prevents the document discharged into the discharge tray by the second discharge unit from dropping onto the next document saved in the discharge tray by the first discharge unit. And a delay means for delaying the conveyance start timing of the next original by a predetermined time.
[0006]
Preferably, the time delayed by the delay means is a time corresponding to the size in the document transport direction.
[0007]
Similarly, in order to solve the above-described problem, the present invention is configured to send a plurality of originals one by one to the image reading unit, sequentially read the front side and the back side of each original, and read the finished originals to the discharge tray. In the automatic document feeder for discharging
First conveying means for conveying the original so as to cause the image reading means to read the original;
First discharge means for retracting a document whose surface has been read by the image reading means into the discharge tray;
A second conveying unit that reversely conveys the document saved in the discharge tray by the first discharging unit to read the back side, and sends the original to the first conveying unit;
A second discharge unit that reversely conveys the document that has been read on the back surface and discharges the original into the discharge tray from above the first discharge unit;
And a partition member that is provided in the discharge tray and receives the document discharged by the second discharge unit above the document that is evacuated by the first discharge unit.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
1. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic front sectional view of a digital copying machine to which an automatic document feeder according to the present invention is applied. In the digital copying machine DC, an automatic document feeder 12 sequentially takes in a plurality of documents 11 placed on a document tray 10 one by one, and an image on the document 11 is optically read by a scanner 13. Image data relating to the image read by the scanner 13 is sent to the image processing device 14, subjected to predetermined image processing, and then output from the printer engine 15. Thus, the image on the document 11 is copied.
[0009]
R1 is a feed roller that takes in a plurality of documents 11 placed on the document tray 10 into the automatic document feeder 12 one by one. R2 is a registration roller (hereinafter referred to as a registration roller), and sends the document 11 supplied from the feed roller R1 to the scanner 13. The document 11 sent out by the registration roller R2 is read by the scanner 13 while being conveyed on the platen roller R3.
[0010]
R4 is an out-roller that feeds the document 11 that has been read to the discharge tray 16 side. Reference numeral R5 denotes a first exit roller, which discharges the document 11 that has been read on one side, supplied from the out roller R4, onto the discharge tray 16. Reference numeral R6 denotes a second exit roller, which discharges the document 11 fed in reverse from the first exit roller R5 to the discharge tray 16. The document 11 fed in reverse from the first exit roller R5 is the document 11 that has been read on both sides in the duplex copying mode.
[0011]
S1 is a feed sensor installed in the vicinity of the feed roller R1 and detects whether or not the document 11 supplied from the document tray 11 exists. S2 is a registration sensor (hereinafter referred to as a registration sensor) installed in the vicinity of the registration roller R2, and detects whether or not the document 11 is present at the position of the registration roller R2. S3 is an out sensor installed in the vicinity of the out roller R4, and detects whether or not the document 11 is present at the position of the out roller R4. S4 is a double-sided path sensor that detects whether or not the document 11 supplied from the out-roller R4 is in the conveyance path for reading the back side. S5 is a first exit sensor installed in the vicinity of the first exit roller R5, and detects whether or not the document 11 is present at the position of the first exit roller R5. S6 is a second exit sensor installed in the vicinity of the second exit roller R6, and detects whether or not the document 11 is present at the position of the second exit roller R6. S7 is a size detection sensor comprising a plurality of sensors. The size detection sensor S7 can automatically detect the size of the document 11 on the document tray 10 in the conveyance direction.
[0012]
Next, with reference to FIG. 2 and FIG. 3, the document transport path in the single-sided copying mode and the double-sided copying mode will be described. FIG. 2 shows a document transport path in the single-sided copying mode. As shown in the figure, the document 11 is scanned from the document tray 10 through the feed roller R1 and the registration roller R2, and after the surface image is read by the scanner 13 on the platen roller R3, the out roller R4 and the first exit roller It is discharged to the discharge tray 16 via R5.
[0013]
FIG. 3 shows a document transport path in the duplex copying mode. As shown in the figure, at the time of reading an image on the front surface, the single-sided copying mode shown in FIG. 2 is followed through the same path to reach the first exit roller R5 (step S31). Next, at the time of reading the back surface, it turns back in the direction from the first exit roller R5 to the out roller R4, is reversed through the out roller R4, the double-sided path sensor S4, the feed roller R1, and the registration roller R2, and reads the image on the back surface on the platen roller R3. Is carried out and then conveyed to the first exit roller R5 through the out roller R4 (step S32). The document 11 that has been read on both sides is reversed by folding back in the direction from the first exit roller R5 to the second exit roller R6 (the document 11 thus returns to the same direction as the single-sided copy mode), and the second exit. It is discharged to the discharge tray 16 via the roller R6 (step S33).
[0014]
Next, FIG. 4 is a block diagram showing an electrical configuration of the automatic document feeder 12 according to the present invention. In the figure, reference numeral 21 denotes a CPU which controls each part of the apparatus by executing a predetermined control program. A program ROM 22 stores a control program executed by the CPU 21. Reference numeral 23 denotes a RAM, which is used as a work area for the CPU 21. Further, the CPU 21 receives the outputs of the sensors S1 to S7 installed in the transport path of the document 11, and thereby the position of the document 11 in the transport path and the size of the document 11 in the transport direction. Is supposed to be detected.
[0015]
Reference numeral 24 denotes a feed motor which drives the feed roller R1. A constant speed conveying motor 25 drives the registration roller R2, the platen roller R3, the out roller R4, the first outlet roller R5, and the second outlet roller R6 at a constant speed. The constant speed conveyance motor 25 drives the out roller R4 and the first outlet roller R5 in reverse rotation during reverse conveyance before reading the back surface in the double-sided copying mode, and causes the first outlet roller R5 and second outlet roller R6 to rotate during reverse discharge. Drive in reverse. Reference numeral 26 denotes a registration clutch (hereinafter referred to as a registration clutch), which is a clutch for switching on and off the connection between the registration roller R2 and the constant speed conveyance motor 25. The CPU 21 supplies control signals to the feed motor 24, the constant speed conveyance motor 25, and the registration clutch 26, thereby controlling the conveyance of the document 11.
[0016]
Next, the control operation of the CPU 21 in this embodiment will be described with reference to the flowchart shown in FIG. In the figure, when the power is first turned on, the CPU 21 reads the control program from the program ROM 22, loads it into the RAM 23, and executes it. When the start of copying in the double-sided copying mode is instructed on the operation panel (not shown), the control operation shown in the flowchart of the figure is started, and the reading operation of the surface of the document 11 is started first (step S51). That is, first, the feed motor 24 is turned on to drive the feed roller R1, and the document 11 on the document tray 10 is conveyed to the position of the registration roller R2. Next, the constant speed conveyance motor 25 is turned on and the registration clutch 26 is turned on to drive the registration roller R2, the platen roller R3, and the out roller R4, thereby conveying the document 11 at a constant speed and reading the surface image.
[0017]
When the reading of the front side of the document 11 is completed, the back side reading operation is started (step S52). That is, when the document 11 whose front surface has been read passes through the first exit roller R5 to the discharge tray 16, the constant speed conveyance motor 25 is driven in reverse, and the document 11 is fed from the first exit roller R5 to the duplex path sensor S4. Transport in the direction. Then, through the feed roller R1, the document 11 is transported from the first exit roller R5 to the position where it exits the discharge tray 16 as in the case of the front surface, and the image on the back surface is read.
[0018]
When the reading of the back side of the document 11 is completed, the document 11 is then reversed and discharged (step S53). That is, the constant speed conveyance motor 25 is driven in reverse to convey the document 11 from the first exit roller R5 to the second exit roller R6. The CPU 21 determines whether or not the document 11 still remains on the document tray 10 based on the output of the feed sensor S1 immediately after starting the reverse discharge (step S54).
[0019]
If the document 11 does not exist on the document tray 10, the reading operation is terminated. If not, a predetermined standby time is set in the software timer, and the timer timing operation is started (step S55). ). The waiting time set here refers to the time from the start of reverse discharge of the previous document to the start of the next document reading operation, and this time is the size of the document detected by the size detection sensor S7. Is set corresponding to. When this waiting time has elapsed (step S56), the process returns to the above-described step S51, and the operation for reading the surface of the next original is started.
[0020]
The above-described operation is repeated a number of times corresponding to the number of documents 11 placed on the document tray 10, and reading operations are sequentially performed.
[0021]
Next, the operation timing of each part of the apparatus based on the control operation of the CPU 21 described above will be described with reference to the timing chart shown in FIG. In the figure, CNT1 is a control signal that the CPU 21 supplies to the constant speed conveyance motor 25, and at the rising edge, the reverse discharge of the original on which both sides have been read is started (T5 in the drawing). Further, CNT2 is a control signal that the CPU 21 supplies to the registration clutch 26, and the reading operation of the next original is started at the rising edge (T7 in the drawing). The standby time set by the CPU 21 corresponds to the time interval INT between the rise of the control signal CNT1 that is the start timing of the reverse discharge and the rise of the control signal CNT2 that is the start timing of the reading operation of the next original. SOUT2 to SOUT6 are the outputs of the registration sensor S2, the out sensor S3, the double-sided path sensor S4, the first exit sensor S5, and the second exit sensor S6, respectively, and the high level is detected during the period during which the document is detected. The period during which the period is not low is at a low level.
[0022]
Now, while the image of the back side of the previous document is being read, the outputs of the double-sided path sensor S4, the registration sensor S2, and the out sensor S3 sequentially fall from High to Low (T1 to T3 in the drawing). The output of the exit sensor S5 becomes High (T4 in the drawing). When the reading of the back surface is completed, the CPU 21 restarts the control signal CNT1 and drives the constant speed transport motor 25 in reverse (T5 in the drawing). As a result, the reverse discharge of the document that has been read on both sides of the image is started. At this time, the CPU 21 sets a waiting time until the reading of the next original starts in the software timer, and starts the time counting operation.
[0023]
While the previous document is reversed and discharged, the next document is conveyed to the position of the registration roller S2, and waits at this position. As a result, the output of the registration sensor S2 rises from Low to High (T6 in the drawing).
[0024]
When the standby time set in the above-described timer has elapsed, the registration clutch 26 is turned on, thereby starting the reading operation for the next original (T7 in the figure). Thus, when the reading of the front side of the next original is completed, the next original is conveyed to the position of the first exit roller R5 through the out roller R3 and is temporarily retracted in the discharge tray 16. During this time, the outputs of the out sensor S3 and the first outlet sensor S5 sequentially rise from Low to High (T8 and T9 in the drawing). On the other hand, at this time, the original document for which the image reading on both sides has been completed has been reversed and discharged (T10 in the figure), and has already dropped on the discharge tray 16.
[0025]
That is, according to the present embodiment, the waiting time is set at the start of the reverse discharge of the previous document and the reading start timing of the next document is delayed, so that the next document after the reading of the front surface is saved in the discharge tray 16. At this time, the reverse discharge of the previous document is finished and has already dropped on the discharge tray 16. For this reason, the first original document that has been dropped after being inverted and discharged and the next original document that has been saved after reading the front surface come into contact with each other in the discharge tray 16, and as shown in FIG. The previous document that is falling in the tray 16 is not drawn in, or the previous document is not protruded from the discharge tray 16 due to the collision of both documents in the discharge tray 16 as shown in FIG.
In addition, by setting the above-described waiting time to the minimum necessary value corresponding to the document size, the reading start timing of the next document is not unnecessarily delayed, and the productivity of document reading can be improved.
[0026]
2. Second Embodiment Next, a second embodiment of the present invention will be described. FIG. 9 is a schematic front sectional view of an automatic document feeder according to the second embodiment of the present invention. As shown in the figure, in the present embodiment, a partition with a second exit OUT2 from which a document whose back surface has been read is discharged is disposed above the first outlet OUT1 where the document whose front surface has been scanned is saved. Mylar 17 is provided. For example, the end of the mylar 17 is fixed to the inner wall of the discharge tray 16 by screwing or the like.
[0027]
According to such a structure, the originals reversely discharged into the discharge tray 16 from the second outlet OUT2 after the reading of both sides are stacked on the mylar 17, so that the surface of the surface that is retracted into the discharge tray 16 from the first outlet OUT1. It does not come into contact with the next original document that has been read and is not pushed out. Here, the size of the mylar 17 is not necessarily the size on which the original is completely placed. As shown in the drawing, at least one end of the original is placed on the mylar, and the next original discharged from the first outlet OUT1. A size that can avoid interference is sufficient.
Further, according to the present embodiment, it is not necessary to perform transport timing control such as setting a standby time as in the first embodiment.
[0028]
In the above-described embodiments, the case where the present invention is applied to an automatic document feeder provided in a digital copying machine that is an example of an image forming apparatus has been described as an example. It is also possible to apply to an automatic document feeder provided in such an image reading apparatus.
[0029]
【The invention's effect】
As described above, according to the present invention, the back side of the next original is started when the previous original that has been dropped after the reverse discharge and the next original that has been saved after reading the front surface come into contact with each other in the discharge tray. Sometimes, it is possible to avoid the problem of pulling the original document falling in the discharge tray or protruding the original document from the discharge tray due to the collision of both documents in the discharge tray.
Further, the waiting time corresponding to the document size is set as in the invention of claim 2 or 3, or the partition member is provided as in the invention of claim 4 to start reading the next document unnecessarily. Productivity can be improved without delay.
[Brief description of the drawings]
FIG. 1 is a schematic front sectional view showing a configuration of a first embodiment of the present invention.
FIG. 2 is a schematic front sectional view of an automatic document feeder showing a document transport path in a single-sided copying mode.
FIG. 3 is a schematic front cross-sectional view of an automatic document feeder showing a document transport path in a duplex copying mode.
FIG. 4 is a block diagram showing an electrical configuration of the first embodiment.
FIG. 5 is a flowchart showing a control operation of the CPU in the first embodiment.
FIG. 6 is a timing chart showing the operation timing of each part of the apparatus in the first embodiment.
FIG. 7 is a diagram illustrating a state of drawing a document that is avoided by the first embodiment.
FIG. 8 is a diagram illustrating a situation of document collisions avoided by the first embodiment.
FIG. 9 is a schematic front sectional view showing the configuration of a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Document tray 11 Document 12 Automatic document feeder 13 Scanner 14 Image processing device 15 Printer engine 16 Discharge tray 17 Mylar (partition member)
21 CPU (delay means, delay time control means)
22 Program ROM
23 RAM
24 Feed motor 25 Constant speed conveying motor (first and second conveying means, first and second discharging means)
26 cash register clutch (first conveying means)
R1 feed roller R2 registration roller (first conveying means)
R3 Platen roller R4 Out roller (first and second conveying means)
R5 first outlet roller (second conveying means, first and second discharging means)
R6 Second outlet roller (second discharge means)
S1 Feed sensor S2 Registration sensor S3 Out sensor S4 Double-sided path sensor S5 First exit sensor S6 Second exit sensor S7 Size detection sensor (size detection means)

Claims (6)

In an automatic document feeder that feeds a plurality of documents one by one to the image reading unit, sequentially reads the front side and the back side of each document, and discharges the scanned documents to a discharge tray.
First conveying means for conveying the original so as to cause the image reading means to read the original;
First discharge means for retracting a document whose surface has been read by the image reading means into the discharge tray;
A second conveying unit that reversely conveys the document saved in the discharge tray by the first discharging unit to read the back side, and sends the original to the first conveying unit;
A second discharge unit that reversely conveys the document that has been read on the back surface and discharges the original into the discharge tray from above the first discharge unit;
The first transport unit prevents the document discharged into the discharge tray by the second discharge unit from dropping onto the next document saved in the discharge tray by the first discharge unit. An automatic document feeder comprising: delay means for delaying the conveyance start timing of the next document by a predetermined time. The automatic document feeder according to claim 1,
2. The automatic document feeder according to claim 1, wherein the time delayed by the delay means is a time corresponding to a size in the document transport direction. The automatic document feeder according to claim 2,
A size detecting means for detecting the size in the conveyance direction of the document;
An automatic document feeder comprising delay time control means for controlling a time delayed by the delay means based on a detection result of the size detection means. In an automatic document feeder that feeds a plurality of documents one by one to the image reading unit, sequentially reads the front side and back side of each document, and discharges the finished document to the discharge tray.
First conveying means for conveying the original so as to cause the image reading means to read the original;
First discharge means for retracting a document whose surface has been read by the image reading means into the discharge tray;
A second conveying unit that reversely conveys the document saved in the discharge tray by the first discharging unit to read the back side, and sends the original to the first conveying unit;
A second discharge unit that reversely conveys the document that has been read on the back surface and discharges the original into the discharge tray from above the first discharge unit;
An automatic document feed comprising: a partition member provided in the discharge tray and configured to receive a document discharged by the second discharge unit above the document retracted by the first discharge unit. apparatus. An image reading apparatus comprising the automatic document feeder according to any one of claims 1 to 4,
An image reading apparatus further comprising image reading means for reading an image of a document conveyed by the automatic document feeder. An image forming apparatus comprising the automatic document feeder according to any one of claims 1 to 4,
Image reading means for reading an image of a document conveyed by the automatic document feeder;
An image forming apparatus, further comprising: an image forming unit that forms an image corresponding to the image information read by the image reading unit.

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