JP2003104631A - Document carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document carrying device which can avoid defective carrying of a document without fail immediately after the start of the drive of a PS roller when the back face of the document is read out in a device of such constitution that a reversal roller and the PS roller are driven by one motor. SOLUTION: A paper discharge roller 33 depends on the rotation of the motor 70. That is, the motor 70 is rotated in the normal direction to drive the roller 33 in the direction to carry the document 3 in the document discharge direction and is rotated in the reversal direction to drive the roller 33 in the direction to carry the document 3 in a reverse carriage passage 36. When the motor 70 is rotated in the normal direction, the PS roller 32 is also driven in the normal direction to send the document 3 to a document reading position, and when the motor 7 is rotated in the reversal direction, a clutch 71 is released to stop the rotation of the PS roller. In this case, when the reversal rotation of the motor 70 is switched to the normal rotation, the drive force of the motor 70 is transmitted to the roller 33 delayed specified time from the start of the normal rotation of the motor 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DSPF (Duplex Single PDP) used in a document moving type document reading apparatus.
ath Feeder) type document feeder.

[0002]

2. Description of the Related Art Conventionally, there is a document feeder which is placed on a document table of a copying machine and automatically conveys documents from a document tray one by one onto the document table. In such a document feeder, for a double-sided document, the document is conveyed onto the document table and the front side is read, and then the document is switched back and fed again onto the document table. There are also those that allow the back side of the document to be read.

In the above-described document feeder for double-sided documents, a reversing roller capable of reverse driving is used in the document switchback mechanism. Further, a PS (Paper Stop) roller is usually used for aligning the copy image and the document, but since the PS roller includes a stop operation for aligning the timing when the document is sent to the document reading position. However, a control different from that of the reversing roller is required.

When two types of rollers having different operations are controlled by using two different motors,
This leads to an increase in the size of the device and complicates control such as synchronous control, which leads to an increase in cost. On the other hand, JP-A-200
Japanese Unexamined Patent Publication No. 0-89524 discloses a document conveying device in which one motor drives a reversing roller and a PS roller.

In the document feeder of the above-mentioned Japanese Patent Laid-Open No. 2000-89524, the sheet discharge roller, which is a reversing roller, conveys the document in the sheet discharge direction when the motor is driven to rotate in the normal direction as the motor rotates. Forward rotation is performed, and when the motor is driven in reverse, reverse rotation is performed to convey the document to the reverse conveyance path. On the other hand, when the motor is driven in the normal direction, the PS roller is driven in the normal direction to feed the document to the document reading position, and when the motor is driven in the reverse direction, the clutch is released to stop the rotation. Further, the reversing roller is provided with a separating mechanism so that the pair of rollers can be separated from each other.

In the document feeder having the above-mentioned structure, double-sided reading of a document is executed in the following procedure. Both the PS roller and the discharge roller are driven in the forward direction,
The front side of the manuscript is read. At this time, the motor is normally driven. When the front side of the original has been read and the trailing edge of the original has been sandwiched by the discharge rollers, the motor is switched to reverse rotation driving. As a result, the original is conveyed in reverse by the discharge rollers and is conveyed (switched back) to the reverse conveyance path. At this time, the PS roller is in the stopped state due to the action of the clutch, and the leading edge of the document reaches the PS roller. The motor is switched to the normal rotation drive, the PS roller conveys the document in the paper discharge direction, and the back side of the document is read. At this time, the paper discharge rollers are separated from each other by a separating mechanism immediately after the start of the conveyance, so that the conveyance force in the direction opposite to the conveyance direction is not applied to the document. Before the trailing edge of the document is removed from the transport roller, the separated state of the paper discharge rollers is released, and the document is discharged.

[0007]

However, the above-mentioned conventional structure has the following problems.

That is, in the above procedure, the paper discharge roller is
If the rollers are separated before the driving of the PS roller is started or at the same time as the driving is started, the leading edge of the document is not sufficiently pressed against the PS roller and the document is not sufficiently caught in the PS roller. May cause. For this reason, in the above procedure, the separation of the discharge rollers takes a little time (minute time) from the start of driving the PS roller.
It will be implemented after leaving.

At this time, until the paper discharge rollers are separated from each other, both the PS roller and the paper discharge rollers are applied with a conveying force in opposite directions to the original. Normally, the original before being conveyed by the PS roller is bent to a certain extent in the conveying path, and even if the PS roller and the discharge roller give a conveying force in the opposite direction as described above, the influence thereof is not exerted. It is absorbed by the bending.

However, for example, when the original is thick paper, it may not be possible to sufficiently bend the original before the conveyance by the PS roller. In such a case, the conveyance force in the reverse direction from the paper discharge roller immediately after the start of driving of the PS roller may adversely affect the document entrapment of the PS roller, and may cause oblique conveyance or conveyance failure.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to immediately drive a PS roller at the time of reading a back surface in a structure in which a reversing roller and a PS roller are driven by one motor. An object of the present invention is to provide a document feeding device capable of reliably avoiding the document feeding failure in the above.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an original document conveying apparatus of the present invention reverses an original document conveyance path for conveying an original document to an original document reading position and an original document whose one side has been read. And a document reversing / conveying path for conveying the document again to the document reading position, and a reversing roller which is disposed on the downstream side of the confluence of the document reconveying path and the document reversing / conveying path and is capable of forward / reverse driving, In the document conveying device including a PS roller which is arranged before the document reading position and which feeds the document temporarily stopped before the document reading position to the document reading position at a predetermined timing, the reversing roller and the PS roller are provided.
The reversing roller is provided with a single drive source that applies a drive force to both the roller and a clutch that opens and closes a drive force transmission path between the drive source and the PS roller. If the drive source is driven in the reverse direction, the document is transported to the document reverse transport path by the reverse rotation drive.
When the drive source drives in the forward direction, the roller drives in the forward direction to feed the document to the document reading position, and when the drive source drives in the reverse direction, the clutch is released to stop the rotation. The reversing roller is characterized in that, when the driving source is switched from the reverse driving to the normal driving, the driving force is transmitted from the driving source with a delay of a predetermined time from the start of the normal driving of the driving source.

According to the above construction, in the back surface reading operation of the original when the reverse roller and the PS roller are driven by one motor, the reverse roller is reversely driven by the reverse drive of the drive source to switch the original back. After carrying and carrying the leading end of the carrying into the PS roller, the rotation of the drive source is switched to the normal drive.

At this time, the PS roller starts the normal rotation drive with almost no delay with respect to the normal rotation drive of the drive source and sends the original document to the original reading position. The reversing roller drives the normal rotation drive of the drive source. Since the driving force is transmitted from the driving source after a predetermined time delay from the start, the driving is not started immediately.

Therefore, immediately after the forward rotation of the drive source is started, the document receives the driving force from only the PS roller, and the conveyance force in the opposite direction is received by the reversing roller, so that the conveyance failure occurs. It can be avoided.

Further, the reversing roller does not start driving immediately after the start of the normal rotation driving of the driving source, but maintains the state of being stopped with the original sandwiched. Therefore, a sufficient force for pressing the leading edge of the document against the nip portion of the PS roller can be obtained, and the P
It is also possible to prevent conveyance failure due to insufficient pressing against the S roller.

In the document feeder, the drive force transmitting mechanism for transmitting the drive force of the drive source to the reversing roller is driven by the drive gear connected to the drive source and the drive force from the drive gear. It is preferable that a play is provided between the reversing roller and the drive shaft.

According to the above construction, when the drive source is switched from the reverse rotation drive to the normal rotation drive, the drive force is applied from the drive gear to the drive shaft while the drive gear rotates by the play amount. No transmission occurs.

Thus, when the drive source is switched from the reverse rotation drive to the normal rotation drive, the reverse roller receives the driving force after a predetermined time delay from the start of the normal rotation drive of the drive source. Can be easily obtained.

Further, in the document conveying apparatus, the reversing roller has a separating mechanism for separating and contacting the driving roller and the driven roller which constitute the reversing roller. It is preferable that the pair of rollers of the reversing roller be separated from each other during a period from when the driving source starts the normal rotation driving to when the driving force is transmitted to the reversing roller.

According to the above structure, even when the driving force is transmitted to the reversing roller, the driving force of the reversing roller is increased by separating the pair of rollers of the reversing roller by the separating mechanism. Since it is not transmitted to the original, the reverse conveying force of the PS roller and the reverse roller does not act on the original at the same time, and a good original conveying operation can be obtained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. In the following embodiments, the case where the document feeder according to the present invention is applied to an image forming apparatus capable of double-sided printing is exemplified.

A schematic configuration of the image forming apparatus will be described with reference to FIG. The image forming apparatus is such that a document feeder 2 according to the present invention is arranged on a copying machine 1 which is a main body of an image forming apparatus capable of double-sided printing. The image information on both sides of the original 3 can be read by automatically feeding it to the original reading unit 4 of the copying machine 1.

The copying machine 1 accommodates the document reading section 4, the image forming section 5 for printing the image information of the document 3 read by the document reading section 4 on the recording sheet 7, and the recording sheet 7. , And a sheet feeding section 6 for sequentially feeding the stored recording sheets 7 to the image forming section 5.

The original reading section 4 is, as shown in FIG.
A lamp reflector assembly 8 that exposes the surface of the original 3 and a photoelectric conversion element (hereinafter CC
(Refer to D) 11 for reflecting mirrors 9a to 9
c, an optical lens body 10 for forming an image of reflected light from the original 3, and a CCD 11 for converting the reflected light image formed by the optical lens body 10 into an electric image signal. The document reading unit 4 uses the image information of the document 3 read as described above to generate an image processing unit (not shown).
The laser light corresponding to the image signal is converted into an image signal via the semiconductor laser 1 as shown by the solid line in FIG.
2 irradiates the surface of the photoconductor 13 of the image forming unit 5,
An electrostatic latent image is formed on the surface of the photoconductor 13.

The image forming section 5 includes a drum-shaped photoconductor 13
A developing unit 14 that visualizes the electrostatic latent image of the photoconductor 13 with toner, a transfer unit 15 that transfers the visible image of the toner of the photoconductor 13 onto the recording sheet 7, and a surface of the photoconductor 13. A cleaning unit 16 that removes residual toner, a charging unit 17 that charges the photoconductor 13 to a predetermined potential, a fixing unit 18 that fixes the toner image transferred onto the recording paper 7 with heat and pressure, and a photoconductor 13 on the photoconductor 13. A static eliminator (not shown) for removing the residual potential.

When an image forming operation is performed in the copying machine 1 having the above structure, the recording sheet 7 is picked up and conveyed from the sheet feeding section 6 by the pickup roller and passes between the photoconductor 13 and the transfer section 15. (Main transport path) 19
Be transported to. In the recording paper conveyance path 19, the recording paper 7 is once held by the first roller 20 after the conveyance of the recording paper 7 is confirmed by a paper input sensor (not shown). That is, in the first roller 20, the toner image on the surface of the photoconductor 13 is accurately transferred to the recording paper 7 in the image forming section 5, so that the leading end of the image information including the toner image and the leading end of the recording paper 7 are transferred. So that
The recording paper 7 is conveyed to the image forming unit 5 at a predetermined timing, and operates as a PS roller in the image forming unit 5. The recording paper 7 may be picked up and conveyed from a manual feed tray or the like in addition to the paper feed section 6.

The recording paper 7 on which an image has been formed by passing through the recording paper conveyance path 19 is driven by a normal rotation of a second roller (paper discharge roller) 21 that can rotate in the normal direction. Sent to. At this time, if the image forming operation is a one-sided printing process, the recording paper 7 is ejected to the paper ejection unit 23 as it is. However, if the image forming operation is a double-sided printing process, the second roller 21 is reversed with the rear end of the recording paper 7 sandwiched in order to print on the back surface of the recording paper 7. The recording sheet 7 is driven and sent to the recording sheet re-conveying path 24 forming a loop with the recording sheet conveying path 19. Recording paper re-conveyance path 2
4 includes a third sheet for normally assisting the conveyance of the recording sheet 7.
Rollers 22 are provided.

Further, the copying machine 1 is provided with a side cover 25 arranged on the side surface of the recording sheet re-conveying path 24 so as to be rotatable around a shaft 26 as a fulcrum. When a paper jam or the like occurs in the recording paper transport path 19, the side cover 25 is opened and the jam processing is performed.

As shown in FIG. 1, the document feeder 2 includes a document tray 31, a PS (Paper Stop) roller 32, a paper discharge roller (reversing roller) 33, and a paper discharge tray 34, and further serves as a conveyance path. Is a main transport path (document transport path) 35 for transporting the document 3 to the document reading position, and a reverse transport path for transporting the document 3 switched back during double-sided scanning to the main transport path 35 again (document reverse transport path). Has 36. Further, the paper discharge roller 33 has a separating mechanism for separating the roller pair of the driving roller and the driven roller. That is, if the pair of rollers of the discharge roller 33 are separated by the separating mechanism,
Even when the driving force is transmitted to the paper discharge roller 33, the paper discharge roller 33 cannot give a conveying force to the document 3.

On the document tray 31, a plurality of documents to be read are placed. The PS roller 32 is arranged in front of the document reading position in the main conveyance path 35, and
After the document 3 fed into the document 5 is temporarily stopped here, the document 3 is fed to the document reading position at a predetermined timing in order to control the reading start position of the document 3. The paper discharge roller 33 is a roller capable of rotating in the forward and reverse directions, and is used for discharging the read document to the paper discharge tray 34 or sending it to the reverse conveyance path 36. The paper discharge tray 34 is a discharge destination of the document 3 that has been read.

When reading only one side of the original 3 in the original conveying device 2, the original 3 fed from the original tray 31 is picked up by the pickup roller 37 and the paper feeding roller 3.
The original 3 is fed to the main conveyance path 35 by means of 8 and the original 3 is read at the original reading position. The paper feed roller 38 is in contact with the paper feed pad 39, and when two or more originals 3 are simultaneously sent out by the pickup roller 37, the lower original 3 is conveyed by the paper feed pad 39. Is restricted, the originals 3 can be sequentially fed one by one from the top.

Here, the original reading position means the copying machine 1.
Lamp reflector assembly 8 in the original reading section 4
Is the position where the light of is irradiated. That is, the document reading unit 4
A platen glass 27 is provided on the upper surface of the original corresponding to the position of the lamp reflector assembly 8. When the original 3 moves on the upper surface of the platen glass 27 at the original reading position, the original surface is irradiated with light. The lower surface of the original 3 is read. At the original reading position, the position restricting member 40 is arranged above the platen glass 27, and the original 3 has the platen glass 27 and the position restricting member 4.
By passing through 0 and 0, the optimum positional relationship with the platen glass 27 can be maintained. Further, since the height of the document feeding device 2 is regulated by the document pressing member 46, even if the position of the document feeding device 2 fluctuates in the vertical direction, the position regulating member can be maintained so that the distance between the document 3 and the platen glass 27 can be appropriately maintained. 40 is biased downward by a conical coil spring 41.

The original 3 thus read is
The sheet is discharged onto the sheet discharge tray 34 by the transport roller 42 and the sheet discharge roller 33.

When reading both sides of the original 3,
First, the front surface of the original 3 is read by the original reading unit 4 by the same operation as in the above-described single-sided reading. The document 3 whose front surface has been read is sent to the intermediate tray 43 side instead of the paper discharge tray 34 side. That is, the switching gate 44 is arranged on the downstream side of the paper discharge roller 33, and the destination of the document 3 can be switched between the paper discharge tray 34 and the intermediate tray 43 by the position of the switching gate 44.

After that, in order to read the back surface of the original 3,
While the document 3 is sandwiched by the paper discharge rollers 33, the paper discharge rollers 33 are driven in the reverse direction to send the document 3 to the reverse conveyance path 36. That is, on the upstream side of the paper discharge roller 33, the switching gate 45 is provided at the confluence of the main transport path 35 and the reverse transport path 36.
Documents 3 to be sent to the intermediate tray 43.
When the trailing edge of the trailing edge exceeds the leading edge of the switching gate 45, the position of the switching gate 45 is switched and the discharge roller 33 is reversely driven, so that the original 3 is sent to the reverse conveyance path 36.

The original 3 thus sent out to the reverse conveying path 36 is again sent from the main conveying path 35 to the original reading position, and the page order is disturbed if it is immediately ejected after the reading of the back side is finished, so the switch back is carried out again. After performing the above, the sheet may be discharged onto the sheet discharge tray 34.

The document reading process and the image forming process each have two processing modes, the contents of which will be described below.

First, the overall operation of the image forming apparatus according to this embodiment will be described below with reference to the flowchart of FIG.

When a print request for copy processing is issued to the image forming apparatus (S1), the print number, print magnification, recording paper size, etc. are set according to the print request, and the original reading mode is selected (single-sided original).・ Double-sided original),
Then, the printing mode selection (single-sided printing / double-sided printing) is performed (S2).

Thereafter, the document is placed on the document tray 31 (S3), and the document reading process (S4) and the printing process (S7) are processed in parallel. In the original reading process, it is determined whether all the originals have been read (S5) and whether the originals have been discharged to the discharge tray 34 (S6). The reading unit 4 ends one job of the corresponding print request. In the printing process, the presence / absence of next printing is determined (S8), and the paper output unit 23
It is determined whether or not the recording paper has been completely discharged (S9), and the image forming unit 5
Ends one job of the print request. The print request for one job is completed by the end of both processes in which the parallel processing is performed.

Regarding the original reading mode in such a situation, the "single-sided reading process" will be described with reference to the flowchart of FIG.

When the one-sided reading process is selected in the document reading process (S4), it is determined whether the switching gate 44 of the document feeding device 2 is at the home position 1 (S11). At this time, the home position 1 is the same as that shown in FIG.
It is clear from FIG. 1 that the position is indicated by the solid line, and that the document is arranged to be guided to the discharge tray 34 after the reading is completed. When the switching gate 44 is not at the home position 1 in S11, the switching gate 44 is moved to the home position 1 (S19). In this way, the switching gate 4
After the position of No. 4 is determined, the document is picked up and conveyed by the pickup roller 37 (S12), temporarily stopped by the PS roller 32 as described above (S13), and then reconveyed at the document reading timing (S14). ).

The image information of the conveyed document is read by the document reading section 4 (S15). At this time, it is determined whether or not the image information of the read document is input to the memory of the control unit (S16). This determination is based on S2.
It is determined by the number of sheets set for single printing or multi-printing when the number of printed sheets is set in. In S16, memory input is performed when multi-printing is set in S2. When single printing is set in S2, the memory input is not performed, and the image information of the read document is image-processed by the control unit and then transmitted to the semiconductor laser 12 of the image forming unit 5 (S20). While the image processing is being performed in this manner, the document is conveyed to the reversibly rotatable discharge roller 33 via the conveyance roller 42, and the discharge roller 3
The document is rotated to the sheet discharge tray 34 by the rotation of the document discharge sheet 3 and the position of the switching gate 44 (S17). Then, it is determined whether or not there is a next original to be read (S1).
8) If there is no next original, the process ends.

A single-sided original is read by the operations of the original feeding device 2 and the original reading section 4 as described above.
Such one-sided reading process is performed not only when there is image information on only one side of the document, but also when the user's read request is a request to read the one-sided image information even when there is image information on both sides.

Next, the "double-sided reading process" will be described with reference to FIGS.
A description will be given based on the flowchart.

When the double-sided reading process is selected in the document reading process (S4), the double-sided document is picked up and conveyed by the pickup roller 37 (S31) and temporarily stopped by the PS roller 32 as described above (S32). .
Next, it is determined whether the switching gate 44 is in the home position 2 (S33). At this time, the home position 2 is the position shown by the chain double-dashed line in FIG. 1, and the arrangement for guiding the read document to the intermediate tray 43 is shown in FIG.
Is clear from. When the switching gate 44 is not in the home position 2 in S33, the switching gate 44 is moved to the home position 2 (S54). After the position of the switching gate 44 is determined in this way, the document is re-conveyed by the PS roller 32 at the document reading timing (S34).

The image information on the front surface of the original is read by the original reading section 4 (S35). The image information of the front side original read at this time is input to the memory in the control unit (S36). At this time, the image information of the front side document stored in the memory is in a state of being image-processed. While the image is processed and stored as described above, the original is conveyed to the reversible rotatable discharge roller 33 via the conveying roller 42, and the rotation of the discharge roller 33 for discharging the original and the position of the switching gate 44 are performed. And are guided to the intermediate tray 43 (S37). The document guided to the intermediate tray 43 is temporarily stopped with the trailing end of the document in the document transport direction being sandwiched by the paper discharge rollers 33 (S38). This is the first of each double-sided original
"Front side original document reading and conveying process" performed at the time of the second conveying
Is.

Thereafter, the paper discharge roller 33 is moved to the step S37.
The original is conveyed through the reverse conveyance path 36 by performing the rotation opposite to the rotation direction in (S39). The document conveyed through the reverse conveyance path 36 is temporarily stopped by the PS roller 32 (S40), and is conveyed again at the document reading timing (S41). The image information on the back side of the document is read by the document reading unit 4 of the conveyed document (S42).
The image information of the back side document read at this time is subjected to image processing by the control unit, and thereafter, the semiconductor laser 1 of the image forming unit 5 is processed.
2 is transmitted (S43). While the image is processed and transmitted in this manner, the original document is conveyed to the reversibly rotatable sheet ejection roller 33 via the conveyance roller 42, and the sheet ejection roller 33 is conveyed.
The sheet is guided to the intermediate tray 43 by the rotation for discharging the document and the position of the switching gate 44 (S44). The document guided to the intermediate tray 43 has the rear end in the document transport direction at the paper ejection roller 3
It is temporarily stopped in the state of being sandwiched by 3 (S45). More than,
This is the "reverse side document reading and conveying step" that is performed during the second conveyance of each double-sided original.

Further, the temporarily stopped document is conveyed through the reversing conveyance path 36 by the discharge roller 33 rotating in the opposite direction to the rotation direction in S44 (S46). With respect to the document conveyed in this way, it is determined by the sheet detection switch 47 whether the trailing edge of the passing document has passed the sheet detection switch 47 (S4).
7). At this time, when the trailing edge of the original has passed the sheet input detection switch 47 and there is a next original (S48), the next original is picked up and conveyed by the pickup roller 37 (S49), and is temporarily moved by the PS roller 32. It is stopped (S50), and waits until the reading timing comes. Even while the next original is being conveyed, the original having its front and back sides read is conveyed through the conveying path.

As described above, when the originals whose front and back images are read pass through the paper feed detection switch 47 by the above-mentioned conveyance, it is judged whether or not the switching gate 44 is at the home position 1 (S51). At this time, since the switching gate 44 is in the home position 2 in S33, it is moved to the home position 1 (S).
55). In this way, the position of the switching gate 44 is determined. Even during this period, the original after the image is read is conveyed and conveyed to the reversible rotatable discharge roller 33 via the conveying roller 42, and the rotation of the discharge roller 33 for discharging the original and the position of the switching gate 44. And are discharged to the discharge tray 34 (S53). At this time, as described above, the next original document waiting by the PS roller 32 is conveyed again when it is confirmed that the passing original document whose reading has been completed has passed the original document reading position (S52), Is read. Note that the process for such a next original document is S52.
After that, the process proceeds to S33. The above is the "original empty conveyance process" performed as the third conveyance of each double-sided original.

A double-sided original is read by the operations of the original feeding device 2 and the original reading section 4 as described above. As described above, to read a double-sided original, there are three steps of original conveyance: "front side original reading / conveying", "back side original reading / conveying", and "empty original conveying". The reason for carrying out such conveyance is as follows. That is, it can be easily understood that the "front surface original reading / conveying" and the "back surface original reading / conveying" are necessary for reading the original. And
When the position of the switching gate 44 is moved after the "reverse side document reading and conveying" step is finished and the original sheet which has just finished the reverse side reading is discharged to the discharge tray 34, it is discharged when a plurality of original sheets are placed. On the tray 34, the front and back of the originals are out of order and the pages cannot be aligned. In order to eliminate such an inconvenience, a step of "conveying an original document empty" is performed.

Next, the "single-sided printing process" in the image forming section 5 will be described with reference to the flowchart of FIG.

When the one-sided printing process is selected in the printing process (S7), it is first determined whether one image information is printed on one sheet or a plurality of sheets (S61). At this time, when it is determined that one sheet is printed, the image information read as a single copy is not input to the memory, and a step of directly printing the image information subjected to the image processing after the reading is finished is taken. When it is determined that printing is performed on a plurality of sheets, the image information read as multi-copy is input to the memory, and the memory printing step of calling and printing the image information input to the memory in each printing step is performed.

When it is determined in S61 that one sheet is printed in the above selection, the recording sheet is picked up and conveyed by the pickup roller for feeding the recording sheet (S62), and is temporarily stopped by the PS roller 20. (S6
3). Further, the image information of the document read by the document reading unit 4 is written on the photoconductor 13 by using the semiconductor laser 12 after being image-processed by the control unit (S6).
4). The recording paper is re-conveyed by matching the timing of the leading edge of the recording paper with the image information thus written (S).
65). After that, the image information is printed on the recording paper through a transfer process, a fixing process, and the like (S66), and the printed recording paper is discharged to the paper discharge unit 23 (S67).

On the other hand, if it is determined in S61 that plural sheets are printed, the recording sheet is picked up and conveyed by the pickup roller for feeding the recording sheet (S69) as in the case of printing one sheet, and the PS roller is set as described above. It temporarily stops at 20 (S70). Further, the image information read by the document reading unit 4 and stored in the control unit is called,
The image information is written on the photoconductor 13 using the semiconductor laser 12 (S71). The recording paper is re-conveyed by matching the timing of the leading edge of the recording paper with the image information thus written (S72). Thereafter, the image information is printed on a recording sheet through a transfer step, a fixing step, etc. (S7
3) The recording sheet on which printing has been completed is ejected to the paper ejecting section 23 (S74). Then, it is determined whether or not the printing of a plurality of sheets of the requested one image information is completed (S75). If the printing of the requested number of sheets has not been completed, the process returns to S69 and the same processing is performed. If printing for the requested number of sheets has been completed, it is determined whether or not there is next printing (S68), and if there is next printing, S6.
If it does not exist, the process ends.

Single-sided printing is performed by the operation of the image forming section 5 as described above.

Next, the "double-sided printing process" will be described with reference to the flowchart of FIG.

When the double-sided printing process is selected in the printing process (S7), the recording sheet is picked up and conveyed by the pickup roller for feeding the recording sheet (S8).
1) As described above, the PS roller 20 temporarily stops (S
82). The back side image information of the document read by the document reading unit 4 is written on the photoconductor 13 by using the semiconductor laser 12 after being image-processed by the control unit (S8).
3). The recording paper is re-conveyed in accordance with the timing of the leading edge of the recording paper and the back side image information thus written (S84). After that, the back side image information is printed on the recording sheet through a transfer step, a fixing step, etc. (S85), and the recording sheet on which the back side image is printed is discharged to the sheet discharge unit 23 via the reversible rotatable discharge roller 21. It is guided (S86). At this time, the recording paper on which the back side image information is printed is not completely ejected in the paper ejection unit 23, but is temporarily ejected with the rear end portion in the ejection direction of the recording paper sandwiched by the paper ejection rollers 21. Be stopped. The above is the back side printing step, and the back side printing step is performed in parallel with the back side document reading and conveying step of the “double sided reading process” shown in the flowcharts of FIGS. 5 and 6.

After that, the main conveyance path, which is arranged in the conveyance path,
The sub-conveyance path branch claw 60 (see FIG. 2) is moved (S87).
After that, the paper discharge roller 21 rotates in the reverse direction, and the recording paper is guided to the sub-transport path 24 for printing on the front surface (S88).
In the front surface printing step, the recording sheets that have passed through the sub transport path 24 merge with the main transport path 19 and then are temporarily stopped by the PS roller 20 (S89). Further, the front surface image information of the document read by the document reading unit 4 is in a state of being temporarily input to the memory after being image-processed by the control unit. At the time of printing on the front side, the front side image information is called from the memory, and the front side image information is written on the photoconductor 13 by using the semiconductor laser 12 (S9).
0). The recording sheet is re-conveyed in accordance with the timing of the front surface image information thus written and the leading edge of the recording sheet (S91). After that, the front surface image information is printed on a recording sheet through a transfer step, a fixing step, etc. (S9
2) The recording paper is guided to the paper output unit 23 via the paper output roller 21 which is reversibly rotatable (S94). At this time, while the steps S91 to S92 are being performed, the recording sheet that has moved through the main conveyance path / sub-conveyance path branching claw 60 arranged in the conveyance path and has completed printing and has passed through the main conveyance path 19 Is the paper output unit 23
It is guided to the side (S93). The front side printing process described above is performed in parallel with the idle conveyance process of the "double-sided reading process" shown in the flowcharts of FIGS. 5 and 6, whereby the operation time of double-sided printing is minimized. can do.

As described above, double-sided printing is performed by the operation of the image forming section 5.

The difference between the single-sided printing and the double-sided printing in the above description is that single-sided printing can be used for single-sheet printing / plural-sheet printing, but double-sided printing cannot be used for multiple-sheet printing. The reason for this is that the capacity of the memory arranged in the control section and the switchback system of the recording sheet in which a part of the conveyance path of the image forming section 5 also serves as the main conveyance path and the sub-conveyance path are regulated.

In the above description, the operation of reading the original 3 by the automatic conveying mechanism of the original conveying device 2 has been described, but when there is only one original 3 and it is not necessary to use the automatic conveying mechanism. Alternatively, when the material of the original 3 is hard and it is difficult to use the automatic transport mechanism, it is possible to read the original 3 without using the automatic transport mechanism.

Therefore, as shown in FIG. 9, the document feeder 2 is provided so as to be rotatable and openable with respect to the copying machine 1, and the upper surface of the copying machine 1 has a readable document. Three
The table glass 28 corresponding to the maximum size is provided. In this case, the document feeder 2 is opened, the document 3 is placed on the table glass 28 with the reading surface facing down, and then the document feeder 2 is closed. The elastic material 46 a and the white film 46 b are provided on the lower surface of the document feeder 2.
A document pressing member 46 is formed, and the document 3 is pressed against the table glass 28 by closing the document feeding device 2. In this state,
The original 3 can be read by scanning the scanning unit composed of the lamp reflector assembly 8 and the reflecting mirrors 9a to 9c along the original surface.

Now, the driving force transmission mechanism in the document feeder 2 having the above-mentioned structure, which is a feature of the present invention, will be described in detail with reference to FIGS. 10 (a) and (b) to FIG.

As shown in FIGS. 10 (a) and 10 (b), the driving force transmission mechanism roughly drives the discharge roller driving gear 50 for driving the discharge roller 33 and the conveying roller 42. Transport roller driving gear 51, electromagnetic clutch 7
1, a PS roller driving clutch pulley 57, a PS roller driving pulley 52 that drives the PS roller 32, a timing belt 5 that transmits a driving force between the PS roller driving clutch pulley 57 and the PS roller driving pulley 52.
3 and the drive transmission gear 5 for transmitting the driving force between the discharge roller driving gear 50 and the conveyance roller driving gear 51.
It is composed of 5.

In this structure, when the electromagnetic clutch 71 is turned on and off, the rotation of the conveying roller shaft driven by the conveying roller driving gear 51 (up to this point, the operation of the motor is linked to the PS roller driving clutch pulley 57). Transmitted or not transmitted. The discharge roller driving gear 50 is connected to the motor 70 via a motor gear 54 fixed to the drive shaft of the motor 70.

As a clutch for opening and closing the driving force transmission path between the motor 70 as a driving source and the PS roller driving pulley 52 including the driving shaft of the PS roller 32, the electromagnetic clutch 71 is used instead of the electromagnetic clutch 71. Roller drive gear 51
It is also possible to use a one-way clutch inside. In this case, when the motor 70 is driven in the normal direction, the one clutch acts so as to transmit the driving force of the motor 70 to the subsequent driving force transmission path, and when the motor 70 is driven in the reverse direction, the one clutch idles. , The driving force of the motor 70 is not transmitted to the driving force transmission path after the conveying roller driving gear 51. That is, the driving force transmission path between the motor 70 and the PS roller 32 can be opened and closed by the action of the one-sided clutch.

After the reading of the one-sided original or the reading of the back side of the two-sided original, when the original 3 is discharged, the respective members constituting the driving force transmission mechanism in FIG. Rotate. That is, when the motor 70 is rotated in the normal direction, all of the discharge roller driving gear 50, the transport roller driving gear 51, the PS roller driving clutch pulley 57, and the PS roller driving pulley 52 rotate in the normal direction, and the document reading position. The document 3 that has passed through is discharged onto the discharge tray 34. However, at this time, the electromagnetic clutch 71 is in the ON state, and the drive of the transport roller driving gear 51 and the PS roller driving clutch pulley 57 is connected.

When reading the back side of a double-sided original, the discharge roller 33 is temporarily stopped while the rear end of the original 3 is chucked, and then the motor 70 is rotated in the reverse direction to drive the discharge roller. The gear 50 is rotated in the Y direction shown in FIG. By this operation, the original 3 is sent to the reverse conveyance path 36. At this time, the electromagnetic clutch 71
Is in the OFF state, and the PS roller 32 is not rotating. As a result, the leading edge of the original 3 comes into contact with the leading edge of the PS roller 32 and stops, so that the original 3 is moved by the PS roller 32.
It is possible to reliably synchronize the feeding of the document to the document reading position with the operation of the document reading unit 4.

The original 3 at the time of reading the back side conveyed in this way
In the reverse conveyance path 36, some slack occurs. That is, when the document 3 conveyed to the PS roller 32 is skewed called "skew feed", it is temporarily stopped by the PS roller 32, and the "skew feed" is corrected when re-rotated.

In order to move the document 3 stopped in the above state, the motor 70 is rotated in the forward direction and the electromagnetic clutch 56 is turned on, whereby the discharge roller driving gear 50 and the PS roller driving clutch pulley 57 are driven. , And the PS roller driving pulley 52 rotate in the X direction shown in FIG. At this time, the manuscript 3 is printed on the discharge roller 33.
If the state in which the carrying force is received from both the PS roller 32 and the PS roller 32 continues, the carrying force in the opposite direction is given from each of the paper discharge roller 33 and the PS roller 32.
Before the slack of the original document 3 is completely eliminated, the pressure on the discharge roller 33 is released, so that the original document 3 is transferred to the PS roller 32.
The sheet is conveyed to the document reading position by receiving the conveying force only from.

However, as described in the prior art, when the original 3 is thick paper or the like, it may not be possible to cause sufficient slack in the original 3 in the reverse conveyance path 36. In such a case, the slack of the document 3 is completely eliminated immediately after the motor 70 is driven to rotate normally and before the pressure on the discharge roller 33 is released, so that the document 3 becomes the discharge roller 33 and the PS roller 32. In some cases, a conveyance failure such as an oblique feed may occur due to the conveyance force from both. In addition to this, for example, even in a document such as a halftone copy document, which is apt to slip, the PS roller may have a biting defect, and a conveyance defect such as an oblique feed may occur.

In order to accelerate the timing for releasing the pressure on the paper discharge roller 33, the conveyance leading edge of the original 3 is set to P.
The force of pressing against the S roller 32 is weakened, and again in this case, it becomes a factor that causes the conveyance failure of the document 3.

Therefore, in the document feeder 2 according to the present embodiment, the motor 70 is used when reading the back side of a double-sided document.
When the normal rotation is started, the rotation start timing of the paper discharge roller 33 is delayed with respect to the rotation start timing of the PS roller 32. That is, the PS roller 32 starts rotating with almost no delay from the start of rotation of the motor 70, whereas the paper discharge roller 33 starts rotating after a predetermined time from the start of rotation of the motor 70.

In order to obtain the above-mentioned operation, the original feeding device 2
Then, with respect to the paper discharge roller 33, a play is provided in the assembly portion of the paper discharge roller drive gear 50 and the drive shaft of the paper discharge roller 33.

More specifically, in the conventional structure, as shown in FIGS. 11 (a) and 11 (c), the ejection roller driving gear and the ejection roller driving shaft are tightly fitted to each other.
The rotation of the motor 70 is transmitted to the paper ejection roller without delay. On the other hand, in the configuration of the document feeder 2 according to the present embodiment, as shown in FIGS. 11B and 11D, the discharge roller driving gear 50 and the drive shaft of the discharge roller 33 are provided. The fitting in the assembly part is loose.

That is, in the above-mentioned document feeder 2, FIG.
As shown in FIG. 1D, the width of the fitting portion 62a of the bearing hole 62 provided in the discharge roller driving gear 50 is wider than the width of the fitting key 61 of the drive shaft of the discharge roller 33. And the ratio is 2: 2.9. Therefore, the motor 70
When the rotation direction of the paper is switched from the reverse rotation direction to the normal rotation direction, when the motor 70 starts rotating, the discharge roller driving gear 50
Starts rotating immediately, but the gear 50 for driving the discharge roller
In order to transmit the rotation of No. 1 to the paper discharge roller 33 through the fitting key 61 and the fitting portion 62a, the rotation amount of the play provided between the fitting key 61 and the fitting portion 62a is delayed. Occurs.

As described above, by providing a play in the fitting portion of the discharge roller driving gear 50 and the drive shaft of the discharge roller 33, the PS roller 32 starts to convey the original document. The conveyance force of the PS roller 32 is sufficiently transmitted, and it is possible to suppress the conveyance failure. The inventor of the present application is aware that the current device (fitting 0.
1mm), the above-mentioned play of fitting is increased for various originals which are apt to be conveyed poorly (fitting 0.4m).
m, 0.5 mm, 0.8 mm) has been confirmed to reduce conveyance defects.

The document conveying operation at the time of the back surface reading of the both-sides reading operation of the document 3 by the document conveying device 2 having the above-mentioned configuration will be described in detail below with reference to FIGS. Figure 1
Reference numeral 2 denotes the transport position of the leading edge of the document 3 during reverse transport, where the vertical axis represents the position in the transport path and the horizontal axis represents time. Further, FIG. 13 shows the motor 70 and the PS roller 3
2 is a timing chart showing the control operation of the sheet discharge rollers 33 and 33.

[0081] As shown in FIGS. 12 and 13, the back side reading operation of the document 3 is intended is started at time t _1, the motor 70 starts driving reversal at time t _1, the document sheet discharge roller It is conveyed to the reverse conveyance path 36 by the reverse driving of 33. In the conveyance operation of the document 3 by the reverse driving of the paper discharge roller 33, the acceleration section is from time t ₁ to time t ₂ , and the conveyance speed of the document 3 becomes constant after the time t ₂ is exceeded. In addition, in FIG.
Regarding the rotation of the motor 70 and the paper discharge roller 33, + indicates a normal rotation driving state, and − indicates a reverse rotation driving state.

During the conveyance at the constant speed, the paper feed detection switch 47 detects the passage of the leading edge of the original 3 through the conveyance path. The detection timing (pin on) of the document 3 by the sheet detection switch 47 is time t ₃ , that is,
At time t ₃ , the PIN signal, which is the detection signal of the sheet detection switch 47, is switched from OFF to ON. Further, in the document feeder 2, the subsequent time t _{4 to} time t ₈
The operation at 1 is controlled based on the elapsed time from time t ₃ .

Next, from time t ₄ to time t ₅ , there is a deceleration section for stopping the motor 70. Here, FIG.
In the description of No. 3, at the time t ₅ when the motor 70 is stopped, the transport position of the leading edge of the document 3 exceeds the position of the PS roller 32 by ΔL. However, in reality, when the motor 70 is driven in the reverse direction, the PS roller 32 is stopped by the action of the electromagnetic clutch 71, and the leading end of the document 3 is the PS roller 3.
When the nip portion 2 is reached, the leading edge of the original 3 does not move any further. Therefore, the conveyance amount of ΔL is stored as the bending amount of the document 3 in the conveyance path.

Next, at time t ₆ , the motor 70 starts to rotate in the normal direction to start the conveying operation for conveying the original 3 to the original reading position. The PS roller 3
2 indicates that the electromagnetic clutch 71 was switched on at the same time as the motor 70 was stopped at the previous time t ₅ ,
_{In 6} , at the same time as the driving of the motor 70, the normal rotation driving is started without delay.

On the other hand, the paper discharge roller 33 starts driving the motor 70 at time t ₆ (here, the above-mentioned paper discharge roller 3).
3 is composed of a roller pair of a driving roller and a driven roller, and the driving force from the motor 70 is applied only to the driving roller), the above-mentioned discharging roller driving gear 50 and driving of the discharging roller 33. The play in the assembly portion with the shaft causes a delay of Δt to start driving. However, the timing at which the driving of the paper discharge roller 33 is started is set to a timing later than the time t _{7 when} the pressure of the paper discharge roller 33 is released (the driving roller and the driven roller are separated from each other). Therefore, even if the drive of the drive roller of the paper discharge roller 33 is started, the conveying force is not applied to the document 3 by this.

Although not shown in the figure, the pressure release state of the discharge roller 33 is set at the time when the trailing edge of the original 3 is detected by the sheet detection switch 47 (that is, PIN).
It shall be solved when the signal switches from ON to OFF). As a result, the paper discharge roller 33 can discharge the original 3 whose back side has been read to the paper discharge unit.

Therefore, in the document conveying device 2, immediately after the forward rotation of the motor 70 at the time of reading the back side is started, the conveying force in the opposite direction by the sheet discharge roller 33 does not act on the document 3 and the document 3 is conveyed. It is possible to prevent defective conveyance.

Since the pressure of the discharge roller 33 can be released after the drive of the motor 70, that is, the drive of the PS roller 32 is started for a predetermined time, the PS roller 32 is released.
Immediately after the start of the driving of the
It is possible to obtain a sufficient force to press against the nip portion of, and it is possible to prevent conveyance failure due to insufficient pressing of the document 3 against the PS roller 32.

[0089]

As described above, the document conveying apparatus of the present invention has one driving source for applying a driving force to both the reversing roller and the PS roller, and the driving force transmission between the driving source and the PS roller. The reversing roller is provided with a clutch for opening and closing a path, and when the driving source is driven in the forward direction, the reversing roller is driven in the forward direction to convey an original in the sheet discharge direction, and when the driving source is driven in the reverse direction. Performs reverse rotation driving to convey the original to the original reverse conveying path, and when the PS source drives the normal rotation, the PS roller drives normal rotation to send the original to the original reading position, and the drive source drives reverse rotation. In this case, the rotation is stopped by releasing the clutch, and the reversing roller is delayed by a predetermined time from the start of the normal rotation drive of the drive source when the drive source is switched from the reverse rotation drive to the normal rotation drive. Drive from the above drive source Is configured to force is transmitted.

Therefore, the reversing roller and the PS roller are set to 1
Immediately after the forward rotation of the drive source is started during the back side reading operation of the document when driven by two motors, the document receives the driving force from only the PS roller, and receives the conveying force in the opposite direction by the reversing roller. This has the effect of avoiding a problem such as poor conveyance.

Further, since the reversing roller maintains a state in which the document is stopped while sandwiching the document immediately after the forward rotation of the drive source is started, the force for pressing the document leading end against the nip portion of the PS roller is sufficient. In addition, it is possible to obtain the effect described above, and it is possible to prevent the conveyance failure due to insufficient pressing of the document against the PS roller.

In the document feeder, the driving force transmission mechanism for transmitting the driving force of the driving source to the reversing roller is driven by the driving gear connected to the driving source and the driving gear. It is preferable that a play is provided between the reversing roller and the drive shaft.

Therefore, when the drive source is switched from the reverse rotation drive to the normal rotation drive, the drive force is not transmitted from the drive gear to the drive shaft while the drive gear rotates by the play amount. Instead, the effect that the driving force is transmitted to the reversing roller with a predetermined time delay from the start of the normal rotation driving of the driving source can be easily obtained with a simple configuration.

Further, in the document conveying apparatus, the reversing roller has a separating mechanism for separating and contacting the driving roller and the driven roller forming the reversing roller. It is preferable that the pair of rollers of the reversing roller be separated from each other during a period from when the driving source starts the normal rotation driving to when the driving force is transmitted to the reversing roller.

Therefore, even when the driving force is transmitted to the reversing roller, the driving force of the reversing roller is transmitted to the original by separating the pair of rollers of the reversing roller by the separating mechanism. Since there is no more, the conveyance force in the opposite direction by the PS roller and the reversing roller does not act on the original at the same time, and there is an effect that a good original conveyance operation can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention and showing a schematic configuration of a document feeder.

FIG. 2 is an explanatory diagram showing a schematic configuration of an image forming apparatus that is a combination of the original document conveying device and a copying machine.

FIG. 3 is a flowchart showing an operation in a copy mode in the image forming apparatus shown in FIG.

FIG. 4 is a flowchart showing an operation during a single-sided original reading process in the original feeding apparatus shown in FIG.

FIG. 5 is a flowchart showing a part of an operation at the time of a double-sided original reading process in the original conveying apparatus.

FIG. 6 is a flowchart showing a part of an operation at the time of a double-sided original reading process in the original conveying apparatus.

7 is a flowchart showing an operation of a single-sided document printing process in the image forming unit of the image forming apparatus shown in FIG.

FIG. 8 is a flowchart showing an operation at the time of the double-sided document printing process in the image forming unit.

FIG. 9 is an explanatory diagram showing a case in which the document feeder is opened to a copying machine.

10A and 10B are explanatory views showing a driving force transmission mechanism for transmitting the driving force of the motor to the PS roller and the paper discharge roller.

11A and 11B are explanatory views showing an assembly portion of the discharge roller driving gear and the drive shaft of the discharge roller in the driving force transmission mechanism, where FIGS.
And (d) are the configurations according to the present embodiment.

FIG. 12 is an explanatory diagram illustrating a transport position of a transport leading edge of a document during reverse transport.

FIG. 13 is a timing chart showing a control operation of a motor, a PS roller, and a discharge roller during reverse conveyance.

[Explanation of symbols]

2 Document feeder 3 manuscripts 4 Document reading section 32 PS roller 33 Paper ejection roller (reversing roller) 35 Main transport path (original transport path) 36 Reverse transport path (original reverse transport path) 50 Discharge roller drive gear (drive gear) 70 Motor (drive source) 71 Electromagnetic clutch (clutch)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/04 H04N 1/12 Z 5C072 F term (reference) 2H076 BA24 BA42 BA46 BA58 BA63 3F053 BA03 BA12 BA14 LA03 LB02 3F100 AA03 EA02 EA03 EA06 EA14 3F102 AA05 AB01 BA11 BB02 DA08 EA03 EC02 FA07 5C062 AA05 AB02 AB30 AB32 AB46 AC09 AC11 AC71 AD06 AF06 5C072 AA01 BA13 BA20 NA01 NA07 RA05 WA02

Claims (3)

[Claims] 1. A document transporting path for transporting a document to a document reading position, and a document reversing transporting path for reversing a document whose one side has been read and transporting it again to the document reading position. The reversing roller, which is arranged downstream of the confluence point of the original path and the original reversing / conveying path, and which can be driven in the forward / reverse direction, is arranged in front of the original reading position on the original conveying path. In a document feeding device including a PS roller that sends out to a document reading position at the timing of, a driving source that gives a driving force to both the reversing roller and the PS roller, and a driving force of the driving source and the PS roller. A clutch for opening and closing the transmission path is provided, and the reversing roller carries out forward rotation driving to convey the original in the paper discharge direction when the driving source drives forward rotation, and the driving source drives reverse rotation. When the drive source is driven in the forward direction, the PS roller is driven in the forward direction to feed the document to the document reading position, and the drive source is driven. When the reverse drive is driven in the reverse direction, the clutch is released to stop the rotation, and the reverse roller drives the normal rotation drive of the PS roller by the drive source when the drive source is switched from the reverse drive to the normal drive. A document conveying device, wherein a driving force is transmitted from the driving source after a predetermined time delay from the start. 2. A drive force transmitting mechanism for transmitting the drive force of the drive source to the reversing roller, wherein a drive gear connected to the drive source and a drive shaft of the reversing roller to which the drive force is transmitted from the drive gear. The document feeder according to claim 1, wherein a play is provided between the document feeder and the document feeder. 3. The reversing roller has a separating mechanism for separating and contacting a driving roller and a driven roller, which constitute the reversing roller, and the driving source is normally driven when the back surface of the original is read. 3. The document feeder according to claim 1, wherein the pair of rollers of the reversing roller are separated from each other in a period from when the driving force is transmitted to the reversing roller after the start of.