JPH0753542B2 - Document feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder, and more specifically, a fed document is transported to a transport stop and the first side of the document is set on a copy machine platen. , After the exposure of the first side is completed, the original is conveyed to the reversing and returning section, the reversing means of the reversing and returning section reverses the original, and the original is conveyed again to the conveyance stopping section, and the second side of the original is placed on the platen. The present invention relates to a document feeder that is set.

2. Description of the Related Art Conventionally, in order to facilitate copying of double-sided originals,
When the two-sided original is fed to the original feeding device, the feeding stop portion feeds the original and sets the first side of the original on the platen.
After the surface copying is completed, the original is conveyed to the reversing and returning unit, the original is reversed by the reversing and returning unit, and the original is conveyed to the conveyance stopping unit again.
There has been proposed an original document feeder in which the second surface is set on the platen.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In such a document transport apparatus, for example, the transport stop unit and the reverse return unit are driven by separate motors, and the document transport speeds in the transport stop unit and the reverse return unit are the same. However, if the speed of the motor is inconsistent, there will be a difference in the document transport speed between the transport stop section and the reversing and returning section, and if the speed of the document receiving side becomes slow, wrinkles will occur on the transported document. There was a problem that it occurred.

Further, when the conveyance stop unit and the reverse return unit are driven by the same motor, the above-mentioned inconvenience due to the variation in the rotation speed of the motor is solved, but the conveyance rollers and the conveyance rollers at the conveyance stop unit and the reverse return unit are eliminated. There is a problem in that a conveyance speed difference occurs due to slippage between the belt and the original, and like the above case, when the speed of the original receiving side becomes slow, the conveyed original is wrinkled.

SUMMARY OF THE INVENTION Therefore, according to the present invention, the supplied original is conveyed to the conveyance stop portion, the first surface of the original is set on the platen of the copying machine, and the original is inverted after the exposure of the first surface is completed. In a document transport device in which a document is transported to the transport stop unit after being reversed by the return unit and the second surface of the document is set on the platen, the document transport device is rotated in the first direction to reverse and transport from the transport stop unit. A conveyance belt that conveys the original conveyed from the reverse return unit onto the platen by rotating the original in the second direction, which is opposite to the first direction, while conveying the original onto the platen; A first driving unit that is driven at a speed; a reversing roller that reverses the document conveyed by the conveyor belt and conveys it again toward the conveyor belt; and a reversing roller that conveys the reversing roller at least by the first driving unit. Second driving means for driving the belt at a first speed higher than a predetermined speed or a second speed slower than the predetermined speed, and detection for detecting that an original has passed through the conveyor belt. Means and a control means for controlling the driving speed by the second driving means to be the first speed until the detection means detects the passage of the original document, and detecting the passage of the original document and then changing to the second speed. It is characterized by having.

Effect In the present invention, when copying both sides of an original, it is detected that the original has passed through the conveyor belt when the original is conveyed from the conveyance stop section of the original conveying apparatus to the reverse return section after the exposure of the first side. The drive speed of the reversing roller is made higher than the drive speed of the conveyor belt until the detecting means detects it, and when the detecting means detects that the document has passed the conveyor belt, the drive speed of the reversing roller is made lower than the drive speed of the conveying belt. The original is conveyed while pulling the original by increasing the driving speed of the conveying means on the upstream side in the conveying direction of the original.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a schematic configuration of an automatic document feeder (2) (hereinafter referred to as ADF) having a sheet feeding section (3). The ADF (2) uses the sheet feeding section (3) for the copying machine (1).
The sheet original (8) installed at the upper end and fed from the sheet feeding section (3) is automatically conveyed to a predetermined position on the original placing glass (4) on the upper surface of the copying machine (1) and temporarily held. In cooperation with the transport stop unit (5), the transport stop unit (5) to be stopped and the sheet document (8) sent out from the transport stop unit (5) after being temporarily stopped are reversed as necessary. It has a reverse return / discharge unit (6) for returning it to a predetermined position on the original placing glass (4) or for directly discharging it without inverting it.

The sheet feeding unit (3) receives a stacked sheet document (8) on a document tray (7) mounted so as to project outside the copying machine (1) on a sheet transport belt (9), and a transport stop unit. Delivery to (5). On the conveyor belt (9), the reverse handling belt (10) facing the end in the conveyor direction (a).
Is provided, and the stacked sheet document (8) about to be fed to the conveyance stop portion (5) is sorted by reverse rotation sorting,
Only one sheet of original document (8) in contact with the transport belt (9) is sent to the transport stop (5).

The transport stop unit (5) receives the sheet document (8) sent from the sheet feeding unit (3) in the receiving path, temporarily stops it by the entrance stopper (11), and after adjusting the leading end position and timing adjustment. , Transport roller (13) and transport roller pair (14)
Drive the sheet document (8) in the transport direction (a). Further, by rotating the drive roller (15) and the idle rollers (18a), (18b), (18c), (18d), and (20) stretched endlessly, the endless conveyor belt (21) rotates in the sheet direction. The original (8) is sent out onto the original placing glass (4), stopped at a predetermined exposure position for a required exposure time corresponding to the number of copies, and after the exposure is finished, it is reversed and returned by a conveyor belt (21) and a driving roller (16). It also sends it to the discharge section (6).
The drive roller (15) that drives the conveyor belt (21) and the drive roller (16) that sends out the sheet original (8) to the reversing / returning and discharging section (6) are driven by the same belt conveyor motor (M ₁ ). The belt conveying motor (M ₁ ) is capable of forward and reverse rotations, and conveys the document (8) in the direction of arrow (a) during normal rotation and in the direction of arrow (b) during reverse rotation.

The reverse return / discharge unit (6) reverses the first position where the received sheet document (8) is directly discharged onto the document discharge tray (17) and the received document (8), and the conveyance stop unit (6) is turned on again. 5) A movable switching claw (19) which is movable to a second position, and drive rollers (22) and (23) and idle rollers (which are pressed against the drive rollers (22) and (23) respectively. 22a), (22b), (23a), (23b) and the sheet original (8) is a double-sided original, the switching claw (19) is set to the second position (the position shown in FIG. 1). The sheet document (8) is moved from the lower conveyance path (24) to the upper conveyance path (25) and inverted by driving the driving rollers (22) and (23) in the clockwise direction. Send to Department (5). Also,
When the sheet original (8) is to be copied on only one side, the switching claw (19) is rotated counterclockwise so that the lower conveyance path (24).
The sheet original is closed by closing the passage between the upper conveyance path (25) and the upper conveyance path (25) and forming a passage to the discharge tray (17) (that is, by arranging the switching claw (19) at the first position). Eject (8) from lower transport path (24) to discharge tray (17)
To discharge. The drive rollers (22) and (23) are driven by the same reversing motor (M ₂ ).

Further, the sheet original document (8) reversed by the reverse return / discharge unit (6) and sent to the conveyance stop unit (5) is driven in reverse by the driving rollers (16) and (15) of the conveyance stop unit (5). Due to
It is conveyed in the direction of the arrow (b) and stopped at the predetermined position. In this way, after the required exposure time corresponding to the number of copies is stopped, the drive rollers (16) and (15) are again driven in the forward direction to be conveyed to the reverse return / discharge section (6). At this time, as will be described later, the original is inverted again as described above by the switching claw (19) taking the second position, and the original stop portion (5) is reached.
After being conveyed up to, the drive rollers (16) and (15) are forwardly driven to be sent to the reverse return / discharge section (6), and the switching claw (1
9) is discharged to the discharge tray (17) by taking the first position. By the above operation, the pages of the discharged originals are aligned.

FIG. 2 is a control circuit diagram for controlling the operation of the embodiment of the present invention. The first CPU (50) is a microcomputer that controls the copying machine (1), and the operation of the first CPU (50) is generally known, and a detailed description thereof is omitted here. Second CPU (5
1) is a microcomputer that controls the ADF (2). The open / close detection switch (PSW) of the ADF (2), the start switch (SSW) of the ADF (2), and the passage sensor (30) are connected to the input port of the second CPU (51). In addition,
As shown in FIG. 1, the passage sensor (30) is provided immediately after the drive roller (16) of the conveyance stop portion (5), detects the presence or absence of a document, and detects the conveyance state of the document. The output port includes a drive circuit (52) for a sheet feeding motor (not shown) that drives the conveyor belt (9) of the sheet feeding unit (3), drive rollers (15), (16) for the conveyance stop unit (5). ) Etc. drive circuit (53) for the belt transport motor (M ₁ ), drive rollers (22) for the reversing section (6), reversing motor (M ₂ ) for driving (23)
It is connected to the drive circuit (54). The second CPU (51) is
Since it operates under 1CPU (50), data sampling and output clock SCK of the 1st CPU (50), interrupt signal output PCO,
Output terminal SOUT and data input terminal SIN are
It is connected to the clock SCK, the interrupt signal input INT, the data input terminal SIN and the data output terminal SOUT of the second CPU (51).

As described above, the first and second CPUs (50) and (51) associated with the copying machine (1) and the ADF (2) exchange signals with each other, and the flowcharts of FIGS. The process shown in is executed.

FIG. 3 is a flowchart showing a processing procedure of control executed by the second CPU (51).

In step (S ₁ ), the second CPU (51) is initialized, and in step (S ₂ ), a main timer that defines the length of one routine is set. In step (S _3), ADF operation flag (F _0), it is determined whether "0", the process proceeds in the case of "0" step (S _4), in the case of "1" step (S ₄₎ The process is skipped and the process proceeds to step (S ₅ ). Here, the ADF operation flag (F ₀ ) is a flag that indicates the operation state of the ADF (2), where “0” indicates that the ADF (2) is not operating, and “1” indicates that the ADF (2). 2) indicates that it is in operation. In step (S ₄ ) AD
Calls the F start subroutine and executes the input and output of the second CPU (51). In step (S ₅ ), it is determined whether the document start flag (F ₁ ) is “1”,
If "1", the flow proceeds to step (S _6), in the case of "0" skip the process of step (S _6), the flow advances to step (S _7). Here, the document start flag (F ₁ ) is a flag indicating whether or not document feeding is possible. When it is “0”, document feeding cannot be started, and when it is “1”, document feeding can be started. It is possible. In step (S ₆ ), the original feeding subroutine is called to start feeding the sheet originals (8) stacked on the original tray (7), and the first side of the sheet originals (8) is placed. It is conveyed to a predetermined position on the glass (4). Thereafter, the first surface of the copying is completed, the step (S _7), the _{(S 8), (S 9} ), document reversing discharge start subroutine, document reversing subroutine, sequentially calls the document discharge subroutine. These subroutines will be described in detail later, but here, the sheet document (8)
If the original is a double-sided original, the sheet original (8) is inverted by the reverse return / discharge unit (6), the second surface is stopped at a predetermined position of the original placing glass (4) for a required time, and then inverted again. In the return / discharge unit (6), the document is inverted and discharged to the discharge tray (17), or in the case of a single-sided document, the document (8) is directly discharged to the discharge tray (17). Step In (S ₁₀₎ calls the communication subroutine performs transmission and reception of data to the copying machine (1). In step (S ₁₁ ), the main timer set in step (S ₂ ) is waited for, and when it is finished, one routine is ended and the process returns to step (S ₂ ) to repeat the above-mentioned processing again.

FIG. 4 is a flowchart showing the details of the original document reverse discharge start subroutine.

In step (S _12), to determine whether ADF standby flag (F ₂₎ is "0", when "0", the step (S
Proceed to _13), in the case of "1", the flow goes to step (S _8). Here, the ADF standby flag (F ₂ ) is a flag that indicates the state of each motor of ADF (2). When it is “0”, each motor of ADF (2) is stopped, and when it is “1” Indicates that each motor is operating. Step (S ₁₃₎ the copy end signal to determine whether it is "1", the flow proceeds to the case of "1" step (S _14), in the case of "0", the processing proceeds to a step (S _8). Here, the copy end signal means that when the copy of the set number of sheets on the surface of the sheet document (8) is completed, the first CPU
This signal is output from the (50) to the second CPU (51). In step (S ₁₄ ), it is determined whether the mode is the double-sided original mode. If the mode is the double-sided original mode, the process proceeds to step (S ₁₅ ), the reverse flag (F ₄ ) is set to “1”, and the mode is not the double-sided original mode. proceeds to step (S _16), the discharge flag (F ₅₎ is "1". Here, the double-sided original mode is a mode selected by a switch (not shown) provided in the ADF (2) or the copying machine main body, and when this mode is selected, the first original of the sheet original (8) is selected. After the surface copying is completed, the original (8) is reversed by the reverse return / discharge unit (6) to copy the second surface. Further, the inversion flag (F ₄ ) is a flag indicating whether or not the inversion processing mode is set,
When it is "0", it is not the reversal processing mode, and when it is "1", it is the reversal processing mode. Further, the discharge flag (F ₅ ) is a flag indicating whether or not the discharge processing mode is set,
When it is "0", it is not the discharge processing mode, and when it is "1", it is the discharge processing mode.

5 (a) and 5 (b) are flowcharts showing the details of the original reversing subroutine, and FIG. 7 is a time chart of the control performed by the original reversing subroutine in the case of a double-sided original.

Step (S _17), in the (S _18), or discharge flag (F ₅₎ is whether "0", the inversion flag (F ₄₎ to determine whether "1". Here, the discharge flag (F ₅ ) is “0”
And the reversal flag (F ₄ ) is “1”, that is, the reversal processing mode is not the discharge processing mode, and the second surface copying is performed after the first surface copying of the document (8) is completed. If so, proceed to steps (S ₁₉ ) and (S ₂₀ ) where the ADF standby flag (F ₂ ) is set to “1” and the belt transport motor (M ₁ ) is rotated at the transport speed (V ₁ ) in the forward direction. Yes (time in Fig. 7)
t ₁ ). The transport speed (V ₁ ) is the transport speed (V ₂ ) described later.
If, set so that the relationship of V _2> V ₁ is satisfied. Further, the step (S _17), the (S _18), if the discharge flag (F ₅₎ is "1" or inversion flag (F ₄₎ is "0", i.e.,
If the discharge processing mode or the reverse processing mode is not set, the process proceeds to step (S ₉ ). In step (S _21), when the passing sensor (30) detects the leading edge of the document (8), the flow advances to step (S _22), determines the operating state of the reverse motor (M ₂₎ in step (22) If the reversing motor is OFF, the reversing motor (M ₂ ) is driven at the conveying speed (V ₂ ) (where V ₂ > V ₁ ) in step (S ₂₃ ) (time in FIG. 7).
t ₂ ). Further, when the leading edge of the document (8) is detected by the passage sensor (30) in step (S ₉ ) and it is determined that the reversing motor (M ₂ ) is in the ON state in step (S ₂₂ ) (Fig. 7). Middle time
t ₄ ) proceeds to step (S ₂₄ ). Step (S ₂₄₎ to ON switching solenoid not shown in to position switching claw (19) to the second position. Furthermore, if the passage sensor (30) has not detected the leading edge of the document (8) in step (S ₂₁ ),
Step _{(S 22), (S 23} ), skipping the process in (S _24), the flow advances to step (S _25). In step (S _25), to determine whether the belt conveyor motor (M ₁₎ is being reversed, the if in reverse step (S _26), if it is in forward rotation to step (S ₃₉₎ move on. Step In (S _26), passes through the sensor (30) determines whether the detected the trailing end of the document, if you are detected, it stops the reversing unit motor (M ₂₎ in step (S ₂₇₎ Step (S ₂₈ )
To turn off the switching solenoid to position the switching pawl (19) to the first position, and set the timer (T ₁ ) to stop the belt transport motor (M ₁ ) in step (S ₂₉ ) (Fig. 7). medium time (t _5)). In the case where not detected the leading edge of the document in step (S ₂₆₎ skips the process of step _{(S 27) ~ (S 29} ), the flow advances to step (S _30). Step In (S ₃₀₎ to determine the end of the timer (T ₁₎ which is set at step (S _29), the timer if (T ₁₎ is completed (S ₃₁₎
If not, go to step (S ₉ ). When the end of the step timer (S ₃₀₎ (T ₁₎ is determined, the step (S _31), and OFF reversal of (S _32), the (S _33), the belt conveyor motor (M ₁₎ (the 7 Time t ₆ ), ADF
The standby flag (F ₂ ) and the inversion flag (F ₄ ) are reset to “0”. In step (S _34), the document flag (F _3), it is determined whether "0", if "0",
That is, a surface mode, if not performed yet copying of the second surface, and set the document flag (F ₃₎ to "1" in step (S _35), the at step (S ₃₆₎ 1CP
A copy start signal is output to U (50) and the second side is copied. In step ( _S34 ), the original flag (F
_{If 3)} is set to "1", i.e., a rear surface mode, if the copying of the second surface is completed, step (original flag in S ₃₇₎ (F ₃₎ to "0" Reset the discharge flag (F ₅ ) to “1” in step (S ₃₈ ).
Set to.

Moreover, a belt conveyor motor (M ₁₎ is in forward rotation in step (S _25), if the process proceeds to step (S _39), In step (S ₃₉₎ passes the sensor (30) after the original (8) If the passage sensor (30) detects the trailing edge of the document (8), the forward rotation of the belt conveyance motor (M ₁ ) is turned off in step (S ₄₀ ). In step (S ₄₁ ), a timer (T _P ) for setting the reverse rotation start timing of the belt conveyance motor (M ₁ ) is set (time t _{3 in} FIG. 7).
Further, when the passage sensor (30) has not detected the trailing edge of the document (8), a step (S _40), skipping the process in (S _41), the flow advances to step (S _42). In step (S ₄₂ ), it is determined whether or not the timer (T _P ) has ended. If it has ended, in step (S ₄₃ ), the belt transport motor (M
₁ ) is reversely driven so that it becomes the transport speed (V ₃ ) (time t _{4 in} FIG. 7), and if the timer (T _P ) has not ended, the process of step (S ₄₃ ) is skipped and the step (S ₄₃ ) is skipped. Go to S ₉ ).
Here, the forward rotation conveyance speed V ₁ (direction a), the reverse rotation conveyance speed V ₃ (direction b) of the belt (21) and the conveyance roller (16), and the conveyance roller (22) driven by the reversing motor (M ₂ ). ),
The transport speed V _{2 in} (23) is set so that the relationship of V ₁ <V ₂ <V ₃ is established.

FIG. 6 is a flowchart showing the details of the document discharge subroutine. Step (S _44), in the (S _45), whether the inversion flag (F ₄₎ is "0", discharge flag (F ₅₎ to determine whether "1". Where the inversion flag (F ₄ )
A There "0", and, if the discharge flag (F ₅₎ is "1", i.e., a discharge mode rather than reversal processing mode, when attempting to discharge the original (8), a step (S ₄₆₎ ，
In (S _47), set ADF wait flag (F ₂₎ to "1", to normally drive the belt conveyor motor (M _1). Also,
Inversion flag (F ₄ ) in steps (S ₄₄ ) and (S ₄₅ )
Is “1” or the discharge flag is “0”, the step (S
Go to ₁₀ ). In step (S ₄₈ ), it is determined whether or not the passage sensor (30) detects the leading edge of the document (8). If so, the process proceeds to step (S ₄₉ ), and the reversing motor (M ₂ ) is driven. To do. If the passage sensor (30) does not detect the leading edge of the document (8), step ( _S49 ).
Skip the process of and proceed to step (S ₅₀ ). Step (S
_{In 50} ), it is determined whether or not the passage sensor (30) detects the trailing edge of the document (8).
Step _{(S 51), (S 52} ) the belt conveyor motor (M ₁₎ is driven in the forward direction at, it sets a timer (T ₂₎ for stopping the reverse motor (M _2). Also, step (S ₅₀ )
If the passage sensor (30) does not detect the trailing edge of the document (8) in step 1, the processing in steps (S ₅₁ ) and (S ₅₂ ) is skipped, and the process proceeds to step (S ₅₃ ). Step In (S ₅₃₎ to determine the end of the timer (T _2), if the timer (T ₂₎ has been completed, the step _{(S 54), (S 55} ), (S 56),
At (S ₅₇ ), the reversing motor (M ₂ ) is turned off, the ADF standby flag (F ₂ ) and the discharge flag (F ₅ ) are reset to “0”, and the document start flag (F ₁ ) is set to “1”. Set to.
If the timer (T ₂ ) has not expired in step (S ₅₃ ), steps (S ₅₄ ), (S ₅₅ ), (S ₅₆ ),
The process in (S ₅₇ ) is skipped, and the process proceeds to step (S ₁₀ ).

As described above, in the present embodiment, when copying both sides of the original, when the original (8) is conveyed from the conveyance stop section (5) to the reverse return / discharge section (6) after the exposure of the first side, Reversal return / discharge unit (6) based on the transport speed at the transport stop unit (5)
Transport speed at the same time is high, and it is also the reversing and returning section and the discharging section (6)
When the document (8) is conveyed from the reverse return / discharge unit (6) to the conveyance stop unit (5) after the document (8) is reversed by, the conveyance is stopped at the conveyance speed of the reverse return / discharge unit (6). Since the rotation speed of the belt conveyance motor (M ₁ ) is switched so as to increase the conveyance speed in the section, the document conveyance speed on the receiving side is always high, and the document (8) is conveyed while being pulled. The inconvenience of wrinkles is eliminated.

In the above embodiment, the conveyance speed at the time of discharging the document is not described, but the conveyance speed at the reverse return / discharge unit (6) for discharging to the discharge tray (17) is set to the conveyance stop unit ( It is better to make it faster than the transportation speed in 6).

In the above embodiment, the rotation of the belt conveying motor (M ₁ ) is shown, but the reversing motor (M ₂ ) may be controlled. 8 (a), (b) and FIG. 9 are a flow chart and a time chart for controlling the reversing motor (M ₂ ). Figure 8 (a), the flowchart in step _{(b) (S 100) ~} (S 121) is FIG. 5 (a), (b)
Since it is the same as steps (S ₁₇ ) to (S ₃₈ ) shown in FIG. In step ( _S122 ), it is determined whether or not the passage sensor (30) detects the trailing edge of the document (8). If the passage sensor (30) detects the trailing edge of the document (8), Proceed to steps (S ₁₂₃ ), (S ₁₂₄ ), and (S ₁₂₅ ), where the reverse speed of the reversing motor (M ₂ ) is set to V ₃ , the forward rotation of the belt transfer motor (M ₁ ) is turned off, and , Set a timer (T _P ) for timing the reverse rotation start of the belt transport motor (M ₁ ) (time t _{3 ′ in} FIG. 9). Also,
When passage sensor (30) has not detected the trailing edge of the document (8), a step (S _123), skipping the process at (S _124), (S _125), the process proceeds to step (S _126). In step (S ₁₂₆ ), it is determined whether or not the timer (T _P ) has ended. If it has ended, in step (S ₁₂₅ ), the belt transport motor (M ₁ ) is rotated in the same way as during normal rotation. If the timer (T _P ) has not expired by reverse-driving so that the conveyance speed (V ₁ ) is reached (time t _{4 ′ in} FIG. 9), skip the process of step (S ₁₂₇ ),
Proceed to step (S ₉ ). That is, in the embodiment described above, the original (8) conveyed at the conveying speed (V ₁ ) by the belt conveying motor (M ₁ ) at the conveying stop portion (5) is transferred to the reversing portion (6) by the V It receives at a faster transport speed than ₁ (V _2), as the way the conveying speed _{(V 3) (V 3 <} V 1), conveys conveyance stop unit is reversed at a conveying speed (V ₁₎ to (5).

In the above two embodiments, the speed control of the belt conveying motor (M ₁ ) or the reversing motor (M ₂ ) is performed. The method is to use a DC motor and change the voltage applied to the motor. Although there are methods such as controlling the speed by doing so, many specific methods for controlling the speed of the motor are already known, and since they are not directly related to the gist of the present invention, detailed description will be given here. Detailed description is omitted.

EFFECTS OF THE INVENTION As is clear from the above description, in the present invention, when both sides of a document are copied, when the document is conveyed from the conveyance stop section of the document conveying apparatus to the reverse return section after the exposure of the first side is completed. , Until the detection means detects that the document has passed the conveyance belt, the drive speed of the reversing roller is made faster than the drive speed of the conveyance belt, and when the detection means detects that the document has passed the conveyance belt, Since the drive speed is controlled so as to be slower than the drive speed of the conveyor belt, the inconvenience that the original is wrinkled due to the variation in the rotation speed of the motor and the slip between the conveyor belt and the reversing roller and the original is eliminated. Will be resolved. Further, by configuring the reversing portion of the document by the rollers, the paper can be reliably transported even when the transport belt is always driven at the maximum speed, and the document transport device can be operated with the maximum efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an automatic document feeder.
FIG. 2 shows a control circuit for controlling the operation of the automatic document feeder,
FIGS. 3 to 6 are flowcharts showing the processing procedure of the control of the automatic document feeder, FIG. 7 is a timing chart showing the operation timing of each part when performing double-sided copying, and FIG.
FIGS. 9A and 9B are flowcharts of another embodiment, and FIG. 9 is a timing chart of another embodiment. (2) ...... Automatic document feeder, (3) ...... Sheet feeding section, (5) ...... Conveyance stop section, (6) ...... Reverse return and discharge section, (15), (16), (22 ), (23) …… Drive roller,
(21) …… Conveyor belt, (30) …… Passage sensor, (53)
Belt drive motor drive circuit, (54) Reversal motor drive circuit, (M ₁ ) Belt transport motor, (M ₂ ) Reversal motor.

Claims (1)

[Claims] 1. A feeding original is fed to a feeding stop portion,
Set the first side of the original on the copier platen, and after the exposure of the first side is completed, the original is reversed by the reversing and returning section, the original is conveyed again to the conveyance stop section, and the second side of the original is set on the platen. In the document transporting device configured to perform the above, the document is transported from the transport stop unit to the reversing and returning unit by rotating in the first direction, and is also reversed by rotating in the second direction opposite to the first direction. A transport belt that transports the document transported from the return unit onto the platen, a first driving unit that drives the transport belt at a predetermined speed, and the document transported by the transport belt is reversed.
A reversing roller that conveys the reversing roller toward the conveying belt again; a first speed that is higher than a predetermined speed of the conveying belt by the first driving means, or a second speed that is lower than the predetermined speed. The second driving means for driving at one speed, the detecting means for detecting that the original has passed the conveyance belt, and the driving speed by the second driving means until the detecting means detects the passage of the original. A document conveying device comprising: a first speed; and a control unit that controls to change to a second speed after detecting passage of a document.